CONTROL METHOD OF WORK MACHINE, WORK MACHINE CONTROL PROGRAM, WORK MACHINE CONTROL SYSTEM, AND WORK MACHINE

Description

DESCRIPTION

CROSS-REFERENCE

This application claims foreign priority of JP2024-203713 filed November 22, 2024, the disclosure of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a control method of a work machine that comprises a prime mover for driving a hydraulic pump that discharges hydraulic oil, a work machine control program, a work machine control system, and a work machine.

BACKGROUND ART

As a related art, a work machine (work vehicle) including a prime mover composed of an electric motor is known (see, for example, Patent Document 1). The work machine according to the related art includes an accelerator operation portion (operation portion) that sets a rated rotational speed (rotational speed) of the prime mover, and normally rotates the prime mover at the rated rotational speed.

The work machine determines whether the load of the work machine is in a no-load state in which work or traveling is not performed by the prime mover, and when it is determined that the load of the work machine is in the no-load state, the work machine executes deceleration control of rotating the prime mover at a rotational speed lower than a rated rotational speed (sets an automatic idle function to be enabled). When the accelerator operation portion is operated while the deceleration control is being executed, it is determined that the work machine is not in the no-load state and cancels the deceleration control (sets an automatic idle function to be disabled).

PRIOR ART DOCUMENT

PATENT DOCUMENT

Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-197817

SUMMARY OF INVENTION

TECHNICAL PROBLEM

In the related art described above, for example, even when the operator operates the accelerator operation portion in advance to set the rated rotational speed for the next work while the deceleration control is being executed, the deceleration control is immediately canceled, and thus the action intended by the operator may not be performed.

The object of the present invention is to provide a control method of a work machine, a work machine control program, a work machine control system, and a work machine, that can easily perform an action intended by an operator.

SOLUTION TO PROBLEM

A control method of a work machine according to the present invention includes executing the deceleration control when the deceleration condition is satisfied and changing the rated rotational speed in accordance with an operation of the accelerator operation portion. In the deceleration control, the target rotational speed of the prime mover for driving the hydraulic pump that discharges hydraulic oil is switched from the rated rotational speed to a first specific rotational speed lower than the rated rotational speed. Here, in the control method, when there is an operation on the accelerator operation portion while the deceleration control is being executed, the deceleration control is continued.

A work machine control program according to one aspect of the present invention is a program for causing one or more processors to execute the control method of the work machine.

A work machine control system according to one aspect of the present invention includes a control processing portion and a setting processing portion. The control processing portion is capable of executing deceleration control when a deceleration condition is satisfied. In the deceleration control, the target rotational speed of the prime mover for driving the hydraulic pump that discharges hydraulic oil is switched from the rated rotational speed to a first specific rotational speed lower than the rated rotational speed. The setting processing portion changes the rated rotational speed in accordance with an operation of an accelerator operation portion. When there is an operation on the accelerator operation portion while the deceleration control is being executed, control processing portion continues the deceleration control.

A work machine according to one aspect of the present invention includes the work machine control system and a machine body.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a control method of a work machine, a work machine control program, a work machine control system, and a work machine, that can easily perform an action intended by an operator.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view illustrating an overall configuration of a work machine according to Embodiment 1.

FIG. 2 is a schematic view illustrating a hydraulic circuit and the like of the work machine according to Embodiment 1.

FIG. 3 is a timing chart illustrating an operation example of the work machine control system according to Embodiment 1.

FIG. 4 is a timing chart illustrating an operation example of the work machine control system according to Embodiment 1.

FIG. 5 is a flowchart illustrating an operation example of a work machine control system according to Embodiment 1.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention will be described below with reference to the accompanying drawings. The following embodiments are examples embodying the present invention and are not intended to limit the technical scope of the present invention.

Embodiment 1

1. Overall Configuration

As illustrated in FIG. 1, a work machine 3 according to the present embodiment has a machine body 30 including a traveling portion 31, a turning portion 32, and a work portion 33. As illustrated in FIG. 2, the work machine 3 further includes a work machine control system 1 (hereinafter also simply referred to as a "control system 1"). Further, as illustrated in FIG. 1 and FIG. 2, the machine body 30 is provided with a display device 2, an operation device 35, a main switch 36, an accelerator operation portion 37, and the like.

The "work machine" described in the present disclosure means a machine for any of various types of work, and examples thereof are work vehicles such as backhoes (including a hydraulic shovel and a mini shovel), a wheel loader, and a carrier. The work machine 3 includes the work portion 33 capable of performing one or more types of work. The work machine 3 is not limited to "vehicles" and may be, for example, a working vessel, a working projectile such as a drone or a multicopter, or the like. Furthermore, the work machine 3 is not limited to a construction machine (construction equipment), and may be, for example, an agricultural machine (agricultural equipment) such as a rice transplanter, a tractor, or a combine harvester. In the present embodiment, unless otherwise specified, an example will be described in which the work machine 3 is a riding type backhoe and is capable of performing work such as excavation work, ground leveling work, trench excavation work, or loading work.

In the present embodiment, a vertical direction in a usable state of the work machine 3 will be defined as an up-down direction D1 for convenience of description. Furthermore, in a non-turning state of the turning portion 32, a front-rear direction D2 and a right-left direction D3 will be defined with reference to directions seen from a user (operator) who gets in (a driving portion 321 of) the work machine 3. In other words, each of the directions used in the present embodiment is a direction that is defined with reference to the machine body 30 of the work machine 3. A movement direction of the machine body 30 during forward travel of the work machine 3 will be defined as "front", and a movement direction of the machine body 30 during reverse travel of the work machine 3 will be defined as "rear". Similarly, a direction in which a front end portion of the machine body 30 moves during a right turn of the work machine 3 will be defined as "right", and a direction in which the front end portion of the machine body 30 moves during a left turn of the work machine 3 will be defined as "left". Here, these directions are not intended to limit a use direction (a direction in use) of the work machine 3.

The work machine 3 is provided with a prime mover 40 (see FIG. 2) that serves as a power source. The prime mover 40 is, for example, a device that converts energy such as electricity, or heat of combustion or steam into mechanical force (power) and generates power for driving each part of the machine body 30. In the present embodiment, as an example, the prime mover 40 is an electric motor (electric machine). The prime mover 40 is driven by receiving electric power supply from a battery 38 (see FIG. 2). In this embodiment, the prime mover 40 is an AC motor and is driven by AC power (AC voltage) supplied from a drive circuit 39 constituted by an inverter circuit (see FIG. 2). The drive circuit 39 is electrically connected to the battery 38, and converts a DC voltage output from the battery 38 to an AC voltage and supply the AC voltage to the prime mover 40 to thereby drive the prime mover 40. That is, the work machine 3 includes the battery 38 and the drive circuit 39.

The output shaft of the prime mover 40 is connected to a hydraulic pump 41 (see FIG. 2) via a power transmission portion or the like, and the hydraulic pump 41 is driven by power from the prime mover 40. In the work machine 3, the hydraulic pump 41 is driven by the prime mover 40, and hydraulic oil is supplied from the hydraulic pump 41 to hydraulic actuators (including a hydraulic motor 43, a hydraulic cylinder 44, and the like) of the respective portions of the machine body 30, and thereby the machine body 30 is driven. That is, the prime mover 40 drives the hydraulic pump 41 to discharge hydraulic oil from the hydraulic pump 41, and supplies power (hydraulic oil) to each part of the machine body 30 of the work machine 3 to drive each part of the machine body 30.

The above work machine 3 is controlled, for example, when the user (operator) who is riding on the driving portion 321 of the machine body 30 operates an operation lever and the like of the operation device 35. That is, the power generated by the prime mover 40 is distributed to each part of the machine body 30 in accordance with the operation of the operator, so that the work machine 3 acts in accordance with the operation of the operator.

In the present embodiment, it is assumed that the work machine 3 is the riding-type backhoe as described above. Thus, the work portion 33 is driven according to the operation of the user (operator) who gets in the driving portion 321, and performs the work such as the excavation work. The driving portion 321, which the user gets in, is provided to the turning portion 32.

Here, the display device 2 and the operation device 35 are mounted to the driving portion 321 of the machine body 30. The user can operate the operation device 35 while looking at various types of information on the work machine 3 that are displayed on the display device 2. As an example, information on an actuation state of the work machine 3, such as a cooling water temperature and a hydraulic oil temperature, is displayed on a display screen of the display device 2. Accordingly, the user can check, on the display device 2, the information on the actuation state of the work machine 3 that is required for an operation of the operation device 35.

The traveling portion 31 has a traveling function, and is configured to be able to travel (and turn) on the ground. The traveling portion 31 has a pair of left and right crawlers 311 and a blade 312, for example. The traveling portion 31 further includes a hydraulic motor 43 (hydraulic actuator) for traveling and the like for driving the crawlers 311.

The turning portion 32 is positioned above the traveling portion 31, and is configured to be capable of swinging relative to the traveling portion 31 around a rotation axis along the up-down direction D1. The turning portion 32 includes a hydraulic motor (hydraulic actuator) for turning, and the like. The turning portion 32 includes the prime mover 40, the hydraulic pump 41, and the like in addition to the driving portion 321. Furthermore, a front end portion of the turning portion 32 includes a boom bracket 322 to which the work portion 33 is attached.

The work portion 33 is configured to be capable of performing one or more types of work. The work portion 33 is supported by the boom bracket 322 of the turning portion 32 and performs work. The work portion 33 has a bucket 331. The bucket 331 is one type of attachments (work implements) that is attached to the machine body 30 of the work machine 3 and is any implement selected from a plurality of types of attachments according to content of work. For example, the bucket 331 is detachably attached to the machine body 30, and is replaced according to the content of work. In addition to the bucket 331, attachments for the work machine 3 include, for example, various implements such as a breaker, an auger, a crusher, a fork, a fork claw, a steel frame cutter, an asphalt milling machine, a mower, a ripper, a mulcher, a tilt rotator, a tamper, and the like.

The work portion 33 further has a boom 332, an arm 333, and a hydraulic actuator (including a hydraulic cylinder 44, a hydraulic motor, and the like), and the like. The bucket 331 is attached to a tip end of the arm 333.

The boom 332 is rotatably supported by the boom bracket 322 of the turning portion 32. Specifically, the boom 332 is supported by the boom bracket 322 so as to be rotatable about a rotation axis along the horizontal direction. The boom 332 has a shape that extends upward from a base end portion supported by the boom bracket 322. The arm 333 is coupled to a tip end of the boom 332. The arm 333 is supported by the boom 332 so as to be rotatable around a rotation axis along the horizontal direction.

The work portion 33 moves by receiving power from the prime mover 40 serving as a power source. Specifically, the hydraulic pump 41 is driven by the prime mover 40, and hydraulic oil is supplied from the hydraulic pump 41 to the hydraulic actuator (hydraulic cylinder 44, etc.) of the work portion 33, thereby causing each portion of the work portion 33 (bucket 331, boom 332, and arm 333) to move.

In particular, in this embodiment, the work portion 33 has a multi-joint structure in which the boom 332 and the arm 333 are configured to be individually rotatable. That is, each of the boom 332 and the arm 333 is rotated around the rotation axis extending in the horizontal direction, so that, for example, the multi-joint work portion 33 including the boom 332 and the arm 333 can be extended or folded as a whole.

Each of the traveling portion 31 and the turning portion 32 also moves by receiving power from the prime mover 40 serving as a power source, similarly to the work portion 33. That is, hydraulic oil is supplied from the hydraulic pump 41 to the hydraulic motor 43 of the traveling portion 31, the hydraulic motor of the turning portion 32, and the like to cause the turning portion 32 and the traveling portion 31 to move.

The actuators (in the present embodiment, hydraulic actuators including the hydraulic motor 43, the hydraulic cylinder 44, and the like) provided in respective portions of the machine body 30 are activated in response to the operation of the operation device 35. That is, the work machine 3 according to the present embodiment is provided with actuators that are actuated in response to the operation of the operation device 35. Thus, the work machine 3 performs various actions such as forward/backward traveling by the traveling portion 31, turning by the turning portion 32, digging work by the work portion 33, and the like in response to the operation of the operation device 35 by the user (operator).

FIG. 2 schematically illustrates a hydraulic circuit and an electrical circuit (an electrical connection relationship) of the work machine 3 according to the present embodiment. In FIG. 2, solid lines represent high-pressure oil paths (for hydraulic oil), dotted lines represent low-pressure oil paths (for pilot oil), and dashed-dotted line arrows represent electric signal paths. A thick line (solid line) between the prime mover 40 and the hydraulic pump 41 indicates physical coupling between (the output shaft of) the prime mover 40 and the hydraulic pump 41.

As illustrated in FIG. 2, the work machine 3 includes a pilot pump 42, a remote control valve 45, a control valve 461, a cutoff switch 462, a cutoff lever 463, a temperature sensor 47, a direction switching valve (control valve) 48, a hydraulic oil tank 49, a main switch 36, an accelerator operation portion 37, and the like, in addition to the hydraulic pump 41, the hydraulic motor 43 (not illustrated in FIG. 2), the hydraulic cylinder 44, the prime mover 40, the battery 38, and the drive circuit 39.

The hydraulic oil from the hydraulic pump 41 driven by the prime mover 40 is supplied to the hydraulic motor 43 of the traveling portion 31, the hydraulic motor of the turning portion 32, the hydraulic cylinders 44 of the work portion 33, and the like. Thus, the hydraulic actuators such as the hydraulic motor 43 and the hydraulic cylinder 44 are driven.

The drive circuit 39 drives the prime mover 40 at an arbitrary rotational speed. That is, by controlling the rotational speed of the prime mover 40, the drive circuit 39 can control the rotational speed of the hydraulic pump 41 driven by the prime mover 40 and change the amount of hydraulic oil discharged from the hydraulic pump 41. Thus, in the present embodiment, the flow rate of the hydraulic oil supplied from the hydraulic pump 41 is not fixed, and can be changed (variable) by a proper measure. The drive circuit 39 may, without steps, continuously vary the rotational speed of the prime mover 40, or may vary the rotational speed at steps (for example, 2, 5, or 10 steps).

Each of the hydraulic actuators, such as the hydraulic motor 43 and the hydraulic cylinder 44, includes a pilot-type direction switching valve 48 capable of switching a direction and flow rate of the hydraulic oil from the hydraulic pump 41. The direction switching valve 48 is driven when the pilot oil serving as an input instruction is supplied from the pilot pump 42.

Here, the remote control valve 45 is provided, for example, in a supply path of the pilot oil to the direction switching valve 48 that corresponds to the hydraulic cylinder 44 of the work portion 33. The remote control valve 45 outputs a work operation instruction of the work portion 33 according to the operation of the operation device 35 (operation lever). The work operation instruction instructs the work portion 33 to perform an extending action, a retracting action, or the like. Further, the flow rate of the pilot oil supplied from the pilot pump 42 to the remote control valve 45 is adjustable by the control valve 461.

The control valve 461 is composed of an electromagnetic-type control valve (electromagnetic valve), and is inserted between the remote control valve 45 and the pilot pump 42. The control valve 461 is connected to a power supply via the cutoff switch 462 and is actuated in response to a supply current from the power supply. The control valve 461 is here assumed to be an (electromagnetic-type) proportional control valve, but the present invention is not limited thereto and the control valve 461 may be a switchable open/close valve that opens/closes the flow path, for example.

The control valve 461 opens the flow path of the pilot oil in an energized state, that is, in a state where the current as a control signal is supplied, and closes the flow path of the pilot oil in a de-energized state, that is, in a state where the current as the control signal is shut off. Thus, shutting off the supply current (control signal) to the control valve 461 disables the hydraulic actuator (such as hydraulic cylinder 44) that corresponds to the remote control valve 45, thus forcibly stopping the hydraulic actuator regardless of the operation of the operation device 35.

Similarly, a remote control valve is also provided in a supply path of the pilot oil to the direction switching valve corresponding to the hydraulic motor 43 of the traveling portion 31. This remote control valve outputs a traveling operation instruction of the traveling portion 31 according to the operation of the operation device 35 (operation lever). The traveling operation instruction instructs a traveling action (for example, forward traveling or backward traveling) of the traveling portion 31. Further, a remote control valve is also provided in a supply path of the pilot oil to the direction switching valve corresponding to the hydraulic motor of the turning portion 32. This remote control valve outputs a turning operation instruction of the turning portion 32 according to the operation of the operation device 35 (operation lever). The turning operation instruction instructs a turning action (left turn, right turn, etc.) of the turning portion 32. The control valve 461 is also inserted between each of these remote control valves and the pilot pump 42.

The cutoff switch 462 is linked to the cutoff lever 463. The cutoff lever 463 is arranged in the driving portion 321 of the machine body 30 and accepts an operation input by the user (operator). In the present embodiment, as an example, the cutoff lever 463 can be operated in the up-down direction D1. When the cutoff lever 463 is located at an "up position" that is an upper end position within a movable range, the cutoff switch 462 is "off". When the cutoff lever 463 is located at a "down position" that is a lower end position within the movable range, the cutoff switch 462 is "on". The cutoff switch 462 is connected to the control system 1, and on/off of the cutoff switch 462, that is, the operation state of the cutoff lever 463 is monitored by the control system 1.

Therefore, when the cutoff lever 463 is located at the "down position", the control valve 461 is in the energized state and the hydraulic actuator (such as hydraulic cylinder 44) is driven by the operation of the operation device 35. In contrast, when the cutoff lever 463 is located at the "up position", the control valve 461 is in the de-energized state and the hydraulic actuator is forcibly stopped regardless of the operation of the operation device 35. Accordingly, in order to drive the hydraulic actuators (hydraulic cylinder 44 and the like), the user (operator) needs to operate the cutoff lever 463 to the "down position".

Furthermore, each of the turning portion 32 and the traveling portion 31 is also actuated when the hydraulic oil is supplied from the hydraulic pump 41 to the hydraulic actuator (the hydraulic motor 43, and the like). Therefore, when the cutoff lever 463 is located at the "up position", neither the turning portion 32 nor the traveling portion 31 is actuated. That is, when the cutoff lever 463 is located at the "up position", all of the work portion 33, the turning portion 32, and the traveling portion 31 are forcibly brought into an undrivable state.

In the present embodiment, a state of the cutoff lever 463 in which the cutoff lever 463 is located at the "up position", that is, a state in which the work machine 3 cannot be operated is defined as a "locked state". Meanwhile, a state of the cutoff lever 463 in which the cutoff lever 463 is located at the "down position", that is, a state in which the work machine 3 can be operated is defined as an "unlocked state".

In short, when the cutoff switch 462 is off, the cutoff switch 462 is in the "locked state" in which the action of the work machine 3 is limited (including prohibited), and when the cutoff switch 462 is on, the cutoff switch 462 is in the "unlocked state" in which the action of the work machine 3 is not limited. When the cutoff lever 463 is located at the "up position" and the cutoff switch 462 is in the locked state (off), the action of the work machine 3 is forcibly limited regardless of the operation of the operation device 35. The cutoff lever 463 is a lever that is operated to lock the action of the work machine 3 as described above, and is synonymous with a gate lock lever.

The operation device 35 is arranged in the driving portion 321 of the machine body 30 and is a user interface for accepting an operation input by the user (operator). The operation device 35 includes, for example, an operation lever, and controls the remote control valve 45 in accordance with an operation amount of the operation lever. In this manner, the operator can operate the operation device 35 to activate the remote control valve 45, instruct the direction and flow rate of the hydraulic oil from the hydraulic pump 41, and move the work machine 3.

The temperature sensor 47 detects the temperature of the hydraulic oil (hydraulic oil temperature) discharged from the hydraulic pump 41. Specifically, in the present embodiment, the temperature sensor 47 is provided in the hydraulic oil tank 49 that stores hydraulic oil, and detects the temperature of the hydraulic oil stored in the hydraulic oil tank 49. The hydraulic pump 41 pumps up and discharges the hydraulic oil stored in the hydraulic oil tank 49, and thus the temperature sensor 47 detects the temperature of the hydraulic oil discharged from the hydraulic pump 41. The temperature sensor 47 is connected to the control system 1, and temperature detection signal indicative of the temperature (hydraulic oil temperature) detected by the temperature sensor 47 is input to the control system 1.

The temperature sensor 47 is an example of a detection portion that detects a state quantity of the hydraulic oil. The term "state quantity" in the present disclosure is a physical quantity representing a state of an object (here, hydraulic oil), means a value determined in accordance with the state, and includes, for example, viscosity, pressure, volume, density, oil type, or the like in addition to temperature. In the present embodiment, the temperature sensor 47 detects, as the state quantity of the hydraulic oil, the temperature of the hydraulic oil discharged from the hydraulic pump 41.

The main switch 36 is arranged in the driving portion 321 of the machine body 30 and is operated by the user (operator) at a start of the work machine 3. While the main switch 36 is off, the machine body 30 (including the traveling portion 31, the turning portion 32, and work portion 33) is not in a state in which the machine body 30 is moved according to the operation of the operation device 35. Only when the main switch 36 is on, the machine body 30 is in a state in which the machine body 30 is moved according to the operation of the operation device 35. When the main switch 36 is turned on, the energization of the display device 2 and the like is also started. In the present embodiment, as an example, the main switch 36 is linked to a key cylinder, and is turned on when a start operation of the prime mover 40 is performed by using a key.

The accelerator operation portion 37 is arranged in the driving portion 321 of the machine body 30 and is operated by the user (operator) at a start of the work machine 3. The accelerator operation portion 37 is a device that is operated to set the rated rotational speed of the prime mover 40, and is, for example, an accelerator dial, an accelerator lever, an accelerator pedal, or the like. The accelerator operation portion 37 is connected to the control system 1, and an operation signal generated by an operation of the accelerator operation portion 37 is input to the control system 1. In the present embodiment, as an example, the accelerator operation portion 37 is a dial-type operation portion that is rotationally operated, and sets the rated rotational speed of the prime mover 40 in accordance with the rotational position of the accelerator operation portion 37.

The control system 1 is mainly composed of a computer system that has one or more processors such as a central processing portion (CPU) and one or more memories such as a read only memory (ROM) and a random access memory (RAM), and executes various types of processing (information processing). In the present embodiment, the control system 1 is an integrated controller that controls the entire work machine 3, and composed of an electronic control unit (ECU), for example. However, the control system 1 may be provided separate from the integrated controller, and may be mainly composed of one or more processors. The control system 1 will be specifically described in "[2] Configuration of Control System".

The display device 2 is arranged in the driving portion 321 of the machine body 30, and is a user interface that accepts an operation input by the user (operator) and outputs various types of information to the user. The display device 2 accepts any of various operations by the user by outputting an electrical signal that corresponds to the operation of the user. In this way, the user (operator) can visually recognize the display screen displayed on the display device 2, and can operate the display device 2 as necessary.

As illustrated in FIG. 2, the display device 2 includes a control portion 21, an operation portion 22, and a display portion 23. The display device 2 is configured to be communicable with the control system 1 and can exchange data with the control system 1. In the present embodiment, as an example, the display device 2 is a dedicated device used for the work machine 3.

The control portion 21 controls the display device 2 according to the data from the control system 1. Specifically, the control portion 21 outputs an electrical signal that corresponds to the operation of the user accepted by the operation portion 22, and displays the display screen that is generated by the control system 1 on the display portion 23.

The operation portion 22 is a user interface for accepting the operation input by the user (operator) to the display screen that is displayed on the display portion 23. The operation portion 22 accepts various operations by the user by outputting an electrical signal that corresponds to the operation of the user, for example.

The display portion 23 is a user interface for presenting information to the user (operator) such as a liquid-crystal display and an organic EL display for displaying various types of information. The display portion 23 presents various types of information to the user by means of display.

In addition to the above-described configuration, the machine body 30 further includes an actuation device, a communication terminal, and the like. The actuation device is a device for supplying power to the attachment of the work portion 33, and is composed of a device (mechanism) such as a power take-off (PTO) for taking out power from the prime mover 40 as power for driving the attachment composed of a hydraulic instrument. Further, the machine body 30 is provided with various sensors (including cameras) for detecting a detection target in a monitoring area around the work machine 3, such as a camera for capturing an image around the machine body 30.

2. Configuration of Control System

Subsequently, a configuration of the control system 1 according to the present embodiment will be explained with reference to FIG. 2. The control system 1 controls each portion of the machine body 30 (including the traveling portion 31, the turning portion 32, and the work portion 33). In the present embodiment, the control system 1 is a component of the work machine 3 and constitutes the work machine 3 together with the machine body 30 and the like. In other words, the work machine 3 according to the present embodiment includes at least the control system 1 and the machine body 30.

As illustrated in FIG. 2, the control system 1 includes an acquisition processing portion 11, a control processing portion 12, and a setting processing portion 13. Since in the present embodiment, as an example, the control system 1 is mainly composed of the computer system that has one or more processors, when the one or more processors execute a work machine control program, the plurality of functional portions (the acquisition processing portion 11 and the like) are provided. The plurality of functional portions included in the control system 1 may be separately provided in a plurality of housings or may be provided in a single housing.

The control system 1 is configured to be communicable with the device that is provided to each part of the machine body 30. That is, at least the drive circuit 39, the prime mover 40, the main switch 36, the accelerator operation portion 37, the temperature sensor 47, the display device 2, the cutoff switch 462, and the like are connected to the control system 1. Thus, the control system 1 can control the drive circuit 39, the display device 2, and the like, and can acquire the rotational speed of the prime mover 40, the operation state of the accelerator operation portion 37, the detection result (hydraulic oil temperature) of the temperature sensor 47, and the like. The control system 1 may directly exchange various types of information (data) with each device, or may indirectly exchange the information (data) with the device via a relay or the like. As an example, the control system 1 and the device provided in each part of the machine body 30 can communicate with each other by the communication method such as a Controller Area Network (CAN).

The acquisition processing portion 11 executes acquisition processing of acquiring the rotational speed of the prime mover 40, the operation state of the accelerator operation portion 37, the detection result (hydraulic oil temperature) of the temperature sensor 47, and the like. In the present embodiment, the acquisition processing portion 11 regularly or irregularly acquires the rotational speed of the prime mover 40, the operation state of the accelerator operation portion 37, the detection result (hydraulic oil temperature) of the temperature sensor 47, and the like.

The acquisition processing portion 11 can regularly or irregularly acquire information such as the ON/OFF states of the main switch 36 and the cutoff switch 462 by the acquisition processing. Here, the acquisition processing portion 11 can also acquire outputs (sensor signals) of a remaining fuel amount sensor, a cooling water temperature sensor, and a hydraulic oil temperature sensor. The acquisition processing portion 11 may acquire various types of data directly from various sensors and the like (including cameras), or indirectly through an electronic control unit or the like. The data acquired by the acquisition processing portion 11 is stored in a memory or the like, for example.

The control processing portion 12 adjusts the rotational speed of the prime mover 40 by controlling the drive circuit 39. The control processing portion 12 sets a target rotational speed of the prime mover 40, and controls the rotational speed of the prime mover 40 by the drive circuit 39 such that the actual rotational speed of the prime mover 40 (actual rotational speed) acquired from the prime mover 40 by the acquisition processing portion 11 approaches the target rotational speed. Specifically, when the actual rotational speed of the prime mover 40 is lower than the target rotational speed, the control processing portion 12 controls the drive circuit 39 to increase the rotational speed of the prime mover 40 (to increase the speed). Conversely, when the actual rotational speed of the prime mover 40 is higher than the target rotational speed, the control processing portion 12 controls the drive circuit 39 to decrease the rotational speed of the prime mover 40 (to decrease the speed).

The setting processing portion 13 executes setting processing of setting the rated rotational speed of the prime mover 40. The setting processing portion 13 changes the rated rotational speed in accordance with the operation of the accelerator operation portion 37. That is, the rated rotational speed of the prime mover 40 is not constant, and can be arbitrarily set by the operation of the accelerator operation portion 37 by the operator. Thus, for example, the rated rotational speed can be set to a rated rotational speed corresponding to the action of the work machine 3, such as setting the rated rotational speed to a higher value when performing heavy-load work and setting the rated rotational speed to a lower value when performing light-load work.

More specifically, the setting processing portion 13 changes the rated rotational speed of the prime mover 40 to a rotational speed lower or higher than the current set value in accordance with the operation state of the accelerator operation portion 37 acquired by the acquisition processing portion 11. In the present embodiment, as an example, the accelerator operation portion 37 is a dial-type operation portion that is rotationally operated, and thus the setting processing portion 13 sets the rated rotational speed of the prime mover 40 to a value (rotational speed) corresponding to the rotational position of the accelerator operation portion 37. The setting processing portion 13 may, without steps, continuously vary the rated rotational speed of the prime mover 40, or may vary the rotational speed at steps (for example, 2, 5, or 10 steps).

The control processing portion 12 can execute, as control for automatically changing the target rotational speed of the prime mover 40, deceleration (decelerator) control, stop control, deceleration cancellation control, and stop cancellation control.

The deceleration control is control for switching the target rotational speed of the prime mover 40 from the rated rotational speed to a first specific rotational speed lower than the rated rotational speed. That is, the control processing portion 12 has an automatic deceleration function that automatically decreases the rotational speed of the prime mover 40. For example, when a state where the work portion 33 or the like is not actuated and the output of the prime mover 40 is not required continues for a certain period of time, the control processing portion 12 outputs a control signal for decreasing the target rotational speed to the drive circuit 39 and executes the deceleration control for decreasing the rotational speed of the prime mover 40.

The deceleration cancellation control is control for canceling the deceleration control, and is specifically control for switching the target rotational speed of the prime mover 40 from the first specific rotational speed to a first return rotational speed higher than the first specific rotational speed.

That is, when the automatic deceleration function is activated, the control processing portion 12 switches the rotational speed of the prime mover 40 to a low idle rotational speed (first specific rotational speed) lower than the rated rotational speed. When the automatic deceleration function is canceled, the control processing portion 12 switches the rotational speed of the prime mover 40 to a high idle rotational speed (first return rotational speed) higher than the first specific rotational speed. That is, the control processing portion 12 can automatically decrease the rotational speed of the prime mover 40 by the deceleration control and automatically increase the rotational speed of the prime mover 40 by the deceleration cancellation control. Thus, by suppressing the rotational speed of the prime mover 40 to be low as necessary, it is possible to prevent the generation of a time lag due to the restart of the prime mover 40 while reducing the noise and vibration generated in the prime mover 40 and suppressing the energy (electric power) consumption in the prime mover 40.

The stop control is control for stopping the prime mover 40 and setting the target rotational speed to zero (0). That is, the control processing portion 12 has an automatic stop function that automatically decreases the rotational speed of the prime mover 40 to zero (that is, stops the prime mover 40). For example, when a state where the work portion 33 or the like is not actuated and the output of the prime mover 40 is not required continues for a certain period of time, the control processing portion 12 outputs a control signal for stopping the action to the drive circuit 39 and executes the stop control for sopping the prime mover 40 in a restartable manner.

The stop cancellation control is control for canceling the stop control, and is specifically control for starting the prime mover 40 stopped by the stop control and setting the target rotational speed of the prime mover 40 to the second specific rotational speed.

That is, when the automatic stop function is activated, the control processing portion 12 temporarily stops the prime mover 40 (that is, in a manner in which the prime mover 40 can be restarted by the control processing portion 12) to set the rotational speed of the prime mover 40 to zero. On the other hand, when the automatic stop function is canceled, the control processing portion 12 restarts the prime mover 40 and increases the rotational speed of the prime mover 40 to the second specific rotational speed. That is, the control processing portion 12 can automatically stop the prime mover 40 by the stop control and automatically start (restart) the prime mover 40 by the stop cancellation control. Thus, by temporarily stopping the prime mover 40 as necessary, it is possible to further reduce the noise and vibration generated in the prime mover 40 and further suppress the energy (electric power) consumption in the prime mover 40.

Each of the automatic deceleration function and the automatic stop function can be switched between enabled and disabled. The enabling/disabling of the automatic deceleration function and the automatic stop function is switched by, for example, an operation of the user (operator) on an automatic deceleration switch and an automatic stop switch provided in the driving portion 321. That is, when the automatic deceleration switch is on, the automatic deceleration function is enabled, and when the automatic deceleration switch is off, the automatic deceleration function is disabled. When the automatic stop switch is on, the automatic stop function is enabled, and when the automatic stop switch is off, the automatic stop function is disabled.

3. Control Method of Work Machine

Hereinafter, with reference to FIG. 3 to FIG. 5, one example of a control method of the work machine 3 (hereinafter, simply referred to as "control method") mainly executed by the control system 1 will be explained.

The control method according to the present embodiment is executed by the control system 1 that is mainly composed of the computer system, and thus, in other words, is embodied by the work machine control program (hereinafter simply referred to as a "control program"). That is, the control program according to the present embodiment is a computer program for causing one or more processors to perform processes related to the control method. Such a control program may be executed in cooperation by the control system 1 and the display device 2, for example.

When a specific start operation set in advance for executing the control program is performed, the control system 1 executes the following various types of processing related to the control method. A start operation is, for example, the start operation for the prime mover 40 of the work machine 3, that is, an ON operation of the main switch 36. In contrast, when a specific end operation set in advance is performed, the control system 1 ends the following various types of processing related to the control method. An end operation is, for example, the stop operation for the prime mover 40 of the work machine 3, that is, an OFF operation of the main switch 36.

3.1. Deceleration Control and Deceleration Cancellation Control

Here, first, the control method according to the present embodiment, that is, the operations related to the deceleration control and the deceleration cancellation control among the operations of the control system 1 according to the present embodiment will be described.

When a predetermined deceleration condition is satisfied in a state where the automatic deceleration function is enabled (that is, the automatic deceleration switch is on), the control processing portion 12 of the control system 1 executes deceleration control of switching the target rotational speed of the prime mover 40 from the rated rotational speed to a first specific rotational speed lower than the rated rotational speed. The deceleration condition is a condition for executing the deceleration control, and the control processing portion 12 decreases the target rotational speed of the prime mover 40 when the deceleration condition is satisfied.

The rated rotational speed is changed by the setting processing portion 13 in accordance with the operation of the accelerator operation portion 37. That is, the rotational speed (rated rotational speed) of the prime mover 40 before the deceleration control is performed is not constant, and can be arbitrarily set by an operation of the operator. Thus, for example, the rated rotational speed can be set to a rated rotational speed corresponding to the action of the work machine 3, such as setting the rated rotational speed to a higher value when performing heavy-load work and setting the rated rotational speed to a lower value when performing light-load work.

In the present embodiment, the deceleration condition includes a condition related to an operation of the work machine 3. That is, a condition related to an operation of the work machine 3 by the operator (also referred to as an "operation-related condition") is included in the deceleration condition. Therefore, the operation status of the work machine 3 by the operator is reflected in whether the deceleration condition is satisfied, that is, whether the deceleration control is performed. Therefore, when the operation status of the work machine 3 by the operator satisfies the deceleration condition in a situation where, for example, the work portion 33 or the like is not actuated and the output of the prime mover 40 is not required, it is possible to perform the deceleration control of decreasing the target rotational speed of the prime mover 40. That is, whether or not to perform the deceleration control can be determined by the operator's intention.

The condition related to the operation of the work machine 3 (operation-related condition) included in the deceleration condition includes that the operation device 35 of the work machine 3 has not been operated for a specified time. Specifically, when the operation device 35 includes an operation lever, a state in which the user (operator) does not operate the operation lever and the operation lever is in the neutral position is defined as the state in which the operation device 35 is not operated. In a state where the operation device 35 is not operated, the work machine 3 is in a standby state, and the respective portions (the traveling portion 31, the turning portion 32, and the work portion 33) of the machine body 30 do not act.

Therefore, in a situation where the output of the prime mover 40 is not required, such as when the standby state of the work machine 3 continues for a specified time or more, the deceleration condition is satisfied, and the deceleration control can be performed. That is, since the needs to immediately move the work machine 3 is low when a situation in which the output of the prime mover 40 is not required continues for a specified time or more, the noise and vibration generated in the prime mover 40 can be reduced and the energy (electric power) consumption in the prime mover 40 can be suppressed by performing the deceleration control in such a situation.

In other words, the deceleration condition includes that the load applied to the work machine 3 is in a light load state. The term "light load state" described here means a state in which the magnitude of the load related to the traveling action (of the traveling portion 31) and/or the work action (of the work portion 33) of the work machine 3 is less than a predetermined value, and also includes a no-load state in which the load related to the traveling action and/or the work action of the work machine 3 is substantially 0 (zero). That is, the load applied to the work machine 3 is in the light load state at least in the standby state of the work machine 3.

In the present embodiment, the control processing portion 12 has a light load determination function of determining whether the load applied to the work machine 3 is in a light load state. The deceleration condition includes that the load applied to the work machine 3 is determined to be in a light load state by the light load determination function of the control processing portion 12. Since the deceleration condition includes that the load of the work machine 3 is in the light load state as described above, when the needs to immediately move the work machine 3 is low, it is possible to reduce the noise and vibration generated in the prime mover 40 and suppress the energy (electric power) consumption in the prime mover 40 by the deceleration control.

In the present embodiment, the control processing portion 12 particularly determines whether the load of the work machine 3 is in a light load state from the operation status of traveling and/or work of the work machine 3. That is, the light load determination function of the control processing portion 12 does not directly detect the magnitude of the load applied to the work machine 3, but determines whether the load of the work machine 3 is in the light load state on the basis of the operation status of the traveling and/or work of the work machine 3. Specifically, the light load determination function determines whether the load of traveling and/or work of the work machine 3 is in a light load state based on the operation status of the operation device 35 related to the traveling action (of the traveling portion 31) and/or the work action (of the work portion 33) of the work machine 3. When the operation device 35 is not operated and the work machine 3 is in a standby state, it is determined that the load of the work machine 3 is in a light load state. With this configuration, the configuration for detection can be simplified as compared with a case where the magnitude of the load applied to the work machine 3 is directly detected.

Then, in a case where the specific condition is satisfied, when an operation of the traveling and/or work of the work machine 3 is performed, it is determined that the load of the work machine 3 is not in the light load state. That is, in a case where the specific condition is satisfied, when an operation of the operation device 35 related to the traveling action (of the traveling portion 31) and/or the work action (of the work portion 33) of the work machine 3 is performed, the control processing portion 12 determines that the load of the work machine 3 is not in the light load state. Thus, when the work machine 3 is not in the standby state, it is possible to avoid determination that the deceleration condition is satisfied and execution of the deceleration control.

In the present embodiment, the specific condition includes that the cutoff lever 463 is in the unlocked state. That is, when the cutoff lever 463 is in the "down position", the specific condition is satisfied, and when an operation of the traveling and/or work of the work machine 3 is performed in this state, it is determined that the load of the work machine 3 is not in the light load state. With this configuration, when the cutoff lever 463 is in the "up position" (that is, in the locked state), it can be determined that the load of the work machine 3 is in the light load state even when an operation of the traveling and/or work of the work machine 3 is performed.

The deceleration condition also includes a condition that a state where the accelerator operation portion 37 is not operated continues for a specified time or more. That is, in a case in which a state where none of the operation device 35 for operating the traveling portion 31, the work portion 33, and the like of the machine body 30 and the accelerator operation portion 37 is operated continues for a specified time (for example, about 3 seconds) or more while the automatic deceleration function is enabled, it is determined that the deceleration condition is satisfied and the control processing portion 12 executes the deceleration control. Conversely, even in a case in which a state where the operation device 35 for operating the traveling portion 31, the work portion 33, and the like of the machine body 30 is not operated continues for a specified time or more, the deceleration control is not performed because the deceleration condition is not satisfied when the accelerator operation portion 37 is operated within the latest specified time.

In short, the deceleration condition includes that the three items, that is, the non-operation state of the operation device 35 for operating the traveling portion 31, the non-operation state of the operation device 35 for operating the work portion 33, and the non-operation state of the accelerator operation portion 37 for changing the rated rotational speed, continue for a specified time (for example, about 3 seconds) or more. The deceleration condition is satisfied only when all of these three items continue for a specified time or more, and the control processing portion 12 decreases the target rotational speed of the prime mover 40 from the rated rotational speed to a low idle rotational speed (first specific rotational speed) lower than the rated rotational speed. When there is an item that has not continued for the specified time or more among the three items, the deceleration condition is not satisfied, and the control processing portion 12 does not execute the deceleration control and sets the target rotational speed of the prime mover 40 to the rated rotational speed.

Particularly, when the accelerator operation portion 37 is operated, the control processing portion 12 sets, as the target rotational speed of the prime mover 40, the rated rotational speed that has been changed (modified) by the operation of the accelerator operation portion 37. Therefore, the deceleration control is not executed when the accelerator operation portion 37 is operated, and the target rotational speed of the prime mover 40 is changed in real time. The fact that the accelerator operation portion 37 is operated means that the operator intends to change the rotational speed of the prime mover 40, such as increasing or decreasing the rotational speed of the prime mover 40. Therefore, the rotational speed of the prime mover 40 is immediately changed, and thus, an action in accordance with the intention of the operator can be performed. That is, since the deceleration condition includes a condition that a state where the accelerator operation portion 37 is not operated continues for a specified time or more, an action according to the intention of the operator is realized.

When a predetermined deceleration cancellation condition is satisfied while the deceleration control is being executed, the control processing portion 12 of the control system 1 executes deceleration cancellation control of switching the target rotational speed of the prime mover 40 from the first specific rotational speed to a first return rotational speed higher than the first specific rotational speed. The deceleration cancellation condition is a condition for executing the deceleration cancellation control, and the control processing portion 12 increases the target rotational speed of the prime mover 40 when the deceleration cancellation condition is satisfied.

In the present embodiment, the deceleration cancellation condition includes a condition related to an operation of the work machine 3. That is, a condition related to an operation of the work machine 3 by the operator (operation-related condition) is also included in the deceleration cancellation condition. Therefore, the operation status of the work machine 3 by the operator is reflected in whether the deceleration cancellation condition is satisfied, that is, whether the deceleration cancellation control is performed. Therefore, in a state where the target rotational speed of the prime mover 40 is suppressed to the low idle rotational speed (first specific rotational speed) by the deceleration control, for example, in a situation where the output of the prime mover 40 is required to actuate the work portion 33 or the like, when the deceleration cancellation condition is satisfied depending on the operation status of the work machine 3 by the operator at that time, the deceleration cancellation control of increasing the target rotational speed of the prime mover 40 can be performed. That is, whether or not to perform the deceleration cancellation control can be determined by the operator's intention.

The condition related to the operation of the work machine 3 (operation-related condition) included in the deceleration cancellation condition includes that the operation device 35 of the work machine 3 is operated. Specifically, when the operation device 35 includes an operation lever, the deceleration cancellation condition includes that the operation lever is operated to a position other than the neutral position. Therefore, when the output of the prime mover 40 is required in a state where the target rotational speed of the prime mover 40 is suppressed to the low idle rotational speed (first specific rotational speed) by the deceleration control, the deceleration cancellation condition is satisfied, and the deceleration cancellation control can be performed.

The deceleration cancellation condition does not include that the accelerator operation portion 37 is operated. In other words, even when the accelerator operation portion 37 is operated while the deceleration control is being executed, the control processing portion 12 continues the deceleration control without executing the deceleration cancellation control. That is, when any one of the operation devices 35 for operating the traveling portion 31, the work portion 33, and the like of the machine body 30 is operated during the deceleration control, the control processing portion 12 increases the target rotational speed of the prime mover 40 from the low idle rotational speed (first specific rotational speed) to the high idle rotational speed (first return rotational speed) higher than the first specific rotational speed. On the other hand, even when the accelerator operation portion 37 is operated during the deceleration control, the control processing portion 12 maintains the target rotational speed of the prime mover 40 at the low idle rotational speed (first specific rotational speed).

That is, even when the accelerator operation portion 37 is operated while the deceleration control is being executed since it is determined that the load of the work machine 3 is in the light load state, the control processing portion 12 determines that the load of the work machine 3 is still in the light load state by the light load determination function and continues the deceleration control. Thus, for example, when the operator operates the accelerator operation portion 37 in advance to set the rated rotational speed for the next work while the deceleration control is being executed, it is assumed that the light load state continues, and the deceleration control is continuously executed.

The deceleration cancellation condition also includes disabling the automatic deceleration function. That is, when the automatic deceleration switch is turned off and the automatic deceleration function is disabled after the deceleration control is performed in a state where the automatic deceleration switch is on and the automatic deceleration function is enabled, the deceleration cancellation condition is satisfied and the control processing portion 12 switches the target rotational speed of the prime mover 40 from the first specific rotational speed to the first return rotational speed.

In the present embodiment, the first return rotational speed is the same as the rated rotational speed. That is, the target rotational speed of the prime mover 40 is switched from the rated rotational speed to the first specific rotational speed by the deceleration control, and is switched from the first specific rotational speed to the rated rotational speed (first return rotational speed) by the deceleration cancellation control. Therefore, in a state where the prime mover 40 is driven at the rated rotational speed, the rotational speed of the prime mover 40 is decreased by the deceleration control and is returned by the deceleration cancellation control.

The setting processing portion 13 changes the rated rotational speed, which is the first return rotational speed, in accordance with the operation of the accelerator operation portion 37. Specifically, when the accelerator operation portion 37 is operated while the deceleration control is being executed, the setting processing portion 13 changes the rated rotational speed in accordance with the operation of the accelerator operation portion 37. However, since the target rotational speed of the prime mover 40 is suppressed not to the rated rotational speed but to the first specific rotational speed while the deceleration control is being executed, the target rotational speed of the prime mover 40 does not change and is maintained constant (at the first specific rotational speed) even when the rated rotational speed of the prime mover 40 changes. Then, when the target rotational speed of the prime mover 40 is returned to the rated rotational speed by the deceleration cancellation control, the target rotational speed is returned to the changed (modified) rated rotational speed.

In short, in the present embodiment, even when the accelerator operation portion 37 is operated while the deceleration control is being executed, the deceleration control is continued, and thus the change in the rated rotational speed is not immediately reflected in the rotational speed of the prime mover 40. Therefore, the rated rotational speed changed by the operation on the accelerator operation portion 37 performed while the deceleration control is being executed is reflected in the deceleration cancellation control. Thus, while the deceleration control is being executed, that is, when the target rotational speed of the prime mover 40 is maintained at the first specific rotational speed (< the rated rotational speed), the change in the rated rotational speed performed by the operation on the accelerator operation portion 37 can be reflected in the rotational speed of the prime mover 40.

Hereinafter, as illustrated in FIG. 3, it is assumed that the rotational speeds of a plurality of stages (here, four stages) of the rotational speeds V21, V22, V23, and V24 can be set as the rated rotational speed V2. Among the rotational speeds V21, V22, V23, and V24, "V21" is the lowest (the lowest speed), and "V22", "V23", and "V24" are higher in this order (that is, V21<V22<V23<V24).

In each of the deceleration control and the deceleration cancellation control, the control processing portion 12 does not switch the rotational speed of the prime mover 40 at once, but gradually changes the rotational speed of the prime mover 40 such that the rotational speed of the prime mover 40 is shifted to the target rotational speed over a certain length of shift time.

In FIG. 3, the horizontal axis is a time axis, and the rotational speed of the prime mover 40 that changes by the deceleration control and the deceleration cancellation control is illustrated. As illustrated in FIG. 3, the control processing portion 12 gradually changes the actual rotational speed of the prime mover 40 (actual rotational speed) by changing the target rotational speed of the prime mover 40 during the deceleration control and the deceleration cancellation control. FIG. 3 illustrates a change in the rotational speed of the prime mover 40 when the rated rotational speed V2 is set to each of the rotational speeds V21, V22, V23, and V24.

To be specific, as illustrated in the upper part of FIG. 3, in the deceleration control, the control processing portion 12 gradually decreases the rotational speed of the prime mover 40 from the rated rotational speed V2 to the first specific rotational speed V1. The rotational speed of the prime mover 40 decreases from a time point t1 at a certain slope with the lapse of time, and is maintained at the first specific rotational speed V1 at a time point when the rotational speed reaches the first specific rotational speed V1. The slope of the graph in FIG. 3 corresponds to the amount of change in the rotational speed of the prime mover 40 per unit time, and is also referred to as a "change rate of the rotational speed".

In the example of FIG. 3, the change rate of the rotational speed in the deceleration control is identical (uniform) regardless of whether the rated rotational speed V2 before the deceleration control is the rotational speed V21, V22, V23, or V24. Therefore, the shift time (t3-t1) required when the rotational speed is shifted from the rated rotational speed V2 that is the rotational speed V22 to the first specific rotational speed V1 by the deceleration control is longer than the shift time (t2-t1) required when the rotational speed is shifted from the rated rotational speed V2 that is the rotational speed V21 to the first specific rotational speed V1 by the deceleration control. Similarly, the shift time (t4-t1) when the rated rotational speed V2 is the rotational speed V23 is further longer, and the shift time (t5-t1) when the rated rotational speed V2 is the rotational speed V24 is further longer.

As illustrated in the lower part of FIG. 3, in the deceleration cancellation control, the control processing portion 12 gradually increases the rotational speed of the prime mover 40 from the first specific rotational speed V1 to the rated rotational speed V2 (first return rotational speed). The rotational speed of the prime mover 40 decreases from the time point t1 at a certain slope with the lapse of time, and is maintained at the rated rotational speed V2 from the time point when the rotational speed reaches the rated rotational speed V2.

However, when the accelerator operation portion 37 is operated during the deceleration control, the setting processing portion 13 changes the rated rotational speed V2, and the control processing portion 12 gradually increases the rotational speed of the prime mover 40 to the changed rated rotational speed V2 during the deceleration cancellation control. As an example, when the rated rotational speed V2 before the deceleration control is the rotational speed V21 and the accelerator operation portion 37 is operated to change the rated rotational speed V2 to the rotational speed V22 during the deceleration control, the control processing portion 12 returns the rotational speed of the prime mover 40 to the rotational speed V22 that is the changed rated rotational speed V2 during the deceleration cancellation control.

As described above, the control method according to the present embodiment includes, when the deceleration condition is satisfied, executing the deceleration control in which the target rotational speed of the prime mover 40 for driving the hydraulic pump 41 that discharges hydraulic oil is switched from the rated rotational speed to the first specific rotational speed lower than the rated rotational speed, and changing the rated rotational speed in accordance with the operation of the accelerator operation portion 37. When the accelerator operation portion 37 is operated while the deceleration control is being executed, the control processing portion 12 continues the deceleration control.

In short, in the control method according to the present embodiment, the deceleration cancellation condition does not include the condition in which the accelerator operation portion 37 is operated, and thus, even when the accelerator operation portion 37 is operated while the deceleration control is being executed, the deceleration control is continued (without the execution of the deceleration cancellation control). Thus, for example, even when the operator operates the accelerator operation portion 37 in advance to set the rated rotational speed for the next work while the deceleration control is being executed, the deceleration control is not canceled and the deceleration control is continued. Therefore, while the deceleration control is being executed, the operator can change the rated rotational speed by operating the accelerator operation portion 37 without canceling the deceleration control.

Therefore, it is possible to avoid the action not intended by the operator as in the case where the deceleration control is immediately canceled when the accelerator operation portion 37 is operated while the deceleration control is being executed. As a result, it is possible to provide the control method of the work machine 3, the work machine control program, the control system 1, and the work machine 3, that can easily perform an action (of the work machine 3) intended by an operator. Further, it is also possible to suppress the power waste of the battery 38 due to the release of the deceleration control.

In other words, the work machine 3 according to the present embodiment is a work machine 3 including the prime mover 40 (electric motor), and includes the accelerator operation portion 37 that sets the rotational speed of the prime mover 40, the light load state determination portion, the automatic deceleration function setting portion, and the motor rotational speed control portion. The light load state determination portion determines whether the prime mover 40 is in a light load state in which the prime mover 40 is not performing work or traveling. When the light load state determination portion determines that the load of the work machine 3 is in the light load state, the automatic deceleration function setting portion enables an automatic deceleration function of rotating the prime mover 40 at a rotational speed lower than the rotational speed set by the accelerator operation portion 37. When the motor rotational speed control portion and the automatic deceleration function are set to be enabled, the prime mover 40 is rotated at a rotational speed lower than the rotational speed set by the accelerator operation portion 37. When the accelerator operation portion 37 is operated while the automatic deceleration function is set to be enabled by the automatic deceleration function setting portion (that is, while the deceleration control is being executed), the light load state determination portion determines that the load of the work machine 3 is in the light load state.

In the present embodiment, the light load state determination portion, the automatic deceleration function setting portion, and the motor rotational speed control portion are all included in the control processing portion 12 as one function of the control processing portion 12. Thus, when the accelerator operation portion 37 is operated while the deceleration control is being executed, the load of the work machine 3 is determined to be in the light load state, and thus the deceleration control is continued.

3.2. Stop Control and Stop Cancellation Control

Next, the control method according to the present embodiment, that is, the operations related to the stop control and the stop cancellation control among the operations of the control system 1 according to the present embodiment will be described.

When a predetermined stop condition is satisfied in a state where the automatic stop function is enabled (that is, the automatic stop switch is on), the control processing portion 12 of the control system 1 executes stop control of stopping the prime mover 40 and switching the target rotational speed of the prime mover 40 from the rated rotational speed to zero. The stop condition is a condition for executing the stop control, and the control processing portion 12 sets the target rotational speed of the prime mover 40 to zero when the stop condition is satisfied.

In the present embodiment, the stop condition includes a condition related to an operation of the work machine 3. That is, a condition related to an operation of the work machine 3 by the operator (operation-related condition) is included in the stop condition. Therefore, the operation status of the work machine 3 by the operator is reflected in whether the stop condition is satisfied, that is, whether the stop control is performed. Therefore, when the operation status of the work machine 3 by the operator satisfies the stop condition in a situation where, for example, the work portion 33 or the like is not actuated and the output of the prime mover 40 is not required, it is possible to perform the stop control of setting the target rotational speed of the prime mover 40 to zero (stopping the prime mover 40). That is, whether or not to perform the stop control can be determined by the operator's intention.

The condition related to the operation of the work machine 3 (operation-related condition) included in the stop condition includes that the operation device 35 of the work machine 3 has not been operated for a specified time. Specifically, when the operation device 35 includes an operation lever, a state in which the user (operator) does not operate the operation lever and the operation lever is in the neutral position is defined as a state in which the operation device 35 is not operated. In a state where the operation device 35 is not operated, the work machine 3 is in a standby state, and the respective portions (the traveling portion 31, the turning portion 32, and the work portion 33) of the machine body 30 do not act. Therefore, in a situation where the output of the prime mover 40 is not required, such as when the standby state of the work machine 3 continues for a specified time or more, the stop condition is satisfied, and the stop control can be performed. That is, since the needs to immediately move the work machine 3 is low when a situation in which the output of the prime mover 40 is not required continues for a specified time or more, the noise and vibration generated in the prime mover 40 can be reduced and the energy (electric power) consumption in the prime mover 40 can be suppressed by performing the stop control in such a situation.

The stop condition also includes a condition that a state where the accelerator operation portion 37 is not operated continues for a specified time or more. That is, when a state in which neither the operation device 35 for operating the traveling portion 31, the work portion 33, and the like of the machine body 30 nor the accelerator operation portion 37 is operated continues for a specified time (for example, about five minutes) or more, the control processing portion 12 sets the target rotational speed of the prime mover 40 to zero and stops the prime mover 40. The specified time in the stop condition is longer than the specified time in the deceleration condition for the deceleration control, and as an example, when the specified time in the deceleration condition is "3 seconds", the specified time in the stop condition is set to "5 minutes".

When the cutoff lever 463 is operated to the "up position" and the cutoff switch 462 is turned "off", the control processing portion 12 executes the stop control of switching the target rotational speed of the prime mover 40 from the rated rotational speed to zero regardless of whether the automatic stop function is enabled or disabled. In short, when the cutoff lever 463 is operated to enter a state where the work machine 3 cannot be operated (locked state), the stop control is exceptionally executed even when the automatic stop function is disabled (that is, the automatic stop switch is off).

Even when the stop control is executed and the prime mover 40 is stopped, the control system 1 continues to be energized, and thus the control system 1 continues to operate.

When both the deceleration condition and the stop condition are satisfied, the control processing portion 12 activates the automatic stop function preferentially to the automatic deceleration function, and executes the stop control to temporarily stop the prime mover 40. Since the stop control is executed when the cutoff lever 463 is at the "up position", the deceleration condition does not include a condition related to the operation of the cutoff lever 463.

On the other hand, when a predetermined stop cancellation condition is satisfied while the stop control is being executed, the control processing portion 12 of the control system 1 starts the prime mover 40 and executes the stop cancellation control of switching the target rotational speed of the prime mover 40 from zero to a second specific rotational speed. The stop cancellation condition is a condition for executing the stop cancellation control, and the control processing portion 12 increases the target rotational speed of the prime mover 40 when the stop cancellation condition is satisfied.

In the present embodiment, the stop cancellation condition includes a condition related to an operation of the work machine 3. That is, a condition related to an operation of the work machine 3 by the operator (operation-related condition) is also included in the stop cancellation condition. Therefore, the operation status of the work machine 3 by the operator is reflected in whether the stop cancellation condition is satisfied, that is, whether the stop cancellation control is performed. Therefore, in a state where the target rotational speed of the prime mover 40 is suppressed to zero by the stop control, for example, in a situation where the output of the prime mover 40 is required to actuate the work portion 33 or the like, when the stop cancellation condition is satisfied depending on the operation status of the work machine 3 by the operator at that time, the stop cancellation control of increasing the target rotational speed of the prime mover 40 can be performed. That is, whether or not to perform the stop cancellation control can be determined by the operator's intention.

The condition related to the operation of the work machine 3 (operation-related condition) included in the stop cancellation condition includes that the operation device 35 of the work machine 3 is operated. Specifically, when the operation device 35 includes an operation lever, the stop cancellation condition includes that the operation lever is operated to a position other than the neutral position. Therefore, when the output of the prime mover 40 is required in a state where the target rotational speed of the prime mover 40 is set to zero by the stop control and the prime mover 40 is stopped, the stop cancellation condition is satisfied, and the stop cancellation control can be performed.

The stop cancellation condition also includes that the accelerator operation portion 37 is operated. That is, when any one of the operation device 35 for operating the traveling portion 31, the work portion 33, and the like of the machine body 30 and the accelerator operation portion 37 is operated during the stop control, the control processing portion 12 increases the target rotational speed of the prime mover 40 from zero to the second specific rotational speed.

The stop cancellation condition also includes that the automatic stop function is disabled in a state where the cutoff lever 463 is at the "down position". That is, when the automatic stop switch is turned off and the automatic stop function is disabled after the stop control is performed in a state where the automatic stop switch is on and the automatic stop function is enabled, the stop cancellation condition is satisfied and the control processing portion 12 switches the target rotational speed of the prime mover 40 from zero to the second specific rotational speed.

When the cutoff lever 463 is operated to the "down position" and the cutoff switch 462 is turned "on" in a state where the cutoff lever 463 has been operated to the "up position" and the stop control has been executed, the control processing portion 12 executes the stop cancellation control of switching the target rotational speed of the prime mover 40 from zero to the second specific rotational speed. That is, the stop cancellation condition includes an operation of setting the cutoff lever 463 to the locked state and then setting the cutoff lever 463 to the unlocked state. In short, when the cutoff lever 463 is operated to be changed from the state in which the work machine 3 can not be operated (locked state) to the state in which the work machine 3 can be operated (unlocked state), the stop cancellation control is executed. Thus, the stop control can be canceled only by the operation of the cutoff lever 463.

In the present embodiment, the second specific rotational speed is the same as the first return rotational speed. Furthermore, in the present embodiment, as described above, the first return rotational speed is the same as the rated rotational speed. That is, the target rotational speed of the prime mover 40 is switched from the rated rotational speed to zero by the stop control, and is switched from zero to the rated rotational speed (second specific rotational speed = first return rotational speed) by the stop cancellation control. Therefore, in a state where the prime mover 40 is driven at the rated rotational speed, the prime mover 40 is temporarily stopped by the stop control and returned by the stop cancellation control.

As in the deceleration control and the deceleration cancellation control, in each of the stop control and the stop cancellation control, the control processing portion 12 does not switch the rotational speed of the prime mover 40 at once, but gradually changes the rotational speed of the prime mover 40 such that the rotational speed of the prime mover 40 is shifted to the target rotational speed over a certain length of shift time.

In FIG. 4, the horizontal axis is a time axis, and the rotational speed of the prime mover 40 that changes by the stop control and the stop cancellation control is illustrated. As illustrated in FIG. 4, the control processing portion 12 gradually changes the actual rotational speed of the prime mover 40 (actual rotational speed) by changing the target rotational speed of the prime mover 40 during the stop control and the stop cancellation control. FIG. 4 illustrates a change in the rotational speed of the prime mover 40 when the rated rotational speed V2 is set to each of the rotational speeds V21, V22, V23, and V24.

To be specific, as illustrated in the upper part of FIG. 4, in the stop control, the control processing portion 12 gradually decreases the rotational speed of the prime mover 40 from the rated rotational speed V2 to zero (0). The rotational speed of the prime mover 40 decreases from the time point t1 at a certain slope with the lapse of time, and is maintained at zero from the time point when the rotational speed reaches zero. The slope of the graph in FIG. 4 corresponds to the amount of change in the rotational speed of the prime mover 40 per unit time, and is also referred to as a "change rate of the rotational speed".

In the example of FIG. 4, the change rate of the rotational speed in the stop control is identical (uniform) regardless of whether the rated rotational speed V2 before the stop control is the rotational speed V21, V22, V23, or V24.

Therefore, the shift time (t3-t1) required when the rotational speed is shifted from the rated rotational speed V2 that is the rotational speed V22 to zero by the stop control is longer than the shift time (t2-t1) required when the rotational speed is shifted from the rated rotational speed V2 that is the rotational speed V21 to zero by the stop control. Similarly, the shift time (t4-t1) when the rated rotational speed V2 is the rotational speed V23 is further longer, and the shift time (t5-t1) when the rated rotational speed V2 is the rotational speed V24 is further longer.

As illustrated in the lower part of FIG. 4, in the stop cancellation control, the control processing portion 12 gradually increases the rotational speed of the prime mover 40 from zero to the rated rotational speed V2 (second specific rotational speed). The rotational speed of the prime mover 40 decreases from the time point t1 at a certain slope with the lapse of time, and is maintained at the rated rotational speed V2 from the time point when the rotational speed reaches the rated rotational speed V2.

3.3. Flowchart

FIG. 5 is a flowchart illustrating an example of processing according to the deceleration control and the deceleration cancellation control in the control method of the work machine 3 according to the present embodiment.

First, the control processing portion 12 sets the target rotational speed of the prime mover 40 to the rated rotational speed and controls the prime mover 40 (S1). At this time, the rotational speed of the prime mover 40 is controlled to become the rated rotational speed set by the accelerator operation portion 37.

Then, the control processing portion 12 confirms that the operation related to the traveling of the work machine 3 is not performed (S2), that the operation related to the work of the work machine 3 is not performed (S3), and that the operation of the accelerator operation portion 37 is not performed (S4). When the specified time has elapsed (S5:Yes) in a state where any of the operations is not performed (S2:No, S3:No, S4:No), the control processing portion 12 determines that the deceleration condition is satisfied and executes the deceleration control. That is, the control processing portion 12 decreases the rotational speed of the prime mover 40 by decreasing the target rotational speed of the prime mover 40 from the rated rotational speed to the first specific rotational speed (S7).

On the other hand, when "Yes" is determined in any one of steps S2 to S5, the control processing portion 12 determines that the deceleration condition is not satisfied, and returns the processing to step S1 to maintain the target rotational speed of the prime mover 40 at the rated rotational speed. However, only when the accelerator operation portion 37 is operated (S4:No), the setting processing portion 13 performs the processing of changing the rated rotational speed (S6), and then the processing returns to step S1.

Following the step S7, the control processing portion 12 confirms that the operation related to the traveling of the work machine 3 is not performed (S8), that the operation related to the work of the work machine 3 is not performed (S9), and that the operation of the accelerator operation portion 37 is not performed (S10). When none of the operations has been performed (S8:No, S9:No, S10:No), the control processing portion 12 determines that the deceleration cancellation condition is not satisfied, and returns the processing to step S7 to maintain the target rotational speed of the prime mover 40 at the first specific rotational speed. That is, the control processing portion 12 continues the deceleration control.

On the other hand, when an operation related to traveling or work of the work machine 3 is performed and "Yes" is determined in any one of steps S8 to S9, the control processing portion 12 determines that the deceleration cancellation condition is satisfied and executes the deceleration cancellation control. That is, the control processing portion 12 increases the rotational speed of the prime mover 40 by increasing the target rotational speed of the prime mover 40 from the first specific rotational speed to the rated rotational speed (S12).

However, when the accelerator operation portion 37 is operated while the deceleration control is being executed (S10:Yes), the setting processing portion 13 performs the processing of changing the rated rotational speed (S11), and then the processing returns to step S7. That is, since the deceleration cancellation condition is not satisfied even when the accelerator operation portion 37 is operated, the deceleration cancellation control (S12) is not performed, and the deceleration control is continued. In this case, the changed rated rotational speed is reflected for the first time in step S12 in which the deceleration cancellation control is performed.

The work machine 3 repeatedly executes the processes of the steps S1 to S12 described above. However, the flowchart illustrated in FIG. 5 is merely one example. Processing may appropriately be added or omitted, or an order of the processing may appropriately be switched.

4. Modified Examples

Hereinafter, modified examples of Embodiment 1 will be listed. The modified examples, which will be described below, can be applied in combination as appropriate.

The control system 1 in the present disclosure includes a computer system. The computer system includes, as a main component, one or more processors and one or more memories as hardware. When the processor executes the program that is stored in the memory of the computer system, the function as the control system 1 in the present disclosure is implemented. The program may be recorded in the memory of the computer system in advance, may be provided through the telecommunication line, or may be provided in a manner to be recorded in the non-transitory recording medium, such as a memory card, an optical disk, or a hard disk drive, each of which is readable by the computer system. Moreover, a part or all of the functional portions included in the control system 1 may be configured by an electronic circuit.

The configuration that at least some of the functions of the control system 1 are integrated in one housing is not an essential configuration for the control system 1, and the components of the control system 1 may separately be provided in the plural housings. On the contrary, the functions that are separately provided in the plural devices (for example, the control system 1 and the display device 2) in Embodiment 1 may be integrated in one housing. Furthermore, at least a part of the functions of the control system 1 may be realized by a cloud (cloud computing) or the like.

The prime mover 40 serving as a power source of the work machine 3 is not limited to an AC motor, and may be, for example, a DC motor or the like, or may be a power source other than an electric motor (electric machine) in the first place. That is, the prime mover 40 may be a diesel engine, an internal combustion engine (engine) other than a diesel engine, or a hybrid power source including an electric motor and an internal combustion engine.

It is not essential that the configuration that the first return rotational speed is the same value as the second specific rotational speed, and the first return rotational speed may be higher or lower than the second specific rotational speed. It is not essential that the configuration that the first return rotational speed (or the second specific rotational speed) is the same value as the rated rotational speed, and the first return rotational speed (or the second specific rotational speed) may be higher or lower than the rated rotational speed.

Further, the operation lever of the operation device 35 may be an electric operation device that is configured to accept various operations by the user by outputting an electric signal (operation signal) according to an operation by the user (operator) to the control system 1. In this case, the control system 1 can control the hydraulic actuator by controlling, for example, a control valve (electromagnetic valve) provided in place of the remote control valve 45 according to the operation of the operation device 35 (operation lever).

It is not essential that the control system 1 has the two functions of the automatic deceleration function and the automatic stop function, and the control system 1 may have only one of the automatic deceleration function and the automatic stop function.

The display device 2 is not limited to the dedicated device, but may be a general-purpose terminal, such as a laptop computer, a tablet terminal, or a smartphone. Furthermore, the mode of the display portion 23 is not limited to the mode in which the display screen is directly displayed like a liquid-crystal display or an organic EL display, and may be, for example, configured to display the display screen by projection like a projector.

As the information input mode of the operation portion 22, the mode other than the push-button switch, the touchscreen, and the operation dial may be adopted. For example, the operation portion 22 may adopt an input mode using a keyboard or a pointing device such as a mouse, a voice input mode, a gesture input mode, an input mode of an operation signal from another terminal, or the like.

The actuator in each of the portions of the machine body 30 is not limited to the hydraulic actuator. For example, the actuator may be a pneumatic actuator that is driven by a pneumatic pressure of compressed air or the like, may be an electric actuator that is driven by electric power supply, or may be a combination of these.

Supplementary Note of Invention

Hereinafter, an outline of the invention extracted from the above-described embodiment will be described in supplementary notes. Note that components and processing functions described in the following supplementary notes can be arbitrary selected and combined.

Supplementary Note 1

A control method of a work machine comprising:

when a deceleration condition is satisfied, executing deceleration control in which a target rotational speed of a prime mover for driving a hydraulic pump that discharges hydraulic oil is switched from a rated rotational speed to a first specific rotational speed lower than the rated rotational speed; and

changing the rated rotational speed in accordance with an operation of an accelerator operation portion,

wherein when the accelerator operation portion is operated while the deceleration control is being executed, the deceleration control is continued.

Supplementary Note 2

The control method of the work machine according to Supplementary Note 1, wherein

the deceleration condition includes that a state where the accelerator operation portion is not operated continues for a specified time or more.

Supplementary Note 3

The control method of the work machine according to Supplementary Note 1 or 2, wherein

the deceleration condition includes that a load applied to the work machine is in a light load state.

Supplementary Note 4

The control method of the work machine according to Supplementary Note 3, further comprising:

determining whether the load of the work machine is in the light load state from an operation status of traveling and/or work of the work machine.

Supplementary Note 5

The control method of the work machine according to Supplementary Note 4, wherein

in a case where a specific condition is satisfied, when an operation of traveling and/or work of the work machine is performed, it is determined that the load of the work machine is not in the light load state.

Supplementary Note 6

The control method of the work machine according to Supplementary Note 5, wherein

the specific condition includes that a cutoff lever is in an unlocked state.

Supplementary Note 7

The control method of the work machine according to any one of Supplementary Notes 1 to 6, further comprising:

when a stop condition is satisfied, executing stop control in which the prime mover is stopped and the target rotational speed is set to zero.

Supplementary Note 8

The control method of the work machine according to Supplementary Note 7, further comprising:

when a stop cancellation condition is satisfied in a state where the prime mover is stopped by the stop control, executing stop cancellation control in which the prime mover is started and the target rotational speed is set to a second specific rotational speed.

Supplementary Note 9

The control method of the work machine according to Supplementary Note 8, wherein

the stop cancellation condition includes an operation of setting a cutoff lever to a locked state and then setting the cutoff lever to an unlocked state.

Supplementary Note 10

The control method of the work machine according to any one of Supplementary Notes 1 to 9, wherein

when an operation is performed on the accelerator operation portion while the deceleration control is being executed, the rated rotational speed is changed in accordance with the operation of the accelerator operation portion.

Supplementary Note 11

The control method of the work machine according to Supplementary Note 10, further comprising:

when a deceleration cancellation condition is satisfied in a state where the target rotational speed is set to the first specific rotational speed by the deceleration control, executing deceleration cancellation control in which the target rotational speed is switched from the first specific rotational speed to the rated rotational speed,

wherein the rated rotational speed changed by an operation on the accelerator operation portion performed while the deceleration control is being executed is reflected in the deceleration cancellation control.

Supplementary Note 12

A work machine control program for causing one or more processors to execute

the control method of the work machine according to any one of Supplementary Notes 1 to 11.

REFERENCE SIGNS LIST

1 work machine control system

3 work machine

12 control processing portion

13 setting processing portion

30 machine body

37 accelerator operation portion

40 prime mover

41 hydraulic pump

463 cutoff lever

V1 first specific rotational speed

V2 rated rotational speed (second specific rotational speed)