ROTATIONAL STRUCTURE AND WORKING MACHINE INCLUDING THE ROTATIONAL STRUCTURE

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2024-221936 filed on Dec. 18, 2024. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to rotational structures each configured to support a working device such that the working device is rotatable, and working machines each including such a rotational structure.

2. Description of the Related Art

Known working machines in the related art include a swing function to cause a working device including a boom, an arm, a bucket, and the like to pivot about a vertically extending pivot (swing pin). Some working machines with such a swing function include a detector to detect a swing state. For example, Japanese Unexamined Patent Application Publication No. 2021-099000 discloses a technique including the following components: a support bracket; a swing bracket rotatably supported on the support bracket; a noncontact sensor attached to the swing bracket; and a detected body attached to the support bracket. The technique detects the swing state through detection of the detected body by the noncontact sensor.

With the technique in Japanese Unexamined Patent Application Publication No. 2021-099000, the noncontact sensor is attached to the swing pin. Thus, vertical positional instability of the swing pin may cause variations in sensing accuracy.

SUMMARY OF THE INVENTION

Example embodiments of the present invention provide rotational structures that may address the issue mentioned above, and working machines each including such a rotational structure.

A rotational structure according to an example embodiment of the present invention includes a base, a detected body fixed to the base, a pivot supported on the base such that the pivot is rotatable about an axis, a swing bracket attached to the base via the pivot and configured to rotate relative to the base by rotating together with the pivot, a sensor to detect the detected body, and a sensor bracket fastened to the swing bracket to support the sensor.

The rotational structure may further include a rotation stopper fixed to the pivot, and a fastening mechanism to fasten the sensor bracket to the swing bracket and restrict rotation of the rotation stopper about the axis of the pivot relative to the swing bracket.

The fastening mechanism may include a tubular body fixed to the sensor bracket, and a fastener to fasten the sensor bracket to the swing bracket by being inserted in the tubular body and attached to the swing bracket.

The tubular body may be attached to the swing bracket by the fastener such that the tubular body is inserted in the rotation stopper to restrict the rotation of the rotation stopper about the axis of the pivot relative to the swing bracket.

The tubular body may be integral with the sensor bracket.

A working machine according to an example embodiment of the present invention includes the rotational structure, a machine body including the base, a working device supported by the swing bracket, and an actuator provided between the machine body and the swing bracket to allow the swing bracket to rotate relative to the base.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of example embodiments of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings described below.

FIG. 1 is a left side view of a slewing excavation working machine (to be referred to simply as “working machine” hereinafter).

FIG. 2 is a plan view of the working machine.

FIG. 3 is an enlarged plan view of a front portion of a machine body of the working machine, with components such as a canopy, a swing bracket, and a working device omitted.

FIG. 4 is a perspective view, as viewed from the right front, of a body frame including a rotational structure, with a sensor cover omitted.

FIG. 5 is a perspective view of the rotational structure as viewed from the upper right.

FIG. 6 is a perspective view of the rotational structure as viewed from the upper left rear.

FIG. 7A is a partial enlarged perspective view of major portions of the rotational structure, with the sensor cover omitted.

FIG. 7B is a partial enlarged perspective view of major portions of the rotational structure, with the sensor cover, a swing pin, and a rotation stop arm omitted.

FIG. 7C is a partial enlarged perspective view of major portions of the rotational structure, with a detector, the swing pin, and the rotation stop arm omitted.

FIG. 8A is a partial enlarged rear view of major portions of the rotational structure.

FIG. 8B is a partial enlarged rear view of major portions of the rotational structure, with the sensor cover omitted.

FIG. 8C is a partial enlarged rear view of major portions of the rotational structure, with the sensor cover, the swing pin, and the rotation stop arm omitted.

FIG. 9A is a partial enlarged rear view of major portions of the rotational structure, with the sensor cover omitted.

FIG. 9B is a partial enlarged rear view of major portions of the rotational structure, with the sensor cover, the swing pin, and the rotation stop arm omitted.

FIG. 10 is a cross-sectional view, taken along a line X-X indicated by arrows in FIG. 8B, of major portions of the rotational structure, with the sensor cover omitted.

FIG. 11 is a cross-sectional view, taken along a line XI-XI indicated by arrows in FIG. 8B, of major portions of the rotational structure, with the sensor cover omitted.

FIG. 12 is a perspective view of a sensor bracket.

FIG. 13 is a block diagram illustrating a swing control system.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

Example embodiments will now be described with reference to the accompanying drawings, wherein like reference numerals designate corresponding or identical elements throughout the various drawings. The drawings are to be viewed in an orientation in which the reference numerals are viewed correctly.

First, a configuration of a slewing excavation working machine 1 (to be referred to simply as “working machine 1” hereinafter), which is an example of a working machine including a rotational structure 40 according to the present invention, will now be described with reference to FIGS. 1 to 6 and the like.

FIG. 1 is a left side view of the working machine 1. FIG. 2 is a plan view of the working machine 1. FIG. 3 is an enlarged plan view of a front portion of a machine body 20 of the working machine 1, with components such as a canopy 27, a swing bracket 42, and a working device 30 omitted. FIG. 4 is a perspective view, as viewed from the right front, of a body frame 21 including the rotational structure 40, with a sensor cover 48 omitted. FIG. 5 is a perspective view of the rotational structure 40 as viewed from the upper right. FIG. 6 is a perspective view of the rotational structure 40 as viewed from the upper left rear.

As illustrated in FIGS. 1, 2, and the like, the working machine 1 includes a traveling body 10, the machine body 20, and the working device 30.

The machine body 20 is mounted to the upper portion of the traveling body 10 (specifically, a traveling frame 11 described later) via a slewing joint (swivel joint). The slewing joint has a vertically extending axis Xv (hereinafter, “slewing axis Xv”) as illustrated in FIGS. 1 and 4. The machine body 20 is configured to rotate (slew) in the horizontal direction about the slewing axis Xv relative to the traveling body 10.

As illustrated in FIG. 1, the entire working device 30 including a boom 31, an arm 32, a bucket 33, and the like is supported on the machine body 20 via the rotational structure 40. The rotational structure 40 includes a pivot (a swing pin 41) with a vertically extending axis Y (hereinafter, “swing axis Y”) as illustrated in FIGS. 1, 4 to 6, and the like. The entire working device 30 is configured to rotate (swing) in the horizontal direction about the swing axis Y relative to the machine body 20.

In the following description of each structural portion of the working machine 1, a “front-rear direction” refers to a direction that is coincident with the front-rear direction (width direction) of the machine body 20, and that is constant regardless of the rotational position of the traveling body 10 about the slewing axis Xv relative to the machine body 20. As for the machine body 20 (the body frame 21) depicted in FIGS. 1 to 6, the front-rear direction of the machine body 20 refers to the direction along a double-headed arrow A1 in FIGS. 1, 2, and 6 (to be referred to as “front-rear direction A1” hereinafter).

In the following description of each structural portion of the working machine 1, “forward”, “front”, or other directional terms used for the structural portion corresponds to the direction indicated by a single-headed arrow A2 aligned with the front-rear direction A1 of the machine body 20 as illustrated in FIGS. 1 to 6, and “rearward”, “rear”, or directional terms used for the structural portion corresponds to the direction indicated by a single-headed arrow A3 aligned with the front-rear direction A1 of the machine body 20 as illustrated in FIGS. 1, 2, and 4 to 6.

That is, in some of FIGS. 5 to 11 to which reference will be made later in describing the configuration of the rotational structure 40, the arrow A2 is depicted as indicating a direction such as “forward” or “front” for the rotational structure 40, and the arrow A3 is depicted as indicating a direction such as “rearward” or “rear” for the rotational structure 40.

In the following description of each structural portion of the working machine 1, a “left-right direction” refers to a direction coincident with the left-right direction (width direction) of the machine body 20, which is a constant direction regardless of the relative rotational position of the traveling body 10 about the slewing axis Xv with respect to the machine body 20. As for the machine body 20 (the body frame 21) depicted in FIGS. 2 to 6, the left-right direction of the machine body 20 refers to the direction along a double-headed arrow B1 in FIGS. 2 and 6 (to be referred to as “left-right direction B1” hereinafter).

In the following description of each structural portion of the working machine 1, “leftward”, “left”, or other directional terms used for the structural portion corresponds to the direction indicated by a single-headed arrow B2 aligned with the left-right direction B1 of the machine body 20 as illustrated in FIGS. 2 to 6, and “rightward”, “right”, or directional terms used for the structural portion corresponds to the direction indicated by a single-headed arrow B3 aligned with the left-right direction B1 of the machine body 20 as illustrated in FIGS. 2 to 6.

That is, in some of FIGS. 5 to 11 to which reference will be made later in describing the configuration of the rotational structure 40, the arrow B2 is depicted as indicating a direction such as “leftward” or “left” for the rotational structure 40, and the arrow B3 is depicted as indicating a direction such as “rightward” or “right” for the rotational structure 40.

The configuration of the traveling body 10 of the working machine 1 will now be described with reference to FIGS. 1 to 3. FIGS. 1 to 3 illustrate the working machine 1 in a state in which the front-rear direction of the traveling body 10 coincides with the front-rear direction of the machine body 20. The following description of the traveling body 10 assumes that the working machine 1 is in this state.

The traveling body 10 includes the traveling frame 11, and a pair of left and right traveling devices 12. One of the pair of left and right traveling devices 12 is a left traveling device 12L provided at a left portion of the traveling frame 11, and the other is a right traveling device 12R provided at a right portion of the traveling frame 11.

According to the present embodiment, the traveling device 12 is a crawler-type traveling device with a crawler wound around a drive wheel, an idler wheel, and the like that are supported on a track frame. However, the traveling device 12 may be a traveling device different in configuration from a crawler-type traveling device, for example, a tire-type traveling device including no crawler and including tires as front and rear wheels.

As illustrated in FIGS. 1 to 3, a dozer 13 is provided at a front portion of the traveling body 10. The dozer 13 includes a blade 13a positioned in front of the pair of left and right traveling devices 12, an actuator (hydraulic cylinder) 13b configured to swing the blade upward or downward, and the like.

The configuration of the machine body 20 of the working machine 1 will now be described with reference to FIGS. 1 to 5. The machine body 20 includes a body frame (chassis) 21, a lower side cover 22, a counterweight 23, a rear hood 24, a side hood 25, and the like. The body frame 21 is configured as illustrated in FIGS. 3 to 5 and the like. The lower side cover 22 is provided in a standing manner along a peripheral edge of the body frame 21 that extends from the left front portion of the body frame 21 to the left end portion as illustrated in FIGS. 1 and 2. The counterweight 23 is mounted to a rear end portion of the body frame 21 as illustrated in FIG. 1. The rear hood 24 is mounted to a rear portion of the body frame 21 via the counterweight 23 and defines a rear portion of the machine body 20 as illustrated in FIG. 1. The side hood 25 is mounted to a right portion of the body frame 21 and defines a right portion of the machine body 20 as illustrated in FIG. 2.

Various pieces of equipment for driving (actuating) the traveling device 12, the working device 30, and the like are provided to the machine body 20 configured as described above. For example, an internal combustion engine (engine) or the like that functions as a prime mover is mounted to the rear portion of the body frame 21 and covered by the rear hood 24, and a fuel tank, a hydraulic fluid tank, a battery, and the like are mounted to the right portion of the body frame 21 and covered by the side hood 25.

As illustrated in FIGS. 1 to 5 and the like, an operator's seat 26 is mounted immediately in front of and near the rear hood 24, and immediately to the left of and near the side hood 25. As illustrated in FIGS. 1, 4, 5, and the like, the left wall portion of the side hood 25 defines an operation panel 25a positioned laterally to the right of the operator's seat 26. The operation panel 25a is provided with various operation actuators such as switches.

As illustrated in FIGS. 1 and 2, the canopy 27 is provided to the machine body 20. The canopy 27 includes at least one canopy post 27a and a roof 27b. In rear of the operator's seat 26, a pair of left and right canopy posts 27a are provided in a standing manner from the upper face of the rear hood 24. The roof 27b extends forward from the upper ends of the pair of left and right canopy posts 27a such that the roof 27b covers the operator's seat 26 from above.

As illustrated in FIGS. 1 to 3, a floorboard 28 is laid along the upper edge of the lower side cover 22 such that the floorboard 28 extends from a position in front of the operator's seat 26 to a position laterally to the left of the operator's seat 26. An operator seated on the operator's seat 26 is able to have, through an open space extending above the floorboard 28, a clear, unobstructed view of the space located in front (A2) of the machine body 20 and the external space (B2) located to the left of the machine body 20. In particular, the operator seated on the operator's seat 26 is able to visually check the states of the working device 30 and the rotational structure 40, which are located in front (A2) of the machine body 20.

As illustrated in FIGS. 1 to 3, consoles positioned rearward of the floorboard 28 and laterally to the left and right of the operator's seat 26 are each provided with at least one work operation lever 61, which is configured to be manually operated by the operator seated on the operator's seat 26. According to the present embodiment, a pair of left and right work operation levers 61 are provided. One of the pair of left and right work operation levers 61 is a left work operation lever 61L positioned to the left of the operator's seat 26, and the other is a right work operation lever 61R positioned to the right of the operator's seat 26.

Each of the work operation levers 61 (the left and right work operation levers 61L and 61R) is a lever configured to be operated to control operation of the boom 31, the arm 32, and the bucket 33 of the working device 30 (i.e., extension and retraction of a boom cylinder 34, an arm cylinder 35, and a bucket cylinder 36).

As illustrated in FIGS. 1 and 2, at least one travel operation lever 62, at least one operation pedal 63, and the like are provided at suitable positions on the floorboard 28 forward of the operator's seat 26. The travel operation lever 62 is configured to be operated manually by the operator seated on the operator's seat 26. The operation pedal 63 is configured to be stepped on by the operator with the operator's foot.

According to the present embodiment, a pair of left and right travel operation levers 62 are provided to individually control the travel directions and the travel speeds of the left and right traveling devices 12. That is, of the pair of left and right travel operation levers 62, one is a left travel operation lever 62L configured to control the travel speed and the travel direction of the left traveling device 12L, and the other is a right travel operation lever 62R configured to control the travel speed and the travel direction of the right traveling device 12R.

Likewise, according to the present embodiment, a pair of left and right operation pedals 63 are provided. For example, one of the operation pedals 63 (the operation pedal 63 at the left according to the present embodiment) is a swing pedal 63a configured to be operated to rotate (swing) the working device 30 (the swing bracket 42) about the swing axis Y (i.e., to extend or retract a swing cylinder 39 described later). The other of the operation pedals 63 (the operation pedal 63 at the right according to the present embodiment) is an AUX pedal 63b configured to be operated to drive an auxiliary (AUX) attachment that is attached to the distal end of the arm 32 instead of (or in addition to) the bucket 33 (i.e., to control the supply or discharge of hydraulic fluid through an AUX port 38 described later).

As illustrated in FIGS. 1 and 2, safety barriers 64 and 65, which also function as handrails, are provided in a standing manner along the left and front edges of the floorboard 28. As illustrated in FIG. 1, to the right of the safety barrier 65 extending along the front edge of the floorboard 28, a post 66 is provided in a standing manner, and a display 67 illustrated in FIGS. 1 and 2 is provided at the upper end of the post 66.

The display 67 functions as both of the following interfaces: an output interface (instrument panel) configured to display information such as detection results obtained from various sensors or the like provided to the working machine 1 or the current settings made by operation of a switch or the like; and an input interface (operation panel) configured to accept input of information made by the operator, such as set values for various operations. An operation actuator configured to be operated by the operator, such as a switch, may be in the form of an image displayed on the screen by the display 67, or may be in the form of a physical switch attached to the display 67.

For example, the working machine 1 is configured to allow selection of one of the following modes as an operating mode of the working device 30: an excavation work mode in which excavation work is performed by use of the bucket 33 described later; and a crane mode in which the working device 30 is operated as a crane for lifting a load. The operator is allowed to perform, via the display 67, a selection operation for selecting a mode. The display 67 is configured to display the mode set through such a selection operation.

The central portion of the body frame 21 in FIG. 4 is pivotally supported on the traveling frame 11 located below the central portion of the body frame 21, via the above-mentioned slewing joint (swivel joint) having the slewing axis Xv.

As illustrated in FIGS. 2 to 5, the swing cylinder (actuator) 39 is positioned in the space between the body frame 21 and the floorboard 28 located above the body frame 21. As illustrated in FIG. 4, the proximal end portion (cylinder bottom) of the swing cylinder 39 is pivotally supported on a cylinder bracket portion 21a provided at a right portion of the body frame 21. Further, as illustrated in FIG. 5 and the like, the distal end portion (cylinder head) of the swing cylinder 39 is pivotally supported on a cylinder bracket portion 42e provided at a right portion of the swing bracket 42 described later.

As illustrated in FIGS. 1 to 6 and the like, a front portion of the body frame 21 projects beyond the front end of the floorboard 28, and the forwardly projecting portion defines a base 29. As illustrated in FIGS. 1, and 3 to 6, the swing bracket 42 is attached to the base 29 via the above-mentioned swing pin (pivot) 41 having the swing axis Y that extends vertically.

The base 29, the swing pin 41, the swing bracket 42, and the like mentioned above define the rotational structure 40 configured to, as mentioned above, support the entire working device 30 onto the machine body 20 (the body frame 21) such that the working device 30 is allowed to rotate (swing) about the swing axis Y relative to the machine body 20. A specific configuration of the rotational structure 40 will be described later in detail.

A configuration of the working device 30 of the working machine 1 will now be described with reference to FIGS. 1 and 2. The working device 30 of the working machine 1, which is an excavation working machine (backhoe), includes the boom 31, the arm 32, and the bucket 33 as mentioned above.

As illustrated in FIG. 1, the boom 31 is bent at a portion along its length, and the proximal end portion of the boom 31, which is located at one side with respect to the bent portion, is pivotally supported on a boom bracket portion 42c, which is provided in an upper portion of the swing bracket 42, via a horizontally extending boom pivot 31a in a manner that allows upward and downward pivotal movement.

The proximal end portion of the arm 32 is pivotally supported on the distal end portion of the boom 31, which is located at the other side with respect to the bent position of the boom 31, via a horizontally extending arm pivot 32a in a manner that allows upward and downward pivotal movement. The bucket 33 is pivotally coupled to the distal end portion of the arm 32.

As illustrated in FIGS. 1 and 2, the working device 30 includes the following cylinders: the boom cylinder 34, which is a hydraulic actuator for the boom 31; the arm cylinder 35, which is a hydraulic actuator for the arm 32; and the bucket cylinder 36, which is a hydraulic actuator for the bucket 33.

As illustrated in FIG. 1 and the like, the proximal end portion (cylinder bottom) of the boom cylinder 34 is pivotally supported on a cylinder bracket portion 42d provided in the swing bracket 42. When the swing bracket 42 is in a default position D (see FIG. 6 and the like) described later in the direction of its rotation about the swing pin 41, the cylinder bracket portion 42d is located at the front end portion of the swing bracket 42 in the front-rear direction A1 of the machine body 20 (for the swing bracket 42, the distal end portion located in the direction of the arrow A2 in FIGS. 1 to 6).

As illustrated in FIG. 1, a cylinder bracket portion 31b is provided on one side of the bent portion of the boom 31, and the distal end portion (cylinder head) of the boom cylinder 34 is pivotally supported on the cylinder bracket portion 31b. Accordingly, extraction or retraction of the boom cylinder 34 provided between the swing bracket 42 and the boom 31 causes the boom 31 to pivot about the boom pivot 31a relative to the swing bracket 42 (the machine body 20).

As illustrated in FIG. 1, the proximal end portion (cylinder bottom) of the arm cylinder 35 is pivotally supported on a cylinder bracket portion 31c, which is provided on the other side of the bent position of the boom 31. The distal end portion (cylinder head) of the arm cylinder 35 is pivotally supported on a cylinder bracket portion 32b, which is provided at the proximal end portion of the arm 32. Accordingly, extraction or retraction of the arm cylinder 35 provided between the boom 31 and the arm 32 causes the arm 32 to pivot about the arm pivot 32a relative to the boom 31.

As illustrated in FIG. 1, further, the proximal end portion (cylinder bottom) of the bucket cylinder 36 is pivotally supported on the cylinder bracket portion 32b of the arm 32. The distal end portion (cylinder head) of the bucket cylinder 36 is pivotally coupled via a bucket link 33a to the distal end portion of the arm 32 and to the bucket 33. Accordingly, as the bucket cylinder 36 provided between the arm 32 and the bucket 33 extends or retracts, the bucket link 33a is actuated, and the bucket 33 swings in a scoop direction C1 and a dump direction C2 relative to the arm 32.

As illustrated in FIGS. 1 and 2, in addition to a hydraulic fluid line to each of the boom cylinder 34, the arm cylinder 35, and the bucket cylinder 36, a line for supply/discharge of hydraulic fluid to/from an AUX attachment attached to the distal end of the arm 32 instead of (or in addition to) the bucket 33 is provided to the boom 31 and the arm 32, and the distal end of the above-mentioned line is positioned on a side portion of the arm 32 to define an AUX port (coupler) 38.

As illustrated in FIGS. 1 and 2, the bucket 33 is provided with a hook 37 to lift a load. Under normal conditions (during excavation work or the like), the hook 37 is stored in a locked state in the bucket 33. The hook 37 is configured to hang downward from the bucket 33 when the bucket 33 is pivoted in the scoop direction C1 relative to the arm 32 and the lock is released (such as by removing a lock pin). In the crane made mentioned above, a load is slung on the hook 37 thus allowed to hang downward, and the boom 31 and/or the arm 32 is operated to allow execution of lifting (crane) work for the load.

In the crane mode, to ensure safety in operating the boom 31 and the arm 32 as a crane, the rotation (swinging) of the working device 30 about the swing axis Y is limited or disabled. Accordingly, as illustrated in FIGS. 1, 6, and the like, the rotational structure 40 includes a detector 40s configured to execute detection related to the rotation of the swing bracket 42 about the swing axis Y (such as detection of the rotation angle of the swing bracket 42, or detection of whether the swing bracket 42 is in a predetermined rotational position (range)).

According to the present embodiment, the detector 40s is configured to detect whether the swing bracket 42 is in the default position D (see FIG. 8 and the like) corresponding to a predetermined rotational position. The detector 40s includes a detected body 49, a sensor 47 configured to detect the presence or absence of the detected body 49, and the like described later.

The working machine 1 includes a control system constructed therein to limit (disable) the rotation (swinging) of the working device 30 about the swing axis Y when the working device 30 is set in the crane mode. FIG. 13 is a block diagram illustrating a swing control system 100 representing such a control system. The swing control system 100 in FIG. 13 will now be described below.

The working machine 1 includes a controller 101 including, for example, an integrated circuit programmed to construct the above-mentioned system. The swing control system 100 includes the controller 101, the detector 40s electrically connected to the controller 101, the display 67, a control valve 102, the swing cylinder (actuator) 39 in fluid connection with the control valve 102, and the like. The control valve 102 is configured as a valve (e.g., a solenoid proportional valve) whose position can be electromagnetically controlled by an electrical signal provided from the controller 101. Changing the position of the control valve 102 allows the extension and retraction of the swing cylinder 39 to be controlled.

When an operator sets the crane mode by operating the display 67 as an input interface, a crane mode signal Sc, which indicates that the crane mode has been set, is input to the controller 101 via the display 67.

While receiving the crane mode signal Sc from the display 67, the controller 101 receives a default determination signal Sd indicative of a detection result obtained from the detector 40s. The controller 101 is configured to determine, based on the default determination signal Sd, whether the swing bracket 42 is in the default position D, transmit an image output signal Se to the display 67 that functions as an output interface, and cause the display 67 to display the result of the determination or, depending on the case, display a warning image.

In response to the controller 101 determining that the swing bracket 42 is in the default position D based on the default determination signal Sd received from the detector 40s while receiving the crane mode signal Sc from the display 67, then while receiving the crane mode signal Sc, the controller 101 transmits a control signal Sf to the control valve 102, maintains the position in which the control valve 102 is at the time of the above-mentioned determination, and restricts the extension and retraction of the swing cylinder 39.

In response to the controller 101 determining in the crane mode that the swing bracket 42 is not in the default position D, the controller 101 prompts the operator to perform an operation (e.g., the above-mentioned operation of stepping on the swing pedal 63a) to rotate (swing) the swing bracket 42 into the default position D, such as by causing the display 67 to display the above-mentioned warning image.

As mentioned above, the working machine 1 according to the present embodiment includes the swing pedal 63a, which functions as an operation member configured to be operated by the operator to rotate (swing) the swing bracket 42 (i.e., to operate the control valve 102 to extend or retract the swing cylinder 39). Accordingly, the swing pedal 63a may be provided with a lock mechanism configured to, in the crane mode, lock the swing bracket 42 in the default position D.

In this case, for example, the controller 101 may be configured to, upon receiving the crane mode signal Sc from the display 67 functioning as an input interface and upon receiving the default determination signal Sd from the detector 40s, actuate the lock mechanism to lock the swing pedal 63a into a neutral position corresponding to the default position D of the swing bracket 42. The controller 101 may be configured to execute such a control of the lock mechanism to lock the swing pedal 63a, instead of or in addition to the above-mentioned outputting of the control signal Sf to the control valve 102.

Alternatively, for example, in a case where the working machine 1 includes, in addition to the detector 40s, a potentiometer or the like to detect the actual rotation (swing) position of the swing bracket 42 about the swing axis Y, when the controller 101 determines, in the crane mode, that the swing bracket 42 is not in the default position D, the controller 101 may, based on a signal received from the potentiometer or the like and indicative of the actual rotation (swing) position of the swing bracket 42, output a command signal for position change to the control valve 102, and cause the swing cylinder 39 to extend or retract to rotate (swing) the swing bracket 42 into the default position D.

A specific configuration of the rotational structure 40 including the detector 40s will now be described in detail, with reference to FIGS. 7A to 12 and the like in addition to FIGS. 1 to 6 and 13 cited above.

FIG. 7A is a partial enlarged perspective view of major portions of the rotational structure 40, with the sensor cover 48 omitted. FIG. 7B is a partial enlarged perspective view of major portions of the rotational structure 40, with the sensor cover 48, the swing pin 41, and a rotation stop arm 43 omitted. FIG. 7C is a partial enlarged perspective view of major portions of the rotational structure 40, with the detector 40s, the swing pin 41, and the rotation stop arm 43 omitted.

FIG. 8A is a partial enlarged rear view of major portions of the rotational structure 40. FIG. 8B is a partial enlarged rear view of major portions of the rotational structure 40, with the sensor cover 48 omitted. FIG. 8C is a partial enlarged rear view of major portions of the rotational structure 40, with the sensor cover 48, the swing pin 41, and the rotation stop arm 43 omitted.

FIG. 9A is a partial enlarged rear view of major portions of the rotational structure 40, with the sensor cover 48 omitted. FIG. 9B is a partial enlarged rear view of major portions of the rotational structure 40, with the sensor cover 48, the swing pin 41, and the rotation stop arm 43 omitted.

FIG. 10 is a cross-sectional view, taken along a line X-X indicated by arrows in FIG. 8B, of major portions of the rotational structure 40, with the sensor cover 48 omitted. FIG. 11 is a cross-sectional view, taken along a line XI-XI indicated by arrows in FIG. 8B, of major portions of the rotational structure 40, with the sensor cover 48 omitted. FIG. 12 is a perspective view of a sensor bracket 44.

The rotational structure 40 includes: the base 29; the detected body 49 fixed to the base 29; the swing pin (pivot) 41 supported on the base 29 such that the swing pin 41 is rotatable about the swing axis Y; the swing bracket 42 attached to the base 29 via the swing pin 41 and configured to rotate relative to the base 29 by rotating together with the swing pin 41; the sensor 47 to detect the detected body 49; and the sensor bracket 44 fastened to the swing bracket 42 to support the sensor 47.

Further, the rotational structure 40 includes: the rotation stop arm (rotation stopper) 43 fixed to the swing pin 41; and at least one fastening mechanism 50 to fasten the sensor bracket 44 to the swing bracket 42 and restrict rotation of the rotation stop arm 43 about the swing axis Y relative to the swing bracket 42.

The fastening mechanism 50 includes: at least one boss (tubular body) 45 fixed to the sensor bracket 44; and at least one bolt (fastener) 46 to fasten the sensor bracket 44 to the swing bracket 42 by being inserted in the boss 45 and attached to the swing bracket 42.

The boss 45 is attached to the swing bracket 42 by the bolt 46 such that the boss 45 is inserted in the rotation stop arm 43 to restrict the rotation of the rotation stop arm 43 about the swing axis Y relative to the swing bracket 42.

The boss 45 may be integral with the sensor bracket 44.

The general configuration of the rotational structure 40 is as described above. The specific configuration of various components of the rotational structure 40 will now be described.

Major components of the rotational structure 40 include: the base 29 of the machine body 20; the swing bracket 42 to support the working device 30; and the swing pin 41 to pivotally support the swing bracket 42 onto the base 29.

As illustrated in FIGS. 3, 7C, 10, 11, and the like, a cylindrical boss 29a including a boss hole 29b in the form of a vertically extending through-hole is provided at the front end portion of the base 29. The swing pin 41 in the form of a hollow cylinder or a solid cylinder is inserted in the boss 29a, and the axis of the boss hole 29b and the axis of the swing pin 41 are aligned to define the swing axis Y that extends vertically.

As illustrated in FIGS. 10 and 11, an outer peripheral face of the swing pin 41, and an inner peripheral face of the boss 29a, which defines the boss hole 29b, are in contact with each other in a manner that allows relative sliding movement, via a bush (radial bearing) 41a. This allows the swing pin 41 to rotate (swing) about the swing axis Y relative to the base 29 (the machine body 20), and further allows the swing pin 41 to move (slide) also along the swing axis Y (i.e., upward or downward) relative to the base 29 (the machine body 20).

As illustrated in FIGS. 1, 4 to 6, 7C, and the like, the swing bracket 42 includes, at one portion thereof in the horizontal direction, an upper clamping portion 42a and a lower clamping portion 42b (to be sometimes referred to as “upper and lower clamping portions 42a and 42b” hereinafter) that extend in the horizontal direction. The upper clamping portion 42a is positioned above the base 29, and the lower clamping portion 42b is positioned below the base 29.

As illustrated in FIGS. 1, 4 to 6, 7C, and the like, the swing bracket 42 includes, at the other portion thereof in the horizontal direction opposite from the upper and lower clamping portions 42a and 42b, the cylinder bracket portion 42d described above that pivotally supports the proximal end portion of the boom cylinder 34.

As described above, as for the rotation (swinging) of the swing bracket 42 about the swing axis Y relative to the base 29, the default position D is set. FIGS. 4 to 11 all illustrate the rotational structure 40 when the swing bracket 42 is in the default position D.

Thus, when the swing bracket 42 is in the default position D, the one portion of the swing bracket 42 in the horizontal direction where the upper and lower clamping portions 42a and 42b are provided refers to a rearward portion (see the arrow A3 in FIGS. 4 to 7C and 9A to 11) in the front-rear direction A1 of the machine body 20, and the other portion of the swing bracket 42 in the horizontal direction where the cylinder bracket portion 42d is provided refers to a forward portion (see the arrow A2 in FIGS. 4 to 6, 7C, 9A, 9B, and 11) in the front-rear direction A1 of the machine body 20.

That is, as illustrated in FIGS. 5, 6, and the like, when in the default position D, the swing bracket 42 is oriented such that the upper and lower clamping portions 42a and 42b face rearward (A3) and the cylinder bracket portion 42d faces forward (A2).

The bottom portion of the swing pin 41 and the upper portion of the swing pin 41 are inserted in a pin hole in the form of a vertically extending through-hole in the lower clamping portion 42b located below the base 29 and in a pin hole 42al in the form of a vertically extending through-hole in the upper clamping portion 42a located above the base 29, respectively, via the bush 41a or the like as illustrated in FIGS. 10 and 11, in a manner that allows relative rotation (swinging) about the swing axis Y and that also allows relative movement along the swing axis Y.

As illustrated in FIGS. 10, 11, and the like, the upper end portion of the swing pin 41 projects upward beyond the upper clamping portion 42a, and the rotation stop arm (rotation stopper) 43 is fixed to the upper end portion of the swing pin 41.

It may suffice that the rotation stop arm 43 be fixed to the swing pin 41. That is, it may suffice that the rotation stop arm 43 be unable to move in any direction (or at least about the swing axis Y and along the swing axis Y) relative to the swing pin 41.

The rotation stop arm 43 may be, for example, a member originally separate from the swing pin 41 and subsequently fixed to the upper end portion of the swing pin 41 such as by welding or pinning, or may be a member designed from the beginning to be integral with the swing pin 41.

According to the present embodiment, the rotation stop arm 43 is provided in the form of a flange surrounding the entire outer peripheral face of the swing pin 41. The rotation stop arm 43, however, need not necessarily be provided in the manner mentioned above. For example, the rotation stop arm 43 may be provided in such a manner that when the swing bracket 42 is in the default position D, the front end portion of the rotation stop arm 43 is connected to only a portion of the swing pin 41 that defines the rear end portion.

As illustrated in FIGS. 5, 6, 7A, 10, 11, and the like, the rotation stop arm 43 is a plate-shaped member that extends from its portion fixed to the upper end portion of the swing pin 41 to its distal edge 43a, along the upper face of the upper clamping portion 42a (in the radial direction of the swing pin 41). The distal edge 43a of the rotation stop arm 43 is positioned along a distal edge 42a2 of the upper clamping portion 42a. As illustrated in FIG. 10, the rotation stop arm 43 includes, near the distal edge 43a, at least one hole 43b in the form of a vertically extending through-hole in which the boss 45 is to be inserted.

As illustrated in the figures mentioned above, when the swing bracket 42 is in the default position D, the distal edge 43a corresponds to the rear edge of the rotation stop arm 43, and the distal edge 42a2 corresponds to the rear edge of the upper clamping portion 42a. That is, the distal edge 43a of the rotation stop arm 43 and the distal edge 42a2 of the upper clamping portion 42a are positioned rearward (in the direction indicated by the arrow A3) of the swing pin 41.

As illustrated in FIGS. 5 to 11 (excluding FIGS. 7B, 7C, and 8C) and the like, the sensor bracket 44 having the structure (shape) as illustrated in FIG. 12 is positioned above the rotation stop arm 43. The rotational structure 40 includes the fastening mechanism 50 to fasten the sensor bracket 44 to the swing bracket 42. The fastening mechanism 50 is configured to restrict rotation of the rotation stop arm 43 about the swing axis Y relative to the swing bracket 42.

The fastening mechanism 50 includes the boss (tubular body) 45 and the bolt (fastener) 46. The boss 45 is fixed to the sensor bracket 44. The bolt 46 fastens the sensor bracket 44 to the swing bracket 42 by being inserted in the boss 45 and attached to the swing bracket 42.

The boss 45 hangs downward from a bottom plate portion 44b in the sensor bracket 44, and is inserted in the hole 43b of the rotation stop arm 43. The boss 45 and the hole 43b have substantially the same diameter, and the outer peripheral face of the boss 45 and the inner peripheral face of the hole 43b are in close contact with each other. Accordingly, there is no clearance in the hole 43b that allows the boss 45 to move in the horizontal direction (the radial direction of the boss 45) relative to the rotation stop arm 43.

Preferably, the rotation stop arm 43 includes a plurality of (two according to the present embodiment) holes 43b such that the holes 43b are arranged around the swing axis Y. The rotation stop arm 43 includes, in the corresponding manner, a number of (two according to the present embodiment) bosses 45 equal to the number of holes 43b. As each of the bosses 45 is inserted in the corresponding one of the holes 43b, relative pivotal movement between the rotation stop arm 43 and the sensor bracket 44 about the swing axis Y is restricted more reliably.

The distal edge 43a of the rotation stop arm 43 has a width substantially around the swing axis Y in correspondence with such holes 43b. Accordingly, as viewed along the swing axis Y (in the vertical direction), the rotation stop arm 43 has a U-shape that is open at the rear. The shape of the rotation stop arm 43, however, is not limited to the above-mentioned shape. For example, if the rotation stop arm 43 includes two holes 43b, the rotation stop arm 43 may be configured to extend in a bifurcated manner toward the two holes 43b from its portion fixed to the swing pin 41.

It may suffice that the boss 45 be fixed to the sensor bracket 44, that is, be unable to move in any direction (at least about the swing axis Y and along the swing axis Y) relative to the sensor bracket 44. The boss 45 may be, for example, a member originally separate from the sensor bracket 44 and subsequently fixed at its upper portion to the bottom plate portion 44b of the sensor bracket 44 such as by welding or pinning, or may be a member designed from the beginning to be integral with the sensor bracket 44.

The construction of the sensor bracket 44 illustrated in FIG. 12 and the like will now be described. The sensor bracket 44 includes a body 44a in the form of a vertically extending upright plate. The bottom plate portion 44b in the form of a horizontal plate extends horizontally from the bottom end of the body 44a, and is fixed to a vertically intermediate portion of the boss 45 or to an upper portion of the boss 45. That is, the boss 45 hangs downward from the bottom plate portion 44b.

According to the present embodiment, two bosses 45 are provided, and thus the sensor bracket 44 includes two bottom plate portions 44b corresponding to the two bosses 45. Each boss 45 is fixed to the corresponding bottom plate portion 44b. A lower portion of the body 44a of the sensor bracket 44 is bifurcated and extends toward the two bottom plate portions 44b. The two bosses 45 each hang downward from the corresponding one of the two bottom plate portions 44b.

That is, the lower portion of the body 44a of the sensor bracket 44 includes a cutout 44c. The lower portion of the body 44a of the sensor bracket 44 is bifurcated so as to straddle the cutout 44c, with the cutout 44c defining the spacing between the two bottom plate portions 44b.

As illustrated in FIGS. 10 and 11, the upper end portion of the swing pin 41, which projects slightly upward beyond the rotation stop arm 43, has a portion (the rear upper end portion of the swing pin 41 when in the default position D) thereof positioned within the cutout 44c of the sensor bracket 44. That is, the body 44a of the sensor bracket 44, which is a body having a bifurcated shape, is positioned to straddle the upper end portion of the swing pin 41.

As illustrated in FIG. 10, a predetermined position Ps of the sensor bracket 44, which is a suitable position for the detector 40s provided to the rotational structure 40, is set on the upper clamping portion 42a. Generally speaking, a suitable position of the sensor bracket 44 for the detector 40s refers to a position that is suited for the sensor 47 supported on the sensor bracket 44 to, when the swing bracket 42 is in the default position D, reliably detect the detected body 49 provided to the base 29.

According to the present embodiment, with the sensor bracket 44 positioned in the predetermined position Ps and attached to the upper clamping portion 42a, a distance Ls, which is the distance from the swing axis Y to the body 44a in the radial direction (horizontal direction) of the swing pin 41, is less than a radius Lr of the outer periphery of the swing pin 41 as illustrated in FIG. 10. That is, with this taken into account, the sensor bracket 44 is shaped to have the cutout 44c (bifurcated) as illustrated in FIG. 12.

In a case where the body 44a of the sensor bracket 44 can be positioned outside the swing pin 41 (positioned closer to the distal edge 42a2 of the upper clamping portion 42a than is the swing pin 41) (positioned rearward (A3) of the rear end of the swing pin 41 when the swing bracket 42 is in the default position D) in the radial direction of the swing pin 41, the body 44a of the sensor bracket 44 may have a non-bifurcated shape with no cutout 44c, and a single bottom plate portion 44b may be provided rather than a pair of bottom plate portions 44b positioned across the cutout 44c, with two (a plurality of) bosses 45 fixed to the single bottom plate portion 44b.

That is, in a case where the rotational structure 40 is configured such that the distance Ls from the swing axis Y to the body 44a of the sensor bracket 44 located in the predetermined position Ps is greater than the radius Lb of the outer periphery of the swing pin 41, the sensor bracket 44 may have a shape (non-bifurcated shape) that does not include the cutout 44c illustrated in FIG. 12.

As mentioned above, the shape or the like of the sensor bracket 44 is not limited to that illustrated in FIG. 12 but may, for example, be changed as described above according to a condition such as the positional relationship between the sensor bracket 44 located in the predetermined position Ps and the swing pin 41.

The sensor bracket 44 is made of, for example, a metal plate material. The body 44a having a bifurcated shape is formed through punching or the like of the metal plate material, and the bottom plate portion 44b, a sensor attachment plate portion 44d, which will be described later, and the like are formed through bending or the like. However, the material of the sensor bracket 44, the method for forming various portions of the sensor bracket 44, and the like are not limited to those mentioned above. The sensor bracket 44 may be formed by use of any material, method, and the like that can satisfy various requirements required in providing the detector 40s to the rotational structure 40 in terms of rigidity, durability, ease of processing, cost effectiveness, and the like.

How the predetermined position Ps of the sensor bracket 44 on the upper clamping portion 42a (i.e., the distance Ls of the body 44a from the swing axis Y) is determined will be described later in detail.

As illustrated in FIGS. 7C and 10, the upper clamping portion 42a of the swing bracket 42 includes, near the distal edge 42a2, at least one threaded hole 42a3 in the form of an upwardly facing opening corresponding to a boss hole 45a of the boss 45. The sensor bracket 44 is positioned such that the boss hole 45a of the boss 45 aligns with the threaded hole 42a3.

In a case where the sensor bracket 44 includes a plurality of (two according to the present embodiment) bosses 45, the upper clamping portion 42a includes at least the same number of (two according to the present embodiment) threaded holes 42a3 as the number of bosses 45. In this case, the sensor bracket 44 is positioned such that the boss hole 45a of each of the sensor brackets 44 aligns with the corresponding one of the threaded holes 42a3.

As illustrated in FIGS. 7C, 8C, 10, and the like, preferably, the upper face of the upper clamping portion 42a includes at least one smooth spot-faced surface 42a4, and the upper end of the threaded hole 42a3 is open at the spot-faced surface 42a4. According to the present embodiment, two separate spot-faced surfaces 42a4 are provided, with two threaded holes 42a3 being each open at the corresponding one of the two spot-faced surfaces 42a4. Two (a plurality of) threaded holes 42a3 may be open at a single continuous spot-faced surface.

As illustrated in FIGS. 10, 12, and the like, the boss hole 45a vertically extends through the boss 45. Preferably, the boss 45 has a smooth lower end face. As illustrated in FIGS. 7C, 8C, 10, and the like, in attaching (securely fastening) the sensor bracket 44 to the upper clamping portion 42a of the swing bracket 42, the lower end of the boss hole 45a aligns with the upper end of the threaded hole 42a3 such that the smooth lower end face of the boss 45 is in abutting contact with the smooth spot-faced surface 42a4. The lower end face of the boss 45 and the spot-faced surface 42a4 may be spaced from each other with a spacing component (e.g., a washer or a spacer) therebetween, rather than being in direct abutting contact with each other.

The upper end of the boss hole 45a is open upward at the upper face of the bottom plate portion 44b or at a position above the upper face of the bottom plate portion 44b. According to the present embodiment, as illustrated in FIG. 12 and the like, the bottom plate portion 44b of the sensor bracket 44 is fixed in the form of a flange to a vertically intermediate portion of the boss 45. The upper end portion of the boss 45 thus projects upward from the upper face of the bottom plate portion 44b, and the upper end of the boss hole 45a is open at the upper end face of the boss 45. However, the upper end portion of the boss 45 need not necessarily project upward from the upper face of the bottom plate portion 44b of the sensor bracket 44 (i.e., may project (hang) only downward from the bottom plate portion 44b). In this case, the upper end of the boss hole 45a (or a hole defined in the bottom plate portion 44b as an upward extension of the boss hole 45a) is open at the upper face of the bottom plate portion 44b.

As illustrated in FIG. 10 and the like, with the bolt (fastener) 46 positioned to extend vertically, that is, in parallel to the swing axis Y (along the swing axis Y), the bolt 46 is inserted into the boss hole 45a of the boss 45 from above the bottom plate portion 44b, and is passed through the boss hole 45a for threaded insertion into the threaded hole 42a3. The bolt 46 threadedly inserted in the threaded hole 42a3 has its head fastened to the upper end face of the boss 45 or the upper face of the bottom plate portion 44b, preferably with a spacing component 46a such as a washer, a nut, or a flange interposed therebetween as illustrated in FIGS. 7A, 7B, and 8A to 11, or directly with no such spacing component interposed between. The sensor bracket 44 is thus securely fastened with the bolt 46 to the upper clamping portion 42a of the swing bracket 42.

By securely fastening the sensor bracket 44 to the upper clamping portion 42a as described above, the bolt 46 restricts movement of the sensor bracket 44 relative to the swing bracket 42, both about the swing axis Y and along the swing axis Y. That is, the bolt 46 fixes the sensor bracket 44 against rotation with respect to the swing bracket 42, and prevents (restricts) vertical looseness of the sensor bracket 44 with respect to the swing bracket 42.

Consequently, the sensor 47 to be attached to the sensor bracket 44 as will be described later is held in a predetermined position relative to the upper clamping portion 42a, regardless of the vertical looseness of the swing pin 41 with respect to the swing bracket 42 mentioned above.

Preferably, as with the present embodiment, a plurality of (two according to the present embodiment) bolts 46 corresponding to a plurality of (two according to the present embodiment) bosses 45 provided to the sensor bracket 44 fasten the sensor bracket 44 to the upper clamping portion 42a. This more reliably restricts movement of the sensor bracket 44 about the swing axis Y and along the swing axis Y relative to the swing bracket 42.

That is, preferably, the rotational structure 40 includes a plurality (a pair according to the present embodiment) of fastening mechanisms 50, each of which includes the boss (tubular body) 45 and the bolt (fastener) 46. Alternatively, a single fastening mechanism 50 includes a plurality (a pair according to the present embodiment) of bosses (tubular bodies) 45 and a plurality (a pair according to the present embodiment) of bolts (fasteners) 46. The sensor bracket 44 is fastened to the swing bracket 42 by means of such a plurality of fastening mechanisms 50, or such a single fastening mechanism 50 including a plurality of bosses (tubular bodies) 45 and a plurality of bolts (fasteners) 46. This makes it possible to more reliably restrict movement of the sensor bracket 44 relative to the swing bracket 42.

According to the present embodiment, the bolt 46 is used as the fastener to fasten the sensor bracket 44 to the swing bracket 42 (the upper clamping portion 42a). The fastener, however, is not limited to a bolt. For example, the fastener may be a screw. Alternatively, a configuration may be used in which the fastener includes a threaded rod and a nut, the threaded rod is provided to the upper clamping portion 42a so as to extend upward, and after the threaded rod is inserted in the boss 45, the nut is threadedly installed on the threaded rod to fasten the boss 45 to the upper clamping portion 42a with the nut.

As illustrated in FIG. 10 and the like, with the boss 45 inserted in the hole 43b of the rotation stop arm 43 as described above, the boss 45 is fastened with the bolt 46 to the upper clamping portion 42a. The outer peripheral face of the boss 45 is in sliding contact with the peripheral face of the hole 43b. Accordingly, although there is no clearance within the hole 43b that allows relative movement of the boss 45 in the horizontal direction (around the swing axis Y), the rotation stop arm 43 is allowed to slide along the boss 45 in the vertical direction (along the swing axis Y) within a predetermined range (play).

As illustrated in FIG. 10, the rotation stop arm 43 is positioned between the bottom plate portion 44b of the sensor bracket 44 and the upper face of the upper clamping portion 42a. The bottom plate portion 44b and the upper face of the upper clamping portion 42a are separated from each other by a predetermined distance L1 in the vertical direction that varies with the vertical length of the boss 45. The rotation stop arm 43 has a thickness L2 in the vertical direction. Accordingly, sliding movement of the rotation stop arm 43 along the boss 45 is allowed within a predetermined range (play) corresponding to a difference L3, which is the difference between the distance L1 and the thickness L2.

As a result, vertical looseness of the swing pin 41 with respect to the swing bracket 42 is allowed within the above-mentioned play. In other words, while vertical looseness of the swing pin 41 with respect to the swing bracket 42 is allowed, the sensor bracket 44 is fixed (securely fastened) to the swing bracket 42 such that vertical looseness of the sensor bracket 44 with respect to the swing bracket 42 (the upper clamping portion 42a) is prevented or reduced.

In this way, the sensor bracket 44 is fixed (securely fastened) to the upper clamping portion 42a. As illustrated in FIG. 12 and the like, the sensor attachment plate portion 44d extending in the horizontal direction, a relay attachment plate portion 44e in the form of an upright plate, and a cover attachment plate portion 44f in the form of an upright plate are provided at the upper end portion of the body 44a of the sensor bracket 44.

As illustrated in FIGS. 7A, 7B, 8A to 11, and the like, a sensor element holder 47a (detecting body), which defines the body of the sensor 47, is attached to the sensor attachment plate portion 44d with the head portion (sensor head) of the sensor element holder 47a facing down. A relay 47c of the sensor 47, which is a relay connected to the sensor element holder 47a via an electric wire (such as a harness or a cable) 47b, is attached to the relay attachment plate portion 44e. The sensor cover 48, which covers the sensor 47 (the sensor element holder 47a, the electric wire (such as a harness or a cable) 47b, and the relay 47c), is securely fastened with a bolt, a screw, or the like to the cover attachment plate portion 44f.

As illustrated in FIGS. 8A, 8B, 9A to 11, and the like, the sensor 47 has a limited sensing region Rs directly below the lower end portion of the sensor element holder 47a (detecting body), which is an end portion defining the sensor head. As illustrated in FIGS. 7A, 7B, 9A to 11, and the like, with the sensor bracket 44 positioned in the predetermined position Ps and securely fastened to the upper clamping portion 42a, the sensor attachment plate portion 44d of the sensor bracket 44 extends laterally outward (rearward when the swing bracket 42 is in the default position D) of the distal edge 42a2 of the upper clamping portion 42a when viewed in the horizontal direction. The sensing region Rs, which is located directly below the sensor element holder 47a attached to the sensor attachment plate portion 44d, is positioned above a portion of the base 29 that extends rearward (A3) of the distal edge 42a2 of the upper clamping portion 42a, when the swing bracket 42 is in the default position D.

As for the base 29 on the machine body 20, as illustrated in FIGS. 7A to 11 and the like, the detected body 49 is fixed to the base 29 such that the detected body 49 projects upward from the upper face of the base 29. According to the present embodiment, the detected body 49 includes a stay 49b in contact with the upper face of the base 29 and located at the bottom of the detected body 49, and the stay 49b is securely fastened to the base 29 with a fastener such as a bolt. It may suffice, however, that the detected body 49 be fixed to the base 29 in a manner that does not allow the detected body 49 to move in any direction relative to the base 29. For example, the detected body 49 may be fixed to the upper face of the base 29 by welding or the like, or may be designed from the beginning to be integral with the machine body 20 (the body frame 21).

The detector 40s is configured to, based on sensing of the detected body 49 by the sensor 47, detect whether the swing bracket 42 is in the default position D. Additionally, the detector 40s is configured to allow an operator seated on the operator's seat 26 to, by looking at the state of the detector 40s in front of the operator, determine whether the swing bracket 42 is in the default position D.

That is, as illustrated in FIGS. 5 to 7A, 8A, 9A, and the like, the sensor cover 48 is provided with an indicator 48a. As illustrated in FIG. 8A, as viewed from the operator seated on the operator's seat 26 when the swing bracket 42 is in the default position D, the indicator 48a appears to be vertically aligned with the detected body 49 provided to the base 29.

As can be appreciated from FIG. 8A, the left-right direction B1 of the base 29 (i.e., the machine body 20) substantially coincides with direction in which the upper clamping portion 42a of the swing bracket 42 rotates (swings) when the swing bracket 42 is in the default position D or in the vicinity of the default position D. Thus, when the swing bracket 42 deviates from the default position D, then as viewed from the operator seated on the operator's seat 26, the indicator 48a is displaced to the left (B2) or the right (B3) from the position corresponding to the detected body 49. This allows the operator seated on the operator's seat 26 to, upon finding displacement of the indicator 48a to the left or right relative to the detected body 49, determine that the swing bracket 42 (the working device 30) has deviated from the default position D.

In this way, the operator seated on the operator's seat 26 is able to determine whether the swing bracket 42 is in the default position D, by looking at the detector 40s in front of the operator with the operator's own eyes and checking the positional relationship between the indicator 48a of the sensor cover 48 and the detected body 49. Further, when extending or retracting the swing cylinder 39 through a stepping operation of the swing pedal 63a to rotate (swing) the working device 30, the operator seated on the operator's seat 26 is able to determine whether the swing bracket 42 has reached the default position D by checking, with the unaided eye, the positional relationship between the indicator 48a of the sensor cover 48 and the detected body 49.

According to the present embodiment, the indicator 48a is in the form of a protrusion at the upper end portion of the sensor cover 48. This, however, does not imply any limitation on the configuration of the indicator 48a. For example, the indicator 48a may be applied on the sensor cover 48 with paint or the like, or written on the sensor cover 48. Further, the indicator 48a need not necessarily be positioned at the upper end portion of the sensor cover 48 but may be located at, for example, a position lower than the upper end portion of the sensor cover 48.

The sensor (detecting body) 47 and the detected body 49 may take various conceivable configurations. In one conceivable example, the sensor 47 may be an optical sensor, and the detected body 49 may be of a material or a property that allows detection of the detected body 49 by the optical sensor.

With the detector 40s according to the present embodiment, however, the sensor 47 is a magnetic proximity sensor (including a Hall element, a reed switch, a magneto-resistive (MR) sensor element, or the like), and the detected body 49 is a magnetic body made of iron, nickel, or cobalt with a magnetic field that is detectable by the magnetic proximity sensor. The description given below with regard to the rotational structure 40 (including the detector 40s) assumes that the sensor 47 is a magnetic proximity sensor and the detected body 49 is a magnetic body.

The detected body 49 includes, at its upper end, a sensed portion 49a that can be positioned in closest proximity to the sensor head located at the lower end of the sensor element holder (detecting body) 47a. As the swing bracket 42 rotates about the swing axis Y, the sensor 47 senses the magnetic field originating from the detected body 49 most strongly when the sensed portion 49a enters the sensing region Rs and comes into proximity with the lower end (sensor head) of the sensor element holder (detecting body) 47a.

Accordingly, with the swing control system 100 in FIG. 13, the default determination signal Sd to be input from the detector 40s to the controller 101 is set as a signal indicative of the intensity of a magnetic field sensed by the sensor 47, and the intensity of a magnetic field sensed by the sensor 47 upon entry of the sensed portion 49a into the sensing region Rs is set as a threshold. This allows the controller 101 to determine whether the swing bracket 42 is in the default position D by comparing, with the threshold, the intensity of the magnetic field indicated by the default determination signal Sd.

As described above, the sensor bracket 44 that supports the sensor 47 is securely fastened to the upper clamping portion 42a of the swing bracket 42 such that the sensor bracket 44 is free from vertical positional instability. This also prevents or reduces vertical positional instability of the sensor element holder 47a relative to the swing bracket 42 and thus, as illustrated in FIGS. 8B and 8C, keeps a distance Rd constant, the distance Rd being the vertical distance from the sensed portion 49a that has entered the sensing region Rs to the sensor head at the lower end of the sensor element holder 47a. Therefore, every time the sensed portion 49a enters the sensing region Rs, the sensor 47 always senses a magnetic field of a constant intensity. This stabilizes the accuracy of detection performed by the detector 40s, which is configured to detect whether the swing bracket 42 is in the default position D.

To reliably retain the swing bracket 42 in the default position D in the crane mode, it is required to minimize the range of rotation (swing) angle of the swing bracket 42 about the swing axis Y within which the sensor 47 senses the presence of the sensed portion 49a within the sensing region Rs.

Accordingly, the detector 40s uses, as the sensor 47, a proximity sensor or the like with a narrow sensing region Rs, and uses, as the detected body 49 in the form of a magnetic body, a member having a small width in the left-right direction B1 (which substantially coincides with the direction in which the upper clamping portion 42a of the swing bracket 42 rotates (swings) when the swing bracket 42 is in the default position D or in the vicinity of the default position D) of the base 29 (the machine body 20) as illustrated in FIGS. 5 to 8C and the like.

That is, as illustrated in FIGS. 8A to 8C, the detected body 49 has, from its upper end portion defining the sensed portion 49a to its lower end portion defining the base of the stay 49b, a width W1 that is uniform in the left-right direction B1. To eliminate or reduce the likelihood that the sensor 47 senses the presence of the sensed portion 49a within the sensing region Rs even when the swing bracket 42 deviates from the default position D, the width W1 is set in a suitable manner such as by taking a width W2 into account, which is the width in the left-right direction B1 of the sensing region Rs of the sensor 47 located above the upper clamping portion 42a of the swing bracket 42 when the swing bracket 42 is in the default position D or in the vicinity of the default position D.

The stay 49b of the detected body 49 is elongated in the left-right direction B1. In this regard, to ensure that the sensor 47 does not sense the magnetic field originating from the stay 49b regardless of the position to which the swing bracket 42 rotates (swings) about the swing axis Y, the stay 49b is fixed to the base 29 at a position clear of the sensing region Rs in the radial direction of the swing pin 41, that is, as illustrated in FIGS. 9A and 9B, at a position that is rearward (A3) of the sensing region Rs of the sensor 47 located above the upper clamping portion 42a when the swing bracket 42 is in the default position D.

To connect the stay 49b, which is positioned clear of the sensing region Rs as described above, and the sensed portion 49a, which is located at a position that allows its entry into the sensing region Rs, the detected body 49 includes a vertically extending portion 49c and, further, an obliquely extending portion 49d as illustrated in FIGS. 9A, 9B, and the like. The vertically extending portion 49c, which lies from a lower portion of the detected body 49 to a vertically intermediate portion, extends upward from the stay 49b. The obliquely extending portion 49d extends obliquely upward and forward to the sensed portion 49a, which is located at the upper end portion of the detected body 49, from a bent portion where the detected body 49 is bent at the vertically intermediate portion (the upper end of the vertically extending portion 49c). The vertically extending portion 49c and the obliquely extending portion 49d each have the uniform width W1 described above.

The above-mentioned configuration of the detected body 49 may lead to a possibility that the sensor 47 senses the magnetic field originating from the obliquely extending portion 49d extending in the vicinity of the sensing region Rs. However, the obliquely extending portion 49d extends in the radial direction of the swing pin 41 and, as described above, has the limited uniform width W1 that is set with the width W2 of the sensing region Rs taken into account. Accordingly, the only time that the sensor 47 senses the magnetic field originating from the obliquely extending portion 49d outside the sensing region Rs is when the sensor 47 senses the magnetic field originating from the sensed portion 49a simultaneously with the sensing of the magnetic field originating from the obliquely extending portion 49d. Therefore, the sensing of the magnetic field originating from the obliquely extending portion 49d does not affect the accuracy of the determination of whether the swing bracket 42 is in the default position D.

With regard to the positional setting of the sensing region Rs of the sensor 47, the distance of the sensing region Rs of the sensor 47 from the swing axis Y depends on the above-mentioned distance Ls of (the body 44a of) the sensor bracket 44 from the swing axis Y. The distance Ls is determined to satisfy requirements described below.

First, to make the swing bracket 42 compact, it is desired that the distance (length) in the horizontal direction from the swing axis Y to the distal edge 42a2 of the upper clamping portion 42a be as small as possible. To satisfy this requirement, it is desired that the distance Ls of (the body 44a of) the sensor bracket 44 from the swing axis Y be as small as possible.

In cases such as when, for example, the boom 31 and the arm 32 are extended at a low position in substantially the horizontal direction, even for the same movement in the horizontal direction associated with the rotation (swinging) of the swing bracket 42 about the swing axis Y, for example, a portion (to be referred to as “most remote portion” hereinafter) of the working device 30 located most remote from the swing axis Y in the horizontal direction (the radial direction of the swing pin 41), such as the distal end portion of the bucket 33, undergoes a greater amount of movement than does the distal edge 42a2 of the upper clamping portion 42a.

In such a case, a situation may arise where, even when the amount of movement of the distal edge 42a2 in the horizontal direction associated with the rotation (swinging) of the swing bracket 42 about the swing axis Y is small and within a range in which the swing bracket 42 is regarded as being still in the default position D, the most remote portion of the working device 30 undergoes an amount of movement exceeding a range in which the swing bracket 42 is regarded as being in the default position D.

The amount of movement of the most remote portion of the working device 30, which tends to be comparatively great as mentioned above, is to be also taken into account in setting a region where the sensor 47 senses a magnetic field of such an intensity that the swing bracket 42 is determined to be in the default position D. In such a case, it is desired that the distance Ls of (the body 44a of) the sensor bracket 44 from the swing axis Y be as large as possible, so that the difference between the amount of movement of the sensor 47 relative to the detected body 49 and the amount of movement of the most remote portion of the working device 30, which are associated with the rotation (swinging) of the swing bracket 42 about the swing axis Y, can be made as small as possible.

Accordingly, the distance Ls of (the body 44a of) the sensor bracket 44 from the swing axis Y is preferably set to a suitable value for satisfying the two competing requirements mentioned above.

The foregoing describes the specific configuration of the rotational structure 40 including the detector 40s. Advantageous effects and the like of the rotational structure 40 and of the working machine 1 including the rotational structure 40 according to some configurations will now be described.

(Item 1) A rotational structure 40 including a base 29, a detected body 49 fixed to the base 29, a pivot 41 (swing pin) supported on the base 29 such that the pivot 41 is rotatable about an axis Y (swing axis), a swing bracket 42 attached to the base 29 via the pivot 41 and configured to rotate relative to the base 29 by rotating together with the pivot 41, a sensor 47 to detect the detected body 49, and a sensor bracket 44 fastened to the swing bracket 42 to support the sensor 47.

According to the above-mentioned configuration, the sensor bracket 44 securely fastened to the swing bracket 42 is free from vertical positional instability with respect to the swing bracket 42, and thus the sensor 47 supported on the sensor bracket 44 is also free from vertical positional instability with respect to the swing bracket 42. This stabilizes the positional relationship between the sensor 47 attached to the swing bracket 42 via the sensor bracket 44, and the detected body 49 fixed to the base 29, and also stabilizes the ability (sensitivity) of the sensor 47 to detect the detected body 49.

(Item 2) The rotational structure 40 according to item 1, further including a rotation stopper 43 fixed to the pivot 41, and a fastening mechanism 50 to fasten the sensor bracket 44 to the swing bracket 42 and restrict rotation of the rotation stopper 43 about the axis Y of the pivot 41 relative to the swing bracket 42.

According to the above-mentioned configuration, by means of the fastening mechanism 50, the sensor bracket 44 supporting the sensor 47 is easily and reliably fastened securely to the swing bracket 42 in a manner that restricts both relative rotation about the swing axis Y of the pivot 41 and relative movement along the swing axis Y. This makes it easily possible to stabilize the positional relationship between the sensor 47 and the detected body 49 (stabilize the sensitivity of the sensor 47).

(Item 3) The rotational structure 40 according to item 2, wherein the fastening mechanism 50 includes a tubular body 45 fixed to the sensor bracket 44, and a fastener 46 to fasten the sensor bracket 44 to the swing bracket 42 by being inserted in the tubular body 45 and attached to the swing bracket 42.

According to the above-mentioned configuration, by means of the fastener(s) 46 inserted in the tubular body(s) 45 fixed to the sensor bracket 44, the sensor bracket 44 supporting the sensor 47 is easily and reliably fastened securely to the swing bracket 42 in a manner that restricts both relative rotation about the swing axis Y of the pivot 41 and relative movement along the swing axis Y. This makes it easily possible to stabilize the positional relationship between the sensor 47 and the detected body 49 (stabilize the sensitivity of the sensor 47).

(Item 4) The rotational structure 40 according to item 3, wherein the tubular body 45 is attached to the swing bracket 42 by the fastener 46 such that the tubular body 45 is inserted in the rotation stopper 43 to restrict the rotation of the rotation stopper 43 about the axis Y of the pivot 41 relative to the swing bracket 42.

According to the above-mentioned configuration, the tubular body 45 securely fastened to the swing bracket 42 together with the sensor bracket 44 is inserted in the rotation stopper 43 fixed to the pivot 41. This ensures that the pivot 41 rotates (swings) relative to the base 29 integrally with the swing bracket 42.

(Item 5) The rotational structure 40 according to item 3 or 4, wherein the tubular body 45 is integral with the sensor bracket 44.

According to the above-mentioned configuration, no special process or effort is required to fix the tubular body 45 to the sensor bracket 44. This makes it possible to achieve cost effectiveness required for the rotational structure 40.

(Item 6) A working machine 1 including the rotational structure 40 according to any one of items 1 to 5, a machine body 20 including the base 29, a working device 30 supported by the swing bracket 42, and an actuator 39 provided between the machine body 20 and the swing bracket 42 to allow the swing bracket 42 to rotate relative to the base 29.

According to the above-mentioned configuration, the working machine 1 includes the rotational structure 40 including the sensor 47 configured to detect the detected body 49 with a stable sensitivity. This improves the accuracy in controlling the position to which the working device 30 rotates relative to the machine body 20 via the actuator 39 and the rotational structure 40. For example, in the crane mode, the swing bracket 42 and the working device 30 are reliably held in the default position D.

While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.