METHOD FOR DISTRIBUTING POWER OF AN ELECTRICAL DRIVE TRAIN OF A WORKING MACHINE, CONTROL DEVICE, COMPUTER PROGRAM PRODUCT AND WORKING MACHINE

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2022/079938, filed on Oct. 26, 2022, and claims benefit to German Patent Application No. DE 10 2021 212 135. 7, filed on Oct. 27, 2021. The International Application was published in German on May 4, 2023 as WO 2023/073021 A1 under PCT Article 21(2).

FIELD

The present invention relates to a method for distributing power of an electrical drive train of a working machine, a control device, a computer program product, and a working machine.

BACKGROUND

Electrically driven working machines, for example wheel loaders, construction machines, or front loaders, currently have separately controllable traction drives and auxiliary drives which, in terms of their total output, exceed the performance capacity of a power storage device of the working machine, and therefore must be limited in output terms in different situations. A percentage or residual power distribution is mostly used. The distribution strategy used has a decisive influence on the traction behavior of the working machine and can significantly diminish the productivity of the working machine, depending on the situation.

DE 11 2012 002 685 T5 discloses a system and a method for power management in a working machine with electrical and/or hydraulic devices.

SUMMARY

In an embodiment, the present disclosure provides a method for distributing power of an electrical drive train of a working machine, wherein the drive train has a traction drive and an auxiliary drive, the method comprising determining an actual power allocation for the traction drive and an actual power allocation for the auxiliary drive and determining a current working state of the working machine. The method further comprises specifying a target power allocation to the traction drive and a target power allocation to the auxiliary drive based on the determined current working state of the working machine and adjusting the actual power allocation for the traction drive to the target power allocation for the traction drive, and adjusting the actual power allocation for the auxiliary drive to the target power allocation for the auxiliary drive.

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:

FIG. 1 illustrates a schematic depiction of a working machine according to an exemplary embodiment; and

FIG. 2 illustrates a schematic depiction of a method for distributing power of the electrical drive train of the working machine from FIG. 1.

DETAILED DESCRIPTION

In an embodiment, the present provides an improved method for distributing power of an electrical drive train of a working machine. Productivity of the working machine is increased in different working states, for example when loading or when traveling, in comparison with the prior art.

On the basis of the above, an embodiment of the present invention provides a method for distributing power of an electrical drive train of a working machine, a control device, a computer program product, and a working machine.

In a method for distributing power of an electrical drive train of a working machine, wherein the drive train has a traction drive and an auxiliary drive, an actual power allocation for the traction drive and an actual power allocation for the auxiliary drive is determined. A current working state of the working machine is determined. On the basis of the determined current working state, a target power allocation to the traction drive is specified. On the basis of the determined current working state, a target power allocation to the auxiliary drive is specified. The actual power allocation for the traction drive is adjusted to the target power allocation for the traction drive. The actual power allocation for the auxiliary drive is adjusted to the target power allocation for the auxiliary drive.

The working machine is preferably formed as a wheel loader or as a front loader, for example, but it can also be formed as another construction machine, as an agricultural machine, as a fork-lift truck or the like. The working machine has the electrical drive train. The electrical drive train has at least one electric machine, which can be operated in motor mode and optionally also in generator mode. The electrical drive train preferably has two electric machines. Furthermore, the electrical drive train has at least one transmission, which is operatively connected to the electric machine or to the electric machines and transmits the speed provided. The transmission can be a powershift stepped transmission, an automated transmission with a countershaft construction, a dual-clutch transmission or a continuously variable transmission (CVT transmission).

The electrical drive train has the traction drive and the auxiliary drive. The traction drive is preferably formed by means of a first one of the two electric machines and the auxiliary drive is preferably formed by means of a second one of the two electric machines. The traction drive of the working machine is designed to provide power that is required for driving the working machine, for example so that the working machine can move forward along a route. The auxiliary drive of the working machine is designed to provide power that is required for the work to be carried out by the working machine, for example in order to pick up, lift or offload bulk material or general cargo.

Bulk material is understood here to mean a powdery, granular or lumpy mixture, for example sand, gravel, soil, or rubble. Bulk material can be found in excavated debris, for example. The term excavated debris is used to denote a shapeless, loose accumulation of bulk material. General cargo is understood here to mean goods which, in contrast to bulk materials, can be transported as individual items, for example logs, crates, and pallets. A plurality of preferably similar items can also be grouped together.

In a first step of the method, the actual power allocation for the traction drive and the actual power allocation for the auxiliary drive is determined. This takes place via sensors in the working machine, for example by means of speed sensors, wherein the power that is available in each case is determined on the basis of a speed provided in each case. The power available for the traction drive or the power available for the auxiliary drive can of course also be determined in other customary ways. Thus, it is identified which power is presently allocated for the traction drive and which power is presently allocated for the auxiliary drive.

In a second step of the method, the current working state of the working machine is determined. The current working state is defined as that state in which the working machine is being operated. A non-exhaustive list of examples of working states includes a traveling state, a loading state, a Y cycle, and an unloading state, for example. In the case of a working machine, in particular in the case of a wheel loader or a front loader, a Y cycle is understood to mean the following: The working machine travels with an empty bucket toward a pile of excavated debris. The working machine then shovels into the pile. Following this, the bucket in the pile of excavated debris is filled. Following this in turn, the working machine travels backward away from the pile of excavated debris with a full bucket. A request is then made for the working machine to turn in the forward direction of travel, wherein forward travel with a loaded bucket is then performed. Proceeding from this, the bucket is unloaded and the working machine is subsequently operated in the reverse direction of travel with an unloaded bucket. After another turning operation, the working machine is situated in a starting position and a further Y cycle can begin.

The current working state can be determined by means of sensors in the working machine. For example, an imaging sensor or a plurality of imaging sensors, e.g. cameras, lidar sensors, or radar sensors, can detect when the working machine approaches a pile of excavated debris. This can happen in such a way, for example, that the pile of excavated debris is detected by means of the imaging sensor or the imaging sensors and a reduction in the distance between the working machine and the pile of excavated debris is detected. From this it is possible, by means of an evaluation that is run on a control device, for example, e.g. an ECU, to draw the conclusion that a loading state is imminent. This evaluation takes place by means of software that uses a computer program product that can make use of artificial intelligence, for example. Likewise in the reverse scenario, if the pile of excavated debris is detected and the distance between the pile of excavated debris and the working machine is increased, the evaluation can be used to conclude that a traveling state is imminent. In addition, by means of the imaging sensor or the imaging sensors, a transport vehicle, for example, can be detected as well as a reduction in the distance between the working machine and the transport vehicle. From this it can be concluded, by means of the evaluation, that an unloading state is imminent. If the loading state, traveling state, unloading state, and a further traveling state alternate repeatedly, the evaluation can be used to conclude that a Y cycle is taking place.

As an alternative to the embodiment just described, which employs imaging sensors, the current working state can be determined by means of other sensors in the working machine. For example, by using sensors it can be identified which speed a user of the working machine requests of the working machine. If the requested speed is higher than a predetermined threshold value, the traveling state can be inferred. In contrast, if the requested speed is lower than the predetermined threshold value, the loading state or the unloading state can be inferred.

In addition or as an alternative to this, by using sensors it can be determined whether a working apparatus of the working machine, for example a bucket or a fork, is filled or empty. This can take place, for example, by a weight of the working apparatus being determined using sensors. As an alternative to this, an imaging sensor can be used to determine whether the working apparatus is empty or filled. If the working apparatus is empty, it can be concluded that a loading operation is imminent. If the working apparatus is filled, it can be concluded that an unloading operation is imminent. In conjunction with a requested speed, an evaluation can be used to determine whether the traveling state is present or the loading state or the unloading state. If, for example, the working apparatus is empty and the requested speed lies below the predetermined threshold value, the loading state is present. If, for example, the working apparatus is empty and the requested speed lies above the predetermined threshold value, the traveling state is present. If, for example, the working apparatus is filled and the requested speed lies below the predetermined threshold value, the unloading state is present. If, for example, the working apparatus is filled and the requested speed lies above the predetermined threshold value, the traveling state is present.

In a third step of the method, on the basis of the determined current working state, the target power allocation to the traction drive is specified and the target power allocation to the auxiliary drive is specified. This specification takes place by means of the control device, which has stored a predefined power allocation for each working state of the working machine in its storage device. These predefined power allocations are stored in the storage device in the factory, for example. As an alternative or in addition to this, the target power allocations can be specified on the basis of empirical values from previous working states of the working machine by means of a machine learning method and stored in the storage device. This makes it possible to adjust power allocations predefined in the factory.

In a fourth step of the method, the actual power allocation for the traction drive is adjusted to the target power allocation for the traction drive. This adjustment obviously takes place only when the target power allocation for the traction drive is different from the actual power allocation for the traction drive. In the same step, the actual power allocation for the auxiliary drive is adjusted to the target power allocation for the auxiliary drive. This adjustment obviously takes place only when the target power allocation for the auxiliary drive is different from the actual power allocation for the auxiliary drive.

The power allocation takes place automatically, without a user of the working machine having to request the adjustment of the power allocation. For this purpose, the control device controls the auxiliary drive and the main drive and regulates the power allocation in each case. The power allocation takes place dynamically. In other words, the actual power allocation for the auxiliary drive and the actual power allocation for the traction drive is checked continuously and is adjusted to the appropriate target power allocation for the auxiliary drive and to the appropriate target power allocation for the traction drive when the working state changes. The method as a whole therefore runs continuously and repeatedly.

With the presented method, it is possible to allocate less power to the traction drive in certain working states, for example in the loading state or unloading state, than in other working states, for example in the traveling state. It is equally possible to allocate more power to the auxiliary drive in certain working states, for example in the loading state or unloading state, than in other working states, for example in the traveling state. It is advantageous that this can increase the productivity of the working machine in comparison with working machines that do not use the method.

According to an embodiment, if a loading state or an unloading state is determined as the current working state, the target power allocation to the traction drive is specified to be lower than the target power allocation to the auxiliary drive. This takes place automatically. In the loading state, when there is a misallocation of power, this can lead to jamming of the working apparatus of the working machine, for example when bulk material is being picked up from a pile of excavated debris using a bucket. By increasing the power allocation for the auxiliary drive and reducing the power allocation for the traction drive, jamming is prevented and the loading operation is accelerated. At the same time, the speed of the working machine is reduced when it approaches a loading area.

In the unloading state, for example when bulk material is being unloaded from a bucket onto a transport vehicle or onto a pile of excavated debris, raising of the working apparatus, and thus unloading, is accelerated if the power allocation for the auxiliary drive is increased and simultaneously the power allocation for the traction drive is reduced. At the same time, the speed of the working machine is reduced when it approaches an unloading area.

The productivity of the working machine is therefore increased in comparison with working machines that do not use the method. In both cases, reducing the power allocation for the traction drive presents no disadvantage to the user of the working machine.

According to an embodiment, if a traveling state is determined as the current working state, the target power allocation to the traction drive is specified to be higher than the target power allocation to the auxiliary drive. This takes place automatically. This means that the speed of the working machine can be increased during forward travel or during backward travel. As a result, the working machine travels along a route more quickly. The productivity of the working machine is therefore increased in comparison with working machines that do not use the method. Reducing the power allocation for the auxiliary drive presents no disadvantage to the user of the working machine.

According to an embodiment, if a Y cycle is determined as the current working state, when the working machine is reset, the target power allocation to the traction drive is specified to be higher than the target power allocation to the auxiliary drive, and subsequently, after the working machine is turned, the target power allocation to the traction drive is specified to be lower than the target power allocation to the auxiliary drive. Turning of the working machine can be determined by means of driving dynamics sensors in the working machine, for example, e.g. by means of steering-angle sensors, acceleration sensors, or yaw-rate sensors etc.

The loading state and the unloading state are each part of the Y cycle. The traveling state is also part of the Y cycle. The resetting of the working machine corresponds to the traveling state. After turning, the working machine adopts either a loading state or an unloading state. In both cases, the target power allocation to the auxiliary drive is increased and the target power allocation to the traction drive is reduced. The productivity of the working machine is therefore increased in comparison with working machines that do not use the method. The alternating reduction of the power allocation for the auxiliary drive and of the power allocation for the traction drive presents no disadvantage to the user of the working machine.

A control device for a working machine is connectable to the electrical drive train. The control device has means for carrying out the method that has already been described in the preceding description. Here, connectable means that the control device is connected to the electrical drive train of the working machine if said control device is used in the working machine. The means can be designed as a computer program product, for example, that runs on the control device.

On the basis of the prevailing working state of the working machine, the control device controls the electrical drive train of the working machine, more specifically the traction drive and the auxiliary drive, in order to adjust the actual power allocation for the traction drive to the target power allocation for the traction drive, and in order to adjust the actual power allocation for the auxiliary drive to the target power allocation for the auxiliary drive. This has already been described.

The computer program product comprises commands which, when the program is executed by the control device that has already been described, perform the method that has likewise already been described. The computer program product can comprise a program code that contains these commands. The program code can be incorporated in a data carrier or embodied as a downloadable data stream, for example.

A working machine has the control device that has already been described in the preceding description. In addition, the working machine has the electrical drive train, wherein the drive train has a traction drive and an auxiliary drive. This has already been described. The control device is connected to the drive train. The working machine is preferably formed as a wheel loader or as a front loader.

Various exemplary embodiments and details of the invention will be described in more detail with reference to the figures explained herein below.

FIG. 1 shows a schematic depiction of a working machine 1 according to an exemplary embodiment. The working machine 1 here is a wheel loader. The working machine 1 has an electrical drive train 2. The electrical drive train 2 has a traction drive 3 and an auxiliary drive 4.

The traction drive 3 serves to drive the working machine 1, so that said working machine 1 can move along a route. This is indicated by the longitudinal arrow. The auxiliary drive 4 serves to drive a working apparatus of the working machine 1, so that said working apparatus can perform its work. This is indicated by the vertical arrow. Here, the working apparatus is formed as a bucket that can be lowered, raised and tilted.

The working machine 1 has a control device 5 that is connected to the traction drive 3 and to the auxiliary drive 4. The control device 5 is formed as an ECU, for example. The control device 5 is set up to control the traction drive 3 and the auxiliary drive 4. For this purpose, the control device 5 has corresponding interfaces. The control device 5 has a storage device. Target power allocations SPN, SPF for the auxiliary drive 4 and for the traction drive 3 are stored in this storage device for every possible working state A of the working machine 1.

FIG. 2 shows a schematic depiction of a method 100 for distributing power of the electrical drive train 2 of the working machine from FIG. 1. In a first step 101 of the method 100, an actual power allocation IPF for the traction drive 3 and an actual power allocation IPN for the auxiliary drive 4 is determined. This determination takes place by means of sensors in the working machine and by means of an evaluation of the sensor data by the control device 5.

In a second step 102 of the method 100, a current working state A of the working machine 1 is determined. This determination takes place by means of sensors in the working machine and by means of an evaluation of the sensor data by the control device 5. The second step 102 can run at the same time as the first step 101 or alternatively after the first step 101. The working machine 1 here can assume, for example, the following working states A: A loading state A1, an unloading state A2, a traveling state A3, or, as a special working state, a Y cycle A4. The Y cycle A4 therefore represents a special feature, since it is designed as a combination of a plurality of successive working states A. The Y cycle A4 therefore has in each case loading states A1, unloading states A2 and traveling states A3, which alternate and repeat.

In a third step, on the basis of the determined current working state A, that is to say on the basis of the loading state A1, the unloading state A2, the traveling state A3 or the Y cycle A4, a target power allocation SPF to the traction drive 3 is specified, and a target power allocation SPN to the auxiliary drive 4 is specified. This specification takes place by means of the control device 5.

In a fourth step 104, the actual power allocation IPF for the traction drive 3 is adjusted to the target power allocation SPF for the traction drive 3, and the actual power allocation IPN for the auxiliary drive 4 is adjusted to the target power allocation SPN for the auxiliary drive 4. This adjustment, of course, takes place only when the target power allocation SPN for the auxiliary drive 4 differs from the actual power allocation IPN for the auxiliary drive 4 or when the target power allocation SPF for the traction drive 3 differs from the actual power allocation IPF for the traction drive 3. The control device 5 therefore compares the respective target power allocation SPF, SPN with the corresponding actual power allocation IPF, IPN.

Depending on the working state A, the target power allocation SPF to the traction drive 3 can therefore be specified to be lower than the target power allocation SPN to the auxiliary drive 4 or vice versa. For example, in the loading state A1 and in the unloading state A2, the target power allocation SPF to the traction drive 3 can be specified to be lower than the target power allocation SPN to the auxiliary drive 4. As a result, the power available to the traction drive 3 is limited. Equally, the power available to the auxiliary drive 4 is increased by the corresponding value. For example, in the traveling state A3, the target power allocation SPF to the traction drive 3 can be specified to be higher than the target power allocation SPN to the auxiliary drive 4. As a result, the power available to the auxiliary drive 4 is limited. Equally, the power available to the traction drive 3 is increased by the corresponding value.

For example, upon resetting in the Y cycle A4, the target power allocation SPF to the traction drive 3 is increased in comparison with the target power allocation SPN to the auxiliary drive 4. Equally, the power available to the auxiliary drive 4 is limited by the corresponding value. The resetting corresponds to a traveling state A3. Subsequently, after the working machine 1 is turned, the target power allocation SPF to the traction drive 3 is limited. Equally, the power available to the auxiliary drive 4 is increased by the corresponding value, since the turning of the working machine 1 in the Y cycle A4 is always followed by a loading state A1 or an unloading state A2.

The power allocation takes place dynamically. In other words, the actual power allocation IPN for the auxiliary drive 4 and the actual power allocation IPF for the traction drive 3 is checked continually and is adjusted to the appropriate target power allocation SPN for the auxiliary drive 4 and to the appropriate target power allocation SPF for the traction drive 3 when the working state A changes. The method 100 as a whole therefore runs continuously and repeatedly. By using the method 100, the productivity of the working machine 1 is increased significantly in comparison with working machines that do not use the method 100.

While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above.

The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.

LIST OF REFERENCE SIGNS

• • 1 working machine
  • 2 drive train
  • 3 traction drive
  • 4 auxiliary drive
  • 5 control device
  • 100 method
  • 101 first step
  • 102 second step
  • 103 third step
  • 104 fourth step
  • A working state
  • A1 loading state
  • A2 unloading state
  • A3 traveling state
  • A4 Y cycle
  • IPF actual power allocation for the traction drive
  • IPN actual power allocation for the auxiliary drive
  • SPF target power allocation for the traction drive
  • SPN target power allocation for the auxiliary drive