Method, control device and drive unit for preventing an undesired travel of a work machine in an infrared direction,

Abstract

A method is described for preventing an undesired travel of a working machine (14) in a wrong direction, the working machine (14) having an electric motor (2) for driving the working machine (14). A desired travel direction (FRW) of an operator of the work machine (14) is sensed (S1), and a state variable of the work machine (14) related to an actual travel direction of the work machine is sensed (S2). Furthermore, it is determined (S3) whether the electric machine (2) is in a safety critical state on the basis of a comparison of the sensed desired direction of travel (FRW) of the working machine with the sensed state variable. Then, if it has been identified that the safety critical state exists, a signal is sent (S4) to the motor (2) in order to bring the motor (2) into a state that is not suitable for driving. The invention further relates to a control unit (4) designed to carry out such a method. The invention further relates to a drive unit (6) having such a control unit (4), and to a work machine (14) having such a drive unit (6).

Description

Technical Field

[0001] The invention relates to a method for preventing an undesired travel of a working machine in the wrong direction. The invention also relates to a control device configured to perform such a method. The invention also relates to a drive unit having such a control device and to a working machine having such a drive unit. Prior art

[0002] Methods for controlling the driving behavior of a vehicle are known from the prior art. In this case, the driving behavior can be actively brought about, such as active braking. Alternatively, a process, such as a lane change, can be prevented. Summary of the invention

[0003] In a first aspect, the present invention relates to a method for preventing an undesired movement of a working machine in a wrong direction. The working machine may be an agricultural machine, a construction machine, a transport machine or an off-road vehicle. The working machine has a motor for propelling the working machine. Electrical energy may be supplied to the motor from an energy storage device (e.g., a battery, such as a lithium-ion battery) so as to propel the working machine. In addition to the motor for propulsion, the working machine may have additional machinery, such as an additional motor, for example for lifting a lifting frame. In addition, the working machine may have a control device, which may be configured to perform a method for preventing undesired movement in the wrong direction. The motor may have an inverter, such as a low-voltage inverter. Undesired movement in the wrong direction may be movement of the working machine in a direction that is undesired by the driver of the working machine. Preventing undesired movement may include stopping or preventing further undesired movement. In addition, the method may include preventing undesired changes in direction.

[0004] The method includes detecting a desired direction of travel of a driver of a work machine. In this case, information about the position of a direction of travel switch may be obtained and sent to a control device performing the method. Detecting the desired direction of travel may include receiving information about the position of the direction of travel switch. Detecting the desired direction of travel may include determining the desired direction of travel as a function of the received information about the position of the direction of travel switch. For example, the desired direction of travel may be forward, backward, or neutral.

[0005] The method also includes detecting a state variable of the work machine related to the actual direction of travel of the work machine. For example, the state variable related to the actual direction of travel of the work machine may be the rotational speed of a wheel or chain of the work machine. The rotational speed may be negative, zero, or positive. Depending on the sign of the rotational speed, the actual direction of travel of the work machine may be forward, backward, or neutral, where neutral may mean, for example, that the work machine is not moving and is stationary. Detecting the state variable may include receiving information about the state variable.

[0006] The method also includes determining whether the motor is in a safety critical state based on a comparison of a detected desired direction of travel of the work machine with a detected state variable. For example, if the desired direction of travel and an actual direction of travel associated with the state variable are different, then the motor is in a safety critical state. For example, the driver may want to drive forward, while the state variable may indicate, for example, that the actual direction of travel is backward.

[0007] The method also includes, if it has been determined that a safety critical state exists, sending a signal to the motor to transfer the motor to a state that is not suitable for propulsion. The control device for performing the method can be electrically connected to the motor and the inverter. This enables a signal for transferring the motor to a state that is not suitable for propulsion to be sent to the inverter and the motor. In this case, a safety state query can be sent to the motor or the inverter by the control device performing the method. Here, the state that is not suitable for propulsion can be a safe state of the motor. In the state that is not suitable for propulsion, it can be stipulated that the motor cannot generate any driving force to propel the working machine.

[0008] With the indicated method, undesired movement in the wrong direction, such as undesired driving away, can thus be blocked and prevented. Movement of the work machine, such as driving away, can be safety-critical because people can be present in the surroundings of the work machine. This method can prevent undesired movement in the wrong direction if, for example, a hardware or software fault exists in the control device and undesired movement in the wrong direction is initiated.

[0009] According to another embodiment, the method may be characterized in that detecting a state variable associated with the actual direction of travel includes detecting the motor rotation direction of the motor. For example, this may be detected by a sensor on the motor. Alternatively or additionally, the motor rotation direction may be detected by current and voltage measurements on the inverter and alternatively or additionally on the motor. The detected motor rotation direction may be sent from the inverter or from the motor to a control device that performs the method, wherein detecting the state variable may include receiving information in the form of a signal. The method may also be characterized in that a determination of the actual direction of travel is performed based on the detected motor rotation direction. The actual direction of travel may be determined by a predetermined transmission ratio that varies with the motor rotation direction. For example, if the motor rotates in a first direction, the actual direction of travel may be forward. If the motor rotates in a second direction opposite to the first direction, the actual direction of travel may be backward. If the motor rotation direction is zero, the actual direction of travel may be neutral and the work machine may be stationary. The method may also be characterized in that if the determined actual direction of travel is different from the detected desired direction of travel, a determination of a safety critical state is performed. For example, the actual direction of travel may be in a first direction of travel, such as forward, and the desired direction of travel may be in a second direction of travel opposite to the first direction of travel, such as backward.

[0010] Thus, a method can be indicated, which method can determine the actual direction of travel by means of information about the motor rotation direction, and by means of which the determination of a safety critical state can be performed. Thus, sending a signal to the motor to transfer the motor to a state not suitable for propulsion can be performed based on an easily measurable state variable of the motor (motor rotation direction).

[0011] According to another embodiment, the method may be characterized in that detecting a state variable associated with the actual direction of travel includes detecting a motor speed of the motor. Detecting the motor speed of the motor may include receiving a signal having information about the motor speed of the motor from the inverter and alternatively or additionally from the motor. The motor speed may be detected by a sensor on the motor. Alternatively or additionally, the motor speed may be determined by current and voltage measurements. Detecting the motor speed may also include detecting the motor rotation direction. Thus, a determination of the actual direction of travel may be made based on the detected motor speed. The method may also be characterized in that a determination of a safety critical state is made if the detected motor speed is within a parameter range around a motor speed corresponding to a stationary state of the working machine. For example, the motor speed corresponding to a stationary state of the working machine may be zero. The parameter range may include a positive motor speed and a negative motor speed, wherein the parameter range is, for example, arranged symmetrically around a zero motor speed. Alternatively or additionally, a determination of a safety critical state may be made if the detected motor speed changes from a value corresponding to a stationary state of the working machine. For example, a determination of a safety critical state may be made if the motor speed changes from a zero value to a value not equal to zero.

[0012] By means of the method shown, a safety-critical state can be determined if the motor speed is within a range around the motor speed corresponding to a stationary state of the working machine. Thus, at low travel speeds, that is to say, for example, when driving off the working machine, the functionality of the method for preventing driving off in the wrong direction can be provided. If the determination of the safety-critical state is carried out when the detected motor speed changes from a zero value to a value not equal to zero, the function can be triggered and the safety-critical state can be determined only when driving off from a stationary state, and if, for example, the working machine has already moved before the method is started, the function can not be triggered, i.e. the safety-critical state is not determined.

[0013] According to another embodiment, the method may also be characterized in that, based on the detected motor speed, a determination of the gradient of the motor speed may be performed. In this case, the control device may be configured to perform the determination of the gradient of the motor speed. In addition, the method may be characterized in that, if there is a change in the desired direction of travel and a comparison of the determined gradient of the motor speed with the minimum gradient shows that the determined gradient is greater, a determination of a safety critical state is performed. Here, the minimum gradient may be a predetermined minimum gradient and may be stored in the control device. The minimum gradient may be parameterized during the encoding of the control device. For example, if the driver changes the position of the direction of travel switch from a first direction (e.g. forward) to a second direction (e.g. backward), there may be a change in the desired direction of travel. The comparison of the determined gradient with the minimum gradient may be performed by the control device and be part of the determination of the safety critical state, or may be performed shortly before this.

[0014] By means of the method, a reversal, i.e. a change in the desired direction of travel by the driver, can be taken into account. For example, in the case where there is a reversal and the gradient of the motor speed is below a minimum gradient, a safety critical state is not determined. In this case, it may be expected that the desired direction of travel and the actual direction of travel are different. This may contribute to increasing the robustness of the method, wherein if a desired reversal by the driver is performed, a transfer of the motor to a state that is not suitable for propulsion is not performed.

[0015] According to another embodiment, the method may be characterized in that information about the operating mode of the motor is obtained. Here, the acquisition may include receiving information about the operating mode from the inverter and alternatively or additionally from the motor. The operating mode may include information about the torque provided by the motor for propelling the working machine. For example, the operating mode may be one of a generator mode, a motor mode, and a torque-free mode. In the generator mode, the motor may operate as a generator, and there may be a negative torque, wherein the torque is transmitted to the motor, for example, via a transmission system. In the motor mode, there may be a positive torque, and in the motor mode, the motor may be configured to provide a torque for propelling the working machine. In the torque-free mode, the torque transmitted from the motor or the torque transmitted to the motor may be less than one or more threshold torques. The method may also be characterized in that if the motor is in the motor mode, a determination is made for a safety critical state. Therefore, if the motor is in, for example, a generator mode or a torque-free mode, it is impossible to make a determination for a safety critical state. Therefore, when a torque is actively transmitted from the motor to propel the working machine, a safety critical state may be determined.

[0016] Thus, the method can take into account the operating mode of the electric machine. In this context, it can be taken into account whether the work machine is actively driving off or merely coasting off. In the case of a coasting off, for example, there can be a torque-free state of the electric machine and in this case, for example, a safety-critical state cannot be determined. Thus, the robustness of the method with respect to incorrect shutdowns can also be increased. Furthermore, a low-voltage inverter can be used in combination with a control device that can execute the method. With such a low-voltage inverter, it may be the case that precise information about the current or past torque at the electric machine is not available. The only information about the torque that may be available is whether this torque is above or below a certain threshold torque, and this can, for example, be sent to the control device in the form of an operating mode in order to execute the method.

[0017] According to another embodiment, the method may be characterized in that a determination of a safety critical state is made if the safety critical state exists for the duration of a tolerance time. For example, the tolerance time may be a few milliseconds, a few hundred or a few tenths of a second or a few seconds. The tolerance time may be parameterizable and alternatively or additionally coded in a control device that can perform the method. Thus, for example, a determination of a safety critical state may be made if the operating mode of the electric machine is in motor mode and the desired direction of travel and the actual direction of travel differ for the duration of the tolerance time.

[0018] Furthermore, specifying a tolerance time makes the method more robust against undesired incorrect shutdowns. Thus, for example, a safety-critical state may not be determined if a prerequisite for determining a safety-critical state exists for a duration shorter than the tolerance time.

[0019] According to another embodiment, the method may be characterized in that a detection of a driver's travel request is performed. The detection may include receiving a signal about the position of one or more pedals of the working machine. The travel request may be, for example, that the driver is depressing the accelerator pedal to halfway. The method may also be characterized in that a determination of the desired travel speed is performed based on the detected travel request. For example, the control device may be configured to perform the determination. For example, in the case where the accelerator pedal is halfway depressed, the value of the desired travel speed may be determined as half of the maximum possible speed of the working machine. The method may also be characterized in that if a comparison of the desired travel speed with the minimum speed shows that the desired travel speed is greater, a determination of a safety critical state is performed. The step of comparing the desired travel speed with the minimum speed may be part of the determination of the safety critical state and may be performed by the control device. For example, the minimum speed may be 3 or 5 km / h.

[0020] With this method, a safety-critical state can be determined if the driver actively wishes to drive to a desired travel speed that exceeds the minimum speed, i.e. wishes to actively drive the work machine away. The method can therefore also be more robust. In this way, for example, if the driver does not press the pedal to request a travel speed, a determination of a safety-critical state may not be made. Here, the determination of a safety-critical state can be prevented simply, for example, by changing the position of the travel direction switch to the forward direction without pressing the accelerator pedal at the same time. In this case, there is no incorrect shutdown of the motor to a state that is not suitable for propulsion.

[0021] A second aspect of the present invention relates to a control device configured to perform a method for controlling a working machine according to an embodiment of the first aspect of the present invention. The control device may include an interface for receiving signals from and sending signals to sensors, actuators, and other control devices.

[0022] A third aspect of the invention relates to a drive unit having an electric machine and a control device according to the second aspect of the invention. The electric machine can have a low-voltage inverter.

[0023] A fourth aspect of the invention relates to a working machine having a vehicle control device, a pedal, a travel direction switch and a drive unit according to the third aspect of the invention. Alternatively, the working machine has more than one pedal. For example, it has a brake pedal and an accelerator pedal. The pedal and the travel direction switch can be electrically connected to the vehicle control device, which in turn can be electrically connected to the drive unit and simultaneously electrically connected to the control device of the drive unit. Signals from the pedal and from the travel direction switch can be sent to the control device via the vehicle control device. In the control device, steps of a method for preventing the working machine from undesirably traveling in the wrong direction can be performed. In addition, the working machine can be configured to transfer the motor to a state that is not suitable for propulsion. The working machine can be a construction machine, an agricultural machine, a transport machine or an off-road vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 shows a schematic diagram of a work machine according to one embodiment;

[0025] Figure 2 Schematically shows the Figure 1 The steps of a method for preventing undesired travel of a work machine in a wrong direction;

[0026] Figure 3a Shows that in the implementation Figure 2 The temporal behavior of the state variables during the method of the steps schematically shown in FIG.

[0027] Figure 3b Shows that there is Figure 2 Alternative temporal characteristics of the method of the steps shown schematically. DETAILED DESCRIPTION

[0028] Figure 1A working machine 14 according to an embodiment of the present invention is schematically shown. The working machine 14 has a drive unit 6 of the present invention. The drive unit 6 has a control device 4 and a motor 2 and a low-voltage inverter (not shown). The motor 2 is electrically connected via the low-voltage inverter and is electrically connected to the control device 4. In addition, the working machine 14 has a vehicle control device 8 electrically connected to the control device 4. The vehicle control device 8 is electrically connected to a pedal 10 and a travel direction switch 12. The vehicle control device 8 is configured to receive and process signals from the pedal 10 and from the travel direction switch 12, and to send these signals to the control device 4. The motor 2 and the low-voltage inverter are configured to send electrical signals to the control device 4. The control device 4 is configured according to Figure 2 The steps schematically shown in exemplify a method for preventing undesired travel of work machine 14 .

[0029] Figure 3a The temporal variation of state variables during the execution of a method for preventing undesired travel of a work machine 14 in the wrong direction is shown by way of example. In this context, the desired direction of travel FRW, the motor speed n, and the operating mode BM are plotted as state variables relative to time t. At time t1, the desired direction of travel FRW changes to forward. At time t2, the desired direction of travel FRW changes to forward. Figure 3b In the alternative case shown, the desired direction of travel FRW is changed to reverse at time t1. This is achieved by the driver changing the position of the direction of travel switch to a position corresponding to the forward direction or, alternatively, the reverse direction. A detection S1 of the desired direction of travel FRW of the driver of the work machine 14 is performed. At time t2, the operating mode BM of the electric machine 2 is changed to the motor mode. This is done in Figure 3a and Figure 3b In the motor mode, the torque for propelling the working machine 14 is provided by the motor 2. This is achieved by the control device 4 activating the inverter and supplying energy to the motor 2 from an energy storage device (not shown). In addition, the acquisition S5 of information about the operating mode BM is performed. The operating mode BM can be determined by the inverter and can be sent to the control device 4 in the form of a signal.

[0030] Since the motor 2 is activated to propel the working machine 14, the working machine 14 is propelled. The detection S2 of the motor speed n as a state variable is performed. Here, the magnitude of the motor speed n increases with time t. Figure 3a The value of the motor speed n decreases. Figure 3b In the alternative case shown, the value of the motor speed n increases and is related to Figure 3a In other words, in Figure 3a and Figure 3b The motor speeds n in the cases shown differ in sign.

[0031] In the detection step S6.1, a detection of the driver's travel request is also performed. The driver can, for example, actuate the pedal 10, wherein the pedal 10 sends information about this actuation to the vehicle control device 8 and also to the control device 4. In step S6.2, a determination of the desired travel speed is performed as a function of the detected travel request. Thus, in the case of a pedal being depressed by 30%, for example, a travel speed of 30% of the maximum speed is determined.

[0032] The method also has a step of determining S3 a safety critical state of the electric machine 2. If within a fault tolerance time T running from time t2 to time t3, the desired direction of travel FRW corresponds to a first direction and the actual direction of travel corresponds to a second direction opposite to the first direction, a safety critical state is determined. Figure 3a , the desired direction of travel FRW is positive, corresponding to the desired direction of travel FRW in the forward direction. Figure 3b In , the desired direction of travel FRW is negative, that is, the desired direction of travel FRW is in the backward direction. Based on the detected motor speed n, a determination S2.1 of the actual direction of travel is performed. Therefore, Figure 3a The negative motor speed n in corresponds to the actual direction of travel in the backward direction, and as Figure 3b As shown, a positive motor speed n corresponds to a forward direction. At the same time, there must be a motor mode that can be used as the operating mode BM of the electric machine 2 in order to determine the safety critical state of the S3 fault tolerance time T. In addition, the detected motor speed n must be within a parameter range P around the motor speed n corresponding to the stationary state of the work machine 14. Figure 3a and Figure 3b In the case shown, the stationary state is defined by a motor speed n equal to zero. In addition, a determination S3.2 is made for the gradient of the motor speed n. If the gradient is greater than a minimum gradient, a determination S3 is made for a safety-critical state. Here, the minimum gradient can be a predetermined minimum gradient and can be stored in the control device 4. If all these prerequisites are present, it is determined at time t3 that a safety-critical state exists.

[0033] In addition, an S4 signal is sent to the motor 2 and simultaneously a signal is sent to the low voltage inverter to transfer the motor 2 to a state that is not suitable for propulsion. This state that is not suitable for propulsion is achieved by sending a safe state query from the control device 4 to the inverter and also to the motor 2. After the motor 2 is transferred to a state that is not suitable for propulsion, the motor 2 is torque-free with respect to the propulsion of the working machine 14. Therefore, there is no power transmission from the motor 2 for propelling the working machine 14.

[0034] Reference numerals

[0035] 2 Motor

[0036] 4 Control device

[0037] 6 drive units

[0038] 8 Vehicle Control Devices

[0039] 10 pedals

[0040] 12 Travel direction switch

[0041] 14Operation machinery

[0042] S1 (Step) Detection of the desired direction of travel

[0043] S2 (step) detection of state variables

[0044] S2.1 (Step) Determination of the actual direction of travel

[0045] S2.2 (Step) Determination of the gradient of the motor speed

[0046] S3 (Step) Determination of safety criticality

[0047] S4 (step) sends a signal for transferring the motor to a state unsuitable for propulsion

[0048] S5 (Step) Obtaining Information About Operation Mode

[0049] S6.1 (Step) Testing of travel requirements

[0050] S6.2 (Step) Determination of the desired travel speed

[0051] BM (value) operation mode

[0052] FRW (value) desired direction of travel

[0053] n (value) motor speed

[0054] P parameter range

[0055] T Fault tolerance time

[0056] t time

[0057] t1 (time) desired change in direction of travel

[0058] t2 (time) Operation mode change

[0059] t3 (time) reaches the safety critical state.

Claims

1. A method for preventing an undesired movement of a work machine (14) in a wrong direction, in, The working machine (14) has a motor (2) for propelling the working machine (14), and the method comprises the following steps: Detecting (S1) a desired direction of travel (FRW) of a driver of the work machine (14); Detecting (S2) a state variable of the working machine (14) related to an actual travel direction of the working machine; determining (S3) whether the motor (2) is in a safety-critical state based on a comparison of the detected desired direction of travel (FRW) and a detected state variable of the work machine; and If it has been determined that a safety-critical state exists, a signal is sent (S4) to the electric motor (2) to transfer the electric motor (2) to a state that is not suitable for propulsion.

2. The method according to claim 1, It is characterized in that The detection (S2) of the state variable related to the actual direction of travel comprises detecting the motor rotation direction of the electric motor (2), and Based on the detected motor rotation direction, a determination is made as to the actual direction of travel (S2.1), and If the determined actual direction of travel differs from the detected desired direction of travel (FRW), the determination of a safety-critical state is performed ( S3 ).

3. The method according to claim 1 or 2, It is characterized in that The detection (S2) of the state variable related to the actual direction of travel comprises detecting a motor speed (n) of the motor (2), and If the detected motor speed (n) is within a parameter range (P) around a motor speed (n) corresponding to a stationary state of the work machine, the determination of a safety-critical state is performed ( S3 ).

4. The method according to claim 3, It is characterized in that Based on the detected motor speed (n), a determination is made for the gradient of the motor speed (n) (S2.2), and If there is a change in the desired direction of travel (FRW) and a comparison of the determined gradient of the motor speed (n) with a minimum gradient shows that the determined gradient is greater, the determination of a safety-critical state is performed ( S3 ).

5. The method according to one of the preceding claims, It is characterized in that Acquiring information about the operating mode (BM) of the electric machine (2) (S5), and If the electric machine (2) is in motor mode, the determination of a safety-critical state is performed (S3).

6. The method according to one of the preceding claims, It is characterized in that If the safety-critical state exists for the duration of the tolerance time (T), the determination of the safety-critical state is performed ( S3 ).

7. The method according to one of the preceding claims, It is characterized in that Performing a detection of the driver's driving request (S6.1), Determining the desired travel speed based on the detected travel requirement (S6.2), and If the comparison of the desired travel speed with the minimum speed shows that the desired travel speed is greater, the determination of the safety-critical state is performed ( S3 ).

8. A control device (4) configured to carry out the method according to one of claims 1 to 7 for controlling a work machine (14).

9. A drive unit (6) comprising an electric motor (2) and a control device (4) according to claim 8.

10. A working machine (14) comprising a vehicle control device (8), a pedal (10), a travel direction switch (12), and a drive unit (6) according to claim 9.

Images