Method for actuating drive train and drive train

Abstract

The invention relates to a method for operating a drive train and to a drive train. The drive train comprises at least a first drive motor (16), a second drive motor (18) and a transmission (20) for receiving drive torques (M1, M2) of the first drive motor (16) and the second drive motor (18). The method comprises the following steps: ascertaining a driver desired torque (MFW); ascertaining a shift position of at least one first shift element (64) of the transmission (20); -calculating the target torque (MS) on the basis of the driver desired torque (MFW), the drive torque (M1) of the first drive motor (16) and the shift position of the at least one first shift element (64) of the transmission (20).

Description

Technical Field

[0001] This invention relates to a method for controlling a drive system in a vehicle according to the preamble of claim 1. The invention also relates to a control device, drive system, vehicle, computer program, and computer-readable medium according to the co-independent claims. Background Technology

[0002] Drive systems for vehicles are known from the prior art, which have one or more drive motors and a transmission for transforming and distributing the driving torque provided by the one or more drive motors. In drive systems with more than one drive motor, especially in hybrid drive systems with electric drive motors and internal combustion engines, or in electric drive systems with multiple electric drive motors, the transmission faces the challenge of receiving the driving torque of multiple drive motors and centrally outputting it to the transmission output.

[0003] Especially in drive systems with two electric drive motors, a target torque needs to be predetermined for each motor. This target torque is primarily derived from the position of the driver's pedal. For precise control of the drive system, this driver-desired torque must be converted into the desired torque of the drive axle.

[0004] DE 10 2019 214 986 A1 discloses an electrically driven vehicle having an electric drive system with two electric drive motors. These electric drive motors are connected via a shiftable transmission, such that the driving torque of the first electric drive motor is transmitted to a first input terminal of the transmission. In a first shift position of the transmission, the driving torque of the second electric drive motor can be additionally transmitted to the same input terminal of the transmission, such that the two driving torques are directly added together. In a second shift position of the transmission, the driving torque of the second electric drive motor can be transmitted to a second input terminal of the transmission, different from the first input terminal, wherein the driving torque is transformed and increased or decreased relative to the driving torque transmitted in the first shift position. Here, the transmission output torque is calculated based on the shift position of the transmission. Summary of the Invention

[0005] The objective of this invention is to improve the functional safety of the drive system and to overcome or at least mitigate the disadvantages known in the prior art.

[0006] This task is solved by a method for controlling a vehicle's drive system, which includes at least: a first drive motor, a second drive motor, and a transmission for receiving the driving torque from the first and second drive motors. The method includes the following steps:

[0007] - Obtain the driver's desired torque;

[0008] - To know the shift position of at least one first shift element of the transmission;

[0009] - The target torque is calculated based on the driver's desired torque, the driving torque of the first drive motor, and the shift position of at least one first shift element of the transmission.

[0010] Here, the vehicle can in principle be any land, water and / or air transport, such as passenger cars, freight cars, buses, autonomous passenger or freight vehicles, emergency vehicles, work vehicles (e.g., forklifts), engineering vehicles such as concrete mixers, excavators, etc., aircraft such as airplanes, helicopters, drones, air taxis, etc., and / or boats or ships, but can also be a motorized two-wheeled vehicle such as a motorcycle or electric bicycle.

[0011] In this respect, a drive system is understood as a unit that enables the movement of a vehicle independent of external forces acting on it, especially independent of gravity. Such a drive system specifically includes a drive motor and a power transmission unit that connects the drive motor to another drive element.

[0012] In this regard, the drive motor is particularly understood as an electric drive motor or an internal combustion engine. Preferably, a drive system with two electric drive motors is provided. Alternatively, the drive system can also be designed as a hybrid drive system, and includes both electric drive motors and an internal combustion engine.

[0013] In this respect, a transmission is understood as a unit that converts the input torque of a drive motor into the output torque at the driven end.

[0014] In this respect, driving torque is understood as the torque generated by one or both of the drive motors.

[0015] In this respect, the driver-desired torque is understood as the driving torque used for the vehicle, which is equivalent to the driving torque desired by the driver and provided by the drive motor.

[0016] In this respect, target torque is understood as the torque of one of the drive motors that is suitable for providing the torque desired by the driver.

[0017] In this respect, the shift position of a transmission is understood as the position in which the driving torque is transmitted to the driven end through the transmission at a fixed gear ratio, or in which the driving torque is not transmitted due to the interruption of the torque transmission connection between the drive motor and the transmission.

[0018] The method according to the present invention enables the functional safety of a drive system with two drive motors to be ensured and the drive system to be protected, especially from damage caused by excessive torque, in a simple and cost-effective manner. Here, the proposed approach for calculating the target torque with respect to the driven end of the transmission is to consider only parameters important for handling, and to disregard other parameters when calculating the target torque.

[0019] Here, existing solutions have shown that condition-dependent calculation of the distribution coefficients of the driver's desired torque to the two drive motors can be inaccurate, unreproducible, and error-prone for use in safety functions. Since the driving functions related to the driver's desired torque and the functions for drive system safety are implemented separately in existing solutions, this requires high computational overhead and correspondingly high computational performance. Deviations due to instability in the obtained values ​​during calculation can lead to error-proneness and a lack of robustness in the functional safety features. By using the method according to the present invention, the required computational performance can be reduced and the robustness related to functional safety can be improved because only the actual torque that is excessively large compared to the target torque is important for functional safety. Torques below the target torque are not critical for functional safety.

[0020] In a typical implementation of this method, the target torque is calculated based on the following assumption: the second drive motor is connected to the first drive motor such that the driving torque of the first drive motor and the driving torque of the second drive motor are transmitted to the transmission via a common input terminal. This simplifies the input conditions for calculating the target torque, thereby further reducing the required computational performance and improving the robustness of the calculation method. Therefore, the shifting position of the shifting element connecting the second drive motor and the first drive motor can be ignored when calculating the target torque.

[0021] In a favorable design of this method, the target torque is calculated based on the assumption that the second drive motor is torque-transmittingly connected to the first drive motor, wherein the calculation does not depend on the actual connection between the first and second drive motors. This assumption means that the known torque is greater than or equal to the actual torque. This simplification is possible because a torque below the target torque is not critical for functional safety.

[0022] In a favorable design of this method, the calculation of the target torque is based on the assumption that the total desired torque for the driver is generated by the first drive motor. This assumption further simplifies the calculation method.

[0023] According to a preferred embodiment of the method, the calculation of the target torque does not depend on the distribution coefficient between the actual driving torque of the first drive motor and the actual driving torque of the second drive motor. By calculating only the driving torque at the input of the transmission (without distributing it to both drive motors), the method for controlling the drive system can be simplified accordingly, thereby improving functional safety.

[0024] In another advantageous design of this method, it is specified that when the first shift element is in a shift position that connects the second drive motor to the transmission in a torque-transmitting manner, the target torque is calculated via a selected gear ratio of the transmission. In a shift position where the second drive motor is disengaged from the transmission and does not transmit torque, the calculation is performed through a fictitious connection with a fixed gear ratio.

[0025] In a typical implementation, the transmission is a shiftable multi-speed transmission, wherein, when the second drive motor is connected to the transmission to transmit torque, the target torque is calculated using the gear ratio of the selected gear. In the shifting position where the second drive motor is disengaged from the transmission and does not transmit torque, the target torque is calculated by assuming a minimum gear ratio for the transmission. Therefore, in the neutral position or during gear shifting, a relatively large driven torque is always predetermined as the target torque.

[0026] Another aspect of the invention relates to a control device for manipulating a drive system in a vehicle, wherein the control device is operatively connected to a transmission and two drive motors of the drive system. The control device is configured to perform the methods described in the preceding paragraphs, particularly when machine-readable computer program code is executed via the control device.

[0027] Another aspect of the invention relates to a drive system for a vehicle, the drive system having a first drive motor and a second drive motor. Here, the transmission of the drive system is connected to the first and second drive motors on the input side. The drive system also includes the control device described in the previous paragraph for operating these drive motors and the transmission.

[0028] In a preferred design and embodiment of the drive system, the first drive motor is a first electric motor, and the second drive motor is a second electric motor.

[0029] Another aspect of the invention relates to a computer program comprising instructions that, when implemented by a computer, cause the computer to perform one of the methods described above. Here, the computer program may also be referred to as a computer program product.

[0030] Another aspect of the invention relates to a computer-readable medium having computer program code for performing the methods described in the foregoing paragraphs to operate a drive system in a vehicle. However, the term "computer-readable medium" should be understood herein, in particular, but not only, as: hard disks and / or servers and / or memory sticks and / or flash memory and / or DVDs and / or Blu-ray discs and / or CDs. Additionally, the term "computer-readable medium" is also understood to mean a data stream, formed, for example, when downloading computer programs and / or computer program products from the Internet. Attached Figure Description

[0031] The invention will now be briefly described with reference to the accompanying drawings. Herein:

[0032] Figure 1 A schematic diagram of a drive system for a vehicle is shown, which is operated by a method for operating the drive system according to the present invention.

[0033] Figure 2 A preferred embodiment of a drive system for a vehicle according to the invention is shown, wherein the drive system is operated by a method for operating the drive system according to the invention.

[0034] Figure 3 A schematic diagram of a preferred embodiment of a drive system for a vehicle according to the present invention is shown;

[0035] Figure 4 A vehicle having a drive system according to the invention is shown;

[0036] Figure 5 A table showing the gear ratios for output torque is provided; these ratios depend on the operation of the drive motor and the shift positions in the transmission of the drive system.

[0037] Figure 6 A flowchart is shown illustrating a method for executing a drive system for controlling a vehicle according to the present invention. Detailed Implementation

[0038] Figure 1 A schematic diagram of the drive system 12 of the vehicle 10 is shown. The drive system 12 includes: an energy supply unit 14; a first drive motor 16 connected to the energy supply unit 14; and a second drive motor 18 connected to the energy supply unit 14. The first drive motor 16 and the second drive motor 18 are connected to the driven end 42 via a common transmission 20, wherein the transmission 20 is implemented as a torque superposition transmission, which can receive the driving torque M1 of the first drive motor 16 and the driving torque M2 of the second drive motor 18 individually or jointly and transfer them to the driven end 42.

[0039] exist Figure 2 The diagram illustrates a preferred embodiment of the drive system 12 for a vehicle 10. The drive system 12 includes an energy supply unit 14 configured as a high-voltage battery 40. This high-voltage battery 40 can be, in particular, but is not limited to, a lithium-ion battery, a lithium iron phosphate battery, a solid electrolyte battery, or a sodium-ion battery. The drive system 12 also includes a first inverter 44 that connects the energy supply unit 14 to a first drive motor 16. In this embodiment, the first drive motor 16 is designed as a first electric drive motor 46. The drive system 12 also includes a second inverter 45 that connects the energy supply unit 14 to a second drive motor 18. The second drive motor is designed as a second electric drive motor 48.

[0040] The first electric drive motor 46 and the second electric drive motor 48 are connected to a common transmission 20, which is implemented as a torque superposition transmission, particularly as a planetary transmission 22. The transmission 20 has a driven end 42, through which the driving torque M1 of the first drive motor 16 and / or the driving torque M2 of the second drive motor 18 are transmitted to the drive axle 50 of the vehicle 10.

[0041] exist Figure 3 The diagram shows a preferred embodiment of a drive system 12 for a vehicle 10 according to the invention. The drive system 12 has a first electric drive motor 46 and a second electric drive motor 48, which are connected to a common driven end 42 via a planetary transmission 22. The driven end 42 is connected to a differential 56 of a drive axle 50, which distributes driving torque to the driven wheels 52, 54 of the drive axle 50 via an axle transmission mechanism 90.

[0042] The planetary transmission 22 has a first ring gear 24, which is operatively connected to the first planet gear 28 of the first planetary gear set 72 via a first toothed portion 30. The driving torque M1 of the first electric drive motor 46 is transmitted to the first planet gear 28 of the first planetary gear set 72 via the first sun gear 26 of the first planetary gear set 72 through the second toothed portion 32. The planet gears 28 of the first planetary gear set 72 are connected to and drive the second ring gear 76 of the second planetary gear set 74 via a first planet carrier. The second ring gear 76 is engaged with the second planet gears 78 of the second planetary gear set 74 via a third toothed portion 34, and these second planet gears are engaged with the second sun gear 79 of the second planetary gear set 74 via a fourth toothed portion 36. The planet carrier of the second planetary gear set 74 forms the driven end 42 of the planetary transmission 22, which is connected to the differential 56 of the drive axle 50. Drive torque is distributed to the driven first wheel 52 and driven second wheel 54 of the drive axle 50 via the differential 56 and another axle drive mechanism 90.

[0043] The second electric drive motor 48 can be connected to the first electric drive motor 46 via the second shifting element 38 through the first shifting path 58. Furthermore, the second electric drive motor 48 can be connected to the first shifting element 64 via the second shifting path 60. A neutral position 62 is provided between the first shifting path 58 and the second shifting path 60, in which the second electric drive motor 48 does not transmit torque.

[0044] The first shift element 64 can achieve three different gear ratios for the second electric drive motor 48. In the first shift path 66 of the first shift element 64, the driving torque M2 of the second electric drive motor 48 is transmitted to the second sun gear 79 of the planetary transmission 22. In the second shift path 68, the torque of the second electric drive motor 48 is transmitted to the planet carrier of the second planetary gear set 74 of the planetary transmission 22. In the third shift path 70, the torque of the second electric drive motor 48 is transmitted to the first sun gear 26 of the planetary transmission 22. Furthermore, the first shift element 64 can achieve neutral positions 62, in which no torque is transmitted to the planetary transmission 22.

[0045] The drive system 12 also includes a control device 80 for controlling the first drive motor 16 and the second drive motor 18. Furthermore, the control device 80 is connected to the planetary transmission 22 to process signals from the planetary transmission 22, particularly the shift positions of the shift elements 38 and 64, and takes these signals into account when controlling the drive system 12. The control device 80 has a storage unit 82 and a computing unit 84. The storage unit 82 stores computer program code 86 for implementing the method for controlling the drive system 12 according to the invention, and the drive system executes this method when the computer program code 86 is implemented by the computing unit 84.

[0046] exist Figure 4 The diagram illustrates a vehicle 10 having a drive system 12 according to the invention. The vehicle 10 has an energy supply system 14 including a high-voltage battery 40. The drive system 12 also includes a first inverter 44 that connects the energy supply unit 14 to a first drive motor 16. In this embodiment, the first drive motor 16 is designed as a first electric drive motor 46. The drive system 12 also includes a second inverter 45 that connects the energy supply unit 14 to a second drive motor 18. The second drive motor is designed as a second electric drive motor 48.

[0047] The first electric drive motor 46 and the second electric drive motor 48 are connected to a common transmission 20, which is implemented as a torque superposition transmission, particularly as a planetary transmission 22. The transmission 20 has a driven end 42 through which the driving torque M1 of the first drive motor 16 and / or the driving torque M2 of the second drive motor 18 are transmitted to the drive axle 50 of the vehicle 10. The vehicle 10 also has a non-driven second axle 92.

[0048] exist Figure 5 A table is shown that discloses exemplary gear ratios for the output torque of the transmission 20, which depend on the shift positions of the first shift element 64 and the second shift element 38 of the transmission 20 and the input torque of the drive motors 16 and 18. It can be seen here that three different gear ratios can be achieved by the transmission 20.

[0049] exist Figure 6 The diagram shows a flowchart of a method for controlling a drive system 12 of a vehicle 10 according to the invention, the drive system having at least: a first drive motor 16, particularly a first electric drive motor 46; a second drive motor 18, particularly a second electric drive motor 48; and a transmission 20 implemented as a planetary transmission 22, wherein the planetary transmission 22 is connected to the first drive motor 16 and the second drive motor 18 on the input side, and as a torque superposition transmission transmits the driving torque M1 of the first drive motor 16 and the driving torque M2 of the second drive motor 18 to a common driven end 42.

[0050] In the method steps <100> In the process, the driver's desired torque M is obtained. FW In the method steps <110> In this process, the shift position of the first shift element 64 of the transmission 20 is detected. Here, the method steps... <100> and <110> They can be performed sequentially or in parallel in any order. (In the method steps) <120> In the middle, based on the driver's desired torque M FW The target torque M is determined by the driving torque M1 of the first drive motor 16 and the shift position of the first shift element 64 of the transmission 20. S .

[0051] Here, the target torque M is calculated. S The method is as follows: Based on the transmission geometry of transmission 20, one of the shift elements 38 and 64 is designated as the important and decisive shift element 64, while the other shift element 38 is considered unimportant. This is particularly true in transmission 20... Figure 3 In the geometry described herein, this is made possible by the geometry of the transmission 20. Here, the first shift element 64 is considered an important shift element, while the positioning of the second shift element 38 is ignored.

[0052] In addition, in order to calculate the target torque M S And assuming: the total driver's desired torque M FW This is generated by the drive motor 16, that is, by the first drive motor 16 in the geometry described for the drive system 12. Similarly, it is assumed here that the second shift element 38 is always in a shift position in which the second drive motor 18 is connected to the first drive motor 16 via the first shift path 58.

[0053] Driver's desired torque M FW The gear ratio for the target torque M is determined by the shift position of the first shift element 64 via respective shift paths 66, 68, and 70. S Perform the conversion.

[0054] If the first shift element 64 is in a neutral shift position, then it should rely on the driver's desired torque M. FW The target torque M is calculated using the gear ratio of the first shift path 66. S If the first shift element 64 is in a neutral position between the second shift path 68 and the third shift path 70, then it should depend on the driver's desired torque M. FW The target torque M is calculated using the gear ratio of the second shift path 68. S Therefore, in the neutral position or when shifting gears, a larger driven torque is always predetermined as the target torque M. S .

[0055] The advantage of this calculation method is that it eliminates the need for error-prone calculations and significantly simplifies the calculation of the target torque M. S The calculations are performed without needing to separately calculate the two torques and the distribution coefficient, significantly reducing the required computational power. Furthermore, the calculations can be performed independently of the shift position of the second shift element 38. Thus, a method is provided in a simple manner that achieves sufficient accuracy regarding the handling and functional safety of the drivetrain 12. Moreover, vehicle usability is improved by avoiding or reducing erroneous interventions used to ensure the functional safety of the drivetrain 12.

[0056] This invention is not limited to the described embodiments. The scope of protection is defined by the claims.

[0057] In principle, all methods described in the specification or claims can be performed by a device that includes means for performing the corresponding method steps.

[0058] Figure Labels

[0059] 10 vehicles

[0060] 12 drive system

[0061] 14 Energy Supply Department

[0062] 16 First drive motors

[0063] 18 Second drive motor

[0064] 20 transmission

[0065] 22 planetary transmission

[0066] 24 First gear ring

[0067] 26 First Sun Wheel

[0068] 28 First Planetary Wheel

[0069] 30 First tooth

[0070] 32 Second tooth

[0071] 34 Third tooth

[0072] 36 Fourth tooth

[0073] 38 Second shift element

[0074] 40 high voltage battery

[0075] 42 fuel tanks

[0076] 44 First Inverter

[0077] 44 Second Inverter

[0078] 46 First Electric Motor

[0079] 48 Second Electric Motor

[0080] 50 First Axle / Drive Axle

[0081] 52 First Round

[0082] 54 Second Round

[0083] 56 differential

[0084] 58 First Shift Path

[0085] 60 Second Shift Path

[0086] 62 Neutral Positions

[0087] 64 First shift element

[0088] 66 First Shift Path

[0089] 68 Second Shift Path

[0090] 70 Third Shift Path

[0091] 72 First Planetary Gear Set

[0092] 74 Second Planetary Gear Set

[0093] 76 Second Gear

[0094] 78 Second Planetary Wheel

[0095] 79 Second Sun Wheel

[0096] 80 control equipment

[0097] 82 memory units

[0098] 84 computing units

[0099] 86 Computer Program Code

[0100] 90 Axle Transmission Mechanism

[0101] 92 Second Axle

[0102] The driving torque of the M1 first drive motor

[0103] The driving torque of the M2 second drive motor

[0104] M FW Driver's desired torque

[0105] M S Target torque

Claims

1. A method for operating a drive system (12) of a vehicle (10), the drive system having at least: a first drive motor (16), a second drive motor (18), and a transmission (20) for receiving drive torques (M1, M2) of the first drive motor (16) and the second drive motor (18), the method comprising the following steps: - Obtain the driver's desired torque (M FW ); - To know the shift position of at least one first shift element (64) of the transmission (20); - Based on the driver's desired torque (M) FW The target torque (M1) is calculated by considering the driving torque (M1) of the first drive motor (16) and the shift position of at least one first shift element (64) of the transmission (20). S ).

2. The method according to claim 1, characterized in that, The target torque (M) S The calculation is based on the following assumption: the second drive motor (18) is connected to the first drive motor (16) such that the driving torque (M1) of the first drive motor (16) and the driving torque (M2) of the second drive motor (18) are transmitted to the transmission (20) via a common input terminal.

3. The method according to claim 2, characterized in that, The calculation is based on the following assumption: the second drive motor (18) is connected to the first drive motor (16) in a torque-transmitting manner, wherein the target torque (M) S The calculation of ) does not depend on the actual connection between the first drive motor (16) and the second drive motor (18).

4. The method according to any one of claims 1 to 3, characterized in that, The target torque (M) S The calculation of ) is based on the following assumption: the total driver's desired torque (M FW The ) is generated by the first drive motor (16).

5. The method according to any one of claims 1 to 4, characterized in that, The target torque (M) S The calculation of ) does not depend on the distribution coefficient between the actual driving torque (M1) of the first drive motor (16) and the actual driving torque (M2) of the second drive motor (18).

6. The method according to any one of claims 1 to 5, characterized in that, When the first shift element (64) is in a shift position that connects the second drive motor (18) to the transmission (20) in a torque-transmitting manner, the target torque (M) S The calculation is performed by conversion via the selected gear ratio of the transmission (20); while in the shift position where the second drive motor (18) is disengaged from the transmission (20), the calculation is performed by a fictitious connection with a fixed gear ratio.

7. The method according to claim 6, characterized in that, The transmission (20) is implemented as a shiftable multi-speed transmission, wherein, when the second drive motor (18) is connected to the transmission (20) in a torque-transmitting manner, the target torque (M) S The calculation of the target torque is performed by the gear ratio of the selected gear of the transmission (20); while in the shift position where the second drive motor (18) is disengaged from the transmission (20), the calculation of the target torque is performed by assuming the minimum gear ratio of the transmission (20).

8. A control device (80) for operating the drive system (12) in the vehicle (10), wherein, The control device (40) is operatively connected to the transmission (20) of the drive system (12) and the two drive motors (16, 18) and is configured to perform the method according to any one of claims 1 to 7.

9. A drive system (12) for a vehicle (10), said drive system comprising: First drive motor (16); second drive motor (18). and a transmission (20) connected on the input side to the first drive motor (16) and the second drive motor (18); and a control device (80) according to claim 8.

10. The drive system (12) according to claim 9, wherein, The first drive motor (16) is a first electric motor (46) and the second drive motor (18) is a second electric motor (48).

11. A vehicle (10) having a drive system (12) according to claim 9 or 10.

12. A computer program comprising instructions that, when implemented by a computer, cause the computer to perform the method according to any one of claims 1 to 7.

13. A computer-readable medium, characterized in that, The computer-readable medium includes computer program code (86) for performing the method according to any one of claims 1 to 7.

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