Vehicle drive system

Abstract

To enable a vehicle to travel only by the driving force of rear wheels out of front wheels and the rear wheels even under the condition that an engine is operated.SOLUTION: The vehicle drive system 20 includes a front wheel system drive unit 30 that has an engine 31 and a second motor generator 33 and adjusts the driving force of the front wheels 11, and a rear wheel system drive unit 40 that has a third motor generator 41 and adjusts the driving force of the rear wheels 12. When the rear-wheel drive mode is selected while the engine 31 is being operated, the control device 50 of the system controls the driving force of the rear wheels 12 by driving the third motor generator 41 after offsetting the output torque of the engine 31 with the output torque of the second motor generator 33.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle drive system. [Background technology]

[0002] Patent Document 1 discloses a vehicle control device that can adjust the driving force of the front wheels by the engine and can adjust the driving force of the rear wheels by the electric motor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-102420 Summary of the Invention [Problem to be solved by the invention]

[0004] A rear-wheel drive mode may be provided as a driving mode selectable by a vehicle driver. The rear-wheel drive mode is a mode in which the vehicle is driven only by the driving force of the rear wheels out of the front wheels and the rear wheels.

[0005] If the driver selects rear-wheel drive mode while the engine is running, the engine output torque may be transmitted to the front wheels, making it impossible to run the vehicle using only the driving force of the rear wheels. [Means for solving the problem]

[0006] A vehicle drive system for solving the above problems includes a front-wheel drive unit having an engine and a front-wheel motor and adjusting the drive force of the front wheels, a rear-wheel drive unit having a rear-wheel motor and adjusting the drive force of the rear wheels, and a control device that controls the front-wheel drive unit and the rear-wheel drive unit. When a rear-wheel drive mode is selected as the vehicle driving mode while the engine is operating, the control device drives the front-wheel motor so that the output torque of the engine is offset by the output torque of the front-wheel motor, and drives the rear-wheel motor to control the drive force of the rear wheels. [Effects of the Invention]

[0007] To enable a vehicle to travel only by the driving force of the rear wheels out of the front wheels and the rear wheels even when the engine is running. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a vehicle equipped with a vehicle drive system according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing a series of processes executed by the control device provided in the vehicle drive system of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of a vehicle drive system will be described with reference to FIGS. 1 shows a vehicle 10 equipped with a vehicle drive system 20. The vehicle 10 has a plurality of front wheels 11 and a plurality of rear wheels 12. The vehicle 10 is a hybrid vehicle that can generate driving force from both the front wheels 11 and the rear wheels 12.

[0010] <Vehicle drive system configuration> The vehicle drive system 20 includes a front wheel drive unit 30 that adjusts the drive force of the front wheels 11, a rear wheel drive unit 40 that adjusts the drive force of the rear wheels 12, and a control device 50 that controls the front wheel drive unit 30 and the rear wheel drive unit 40.

[0011] The front-wheel drive unit 30 includes an engine 31, a first motor generator 32, a second motor generator 33, and a planetary gear mechanism 34. The planetary gear mechanism 34 includes a sun gear 34s, a ring gear 34r, a pinion gear 34p, and a carrier 34c. A crankshaft 31a of the engine 31 is connected to the pinion gear 34p via the carrier 34c. An output shaft 32a of the first motor generator 32 is connected to the sun gear 34s. An output shaft 33a of the second motor generator 33 is connected to the ring gear 34r via another gear mechanism 35.

[0012] The output torque of the front-wheel drive unit 30 is transmitted to the front wheels 11 via the front-wheel differential 15F. In other words, the front-wheel drive unit 30 can adjust the driving force of the front wheels 11 by coordinating the engine 31, the first motor generator 32, and the second motor generator 33. In this embodiment, the second motor generator 33 corresponds to the "front-wheel motor."

[0013] The rear-wheel drive unit 40 includes a third motor generator 41. The third motor generator 41 corresponds to the "rear-wheel motor." The output torque of the rear-wheel drive unit 40 is transmitted to the multiple rear wheels 12 via a rear-wheel differential 15R. In other words, the rear-wheel drive unit 40 can adjust the driving force of the rear wheels 12 by driving the third motor generator 41.

[0014] <Control device> An example of the control device 50 is an electronic control device. In this case, the control device 50 has a CPU 51 and a memory 52. ​​The memory 52 stores a control program executed by the CPU 51. The control program in the memory 52 is executed by the CPU 51, so that the control device 50 can control the front wheel drive unit 30 and the rear wheel drive unit 40.

[0015] A four-wheel drive mode and a rear-wheel drive mode are available as driving modes of the vehicle 10 that can be selected by the driver of the vehicle 10. The four-wheel drive mode is a mode in which the vehicle 10 is driven by generating driving force from both the front wheels 11 and the rear wheels 12. The rear-wheel drive mode is a mode in which the vehicle 10 is driven by generating driving force only from the rear wheels 12, out of the front wheels 11 and the rear wheels 12.

[0016] <Processing flow executed by the control device> A series of processes executed by the control device 50 will be described with reference to FIG. In step S11, the control device 50 determines whether the rear-wheel drive mode has been selected as the driving mode. If the rear-wheel drive mode has been selected (S11: YES), the control device 50 proceeds to step S15. If the rear-wheel drive mode has not been selected (S11: NO), that is, if the four-wheel drive mode has been selected, the control device 50 proceeds to step S13.

[0017] In step S13, the control device 50 controls the front-wheel drive unit 30 and the rear-wheel drive unit 40 so that drive force is generated at both the front wheels 11 and the rear wheels 12. The proportion of the drive force of the front wheels 11 in the total drive force, which is the drive force of the entire vehicle, is defined as the front-wheel drive proportion. At this time, the control device 50 controls the front-wheel drive unit 30 and the rear-wheel drive unit 40 so as to satisfy the following conditions:

[0018] The sum of the driving force of the front wheels 11 and the driving force of the rear wheels 12 is equal to the required total driving force. - The front-wheel drive ratio is equal to the specified ratio. Then, the control device 50 temporarily ends the series of processes shown in FIG.

[0019] In step S15, the control device 50 determines whether the engine 31 is operating. If the engine 31 is operating (S15: YES), the control device 50 proceeds to step S17. On the other hand, if the engine 31 is not operating (S15: NO), the control device 50 proceeds to step S19.

[0020] In step S17, the control device 50 executes a process for reducing the front wheel driving force to zero. In the process for reducing the front wheel driving force to zero, the control device 50 drives the second motor generator 33 so that the output torque of the engine 31 is offset by the output torque of the second motor generator 33. For example, the control device 50 drives the second motor generator 33 so that the front wheel output torque transmitted from the front wheel drive unit 30 to the front wheel differential 15F becomes 0 (zero). Then, the control device 50 proceeds to step S19.

[0021] In step S19, the control device 50 executes a rear-wheel drive process to adjust the driving force of the rear wheels 12. In the rear-wheel drive process, the control device 50 drives the third motor-generator 41 so that the driving force of the rear wheels 12 becomes equal to the required value of the total driving force. Thereafter, the control device 50 temporarily ends the series of processes shown in FIG. 2.

[0022] <Actions and Effects of This Embodiment> The rear-wheel drive mode may be selected while the engine 31 is operating. In this case, the control device 50 drives the second motor generator 33 so that the output torque of the engine 31 is offset by the output torque of the second motor generator 33. This allows the control device 50 to make the driving force of the front wheels 11 zero even when the engine 31 is operating. In this state, the control device 50 drives the third motor generator 41 to control the driving force of the rear wheels 12. This allows the control device 50 to run the vehicle 10 using only the driving force of the rear wheels 12, out of the front wheels 11 and rear wheels 12, even when the engine 31 is operating.

[0023] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0024] The front wheel drive unit may have a different configuration from the front wheel drive unit 30 shown in FIG. 1, as long as it has an engine and a front wheel mode. [Explanation of symbols]

[0025] 10...vehicle, 11...front wheels, 12...rear wheels, 20...vehicle drive system, 30...front wheel drive unit, 31...engine, 32...first motor generator, 33...second motor generator, 40...rear wheel drive unit, 41...third motor generator, 50...control device

Claims

[Claim 1] a front wheel drive unit having an engine and a front wheel motor and adjusting the driving force of the front wheels; a rear wheel drive unit having a rear wheel motor and adjusting the driving force of the rear wheels; a control device that controls the front wheel drive unit and the rear wheel drive unit, The control device When the rear-wheel drive mode is selected as the vehicle driving mode while the engine is operating, driving the front wheel motor so that the output torque of the engine is offset by the output torque of the front wheel motor; and driving the rear wheel motor to control the driving force of the rear wheels. Vehicle drive system.

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