Hybrid all-wheel drive vehicle

Abstract

To provide a two motor type hybrid all-wheel-drive vehicle which can perform regeneration by a front-wheel at the time of deceleration, and realize ideal front and rear wheel driving force distribution when shifting from EV travel, restarting an engine, to HEV travel.SOLUTION: A hybrid all-wheel-drive vehicle 1 comprises: a first clutch 42 which is mounted between a second motor generator 12 and a front wheel; and a second clutch 51 which is mounted between the second motor generator 12 and a rear wheel. HEV-CU80 makes the first clutch 42 engaged at the time of regeneration and release the second clutch 51, and makes the first motor generator 11 activate to re-start an engine 10 when shifting from EV travel by the second motor generator 12 to HEV travel, and the HEV-CU also adjusts fastening power of the first clutch 42 and the second clutch 51 and output torque of the second motor generator 12 to compensate the drive torque of the front wheel with the second motor generator 12 while keeping the drive torque of the rear wheel.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hybrid all-wheel drive vehicle, and particularly to a two-motor type hybrid all-wheel drive vehicle.

Background Art

[0002] In recent years, hybrid electric vehicles (HEVs) that can effectively improve the fuel consumption rate (fuel efficiency) of vehicles by using both an engine and a motor generator (electric motor) have been widely put into practical use. On the other hand, conventionally, all-wheel drive (AWD) vehicles (or four-wheel drive (4WD) vehicles) that are excellent in running performance on steep slopes, rough roads with many unevennesses, and slippery road surfaces (for example, snowy roads and muddy roads) have been widely put into practical use.

[0003] Here, a three-motor type hybrid all-wheel drive system that combines a two-motor HEV system for front-wheel drive and a motor for rear-wheel drive is known. However, in the three-motor type hybrid all-wheel drive system, an increase in the number of parts, a cost increase due to system complexity, and a deterioration in fuel efficiency due to an increase in weight and spin loss are inevitable. Therefore, in order to avoid an increase in the number of parts and system complexity and suppress an increase in weight and spin loss (that is, to suppress a cost increase and fuel efficiency deterioration), a hybrid all-wheel drive system capable of distributing driving force to the front and rear with two motors has been desired.

[0004] As such a two-motor type hybrid all-wheel drive system, Patent Document 1 discloses a hybrid all-wheel drive system including a differential mechanism and a differential limiting clutch between a first electric motor MG1 connected to a front wheel so as to be torque-transmittable and a second electric motor MG2 connected to a rear wheel so as to be torque-transmittable.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the configuration of the two-motor type hybrid all-wheel drive system disclosed in Patent Document 1, when differential restriction is applied during braking, spinning due to simultaneous locking of the front and rear wheels is likely to occur (i.e., due to the constraint of differential restriction). Therefore, it is difficult to regenerate from the front wheels where the load moves during braking, and regeneration can only be obtained from the rear wheels. As a result, the amount of regeneration decreases (generally, the braking force ratio between the front and rear wheels is 7:3 to 8:2).

[0007] Also, when switching from motor driving (EV driving) by a motor generator to hybrid driving (HEV driving) by an engine and a motor generator, that is, when restarting the engine with the first motor MG1, if the first motor MG1 attempts to lift the rotation of the engine, a decelerating force is generated on the front and rear wheels by the reaction force. If an attempt is made to cancel this reaction force with the output of the second motor MG2, the driving force of the rear wheels increases and the front-rear drive distribution balance deteriorates, and the vehicle behavior is likely to become unstable, for example, during a low-μ road turn (i.e., the vehicle tends to spin). If differential restriction torque is applied to suppress the imbalance of the front and rear driving forces, there is a risk of increasing the tight corner braking phenomenon, for example, during a high-μ road large steering turn. That is, when switching from EV driving to restarting the engine and switching to HEV driving, an ideal front-rear driving force distribution cannot be achieved.

[0008] The present invention has been made to solve the above problems, and in a two-motor type hybrid all-wheel drive vehicle equipped with an engine and two motor generators, it is possible to regenerate at the front wheels during deceleration, and when switching from EV driving (motor driving) by a motor generator to HEV driving (hybrid driving) by restarting the engine and using the engine and the motor generator, an object of the present invention is to provide a hybrid all-wheel drive vehicle capable of realizing an ideal front-rear driving force distribution.

Means for Solving the Problems

[0009] In a hybrid all-wheel drive vehicle according to one aspect of the present invention, in a hybrid all-wheel drive vehicle including an engine, a first motor generator, and a second motor generator as driving force sources, a first clutch interposed between the second motor generator and the front wheels, a second clutch interposed between the second motor generator and the rear wheels, and a control unit that controls the engine, the first motor generator, the second motor generator, the first clutch, and the second clutch based on the running state of the vehicle. The first motor generator is connected to be torque-transmittable to the engine and is also connected to be torque-transmittable to the front wheels. The control unit engages the first clutch and disengages the second clutch during regeneration, and when restarting the engine from motor running by the second motor generator and shifting to hybrid running, while operating the first motor generator to restart the engine, the engagement forces of the first clutch and the second clutch are adjusted and the output torque of the second motor generator is adjusted so as to compensate for the driving torque of the front wheels with the second motor generator while maintaining the driving torque of the rear wheels.

[0010] According to the hybrid all-wheel drive vehicle of the present invention, during regeneration, the first clutch is engaged and the second clutch is disengaged. Therefore, the second motor generator and the front wheels are directly connected, and the regenerative energy can be efficiently recovered from the front wheels. Also, at that time, since the second clutch is disengaged, the differential limiting torque becomes zero, and the vehicle can be prevented from having a spinning tendency.

[0011] Also, when the engine is restarted and the vehicle shifts from motor driving (EV driving) by the second motor-generator to hybrid driving (HEV driving), while the first motor-generator is operated (driven) to restart the engine, the engagement forces of the first clutch and the second clutch are adjusted (controlled) and the output torque of the second motor-generator is adjusted so as to compensate for the driving torque of the front wheels by the second motor-generator while maintaining the driving torque of the rear wheels. Therefore, for example, by controlling the second clutch to a semi-engaged state to transmit appropriate torque to the rear wheels and engaging the first clutch, the output torque of the second motor-generator can also be transmitted to the front wheels. Thus, when driving the first motor-generator to lift the engine rotation and restart the engine, it is possible to cancel the reaction force acting on the front wheels while maintaining an ideal front-rear driving force distribution.

Advantages of the Invention

[0012] As a result, according to the present invention, in a two-motor type hybrid all-wheel drive vehicle equipped with an engine and two motor-generators, it is possible to regenerate at the front wheels during deceleration, and when shifting from EV driving (motor driving) by the motor-generator to HEV driving (hybrid driving) by the engine and the motor-generator, it is possible to realize an ideal front-rear driving force distribution.

Brief Description of the Drawings

[0013]

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Embodiments for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts will be denoted by the same reference numerals. Also, in each figure, the same elements will be denoted by the same reference numerals and redundant explanations will be omitted.

[0015] First, with reference to FIG. 1, the configuration of the hybrid all-wheel drive vehicle 1 according to the embodiment will be described. FIG. 1 is a skeleton diagram showing the configuration of the hybrid all-wheel drive vehicle 1 and a block diagram showing the configuration of its control system.

[0016] A power split mechanism 30 is connected to a crankshaft 10a of an engine 10 via a pair of gears 21. The power split mechanism 30 is composed of a plurality of gears, shafts, etc., and is connected to a drive train 15 that transmits torque to drive wheels and a first motor-generator (MG) 11. The power split mechanism 30 has, for example, a planetary gear mechanism (corresponding to the first planetary gear described in the claims) composed of a sun gear 30a, a ring gear 30b, a pinion gear 30c, and a carrier 30d, and splits and transmits the drive torque generated from the engine 10 to the drive train 15 and the first motor-generator 11.

[0017] More specifically, the carrier 30d is connected to the crankshaft 10a of the engine 10 via a pair of gears 21. The sun gear 30a is connected to the first motor-generator 11. On the other hand, the ring gear 30b is connected to a propeller shaft (rear wheel output shaft) 50 constituting the drive train 15 via a pair of gears (counter gears) 31, and is further connected to a front drive shaft (front wheel output shaft) 60 via a drive reduction gear 43.

[0018] When the first motor-generator 11 functions as a generator, the power distribution mechanism 30 distributes the torque (driving force) from the engine 10 input from the carrier 30d to both the sun gear 30a and the ring gear 30b according to their respective gear ratios. On the other hand, when the first motor-generator 11 functions as a motor, the power distribution mechanism 30 integrates the torque from the engine 10 input from the carrier 30d and the torque from the first motor-generator 11 input from the sun gear 30a and outputs the integrated torque to the ring gear 30b. The torque output to the ring gear 30b is output to the propeller shaft 50 constituting the drive train 15 via a pair of gears (counter gears) 31, and is further output to the front drive shaft 60 via the drive reduction gear 43. Therefore, the first motor-generator 11 is connected to the engine 10 so as to be torque-transmittable, and is also connected to the front wheels 5FL and 5FR so as to be torque-transmittable. Further, the engine 10 can be started and restarted by the driving torque of the first motor-generator 11.

[0019] On the other hand, a second motor-generator (MG) 12 is also connected to the drive train 15. More specifically, the second motor-generator 12 is connected to the propeller shaft 50 via the motor reduction gear 41. Further, the second motor-generator 12 is connected to the front drive shaft 60 via a drive reduction gear mechanism 40 composed of the motor reduction gear 41 and the drive reduction gear 43. The front drive shaft 60 transmits torque to and from the front wheels 5FL and 5FR. The propeller shaft 50 transmits torque to and from the rear wheels 5RL and 5RR.

[0020] Here, between the motor reduction gear 41 and the drive reduction gear 43 (that is, between the second motor-generator 12 and the front wheels 5FL, 5FR), a first clutch 42 for adjusting the torque transmitted between the second motor-generator 12 and the front wheels 5FL, 5FR is interposed. Also, on the propeller shaft 50 (between the second motor-generator 12 and the rear wheels 5RL, 5RR), a second clutch 51 for adjusting the torque transmitted between the second motor-generator 12 and the rear wheels 5RL, 5RR is interposed.

[0021] The first motor-generator 11 and the second motor-generator 12 are configured as synchronous motor-generators having both the function of a motor for converting the supplied electric power into mechanical power and the function of a generator for converting the input mechanical power into electric power. That is, each of the first motor-generator 11 and the second motor-generator 12 operates as a motor that generates drive torque during vehicle driving and operates as a generator during regeneration. Note that the first motor-generator 11 mainly operates as a generator, and the second motor-generator 12 mainly operates as a motor.

[0022] The drive reduction gear mechanism 40 is configured to include a motor reduction gear 41 and a drive reduction gear 43. Also, the motor reduction gear 41 is composed of planetary gears, and the reduction gear 43 is composed of, for example, spur gears (or helical gears).

[0023] More specifically, the motor reduction gear 41 has, for example, a planetary gear mechanism (corresponding to the second planetary gear described in the claims) composed of a sun gear 41a, a ring gear 41b, a pinion gear 41c, and a carrier 41d. The sun gear 41a is connected to the rotating shaft of the second motor generator 12 so as to be torque-transmittable. The carrier 41d is connected to the first clutch 42 and the second clutch 51 so as to be torque-transmittable. When the second motor generator 12 functions as a motor, the motor reduction gear 41 reduces the rotation transmitted from the second motor generator 12 (increases the torque) and outputs it from the carrier 41d. On the other hand, the motor reduction gear 41 functions as a generator for the second motor generator 12 by accelerating the rotation (reducing the torque) due to the torque (driving force) input to the carrier 41d and outputting it from the sun gear 41a.

[0024] The front drive shaft 60 transmits torque between the drive reduction gear mechanism 40 and the drive wheels (front wheels 5FL and 5FR in the example of FIG. 1). More specifically, the torque of the engine 10, the second motor generator 12, etc. transmitted to the front drive shaft 60 is transmitted to the front differential (hereinafter also referred to as "front diff") 62. The front diff 62 is, for example, a bevel gear type differential device. The torque from the front diff 62 is transmitted to the left front wheel 5FL via the left front wheel drive shaft and to the right front wheel 5FR via the right front wheel drive shaft.

[0025] On the other hand, the propeller shaft 50 transmits torque between the rear wheels 5RL and 5RR. As described above, the second clutch 51 for adjusting the torque transmitted to the rear wheel 5RL, 5RR side is interposed in the propeller shaft 50. The fastening force (that is, the torque distribution ratio to the rear wheels 5RL, 5RR) of the second clutch 51 is controlled according to the driving state of the four wheels (for example, the slip state). Therefore, the torque of the second motor generator 12 etc. transmitted to the propeller shaft 50 is distributed according to the fastening force of the second clutch 51 and is also transmitted to the rear wheel 5RL, 5RR side.

[0026] More specifically, the torque transmitted to the propeller shaft 50 and adjusted by the second clutch 51 is transmitted to the rear differential (hereinafter also referred to as "rear diff") 52. The left and right rear wheel drive shafts are connected to the rear diff 52. The driving force from the rear diff 52 is transmitted to the left rear wheel 5RL via the left rear wheel drive shaft and to the right rear wheel 5RR via the right rear wheel drive shaft.

[0027] Thus configured, in the vehicle (AWD HEV) according to the present embodiment, the front wheels 5FL, 5FR and the rear wheels 5RL, 5RR (vehicle) can be driven by the two power sources of the engine 10 and the second motor-generator 12. Further, according to the driving conditions, for example, driving by only the second motor-generator 12 (EV driving) and driving by the engine 10 and the second motor-generator 12 (HEV driving) can be switched. Furthermore, regeneration can also be performed by the second motor-generator 12 or the like.

[0028] The engine 10, the second motor-generator 12, and the first motor-generator 11, which are the driving power sources of the vehicle, are comprehensively controlled by the HEV-CU 80. Further, the HEV-CU 80 also controls the engagement forces (engagement, release) of the first clutch 42 and the second clutch 51.

[0029] The HEV-CU 80 includes a microprocessor that performs calculations, an EEPROM that stores programs and the like for causing the microprocessor to execute each process, a RAM that stores various data such as calculation results, a backup RAM that holds the stored content, and an input / output I / F and the like.

[0030] The HEV-CU80 is connected with various sensors, such as an accelerator pedal sensor 91 for detecting the depression amount of the accelerator pedal, a throttle opening sensor 92 for detecting the opening degree of the throttle valve, a G sensor (acceleration sensor) 93 for detecting the longitudinal and lateral accelerations of the vehicle, a vehicle speed sensor 94 for detecting the wheel speed, a rotation speed sensor 95 for detecting the rotation speed of the front drive shaft 60, a resolver 97 for detecting the rotational position (rotation speed) of the first motor-generator 11, a resolver 98 for detecting the rotational position (rotation speed) of the second motor-generator 12, and a rotation speed sensor for detecting the rotation speed of the propeller shaft 50, etc.

[0031] Also, the HEV-CU80 is communicably connected to an ECU81 for controlling the engine 10, a vehicle dynamics control unit (hereinafter referred to as "VDCU") 85 for suppressing vehicle sideslip, etc. and improving driving stability, etc. via a CAN (Controller Area Network) 100. The HEV-CU80 receives various information, such as engine speed, brake operation amount, steering angle of the steering wheel, yaw rate, etc. from the ECU81 and the VDCU85 via the CAN100.

[0032] Based on the various information obtained, HEV-CU80 comprehensively controls the driving of the engine 10, the second motor-generator 12, and the first motor-generator 11, and drives the first clutch 42 and the second clutch 51 to switch the mode among the EV driving (motor driving) mode, the HEV driving (hybrid driving) mode, and the regeneration mode. HEV-CU80, for example, based on the accelerator pedal opening (driver's required driving force), the driving state of the vehicle (such as vehicle speed and steering angle), the state of charge (SOC) of the high-voltage battery 70, and the BSFC of the engine 10, etc., obtains and outputs the required output of the engine 10 and the torque command values of the second motor-generator 12 and the first motor-generator 11, and outputs a control signal (such as a duty signal) for controlling the engagement force (engagement, release) of the first clutch 42 and the second clutch 51. That is, HEV-CU80 functions as the control unit described in the claims.

[0033] Based on the above required output, ECU81 adjusts, for example, the opening of the electronically controlled throttle valve. Also, the power control unit (hereinafter referred to as "PCU") 82 drives the second motor-generator 12 and the first motor-generator 11 via the inverter 82a based on the above torque command values. Here, the inverter 82a converts the DC power of the high-voltage battery 70 into three-phase AC power and supplies it to the second motor-generator 12 and the first motor-generator 11. On the other hand, during regeneration, etc., the inverter 82a converts the AC voltage generated by the second motor-generator 12 and / or the first motor-generator 11 into a DC voltage to charge the high-voltage battery 70.

[0034] In particular, the HEV-CU80 can perform regeneration at the front wheels 5FL and 5FR during deceleration, and can realize an ideal front-rear drive force distribution when restarting the engine 10 from EV driving (motor driving) by the second motor-generator 12 and shifting to HEV driving (hybrid driving) by the engine 10 and the second motor-generator 12. In the HEV-CU80, the above functions are realized by a program stored in an EEPROM or the like being executed by a microprocessor.

[0035] (1) HEV driving (hybrid driving) mode During HEV driving (hybrid driving) mode, the HEV-CU80 operates (drives) the engine 10, the first motor-generator 11, and the second motor-generator 12. At this time, the HEV-CU80 adjusts (controls) the engagement force of the first clutch 42 and the second clutch 51 so as to achieve an ideal front-rear drive force distribution according to the margin of frictional force between the front wheels 5FL, 5FR and the rear wheels 5RL, 5RR and the road surface. The HEV-CU80 obtains the ground loads of the front wheels 5FL, 5FR and the rear wheels 5RL, 5RR from, for example, the longitudinal acceleration and lateral acceleration of the vehicle, and estimates the margin of frictional force with the road surface based on the ground loads.

[0036] Here, the torque transmission path (torque flow) in the HEV driving mode is shown in FIG. 2. Also, a collinear diagram (speed diagram) showing the rotational states (operating states) of the first motor-generator 11, the engine 10, the front wheels 5FL, 5FR, the second motor-generator 12, and the rear wheels 5RL, 5RR in the HEV driving mode is shown in FIG. 3.

[0037] In the HEV driving (hybrid driving) mode, the torques of the engine 10 and the first motor-generator 11 are transmitted to the front wheels 5FL, 5FR via the power split mechanism 30, and are also transmitted to the rear wheels 5RL, 5RR via the first clutch 42 and the second clutch 51. The torque of the second motor-generator 12 is transmitted to the rear wheels 5RL, 5RR via the second clutch 51, and is also transmitted to the front wheels 5FL, 5FR via the first clutch 42.

[0038] (2) EV Driving (Motor Driving) Mode When in the EV driving (motor driving) mode, HEV-CU80 stops (halts) the engine 10 and the first motor / generator 11, and operates (drives) the second motor / generator 12. Also, at this time, HEV-CU80 adjusts (controls) the engagement forces of the first clutch 42 and the second clutch 51 so as to achieve an ideal front-rear drive force distribution according to the margin of frictional force between the front wheels 5FL, 5FR and the rear wheels 5RL, 5RR and the road surface. Note that HEV-CU80 obtains the ground loads of the front wheels 5FL, 5FR and the rear wheels 5RL, 5RR from, for example, the longitudinal and lateral accelerations of the vehicle, and estimates the margin of frictional force with the road surface based on the ground loads.

[0039] Here, the torque transmission path (torque flow) in the EV driving mode is shown in FIG. 4. Also, a collinear diagram (speed diagram) showing the rotational states (operating states) of the first motor / generator 11, the engine 10, the front wheels 5FL, 5FR, the second motor / generator 12, and the rear wheels 5RL, 5RR in the EV driving mode is shown in FIG. 5.

[0040] In the EV driving (motor driving) mode where the engine 10 is stopped and driving is performed by the second motor / generator 12, the torque of the second motor / generator 12 is transmitted to the front wheels 5FL, 5FR via the first clutch 42 and to the rear wheels 5RL, 5RR via the second clutch 51. At this time, when the front-rear drive force distribution ratio is such that the front wheels 5FL, 5FR ≥ the rear wheels 5RL, 5RR, the first clutch 42 is engaged and the second clutch 51 is in a semi-engaged state. On the other hand, when the front-rear drive force distribution ratio is such that the front wheels 5FL, 5FR < the rear wheels 5RL, 5RR, the second clutch 51 is engaged and the first clutch 42 is in a semi-engaged state.

[0041] (3) Regeneration Mode When in the regeneration mode, HEV-CU80 engages the first clutch 42 and releases the second clutch 51.

[0042] Here, the torque transmission path (torque flow) in the regeneration mode is shown in FIG. 6. Also, a collinear diagram (speed diagram) showing the rotational states (operating states) of the first motor-generator 11, engine 10, front wheels 5FL, 5FR, second motor-generator 12, and rear wheels 5RL, 5RR in the regeneration mode is shown in FIG. 7.

[0043] In the regeneration mode (during braking), the second clutch 51 is released (or semi-engaged), and the first clutch 42 is engaged. Therefore, the second motor-generator 12 is directly connected to the front wheels 5FL, 5FR, and regenerative energy is efficiently recovered from the front wheels 5FL, 5FR. Also, at this time, since the second clutch 51 is released, the differential limiting torque becomes zero, preventing the vehicle from having a spinning tendency. Note that if both the first clutch 42 and the second clutch 51 have a transmission capacity during braking and the rotation of the front and rear wheels is differentially limited, cascade lock (all-wheel lock) may occur and the vehicle may spin.

[0044] (4) Switching from EV driving to HEV driving (engine restart) When the HEV-CU80 switches from the EV driving (motor driving) mode by the second motor-generator 12 to the HEV driving (hybrid driving) mode by restarting the engine 10, it operates (drives) the first motor-generator 11 to restart the engine 10. While maintaining the driving torque of the rear wheels 5RL, 5RR, it adjusts (controls) the engagement forces of the first clutch 42 and the second clutch 51 and adjusts the output torque of the second motor-generator 12 so as to compensate for the driving torque of the front wheels 5FL, 5FR with the second motor-generator 12.

[0045] Here, the torque transmission path (torque flow) when switching from the EV driving mode to the HEV driving mode (during engine restart) is shown in FIG. 8. Also, a collinear diagram (speed diagram) showing the rotational states (operating states) of the first motor-generator 11, engine 10, front wheels 5FL, 5FR, second motor-generator 12, and rear wheels 5RL, 5RR when switching from the EV driving mode to the HEV driving mode (during engine restart) is shown in FIG. 9.

[0046] When switching from the EV driving mode to the HEV driving mode (when the engine is restarted), for example, the second clutch 51 is controlled to a semi-clutch state, and appropriate torque is transmitted to the rear wheels 5RL and 5RR, while the first clutch 42 is engaged, so that the output torque of the second motor-generator 12 is also transmitted to the front wheels 5FL and 5FR. Therefore, when the first motor-generator 11 is driven to lift the rotation of the engine 10 and the engine 10 is restarted, the reaction force transmitted to the front wheels 5FL and 5FR is offset, and an ideal front-rear drive force distribution is maintained.

[0047] As described in detail above, according to this embodiment, during regeneration, the first clutch 42 is engaged and the second clutch 51 is released. Therefore, the second motor-generator 12 and the front wheels 5FL and 5FR are directly connected, and regenerative energy can be efficiently recovered from the front wheels 5FL and 5FR. Also, at this time, since the second clutch 51 is released, the differential limiting torque becomes zero, and it is possible to prevent the vehicle from having a spinning tendency.

[0048] Also, when the engine 10 is restarted from motor driving (EV driving) by the second motor-generator 12 and shifts to hybrid driving (HEV driving), while the first motor-generator 11 is operated (driven) to restart the engine 10, the engagement forces of the first clutch 42 and the second clutch 51 are adjusted (controlled) and the output torque of the second motor-generator 12 is adjusted so as to compensate the driving torque of the front wheels 5FL and 5FR by the second motor-generator 12 while maintaining the driving torque of the rear wheels 5RL and 5RR. Therefore, for example, by controlling the second clutch 51 to a semi-clutch state to transmit appropriate torque to the rear wheels 5RL and 5RR and engaging the first clutch 42, the output torque of the second motor-generator 12 can also be transmitted to the front wheels 5FL and 5FR. Thus, when driving the first motor-generator 11 to lift the rotation of the engine 10 and restart the engine 10, it is possible to offset the reaction force acting on the front wheels 5FL and 5FR while maintaining an ideal front-rear drive force distribution.

[0049] As a result, in the two-motor type hybrid all-wheel drive vehicle 1 including the engine 10 and the two motor-generators 11 and 12, it is possible to regenerate at the front wheels 5FL and 5FR during deceleration, and when restarting the engine 10 from the EV running (motor running) by the second motor-generator 12 and shifting to the HEV running (hybrid running) by the engine 10 and the second motor-generator 12, it is possible to realize an ideal front-rear driving force distribution.

[0050] Further, according to the present embodiment, in the HEV running (hybrid running) mode, the engine 10, the first motor-generator 11, and the second motor-generator 12 are operated (driven), and the fastening forces of the first clutch 42 and the second clutch 51 are adjusted (controlled) so as to achieve a front-rear driving force distribution according to the margin of the frictional force between the front wheels 5FL and 5FR and the rear wheels 5RL and 5RR and the road surface. Therefore, in the HEV running in which all wheels are driven, it is possible to realize an ideal front-rear driving force distribution according to the margin of the frictional force between the front wheels 5FL and 5FR, the rear wheels 5RL and 5RR, and the road surface.

[0051] Furthermore, according to the present embodiment, in the EV running (motor running) mode, the engine 10 and the first motor-generator 11 are stopped, the second motor-generator 12 is operated (driven), and the fastening forces of the first clutch 42 and the second clutch 51 are adjusted (controlled) so as to achieve a front-rear driving force distribution according to the margin of the frictional force between the front wheels 5FL and 5FR and the rear wheels 5RL and 5RR and the road surface. Therefore, in the EV running in which all wheels are driven, it is possible to realize an ideal front-rear driving force distribution according to the margin of the frictional force between the front wheels 5FL and 5FR, the rear wheels 5RL and 5RR, and the road surface.

[0052] According to this embodiment, the ground contact loads of the front wheels 5FL and 5FR and the rear wheels 5RL and 5RR are obtained from the longitudinal acceleration and lateral acceleration of the vehicle, and based on the ground contact loads, the margin of frictional force with the road surface is estimated. Therefore, the margin of frictional force between the front wheels 5FL and 5FR and the rear wheels 5RL and 5RR and the road surface can be accurately estimated, and it is also possible to perform control so as to achieve an ideal front-rear drive force distribution according to the margin of frictional force with the road surface.

[0053] As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and various modifications are possible. For example, the configuration of the drive system composed of a plurality of gears and shafts is not limited to the above embodiment. Further, in the above embodiment, hydraulic clutches are used as the first clutch 42 and the second clutch 51, but for example, electric clutches can also be used.

[0054] Also, the system configuration of controllers such as HEV-CU80 and ECU81, and the functional division of each controller are not limited to the above embodiment.

Explanation of Signs

[0055] 1 Hybrid all-wheel drive vehicle 10 Engine 11 First motor-generator 12 Second motor-generator 30 Drive force splitting mechanism 40 Driving reduction gear mechanism 41 Motor reduction gear 42 First clutch 43 Driving reduction gear 50 Propeller shaft 51 Second clutch 52 Rear differential 60 Front drive shaft 62 Front differential 70 High-voltage battery 80 HEV-CU 81 ECU 82 PCU 85 VDCU 91 Accelerator Pedal Sensor 92 Throttle Opening Sensor 93 G-Sensor (Acceleration Sensor) 94 Vehicle Speed Sensor (Wheel Speed Sensor) 95 Rotation Speed Sensor 97,98 Resolver 100 CAN

Claims

1. In a hybrid all-wheel drive vehicle including an engine, a first motor generator, and a second motor generator, a first clutch interposed between the second motor generator and the front wheels; a second clutch interposed between the second motor generator and the rear wheels; a control unit configured to control the engine, the first motor generator, the second motor generator, the first clutch, and the second clutch based on a running state of the vehicle, wherein the first motor generator is connected to be torque-transmittable to the engine and is also connected to be torque-transmittable to the front wheels, and the control unit engages the first clutch and disengages the second clutch during regeneration, when shifting from motor running by the second motor generator to restarting the engine and shifting to hybrid running, while operating the first motor generator to restart the engine, maintains the driving torque of the rear wheels, and compensates for the driving torque of the front wheels with the second motor generator, adjusts the engagement forces of the first clutch and the second clutch, and adjusts the output torque of the second motor generator A hybrid all-wheel drive vehicle characterized by the above.

2. The control unit operates the engine, the first motor generator, and the second motor generator during hybrid running, and adjusts the engagement forces of the first clutch and the second clutch so that the front and rear driving force distribution corresponds to the margin of frictional force between the front and rear wheels and the road surface. The hybrid all-wheel drive vehicle according to claim 1.

3. During motor running, the control unit stops the engine and the first motor generator, operates the second motor generator, and adjusts the engagement forces of the first clutch and the second clutch so that the front and rear driving force distribution corresponds to the margin of frictional force between the front and rear wheels and the road surface. The hybrid all-wheel drive vehicle according to claim 1 or 2.

4. The control unit obtains the ground loads of the front and rear wheels from the longitudinal acceleration and lateral acceleration of the vehicle, and estimates the margin of frictional force with the road surface based on the ground loads. The hybrid all-wheel drive vehicle according to claim 2 or 3.

5. A first planetary gear including a sun gear to which the rotation shaft of the first motor generator is torque-transmissively connected, and a carrier to which the output shaft of the engine is torque-transmissively connected; A second planetary gear including a sun gear to which the rotation shaft of the second motor generator is torque-transmissively connected, and a carrier to which the first clutch and the second clutch are torque-transmissively connected, the hybrid all-wheel drive vehicle according to any one of claims 1 to 4, characterized by comprising the second planetary gear.

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