Four-wheel drive system and vehicle

Abstract

Four-wheel drive system and vehicle of the present invention, a four-wheel drive system, comprising an engine, a starting motor, a first clutch, a gearbox, a drive motor, a power take-off, an intermediate transmission shaft and a power coupler; the gearbox includes a speed-changing assembly and a front differential; the engine is connected to the speed-changing assembly through the first clutch; the input end of the power take-off is connected to the front differential, and a second clutch connected to the input end of the intermediate transmission shaft is provided at the output end of the power take-off; the power coupler includes a rear differential at its power output end; the power input ends of the power coupler are respectively connected to the drive motor and the output end of the intermediate transmission shaft. The engine or the drive motor can perform two-wheel drive, the engine can perform four-wheel drive, the engine and the drive motor can perform four-wheel drive together. When the engine performs four-wheel drive, the drive motor can supplement the driving torque of the rear axle, improve the off-road passability of the vehicle, avoid overheating of the torque manager and too short working time of the drive motor, and effectively improve the economy and NVH performance of the vehicle.

Description

Technical Field

[0001] The present invention belongs to the field of new energy vehicles, and particularly relates to a four-wheel drive system and a vehicle. Background Art

[0002] With the rapid improvement of people's living standards, the leapfrog development of automotive science and technology, and the urgent need for environmental protection of survival, people have put forward higher requirements for automobiles. A high-performance vehicle with rich driving pleasure, adaptable to various road conditions, sufficient power and good economy has become the pursuit of the majority of consumers and an important breakthrough for automobile enterprises to occupy the high-end market.

[0003] For vehicles with rich driving pleasure and adaptable to various road conditions, through long-term exploration, part-time four-wheel drive, full-time four-wheel drive and on-demand four-wheel drive have been proposed; among them,

[0004] For part-time four-wheel drive, generally only the driver needs to stop and manually switch to the four-wheel drive mode, and the vehicle drive type is selected by connecting and disconnecting the transfer case. If the four-wheel drive mode is switched on a paved road surface, there will be a turning braking phenomenon in the vehicle, which is likely to damage the four-wheel drive system;

[0005] For full-time four-wheel drive, by calibrating the output torque distributed to the rear axle, it is possible to better avoid the understeering of front-wheel drive vehicles and the oversteering of rear-wheel drive vehicles, and can well improve the active safety and passability of the vehicle. However, full-time four-wheel drive has higher requirements for the strength of the transmission system, a large failure rate, and relatively high fuel consumption;

[0006] The on-demand four-wheel drive system inherits the advantages of part-time four-wheel drive and full-time four-wheel drive through intelligent control, and at the same time makes up for their deficiencies. On low-adhesion, muddy, sandy and other attached road surfaces, switching to the four-wheel drive mode through four-wheel drive decision-making can greatly improve the power performance and off-road performance of the vehicle, and is full of driving pleasure; on paved road surfaces such as urban roads, switching to the two-wheel drive mode through four-wheel drive decision-making can avoid problems such as turning braking and early tire wear, and can improve the economy of the vehicle. However, due to the layout problem of the power take-off, in order to protect the power take-off, the four-wheel drive torque limit value needs to be set low for on-demand four-wheel drive, resulting in poor vehicle passability caused by the inability to transmit appropriate driving torque to the rear axle, and the torque manager is prone to overheating, and customers are prone to complain, so it is jokingly called the problem of false four-wheel drive.

[0007] In order to save energy, reduce emissions, protect the environment, and at the same time ensure vehicle power, passability and consider technical feasibility, the hybrid four-wheel drive solution of P1 (or P2, or P3) motor + P4 motor is a hybrid power form that is currently in mass production and research and development. "P" refers to the position of the motor. However, practice has shown that due to insufficient battery capacity, the medium-hybrid and weak-hybrid four-wheel drive solutions cannot achieve vehicle energy saving under more severe working conditions, let alone four-wheel drive escape. The additional weight increase of new energy is even more detrimental to the improvement of vehicle energy saving and power; the strong hybrid four-wheel drive solution requires a large-capacity battery, which is not only expensive and significantly increases weight, but also poses a huge test to battery layout and thermal management, which is not conducive to product competition. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a four-wheel drive system and a vehicle in order to solve the problems of insufficient four-wheel drive power and poor economy of the existing solutions.

[0009] To solve the above technical problems, an embodiment of the present invention provides a four-wheel drive system, comprising an engine, a starting motor, a first clutch, a gearbox, and a drive motor, wherein the starting motor is connected to the engine; a power take-off, an intermediate transmission shaft, and a power coupler; the gearbox comprises a transmission assembly and a front differential connected to the transmission assembly;

[0010] The engine is connected to the transmission assembly via the first clutch;

[0011] The input end of the power take-off is connected to the front differential, and the output end of the power take-off is provided with a second clutch;

[0012] The input end of the intermediate transmission shaft is connected to the second clutch;

[0013] The power coupler includes a rear differential located at its power output end; the power input end of the power coupler is connected to the output ends of the drive motor and the intermediate transmission shaft respectively.

[0014] Optionally, the power coupler further comprises a third clutch, a torque manager and a fourth clutch;

[0015] The driving motor is connected to the third clutch;

[0016] The output end of the intermediate transmission shaft is connected to the torque manager;

[0017] The third clutch and the torque manager are both connected to the rear differential via the fourth clutch.

[0018] Optionally, the power coupler further comprises a planetary gear mechanism, a first brake and a second brake; the planetary gear mechanism comprises a sun gear, a planet carrier and a ring gear;

[0019] An output end of the torque manager is connected to the sun gear, and the second brake is used to brake the sun gear;

[0020] The drive motor is connected to the ring gear via the third clutch, and the first brake is used to brake the ring gear;

[0021] The planetary carrier is connected to the rear differential through the fourth clutch.

[0022] Optionally, the speed ratio of the power take-off is i, the gear ratio of the ring gear to the sun gear is k, and i=1+K.

[0023] Optionally, the power coupler further includes an intermediate gear, the diameter of which is smaller than the diameter of the ring gear; the drive motor is located on the front side of the power coupler, the third clutch is connected to the intermediate gear, and the intermediate gear is meshed with the ring gear.

[0024] Optionally, the ring gear is located outside the torque manager, and the intermediate gear is located on a side of the ring gear facing away from the torque manager.

[0025] Optionally, the four-wheel drive system has an engine two-wheel drive mode, a pure electric two-wheel drive mode, an engine four-wheel drive mode, a hybrid four-wheel drive mode and a super four-wheel drive mode;

[0026] Engaging the first clutch, disengaging the second clutch, disengaging the fourth clutch, operating the starting motor, driving the engine, deactivating the torque manager, and deactivating the drive motor, so as to establish the engine two-wheel drive mode;

[0027] The first clutch is disengaged, the second clutch is disengaged, the third clutch is engaged, the fourth clutch is engaged, the first brake is disengaged, the second brake is engaged, the starting motor is deactivated, the engine is deactivated, the torque manager is deactivated, and the drive motor is driven to establish the pure electric two-wheel drive mode;

[0028] Engaging the first clutch, engaging the second clutch, disengaging the third clutch, engaging the fourth clutch, engaging the first brake, disengaging the second brake, operating the starting motor, driving the engine, operating the torque manager, and deactivating the drive motor to establish the engine four-wheel drive mode;

[0029] Engage the first clutch, disengage the second clutch, engage the third clutch, engage the fourth clutch, disengage the first brake, engage the second brake, operate the starting motor, drive the engine, the torque manager does not operate, and the drive motor operates to establish the hybrid four-wheel drive mode;

[0030] Engage the first clutch, engage the second clutch, engage the third clutch, engage the fourth clutch, disengage the first brake, disengage the second brake, operate the starting motor, drive the engine, the torque manager operates, and the drive motor operates to establish the super four-wheel drive mode.

[0031] Optionally, the power take-off is disposed within the transmission.

[0032] Optionally, the driving gear shaft of the power take-off is connected to the housing of the front differential.

[0033] An embodiment of the present invention provides a vehicle, including a controller, a power battery, and a four-wheel drive system, and the four-wheel drive system is connected to the controller and the power battery.

[0034] The four-wheel drive system and the vehicle provided by the embodiment of the present invention can realize the switching of the working state of the engine by controlling the working state of the first clutch. When the first clutch is engaged, the engine can output power to the front differential and drive the front wheels through the front differential. By controlling the working state of the second clutch, the power transmission or interruption between the front differential and the intermediate transmission shaft can be controlled. When the first clutch and the second clutch are engaged simultaneously, the power of the engine can be transmitted to the rear wheels. The power of the drive motor is transmitted to the rear wheels, and even the intermediate transmission shaft, through the power coupler. Therefore, according to the power demand of the vehicle, it is possible to select the engine to drive the front wheels alone or to drive the front wheels and the rear wheels simultaneously, and to select the drive motor to drive the rear wheels alone or to drive the rear wheels together with the engine, combining the advantages of conventional four-wheel drive and hybrid electric vehicles. By supplementing the rear axle driving torque with the drive motor, the problem that the traditional four-wheel drive vehicle cannot transmit an appropriate driving torque to the rear axle due to the strength limitation of the power take-off is avoided, ensuring that the rear axle has sufficient output torque to improve the off-road passability of the vehicle, avoiding damage to the four-wheel drive system caused by overheating of the torque manager, and avoiding the problem that the working time of the drive motor in the hybrid four-wheel drive vehicle is too short due to insufficient battery capacity, effectively improving the vehicle economy and NVH performance. Description of the Drawings

[0035] Figure 1 It is a structural schematic diagram of the four-wheel drive system provided by the embodiment of the present invention;

[0036] Figure 2 is Figure 1 a partial enlarged view of;

[0037] The accompanying drawing reference numerals in the specification are as follows:

[0038] 1. Engine; 2. Starting motor; 3. First clutch;

[0039] 4. Transmission; 41. Transmission component; 42. Front differential;

[0040] 5. Power take-off; 51. Second clutch; 6. Intermediate transmission shaft;

[0041] 7. Power coupler; 71. Third clutch; 72. Torque manager; 73. Fourth clutch;

[0042] 74. Planetary gear mechanism; 741. Sun gear; 742. Planet carrier; 743. Ring gear; [[ID=??]]

[0043] 75. First brake; 76. Second brake; 77. Intermediate gear; 78. Rear differential;

[0044] 8. Drive motor;

[0045] 10. Front wheels; 11. Left front half shaft; 12. Right front half shaft;

[0046] 13. Rear wheels; 14. Left rear half shaft; 15. Right rear half shaft;

[0047] 16. Power battery; 17. Controller. Detailed implementation manners

[0048] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] As Figure 1 shown, the embodiment of the present invention provides a four-wheel drive system, including an engine 1, a starting motor 2, a first clutch 3, a transmission 4, a drive motor 8, a power take-off 5, an intermediate transmission shaft 6 and a power coupler 7; the transmission 4 includes a transmission component 41 and a front differential 42 connected to the transmission component 41;

[0050] The starting motor 2 is connected to the engine 1;

[0051] The engine 1 is connected to the transmission component 41 through the first clutch 3;

[0052] The input end of the power take-off 5 is connected to the front differential 42, and the output end of the power take-off 5 is provided with a second clutch 51;

[0053] The input end of the intermediate transmission shaft 6 is connected to the second clutch 51;

[0054] The power coupler 7 includes a rear differential 78 located at its power output end; the power input ends of the power coupler 7 are respectively connected to the output end of the drive motor 8 and the output end of the intermediate transmission shaft 6.

[0055] In use, the power of the engine 1 is transmitted to the gearbox 4 through the first clutch 3 and drives the front wheels 10 through the front differential 42; the power of the front differential 42 is transmitted to the intermediate transmission shaft 6 through the power take-off 5 and drives the rear wheels 13 through the power coupler 7; therefore, according to the vehicle power demand, by switching the working states of the first clutch 3 and the second clutch 51, the engine 1 can be controlled to drive the front wheels 10 alone, or drive the front wheels 10 and the rear wheels 13 simultaneously; the power of the drive motor 8 is transmitted to the power coupler 7 and drives the rear wheels 13 through the rear differential 78; of course, when the engine 1 is not working and the power battery 16 has sufficient power, the front wheels 10 and the rear wheels 13 can also be driven simultaneously by the drive motor 8; when the engine 1 and the drive motor 8 transmit power to the rear wheels 13 simultaneously, the power coupler 7 outputs the coupled power to the rear wheels 13. Of course, when necessary, the starting motor 2 can also deliver power to the front differential 42.

[0056] Specifically, the front differential 42 distributes power to the left front half shaft 11 and the right front half shaft 12, and drives the left and right front wheels 10 through the left front half shaft 11 and the right front half shaft 12. The rear differential 78 distributes power to the left rear half shaft 14 and the right rear half shaft 15, and drives the left and right rear wheels 13 through the left rear half shaft 14 and the right rear half shaft 15.

[0057] The four-wheel drive system provided by the embodiments of the present invention can achieve the switching of the operating state of the engine 1 by controlling the operating state of the first clutch 3. When the first clutch 3 is engaged, the engine 1 can output power to the front differential 42, and drive the front wheels 10 through the front differential 42; by controlling the operating state of the second clutch 51, the power transmission or interruption between the front differential 42 and the intermediate transmission shaft 6 can be controlled. When the first clutch 3 and the second clutch 51 are engaged simultaneously, the power of the engine 1 can be transmitted to the rear wheels 13; the power of the drive motor 8 is transmitted to the rear wheels 13 through the power coupler 7, and even to the intermediate transmission shaft 6; thus, according to the power demand of the vehicle, it can be selected that the engine 1 drives the front wheels 10 alone or drives the front wheels 10 and the rear wheels 13 simultaneously, and it can be selected that the drive motor 8 drives the rear wheels 13 alone or drives the rear wheels 13 together with the engine 1, combining the advantages of conventional four-wheel drive and hybrid electric vehicles. By supplementing the rear axle driving torque with the drive motor 8, the problem that the traditional four-wheel drive vehicle cannot transmit an appropriate driving torque to the rear axle due to the strength limitation of the power take-off 5 is avoided, ensuring that the rear axle has sufficient output torque to improve the off-road passability of the vehicle, avoiding damage to the four-wheel drive system caused by overheating of the torque manager 72, and avoiding the problem that the working time of the drive motor 8 can be participated in is too short due to insufficient battery capacity of the hybrid four-wheel drive vehicle, effectively improving the vehicle economy and NVH (Noise, Vibration, Harshness) performance, and being applicable to mild hybrid four-wheel drive vehicles.

[0058] Specifically, the engine 1 is coaxially connected to the starting motor 2 through a spline, which can achieve coaxial torque coupling, so that the starting motor 2 can not only start the engine 1, but also participate in driving when necessary.

[0059] Specifically, the transmission assembly 41 can achieve gear shifting and speed reduction and torque increase of the output of the engine 1.

[0060] In one embodiment, as Figure 1 shown, the power coupler 7 further includes a third clutch 71, a torque manager 72, and a fourth clutch 73;

[0061] The drive motor 8 is connected to the third clutch 71;

[0062] The output end of the intermediate transmission shaft 6 is connected to the torque manager 72;

[0063] Both the third clutch 71 and the torque manager 72 are connected to the rear differential 78 through the fourth clutch 73.

[0064] When the driving motor 8 does not need to work, the third clutch 71 is disengaged, which not only reduces the system load but also protects the driving motor 8. When the driving motor 8 needs to participate in driving or power generation, the third clutch 71 can be engaged again. When the front wheels 10 are driving, the second clutch 51 and the fourth clutch 73 are disengaged, which is beneficial to reducing the system load and protecting the torque manager 72. According to the power demand of the vehicle, torque is correspondingly distributed through the torque manager 72. Conventional four-wheel drive can be achieved through the engine 1 and can be used for part-time four-wheel drive. Hybrid four-wheel drive can be achieved by driving the front wheels 10 with the engine 1 and driving the rear wheels 13 with the driving motor 8, which can be used when the power take-off 5 cannot bear the load and the torque manager 72 is temporarily overheated. Super four-wheel drive can be achieved by driving the front wheels 10 and the rear wheels 13 with the engine 1 and driving the rear wheels 13 with the driving motor 8, which is applicable when the vehicle cannot get out of trouble with conventional four-wheel drive and hybrid four-wheel drive. Implementing the above three four-wheel drive modes can not only avoid the power take-off 5 with a small design margin due to the limited layout space of the power take-off 5 being unable to bear a slightly larger load, improve off-road passability, but also avoid the torque manager 72 from overheating due to long-term slipping, and can optimize the vehicle's power performance and passing performance without increasing the torque limit value of the torque manager 72.

[0065] In one embodiment, as Figure 1 and Figure 2 shown, the power coupler 7 further includes a planetary gear mechanism 74, a first brake 75 and a second brake 76; the planetary gear mechanism 74 includes a sun gear 741, a planetary carrier 742 and a ring gear 743;

[0066] The output end of the torque manager 72 is connected to the sun gear 741, and the second brake 76 is used to brake the sun gear 741;

[0067] The driving motor 8 is connected to the ring gear 743 through the third clutch 71, and the first brake 75 is used to brake the ring gear 743;

[0068] The planetary carrier 742 is connected to the rear differential 78 through the fourth clutch 73.

[0069] When only the driving motor 8 outputs power to the rear wheels 13, the second brake 76 brakes the sun gear 741. When only the torque manager 72 outputs power to the rear wheels 13, the first brake 75 brakes the ring gear 743, enabling the planetary gear mechanism 74 to achieve speed change of the power output by the driving motor 8 and the torque manager 72. When the driving motor 8 and the torque manager 72 output power to the rear differential 78 at the same time, the planetary gear mechanism 74 also plays a role in coupling power, which not only simplifies the structure, reduces the system load and improves economy, but also ensures the smoothness of transmission.

[0070] In one embodiment, the speed ratio of the power take-off 5 is i, and the tooth number ratio of the ring gear 743 to the sun gear 741 is k, where i = 1 + K, which can prevent the torque manager 72 from being damaged due to the speed difference and extend the service life of the torque manager 72.

[0071] In one embodiment, as Figure 1 shown, the power coupler 7 further includes an intermediate gear 77. The drive motor 8 is located on the front side of the power coupler 7. The third clutch 71 is connected to the intermediate gear 77, and the intermediate gear 77 meshes with the ring gear 743. The structure is simple and compact, which is beneficial to reducing the lateral dimension of the four-wheel drive system.

[0072] Specifically, the first brake 75 is connected to a clutch portion of the third clutch 71 that is connected to the intermediate gear 77, on the intermediate gear 77, or on the ring gear 743. To simplify the structure of the power coupler 7 and reduce its volume, it is preferably that the first brake 75 is arranged between the third clutch 71 and the intermediate gear 77 and is connected to a clutch portion of the third clutch 71 that is connected to the intermediate gear 77 (as Figure 1 and Figure 2 shown).

[0073] In one embodiment, the diameter of the intermediate gear 77 is smaller than that of the ring gear 743, which can achieve speed reduction and torque increase when power is transmitted from the intermediate gear 77 to the ring gear 743, and better match the power requirements of the vehicle.

[0074] In one embodiment, as Figure 1 and Figure 2 shown, the ring gear 743 is located outside the torque manager 72, and the intermediate gear 77 is located on the side of the ring gear 743 away from the torque manager 72. The structure is more compact, which is beneficial to reducing the volume.

[0075] In one embodiment, as Figure 1 shown, the power take-off 5 is arranged in the transmission 4, and the structure is simpler and more compact, which is beneficial to improving the load-bearing capacity.

[0076] Preferably, the driving gear shaft of the power take-off 5 is connected to the housing of the front differential 42, which is beneficial to increasing the structural stability and the load-bearing capacity.

[0077] More preferably, the power take-off further includes a speed increasing gear set, and the speed increasing gear set is connected to the housing of the front differential and the second clutch in a speed increasing manner. That is, the power take-off not only realizes torque reversal but also realizes speed increase and torque reduction of the power transmission from the housing of the front differential to the second clutch.

[0078] In one embodiment, as Figure 1 shown, the starting motor 2 is located between the engine 1 and the transmission 4, which is beneficial to increasing the structural compactness.

[0079] Specifically, the four-wheel drive system has five working modes, namely the engine two-wheel drive mode, the pure electric two-wheel drive mode, the engine four-wheel drive mode, the hybrid four-wheel drive mode, and the super four-wheel drive mode, which are reflected in Table 1 as follows:

[0080] Table 1

[0081]

[0082] (1) Engine two-wheel drive mode

[0083] Engage the first clutch 3, disengage the second clutch 51, disengage the fourth clutch 73, the starting motor 2 works, the engine 1 drives, the torque manager 72 does not work, and the drive motor 8 does not work to establish the engine two-wheel drive mode;

[0084] In this mode, the starting motor 2 starts the engine 1, and the power of the engine 1 is transmitted to the transmission 4 through the first clutch 3. After being shifted by the transmission 4, the power is delivered to the left front half shaft 11 and the right front half shaft 12 through the front differential 42, driving the left and right front wheels 10, thereby realizing the front-wheel drive of the vehicle. The intermediate drive shaft 6 remains stationary, effectively improving the NVH performance and economy of the vehicle, and is suitable for driving on good roads.

[0085] When the second clutch 51 and the fourth clutch 73 are disengaged, there is no power input to the structure of the power coupler 7 except for the part connected to the rear differential 78 of the fourth clutch 73 and the intermediate drive shaft 10. Whether the third clutch, the first brake, and the second brake are engaged or not will not increase the load of the system. Therefore, the working states of the third clutch, the first brake, and the second brake can be unrestricted.

[0086] (2) Pure electric two-wheel drive mode

[0087] Disengage the first clutch 3, disengage the second clutch 51, engage the third clutch 71, engage the fourth clutch 73, disengage the first brake 75, engage the second brake 76, the starting motor 2 does not work, the engine 1 does not work, the torque manager 72 does not work, and the drive motor 8 drives to establish the pure electric two-wheel drive mode;

[0088] In this mode, the power of the drive motor 8 is transmitted to the planetary gear mechanism 74 through the third clutch 71. After being shifted by the planetary gear mechanism 74, it is transmitted to the rear differential 78 through the fourth clutch 73. The power is delivered to the left rear half shaft 14 and the right rear half shaft 15 through the rear differential 78, driving the left and right rear wheels 13, thereby realizing the rear-wheel drive of the vehicle. It is applicable to low-load conditions such as when the vehicle speed is low, the vehicle starts slowly, and the vehicle cruises at a low speed, avoiding the engine 1 working in the low-efficiency area; through the coordinated control of the controller 17, the frequent start of the engine 1 and the idling of the intermediate drive shaft 6 are avoided, effectively improving the economy of the vehicle and reducing emissions.

[0089] (3) Engine four-wheel drive mode

[0090] Engage the first clutch 3, engage the second clutch 51, disengage the third clutch 71, engage the fourth clutch 73, engage the first brake 75, disengage the second brake 76, start the starting motor 2, drive the engine 1, operate the torque manager 72, and the drive motor 8 does not operate to establish the engine four-wheel drive mode;

[0091] This mode is a conventional four-wheel drive mode. The starting motor 2 starts the engine 1, and the power of the engine 1 is transmitted to the transmission 4 through the first clutch 3. After being shifted by the transmission 4, the front differential 42 delivers a part of the power to the left front half shaft 11 and the right front half shaft 12 to drive the left and right front wheels 10.

[0092] The front differential 42 delivers another part of the power to the intermediate drive shaft 6 through the power take-off 5, and then transmits it to the planetary gear mechanism 74 through the torque manager 72. After being shifted by the planetary gear mechanism 74, it is transmitted to the rear differential 78 through the fourth clutch 73. The rear differential 78 delivers the power to the left rear half shaft 14 and the right rear half shaft 15 to drive the left and right rear wheels 13, thus realizing four-wheel drive. The controller 17 intelligently decides the magnitude of the pressing force of the torque manager 72 according to the vehicle slip ratio, handling and stability characteristics, etc. to optimize the torque input to the sun gear 741.

[0093] To protect the power take-off 5, the torque limit value of the torque manager 72 is relatively small. In addition, the rear axle does not have sufficient power to suppress vehicle skidding and there is a certain axle speed difference between the front and rear axles. The torque manager 72 is prone to overheating during long-term skidding, causing the vehicle to temporarily lose the engine four-wheel drive function. Further overheating will damage the four-wheel drive system. Therefore, to protect the four-wheel drive system, the engine four-wheel drive mode is suitable for on-demand four-wheel drive when the vehicle is driving on harsh roads.

[0094] (4) Hybrid four-wheel drive mode

[0095] Engage the first clutch 3, disengage the second clutch 51, engage the third clutch 71, engage the fourth clutch 73, disengage the first brake 75, engage the second brake 76, start the starting motor 2, drive the engine 1, the torque manager 72 does not operate, and the drive motor 8 operates to establish the hybrid four-wheel drive mode;

[0096] In this mode, the starting motor 2 starts the engine 1, and the power of the engine 1 is transmitted to the transmission 4 through the first clutch 3. After being shifted by the transmission 4, the front differential 42 delivers the power to the left front half shaft 11 and the right front half shaft 12 to drive the left and right front wheels 10.

[0097] The power of the drive motor 8 is transmitted to the planetary gear mechanism 74 through the third clutch 71. After being speed-changed by the planetary gear mechanism 74, it is transmitted to the rear differential 78 through the fourth clutch 73. The power is delivered to the left rear half shaft 14 and the right rear half shaft 15 through the rear differential 78, driving the left and right rear wheels 13, thus achieving four-wheel drive.

[0098] It has both engine four-wheel drive and hybrid four-wheel drive modes, and the four-wheel drive performance of the whole vehicle is better. When the vehicle is driving on harsh roads, in order to improve the off-road passability of the vehicle, the vehicle needs four-wheel drive. However, when the power take-off 5 is not strong enough and the torque manager 72 is temporarily overheated and the engine four-wheel drive mode cannot be adopted, the vehicle can work in the hybrid four-wheel drive mode to avoid temporarily interrupting the four-wheel drive power transmission. By optimizing the drive motor 8 and designing the transmission ratio of the power coupling mechanism, the rear axle power stronger than that of the engine four-wheel drive can be briefly output. The hybrid four-wheel drive mode is a reasonable supplement to the engine four-wheel drive, effectively avoiding the problems of the strength of the power take-off 5 and the failure of the torque manager 72.

[0099] (5) Super four-wheel drive mode

[0100] Engage the first clutch 3, engage the second clutch 51, engage the third clutch 71, engage the fourth clutch 73, disengage the first brake 75, disengage the second brake 76, the starting motor 2 works, the engine 1 drives, the torque manager 72 works, and the drive motor 8 works to establish the super four-wheel drive mode.

[0101] When the vehicle is driving on harsh roads and the above-mentioned engine four-wheel drive or hybrid four-wheel drive cannot get the vehicle out of trouble, at this time, the vehicle needs an instant extremely large driving torque to briefly drive out of the extremely bad road surface, and the vehicle can work in the super four-wheel drive mode.

[0102] In this mode, after the power output by the engine 1 and the power output by the starting motor 2 are coupled, or after the starting motor 2 starts the engine 1 and then stops working and the engine 1 outputs power alone, it is input to the transmission 4 through the third clutch 71. The power is transmitted to the differential housing after being decelerated and torque-increased by the transmission 4. A part of the power of the differential housing is respectively transmitted to the left and right front wheels 10 through the left front half shaft 11 and the right front half shaft 12 to realize the drive of the front wheels 10.

[0103] Another part of the power of the differential housing is input to the second clutch 51 of the power take-off 5 after being speed-increased, torque-reduced and reversed by the power take-off 5, and then the front axle power is transmitted to the power coupler 7 through the intermediate transmission shaft 6. Then, the torque manager 72 in the power coupler 7 intelligently decides the torque input to the sun gear 741, and the power is output from the planet carrier 742 after being decelerated and torque-increased by the planetary gear mechanism 74. At the same time, the drive motor 8 transmits the power to the intermediate gear 77 through the third clutch 71 and is transmitted to the ring gear 743 meshing with it through the intermediate gear 77, and then the power is output from the planet carrier 742.

[0104] The planet carrier 742 converges the power of the engine 1 and the drive motor 8, and finally outputs it to the rear differential 78 through the fourth clutch 73, and then distributes it to the left rear half shaft 14 and the right rear half shaft 15, and finally transmits it to the rear wheels 13 to realize the drive of the rear wheels 13.

[0105] This mode can realize the four-wheel drive power coupling of conventional four-wheel drive and hybrid four-wheel drive. Without increasing the torque limit value of the torque manager 72, the vehicle power performance and passing performance can be maximized.

[0106] Of course, the four-wheel drive system of the present invention can also realize the conventional working modes of models with the engine 1 and the drive motor 8 such as on-board charging and braking energy regeneration. When charging is required, the power transmission routes of the engine 1 and the drive motor 8 are connected while minimizing other loads as much as possible. When braking energy regeneration occurs, the power transmission route between the drive motor 8 and the wheels is connected while minimizing other loads as much as possible. Details are not described here.

[0107] If the planetary gear mechanism 74 is cancelled on the basis of the foregoing solution, for example, the power transmission between the torque manager 72 and the fourth clutch 73 and between the drive motor 8 and the fourth clutch 73 is realized through two sets of parallel gears, then the settings of the first brake 75 and the second brake 76 can be cancelled, and the control of the first brake 75 and the second brake 76 can be cancelled accordingly when switching the working mode; if the third clutch 71 is cancelled on the basis of the foregoing solution, then the control of the third clutch 71 can be cancelled. When the drive motor 8 does not participate in the work, it receives the power from the engine 1, and the rotating shaft of the drive motor 8 can rotate idly; if the fourth clutch 73 is cancelled on the basis of the foregoing solution, then the control of the fourth clutch 73 can be cancelled. When the drive motor 8 does not participate in the work, it receives the power from the engine 1 or the rear wheels 13, and the rotating shaft of the drive motor 8 can rotate idly. The intermediate drive shaft 6 receives the power from the rear wheels 13 and can rotate idly. For the sake of brevity, the power routes of each working mode of this solution are not listed one by one here.

[0108] The embodiment of the present invention also provides a vehicle, including a controller 17, a power battery 16 and the four-wheel drive system described in any of the foregoing embodiments, and the four-wheel drive system is connected to the controller 17 and the power battery 16.

[0109] Through the structural design of the electromechanical coupling four-wheel drive system and the coordinated control with the controller 17, the advantages of traditional four-wheel drive and hybrid four-wheel drive are skillfully combined, and at the same time, the deficiencies of the two types of four-wheel drive are complemented, optimizing the vehicle four-wheel drive performance, making the vehicle full of driving pleasure, adaptable to various road conditions, and having sufficient power, effectively enhancing the competitiveness of the vehicle.

[0110] Specifically, the engine 1, the starting motor 2, the drive motor 8, the torque manager 72, the first clutch 3, the second clutch 51, the third clutch 71, the fourth clutch 73, the first brake 75 and the second brake 76 are connected to the controller 17 and controlled by the controller 17. Both the starting motor 2 and the drive motor 8 are connected to the power battery 16. Figure 1 In the figure, the connection between the controller 17 and the components controlled by it is represented by a dashed line, and the connection between the power battery 16 and the charging / discharging components is represented by a dotted line.

[0111] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A four-wheel drive system, comprising an engine, a starting motor, a first clutch, a gearbox, and a drive motor, wherein the starting motor is connected to the engine; characterized in that, It also includes a power take-off, an intermediate transmission shaft and a power coupler; the gearbox includes a speed change assembly and a front differential connected to the speed change assembly; The engine is connected to the transmission assembly via the first clutch; The input end of the power take-off is connected to the front differential, and the output end of the power take-off is provided with a second clutch; The input end of the intermediate transmission shaft is connected to the second clutch; The power coupler includes a rear differential at its power output end; the power input end of the power coupler is connected to the output end of the drive motor and the output end of the intermediate transmission shaft respectively; The power take-off is arranged in the gearbox; The driving gear shaft of the power take-off is connected to the housing of the front differential; The starting motor is located between the engine and the gearbox.

2. The four-wheel drive system according to claim 1, wherein The power coupler further includes a third clutch, a torque manager, and a fourth clutch; The driving motor is connected to the third clutch; The output end of the intermediate transmission shaft is connected to the torque manager; The third clutch and the torque manager are both connected to the rear differential via the fourth clutch.

3. The four-wheel drive system according to claim 2, wherein The power coupler further comprises a planetary gear mechanism, a first brake and a second brake; the planetary gear mechanism comprises a sun gear, a planet carrier and a ring gear; An output end of the torque manager is connected to the sun gear, and the second brake is used to brake the sun gear; The drive motor is connected to the ring gear via the third clutch, and the first brake is used to brake the ring gear; The planetary carrier is connected to the rear differential through the fourth clutch.

4. The four-wheel drive system according to claim 3, wherein The speed ratio of the power take-off is i, the gear ratio between the ring gear and the sun gear is k, i=1+K.

5. The four-wheel drive system according to claim 4, wherein, The power coupler also includes an intermediate gear, the diameter of which is smaller than the diameter of the ring gear; the drive motor is located at the front side of the power coupler, the third clutch is connected to the intermediate gear, and the intermediate gear is meshed with the ring gear.

6. The four-wheel drive system according to claim 5, characterized in that The ring gear is located on an outer side of the torque manager, and the intermediate gear is located on a side of the ring gear facing away from the torque manager.

7. The four-wheel drive system according to claim 3, wherein The four-wheel drive system has an engine two-wheel drive mode, a pure electric two-wheel drive mode, an engine four-wheel drive mode, a hybrid four-wheel drive mode and a super four-wheel drive mode; Engaging the first clutch, disengaging the second clutch, disengaging the fourth clutch, operating the starting motor, driving the engine, deactivating the torque manager, and deactivating the drive motor, so as to establish the engine two-wheel drive mode; The first clutch is disengaged, the second clutch is disengaged, the third clutch is engaged, the fourth clutch is engaged, the first brake is disengaged, the second brake is engaged, the starting motor is deactivated, the engine is deactivated, the torque manager is deactivated, and the drive motor is driven to establish the pure electric two-wheel drive mode; Engaging the first clutch, engaging the second clutch, disengaging the third clutch, engaging the fourth clutch, engaging the first brake, disengaging the second brake, operating the starting motor, driving the engine, operating the torque manager, and deactivating the drive motor to establish the engine four-wheel drive mode; Engage the first clutch, disengage the second clutch, engage the third clutch, engage the fourth clutch, disengage the first brake, engage the second brake, operate the starting motor, drive the engine, the torque manager does not operate, and operate the drive motor to establish the hybrid four-wheel drive mode; Engage the first clutch, engage the second clutch, engage the third clutch, engage the fourth clutch, disengage the first brake, disengage the second brake, operate the starting motor, drive the engine, the torque manager operates, and operate the drive motor to establish the super four-wheel drive mode.

8. A vehicle, comprising a controller and a power battery, characterized in that, It further includes the four-wheel drive system according to any one of claims 1-7, and the four-wheel drive system is connected to the controller and the power battery.

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