CN110103918B

CN110103918B - Four-wheel centralized drive electric vehicle braking energy recovery system based on stacked one-way valve and one-way valve

Info

Publication number: CN110103918B
Application number: CN201910429070.1A
Authority: CN
Inventors: 杨坤; 王杰; 李敏; 郭栋; 赵淑红; 刘庆新; 籍英华
Original assignee: Shandong University of Technology
Current assignee: Shandong University of Technology
Priority date: 2019-05-22
Filing date: 2019-05-22
Publication date: 2022-02-25
Anticipated expiration: 2039-05-22
Also published as: CN110103918A

Abstract

The invention provides a four-wheel centralized drive electric vehicle braking energy recovery system based on a superposed one-way valve and a one-way valve, belonging to the technical field of electric vehicle braking energy recovery.

Description

Four-wheel centralized drive electric vehicle braking energy recovery system based on stacked one-way valve and one-way valve

Technical Field

The invention belongs to the technical field of electric vehicle braking energy recovery, and particularly relates to a four-wheel centralized driving electric vehicle braking energy recovery system based on a superposition type one-way valve and a one-way valve.

Background

Along with the increasing serious problems of environmental pollution and energy safety, the electric vehicle is more and more emphasized by people, a braking energy recovery system is one of the key means for energy conservation of the electric vehicle, and can recover and utilize energy originally consumed in friction braking through a motor, for example, as described in the research on an EMB-based decoupled braking energy recovery system (Yangkun, Gaussong, Wangjie, and the like), the research on the EMB-based decoupled braking energy recovery system [ J ] in automobile engineering, 2016,38(8):1072 + 1079 ], and the energy of the part can account for about 30% of energy required by driving the whole vehicle.

At present, the braking energy recovery system can be divided into a coupling type and a decoupling type according to the working principle, although the arrangement of the original vehicle braking system is not changed, the coupling type braking energy recovery system has the defects of poor braking feeling and low braking energy recovery rate, and the application is gradually reduced at present.

The decoupling type braking energy recovery system can accurately meet the braking requirement of a driver through the coupling of mechanical braking force and motor braking force, and has the advantages of good braking feeling and high braking energy recovery rate. When the braking force of the motor can completely meet the braking requirement of a driver, the braking force is completely provided by the motor brake, and when the braking force of the motor cannot completely meet the braking requirement of the driver, the braking force of the whole vehicle is provided by the motor brake and the mechanical brake together, so that whether the resultant force of the motor braking force and the mechanical braking force can accurately track the braking force required by the driver becomes the key for influencing the effect of the decoupling type braking energy recovery system.

For an electric commercial vehicle, because the whole vehicle has a heavy weight, the influence of a braking energy recovery effect on the economy of the whole vehicle is very important, and meanwhile, from the perspective of reducing the system cost, the development cost and the system transformation workload, at present, the scheme of a decoupling type braking energy recovery system for the electric commercial vehicle which is researched more is a decoupling type braking energy recovery system based on an air pressure ABS electromagnetic valve, which is mentioned in the document URBS air pressure ABS electromagnetic valve failure analysis and improvement of a new energy passenger vehicle (Yangkun, Ma super, Guo Chi, and the like. the URBS air pressure ABS electromagnetic valve failure analysis and improvement [ J ]. Guangxi university report (natural science version), 2017,42(5): 1647-; this solution has the advantages of low cost and easy implementation, but the following problems are found in the research: the adjusting speed of the pressure of the brake air chamber depends on the difference value of the air pressure of the air storage tank and the air pressure of the brake air chamber, when the continuous braking times are more than two times in the driving process, the pressure in the air storage tank can be obviously reduced, and the more the continuous braking times are, the greater the pressure reduction is, the more the adjusting speed of the pressure of the brake air chamber can be obviously reduced, so that the coupling braking force applied to the whole vehicle by the braking energy recovery system can lag behind the required braking force, thereby bringing the serious problems of different braking feeling from the conventional braking system, possibly causing the lengthening of the braking distance and the like; in addition, for the four-wheel drive electric commercial vehicle, the front wheels and the rear wheels can recover the braking energy, which provides a foundation for further improving the recovery rate of the braking energy, so that the development of the decoupling type braking energy recovery system suitable for the four-wheel drive electric commercial vehicle has important significance.

Disclosure of Invention

Aiming at the problems, the invention provides a braking energy recovery system of a four-wheel centralized driving electric vehicle based on a superposed one-way valve and a one-way valve on the basis of the existing decoupling type braking energy recovery system scheme based on an air pressure ABS electromagnetic valve, in the scheme, an auxiliary air storage tank (3), a rear driving shaft switch electromagnetic valve (5), a first three-way valve (7), a rear driving shaft relay valve (8), a second three-way valve (9), a right rear driving wheel superposed one-way valve (10), a third three-way valve (11), a right rear driving wheel braking pressure sensor (15), a right rear driving wheel one-way valve (19), a fourth three-way valve (20), a left rear driving wheel one-way valve (23), a fifth three-way valve (30), a left rear driving wheel superposed one-way valve (31), a sixth three-way valve (32), a front driving shaft relay valve (36) and the like are additionally arranged in the existing braking energy recovery system, A seventh three-way valve (37), an eighth three-way valve (38), a left front driving wheel superposed one-way valve (39), a ninth three-way valve (40), a left front driving wheel one-way valve (47), a right front driving wheel one-way valve (50), a right front driving wheel brake pressure sensor (54), a thirteenth three-way valve (58), a right front driving wheel superposed one-way valve (59), an eleventh three-way valve (60), a twelfth three-way valve (61), a brake pedal displacement sensor (62), a front driving shaft switch electromagnetic valve (63) and the like, so that each driving wheel brake circuit has two independent high-pressure air sources and a double-circuit structure, when the braking energy recovery is triggered, a gas source with high gas pressure can be selected by the control system to provide high-pressure gas for the braking gas chambers of the driving wheels, therefore, the problem of reduction of the adjusting speed of the air pressure braking force of the wheel caused by low air source pressure during continuous braking is effectively solved.

A four-wheel centralized drive electric vehicle braking energy recovery system based on stacked one-way valves and one-way valves is composed of a brake pedal (1), a brake valve (2), an auxiliary gas storage tank (3), a main gas storage tank (4), a rear drive shaft switch electromagnetic valve (5), an air compressor (6), a first three-way valve (7), a rear drive shaft relay valve (8), a second three-way valve (9), a right rear drive wheel stacked one-way valve (10), a third three-way valve (11), a right rear drive wheel speed sensor (14), a right rear drive wheel braking pressure sensor (15), a right rear drive wheel braking gas chamber (16), a right rear drive wheel ABS electromagnetic valve (17), a right rear drive wheel one-way valve (19), a fourth three-way valve (20), a rear shaft drive motor and transmission device (21), a rear shaft drive motor controller (22), a left rear drive wheel one-way valve (23), The brake system comprises a left rear driving wheel ABS solenoid valve (25), a left rear driving wheel brake air chamber (26), a left rear driving wheel speed sensor (27), a fifth three-way valve (30), a left rear driving wheel superposed type one-way valve (31), a sixth three-way valve (32), a battery management system (33), a vehicle control unit (34), a brake controller (35), a front driving wheel relay valve (36), a seventh three-way valve (37), an eighth three-way valve (38), a left front driving wheel superposed type one-way valve (39), a ninth three-way valve (40), a left front driving wheel speed sensor (43), a left front driving wheel brake air chamber (44), a left front driving wheel ABS solenoid valve (46), a left front driving wheel one-way valve (47), a front shaft driving motor and transmission device (48), a front shaft driving motor controller (49), a right front driving wheel one-way valve (50), a right front driving wheel ABS solenoid valve (51), The brake system comprises a right front driving wheel brake air chamber (53), a right front driving wheel brake pressure sensor (54), a right front driving wheel speed sensor (55), a thirteenth through valve (58), a right front driving wheel superposition type one-way valve (59), an eleventh through valve (60), a twelfth through valve (61), a brake pedal displacement sensor (62) and a front driving shaft switch electromagnetic valve (63).

An air outlet port b of the air compressor (6) is connected with an air inlet port a of the main air storage tank (4) through an air path, and an air outlet port a of the air compressor (6) is connected with an air inlet port a of the auxiliary air storage tank (3) through an air path.

An air inlet port a of the brake valve (2) is connected with an air outlet port d of the main air storage tank (4) through an air path, an air inlet port b of the brake valve (2) is connected with an air outlet port c of the main air storage tank (4) through an air path, an air outlet port c of the brake valve (2) is connected with a control port c of the front drive shaft relay valve (36) through an air path, and an air outlet port d of the brake valve (2) is connected with a control port c of the rear drive shaft relay valve (8) through an air path.

An air outlet port b of the auxiliary air storage tank (3) is connected with an air inlet port a of the rear driving shaft switching electromagnetic valve (5) through an air path, an air outlet port b of the rear driving shaft switching electromagnetic valve (5) is connected with an air inlet port a of the first three-way valve (7) through an air path, an air outlet port b of the first three-way valve (7) is connected with an air inlet port b of the right rear driving wheel superposition type one-way valve (10) through an air path, and an air outlet port c of the first three-way valve (7) is connected with an air inlet port b of the left rear driving wheel superposition type one-way valve (31) through an air path.

And a port a of the rear drive shaft relay valve (8) is connected with an air outlet port e of the main air storage tank (4) through an air passage, and a port b of the rear drive shaft relay valve (8) is connected with a port b of the second three-way valve (9) through an air passage.

The port a of the second three-way valve (9) is connected with the port c of the fourth three-way valve (20) through an air path, the port a of the fourth three-way valve (20) is connected with the air inlet port a of the right rear driving wheel superposition type one-way valve (10) through an air path, the port b of the fourth three-way valve (20) is connected with the air outlet port b of the right rear driving wheel one-way valve (19) through an air path, the air outlet port c of the right rear driving wheel superposition type one-way valve (10) is connected with the port a of the third three-way valve (11) through an air path, the air inlet port a of the right rear driving wheel one-way valve (19) is connected with the port c of the third three-way valve (11) through an air path, the port b of the third three-way valve (11) is connected with the air inlet port a of the right rear driving wheel ABS solenoid valve (17) through an air path, and the air inlet port b of the right rear driving wheel ABS solenoid valve (17) is connected with the right rear driving wheel brake air chamber (16) through an air path.

A right rear driving wheel brake pressure sensor (15) is arranged on the right rear driving wheel brake air chamber (16).

The port c of the second three-way valve (9) is connected with the port c of the sixth three-way valve (32) through an air path, the port a of the sixth three-way valve (32) is connected with the air inlet port a of the left rear driving wheel superposed type one-way valve (31) through an air path, the port b of the sixth three-way valve (32) is connected with the air outlet port b of the left rear driving wheel one-way valve (23) through an air path, the air outlet port c of the left rear driving wheel superposed type one-way valve (31) is connected with the port a of the fifth three-way valve (30) through an air path, the air inlet port a of the left rear driving wheel one-way valve (23) is connected with the port c of the fifth three-way valve (30) through an air path, the port b of the fifth three-way valve (30) is connected with the air inlet port a of the left rear driving wheel ABS solenoid valve (25) through an air path, and the air inlet port b of the left rear driving wheel ABS solenoid valve (25) is connected with the left rear driving wheel brake air chamber (26) through an air path.

An air outlet port c of the auxiliary air storage tank (3) is connected with an air inlet port a of the front driving shaft switch electromagnetic valve (63) through an air passage, an air outlet port b of the front driving shaft switch electromagnetic valve (63) is connected with an air inlet port a of the twelfth three-way valve (61) through an air passage, an air outlet port b of the twelfth three-way valve (61) is connected with an air inlet port b of the right front driving wheel superposition type one-way valve (59) through an air passage, and an air outlet port c of the twelfth three-way valve (61) is connected with an air inlet port b of the left front driving wheel superposition type one-way valve (39) through an air passage.

And a port a of the front drive shaft relay valve (36) is connected with an air outlet port b of the main air storage tank (4) through an air passage, and a port b of the front drive shaft relay valve (36) is connected with a port b of a seventh three-way valve (37) through an air passage.

The port a of the seventh three-way valve (37) is connected with the port c of the eleventh three-way valve (60) through an air passage, the port a of the eleventh three-way valve (60) is connected with the air inlet port a of the right front driving wheel superposition type one-way valve (59) through an air passage, the port b of the eleventh three-way valve (60) is connected with the air outlet port b of the right front driving wheel one-way valve (50) through an air passage, the air outlet port c of the right front driving wheel superposition type one-way valve (59) is connected with the port a of the thirteenth one-way valve (58) through an air passage, the air inlet port a of the right front driving wheel one-way valve (50) is connected with the port c of the thirteenth one-way valve (58) through an air passage, the port b of the thirteenth one-way valve (58) is connected with the air inlet port a of the right front driving wheel ABS solenoid valve (51) through an air passage, and the air inlet port b of the right front driving wheel ABS solenoid valve (51) is connected with the right front driving wheel brake air chamber (53) through an air passage.

A right front driving wheel brake pressure sensor (54) is arranged on the right front driving wheel brake air chamber (53).

The port c of the seventh three-way valve (37) is connected with the port c of the eighth three-way valve (38) through an air passage, the port a of the eighth three-way valve (38) is connected with the air inlet port a of the left front driving wheel superposition type one-way valve (39) through an air passage, the port b of the eighth three-way valve (38) is connected with the air outlet port b of the left front driving wheel one-way valve (47) through an air passage, the air outlet port c of the left front driving wheel superposition type one-way valve (39) is connected with the port a of the ninth three-way valve (40) through an air passage, the air inlet port a of the left front driving wheel one-way valve (47) is connected with the port c of the ninth three-way valve (40) through an air passage, the port b of the ninth three-way valve (40) is connected with the air inlet port a of the left front driving wheel ABS solenoid valve (46) through an air passage, and the air inlet port b of the left front driving wheel ABS solenoid valve (46) is connected with the left front driving wheel brake air chamber (44) through an air passage.

The right rear driving wheel speed sensor (14), the left rear driving wheel speed sensor (27), the left front driving wheel speed sensor (43) and the right front driving wheel speed sensor (55) are connected with the brake controller (35) through signal lines.

The right rear driving wheel ABS electromagnetic valve (17), the left rear driving wheel ABS electromagnetic valve (25), the left front driving wheel ABS electromagnetic valve (46) and the right front driving wheel ABS electromagnetic valve (51) are connected with the brake controller (35) through signal lines.

The rear driving shaft switch electromagnetic valve (5), the right rear driving wheel brake pressure sensor (15), the right front driving wheel brake pressure sensor (54), the brake pedal displacement sensor (62) and the front driving shaft switch electromagnetic valve (63) are connected with the whole vehicle controller (34) through signal lines.

The rear axle driving motor controller (22), the battery management system (33), the whole vehicle controller (34), the brake controller (35) and the front axle driving motor controller (49) are connected through a CAN bus.

Based on the four-wheel centralized drive electric vehicle braking energy recovery system based on the superposition type one-way valve and the one-way valve, a vehicle control unit (34) judges whether to trigger a braking energy recovery function or not based on the vehicle speed output by a braking controller (35) through a CAN bus, a pedal displacement signal output by a braking pedal displacement sensor (62), the maximum allowable charging current of a battery output by a battery management system (33) through the CAN bus, the maximum motor braking force provided by a rear shaft drive motor and a transmission device (21) output by a rear shaft drive motor controller (22) through the CAN bus, and the maximum motor braking force provided by a front shaft drive motor and a transmission device (48) output by a front shaft drive motor controller (49) through the CAN bus, and controls the rear drive shaft on-off solenoid valve (5) and the front drive shaft on-off solenoid valve (63) in accordance therewith.

When a brake pedal is stepped on and a braking energy recovery function is triggered, the whole vehicle controller (34) controls the conduction of the rear driving shaft switch electromagnetic valve (5), and the gas path between the port b of the auxiliary gas storage tank (3) and the port a of the first three-way valve (7) is conducted; the whole vehicle controller (34) controls the conduction of the front drive shaft switch electromagnetic valve (63), and the gas path between the port c of the auxiliary gas storage tank (3) and the port a of the twelfth three-way valve (61) is conducted.

When a brake pedal is stepped on but the braking energy recovery function is not triggered, the whole vehicle controller (34) controls the rear driving shaft switch electromagnetic valve (5) to be switched off, and an air path between the port b of the auxiliary air storage tank (3) and the port a of the first three-way valve (7) is not communicated; the vehicle control unit (34) controls the front drive shaft switch electromagnetic valve (63) to be turned off, and the air path between the port c of the auxiliary air storage tank (3) and the port a of the twelfth three-way valve (61) is not communicated.

When a driver looses the brake pedal (1), the vehicle control unit (34) controls the rear drive shaft switch electromagnetic valve (5) to disconnect the air path connection between the port b of the auxiliary air storage tank (3) and the port a of the first three-way valve (7); the vehicle control unit (34) controls the front drive shaft switch electromagnetic valve (63) to disconnect the air path connection between the port c of the auxiliary air storage tank (3) and the port a of the twelfth three-way valve (61).

Compared with the prior art, the invention adds an auxiliary gas storage tank (3), a rear driving shaft switch electromagnetic valve (5), a first three-way valve (7), a rear driving shaft relay valve (8), a second three-way valve (9), a right rear driving wheel superposed type one-way valve (10), a third three-way valve (11), a right rear driving wheel brake pressure sensor (15), a right rear driving wheel one-way valve (19), a fourth three-way valve (20), a left rear driving wheel one-way valve (23), a fifth three-way valve (30), a left rear driving wheel superposed type one-way valve (31), a sixth three-way valve (32), a front driving shaft relay valve (36), a seventh three-way valve (37), an eighth three-way valve (38), a left front driving wheel superposed type one-way valve (39), a ninth three-way valve (40), a left front driving wheel one-way valve (47), a right front driving wheel one-way valve (50) and a brake pressure sensor (15), a right rear driving wheel brake pressure sensor, The brake system comprises a right front driving wheel brake pressure sensor (54), a thirteenth through valve (58), a right front driving wheel stacked one-way valve (59), an eleventh through valve (60), a twelfth through valve (61), a brake pedal displacement sensor (62), a front driving shaft switch electromagnetic valve (63) and the like, so that each driving wheel brake circuit has two independent high-pressure air sources and a double-circuit structure, and when braking energy recovery is triggered, the air sources with higher air pressure can provide high-pressure air for a driving wheel brake air chamber, thereby effectively solving the key problems that the coupling brake force response speed of the driving wheels is slow and the coupling brake force lags behind the required brake force caused by low air source pressure in the continuous braking in the existing scheme.

FIG. 1 is a schematic structural diagram of a braking energy recovery system of a four-wheel centralized drive electric vehicle based on a stacked one-way valve and a one-way valve. Wherein: 1. a brake pedal; 2. a brake valve; 3. a secondary gas storage tank; 4. a primary gas storage tank; 5. the rear driving shaft switches the electromagnetic valve; 6. an air compressor; 7. a first three-way valve; 8. a rear drive shaft relay valve; 9. a second three-way valve; 10. a right rear driving wheel superposition type one-way valve; 11. a third three-way valve; 12. a right rear drive wheel brake; 13. a right rear drive wheel; 14. a right rear driving wheel speed sensor; 15. a right rear drive wheel brake pressure sensor; 16. a brake chamber of a right rear driving wheel; 17. ABS electromagnetic valve of the right rear driving wheel; 18. a right rear drive half shaft; 19. a right rear drive wheel check valve; 20. a fourth three-way valve; 21. A rear shaft driving motor and a transmission device; 22. a rear axle drive motor controller; 23. a left rear drive wheel check valve; 24. a left rear drive half shaft; 25. ABS electromagnetic valve of the left rear driving wheel; 26. a left rear drive wheel brake chamber; 27. a left rear drive wheel speed sensor; 28. a left rear drive wheel; 29. a left rear drive wheel brake; 30. a fifth three-way valve; 31. a left rear driving wheel superposed one-way valve; 32. a sixth three-way valve; 33. a battery management system; 34. a vehicle control unit; 35. a brake controller; 36. a front drive shaft relay valve; 37. a seventh three-way valve; 38. an eighth three-way valve; 39. a left front driving wheel superposed one-way valve; 40. a ninth three-way valve; 41. a left front drive wheel; 42. a left front drive wheel brake; 43. a left front drive wheel speed sensor; 44. a left front drive wheel brake chamber; 45. a left front drive half shaft; 46. a left front drive wheel ABS solenoid valve; 47. a left front drive wheel check valve; 48. a front shaft driving motor and a transmission device; 49. a front axle drive motor controller; 50. a right front drive wheel check valve; 51. An ABS electromagnetic valve of a right front driving wheel; 52. a right front drive half shaft; 53. a right front drive wheel brake chamber; 54. a right front drive wheel brake pressure sensor; 55. a right front drive wheel speed sensor; 56. a right front drive wheel brake; 57. a right front drive wheel; 58. a thirteenth way valve; 59. a right front driving wheel superposition type one-way valve; 60. an eleventh three-way valve; 61. a twelfth three-way valve; 62. a brake pedal displacement sensor; 63. the front drive shaft switches the electromagnetic valve.

The following describes in detail embodiments of the present invention.

The invention provides a braking energy recovery system of a four-wheel centralized drive electric vehicle based on a superposition type one-way valve and a one-way valve, which is further described in detail by referring to the attached drawings and taking examples in order to make the technical scheme and the effect of the invention clearer and clearer; it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in figure 1, the four-wheel centralized drive electric vehicle braking energy recovery system based on the superposition type one-way valve and the one-way valve comprises a brake pedal (1), a brake valve (2), an auxiliary air storage tank (3), a main air storage tank (4), a rear drive shaft switch electromagnetic valve (5), an air compressor (6), a first three-way valve (7), a rear drive shaft relay valve (8), a second three-way valve (9), a right rear drive wheel superposition type one-way valve (10), a third three-way valve (11), a right rear drive wheel speed sensor (14), a right rear drive wheel braking pressure sensor (15), a right rear drive wheel braking air chamber (16), a right rear drive wheel ABS electromagnetic valve (17), a right rear drive wheel one-way valve (19), a fourth three-way valve (20), a rear shaft drive motor and transmission device (21), a rear shaft drive motor controller (22), a left rear drive wheel one-way valve (23), The brake system comprises a left rear driving wheel ABS solenoid valve (25), a left rear driving wheel brake air chamber (26), a left rear driving wheel speed sensor (27), a fifth three-way valve (30), a left rear driving wheel superposed type one-way valve (31), a sixth three-way valve (32), a battery management system (33), a vehicle control unit (34), a brake controller (35), a front driving wheel relay valve (36), a seventh three-way valve (37), an eighth three-way valve (38), a left front driving wheel superposed type one-way valve (39), a ninth three-way valve (40), a left front driving wheel speed sensor (43), a left front driving wheel brake air chamber (44), a left front driving wheel ABS solenoid valve (46), a left front driving wheel one-way valve (47), a front shaft driving motor and transmission device (48), a front shaft driving motor controller (49), a right front driving wheel one-way valve (50), a right front driving wheel ABS solenoid valve (51), The brake system comprises a right front driving wheel brake air chamber (53), a right front driving wheel brake pressure sensor (54), a right front driving wheel speed sensor (55), a thirteenth through valve (58), a right front driving wheel superposition type one-way valve (59), an eleventh through valve (60), a twelfth through valve (61), a brake pedal displacement sensor (62) and a front driving shaft switch electromagnetic valve (63).

When braking, the working principle of the braking system is as follows.

In the running process of the automobile, the brake controller (35) receives wheel speed signals output by a right rear driving wheel speed sensor (14), a left rear driving wheel speed sensor (27), a left front driving wheel speed sensor (43) and a right front driving wheel speed sensor (55).

The vehicle control unit (34) receives a vehicle speed signal and a vehicle acceleration signal output by the brake controller (35), a pedal displacement signal output by the brake pedal displacement sensor (62), a front drive shaft brake air pressure value output by the right front drive wheel brake pressure sensor (54), a rear drive shaft brake air pressure value output by the right rear drive wheel brake pressure sensor (15), a battery allowed maximum charging current output by the battery management system (33) through a CAN bus, a maximum motor braking force which CAN be provided by the rear drive motor controller (22) through the CAN bus and a rear drive motor and transmission device (21), and a maximum motor braking force which CAN be provided by the front drive motor controller (49) through the CAN bus and the front drive motor and transmission device (48).

The maximum motor braking force which CAN be applied to the right rear driving wheel (13) and the left rear driving wheel (28) by the rear shaft driving motor and transmission device (21), the maximum motor braking force which CAN be applied to the right front driving wheel (57) and the left front driving wheel (41) by the front shaft driving motor and transmission device (48) are determined by the vehicle control unit (34) according to the vehicle speed of the whole vehicle, the acceleration of the whole vehicle, the maximum allowable charging current of a battery output by the battery management system (33) through a CAN bus, the maximum motor braking force which CAN be provided by the rear shaft driving motor and transmission device (21) and output by the rear shaft driving motor controller (22) through the CAN bus, and the maximum motor braking force which CAN be provided by the front shaft driving motor and transmission device (48) and output by the front shaft driving motor controller (49) through the CAN bus.

The vehicle control unit (34) judges whether to trigger a braking energy recovery function according to the following four conditions based on the vehicle speed output by the braking controller (35) through the CAN bus, the pedal displacement signal output by the braking pedal displacement sensor (62), the maximum charging current allowed by the battery output by the battery management system (33) through the CAN bus, the maximum motor braking force provided by the rear axle driving motor and transmission device (21) output by the rear axle driving motor controller (22) through the CAN bus and the maximum motor braking force provided by the front axle driving motor and transmission device (48) output by the front axle driving motor controller (49) through the CAN bus: the first condition is as follows: the vehicle speed value output by the brake controller (35) is greater than the minimum vehicle speed threshold value allowing the recovery of the brake energy; and a second condition: a pedal displacement signal output by a brake pedal displacement sensor (62) is greater than a pedal displacement threshold value for triggering braking energy recovery; and (3) carrying out a third condition: the battery management system (33) outputs a battery allowable maximum charging current larger than 0; and a fourth condition: the front axle required motor braking force or the rear axle required motor braking force determined by the vehicle control unit (34) is greater than a minimum motor braking force threshold that allows for recovery of braking energy.

When the four conditions are met simultaneously, the braking energy recovery function is triggered; when any one of the brake energy recovery functions cannot be met, the brake energy recovery function cannot be triggered.

When the brake pedal (1) is stepped on and the braking energy recovery function is triggered.

The vehicle control unit (34) determines a total braking force target value required by the left front driving wheel (41), the right front driving wheel (57), the left rear driving wheel (28) and the right rear driving wheel (13) according to the vehicle speed, the vehicle acceleration and the brake pedal displacement.

The vehicle control unit (34) determines motor braking force target values required by the left front driving wheel (41), the right front driving wheel (57), the left rear driving wheel (28) and the right rear driving wheel (13) according to a total braking force target value required by the left front driving wheel (41), the right front driving wheel (57), the left rear driving wheel (28) and the right rear driving wheel (13), a maximum allowable battery charging current output by the battery management system (33) through a CAN bus, a maximum motor braking force which CAN be provided by a rear shaft driving motor and transmission device (21) and output by a rear shaft driving motor controller (22) through the CAN bus, and a maximum motor braking force which CAN be provided by a front shaft driving motor and transmission device (48) and output by a front shaft driving motor controller (49) through the CAN bus.

The vehicle control unit (34) determines a target air pressure braking force value of the left rear driving wheel (28) according to the target total braking force value of the left rear driving wheel (28) and a target motor braking force value required by the left rear driving wheel (28); the vehicle control unit (34) determines a target air pressure braking force value of the right rear driving wheel (13) according to the target total braking force value of the right rear driving wheel (13) and a target motor braking force value required by the right rear driving wheel (13); the vehicle control unit (34) determines an air pressure braking force target value of the left front driving wheel (41) according to the total braking force target value of the left front driving wheel (41) and a motor braking force target value required by the left front driving wheel (41); the vehicle control unit (34) determines a target air pressure braking force value of the right front driving wheel (57) on the basis of the target total braking force value of the right front driving wheel (57) and a target motor braking force value required by the right front driving wheel (57).

The vehicle control unit (34) outputs a required motor braking force target value of the left rear driving wheel (28) and a required motor braking force target value of the right rear driving wheel (13) to the rear axle driving motor controller (22) through the CAN bus, outputs a required motor braking force target value of the left front driving wheel (41) and a required motor braking force target value of the right front driving wheel (57) to the front axle driving motor controller (49), and outputs the vehicle control unit (34) to the brake controller (35) through the CAN bus, wherein the vehicle control unit outputs air pressure braking force target values of the left front driving wheel (41), the right front driving wheel (57), the left rear driving wheel (28) and the right rear driving wheel (13), a rear driving axle air pressure braking force actual value output by the right rear driving wheel braking pressure sensor (15), and a front driving axle air pressure braking force actual value output by the right front driving wheel braking pressure sensor (53).

The principle of applying braking to the left rear drive wheel (28) when the braking energy recovery function is triggered is as follows.

The whole vehicle controller (34) controls the conduction of the rear drive shaft switching electromagnetic valve (5), and high-pressure gas in the auxiliary gas storage tank (3) sequentially passes through the port b of the auxiliary gas storage tank (3), the port a and the port b of the rear drive shaft switching electromagnetic valve (5), and the port a and the port c of the first three-way valve (7) to reach the port b of the left rear drive wheel superposition type one-way valve (31).

High-pressure gas in the main gas storage tank (4) enters a control port c of the rear drive shaft relay valve (8) through a port d of the main gas storage tank (4) and ports a and d of the brake valve (2) to enable the port a and the port b of the rear drive shaft relay valve (8) to be communicated, and the high-pressure gas in the main gas storage tank (4) sequentially reaches the port a of the left rear drive wheel superposition type check valve (31) through a port e of the main gas storage tank (4), the ports a and b of the rear drive shaft relay valve (8), the ports b and c of the second three-way valve (9), and the ports c and a of the sixth three-way valve (32).

At this time, the conditions of supplying the brake pressure to the brake air chamber (26) of the left rear driving wheel are divided into the following two types according to the air pressure of the port a of the left rear driving wheel superposition type check valve (31) and the air pressure of the port b of the left rear driving wheel superposition type check valve (31).

When the air pressure at the port a of the left rear driving wheel superposition type check valve (31) is larger than the air pressure at the port b, the main air storage tank (4) provides high-pressure air for the brake chamber (26) of the left rear driving wheel; at this time, the high-pressure gas in the main gas tank (4) sequentially passes through a port e of the main gas tank (4), a port a and a port b of the rear drive shaft relay valve (8), a port b and a port c of the second three-way valve (9), a port c and a port a of the sixth three-way valve (32), a port a and a port c of the left rear drive wheel superposition type check valve (31), a port a and a port b of the fifth three-way valve (30), and a port a and a port b of the left rear drive wheel ABS solenoid valve (25) to enter the left rear drive wheel brake chamber (26), so that air pressure braking force can be applied to the left rear drive wheel (28) through the left rear drive wheel brake (29).

When the air pressure at the port a of the left rear driving wheel superposition type one-way valve (31) is smaller than the air pressure at the port b, the auxiliary air storage tank (3) provides high-pressure air for the brake chamber (26) of the left rear driving wheel; at this time, high-pressure gas in the auxiliary gas storage tank (3) sequentially passes through a port b of the auxiliary gas storage tank (3), a port a and a port b of the rear drive shaft switching solenoid valve (5), a port a and a port c of the first three-way valve (7), a port b and a port c of the left rear drive wheel superposition type check valve (31), a port a and a port b of the fifth three-way valve (30) and a port a and a port b of the left rear drive wheel ABS solenoid valve (25) and enters the left rear drive wheel brake chamber (26), so that air pressure braking force can be applied to the left rear drive wheel (28) through the left rear drive wheel brake (29).

In order to realize the decoupling control of the motor braking force and the air pressure braking force of the left rear driving wheel (28), the air pressure braking force of the left rear driving wheel (28) can be adjusted through the ABS electromagnetic valve (25) of the left rear driving wheel, and the modes of applying the braking force to the left rear driving wheel (28) are divided into the following two modes according to the relationship between the maximum motor braking force which can be applied to the left rear driving wheel (28) by the rear shaft driving motor and the transmission device (21) and the total braking force target value of the left rear driving wheel (28).

The first mode is as follows: when the maximum motor braking force applied to the left rear driving wheel (28) by the rear axle driving motor and transmission device (21) through the left rear driving half axle (24) is larger than or equal to the total braking force target value of the left rear driving wheel (28), the air pressure braking force target value of the left rear driving wheel (28) is 0, at the moment, the brake controller (35) controls the port a of the left rear driving wheel ABS electromagnetic valve (25) to be closed through a signal line, the port b and the port c are opened, the air path connection between the left rear driving wheel brake air chamber (26) and the port b of the fifth three-way valve (30) is disconnected, the left rear driving wheel brake air chamber (26) is communicated with the atmosphere through the port b and the port c of the left rear driving wheel ABS electromagnetic valve (25), and at the moment, the rear axle driving motor and transmission device (21) applies the required braking force to the left rear driving wheel (28) through the left rear driving half axle (24).

And a second mode: when the maximum motor braking force which can be applied to the left rear driving wheel (28) by the rear axle driving motor and transmission device (21) through the left rear driving half axle (24) is smaller than the target value of the total braking force of the left rear driving wheel (28), the rear axle driving motor and transmission device (21) applies the maximum motor braking force to the left rear driving wheel (28) through the left rear driving half axle (24).

The target value of the air pressure braking force of the left rear driving wheel (28) is determined by the difference between the target value of the total braking force of the left rear driving wheel (28) and the maximum motor braking force applied to the left rear driving wheel (28) by the rear axle driving motor and transmission (21) through the left rear driving half axle (24), and the cases of applying the air pressure braking force to the left rear driving wheel (28) are divided into the following three cases according to the relationship between the target value of the air pressure braking force of the left rear driving wheel (28) and the actual value of the air pressure braking force.

When the target value of the air pressure braking force of the left rear driving wheel (28) is larger than the actual value of the air pressure braking force, the brake controller (35) controls the opening of the port a and the port b of the ABS electromagnetic valve (25) of the left rear driving wheel to be conducted through a signal line, the port c is closed, and high-pressure air at the port b of the fifth three-way valve (30) enters the brake air chamber (26) of the left rear driving wheel through the port a and the port b of the ABS electromagnetic valve (25) of the left rear driving wheel so as to increase the actual air pressure braking force of the left rear driving wheel (28).

When the target value of the air pressure braking force of the left rear driving wheel (28) is smaller than the actual value of the air pressure braking force, the brake controller (35) controls the port a of the ABS electromagnetic valve (25) of the left rear driving wheel to be closed through a signal line, the port b is communicated with the port c, and high-pressure air at the brake air chamber (26) of the left rear driving wheel is exhausted into the atmosphere through the port b and the port c of the ABS electromagnetic valve (25) of the left rear driving wheel so as to reduce the actual air pressure braking force of the left rear driving wheel (28).

When the target value of the air pressure braking force of the left rear driving wheel (28) is equal to the actual value of the air pressure braking force, the brake controller (35) controls the port b and the port c of the ABS electromagnetic valve (25) of the left rear driving wheel to be closed through a signal line, and the air pressure in the brake air chamber (26) of the left rear driving wheel is kept unchanged so as to realize the maintenance of the actual air pressure braking force of the left rear driving wheel (28).

When the brake pedal (1) is depressed, but the braking energy recovery function is not triggered.

And the rear driving shaft switch electromagnetic valve (5) is closed, the air path between the port b of the auxiliary air storage tank (3) and the port a of the first three-way valve (7) is disconnected, and the port b of the left rear driving wheel superposition type one-way valve (31) has no high-pressure air.

The port b of the left rear driving wheel superposition type check valve (31) is closed, the port a and the port c are communicated, high-pressure gas in the main gas storage tank (4) sequentially passes through the port e of the main gas storage tank (4), the port a and the port b of the rear driving wheel relay valve (8), the port b and the port c of the second three-way valve (9), the port c and the port a of the sixth three-way valve (32), the port a and the port c of the left rear driving wheel superposition type check valve (31), the port a and the port b of the fifth three-way valve (30) and the port a and the port b of the left rear driving wheel ABS solenoid valve (25) to enter the left rear driving wheel brake air chamber (26), and therefore air pressure braking force is applied to the left rear driving wheel (28) through the left rear driving wheel brake (29).

The brake release of the left rear driving wheel (28) is divided into the release of the motor braking force and the release of the air pressure power, and the working principle is as follows.

When the driver releases the brake pedal (1), the vehicle control unit (34) controls the motor braking force applied to the left rear driving wheel (28) by the rear axle driving motor and transmission device (21) through the left rear driving half axle (24) to be reduced through the rear axle driving motor controller (22) so as to release the motor braking force of the left rear driving wheel.

When a driver releases a brake pedal (1), a brake valve (2) is closed, a rear drive shaft relay valve (8) breaks the air path connection between a port e of a main air storage tank (4) and a port b of a second three-way valve (9), a rear drive shaft switch electromagnetic valve (5) breaks the air path connection between a port b of an auxiliary air storage tank (3) and a port a of a first three-way valve (7), high-pressure air in a brake air chamber (26) of a left rear drive wheel sequentially passes through the port b and the port a of a left rear drive wheel ABS electromagnetic valve (25), the port b and the port c of a fifth three-way valve (30), the port a and the port b of a left rear drive wheel one-way valve (23), the port b and the port c of a sixth three-way valve (32), and the port c and the port b of a second three-way valve (9) to enter the rear drive shaft relay valve (8), and is discharged into the atmosphere through the rear drive shaft relay valve (8), so that the air pressure of the left rear drive wheel (28) is released, in this process, no control is applied to the left rear drive wheel ABS solenoid valve (25).

The principle of applying braking to the right rear drive wheel (13) when the braking energy recovery function is triggered is as follows.

The whole vehicle controller (34) controls the conduction of the rear drive shaft switching electromagnetic valve (5), and high-pressure gas in the auxiliary gas storage tank (3) sequentially passes through the port b of the auxiliary gas storage tank (3), the port a and the port b of the rear drive shaft switching electromagnetic valve (5), and the port a and the port b of the first three-way valve (7) to reach the port b of the right rear drive wheel superposition type one-way valve (10).

High-pressure gas in the main gas storage tank (4) enters a control port c of the rear drive shaft relay valve (8) through a port d of the main gas storage tank (4) and ports a and d of the brake valve (2) to enable the port a and the port b of the rear drive shaft relay valve (8) to be communicated, and the high-pressure gas in the main gas storage tank (4) sequentially passes through a port e of the main gas storage tank (4), the ports a and b of the rear drive shaft relay valve (8), the ports b and a of the second three-way valve (9), and the port c and the port a of the fourth three-way valve (20) to reach a port a of the right rear drive wheel superposition type one-way valve (10).

At this time, the conditions of supplying the braking pressure to the brake chamber (16) of the right rear driving wheel are divided into the following two conditions according to the air pressure of the port a of the right rear driving wheel superposition type check valve (10) and the air pressure of the port b of the right rear driving wheel superposition type check valve (10).

When the air pressure at the port a of the right rear driving wheel superposition type one-way valve (10) is larger than the air pressure at the port b, the main air storage tank (4) provides high-pressure air for the brake chamber (16) of the right rear driving wheel; at this time, high-pressure gas in the main gas storage tank (4) sequentially passes through a port e of the main gas storage tank (4), a port a and a port b of a rear drive shaft relay valve (8), a port b and a port a of a second three-way valve (9), a port c and a port a of a fourth three-way valve (20), a port a and a port c of a right rear drive wheel superposition type one-way valve (10), a port a and a port b of a third three-way valve (11) and a port a and a port b of a right rear drive wheel ABS solenoid valve (17) to enter a right rear drive wheel brake chamber (16), so that air pressure braking force can be applied to a right rear drive wheel (13) through a right rear drive wheel brake (12).

When the air pressure at the port a of the right rear driving wheel superposition type one-way valve (10) is smaller than the air pressure at the port b, the auxiliary air storage tank (3) provides high-pressure air for a brake chamber (16) of the right rear driving wheel; at the moment, high-pressure gas in the auxiliary gas storage tank (3) sequentially passes through a port b of the auxiliary gas storage tank (3), a port a and a port b of a rear drive shaft switching solenoid valve (5), a port a and a port b of a first three-way valve (7), a port b and a port c of a right rear drive wheel superposition type one-way valve (10), a port a and a port b of a third three-way valve (11) and a port a and a port b of a right rear drive wheel ABS solenoid valve (17) and enters a right rear drive wheel brake chamber (16), so that air pressure braking force can be applied to a right rear drive wheel (13) through a right rear drive wheel brake (12).

In order to realize the decoupling control of the motor braking force and the air pressure braking force of the right rear driving wheel (13), the air pressure braking force of the right rear driving wheel (13) can be adjusted through an ABS electromagnetic valve (17) of the right rear driving wheel, and the modes of applying the braking force to the right rear driving wheel (13) are divided into the following two modes according to the relationship between the maximum motor braking force which can be applied to the right rear driving wheel (13) by a rear shaft driving motor and a transmission device (21) and the target value of the total braking force of the right rear driving wheel (13).

The first mode is as follows: when the maximum motor braking force applied to the right rear driving wheel (13) by the rear axle driving motor and transmission device (21) through the right rear driving half axle (18) is larger than the total braking force target value of the right rear driving wheel (13), the air pressure braking force target value of the right rear driving wheel (13) is 0, at the moment, the brake controller (35) controls the port a of the right rear driving wheel ABS electromagnetic valve (17) to be closed through a signal line, the port b and the port c are opened, the air path connection between the right rear driving wheel brake air chamber (16) and the third three-way valve (11) is disconnected, the right rear driving wheel brake air chamber (16) is communicated with the atmosphere through the port b and the port c of the right rear driving wheel ABS electromagnetic valve (17), and at the moment, the rear axle driving motor and transmission device (21) applies the required braking force to the right rear driving wheel (13) through the right rear driving half axle (18).

And a second mode: when the maximum motor braking force which can be applied to the right rear driving wheel (13) by the rear axle driving motor and transmission device (21) through the right rear driving half shaft (18) is smaller than the target value of the total braking force of the right rear driving wheel (13), the rear axle driving motor and transmission device (21) applies the maximum motor braking force to the right rear driving wheel (13) through the right rear driving half shaft (18).

The target value of the air pressure braking force of the right rear driving wheel (13) is determined by the difference between the target value of the total braking force of the right rear driving wheel (13) and the maximum motor braking force applied to the right rear driving wheel (13) by the rear axle driving motor and transmission device (21) through the right rear driving half axle (18), and the conditions of applying the air pressure braking force to the right rear driving wheel (13) are divided into the following three according to the relationship between the target value of the air pressure braking force of the right rear driving wheel (13) and the actual value of the air pressure braking force.

When the target value of the air pressure braking force of the right rear driving wheel (13) is larger than the actual value of the air pressure braking force, the brake controller (35) controls the opening of the port a and the port b of the ABS electromagnetic valve (17) of the right rear driving wheel to be conducted through a signal line, the port c is closed, and high-pressure air at the port b of the third three-way valve (11) enters the brake air chamber (16) of the right rear driving wheel through the port a and the port b of the ABS electromagnetic valve (17) of the right rear driving wheel so as to increase the actual air pressure braking force of the right rear driving wheel (13).

When the target value of the air pressure braking force of the right rear driving wheel (13) is smaller than the actual value of the air pressure braking force, the brake controller (35) controls the port a of the ABS electromagnetic valve (17) of the right rear driving wheel to be closed through a signal line, the port b is communicated with the port c, and high-pressure air at the brake air chamber (16) of the right rear driving wheel is exhausted into the atmosphere through the port b and the port c of the ABS electromagnetic valve (17) of the right rear driving wheel so as to reduce the actual air pressure braking force of the right rear driving wheel (13).

When the target value of the air pressure braking force of the right rear driving wheel (13) is equal to the actual value of the air pressure braking force, the brake controller (35) controls the port b and the port c of the ABS electromagnetic valve (17) of the right rear driving wheel to be closed through a signal line, and the air pressure in the brake air chamber (16) of the right rear driving wheel is kept unchanged so as to realize the maintenance of the actual air pressure braking force of the right rear driving wheel (13).

And the rear driving shaft switch electromagnetic valve (5) is closed, the air path between the port b of the auxiliary air storage tank (3) and the port a of the first three-way valve (7) is disconnected, and the port b of the right rear driving wheel superposition type one-way valve (10) does not contain high-pressure air.

The port b of the right rear driving wheel superposition type one-way valve (10) is closed, the port a and the port c are communicated, high-pressure gas in the main gas storage tank (4) sequentially passes through the port e of the main gas storage tank (4), the port a and the port b of the rear driving shaft relay valve (8), the port b and the port a of the second three-way valve (9), the port c and the port a of the fourth three-way valve (20), the port a and the port c of the right rear driving wheel superposition type one-way valve (10), the port a and the port b of the third three-way valve (11) and the port a and the port b of the right rear driving wheel ABS solenoid valve (17) to enter the right rear driving wheel brake chamber (16), and accordingly air pressure braking force is applied to the right rear driving wheel (13) through the right rear driving wheel brake (12).

The brake release of the right rear driving wheel (13) is divided into the release of the motor braking force and the release of the air compression power, and the working principle is as follows.

When a driver releases the brake pedal (1), the vehicle control unit (34) controls the motor braking force applied to the right rear driving wheel (13) by the rear axle driving motor and transmission device (21) through the right rear driving half axle (18) to be reduced through the rear axle driving motor controller (22) so as to release the motor braking force of the right rear driving wheel.

When a driver releases a brake pedal (1), a brake valve (2) is closed, a rear drive shaft relay valve (8) breaks the air path connection between a port e of a main air storage tank (4) and a port b of a second three-way valve (9), a rear drive shaft switch electromagnetic valve (5) breaks the air path connection between a port b of an auxiliary air storage tank (3) and a port a of a first three-way valve (7), high-pressure air in a brake air chamber (16) of a right rear drive wheel sequentially passes through a port b and a port a of a right rear drive wheel ABS electromagnetic valve (17), a port b and a port c of a third three-way valve (11), a port a and a port b of a right rear drive wheel one-way valve (19), a port b and a port c of a fourth three-way valve (20), a port a and a port b of a second three-way valve (9) to enter the rear drive shaft relay valve (8), and is discharged into the atmosphere through the rear drive shaft relay valve (8), so that the air pressure of a right rear drive wheel (13) is released, in the process, the control is not exerted on the ABS electromagnetic valve (17) of the right rear driving wheel.

The principle of applying braking to the left front drive wheel (41) when the braking energy recovery function is triggered is as follows.

The whole vehicle controller (34) controls the conduction of the front drive shaft switch electromagnetic valve (63), and high-pressure gas in the auxiliary gas storage tank (3) sequentially passes through a port c of the auxiliary gas storage tank (3), a port a and a port b of the front drive shaft switch electromagnetic valve (63), and a port a and a port c of the twelfth three-way valve (61) to reach a port b of the left front drive wheel superposition type one-way valve (39).

High-pressure gas in the main gas storage tank (4) enters a control port c of the front drive shaft relay valve (36) through a port c of the main gas storage tank (4) and a port b and a port c of the brake valve (2) to enable the port a and the port b of the front drive shaft relay valve (36) to be communicated, and the high-pressure gas in the main gas storage tank (4) sequentially passes through the port b of the main gas storage tank (4), the port a and the port b of the front drive shaft relay valve (36), the port b and the port c of the seventh three-way valve (37), and the port c and the port a of the eighth three-way valve (38) to reach the port a of the front drive wheel superposition type one-way valve (39).

At this time, the conditions of supplying the braking pressure to the left front driving wheel brake air chamber (44) are divided into the following two types according to the air pressure of the port a of the left front driving wheel superposition type check valve (39) and the air pressure of the port b of the left front driving wheel superposition type check valve (39).

When the air pressure at the port a of the left front driving wheel superposition type one-way valve (39) is larger than the air pressure at the port b, high-pressure air is provided for a braking air chamber (44) of the left front driving wheel by a main air storage tank (4); at this time, the high-pressure gas in the main gas tank (4) sequentially passes through a port b of the main gas tank (4), a port a and a port b of the front drive shaft relay valve (36), a port b and a port c of the seventh three-way valve (37), a port c and a port a of the eighth three-way valve (38), a port a and a port c of the left front drive wheel superposition type one-way valve (39), a port a and a port b of the ninth three-way valve (40), and a port a and a port b of the left front drive wheel ABS solenoid valve (46) to enter the left front drive wheel brake chamber (44), so that air pressure braking force can be applied to the left front drive wheel (41) through the left front drive wheel brake (42).

When the air pressure at the port a of the left front driving wheel superposition type one-way valve (39) is smaller than the air pressure at the port b, the auxiliary air storage tank (3) provides high-pressure air for the braking air chamber (44) of the left front driving wheel; at this time, the high-pressure gas in the auxiliary gas tank (3) sequentially passes through a port c of the auxiliary gas tank (3), a port a and a port b of a front drive shaft switching solenoid valve (63), a port a and a port c of a twelfth three-way valve (61), a port b and a port c of a left front drive wheel superposition type one-way valve (39), a port a and a port b of a ninth three-way valve (40), and a port a and a port b of a left front drive wheel ABS solenoid valve (46) and enters a left front drive wheel brake chamber (44), so that air pressure braking force can be applied to the left front drive wheel (41) through the left front drive wheel brake (42).

In order to realize the decoupling control of the motor braking force and the air pressure braking force of the left front driving wheel (41), the air pressure braking force of the left front driving wheel (41) can be adjusted through the ABS electromagnetic valve (46) of the left front driving wheel, and modes of applying the braking force to the left front driving wheel (41) are divided into the following two modes according to the relation between the maximum motor braking force which can be applied to the left front driving wheel (41) by the front shaft driving motor and the transmission device (48) and the total braking force target value of the left front driving wheel (41).

The first mode is as follows: when the maximum motor braking force applied to the left front driving wheel (41) by the front axle driving motor and transmission device (48) through the left front driving half axle (45) is larger than or equal to the total braking force target value of the left front driving wheel (41), the air pressure braking force target value of the left front driving wheel (41) is 0, at the moment, the braking controller (35) controls the port a of the left front driving wheel ABS electromagnetic valve (46) to be closed through a signal line, the port b and the port c are opened, the air circuit connection between the left front driving wheel braking air chamber (44) and the port b of the ninth three-way valve (40) is disconnected, the left front driving wheel braking air chamber (44) is communicated with the atmosphere through the port b and the port c of the left front driving wheel ABS electromagnetic valve (46), and at the moment, the front axle driving motor and transmission device (48) applies the required braking force to the left front driving wheel (41) through the left front driving half axle (45).

And a second mode: when the maximum motor braking force which can be applied to the left front driving wheel (41) by the front axle driving motor and transmission device (48) through the left front driving half axle (45) is smaller than the target value of the total braking force of the left front driving wheel (41), the front axle driving motor and transmission device (48) applies the maximum motor braking force to the left front driving wheel (41) through the left front driving half axle (45).

The target value of the air pressure braking force of the left front driving wheel (41) is determined by the difference between the target value of the total braking force of the left front driving wheel (41) and the maximum motor braking force applied to the left front driving wheel (41) by a front shaft driving motor and a transmission device (48) through a left front driving half shaft (45), and the conditions of applying the air pressure braking force to the left front driving wheel (41) are divided into the following three according to the relationship between the target value of the air pressure braking force of the left front driving wheel (41) and the actual value of the air pressure braking force.

When the target value of the air pressure braking force of the left front driving wheel (41) is larger than the actual value of the air pressure braking force, the brake controller (35) controls the opening of a port a and a port b of an ABS electromagnetic valve (46) of the left front driving wheel to be conducted through a signal line, a port c is closed, and high-pressure air at the port b of the ninth three-way valve (40) enters a brake air chamber (44) of the left front driving wheel through the port a and the port b of the ABS electromagnetic valve (46) of the left front driving wheel so as to increase the actual air pressure braking force of the left front driving wheel (41).

When the target value of the air pressure braking force of the left front driving wheel (41) is smaller than the actual value of the air pressure braking force, the brake controller (35) controls the port a of the ABS electromagnetic valve (46) of the left front driving wheel to be closed through a signal line, the port b is communicated with the port c, and high-pressure air at the brake air chamber (44) of the left front driving wheel is exhausted into the atmosphere through the port b and the port c of the ABS electromagnetic valve (46) of the left front driving wheel so as to reduce the actual air pressure braking force of the left front driving wheel (41).

When the target value of the air pressure braking force of the left front driving wheel (41) is equal to the actual value of the air pressure braking force, the brake controller (35) controls the port b and the port c of the ABS electromagnetic valve (46) of the left front driving wheel to be closed through signal lines, and the air pressure in the brake air chamber (44) of the left front driving wheel is kept unchanged so as to keep the actual air pressure braking force of the left front driving wheel (41).

The front drive shaft switch electromagnetic valve (63) is closed, the air path between the port c of the auxiliary air storage tank (3) and the port a of the twelfth three-way valve (61) is disconnected, and the port b of the left front drive wheel superposition type one-way valve (39) does not contain high-pressure air.

The port b of the left front driving wheel superposition type one-way valve (39) is closed, the port a is communicated with the port c, high-pressure gas in the main gas storage tank (4) sequentially passes through the port b of the main gas storage tank (4), the port a and the port b of the front driving shaft relay valve (36), the port b and the port c of the seventh three-way valve (37), the port c and the port a of the eighth three-way valve (38), the port a and the port c of the left front driving wheel superposition type one-way valve (39), the port a and the port b of the ninth three-way valve (40), and the port a and the port b of the left front driving wheel ABS solenoid valve (46) to enter the left front driving wheel brake chamber (44), so that air pressure braking force is applied to the left front driving wheel (41) through the left front driving wheel brake (42).

The release of the brake of the left front drive wheel (41) is divided into the release of the motor brake force and the release of the pneumatic brake force, and the working principle is as follows.

When a driver releases the brake pedal (1), the vehicle control unit (34) controls the front axle driving motor and the transmission device (48) to reduce the motor braking force applied to the left front driving wheel (41) through the left front driving half axle (45) through the front axle driving motor controller (49) so as to release the motor braking force of the left front driving wheel.

When a driver releases a brake pedal (1), a brake valve (2) is closed, a front drive shaft relay valve (36) breaks the air path connection between a port b of a main air storage tank (4) and a port b of a seventh three-way valve (37), a front drive shaft switch electromagnetic valve (63) breaks the air path connection between a port c of an auxiliary air storage tank (3) and a port a of a twelfth three-way valve (61), high-pressure air in a brake air chamber (44) of a left front drive wheel sequentially passes through the port b and the port a of a ABS electromagnetic valve (46) of the left front drive wheel, the port b and the port c of a ninth three-way valve (40), the port a and the port b of a one-way valve (47) of the left front drive wheel, the port b and the port c of an eighth three-way valve (38), and the port c and the port b of the seventh three-way valve (37) to enter the front drive shaft relay valve (36), and is exhausted to the atmosphere through the front drive shaft relay valve (36), so that the air pressure of the left front drive wheel (41) is released, during the process, the control is not exerted on the ABS solenoid valve (46) of the left front driving wheel.

The principle of applying braking to the right front drive wheel (57) when the braking energy recovery function is triggered is as follows.

The whole vehicle controller (34) controls the conduction of the front drive shaft switch electromagnetic valve (63), and high-pressure gas in the auxiliary gas storage tank (3) sequentially passes through a port c of the auxiliary gas storage tank (3), a port a and a port b of the front drive shaft switch electromagnetic valve (63), and a port a and a port b of the twelfth three-way valve (61) to reach a port b of the right front drive wheel superposition type one-way valve (59).

High-pressure gas in the main gas storage tank (4) enters a control port c of the front drive shaft relay valve (36) through a port c of the main gas storage tank (4) and a port b and a port c of the brake valve (2) to enable the port a and the port b of the front drive shaft relay valve (36) to be communicated, and the high-pressure gas in the main gas storage tank (4) sequentially passes through the port b of the main gas storage tank (4), the port a and the port b of the front drive shaft relay valve (36), the port b and the port a of the seventh three-way valve (37), the port c and the port a of the eleventh three-way valve (60) to reach the port a of the right front drive wheel superposition type one-way valve (59).

At this time, the case of supplying the brake pressure to the right front driving wheel brake chamber (53) is divided into the following two cases according to the magnitude of the air pressure at the port a of the right front driving wheel superposition type check valve (59) and the air pressure at the port b of the right front driving wheel superposition type check valve (59).

When the air pressure at the port a of the right front driving wheel superposition type check valve (59) is larger than the air pressure at the port b, the main air storage tank (4) provides high-pressure air for the brake air chamber (53) of the right front driving wheel; at this time, the high-pressure gas in the main gas tank (4) passes through the port b of the main gas tank (4), the port a and the port b of the front drive shaft relay valve (36), the port b and the port a of the seventh three-way valve (37), the port c and the port a of the eleventh three-way valve (60), the port a and the port c of the right front drive wheel superposition type check valve (59), the port a and the port b of the thirteenth three-way valve (58), and the port a and the port b of the right front drive wheel ABS solenoid valve (51) in sequence to enter the right front drive wheel brake chamber (53), so that the right front drive wheel brake (57) can be applied with pneumatic brake force by the right front drive wheel brake (56).

When the air pressure at the port a of the right front driving wheel superposition type check valve (59) is smaller than the air pressure at the port b, the auxiliary air storage tank (3) provides high-pressure air for the brake air chamber (53) of the right front driving wheel; at this time, the high-pressure gas in the sub gas tank (3) passes through a port c of the sub gas tank (3), a port a and a port b of the front drive shaft switching solenoid valve (63), a port a and a port b of the twelfth three-way valve (61), a port b and a port c of the right front drive wheel superposition type check valve (59), a port a and a port b of the thirteenth three-way valve (58), and a port a and a port b of the right front drive wheel ABS solenoid valve (51) in sequence, enters the right front drive wheel brake chamber (53), and thus, the right front drive wheel brake (57) can be applied with pneumatic brake force by the right front drive wheel brake (56).

In order to realize the decoupling control of the motor braking force and the air pressure braking force of the right front driving wheel (57), the air pressure braking force in the right front driving wheel (57) can be adjusted through the ABS electromagnetic valve (51) of the right front driving wheel, and the modes of applying the braking force to the right front driving wheel (57) are divided into the following two modes according to the relationship between the maximum motor braking force which can be applied to the right front driving wheel (57) by the front shaft driving motor and the transmission device (48) and the total braking force target value of the right front driving wheel (57).

The first mode is as follows: when the maximum motor braking force applied to the right front driving wheel (57) by the front axle driving motor and transmission device (48) through the right front driving half axle (52) is larger than the total braking force target value of the right front driving wheel (57), the air pressure braking force target value of the right front driving wheel (57) is 0, at the moment, the braking controller (35) controls the port a of the ABS electromagnetic valve (51) of the right front driving wheel to be closed through a signal line, the port b and the port c are opened, the air path connection between the braking air chamber (53) of the right front driving wheel and the thirteenth through valve (58) is disconnected, the braking air chamber (53) of the right front driving wheel is communicated with the atmosphere through the port b and the port c of the ABS electromagnetic valve (51), and at the moment, the front axle driving motor and transmission device (48) applies the required braking force to the right front driving wheel (57) through the right front driving half axle (52).

And a second mode: when the maximum motor braking force that the front axle drive motor and transmission (48) can apply to the front right drive wheel (57) through the front right drive axle (52) is less than the target value of the total braking force of the front right drive wheel (57), the front axle drive motor and transmission (48) applies the maximum motor braking force to the front right drive wheel (57) through the front right drive axle (52).

The target value of the pneumatic braking force of the front right driving wheel (57) is determined by the difference between the target value of the total braking force of the front right driving wheel (57) and the maximum motor braking force applied to the front right driving wheel (57) by the front axle drive motor and transmission (48) through the front right driving half axle (52), and the cases of applying the pneumatic braking force to the front right driving wheel (57) are divided into the following three cases according to the relationship between the target value of the pneumatic braking force of the front right driving wheel (57) and the actual value of the pneumatic braking force.

When the target value of the air pressure braking force of the right front driving wheel (57) is larger than the actual value of the air pressure braking force, the brake controller (35) controls the opening of the port a and the port b of the ABS electromagnetic valve (51) of the right front driving wheel through a signal line, the port c is closed, and high-pressure air at the port b of the thirteenth communication valve (58) enters the brake air chamber (53) of the right front driving wheel through the port a and the port b of the ABS electromagnetic valve (51) of the right front driving wheel so as to realize the increase of the actual air pressure braking force of the right front driving wheel (57).

When the target value of the air pressure braking force of the front right driving wheel (57) is smaller than the actual value of the air pressure braking force, the brake controller (35) controls the port a of the ABS electromagnetic valve (51) of the front right driving wheel to be closed through a signal line, the port b and the port c are conducted, and high-pressure air at the brake air chamber (53) of the front right driving wheel is exhausted into the atmosphere through the port b and the port c of the ABS electromagnetic valve (51) of the front right driving wheel so as to achieve reduction of the actual air pressure braking force of the front right driving wheel (57).

When the target value of the air pressure braking force of the right front driving wheel (57) is equal to the actual value of the air pressure braking force, the brake controller (35) controls the port b and the port c of the ABS electromagnetic valve (51) of the right front driving wheel to be closed through a signal line, and the air pressure in the brake air chamber (53) of the right front driving wheel is kept unchanged so as to realize the maintenance of the actual air pressure braking force of the right front driving wheel (57).

The front drive shaft switch electromagnetic valve (63) is closed, the air passage between the port c of the auxiliary air storage tank (3) and the port a of the twelfth three-way valve (61) is disconnected, and the port b of the right front drive wheel superposition type one-way valve (59) does not contain high-pressure air.

The port b of the right front driving wheel superposition type check valve (59) is closed, the port a and the port c are communicated, high-pressure gas in the main gas storage tank (4) sequentially passes through the port b of the main gas storage tank (4), the port a and the port b of the front driving shaft relay valve (36), the port b and the port a of the seventh three-way valve (37), the port c and the port a of the eleventh three-way valve (60), the port a and the port c of the right front driving wheel superposition type check valve (59), the port a and the port b of the thirteenth three-way valve (58) and the port a and the port b of the right front driving wheel ABS solenoid valve (51) to enter the right front driving wheel brake air chamber (53), and therefore pneumatic braking force is applied to the right front driving wheel (57) through the right front driving wheel brake (56).

The release of the braking of the right front driving wheel (57) is divided into the release of the motor braking force and the release of the air pressure power, and the operation principle is as follows.

When the driver releases the brake pedal (1), the vehicle control unit (34) controls the motor braking force applied to the right front driving wheel (57) by the front axle driving motor and transmission device (48) through the right front driving half axle (52) to be reduced through the front axle driving motor controller (49) so as to release the motor braking force of the right front driving wheel.

When a driver releases a brake pedal (1), a brake valve (2) is closed, a front drive shaft relay valve (36) breaks an air path connection between a port b of a main air storage tank (4) and a port b of a seventh three-way valve (37), a front drive shaft switch electromagnetic valve (63) breaks an air path connection between a port c of an auxiliary air storage tank (3) and a port a of a twelfth three-way valve (61), high-pressure air in a brake air chamber (53) of a right front drive wheel sequentially enters the front drive shaft relay valve (36) through the port b and the port a of a right front drive wheel ABS electromagnetic valve (51), the port b and the port c of a thirteenth three-way valve (58), the port a and the port b of a one-way valve (50) of the right front drive wheel, the port b and the port c of an eleventh three-way valve (60) and the port a and the port b of a seventh three-way valve (37) and is exhausted to the atmosphere through the front drive shaft relay valve (36), so that the air pressure of a right front drive wheel (57) is released, during this process, the ABS solenoid valve (51) of the right front driving wheel is not controlled.

The working characteristics of a rear driving shaft switch electromagnetic valve (5), a front driving shaft switch electromagnetic valve (63), a right rear driving wheel superposed type one-way valve (10), a left rear driving wheel superposed type one-way valve (31), a right front driving wheel superposed type one-way valve (59), a left front driving wheel superposed type one-way valve (39), a right rear driving wheel one-way valve (19), a left rear driving wheel one-way valve (23), a right front driving wheel one-way valve (50) and a left front driving wheel one-way valve (47) in the four-wheel centralized driving electric vehicle braking energy recovery system based on the superposed type one-way valve and the one-way valve are introduced as follows.

When a driver does not step on the brake pedal (1), the rear driving shaft switch electromagnetic valve (5) is in a turn-off state, and high-pressure gas does not exist at the port a of the first three-way valve (7); when a driver steps on the brake pedal (1) but does not trigger the braking energy recovery function, the rear driving shaft switch electromagnetic valve (5) is in a turn-off state, and no high-pressure gas exists at the port a of the first three-way valve (7); when a driver steps on the brake pedal (1) and triggers the braking energy recovery function, the rear driving shaft switch electromagnetic valve (5) is in a conduction state, and high-pressure gas is arranged at the port a of the first three-way valve (7).

When a driver does not step on the brake pedal (1), the front drive shaft switch electromagnetic valve (63) is in an off state, and high-pressure gas does not exist at the port a of the twelfth three-way valve (61); when a driver steps on the brake pedal (1) but does not trigger the braking energy recovery function, the front drive shaft switch electromagnetic valve (63) is in a turn-off state, and no high-pressure gas exists at the port a of the twelfth three-way valve (61); when a driver steps on the brake pedal (1) and triggers the braking energy recovery function, the front drive shaft switch electromagnetic valve (63) is in a conducting state, and high-pressure gas is arranged at the port a of the twelfth three-way valve (61).

The right rear driving wheel superposition type check valve (10) is provided with three ports: the gas can only flow into the gas inlet port a and the gas inlet port b of the right rear driving wheel superposition type one-way valve (10) and flow out of the gas outlet port c of the right rear driving wheel superposition type one-way valve (10), so that the gas can be controlled to flow to the right rear driving wheel brake gas chamber (16) only from the first three-way valve (7) or the rear driving shaft relay valve (8) and cannot be conducted in the reverse direction; when the air pressure of the air inlet port a is larger than that of the air inlet port b, the port a is communicated with the port c, and the port b is closed; when the air pressure of the air inlet port a is smaller than that of the air inlet port b, the port b and the port c are conducted, and the port a is closed.

The left rear drive wheel superposition type check valve (31) has three ports: the gas can only flow into the left rear driving wheel superposition type one-way valve (31) from the gas inlet port a and the gas inlet port b and flow out of the left rear driving wheel superposition type one-way valve (31) from the gas outlet port c, so that the gas can only be controlled to flow into the left rear driving wheel brake air chamber (26) from the first three-way valve (7) and the rear driving shaft relay valve (8), and the gas cannot be conducted in the reverse direction; when the air pressure of the air inlet port a is larger than that of the air inlet port b, the port a is communicated with the port c, and the port b is closed; when the air pressure of the air inlet port a is smaller than that of the air inlet port b, the port b and the port c are conducted, and the port a is closed.

The right front drive wheel superposition type check valve (59) has three ports: the gas can only flow into the air inlet port a and the air inlet port b of the right front driving wheel superposition type one-way valve (59) and flow out of the air outlet port c of the right front driving wheel superposition type one-way valve (59), so that the gas can only flow to the right front driving wheel brake air chamber (53) from the twelfth three-way valve (61) or the front driving shaft relay valve (36) and can not be conducted in the reverse direction; when the air pressure of the air inlet port a is larger than that of the air inlet port b, the port a is communicated with the port c, and the port b is closed; when the air pressure of the air inlet port a is smaller than that of the air inlet port b, the port b and the port c are conducted, and the port a is closed.

The left front drive wheel superposition type check valve (39) has three ports: the gas can only flow into the left front driving wheel superposition type one-way valve (39) from the gas inlet port a and the gas inlet port b and flow out of the left front driving wheel superposition type one-way valve (39) from the gas outlet port c, so that the gas can only flow to the left front driving wheel brake air chamber (44) from the twelfth three-way valve (61) or the front driving shaft relay valve (36) and can not be conducted in the reverse direction; when the air pressure of the air inlet port a is larger than that of the air inlet port b, the port a is communicated with the port c, and the port b is closed; when the air pressure of the air inlet port a is smaller than that of the air inlet port b, the port b and the port c are conducted, and the port a is closed.

The right rear drive wheel check valve (19) has two ports: and the air inlet port a and the air outlet port b are used for controlling the air to flow from the brake air chamber (16) of the right rear driving wheel to the rear driving shaft relay valve (8) only.

The left rear drive wheel check valve (23) has two ports: and the air inlet port a and the air outlet port b can only flow from the air inlet port a to the air outlet port b, and cannot be communicated in the reverse direction, so that the air inlet port a and the air outlet port b are used for controlling the air to only flow from the left rear driving wheel brake air chamber (26) to the rear driving shaft relay valve (8).

The front right drive wheel check valve (50) has two ports: and the air inlet port a and the air outlet port b are used for controlling air to flow from the front right driving wheel brake air chamber (53) to the front driving shaft relay valve (36).

The left front drive wheel check valve (47) has two ports: and the air inlet port a and the air outlet port b are used for controlling the air to flow from the left front driving wheel brake air chamber (44) to the front driving shaft relay valve (36) only.

From the above discussion, it can be seen that the auxiliary air tank (3), the rear drive shaft on-off solenoid valve (5), the first three-way valve (7), the rear drive shaft relay valve (8), the second three-way valve (9), the right rear drive wheel stacked type one-way valve (10), the third three-way valve (11), the right rear drive wheel brake pressure sensor (15), the right rear drive wheel one-way valve (19), the fourth three-way valve (20), the left rear drive wheel one-way valve (23), the fifth three-way valve (30), the left rear drive wheel stacked type one-way valve (31), the sixth three-way valve (32), the front drive shaft relay valve (36), the seventh three-way valve (37), the eighth three-way valve (38), the left front drive wheel stacked type one-way valve (39), the ninth three-way valve (40), the left front drive wheel one-way valve (47), the right front drive wheel one-way valve (50), and the drive wheel brake pressure sensor (15) are added in the existing brake energy recovery system, The brake system comprises a right front driving wheel brake pressure sensor (54), a thirteenth through valve (58), a right front driving wheel superposition type one-way valve (59), an eleventh through valve (60), a twelfth through valve (61), a brake pedal displacement sensor (62), a front driving shaft switch electromagnetic valve (63) and the like, so that each driving wheel brake circuit has two independent high-pressure air sources and a double-circuit structure, and when a driver steps on a brake pedal (1) and does not trigger a brake energy recovery function, high-pressure air required by a left rear driving wheel (28), a right rear driving wheel (13), a left front driving wheel (41) and a right front driving wheel (57) is provided by a main air storage tank (4); when a driver steps on a brake pedal (1) and triggers a braking energy recovery function, high-pressure gas required by the left rear driving wheel (28), the right rear driving wheel (13), the left front driving wheel (41) and the right front driving wheel (57) is provided by the main gas storage tank (4) and the auxiliary gas storage tank (3) with large gas pressure, so that the key problems that the response speed of the coupling braking force of the driving wheels is low and the coupling braking force lags behind the required braking force caused by low gas source pressure in the existing scheme during continuous braking can be effectively solved.

Claims

1. The utility model provides a four-wheel centralized drive electric motor car braking energy recovery system based on stack formula check valve and check valve which characterized in that: the brake system is composed of a brake pedal (1), a brake valve (2), an auxiliary gas storage tank (3), a main gas storage tank (4), a rear drive shaft switch solenoid valve (5), an air compressor (6), a first three-way valve (7), a rear drive shaft relay valve (8), a second three-way valve (9), a right rear drive wheel stacked type one-way valve (10), a third three-way valve (11), a right rear drive wheel speed sensor (14), a right rear drive wheel brake pressure sensor (15), a right rear drive wheel brake air chamber (16), a right rear drive wheel ABS solenoid valve (17), a right rear drive wheel one-way valve (19), a fourth three-way valve (20), a rear shaft drive motor and transmission device (21), a rear shaft drive motor controller (22), a left rear drive wheel one-way valve (23), a left rear drive wheel ABS solenoid valve (25), a left rear drive wheel brake air chamber (26), a left rear drive wheel speed sensor (27), A fifth three-way valve (30), a left rear driving wheel superposed type one-way valve (31), a sixth three-way valve (32), a battery management system (33), a whole vehicle controller (34), a brake controller (35), a front driving wheel relay valve (36), a seventh three-way valve (37), an eighth three-way valve (38), a left front driving wheel superposed type one-way valve (39), a ninth three-way valve (40), a left front driving wheel speed sensor (43), a left front driving wheel brake air chamber (44), a left front driving wheel ABS electromagnetic valve (46), a left front driving wheel one-way valve (47), a front driving motor and transmission device (48), a front driving motor controller (49), a right front driving wheel one-way valve (50), a right front driving wheel ABS electromagnetic valve (51), a right front driving wheel brake air chamber (53), a right front driving wheel brake pressure sensor (54), a right front driving wheel speed sensor (55), A thirteenth through valve (58), a right front driving wheel superposition type one-way valve (59), an eleventh through valve (60), a twelfth through valve (61), a brake pedal displacement sensor (62) and a front driving shaft switch electromagnetic valve (63);

an air outlet port b of the air compressor (6) is connected with an air inlet port a of the main air storage tank (4) through an air path, and an air outlet port a of the air compressor (6) is connected with an air inlet port a of the auxiliary air storage tank (3) through an air path;

an air inlet port a of the brake valve (2) is connected with an air outlet port d of the main air storage tank (4) through an air path, an air inlet port b of the brake valve (2) is connected with an air outlet port c of the main air storage tank (4) through an air path, an air outlet port c of the brake valve (2) is connected with a control port c of the front drive shaft relay valve (36) through an air path, and an air outlet port d of the brake valve (2) is connected with a control port c of the rear drive shaft relay valve (8) through an air path;

an air outlet port b of the auxiliary air storage tank (3) is connected with an air inlet port a of the rear driving shaft switch electromagnetic valve (5) through an air passage, an air outlet port b of the rear driving shaft switch electromagnetic valve (5) is connected with an air inlet port a of the first three-way valve (7) through an air passage, an air outlet port b of the first three-way valve (7) is connected with an air inlet port b of the right rear driving wheel superposition type one-way valve (10) through an air passage, and an air outlet port c of the first three-way valve (7) is connected with an air inlet port b of the left rear driving wheel superposition type one-way valve (31) through an air passage; a port a of the rear drive shaft relay valve (8) is connected with an air outlet port e of the main air storage tank (4) through an air passage, and a port b of the rear drive shaft relay valve (8) is connected with a port b of the second three-way valve (9) through an air passage;

a port a of the second three-way valve (9) is connected with a port c of a fourth three-way valve (20) through an air path, the port a of the fourth three-way valve (20) is connected with an air inlet port a of a right rear driving wheel superposition type one-way valve (10) through an air path, a port b of the fourth three-way valve (20) is connected with an air outlet port b of a right rear driving wheel one-way valve (19) through an air path, the air outlet port c of the right rear driving wheel superposition type one-way valve (10) is connected with a port a of a third three-way valve (11) through an air path, the air inlet port a of the right rear driving wheel one-way valve (19) is connected with a port c of the third three-way valve (11) through an air path, the port b of the third three-way valve (11) is connected with an air inlet port a of a right rear driving wheel ABS solenoid valve (17) through an air path, and the air inlet port b of the right rear driving wheel ABS solenoid valve (17) is connected with a rear driving wheel brake air chamber (16) through an air path;

a right rear driving wheel brake pressure sensor (15) is arranged on the right rear driving wheel brake air chamber (16);

a port c of the second three-way valve (9) is connected with a port c of a sixth three-way valve (32) through an air passage, a port a of the sixth three-way valve (32) is connected with an air inlet port a of the left rear driving wheel superposed type one-way valve (31) through the air passage, a port b of the sixth three-way valve (32) is connected with an air outlet port b of the left rear driving wheel one-way valve (23) through the air passage, an air outlet port c of the left rear driving wheel superposed type one-way valve (31) is connected with a port a of a fifth three-way valve (30) through the air passage, an air inlet port a of the left rear driving wheel one-way valve (23) is connected with a port c of the fifth three-way valve (30) through the air passage, a port b of the fifth three-way valve (30) is connected with an air inlet port a of the left rear driving wheel ABS solenoid valve (25) through the air passage, and an air inlet port b of the left rear driving wheel ABS solenoid valve (25) is connected with a rear driving wheel brake air chamber (26) through the air passage;

an air outlet port c of the auxiliary air storage tank (3) is connected with an air inlet port a of the front driving shaft switch electromagnetic valve (63) through an air passage, an air outlet port b of the front driving shaft switch electromagnetic valve (63) is connected with an air inlet port a of the twelfth three-way valve (61) through an air passage, an air outlet port b of the twelfth three-way valve (61) is connected with an air inlet port b of the right front driving wheel superposition type one-way valve (59) through an air passage, and an air outlet port c of the twelfth three-way valve (61) is connected with an air inlet port b of the left front driving wheel superposition type one-way valve (39) through an air passage;

a port a of the front drive shaft relay valve (36) is connected with an air outlet port b of the main air storage tank (4) through an air passage, and a port b of the front drive shaft relay valve (36) is connected with a port b of a seventh three-way valve (37) through an air passage;

a port a of the seventh three-way valve (37) is connected with a port c of an eleventh three-way valve (60) through an air passage, the port a of the eleventh three-way valve (60) is connected with an air inlet port a of a right front driving wheel superposition type one-way valve (59) through the air passage, a port b of the eleventh three-way valve (60) is connected with an air outlet port b of a right front driving wheel one-way valve (50) through the air passage, the air outlet port c of the right front driving wheel superposition type one-way valve (59) is connected with a port a of a thirteenth one-way valve (58) through the air passage, the air inlet port a of the right front driving wheel one-way valve (50) is connected with a port c of a thirteenth one-way valve (58) through the air passage, the port b of the thirteenth one-way valve (58) is connected with an air inlet port a of a right front driving wheel ABS solenoid valve (51) through the air passage, and the air inlet port b of the right front driving wheel ABS solenoid valve (51) is connected with a right front driving wheel brake air chamber (53) through the air passage;

a right front driving wheel brake pressure sensor (54) is arranged on the right front driving wheel brake air chamber (53);

a port c of the seventh three-way valve (37) is connected with a port c of an eighth three-way valve (38) through an air passage, a port a of the eighth three-way valve (38) is connected with an air inlet port a of a left front driving wheel superposition type one-way valve (39) through an air passage, a port b of the eighth three-way valve (38) is connected with an air outlet port b of a left front driving wheel one-way valve (47) through an air passage, an air outlet port c of the left front driving wheel superposition type one-way valve (39) is connected with a port a of a ninth three-way valve (40) through an air passage, an air inlet port a of the left front driving wheel one-way valve (47) is connected with a port c of the ninth three-way valve (40) through an air passage, a port b of the ninth three-way valve (40) is connected with an air inlet port a of a left front driving wheel ABS solenoid valve (46) through an air passage, and an air inlet port b of the left front driving wheel ABS solenoid valve (46) is connected with a left front driving wheel brake air chamber (44) through an air passage;

the right rear driving wheel speed sensor (14), the left rear driving wheel speed sensor (27), the left front driving wheel speed sensor (43) and the right front driving wheel speed sensor (55) are connected with the brake controller (35) through signal lines;

the right rear driving wheel ABS electromagnetic valve (17), the left rear driving wheel ABS electromagnetic valve (25), the left front driving wheel ABS electromagnetic valve (46) and the right front driving wheel ABS electromagnetic valve (51) are connected with the brake controller (35) through signal lines;

the rear driving shaft switch electromagnetic valve (5), the right rear driving wheel brake pressure sensor (15), the right front driving wheel brake pressure sensor (54), the brake pedal displacement sensor (62) and the front driving shaft switch electromagnetic valve (63) are connected with the whole vehicle controller (34) through signal lines;

2. The braking energy recovery system of four-wheel centralized drive electric vehicle based on the stacked one-way valve and one-way valve as claimed in claim 1, wherein the vehicle control unit (34) determines whether to trigger the braking energy recovery function based on the vehicle speed outputted by the braking control unit (35) through the CAN bus, the pedal displacement signal outputted by the braking pedal displacement sensor (62), the maximum charging current allowed by the battery outputted by the battery management system (33) through the CAN bus, the maximum motor braking force provided by the rear axle driving motor and the transmission device (21) outputted by the rear axle driving motor controller (22) through the CAN bus, the maximum motor braking force provided by the front axle driving motor and the transmission device (48) outputted by the front axle driving motor controller (49) through the CAN bus, and controls the rear drive axle switch solenoid valve (5) and the front drive axle switch solenoid valve (63) accordingly, the method is characterized in that:

when a brake pedal is stepped on and a braking energy recovery function is triggered, the whole vehicle controller (34) controls the conduction of the rear driving shaft switch electromagnetic valve (5), and the gas path between the port b of the auxiliary gas storage tank (3) and the port a of the first three-way valve (7) is conducted; the whole vehicle controller (34) controls the conduction of the front drive shaft switch electromagnetic valve (63), and the gas path between the port c of the auxiliary gas storage tank (3) and the port a of the twelfth three-way valve (61) is conducted;

when a brake pedal is stepped on but the braking energy recovery function is not triggered, the whole vehicle controller (34) controls the rear driving shaft switch electromagnetic valve (5) to be switched off, and an air path between the port b of the auxiliary air storage tank (3) and the port a of the first three-way valve (7) is not communicated; the whole vehicle controller (34) controls the front drive shaft switch electromagnetic valve (63) to be turned off, and an air path between a port c of the auxiliary air storage tank (3) and a port a of the twelfth three-way valve (61) is not communicated;