Wet clutch control device and control method for hybrid power new energy vehicle considering sliding wear temperature rise effect

Abstract

The invention discloses a wet clutch control device and method for a hybrid power new energy vehicle with the slip wear temperature rise effect considered. The wet clutch control device comprises a wet clutch, a hydraulic device and an electronic control unit. Rotating speed sensors are arranged at an input shaft and an output shaft of the wet clutch, and a temperature sensor is arranged at an oil inlet of the clutch; the hydraulic device comprises an oil tank, a filter, an oil pump, an overflow valve, a three-position three-way electromagnetic directional valve, a throttle valve, a three-position four-way electromagnetic directional valve, a hydraulic control one-way valve, a cartridge valve and a cooler; and the rotating speed sensor, the temperature sensor, an electromagnet of the three-position three-way electromagnetic directional valve, an electromagnet of the three-position four-way electromagnetic directional valve, a road slope signal, a gear signal, an accelerator opening degree and a brake signal are respectively connected with the electronic control unit. The device is simple in structure and accurate in control; the working conditions of complete connection, sliding friction and complete separation of the wet clutch can be maintained for a long time, the working temperature of the clutch is maintained within a reasonable range through a dynamic clutch oil inlet and outlet mode, and the service life of the clutch is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of control of wet clutches for hybrid new energy vehicles, and particularly relates to a control device and a control method for a wet clutch for hybrid new energy vehicles considering the effect of sliding friction temperature rise. Background Art

[0002] Since the friction plate is immersed in lubricating oil, the wet clutch has smooth engagement and disengagement performance, can effectively reduce the impact and vibration during driving, and improve comfort. Moreover, the wet clutch has a high and stable friction coefficient and can transmit a large torque. Therefore, the wet clutch can be equipped on new energy commercial vehicles with multi-speed gearboxes to meet complex working conditions and large torque transmission requirements. On the other hand, wet clutches are used in hybrid new energy vehicles. For example, in some hybrid vehicle models using dual-clutch transmissions (DCT), the wet clutch can better handle the power transmission requirements of the frequent switching between the motor and the engine in the hybrid system, ensuring the smoothness and reliability of the power switching process. However, during the power transmission process of the wet clutch, there is a sliding friction phenomenon between the friction plate and the mating component, which will cause the temperature to rise. Although its heat dissipation performance is relatively good, if the sliding friction time is too long, the frequency is too high, or the working load is too large, the temperature will still exceed the normal range.

[0003] Too high temperature will cause ablation on the surface of the friction plate, resulting in a sharp drop in its friction coefficient and poor engagement performance of the wet clutch. At the same time, high temperature will also reduce the mechanical properties of the friction plate material. Being in a high temperature state for a long time is likely to cause deformation of the friction plate, further affecting the normal operation of the wet clutch. In addition, if the instantaneous temperature change rate of the wet clutch is too large, internal stress will be generated in the friction plate material due to rapid thermal expansion. When the stress exceeds the bearing limit of the material, problems such as micro-cracks and deformation will occur in the friction plate, affecting its normal friction performance and service life. Too high an instantaneous temperature change rate will cause the viscosity of the wet clutch oil to decrease rapidly and the oil film strength to weaken, unable to form an effective lubricating and heat dissipating oil film between the friction plates, aggravating the wear and heat generation of the friction plates. Summary of the Invention

[0004] In order to solve the above technical problems, the invention provides a control device and a control method for a wet clutch for hybrid new energy vehicles considering the effect of sliding friction temperature rise, which has a simple structure and high control precision, enables the hydraulic oil to circulate inside the wet clutch, continuously takes away heat from the high-temperature area, and then dissipates the heat to the external environment through a cooler, maintaining the working temperature of the wet clutch within a reasonable range, and enabling the wet clutch to remain in the optimal sliding friction working condition for a long time when not powered on.

[0005] The technical solution adopted by the present invention is as follows: A wet clutch control device for a hybrid new energy vehicle considering the effect of sliding friction temperature rise, characterized in that: it includes a wet clutch, a hydraulic device and an electronic control unit; speed sensors I and II are provided at both the input shaft and the output shaft of the wet clutch; the hydraulic device includes a fuel tank, a filter, an oil pump, a relief valve, a three-position three-way electromagnetic reversing valve, a throttle valve I, a throttle valve II, a three-position four-way electromagnetic reversing valve, a hydraulic check valve I, a hydraulic check valve II, a cartridge valve I, a cartridge valve II, and a cooler; the inlet of the filter is connected to the fuel tank, and the outlet of the filter is connected to the inlet of the oil pump; the outlet of the oil pump is connected to port A of the three-position three-way electromagnetic reversing valve, port P of the cartridge valve I, and the inlet of the relief valve through a pipeline, and the outlet of the relief valve is connected to the fuel tank; port T of the three-position three-way electromagnetic reversing valve is connected to the hydraulic control port T of the hydraulic check valve I and the hydraulic control port T of the hydraulic check valve II, and port P of the three-position three-way electromagnetic reversing valve is connected to port A of the three-position four-way electromagnetic reversing valve; port O of the three-position four-way electromagnetic reversing valve is connected to the fuel tank, port T of the three-position four-way electromagnetic reversing valve is respectively connected to port T of the cartridge valve II and port P of the hydraulic check valve II, port A of the hydraulic check valve II is connected to the fuel tank, and port P of the three-position four-way electromagnetic reversing valve is respectively connected to port P of the hydraulic check valve I and port T of the cartridge valve I; port A of the cartridge valve I is connected to the oil inlet of the wet clutch and port A of the cartridge valve II, port P of the cartridge valve II is connected to the cooler, and the cooler is connected to the fuel tank; the speed sensor I, the speed sensor II, the temperature sensor, the electromagnet 1YA of the three-position three-way electromagnetic reversing valve, the electromagnet 2YA of the three-position three-way electromagnetic reversing valve, the electromagnet 3YA of the three-position four-way electromagnetic reversing valve, the electromagnet 4YA of the three-position four-way electromagnetic reversing valve, the road slope signal, the gear signal, the throttle opening, and the brake signal are respectively connected to the electronic control unit.

[0006] In the above-mentioned wet clutch control device for a hybrid new energy vehicle considering the effect of sliding friction temperature rise, the hydraulic control port T of the hydraulic check valve I and the hydraulic control port T of the hydraulic check valve II are connected to port T of the three-position three-way electromagnetic reversing valve;

[0007] In the above-mentioned wet clutch control device for a hybrid new energy vehicle considering the effect of sliding friction temperature rise, the T port of the cartridge valve is connected to the O port of the hydraulic check valve;

[0008] In the above-mentioned wet clutch control device for a hybrid new energy vehicle considering the effect of sliding friction temperature rise, port P of the cartridge valve I is connected to port A of the three-position three-way electromagnetic reversing valve.

[0009] A wet clutch control method for a hybrid new energy vehicle considering the effect of sliding friction temperature rise using the above-mentioned wet clutch control device for a hybrid new energy vehicle considering the effect of sliding friction temperature rise is as follows in specific operations:

[0010] When the wet clutch enters the optimal slip friction condition or the fully engaged condition from the fully disengaged condition, the following steps are included:

[0011] 1) The electronic control unit determines whether the wet clutch needs to enter the fully engaged state from the fully disengaged condition according to the road gradient, the braking signal and the gear signal. If so, it enters step 10). If not, it proceeds to the next step 2);

[0012] 2) Determine whether the wet clutch needs to enter the optimal slip friction condition from the fully disengaged condition in the actual working condition. If so, it proceeds to the next step 3). If not, it returns to the previous step 1);

[0013] 3) The electronic control unit sets the optimal target slip ratio e0 of the wet clutch, the temperature threshold T C and the temperature change rate threshold tc according to the road gradient signal, the throttle opening and the gear signal;

[0014] 4) Start the oil pump. The electronic control unit controls the electromagnet 1YA to be de-energized, controls the electromagnet 2YA to be energized, and the three-position five-way solenoid directional valve works in the right position. The oil port A of the three-position five-way solenoid directional valve is connected to the oil port P of the three-position five-way solenoid directional valve. The electronic control unit controls the electromagnet 3YA to be energized and the magnet 4YA to be de-energized. The four-way three-position solenoid directional valve works in the left position. The P port of the four-way three-position solenoid directional valve is connected to the O port of the four-way three-position solenoid directional valve. The A port of the four-way three-position solenoid directional valve is connected to the T port of the four-way three-position solenoid directional valve. The pressure oil output by the oil pump is input to the oil port T of the cartridge valve II through the A port of the three-position five-way solenoid directional valve, the P port of the three-position five-way solenoid directional valve, the A port of the four-way three-position solenoid directional valve, and the T port of the four-way three-position solenoid directional valve. The pressure oil at the T port of the cartridge valve I flows back to the oil tank through the P port of the four-way three-position solenoid directional valve and the O port of the four-way three-position solenoid directional valve. The P port and the A port of the cartridge valve I are connected. The pressure oil output by the oil pump is input to the oil port A of the wet clutch through the P port of the cartridge valve I and the A port of the cartridge valve I, controlling the main and driven disks of the wet clutch to start engaging;

[0015] 5) The electronic control unit measures the rotational speeds of the input shaft I of the wet clutch and the output shaft O of the wet clutch through the rotational speed sensor I and the rotational speed sensor II, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft, and n2 is the rotational speed of the output shaft;

[0016] 6) Compare the actual slip ratio e with the optimal target slip ratio e0 in real time. After the actual slip ratio e is consistent with the optimal target slip ratio e0, turn off the oil pump. The electronic control unit controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be in the off state. The three-way three-position electromagnetic directional control valve and the four-way three-position electromagnetic directional control valve are both in the middle position to form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch under the optimal target slip ratio condition;

[0017] 7) The electronic control unit measures the real-time temperature T of the wet clutch through the temperature sensor and calculates the temperature change rate t;

[0018] 8) Compare the real-time temperature T of the wet clutch with the temperature threshold T C , and the temperature change rate t with the temperature change rate threshold tc. If T < T C , and it is determined that the wet clutch does not need to enter the fully engaged state from the optimal target slip ratio condition, return to step 6); if T < T C , and it is determined that the wet clutch needs to enter the fully engaged state from the optimal target slip ratio condition, perform step 10); if T ≥ T C , and t < tc, perform step 9);

[0019] 9) Start the oil pump. The electronic control unit controls the electromagnets 1YA and 3YA to be in the power-off state and controls the electromagnets 2YA and 4YA to be in the power-on state. The three-way three-position electromagnetic directional control valve works in the right position, and the oil ports A and P of the three-way three-position electromagnetic directional control valve are connected. The four-way three-position electromagnetic directional control valve works in the right position, and the oil ports A and P of the four-way three-position electromagnetic directional control valve are connected. The oil ports O and T of the four-way three-position electromagnetic directional control valve are connected. The hydraulic oil at the oil port T of the cartridge valve II flows back to the oil tank through the oil ports T and O of the four-way three-position electromagnetic directional control valve. The oil ports A and P of the cartridge valve II are connected. The pressure oil at the oil port A of the wet clutch flows back to the oil tank through the port A, port P of the cartridge valve II and the cooler, reducing the engagement pressure between the driving and driven discs of the wet clutch, continuously taking heat away from the high-temperature area, and dissipating the heat to the external environment through the cooler until T < T C , then perform step 5);

[0020] 10) Start the oil pump. The electronic control unit controls the electromagnet 1YA to be de-energized and the electromagnet 2YA to be energized. The three-way two-position electromagnetic directional valve works in the right position, and the oil ports A and P of the three-way two-position electromagnetic directional valve are connected. The electronic control unit controls the electromagnet 3YA to be energized and the magnet 4YA to be de-energized. The four-way three-position electromagnetic directional valve works in the left position, and the P port and O port of the four-way three-position electromagnetic directional valve are connected, and the A port and T port of the four-way three-position electromagnetic directional valve are connected. The pressurized oil output by the oil pump is input to the oil port T of the cartridge valve II through the oil port A of the three-way two-position electromagnetic directional valve, the P port of the three-way two-position electromagnetic directional valve, the A port of the four-way three-position electromagnetic directional valve, and the T port of the four-way three-position electromagnetic directional valve. The pressurized oil output by the oil pump is input to the oil port A of the wet clutch through the P port and A port of the cartridge valve I, and the engagement oil pressure of the wet clutch is further increased to control the further engagement of the driving and driven discs of the wet clutch;

[0021] 11) The electronic control unit measures the rotational speeds at the input shaft and output shaft of the wet clutch through the speed sensor I 16 and the speed sensor II 14, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft and n2 is the rotational speed of the output shaft;

[0022] 12) After the actual slip ratio e reaches 0, turn off the oil pump. The electronic control unit controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be all in the de-energized state. The three-way two-position electromagnetic directional valve and the four-way three-position electromagnetic directional valve both work in the middle position to form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch under the fully engaged condition;

[0023] 13) The electronic control unit measures the real-time temperature T of the wet clutch through the temperature sensor and calculates the temperature change rate t;

[0024] 14) Compare the real-time temperature T of the wet clutch with the temperature threshold T C , and the temperature change rate t and the temperature change rate threshold tc in real time. If T < T C , then return to step 12); if T ≥ T C , and t < tc, then return to step 9); if T ≥ T C , and t ≥ tc, then proceed to step 15);

[0025] 15) Start the oil pump. The electronic control unit controls the electromagnet 1YA to be energized and controls the electromagnets 2YA, 3YA, and 4YA to be de-energized. The three-position three-way electromagnetic directional valve works in the left position, and the oil ports A and T of the three-position three-way electromagnetic directional valve are connected. The pressure oil output by the oil pump enters the control port T of the pilot-operated check valve I through port A of the three-position three-way electromagnetic directional valve, port T of the three-position three-way electromagnetic directional valve, and throttle valve II. The pressure oil output by the oil pump enters the control port T of the pilot-operated check valve II through port A of the three-position three-way electromagnetic directional valve, port T of the three-position three-way electromagnetic directional valve, and throttle valve I. The hydraulic oil at port T of the cartridge valve I flows back to the fuel tank through ports P and A of the pilot-operated check valve I. The hydraulic oil at port T of the cartridge valve II flows back to the fuel tank through ports P and A of the pilot-operated check valve II. The hydraulic oil at port T of the cartridge valve I11 flows back to the fuel tank 1 through ports P and A of the pilot-operated check valve I9. The port P and port A of the cartridge valve I11 are connected. The hydraulic oil at port T of the cartridge valve II12 flows back to the fuel tank 1 through ports P and A of the pilot-operated check valve II10. The port A and port P of the cartridge valve II12 are connected. The pressure oil output by the oil pump enters port A of the wet clutch through port P of the cartridge valve I and port A of the cartridge valve I. The pressure oil at port A of the wet clutch flows back to the fuel tank through port A of the cartridge valve II, port P of the cartridge valve II, and the cooler, realizing the dynamic inlet and outlet of the hydraulic oil, continuously taking away the heat from the high-temperature area, and dissipating the heat to the external environment through the cooler until T < T C , and t < tc / 2, then go to step 5);

[0026] When the wet clutch enters the optimal slip friction condition or the fully disengaged condition from the fully engaged condition, it includes the following steps:

[0027] 1) The electronic control unit judges according to the road slope, braking signal, and gear signal whether the wet clutch needs to enter the fully disengaged state from the fully engaged condition in the actual working condition. If so, go to step 7); if not, go to the next step;

[0028] 2) Judge whether the wet clutch needs to enter the optimal slip friction condition from the fully engaged condition in the actual working condition. If so, go to the next step; if not, return to step 1);

[0029] 3) The electronic control unit sets the optimal target slip ratio e1 of the wet clutch according to the road slope signal, throttle opening, and gear signal;

[0030] 4) Start the oil pump. The electronic control unit controls the electromagnets 1YA and 3YA to be in the de-energized state, and controls the electromagnets 2YA and 4YA to be in the energized state. The three-way solenoid directional control valve works in the right position, the oil port A of the three-way solenoid directional control valve is connected to the oil port P of the three-way solenoid directional control valve. The four-way solenoid directional control valve works in the right position, the oil port A of the four-way solenoid directional control valve is connected to the oil port P of the four-way solenoid directional control valve, and the oil port O and the oil port T of the four-way solenoid directional control valve are connected. The hydraulic oil at the oil port T of the cartridge valve II flows back to the oil tank through the oil port T and the oil port O of the four-way solenoid directional control valve. The oil port A and the oil port P of the cartridge valve II are connected. The pressure oil at the oil port A of the wet clutch flows back to the oil tank through the port A, the port P of the cartridge valve II and the cooler, reducing the engagement pressure of the wet clutch and controlling the separation of the driving and driven discs of the wet clutch;

[0031] 5) The electronic control unit measures the rotational speeds at the input shaft and the output shaft of the wet clutch through the speed sensor I and the speed sensor II, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft and n2 is the rotational speed of the output shaft;

[0032] 6) Compare the actual slip ratio e with the optimal target slip ratio e1 in real time. After the actual slip ratio e is consistent with the optimal target slip ratio e0, turn off the oil pump. The electronic control unit controls the electromagnets 1YA, 2YA, 3YA and 4YA to be in the de-energized state. The three-way solenoid directional control valve and the four-way solenoid directional control valve both work in the middle position. The cartridge valve I and the cartridge valve II form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch under the optimal target slip ratio condition;

[0033] 7) The electronic control unit measures the real-time temperature T of the wet clutch through the temperature sensor and calculates the temperature change rate t;

[0034] 8) Compare the real-time temperature T of the wet clutch with the temperature threshold T C , and the temperature change rate t and the temperature change rate threshold tc in real time. If T < T C , and it is determined that the wet clutch does not need to enter the fully separated state from the optimal target slip ratio condition, return to step 6); if T < T C , and it is determined that the wet clutch needs to enter the fully separated state from the optimal target slip ratio condition, then perform step 9);

[0035] 9) The electronic control unit sets the maximum slip ratio e of the wet clutch according to the road slope signal, the throttle opening and the gear signal max ;

[0036] 10) Start the oil pump. The electronic control unit controls the electromagnets 1YA and 3YA to be in the de-energized state, and controls the electromagnets 2YA and 4YA to be in the energized state. The three-way two-position solenoid directional valve works in the right position, and the oil port A of the three-way two-position solenoid directional valve is connected to the oil port P of the three-way two-position solenoid directional valve. The four-way three-position solenoid directional valve works in the right position, and the oil port A of the four-way three-position solenoid directional valve is connected to the oil port P of the four-way three-position solenoid directional valve. The oil port O of the four-way three-position solenoid directional valve is connected to the oil port T of the four-way three-position solenoid directional valve. The hydraulic oil at the oil port T of the cartridge valve II flows back to the oil tank through the oil port T and the oil port O of the four-way three-position solenoid directional valve. The oil port A of the cartridge valve II is connected to the oil port P of the cartridge valve II. The pressure oil at the oil port A of the wet clutch flows back to the oil tank through the port A, the port P of the cartridge valve II and the cooler, reducing the pressure at the oil port A of the wet clutch and further increasing the separation rate of the driving and driven discs of the wet clutch.

[0037] 11) The electronic control unit measures the rotational speeds at the input shaft and the output shaft of the wet clutch through the speed sensor I and the speed sensor II, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft and n2 is the rotational speed of the output shaft.

[0038] 12) Until the actual slip ratio e is max consistent with the maximum slip ratio e, turn off the oil pump. The electronic control unit controls the electromagnets 1YA, 2YA, 3YA and 4YA to be in the de-energized state. The three-way two-position solenoid directional valve and the four-way three-position solenoid directional valve both work in the middle position. The cartridge valve I and the cartridge valve II form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch under the maximum slip ratio condition.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] The wet clutch control device for hybrid new energy vehicles considering the sliding friction temperature rise effect of the present invention is real-time accurate and easy to operate; the present invention provides judgment criteria for the full engagement, sliding friction, and full separation of the wet clutch according to the road gradient, braking signal, and gear signal, and design criteria for setting the target slip ratio according to the road gradient signal, throttle opening, and gear signal. The criteria are simple and have strong anti-interference ability; according to the real-time temperature T and temperature threshold TC, as well as the temperature change rate t and temperature change rate threshold tc, the control device and control method of the present invention can achieve a dynamic oil inlet and outlet mode, which helps to maintain the working temperature of the clutch within a reasonable range and prevent damage to the clutch caused by excessive temperature; through the wet clutch sliding friction adaptive control device of the present invention, the wet clutch can be kept in the full engagement, sliding friction, and full separation working conditions for a long time without power supply; generally, the present invention can maintain the wet clutch in the full engagement, sliding friction, and full separation working conditions for a long time, and maintain the working temperature of the clutch within a reasonable range, improving the service life of the clutch.

[0041] The present invention provides a wet clutch control device and control method for hybrid new energy vehicles considering the sliding friction temperature rise effect, which has a simple structure and high control accuracy, enables hydraulic oil to circulate inside the wet clutch, continuously takes away heat from the high-temperature area, and then dissipates the heat to the external environment through a cooler, maintains the working temperature of the wet clutch within a reasonable range, and enables the wet clutch to maintain the optimal sliding friction working condition for a long time without power supply. Brief Description of the Drawings

[0042] Figure 1 is a schematic structural diagram of the wet clutch control device for hybrid new energy vehicles considering the sliding friction temperature rise effect of the present invention.

[0043] In the figure: 1. Fuel tank, 2. Filter, 3. Oil pump, 4. Relief valve, 5. Three-position three-way solenoid directional control valve, 6. Throttle valve I, 7. Throttle valve II, 8. Three-position four-way solenoid directional control valve, 9. Hydraulic control check valve I, 10. Hydraulic control check valve II, 11. Cartridge valve I, 12. Cartridge valve II, 13. Cooler, 14. Rotation speed sensor II, 15. Wet clutch, 16. Rotation speed sensor I, 17. Temperature sensor, 18. Electronic control unit, 19. Road gradient, 20. Gear signal, 21. Throttle opening. Detailed Embodiment

[0044] The following further describes the present invention with reference to the drawings.

[0045] As Figure 1As shown in the figure, the wet clutch control device for hybrid new energy vehicles considering the effect of sliding friction temperature rise of the present invention includes a wet clutch 15, a hydraulic device, and an electronic control unit 18; a speed sensor I 16 and a speed sensor II 14 are respectively arranged at the input shaft I and the output shaft O of the wet clutch.

[0046] The hydraulic device includes an oil tank 1, a filter 2, an oil pump 3, a relief valve 4, a three-position three-way electromagnetic reversing valve 5, a throttle valve I 6, a throttle valve II 7, a three-position four-way electromagnetic reversing valve 8, a hydraulic control check valve I 9, a hydraulic control check valve II 10, a cartridge valve I 11, a cartridge valve II 12, and a cooler 13; the inlet of the filter 2 is connected to the oil tank 1, and the outlet of the filter 2 is connected to the inlet of the oil pump 3; the outlet of the oil pump 3 is communicated with the port A of the three-position three-way electromagnetic reversing valve 5, the port P of the cartridge valve I 11, and the inlet of the relief valve 4 through a pipeline, and the outlet of the relief valve 4 is connected to the oil tank 1; the port T of the three-position three-way electromagnetic reversing valve 5 is connected to the hydraulic control port T of the hydraulic control check valve I 9 and the hydraulic control port T of the hydraulic control check valve II 10, and the port P of the three-position three-way electromagnetic reversing valve 5 is connected to the port A of the three-position four-way electromagnetic reversing valve 8; the port O of the three-position four-way electromagnetic reversing valve 8 is connected to the oil tank 1, the port T of the three-position four-way electromagnetic reversing valve 8 is respectively connected to the port T of the cartridge valve II 12 and the port P of the hydraulic control check valve II 10, the port A of the hydraulic control check valve II 10 is connected to the oil tank 1, and the port P of the three-position four-way electromagnetic reversing valve 8 is respectively connected to the port P of the hydraulic control check valve I 9 and the port T of the cartridge valve I 11; the port A of the cartridge valve I 11 is connected to the inlet of the wet clutch 15 and the port A of the cartridge valve II 12, the port P of the cartridge valve II 12 is connected to the cooler 13, and the cooler 13 is connected to the oil tank 1; the speed sensor I 16, the speed sensor II 14, the temperature sensor 17, the electromagnet 1YA of the three-position three-way electromagnetic reversing valve 5, the electromagnet 2YA of the three-position three-way electromagnetic reversing valve 5, the electromagnet 3YA of the three-position four-way electromagnetic reversing valve 8, the electromagnet 4YA of the three-position four-way electromagnetic reversing valve 8, the road gradient signal 19, the gear signal 20, the throttle opening 21, and the brake signal 22 are respectively connected to the electronic control unit 18.

[0047] A wet clutch control method for hybrid new energy vehicles considering the effect of sliding friction temperature rise using the above wet clutch control device for hybrid new energy vehicles considering the effect of sliding friction temperature rise is as follows:

[0048] When the wet clutch enters the optimal sliding friction condition or the fully engaged condition from the fully disengaged condition, the following steps are included:

[0049] 1) The electronic control unit 18 judges whether the wet clutch 15 needs to enter the fully engaged state from the fully disengaged state in the actual working condition according to the road gradient 19, the brake signal 22, and the gear signal 20. If so, it enters step 10). If not, it proceeds to the next step;

[0050] 2) Determine whether the wet clutch 15 needs to enter the optimal slip friction condition from the fully disengaged condition under actual working conditions. If so, proceed to the next step 3); otherwise, return to the previous step 1).

[0051] 3) The electronic control unit 18 sets the optimal target slip ratio e0 of the wet clutch 15, sets the temperature threshold T of the wet clutch 15, and sets the temperature change rate threshold tc according to the road slope signal 19, the throttle opening 21, and the gear signal 20. C and the temperature change rate threshold tc;

[0052] 4) Start the oil pump 3. The electronic control unit 18 controls the electromagnet 1YA to be de-energized, controls the electromagnet 2YA to be energized, the three-position three-way electromagnetic reversing valve 5 works in the right position, and the oil port A of the three-position three-way electromagnetic reversing valve 5 is connected to the oil port P of the three-position three-way electromagnetic reversing valve 5; the electronic control unit 18 controls the electromagnet 3YA to be energized, the magnet 4YA to be de-energized, the four-way three-position electromagnetic reversing valve 8 works in the left position, the P port of the four-way three-position electromagnetic reversing valve 8 is connected to the O port of the four-way three-position electromagnetic reversing valve 8, and the A port of the four-way three-position electromagnetic reversing valve 8 is connected to the T port of the four-way three-position electromagnetic reversing valve 8; the pressure oil output by the oil pump 3 is input to the oil port T of the cartridge valve II 12 through the A port of the three-position three-way electromagnetic reversing valve 5, the P port of the three-position three-way electromagnetic reversing valve 5, the A port of the four-way three-position electromagnetic reversing valve 8, and the T port of the four-way three-position electromagnetic reversing valve 8; the pressure oil at the T port of the cartridge valve I 11 flows back to the fuel tank through the P port of the four-way three-position electromagnetic reversing valve 8 and the O port of the four-way three-position electromagnetic reversing valve 8, and the P port and the A port of the cartridge valve I 11 are connected; the pressure oil output by the oil pump 3 is input to the oil port A of the wet clutch 15 through the P port and the A port of the cartridge valve I 11 to control the main and driven discs of the wet clutch 15 to start engaging.

[0053] 5) The electronic control unit 18 measures the rotational speeds of the input shaft I of the wet clutch and the output shaft O of the wet clutch through the rotational speed sensor I 16 and the rotational speed sensor II 14, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft, and n2 is the rotational speed of the output shaft.

[0054] 6) Compare the actual slip ratio e with the optimal target slip ratio e0 in real time until the actual slip ratio e is consistent with the optimal target slip ratio e0, then turn off the oil pump 3. The electronic control unit 18 controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be all in the off state, and the three-position three-way electromagnetic reversing valve 5 and the four-way three-position electromagnetic reversing valve 8 both work in the middle position to form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch 15 under the optimal target slip ratio condition.

[0055] 7) The electronic control unit 18 measures the real-time temperature T of the wet clutch 15 through the temperature sensor 17 and calculates the temperature change rate t;

[0056] 8) Compare the real-time temperature T of the wet clutch 15 with the temperature threshold T in real time C , and the temperature change rate t and the temperature change rate threshold tc. If T < T C , and it is determined that the wet clutch 15 does not need to enter the fully engaged state from the optimal target slip ratio condition, then return to step 6); if T < T C , and it is determined that the wet clutch 15 needs to enter the fully engaged state from the optimal target slip ratio condition, then proceed to step 10); if T ≥ T C , and t < tc, then proceed to step 9);

[0057] 9) Start the oil pump 3. The electronic control unit 18 controls the electromagnets 1YA and 3YA to be in the de-energized state, and controls the electromagnets 2YA and 4YA to be in the energized state; the three-way three-position electromagnetic directional valve 5 works in the right position, the oil ports A and P of the three-way three-position electromagnetic directional valve 5 are connected, the four-way three-position electromagnetic directional valve 8 works in the right position, the oil ports A and P of the four-way three-position electromagnetic directional valve 8 are connected, and the oil port O and oil port T of the four-way three-position electromagnetic directional valve 8 are connected. The hydraulic oil at the oil port T of the cartridge valve II 12 flows back to the oil tank 1 through the oil port T of the four-way three-position electromagnetic directional valve 8 and the oil port O of the four-way three-position electromagnetic directional valve 8, and the oil ports A and P of the cartridge valve II 12 are connected; the pressure oil at the oil port A of the wet clutch 15 flows back to the oil tank 1 through the port A of the cartridge valve II 12, the port P of the cartridge valve II 12 and the cooler 13, reducing the engagement pressure between the driving and driven discs of the wet clutch 15, continuously taking away the heat from the high-temperature area, and dissipating the heat to the external environment through the cooler 13 until T < T C, then proceed to step 5); 10) Start the oil pump 3. The electronic control unit 18 controls the electromagnet 1YA to be in the power-off state and the electromagnet 2YA to be in the power-on state. The three-position three-way electromagnetic directional valve 5 works in the right position, and the oil port A of the three-position three-way electromagnetic directional valve 5 is connected to the oil port P of the three-position three-way electromagnetic directional valve 5; the electronic control unit 18 controls the electromagnet 3YA to be in the power-on state and the magnet 4YA to be in the power-off state. The four-way three-position electromagnetic directional valve 8 works in the left position. The P port of the four-way three-position electromagnetic directional valve 8 is connected to the O port of the four-way three-position electromagnetic directional valve 8, and the A port of the four-way three-position electromagnetic directional valve 8 is connected to the T port of the four-way three-position electromagnetic directional valve 8; the pressure oil output by the oil pump 3 is input to the oil port T of the cartridge valve II 12 through the A port of the three-position three-way electromagnetic directional valve 5, the P port of the three-position three-way electromagnetic directional valve 5, the A port of the four-way three-position electromagnetic directional valve 8, and the T port of the four-way three-position electromagnetic directional valve 8; the pressure oil output by the oil pump 3 is input to the oil port A of the wet clutch 15 through the P port of the cartridge valve I 11 and the A port of the cartridge valve I 11, and the engagement oil pressure of the wet clutch 15 is further increased to control the main and driven disks of the wet clutch 15 to be further engaged;

[0058] 11) The electronic control unit 18 measures the rotational speeds of the input shaft I of the wet clutch and the output shaft O of the wet clutch through the rotational speed sensor I 16 and the rotational speed sensor II 14, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft, and n2 is the rotational speed of the output shaft;

[0059] 12) After the actual slip ratio e reaches 0, turn off the oil pump 3; the electronic control unit 18 controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be all in the off state. The three-position three-way electromagnetic directional valve 5 and the four-way three-position electromagnetic directional valve 8 both work in the middle position to form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch 15 in the fully engaged working condition;

[0060] 13) The electronic control unit 18 measures the real-time temperature T of the wet clutch 15 through the temperature sensor 17 and calculates the temperature change rate t;

[0061] 14) Compare the real-time temperature T of the wet clutch 15 with the temperature threshold T C , and the temperature change rate t and the temperature change rate threshold tc in real time. If T < T C , then return to step 12); if T ≥ T C , and t < tc, then return to step 9); if T ≥ T C , and t ≥ tc, then proceed to step 15);

[0062] 15) Start the oil pump 3. The electronic control unit 18 controls the electromagnet 1YA to be energized and controls the electromagnets 2YA, 3YA, and 4YA to be de-energized. The three-position three-way electromagnetic directional valve 5 works in the left position, and the oil port A of the three-position three-way electromagnetic directional valve 5 is connected to the oil port T of the three-position three-way electromagnetic directional valve 5. The pressurized oil output by the oil pump 3 is input to the hydraulic control port T of the hydraulic control one-way valve I 9 through the A port of the three-position three-way electromagnetic directional valve 5, the T port of the three-position three-way electromagnetic directional valve 5, and the throttle valve II 7. The pressurized oil output by the oil pump 3 is input to the hydraulic control port T of the hydraulic control one-way valve II 10 through the A port of the three-position three-way electromagnetic directional valve 5, the T port of the three-position three-way electromagnetic directional valve 5, and the throttle valve I 6. The hydraulic oil at the oil port T of the cartridge valve I 11 flows back to the oil tank 1 through the P port and A port of the control one-way valve I 9, and the oil port P and the oil port A of the cartridge valve I 11 are connected. The hydraulic oil at the oil port T of the cartridge valve II 12 flows back to the oil tank 1 through the P port and A port of the control one-way valve II 10, and the oil port A and the oil port P of the cartridge valve II 12 are connected. The pressurized oil output by the oil pump 3 is input to the oil port A of the wet clutch 15 through the P port and A port of the cartridge valve I 11. The pressurized oil at the oil port A of the wet clutch 15 flows back to the oil tank 1 through the A port of the cartridge valve II 12, the P port of the cartridge valve II 12, and the cooler 13, realizing the dynamic inflow and outflow of the hydraulic oil, continuously taking away the heat from the high-temperature area, and dissipating the heat to the external environment through the cooler 13 until T < T C , and t < tc / 2, then go to step 5);

[0063] When the wet clutch enters the optimal slip friction condition or the full separation condition from the fully engaged condition, it includes the following steps:

[0064] 1) The electronic control unit 18 judges according to the road slope 19, the brake signal 22, and the gear signal 20 that in the actual working condition, the wet clutch 15 needs to enter the full separation state from the fully engaged condition. If so, go to step 7); if not, go to the next step;

[0065] 2) Judge that in the actual working condition, the wet clutch 15 needs to enter the optimal slip friction condition from the fully engaged condition. If so, go to the next step; if not, return to step 1);

[0066] 3) The electronic control unit 18 sets the optimal target slip ratio e1 of the wet clutch 15 according to the road slope signal 19, the throttle opening 21, and the gear signal 20.

[0067] 4) Start the oil pump 3. The electronic control unit 18 controls the electromagnets 1YA and 3YA to be in the power-off state, and controls the electromagnets 2YA and 4YA to be in the power-on state. The three-way solenoid directional valve 5 works in the right position. The oil port A of the three-way solenoid directional valve 5 is connected to the oil port P of the three-way solenoid directional valve 5. The four-way solenoid directional valve 8 works in the right position. The oil port A of the four-way solenoid directional valve 8 is connected to the oil port P of the four-way solenoid directional valve 8, and the oil port O of the four-way solenoid directional valve 8 is connected to the oil port T of the four-way solenoid directional valve 8. The hydraulic oil at the oil port T of the cartridge valve II 12 flows back to the oil tank 1 through the oil port T and the oil port O of the four-way solenoid directional valve 8. The oil port A and the oil port P of the cartridge valve II 12 are connected. The pressure oil at the oil port A of the wet clutch 15 flows back to the oil tank 1 through the port A, the port P of the cartridge valve II 12 and the cooler 13, reducing the engagement pressure of the wet clutch 15 and controlling the separation of the driving and driven discs of the wet clutch 15;

[0068] 5) The electronic control unit 18 measures the rotational speeds at the input shaft I and the output shaft O of the wet clutch through the speed sensor I 16 and the speed sensor II 14, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft and n2 is the rotational speed of the output shaft;

[0069] 6) Compare the actual slip ratio e with the optimal target slip ratio e1 in real time. After the actual slip ratio e is consistent with the optimal target slip ratio e0, turn off the oil pump 3. The electronic control unit 18 controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be in the off state. The three-way solenoid directional valve 5 and the four-way solenoid directional valve 8 both work in the middle position. The cartridge valve I 11 and the cartridge valve II 12 form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch 15 under the optimal target slip ratio condition;

[0070] 7) The electronic control unit 18 measures the real-time temperature T of the wet clutch 15 through the temperature sensor 17 and calculates the temperature change rate t;

[0071] 8) Compare the real-time temperature T of the wet clutch 15 with the temperature threshold T C , and the temperature change rate t and the temperature change rate threshold tc in real time. If T < T C , and it is determined that the wet clutch 15 does not need to enter the fully separated state from the optimal target slip ratio condition, return to step 6); if T < T C , and it is determined that the wet clutch 15 needs to enter the fully separated state from the optimal target slip ratio condition, then perform step 9);

[0072] 9) The electronic control unit 18 sets the maximum slip ratio e of the wet clutch 15 according to the road slope signal 19, the throttle opening 21, and the gear signal 20. max ;

[0073] 10) Start the oil pump 3. The electronic control unit 18 controls the electromagnet 1YA and the electromagnet 3YA to be in the power-off state, and controls the electromagnet 2YA and the electromagnet 4YA to be in the powered-on state; the three-way and three-position electromagnetic reversing valve 5 works in the right position, the oil port A of the three-way and three-position electromagnetic reversing valve 5 is communicated with the oil port P of the three-way and three-position electromagnetic reversing valve 5, the three-way and four-position electromagnetic reversing valve 8 works in the right position, the oil port A of the three-way and four-position electromagnetic reversing valve 8 and the oil port P of the three-way and four-position electromagnetic reversing valve 8 are communicated, and the oil port O of the three-way and four-position electromagnetic reversing valve 8 and the oil port T of the three-way and four-position electromagnetic reversing valve 8 are communicated. The hydraulic oil at the oil port T of the cartridge valve II 12 flows back to the oil tank 1 through the oil port T and the oil port O of the three-way and four-position electromagnetic reversing valve 8. The oil port A of the cartridge valve II 12 is communicated with the oil port P of the cartridge valve II 12. The pressure oil at the oil port A of the wet clutch 15 flows back to the oil tank 1 through the port A, the port P of the cartridge valve II 12, and the cooler 13, reducing the pressure at the oil port A of the wet clutch 15 and further increasing the separation rate of the driving and driven discs of the wet clutch 15.

[0074] 11) The electronic control unit 18 measures the rotational speeds at the input shaft I and the output shaft O of the wet clutch 15 through the rotational speed sensor I 16 and the rotational speed sensor II 14, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft, and n2 is the rotational speed of the output shaft.

[0075] 12) Until the actual slip ratio e is consistent with the maximum slip ratio e max After that, turn off the oil pump 3. The electronic control unit 18 controls the electromagnet 1YA, the electromagnet 2YA, the electromagnet 3YA, and the electromagnet 4YA to be all in the off state. The three-way and three-position electromagnetic reversing valve 5 and the three-way and four-position electromagnetic reversing valve 8 both work in the middle position. The cartridge valve I 11 and the cartridge valve II 12 form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch 15 under the maximum slip ratio condition.

Claims

1. A wet clutch control device for a hybrid new energy vehicle considering the effect of sliding friction temperature rise, characterized in that: It includes a wet clutch, a hydraulic device and an electronic control unit; speed sensors Ⅰ and Ⅱ are provided at both the input shaft and the output shaft of the wet clutch; the hydraulic device includes an oil tank, a filter, an oil pump, a relief valve, a three-position three-way electromagnetic directional valve, a throttle valve Ⅰ, a throttle valve Ⅱ, a three-position four-way electromagnetic directional valve, a hydraulic check valve Ⅰ, a hydraulic check valve Ⅱ, a cartridge valve Ⅰ, a cartridge valve Ⅱ, and a cooler; the inlet of the filter is connected to the oil tank, and the outlet of the filter is connected to the inlet of the oil pump; the outlet of the oil pump is communicated with port A of the three-position three-way electromagnetic directional valve, port P of the cartridge valve Ⅰ, and the inlet of the relief valve through a pipeline, and the outlet of the relief valve is connected to the oil tank; port T of the three-position three-way electromagnetic directional valve is connected to the hydraulic control port T of the hydraulic check valve Ⅰ and the hydraulic control port T of the hydraulic check valve Ⅱ, and port P of the three-position three-way electromagnetic directional valve is connected to port A of the three-position four-way electromagnetic directional valve; port O of the three-position four-way electromagnetic directional valve is connected to the oil tank, port T of the three-position four-way electromagnetic directional valve is respectively connected to port T of the cartridge valve Ⅱ and port P of the hydraulic check valve Ⅱ, port A of the hydraulic check valve Ⅱ is connected to the oil tank, and port P of the three-position four-way electromagnetic directional valve is respectively connected to port P of the hydraulic check valve Ⅰ and port T of the cartridge valve Ⅰ; port A of the cartridge valve Ⅰ is connected to the oil inlet of the wet clutch and port A of the cartridge valve Ⅱ, port P of the cartridge valve Ⅱ is connected to the cooler, and the cooler is connected to the oil tank; the speed sensor Ⅰ, the speed sensor Ⅱ, the temperature sensor, the electromagnet 1YA of the three-position three-way electromagnetic directional valve, the electromagnet 2YA of the three-position three-way electromagnetic directional valve, the electromagnet 3YA of the three-position four-way electromagnetic directional valve, the electromagnet 4YA of the three-position four-way electromagnetic directional valve, the road gradient signal, the gear signal, the throttle opening, and the brake signal are respectively connected to the electronic control unit.

2. The wet clutch control device for a hybrid new energy vehicle considering the sliding friction temperature rise effect according to claim 1, characterized in that: The hydraulic control port T of the hydraulic check valve Ⅰ and the hydraulic control port T of the hydraulic check valve Ⅱ are connected to port T of the three-position three-way electromagnetic directional valve.

3. The wet clutch control device for hybrid new energy vehicles considering the effect of sliding friction temperature rise according to claim 1, characterized in that: Port T of the cartridge valve is connected to port O of the hydraulic check valve.

4. The wet clutch control device for a hybrid new energy vehicle considering the effect of sliding friction temperature rise according to claim 1, wherein: Port P of the cartridge valve Ⅰ is connected to port A of the three-position three-way electromagnetic directional valve.

5. A method for controlling a wet clutch for a hybrid new energy vehicle considering the sliding friction temperature rise effect by using the wet clutch control device for a hybrid new energy vehicle considering the sliding friction temperature rise effect according to any one of claims 1-4, and the specific operation is as follows: When the wet clutch enters the optimal sliding friction condition or the fully engaged condition from the fully disengaged condition, it includes the following steps: 1) The electronic control unit judges whether the wet clutch needs to enter the fully engaged state from the fully disengaged condition in the actual working condition according to the road gradient, the brake signal and the gear signal. If so, it enters step 10). If not, it proceeds to the next step 2); 2) Judge whether the wet clutch needs to enter the optimal sliding friction condition from the fully disengaged condition in the actual working condition. If so, it proceeds to the next step 3). If not, it returns to the previous step 1); 3) The electronic control unit sets the optimal target slip ratio e0 of the wet clutch and sets the temperature threshold T and the temperature change rate threshold tc of the wet clutch according to the road gradient signal, the throttle opening, and the gear signal. C and the temperature change rate threshold tc; 4) Start the oil pump. The electronic control unit controls the electromagnet 1YA to be in the power-off state and the electromagnet 2YA to be in the power-on state. The three-way three-position electromagnetic directional valve works in the right position, and the oil port A of the three-way three-position electromagnetic directional valve is connected to the oil port P of the three-way three-position electromagnetic directional valve. The electronic control unit controls the electromagnet 3YA to be in the power-on state and the electromagnet 4YA to be in the power-off state. The four-way three-position electromagnetic directional valve works in the left position, and the P port of the four-way three-position electromagnetic directional valve is connected to the O port of the four-way three-position electromagnetic directional valve, and the A port of the four-way three-position electromagnetic directional valve is connected to the T port of the four-way three-position electromagnetic directional valve. The pressurized oil output by the oil pump is input into the oil port T of the cartridge valve II through the oil port A of the three-way three-position electromagnetic directional valve, the oil port P of the three-way three-position electromagnetic directional valve, the oil port A of the four-way three-position electromagnetic directional valve, and the oil port T of the four-way three-position electromagnetic directional valve. The pressurized oil at the T port of the cartridge valve I flows back to the oil tank through the P port of the four-way three-position electromagnetic directional valve and the O port of the four-way three-position electromagnetic directional valve, and the P port and the A port of the cartridge valve I are connected. The pressurized oil output by the oil pump is input into the oil port A of the wet clutch through the P port of the cartridge valve I and the A port of the cartridge valve I, controlling the main and driven disks of the wet clutch to start engaging. 5) The electronic control unit measures the rotational speeds of the input shaft I of the wet clutch and the output shaft O of the wet clutch through the speed sensor I and the speed sensor II, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft, and n2 is the rotational speed of the output shaft. 6) Compare the actual slip ratio e with the optimal target slip ratio e0 in real time. After the actual slip ratio e is consistent with the optimal target slip ratio e0, turn off the oil pump. The electronic control unit controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be in the power-off state. The three-way three-position electromagnetic directional valve and the four-way three-position electromagnetic directional valve both work in the middle position, forming a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch under the optimal target slip ratio condition. 7) The electronic control unit measures the real-time temperature T of the wet clutch through the temperature sensor and calculates the temperature change rate t. 8) Compare the real-time temperature T of the wet clutch with the temperature threshold T in real time C , as well as the temperature change rate t and the temperature change rate threshold tc. If T < T C , and it is determined that the wet clutch does not need to enter the fully engaged state from the optimal target slip ratio condition, then return to step 6); if T < T C , and it is determined that the wet clutch needs to enter the fully engaged state from the optimal target slip ratio condition, then proceed to step 10); if T ≥ T C , and t < tc, then proceed to step 9); 9) Start the oil pump. The electronic control unit controls the electromagnets 1YA and 3YA to be in the power-off state, and controls the electromagnets 2YA and 4YA to be in the power-on state. The three-way two-position solenoid directional valve works in the right position, and the oil ports A and P of the three-way two-position solenoid directional valve are connected. The four-way three-position solenoid directional valve works in the right position, and the oil ports A and P of the four-way three-position solenoid directional valve are connected. The oil ports O and T of the four-way three-position solenoid directional valve are connected. The hydraulic oil at the oil port T of the cartridge valve II flows back to the oil tank through the oil ports T and O of the four-way three-position solenoid directional valve. The oil port A and the oil port P of the cartridge valve II are connected. The pressure oil at the oil port A of the wet clutch flows back to the oil tank through the port A, port P of the cartridge valve II and the cooler, reducing the engagement pressure between the driving and driven discs of the wet clutch, continuously taking heat away from the high-temperature area, and dissipating the heat to the external environment through the cooler until T < T C , then go to step 5); 10) Start the oil pump. The electronic control unit controls the electromagnet 1YA to be in the power-off state and the electromagnet 2YA to be in the power-on state. The three-way three-position electromagnetic directional valve works in the right position, and the oil port A and the oil port P of the three-way three-position electromagnetic directional valve are connected. The electronic control unit controls the electromagnet 3YA to be in the power-on state and the electromagnet 4YA to be in the power-off state. The four-way three-position electromagnetic directional valve works in the left position, and the P port and the O port of the four-way three-position electromagnetic directional valve are connected, and the A port and the T port of the four-way three-position electromagnetic directional valve are connected. The pressurized oil output by the oil pump is input into the oil port T of the cartridge valve II through the oil port A of the three-way three-position electromagnetic directional valve, the oil port P of the three-way three-position electromagnetic directional valve, the oil port A of the four-way three-position electromagnetic directional valve, and the oil port T of the four-way three-position electromagnetic directional valve. The pressurized oil output by the oil pump is input into the oil port A of the wet clutch through the P port of the cartridge valve I and the A port of the cartridge valve I, and the engagement oil pressure of the wet clutch further increases, controlling the main and driven disks of the wet clutch to further engage. 11) The electronic control unit measures the rotational speeds at the input shaft and output shaft of the wet clutch through speed sensor Ⅰ 16 and speed sensor Ⅱ 14, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft, and n2 is the rotational speed of the output shaft; 12) After the actual slip ratio e reaches 0, the oil pump is turned off; the electronic control unit controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be in the off state, and the three-way three-position electromagnetic directional control valve and the four-way three-position electromagnetic directional control valve are both in the middle position to form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch in the fully engaged condition; 13) The electronic control unit measures the real-time temperature T of the wet clutch through the temperature sensor and calculates the temperature change rate t; 14) Compare the real-time temperature T of the wet clutch with the temperature threshold T in real time C , as well as the temperature change rate t and the temperature change rate threshold tc. If T < T C , then return to step 12); if T ≥ T C , and t < tc, then return to step 9); if T ≥ T C , and t ≥ tc, then proceed to step 15); 15) Start the oil pump. The electronic control unit controls the electromagnet 1YA to be energized and controls the electromagnets 2YA, 3YA, and 4YA to be de-energized. The three-position three-way solenoid directional valve works in the left position, and the oil ports A and T of the three-position three-way solenoid directional valve are connected. The pressure oil output by the oil pump is input to the control port T of the pilot-operated check valve I through the port A of the three-position three-way solenoid directional valve, the port T of the three-position three-way solenoid directional valve, and the throttle valve II. The pressure oil output by the oil pump is input to the control port T of the pilot-operated check valve II through the port A of the three-position three-way solenoid directional valve, the port T of the three-position three-way solenoid directional valve, and the throttle valve I. The hydraulic oil at the oil port T of the cartridge valve I flows back to the fuel tank through the P port and A port of the pilot-operated check valve I. The hydraulic oil at the oil port T of the cartridge valve II flows back to the fuel tank through the P port and A port of the pilot-operated check valve II. The hydraulic oil at the oil port T of the cartridge valve I11 flows back to the fuel tank 1 through the P port and A port of the pilot-operated check valve I9. The oil port P and the oil port A of the cartridge valve I11 are connected. The hydraulic oil at the oil port T of the cartridge valve II12 flows back to the fuel tank 1 through the P port and A port of the pilot-operated check valve II10. The oil port A and the oil port P of the cartridge valve II12 are connected. The pressure oil output by the oil pump is input to the oil port A of the wet clutch through the P port and A port of the cartridge valve I. The pressure oil at the oil port A of the wet clutch flows back to the fuel tank through the A port, P port of the cartridge valve II, and the cooler, realizing the dynamic inlet and outlet of the hydraulic oil, continuously taking away the heat from the high-temperature area, and dissipating the heat to the external environment through the cooler until T < T C , and t < tc / 2, then proceed to step 5); When the wet clutch enters the optimal slip friction condition or the fully separated condition from the fully engaged condition, the following steps are included: 1) The electronic control unit determines, based on the road gradient, braking signal, and gear signal, whether the wet clutch needs to enter the fully separated state from the fully engaged condition in the actual working condition. If so, it proceeds to step 7); if not, it proceeds to the next step; 2) Determine whether the wet clutch needs to enter the optimal slip friction condition from the fully engaged condition in the actual working condition. If so, it proceeds to the next step; if not, it returns to step 1); 3) The electronic control unit sets the optimal target slip ratio e1 of the wet clutch according to the road gradient signal, throttle opening, and gear signal; 4) Start the oil pump. The electronic control unit controls the electromagnets 1YA and 3YA to be in the de-energized state, and controls the electromagnets 2YA and 4YA to be in the energized state; the three-way three-position electromagnetic directional control valve works in the right position, the port A of the three-way three-position electromagnetic directional control valve is connected to the port P of the three-way three-position electromagnetic directional control valve, the four-way three-position electromagnetic directional control valve works in the right position, the port A of the four-way three-position electromagnetic directional control valve is connected to the port P of the four-way three-position electromagnetic directional control valve, and the port O and port T of the four-way three-position electromagnetic directional control valve are connected. The hydraulic oil at the port T of the cartridge valve Ⅱ flows back to the fuel tank through the port T and port O of the four-way three-position electromagnetic directional control valve, the port A and port P of the cartridge valve Ⅱ are connected, and the pressure oil at the port A of the wet clutch flows back to the fuel tank through the port A, port P of the cartridge valve Ⅱ, and the cooler, reducing the engagement pressure of the wet clutch and controlling the separation of the driving and driven discs of the wet clutch; 5) The electronic control unit measures the rotational speeds at the input shaft and output shaft of the wet clutch through speed sensor Ⅰ and speed sensor Ⅱ, and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where: n1 is the rotational speed of the input shaft, and n2 is the rotational speed of the output shaft; 6) Compare the actual slip ratio e with the optimal target slip ratio e1 in real time. After the actual slip ratio e is consistent with the optimal target slip ratio e0, turn off the oil pump. The electronic control unit controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be in the off state. The three-way three-position electromagnetic reversing valve and the four-way three-position electromagnetic reversing valve are both in the middle position. The cartridge valve I and the cartridge valve II form a hydraulic locking circuit to maintain the hydraulic pressure required for the wet clutch under the optimal target slip ratio condition. 7) The electronic control unit measures the real-time temperature T of the wet clutch through the temperature sensor and calculates the temperature change rate t. 8) Compare the real-time temperature T of the wet clutch with the temperature threshold T in real time C , as well as the temperature change rate t and the temperature change rate threshold tc. If T < T C , and it is determined that the wet clutch does not need to enter the fully disengaged state from the optimal target slip ratio condition, then return to step 6); if T < T C , and it is determined that the wet clutch needs to enter the fully disengaged state from the optimal target slip ratio condition, then proceed to step 9); 9) The electronic control unit sets the maximum slip ratio e of the wet clutch according to the road slope signal, throttle opening, and gear signal max ; 10) Start the oil pump. The electronic control unit controls the electromagnets 1YA and 3YA to be in the power-off state and controls the electromagnets 2YA and 4YA to be in the power-on state. The three-way three-position electromagnetic reversing valve works in the right position. The oil port A of the three-way three-position electromagnetic reversing valve is connected to the oil port P of the three-way three-position electromagnetic reversing valve. The four-way three-position electromagnetic reversing valve works in the right position. The oil port A of the four-way three-position electromagnetic reversing valve is connected to the oil port P of the four-way three-position electromagnetic reversing valve. The oil port O of the four-way three-position electromagnetic reversing valve is connected to the oil port T of the four-way three-position electromagnetic reversing valve. The hydraulic oil at the oil port T of the cartridge valve II flows back to the oil tank through the oil port T and the oil port O of the four-way three-position electromagnetic reversing valve. The oil port A of the cartridge valve II is connected to the oil port P of the cartridge valve II. The pressure oil at the oil port A of the wet clutch flows back to the oil tank through the A port of the cartridge valve II, the P port of the cartridge valve II, and the cooler, reducing the pressure at the oil port A of the wet clutch and further increasing the separation rate of the driving and driven discs of the wet clutch. 11) The electronic control unit measures the rotational speeds at the input shaft and the output shaft of the wet clutch through the speed sensor I and the speed sensor II and calculates the actual slip ratio e = (n1 - n2) / ω1 in real time, where n1 is the rotational speed of the input shaft and n2 is the rotational speed of the output shaft. 12) Until the actual slip rate e is consistent with the maximum slip rate e max After that, turn off the oil pump. The electronic control unit controls the electromagnets 1YA, 2YA, 3YA, and 4YA to be in the off state. The three-way three-position electromagnetic directional control valve and the four-way three-position electromagnetic directional control valve are both in the middle position. The cartridge valve I and the cartridge valve II form a hydraulic locking circuit to maintain the hydraulic pressure required by the wet clutch under the maximum slip rate condition.

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