8at automatic transmission hydraulic system

Abstract

This invention discloses an 8AT automatic transmission hydraulic system, including a first pressure regulating valve, a second pressure regulating valve, a first switching valve, a main oil circuit, a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve, a fifth solenoid valve, and a sixth solenoid valve. The first and fifth solenoid valves are connected to the forward gear oil circuit, the sixth solenoid valve is connected to the main oil circuit, and the second and fourth solenoid valves are connected to the pressure reducing oil circuit. The first, fifth, third, and sixth solenoid valves are direct-drive solenoid valves, and the second and fourth solenoid valves are pilot-operated solenoid valves. This 8AT automatic transmission hydraulic system uses direct-drive solenoid valves and pilot-operated solenoid valves to control each clutch of the transmission. It utilizes two constant-high pilot-operated solenoid valves to achieve clutch failure modes, simplifying the design of the pressure regulating valve core. The system is simple in structure, compact in design, cost-effective, and reduces the space occupied.

Description

Technical Field

[0001] This invention belongs to the field of automatic transmission technology, specifically relating to an 8AT automatic transmission hydraulic system. Background Technology

[0002] An 8AT automatic transmission refers to an automatic transmission with eight forward gears.

[0003] In related technologies, the hydraulic system of 8AT automatic transmissions often uses pilot solenoid valves and pressure regulating valves for pressure control and regulation, and uses switching valves to realize the failure modes of the transmission, which is complex in structure and high in cost.

[0004] For example, patent document CN107975594A discloses a hydraulic system for an automatic transmission, including a first failure valve, a second failure valve connected to the first failure valve, a normally high solenoid valve for controlling the first failure valve, a clutch system connected to the first failure valve, and a normally low solenoid valve for controlling the second failure valve and for forming two failure gears. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention provides an 8AT automatic transmission hydraulic system with the aim of improving structural compactness.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an 8AT automatic transmission hydraulic system, including a first pressure regulating valve, a second pressure regulating valve, a first switching valve, a main oil circuit, a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve, a fifth solenoid valve, a sixth solenoid valve, and a main pressure regulating valve. The first and fifth solenoid valves are connected to the forward gear oil circuit, the sixth solenoid valve is connected to the main oil circuit, and the second and fourth solenoid valves are connected to the pressure reducing oil circuit. The first, fifth, third, and sixth solenoid valves are direct-drive solenoid valves, and the second and fourth solenoid valves are pilot solenoid valves. The first pressure regulating valve is connected to the forward gear oil circuit and the C2 clutch of the 8AT automatic transmission, the third solenoid valve is connected to the C3 clutch of the 8AT automatic transmission, the second pressure regulating valve is connected to the forward gear oil circuit and the C4 clutch of the 8AT automatic transmission, and the first switching valve is connected to the first solenoid valve and the start-stop oil circuit, which is configured to provide oil to the C1 clutch.

[0007] The pressure reducing oil circuit is connected to the lock-up prohibition valve, the TC solenoid valve is connected to the lock-up prohibition valve, the shuttle valve is connected to the forward gear oil circuit and the reverse gear oil circuit, and the third solenoid valve is connected to the shuttle valve.

[0008] The shuttle valve has a first oil inlet, a second oil inlet, and an oil outlet. The first oil inlet of the shuttle valve is connected to the forward gear oil circuit, the second oil inlet of the shuttle valve is connected to the reverse gear oil circuit, and the oil outlet of the shuttle valve is connected to the oil inlet of the third solenoid valve.

[0009] The oil inlet of the first pressure regulating valve is connected to the forward oil passage, and the oil outlet of the first pressure regulating valve is connected to the C2 clutch.

[0010] The oil inlet of the second pressure regulating valve is connected to the forward oil passage, and the oil outlet of the second pressure regulating valve is connected to the C4 clutch.

[0011] The start-stop oil circuit includes a start-stop pump. The first switching valve has a first oil inlet and a second oil inlet. The first oil inlet of the first switching valve is connected to the oil outlet of the first solenoid valve, and the second oil inlet of the first switching valve is connected to the oil outlet of the start-stop pump.

[0012] The pressure-reducing oil circuit includes a pressure-reducing valve, the oil inlet of which is connected to the main oil circuit, and the oil outlet of which is connected to the second solenoid valve and the fourth solenoid valve.

[0013] The main pressure regulating valve is connected to the P2 oil circuit, which is configured to supply cooling and lubrication oil. The cooling and lubrication oil circuit includes a cooling pressure regulating valve and an oil cooler. The cooling pressure regulating valve is connected to the PL solenoid valve, which is connected to the main pressure regulating valve and the pressure reducing oil circuit. The PL solenoid valve is a pilot solenoid valve.

[0014] The hydraulic system of the 8AT automatic transmission further includes a first pressure holding valve, a second pressure holding valve, a third pressure holding valve, a fourth pressure holding valve, a fifth pressure holding valve, a sixth pressure holding valve, and a seventh pressure holding valve. The first pressure holding valve is located on the unloading oil line of the first solenoid valve, the second and third pressure holding valves are located on the unloading oil line of the C2 clutch, the fourth and fifth pressure holding valves are located on the unloading oil line of the C4 clutch, the sixth pressure holding valve is located on the unloading oil line of the sixth solenoid valve, and the seventh pressure holding valve is located between the shuttle valve and the manual valve. The seventh pressure holding valve is configured to maintain pressure when unloading oil in the forward gear oil line.

[0015] The hydraulic system of the 8AT automatic transmission further includes a first accumulator, a second accumulator, a third accumulator, a fourth accumulator, a fifth accumulator, a sixth accumulator, and a seventh accumulator. The first accumulator is located in the C1 clutch oil circuit and is used to buffer pressure fluctuations in the C1 clutch oil circuit. The second accumulator is located in the B1 clutch oil circuit and is used to buffer pressure fluctuations in the B1 clutch oil circuit. The third accumulator is located in the B2 clutch oil circuit and is used to buffer pressure fluctuations in the B2 clutch oil circuit. The fourth accumulator is located in the C3 clutch oil circuit and is used to buffer pressure fluctuations in the C3 clutch oil circuit. The fifth accumulator is located between the outlet of the second solenoid valve and the first pressure regulating valve and is used to buffer pressure fluctuations in the C2 clutch oil circuit. The sixth accumulator is located between the outlet of the fourth solenoid valve and the second pressure regulating valve and is used to buffer pressure fluctuations in the C4 clutch oil circuit. The seventh accumulator is located between the outlet of the PL solenoid valve and the main pressure regulating valve and is used to buffer pressure fluctuations in the main oil circuit.

[0016] The hydraulic system of the 8AT automatic transmission of the present invention uses direct-drive solenoid valves and pilot solenoid valves to control each clutch of the transmission. It utilizes two constant-high pilot solenoid valves to realize the failure mode of the clutch, simplifies the design of the pressure regulating valve core, has a simple structure, is compact in design, has cost advantages, and reduces the space occupied. Attached Figure Description

[0017] This manual includes the following figures, which illustrate the following:

[0018] Figure 1 This is a schematic diagram of the hydraulic system of the 8AT automatic transmission of the present invention;

[0019] The diagram is marked as follows:

[0020] 1. Oil pump; 2. Filter; 3. Solenoid pump; 4. First switching valve; 5. First accumulator; 6. First solenoid valve; 7. First pressure holding valve; 8. Fifth solenoid valve; 9. Fifth accumulator; 10. First pressure regulating valve; 11. Second solenoid valve; 12. Second pressure regulating valve; 13. Fourth solenoid valve; 14. Cooling pressure regulating valve; 15. Oil cooler; 16. Cooling back pressure valve; 17. Check valve; 18. Cooling safety valve; 19. TC lock-up valve; 20. TC release valve; 21. TC solenoid valve; 22. Sixth solenoid valve; 23. Third solenoid valve; 24. Shuttle valve; 25. Manual valve; 26. Main pressure regulating valve; 27. First filter; 28. Main oil circuit safety valve; 29. ​​Pressure reducing valve; 30. Lock-up / inhibition valve;

[0021] 31. PL solenoid valve; 32. Forward gear oil circuit; 33. Main oil circuit; 34. P2 oil circuit; 35. Pressure reducing oil circuit; 36. Cooling and lubricating oil circuit; 37. Pilot oil circuit; 38. Reverse gear oil circuit; 39. Start-stop oil circuit; 40. Second pressure holding valve; 41. Third pressure holding valve; 42. Fourth pressure holding valve; 43. Fifth pressure holding valve; 44. Sixth pressure holding valve; 45. Seventh pressure holding valve; 46. Second accumulator; 47. Third accumulator; 48. Fourth accumulator; 49. Sixth accumulator; 50. TC pressure holding valve; 51. Second filter; 52. Pressure sensor; 53. Oil temperature sensor; 54. Seventh accumulator; 55. STC oil circuit. Detailed Implementation

[0022] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, in order to help those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solutions of the present invention, and to facilitate its implementation.

[0023] It should be noted that in the following embodiments, the terms "first", "second", "third", "fourth", "fifth", "sixth" and "seventh" do not represent an absolute distinction in structure and / or function, nor do they represent the order of execution, but are merely for the convenience of description.

[0024] like Figure 1 As shown, the present invention provides an 8AT automatic transmission hydraulic system, including an oil pump 1, a start-stop pump 3, a main pressure regulating valve 26 connected to the oil pump 3, a forward gear oil circuit 32 connected to a manual valve 25, a main oil circuit 33 connected to the main pressure regulating valve 26, a P2 oil circuit 34 connected to the main pressure regulating valve 26, a pressure reducing oil circuit 35 connected to a pressure reducing valve 29, a cooling and lubricating oil circuit 36 ​​connected to a TC lock-up valve 19 and a TC release valve 20, a pilot oil circuit 37 connected to a PL solenoid valve 31, a reverse gear oil circuit 38 connected to the manual valve 25, and a start-stop oil circuit 39 connected to the start-stop pump 3.

[0025] Specifically, such as Figure 1As shown, oil pump 1 is a gear pump; first solenoid valve 6, fifth solenoid valve 8, third solenoid valve 23, and sixth solenoid valve 22 are direct-drive solenoid valves; second solenoid valve 11, fourth solenoid valve 13, TC solenoid valve 21, and PL solenoid valve 31 are pilot solenoid valves. First solenoid valve 6 and fifth solenoid valve 8 are connected to the forward gear oil circuit 32; sixth solenoid valve 22 is connected to the main oil circuit 33; second solenoid valve 11, fourth solenoid valve 13, and PL solenoid valve 31 are connected to the pressure reducing oil circuit 35; lock-up / inhibition valve 30 is connected to the pressure reducing oil circuit 35; TC solenoid valve 21 is connected to the lock-up / inhibition valve 30; shuttle valve 24 is connected to the forward gear oil circuit 32 and the reverse gear oil circuit 38; and third solenoid valve is connected to shuttle valve 24. By adjusting the corresponding solenoid valves, the engagement and disengagement of the corresponding clutches inside the transmission can be controlled, realizing commands for forward gears 1-8, as well as parking, neutral, and reverse gears.

[0026] like Figure 1 As shown, the inlet of the first pressure regulating valve 10 is connected to the forward gear oil circuit 32, and the outlet of the first pressure regulating valve 10 is connected to the C2 clutch of the 8AT automatic transmission. The inlet of the second pressure regulating valve 12 is connected to the forward gear oil circuit 32, and the outlet of the second pressure regulating valve 12 is connected to the C4 clutch of the 8AT automatic transmission.

[0027] like Figure 1 As shown, the first switching valve 4 has a first oil inlet, a second oil inlet, a control port and an oil outlet. The first oil inlet of the first switching valve 4 is connected to the oil outlet of the first solenoid valve 6, and the second oil inlet of the first switching valve 4 is connected to the oil outlet of the start-stop pump 3 through the start-stop oil circuit.

[0028] like Figure 1 As shown, the oil inlet of the pressure reducing valve 29 is connected to the main oil circuit 33, and the oil outlet of the pressure reducing valve 29 is connected to the pressure reducing oil circuit 35.

[0029] like Figure 1 As shown, the shuttle valve 24 has a first oil inlet, a second oil inlet, and an oil outlet. The first oil inlet of the shuttle valve 24 is connected to the forward gear oil circuit 32, the second oil inlet of the shuttle valve 24 is connected to the reverse gear oil circuit 38, and the oil outlet of the shuttle valve 24 is connected to the oil inlet of the third solenoid valve 23.

[0030] like Figure 1 As shown, the oil inlet of the cooling pressure regulating valve 14 is connected to the cooling lubrication oil circuit 36, and the oil outlet of the cooling pressure regulating valve 14 is connected to the oil cooler 15.

[0031] like Figure 1As shown, the inlet of the lock-up / prohibition valve 30 is connected to the pressure reducing oil circuit 35, and the outlet of the lock-up / prohibition valve 30 is connected to the inlet of the TC solenoid valve 21. The inlet of the TC lock-up valve 19 is connected to the main oil circuit 33, and the outlet of the TC lock-up valve 19 is connected to the TC connection end (the connection end of the hydraulic torque converter). The inlet of the TC release valve 20 is connected to the P2 oil circuit 34, and the outlet of the TC release valve 20 is connected to the TC release end.

[0032] like Figure 1 As shown, when the transmission is in D gear, the manual valve 25 is in the leftmost position, and the main oil circuit 33 is connected to the forward gear oil circuit 32. The forward gear oil circuit 32 is connected to the oil inlet of the first solenoid valve 6, the oil inlet of the fifth solenoid valve 8, the oil inlet of the first pressure regulating valve 10, the oil inlet of the second pressure regulating valve 12, and the first oil inlet of the shuttle valve 24. The forward gear oil circuit 32 pushes the steel ball inside the shuttle valve 24 to the right end. At this time, the forward gear oil circuit 32 can be connected to the oil inlet of the third solenoid valve 23 through the shuttle valve 24. After the main oil circuit 33 is regulated by the main pressure regulating valve 26, it enters the first filter 27 and the second filter 51, and is connected to the oil inlet of the pressure reducing valve 29. The oil outlet of the pressure reducing valve 29 is connected to the fourth solenoid valve 13.

[0033] The main oil circuit 33, via the rightmost control port of the main pressure regulating valve 26, pushes the valve core of the main pressure regulating valve 26 to the right, connecting the main oil circuit 33 to the P2 oil circuit 34. The rightmost end of the valve core of the main pressure regulating valve 26 is connected to the pilot oil circuit 37. The valve core of the main pressure regulating valve 26 is balanced by the pressure of the main oil circuit 33 at the leftmost end of the valve core, the spring force at the rightmost end of the valve core, and the pressure of the pilot oil circuit 37. By adjusting the current of the PL solenoid valve 31, the pressure of the pilot oil circuit 37 is controlled, thereby achieving the purpose of regulating the oil pressure of the main oil circuit 33. The pressure range of the main oil circuit 33 is set from 0 to 18.3 bar. The pressure sensor 52 can monitor the oil pressure of the main oil circuit 33. A main oil circuit safety valve 28 is installed on the main oil circuit 33 to prevent the system from malfunctioning due to overload.

[0034] like Figure 1 As shown, when the transmission is in D gear, the forward gear oil circuit 32 provides oil to the three direct-drive solenoid valves: the first solenoid valve 6, the fifth solenoid valve 8, and the third solenoid valve 23. By adjusting the current of the corresponding solenoid valve, the oil pressure entering the corresponding clutch can be controlled.

[0035] The pressure-reducing oil circuit 35 supplies oil to four pilot solenoid valves: the second solenoid valve 11, the third solenoid valve 13, the PL solenoid valve 31, and the TC solenoid valve 21. By adjusting the current of the corresponding solenoid valve, the oil pressure entering the corresponding clutch can be controlled. The valve core of the pressure-reducing valve 29 is balanced by the oil pressure in the pressure-reducing oil circuit 35 at the leftmost end of the valve core and the spring force at the rightmost end of the valve core. The pressure-reducing valve 29 controls the pressure in the pressure-reducing oil circuit 35 to 7.8 bar or below to adapt to the pressure adjustment range of the pilot solenoid valves, which is 7.8 to 0 bar or 0 to 7.8 bar. The main oil circuit 33 supplies oil to the sixth solenoid valve 22, which is connected to the B2 clutch of the automatic transmission. By adjusting the current of the sixth solenoid valve 22, the oil pressure entering the B2 clutch of the automatic transmission can be controlled.

[0036] like Figure 1 As shown, the first accumulator 5 is located in the C1 clutch oil circuit and is used to buffer pressure fluctuations in the C1 clutch oil circuit. The C1 clutch oil circuit is connected to the C1 clutch. The second accumulator 46 is located in the B1 clutch oil circuit and is used to buffer pressure fluctuations in the B1 clutch oil circuit. The B1 clutch oil circuit is connected to the B1 clutch. The third accumulator 47 is located in the B2 clutch oil circuit and is used to buffer pressure fluctuations in the B2 clutch oil circuit. The B2 clutch oil circuit is connected to the B2 clutch. The fourth accumulator 48 is located in the C3 clutch oil circuit and is used to buffer pressure fluctuations in the C3 clutch oil circuit. The C3 clutch oil circuit is connected to the C3 clutch. The fifth accumulator 9 is located between the outlet of the second solenoid valve 11 and the first pressure regulating valve 10 and is used to buffer pressure fluctuations in the C2 clutch oil circuit. The C2 clutch oil circuit is connected to the C2 clutch. The sixth accumulator 49 is located between the outlet of the fourth solenoid valve 13 and the second pressure regulating valve 12 and is used to buffer pressure fluctuations in the C4 clutch oil circuit. The C4 clutch oil circuit is connected to the C4 clutch. The seventh accumulator 54 is located between the oil outlet of the PL solenoid valve 31 and the main pressure regulating valve 26, and is used to buffer pressure fluctuations in the main oil circuit. The function of the pressure holding valve is to keep the oil circuit always in a state of oil supply, thereby increasing the system's response speed.

[0037] like Figure 1 As shown, the first pressure holding valve 7 is located in the unloading oil line of the first solenoid valve 6, the second pressure holding valve 40 and the third pressure holding valve 41 are located in the unloading oil line of the C2 clutch, the fourth pressure holding valve 42 and the fifth pressure holding valve 43 are located in the unloading oil line of the C4 clutch, the sixth pressure holding valve 44 is located in the unloading oil line of the sixth solenoid valve 22, and the seventh pressure holding valve 45 is located between the shuttle valve 24 and the manual valve 25. The seventh pressure holding valve is used to maintain pressure when unloading oil in the forward oil blocking circuit 32.

[0038] like Figure 1As shown, a cooling safety valve 18 is installed on the cooling lubrication oil circuit 36. The cooling safety valve 18 is used to control the maximum pressure of the cooling lubrication oil circuit 36 ​​to protect the normal operation of the system. After the cooling lubrication oil circuit 36 ​​is regulated by the cooling pressure regulating valve 14, it enters the oil cooler 15. When the valve core of the cooling pressure regulating valve 14 is balanced by the pressure of the leftmost cooling lubrication oil circuit 36 ​​and the pressure of the rightmost pilot oil circuit 37, the pressure of the cooling oil circuit 36 ​​can be controlled by adjusting the current of the PL solenoid valve 31. After passing through the oil cooler 15, the cooling lubrication oil circuit 36 ​​enters the front and rear transmission mechanisms of the transmission. When the oil cooler 15 is blocked, the cooling oil circuit enters the front and rear transmission mechanisms of the transmission through the bypass oil circuit and the one-way valve 16.

[0039] like Figure 1 As shown, when the TC solenoid valve 21 is not energized, the P2 oil passage 34 is connected to the oil inlet of the TC release valve 20, and the P2 oil passage 34 supplies oil to the TC release end. At this time, the TC is in the released state. There is an area difference between the left and right ends of the oil inlet chamber of the TC release valve 20, so the oil inlet chamber of the TC release valve will generate a pressure difference to the right. At this time, the valve core of the TC release valve 20 is kept in balance under the pressure difference of the oil inlet chamber and the spring force at the rightmost end. When the TC solenoid valve 21 is energized, the valve core of the TC release valve 20 moves to the right under the pressure of the STC oil passage 55. The P2 oil passage 34 is disconnected from the rear oil passage of the TC release valve 20. The valve core of the TC lock-up valve 19 moves to the left under the pressure of the STC oil passage 55. The main oil passage 33 is connected to the oil inlet of the TC lock-up valve 19, and the main oil passage 33 supplies oil to the TC engagement end. At this time, the TC (torque converter) is in the engaged state. The valve core of TC lock-up valve 19 is kept in balance by the pressure at the leftmost TC engagement end, the spring force, and the pressure at the rightmost STC oil passage 55.

[0040] like Figure 1 As shown, when the transmission is in R gear, the manual valve 25 is in the third position from the left. The main oil circuit 33 is connected to the reverse oil circuit 38, which is connected to the second inlet of the shuttle valve 24. The reverse oil circuit 38 pushes the steel ball inside the shuttle valve 24 to the left end. The reverse oil circuit 38 is connected to the third solenoid valve 23 through the shuttle valve 24. When the sixth solenoid valve 22 is energized, the valve core of the lock-up prohibition valve 30 moves to the left under the pressure of the B2 clutch oil circuit. The pressure reducing oil circuit 35 is disconnected from the inlet of the TC solenoid valve 21, preventing the TC from being mistakenly engaged when the B2 clutch is engaged in forward 1st gear, parking gear, neutral gear, or reverse gear.

[0041] like Figure 1As shown, when the engine is turned off in D gear, the start-stop pump 3 is energized. The start-stop pump 3 draws oil from the fuel tank, passes through the filter 2, and enters the start-stop oil circuit 39. When the engine is off, the oil pump 1 does not work, and there is no pressure in the main oil circuit 33 at the control port of the first switching valve 4. The valve core of the first switching valve 4 moves to the right end under the action of the left spring force. At this time, the start-stop oil circuit 39 is connected to the C1 clutch oil circuit, providing oil to the C1 clutch, and the C1 clutch engages. After the engine is ignited, the main oil circuit 33 begins to build pressure, the valve core of the first switching valve 4 moves to the left, and the oil source for the C1 clutch oil circuit switches to the oil outlet of the first solenoid valve 6. The system responds quickly, ensuring that the forward gear C1 clutch is engaged.

[0042] like Figure 1 As shown, the second solenoid valve 12 and the fourth solenoid valve 13 are always-high pilot solenoid valves. When the TCU (Automatic Transmission Control Unit) fails, the second solenoid valve 12 controls the C2 clutch to engage, and the fourth solenoid valve 13 controls the C4 clutch to engage, so that the transmission enters 6th gear mode, preventing further damage to the transmission and ensuring that the owner can drive the vehicle to the repair shop smoothly for repair.

[0043] In this embodiment, the automatic transmission is an 8AT automatic transmission.

[0044] The hydraulic system of the 8AT automatic transmission with the above structure has the following advantages:

[0045] (1) It makes full use of the advantage of the simple structure of the transmission clutch controlled by the direct drive solenoid valve, eliminates the application of the switching solenoid valve, and directly uses the characteristics of the constant high solenoid valve to control the transmission to enter the clutch corresponding to the failed gear, which greatly simplifies the valve body structure design.

[0046] (2) A pressure-holding valve is used to improve the system response speed. An accumulator is installed in the clutch oil circuit to buffer oil pressure fluctuations, making pressure control more stable and improving driving comfort;

[0047] (3) While ensuring functionality, the design is simplified as much as possible, reducing the use of a large number of pressure regulating valves and switching slide valves, eliminating the use of some pressure regulating valve core return springs, simplifying the valve core design, making the design compact and cost-effective.

[0048] (4) The simplified valve body oil circuit design reduces valve body leakage points, which can better provide cooling and lubrication for the planetary gear mechanism of the gearbox and protect the normal operation of the gearbox.

[0049] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

The hydraulic system of the 1.8AT automatic transmission is characterized by: It includes a first pressure regulating valve, a second pressure regulating valve, a first switching valve, a main oil circuit, a first solenoid valve, a second solenoid valve, a third solenoid valve, a fourth solenoid valve, a fifth solenoid valve, a sixth solenoid valve, and a main pressure regulating valve. The first and fifth solenoid valves are connected to the forward gear oil circuit, the sixth solenoid valve is connected to the main oil circuit, and the second and fourth solenoid valves are connected to the pressure reducing oil circuit. The first, fifth, third, and sixth solenoid valves are direct-drive solenoid valves, and the second and fourth solenoid valves are pilot solenoid valves. The first pressure regulating valve is connected to the forward gear oil circuit and the C2 clutch, the third solenoid valve is connected to the C3 clutch, the second pressure regulating valve is connected to the forward gear oil circuit and the C4 clutch, and the first switching valve is connected to the first solenoid valve and the start-stop oil circuit. The start-stop oil circuit is configured to provide oil to the C1 clutch. The pressure reducing oil circuit is connected to the lock-up prohibition valve, the TC solenoid valve is connected to the lock-up prohibition valve, the shuttle valve is connected to the forward gear oil circuit and the reverse gear oil circuit, and the third solenoid valve is connected to the shuttle valve. The start-stop oil circuit includes a start-stop pump. The first switching valve has a first oil inlet and a second oil inlet. The first oil inlet of the first switching valve is connected to the oil outlet of the first solenoid valve, and the second oil inlet of the first switching valve is connected to the oil outlet of the start-stop pump. The pressure-reducing oil circuit includes a pressure-reducing valve, wherein the oil inlet of the pressure-reducing valve is connected to the main oil circuit, and the oil outlet of the pressure-reducing valve is connected to the second solenoid valve and the fourth solenoid valve. The main pressure regulating valve is connected to the P2 oil circuit, which is configured to supply cooling and lubrication oil. The cooling and lubrication oil circuit includes a cooling pressure regulating valve and an oil cooler. The cooling pressure regulating valve is connected to the PL solenoid valve, which is connected to the main pressure regulating valve and the pressure reducing oil circuit. The PL solenoid valve is a pilot solenoid valve.

2. The hydraulic system for an 8AT automatic transmission according to claim 1, characterized in that: The shuttle valve has a first oil inlet, a second oil inlet, and an oil outlet. The first oil inlet of the shuttle valve is connected to the forward gear oil circuit, the second oil inlet of the shuttle valve is connected to the reverse gear oil circuit, and the oil outlet of the shuttle valve is connected to the oil inlet of the third solenoid valve.

3. The hydraulic system for an 8AT automatic transmission according to claim 1, characterized in that: The oil inlet of the first pressure regulating valve is connected to the forward oil passage, and the oil outlet of the first pressure regulating valve is connected to the C2 clutch.

4. The hydraulic system for an 8AT automatic transmission according to claim 1, characterized in that: The oil inlet of the second pressure regulating valve is connected to the forward oil passage, and the oil outlet of the second pressure regulating valve is connected to the C4 clutch.

5. The hydraulic system for an 8AT automatic transmission according to any one of claims 1 to 4, characterized in that: It also includes a first pressure holding valve, a second pressure holding valve, a third pressure holding valve, a fourth pressure holding valve, a fifth pressure holding valve, a sixth pressure holding valve, and a seventh pressure holding valve. The first pressure holding valve is located in the unloading oil line of the first solenoid valve, the second and third pressure holding valves are located in the unloading oil line of the C2 clutch, the fourth and fifth pressure holding valves are located in the unloading oil line of the C4 clutch, the sixth pressure holding valve is located in the unloading oil line of the sixth solenoid valve, and the seventh pressure holding valve is located between the shuttle valve and the manual valve. The seventh pressure holding valve is configured to maintain pressure when unloading oil in the forward oil blocking circuit.

6. The hydraulic system for an 8AT automatic transmission according to any one of claims 1 to 3, characterized in that: It also includes a first accumulator, a second accumulator, a third accumulator, a fourth accumulator, a fifth accumulator, a sixth accumulator, and a seventh accumulator. The first accumulator is located in the C1 clutch oil circuit and is used to buffer the pressure fluctuations in the C1 clutch oil circuit. The second accumulator is located in the B1 clutch oil circuit and is used to buffer the pressure fluctuations in the B1 clutch oil circuit. The third accumulator is located in the B2 clutch oil circuit and is used to buffer the pressure fluctuations in the B2 clutch oil circuit. The fourth accumulator is located in the C3 clutch oil circuit and is used to buffer the pressure fluctuations in the C3 clutch oil circuit. The fifth accumulator is located between the oil outlet of the second solenoid valve and the first pressure regulating valve and is used to buffer the pressure fluctuations in the C2 clutch oil circuit. The sixth accumulator is located between the oil outlet of the fourth solenoid valve and the second pressure regulating valve and is used to buffer the pressure fluctuations in the C4 clutch oil circuit. The seventh accumulator is located between the oil outlet of the PL solenoid valve and the main pressure regulating valve and is used to buffer the pressure fluctuations in the main oil circuit.

Images