阅读说明：本技术 自动变速器的液压控制装置 (Hydraulic control device for automatic transmission ) 是由 任华林 李臣南 郑勇 杨加丰 陈杨山 于 2019-09-26 设计创作，主要内容包括：本发明公开了一种自动变速器的液压控制装置,包括第一失效切换阀、第二失效切换阀、与第一失效切换阀和第二失效切换阀连接的第三失效切换阀、与第一失效切换阀、第二失效切换阀和第三失效切换阀连接的离合器系统、与所述第二失效切换阀连接且用于在变速器进入失效模式时为所述第一失效切换阀提供油液的调压电磁阀以及用于控制第一失效切换阀的开关电磁阀,开关电磁阀为常低电磁阀,调压电磁阀为常高电磁阀。本发明自动变速器的液压控制装置,所有离合器制动器控制的调压电磁阀种类只有一种,且为常低型电磁阀,降低了成本,并提高变速器的安全性。(The invention discloses a hydraulic control device of an automatic transmission, which comprises a first failure switching valve, a second failure switching valve, a third failure switching valve connected with the first failure switching valve and the second failure switching valve, a clutch system connected with the first failure switching valve, the second failure switching valve and the third failure switching valve, a pressure regulating electromagnetic valve connected with the second failure switching valve and used for providing oil for the first failure switching valve when the transmission enters a failure mode, and a switch electromagnetic valve used for controlling the first failure switching valve, wherein the switch electromagnetic valve is a normally low electromagnetic valve, and the pressure regulating electromagnetic valve is a normally high electromagnetic valve. The hydraulic control device of the automatic transmission has the advantages that only one type of pressure regulating electromagnetic valve is used for controlling all the clutch brakes, and the pressure regulating electromagnetic valve is a normally low type electromagnetic valve, so that the cost is reduced, and the safety of the transmission is improved.)

1. A hydraulic control apparatus for an automatic transmission, including a first failure switching valve, a second failure switching valve, a third failure switching valve connected to the first failure switching valve and the second failure switching valve, and a clutch system connected to the first failure switching valve, the second failure switching valve, and the third failure switching valve, characterized in that: still include with the second switching valve that loses efficacy is connected and is used for when the derailleur gets into failure mode for first switching valve that loses efficacy provides the pressure regulating solenoid valve of fluid and the on-off solenoid valve that is used for controlling first switching valve that loses efficacy, and the on-off solenoid valve is the solenoid valve that hangs down, and the pressure regulating solenoid valve is the solenoid valve that hangs down.

2. The hydraulic control apparatus of an automatic transmission according to claim 1, characterized in that: the clutch system comprises a first clutch connected with the third failure switching valve, a second clutch and a third clutch connected with a first control system and a second control system through the first failure switching valve, and a fourth clutch and a brake connected with the second failure switching valve, wherein the first failure switching valve and the third failure switching valve are connected with the first control system.

3. The hydraulic control apparatus of an automatic transmission according to claim 2, characterized in that: the first failure switching valve is provided with a first control oil port (3a), a second control oil port (3g), a third control oil port (3h), a first oil inlet (3b), a second oil inlet (3i), a first oil outlet (3c), a second oil outlet (3e), a third oil inlet (3d) and a fourth oil inlet (3f), the first control oil port (3a) of the first failure switching valve is connected with a first oil outlet (6d) of the third failure switching valve, the second failure switching valve and the third failure switching valve are used for guiding oil from the control oil port of the pressure regulating electromagnetic valve to the first control oil port (3a) of the first failure switching valve, the second control oil port (3g) of the first failure switching valve is connected with the oil outlet (Prd) of the pressure reducing valve, and the third control oil port (3h) of the first failure switching valve is connected with the oil outlet of the switch electromagnetic valve, the first oil outlet (3c) of the first failure switching valve is connected with the second clutch, the second oil outlet (3e) of the first failure switching valve is connected with the third clutch, the first oil inlet (3b) of the first failure switching valve is connected with the first control system and the second control oil port (6b) of the third failure switching valve, the third oil inlet (3d) of the first failure switching valve is connected with the second control system, and the fourth oil inlet (3f) of the first failure switching valve is connected with the main pressure regulating valve.

4. The hydraulic control apparatus of an automatic transmission according to claim 3, characterized in that: the second failure switching valve is provided with a first control oil port (5a), a second control oil port (5b), a first oil inlet (5c) and a first oil outlet (5d), the first control oil port (5a) of the second failure switching valve is connected with a fourth clutch, the second control oil port (5b) of the second failure switching valve is connected with a brake, the first oil inlet (5c) of the second failure switching valve is connected with the control oil port of the pressure regulating electromagnetic valve, and the first oil outlet (5d) of the second failure switching valve is connected with the first oil inlet (6c) of the third failure switching valve.

5. The hydraulic control apparatus of an automatic transmission according to claim 4, characterized in that: when the transmission enters a failure mode, the oil pressure of the first clutch, the fourth clutch, the brake and the first control system is zero, the switch solenoid valve and the pressure regulating solenoid valve are powered off, the control oil port of the pressure regulating solenoid valve is in a maximum oil pressure state, oil of the control oil port of the pressure regulating solenoid valve flows to the first control oil port (3a) of the first failure switching valve through the second failure switching valve and the third failure switching valve, so that a fourth oil inlet (3f) and a second oil outlet (3e) of the first failure switching valve are communicated, meanwhile, a second oil inlet (3i) and a first oil outlet (3c) of the first failure switching valve are communicated, a main pressure regulating valve is communicated with the third clutch through the first failure switching valve, a D-gear oil path of the manual valve is communicated with the second clutch through the first failure switching valve, and oil from the main pressure regulating valve flows to the third clutch through the first failure switching valve, oil from a D gear oil circuit of the manual valve flows to the second clutch through the first failure switching valve, and the second clutch and the third clutch form a failure gear at the moment.

6. The hydraulic control apparatus of an automatic transmission according to claim 4 or 5, characterized in that: when the transmission does not need to enter a failure mode, the switch electromagnetic valve is electrified, oil liquid at an oil outlet of the switch electromagnetic valve enters a third control oil port (3h) of the first failure switching valve to push the valve core to move, a third oil inlet (3d) of the first failure switching valve is communicated with a second oil outlet (3e), so that the second control system is communicated with the third clutch through the first failure switching valve, a first oil outlet (3c) of the first failure switching valve is communicated with a first oil inlet (3b), and the second clutch is communicated with the first control system through the first failure switching valve.

7. The hydraulic control apparatus according to any one of claims 4 to 6, characterized in that: when the transmission works normally, the oil pressure of one or two of the first clutch, the fourth clutch, the brake and the first control system is larger than zero, the oil flowing into the control oil port of the second failure switching valve or the third failure switching valve pushes the valve core to move, so that the oil liquid at the first oil outlet (5d) of the second failure switching valve or the first oil outlet (6d) of the third failure switching valve can be discharged through the EX port, the pressure of the control oil port (3a) of the first failure switching valve is zero, the spring of the first failure switching valve pushes the valve core to reset, the third oil inlet (3d) of the first failure switching valve is communicated with the second oil outlet (3e), communicating the second control system with the third clutch through a first fail switch valve, and a first oil outlet (3c) and a first oil inlet (3b) of the first failure switching valve are communicated, such that the second clutch is in communication with the first control system through a first fail switch valve.

Technical Field

The invention belongs to the technical field of gearboxes, and particularly relates to a hydraulic control device of an automatic transmission.

Background

In an automatic transmission, an electro-hydraulic system is generally used for shift control, and in order to improve safety performance, power supply to a solenoid valve of the hydraulic system is generally cut off when a transmission control unit detects a failure and cannot handle the failure. The hydraulic system will then enter a specific safety gear to keep the vehicle still able to travel to the service site. In the prior art, normally high pressure regulating solenoid valves (when power is off, the solenoid valves output high pressure) are generally adopted for control systems of clutches or brakes forming specific failure gears, normally low pressure regulating solenoid valves are adopted for control systems of other clutches or brakes, and the required pressure regulating solenoid valves for controlling the clutches and brakes are various and have poor safety performance.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. The invention provides a hydraulic control device of an automatic transmission, aiming to improve the safety performance of the automatic transmission.

In order to achieve the purpose, the invention adopts the technical scheme that: the hydraulic control device of the automatic transmission comprises a first failure switching valve, a second failure switching valve, a third failure switching valve connected with the first failure switching valve and the second failure switching valve, a clutch system connected with the first failure switching valve, the second failure switching valve and the third failure switching valve, a pressure regulating electromagnetic valve connected with the second failure switching valve and used for providing oil for the first failure switching valve when the transmission enters a failure mode, and a switch electromagnetic valve used for controlling the first failure switching valve, wherein the switch electromagnetic valve is a normally low electromagnetic valve, and the pressure regulating electromagnetic valve is a normally high electromagnetic valve.

The clutch system comprises a first clutch connected with the third failure switching valve, a second clutch and a third clutch connected with a first control system and a second control system through the first failure switching valve, and a fourth clutch and a brake connected with the second failure switching valve, wherein the first failure switching valve and the third failure switching valve are connected with the first control system.

The first failure switching valve is provided with a first control oil port, a second control oil port, a third control oil port, a first oil inlet, a second oil inlet, a first oil outlet, a second oil outlet, a third oil inlet and a fourth oil inlet, the first control oil port of the first failure switching valve is connected with the first oil outlet of the third failure switching valve, the second failure switching valve and the third failure switching valve are used for guiding oil from the control oil port of the pressure regulating electromagnetic valve to the first control oil port of the first failure switching valve, the second control oil port of the first failure switching valve is connected with the oil outlet of the pressure reducing valve, the third control oil port of the first failure switching valve is connected with the oil outlet of the switch electromagnetic valve, the first oil outlet of the first failure switching valve is connected with the second clutch, the second oil outlet of the first failure switching valve is connected with the third clutch, and the first oil inlet of the first failure switching valve is connected with the second control oil ports of the first control system and the third failure switching valve And an oil making port is connected, a third oil inlet of the first failure switching valve is connected with the second control system, and a fourth oil inlet of the first failure switching valve is connected with the main pressure regulating valve.

The second failure switching valve is provided with a first control oil port, a second control oil port, a first oil inlet and a first oil outlet, the first control oil port of the second failure switching valve is connected with the fourth clutch, the second control oil port of the second failure switching valve is connected with the brake, the first oil inlet of the second failure switching valve is connected with the control oil port of the pressure regulating electromagnetic valve, and the first oil outlet of the second failure switching valve is connected with the first oil inlet of the third failure switching valve.

When the transmission enters a failure mode, the oil pressure of the first clutch, the fourth clutch, the brake and the first control system is zero, the switch solenoid valve and the pressure regulating solenoid valve are powered off, the control oil port of the pressure regulating solenoid valve is in a maximum oil pressure state, oil of the control oil port of the pressure regulating solenoid valve flows to the first control oil port of the first failure switching valve through the second failure switching valve and the third failure switching valve, the fourth oil inlet and the second oil outlet of the first failure switching valve are communicated, the second oil inlet and the first oil outlet of the first failure switching valve are communicated, the main pressure regulating valve is communicated with the third clutch through the first failure switching valve, the D-gear oil path of the manual valve is communicated with the second clutch through the first failure switching valve, oil from the main pressure regulating valve flows to the third clutch through the first failure switching valve, and oil from the D-gear oil path of the manual valve flows to the second clutch through the first failure switching valve, the second clutch and the third clutch constitute a failure gear at this time.

When the transmission does not need to enter a failure mode, the switch electromagnetic valve is powered on, oil at an oil outlet of the switch electromagnetic valve enters a third control oil port of the first failure switching valve to push the valve core to move, a third oil inlet of the first failure switching valve is communicated with a second oil outlet, so that the second control system is communicated with the third clutch through the first failure switching valve, a first oil outlet of the first failure switching valve is communicated with a first oil inlet, and the second clutch is communicated with the first control system through the first failure switching valve.

When the transmission works normally, the oil pressure of one or two of the first clutch, the fourth clutch, the brake and/or the first control system is larger than zero, the oil flowing into the second failure switching valve or the third failure switching valve controls the oil port to push the valve core to move, so that the oil at the first oil outlet of the second failure switching valve or the first oil outlet of the third failure switching valve can be discharged through the EX port, the control oil port pressure of the first failure switching valve is zero, the spring of the first failure switching valve pushes the valve core to reset, the third oil inlet of the first failure switching valve is communicated with the second oil outlet, communicating the second control system with the third clutch through a first fail switch valve, and a first oil outlet and a first oil inlet of the first failure switching valve are communicated, so that the second clutch is communicated with the first control system through the first failure switching valve.

The hydraulic control device of the automatic transmission has the advantages that only one type of pressure regulating electromagnetic valve is used for controlling all the clutch brakes, and the pressure regulating electromagnetic valve is a normally low type electromagnetic valve, so that the cost is reduced, and the safety of the transmission is improved.

Drawings

The description includes the following figures, the contents shown are respectively:

FIG. 1 is a schematic structural view of a hydraulic control apparatus of an automatic transmission of the present invention;

labeled as: 1. a filter; 2. an oil pump; 3. a first failure switching valve; 3a, a first control oil port; 3b, a first oil inlet; 3c, a first oil outlet; 3d, a third oil inlet; 3e, a second oil outlet; 3f, a fourth oil inlet; 3g, a second control oil port; 3h, a third control oil port; 3i and a second oil inlet; 4. switching on and off the electromagnetic valve; 4a, an oil outlet; 5. a second failure switching valve; 5a, a first control oil port; 5b, a second control oil port: 5c, a first oil inlet; 5d, a first oil outlet; EX, oil drain port; 6. a third failure switching valve; 6a, a first control oil port; 6b, a second control oil port; 6c, a first oil inlet; 6d, a first oil outlet; EX, oil drain port; 7. a first clutch; 8. a second clutch; 9. a third clutch; 10. a fourth clutch; 11. a brake; 12. a first control system; 13. a second control system; 14. a main pressure regulating valve; 15. a pressure regulating solenoid valve; prd, an oil outlet of the pressure reducing valve.

Detailed Description

The following detailed description of the embodiments of the present invention will be given with reference to the accompanying drawings for a purpose of helping those skilled in the art to more fully, accurately and deeply understand the concept and technical solution of the present invention and to facilitate its implementation.

It should be noted that, in the following embodiments, the terms "first", "second", "third" and "fourth" do not represent absolute differences in structure and/or function, nor represent a sequential execution order, but merely for convenience of description.

As shown in fig. 1, the present invention provides a hydraulic control apparatus for an automatic transmission, including a main regulator valve, a first failure switching valve 3, a second failure switching valve 5, a third failure switching valve 6 connected to the first failure switching valve 3 and the second failure switching valve 5, a clutch system connected to the first failure switching valve 3, the second failure switching valve 5, and the third failure switching valve 6, a pressure regulating solenoid valve 15 connected to the second failure switching valve 5 and configured to supply oil to the first failure switching valve 3 when the transmission enters a failure mode, and an on-off solenoid valve 4 configured to control the first failure switching valve 3, wherein the on-off solenoid valve 4 is a normally low solenoid valve, and the pressure regulating solenoid valve 15 is a normally high solenoid valve.

Specifically, as shown in fig. 1, the clutch system includes a first clutch 7 connected to a third failure switching valve 6, a second clutch 8 and a third clutch 9 connected to a first control system 12 and a second control system 13 via the first failure switching valve 3, and a fourth clutch 10 and a brake 11 connected to the second failure switching valve 5, the first failure switching valve 3 and the third failure switching valve 6 are connected to the first control system 12, the second control system 13 is connected to the first failure switching valve 3, and the second clutch 8 and the third clutch 9 are connected to the first failure switching valve 3. The switch electromagnetic valve 4 controls the state of the first failure switching valve 3, the switch electromagnetic valve 4 is used for controlling the valve core of the first failure switching valve 3 to be switched from the first state to the second state, a return spring used for pushing the valve core to be switched from the first state to the second state is further arranged inside the first failure switching valve 3, and the return spring, a pressure reducing valve and the switch electromagnetic valve 4 are matched to realize the return of the first failure switching valve 3.

As shown in fig. 1, the first failure switching valve 3 has a first control oil port 3a, a second control oil port 3g, a third control oil port 3h, a first oil inlet 3b, a second oil inlet 3i, a first oil outlet 3c, a second oil outlet 3e, a third oil inlet 3d, and a fourth oil inlet 3f, and the third failure switching valve 6 has a first control oil port 6a, a second control oil port 6b, a first oil inlet 6c, and a first oil outlet 6 d. A first control oil port 3a of the first failure switching valve 3 is connected with a first oil outlet 6d of a third failure switching valve 6, a second failure switching valve 5 and the third failure switching valve 6 are used for guiding oil from a control oil port of a pressure-regulating solenoid valve 15 to the first control oil port 3a of the first failure switching valve 3, a second control oil port 3g of the first failure switching valve 3 is connected with an oil outlet Prd of a pressure-reducing valve, a third control oil port 3h of the first failure switching valve 3 is connected with an oil outlet 4a of a switch solenoid valve 4, a first oil outlet 3c of the first failure switching valve 3 is connected with a second clutch 8, a second oil outlet 3e of the first failure switching valve 3 is connected with a third clutch 9, a first oil inlet 3b of the first failure switching valve 3 is connected with a first control system 12 and a second control oil port 6b of the third failure switching valve 6, the first control system 12 is connected with a second control oil port 6b of the third failure switching valve 6, the third oil inlet 3D of the first failure switching valve 3 is connected to the second control system 13, the fourth oil inlet 3f of the first failure switching valve 3 is connected to the main pressure regulating valve 14, and the second oil inlet 3i of the first failure switching valve 3 is connected to a D-range oil path of a manual valve of the transmission, which is formed when the manual valve is in a D-range position (forward range position), and which implements a forward range of the transmission.

As shown in fig. 1, the second failure switching valve 5 has a first control oil port 5a, a second control oil port 5b, a first oil inlet 5c and a first oil outlet 5d, the first control oil port 5a of the second failure switching valve 5 is connected to the fourth clutch 10, the second control oil port 5b of the second failure switching valve 5 is connected to the brake 11, the first oil inlet 5c of the second failure switching valve 5 is connected to the control oil port of the pressure regulating solenoid valve 15, the first oil outlet 5d of the second failure switching valve 5 is connected to the first oil inlet 6c of the third failure switching valve 6, and the pressure regulating solenoid valve 15 is connected to the main pressure regulating valve 14. By providing the second failure switching valve 5 and the third failure switching valve 6, the oil pressure of the control port of the pressure regulating solenoid valve 15 is connected to the first control port 3a of the first failure switching valve 3, thereby realizing the control of the clutch.

As shown in fig. 1, the on-off solenoid valve 4 is used for controlling the state of the first failure switching valve 3, the on-off solenoid valve 4 has an oil outlet 4a, the on-off solenoid valve 4 is connected to an oil outlet Prd of a pressure reducing valve provided in a main oil path of the transmission, a second control oil port 3g of the first failure switching valve 3 is connected to the oil outlet Prd of the pressure reducing valve, and a third control oil port 3h of the first failure switching valve 3 is connected to the oil outlet 4a of the on-off solenoid valve 4. When the switch electromagnetic valve 4 is electrified, the oil outlet 4a of the switch electromagnetic valve 4 is communicated with the oil outlet Prd of the pressure reducing valve, the oil pressure of the oil outlet 4a of the switch electromagnetic valve 4 is the same as the oil pressure of the oil outlet Prd of the pressure reducing valve, and the oil pressure of the oil outlet 4a of the switch electromagnetic valve 4 is larger than zero.

As shown in fig. 1, when the transmission is normally operated and the vehicle is normally running, any one of the first clutch 7, the fourth clutch 10, the brake 11 and the first control system 12 has a pressure output, the oil flowing into the control port of the second failure switching valve 5 or the third failure switching valve 6 pushes the spool of the second failure switching valve 5 or the third failure switching valve 6 to move, the spool of the second failure switching valve 5 or the third failure switching valve 6 moves to the spring end (the oil from the first clutch 7 enters the valve cavity of the third failure switching valve 6 through the first control port 6a of the third failure switching valve 6 to push the spool to move toward the spring end, the oil from the fourth clutch 10 enters the valve cavity of the second failure switching valve 5 through the first control port 5a of the second failure switching valve 5 to push the spool to move toward the spring end, the oil from the brake 11 enters the valve cavity of the second failure switching valve 5 through the second control oil port 5b of the second failure switching valve 5 to push the valve core to move towards the spring end, the oil from the first control system 12 enters the valve cavity of the third failure switching valve 6 through the second control oil port 6b of the third failure switching valve 6 to push the valve core to move towards the spring end, namely, the valve core presses the return spring, so that the first oil outlet 5d of the second failure switching valve 5 is communicated with the oil discharge port EX of the second failure switching valve 5 or the first oil outlet 6d of the third failure switching valve 6 is communicated with the oil discharge port EX of the third failure switching valve 6, and further the oil of the first oil outlet 5d of the second failure switching valve 5 or the first oil outlet 6d of the third failure switching valve 6 can be respectively discharged through the oil discharge ports EX of the second failure switching valve 5 or the third failure switching valve 6, the oil of the oil outlet Prd of the pressure reducing valve enters the second control oil port 3g of the first failure switching valve 3 to push the valve core of the first failure switching valve 3 to move, because the first control oil port 3a is communicated with the first oil outlet 6d or the first control oil port 3a is communicated with the first oil outlet 5d through the third failure switching valve 6, the oil of the first control oil port 3a can be discharged, and then the valve core of the first failure switching valve 3 moves to a non-spring end under the action of the spring force generated by the reset spring and the pressure of the second control oil port 3g, the first failure switching valve 3 is in a spring reset state, in this state, the third oil inlet 3d and the second oil outlet 3e of the first failure switching valve 3 are communicated, the first oil outlet 3c and the first oil inlet 3b of the first failure switching valve 3 are communicated, so that the second control system 13 is communicated with the third clutch 9 through the first failure switching valve 3, and the second clutch 8 is caused to communicate with the first control system 12 through the first fail switch valve 3. The first control system 12 regulates the pressure of the second clutch 8, the first control system 12 is used for controlling the connection and the disconnection of the second clutch 8, the second control system 13 regulates the pressure of the third clutch 9, and the second control system 13 is used for controlling the connection and the disconnection of the third clutch 9, so that the normal gear change of the transmission is realized.

Therefore, when the vehicle is normally running, any one or two of the first clutch 7, the fourth clutch 10, the brake 11 and the first control system 12 has a combined pressure to control the state of the second failure switching valve 5 or the third failure switching valve 6, the first control port of the pressure regulating solenoid valve 15, which is hydraulically connected to the first failure switching valve 3, is cut off by the second failure switching valve 5 or the third failure switching valve 6, and the spool of the first failure switching valve 3 is at the non-spring end and cannot enter the failure gear. By means of the structure, the safety accident that other clutch brakes have pressure to cause the locking of the output shaft of the transmission when the transmission enters a failure mode gear is avoided.

As shown in fig. 1, when the transmission enters the failure mode, and a fault is detected at this time, the transmission control unit cuts off the power supply of all the solenoid valves, the oil pressure of the first clutch 7, the fourth clutch 10, the brake 11 and the first control system 12 is zero, the on-off solenoid valve 4 and the pressure regulating solenoid valve 15 are powered off, the control port of the pressure regulating solenoid valve 15 is in the maximum oil pressure state (at this time, the oil pressure of the control port of the pressure regulating solenoid valve 15 is maximum), the spools of the second failure switching valve 5 and the third failure switching valve 6 are at the non-spring end under the action of the spring force generated by the return spring, the second failure switching valve 5 and the third failure switching valve 6 are in the spring return state, the oil pressures at the first control port 5a and the second control port 5b of the second failure switching valve 5 are zero, the oil pressures at the first control port 6a and the second control port 6b of the third failure switching, at this time, the first oil inlet 5c and the first oil outlet 5d of the second failure switching valve 5 are communicated, the first oil inlet 6c and the first oil outlet 6d of the third failure switching valve 6 are communicated, the control oil port of the pressure regulating solenoid valve 15 is communicated with the first control oil port 3a of the first failure switching valve 3 through the second failure switching valve 5 and the third failure switching valve 6, the oil in the control oil port of the pressure regulating solenoid valve 15 flows to the first control oil port 3a of the first failure switching valve 3 through the second failure switching valve 5 and the third failure switching valve 6, the oil entering the first control oil port 3a of the first failure switching valve 3 pushes the valve core to move to the spring end of the first failure switching valve 3 (i.e. the valve core pushes the reset spring), so that the valve core of the first failure switching valve 3 is switched from the second state to the first state, and the valve core of the first failure switching valve 3 is in the first state, the fourth oil inlet 3f of the first failure switching valve 3 is communicated with the second oil outlet 3e, and simultaneously the second oil inlet 3i of the first failure switching valve 3 is communicated with the first oil outlet 3c, further, the main pressure regulating valve 14 is communicated with the third clutch 9 through the first failure switching valve 3, the D-range oil path of the manual valve is communicated with the second clutch 8 through the first failure switching valve 3, thus, the hydraulic fluid from the main pressure regulating valve 14 flows through the first failure switching valve 3 to the third clutch 9 to engage the third clutch 9, the hydraulic fluid from the D-range oil passage of the manual valve flows through the first failure switching valve 3 to the second clutch 8 to engage the second clutch 8, and at this time, the second clutch 8 and the third clutch 9 are engaged, the second clutch 8 and the third clutch 9 constitute a failure range, and the transmission is placed in a failure range in which the second clutch 8 and the third clutch 9 are engaged. An oil inlet of the main pressure regulating valve 14 is connected with an oil pump, an oil outlet of the main pressure regulating valve 14 is connected with the first failure switching valve 3, an oil inlet and an oil outlet of the main pressure regulating valve 14 are communicated, and a control oil port of the main pressure regulating valve 14 is connected with a pressure regulating electromagnetic valve 15.

As shown in fig. 1, when the transmission does not need to enter the failure mode, the on-off solenoid valve 4 is energized, the oil pressure at the oil outlet 4a of the on-off solenoid valve 4 is the same as the oil pressure at the oil outlet Prd of the pressure reducing valve, the third control port 3h of the first failure switching valve 3 has pressure, the oil at the oil outlet Prd of the pressure reducing valve enters the second control port 3g of the first failure switching valve 3, the spool of the first failure switching valve 3 is pushed to move by the spool of the first failure switching valve 3, the spool of the first failure switching valve 3 moves to the non-spring end under the action of the spring force generated by the return spring and the pushing action of the oil from the third control port 3h and the second control port 3g, so that the spool of the first failure switching valve 3 is switched from the first state to the second state, the first failure switching valve 3 is in the spring return state, the spool of the first failure switching valve, the third oil inlet 3d and the second oil outlet 3e of the first failure switching valve 3 are communicated, the first oil outlet 3c and the first oil inlet 3b of the first failure switching valve 3 are communicated, so that the second control system 13 is communicated with the third clutch 9 through the first failure switching valve 3, the second control system 13 controls the third clutch 9 to be combined and separated, the second clutch 8 is communicated with the first control system 12 through the first failure switching valve 3, and the first control system 1 controls the second clutch 8 to be combined and separated. The second clutch 8 and the third clutch 9 are normally shifted under the control of the clutch control system.

Therefore, the first failure switching valve 3 can be controlled by the normally low solenoid valve so that the automatic transmission is not in the failure mode.

The invention is described above with reference to the accompanying drawings. It is to be understood that the specific implementations of the invention are not limited in this respect. Various insubstantial improvements are made by adopting the method conception and the technical scheme of the invention; the present invention is not limited to the above embodiments, and can be modified in various ways.