Pilot control reversing loop capable of resetting quickly

Abstract

The invention belongs to the technical field of hydraulic control, and discloses a quick reset pilot control reversing loop which comprises an oil pump unit, a pilot control valve, a quick reset unit and a main reversing valve. The quick reset unit comprises a cylinder body and a piston with a through hole in the center, an oil inlet P is formed in the first end face of the cylinder body, a main connecting port A is formed in the second end face of the cylinder body, and an oil return port T is formed in the position, close to the second end face, of the side wall of the cylinder body. When the pilot control valve is opened, pressure oil flows into the cylinder body through the oil inlet P and pushes the piston to move to abut against the second end face, and the pressure oil flows into the main reversing valve through the through hole and the main connector A to push the main reversing valve to reverse. When the pilot control valve is closed, the pressure oil flows back to the cylinder body and pushes the piston to be separated from the second end face, so that the oil return opening T is opened, the pressure oil flows out through the oil return opening T, the main reversing valve is reset, the main reversing valve is not affected by the small drift diameter of the pilot control valve, and therefore the main reversing valve is reset rapidly, working efficiency and reliability are improved, and the application range of a reversing loop is widened.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic control, and more specifically, relates to a fast-reset pilot control reversing circuit. Background Art

[0002] The main function of the hydraulic reversing circuit is to change the direction of the fluid flow and the movement direction of the hydraulic actuator. Reversing valves are generally used in hydraulic equipment to achieve reversing. The reversing circuit in hydraulic equipment is the core factor affecting the response speed of the equipment. Due to the advantages of simple structure, few components, and sensitive reversing, the reversing valve is widely used in various hydraulic equipment.

[0003] However, in some special fields such as deep space, deep earth, and deep sea, the working environment can vary from room temperature to 200°C and from normal pressure to 140MPa. In addition to requiring hydraulic equipment to work normally in a wide temperature and pressure environment, it is also required to have characteristics such as large flow rate, fast response speed, and stable operation. At present, there are very few products on the market that can be used for wide temperature and pressure environment requirements, and their diameters are all below 2mm, with a very narrow application range, and cannot meet the requirements of large flow and fast work. Since the viscosity of the liquid medium is greatly affected by changes in ambient temperature, the liquid resistance of the liquid medium through the small diameter oil circuit also changes greatly, resulting in a large return oil resistance through the small diameter pilot control valve, which restricts the reset speed of the main reversing valve, thereby restricting the movement speed of the actuator.

[0004] Therefore, it is urgent to develop a reversing circuit that can improve the resetting speed of the reversing valve to solve the problem that the resetting speed of the main reversing valve and the movement speed of the actuator are restricted by the small diameter of the pilot control valve and the limited application range. Summary of the invention

[0005] In order to solve the problem that in a pilot-controlled reversing circuit, the viscosity of the liquid medium changes when the ambient temperature changes, resulting in the reset speed of the main reversing valve and the movement speed of the actuator being restricted by the small diameter of the pilot control valve and limiting the application scope, the present invention provides a fast-reset pilot-controlled reversing circuit, the purpose of which is to add a fast reset unit so that the reset speed of the main reversing valve is not affected by the small diameter of the pilot control valve, thereby achieving fast resetting of the main reversing valve, improving the working efficiency and reliability of the reversing circuit, and broadening the application scope of the hydraulic reversing circuit.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A fast-reset pilot control reversing circuit is provided, comprising an oil pump unit, a pilot control valve and a main reversing valve connected in sequence through an oil circuit, wherein the oil pump unit is used to provide pressure oil to the pilot control valve; the invention is characterized in that it also comprises a fast-reset unit connected between the pilot control valve and the main reversing valve; the fast-reset unit comprises a cylinder body and a piston with a through hole in the center, the first end face of the cylinder body is provided with an oil inlet P connected to the pilot control valve, the second end face is provided with a main connection port A connected to the main reversing valve, the piston is slidably connected to the inner wall of the cylinder body between the first end face and the second end face of the cylinder body, the side wall of the cylinder body is provided with an oil return port T near the second end face, and the oil return port T is connected to the oil tank;

[0008] When the pilot control valve is opened, the pressure oil flows into the cylinder body through the oil inlet P and pushes the piston to move until it is close to the second end face, so that the pressure oil flows into the main reversing valve through the through hole and the main connecting port A to push the main reversing valve to change direction; when the pilot control valve is closed, the pressure oil in the main reversing valve flows back to the cylinder body and pushes the piston to separate from the second end face, so that the return oil port T is opened, and the pressure oil flows out through the return oil port T to realize the resetting of the main reversing valve.

[0009] Preferably, the rapid reset unit further comprises an elastic structure, wherein the elastic structure is provided between the first end surface and the piston, and the elastic structure is in a compressed state.

[0010] Preferably, a first groove is provided on the end face of the piston facing the main connecting port A, and a first sealing ring is provided at the first groove. The thickness of the first sealing ring is greater than the depth of the first groove, so that when the piston moves to press against the second end face, there is a gap between the end face of the piston facing the main connecting port A and the second end face.

[0011] Preferably, when the pilot control valve is closed, the thrust exerted on the piston by the pressure oil in the main reversing valve is greater than the preload force of the elastic structure, so that the piston can be pushed to separate from the second end surface.

[0012] Preferably, the axial projection area of ​​the piston is S, and the oil pressure of the pressure oil is p c , the oil pressure of the oil tank is p t , the piston has friction resistance F during the sliding process t , the oil in the cylinder body has an axial fluid force F during the flow process h When the piston is pressed against the second end surface, the pre-compression force F of the elastic structure satisfies the following relationship:

[0013] F <S×(p c -pt )-F f -F h .

[0014] Preferably, a second groove is provided on the side wall of the piston, a second sealing ring is provided at the second groove, and the piston is connected to the cylinder body in a sliding and sealing manner via the second sealing ring.

[0015] Preferably, the pilot control valve includes a pilot oil inlet, a pilot oil outlet and a pilot oil return port, the pilot oil outlet is selectively connected to the pilot oil inlet and the pilot oil return port, the oil pump unit is connected to the pilot oil inlet, the pilot oil outlet is connected to the oil inlet P, and the pilot oil return port is connected to the oil tank.

[0016] Preferably, the aperture of the through hole is equal to the diameter of the pilot oil outlet, the diameter of the oil circuit is also equal to the diameter of the pilot oil outlet, and the diameter of the oil return port T is larger than the diameter of the pilot oil outlet.

[0017] Preferably, the main reversing valve includes a valve core and a valve sleeve, a cavity is provided inside the valve sleeve, the valve core can be slidably arranged in the cavity, and the valve core divides the cavity into two parts: a control cavity and a movable cavity, the main connecting port A is connected to the control cavity through the oil circuit; the movable cavity includes a reversing oil return port, and the reversing oil return port is connected to the oil tank.

[0018] Preferably, the linear expansion coefficients of the materials used for the valve core and the valve sleeve are consistent.

[0019] In general, the present invention has the following technical effects compared with the prior art through the above technical solutions conceived:

[0020] 1. Provide a fast-reset pilot control reversing circuit, by arranging a fast-reset unit between the pilot control valve and the main reversing valve, so that during the resetting process of the main reversing valve, when the pressure oil flows back to the cylinder body, the piston can be pushed to separate from the second end surface, and the oil return port T is opened, so that the pressure oil directly flows out through the oil return port T, so that the resetting speed of the main reversing valve is not affected by the small diameter of the pilot control valve, and the main reversing valve can be quickly reset in a wide temperature environment, thereby improving the working efficiency and reliability of the reversing circuit and broadening the application range of the hydraulic reversing circuit;

[0021] 2. The present invention provides an elastic structure between the first end face and the piston, and the elastic structure is in a compressed state, so that the piston can be in a position close to the second end face in the initial state, which is conducive to the rapid response at the beginning of the reversing process and improves the working stability; the pre-compression force F of the elastic structure is set according to the force relationship of the piston during the resetting process, so that the piston and the second end face are separated smoothly during the resetting process, which is conducive to the normal operation of the rapid resetting unit;

[0022] 3. In the present invention, the diameter of the through hole is set to be equal to the diameter of the pilot oil outlet, so that during the switching process of the pilot control valve being opened, the pressure oil flows through the through hole without generating additional resistance, and maintains effective pressure to enter the main reversing valve. At the same time, during the resetting process of the pilot control valve being closed, when the pressure oil flows through the quick resetting unit, the through hole plays a role of liquid resistance, and the pressure oil in the main reversing valve can generate sufficient back pressure to push the piston to overcome resistance such as friction and spring force and separate from the second end face, so that as much pressure oil as possible flows out through the return oil port T with a larger diameter, which is conducive to the quick resetting of the main reversing valve;

[0023] 4. In the present invention, the pilot control valve is provided with a pilot oil return port, and the main reversing valve is provided with a reversing oil return port. The oil return port T, the pilot oil return port and the reversing oil return port are respectively connected to the oil tank, so that the interior of each component in the reversing circuit is connected with the external environment. During the working process, the hydraulic pressure exerted on each component in the reversing circuit is the effective pressure exerted to overcome the load, and the pressure of the environment in which it is subjected is automatically balanced, so that the reversing circuit can operate stably under a wide pressure environment, and its adaptability to a wide pressure environment is improved;

[0024] 5. In the present invention, the materials of the valve sleeve and the valve core preferably use materials with consistent linear expansion coefficients, so that when the main reversing valve is used in different temperature conditions, the thermal deformation caused by temperature changes on the valve sleeve and the valve core is consistent, which is conducive to the stable cooperation between the valve sleeve and the valve core under different temperature environments, and realizes the stable operation of the reversing circuit in a wide temperature environment, thereby improving its adaptability to ambient temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of a fast-reset pilot control reversing circuit of the present invention;

[0026] Figure 2 This is a working principle diagram of a fast-reset pilot control reversing circuit of the present invention;

[0027] Figure 3 A schematic diagram of the reset process of a fast-reset pilot control reversing circuit of the present invention;

[0028] Figure 4 It is a schematic diagram of two working states of a fast-reset pilot control reversing circuit of the present invention;

[0029] In all the drawings, the same reference numerals are used to represent the same elements or structures. Since the main reversing valve in the reversing circuit mainly relies on the action of the valve core to achieve reversing, in order to simplify the description, the single-acting hydraulic cylinder is used in the drawings to replace the action of the valve core and the main reversing valve to explain the reversing working principle; this reversing circuit can be used in the control system of various actuators. In order to simplify the description, the double-acting hydraulic cylinder is used in the drawings to replace the actuator to explain the control process of the reversing circuit, where:

[0030] 1-oil pump unit, 2-pilot control valve, 3-quick reset unit, 4-main reversing valve, 5-oil tank, 6-pilot oil outlet, 7-first oil circuit, 8-oil inlet P, 9-cylinder body, 10-elastic structure, 11-second sealing ring, 12-piston, 13-first sealing ring, 14-gap, 15-main connecting port A, 16-oil return port T, 17-third oil circuit, 18-second oil circuit. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0032] The technical solution of the present invention is described in detail below with specific embodiments.

[0033] See also Figure 1 This embodiment provides a fast-reset pilot control reversing circuit, comprising an oil pump unit 1, a pilot control valve 2 and a main reversing valve 4 connected in sequence through an oil circuit, and also comprising a fast-reset unit 3 connected between the pilot control valve 2 and the main reversing valve 4. The oil pump unit 1 is used to provide hydraulic oil of the pressure and flow required for operation to the reversing circuit, and the oil circuit comprises a first oil circuit 7, a second oil circuit 18 and a third oil circuit 17. The fast-reset unit 3 comprises a cylinder 9 and a piston 12 with a through hole in the center, the first end surface of the cylinder 9 is provided with an oil inlet P8 connected to the pilot control valve 2 through the first oil circuit 7, and the second end surface is provided with a main connection port A15 connected to the main reversing valve 4 through the second oil circuit 18, the piston 12 is slidably connected to the inner wall of the cylinder 9 between the first end surface and the second end surface of the cylinder 9, and the side wall of the cylinder 9 is provided with an oil return port T16 near the second end surface, and the oil return port T16 is connected to the oil tank 5 through the third oil circuit 17.

[0034] When the pilot control valve 2 is opened, refer to Figure 2, the pressure oil flows out from the pilot control valve 2, flows into the cylinder 9 through the oil inlet P8 and pushes the piston 12 to move to the second end face, so that the pressure oil flows out through the through hole and the main connecting port A15, flows into the main reversing valve 4 through the second oil path 18, and pushes the main reversing valve 4 to change direction; when the pilot control valve 2 is closed, refer to Figure 3 , the main reversing valve 4 is reset under the action of the reset structure, and the pressure oil in the main reversing valve 4 flows back to the cylinder body 9 and generates a large back pressure, pushing the piston 12 to separate from the second end face, so that the return oil port T16 is opened, and the pressure oil preferentially flows directly back to the oil tank 5 through the return oil port T16 with a larger aperture and the third oil circuit 17, so that the main reversing valve 4 is not restricted by the small diameter of the pilot control valve 2 during the reset process, and the main reversing valve 4 can be quickly reset in a wide temperature environment, and the working performance is not affected by the change of fluid resistance caused by the change of oil viscosity, thereby improving the environmental temperature adaptability and reliability of the reversing circuit. Through the cycle of the above-mentioned opening and closing steps of the pilot control valve 2, the rapid change of the reversing and resetting of the main reversing valve 4 is achieved.

[0035] In practical applications, the commutation circuit provided in this embodiment is connected to the actuators in different application requirements. Figure 4 It can realize the rapid reset of the main reversing valve, adapt to the application requirements of various flow and diameter actuators, improve the working efficiency and reliability of the reversing circuit, and broaden the application range of the hydraulic reversing circuit in a wide temperature and pressure environment.

[0036] Specifically, the quick reset unit 3 further includes an elastic structure 10, one end of which is arranged on the inner wall of the first end surface, and the other end is arranged on the end surface of the piston 12 facing the oil inlet P 8. The elastic structure 10 is in a compressed state, which can ensure that the piston 12 is in a position close to the second end surface in the initial state, which is conducive to the rapid response at the beginning stage of the reversing stroke and improves the working stability.

[0037] Specifically, the end face of the piston 12 facing the main connection port A15 is provided with a first groove, and a first sealing ring 13 is provided at the first groove. The thickness of the first sealing ring 13 is greater than the depth of the first groove, so that when the piston 12 moves to abut against the second end face, there is a gap 14 between the end face of the piston 12 facing the main connection port A15 and the second end face, so that the oil pressure of the pressure oil during the resetting process acts on the end face of the piston 12 facing the main connection port A15, pushing the piston 12 to separate from the second end face. At the same time, the gap 14 is conducive to buffering the oil pressure shock and improving work safety. The first sealing ring 13 is used to prevent radial leakage of the pressure oil when the piston 12 abuts against the second end face. The material can be an axial O-ring made of high-temperature resistant rubber material, or other high-temperature resistant sealing materials, which are not limited here; the groove design between the first sealing ring 13 and the first groove can adopt a dovetail groove to keep the sealing ring fixed, or other special shapes of groove designs can be adopted, which are not limited here.

[0038] Specifically, when the pilot control valve 2 is closed, the thrust generated by the pressure oil in the main reversing valve 4 on the piston 12 is greater than the pre-compression force of the elastic structure 10, so that the piston 12 can be pushed to separate from the second end surface.

[0039] Specifically, the axial projection area of ​​the piston 12 is S, and the oil pressure of the pressure oil is p c , the oil pressure of the oil tank 5 is p t The piston 12 has a friction resistance F during the sliding process. t The oil in the cylinder 9 has an axial fluid force F during the flow process. h When the piston 12 is pressed against the second end surface, the pre-compression force F of the elastic structure 10 satisfies the following relationship:

[0040] F <S×(p c -p t )-F f -F h ,

[0041] The piston 12 and the second end surface are separated smoothly during the resetting process, which is beneficial to the normal operation of the quick resetting unit 3.

[0042] Specifically, the side wall of the piston 12 is provided with a second groove, and the second groove is provided with a second sealing ring 11. The piston 12 is connected to the cylinder body 9 in a sliding and sealing manner through the second sealing ring 11. The second sealing ring 11 is conducive to preventing oil leakage between the cylinder body 9 and the side wall of the piston 12, and at the same time avoiding axial movement of the piston 12. The second sealing ring 11 can be a shaft-use combined sealing ring made of high-temperature resistant fluororubber material, or other high-temperature resistant sealing materials, which are not limited here.

[0043] Specifically, the pilot control valve 2 includes a pilot oil inlet, a pilot oil outlet 6 and a pilot oil return port, the pilot oil outlet 6 is selectively connected to the pilot oil inlet and the pilot oil return port, the oil pump unit 1 is connected to the pilot oil inlet, the pilot oil outlet 6 is connected to the oil inlet P8 through the first oil path 7, and the pilot oil return port is connected to the oil tank 5. When the pilot control valve 2 is opened, the pilot oil inlet is connected to the pilot oil outlet 6, thereby transmitting pressure oil; when the pilot control valve 2 is closed, the pilot oil outlet 6 is connected to the pilot oil return port, so that the inside of the pilot control valve 2 is filled with hydraulic oil, thereby automatically balancing with the ambient pressure and improving its adaptability to the ambient pressure.

[0044] Specifically, the aperture of the through hole is equal to the diameter of the pilot oil outlet 6, and the diameter of the first oil passage 7 is also equal to the diameter of the pilot oil outlet 6, so that during the switching process of the pilot control valve 2 being opened, the pressure oil flows through the through hole and the oil passage without generating additional liquid resistance, which is conducive to the pressure oil maintaining effective pressure to enter the main reversing valve 4; the diameter of the return oil port T16 is larger than the diameter of the pilot oil outlet 6, which is conducive to reducing the resistance of the pressure oil flowing out of the return oil port T16. At the same time, during the resetting process of the pilot control valve 2, when the pressure oil flows through the quick reset unit, the through hole plays a role of liquid resistance, and the pressure oil in the main reversing valve can generate sufficient back pressure, so that the piston 12 can overcome the resistance such as spring force and friction force to move and separate from the second end face, so that as much pressure oil as possible flows out through the return oil port T16 with a larger diameter, which is conducive to the quick resetting of the main reversing valve 4. The through hole can be designed as a straight through hole, a spiral hole or a through hole of other shapes that penetrates the piston according to actual working needs, which is not limited here.

[0045] In some embodiments, the main reversing valve 4 includes a valve core and a valve sleeve, a cavity is provided inside the valve sleeve, the valve core can be slidably arranged in the cavity, and the valve core divides the cavity into a control cavity and a movable cavity. The main connecting port A15 is connected to the control cavity through the second oil circuit 18; the movable cavity includes a reversing oil return port, and the reversing oil return port is connected to the oil tank 5, so that the main reversing valve 4 is filled with hydraulic oil. During the working process, the liquid pressure applied to the main reversing valve 4 is the effective pressure applied to overcome the load, and the pressure of the environment in which it is located is automatically balanced, so that the reversing circuit can operate stably under a wide pressure environment and improve the adaptability to environmental pressure.

[0046] As a further preferred embodiment, the linear expansion coefficients of the materials used for the valve core and the valve sleeve are consistent, such as 17-4PH stainless steel and Monel K500 alloy, so that when the main reversing valve 4 is used in different temperature conditions between room temperature and 200°C, the thermal deformation caused by temperature changes on the valve sleeve and the valve core is consistent, which is conducive to the stable cooperation between the valve sleeve and the valve core under different temperature environments, so that the reversing circuit can operate stably in a wide temperature environment, and improve its adaptability to a wide temperature environment. The selection of specific materials needs to preset the allowed difference threshold according to the actual application scenario, so as to select materials to ensure the performance of normal operation within the actual temperature change range, which is not limited here.

[0047] The fast reset unit 3 provided in this embodiment enables the main reversing valve 4 to be free from the restriction of the small diameter of the pilot control valve 2 during the resetting process, the linear expansion coefficients of the materials used for the valve core and the valve sleeve are consistent, and the pilot oil return port, the reversing oil return port and the oil return port T are respectively connected to the oil tank so that the environmental pressure inside and outside the reversing circuit is automatically balanced, which is suitable for deep-earth fields where the ambient temperature and ambient pressure vary in a wide range, such as in the fields of drilling and logging. In the process of going deep into the well, the environment of the fast-reset pilot control reversing circuit rises from the normal temperature and pressure on the surface to the high temperature and high pressure underground. The ambient temperature in this field varies from room temperature to 200°C, and the ambient pressure varies from 0 to 140MPa, or even higher.

[0048] The fast reset unit 3 provided in this embodiment enables the main reversing valve 4 to be free from the restriction of the small diameter of the pilot control valve 2 during the resetting process. The valve core of the main reversing valve 4 and the valve sleeve are made of high-temperature resistant materials with equal or similar linear expansion coefficients. They are also suitable for deep space fields where the ambient temperature varies in a wide range and the ambient pressure is relatively stable. For example, in a space station, the fast reset pilot control reversing circuit may be inside or outside the space station, the station is in a normal pressure environment, and the station is in a high vacuum environment. When going deep into the space environment of about 400 km from the ground, under the direct irradiation of sunlight, the surface temperature of the space station can reach about 150°C or even higher, so the ambient temperature change range of the fast reset pilot control reversing circuit can reach more than 150°C.

[0049] The pilot oil return port, the reversing oil return port and the oil return port T described in this embodiment are respectively connected to the oil tank, so that the environmental pressure inside and outside the reversing circuit is automatically balanced. It is also suitable for deep-sea fields where the environmental pressure varies in a wide range and the environmental temperature is relatively stable, such as seabed exploration. During the operation of the fast-reset pilot control reversing circuit on the seabed, the working pressure gradually changes from the normal pressure environment at sea level to a high-pressure environment of about 120MPa, and the diving depth is about 11,000m under the sea. As the depth of the sea water changes, the environmental pressure changes in the range of 0 to 120MPa, and the environmental temperature is between room temperature and about 6°C.

[0050] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A fast-reset pilot control reversing circuit, comprising an oil pump unit (1), a pilot control valve (2) and a main reversing valve (4) connected in sequence through an oil circuit, wherein the oil pump unit (1) is used to provide pressure oil to the pilot control valve (2); characterized in that: It also includes a quick reset unit (3) connected between the pilot control valve (2) and the main reversing valve (4); the quick reset unit (3) includes a cylinder body (9) and a piston (12) with a through hole in the center, the first end surface of the cylinder body (9) is provided with an oil inlet port P (8) connected to the pilot control valve (2), and the second end surface is provided with a main connection port A (15) connected to the main reversing valve (4), the piston (12) is slidably connected to the inner wall of the cylinder body (9) between the first end surface and the second end surface of the cylinder body (9), and the side wall of the cylinder body (9) is provided with an oil return port T (16) near the second end surface, and the oil return port T (16) is connected to the oil tank (5); When the pilot control valve (2) is opened, the pressure oil flows into the cylinder body (9) through the oil inlet port P (8) and pushes the piston (12) to move until it is close to the second end surface, so that the pressure oil flows into the main reversing valve (4) through the through hole and the main connecting port A (15) to push the main reversing valve (4) to change direction; when the pilot control valve (2) is closed, the pressure oil in the main reversing valve (4) flows back to the cylinder body (9) and pushes the piston (12) to separate from the second end surface, so that the return oil port T (16) is opened, and the pressure oil flows out through the return oil port T (16) to realize the resetting of the main reversing valve (4).

2. The fast-reset pilot control reversing circuit according to claim 1, characterized in that: The rapid reset unit (3) further comprises an elastic structure (10), wherein the elastic structure (10) is arranged between the first end surface and the piston (12), and the elastic structure (10) is in a compressed state.

3. The fast-reset pilot control reversing circuit according to claim 1, characterized in that: The end surface of the piston (12) facing the main connecting port A (15) is provided with a first groove, and a first sealing ring (13) is provided at the first groove. The thickness of the first sealing ring (13) is greater than the depth of the first groove, so that when the piston (12) moves to abut against the second end surface, a gap (14) is provided between the end surface of the piston (12) facing the main connecting port A (15) and the second end surface.

4. The fast-reset pilot control reversing circuit according to claim 2, characterized in that: When the pilot control valve (2) is closed, the thrust generated by the pressure oil in the main reversing valve (4) on the piston (12) is greater than the preload force of the elastic structure (10), so that the piston (12) can be pushed to separate from the second end surface.

5. The fast-reset pilot control reversing circuit according to claim 4, characterized in that: The axial projection area of ​​the piston (12) is S, and the oil pressure of the pressure oil is p c , the oil pressure of the oil tank (5) is p t The piston (12) has a friction resistance F during the sliding process. t The oil in the cylinder (9) has an axial fluid force F during its flow. h When the piston (12) is pressed against the second end surface, the pre-compression force F of the elastic structure (10) satisfies the following relationship: F<S×(p c -p t )-F f -F h 。 6. The fast-reset pilot control reversing circuit according to any one of claims 1 to 5, characterized in that: A second groove is provided on the side wall of the piston (12), a second sealing ring (11) is provided at the second groove, and the piston (12) and the cylinder body (9) are connected in a sliding and sealing manner via the second sealing ring (11).

7. The fast-reset pilot control reversing circuit according to any one of claims 1 to 5, characterized in that: The pilot control valve (2) comprises a pilot oil inlet, a pilot oil outlet (6) and a pilot oil return port, the pilot oil outlet (6) selectively communicates with the pilot oil inlet and the pilot oil return port, the oil pump unit (1) communicates with the pilot oil inlet, the pilot oil outlet (6) communicates with the oil inlet P (8), and the pilot oil return port is connected to the oil tank (5).

8. The fast-reset pilot control reversing circuit according to claim 7, characterized in that: The aperture of the through hole is equal to the diameter of the pilot oil outlet (6), the diameter of the oil circuit is also equal to the diameter of the pilot oil outlet (6), and the diameter of the oil return port T (16) is greater than the diameter of the pilot oil outlet (6).

9. The fast-reset pilot control reversing circuit according to any one of claims 1 to 5, characterized in that: The main reversing valve (4) comprises a valve core and a valve sleeve, wherein a cavity is provided inside the valve sleeve, wherein the valve core is slidably arranged in the cavity, and wherein the valve core divides the cavity into two parts, namely a control cavity and a movable cavity, wherein the main connecting port A (15) is connected to the control cavity via the oil circuit (18); and the movable cavity comprises a reversing oil return port, wherein the reversing oil return port is connected to the oil tank (5).

10. The fast-reset pilot control reversing circuit according to claim 9, characterized in that: The linear expansion coefficients of the materials used for the valve core and the valve sleeve are consistent.

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