Multi-way valve oil inlet module with automatic low-pressure unloading function

Abstract

The invention discloses a multi-way valve oil inlet module with an automatic low-pressure unloading function, and relates to the technical field of hydraulic elements and systems.The multi-way valve oil inlet module comprises a valve block, a pressure compensation valve is arranged in the valve block, and a pre-pressing spring is arranged at the upper end of the pressure compensation valve and used for providing downward preset pressure difference for the pressure compensation valve; the LS port of the proportional control valve feeds back the load pressure to the PL port of the valve block; and the auxiliary piston mechanism is communicated with a PL port of the valve block. When the hydraulic cylinder does not act, the load pressure fed back by the proportional control valve to the pressure compensation valve is zero, at the moment, the auxiliary piston mechanism can achieve the function of automatically jacking the pressure compensation valve upwards, the force application direction of the auxiliary piston mechanism is the same as the working pressure application direction of the hydraulic pump, and part of preset pressure difference can be counteracted; at the moment, the working pressure of the hydraulic pump is equal to the value obtained by subtracting the jacking pressure of the auxiliary piston mechanism from the preset pressure difference, namely, the effect of reducing the constant pressure difference, namely the unloading pressure of the hydraulic pump when the hydraulic cylinder does not act is achieved, and meanwhile the through-flow capacity of the system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic components and systems, and particularly to a multi-way valve inlet module with an automatic low-pressure unloading function. Background Art

[0002] In a hydraulic system, a fixed-displacement pump always provides a fixed flow rate. To reduce the energy loss of the fixed-displacement pump when the actuator is not operating, a fixed-displacement pump system is combined with a load-sensing system. The load-sensing system uses a pressure-compensating valve, such that the operating pressure of the fixed-displacement pump is only higher than the load pressure by a preset constant pressure difference value. When all the actuators in the system are not operating, the operating pressure of the pump is the preset pressure difference value of the pressure-compensating valve. Thus, it can be known that the wasted energy in this state is the product of the pump flow rate and this constant pressure difference. If the constant pressure difference can be reduced when the system is not operating, the system energy waste can be reduced, the cost can be lowered, and the service life of the equipment can be extended.

[0003] However, directly reducing the constant pressure difference will reduce the flow capacity of the valve in the circuit and reduce the movement speed of the actuator, which cannot meet the production requirements. And if a valve with a larger flow capacity is selected while reducing the constant pressure difference, the equipment cost will increase, and the purpose of cost reduction cannot be achieved.

[0004] In view of this, how to provide a device that can reduce the constant pressure difference when the system is not operating and at the same time ensure the flow capacity of the valve is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-way valve inlet module with an automatic low-pressure unloading function to solve the problems existing in the prior art.

[0006] To achieve the above purpose, the present invention provides a multi-way valve inlet module with an automatic low-pressure unloading function, including:

[0007] A valve block;

[0008] A pressure-compensating valve, disposed within the valve block, the P port of the pressure-compensating valve is connected to a hydraulic pump through a first oil passage, and the T port is connected to a fuel tank through a second oil passage;

[0009] A preloading spring, disposed at the upper end of the pressure-compensating valve for providing a downward preset pressure difference Δp1 to the pressure-compensating valve;

[0010] A proportional control valve, its P port is connected to the hydraulic pump through a third oil passage, and the T port is connected to the fuel tank through a fourth oil passage; its A port is connected to the rodless cavity of a hydraulic cylinder, and the B port is connected to the rod cavity of the hydraulic cylinder; the LS port of the proportional control valve is connected to the PL port of the valve block, and the LS port of the proportional control valve can output the load pressure p LThe first control port of the pressure compensation valve is connected to the PL port of the valve block through the fifth oil circuit to transmit the load pressure p L The second control port of the pressure compensation valve is connected to the hydraulic pump through the sixth oil circuit for transmitting the oil pressure p p ; The first control port and the second control port are respectively located at the upper and lower ends of the pressure compensation valve;

[0011] The auxiliary piston mechanism is connected to the PL port of the valve block. When the hydraulic cylinder moves, the LS port of the proportional control valve feeds back the load pressure p to the PL port of the valve block. L , the auxiliary piston mechanism is in the first working position and away from the pressure compensation valve, at this time p p =p L +Δp1; when the hydraulic cylinder does not move, the LS port of the proportional control valve feeds back zero load pressure to the PL port, the auxiliary piston mechanism is in the second working position and lifts the pressure compensation valve upward, and the equivalent pressure of the lifting is Δp2. At this time, p p =Δp1-Δp2.

[0012] Furthermore, it also includes a relief valve, the P port of the hydraulic pump is connected to the P port of the relief valve, the S port of the hydraulic pump is connected to the oil tank, and the T port of the relief valve is connected to the oil tank.

[0013] Furthermore, a first installation cavity is defined in the valve block, the pressure compensating valve has a pressure compensating valve core, the pressure compensating valve core is arranged in the first installation cavity, and the first installation cavity forms a first control port and a second control port at the upper and lower ends of the pressure compensating valve core, respectively; the pre-stress spring is arranged in the first control port, one end of the pre-stress spring is connected to the pressure compensating valve core, and the other end is connected to the inner wall of the first installation cavity; one end of the fifth oil circuit is connected to the PL port of the valve block, and the other end is connected to the first control port.

[0014] Furthermore, the auxiliary piston mechanism includes a switching valve and a piston assembly, and the switching valve includes:

[0015] A switching valve core, wherein a second installation cavity is defined in the valve block, the switching valve core is arranged in the second installation cavity, the second installation cavity forms a third control port at one end of the switching valve core, the third control port is communicated with the first control port through a seventh oil path; a first return spring is arranged at the other end of the switching valve core;

[0016] The A port of the switching valve is connected to the piston assembly through the eighth oil circuit, the P port of the switching valve is connected to the hydraulic pump, and the T port of the switching valve is connected to the oil tank; when the hydraulic cylinder moves, the LS port of the proportional control valve feeds back the load pressure p to the PL port L, the load pressure p L The load pressure p is transmitted to the third control port through the seventh oil passage. L The switching valve core is driven to overcome the elastic force of the first return spring and move to the first working valve position, so that the A port of the switching valve is connected to the T port, and the piston assembly is away from the pressure compensation valve core; when the hydraulic cylinder does not move, the LS port of the proportional control valve feeds back zero load pressure to the PL port, and the first return spring moves the switching valve core to the second working valve position, so that the A port of the switching valve is connected to the P port, and the oil pressure p p The oil is transmitted to the piston assembly through the eighth oil passage and drives the piston assembly to lift the valve core of the pressure compensation valve upward.

[0017] Furthermore, the piston assembly comprises:

[0018] A piston, wherein the valve block defines a third installation cavity, and the piston is disposed in the third installation cavity;

[0019] A piston rod, one end of which is connected to the piston, and the other end of which extends into the second control port and is connected to the valve core of the pressure compensation valve; the third installation cavity defines a piston rod cavity and a non-piston rod cavity at the upper and lower ends of the piston, the non-piston rod cavity is connected to the eighth oil circuit, and the piston rod cavity is respectively connected to the T port of the switching valve and the oil tank;

[0020] A second return spring is sleeved on the piston rod, one end of the second return spring is connected to the piston, and the other end is connected to the inner wall of the third installation cavity.

[0021] Furthermore, it also includes:

[0022] Leakage oil circuit, the T port of the switching valve is connected to the oil tank through the ninth oil circuit, one end of the leakage oil circuit is connected to the second mounting cavity, the connection point is close to the first return spring, and the other end is connected to the ninth oil circuit.

[0023] The present invention discloses the following technical effects:

[0024] This application is provided with a proportional control valve and an auxiliary piston mechanism. When the hydraulic cylinder is working normally, the proportional control valve feeds back the load pressure to the pressure compensation valve. At this time, the working pressure of the hydraulic pump is equal to the sum of the load pressure and the preset pressure difference, which is no different from the prior art. When the hydraulic cylinder has no movement, the load pressure fed back by the proportional control valve to the pressure compensation valve is zero. At this time, the auxiliary piston mechanism can realize the function of automatically jacking up the pressure compensation valve upward. The force application direction of the auxiliary piston mechanism is the same as that of the working pressure of the hydraulic pump, and it can offset part of the preset pressure difference. At this time, the working pressure of the hydraulic pump is equal to the preset pressure difference minus the jacking pressure of the auxiliary piston mechanism. That is to say, this application achieves the effect of reducing the constant pressure difference when the hydraulic cylinder has no movement, and at the same time ensures the valve flow capacity. The operation of the auxiliary piston mechanism depends on the feedback load pressure of the proportional control valve, and it can automatically act according to the situation of the feedback load pressure, reduce the unloading pressure of the hydraulic pump, has good energy-saving effects, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is a schematic structural diagram of the present invention;

[0027] Figure 2 It is a schematic structural diagram of the valve block;

[0028] Among them, 1. Valve block; 2. Pressure compensation valve; 201. First control port; 202. Second control port; 203. Pressure compensation valve spool; 3. First oil passage; 4. Hydraulic pump; 5. Second oil passage; 6. Preloading spring; 7. Proportional control valve; 8. Third oil passage; 9. Fourth oil passage; 10. Hydraulic cylinder; 11. Fifth oil passage; 12. Sixth oil passage; 13. Relief valve; 14. Switching valve; 1401. Switching valve spool; 1402. Third control port; 1403. First return spring; 15. Seventh oil passage; 16. Eighth oil passage; 17. Piston assembly; 1701. Piston; 1702. Piston rod; 1703. Second return spring; 18. Leakage oil passage; 19. Ninth oil passage. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The embodiment of the present invention provides a multi-way valve oil inlet module with automatic low-pressure unloading function, comprising:

[0032] Valve block 1;

[0033] The pressure compensating valve 2 is arranged in the valve block 1, the P port of the pressure compensating valve 2 is connected to the hydraulic pump 4 through the first oil circuit 3, and the T port is connected to the oil tank through the second oil circuit 5;

[0034] A pre-compression spring 6 is arranged at the upper end of the pressure compensating valve 2 and is used to provide a preset downward pressure difference Δp1 to the pressure compensating valve 2;

[0035] The proportional control valve 7 has its P port connected to the hydraulic pump 4 through the third oil circuit 8, and its T port connected to the oil tank through the fourth oil circuit 9; its A port is connected to the rodless chamber of the hydraulic cylinder 10, and its B port is connected to the rod chamber of the hydraulic cylinder 10; the LS port of the proportional control valve 7 is connected to the PL port of the valve block 1, and the LS port of the proportional control valve 7 can adjust the load pressure p L Feedback to the PL port of the valve block 1; the first control port 201 of the pressure compensation valve 2 is connected to the PL port of the valve block 1 through the fifth oil circuit 11 for transmitting the load pressure p L The second control port 202 of the pressure compensation valve 2 is connected to the hydraulic pump 4 through the sixth oil circuit 12 for transmitting the oil pressure p p , the first control port 201 and the second control port 202 are respectively located at the upper and lower ends of the pressure compensation valve 2;

[0036] The auxiliary piston mechanism is connected to the PL port of the valve block 1. When the hydraulic cylinder 10 is working, the LS port of the proportional control valve 7 feeds back the load pressure p to the PL port of the valve block 1. L , the auxiliary piston mechanism is in the first working position and away from the pressure compensation valve 2. At this time, p p =p L +Δp1; when the hydraulic cylinder 10 is not in motion, the LS port of the proportional control valve 7 feeds back zero load pressure to the PL port, the auxiliary piston mechanism is in the second working position and lifts the pressure compensation valve 2 upward, the lifting force is Δp2, at this time p p =Δp1-Δp2.

[0037] In this embodiment, a relief valve 13 is further included, the P port of the hydraulic pump 4 is connected to the P port of the relief valve 13, the S port of the hydraulic pump 4 is connected to the oil tank, and the T port of the relief valve 13 is connected to the oil tank.

[0038] Furthermore, a first installation cavity is defined in the valve block 1, and the pressure compensating valve 2 has a pressure compensating valve core 203, which is arranged in the first installation cavity. The first installation cavity forms a first control port 201 and a second control port 202 at the upper and lower ends of the pressure compensating valve core 203, respectively; a preload spring 6 is arranged in the first control port 201, one end of the preload spring 6 is connected to the pressure compensating valve core 203, and the other end is connected to the inner wall of the first installation cavity; one end of the fifth oil circuit 11 is connected to the PL port of the valve block 1, and the other end is connected to the first control port 201.

[0039] In this embodiment, the switching valve 14 includes:

[0040] The switching valve core 1401 defines a second installation cavity in the valve block 1, and the switching valve core 1401 is disposed in the second installation cavity. The second installation cavity forms a third control port 1402 at one end of the switching valve core 1401, and the third control port 1402 is connected to the first control port 201 through the seventh oil path 15; the other end of the switching valve core 1401 is provided with a first return spring 1403;

[0041] The A port of the switching valve 14 is connected to the piston assembly 17 through the eighth oil circuit 16, the P port of the switching valve 14 is connected to the hydraulic pump 4, and the T port of the switching valve 14 is connected to the oil tank; when the hydraulic cylinder 10 is working, the LS port of the proportional control valve 7 feeds back the load pressure p to the PL port L , load pressure p L The load pressure p is transmitted to the third control port 1402 through the seventh oil passage 15. L The switching valve core 1401 is driven to overcome the elastic force of the first return spring 1403 and move to the first working valve position, so that the A port of the switching valve 14 is connected to the T port. At this time, the piston assembly 17 is away from the pressure compensation valve core 203. When the hydraulic cylinder 10 is not in motion, the LS port of the proportional control valve 7 feeds back zero load pressure to the PL port, and the first return spring 1403 moves the switching valve core 1401 to the second working valve position, so that the A port of the switching valve 14 is connected to the P port, and the oil pressure p p The oil is transmitted to the piston assembly 17 through the eighth oil passage 16 and drives the piston assembly 17 to lift the pressure compensation valve core 203 upward.

[0042] In this embodiment, the piston assembly 17 includes:

[0043] The piston 1701 and the valve block 1 define a third installation cavity, and the piston 1701 is disposed in the third installation cavity;

[0044] The piston rod 1702, one end of the piston rod 1702 is connected to the piston 1701, and the other end extends into the second control port 202 and is connected to the pressure compensation valve spool 203; the third installation cavity defines a piston rod cavity and a non-piston rod cavity at the upper and lower ends of the piston 1701. The non-piston rod cavity is connected to the eighth oil passage 16, and the piston rod cavity is respectively connected to the T port of the switching valve 14 and the oil tank;

[0045] The second return spring 1703, the second return spring 1703 is sleeved on the piston rod 1702, one end thereof is connected to the piston 1701, and the other end is connected to the inner side wall of the third installation cavity.

[0046] In this embodiment, it further includes:

[0047] The leakage oil passage 18, the T port of the switching valve 14 is connected to the L port through the ninth oil passage 19, the L port is connected to the oil tank, one end of the leakage oil passage 18 is connected to the second installation cavity, the connection position is close to the first return spring 1403, and the other end is connected to the ninth oil passage 19.

[0048] The specific working process is as follows:

[0049] 1. The hydraulic cylinder works

[0050] Taking the extension movement of the hydraulic cylinder 10 as an example (the retraction movement is similar to the extension movement principle), the proportional control valve works in the first working valve position. The hydraulic pump 4 sucks oil from the oil tank, the high-pressure oil is discharged from the P port of the hydraulic pump 4, and is conveyed to the P port of the proportional control valve 7 through the third oil passage 8, enters the rodless cavity of the hydraulic cylinder 10 from the A port of the proportional control valve 7, and pushes the hydraulic cylinder 10 of the hydraulic cylinder 10 to extend outwards. At the same time, the oil in the rod cavity flows through the B port of the proportional control valve 7 to the T port of the proportional control valve 7 and finally returns to the oil tank.

[0051] In the above process, the pressure in the rodless cavity of the hydraulic cylinder 10 is the load pressure p L , the load pressure p L flows through the feedback loop inside the proportional control valve 7 to the LS port and is transmitted to the PL port of the valve block 1.

[0052] For the upper end face of the pressure compensation valve 2, the load pressure p L is transmitted to the first control port 201 through the fifth oil passage 11 and acts on the pressure compensation valve 2. At the same time, the preloading spring 6 also acts on the pressure compensation valve 2, and the acting effect is the preset pressure difference Δp1. It can be seen that the force on the upper end face of the pressure compensation valve 2 is p L +Δp1.

[0053] For the lower end face of the pressure compensation valve 2, the high-pressure oil transmits the oil pressure p p .

[0054] For the auxiliary piston mechanism, the load pressure p L is transmitted through the first control port 201 and the seventh oil passage 15 to the third control port 1402 and acts on the switching valve spool 1401; under the action of the load pressure p L , the switching valve spool 1401 overcomes the elastic force of the first return spring 1403 and moves to the first working valve position. The A port and the T port of the switching valve 14 are communicated. The piston 1701 moves away from the pressure compensation valve 2 under the action of the second return spring 1703, and the piston rod 1702 is separated from the pressure compensation valve 2 without applying force to the pressure compensation valve 2. It can be seen that when the pressure compensation valve 2 is in force balance, p p = p L +Δp1. That is, in the prior art, the working pressure of the hydraulic pump 4 is equal to the sum of the load pressure and the preset pressure difference.

[0055] 2. The hydraulic cylinder does not move

[0056] When the hydraulic cylinder 10 does not move, the load pressure p L = 0.

[0057] For the auxiliary piston mechanism, the switching valve spool 1401 loses the driving force of the load pressure p L . Under the action of the first return spring 1403, the switching valve spool 1401 moves to the second working valve position. The A port and the P port of the switching valve 14 are communicated (the realization of this function depends on the cavity in the middle of the switching valve spool 1401). Part of the oil of the hydraulic pump 4 is shunted into the second installation cavity and output from the A port of the switching valve 14, and is transmitted through the eighth oil passage 16 to the rodless cavity of the third installation cavity. This pressure can push the piston 1701 and the piston rod 1702 to move towards the pressure compensation valve 2 (the oil in the rod cavity flows to the fuel tank. Actually, the operating mechanism of the piston assembly 17 is the same as that of the hydraulic cylinder 10). The piston rod 1702 applies a jacking force to the lower end surface of the pressure compensation valve 2, and the equivalent pressure of the jacking force is Δp2. Therefore, at this time p p =Δp1 - Δp2. Compared with the prior art, when the hydraulic cylinder 10 does not move, the working pressure of the hydraulic pump 4 is not the preset pressure difference Δp1, but is reduced by Δp2 on the basis of the preset pressure difference Δp1.

[0058] For the common preloading spring 6, its preset pressure difference is generally Δp1 = 0.8 MPa. Assuming that the equivalent jacking pressure Δp2 of the piston rod 1702 for the pressure compensation valve 2 is 0.4 MPa, at this time the oil pressure (working pressure) p p of the hydraulic pump 4 = 0.4 MPa, and its load is directly reduced by half, which can reduce half of the energy waste of the system.

[0059] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the present invention.

[0060] The embodiments described above are only for describing the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A multi-way valve oil inlet module with automatic low-pressure unloading function, characterized in that: include: Valve block (1); A pressure compensating valve (2) is arranged in the valve block (1), wherein the P port of the pressure compensating valve (2) is connected to the hydraulic pump (4) through the first oil circuit (3), and the T port of the pressure compensating valve (2) is connected to the oil tank through the second oil circuit (5); A pre-compression spring (6), arranged at the upper end of the pressure compensation valve (2) and used for providing a preset downward pressure difference Δp1 to the pressure compensation valve (2); A proportional control valve (7), wherein the LS port of the proportional control valve (7) is connected to the PL port of the valve block (1), and the LS port of the proportional control valve (7) converts the load pressure p L The first control port (201) of the pressure compensation valve (2) is connected to the PL port of the valve block (1) through the fifth oil path (11) to transmit the load pressure p L The second control port (202) of the pressure compensation valve (2) is connected to the hydraulic pump (4) through the sixth oil circuit (12) for transmitting the oil pressure p p , the first control port (201) and the second control port (202) are respectively located at the upper and lower ends of the pressure compensation valve (2); The auxiliary piston mechanism is connected to the PL port of the valve block (1). When the hydraulic cylinder (10) is working, the LS port of the proportional control valve (7) feeds back the load pressure p to the PL port of the valve block (1). L , the auxiliary piston mechanism is in the first working position and is away from the pressure compensation valve (2), at which time p p =p L +Δp1; when the hydraulic cylinder (10) is not in motion, the LS port of the proportional control valve (7) feeds back zero load pressure to the PL port, the auxiliary piston mechanism is in the second working position and lifts the pressure compensation valve (2) upward, the lifting force is Δp2, at this time p p =Δp1-Δp2.

2. A multi-way valve oil inlet module with automatic low-pressure unloading function according to claim 1, characterized in that: It also includes a relief valve (13), wherein the P port of the hydraulic pump (4) is connected to the P port of the relief valve (13), the S port of the hydraulic pump (4) is connected to the oil tank, and the T port of the relief valve (13) is connected to the oil tank.

3. A multi-way valve oil inlet module with automatic low-pressure unloading function according to claim 1, characterized in that: A first installation cavity is defined in the valve block (1); the pressure compensation valve (2) has a pressure compensation valve core (203); the pressure compensation valve core (203) is arranged in the first installation cavity; the first installation cavity forms a first control port (201) and a second control port (202) at the upper and lower ends of the pressure compensation valve core (203); the preload spring (6) is arranged in the first control port (201); one end of the preload spring (6) is connected to the pressure compensation valve core (203), and the other end is connected to the inner wall of the first installation cavity; one end of the fifth oil circuit (11) is connected to the PL port of the valve block (1), and the other end is connected to the first control port (201).

4. A multi-way valve oil inlet module with automatic low-pressure unloading function according to claim 3, characterized in that: The auxiliary piston mechanism comprises a switching valve (14) and a piston assembly (17), wherein the switching valve (14) comprises: A switching valve core (1401), wherein a second installation cavity is defined in the valve block (1), and the switching valve core (1401) is arranged in the second installation cavity, and the second installation cavity forms a third control port (1402) at one end of the switching valve core (1401), and the third control port (1402) is connected to the first control port (201) through a seventh oil path (15); and a first return spring (1403) is arranged at the other end of the switching valve core (1401); The A port of the switching valve (14) is connected to the piston assembly (17) via the eighth oil circuit (16), the P port of the switching valve (14) is connected to the hydraulic pump (4), and the T port of the switching valve (14) is connected to the oil tank; when the hydraulic cylinder (10) moves, the LS port of the proportional control valve (7) feeds back the load pressure p to the PL port L , the load pressure p L The load pressure p is transmitted to the third control port (1402) through the seventh oil passage (15). L The switching valve core (1401) is driven to overcome the elastic force of the first return spring (1403) and move to the first working valve position, so that the A port of the switching valve (14) is connected to the T port, and the piston assembly (17) is away from the pressure compensation valve core (203); when the hydraulic cylinder (10) is not in motion, the LS port of the proportional control valve (7) feeds back zero load pressure to the PL port, and the first return spring (1403) moves the switching valve core (1401) to the second working valve position, so that the A port of the switching valve (14) is connected to the P port, and the oil pressure p from the hydraulic pump (4) is p The oil is transmitted to the piston assembly (17) through the eighth oil passage (16) and drives the piston assembly (17) to lift the valve core (203) of the pressure compensation valve upward.

5. A multi-way valve oil inlet module with automatic low-pressure unloading function according to claim 4, characterized in that: The piston assembly (17) comprises: A piston (1701), wherein the valve block (1) defines a third installation cavity, and the piston (1701) is arranged in the third installation cavity; a piston rod (1702), one end of the piston rod (1702) being connected to the piston (1701), and the other end of the piston rod (1702) extending into the second control port (202) and connected to the valve core (203) of the pressure compensation valve; the third installation cavity defines a piston rod cavity and a non-piston rod cavity at the upper and lower ends of the piston (1701), the non-piston rod cavity being connected to the eighth oil circuit (16), and the piston rod cavity being connected to the T port of the switching valve (14) and the oil tank respectively; The second return spring (1703) is sleeved on the piston rod (1702), one end of the second return spring (1703) is connected to the piston (1701), and the other end is connected to the inner wall of the third installation cavity.

6. A multi-way valve oil inlet module with automatic low-pressure unloading function according to claim 4, characterized in that: Also includes: A leakage oil circuit (18), wherein the T port of the switching valve (14) is connected to the oil tank via a ninth oil circuit (19), one end of the leakage oil circuit (18) is connected to the second mounting cavity, the connection point being close to the first return spring (1403), and the other end is connected to the ninth oil circuit (19).

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