Automatic low-pressure unloading multi-way valve oil inlet module

Abstract

The invention discloses an automatic low-pressure unloading multi-way valve oil inlet module, and relates to the technical field of hydraulic elements and systems, the automatic low-pressure unloading 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 functions of automatically loosening the preset spring, reducing the elastic force of the preset spring and then reducing the preset pressure difference, and at the moment, the working pressure of the hydraulic pump is equal to the reduced preset pressure difference. The effect of reducing the constant pressure difference when the hydraulic cylinder does not act is achieved, and meanwhile the through-flow capacity of the valve 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 automatic low-pressure unloading. 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 actuators are not operating, the 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 valves in the circuit and the movement speed of the actuators, and cannot meet the production requirements. And if valves with a larger flow capacity are 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 while ensuring the flow capacity of the valves 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 automatic low-pressure unloading 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 automatic low-pressure unloading, including:

[0007] A valve block;

[0008] A pressure-compensating valve, arranged in 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, arranged at the upper end of 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 LFeed back to the PL port of the valve block; the first control port of the pressure compensation valve is connected to the PL port of the valve block through the fifth oil passage for transmitting the load pressure p L ; the second control port of the pressure compensation valve is connected to the hydraulic pump through the sixth oil passage 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] An 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 output end of the auxiliary piston mechanism is close to the pressure compensation valve, compressing the preload spring to the first working state and used to provide a downward first preset pressure difference Δp1 to the pressure compensation valve. At this time, p p = p L +Δp1; when the hydraulic cylinder has no action, the LS port of the proportional control valve feeds back a zero load pressure to the PL port, and the output end of the auxiliary piston mechanism is far away from the pressure compensation valve, compressing the preload spring to the second working state and used to provide a downward second preset pressure difference Δp2 to the pressure compensation valve. Δp1>Δp2. At this time, p p =Δp2.

[0012] Further, an overflow valve is further included. The P port of the hydraulic pump is connected to the P port of the overflow valve, the S port of the hydraulic pump is connected to the fuel tank, and the T port of the overflow valve is connected to the fuel tank.

[0013] Further, a first installation cavity is defined in the valve block. The pressure compensation valve has a pressure compensation valve spool, and the pressure compensation valve spool is arranged in the first installation cavity. The first installation cavity forms a first control port and a second control port at the upper and lower ends of the pressure compensation valve spool respectively; the preload spring is arranged in the first control port, one end of the preload spring is connected to the pressure compensation valve spool, and the other end is connected to the auxiliary piston mechanism; one end of the fifth oil passage is connected to the PL port of the valve block, and the other end is connected to the first control port.

[0014] Further, the auxiliary piston mechanism includes a switching valve and a piston assembly. The switching valve includes:

[0015] A switching valve spool. A second installation cavity is defined in the valve block, and the switching valve spool is arranged in the second installation cavity. The second installation cavity forms a third control port at one end of the switching valve spool. The third control port is connected to the first control port through the seventh oil passage; a first return spring is arranged at the other end of the switching valve spool;

[0016] The A port of the switching valve is connected to the piston assembly through the eighth oil passage, 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 is transmitted to the third control port through the seventh oil passage, and the load pressure p L drives the spool of the switching valve to move to the first working valve position against the elastic force of the first return spring, so that the A port and the T port of the switching valve are connected. At this time, the output end of the piston assembly approaches the pressure compensation valve, and compresses the preloading spring to the first working state; 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 spool of the switching valve to the second working valve position, so that the A port and the P port of the switching valve are connected, and the oil pressure p p is transmitted to the piston assembly through the eighth oil passage and drives the output end of the piston assembly to move away from the pressure compensation valve, compressing the preloading spring to the second working state.

[0017] Further, the piston assembly includes:

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

[0019] A first piston rod, one end of the first piston rod is connected to the first piston, and the other end extends into the first control port and is connected to the preloading spring; the first piston rod cavity and the first pistonless rod cavity are defined at the upper and lower ends of the first piston in the third installation cavity, the first piston rod cavity is connected to the eighth oil passage, and the first pistonless rod cavity is respectively connected to the T port of the switching valve and the oil tank;

[0020] A second return spring, which is arranged in the third installation cavity and is located on the side of the first piston away from the first piston rod, one end of the second return spring is connected to the first piston, and the other end is connected to the inner side wall of the third installation cavity.

[0021] Further, the auxiliary piston mechanism may further include:

[0022] A second piston, the valve block defines a fourth installation cavity, and the second piston is arranged in the fourth installation cavity;

[0023] A second piston rod, one end of the second piston rod is connected to the second piston, and the other end extends into the first control port and is connected to the preloading spring; the second piston rod cavity and the second pistonless rod cavity are defined at the upper and lower ends of the second piston in the fourth installation cavity;

[0024] A third return spring is disposed in the fourth installation cavity and on the side of the second piston close to the second piston rod. One end of the third return spring is connected to the second piston, and the other end is connected to the inner side wall of the fourth installation cavity;

[0025] A check valve. The second rodless cavity is communicated with the hydraulic pump through a tenth oil passage, and the check valve is disposed on the tenth oil passage;

[0026] A drain pipe, one end of which is communicated with the tenth oil passage, the communication position is between the check valve and the second rodless cavity, and the other end is communicated with the hydraulic pump. A throttle valve is disposed on the drain pipe;

[0027] When the hydraulic cylinder moves, the hydraulic oil of the hydraulic cylinder enters the second rodless cavity through the tenth oil passage and pushes the second piston rod close to the pressure compensation valve, compressing the preloading spring to the first working state; when the hydraulic cylinder stops moving, the hydraulic oil in the rodless cavity is discharged along the drain pipe, and the third return spring pushes the second piston rod away from the pressure compensation valve, compressing the preloading spring to the second working state.

[0028] Further, a limit bolt is further included. The limiting end of the limit bolt is disposed in the first rodless cavity or the second rodless cavity and is spaced from the second return spring or the third return spring. When the preloading spring is in the second working state, the limiting end of the limit bolt is in contact with the first piston or the second piston.

[0029] Further, the following is further included:

[0030] A leakage oil passage. The T port of the switching valve is communicated with the fuel tank through a ninth oil passage. One end of the leakage oil passage is communicated with the second installation cavity, the communication position is close to the first return spring, and the other end is communicated with the ninth oil passage.

[0031] The present invention discloses the following technical effects:

[0032] 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 functions of automatically relaxing the preset spring, reducing the elastic force of the preset spring, and further reducing the preset pressure difference. At this time, the working pressure of the hydraulic pump is equal to the reduced preset pressure difference. That is to say, this application realizes 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 oil pressure of the hydraulic pump or the feedback load pressure of the proportional control valve, and can act automatically according to the working conditions of the hydraulic pump or the situation of the feedback load pressure, reducing the unloading pressure of the hydraulic pump, having good energy-saving effects and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] 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.

[0034] Figure 1 Structural schematic diagram of Embodiment 1 of the present invention;

[0035] Figure 2 Structural schematic diagram of the valve block in Embodiment 1;

[0036] Figure 3 Structural schematic diagram of Embodiment 2 of the present invention;

[0037] Figure 4 Structural schematic diagram of the valve block in Embodiment 2;

[0038] 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 circuit; 4. hydraulic pump; 5. second oil circuit; 6. preloading spring; 7. proportional control valve; 8. third oil circuit; 9. fourth oil circuit; 10. hydraulic cylinder; 11. fifth oil circuit; 12. sixth oil circuit; 13. overflow valve; 14. switching valve; 1401. switching valve spool; 1402. third control port; 1403. first return spring; 15. seventh oil circuit; 16. eighth oil circuit; 17. piston assembly; 1701. first piston; 1702. first piston rod; 1703. second return spring; 1704. limit bolt; 18. leakage oil circuit; 19. ninth oil circuit; 20. second piston; 21. second piston rod; 22. third return spring; 23. check valve; 24. tenth oil circuit; 25. drain pipe; 26. throttle valve. Detailed implementation manners

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0041] Embodiment 1

[0042] The embodiment of the present invention provides a multi-way valve inlet module with automatic low-pressure unloading, including:

[0043] Valve block 1;

[0044] A pressure compensation valve 2 is arranged in the valve block 1. The P port of the pressure compensation valve 2 is connected to the hydraulic pump 4 through the first oil circuit 3, and the T port is connected to the fuel tank through the second oil circuit 5;

[0045] A preloading spring 6 is arranged at the upper end of the pressure compensation valve 2;

[0046] A proportional control valve 7, its P port is connected to the hydraulic pump 4 through the third oil circuit 8, and the T port is connected to the fuel tank through the fourth oil circuit 9; its A port is connected to the rodless cavity of the hydraulic cylinder 10, and the B port is connected to the rod cavity 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 to feed back the load pressure p L 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 passage 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;

[0047] The auxiliary piston mechanism is connected to the PL port of the valve block 1. When the hydraulic cylinder 10 works, 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 output end of the auxiliary piston mechanism is close to the pressure compensation valve 2, and the preloading spring 6 is compressed to the first working state. The preloading spring 6 provides a downward first preset pressure difference Δp1 to the pressure compensation valve 2. At this time, p p = p L + Δp1; when the hydraulic cylinder 10 has no action, the LS port of the proportional control valve 7 feeds back a zero load pressure to the PL port, and the output end of the auxiliary piston mechanism is far from the pressure compensation valve 2, and the preloading spring 6 is compressed to the second working state. At this time, the preloading spring 6 provides a downward second preset pressure difference Δp2 to the pressure compensation valve 2, Δp1 > Δp2. At this time, p p = Δp2.

[0048] In this embodiment, an overflow valve 13 is further included. The P port of the hydraulic pump 4 is connected to the P port of the overflow valve 13, the S port of the hydraulic pump 4 is connected to the fuel tank, and the T port of the overflow valve 13 is connected to the fuel tank.

[0049] Furthermore, a first installation cavity is defined in the valve block 1. The pressure compensation valve 2 has a pressure compensation valve spool 203. The pressure compensation valve spool 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 spool 203 respectively; the preloading spring 6 is arranged in the first control port 201. One end of the preloading spring 6 is connected to the pressure compensation valve spool 203, and the other end is connected to the auxiliary piston mechanism; one end of the fifth oil passage 11 is connected to the PL port of the valve block 1, and the other end is connected to the first control port 201.

[0050] In this embodiment, the switching valve 14 includes:

[0051] A switching valve spool 1401. A second installation cavity is defined in the valve block 1. The switching valve spool 1401 is arranged in the second installation cavity. The second installation cavity forms a third control port 1402 at one end of the switching valve spool 1401. The third control port 1402 is connected to the first control port 201 through the seventh oil passage 15; a first return spring 1403 is arranged at the other end of the switching valve spool 1401;

[0052] The A port of the switching valve 14 is connected to the piston assembly 17 through the eighth oil passage 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 fuel 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 , the load pressure p L is transmitted to the third control port 1402 through the seventh oil passage 15. The load pressure p L drives the switching valve spool 1401 to move to the first working valve position at the left end against the elastic force of the first return spring 1403, so that the A port of the switching valve 14 is connected to the T port. At this time, the output end of the piston assembly 17 approaches the pressure compensation valve 2, and the preloading spring 6 is compressed to the first working state. When the hydraulic cylinder 10 has no action, the LS port of the proportional control valve 7 feeds back a zero load pressure to the PL port, and the first return spring 1403 moves the switching valve spool 1401 to the second working valve position at the right end, so that the A port of the switching valve 14 is connected to the P port, and the oil pressure p p is transmitted to the piston assembly 17 through the eighth oil passage 16 and drives the output end of the piston assembly 17 to move away from the pressure compensation valve 2, and the preloading spring 6 is compressed to the second working state.

[0053] In this embodiment, the piston assembly 17 includes:

[0054] A first piston 1701, the valve block 1 defines a third installation cavity, and the first piston 1701 is arranged in the third installation cavity;

[0055] A first piston rod 1702, one end of the first piston rod 1702 is connected to the first piston 1701, and the other end extends into the first control port 201 and is connected to the preloading spring 6. The first piston 1701 defines a first piston rod cavity and a first piston rodless cavity at its upper and lower ends. The first piston rod cavity is connected to the eighth oil passage 16, and the first piston rodless cavity is respectively connected to the T port of the switching valve 14 and the fuel tank;

[0056] A second return spring 1703, which is arranged in the third installation cavity and is located on the side of the first piston 1701 away from the first piston rod 1702. One end of the second return spring 1703 is in contact with the first piston 1701, and the other end is in contact with the inner side wall of the third installation cavity.

[0057] In this embodiment, it further includes:

[0058] The limit bolt 1704 has its limit end disposed in the first rodless piston cavity and spaced from the second return spring 1703 (actually located in the middle cavity of the second return spring 1703). When the preloading spring 6 is in the second working state, the limit end of the limit bolt 1704 contacts the first piston 1701. The limit bolt 1704 is screwed into the valve block 1 from the outside, and its rotating operating end is outside the valve block 1. The function of the limit bolt 1704 is to limit the retraction displacement of the first piston 1701 in the state where the hydraulic cylinder 10 is inoperative, thereby realizing the function of controlling the magnitude of the second preset pressure difference Δp2.

[0059] In this embodiment, it further includes:

[0060] The leakage oil passage 18, the T port of the switching valve 14 is communicated with the L port through the ninth oil passage 19, the L port is communicated with the fuel tank, one end of the leakage oil passage 18 is communicated with the second installation cavity, the communicating position is close to the first return spring 1403, and the other end is communicated with the ninth oil passage 19.

[0061] The specific working process is as follows:

[0062] 1. The hydraulic cylinder works

[0063] As Figure 1 and Figure 2 shown, taking the extension movement of the hydraulic cylinder 10 as an example (the retraction movement has a similar principle), the proportional control valve works in the first working valve position. The hydraulic pump 4 sucks oil from the fuel tank, the high-pressure oil is discharged from the P port of the hydraulic pump 4, and is delivered to the P port of the proportional control valve 7 through the third oil passage 8, and enters the rodless cavity of the hydraulic cylinder 10 from the A port of the proportional control valve 7, pushing the first piston rod 1702 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 fuel tank.

[0064] 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.

[0065] For the upper end surface 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 second return spring 1703 compresses the preloading spring 6 through the first piston 1701 and the first piston rod 1702, so that the preloading spring 6 also acts on the pressure compensation valve 2, and the acting effect is the first preset pressure difference Δp1. It can be seen that the force on the upper end surface of the pressure compensation valve 2 is p L +Δp1.

[0066] For the lower end face of the pressure compensation valve 2, the high-pressure hydraulic oil from the hydraulic pump is transmitted through the sixth oil passage 12 to apply the oil pressure p p .

[0067] 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 at the left end. The A port and the T port of the switching valve 14 are communicated. The first piston 1701 and the first piston rod 1702 approach the pressure compensation valve 2 under the action of the second return spring 1703, compressing the preloading spring 6 to the first working state. It can be seen that when the pressure compensation valve 2 is in force balance, p p =p L +Δp1. At this time, the working pressure of the hydraulic pump 4 is equal to the sum of the load pressure and the preset pressure difference.

[0068] 2. The hydraulic cylinder has no action

[0069] When the hydraulic cylinder 10 has no action, the load pressure signal fed back by the proportional valve 7 is zero.

[0070] 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 at the right end. 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 first piston rod chamber of the third installation cavity. This pressure can overcome the elastic force of the second return spring 1703 and push the first piston 1701 and the first piston rod 1702 to move away from the pressure compensation valve 2 (the oil in the first pistonless chamber flows to the fuel tank. Actually, the operating mechanism of the piston assembly 17 is similar to that of the hydraulic cylinder 10). The first piston rod 1702 reduces the pressure on the preloading spring 6, making the preloading spring 6 in the second working state (it should be noted that both the first working state and the second working state are in the compressed state, but the compression amount in the first working state is larger, so the first preset pressure difference Δp1 is larger). The pressure difference generated by the preloading spring 6 on the pressure compensation valve 2 is reduced to Δp2. Therefore, at this time p p =Δp2 and Δp1>Δp2. Compared with the prior art, when the hydraulic cylinder 10 has no action, the working pressure of the hydraulic pump 4 is not the first preset pressure difference Δp1, but is reduced to the second preset pressure difference Δp2 on the basis of the first preset pressure difference Δp1.

[0071] For the common preloaded spring 6, its first preset pressure difference is generally Δp1 = 0.8 MPa. Assuming that the second preset pressure difference Δp2 = 0.4 MPa when the hydraulic pump is not working, at this time, the oil pressure (working pressure) p of the hydraulic pump 4 p = 0.4 MPa, and its load is directly reduced by half, which can reduce half of the energy waste of the system.

[0072] Embodiment 2

[0073] As Figure 3 and Figure 4 shown, the difference between this embodiment and Embodiment 1 is that the auxiliary piston mechanism includes:

[0074] A second piston 20, the valve block 1 defines a fourth installation cavity, and the second piston 20 is arranged in the fourth installation cavity;

[0075] A second piston rod 21, one end of the second piston rod 21 is connected to the second piston 20, and the other end extends into the first control port 201 and is connected to the preloaded spring 6; the second piston 20 defines a second piston rod cavity and a second rodless cavity at its upper and lower ends in the fourth installation cavity;

[0076] A third return spring 22, which is arranged in the fourth installation cavity and is located on the side of the second piston 20 close to the second piston rod 21. One end of the third return spring 22 is connected to the second piston 20, and the other end is connected to the inner side wall of the fourth installation cavity;

[0077] A one-way valve 23, the second rodless cavity is communicated with the hydraulic pump 4 through the tenth oil passage 24, and the one-way valve 23 is arranged on the tenth oil passage 24;

[0078] A drain pipe 25, one end of which is communicated with the tenth oil passage 24, and the communication position is between the one-way valve 23 and the second rodless cavity, and the other end is communicated with the hydraulic pump 4. A throttle valve 26 is arranged on the drain pipe 25;

[0079] Its working process is similar to that of Embodiment 1. Specifically, when the hydraulic cylinder 10 moves, the oil of the hydraulic pump 4 enters the second rodless cavity through the one-way valve 23 and the tenth oil passage 24 and pushes the second piston rod 21 close to the pressure compensation valve 2, compressing the preloaded spring 6 to the first working state; when the hydraulic cylinder 10 stops moving, since the pressure feedback by the fifth oil passage 11 is zero, the pressure of the hydraulic pump 4 decreases, and the third return spring 22 pushes the second piston 20 and the second piston rod 21 to move to the right, and the oil in the rodless cavity is discharged through the tenth oil passage 24, the throttle valve 26, and the drain pipe 25, and the preloaded spring 6 turns into the second working state.

[0080] 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 to the present invention.

[0081] The above-described embodiments are only descriptions of the preferred embodiments 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 solutions 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, 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) is arranged at the upper end of 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) is capable of adjusting 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 output end of the auxiliary piston mechanism is close to the pressure compensation valve (2), compressing the pre-compression spring (6) to a first working state and providing a first preset downward pressure difference Δp1 to 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 output end of the auxiliary piston mechanism is away from the pressure compensation valve (2), the preload spring (6) is compressed to the second working state and is used to provide the pressure compensation valve (2) with a second preset downward pressure difference Δp2, Δp1>Δp2, at this time p p =Δp2.

2. The multi-way valve oil inlet module with automatic low-pressure unloading according to claim 1 is 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. The multi-way valve oil inlet module with automatic low-pressure unloading according to claim 1 is 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 auxiliary piston mechanism; 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. The multi-way valve oil inlet module with automatic low-pressure unloading according to claim 3 is 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. At this time, the output end of the piston assembly (17) is close to the pressure compensation valve (2), and the pre-compression spring (6) is compressed to the first working state; 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 pressure is transmitted to the piston assembly (17) through the eighth oil passage (16) and drives the output end of the piston assembly (17) away from the pressure compensation valve (2), thereby compressing the pre-compression spring (6) to the second working state.

5. The multi-way valve oil inlet module with automatic low-pressure unloading according to claim 4 is characterized in that: The piston assembly (17) comprises: a first piston (1701), the valve block (1) defines a third installation cavity, and the first piston (1701) is arranged in the third installation cavity; a first piston rod (1702), one end of the first piston rod (1702) being connected to the first piston (1701), and the other end of the first piston rod (1702) extending into the first control port (201) and connected to the preload spring (6); the third mounting chamber defines a first piston rod chamber and a first piston rod-free chamber at the upper and lower ends of the first piston (1701), the first piston rod chamber being connected to the eighth oil circuit (16), and the first piston rod-free chamber being connected to the T port of the switching valve (14) and the oil tank respectively; The second return spring (1703) is arranged in the third installation cavity and is located on the side of the first piston (1701) away from the first piston rod (1702). One end of the second return spring (1703) is connected to the first piston (1701), and the other end is connected to the inner wall of the third installation cavity.

6. The multi-way valve oil inlet module with automatic low-pressure unloading according to claim 3 is characterized in that: The auxiliary piston mechanism comprises: a second piston (20), the valve block (1) defining a fourth mounting cavity, the second piston (20) being disposed in the fourth mounting cavity; a second piston rod (21), one end of the second piston rod (21) being connected to the second piston (20), and the other end of the second piston rod (21) extending into the first control port (201) and connected to the preload spring (6); the fourth mounting cavity defining a second piston rod cavity and a second piston rod-free cavity at the upper and lower ends of the second piston (20); a third return spring (22), which is arranged in the fourth installation cavity and is located on a side of the second piston (20) close to the second piston rod (21), wherein one end of the third return spring (22) is connected to the second piston (20), and the other end is connected to the inner wall of the fourth installation cavity; a one-way valve (23), wherein the second piston rod-free chamber is connected to the hydraulic pump (4) via a tenth oil passage (24), and the one-way valve (23) is arranged on the tenth oil passage (24); a liquid discharge pipe (25), one end of which is in communication with the tenth oil circuit (24), the communication point being located between the one-way valve (23) and the second piston rod-free chamber, and the other end of which is in communication with the hydraulic pump (4); a throttle valve (26) is provided on the liquid discharge pipe (25); When the hydraulic cylinder (10) moves, the oil in the hydraulic cylinder (10) enters the second piston rod-free chamber through the tenth oil path (24) and pushes the second piston rod (21) close to the pressure compensation valve (2), compressing the pre-compression spring (6) to the first working state; when the hydraulic cylinder (10) stops moving, the oil in the piston rod-free chamber is discharged along the drain pipe (25), and the third return spring (22) pushes the second piston rod (21) away from the pressure compensation valve (2), compressing the pre-compression spring (6) to the second working state.

7. The multi-way valve oil inlet module with automatic low-pressure unloading according to claim 5 is characterized in that: Also includes: A limiting bolt (1704), whose limiting end is arranged in the first piston rod-free cavity and is spaced apart from the second return spring (1703); when the preload spring (6) is in the second working state, the limiting end of the limiting bolt (1704) is connected to the first piston (1701).

8. The multi-way valve oil inlet module with automatic low-pressure unloading according to claim 4 is 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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