A proportional air hole relief valve

Abstract

, an oil pump having a seal, is provided at the bottom of the oil drain plug, and the seal ...

Description

Technical Field

[0001] The invention relates to the technical field of pressure valves, in particular to a proportional air hole overflow valve. Background Art

[0002] The overflow valve is a commonly used pressure valve. One of the characteristics of hydraulic transmission is that it can easily achieve overload protection. This is the role of the overflow valve. It overflows through the opening of the valve port to keep the system pressure constant or limit the maximum pressure. The overflow valve can not only play the role of a safety valve, but also be used as a pressure regulating valve, unloading valve, back pressure valve, balancing valve, etc. When used as a safety valve in the system, the overflow valve is in a normally closed state and only opens to overflow when the system is overloaded to limit the maximum pressure of the hydraulic system and protect the hydraulic system or mechanical structure; in the throttle valve speed control system, the overflow valve is in a normally open state. At this time, the overflow valve is a pressure regulating valve or a constant pressure valve to keep the system pressure constant.

[0003] The working principle of the proportional relief valve is: the proportional relief valve changes the overflow pressure by the size of the spring force, and the force of the proportional solenoid on the spring can be adjusted proportionally, so the pressure of the proportional relief valve will also change when the input signal changes. Figure 1 The pilot-operated proportional relief valve is a valve that is divided into a pilot valve and a main valve. When working, the hydraulic pressure acts on the pressure measuring surfaces of the main valve core and the pilot valve core at the same time. When the pilot valve 1 is not opened, the oil in the valve chamber does not flow, and the pressure acting on the main valve core 6 in the upper and lower directions is equal. However, because the effective pressure area A2 of the upper end face is larger than the effective pressure area A1 of the lower end face, the main valve core is at the lowest position under the action of the combined force, and the valve port is closed. When the oil inlet pressure increases to open the pilot valve, the liquid flows back to the oil tank through the damping hole 5 and the pilot valve 1 on the main valve core. Due to the damping effect of the damping hole, the hydraulic pressures in the upper and lower directions on the main valve core 6 are not equal. The main valve core moves up under the action of the pressure difference, opens the valve port, realizes overflow, and maintains the pressure basically stable. The overflow pressure can be adjusted by adjusting the pressure regulating spring 9 of the pilot valve. Therefore, the pilot-operated proportional relief valve is usually used in high-pressure pipelines.

[0004] Since the pilot-operated proportional relief valve works in a high-pressure pipeline, and it takes some time for the valve to overflow from opening, in actual use, in the short time when the high-pressure pipeline liquid just flows into the valve, the high-pressure fluid will bring great impact and pressure to the valve and the liquid outlet pipe. This stamping will cause certain losses to the valve and the pipeline, and have an adverse effect on the service life of the valve and the pipeline; therefore, it does not meet the existing needs, and we have proposed a proportional air hole relief valve. Summary of the invention

[0005] The present invention provides a proportional air hole relief valve, which has the beneficial effect of solving the problem mentioned in the above background technology that since the working environment of the pilot proportional relief valve is a high-pressure pipeline, and the valve takes a period of time from opening to overflowing, therefore in actual use, in the short time when the high-pressure pipeline liquid just flows into the valve, the high-pressure fluid will bring great impact and pressure to the valve and the liquid outlet pipe, and this stamping will cause certain losses to the valve and the pipeline, which will have an adverse effect on the service life of the valve and the pipeline.

[0006] The present invention provides the following technical solution: a proportional air hole relief valve, comprising a machine box, the side of the machine box is connected with an oil inlet, an oil outlet and an oil return port, the side of the machine box is installed with a pilot valve body for adjusting the overflow pressure and a first valve body for achieving overflow, the oil inlet, the oil outlet and the oil return port are all connected with the first valve body and the pilot valve body, and also includes:

[0007] A pressure reducing plate assembly is used to adjust the instantaneous oil pressure of the oil inlet. The pressure reducing plate assembly is arranged on a connecting pipe between the oil inlet and the oil outlet. The pressure reducing plate assembly includes a fixed valve plate with a hole, and a movable valve plate with a hole slidably fitted on the side of the fixed valve plate with a hole. A connecting rod is connected between the movable valve plate with a hole and the first valve core of the first valve body.

[0008] As an optional solution for a proportional air hole overflow valve described in the present invention, the fixed valve plate with a hole is configured as a fixed plate with a through hole in the middle, and the movable valve plate with a hole is configured as a sliding plate with a through hole in the middle, and the through holes of the fixed valve plate with a hole and the movable valve plate with a hole remain overlapping.

[0009] As an optional scheme of a proportional air hole overflow valve described in the present invention, wherein: a cross oil pipe is connected to the side of the first valve body, the upper end of the cross oil pipe is connected to the pilot valve body, the left end of the cross oil pipe is connected to the second valve body, the right end of the cross oil pipe is connected to the oil outlet, a first oil pipe is connected between the second valve body and the pilot valve body, a second oil pipe is connected between the second valve body and the oil return port, a third oil pipe is connected between the second valve body and the first valve body, the oil inlet is connected in series with the first valve body, the pilot valve body, the second valve body and the oil return port, an oil inlet pipe is connected between the oil inlet and the first valve body, an oil outlet pipe is connected between the oil outlet and the oil inlet pipe, an oil return pipe is installed on the inner side of the oil return port, and the diameters of the cross oil pipe, the first oil pipe, the second oil pipe and the third oil pipe are smaller than the diameters of the oil inlet pipe, the oil outlet pipe and the oil return pipe.

[0010] As an optional solution of a proportional air hole overflow valve described in the present invention, the second valve body includes a second oil chamber arranged inside the machine box, a second valve core slidably installed inside the second oil chamber, a second spring abutting against the rear side of the second valve core, and a regulating valve block abutting against the rear side of the second spring and capable of adjusting the pressure, wherein the regulating valve block is configured as a block with bolts on the rear side.

[0011] As an optional scheme of a proportional air hole overflow valve described in the present invention, the second valve core is configured as a hollow block that slides in contact with the end of the second oil chamber, and a plurality of side open flow holes are distributed on the side wall of the second valve core, and the liquid in the first oil pipe flows into the second oil pipe through the side open flow holes.

[0012] As an optional scheme for a proportional air hole overflow valve described in the present invention, wherein: the first valve body includes a first oil chamber opened inside the machine box, the first valve core slidably installed inside the first oil chamber, and a first spring connected between the first valve core and the top wall of the first oil chamber, the first spring is located in the opposite direction of the oil inlet pipe, the pilot valve body includes a pilot oil chamber arranged inside the machine box, a pilot valve core slidably installed in the pilot oil chamber, an adjusting spring abutting on the back side of the pilot valve core, an adjusting rod abutting on the rear side of the adjusting spring to adjust the pressure, a pilot overflow port connected to the pilot oil chamber, and a pilot sealing valve port engaged with the pilot valve core, the pilot sealing valve port is located between the pilot valve core and the pilot overflow port.

[0013] As an optional scheme for a proportional air hole overflow valve described in the present invention, when the oil pressure at the oil inlet is normal, the first valve core is located at the bottom of the first oil chamber, the pipe mouth of the third oil pipe is blocked by the first valve core, the through hole of the fixed valve plate with holes overlaps and is aligned with the through hole of the movable valve plate with holes, and the liquid in the oil inlet pipe directly enters the oil outlet pipe.

[0014] As an optional scheme of a proportional air hole overflow valve described in the present invention, when the oil pressure at the oil inlet lifts the first valve core to the middle of the first oil chamber, the first valve core drives the movable valve plate with a hole to move upward through the connecting rod, and the overlapping area of ​​the through hole of the movable valve plate with a hole and the through hole of the fixed valve plate with a hole is reduced, thereby realizing oil quantity limitation.

[0015] As an optional scheme for a proportional air hole overflow valve described in the present invention, when the oil pressure reaching the oil outlet pipe is still greater than the oil pressure of the required outlet, the oil in the oil outlet pipe extends upward to the cross oil pipe, the oil at the left end of the cross oil pipe is blocked by the second valve core, the oil at the lower end of the cross oil pipe is blocked by the first valve core, the oil at the upper end of the cross oil pipe enters the pilot valve body, the pilot valve core moves, the oil enters the pilot overflow port and the first oil pipe, and the oil overflows into the return oil pipe through the side open flow hole.

[0016] As an optional scheme for a proportional air hole overflow valve described in the present invention, when the oil pressure at the oil inlet lifts the first valve core to the uppermost end of the first oil chamber, the first valve core drives the movable valve plate with a hole to move upward through the connecting rod, and the overlapping area of ​​the through hole of the movable valve plate with a hole and the through hole of the fixed valve plate with a hole is reduced to a minimum, and the pipe mouth of the third oil pipe is connected to the first oil chamber, and the oil in the first oil chamber directly enters the return oil pipe through the third oil pipe and overflows.

[0017] The present invention has the following beneficial effects:

[0018] 1. The proportional air hole relief valve is provided with a pressure reducing plate assembly between the oil inlet pipe and the oil outlet pipe, and the pressure reducing plate assembly is drivingly connected to the first valve body. At the moment when the high-pressure oil enters the relief valve, the high-pressure oil pushes up the first valve core, so that the first valve core drives the movable valve plate with holes to move upward, so that the channel of the combination of the movable valve plate with holes and the fixed valve plate with holes becomes narrower, thereby restricting the oil, so that the high-pressure oil is buffered and reduced in flow after flowing out of the oil outlet pipe, and the greater the oil inlet pressure, the higher the first valve core is lifted, the more the movable valve plate with holes moves upward, the smaller the channel, the greater the restriction on the oil flowing through, thereby realizing the protection of other components of the relief valve and extending the service life of the relief valve.

[0019] 2. The proportional air hole overflow valve can realize multi-stage overflow in proportion through the cooperation between the first valve body, the pilot valve body and the second valve body. When the first valve core is lifted to the middle, there is no flow between the third oil pipe and the oil inlet pipe. At this time, the oil spreads to the lower side of the pilot valve body and the side of the second valve body through the cross oil pipe. If the oil is greater than the set pressure of the pilot valve body, the pilot valve core moves, and the oil can flow into the oil outlet pipe through the side open flow hole. If the oil pressure is greater than the set pressure of the second valve body, the oil can directly push the second valve core, so that the oil in the cross oil pipe can directly flow into the second oil pipe and overflow from the return oil pipe. It can cope with hydraulic pressures under different pressure conditions and make the hydraulic system more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the prior art of the present invention.

[0021] Figure 2 It is a schematic diagram of the main stereoscopic structure of the present invention.

[0022] Figure 3 It is a schematic diagram of the top three-dimensional structure of the present invention.

[0023] Figure 4 It is a schematic diagram of the first cross-sectional structure of the present invention.

[0024] Figure 5 It is a schematic diagram of the second cross-sectional structure of the present invention.

[0025] Figure 6 It is a schematic diagram of the structure of the present invention during normal hydraulic pressure.

[0026] Figure 7 This is a schematic diagram of the structure of the present invention when the hydraulic pressure is slightly larger.

[0027] Figure 8 It is a structural schematic diagram of the present invention when the hydraulic pressure is relatively large.

[0028] Fig. 9 It is a schematic diagram of the structure of the hydraulic maximum of the present invention.

[0029] In the figure: 110, machine box; 120, oil inlet; 130, oil outlet; 140, oil return port; 150, oil inlet pipe; 160, oil outlet pipe; 170, oil return pipe; 180, first valve body; 181, first valve core; 182, first spring; 183, first oil chamber; 190, pilot valve body; 191, pilot valve core; 192, adjusting rod; 193, adjusting spring; 194, pilot sealing valve port; 195, pilot Oil guide chamber; 196, pilot overflow port; 200, second valve body; 210, second valve core; 220, side open flow hole; 230, second spring; 240, regulating valve block; 250, pressure reducing plate assembly; 251, movable valve plate with hole; 252, fixed valve plate with hole; 253, connecting rod; 260, second oil chamber; 310, cross oil pipe; 320, first oil pipe; 330, second oil pipe; 340, third oil pipe. DETAILED DESCRIPTION

[0030] 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.

[0031] Example 1

[0032] This embodiment is intended to promote the solution of the problem that the pilot-operated proportional relief valve works in a high-pressure pipeline, and it takes a while for the valve to overflow from opening. Therefore, in actual use, in the short time when the high-pressure pipeline liquid just flows into the valve, the high-pressure fluid will bring great impact and pressure to the valve and the liquid outlet pipe. This stamping will cause certain damage to the valve and the pipeline, and have an adverse effect on the service life of the valve and the pipeline. Please refer to Figure 2-Figure 9 A proportional air hole relief valve includes a machine box 110, a side of the machine box 110 is connected with an oil inlet 120, an oil outlet 130 and an oil return port 140, a pilot valve body 190 for adjusting the overflow pressure and a first valve body 180 for achieving overflow are installed on the side of the machine box 110, the oil inlet 120, the oil outlet 130 and the oil return port 140 are all connected with the first valve body 180 and the pilot valve body 190, and also includes:

[0033] The pressure reducing plate assembly 250 is used to adjust the instantaneous oil pressure of the oil inlet 120. The pressure reducing plate assembly 250 is arranged on the connecting pipe between the oil inlet 120 and the oil outlet 130. The pressure reducing plate assembly 250 includes a fixed valve plate 252 with holes, and a movable valve plate 251 with holes slidably attached to the side of the fixed valve plate 252 with holes. A connecting rod 253 is fixedly connected between the movable valve plate 251 with holes and the first valve core 181 of the first valve body 180. In the specific setting, the fixed valve plate 252 with holes is set as a fixed plate with a through hole in the middle, and the movable valve plate 251 with holes is set as a sliding plate with a through hole in the middle. The through holes of the fixed valve plate 252 with holes and the movable valve plate 251 with holes are kept overlapping, so as to form a channel for oil to flow through, and the size of the channel is adjustable, so as to cause different degrees of flow restriction on the oil.

[0034] A cross oil pipe 310 is connected to the side of the first valve body 180, the upper end of the cross oil pipe 310 is connected to the pilot valve body 190, the left end of the cross oil pipe 310 is connected to the second valve body 200, the right end of the cross oil pipe 310 is connected to the oil outlet 130, a first oil pipe 320 is connected between the second valve body 200 and the pilot valve body 190, a second oil pipe 330 is connected between the second valve body 200 and the oil return port 140, and a third oil pipe 340 is connected between the second valve body 200 and the first valve body 180. The oil port 120 is connected in series with the first valve body 180, the pilot valve body 190, the second valve body 200 and the oil return port 140. An oil inlet pipe 150 is connected between the oil inlet port 120 and the first valve body 180. An oil outlet pipe 160 is connected between the oil outlet port 130 and the oil inlet pipe 150. An oil return pipe 170 is installed on the inner side of the oil return port 140. The diameters of the cross oil pipe 310, the first oil pipe 320, the second oil pipe 330 and the third oil pipe 340 are smaller than the diameters of the oil inlet pipe 150, the oil outlet pipe 160 and the oil return pipe 170.

[0035] The second valve body 200 includes a second oil chamber 260 arranged inside the machine box 110, a second valve core 210 slidably installed inside the second oil chamber 260, a second spring 230 abutting against the rear side of the second valve core 210, and a regulating valve block 240 abutting against the rear side of the second spring 230 and capable of adjusting the pressure. The regulating valve block 240 is configured as a block with bolts on the rear side. The tighter the bolts, the deeper the position of the regulating valve block 240, and the greater the pressure generated by the second spring 230 on the second valve core 210.

[0036] The second valve core 210 is configured as a hollow block that slides in contact with the end of the second oil chamber 260 . A plurality of side open flow holes 220 are distributed on the side wall of the second valve core 210 . The liquid in the first oil pipe 320 flows into the second oil pipe 330 through the side open flow holes 220 .

[0037] The first valve body 180 includes a first oil chamber 183 opened inside the machine box 110, a first valve core 181 slidably installed inside the first oil chamber 183, and a first spring 182 connected between the first valve core 181 and the top wall of the first oil chamber 183, the first spring 182 is located in the opposite direction of the oil inlet pipe 150, the pilot valve body 190 includes a pilot oil chamber 195 arranged inside the machine box 110, a pilot valve core 191 slidably installed in the pilot oil chamber 195, an adjusting spring 193 abutting against the back side of the pilot valve core 191, an adjusting rod 192 abutting against the rear side of the adjusting spring 193 and capable of adjusting the pressure, a pilot overflow port 196 communicated with the pilot oil chamber 195, and a pilot sealing valve port 194 engaged with the pilot valve core 191, the pilot sealing valve port 194 is located between the pilot valve core 191 and the pilot overflow port 196. The adjusting rod 192 in this embodiment is configured as an adjusting bolt and a nut. The tighter the adjusting rod 192 is, the greater the pressure of the adjusting spring 193 is. Conversely, the looser the adjusting rod 192 is, the smaller the pressure is.

[0038] It should be noted that the pilot valve body 190 may also be configured as a solenoid valve.

[0039] See Figure 6 When the oil pressure at the oil inlet 120 is normal, the first valve core 181 is located at the bottom of the first oil chamber 183, the pipe mouth of the third oil pipe 340 is blocked by the first valve core 181, the through hole of the fixed valve plate 252 with a hole overlaps and is aligned with the through hole of the movable valve plate 251 with a hole, and the liquid in the oil inlet pipe 150 directly enters the oil outlet pipe 160.

[0040] See Figure 7 When the oil pressure at the oil inlet 120 is relatively high, the first valve core 181 is lifted and drives the movable valve plate 251 with a hole to move upward, so that the overlapping area between the through hole of the fixed valve plate 252 with a hole and the through hole of the movable valve plate 251 with a hole becomes smaller, and the channel formed by the two becomes narrower, restricting the oil passing through.

[0041] See Fig. 9When the oil pressure at the oil inlet 120 is greater than the pressure set by the first valve body 180, the first valve core 181 is lifted to the highest position and drives the movable valve plate 251 with a hole to move upward, so that the overlapping area between the through hole of the fixed valve plate 252 with a hole and the through hole of the movable valve plate 251 with a hole becomes smaller and is minimized, and the channel formed by the two becomes narrower, restricting the oil passing through.

[0042] In this embodiment: by arranging a pressure reducing plate assembly 250 between the oil inlet pipe 150 and the oil outlet pipe 160, and drivingly connecting the pressure reducing plate assembly 250 with the first valve body 180, at the moment when the high-pressure oil enters the relief valve, the high-pressure oil pushes up the first valve core 181, so that the first valve core 181 drives the movable valve plate 251 with holes to move upward, so that the channel of the combination of the movable valve plate 251 with holes and the fixed valve plate 252 with holes becomes narrower, thereby restricting the oil, so that the high-pressure oil is buffered and reduced in flow after flowing out of the oil outlet pipe 160, and the greater the oil inlet pressure, the higher the first valve core 181 is lifted, the more the movable valve plate 251 with holes moves upward, and the smaller the channel, the greater the restriction on the oil flowing through, thereby realizing the protection of other components of the relief valve, extending the service life of the relief valve, and maintaining the pressure basically stable.

[0043] Example 2

[0044] This embodiment is intended to promote the solution of the problem that the hydraulic system needs to maintain hydraulic stability when facing different pressures. This embodiment is an improvement made on the basis of embodiment 1. Specifically, the difference from embodiment 1 is that, please refer to Figure 8 When the oil pressure at the oil inlet 120 lifts the first valve core 181 to the middle of the first oil chamber 183, the first valve core 181 drives the movable valve plate 251 with a hole to move upward through the connecting rod 253, and the overlapping area of ​​the through hole of the movable valve plate 251 with a hole and the through hole of the fixed valve plate 252 with a hole is reduced, thereby realizing oil quantity limitation.

[0045] At the same time, when the oil pressure reaching the oil outlet pipe 160 is still greater than the oil pressure of the required outlet, the oil in the oil outlet pipe 160 extends upward to the cross oil pipe 310, the oil at the left end of the cross oil pipe 310 is blocked by the second valve core 210, and the oil at the lower end of the cross oil pipe 310 is blocked by the first valve core 181. The oil at the upper end of the cross oil pipe 310 enters the pilot valve body 190, the pilot valve core 191 moves, and the oil enters the pilot overflow port 196 and the first oil pipe 320, and the oil overflows into the return oil pipe 170 through the side open flow hole 220.

[0046] Furthermore, when the first valve core 181 is lifted to the middle of the first oil chamber 183, there is no circulation between the third oil pipe 340 and the oil inlet pipe 150. At this time, the oil spreads to the lower side of the pilot valve body 190 and the side of the second valve body 200 through the cross oil pipe 310. If the oil is greater than the set pressure of the pilot valve body 190, the pilot valve core 191 moves, and the oil can flow into the oil outlet pipe 160 through the side open flow hole 220. If the oil pressure is greater than the set pressure of the second valve body 200, the oil can directly push the second valve core 210, so that the oil in the cross oil pipe 310 can directly flow into the second oil pipe 330 and overflow from the return oil pipe 170, which can cope with hydraulic pressures under different pressure conditions and make the hydraulic system more stable.

[0047] In this embodiment, on the basis of limiting the oil entering the valve by the pressure reducing plate assembly 250, the hydraulic pressure of various pressure conditions can also be handled, so that the hydraulic system is more stable.

[0048] Example 3

[0049] This embodiment is intended to promote the solution of the problem that the hydraulic system needs to maintain hydraulic stability when facing different pressures. This embodiment is an improvement made on the basis of embodiment 1. The difference from embodiment 2 is that Fig. 9 When the oil pressure of the oil inlet 120 lifts the first valve core 181 to the uppermost end of the first oil chamber 183, the first valve core 181 drives the movable valve plate 251 with holes to move upward through the connecting rod 253, and the overlapping area of ​​the through hole of the movable valve plate 251 with holes and the through hole of the fixed valve plate 252 with holes is reduced and minimized. At this time, the pipe mouth of the third oil pipe 340 is connected with the first oil chamber 183, and the oil in the first oil chamber 183 directly overflows into the return oil pipe 170 through the third oil pipe 340. At the same time, excess oil can also enter the cross oil pipe 310, the pilot valve core 191 moves, and the oil enters the pilot overflow port 196 and the first oil pipe 320, and the oil overflows into the return oil pipe 170 through the side open flow hole 220.

[0050] In this embodiment: through the cooperation between the first valve body 180, the pilot valve body 191 and the second valve body 200, multi-level overflow can be achieved in proportion. On the basis of the restriction of the oil entering the valve by the pressure reducing plate assembly 250, in the face of different hydraulic conditions, the overflow activity opened inside the overflow valve is different, and the overflow effect achieved is different, so that the hydraulic pressure and the overflow correspond in proportion, thereby maintaining the stability of the oil output hydraulic pressure, and then maintaining the stability of the hydraulic system.

[0051] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A proportional air hole relief valve, comprising a machine box (110), wherein the side of the machine box (110) is connected with an oil inlet (120), an oil outlet (130) and an oil return port (140), wherein a pilot valve body (190) for adjusting the relief pressure and a first valve body (180) for achieving relief are installed on the side of the machine box (110), wherein the oil inlet (120), the oil outlet (130) and the oil return port (140) are all connected with the first valve body (180) and the pilot valve body (190), and wherein: Also includes: A pressure reducing plate assembly (250) for adjusting the instantaneous oil pressure of the oil inlet (120); the pressure reducing plate assembly (250) is arranged on a connecting pipe between the oil inlet (120) and the oil outlet (130); the pressure reducing plate assembly (250) comprises a fixed valve plate with a hole (252), and a movable valve plate with a hole (251) slidably attached to a side of the fixed valve plate with a hole (252); a connecting rod (253) is connected between the movable valve plate with a hole (251) and a first valve core (181) of the first valve body (180); A cross oil pipe (310) is connected to the side of the first valve body (180), the upper end of the cross oil pipe (310) is connected to the pilot valve body (190), the left end of the cross oil pipe (310) is connected to the second valve body (200), the right end of the cross oil pipe (310) is connected to the oil outlet (130), a first oil pipe (320) is connected between the second valve body (200) and the pilot valve body (190), a second oil pipe (330) is connected between the second valve body (200) and the oil return port (140), a third oil pipe (340) is connected between the second valve body (200) and the first valve body (180), and the oil inlet (120) is connected to the second valve body (200). The oil return port (140) is connected in series with the first valve body (180), the pilot valve body (190), the second valve body (200) and the oil return port (140); an oil inlet pipe (150) is connected between the oil inlet port (120) and the first valve body (180); an oil outlet pipe (160) is connected between the oil outlet port (130) and the oil inlet pipe (150); an oil return pipe (170) is installed on the inner side of the oil return port (140); and the diameters of the cross oil pipe (310), the first oil pipe (320), the second oil pipe (330) and the third oil pipe (340) are smaller than the diameters of the oil inlet pipe (150), the oil outlet pipe (160) and the oil return pipe (170).

2. A proportional air hole relief valve according to claim 1, characterized in that: The fixed valve plate with holes (252) is configured as a fixed plate with a through hole in the middle, and the movable valve plate with holes (251) is configured as a sliding plate with a through hole in the middle as well, and the through holes of the fixed valve plate with holes (252) and the movable valve plate with holes (251) are kept overlapping.

3. A proportional air hole relief valve according to claim 1, characterized in that: The second valve body (200) includes a second oil chamber (260) arranged inside the machine box (110), a second valve core (210) slidably installed inside the second oil chamber (260), a second spring (230) abutting against the rear side of the second valve core (210), and a regulating valve block (240) abutting against the rear side of the second spring (230) and capable of adjusting the pressure, wherein the regulating valve block (240) is configured as a block having bolts on the rear side.

4. A proportional air hole relief valve according to claim 3, characterized in that: The second valve core (210) is configured as a hollow block that is slidably fitted with the end of the second oil chamber (260), and a plurality of side open circulation holes (220) are distributed on the side wall of the second valve core (210), and the liquid in the first oil pipe (320) flows into the second oil pipe (330) through the side open circulation holes (220).

5. A proportional air hole relief valve according to claim 4, characterized in that: The first valve body (180) comprises a first oil chamber (183) provided inside the machine box (110), the first valve core (181) slidably installed inside the first oil chamber (183), and a first spring (182) connected between the first valve core (181) and the top wall of the first oil chamber (183), wherein the first spring (182) is located in the opposite direction of the oil inlet pipe (150). The pilot valve body (190) comprises a pilot oil chamber (195) provided inside the machine box (110), a first valve core (181) slidably installed inside the first oil chamber (183), and a first spring (182) connected between the first valve core (181) and the top wall of the first oil chamber (183). A pilot valve core (191) is installed in the pilot oil chamber (195), an adjustment spring (193) abutting against the back side of the pilot valve core (191), an adjustment rod (192) abutting against the rear side of the adjustment spring (193) and capable of adjusting the pressure, a pilot overflow port (196) connected to the pilot oil chamber (195), and a pilot sealing valve port (194) engaged with the pilot valve core (191), wherein the pilot sealing valve port (194) is located between the pilot valve core (191) and the pilot overflow port (196).

6. A proportional air hole relief valve according to claim 5, characterized in that: When the oil pressure at the oil inlet (120) is normal, the first valve core (181) is located at the bottom of the first oil chamber (183), the pipe opening of the third oil pipe (340) is blocked by the first valve core (181), the through hole of the fixed valve plate with a hole (252) overlaps and is aligned with the through hole of the movable valve plate with a hole (251), and the liquid in the oil inlet pipe (150) directly enters the oil outlet pipe (160).

7. A proportional air hole relief valve according to claim 5, characterized in that: When the oil pressure of the oil inlet (120) lifts the first valve core (181) to the middle of the first oil chamber (183), the first valve core (181) drives the movable valve plate with holes (251) to move upward through the connecting rod (253), and the overlapping area of ​​the through hole of the movable valve plate with holes (251) and the through hole of the fixed valve plate with holes (252) is reduced, thereby achieving oil quantity limitation.

8. A proportional air hole relief valve according to claim 5, characterized in that: When the oil pressure reaching the oil outlet pipe (160) is still greater than the oil pressure of the required outlet, the oil in the oil outlet pipe (160) extends upward to the cross oil pipe (310), the oil at the left end of the cross oil pipe (310) is blocked by the second valve core (210), the oil at the lower end of the cross oil pipe (310) is blocked by the first valve core (181), the oil at the upper end of the cross oil pipe (310) enters the pilot valve body (190), the pilot valve core (191) moves, the oil enters the pilot overflow port (196) and the first oil pipe (320), and the oil overflows into the return oil pipe (170) through the side open flow hole (220).

9. A proportional air hole relief valve according to claim 5, characterized in that: When the oil pressure of the oil inlet (120) lifts the first valve core (181) to the uppermost end of the first oil chamber (183), the first valve core (181) drives the movable valve plate (251) with a hole to move upward through the connecting rod (253), and the overlapping area of ​​the through hole of the movable valve plate (251) with a hole and the through hole of the fixed valve plate (252) with a hole is reduced to a minimum, and the pipe mouth of the third oil pipe (340) is connected to the first oil chamber (183), and the oil in the first oil chamber (183) directly enters the oil return pipe (170) through the third oil pipe (340) and overflows.

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