Overflow valve

Abstract

The utility model relates to the technical field of pressure control, in particular to an overflow valve. The overflow valve comprises a shell, a pilot valve assembly and a first adjusting part, the pilot valve assembly comprises a pilot valve element and a push rod, the push rod abuts against the pilot valve element, the pilot valve element is spherical, the push rod can abut against the first adjusting part, and the first adjusting part is movably arranged in the shell so that the push rod can push the pilot valve element to move in the left-right direction. The first adjusting piece pushes the pilot valve element to move in the left-right direction, so that the maximum stroke of the pilot valve element relative to the pilot valve seat is adjusted, the maximum working pressure, needing to be adjusted, of an oil way is flexibly adjusted, and universality is good; the pilot valve element is arranged to be spherical, the push rod can be simply ground, and the machining difficulty and the machining cost of the pilot valve assembly are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of pressure control, in particular to a relief valve. Background Art

[0002] Overflow valves are widely used in hydraulic system control circuits and are commonly used pressure control components in hydraulic systems. They adjust the system working pressure or limit its maximum working pressure through the overflow of the valve port, prevent system overload, and ensure the safety of the hydraulic system.

[0003] The pilot spool of existing relief valves typically features a sliding cone structure. This structure places high demands on the concentricity and roundness of the guide outer circle and the sealing cone. This structure is prone to sharp corner chipping during machining, making grinding difficult. Exceeding these tolerances and chipping defects can even lead to pilot valve seal failure, resulting in an inability to effectively build pressure and, consequently, poor performance.

[0004] In addition, the maximum stroke of the pilot valve core of the existing relief valve is fixed, so the maximum working pressure of the oil circuit that can be limited is constant. When the maximum working pressure of the oil circuit needs to be adjusted, the relief valve of different specifications needs to be replaced, which is inconvenient to use and has poor versatility.

[0005] Therefore, there is an urgent need for a relief valve to solve the above problems. Utility Model Content

[0006] The purpose of the utility model is to provide a relief valve, which can be achieved by setting the pilot valve core to a spherical shape and simply grinding the push rod, thereby reducing the processing difficulty and processing cost of the pilot valve assembly; the stroke of the pilot valve core can be adjusted by the first adjusting member, thereby flexibly adjusting the maximum set working pressure of the relief valve, and the product has good versatility.

[0007] To achieve the above objectives, the following technical solutions are provided:

[0008] Relief valve, including:

[0009] case;

[0010] A pilot valve assembly, the pilot valve assembly comprising a pilot valve core and a push rod, the push rod abutting against the pilot valve core, and the pilot valve core is spherical;

[0011] The first adjusting member is abutted against by the push rod, and the first adjusting member is movably arranged in the housing so that the push rod pushes the pilot valve core to move in the left and right directions.

[0012] As a preferred solution, the first adjusting member is threadedly connected to the housing.

[0013] As a preferred solution, the first adjusting member is provided with a first limiting groove extending along the left-right direction, and the housing is provided with a first limiting portion, and the first limiting portion is located in the first limiting groove.

[0014] As a preferred solution, the overflow valve further includes:

[0015] The second adjusting member is sleeved in the first adjusting member and is threadedly connected to the first adjusting member. The pilot valve assembly also includes a pressure-adjusting spring. One end of the pressure-adjusting spring abuts against the second adjusting member, and the other end can abut against the push rod. The second adjusting member is movably arranged in the first adjusting member to adjust the elastic force of the pressure-adjusting spring.

[0016] As a preferred solution, the second adjusting member is provided with a second limiting groove extending in the left-right direction, the first adjusting member is provided with a second limiting portion, and the second limiting portion is located in the second limiting groove.

[0017] As a preferred solution, the relief valve further includes a main valve assembly, and the main valve assembly includes:

[0018] A main valve sleeve, the main valve sleeve having an oil inlet and an oil return port, the main valve sleeve and the pilot valve assembly together forming a first cavity;

[0019] The main valve core and the damping valve core, the main valve core is sleeved in the main valve sleeve, the damping valve core is sleeved in the main valve core, the main valve core and the damping valve core form an annular gap at the end near the oil inlet, a first damping hole is provided in the main valve core, the oil inlet, the annular gap and the first cavity are connected.

[0020] As a preferred solution, a throttling groove is provided at one end of the main valve core close to the oil inlet.

[0021] As a preferred solution, the main valve sleeve and the main valve core together form a second cavity, and the main valve core can move in the left and right directions to connect or disconnect the oil inlet and the oil return port with the second cavity.

[0022] As a preferred solution, the pilot valve assembly further includes a pilot valve seat, a channel is opened on the pilot valve seat, and the relief valve further includes:

[0023] The electromagnetic drive assembly is configured to drive the pilot valve core to abut against the pilot valve seat to block the channel.

[0024] As a preferred solution, an oil drain port is provided on the electromagnetic drive assembly, and the electromagnetic drive assembly and the pilot valve assembly together form a third cavity, and the third cavity is connected to the oil drain port. The pilot valve core can move in the left and right directions so that the first cavity can be connected or disconnected with the third cavity through the channel.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] The pilot valve core of the relief valve provided by the present invention is spherical, and the relief valve also includes a first adjusting member, which is movably arranged in a shell body, and the first adjusting member abuts against the moving iron. The first adjusting member moves in the left and right directions relative to the shell body to push the moving iron to move in the left and right directions, and then the push rod pushes the pilot valve core to move in the left and right directions, so as to adjust the maximum stroke of the pilot valve core relative to the pilot valve seat, and then flexibly adjust the maximum working pressure that needs to be adjusted in the oil circuit, and has good versatility; by setting the pilot valve core to a spherical shape, it can be achieved by simply grinding the push rod, thereby reducing the processing difficulty and processing cost of the pilot valve assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0028] Figure 1 A cross-sectional view of a relief valve provided in an embodiment of the present utility model;

[0029] Figure 2 A cross-sectional view of the main valve core, the damping valve core, and the main valve sleeve provided in an embodiment of the present utility model;

[0030] Figure 3 A schematic structural diagram of the main valve core provided in an embodiment of the present utility model;

[0031] Figure 4 This is a schematic structural diagram of the overflow valve provided in an embodiment of the present utility model.

[0032] Reference numerals:

[0033] 100. Overflow valve;

[0034] 10. Main valve assembly; 11. Main valve sleeve; 111. Oil inlet; 112. Oil return port; 113. First cavity; 114. Second cavity; 12. Main valve core; 121. Throttle groove; 122. Annular gap; 13. Damping valve core; 131. First damping orifice; 14. Return spring; 15. Damping gasket; 151. Second damping orifice;

[0035] 20. Pilot valve assembly; 21. Pilot valve seat; 211. Passage; 22. Pilot valve core; 23. Pressure regulating spring; 24. Push rod;

[0036] 30. Electromagnetic drive assembly; 31. Coil; 32. Moving iron; 33. Magnetic tube; 331. Oil drain port; 332. Third cavity;

[0037] 40. First adjusting member; 41. First limiting groove; 42. Second limiting portion; 43. First tool groove;

[0038] 50. Second adjusting member; 51. Second limiting groove; 52. Second tool groove;

[0039] 60. Seals;

[0040] 70. Housing; 71. First limiting portion;

[0041] 80. Gasket. DETAILED DESCRIPTION

[0042] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0043] In the description of this application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0044] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of this application, if the term "plurality" appears, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0045] In this application, unless otherwise specified or limited, the terms "mounted," "connected," "connected," "fixed," etc., should be interpreted broadly. For example, these terms may refer to fixed connections, removable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; and internal communication between two components or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of these terms in this application based on the specific circumstances.

[0046] In this application, unless otherwise expressly specified or limited, if a first feature is described as being "above" or "below" a second feature, or similar descriptions, this may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is described as being "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is described as being "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0047] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only embodiment.

[0048] An embodiment of the present application provides a relief valve that can be used to maintain pressure and provide back pressure in a hydraulic system to ensure the safety of the hydraulic system.

[0049] Specifically, if Figure 1 and Figure 2As shown, the relief valve 100 includes a main valve assembly 10, a pilot valve assembly 20 and an electromagnetic drive assembly 30 connected in sequence. The main valve assembly 10 includes a main valve sleeve 11, which has an oil inlet 111 and an oil return port 112. The main valve sleeve 11 and the pilot valve assembly 20 together form a first cavity 113. The main valve core 12 is sleeved in the main valve sleeve 11, and the damping valve core 13 is sleeved in the main valve core 12. The main valve core 12 and the damping valve core 13 form an annular gap 122 at the end near the oil inlet 111. A first damping hole 131 is provided in the damping valve core 13. The oil inlet 111, the annular gap 122 and the first cavity 113 are connected. The main valve core 12 can move in the left and right directions to connect or disconnect the oil inlet 111 and the oil return port 112.

[0050] It should be explained that the "left" and "right" mentioned in this embodiment are not the "left" and "right" in the actual application of the relief valve 100. They are only used for reference. Figure 1 The viewing orientation is only used to distinguish different features and cannot be used as a limitation to the technical solution of this application.

[0051] The main valve core 12 and the main valve sleeve 11 together form a second cavity 114 . When the main valve core 12 moves leftward, the oil inlet 111 , the second cavity 114 and the oil return port 112 are connected, and the oil circuit connected to the oil inlet 111 can be depressurized.

[0052] The main valve assembly 10 also includes a return spring 14, one end of the return spring 14 abuts against the main valve core 12, and the other end abuts against the pilot valve assembly 20. The return spring 14 applies spring force to the main valve core 12 to ensure the sealing effect of the main valve core 12. At the same time, the return spring 14 can also realize the reset of the main valve core 12 after overflow.

[0053] Optionally, the main valve assembly 10 further includes a damping washer 15, which is positioned between the return spring 14 and the pilot valve assembly 20. The damping washer 15 defines a second damping hole 151, which communicates with the first cavity 113 to reduce the impact of oil pressure on the pilot valve core 22. It should be noted that the second damping hole 151 is provided on the damping washer 15 rather than on the pilot valve seat 21 because the holes on the pilot valve seat 21 are already difficult to machine, and providing a second damping hole 151 with a smaller diameter on the pilot valve seat 21 would significantly increase the machining difficulty. Therefore, by providing the second damping hole 151 on the damping washer 15, the impact of oil pressure on the pilot valve core 22 is reduced, while also reducing the machining difficulty of the pilot valve seat 21.

[0054] Alternatively, as Figure 3As shown, a throttling groove 121 is provided at one end of the main valve core 12 close to the oil inlet 111. The throttling groove 121 ensures that when the main valve core 12 is opened, the opening area and the displacement are in a linear relationship, and the required proportional opening area curve can be obtained.

[0055] like Figure 1 As shown, the pilot valve assembly 20 includes a pilot valve seat 21 and a pilot valve core 22. The pilot valve core 22 is movably arranged in the pilot valve seat 21. The pilot valve seat 21 is connected to the main valve sleeve 11. A channel 211 is opened on the pilot valve seat 21. The channel 211 is connected to the first cavity 113. The pilot valve core 22 is blocked in the channel 211 so that the oil in the first cavity 113 can maintain a certain pressure.

[0056] A sealing member 60 is provided between the pilot valve seat 21 and the main valve sleeve 11 to improve the sealing performance of the first cavity 113. The sealing member 60 is an O-ring.

[0057] The relief valve 100 further includes an electromagnetic drive assembly 30 , and the pilot valve assembly 20 further includes a push rod 24 . The electromagnetic drive assembly 30 is configured to drive the pilot valve core 22 to abut against the pilot valve seat 21 to block the channel 211 .

[0058] The electromagnetic drive assembly 30 includes a coil 31, a magnetic tube 33, and a movable iron 32. The coil 31 is mounted on the outer periphery of the housing 70. One end of the magnetic tube 33 is mounted on the housing 70, and the other end of the magnetic tube 33 is mounted on the main valve housing 11. The movable iron 32 is movably mounted within the housing 70. One end of the push rod 24 is connected to the movable iron 32, and the other end is in contact with the pilot valve core 22. During operation, the coil 31 is energized. As the proportional current increases, the magnetic force generated by the magnetic tube 33 pushes the movable iron 32 to the left, inversely reducing the force exerted by the movable iron 32 on the push rod 24 and the pilot valve core 22, thereby reducing the relief pressure of the relief valve 100 and achieving inverse proportional pressure control. This allows for flexible adjustment of the opening pressure of the relief valve 100.

[0059] The magnetic tube 33, movable iron 32, and pilot valve seat 21 collectively form a third cavity 332. The channel 211 on the pilot valve seat 21 communicates with the third cavity 332. An oil drain port 331 is defined on the magnetic tube 33, communicating with the third cavity 332. When the pilot valve core 22 opens, oil in the first cavity 113 flows through the second damping orifice 151, the channel 211, and the third cavity 332, ultimately returning to the oil tank through the oil drain port 331.

[0060] The pilot valve core 22 of the existing relief valve 100 is usually a sliding cone structure. The valve core of the sliding cone structure has high requirements on the concentricity and roundness of the guide outer circle and the sealing cone surface. It is easy to produce problems such as sharp corners and cracks during the processing, and it is difficult to grind. Excessive shape and position tolerances and crack defects may even cause the pilot valve seal to fail, resulting in the product being unable to effectively build pressure, and then causing the product performance to fail. In addition, the maximum stroke of the pilot valve core 22 of the existing relief valve 100 is fixed, so the maximum working pressure of the oil circuit that can be limited is constant. When the maximum working pressure of the oil circuit needs to be adjusted, it is necessary to replace the relief valve 100 of different specifications, which is inconvenient to use and has poor versatility.

[0061] In order to solve the above problems, Figure 1 As shown, the pilot valve core 22 provided in this embodiment is spherical, and the relief valve 100 also includes a first adjusting member 40, which is movably arranged in the housing 70, and the first adjusting member 40 is in contact with the moving iron 32. The first adjusting member 40 moves in the left and right directions relative to the housing 70 to push the moving iron 32 to move in the left and right directions, and then the push rod 24 pushes the pilot valve core 22 to move in the left and right directions, so as to adjust the maximum stroke of the pilot valve core 22 relative to the pilot valve seat 21, and then flexibly adjust the size of the maximum working pressure that needs to be adjusted in the oil circuit, and has good versatility; by setting the pilot valve core 22 to a spherical shape, it can be achieved by simply grinding the push rod 24, thereby reducing the processing difficulty and processing cost of the pilot valve assembly 20.

[0062] Optionally, the first adjusting member 40 is threadedly connected to the shell 70, and the relative position of the first adjusting member 40 and the shell 70 can be adjusted by the extent to which the thread of the first adjusting member 40 is screwed into the shell 70. The adjustment method is simple and convenient for quickly adjusting the relative position of the first adjusting member 40 and the shell 70.

[0063] Alternatively, as Figure 4 As shown, the end of the first adjusting member 40 is provided with a first tool slot 43, which facilitates the insertion of an adjusting tool, thereby facilitating the use of the adjusting tool to adjust the position of the thread of the first adjusting member 40 screwed into the housing 70, saving manpower. Specifically, the adjusting tool can be a flat-blade screwdriver.

[0064] Optionally, a first limiting groove 41 extending in the left-right direction is provided on the first adjusting member 40, and a first limiting portion 71 is provided on the shell 70. The first limiting portion 71 is located in the first limiting groove 41, so that the first adjusting member 40 can be adjusted within the range of the first limiting groove 41.

[0065] Optionally, the relief valve 100 further includes a second adjusting member 50, which is sleeved within the first adjusting member 40 and threadedly connected to the first adjusting member 40. The pilot valve assembly 20 further includes a pressure-regulating spring 23, one end of the pressure-regulating spring 23 abutting the second adjusting member 50 and the other end abutting the movable iron 32. The second adjusting member 50 is movably disposed within the first adjusting member 40 to adjust the elastic force of the pressure-regulating spring 23, thereby adjusting the set pressure value of the relief valve 100. By threading the second adjusting member 50 with the first adjusting member 40, the relative position of the second adjusting member 50 to the first adjusting member 40 can be adjusted by adjusting the position of the second adjusting member 50 screwed into the thread of the first adjusting member 40. The adjustment method is simple and facilitates quick adjustment of the relative position of the second adjusting member 50 to the first adjusting member 40.

[0066] Alternatively, as Figure 4 As shown, a second tool groove 52 is provided at the end of the second adjusting member 50. The second tool groove 52 facilitates the insertion of the adjustment tool, thereby facilitating the use of the adjustment tool to adjust the position of the second adjusting member 50 screwed into the thread of the first adjusting member 40, saving manpower.

[0067] Optionally, a second limiting groove 51 extending in the left-right direction is provided on the second adjusting member 50, and a second limiting portion 42 is provided on the first adjusting member 40. The second limiting portion 42 is located in the second limiting groove 51, so that the first adjusting member 40 can be adjusted within the range of the first limiting groove 41.

[0068] Optionally, a sealing member 60 is provided between the first adjusting member 40 and the second adjusting member 50 ; and a sealing member 60 is provided between the first adjusting member 40 and the housing 70 to improve the overall sealing effect of the relief valve 100 .

[0069] A gasket 80 is provided between the moving iron 32 and the second adjusting member 50 . The gasket 80 deforms when under pressure and can absorb pressure shock.

[0070] For ease of understanding, combined Figure 1 and Figure 2 The working process of the relief valve 100 is described as follows:

[0071] Oil enters the relief valve 100 through the oil inlet 111, flows through the annular gap 122 into the damping orifice on the damping spool 13, and then into the chamber containing the return spring 14 (i.e., the first chamber 113). When the pressure in the first chamber 113 is lower than the set value of the pre-compression force of the pressure-regulating spring 23, the pilot valve spool 22 is closed. When the pressure in the first chamber 113 exceeds the preset pressure of the pressure-regulating spring 23, the pilot valve spool 22 moves leftward, and the oil flows through the second damping orifice 151 and the passage 211 into the third chamber 332, ultimately flowing back to the tank through the oil drain port 331. In the process of oil flowing from the first cavity 113 to the third cavity 332, due to the damping effect of the second damping hole 151, pressure loss occurs, so that the pressure of the third cavity 332 is lower than the pressure of the first cavity 113. The pressure difference between the two cavities overcomes the pre-compression force of the return spring 14, pushing the main valve core 12 to the left. At this time, the oil inlet 111, the second cavity 114 and the oil return port 112 are connected, and overflow occurs.

[0072] Note that throughout this specification, references to terms such as "some embodiments" and "other embodiments" indicate that the specific features, structures, materials, or characteristics described in conjunction with those embodiments or examples are included in at least one embodiment or example of the present invention. Throughout this specification, the schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be incorporated in any suitable manner in any one or more embodiments or examples.

[0073] The above are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions are readily apparent to those skilled in the art without departing from the scope of the present invention. Therefore, while the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include other equivalent embodiments without departing from the spirit of the present invention. The scope of the present invention is determined by the appended claims.

Claims

1. Overflow valve, characterized in that, include: Housing (70); A pilot valve assembly (20), the pilot valve assembly (20) comprising a pilot valve core (22) and a push rod (24), the push rod (24) abutting against the pilot valve core (22), and the pilot valve core (22) being spherical; A first adjusting member (40), the push rod (24) can abut against the first adjusting member (40), and the first adjusting member (40) is movably arranged in the housing (70) so that the push rod (24) pushes the pilot valve core (22) to move in the left and right directions.

2. The relief valve according to claim 1, characterized in that The first adjusting member (40) is threadedly connected to the housing (70).

3. The relief valve according to claim 1, characterized in that The first adjusting member (40) is provided with a first limiting groove (41) extending in the left-right direction, and the housing (70) is provided with a first limiting portion (71), and the first limiting portion (71) is located in the first limiting groove (41).

4. The relief valve according to claim 1, characterized in that The relief valve further comprises: The second adjusting member (50) is mounted inside the first adjusting member (40) and is threadedly connected to the first adjusting member (40). The pilot valve assembly (20) further includes a pressure-adjusting spring (23). One end of the pressure-adjusting spring (23) abuts against the second adjusting member (50), and the other end can abut against the push rod (24). The second adjusting member (50) is movably arranged inside the first adjusting member (40) to adjust the elastic force of the pressure-adjusting spring (23).

5. The relief valve according to claim 4, characterized in that: The second adjusting member (50) is provided with a second limiting groove (51) extending along the left-right direction, and the first adjusting member (40) is provided with a second limiting portion (42), and the second limiting portion (42) is located in the second limiting groove (51).

6. The relief valve according to any one of claims 1 to 5, characterized in that: The relief valve further comprises a main valve assembly (10), wherein the main valve assembly (10) comprises: A main valve sleeve (11), the main valve sleeve (11) having an oil inlet (111) and an oil return port (112), the main valve sleeve (11) and the pilot valve assembly (20) jointly forming a first cavity (113); A main valve core (12) and a damping valve core (13), wherein the main valve core (12) is sleeved in the main valve sleeve (11), and the damping valve core (13) is sleeved in the main valve core (12), and an annular gap (122) is formed at the end of the main valve core (12) and the damping valve core (13) near the oil inlet (111), and a first damping hole (131) is provided in the main valve core (12), and the oil inlet (111), the annular gap (122), and the first cavity (113) are connected.

7. The relief valve according to claim 6, characterized in that A throttling groove (121) is provided at one end of the main valve core (12) close to the oil inlet (111).

8. The relief valve according to claim 6, characterized in that The main valve sleeve (11) and the main valve core (12) together form a second cavity (114), and the main valve core (12) can move in the left and right directions to connect or disconnect the oil inlet (111) and the oil return port (112) with the second cavity (114).

9. The relief valve according to claim 8, characterized in that The pilot valve assembly (20) further includes a pilot valve seat (21), wherein a channel (211) is formed on the pilot valve seat (21), and the relief valve further includes: An electromagnetic drive assembly (30) is configured to drive the pilot valve core (22) to abut against the pilot valve seat (21) to block the channel (211).

10. The relief valve according to claim 9, characterized in that The electromagnetic drive assembly (30) is provided with an oil drain port (331). The electromagnetic drive assembly (30) and the pilot valve assembly (20) together form a third cavity (332). The third cavity (332) is connected to the oil drain port (331). The pilot valve core (22) can move in a left-right direction so that the first cavity (113) can be connected to or disconnected from the third cavity (332) through the channel (211).

Images