Pilot valve and electromagnetic valve

Abstract

The utility model relates to the technical field of electromagnetic valves, and particularly discloses a pilot valve and an electromagnetic valve, and the pilot valve comprises a pilot valve seat and a pilot valve core. The pilot valve seat is provided with a first cavity and a second cavity which are communicated with each other, the diameter of the first cavity is smaller than that of the second cavity, and one end of the pilot valve element extends into the first cavity, so that one end of the pilot valve element can be matched with the inner wall of the first cavity in a limiting mode in the radial direction of the pilot valve element. Therefore, the guide effect on the movement of the pilot valve core can be achieved; meanwhile, the other end of the pilot valve element can be matched with the inner wall of the main valve sleeve in a limiting mode in the radial direction of the pilot valve element, the guide effect on movement of the pilot valve element can also be achieved, in this way, the guide effect on the pilot valve element can be achieved through the inner wall of the first cavity and the inner wall of the main valve sleeve, and the phenomenon of clamping stagnation of the pilot valve element is avoided; moreover, the pilot valve provided by the utility model can reduce the size precision requirement during production and processing, and reduces the production cost.

Description

Technical Field

[0001] The utility model relates to the technical field of solenoid valves, in particular to a pilot valve and a solenoid valve. Background Art

[0002] At present, variable damping shock absorbers are mainly realized by magnetorheological, solenoid valve, stepper motor and other methods. Among them, the solenoid valve type is widely used due to its reliable performance, low cost, quick response, compact structure and other advantages. The solenoid valve type shock absorber mainly adjusts the damping of the shock absorber by controlling the size of the inlet and outlet of the pilot valve. The pilot valve is usually composed of a pilot valve seat and a pilot valve core. In the prior art, when the pilot valve core moves axially, it only guides the pilot valve core through the pilot valve seat. Such a setting will cause the pilot valve core to get stuck when moving, affecting the normal operation of the pilot valve. Utility Model Content

[0003] The utility model aims to provide a pilot valve and a solenoid valve to solve the problem in the prior art that the pilot valve core is prone to get stuck when moving.

[0004] On the one hand, the utility model provides a pilot valve, which can be arranged in the main valve sleeve of the solenoid valve, including: a pilot valve seat, which can be fixedly arranged in the main valve sleeve, the pilot valve seat having a first cavity, a second cavity and a flow hole, the first cavity and the second cavity are connected, the flow hole is used to connect the inner cavity of the main valve sleeve with the second cavity, the diameter of the first cavity is smaller than the diameter of the second cavity; a pilot valve core, which has a center hole extending along its axial direction and a connecting hole connected to the center hole, one end of the pilot valve core is slidably arranged in the first cavity, and cooperates with the inner wall of the first cavity at the radial upper limit position of the pilot valve core, the other end of the pilot valve core can be slidably arranged in the cavity of the main valve sleeve, and cooperates with the inner wall of the main valve sleeve at the radial upper limit position of the pilot valve core, the pilot valve core can slide relative to the pilot valve seat to change the flow area of ​​oil flowing into the center hole from the second cavity through the connecting hole.

[0005] As an optional technical solution for the pilot valve, the pilot valve core includes a first rod segment, a second rod segment and a third rod segment connected in sequence, the diameter of the first rod segment is smaller than the diameter of the second rod segment, the diameter of the second rod segment is smaller than the diameter of the third rod segment, a portion of the first rod segment extends into the first cavity, and cooperates with the inner wall of the first cavity at the radial upper limit position of the pilot valve core, the second rod segment and the third rod segment are both located outside the pilot valve seat, the end face of the second rod segment facing the first rod segment can abut the end face of the pilot valve seat to seal the second cavity, and the third rod segment is used to cooperate with the inner wall of the main valve sleeve at the radial upper limit position of the pilot valve core.

[0006] As an optional technical solution for the pilot valve, the third rod segment includes a bottom plate and a limiting side plate, the bottom plate is connected to the second rod segment, the limiting side plate is connected to the bottom plate, and the outer wall of the limiting side plate and the inner wall of the main valve sleeve are limitedly matched.

[0007] As an optional technical solution for the pilot valve, the bottom plate has a plurality of bottom holes distributed at intervals along the circumference of the pilot valve core.

[0008] As an optional technical solution for the pilot valve, there are multiple communicating holes, and the multiple communicating holes are distributed at intervals along the circumference of the central hole.

[0009] As an optional technical solution for the pilot valve, there are multiple flow holes, the multiple flow holes are distributed at intervals along the circumference of the pilot valve core, and the multiple flow holes are all connected to the second cavity.

[0010] As an optional technical solution of the pilot valve, the pilot valve further includes a first elastic member, and the first elastic member is arranged between the pilot valve seat and the pilot valve core.

[0011] On the other hand, the utility model provides a solenoid valve, comprising a main valve sleeve, a main valve core, an electromagnetic drive unit and a pilot valve of any of the above items, the main valve core is arranged in the cavity of the main valve sleeve, and the cavity of the main valve sleeve is divided into a main valve cavity and a pilot cavity, the pilot cavity is connected with the second cavity through a flow hole, the side wall of the main valve sleeve has a side oil hole, the side oil hole can discharge the oil in the main valve cavity, the main valve sleeve is installed on the electromagnetic drive unit, and the electromagnetic drive unit is used to drive the pilot valve core to move along its axial direction.

[0012] As an optional technical solution of the solenoid valve, the solenoid valve further includes a second elastic member, and the second elastic member is arranged between the main valve core and the pilot valve seat.

[0013] As an optional technical solution for the solenoid valve, the electromagnetic drive unit also includes a fixed seat, a guide rod and an electromagnetic assembly. A part of the main valve sleeve, the fixed seat and the guide rod are all arranged in the electromagnetic assembly. The guide rod is inserted into the fixed seat. The fixed seat can abut against the pilot valve core. The electromagnetic assembly can drive the guide rod to move so that the guide rod drives the pilot valve core to move.

[0014] The beneficial effects of the utility model are:

[0015] The utility model provides a pilot valve, which includes a pilot valve seat and a pilot valve core. The pilot valve seat has a first cavity and a second cavity that are interconnected, and the diameter of the first cavity is smaller than the diameter of the second cavity. One end of the pilot valve core is extended into the first cavity, so that one end of the pilot valve core can cooperate with the inner wall of the first cavity at the radial upper limit of the pilot valve core, thereby guiding the movement of the pilot valve core; at the same time, the other end of the pilot valve core can cooperate with the inner wall of the main valve sleeve at the radial upper limit of the pilot valve core, and also can guide the movement of the pilot valve core. In this way, when the pilot valve core moves along its axial direction, the inner wall of the first cavity and the inner wall of the main valve sleeve can both guide the pilot valve core, avoid the phenomenon of the pilot valve core being stuck, and ensure the normal operation of the pilot valve; and the pilot valve provided by the utility model can reduce the dimensional accuracy requirements and reduce the production cost during production and processing. Among them, since the pilot valve core can slide relative to the pilot valve seat, this arrangement can change the flow area of ​​the oil flowing into the center hole through the connecting hole in the second cavity by adjusting the distance between the pilot valve core and the pilot valve seat, thereby causing changes in the oil flow path and the oil pressure, making it easier to control the oil pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A cross-sectional view of a solenoid valve in an embodiment of the utility model;

[0017] Figure 2 It is a cross-sectional view of the structure of the solenoid valve in the embodiment of the utility model;

[0018] Figure 3 It is a structural schematic diagram of the pilot valve seat, the main valve sleeve and the pilot valve core in the embodiment of the utility model.

[0019] In the figure:

[0020] 1. pilot valve seat; 11. first cavity; 12. second cavity; 13. flow hole;

[0021] 2. pilot valve core; 21. first rod section; 22. second rod section; 23. third rod section; 231. bottom plate; 2311. bottom hole; 232. limit side plate; 24. center hole; 25. connecting hole;

[0022] 3. Main valve sleeve; 31. Side oil hole; 32. Oil outlet hole;

[0023] 4. Main valve core;

[0024] 5. Electromagnetic drive unit; 51. Fixed seat; 52. Guide rod; 53. Armature; 54. Magnetic core tube;

[0025] 6. A second elastic member;

[0026] 7. A first elastic member. DETAILED DESCRIPTION

[0027] The technical solution of the utility model will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, 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 cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0031] like Figures 1 to 3As shown, this embodiment provides a pilot valve, which includes a pilot valve seat 1 and a pilot valve core 2. The pilot valve seat 1 has a first cavity 11 and a second cavity 12 that are interconnected, and the diameter of the first cavity 11 is set to be smaller than the diameter of the second cavity 12. In this way, one end of the pilot valve core 2 can be extended into the first cavity 11, so that one end of the pilot valve core 2 can cooperate with the inner wall of the first cavity 11 at the radial upper limit of the pilot valve core 2, and the pilot valve core 2 can move along its axial direction in the first cavity 11, thereby guiding the movement of the pilot valve core 2; at the same time, the other end of the pilot valve core 2 can cooperate with the inner wall of the main valve sleeve 3 at the radial upper limit of the pilot valve core 2. The radial upper limit of the pilot valve core 2 can also guide the movement of the pilot valve core 2. With this arrangement, when the pilot valve core 2 moves along its axial direction, the inner wall of the first cavity 11 and the inner wall of the main valve sleeve 3 can guide the pilot valve core 2, avoiding the pilot valve core 2 from getting stuck, and ensuring the normal operation of the pilot valve; and the pilot valve provided by the utility model can reduce the dimensional accuracy requirements and production costs during production and processing, effectively solving the problem of the pilot valve core 2 being easily stuck when moving in the prior art. Among them, since the pilot valve core 2 can slide relative to the pilot valve seat 1, such an arrangement can change the flow area of ​​the oil flowing from the second cavity 12 into the center hole 24 through the connecting hole 25 by the size of the distance between the pilot valve core 2 and the pilot valve seat 1, thereby causing the oil flow path to change and the oil pressure to change, which is convenient for regulating the oil pressure.

[0032] In this embodiment, a plurality of flow holes 13 are provided, and the plurality of flow holes 13 are spaced apart and distributed along the circumferential direction of the pilot valve core 2, so that the flow rate of the pilot valve can be increased.

[0033] Specifically, the pilot valve core 2 includes a first rod segment 21, a second rod segment 22, and a third rod segment 23 connected in sequence. Since the diameter of the first rod segment 21 is set to be smaller than the diameter of the second rod segment 22, and the diameter of the second rod segment 22 is set to be smaller than the diameter of the third rod segment 23, in this way, a part of the first rod segment 21 can be extended into the first cavity 11, so as to achieve the purpose of cooperating with the inner wall of the first cavity 11 at the radial upper limit position of the pilot valve core 2, and then the inner wall of the first cavity 11 can guide the first rod segment 21; similarly, since the third rod segment 23 is located in the cavity of the main valve sleeve 3, the third rod segment 23 can cooperate with the inner wall of the main valve sleeve 3 at the radial upper limit position of the pilot valve core 2, so as to guide the third rod segment 23. Among them, a second rod section 22 is set, and when the pilot valve core 2 moves along its axial direction, it can achieve the purpose of increasing or decreasing the flow area of ​​oil flowing from the second cavity 12 into the cavity of the main valve sleeve 3, thereby changing the flow path of the oil and the internal pressure of the oil, and achieving the purpose of oil pressure regulation.

[0034] Optionally, the pilot valve seat 1 has a valve port connected to the second cavity 12. Since the diameter of the first rod segment 21 is set to be smaller than the diameter of the second rod segment 22, the end surface of the second rod segment 22 facing the first rod segment 21 can abut against the end surface of the pilot valve seat 1. In this way, when the pilot valve core 2 moves, the flow area of ​​the oil flowing from the second cavity 12 into the cavity of the main valve sleeve 3 is increased or reduced. Among them, the end surface of the pilot valve seat 1 refers to the end surface facing the third rod segment 23.

[0035] like Figure 1 and Figure 2 As shown, in this embodiment, the third rod segment 23 includes a bottom plate 231 and a limiting side plate 232. The bottom plate 231 is connected to the second rod segment 22, and the limiting side plate 232 can be vertically connected to the bottom plate 231, wherein the limiting side plate 232 is arranged toward the first rod segment 21; the limiting side plate 232 is arranged to facilitate the limiting cooperation with the inner wall of the main valve sleeve 3, thereby achieving the purpose of guiding the third rod segment 23. The bottom plate 231 is circular in shape, and the limiting side plate 232 is cylindrical in shape.

[0036] Furthermore, the bottom plate 231 is provided with a plurality of bottom holes 2311 spaced apart along the circumference of the pilot valve core 2. In this way, the bottom holes 2311 can connect the cavity formed between the pilot valve core 2 and the inner cavity of the main valve sleeve 3 with the valve port of the main valve sleeve 3 away from the pilot valve seat 1.

[0037] Specifically, the pilot valve core 2 has a central hole 24 extending along its axial direction and a connecting hole 25 connected to the central hole 24. The connecting hole 25 can connect the central hole 24 with the second cavity 12, and can also facilitate the precise control of the oil and improve the control accuracy of the pilot valve. At the same time, when the pilot valve core 2 moves in its axial direction, the inner wall of the first cavity 11 can block part of the connecting hole 25, so that the oil can be further precisely controlled.

[0038] It should be noted that: when there is no current, the pilot valve core 2 is in contact with the fixed seat 51, and the oil inside the cavity of the main valve sleeve 3 flows into the interior of the pilot valve seat 1 through the side oil hole 31 of the pilot valve seat 1. At this time, the oil is divided into two parts. One part flows into the cavity formed by the pilot valve core 2 and the main valve sleeve 3 through the end valve ports of the pilot valve core 2 and the pilot valve seat 1, and then flows out through the bottom hole 2311 of the pilot valve core 2; the other part flows into the electromagnetic drive part 5 through the connecting hole 25 and the center hole 24 of the pilot valve core 2. At this time, due to the absence of electromagnetic force, the first elastic member 7 mainly acts on the pilot valve core 2, so that the pilot valve core 2 is in contact with the fixed seat 51, and the connecting hole 25 of the pilot valve core 2 is opened to the maximum. When current is present, as the pilot valve core 2 moves toward the pilot valve seat 1, the flow area of ​​the connecting hole 25 of the pilot valve core 2 changes, causing the oil flow path and the internal pressure of the oil to change, thereby realizing the regulation of the oil pressure to achieve precise control of the oil.

[0039] The communicating holes 25 may be arranged in a plurality, and the plurality of communicating holes 25 are spaced and distributed along the circumference of the central hole 24. Such an arrangement can ensure the flow rate of oil from the communicating holes 25 into the central hole 24.

[0040] Specifically, the pilot valve further comprises a first elastic member 7 . The first elastic member 7 is arranged between the pilot valve seat 1 and the pilot valve core 2 , so that the pilot valve core 2 always has a movement tendency away from the pilot valve seat 1 through the elastic force of the first elastic member 7 .

[0041] The first elastic member 7 includes but is not limited to a spring.

[0042] This embodiment also provides a solenoid valve, including a main valve sleeve 3, a main valve core 4, an electromagnetic drive unit 5 and the pilot valve in the above scheme. The solenoid valve also includes a main valve seat installed on the main valve sleeve 3; the electromagnetic drive unit 5 includes a fixed seat 51, a guide rod 52, an armature 53, a magnetic core tube 54 and an electromagnetic coil. The main valve sleeve 3 is installed on the magnetic core tube 54, and an oil outlet 32 ​​is formed between the main valve sleeve 3 and the magnetic core tube 54. The bottom hole 2311 and the center hole 24 are both connected to the oil outlet 32. The fixed seat 51 is installed in the cavity of the magnetic core tube 54, the guide rod 52 is penetrated on the fixed seat 51, and can abut against the pilot valve core 2. The guide rod 52 has a guide hole connected to the center hole 24. The armature 53 is sleeved on the guide rod 52. The electromagnetic coil is installed on the magnetic core tube 54. After the electromagnetic coil is energized, the armature 53 is used to drive the guide rod 52 to move along its axial direction, thereby driving the pilot valve core 2 to move.

[0043] The main valve core 4 is arranged in the cavity of the main valve sleeve 3, and the side wall of the main valve sleeve 3 has a side oil hole 31. The oil entering through the main valve seat can be discharged from the side oil hole 31. The main valve sleeve 3 is installed on the electromagnetic drive unit 5, and the electromagnetic drive unit 5 is used to drive the pilot valve core 2 to move along its axial direction. Specifically, the solenoid valve also includes a second elastic member 6, which is arranged between the main valve core 4 and the pilot valve seat 1. The second elastic member 6 includes but is not limited to a spring.

[0044] Optionally, the solenoid valve further comprises a spring sheet, which is arranged between the second elastic member 6 and the pilot valve seat 1. Such arrangement is mainly to provide elasticity for the second elastic member 6.

[0045] The working principle of the solenoid valve provided by the utility model is as follows:

[0046] The oil passes through the main valve seat and the through hole in the center of the main valve core 4, then enters the cavity formed by the main valve core 4 and the main valve sleeve 3 and then flows into the pilot valve seat 1. The outside of the pilot valve seat 1 has a flow hole 13. A part of the oil passes through the connecting hole 25 of the pilot valve core 2, flows through the center hole 24 (the flow area changes with the movement of the pilot valve core 2) and enters the electromagnetic drive unit 5. The other part of the oil overcomes the spring force of the first elastic member 7 and the electromagnetic force transmitted by the guide rod 52, thereby opening the valve port of the pilot valve seat 1 toward the third rod segment 23, passes through the bottom hole 2311 of the pilot valve core 2, and flows to the cavity formed by the fixed seat 51. Finally, the oil flows to the oil outlet hole 32, thereby achieving the purpose of pressure relief outside the solenoid valve.

[0047] The oil flow and force analysis of the solenoid valve provided by the utility model under different currents:

[0048] When a fixed flow rate L is input to the inlet of the solenoid valve, the main valve core opens and is in a certain equilibrium position: at this time, the force analysis of the main valve core is performed: P1*S1+P2*S2+P3*S3=P4*S4+F, where P3 can change with the change of electromagnetic force: when the electromagnetic coil is not energized, since the gap between the pilot valve core and the main valve sleeve is fixed, P4 does not change; when a 0.3A current is passed through the electromagnetic coil, the armature drives the guide rod to move toward the main valve sleeve under the action of the electromagnetic force, and pushes the pilot valve core to move toward the main valve sleeve, the pilot valve core is separated from the fixed seat, and the oil flow area of ​​the pilot channel increases. P4The main valve core moves toward the fixed seat, P1 decreases accordingly, and the damping force of the shock absorber decreases; when the electromagnetic coil current continues to increase and is no more than 0.6A, the pilot valve core continues to move toward the main valve sleeve, the gap between the pilot valve core and the inner step of the pilot valve seat becomes smaller, the flow area of ​​the pilot channel decreases, P4 increases, the main valve core moves away from the fixed seat, P1 also increases accordingly, and the damping force of the shock absorber increases; when the electromagnetic coil current continues to increase to 0.7A, the pilot valve core continues to move toward the main valve sleeve, the end face of its second rod section contacts the end face of the inner step of the pilot valve seat, the pilot channel is closed, and P4 increases , the main valve core moves away from the fixed seat, P1 also increases, and the damping force of the shock absorber increases; if there is no flow input at this time, the input flow rate changes continuously from 0 to 40L / min, the pilot valve core opens, and the main valve core can open. Before the two are opened, since the oil does not flow, P1=P2=P4. After P1 rises to a certain pressure (referred to as valve opening pressure), the pilot valve core and the main valve core can open. The larger the current, the tighter the pilot valve core fits the pilot valve seat at the beginning, and the greater the required valve opening pressure; 0A (no power) and 0.3A-0.6A are both throttling control; 0.7A-1.6A is pressure control.

[0049] Among them, P1: main valve seat inlet pressure; P2: main valve seat and main valve core annular chamber pressure; P3: main valve seat, main valve core, main valve sleeve enclosed annular chamber pressure; P4: main valve core chamber pressure; S1: main valve seat inner ring area; S2: main valve seat and main valve core annular chamber area; S3: main valve seat, main valve core, main valve sleeve enclosed annular chamber area; S4: main valve core outer circle area; F: second elastic part and special-shaped spring preload.

[0050] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A pilot valve, which can be arranged in a main valve sleeve (3) of a solenoid valve, characterized in that: include: A pilot valve seat (1) can be fixedly arranged in the main valve sleeve (3), the pilot valve seat (1) having a first cavity (11), a second cavity (12) and a flow hole (13), the first cavity (11) and the second cavity (12) being connected, the flow hole (13) being used to connect the inner cavity of the main valve sleeve (3) and the second cavity (12), the diameter of the first cavity (11) being smaller than the diameter of the second cavity (12); The pilot valve core (2) has a center hole (24) extending axially therethrough and a connecting hole (25) connected to the center hole (24). One end of the pilot valve core (2) is slidably disposed in the first cavity (11) and cooperates with the inner wall of the first cavity (11) at the radial upper limit position of the pilot valve core (2). The other end of the pilot valve core (2) can be slidably disposed in the cavity of the main valve sleeve (3) and cooperates with the inner wall of the main valve sleeve (3) at the radial upper limit position of the pilot valve core (2). The pilot valve core (2) can slide relative to the pilot valve seat (1) to change the flow area of ​​oil flowing from the second cavity (12) into the center hole (24) through the connecting hole (25).

2. The pilot valve according to claim 1, characterized in that: The pilot valve core (2) comprises a first rod segment (21), a second rod segment (22) and a third rod segment (23) which are connected in sequence. The diameter of the first rod segment (21) is smaller than the diameter of the second rod segment (22), and the diameter of the second rod segment (22) is smaller than the diameter of the third rod segment (23). A portion of the first rod segment (21) extends into the first cavity (11) and cooperates with the inner wall of the first cavity (11) at the radial upper limit position of the pilot valve core (2). The second rod segment (22) and the third rod segment (23) are both located outside the pilot valve seat (1). The end surface of the second rod segment (22) facing the first rod segment (21) can abut against the end surface of the pilot valve seat (1) to block the second cavity (12). The third rod segment (23) is used to cooperate with the inner wall of the main valve sleeve (3) at the radial upper limit position of the pilot valve core (2).

3. The pilot valve according to claim 2, characterized in that: The third rod section (23) comprises a bottom plate (231) and a limiting side plate (232); the bottom plate (231) is connected to the second rod section (22); the limiting side plate (232) is connected to the bottom plate (231); and the outer wall of the limiting side plate (232) is limitedly matched with the inner wall of the main valve sleeve (3).

4. The pilot valve according to claim 3, characterized in that: The bottom plate (231) has a plurality of bottom holes (2311) distributed at intervals along the circumference of the pilot valve core (2).

5. The pilot valve according to claim 1, characterized in that: There are a plurality of communicating holes (25), and the plurality of communicating holes (25) are distributed at intervals along the circumference of the central hole (24).

6. The pilot valve according to claim 1, characterized in that: There are a plurality of the flow holes (13), and the plurality of the flow holes (13) are distributed at intervals along the circumference of the pilot valve core (2), and the plurality of the flow holes (13) are all in communication with the second cavity (12).

7. The pilot valve according to any one of claims 1 to 6, characterized in that: The pilot valve further comprises a first elastic member (7), wherein the first elastic member (7) is arranged between the pilot valve seat (1) and the pilot valve core (2).

8. A solenoid valve, characterized in that: It comprises a main valve sleeve (3), a main valve core (4), an electromagnetic drive unit (5) and a pilot valve as claimed in any one of claims 1 to 7, wherein the main valve core (4) is arranged in the cavity of the main valve sleeve (3), and the cavity of the main valve sleeve (3) is divided into a main valve cavity and a pilot cavity, the pilot cavity is connected to the second cavity (12) through the flow hole (13), the side wall of the main valve sleeve (3) has a side oil hole (31), and the side oil hole (31) can discharge the oil in the main valve cavity, the main valve sleeve (3) is installed on the electromagnetic drive unit (5), and the electromagnetic drive unit (5) is used to drive the pilot valve core (2) to move along its axial direction.

9. The solenoid valve according to claim 8, characterized in that: The solenoid valve further comprises a second elastic member (6), wherein the second elastic member (6) is arranged between the main valve core (4) and the pilot valve seat (1).

10. The solenoid valve according to claim 8, characterized in that: The electromagnetic drive unit (5) further comprises a fixed seat (51), a guide rod (52) and an electromagnetic assembly. A portion of the main valve sleeve (3), the fixed seat (51) and the guide rod (52) are all arranged in the electromagnetic assembly. The guide rod (52) is inserted into the fixed seat (51). The fixed seat (51) can abut against the pilot valve core (2). The electromagnetic assembly can drive the guide rod (52) to move, so that the guide rod (52) drives the pilot valve core (2) to move.

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