A non-return device

Abstract

The utility model relates to hydraulic technology field especially relates to a check device. A check device, the valve seat and the valve sleeve form first cavity, the side of valve sleeve away from valve seat forms second cavity, forms damping hole on the valve sleeve, and working oil port communicates with first cavity through damping hole, the valve core and valve seat form third cavity, and the valve core forms inside oil channel to make second cavity and third cavity keep communicating in, and the diameter of valve core and valve sleeve cooperation place is equal to the diameter of valve core and valve seat cooperation place, elastic member, act on the valve core, make the valve core abuts on the valve sleeve and forms seal, and the communication between first cavity and second cavity is blocked, and the valve sleeve abuts on the reversing valve body and forms seal, and the communication between working oil port and second cavity is blocked. The technical problem that the check device in the prior art cannot keep pressure balance, aggravates the wear and tear between push rod and thrust mechanism, leads to the increase of power, limits the use of maximum pressure of check device has been solved.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic technology, and in particular to a check valve device. Background Technology

[0002] Check valves are key components in the hydraulic systems of heavy equipment such as construction machinery, agricultural equipment, and special vehicles. They control the flow of hydraulic oil, prevent leakage, and prevent displacement of actuators such as cylinders and motors, thus better protecting the safety of personnel and equipment. Check valves are classified into direct-acting and pilot-operated types; based on the driving method, they are classified into mechanical, hydraulic, and electrically controlled types. The application and selection of check valves vary depending on the specific equipment requirements.

[0003] Existing mechanical check valves cannot maintain pressure balance between the upper and lower chambers. The higher the oil chamber pressure, the greater the pressure on the check valve, resulting in greater force on the mechanical push rod. In other words, the force on the mechanical push rod is related to the oil pressure in the upper chamber of the check valve. The mechanical push rod makes hard contact with the thrust mechanism, generating friction, and is driven by the thrust mechanism. When the oil pressure in the upper chamber of the check valve is too high, it will accelerate the wear of the mechanical push rod and the thrust mechanism, greatly reducing their service life and failing to meet quality requirements.

[0004] Since the force on the mechanical push rod is related to the oil pressure in the upper chamber of the check device, the greater the oil pressure in the upper chamber of the check device, the greater the thrust required by the thrust mechanism, which leads to an increase in power and energy waste; at the same time, it also limits the maximum pressure of the check device and cannot meet the needs of large and heavy-duty equipment. Utility Model Content

[0005] To address the technical problem that existing check devices cannot maintain pressure balance, exacerbate wear between the push rod and the thrust mechanism, lead to increased power, and limit the maximum pressure of the check device, this invention provides a check device that solves the aforementioned technical problems.

[0006] The technical solution of this utility model is as follows:

[0007] This utility model provides a check valve, which is designed for one working port of a directional valve, and includes:

[0008] The valve seat is fixedly assembled;

[0009] A valve sleeve is slidably assembled, a first cavity is formed between the valve seat and the valve sleeve, a second cavity is formed on the side of the valve sleeve away from the valve seat, a damping hole is formed on the valve sleeve, and the working oil port communicates with the first cavity through the damping hole;

[0010] A valve core moves between a valve seat and a valve sleeve; a third cavity is formed between the valve core and the valve seat, and an internal oil passage is formed inside the valve core to keep the second cavity and the third cavity connected; the diameter d1 of the valve core mating with the valve sleeve is equal to the diameter d2 of the valve core mating with the valve seat.

[0011] An elastic element acts on the valve core, causing the valve core to abut against the valve sleeve to form a seal, blocking the communication between the first cavity and the second cavity; the valve sleeve abuts against the valve body of the reversing valve to form a seal, blocking the communication between the working oil port and the second cavity;

[0012] Putter;

[0013] The thrust mechanism drives the valve core to move via a push rod.

[0014] According to one embodiment of the present invention, the valve seat, valve sleeve and valve core are arranged coaxially.

[0015] According to one embodiment of the present invention, a sliding hole is formed on the valve seat, and the first end of the valve core extends into the sliding hole and slides with the valve seat, and the third cavity is formed between the first end face of the valve core and the inner wall of the sliding hole.

[0016] According to one embodiment of the present invention, a through hole is formed on the valve sleeve, the second end of the valve core can pass through the through hole, the valve core abuts against the limiting surface in the through hole, and a gap is formed between the second end of the valve core and the inner wall of the through hole.

[0017] According to one embodiment of the present invention, the second cavity is kept in communication with the gap, and the second cavity is connected to the pressure oil port or the return oil port under the control of the thrust mechanism.

[0018] According to one embodiment of the present invention, the internal oil passage includes an axial oil passage and a radial oil passage that are interconnected. The axial oil passage extends to the first end face of the valve core and communicates with the third cavity. The radial oil passage extends to the outer peripheral surface of the valve core and communicates with the second cavity through the gap.

[0019] According to one embodiment of the present invention, the working oil port is connected to the outer periphery of the valve sleeve via a working oil passage, and the damping orifice is a radial damping orifice.

[0020] According to one embodiment of the present invention, the thrust mechanism acts on the valve core through a push rod, the push rod being slidably assembled, and both ends of the push rod being spherical.

[0021] According to one embodiment of the present invention, the axis of the thrust mechanism is perpendicular to the axis of the push rod, and a conical surface is formed on the thrust mechanism.

[0022] According to one embodiment of the present invention, a spring seat is fitted at one end of the valve seat near the valve sleeve, the valve seat and the spring seat are sealed together, an outer protrusion is formed on the outer peripheral surface of the valve core, the outer protrusion is slidably fitted with the valve sleeve, and the elastic element is located between the spring seat and the outer protrusion.

[0023] Based on the above technical solution, the technical effects that this utility model can achieve are as follows:

[0024] This utility model's check valve, under the action of the elastic element, forms a seal by the valve core against the valve sleeve, blocking the connection between the first and second cavities, thus serving as a pilot-stage check valve; the valve sleeve forms a seal against the directional valve body, blocking the connection between the working port and the second cavity, thus serving as a main-stage check valve; an internal oil passage is formed within the valve core to keep both ends of the valve core connected, thus balancing the pressure in the cavities at both ends of the valve core, facilitating oil suction and discharge during movement; the diameter of the valve core mating with the valve sleeve is equal to the diameter of the valve core mating with the valve seat, so the pressurized oil entering the first cavity exerts almost no force on the valve core in the axial direction, and the push rod only needs to overcome the force of the elastic element to push the valve core open. Therefore, the oil pressure on the valve core is balanced, and the push rod only needs to overcome the force of the elastic element to push the valve core, resulting in low force on the push rod and the thrust mechanism, low wear, reduced power consumption, and increased maximum pressure utilization of the check valve.

[0025] The check valve of this utility model has a valve seat, valve sleeve and valve core arranged coaxially, which can achieve accurate fit of the three; a gap is formed between the second end of the valve core and the inner wall of the through hole. The internal oil passage can ensure that the third cavity can be connected with the second cavity through the internal oil passage and the gap, which facilitates the oil suction and discharge of the third cavity, and will not be interfered with by the cooperation between the second end of the valve core and the push rod.

[0026] In this utility model, the push rod is slidably assembled, and the two ends of the push rod are spherical. The push rod can move axially to push the valve core. The contact area between the push rod and the valve core is small, the friction is small, the wear is reduced, and the service life is improved.

[0027] The check valve of this utility model has a conical surface formed on the thrust mechanism. When the thrust mechanism moves axially, the conical surface can push the push rod, and the push rod pushes the valve core away from the valve sleeve. It overcomes the force of the elastic element almost only and is not affected by the oil pressure of the first chamber. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the anti-return device of this utility model;

[0029] Figure 2 A partially enlarged view of the anti-return device;

[0030] Figure 3This is a schematic diagram of the valve core structure;

[0031] In the diagram: 1-valve seat; 2-valve sleeve; 21-damping hole; 22-through hole; 3-valve core; 31-internal oil passage; 311-axial oil passage; 312-radial oil passage; 32-outer protrusion; 321-flow groove; 33-abutting surface; 4-elastic element; 5-push rod; 6-thrust mechanism; 61-conical surface; 71-first cavity; 72-second cavity; 73-third cavity; 74-gap; 8-spring seat; 91-first seal; 92-second seal; 10-reversing valve body; 101-working oil passage. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present utility model or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0033] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0035] In the description of this utility model, it should be understood that the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0036] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0037] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0038] like Figure 1-3As shown, this embodiment proposes a check valve for a working port of a directional control valve. The check valve includes a valve seat 1, a valve sleeve 2, a valve core 3, an elastic element 4, a push rod 5, and a thrust mechanism 6. The check valve is assembled inside the valve body 10 of the directional control valve. The valve seat 1 is fixedly assembled, and the valve sleeve 2 is slidably assembled. A first cavity 71 is formed between the valve seat 1 and the valve sleeve 2. A second cavity 72 is formed on the side of the valve sleeve 2 away from the valve seat 1. The valve core 3 is located between the valve seat 1 and the valve sleeve 2, and the first end of the valve core 3 is slidably engaged with the valve seat 1. The second end of the valve core 3 abuts against the valve sleeve 2. A damping hole 21 is formed on the valve sleeve 2, through which the working oil port communicates with the first cavity 71. The elastic element 4 acts on the valve core 3, causing it to abut against the valve sleeve 2 to form a seal, blocking the communication between the first cavity 71 and the second cavity 72. The valve sleeve 2 abuts against the directional valve body 10 to form a seal, blocking the communication between the working oil port and the second cavity 72. The second end of the valve core 3 extends out and engages with the push rod 5. The thrust mechanism 6 pushes the push rod 5, thereby pushing the valve core 3. When the thrust mechanism 6 is in the neutral position, the pressure oil from the working oil port can enter the first cavity 71 through the damping hole 21, tightly pressing the valve sleeve 2 against the directional valve body 10, with sealing point E in a sealed state. The valve core 3, also under the action of the elastic element 4, abuts against the valve sleeve 2, with sealing point F in a sealed state. The pressure oil in the first cavity 71 can be maintained within the first cavity 71 without leakage, achieving a check valve function.

[0039] like Figure 1-2 As shown, the check device can be installed inside the directional valve body 10. Specifically, an open mounting cavity can be formed on the directional valve body 10. The mounting cavity is connected to the working oil port. The valve seat 1 is installed at the opening of the mounting cavity. A second sealing element 92 is provided between the valve seat 1 and the directional valve body 10 to ensure sealing.

[0040] As a preferred technical solution in this embodiment, in order to facilitate the assembly of the valve seat 1, the valve seat 1 can be threaded onto the valve body 10 of the directional valve.

[0041] As a preferred technical solution in this embodiment, in order to slide and cooperate with the valve core 3, a sliding hole with an inward opening is formed on the valve seat 1. The first end of the valve core 3 can extend into the sliding hole and slide and cooperate with the valve seat 1. The first end face of the valve core 3 and the inner wall of the sliding hole cooperate to form a third cavity 73.

[0042] like Figure 1-2As shown, the valve sleeve 2 is slidably assembled in the mounting cavity of the directional valve body 10. The valve sleeve 2 is located inside the valve seat 1. Under the indirect force of the elastic element 4 and the oil pressure in the first cavity 71, the valve sleeve 2 can abut against the directional valve body 10, so that the sealing point E is in a sealed state. An axially extending through hole 22 is formed on the valve sleeve 2. The second end of the valve core 3 can pass through the through hole 22 and cooperate with the push rod 4. The valve core 3 can also abut against the valve sleeve 2, so that the sealing point F is in a sealed state.

[0043] As a preferred embodiment, the through hole 22 can be configured as a through hole with varying diameter. The through hole 22 can be divided into a first segment, a second segment, and a third segment along the direction away from the valve seat 1. The first segment has the largest diameter, the third segment has the next largest diameter, and the second segment has the smallest diameter. A limiting surface is formed between the first segment and the second segment, and the valve core 3 abuts against the radially inner end of the limiting surface. To ensure the sealing performance of the sealing point E, the radially inner end of the limiting surface can be an inner conical surface. Preferably, the diameter of the third segment is slightly larger than that of the second end, which facilitates the formation of a gap 74 between the third segment and the outer surface of the second end of the valve core 3.

[0044] As a preferred technical solution in this embodiment, in order to ensure the sealing performance of the sealing point F, an inner conical surface can also be provided on the valve body 10 of the reversing valve, and a corresponding outwardly convex arc surface is formed on the valve sleeve 2 to ensure the sealing effect.

[0045] As a preferred technical solution in this embodiment, the damping hole 21 is a radial hole, and the damping hole 21 is connected to the first section of the through hole 22. The working oil port is connected to the outer periphery of the valve sleeve 2 through the working oil passage 101, and then connected to the first section of the through hole 22 through the damping hole 21, and then connected to the first cavity 71.

[0046] As a preferred technical solution in this embodiment, a second cavity 72 is formed on the side of the valve sleeve 2 away from the valve seat 1. The second cavity 72 is connected to the installation space where the thrust mechanism 6 is located. The second cavity 72 is also connected to the gap 74. The thrust mechanism 6 slides to control the second cavity 72 to connect to the pressure oil port or the return oil port.

[0047] like Figure 1-2 As shown, the valve core 3 has an internal oil passage 31 inside, which can connect the two ends of the valve core 3. Specifically, the internal oil passage 31 connects the third cavity 73 and the second cavity 72. The first end of the valve core 3 extends into the sliding hole of the valve seat 1 and slides with the valve seat 1. The second end of the valve core 3 can abut against the limiting surface of the valve sleeve 2 under the action of the elastic element 4. The second end of the valve core 3 also passes through the through hole 22 of the valve sleeve 2 and cooperates with the push rod 5.

[0048] As a preferred technical solution in this embodiment, such as Figure 2As shown, the diameter of the first end of the valve core 3 that slides with the valve seat 1 is d1. The outer circumferential surface of the second end of the valve core 3 forms an abutment surface 33, which abuts against the limiting surface of the valve sleeve 2. The abutment surface 33 of the valve core 3 can be set as a conical surface, and the diameter of the abutment surface 33 at the abutment point of the limiting surface is d2. d1 and d2 are equal, so that the pressure oil entering the first cavity 71 exerts almost no axial force on the valve core 3.

[0049] As a preferred technical solution in this embodiment, such as Figure 3 As shown, the internal oil passage 31 includes an axial oil passage 311 and a radial oil passage 312 that are interconnected. One end of the axial oil passage 311 extends to the first end face of the valve core 3 and communicates with the third cavity 73. The second end of the axial oil passage 311 communicates with the radial oil passage 312. The radial oil passage 312 extends to the outer peripheral surface of the valve core 3 and maintains communication with the gap 74. That is, the third cavity 73 and the second cavity 72 are connected through the internal oil passage 31 and the gap 74.

[0050] As a preferred technical solution in this embodiment, the valve seat 1, valve sleeve 2 and valve core 3 are arranged coaxially.

[0051] As a preferred technical solution in this embodiment, such as Figure 3 As shown, an outer protrusion 32 is formed on the outer peripheral surface of the valve core 3. The outer protrusion 32 can be used for the assembly of the elastic element 4, and can also form a sliding fit with the first section of the through hole 22 of the valve sleeve 2 to limit the movement direction of the valve core 3. A flow groove 321 is formed on the outer protrusion 32 to facilitate the flow of oil on both sides of the axial direction.

[0052] like Figure 1-2 As shown, the elastic element 4 is sleeved on the valve core 3, and the spring seat 8 is assembled on the valve seat 1. The first end of the valve core 3 can slide through the spring seat 8 and extend into the sliding hole of the valve seat 1. One end of the elastic element 4 abuts against the spring seat 8, and the other end of the elastic element 4 abuts against the outer protrusion 32.

[0053] As a preferred technical solution in this embodiment, the elastic element 4 can be, but is not limited to, a spring.

[0054] As a preferred technical solution in this embodiment, in order to ensure sealing, a first sealing element 91 is provided between the spring seat 8 and the valve seat 1.

[0055] like Figure 1 As shown, the push rod 5 is slidably assembled inside the valve body 10 of the reversing valve and is located between the valve core 3 and the thrust mechanism 6. The first end of the push rod 5 is engaged with the thrust mechanism 6, and the second end of the push rod 5 is engaged with the second end face of the valve core 3. When the thrust mechanism 6 moves, it can push the push rod 5 to move, and the push rod 5 can push the valve core 3 to move against the force of the elastic element 4.

[0056] As a preferred technical solution in this embodiment, the end faces of both ends of the push rod 5 are spherical.

[0057] As a preferred technical solution in this embodiment, the push rod 5 and the valve core 3 are coaxially arranged.

[0058] like Figure 1 As shown, the thrust mechanism 6 is slidably assembled inside the valve body 10 of the reversing valve. The thrust mechanism 6 is connected to the second chamber 72. The thrust mechanism 6 can slide to control the oil inlet and outlet of the second chamber 72. The thrust mechanism 6 can also lift the valve core 3 through the push rod 5 to release the seal at the sealing point F.

[0059] As a preferred technical solution in this embodiment, the thrust mechanism 6 is the valve core of the reversing valve or a part of the reversing valve core. When the thrust mechanism 6 slides, it can control the second cavity 72 to connect to the pressure oil port or the return oil port.

[0060] As a preferred technical solution in this embodiment, a conical surface 61 is formed on the thrust mechanism 6, and the thrust mechanism 6 pushes the push rod 5 to lift the valve core 3 through the conical surface 61.

[0061] As a preferred technical solution in this embodiment, the axis of the thrust mechanism 6 is perpendicular to the axis of the push rod 5.

[0062] Based on the above structure, the working principle of the check valve in this embodiment is as follows:

[0063] When the thrust mechanism 6 is in the neutral position, the pressure oil from the working port enters the first chamber 71 through the working oil passage 101 and the damping hole 21 on the valve sleeve 2, tightly pressing the valve sleeve 2 against the valve body 10 of the reversing valve. The valve core 3 is pressed against the valve sleeve 2 under the action of the elastic element 4. At this time, both sealing points E and F are in a sealed state, and the pressure oil can be kept in the first chamber 71 without leakage, thus achieving the function of check valve.

[0064] When the thrust mechanism 6 moves in the first direction, Figure 1 Taking the state shown as an example, when the thrust mechanism 6 moves to the right, the second chamber 72 is connected to the pressure oil port, the push rod 5 does not work, the high pressure oil passes through the second chamber 72 to push the valve sleeve 2 open, enters the working oil passage 101, enters the working oil port, and completes the output of high pressure oil.

[0065] When the thrust mechanism 6 moves in the second direction, Figure 1Taking the illustrated state as an example, when the thrust mechanism 6 moves to the left, the second chamber 72 connects to the oil return port. The conical surface 61 of the thrust mechanism 6 can push the push rod 5 upward, and the push rod 5 contacts the valve core 3. Since the diameter d1 of the valve core 3 and the valve seat 2 are approximately equal to the diameter d2 of the valve core 3 and the valve sleeve 2, the pressure oil in the first chamber 71 exerts almost no force on the valve core 3 in the axial direction. Therefore, the push rod 5 only needs to overcome the force of the elastic element 4 to push the valve core 3 upward. At this time, the oil in the third chamber 73 will be discharged into the second chamber 72 through the internal oil passage 31 of the valve core 3. Meanwhile, the oil in the first chamber 71 flows into the second chamber 72 through the opening between the valve core 3 and the valve sleeve 2. At this time, since the working oil passage 101 and the first chamber 71 are connected through the damping hole 21 of the valve sleeve 2, the oil flow generates a pressure difference loss. The valve sleeve 2 moves upward under the pressure of the working oil passage 101, and the oil in the working oil passage 101 flows into the second chamber 72 through the opening between the valve sleeve 2 and the valve body 1. The second chamber 72 is connected to the return oil port and the shut-off port is opened to form the entire return oil system.

[0066] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A non-return device provided in relation to a working oil port of a reversing valve, characterized by, include: Valve seat (1) is fixedly assembled; The valve sleeve (2) is slidably assembled, and a first cavity (71) is formed between the valve seat (1) and the valve sleeve (2). A second cavity (72) is formed on the side of the valve sleeve (2) away from the valve seat (1). A damping hole (21) is formed on the valve sleeve (2), and the working oil port is connected to the first cavity (71) through the damping hole (21). The valve core (3) moves between the valve seat (1) and the valve sleeve (2); a third cavity (73) is formed between the valve core (3) and the valve seat (1), and an internal oil passage (31) is formed in the valve core (3) to keep the second cavity (72) and the third cavity (73) connected. The diameter d1 of the valve core (3) and the valve sleeve (2) is equal to the diameter d2 of the valve core (3) and the valve seat (1) at the same point. The elastic element (4) acts on the valve core (3) to make the valve core (3) abut against the valve sleeve (2) to form a seal, blocking the communication between the first cavity (71) and the second cavity (72); the valve sleeve (2) abuts against the valve body (10) of the reversing valve to form a seal, blocking the communication between the working oil port and the second cavity (72); Push rod (5); The thrust mechanism (6) pushes the valve core (3) to move through the push rod (5).

2. A non-return device according to claim 1, characterised in that The valve seat (1), valve sleeve (2) and valve core (3) are arranged coaxially.

3. A non-return device according to claim 1, characterised in that A sliding hole is formed on the valve seat (1), and the first end of the valve core (3) extends into the sliding hole and slides in cooperation with the valve seat (1). The third cavity (73) is formed between the first end face of the valve core (3) and the inner wall of the sliding hole.

4. A check valve according to claim 3, characterized in that, A through hole (22) is formed on the valve sleeve (2), and the second end of the valve core (3) can pass through the through hole (22). The valve core (3) abuts against the limiting surface in the through hole (22), and a gap (74) is formed between the second end of the valve core (3) and the inner wall of the through hole (22).

5. A check valve according to claim 4, characterized in that, The second cavity (72) is kept in communication with the gap (74), and the second cavity (72) is connected to the pressure oil port or the return oil port under the control of the thrust mechanism (6).

6. A check valve according to claim 5, characterized in that, The internal oil passage (31) includes an axial oil passage (311) and a radial oil passage (312) that are interconnected. The axial oil passage (311) extends to the first end face of the valve core (3) and communicates with the third cavity (73). The radial oil passage (312) extends to the outer peripheral surface of the valve core (3) and communicates with the second cavity (72) through the gap (74).

7. A check valve according to claim 1, characterized in that, The working oil port is connected to the outer periphery of the valve sleeve (2) via the working oil passage (101), and the damping hole (21) is a radial damping hole (21).

8. A check valve according to claim 1, characterized in that, The push rod (5) is slidably assembled, and both ends of the push rod (5) are spherical.

9. A check valve according to claim 1, characterized in that, The axis of the thrust mechanism (6) is perpendicular to the axis of the push rod (5), and a conical surface (61) is formed on the thrust mechanism (6).

10. A check valve according to claim 1, characterized in that, The valve seat (1) is fitted with a spring seat (8) at one end near the valve sleeve (2). The valve seat (1) and the spring seat (8) are sealed together. The outer circumferential surface of the valve core (3) has an outer protrusion (32). The outer protrusion (32) is slidably fitted with the valve sleeve (2). The elastic element (4) is located between the spring seat (8) and the outer protrusion (32).

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