Unloading valve

Abstract

The present invention relates to an unloading valve, comprising a valve body and an unloading valve core, wherein the valve body has an oil inlet and an oil return port, an unloading chamber is arranged in the valve body, the unloading valve core is arranged in the unloading chamber and divides the unloading chamber into a first chamber and a second chamber, and a first throttle port and a second throttle port are provided on the unloading valve core, the first throttle port and the second throttle port can both communicate with the first chamber and the second chamber, the first chamber can communicate with an external oil circuit, and the second chamber can communicate with the oil inlet and the oil return port. When the oil circuit of the multi-way valve is disconnected from the first chamber, the pressure oil in the first chamber can first flow from the first throttle port and the second throttle port into the second chamber and return oil through the oil return port, and the unloading valve core slides rapidly to the left; when the unloading valve core slides to the left, the opening of the second throttle port gradually decreases, and when the second throttle port is completely closed, the pressure oil in the first chamber can only flow from the first throttle port into the second chamber and return oil through the oil return port, and the speed of the unloading valve core sliding to the left decreases.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic valve bodies, in particular to a relief valve. Background Art

[0002] The valve core of the existing unloading valve is usually only provided with one throttling hole. In order to enable the valve core to return quickly, the throttling hole needs to be set with a larger diameter, but this will cause the oil at the oil inlet to suddenly merge into the multi-way valve, causing a greater impact on the system. Summary of the invention

[0003] Based on this, it is necessary to provide a relief valve to address the above problems, the valve core of the relief valve can ensure that the valve core returns quickly while avoiding the pressure oil entering from the oil inlet from causing a large impact on the system.

[0004] The present invention first provides an unloading valve, comprising: a valve body, having an oil inlet and an oil return port, wherein the valve body is provided with an unloading chamber; and an unloading valve core, which is provided in the unloading chamber and divides the unloading chamber into a first chamber and a second chamber, wherein the unloading valve core is provided with a first throttle port and a second throttle port, wherein the first throttle port and the second throttle port are both capable of communicating with the first chamber and the second chamber, wherein the first chamber is capable of communicating with an external oil circuit, and the second chamber is capable of communicating with the oil inlet and the oil return port; when the first chamber is connected with the external oil circuit, the pressure The pressure oil can apply a force to the unloading valve core toward the second chamber, so that the unloading valve core can slide toward the side away from the first chamber, and the unloading valve core can open the second chamber and connect the oil inlet and the oil return port; when the first chamber is disconnected from the external oil circuit, the pressure oil can flow out from the first throttle port and the second throttle port, the unloading valve core can slide toward the side close to the first chamber, and the opening of the second throttle port is negatively correlated with the sliding distance of the unloading valve core toward the side close to the first chamber.

[0005] In the above-mentioned unloading valve, when the oil circuit of the multi-way valve is disconnected from the first chamber, the pressure oil in the first chamber can first flow into the second chamber from the first throttle port and the second throttle port and return the oil through the oil return port. At this time, the unloading valve core slides quickly to the left, thereby increasing the return speed of the unloading valve core; when the unloading valve core slides to the left, the opening of the second throttle port gradually decreases. When the second throttle port is completely closed, the pressure oil in the first chamber can only flow into the second chamber from the first throttle port and return the oil through the oil return port. At this time, the sliding speed of the unloading valve core to the left decreases; at the same time, when the unloading valve core slides to the left, the second chamber is gradually closed, and the pressure oil entering the unloading valve from the oil inlet can merge into the multi-way valve to increase the oil volume in the multi-way valve, thereby avoiding the phenomenon that the pressure oil entering the unloading valve from the oil inlet suddenly merges into the multi-way valve due to the sudden return of the unloading valve core, reducing the impact of the pressure oil on the system, and avoiding causing the actuator to accelerate suddenly.

[0006] In one embodiment, a third cavity communicated with the first cavity and a fourth cavity communicated with the third cavity are axially provided in the unloading valve core.

[0007] With such arrangement, after the pressurized oil in the multi-way valve enters the first chamber, due to the action of the first throttle port, the pressurized oil in the third chamber will not directly return to the oil return port, but will exert a greater rightward force on the inner wall of the third chamber in the third chamber, thereby pushing the unloading valve core to slide to the right.

[0008] In one of the embodiments, the unloading valve also includes a throttling plug arranged in the fourth chamber, and a third throttling port is axially opened in the throttling plug, so that the pressure oil entering the third chamber can flow out through the third throttling port and the first throttling port in sequence.

[0009] With such arrangement, the throttling screw plug can further cut off the pressure oil, thereby ensuring that the pressure oil in the third chamber can exert a greater rightward force on the receiving surface.

[0010] In one embodiment, the first throttle port includes a first throttle hole connecting the fourth chamber and the second chamber.

[0011] In one embodiment, the second throttling port includes a first annular groove opened on the outer peripheral wall of the unloading valve core, the first annular groove extends along the axial direction of the unloading valve core, and the second throttling port also includes a second throttling hole connecting the first annular groove and the third chamber.

[0012] With such arrangement, the pressurized oil in the third chamber passes through the first annular groove after being throttled by the second throttling hole; when the edge of the first annular groove fits against the inner circumferential wall of the first chamber, the first annular groove is disconnected from the second chamber, and when the unloading valve core gradually slides to the right, the first annular groove gradually opens and communicates with the second chamber.

[0013] In one of the embodiments, the valve body further has a communication port capable of communicating with an external oil circuit, and the communication port is communicated with the first chamber.

[0014] With such arrangement, the oil circuit in the multi-way valve can be connected or disconnected with the first chamber through the communication port.

[0015] In one embodiment, the unloading valve further includes a first elastic member axially arranged between the unloading valve core and the inner wall of the second cavity along the unloading cavity, and the first elastic member can exert an elastic force away from the unloading valve core itself.

[0016] In this arrangement, when the rightward force exerted by the pressure oil in the first chamber and the third chamber on the unloading valve core is smaller than the leftward force exerted by the first elastic member on the unloading valve core, the unloading valve core will slide to the left under the action of the first elastic member until the unloading valve core slides to the leftmost end.

[0017] In one of the embodiments, the valve body further has a confluence port connected to an external oil circuit, and a confluence oil circuit connected to the oil inlet and the confluence port is also provided in the valve body.

[0018] With this arrangement, the confluence port is connected to the oil inlet of the multi-way valve. When the oil inlet is disconnected from the oil return port, the pressurized oil entering the valve body from the oil inlet can pass through the confluence oil path and merge into the oil inlet of the multi-way valve through the confluence port.

[0019] In one of the embodiments, the unloading valve further includes a one-way valve disposed in the confluent oil circuit.

[0020] With this arrangement, the one-way valve can only allow the pressurized oil to move from the oil inlet to the confluence port.

[0021] In one of the embodiments, a safety oil circuit connected to the confluence port and the first chamber is further provided in the valve body, and a relief valve is provided in the safety oil circuit.

[0022] With such arrangement, when the pressure at the confluence port exceeds the set pressure, the safety oil circuit is opened, and the pressure oil at the confluence port can enter the first chamber through the safety oil circuit, thereby pushing the unloading valve core to slide to the side away from the first chamber, and the oil inlet and the oil return port are connected for unloading, thereby reducing the load and improving the system working capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a schematic structural diagram of an unloading valve according to an embodiment of the present invention;

[0025] Figure 2 The present invention provides Figure 1 Schematic diagram of the cross-sectional structure at aa in the middle;

[0026] Figure 3 The present invention provides Figure 2 Schematic diagram of the enlarged structure at point b in the middle.

[0027] Figure numerals: 1, valve body; 11, unloading chamber; 111, first chamber; 112, second chamber; 113, second annular groove; 12, confluent oil circuit; 13, safety oil circuit; 2, unloading valve core; 21, first throttle port; 211, first throttle hole; 22, second throttle port; 221, first annular groove; 222, second throttle hole; 23, third chamber; 24, fourth chamber; 25, step; 251, receiving surface; 26, through hole; 3, first elastic member; 4, throttling screw plug; 41, third throttle port; 5, one-way valve; 6, overflow valve; P, oil inlet; T, oil return port; A, confluent port; B, connecting port. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it may be directly on the other component or there may also be a central component. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a central component at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of this application are for illustrative purposes only and do not represent the only implementation method.

[0030] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In the present application, unless otherwise clearly specified and limited, a first feature being “above” or “below” a second feature may mean that the first feature is directly in contact with the second feature, or the first feature and the second feature are indirectly in contact through an intermediate medium. Moreover, a first feature being “above”, “above” or “above” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being “below”, “below” or “below” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in the specification of this application includes any and all combinations of one or more related listed items.

[0033] A multi-way valve usually needs to be provided with an unloading valve. When the pressure oil flow rate required by the multi-way valve is small, the unloading valve opens, and the pressure oil entering from the oil inlet P is directly discharged from the oil return port T for unloading. When the pressure oil flow rate required by the multi-way valve is large, the unloading valve returns, and the pressure oil entering from the oil inlet P can enter the multi-way valve for confluence. The valve core of the existing unloading valve is usually provided with only one throttle hole. When the throttle hole has a small diameter, the valve core will return slowly, resulting in hysteresis. In order to enable the valve core to return quickly, the throttle hole needs to be provided with a larger diameter, but this will cause the oil at the oil inlet to suddenly merge into the multi-way valve, causing a greater impact on the system.

[0034] In order to solve the above problems, Figures 1 to 3 As shown, the present invention provides a relief valve, the valve core of which can ensure that the valve core returns quickly while preventing the pressure oil entering from the oil inlet from causing a large impact on the system.

[0035] like Figure 2As shown, specifically, the unloading valve includes a valve body 1 and an unloading valve core 2, the valve body 1 has an oil inlet P and an oil return port T, an unloading chamber 11 is arranged in the valve body 1, the unloading valve core 2 is arranged in the unloading chamber 11 and divides the unloading chamber 11 into a first chamber 111 and a second chamber 112, and a first throttle port 21 and a second throttle port 22 are opened on the unloading valve core 2, the first throttle port 21 and the second throttle port 22 can communicate with the first chamber 111 and the second chamber 112, the first chamber 111 can be communicated with an external oil circuit, and the second chamber 112 can be communicated with the oil inlet P and the oil return port T; when the first chamber 111 When connected with the external oil circuit, the pressure oil can exert a force on the unloading valve core 2 toward the second chamber 112, so that the unloading valve core 2 can slide toward the side away from the first chamber 111, and the unloading valve core 2 can open the second chamber 112 and connect the oil inlet P and the oil return port T; when the first chamber 111 is disconnected from the external oil circuit, the pressure oil can flow out from the first throttle port 21 and the second throttle port 22, the unloading valve core 2 can slide toward the side close to the first chamber 111, and the opening of the second throttle port 22 is negatively correlated with the sliding distance of the unloading valve core 2 toward the side close to the first chamber 111.

[0036] As mentioned above, the valve core of the existing unloading valve is usually only provided with one throttling hole. When the diameter of the throttling hole is small, the valve core will return slowly and there will be a lag. In order to enable the valve core to return quickly, the throttling hole needs to be set with a larger diameter, but this will cause the oil at the oil inlet to suddenly merge into the multi-way valve, causing a greater impact on the system. In the unloading valve provided by the present invention, a first throttle port 21 and a second throttle port 22 are provided on the unloading valve core 2, and the first throttle port 21 can always connect the first chamber 111 and the second chamber 112, and the opening of the second throttle port 22 is negatively correlated with the distance that the unloading valve core 2 slides toward the side close to the first chamber 111; when the amount of oil required for the multi-way valve to operate is small, the oil circuit of the multi-way valve is connected with the first chamber 111, and the pressure oil enters the first chamber 111 and applies a force toward the second chamber 112 to the unloading valve core 2, thereby pushing the unloading valve core 2 to slide to the right. At this time, the unloading valve core 2 can open the second chamber 112 and connect the oil inlet P and the oil return port T. The pressure oil entering the unloading valve from the oil inlet P is directly returned from the oil return port T without entering the multi-way valve.

[0037] When the amount of oil required for the multi-way valve to operate is large, the multi-way valve cuts off the communication with the first chamber 111, and the pressure oil in the first chamber 111 can first flow into the second chamber 112 from the first throttle port 21 and the second throttle port 22 and return the oil through the oil return port T. At this time, the unloading valve core 2 slides quickly to the left, thereby increasing the return speed of the unloading valve core 2; since the opening of the second throttle port 22 is negatively correlated with the distance the unloading valve core 2 slides to the left, the opening of the second throttle port 22 gradually decreases. When the second throttle port 22 is completely closed, the pressure oil in the first chamber 111 can only flow from the second throttle port 21 and the second throttle port 22. A throttle port 21 flows into the second chamber 112 and returns oil through the oil return port T. At this time, the speed at which the unloading valve core 2 slides to the left is reduced; at the same time, in the process of the unloading valve core 2 sliding to the left, the second chamber 112 is also gradually closed, and the oil inlet P and the oil return port T are gradually disconnected. The pressure oil entering the unloading valve from the oil inlet P can merge into the multi-way valve to increase the oil amount in the multi-way valve. In this way, the phenomenon that the pressure oil entering the unloading valve from the oil inlet P suddenly merges into the multi-way valve due to the sudden return of the unloading valve core 2 can be avoided, thereby avoiding impact and causing sudden acceleration of the actuator.

[0038] Furthermore, the valve body 1 has a communication port B that can communicate with the multi-way valve or other external oil circuits, and the communication port B is communicated with the first chamber 111. The oil circuit in the multi-way valve can be controlled to be connected or disconnected with the first chamber 111 through the communication port B.

[0039] like Figure 3 As shown, a third chamber 23 communicating with the first chamber 111 and a fourth chamber 24 communicating with the third chamber 23 are axially provided in the unloading valve core 2. Specifically, the left side of the third chamber 23 is communicated with the first chamber 111, and the unloading valve core 2 is provided with a through hole 26 communicating with the first chamber 111 and the third chamber 23. A step 25 is provided between the third chamber 23 and the fourth chamber 24, and the step 25 has a receiving surface 251 facing the first chamber 111. When the unloading valve core 2 is located at the leftmost side, the leftmost end of the unloading valve core 2 is against the left inner wall of the first chamber 111. At this time, the left side of the third chamber 23 is disconnected from the first chamber 111, and the pressure oil in the multi-way valve enters the first chamber 111 through the connecting port B. The pressure oil can enter the third chamber 23 through the through hole 26. Due to the action of the first throttle port 21, the pressure oil in the third chamber 23 will not directly return to the oil return port T, but can exert a larger rightward force on the receiving surface 251 in the third chamber 23, thereby pushing the unloading valve core 2 to slide to the right. After the left side of the third chamber 23 is connected to the first chamber 111, the pressure oil in the first chamber 111 can further push the unloading valve core 2 to slide to the right.

[0040] like Figure 3As shown, the unloading valve further includes a throttling screw plug 4 disposed in the fourth chamber 24, and a third throttling port 41 is axially provided in the throttling screw plug 4, and the pressure oil entering the third chamber 23 can flow out through the third throttling port 41 and the first throttling port 21 in sequence. The throttling screw plug 4 can further intercept the pressure oil, so that the pressure oil can be throttled once when entering the fourth chamber 24 from the third chamber 23 and when entering the second chamber 112 from the fourth chamber 24, thereby further ensuring that the pressure oil in the third chamber 23 can exert a greater rightward force on the receiving surface 251.

[0041] like Figure 3 As shown, the first throttle port 21 includes a first throttle hole 211 communicating with the fourth chamber 24 and the second chamber 112 .

[0042] like Figure 3 As shown, the second throttle port 22 includes a first annular groove 221 provided on the outer peripheral wall of the unloading valve core 2, the first annular groove 221 extends along the axial direction of the unloading valve core 2, and the second throttle port 22 also includes a second throttle hole 222 connecting the first annular groove 221 and the third chamber 23. The pressure oil in the third chamber 23 passes through the first annular groove 221 after being throttled by the second throttle hole 222; when the edge of the first annular groove 221 fits the inner peripheral wall of the first chamber 111, the first annular groove 221 is disconnected from the second chamber 112, and when the unloading valve core 2 gradually slides to the right, the first annular groove 221 gradually opens and communicates with the second chamber 112. Furthermore, a second annular groove 113 corresponding to the first annular groove 221 is provided at the connection between the first chamber 111 and the second chamber 112, and the second annular groove 113 can control the gear position accurately and is easy to process.

[0043] like Figure 2As shown, the unloading valve also includes a first elastic member 3 axially arranged between the unloading valve core 2 and the inner wall of the second chamber 112 along the unloading chamber 11, and the first elastic member 3 can exert an elastic force away from itself on the unloading valve core 2. When the multi-way valve is connected to the first chamber 111, the rightward force exerted by the pressure oil in the first chamber 111 and the third chamber 23 on the unloading valve core 2 is greater than the leftward force exerted by the first elastic member 3 on the unloading valve core 2, and the unloading valve core 2 can gradually slide to the right; when the multi-way valve is disconnected from the first chamber 111, the pressure oil in the first chamber 111 and the third chamber 23 returns to the oil return port T through the first throttle port 21 and the second throttle port 22. At this time, the rightward force exerted by the pressure oil in the first chamber 111 and the third chamber 23 on the unloading valve core 2 is less than the leftward force exerted by the first elastic member 3 on the unloading valve core 2, and the unloading valve core 2 slides to the left under the action of the first elastic member 3 until the unloading valve core 2 slides to the leftmost end. In the illustrated embodiment, the first elastic member 3 is a spring. Of course, in other embodiments, the first elastic member 3 may also be other elastic elements as long as it can apply an elastic force away from the unloading valve core 2, and no specific limitation is made here.

[0044] like Figure 2 As shown, the valve body 1 also has a confluence port A connected to an external oil circuit, and a confluence oil circuit 12 connected to the oil inlet P and the confluence port A is also provided in the valve body 1. The confluence port A is connected to the oil inlet of the multi-way valve. When the oil inlet P is disconnected from the oil return port T, the pressure oil entering the valve body 1 from the oil inlet P can pass through the confluence oil circuit 12 and merge into the oil inlet of the multi-way valve through the confluence port A.

[0045] like Figure 2 As shown, the unloading valve also includes a one-way valve 5 disposed in the confluent oil circuit 12. The one-way valve 5 can only allow the pressure oil to move from the oil inlet P to the confluent port A, thereby preventing the pressure oil in the multi-way valve from returning from the confluent port A through the confluent oil circuit 12 to the valve body 1.

[0046] like Figure 2 As shown, a safety oil circuit 13 connecting the confluence port A and the first chamber 111 is also provided in the valve body 1, and a relief valve 6 is provided in the safety oil circuit 13. When the pressure at the confluence port A exceeds the set pressure, the relief valve 6 opens, and the pressure at the confluence port A enters the first chamber 111 through the safety oil circuit 13, pushing the unloading valve core 2 to slide rightward, connecting the oil inlet P and the oil return port T for unloading, thereby reducing the load and improving the system working capacity.

[0047] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0048] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of patent protection of the present application shall be subject to the attached claims.

Claims

1. A relief valve, characterized in that: include: A valve body (1) having an oil inlet (P) and an oil return port (T), wherein a load-relief chamber (11) is arranged in the valve body (1); and An unloading valve core (2) is arranged in the unloading chamber (11) and divides the unloading chamber (11) into a first chamber (111) and a second chamber (112); a first throttle port (21) and a second throttle port (22) are provided on the unloading valve core (2); the first throttle port (21) and the second throttle port (22) are both capable of communicating with the first chamber (111) and the second chamber (112); the first chamber (111) is capable of communicating with an external oil circuit; and the second chamber (112) is capable of communicating with the oil inlet (P) and the oil return port (T); When the first chamber (111) is connected to an external oil circuit, the pressure oil can exert a force on the unloading valve core (2) toward the second chamber (112), so that the unloading valve core (2) can slide toward a side away from the first chamber (111), and the unloading valve core (2) can open the second chamber (112) and connect the oil inlet (P) and the oil return port (T); When the first chamber (111) is disconnected from the external oil circuit, the pressurized oil can flow out from the first throttle port (21) and the second throttle port (22), the unloading valve core (2) can slide toward the side close to the first chamber (111), and the opening of the second throttle port (22) is negatively correlated with the distance the unloading valve core (2) slides toward the side close to the first chamber (111); The pressure oil in the first chamber (111) can first flow into the second chamber (112) from the first throttle port (21) and the second throttle port (22) and return oil through the oil return port (T). At this time, the unloading valve core (2) slides rapidly to the left. Since the opening of the second throttle port (22) is negatively correlated with the distance the unloading valve core (2) slides to the left, the opening of the second throttle port (22) gradually decreases. When the second throttle port (22) is completely closed, the pressure oil in the first chamber (111) can only flow into the second chamber (112) from the first throttle port (21) and return oil through the oil return port (T). At this time, the speed at which the unloading valve core (2) slides to the left decreases.

2. The unloading valve according to claim 1, characterized in that: A third chamber (23) in communication with the first chamber (111) and a fourth chamber (24) in communication with the third chamber (23) are axially provided in the unloading valve core (2).

3. The unloading valve according to claim 2, characterized in that: The unloading valve further comprises a throttling screw plug (4) arranged in the fourth chamber (24), a third throttling port (41) being axially opened in the throttling screw plug (4), and the pressure oil entering the third chamber (23) can flow out through the third throttling port (41) and the first throttling port (21) in sequence.

4. The unloading valve according to claim 2, characterized in that: The first throttle port (21) comprises a first throttle hole (211) communicating with the fourth chamber (24) and the second chamber (112).

5. The unloading valve according to claim 2, characterized in that: The second throttling port (22) comprises a first annular groove (221) formed on the outer peripheral wall of the unloading valve core (2), wherein the first annular groove (221) extends axially along the unloading valve core (2), and the second throttling port (22) further comprises a second throttling hole (222) connecting the first annular groove (221) and the third chamber (23).

6. The unloading valve according to claim 1, characterized in that: The valve body (1) also has a communication port (B) capable of communicating with an external oil circuit, and the communication port (B) is in communication with the first chamber (111).

7. The unloading valve according to claim 1, characterized in that: The unloading valve further comprises a first elastic member (3) arranged axially along the unloading chamber (11) between the unloading valve core (2) and the inner wall of the second chamber (112), wherein the first elastic member (3) is capable of exerting an elastic force away from the unloading valve core (2) itself.

8. The unloading valve according to claim 1, characterized in that: The valve body (1) also has a confluence port (A) connected to an external oil circuit, and a confluence oil circuit (12) connected to the oil inlet (P) and the confluence port (A) is also provided in the valve body (1).

9. The unloading valve according to claim 8, characterized in that: The unloading valve further comprises a one-way valve (5) arranged in the confluent oil passage (12).

10. The unloading valve according to claim 8, characterized in that: The valve body (1) is also provided with a safety oil circuit (13) communicating with the confluence port (A) and the first chamber (111), and a relief valve (6) is provided in the safety oil circuit (13).

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