Fixed differential relief valve, load sensing multi-way valve, hydraulic system and engineering machinery

Abstract

The present application relates to hydraulic valve structure, disclose a constant difference overflow valve, load sensitive multi-way valve, hydraulic system and engineering machinery, the constant difference overflow valve includes valve body and the valve core arranged in the valve body, the valve body includes oil inlet, oil return and feedback oil port, the valve core is equipped with with the first control chamber, the hydraulic control chamber and the second control chamber with the feedback oil port communication between the inner wall of the valve body, with the oil inlet communication can control the valve core in the first control chamber pressure, the hydraulic control chamber pressure and the second control chamber pressure can control the movement of the valve core under the interaction of the pressure, the hydraulic control chamber is connected with pressure control valve group, to be able to limit the differential pressure value of the constant difference overflow valve.The constant difference overflow valve can realize the main valve mid 0 pressure load relief, has good energy saving effect, and, can set constant differential pressure value, guarantee the output function of high precision of main valve.

Description

Technical Field

[0001] This invention relates to hydraulic valve structures, specifically to a differential relief valve. It also relates to a load-sensitive multi-way valve, a hydraulic system, and engineering machinery. Background Technology

[0002] With the advancement and development of construction machinery, increasingly higher demands are being placed on hydraulic control technology. These demands are not only reflected in the need for excellent transmission performance, control performance, and ease of maintenance, but also in the need to better meet energy-saving, speed regulation, and complex motion control requirements. Therefore, existing hydraulic systems for construction machinery employ load-sensitive system technology. Load-sensitive systems, represented by load-sensitive multi-way valves, can achieve matched control of system flow, pressure, and power, resulting in excellent energy-saving characteristics. In load-sensitive multi-way valves, the differential relief valve (also known as a three-way flow valve) dynamically adjusts the system pressure based on pressure feedback from the load end to achieve load-sensitive functionality and flow distribution.

[0003] like Figure 1 As shown, the differential pressure value of the constant differential relief valve is set by pre-compressing spring 1a. When the main valve is unloaded in the middle position, the main valve core 2a of the constant differential relief valve needs to compress spring 1a to open the oil drain channel, so that the flow supplied by the fixed pump is unloaded at the pressure set by spring 1a. It is impossible to achieve zero pressure unloading in the middle position, resulting in poor energy saving effect.

[0004] Moreover, refer to Figure 2 Since the magnitude of the spring force F increases linearly with the spring compression stroke S, the corresponding pressure difference will also increase with the increase of the opening stroke of the main valve core 2a (i.e., the spring compression stroke S). Therefore, referring to... Figure 3 When the main valve outputs a small flow rate, most of the flow rate from the metering pump needs to be discharged through the differential relief valve. At this time, the opening stroke (spring compression stroke S) of the main valve core 2a of the differential relief valve is large, resulting in an increase in the set differential pressure value of the differential relief valve, thus increasing the output Q of the main valve. Similarly, when the main valve outputs a large flow rate, a small portion of the flow rate from the metering pump needs to be discharged through the differential relief valve. At this time, the opening stroke (spring compression stroke S) of the main valve core 2a is small, the set differential pressure value of the differential relief valve is small, thus reducing the output Q of the main valve. In other words, using spring 1a preload to set the differential pressure value of the differential relief valve, because the spring force F cannot be set to a constant value independent of the spring compression stroke S, the output flow rate of the main valve is affected by the valve stem opening (stroke) and the differential pressure caused by spring disturbance, making it impossible to achieve high-precision output function.

[0005] In view of this, it is necessary to design a new differential relief valve to overcome or alleviate the above-mentioned technical problems. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a differential pressure relief valve, which can realize zero pressure relief in the middle position of the main valve, has a good energy saving effect, and can set a constant differential pressure value to ensure the high-precision output function of the main valve.

[0007] The technical problem to be further solved by the present invention is to provide a load-sensitive multi-way valve that can achieve zero pressure relief in the middle position of the main valve, has a good energy-saving effect, and has a high-precision output function.

[0008] The technical problem to be further solved by the present invention is to provide a hydraulic system that has good energy-saving effect and high-precision output function.

[0009] Furthermore, the technical problem to be solved by the present invention is to provide an engineering machine that has excellent energy-saving effect and high-precision output function.

[0010] To address the aforementioned technical problems, the first aspect of the present invention provides a differential relief valve, comprising a valve body and a valve core disposed within the valve body. The valve body includes an oil inlet, an oil return port, and a feedback port. A first control chamber communicating with the oil inlet, a hydraulic control chamber, and a second control chamber communicating with the feedback port are provided between the valve core and the inner wall of the valve body, so as to control the movement of the valve core under the interaction of the pressure in the first control chamber, the pressure in the hydraulic control chamber, and the pressure in the second control chamber. The hydraulic control chamber is connected to a pressure control valve assembly to limit the differential pressure value of the differential relief valve.

[0011] Preferably, the pressure control valve assembly includes a first pressure control valve and a second pressure control valve, and the hydraulic control chamber is connected to the oil line between the first pressure control valve and the second pressure control valve.

[0012] Specifically, the first pressure control valve is a pressure reducing valve, and the second pressure control valve is a relief valve.

[0013] Preferably, the valve further includes a valve cover mounted on the valve body and a partition sealed on the valve core. The outer circumferential surface of the partition is sealed to the inner wall of the valve body. The hydraulic control chamber and the second control chamber are located on both sides of the partition. The partition, the inner wall of the valve body, and the valve cover form the second control chamber. The valve core is provided with a stepped structure that is sealed to the inner wall of the valve body. The first control chamber and the hydraulic control chamber are located on both sides of the stepped structure. The valve core can move relative to the partition under the interaction of the pressure in the first control chamber, the pressure in the hydraulic control chamber, and the pressure in the second control chamber.

[0014] Furthermore, it also includes a spacer installed in the valve body, the spacer being located between the partition and the valve cover, so that the partition abuts against the inner wall of the valve body, the partition, the spacer, and the valve cover forming the second control cavity.

[0015] Optionally, a sealing groove is provided on the outer peripheral surface of the partition, and a sealing ring is installed in the sealing groove.

[0016] Optionally, it also includes a return oil chamber, wherein the sealing end of the valve core is a cone, and the first control chamber is connected to the return oil chamber through the sealing end of the valve core, so as to selectively connect or disconnect the oil inlet and the oil return port.

[0017] Optionally, the force-bearing area of ​​the sealing end of the valve core, the force-bearing area of ​​the side of the stepped structure, and the force-bearing area of ​​the load end of the valve core are all equal.

[0018] A second aspect of the present invention provides a load-sensitive multi-way valve, comprising a main valve and a differential relief valve as described in any of the above technical solutions, wherein the feedback port of the differential relief valve is connected to the load feedback port of the main valve.

[0019] Optionally, the main valve and the differential relief valve are integrated into a single structure.

[0020] A third aspect of the present invention provides a hydraulic system including the load-sensitive multi-way valve described in the above technical solution.

[0021] A fourth aspect of the present invention provides an engineering machine, including the hydraulic system described in the above technical solution.

[0022] The beneficial effects of the present invention through the above technical solution are as follows:

[0023] This invention eliminates the use of springs as the setting component for the differential pressure value of the differential relief valve. By connecting the hydraulic control chamber to the pressure control valve, the differential pressure value of the differential relief valve can be made precise, constant, and adjustable. This avoids the nonlinear interference to the differential pressure value of the differential relief valve caused by the influence of the spring force on the stroke, which exists in the prior art. When applied to load-sensitive multi-way valves, the flow distribution is more accurate, and the high-precision output function of the main valve is achieved.

[0024] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1This is a schematic diagram of the structure of a three-way flow valve in the prior art;

[0027] Figure 2 This is a diagram showing the characteristic relationship between spring force and spring compression stroke in a three-way flow valve of existing technology.

[0028] Figure 3 This is a diagram showing the characteristic relationship between the output flow rate of the main valve working port and the opening stroke of the valve core in a three-way flow valve of existing technology.

[0029] Figure 4 This is a schematic diagram of the differential overflow valve according to a specific embodiment of the present invention;

[0030] Figure 5 This is a hydraulic schematic diagram of a differential relief valve applied to a load-sensitive system in a specific embodiment of the present invention.

[0031] Explanation of reference numerals in the attached figures

[0032] 1 Valve body P oil inlet

[0033] T return port Ls feedback port

[0034] 2 valve cores with 21-step structure

[0035] 22 Sealing end 23 Load end

[0036] A1 The force-bearing area of ​​the sealed end; A2 The force-bearing area of ​​the side of the stepped structure.

[0037] The load-bearing area of ​​A3 load end is 31, which is the first control cavity.

[0038] 32 Hydraulic control chamber 33 Second control chamber

[0039] 34 Return oil chamber 41 First pressure control valve

[0040] 42 Second pressure control valve 5 Valve cover

[0041] 6 partitions 61 sealing rings

[0042] 7 spacers Detailed Implementation

[0043] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features.

[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "setting," and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0046] First, it should be noted that the differential relief valve of this invention belongs to the field of hydraulics. For those skilled in the art, its essential technical concept lies in the hydraulic connection relationship. Related hydraulic components, such as pressure reducing valves, relief valves, and hydraulic pumps, are well-known to those skilled in the art and are commonly used components in existing hydraulic systems. Therefore, these hydraulic components will only be briefly described below. After understanding the technical concept of this invention, those skilled in the art can also make simple substitutions to the oil circuits or valves to achieve the function of the differential relief valve of this invention, which also falls within the scope of protection of this invention.

[0047] like Figure 4 As shown, the differential relief valve of the basic embodiment of the present invention includes a valve body 1 and a valve core 2 disposed within the valve body 1. The valve body 1 includes an oil inlet P, an oil return port T, and a feedback port Ls. Between the valve core 2 and the inner wall of the valve body 1, there is a first control chamber 31 communicating with the oil inlet P, a hydraulic control chamber 32, and a second control chamber 33 communicating with the feedback port Ls, so as to control the movement of the valve core 2 under the interaction of the pressure in the first control chamber 31, the pressure in the hydraulic control chamber 32, and the pressure in the second control chamber 33. The hydraulic control chamber 32 is connected to a pressure control valve group so as to limit the differential pressure value of the differential relief valve.

[0048] The present invention controls the movement of the valve core 2 through the interaction between the pressure in the first control chamber 31, the pressure in the hydraulic chamber 32, and the pressure in the second control chamber 33; generally, referring to... Figure 5The feedback port Ls of the differential relief valve is connected to the load feedback port of the main valve in the load feedback multi-way valve, and the inlet P of the differential relief valve is connected to the inlet port of the main valve in the load feedback multi-way valve. This allows the flow rate output by the fixed displacement pump to be distributed between the differential relief valve and the main valve. Addressing the problem in existing technologies where the spring preload setting of the differential relief valve's differential pressure value is not independent of the spring compression stroke and thus affects the output flow rate at the main valve's working port, this invention creatively connects the hydraulic chamber to a pressure control valve assembly. The pressure control valve assembly controls the pressure within the hydraulic chamber 32, thereby precisely and constantly setting the differential pressure value of the differential relief valve. When the main valve is in the neutral position, since the second control chamber 33 is connected to the load feedback port of the main valve, the pressure within the second control chamber 33 is 0. Simultaneously, the pressure within the hydraulic chamber 32 is also controlled to be 0. This causes the valve core 2, under the action of the hydraulic oil flowing into the inlet P, to connect the inlet P to the return port T, thus allowing all the hydraulic oil output by the fixed displacement pump to flow back to the oil tank through the differential relief valve. Achieving zero-pressure unloading results in optimal energy saving. When the main valve reverses, the pressure in the hydraulic chamber 32 is controlled by the pressure control valve group, ensuring a constant differential pressure value for the differential relief valve. This design replaces the conventional method of setting the differential pressure value of the differential relief valve using spring preload. The valve core 2 of the differential relief valve moves primarily due to the interaction between the pressure at the inlet P and the pressure at the feedback port Ls. This allows for dynamic adjustment of the system pressure based on load pressure feedback, enabling the flow rate output by the fixed displacement pump to be distributed between the differential relief valve and the main valve. Furthermore, the differential pressure value of the differential relief valve can be set to a constant value, ensuring that the output flow rate of the main valve is only affected by its valve opening, resulting in a more precise output function.

[0049] As a specific embodiment of the pressure control valve assembly, the pressure control valve assembly includes a first pressure control valve 41 and a second pressure control valve 42. The first pressure control valve 41 is connected to the second pressure control valve 42, so that the hydraulic control chamber 32 is connected to the oil circuit between the first pressure control valve 41 and the second pressure control valve 42. The pressure in the hydraulic control chamber 32 is controlled by the first pressure control valve 41 and the second pressure control valve 42, and the pressure in the hydraulic control chamber 32 can be precisely set to a constant value, thereby preventing the flow rate at the working port of the main valve from being affected by the spring force.

[0050] The first pressure control valve 41 and the second pressure control valve 42 can jointly regulate the pressure within the hydraulic control chamber 32. For example, the first pressure control valve 41 can be a pressure reducing valve, and the second pressure control valve 42 can be a relief valve. The pressure reducing valve P1 can set the basic pressure value within the hydraulic control chamber 32, and the relief valve P2 can set the maximum pressure value within the hydraulic control chamber 32. The pressure within the hydraulic control chamber 32 is regulated between the two set values. The pressure reducing valve and the relief valve can be adjusted using various methods such as manual, hydraulic, and electro-proportional control. Generally, the set pressure values ​​of the pressure reducing valve and the relief valve are adjusted through a control and regulation system. The control and regulation system is generally a conventional control system in hydraulic equipment. Based on this, the set pressure values ​​of pressure control valves such as pressure reducing valves and relief valves are controlled using a control and regulation system, which is a relatively mature technology in terms of control implementation.

[0051] In a specific embodiment, a valve cover 5 is installed on the valve body 1, and the valve cover 5 is installed at the end of the valve body 1. A partition 6 is fitted on the valve core 2, and the partition 6 is sealed to the valve core 2. The valve core 2 can move relative to the partition 6. The outer peripheral surface of the partition 6 is sealed to the inner wall of the valve body 1. The partition 6 divides the space inside the valve body 1 into two chambers, namely the hydraulic control chamber 32 and the second control chamber 33. The partition 6, the inner wall of the valve body 1, and the valve cover 5 form the second control chamber 33. A stepped structure 21 is provided on the valve core 2, and the stepped structure 21 is sealed to the inner wall of the valve body 1. The first control chamber 31 and the hydraulic control chamber 32 are located on both sides of the stepped structure 21. That is to say, the first control chamber 31, the hydraulic control chamber 32, and the second control chamber 33 are sequentially separated by the stepped structure 21 and the partition 6. The first control chamber 31 is connected to the oil inlet P, the hydraulic control chamber 32 is connected to the pressure control valve group, and the second control chamber 33 is connected to the feedback oil port Ls. The pressure in the first control chamber 31 acts on one end of the valve core 2, and the pressure in the hydraulic control chamber 32 and the pressure in the second control chamber 33 act on the other end of the valve core 2, thereby pushing the valve core 2 to move, controlling the conduction and cutoff between the oil inlet P and the return oil port T, as well as the valve opening of the valve core 2, and controlling the flow rate through the differential relief valve. The valve cover 5 and the valve body 1 can be connected by various methods such as screw connection, threaded connection, or welding.

[0052] In one specific embodiment, the valve core 2 includes a sealing end 22 and a load end 23. The sealing end 22 is connected to the first control chamber 31, and the load end 23 passes through the partition 6 and extends into the second control chamber 33. Figure 4In the illustrated embodiment, the sealing end 22 is a cone. The first control chamber 31 is connected to the return oil chamber 34, and the return oil chamber 34 is connected to the return oil port T. The inner wall of the valve body 1 and the stepped structure 21 form the return oil chamber 34. When the oil inlet P and the return oil port T are in a closed state, the sealing end 22 extends into the first control chamber 31, separating and blocking the first control chamber 31 and the return oil chamber 34. The sealing end 22 moves to the right, which can open the channel, allowing the first control chamber 31 and the return oil chamber 34 to conduct, thus realizing the conduction between the oil inlet P and the return oil port T.

[0053] Understandably, differential relief valves are not limited to Figure 4 The cone valve shown can also be any other suitable valve type, such as a slide valve.

[0054] To facilitate understanding of the technical concept of this invention, the working process of the valve core 2 is described below.

[0055] Let the pressure in the first control chamber 31 be P1, the pressure in the hydraulic control chamber 32 be P2, and the pressure in the second control chamber 33 be P3. When each main valve is in the neutral position, the load feedback pressure value is 0, that is, P3 = 0. At this time, adjust the pressure control valve group to make P2 = 0. From P1*A1 = P2*A2 + P3*A3, we know that P1 = 0. The hydraulic oil flowing in from the oil inlet P enters the first control chamber 31, pushing the valve core 2 to move to the right. All the hydraulic oil flows into the return oil chamber 34 through the first control chamber 31 with a pressure value of 0, thereby realizing the main valve in the neutral position with 0 pressure to relieve the load, so as to achieve the best energy saving effect. When the main valve is in the reversing state, the load pressure is fed back to the second control chamber 33, acting on the load end 23 of the valve core 2 of the differential relief valve. At this time, the pressure control valve group is adjusted, and P2 is preset to a constant value, that is, P2*A2 is a constant value. It can be seen from P1*A1=P2*A2+P3*A3 that the valve core 2 is affected by the pressure of the oil inlet P and the load feedback pressure, thereby realizing flow distribution. Generally, it can be designed as A3=A1=A2. The formula P1*A1=P2*A2+P3*A3 can be simplified to P1=P2+P3, P2=P1-P3, that is, the differential pressure value of the differential relief valve is P2. P2 is a settable constant value. Since it is not affected by the spring, the value of P2 can be accurately constant and adjustable, thereby avoiding nonlinear interference caused by the spring force being affected by the stroke, and realizing the high-precision output function of the main valve. Of course, the force-bearing area A1 of the sealing end 22 of the valve core 2, the force-bearing area A2 of the side of the stepped structure 21, and the force-bearing area A3 of the load end 23 of the valve core 2 can also be designed differently. For example, the force-bearing area A2 of the side of the stepped structure 21 can be larger than the force-bearing area A1 of the sealing end 22 and / or the force-bearing area A3 of the load end 23. Depending on the design of the force-bearing area A3 of the load end 23, various pressure differential values ​​such as equal ratio and equal pressure can be set, enhancing the flexibility of the feedback method.

[0056] It should be noted that the connection between the partition 6 and the inner wall of the valve body 1 can be a fixed connection, for example, by welding or other methods to achieve a fixed seal between the partition 6 and the inner wall of the valve body 1. Of course, preferably, the connection between the partition 6 and the inner wall of the valve body 1 is detachable, for example, by a threaded seal connection. Alternatively, a spacer 7 can be provided inside the valve body 1, positioned between the partition 6 and the valve cover 5. Through the interaction between the valve cover 5, the spacer 7, and the partition 6, a stepped structure can be provided on the inner wall of the valve body 1, causing the partition 6 to abut against the stepped structure on the inner wall of the valve body 1, thus achieving the connection between the partition 6 and the inner wall of the valve body 1. The partition 6, the spacer 7, and the valve cover 5 form the second control cavity 33. To ensure sealing, a sealing groove can be provided on the outer circumferential surface, and a sealing ring 61 can be installed in the sealing groove.

[0057] To better understand the technical concept of the present invention, the differential overflow valve of the present invention will be described below in conjunction with a relatively comprehensive set of preferred technical features.

[0058] like Figure 4 As shown, the differential relief valve of the preferred embodiment of the present invention includes a valve body 1 and a valve core 2. The valve body 1 includes an oil inlet P, an oil return port T, and a feedback port Ls. The valve core 2 is disposed inside the valve body 1, and a first control chamber 31, a return oil chamber 34, a hydraulic control chamber 32, and a second control chamber 33 are provided between the valve core 2 and the inner wall of the valve body 1. The first control chamber 31 is connected to the oil inlet P, the return oil chamber 34 is connected to the return oil port T, and the hydraulic control chamber 32 is connected to the oil circuit between the first pressure control valve 41 and the second pressure control valve 42. The valve core 2 is provided with a stepped structure 21, which is sealed to the inner wall of the valve body 1. The return oil chamber 34... The hydraulic control chamber 32 is separated by a stepped structure 21. A partition 6 and a spacer 7 are installed inside the valve body 1. The hydraulic control chamber 32 and the second control chamber 33 are separated by the partition 6. The spacer 7 abuts the partition 6 against the inner wall of the valve body 1. A valve cover 5 is installed on the valve body 1. The valve cover 5 abuts the spacer 7 against the partition 6. The partition 6, the spacer 7 and the valve cover 5 form the second control chamber 33. The second control chamber 33 is connected to the feedback port Ls. The load end 23 of the valve core 2 passes through the partition 6 and extends into the second control chamber 33. The sealing end 22 of the valve core 2 is conical. The first control chamber 31 is connected to the return oil chamber 34 through the sealing end 22 of the valve core 2.

[0059] Among them, reference Figure 5The feedback port Ls is used to connect to the load feedback port of the main valve in the load feedback multi-way valve, and the inlet port P is connected to the inlet port of the main valve in the load feedback multi-way valve. This invention does not use a spring as a setting component for the differential pressure value of the constant differential relief valve, but uses the hydraulic value to set the differential pressure value, thereby avoiding nonlinear interference to the output flow of the main valve caused by the spring force being affected by the stroke. When the main valve is in the neutral position, the load feedback pressure P2 is 0, that is, the pressure P3 in the second control chamber 33 is 0. At the same time, the control and regulation system controls the first pressure control valve 41 and the second pressure control valve 42 to make the pressure in the hydraulic chamber 32 0. Under the action of the hydraulic oil flowing into the inlet P, the valve core 2 makes the inlet P and the return port T connected. From P1*A1=P2*A2+P3*A3, we know that P1=0, so that all the hydraulic oil output by the fixed displacement pump flows back to the oil tank through the differential relief valve to achieve zero pressure unloading. Here, A1 is the force-bearing area of ​​the sealing end 22 of the valve core 2, A2 is the force-bearing area of ​​the side of the stepped structure 21, and A3 is the force-bearing area of ​​the load end 23 of the valve core 2. When the main valve reverses direction, the pressure in the hydraulic chamber 32 is controlled hydraulically, ensuring a constant pressure differential value for the differential relief valve. As shown by P1*A1=P2*A2+P3*A3, the main valve output flow is linearly related to the differential relief valve, allowing the flow output from the fixed displacement pump to be distributed between the differential relief valve and the main valve, thus giving the main valve a more precise output function. Furthermore, a damping orifice can be installed in the oil circuit to reduce pressure surges in the system. A return spring can also be added to enhance the return performance of the valve core 2.

[0060] In the load-sensitive multi-way valve of the present invention, the main valve and the differential relief valve can be integrated into a single structure, which facilitates production and assembly.

[0061] The embodiments of the hydraulic system of the present invention may have the load-sensitive multi-way valve described in the above embodiments, that is, they adopt all the technical solutions of the above-described load-sensitive multi-way valve embodiments, and therefore have at least all the beneficial effects brought about by the technical solutions of the above-described load-sensitive multi-way valve embodiments.

[0062] The engineering machinery embodiments of the present invention may include the hydraulic system described in the above embodiments, that is, they adopt all the technical solutions of the above hydraulic system embodiments, and therefore at least have all the beneficial effects brought about by the technical solutions of the above hydraulic system embodiments. Examples include engineering machinery such as cranes, excavators, and bulldozers.

[0063] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A differential relief valve, characterized in that, The valve includes a valve body (1) and a valve core (2) disposed within the valve body (1). The valve body (1) includes an oil inlet (P), an oil return port (T), and a feedback port (Ls). The valve core (2) and the inner wall of the valve body (1) are provided with a first control chamber (31) communicating with the oil inlet (P), a hydraulic control chamber (32), and a second control chamber (33) communicating with the feedback port (Ls), so as to control the movement of the valve core (2) under the interaction between the pressure of the first control chamber (31), the pressure of the hydraulic control chamber (32), and the pressure of the second control chamber (33). The hydraulic control chamber (32) is connected to a pressure control valve group so as to limit the differential pressure value of the constant differential relief valve. It also includes a valve cover (5) installed on the valve body (1) and a partition (6) sealed on the valve core (2). The outer peripheral surface of the partition (6) is sealed to the inner wall of the valve body (1). The hydraulic control chamber (32) and the second control chamber (33) are located on both sides of the partition (6). The partition (6), the inner wall of the valve body (1) and the valve cover (5) form the second control chamber (33). The valve core (2) is provided with a stepped structure (21) that is sealed to the inner wall of the valve body (1). The first control chamber (31) and the hydraulic control chamber (32) are located on both sides of the stepped structure (21). The valve core (2) can move relative to the partition (6) under the interaction between the pressure of the first control chamber (31), the pressure of the hydraulic control chamber (32) and the pressure of the second control chamber (33).

2. The differential relief valve according to claim 1, characterized in that, The pressure control valve group includes a first pressure control valve (41) and a second pressure control valve (42), and the hydraulic control chamber (32) is connected to the oil line between the first pressure control valve (41) and the second pressure control valve (42).

3. The differential relief valve according to claim 2, characterized in that, The first pressure control valve (41) is a pressure reducing valve, and the second pressure control valve (42) is a relief valve.

4. The differential relief valve according to claim 1, characterized in that, It also includes a spacer (7) installed inside the valve body (1), the spacer (7) being located between the partition (6) and the valve cover (5) so that the partition (6) abuts against the inner wall of the valve body (1), the partition (6), the spacer (7) and the valve cover (5) forming the second control cavity (33).

5. The differential relief valve according to claim 1, characterized in that, A sealing groove is provided on the outer circumferential surface of the partition (6), and a sealing ring (61) is installed in the sealing groove.

6. The differential relief valve according to claim 1, characterized in that, It also includes a return oil chamber (34), the sealing end (22) of the valve core (2) is a cone, and the first control chamber (31) is connected to the return oil chamber (34) through the sealing end (22) of the valve core (2) so that the oil inlet (P) and the oil return port (T) can be selectively connected or cut off.

7. The differential relief valve according to claim 6, characterized in that, The force-bearing area (A1) of the sealing end (22) of the valve core (2), the force-bearing area (A2) of the side of the stepped structure (21), and the force-bearing area (A3) of the load end (23) of the valve core (2) are all equal.

8. A load-sensitive multi-way valve, characterized in that, It includes a main valve and a differential relief valve according to any one of claims 1 to 7, wherein the feedback port (Ls) of the differential relief valve is connected to the load feedback port of the main valve.

9. The load-sensitive multi-way valve according to claim 8, characterized in that, The main valve and the differential relief valve are integrated into a single structure.

10. A hydraulic system, characterized in that, Includes the load-sensitive multi-way valve according to claim 8 or 9.

11. An engineering machinery, characterized in that, Includes the hydraulic system according to claim 10.

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