Anti-blocking overflow valve with hydraulic power compensation function, hydraulic device and hydraulic system

Abstract

The invention discloses an anti-blocking overflow valve with a hydraulic power compensation function, a hydraulic device and a hydraulic system, and belongs to the technical field of hydraulics. The overflow valve comprises a valve body, a valve element and an elastic structure; the valve element is arranged in a valve hole of the valve body and can move in the axial direction of the valve hole, the elastic structure is arranged at the end of the valve body in a sealed mode, and the elastic structure is connected with the valve element. The valve element is provided with a control cavity, the axial projection areas of the two ends, making contact with a pressure medium, of the control cavity are different in the flowing direction of the pressure medium, the area of the end, close to the valve port, of the control cavity is larger than that of the other end of the control cavity, the valve body is provided with an oil inlet P and an oil outlet T1 and communicated with the valve port, and the oil inlet P is communicated with the control cavity. When the overflow valve is in a pressure relief state, the oil liquid inlet P is communicated with the oil liquid outlet T1 through the control cavity; the control cavity is of an asymmetric structure, the set pressure of the overflow valve can be changed by adjusting the area difference of the pressure faces of the control cavity and changing the pressure difference of the two pressure faces of the control cavity, and meanwhile the reliability and stability of the set pressure of the system are improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic element design, in particular to an anti-blocking overflow valve with hydraulic force compensation, a hydraulic device and a hydraulic system. Background Art

[0002] As the core component of the hydraulic system, the high-pressure relief valve is used to stabilize the pressure of the hydraulic system and ensure that the pressure is at the rated state. When the hydraulic system works at the rated pressure, the relief valve remains normally open. At the same time, the high-pressure relief valve is used to limit the maximum pressure of the hydraulic system to avoid damage to related components and pipelines in the hydraulic system. At this time, the set pressure of the relief valve is generally about 2MPa higher than the rated pressure of the system. When the system works normally, the relief valve remains normally closed.

[0003] With the development of industry, higher requirements are put forward for the stability of hydraulic system, which requires the pressure fluctuation of relief valve setting to be as small as possible. The existing high pressure relief valve generally adopts cone valve structure. Figure 1 As shown in the figure, its working principle is: the hydraulic pressure generated by the inlet oil P acting on the cone surface of the main valve core through the damping hole is compared with the spring force to set the nominal pressure of the relief valve; however, when the spring force is constant and the set pressure is high, the diameter of the damping hole is very small. When the size of the solid particles in the oil is close to the hole diameter, the hole is easily blocked, and the set pressure of the relief valve will change, and even the entire valve will fail completely, seriously affecting and restricting the reliability of the entire system; in addition, the valve core back pressure oil (spring chamber oil) and the valve port return oil share the oil drain port T. When the valve port is opened, the fluctuation of the T port pressure will cause the valve core back pressure to fluctuate, and finally cause the P port pressure setting value to fluctuate. At the same time, during the valve port opening process, due to the effect of the hydraulic force, the pressure setting value will also fluctuate. Based on the above factors, the stability of the entire hydraulic system is affected and restricted. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides an anti-clogging overflow valve, a hydraulic device and a hydraulic system with hydraulic force compensation. The overflow valve adopts an asymmetric sliding valve structure to achieve the stability of the hydraulic system.

[0005] The present invention is achieved through the following technical solutions: An anti-clogging overflow valve with hydraulic force compensation comprises a valve body, a valve core and an elastic structure; The valve core is arranged in the valve hole of the valve body and can move axially along the valve hole. The elastic structure is sealed and arranged at the end of the valve body. The elastic structure is connected to the valve core. The valve core is provided with a control chamber. Along the direction of flow of the pressure medium, the axial projection areas of the control chamber at both ends in contact with the pressure medium are different, and the area at one end close to the valve port is larger than the area at the other end. An oil inlet P and an oil outlet T1 are provided on the valve body and are connected with the valve hole. The oil inlet P is connected with the control chamber. When the relief valve is in the pressure relief state, the oil inlet P is connected with the oil outlet T1 through the control chamber.

[0006] Preferably, the control chamber is arranged on the outer wall of the valve core and extends axially along the valve core. One end of the control chamber close to the elastic structure is the first pressure surface, and the other end is the second pressure surface. The pressure area of ​​the first pressure surface is greater than the pressure area of ​​the second pressure surface.

[0007] Preferably, the valve core diameters at both ends of the control chamber are different.

[0008] Preferably, the control chamber is an annular groove and a rectangular groove arranged on the valve core.

[0009] Preferably, the spring structure includes a spring chamber and a spring arranged inside the spring chamber, and the spring chamber is connected to the outside through an oil drain path, so that the spring chamber is in a normal pressure state.

[0010] Preferably, the oil drain path includes an oil drain port T2 provided on the valve body, and the oil drain port T2 is communicated with the spring chamber.

[0011] Preferably, the oil drain path comprises an oil drain groove, which is provided on the valve core, a plurality of oil drain grooves are arranged at intervals along the axial direction of the valve core, and the oil drain grooves are communicated with the outside of the valve body.

[0012] Preferably, the valve core is provided with an oil drain hole, one end of which is communicated with the spring chamber and the oil drain port T2; The oil drain groove is communicated with the oil drain hole through the oil guide hole.

[0013] A hydraulic device, the oil circuit of which is provided with an anti-clogging overflow valve with hydraulic force compensation.

[0014] A hydraulic system comprises the hydraulic device.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The relief valve of the present application adopts an asymmetric sliding valve structure, and the areas at both ends of the hydraulic control chamber adopt an asymmetric structure, thereby generating a pressure difference during the opening process. The pressure difference forms an axial force to drive the valve core to move, so that the control chamber is connected to the oil outlet T1, and the relief valve is opened; in addition, by adjusting the area difference of the pressure surface of the control chamber and changing the pressure difference on the two pressure surfaces of the control chamber, the set pressure of the relief valve can be changed. The smaller the pressure difference, the greater the rated pressure of the relief valve, and vice versa. Secondly, during the opening process of the valve port of the relief valve, the pressures acting on the two ends of the control chamber are different, which compensates for the hydraulic force generated during the opening process of the valve port, thereby reducing the influence of the valve port hydraulic force on the fluctuation of the set pressure value of the relief valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 It is a structural diagram of an existing cone valve type relief valve; Figure 2 It is a schematic diagram of the structure of the overflow valve of the present invention; Figure 3 It is a partial enlarged view of the overflow valve of the present invention; Figure 4 It is an enlarged view of the valve port opening state of the overflow valve of the present invention.

[0018] In the figure: In the figure: 1. adjusting pin; 2. spring; 3. spring chamber; 4. gap; 4-1. oil guide hole; 4-2. oil guide hole; 5. oil drain groove; 6. valve core; 7. oil drain hole; 8. damping hole; 9. control chamber; 91. first pressure surface; 92. second pressure surface. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0021] See also Figure 1 The existing overflow valve adopts a cone valve structure, including a valve body, a spring chamber 3 is arranged in the valve body, an oil inlet P and an oil outlet T are arranged on the valve body and are connected with the spring chamber, a valve core 6 is arranged in the spring chamber, the oil inlet P is connected with the spring chamber through a damping hole 8, a cone valve needle is arranged at the end of the valve core 6, a gap 4 is arranged between the valve core 6 and the spring chamber, the damping hole and the valve needle are arranged coaxially, a spring is arranged in the spring chamber, which is used to apply thrust to the valve core so that the valve needle is inserted into the damping hole, and an adjusting pin 1 is arranged at the end of the valve body for adjusting the elastic force of the spring.

[0022] The relief valve of this cone valve structure is limited by the system power-to-weight ratio. The upper limit of the volume and weight of the component itself has been determined. For the relief valve, the outer diameter of the valve core and the spring force value are basically determined. If the set pressure of the relief valve needs to be increased, a small adjustment can be achieved by adjusting the adjustment pin (increasing the spring pre-compression force). If the set pressure of the relief valve needs to be increased significantly, under the condition that the above parameters remain unchanged, for the traditional cone valve structure, it can only be achieved by reducing the diameter of the damping hole. Achieve. The diameter of the damping hole is about 1.5mm, which is easily blocked by solid particles in the oil (metal chips generated during the operation of the system, molding sand shed from the casting flow channel, metal oxide particles, etc.). If the diameter of the damping hole continues to be reduced, practice has shown that the probability of the hole being blocked will increase significantly, thereby greatly reducing the reliability of the system. Therefore, it is prohibited to use damping holes with a diameter less than 1mm in hydraulic components. In response to the above problems, this application proposes an anti-blocking overflow valve with hydraulic force compensation, which adopts an overflow valve with an asymmetric sliding valve structure. The overflow valve is described in detail below.

[0023] See also Figure 2-4 , an anti-clogging overflow valve with hydraulic force compensation, comprising a valve body, a valve core, a valve hole and an elastic structure; The valve hole is arranged in the valve body, the valve core 6 is arranged in the valve hole and can move axially along the valve hole, the elastic structure is sealed and arranged at the end of the valve body, and the elastic structure is connected to the valve core.

[0024] A control chamber 9 is provided on the valve core. Along the direction of flow of the pressure medium, the axial projection areas of the two ends of the control chamber in contact with the pressure medium are different, and the area at one end close to the valve port is larger than that at the other end. An oil inlet P and an oil outlet T1 are provided on the valve body and are connected with the valve hole. The oil inlet P is connected with the control chamber. When the relief valve is in the pressure relief state, the oil inlet P is connected with the oil outlet T1 through the control chamber.

[0025] The relief valve adopts an asymmetric sliding valve structure, and the areas of both ends of the hydraulic control chamber adopt an asymmetric structure. The area of ​​one end close to the valve port is larger than the area of ​​the other end. The valve port is a channel formed when the control chamber and the oil outlet T1 are connected. Since the two ends of the control chamber adopt an asymmetric structure, when the pressure medium enters the control chamber, a pressure difference is generated, and then an axial force is formed to drive the valve core to move, so that the control chamber is connected with the oil outlet T1. Therefore, by adjusting the area difference of the pressure surface of the control chamber and changing the pressure difference on the two pressure surfaces of the control chamber, the set pressure of the relief valve can be changed. The smaller the pressure difference, the greater the rated pressure of the relief valve, and vice versa. In addition, the relief valve cancels the structure of the damping hole of the existing relief valve, thereby solving the problem of blockage of the relief valve; secondly, in the process of opening the valve port of the relief valve, the pressure acting on the two ends of the control chamber is different, and the hydraulic force generated in the process of opening the valve port is compensated, reducing the influence of the valve port hydraulic force on the fluctuation of the set pressure value of the relief valve.

[0026] In some embodiments, the control chamber is arranged on the outer wall of the valve core 6 and extends along the axial direction of the valve core. One end of the control chamber close to the elastic structure is a first pressure surface 91, and the other end is a second pressure surface 92. The pressure area of ​​the first pressure surface 91 is greater than the pressure area of ​​the second pressure surface 92.

[0027] In some embodiments, the control chamber is an annular groove or a rectangular groove provided on the valve core, preferably an annular groove.

[0028] The annular groove is arranged in the middle of the valve core 6, and the two ends of the annular groove are respectively the first pressure surface 91 and the second pressure surface 92. The valve core diameters at the two ends of the annular groove are different. The valve core diameter at one end close to the spring structure is larger than the diameter at the other end. Therefore, the axial projection areas at the two ends of the annular groove are different. When the pressure medium enters, a pressure difference is generated, which drives the valve core to move, so that the oil inlet P is connected to the oil outlet T1 through the control chamber for pressure relief, so that the pressure of the hydraulic system is maintained at the rated pressure.

[0029] The working principle of the relief valve and the calculation method of pressure are as follows: See also Figure 3 , calculation of the nominal set pressure value of the relief valve (generally ignoring minor factors such as the axial friction force on the valve core and the inertia force of the valve core).

[0030] 1) The force balance equation of the asymmetric valve core is:

[0031] in, : Pressure P acts on the left side of the valve core, ; : The pressure P acts on the right side of the valve core. ; because ,so .

[0032] By adjusting the spring force , so that P just satisfies: When , the valve core starts to move, P is connected to T1, and this pressure is the set pressure of the relief valve.

[0033] 2) The force balance equation of the traditional cone valve is:

[0034] in, : Pressure P acts on the left side of the valve core, ; : Damping hole diameter.

[0035] By adjusting the spring force , so that P just satisfies: When , the valve core starts to move, P and T are connected, and this pressure is the set pressure of the relief valve.

[0036] 3) Compare by examples The main parameters of the two structures of relief valves are the same: the set pressure P is 45MPa, the spring force 80N, valve core outer diameter is 10mm.

[0037] If an asymmetric slide valve structure is used: , ; If the traditional cone valve structure is used: , .

[0038] When the above parameters remain unchanged, for the traditional cone valve structure, the only way to solve the problem is to reduce the diameter of the damping hole. Changing the rated pressure of the relief valve, the diameter of the damping hole is about 1.5mm, which is easy to be blocked by solid particles in the oil. If the diameter of the damping hole is further reduced, the difficulty of processing the damping hole will increase exponentially, and the manufacturing cost of the relief valve will also increase. At the same time, the smaller the damping hole, the greater the probability of blockage, which greatly reduces the reliability of the hydraulic system. The asymmetric slide valve structure of the present application only needs to increase the diameter of the damping hole when other parameters remain unchanged. (Reduce The difference between the two) is sufficient, and at the same time, the damping hole structure is cancelled in the structure, thereby fundamentally eliminating the problem of damping hole blockage and reducing the manufacturing cost of the overflow valve.

[0039] In some embodiments, the spring structure includes a spring chamber 3 and a spring 2 arranged inside the spring chamber. The spring chamber is coaxial with the valve hole and interconnected. The end of the spring is connected to the end of the valve core 6 to apply thrust to the valve core to close the valve port.

[0040] See again Figure 2 In this embodiment, the spring structure is used as a modular structure, including a base and a spring. The spring cavity is arranged in the base. An adjusting pin 1 is also arranged on the base and abuts against the end of the spring to change the pressure of the spring. The base is sealed and connected to the valve body, which reduces the processing technology of the valve body and reduces the cost of the entire overflow valve.

[0041] In some embodiments, the cavity of the spring structure is in a normal pressure state. During the opening process of the overflow valve, the pressure medium enters the spring structure. Since the spring structure is in a normal pressure state, the pressure medium is prevented from causing pressure fluctuations in the spring structure, that is, the back pressure of the valve core remains constant, thereby solving the problem that the hydraulic system cannot work stably due to fluctuations in the set pressure caused by the back pressure during the opening process of the valve port.

[0042] In order to maintain the stability of the back pressure, the present application proposes two structures.

[0043] In the first structure, an oil drain port T2 is provided on the valve body, and the oil drain port T2 is connected to the spring chamber. During the opening process of the relief valve, the pressure medium enters the spring chamber and then flows back to the oil tank through the oil drain port T2, thereby avoiding the unstable flow of the pressure medium into the spring chamber causing fluctuations in the back pressure of the valve core chamber, and further causing pressure fluctuations in the opening process of the relief valve, thereby improving the pressure stability of the hydraulic system. In the second structure, a pressure relief oil circuit is provided on the valve core, including an oil drain groove 5, an oil guide hole 4-2, an oil drain hole 7 and an oil drain port T2. The oil drain hole is provided in the valve core, one end of the oil drain hole is connected to the spring chamber through the oil guide hole 4-1, and the other end extends to the other end of the valve core and is connected to the oil drain port T2.

[0044] The oil drain groove 5 is arranged on the valve core, and multiple oil drain grooves are arranged at intervals along the axial direction of the valve core, and the oil drain grooves are connected with the oil drain hole through the oil guide hole, so that the pressure medium between the valve core and the valve hole is discharged into the oil tank through the oil guide hole and the oil drain port T2, and the pressure medium in the spring chamber is discharged into the oil tank through the oil guide hole and the oil drain port T2, which solves the pressure fluctuation caused by the pressure medium between the valve core and the valve hole and the pressure medium in the spring chamber during the opening of the overflow valve, and maintains the pressure stability of the hydraulic system.

[0045] In the asymmetric spool valve structure relief valve of the present application, the oil in the spring chamber (entering the spring chamber through the process gap between the valve core and the valve hole) enters the oil tank through the oil drain hole 7 and the oil drain port T2, and the oil between the valve core and the valve hole (the process gap between the valve core and the valve hole) enters the oil tank through the oil drain groove, the oil guide hole, the oil drain hole 7 and the oil drain port T2. When the spring chamber pressure is close to zero, there will be no fluctuation.

[0046] For the traditional cone valve structure, the valve core back pressure (spring chamber pressure) is connected to the valve port return oil through the gap between the valve core and the valve hole (the spring chamber return oil and the valve port return oil share the same drain port T). When the valve port is opened, the fluctuation of the T port pressure will cause a large fluctuation in the valve core back pressure, and finally cause the P port pressure setting value to fluctuate, so that the system cannot work stably during the valve port opening process due to the fluctuation of the set pressure.

[0047] The following is a detailed description of the compensation principle of the control chamber for the valve port hydraulic force, as follows: Influence of valve port hydraulic force on fluctuation of relief valve set pressure The hydraulic force is the unbalanced pressure distribution on the valve core caused by the change in the flow velocity of the valve port during the valve opening process, thereby generating an additional axial force in the direction of closing the valve port.

[0048] The hydraulic force acts on the valve core, causing the P port pressure to fluctuate greatly (large overshoot) during the valve opening process. Both the cone valve port and the sliding valve port will be affected by the hydraulic force during the valve opening process.

[0049] In this structure, the hydraulic force is reduced and compensated by the following structures: When the valve port is in the open stage (small opening), the oil flows out from the P port through the valve port and out of the T1 port ( Figure 4 In the direction of the arrow in the middle), since the valve opening is small (the flow area is small), the flow rate (flow rate / flow area) at the valve port is large. According to the Bernoulli equation, the higher the flow rate, the lower the pressure, so the closer to the valve port, the lower the pressure. Therefore, the pressure gradient acting on the S1 area ( Figure 4 P1) is approximately trapezoidal in distribution; while the pressure gradient acting on the S2 area ( Figure 4 P2) is distributed in a rectangular shape (large flow area, uniform flow velocity, and equal pressure).

[0050] like (General slide valve structure), then at this time, due to ,so , thus generating a rightward fluid force This force acts on the valve core and forces the valve port to close, so that during the valve port opening process, the P port set pressure will fluctuate greatly (large overshoot).

[0051] In this structure, due to , then the fluid force It is reduced, thereby compensating for the hydraulic force, so that when the valve port is opening, the fluctuation of the set pressure at port P is reduced (the overshoot is smaller).

[0052] The anti-clogging overflow valve with hydraulic force compensation of the present application has the following advantages: 1. A sliding valve structure is adopted, and the control chamber adopts an asymmetric structure. The area S1 of the first pressure surface 91 (the area acting to the left) is greater than the area S2 of the second pressure surface 91 (the area acting to the right). By adjusting the area difference of the pressure surface of the control chamber and changing the pressure difference on the two pressure surfaces of the control chamber, the set pressure of the relief valve can be changed. At the same time, the damping hole structure is cancelled, which fundamentally eliminates the problem of blockage of the damping hole of the traditional high-pressure relief valve.

[0053] 3) The areas at both ends of the control chamber are different. This asymmetric structure reduces the hydraulic force on the valve core during the opening process of the overflow valve, thereby improving the stability of the hydraulic system.

[0054] 3. The pressure medium between the spring chamber, the valve core and the valve hole is discharged into the oil tank through the oil drain hole and the oil drain port T2, eliminating the problem of fluctuation in the set pressure value of the relief valve caused by the back pressure fluctuation of the valve core, and improving the pressure stability of the hydraulic system.

[0055] A hydraulic device, the oil circuit of which is provided with the above-mentioned anti-clogging overflow valve with hydraulic force compensation.

[0056] The maximum pressure value of the hydraulic device is set according to the relief valve. When the pressure exceeds this set value, the relief valve will automatically open to release excess hydraulic oil, thereby preventing the liquid system from overloading and protecting key components such as the oil pump and motor from damage.

[0057] In the volume speed control circuit, the metering pump bypass throttling speed control circuit and the volume throttling speed control circuit, the overflow valve is in a normally closed state. When the load exceeds the specified limit, it opens and acts as a safety valve to prevent accidents caused by overload in the hydraulic system and machine tools.

[0058] The present application also provides a hydraulic system, comprising the above-mentioned anti-clogging overflow valve with hydraulic force compensation.

[0059] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An anti-clogging overflow valve with hydraulic compensation, characterized in that: It includes a valve body, a valve core and an elastic structure; The valve core is arranged in the valve hole of the valve body and can move axially along the valve hole. The elastic structure is sealed and arranged at the end of the valve body. The elastic structure is connected to the valve core. The valve core is provided with a control chamber. Along the direction of flow of the pressure medium, the axial projection areas of the control chamber at both ends in contact with the pressure medium are different, and the area at one end close to the valve port is larger than the area at the other end. An oil inlet P and an oil outlet T1 are provided on the valve body and are connected with the valve hole. The oil inlet P is connected with the control chamber. When the relief valve is in the pressure relief state, the oil inlet P is connected with the oil outlet T1 through the control chamber.

2. The anti-clogging overflow valve with hydraulic force compensation according to claim 1, characterized in that: The control chamber is arranged on the outer wall of the valve core and extends axially along the valve core. One end of the control chamber close to the elastic structure is a first pressure surface, and the other end is a second pressure surface. The pressure area of ​​the first pressure surface is greater than the pressure area of ​​the second pressure surface.

3. An anti-clogging overflow valve with hydraulic force compensation according to claim 1 or 2, characterized in that: The valve core diameters at both ends of the control chamber are different.

4. The anti-clogging overflow valve with hydraulic force compensation according to claim 3, characterized in that: The control chamber is an annular groove and a rectangular groove arranged on the valve core.

5. An anti-clogging overflow valve with hydraulic force compensation according to claim 1, 2 or 4, characterized in that: The spring structure comprises a spring cavity and a spring arranged inside the spring cavity. The spring cavity is connected to the outside through an oil discharge passage, so that the spring cavity is in a normal pressure state.

6. The anti-clogging overflow valve with hydraulic force compensation according to claim 5, characterized in that: The oil drain path includes an oil drain port T2 disposed on the valve body, and the oil drain port T2 is communicated with the spring chamber.

7. An anti-clogging overflow valve with hydraulic force compensation according to claim 5 or 6, characterized in that: The oil drain path comprises an oil drain groove, which is arranged on the valve core. A plurality of oil drain grooves are arranged at intervals along the axial direction of the valve core, and the oil drain grooves are communicated with the outside of the valve body.

8. The anti-clogging overflow valve with hydraulic force compensation according to claim 7, characterized in that: The valve core is provided with an oil drain hole, one end of which is communicated with the spring chamber and the oil drain port T2; The oil drain groove is communicated with the oil drain hole through the oil guide hole.

9. A hydraulic device, characterized in that: The oil circuit of the hydraulic device is provided with an anti-clogging overflow valve with hydraulic force compensation as claimed in any one of claims 1 to 8.

10. A hydraulic system, characterized in that: Comprising the hydraulic device as claimed in claim 9.

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