pilot operated spool valve

Abstract

The present application relates to hydraulic control slide valve, to solve the problem that the existing hydraulic control slide valve setting valve rod back center position buffer function will affect the slide valve corresponding speed, the present application constructs a kind of hydraulic control slide valve, including valve body, valve rod and the buffer device arranged at each end of valve rod cavity, buffer device includes sleeve, sleeve is set on the outside of valve rod end and with valve rod clearance cooperation forms valve rod control cavity, sleeve can be axially slid relative to valve rod, sleeve is equipped with the valve rod abutting portion that the force in the direction of valve rod middle part is applied to valve rod and the valve body abutting portion that the displacement of sleeve to the direction of valve rod middle part is limited, reset spring is arranged between sleeve and valve body, reset spring applies the elastic force in the direction of valve rod middle part to sleeve, one-way throttle valve is arranged on sleeve and communicates valve rod cavity end chamber and valve rod control cavity.The hydraulic control slide valve in the present application has buffering effect when valve rod back center position, and it can respond quickly when valve rod moves to left position or right position and starts.

Description

Technical Field

[0001] This invention relates to a hydraulic valve, and more specifically, to a hydraulically controlled spool valve. Background Technology

[0002] Hydraulic spool valves are commonly used hydraulic components in engineering machinery to control hydraulic actuators. Common hydraulic spool valves have three operating positions: left, center, and right. Each end of the valve stem within the valve body has an oil-filled control chamber. When the control chamber is filled with oil, it pushes the valve stem to move, placing the hydraulic spool valve in the corresponding operating position. A return spring is usually installed in the control chamber. When no pressure oil is applied to the control chambers at either end of the valve stem, the valve stem is in the center position under the force of the return spring.

[0003] In some hydraulic systems, to avoid shock, the speed at which the valve stem returns to the neutral position needs to be limited. Therefore, in some hydraulic systems, a one-way throttle valve is installed on the oil line connecting the control chamber of the hydraulic spool valve and the pilot valve. When oil is filling the control chamber, the one-way throttle valve is open; when oil flows out of the control chamber, the one-way valve closes, allowing oil to flow out only through the damping orifice in the one-way throttle valve.

[0004] When the hydraulic spool valve returns from the left or right position to the neutral position, the oil in the previously filled control chamber flows out through the damping orifice on that side. Due to the damping effect of the orifice, the valve stem's return to the neutral position is buffered. However, when the valve stem moves from the neutral position to the left or right position, one side of the control chamber is filled with oil, while the oil in the other side of the control chamber flows out through the damping orifice. Since the outflow speed is affected by the damping orifice, it affects the valve stem's movement speed, which in turn affects the hydraulic spool valve's reversing start speed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the valve stem return-to-neutral buffer function of the existing hydraulic spool valve will affect the valve’s start-up speed. The present invention provides a hydraulic spool valve that has a buffering effect when the valve stem returns to the neutral position and does not have a damping delay effect when starting in reverse direction.

[0006] The technical solution of this invention to achieve its objective is as follows: A hydraulically controlled slide valve is constructed, comprising a valve body and a valve stem located within a valve stem cavity of the valve body. Both ends of the valve stem cavity are connected to control ports. The invention is characterized by a buffer device arranged at each end of the valve stem cavity. The buffer device includes a sleeve, which is fitted onto the outer side of the valve stem end and has a clearance fit with the cylindrical side surface of the valve stem end, forming a valve stem control cavity within the sleeve. The sleeve is capable of sliding relative to the valve stem axially. The sleeve is provided with a valve stem abutment and a valve body abutment. When the valve stem abutment abuts against the valve stem, it applies a force towards the center of the valve stem. The valve body abutment abuts against the valve body, restricting the displacement of the sleeve towards the center of the valve stem. A return spring is provided between the sleeve and the valve body, applying a spring force towards the center of the valve stem. A one-way throttle valve connecting the end of the valve stem cavity and the valve stem control cavity is provided on the sleeve.

[0007] In the hydraulic control slide valve of the present invention, the valve stem includes a main valve stem and an end rod fixedly connected and installed at the end of the main valve stem, and a cylindrical side surface on the valve stem for clearance fit with the sleeve is provided on the end rod.

[0008] In the hydraulic control slide valve of the present invention, the end rod is connected to the main valve stem by a threaded connection. The end rod is provided with a positioning shoulder for contacting the end face of the main valve stem. The part of the valve stem for abutting with the valve stem abutting part is the end face of the main valve stem, or the part of the valve stem for abutting with the valve stem abutting part is the stepped side of the positioning shoulder facing away from the end face of the main valve stem.

[0009] In the hydraulic control slide valve of the present invention, a regular polygonal countersunk hole is provided on the end face of the end rod facing away from the main valve rod.

[0010] In the hydraulic control slide valve of the present invention, a radial channel is provided on the sleeve at the part between the valve stem abutment and the valve body abutment, which penetrates the inside and outside of the sleeve.

[0011] In the hydraulically controlled slide valve of the present invention, the one-way throttle valve includes a one-way valve seat fixedly connected to the axial end of the sleeve, a spring seat fixedly installed in the inner cavity of the one-way valve seat, a one-way valve core installed in the inner cavity of the one-way valve formed by the one-way valve seat and the spring seat, and a spring disposed between the one-way valve core and the spring seat; a damping hole is provided on the one-way valve core or the one-way valve seat to connect the inner cavity of the one-way valve with the end of the valve stem cavity.

[0012] In the hydraulic control slide valve of the present invention, the one-way valve seat and the sleeve are integrally formed, or the one-way valve seat is fixedly connected to the sleeve by external threads.

[0013] In the hydraulic control slide valve of the present invention, the one-way valve core is in the shape of a round steel ball, the spring seat is fixedly installed in the one-way valve seat by external thread, and the damping hole is arranged on the circumferential side of the one-way valve seat.

[0014] In the hydraulic control slide valve of the present invention, the one-way valve core has a cylindrical side surface that mates with the inner cavity of the one-way valve seat and a conical portion that mates with the oil inlet channel on the one-way valve seat, and the damping orifice is arranged at the top of the conical portion.

[0015] In the hydraulic control slide valve of the present invention, a step is provided on the circumferential side of the sleeve, and the return spring is a helical spring and is fitted on the circumferential side of the sleeve, with one end of the return spring abutting against the step side of the circumferential side of the sleeve.

[0016] Compared with the prior art, the hydraulic control slide valve of the present invention has a buffering effect when the valve stem returns to the neutral position, and can respond quickly when the valve stem moves to the left or right position to start. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the hydraulically controlled slide valve of the present invention.

[0018] Figure 2 This is a schematic diagram of the buffer device in the hydraulically controlled slide valve of the present invention.

[0019] Figure 3 This is a schematic diagram of the second structure of the buffer device in the hydraulically controlled slide valve of the present invention.

[0020] Figure 4 This is a schematic diagram of the third structure of the buffer device in the hydraulically controlled slide valve of the present invention.

[0021] Component names and serial numbers in the diagram: Valve body 1, control port 11, valve stem cavity 12, valve stem 2, main valve stem 21, end valve stem 22, cylindrical side 221, regular polygonal countersunk hole 222, positioning shoulder 223, valve stem control cavity 23, sleeve 3, valve stem abutment 31, valve body abutment 32, radial channel 33, stepped side 34, return spring 4, one-way throttle valve 5, one-way valve seat 51, one-way valve core 52, spring seat 53, retaining ring 54, spring 55, one-way valve seat inner cavity 56, damping hole 57, oil inlet channel 58. Detailed Implementation

[0022] The specific implementation plan is described below with reference to the attached diagram.

[0023] like Figure 1 As shown, the hydraulic control slide valve in this example includes a valve body 1, a valve stem 2 located in the valve stem cavity of the valve body, and a buffer device arranged at each end of the valve stem cavity. The two ends of the valve stem cavity are respectively connected to the control port 11.

[0024] The valve stem 2 includes a main valve stem 21 and an end rod 22 fixedly connected to the end of the main valve stem 21. Multiple shoulders are provided on the main valve stem 21 as needed so that when the valve stem is in the left, middle and right positions, the shoulders cooperate with the oil groove on the valve body 1 to form a passage or cut off the oil passage, so as to switch the oil passage connection state of the hydraulic control slide valve and realize the corresponding control function.

[0025] The end rod 22 is connected to the main valve stem 21 via a threaded connection. The end rod 22 has a locating shoulder 223 for contact with the end face of the main valve stem 21. A regular polygonal countersunk hole 22 is provided on the end face of the end rod 22 facing away from the main valve stem 21. The regular polygonal countersunk hole 22 is typically an internal hexagonal hole. During assembly, the regular polygonal countersunk hole 22 is used to engage with an installation tool to rotate the end rod 22, thereby locking the end rod 22 and the main valve stem 21 into a threaded, fixed connection.

[0026] like Figure 1 Figure 2 As shown, the buffer device includes a sleeve 3, which is cylindrical with a stepped inner hole. One end of the sleeve 3 is fitted onto the outside of the valve stem end and forms a valve stem control cavity 23 within the sleeve with a clearance fit with the cylindrical side surface of the valve stem end. The cylindrical side surface 221 on the valve stem 2 for clearance fit with the sleeve 3 is provided on the end rod 22. Under the action of external force, the sleeve 3 can slide relative to the valve stem 2 in the axial direction of the valve stem. When the sleeve 3 moves relative to the valve stem, the volume of the valve stem control cavity 23 increases or decreases accordingly.

[0027] The sleeve 3 is provided with a valve stem abutment part 31 and a valve body abutment part 32, such as Figure 2 As shown, the valve stem abutment portion 31 is disposed on the inner wall of the sleeve 3, and is used to contact the stepped side of the valve stem 2. When the valve stem abutment portion 31 abuts against the valve stem 2, the sleeve 3 applies a force to the valve stem 2 in the direction of the middle of the valve stem. The part of the valve stem 2 that abuts against the valve stem abutment portion 31 can be the end face of the main valve stem 21, such as... Figure 2 As shown; the part on the valve stem that abuts against the valve stem abutment 31 can also be the stepped side of the positioning shoulder 223 on the end rod 22 facing away from the end face of the main valve stem 21, such as... Figure 3 As shown.

[0028] The valve body abutment part 32 is used to abut against the valve body 1 to limit the displacement of the sleeve 3 towards the middle of the valve stem. A return spring 4 is provided between the sleeve 3 and the valve body 1. The return spring 4 applies a spring force to the sleeve 3 in the direction towards the middle of the valve stem 2.

[0029] A radial channel 33 is provided on the sleeve 3 between the valve stem abutment portion 31 and the valve body abutment portion 32, penetrating both the inside and outside of the sleeve. When the valve stem 2 slides relative to the sleeve 3, the volume of the gap between the valve stem abutment portion 31 and the valve body abutment portion 32 and the valve stem 2 changes. Oil at the end of the valve stem cavity 12 enters the gap through the radial channel 33, or oil in the gap enters the end of the valve stem cavity through the radial channel 33, thus preventing a pressure difference between the gap and the valve stem cavity from affecting the movement of the valve stem.

[0030] The outer circumference of the sleeve 3 is provided with a step. The return spring 4 is a helical spring and is fitted on the outer circumference of the sleeve 3. One end of the return spring 4 abuts against the step side 34 on the outer circumference of the sleeve, and the other end abuts against the valve body 1. When the valve stem 2 is in the neutral position, the valve body abutting parts 32 of both ends of the sleeve abut against the valve body.

[0031] A one-way throttle valve 5 is provided on the sleeve 3, connecting the end of the valve stem cavity 12 and the valve stem control cavity 23. For example... Figure 2 As shown, the one-way throttle valve 5 includes a one-way valve seat 51 fixedly connected to the axial end of the sleeve 3, a spring seat 53 fixedly installed in the inner cavity of the one-way valve seat 51, a one-way valve core 52 installed in the one-way valve inner cavity formed by the one-way valve seat 51 and the spring seat 53, and a spring disposed between the one-way valve core 52 and the spring seat 53. The spring seat 53 is fixed in the inner cavity of the one-way valve seat 51 by a retaining ring 54.

[0032] The one-way valve core 52 has a cylindrical side that mates with the inner cavity of the one-way valve seat and a tapered portion that mates with the oil inlet channel 58 on the one-way valve seat 51. Both the one-way valve core 52 and the spring seat 53 have a connecting oil passage that connects the inner cavity of the one-way valve to the valve stem control cavity 23. A damping orifice 57 is located at the top of the tapered portion, with one end connected to the connecting oil passage in the one-way valve core and the other end connected to the oil inlet channel 58 of the one-way valve.

[0033] In some other implementations, such as Figure 4 As shown, the one-way valve core 52 is a round steel ball, the spring seat 53 is fixedly installed in the one-way valve seat 51 by external thread, and the damping hole 57 is arranged on the circumferential side of the one-way valve seat 51, with its two ends connected to the connecting oil passage of the spring seat and the end of the valve stem cavity 12, respectively.

[0034] like Figure 2 Figure 4 As shown, the one-way valve seat 51 is fixed in the inner hole at the end of the sleeve 3 by an external thread connection. In some other embodiments, the one-way valve seat 51 and the sleeve 3 can also be an integral structure, such as... Figure 3 As shown.

[0035] The working principle of the hydraulic control slide valve reversing buffer of the present invention is as follows: When there is no pressurized oil input at either of the control ports 11 at both ends of the valve body 1, the pressure at both control ports 11 is equal, and the one-way valve passages of the one-way throttle valves at both ends are closed. The pressure in the valve stem control chambers 23 at both ends of the valve stem 2 is the same. Under the elastic force of the return springs 4, the sleeves 3 at both ends abut against the valve body 1 at their respective valve body contact parts 32, maintaining a stable state. The valve stem contact parts 31 of the sleeves 3 at both ends abut against the valve stem 2, keeping the valve stem 2 in the neutral position. Figure 1 As shown.

[0036] When one end of the control port 11 at both ends of the valve body 1, for example Figure 1 When the control port 11 at the left end of the valve body 1 receives pilot pressure oil, the control port 11 at the right end of the valve body is usually connected to the hydraulic oil tank at this time. Its pressure is lower than that of the control port 11 at the left end. The pressure of the valve stem control chamber 23 at the left end of the valve stem 2 is greater than that of the valve stem control chamber 23 at the right end of the valve stem. The valve stem 2 begins to move to the right, and the volume of the valve stem control chamber 23 at the left end of the valve stem increases. The one-way valve core at the left end moves to the right and opens the one-way valve. The pressure oil from the control port 11 at the left end of the valve body enters the valve stem control chamber 23 at the left end of the valve stem through the oil inlet channel 58 of the one-way throttle valve, the one-way valve core 52, and the connecting oil passage in the spring seat 53. The oil in the valve stem control chamber 23 pushes the valve stem 2 to move to the right. At the same time as the valve stem 2 moves to the right, it comes into contact with the valve stem abutment part 31 of the right end sleeve 3, pushing the right end sleeve 3 to move to the right and compressing the right end return spring 4. The valve stem 2 moves to the right until its right end contacts and stops at the valve body 1, at which point the valve stem is at the right end of the valve stem cavity, and the hydraulic control spool valve operates in the left position. When the valve stem 2 moves to the right, the valve body abutment part 32 of the left end sleeve 3 abuts against the valve body 1 and remains stationary under the elastic force of the left-side return spring 4. (Left end sleeve...) As the valve stem 2 moves to the right, the valve stem control chamber 23 at the left end of the valve stem is filled with oil, while the volume of the valve stem control chamber 23 at the right end of the valve stem remains unchanged. The volume of the right end chamber of the valve stem chamber decreases, and the oil in the right end chamber of the valve stem chamber is directly discharged from the control port 11 at the right end of the valve body. The oil discharge process is not hindered by the damping orifice, so the valve stem can move into position quickly, enabling the hydraulic spool valve to respond and start quickly.

[0037] When the hydraulic control valve returns to the neutral position, for example, from the left position to the neutral position, the valve stem 2 moves from the rightmost end to the neutral position within the valve stem cavity 12. When the valve stem 2 returns to the neutral position, there is no pressure oil input at the control ports 11 at either end of the valve body 1. The valve stem 2 moves to the neutral position by the elastic force of the return spring 4. The movement process is as follows: The pressure at both ends of the valve body control port 11 is equal. The compressed return spring 4 at the right end pushes the right sleeve 3 to move to the left, and the right sleeve 3 drives the valve stem 2 to move to the left. When the valve stem 2 is at the right end of the valve stem cavity, the valve stem 2 and the valve stem abutment part 31 of the left sleeve 3 are no longer in contact, and there is no axial force between the valve stem 2 and the left sleeve 3 that has direct contact. When valve stem 2 moves to the left, the left end of the valve stem squeezes the oil in the valve stem control chamber 23 at the left end of the valve stem. Due to the damping effect of the damping orifice, some of the oil in the valve stem control chamber 23 at the left end flows into the left end chamber of valve stem chamber 12 through the damping orifice 57, forming a pressure difference. This pressure difference causes the left end one-way throttle valve to bear the leftward thrust of the oil in the valve stem chamber 23 at the left end. This thrust acts on the left end return spring 4 at the left end through the sleeve 3 at the left end, causing the return spring 4 at the left end to be compressed. Therefore, during the process of valve stem 2 returning to the neutral position from right to left, valve stem 2 has a reaction force transmitted by the left end return spring 4 through the left end sleeve 3 and the oil in the valve stem control chamber 23 at the left end, which plays a buffering role in the valve stem 2 returning to the neutral position to the left. As the valve stem 2 moves to the left, the length of the right-end return spring 4 increases, and the elastic force it provides decreases. The oil in the valve stem control chamber 23 at the left end flows out through the damping hole, reducing its volume. The left-end return spring 4 slowly releases from its maximum compressed position, pushing the left-end sleeve 3 to move to the right. Eventually, the valve stem contact parts of both the left and right sleeves come into contact with the valve body, and the force on the valve stem reaches equilibrium, placing it in the neutral position.

[0038] The process of the valve stem moving from the center position to the left in a hydraulic control spool valve is similar to the process of the valve stem moving from the center position to the right, and the process of the valve stem returning from the left to the right to the center position is similar to the process of the valve stem returning from the right to the left to the center position, so it will not be described in detail.

[0039] In this embodiment, when the valve stem moves to open the valve, the oil flowing through the valve stem cavity does not need to pass through the damping orifice, thus not hindering the movement of the valve stem and enabling the valve to respond quickly. When the valve stem returns to the neutral position, the oil flowing out of the corresponding valve stem control cavity generates damping, and the return spring at that end generates a force that acts on the valve stem, thus buffering the valve stem when it returns to the neutral position.

[0040] The hydraulic control spool valve in this embodiment has three working positions and can be applied to engineering machinery, such as for steering hydraulic systems, control of hydraulic cylinders in working devices, or control of hydraulic motors.

Claims

1. A hydraulically controlled slide valve, comprising a valve body and a valve stem located within a valve stem cavity of the valve body, wherein both ends of the valve stem cavity are respectively connected to control ports, characterized in that... A buffer device is arranged at each end of the valve stem cavity. The buffer device includes a sleeve, which is fitted onto the outside of the valve stem end and has a clearance fit with the cylindrical side of the valve stem end, forming a valve stem control cavity within the sleeve. The sleeve can slide relative to the valve stem in the valve stem axial direction. The sleeve is provided with a valve stem abutment and a valve body abutment. When the valve stem abutment abuts against the valve stem, it applies a force toward the center of the valve stem. The valve body abutment abuts against the valve body to limit the displacement of the sleeve toward the center of the valve stem. A return spring is provided between the sleeve and the valve body. The return spring applies a spring force toward the center of the valve stem to the sleeve. A one-way throttle valve connecting the valve stem cavity end and the valve stem control cavity is provided on the sleeve.

2. The hydraulically controlled slide valve according to claim 1, characterized in that... The valve stem includes a main valve stem and an end rod fixedly connected to the end of the main valve stem. A cylindrical side of the valve stem for clearance fitting with the sleeve is provided on the end rod.

3. The hydraulically controlled slide valve according to claim 2, characterized in that... The end rod is connected to the main valve stem via a threaded connection. The end rod is provided with a positioning shoulder for contacting the end face of the main valve stem. The part of the valve stem that abuts against the valve stem abutment is the end face of the main valve stem, or the part of the valve stem that abuts against the valve stem abutment is the stepped side of the positioning shoulder facing away from the end face of the main valve stem.

4. The hydraulically controlled slide valve according to claim 3, characterized in that... The end face of the end rod facing away from the main valve stem is provided with a regular polygonal countersunk hole.

5. The hydraulically controlled slide valve according to claim 3, characterized in that... A radial channel is provided on the sleeve at the location between the valve stem abutment and the valve body abutment, penetrating both the inside and outside of the sleeve.

6. The hydraulically controlled slide valve according to any one of claims 1 to 5, characterized in that... The one-way throttle valve includes a one-way valve seat fixedly connected to the axial end of the sleeve, a spring seat fixedly installed in the inner cavity of the one-way valve seat, a one-way valve core installed in the inner cavity of the one-way valve formed by the one-way valve seat and the spring seat, and a spring disposed between the one-way valve core and the spring seat; a damping hole is provided on the one-way valve core or the one-way valve seat to connect the inner cavity of the one-way valve with the end of the valve stem cavity.

7. The hydraulically controlled slide valve according to claim 6, characterized in that... The one-way valve seat and the sleeve are an integral structure, or the one-way valve seat is fixedly connected to the sleeve by external threads.

8. The hydraulically controlled slide valve according to claim 6, characterized in that... The one-way valve core is in the shape of a round steel ball, the spring seat is fixedly installed in the one-way valve seat by external thread, and the damping hole is arranged on the circumferential side of the one-way valve seat.

9. The hydraulically controlled slide valve according to claim 6, characterized in that... The one-way valve core has a cylindrical side that mates with the inner cavity of the one-way valve seat and a conical portion that mates with the oil inlet channel on the one-way valve seat, and the damping orifice is arranged at the top of the conical portion.

10. The hydraulically controlled slide valve according to claim 1, characterized in that... The sleeve has a step on its circumferential side surface. The return spring is a helical spring and is fitted on the circumferential side surface of the sleeve. One end of the return spring abuts against the step side surface of the circumferential side surface of the sleeve.

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