Non-full-circle opening servo spool based on large flow condition optimization

Abstract

The present application relates to a kind of non full circle opening servo spool based on large flow condition optimization, the spool valve cover of one end fixed connection being equipped with the oil return port T of spool valve, the other end clearance fit connection spool valve spool, four shoulders are equipped on spool valve spool, shoulder C and shoulder F are equipped with 5 small annular grooves respectively, for balancing the pressure in clearance, increase the resistance when oil liquid passes, shoulder D and shoulder E adopt non full circle opening structure, i.e. the throttle groove D1 of same width, throttle groove D2 are opened respectively on the working edge of the two sides of shoulder D, the throttle groove E1 of same width, throttle groove E2 are opened respectively on the working edge of the two sides of shoulder E, for improving valve port flow capacity, the shape of throttle groove is the round rectangular of large radial width, small axial length, for ensuring that the valve port characteristics when spool valve spool generates slight displacement can match large flow condition.The present application can obtain better valve port characteristics under different conditions, ensure that servo system runs stably.

Description

Technical Field

[0001] This invention relates to a servo spool valve for a hydraulic system, specifically to a non-full-circumference open servo spool valve optimized for high-flow-rate conditions, which can achieve better valve port characteristics under high-flow-rate input conditions. Background Technology

[0002] As the pilot stage of a valve-controlled hydraulic cylinder servo system, the servo spool valve can adjust its opening and closing and opening size in a timely manner by introducing position feedback from the hydraulic cylinder, thereby further precisely controlling the displacement of the hydraulic cylinder.

[0003] The valve port characteristics of a servo spool valve directly affect the working pressure and flow rate output to the hydraulic cylinder. Simultaneously, the response speed and stability of the spool valve core during operation also influence the smoothness of the output from the valve-controlled hydraulic cylinder. When the working flow rate is high, significant pressure loss or flow obstruction is more likely to occur at the valve port. In the valve-controlled hydraulic cylinder, this can easily lead to excessively low movement speed or poor movement stability, resulting in noticeable chattering.

[0004] A common solution is to create a U-shaped or V-shaped throttling groove on the valve core shoulder to increase the flow area of ​​the valve core or adjust the damping when the oil flows through. When the working flow rate is large, a larger pressure loss or flow obstruction is more likely to occur at the valve port. In valve-controlled hydraulic cylinders, this can easily lead to excessively low movement speed or poor movement stability, resulting in obvious chattering.

[0005] For high-flow-rate conditions, this invention optimizes the shape of the throttling groove and the overflow method of the slide valve to ensure that the valve core obtains sufficient valve port characteristics with a small opening size, and avoids the influence of transient hydraulic forces and return oil back pressure on the stability of the circuit. Summary of the Invention

[0006] Based on the problems existing in the prior art, the present invention provides a non-full-circumference open servo spool valve optimized for high flow conditions. In view of the characteristics of high flow, the inner diameter of the spool valve body is matched and an asymmetrical throttling groove is set on the valve core shoulder, which can obtain better valve port characteristics under different operating conditions and ensure the stable operation of the servo system.

[0007] To achieve the above objectives, the technical solution of the present invention is: a non-full-circumference open servo spool valve optimized for high-flow-rate conditions, comprising a spool valve end cap, a spool valve body, and a spool valve core. One end of the spool valve body is fixedly connected to the spool valve end cap having a return port T, and the other end is clearance-fitted to the spool valve core. The spool valve core has four shoulders, wherein shoulders C and F each have five small annular grooves to balance the pressure within the gap and increase the resistance when the oil passes through. Shoulders D and E adopt a non-full-circumference open structure, that is, throttling grooves D1 and D2 of the same width are respectively opened on the working sides of shoulder D, and throttling grooves E1 and E2 of the same width are respectively opened on the working sides of shoulder E, to improve the flow capacity of the valve port. The shape of the throttling groove is a rounded rectangle with a large radial width and a small axial length, to ensure that the valve port characteristics when the spool valve core produces a small displacement can match the high-flow-rate conditions.

[0008] Furthermore, the shoulders D and E of the spool valve core cooperate with the oil ports B and A on the spool valve body to achieve the zero-opening working state when the spool valve is in the zero position.

[0009] Furthermore, the widths of the shoulders D and E of the spool valve core are matched according to the inner annular groove dimensions of the oil ports A and B of the spool valve body, in order to ensure that the opening of the spool valve core in the spool valve body is zero when it is in the zero position.

[0010] Furthermore, the spool valve core has a long blind hole at its center, in which a threaded hole is pre-drilled at the opening of the long blind hole for installing a throttling hole, and a radial through hole is opened between shoulder C and shoulder D, shoulder E and shoulder F for connecting oil port T. Two radial through holes are opened on the outside of shoulder F to release excess oil and reduce the impact of return oil back pressure on the stability of the spool valve core.

[0011] Furthermore, the axial length of the throttling grooves D1 to E2, or the size of their projected area in the normal direction of the flow field, is positively correlated with the flow rate through each valve port when the servo slide valve is working. That is, when driving an asymmetrical load, the axial lengths of the throttling grooves D2 and E1 are the same, the axial length of the throttling groove D1 is longer, the axial length of the throttling groove E2 is shorter, or no throttling groove is arranged there.

[0012] Furthermore, the slide valve end cap has a threaded through hole on the center line and is bolted to the rear end face of the slide valve body as the oil return port T of the servo slide valve.

[0013] Furthermore, the valve core of the spool valve is inserted from the front end face of the spool valve body and is installed concentrically.

[0014] The beneficial effects of this invention are:

[0015] As a key component of the valve-controlled hydraulic cylinder servo system, the servo spool valve features a non-full-circumference open design on its shoulder. Specifically, rectangular throttling grooves are created on both sides of shoulders D and E, which mate with pressure ports A and B. For the high-flow-rate input conditions emphasized in this invention, a wider rounded rectangle was chosen instead of the traditional U-shape, achieving a larger flow area and superior valve port characteristics within the limited valve spool dimensions. By opening a long blind hole and radial through-hole in the center of the valve spool, the return oil is guided to port T and the opening at the protruding end of the spool valve spool. This effectively reduces the return oil pressure under high operating flow rates, further minimizing the impact of return oil pressure and transient hydraulic forces on the stable operating state of the valve spool. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view of a servo slide valve;

[0017] Figure 2 This is a three-dimensional structural diagram of the valve core of a servo spool valve;

[0018] Figure 3 This is a schematic diagram of the oil flow direction in the long blind hole of the servo spool valve core;

[0019] Figure 4 These are enlarged views and axial cross-sectional views of the valve core.

[0020] Figure 5 yes Figure 4 A cross-sectional view of GG;

[0021] In the figure, 1 is the spool valve end cap, 2 is the spool valve body, 21 is the front end face of the valve body, 3 is the spool valve core, 31 is the threaded hole, and 32 is the long blind hole. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0023] like Figures 1 to 5As shown, this invention discloses a non-full-circumference open servo spool valve optimized for high-flow-rate operation, comprising a spool valve end cap 1, a spool valve body 2, and a spool valve core 3. One end of the spool valve body 2 is fitted with the spool valve end cap 1, while the other end 21 is completely open. The spool valve end cap 1 has a threaded hole serving as the return port T of the spool valve. The spool valve core 3 is inserted from the open end of the spool valve body 2 and is coaxially mounted with it. The shoulders C and F of the spool valve core 3 each have five small grooves that mate with the inner surface of the spool valve body 2 to achieve a gap seal. The shoulders D and E of the spool valve core 3 mate with the ports B and A on the valve body 2 to achieve a zero-opening working state when the spool valve is in the zero position. Rectangular throttling grooves with a small aspect ratio are made on the working sides D1, D2, E1, and E2 of the core 3 to optimize the flow capacity and valve characteristics. The axial length of the throttling groove is determined according to the actual flow rate of the working side. The zero-opening state refers to the zero position of the spool valve. The four grooves on both sides of the shoulder D and shoulder E are completely blocked by the spool valve body 2. The spool valve core 3 has a long blind hole 32, and four radial through holes are opened between the shoulders to connect with the long blind hole 32, so as to ensure that the return oil can quickly return to the oil tank and reduce the impact of the return oil back pressure on the working state of the spool valve.

[0024] The axial length of the throttling grooves D1 to E2, or the size of their projected area in the normal direction of the flow field, is positively correlated with the flow rate through each valve port when the servo slide valve is working. That is, when driving an asymmetrical load, the axial lengths of the throttling grooves D2 and E1 are the same, the axial length of the throttling groove D1 is longer, the axial length of the throttling groove E2 is shorter, or no throttling groove is arranged here.

[0025] The spool 3 has a long blind hole at its center. A threaded hole is pre-drilled at the opening of the long blind hole for installing a throttling hole. A radial through hole is opened between shoulder C and shoulder D, and between shoulder E and shoulder F for connecting to oil port T. Two radial through holes are opened on the outside of shoulder F to release excess oil and reduce the impact of return oil back pressure on the stability of the spool 3.

[0026] Taking the most commonly used asymmetric hydraulic cylinder as an example of the load, the oil ports A and B of the spool valve body 2 are respectively connected to the rod chamber and the rodless chamber of the asymmetric hydraulic cylinder, and the corresponding areas are S1 and S2 (S1 < S2). When the asymmetric hydraulic cylinder reciprocates, the flow rates through the working edges D1, D2, E1, and E2 are all different. Specifically, assuming that the output flow rate Q of the hydraulic source is constant, when the spool moves to connect the oil port P and the oil port A, the rod chamber of the hydraulic cylinder is filled with oil, and the moving speed of the piston rod is expressed as Q / S1. Then the flow rate through E1 is Q, and the flow rate through D1 is Q·S2 / S1; conversely, when the oil port P and the oil port B are connected, the moving speed of the piston rod is expressed as Q / S2, the flow rate through D2 is Q, and the flow rate through E2 is Q·S1 / S2. It can be seen that the flow rate ratio through the four working edges can be expressed as: D1:D2:E1:E2 = (S2 / S1):1:1:(S1 / S2). Therefore, when the radial width of the throttle groove is the same, the axial lengths of the throttle grooves D2 and E1 are the same, the axial length of the throttle groove D1 is relatively longer, and the axial length of the throttle groove E2 is shorter or no throttle groove is arranged here. Specifically, software such as AMEsim can be used to perform simulation calculations on throttle grooves with different equivalent areas to obtain throttle groove dimensions matching the load conditions.

[0027] As Figure 3 shown, regardless of whether the oil port P is connected to the oil port A or the oil port B, the returned oil fluid enters the long blind hole 32 through the radial through holes between the shoulders. Among them, part of the returned oil fluid returns to the fuel tank through the oil port T, and the rest of the oil fluid splashes back to the fuel tank through the two radial through holes outside the shoulder F. Specifically, due to the relatively large working flow rate of the working edge D1, the influence of the transient hydraulic force is more obvious. Therefore, a throttle hole can be considered to be installed at the threaded hole 31 reserved on the spool 3 to increase the damping when the spool moves backward and improve the working stability of the servo spool valve.

[0028] Although the present invention has been disclosed above with preferred embodiments, the embodiments are not used to limit the present invention. Any equivalent changes or modifications made without departing from the spirit and scope of the present invention also belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be defined by the content defined in the claims of this application.

Claims

1. A non-full bore open center servo spool valve based on high flow condition optimization, characterized by: The application relates to a servo valve, which comprises a spool end cover, a spool valve body and a spool valve core, the spool valve body is fixedly connected with the spool end cover provided with an oil return port T at one end, and the other end is gap-connected with the spool valve core, four shoulders are arranged on the spool valve core, wherein five small annular grooves are arranged on the shoulder C and the shoulder F respectively, the annular grooves are used for balancing the pressure in the gap and increasing the resistance of oil liquid, the shoulder D and the shoulder E adopt a non-full-circle opening structure, that is, throttle grooves D1 and D2 with the same width are respectively arranged on the working edges on the two sides of the shoulder D, and throttle grooves E1 and E2 with the same width are respectively arranged on the working edges on the two sides of the shoulder E, the throttle grooves are used for improving the flow capacity of the valve port, the shape of the throttle grooves is a circular-rectangular shape with large radial width and small axial length, and the valve port characteristics when the spool valve core produces a small displacement can match the large-flow working condition; the shoulder D and the shoulder E of the spool valve core are matched with the oil port B and the oil port A on the spool valve body, and are used for realizing the zero-opening working state when the spool valve is in zero position; a long blind hole is arranged in the center of the spool valve core, a threaded hole is pre-opened at the opening of the long blind hole for installing a throttle hole, a radial through hole is arranged between the shoulder C and the shoulder D and between the shoulder E and the shoulder F for connecting the oil port T, two radial through holes are arranged on the outer side of the shoulder F for releasing excess oil liquid and reducing the influence of the back pressure of the oil return on the stability of the spool valve core.

2. The non-full bore open center servo valve based on high flow condition optimization of claim 1, wherein: The width of the shoulder D and the shoulder E of the spool valve core is matched with the inner annular groove size of the oil port A and the oil port B of the spool valve body, so that the opening of the spool valve core in the spool valve body is zero opening when the spool valve is in zero position.

3. The non-full bore open center servo valve based on high flow condition optimization of claim 1, wherein: The axial length or the projection area size in the normal direction of the flow field of the throttle grooves D1-E2 is positively correlated with the flow size through each valve port when the servo spool valve works, that is, the axial length of the throttle groove D2 and the throttle groove E1 is consistent, the axial length of the throttle groove D1 is longer, and the axial length of the throttle groove E2 is shorter or the throttle groove is not arranged.

4. The high flow operating condition optimized partial arc servo valve of claim 1, wherein: The spool end cover is provided with a threaded through hole on the center line, and is installed on the rear end face of the spool valve body through bolts as the oil return port T of the servo spool valve.

5. The high flow operating condition optimized partial arc servo valve of claim 1, wherein: The spool valve core is inserted from the front end face of the spool valve body and is guaranteed to be concentrically installed.

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