Valve element positive feedback steady-state hydraulic power structure

Abstract

According to the positive feedback steady-state hydraulic power structure of the valve element, two sets of symmetrical circular truncated cone structures are arranged at the two ends of the valve element, a plurality of oil holes are formed in a valve sleeve, and the positive feedback steady-state hydraulic power structure is formed; when the valve element acts, the valve element interacts with the valve sleeve to generate vortex, fluid with different flow speeds in the same flow cavity generates different thrust on the wall face of the flow cavity, and the thrust is positive feedback fluid power to promote the valve element to move. The valve element of the positive feedback steady-state hydraulic power structure has the thrust effect of reducing hydraulic power, power saturation of an original structure at a steady-state high-pressure high-flow point can be avoided, it can be guaranteed that the valve element works in a certain flow pressure combined working interval, and the limit power range of the valve is widened to the pressure-resistant pressure point of the valve body; according to the application of the valve element of the positive feedback steady-state hydraulic power structure, the problem of high-frequency dynamic instability of the original valve element under the working condition of high pressure difference can be solved.

Description

Technical Field

[0001] The invention relates to the technical fields of hydraulic control systems, large equipment manufacturing, engineering machinery and the like, and in particular to a valve core positive feedback steady-state hydraulic power structure. Background Art

[0002] The selection of hydraulic valves is a crucial link, and the process is usually carefully screened based on the flow requirements and dynamic response characteristics of the system. However, it is worth noting that the existing types of hydraulic valves have different ultimate power characteristics. The ultimate power has great restrictions on the steady-state flow and dynamic response of the valve, and many special application scenarios are power-limited. Hydraulic systems with high power limits are used in many fields. For example, in the field of new energy vehicle manufacturing, the system performance requirements of automotive integrated sheet metal die-casting machines are becoming increasingly stringent, especially in application scenarios where large flow and high response speed are equally important. Only a few direct-acting voice coil motor proportional servo valves equipped with high-performance drive components and relatively high costs can meet these stringent conditions. Therefore, for the selection of hydraulic valves in certain specific application areas, improving the ultimate power has become an unavoidable technical challenge.

[0003] Under existing technical conditions, the ultimate power of the valve is generally improved from three aspects: the controller, the electromechanical converter and the valve body structure design optimization. The ultimate power of the valve depends on the comparison between its driving power and power consumption. From the perspective of improving driving power: it is mainly achieved by optimizing the controller circuit and control algorithm and changing the driving mode of the electromechanical converter; from the perspective of power consumption: the influence of fluid force is significantly greater than factors such as friction and springs, so most of the research on structural optimization design is aimed at optimizing fluid force.

[0004] For the optimization of steady-state hydraulic power structure, existing research focuses on optimizing the jet angle by the guide structure. Commonly used methods include valve core step guide, non-full-opening structure and setting a shaft shoulder guide at the oil inlet. However, the compensation effect on the negative feedback hydraulic power after optimization is not obvious, and the overall hydraulic power negative feedback effect is still significant. Therefore, a valve core and valve sleeve structure that can generate positive feedback hydraulic power will have great potential value in the development of the industry. Summary of the invention

[0005] The purpose of the present invention is to address the deficiencies of the prior art and propose a valve core positive feedback steady-state fluid dynamic structure for improving the original fluid dynamics of the outlet jet fluid domain to produce a larger negative feedback force, thereby improving the ultimate efficiency of the valve.

[0006] The objective of the present invention is achieved through the following technical solutions: a valve core positive feedback steady-state hydraulic power structure, in which the valve core interacts with the valve sleeve to generate vortex when in action, and fluids with different flow rates in the same flow cavity generate different thrusts on the wall of the flow cavity. The thrust is positive feedback hydraulic power, which promotes the movement of the valve core.

[0007] Furthermore, two groups of symmetrical frustum structures are arranged at both ends of the valve core, and a plurality of oil holes corresponding to the frustum wall are opened on the valve sleeve, forming a positive feedback steady-state fluid power structure.

[0008] Furthermore, through the cooperation between the valve core and the valve sleeve, when the valve core is opened to a certain extent, the flowing oil generates vortex in the flow cavity formed by the valve core and the valve sleeve, so that the pressure on the outer side of the positive feedback steady-state hydraulic structure is greater than that on the inner side.

[0009] Furthermore, when the hydraulic oil returns, in the hydraulic flow chamber formed by the valve core and the valve sleeve, throttling occurs when the oil flows through the opening between the valve sleeve and the valve core, and the pressure energy is converted into kinetic energy. A vortex is formed by utilizing the non-flowing cross-section of the valve sleeve, resulting in different oil flow velocities on the walls on both sides of the flow chamber, forming a pressure difference. Oils of different pressures squeeze the walls of the valve core on both sides of the flow chamber to form a hydraulic force that acts as a positive feedback.

[0010] Furthermore, the valve core positive feedback steady-state fluid dynamic structure converts the pressure energy of the fluid at the flow cavity inlet into kinetic energy and then into the pressure energy of the fluid at the flow cavity outlet, thereby generating a positive feedback fluid dynamic force that increases the valve port.

[0011] Furthermore, the valve core is formed by turning or grinding based on a normal valve core structure to obtain a truncated cone structure with symmetry at both ends; and the valve sleeve is obtained by drilling holes at corresponding truncated cone positions based on the normal valve sleeve structure.

[0012] Furthermore, the wall fluid velocity is obtained based on the fluid flow rate involved in the formation of the vortex and the side area of ​​the cone. The wall of the dead chamber is regarded as 0. Based on the principle of the Bernoulli equation, the relationship between the wall pressure of the dead chamber and the valve port input pressure is obtained, and then the difference between the equivalent thrusts of the left and right walls of the positive feedback steady-state fluid dynamic structure is obtained, which is the magnitude of the positive feedback fluid force.

[0013] Furthermore, the magnitude of the positive feedback hydraulic force is changed according to the valve core opening, so as to compensate for the negative feedback hydraulic force when the valve core moves and reduce the hydraulic force peak value.

[0014] Furthermore, when the valve core has no positive feedback hydraulic power structure, the total hydraulic power of the valve core acts as negative feedback. Based on the positive feedback steady-state hydraulic power structure, the absolute value of the total hydraulic power of the valve core is reduced, which is equivalent to a reduction in the first-order coefficient of the valve core displacement, thereby reducing the movement resistance and making the valve core easier to push.

[0015] Beneficial effects of the present invention:

[0016] 1. A vortex generating structure relying on the joint action of valve core and valve sleeve is designed to improve the problem of large negative feedback of the original hydraulic force in the outlet jet fluid domain, which is beneficial to improve the ultimate power of the valve.

[0017] 2. The positive feedback hydraulic force of the present invention is effective. Through CFD simulation, it is found that the structure can effectively increase the positive feedback force of the valve core; when the valve core is in a low-pressure, low-flow, and low-power condition, the compensation effect is not obvious, and the force on the valve core is still mainly small-value negative feedback; when the valve core is in a high-pressure, high-flow limit condition, the compensation force effect is obvious, and the force on the valve core is medium-value positive feedback; the present invention has proved through experiments that the structure effectively reduces the negative feedback resistance characteristics of the hydraulic force and reduces the peak value of the hydraulic force in the outgoing fluid domain.

[0018] 3. The designed valve core with positive feedback structure has the effect of reducing the thrust of hydraulic force, which can avoid the power saturation of the original structure at the steady-state high-pressure and high-flow point, and can ensure that the valve core works in a certain flow-pressure combination working range to widen the valve limit power range to the valve body pressure resistance point. The application of the valve core with positive feedback structure can solve the problem of high-frequency dynamic instability of the original valve core under high-pressure difference conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 The schematic cross-sectional view shows a valve core designed with a valve core positive feedback steady-state hydraulic power structure installed on a valve body.

[0021] Figure 2 for Figure 1 Enlarged view of structural details.

[0022] Figure 3 It is a schematic diagram of the valve core designed with a positive feedback steady-state hydraulic power structure.

[0023] Figure 4 For Figure 3 Schematic diagram of the valve sleeve with special openings for the middle valve core.

[0024] Figure 5 It is a flow diagram of oil flowing through the positive feedback steady-state hydraulic structure.

[0025] Figure 6 Schematic diagram of valve sleeve aperture.

[0026] Figure 7 Schematic diagram of the cross-sectional dimensions of the positive feedback steady-state fluid dynamic structure.

[0027] Figure 8 Schematic diagram of positive feedback steady-state fluid dynamic structural force analysis.

[0028] Fig. 9 Schematic diagram of the equivalent thrust on the wall of a positive feedback steady-state hydrodynamic structure.

[0029] In the figure, 1. valve body; 2. oil return chamber; 3. valve sleeve; 4. valve core; 5. oil supply chamber; 6. output oil chamber; 8. frustum structure; 9. outer side surface of positive feedback steady-state fluid power structure; 10. inner side surface of positive feedback steady-state fluid power structure; 11. oil hole. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific implementation examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] like Figure 1 As shown, the present invention designs a valve core positive feedback steady-state fluid dynamic structure that relies on the interaction between the valve core and the valve sleeve, which is used to improve the original fluid dynamics of the outlet jet fluid domain to produce a large negative feedback force, thereby improving the valve's ultimate efficiency. The design of the vortex generating structure is inspired by the kinetic energy conversion principle of the Venturi tube and the expander. By optimizing the valve core structure, it forms a "Venturi tube / expander" flow field with the valve sleeve when in motion, thereby generating vortices. The different pressures of fluids with different flow rates in the same flow cavity lead to different thrusts on the wall of the flow cavity, which promotes the movement of the valve core (i.e., positive feedback fluid dynamics). From the perspective of energy conversion, the pressure energy of the fluid at the inlet of the flow cavity is converted into kinetic energy and then into the pressure energy of the fluid at the outlet of the flow cavity, that is, the kinetic energy of the outlet fluid is converted into pressure energy to generate a positive feedback force that increases the valve port.

[0032] According to the Bernoulli equation, when energy loss is ignored, the pressure of the fluid decreases as the flow rate of the fluid increases. This principle provides theoretical support for creating a pressure difference through vortexes to generate a positive feedback steady-state fluid force that promotes the movement of the valve core.

[0033] The Bernoulli equation is as follows:

[0034]

[0035] in, : pressure at the target point in the fluid; ρ: fluid density; v: flow velocity at the target point; g: gravitational acceleration; h: plumb height at the target point; : Energy loss; C: constant, representing the total energy during fluid flow.

[0036] The specific structural design is as follows: Figure 1 and Figure 2The key to generating positive feedback thrust is to form a vortex in the valve cavity of the valve body 1, and to form a vortex by utilizing the non-flowing cross section of the valve sleeve 3; the principle of vortex formation is as follows Figure 2 The enlarged diagram of the positive feedback steady-state hydraulic power structure is shown. When the valve core 4 is in the left position (the figure shows the left position, and the principle is the same when it works in the right position), the hydraulic oil in the return oil chamber 2 flows from the right chamber to the left chamber in the hydraulic flow chamber formed by the valve core 4 and the valve sleeve 3. In this process, when the oil flows from the right chamber to the left chamber, it will throttle when it flows through the opening between the valve sleeve 3 and the valve core 4. The pressure energy of the oil is converted into kinetic energy, and the flow speed increases. Due to the non-flowability of the left chamber, the oil forms a vortex here, resulting in different oil flow rates on the left and right walls of the left chamber. The oil with different flow rates forms a pressure difference in the left chamber, and the oil with different pressures squeezes the valve core walls on both sides of the left chamber to form a hydraulic force that plays a positive feedback role.

[0037] The specific valve core with positive feedback steady-state hydraulic power structure is as follows Figure 3 and Figure 4 Compared with the valve core without positive feedback steady-state hydraulic power structure, it has two sets of symmetrical truncated cone structures 8 at both ends of the valve core, and the valve sleeve is designed to open 20 oil holes 11 on the basic valve sleeve configuration, and the direction of the oil holes corresponds to the truncated cone wall. This structure is a positive feedback steady-state hydraulic power structure. After the valve core 4 and the valve sleeve 3 cooperate, when the valve core is opened to a certain extent, the flowing oil can form a vortex in the flow cavity formed by the two, so that the pressure on the outer side surface 9 of the positive feedback steady-state hydraulic power structure is greater than the inner side surface 10 of the positive feedback steady-state hydraulic power structure, and a hydraulic force with a positive feedback effect is generated.

[0038] The design of the present invention adopts a simple geometric shape, the valve core is easy to process and can be formed by simple turning or grinding, and the valve sleeve can be prepared by drilling holes in a conventional valve sleeve. The design can provide an adaptive positive feedback hydraulic force according to the valve core opening, and can significantly compensate for the negative feedback hydraulic force when the valve core moves without positive feedback, and can effectively reduce the peak value of the hydraulic force, and significantly reduce the negative feedback hydraulic force in the middle of the stroke.

[0039] The present invention is to obtain the mechanism and influencing factors of positive feedback hydraulic force from the perspective of theoretical analysis, take the positive feedback steady-state hydraulic force structure as the research object, and construct a mathematical model of the relationship between the size of positive feedback hydraulic force and basic parameters such as oil supply pressure, valve core opening and structural size. Figure 5 As shown, the fluid flow rate involved in the formation of the vortex for:

[0040]

[0041] in, is the oil supply flow rate of the oil supply chamber 5, The flow rate is the flow rate directly out of the output oil chamber 6 of the valve sleeve. The flow rate can be calculated based on the valve port pressure difference:

[0042]

[0043] in, is the valve port pressure difference, is the flow coefficient, is the valve core displacement, is the area gradient, is the fluid density, and the above formula W is given by Figure 6 Sleeve bore diameter shown The fluid velocity in the area near the outer side of the positive feedback steady-state fluid dynamic structure is very small, which can be regarded as a dead cavity. The fluid flow section of the dead cavity is the side of the cone, such as Figure 7 As shown, busbar length for:

[0044]

[0045] in, is the total length of the valve sleeve groove, is the valve core displacement, is the cylindrical width of the valve core boss, is the inclination angle of the valve core boss. The flow cross-sectional area of ​​the non-flow cavity inlet is the side of the truncated cone. for:

[0046]

[0047] in It is the height of a certain point on the right wall of the valve core positive feedback steady-state fluid dynamic structure. It is the inner diameter of the valve core corresponding to the step.

[0048] The left wall of the valve core positive feedback steady-state hydraulic structure has almost no fluid flow, and the flow rate can be regarded as , the fluid velocity on the right wall is equivalent to:

[0049]

[0050] like Figure 8 and Fig. 9 As shown, since the left flow cavity is a dead cavity, the effect on The fluid velocity on the surface is 0, and its pressure is set to , derived from the Bernoulli equation, Surface fluid pressure for:

[0051]

[0052] Combining the above formula with the flow pressure formula, we can know And valve port input pressure The relationship is:

[0053]

[0054] The equivalent thrusts on the left and right walls of the positive feedback steady-state fluid dynamic structure are:

[0055]

[0056]

[0057] In the above formula, F 2 The expression is The integral of Eliminate, combine the previous formulas and finally get F 2 Simplified into a single value with input pressure , Oil flow , Valve sleeve aperture , Total length of valve sleeve groove , valve core displacement , the width of the cylindrical surface of the valve core boss , boss height h, valve core diameter A function related to the inclination angle θ of the valve core boss. It can be expressed as:

[0058]

[0059] The positive feedback hydraulic force is:

[0060]

[0061] Therefore, the size of the positive feedback hydraulic force can be adjusted by adjusting the input pressure, flow rate and structural parameters.

[0062] The resultant force on the valve core can be expressed as:

[0063]

[0064] Where m is the valve core mass, b is the damping coefficient, and k is the valve core stiffness. It is the total hydraulic power of the valve core.

[0065] When the valve core has no positive feedback hydraulic power structure The effect is negative feedback. When positive feedback fluid force is generated, is positively correlated with and The function of The absolute value decreases, which is equivalent to The first-order coefficient k is reduced, that is, the equivalent stiffness of the valve core is reduced, and its movement resistance is also reduced, making the valve core easier to push, increasing the valve core driving efficiency under the condition of unchanged control current, and thus improving the power limit of the hydraulic system for the normal movement of the valve core. Therefore, the present invention has great potential for solving the problem of instability under high-pressure extreme working conditions.

[0066] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A valve core positive feedback steady-state hydraulic power structure, characterized in that: The valve core of this structure interacts with the valve sleeve to generate vortex when in motion. Fluids with different flow rates in the same flow cavity generate different thrusts on the wall of the flow cavity. The thrusts are positive feedback fluid forces, which promote the movement of the valve core.

2. A valve core positive feedback steady-state hydraulic power structure according to claim 1, characterized in that: Two groups of symmetrical frustum structures are arranged at both ends of the valve core, and a plurality of oil holes corresponding to the frustum wall are opened on the valve sleeve to form a positive feedback steady-state fluid power structure.

3. A valve core positive feedback steady-state hydraulic power structure according to claim 2, characterized in that: Through the cooperation of the valve core and the valve sleeve, when the valve core is opened to a certain extent, the flowing oil generates vortex in the flow cavity formed by the valve core and the valve sleeve, so that the pressure on the outer side of the positive feedback steady-state fluid power structure is greater than that on the inner side.

4. A valve core positive feedback steady-state hydraulic power structure according to claim 1, characterized in that: When the hydraulic oil returns, in the hydraulic flow chamber formed by the valve core and the valve sleeve, throttling occurs when the oil flows through the opening between the valve sleeve and the valve core. The pressure energy is converted into kinetic energy, and a vortex is formed by utilizing the non-flowing cross-section of the valve sleeve, resulting in different oil flow velocities on the walls on both sides of the flow chamber, forming a pressure difference. Oils of different pressures squeeze the walls of the valve core on both sides of the flow chamber to form a hydraulic force that acts as a positive feedback.

5. The valve core positive feedback steady-state hydraulic power structure according to claim 1, characterized in that: The structure converts the pressure energy of the fluid at the flow cavity inlet into kinetic energy and then into the pressure energy of the fluid at the flow cavity outlet, thereby generating a positive feedback fluid force that enlarges the valve port.

6. A valve core positive feedback steady-state hydraulic power structure according to claim 1, characterized in that: The valve core is formed by turning or grinding based on a normal valve core structure to obtain a truncated cone structure with symmetry at both ends; the valve sleeve is obtained by drilling holes at corresponding truncated cone positions based on the normal valve sleeve structure.

7. A valve core positive feedback steady-state hydraulic power structure according to claim 1, characterized in that: The wall fluid velocity is obtained based on the fluid flow rate involved in the formation of the vortex and the side area of ​​the cone. The wall of the dead chamber is regarded as 0. Based on the principle of the Bernoulli equation, the relationship between the wall pressure of the dead chamber and the valve port input pressure is obtained, and then the difference between the equivalent thrusts of the left and right walls of the positive feedback steady-state fluid power structure is obtained, which is the size of the positive feedback fluid power.

8. The valve core positive feedback steady-state hydraulic power structure according to claim 1, characterized in that: The magnitude of the positive feedback hydraulic force is changed according to the valve core opening, so as to compensate for the negative feedback hydraulic force when the valve core moves and reduce the hydraulic force peak value.

9. A valve core positive feedback steady-state hydraulic power structure according to claim 1, characterized in that: When the valve core has no positive feedback hydraulic power structure, the total hydraulic power of the valve core acts as negative feedback. Based on the positive feedback steady-state hydraulic power structure, the absolute value of the total hydraulic power of the valve core is reduced, which is equivalent to a first-order coefficient of the valve core displacement, reducing the movement resistance and making the valve core easier to push.

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