A valve core positive feedback steady-state hydraulic power structure

Abstract

The present invention discloses a valve core positive feedback steady-state hydraulic power structure, in which two sets of symmetrical frustum structures are provided at both ends of the valve core, and a plurality of oil holes are opened on the valve sleeve, forming a positive feedback steady-state hydraulic power structure; when the valve core is in motion, it interacts with the valve sleeve to generate vortexes, and fluids with different flow rates in the same flow cavity generate different thrusts on the wall of the flow cavity. This thrust is the positive feedback hydraulic power, which promotes the movement of the valve core. The valve core designed by the present invention with a positive feedback steady-state hydraulic power structure has the effect of reducing the thrust of the hydraulic power, 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 a positive feedback steady-state hydraulic power structure proposed by the present invention can solve the problem of high-frequency dynamic instability of the original valve core under high-pressure difference working conditions.

Description

Technical Field

[0001] The present invention relates to the technical fields of hydraulic control systems, large-scale 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 step, and this process is usually carried out through careful screening based on the system's flow requirements and dynamic response characteristics. However, it is worth noting that the various types of existing hydraulic valves have different ultimate power characteristics. The ultimate power has great restrictions on the valve's steady-state flow and dynamic response, 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 integrated automotive sheet metal die-casting machines are becoming increasingly stringent, especially in application scenarios where high 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 current technological conditions, improving a valve's ultimate power is generally achieved through optimizing the controller, electromechanical converter, and valve body structure. This ultimate power is determined by comparing its drive power to its power consumption. Increasing drive power is primarily achieved through optimizing the controller circuitry and control algorithms, as well as modifying the electromechanical converter's drive method. Regarding power consumption, the influence of fluid dynamics significantly outweighs factors like friction and springs. Therefore, most research on structural optimization design focuses on optimizing fluid dynamics.

[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 shaft shoulder guide at the oil inlet. However, the compensation effect of negative feedback hydraulic power after optimization is not obvious, and the overall negative feedback effect of hydraulic power 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 existing technology and propose a valve core positive feedback steady-state hydraulic force structure for improving the original hydraulic force of the outlet jet fluid domain to produce a larger negative feedback force, thereby improving the ultimate efficiency of the valve.

[0006] The purpose 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 it is in motion, and fluids with different flow rates in the same flow cavity generate different thrusts on the wall of the flow cavity. This thrust is positive feedback hydraulic power, which promotes the movement of the valve core.

[0007] Furthermore, two groups of symmetrical frustum structures are provided at both ends of the valve core, and a plurality of oil holes corresponding to the frustum wall surfaces are opened on the valve sleeve, forming a positive feedback steady-state fluid dynamic 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 fluid dynamic 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. The non-flowing cross-section of the valve sleeve is used to form a vortex, resulting in different oil flow rates on the walls on both sides of the flow chamber, forming a pressure difference. The oils of different pressures squeeze the valve core walls 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, generating 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 frustum structure with symmetrical ends; and the valve sleeve is obtained by drilling holes at corresponding frustum 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 vortex formation 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 dead chamber wall pressure and the valve port input pressure is obtained, and then the difference between the equivalent thrusts on 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 dynamic force.

[0013] Furthermore, the magnitude of the positive feedback hydraulic force is changed according to the valve core opening, thereby compensating for the negative feedback hydraulic force when the valve core moves and reducing the peak value of the hydraulic force.

[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, 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 generated by the present invention is significant. CFD simulations have shown that this 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 operating condition, the compensation effect is not significant, 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 extreme operating condition, the compensation force effect is significant, and the force on the valve core is medium-value positive feedback. Experiments have shown that this structure effectively reduces the negative feedback resistance characteristics of the hydraulic force and reduces the peak hydraulic force in the exiting 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. It can ensure that the valve core works within a certain flow-pressure combination working range and widen the valve's maximum power range to the valve body's pressure-resistant pressure point. The application of the proposed 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 figure is a cross-sectional diagram of 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 A magnified view of the structural details.

[0022] Figure 3 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] Figure 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 dynamic structure; 10. inner side surface of positive feedback steady-state fluid dynamic 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 with reference to the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not intended 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 generate 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"-like flow field with the valve sleeve when it is 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 cavity wall, forming a thrust that 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 cavity inlet is converted into kinetic energy and then into the pressure energy of the fluid at the cavity outlet. 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 Bernoulli's equation, when energy loss is ignored, the pressure of the fluid decreases as the flow rate increases. This principle provides theoretical support for creating a pressure difference through vortexes to generate positive feedback steady-state fluid force that promotes valve core movement.

[0033] The Bernoulli equation is as follows:

[0034]

[0035] Where p is the pressure at the target point in the fluid; ρ is the fluid density; v is the flow velocity at the target point; g is the acceleration due to gravity; h is the height of the plumb bob at the target point; ζ is the height of the plumb bob at the target point. w : Energy loss; C: constant, representing the total energy during fluid flow.

[0036] Specific structural design such as Figure 1 and Figure 2 The 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 diagram shows an enlarged view of the positive feedback steady-state hydraulic power structure. When the valve core 4 is in the left position (the diagram shows the left position; the principle is the same when it is in the right position), the hydraulic oil in the return oil chamber 2 returns from the right chamber to the left chamber in the hydraulic flow chamber formed by the valve core 4 and the valve sleeve 3. During this process, throttling occurs when the oil flows from the right chamber to the left chamber 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 velocity increases. Due to the non-flowability of the left chamber, the oil forms a vortex here, resulting in different oil flow velocities on the left and right walls of the left chamber. The oil with different flow velocities forms a pressure difference in the left chamber. The oil with different pressures squeezes the valve core walls on both sides of the left chamber to form a hydraulic force that acts as a positive feedback.

[0037] The specific valve core with positive feedback steady-state hydraulic power structure is as follows Figure 3 and Figure 4 Compared to a valve core without a positive feedback steady-state fluid dynamics structure, this one has two sets of symmetrical frustum structures 8 at both ends of the valve core. The valve sleeve is designed to have 20 oil holes 11 on the basic valve sleeve configuration, with the oil holes oriented in the direction of the frustum wall. This structure is a positive feedback steady-state fluid dynamics structure. When the valve core 4 and valve sleeve 3 cooperate and the valve core is opened to a certain extent, the flowing oil forms a vortex in the flow cavity formed by the two, causing the pressure on the outer side surface 9 of the positive feedback steady-state fluid dynamics structure to be greater than that on the inner side surface 10 of the positive feedback steady-state fluid dynamics structure, generating a fluid dynamics force that acts as a positive feedback.

[0038] The design of this invention utilizes a simple geometry, making the valve core easy to manufacture, requiring only simple turning or grinding. The valve sleeve can be prepared by conventional valve sleeve drilling. This design provides adaptive positive feedback hydraulic force according to the valve core opening, significantly compensating for the negative feedback hydraulic force during valve core movement without positive feedback, effectively reducing peak hydraulic force and significantly reducing negative feedback hydraulic force during mid-stroke.

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

[0040] q vor =q o -q direct

[0041] Among them, q o is the oil supply flow rate of the oil supply chamber 5, q direct The flow rate is the flow rate that flows 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] Where Δp is the pressure difference at the valve port, C d is the flow coefficient, x open is the valve core displacement, W is the area gradient, ρ is the fluid density, and the above formula W is given by Figure 6 Valve sleeve bore diameter x shown k The fluid velocity in the area near the outer side of the positive feedback steady-state hydrodynamic structure is very small and 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, the busbar length is x vor for:

[0044] x vor =(x dent -x open -x boos )sinθ

[0045] Among them, x dent is the total length of the valve sleeve groove, x open is the valve core displacement, x boos is the width of the cylindrical surface of the valve core boss, and θ is the inclination angle of the valve core boss. The flow cross-sectional area of ​​the non-flow cavity inlet is the side surface A of the frustum. vor for:

[0046] A vor =πx vor (x vor cosθ+2d c +2h′)

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

[0048] In the valve core positive feedback steady-state hydraulic structure, the fluid on the left wall hardly flows, and the flow velocity can be regarded as v1=0. The flow velocity of the fluid on the right wall is equivalent to:

[0049]

[0050] like Figure 8 and Figure 9 As shown in the figure, since the left flow cavity is a dead cavity, the fluid velocity acting on the A1 surface is 0, and its pressure is set to p1. The pressure p2 of the fluid acting on the A2 surface is derived by the Bernoulli equation;

[0051] Based on the flow pressure formula, p1 and valve port input pressure p in relationship;

[0052] The equivalent thrusts on the left and right walls of the positive feedback steady-state fluid dynamic structure are F1 and F2 respectively; among them, F2 is a in , oil flow rate q o , valve sleeve aperture x k , total length of valve sleeve groove x dent , valve core displacement x open , valve core boss cylindrical surface width x boos , boss height h, valve core diameter d c A function related to the inclination angle θ of the valve core boss. It can be expressed as:

[0053] F2=F{p in ,q o ,x k ,x dent ,x open ,x boos ,h,d c, θ}

[0054] The magnitude of the positive feedback hydraulic force is:

[0055] F h =F1-F2

[0056] Therefore, the magnitude of the positive feedback hydraulic force can be adjusted by adjusting the input pressure, flow rate and structural parameters.

[0057] The resultant force on the valve core can be expressed as:

[0058]

[0059] Where m is the valve core mass, b is the damping coefficient, k is the valve core stiffness, F f It is the total hydraulic power of the valve core.

[0060] When the valve core has no positive feedback hydraulic power structure, F f The function is negative feedback. When positive feedback fluid force is generated, F f is positively correlated with Δp and x open Function, F f The absolute value decreases, which is equivalent to x open The first-order coefficient k decreases, which means the equivalent stiffness of the valve core decreases, and its motion resistance also decreases, making the valve core easier to push. This increases the valve core drive efficiency while maintaining the same control current, thereby raising the hydraulic system power limit for normal valve core movement. Therefore, this invention has great potential for solving the problem of instability under high-pressure extreme conditions.

[0061] The above embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes 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: Two groups of symmetrical frustum structures are provided at both ends of the valve core, and a plurality of oil holes corresponding to the frustum wall surfaces are opened on the valve sleeve, forming a positive feedback steady-state fluid dynamic structure. Through the cooperation of the valve core and the valve sleeve, when the hydraulic oil returns, the valve core opens to a certain extent. In the hydraulic flow cavity formed by the valve core and the valve sleeve, the fluid on the left wall of the valve core positive feedback steady-state fluid dynamic structure is almost not circulated. When the oil flows through the opening between the valve sleeve and the valve core, throttling occurs, and pressure energy is converted into kinetic energy to form a flow field similar to a Venturi tube and an expander. The flowing oil uses the non-flowing cross-section of the valve sleeve to form a vortex in the flow cavity formed by the valve core and the valve sleeve, resulting in different oil flow velocities on the walls on both sides of the flow cavity, forming a pressure difference, so that the pressure on the outer side of the positive feedback steady-state fluid dynamic structure is greater than that on the inner side. The oils of different pressures squeeze the valve core walls on both sides of the flow cavity to form a fluid force that has a positive feedback effect, and the positive feedback fluid force promotes the movement of the valve core. This 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, generating a positive feedback fluid force that increases the valve opening. The wall fluid velocity is obtained based on the fluid flow rate involved in the vortex formation 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 dead chamber wall pressure and the valve port input pressure is obtained, and then the difference between the equivalent thrusts on 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 dynamic force.

2. 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 frustum structure with symmetrical ends; the valve sleeve is obtained by drilling holes at corresponding frustum positions based on the normal valve sleeve structure.

3. 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, compensating for the negative feedback hydraulic force when the valve core moves, thereby reducing the hydraulic force peak value.

4. The 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 the first-order coefficient of the valve core displacement, reducing the movement resistance and making the valve core easier to push.

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