A liquid precision throttle valve based on a screw-type piezoelectric actuator

Abstract

The present invention discloses a liquid precision throttle valve based on a screw-type piezoelectric actuator, which includes a valve body, a valve core located inside the valve body, and a piezoelectric actuator. The piezoelectric actuator includes a piezoelectric actuator rotor, a piezoelectric actuator stator, and a driving module. The rotor is arranged in the threaded hole of the stator for threaded connection. The driving module applies a voltage signal to the piezoelectric actuator stator to excite the first-order flexural vibration of the stator. Through the frictional force between the threads, the rotor obtains a driving torque and rotates, thereby axially moving relative to the stator. The movement of the rotor drives the movement of the valve core, thereby realizing the control of the throttle valve. The microscopic vibration of the stator is converted into the macroscopic rotation of the rotor to drive the movement of the valve core, thereby realizing the precise control and rapid response of the throttle valve. At the same time, the movement of the valve core is completely controlled by the piezoelectric actuator and does not depend on elastic elements, enabling the active control of the flow rate. The throttle valve has a simple structure, is not affected by electromagnetic interference, and the valve core has a fast response speed.

Description

Technical Field

[0001] The invention relates to a throttle valve for controlling liquid flow, in particular to a liquid precision throttle valve based on a screw-type piezoelectric driver. Background Art

[0002] The throttle valve has the characteristics of large flow adjustment range, smooth flow-pressure difference change, small adjustment torque, and sensitive action. It plays the role of controlling or adjusting the speed of the actuator in the hydraulic control system.

[0003] The performance of the throttle valve's electronically controlled drive device is directly related to the valve's performance indicators. Currently, the commonly used electronically controlled drive devices in throttle valves include electromagnet type, stepper motor and torque motor type, which have problems such as slow dynamic response, small linear range, poor stability, low efficiency and weak load-bearing capacity.

[0004] With the rapid development of modern industrial automation, higher requirements are placed on hydraulic control valves. Throttle valves should have the characteristics of high precision, fast response, low power, small and flexible size, strong anti-electromagnetic interference ability, and high safety performance.

[0005] The rise of new intelligent materials has provided new ideas for the development of hydraulic control valves. Among them, piezoelectric ceramic materials have been used in hydraulic control valves. Most of them use the inverse piezoelectric effect of piezoelectric ceramics to generate unidirectional rigid strain, and drive the valve core movement through the rigid deformation output displacement, including dual piezoelectric chip type drivers and piezoelectric stack type drivers. In the prior art, for example, Chinese patent application No. 2015107504333 discloses a deflection plate jet electro-hydraulic servo valve based on a piezoelectric structure, in which bending deformation is generated by a piezoelectric dual chip, transmitted to a connecting rod, and a reaction rod is driven by the connecting rod, thereby forming a relative displacement between the reaction rod and the jet assembly, generating a jet-level pressure difference, and driving the valve core to move. The dual piezoelectric chip type driver has a small output driving force, and a flexible hinge structure is required to amplify its output displacement. The structure is complex and has high requirements on processing accuracy; for example, Chinese patent application No. 2020106728446 discloses a piezoelectric-driven large-flow fuel valve, in which a cylindrical multi-layer stacked piezoelectric stack is used to directly drive the valve core. The piezoelectric stack type driver has a large output force, but there is a hysteresis problem. Summary of the Invention

[0006] Purpose of the invention: In view of the above shortcomings, the present invention provides a liquid precision throttle valve based on a screw-type piezoelectric drive with fast response and precise control.

[0007] Technical solution: To solve the above problems, the present invention adopts a liquid precision throttle valve based on a screw-type piezoelectric actuator, which includes a valve body, a valve core located inside the valve body, and a piezoelectric actuator. The piezoelectric actuator includes a piezoelectric actuator rotor, a piezoelectric actuator stator fixedly arranged inside the valve body, and a driving module. The piezoelectric actuator rotor is a screw, and the piezoelectric actuator stator is provided with a threaded hole. The piezoelectric actuator rotor is arranged in the threaded hole of the piezoelectric actuator stator for threaded connection. The driving module applies a voltage signal to the piezoelectric actuator stator to excite the first-order flexural vibration of the piezoelectric actuator stator. Through the frictional force between the threads, the piezoelectric actuator rotor obtains a driving torque and rotates, thereby axially moving relative to the piezoelectric actuator stator. One end of the piezoelectric actuator rotor always contacts the valve core, and an elastic component is connected between the valve core and the valve body. The elastic component applies a force to the valve core to approach the piezoelectric actuator rotor. When the piezoelectric actuator rotor moves towards the valve core, the valve core moves to close the throttle valve and compress the elastic component. When the piezoelectric actuator rotor moves away from the valve core, the elastic component pushes the valve core to move to open the throttle valve.

[0008] Further, the piezoelectric actuator stator includes four square sides. The driving module includes piezoelectric ceramics arranged on the sides of the piezoelectric actuator stator. Two relatively arranged piezoelectric ceramics are connected to the same-phase square-wave voltage signal, and the four piezoelectric ceramics are connected with two-phase square-wave voltage signals, and the two-phase square-wave voltage signals differ by 90° or -90°. A wear-resistant sheet is provided at the contact part between the valve core and the piezoelectric actuator rotor.

[0009] Further, the valve body includes a control cavity for accommodating the piezoelectric actuator and a liquid flow cavity for liquid circulation. The control cavity and the liquid flow cavity are isolated by a fixedly arranged sealing part. The valve core passes through the sealing part, with one end located in the control cavity and the other end located in the liquid flow cavity. The valve core moves relative to the sealing part. The end of the liquid flow cavity is provided with a throttle port and the side is provided with a liquid outlet. The valve core moves to open or close the throttle port. A sealing ring is provided between the valve core and the sealing part.

[0010] Further, the valve core includes a connecting part, a moving part, and a sealing part. One end of the connecting part contacts the piezoelectric actuator rotor, the other end of the connecting part is fixedly connected to the moving part, and the other end of the connecting part is connected to the sealing part through an elastic component. The sealing part is arranged at the end of the moving part. The cross-sectional shape of the sealing part includes a triangle, a U shape, and a rectangle. By adjusting the position of the sealing part relative to the throttle port, the opening degree of the throttle port can be adjusted.

[0011] Further, the elastic component is a spring. One end of the spring is connected to the valve core, and the other end of the spring is connected to the valve body. The spring is always in a compressed state and generates a thrust force on the valve core.

[0012] Further, a plurality of through holes communicating with the outside are formed in the control cavity of the valve body, and set screws are arranged in the through holes to fix the piezoelectric actuator stator.

[0013] Beneficial effects: Compared with the prior art, the remarkable advantage of the present invention is that by utilizing the inverse piezoelectric effect of piezoelectric materials, a voltage signal with a frequency above 20,000 Hz is applied to the stator elastomer, so that microscopic mechanical vibrations are generated on the surface of the stator elastomer. Through the frictional action between the stator and the rotor (or mover), the microscopic vibrations of the stator are converted into macroscopic rotation of the rotor (or mover), driving the valve core to move, thereby realizing precise control and rapid response of the throttle valve. At the same time, the movement of the valve core is completely controlled by the piezoelectric actuator and does not rely on elastic elements, enabling active control of the flow rate. The piezoelectric actuator has the advantages of low speed and large torque, fast response speed, no electromagnetic interference, flexible structure, easy miniaturization, and power-off self-locking. The throttle valve has a simple structure, is not affected by electromagnetic interference, and has a fast response speed of the valve core. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Shown is a schematic structural diagram of the liquid precision throttle valve in the present invention;

[0015] Figure 2 Shown is a schematic structural diagram of the screw-type piezoelectric actuator in the present invention;

[0016] Figure 3 Shown is a working principle diagram of the screw-type piezoelectric actuator in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] As Figure 1 Shown, a liquid precision throttle valve based on a screw-type piezoelectric actuator in this embodiment includes a valve cover 1, a valve body 2, a slotted long cylindrical end set screw 3, a piezoelectric actuator stator 4, a piezoelectric actuator rotor 5, a wear-resistant sheet 6, a valve core 7, a spring 8, a sealing ring 9, and a piezoelectric actuator drive module (drive power supply, controller); the piezoelectric actuator stator is a tetrahedral nut structure with threaded holes formed inside, and piezoelectric ceramics are respectively pasted on four outer side surfaces. Two opposite piezoelectric ceramic sheets are connected to the same-phase square wave voltage signal, and the two-phase voltage signals differ by 90°. After being energized, the first-order bending vibration of the piezoelectric actuator stator 4 is excited; the piezoelectric actuator rotor is a screw structure, and the piezoelectric actuator rotor is arranged in the threaded hole of the piezoelectric actuator stator 4 for threaded connection. The rotor contacts the stator at the position with the maximum displacement, and the rotor obtains a driving torque through the frictional force between the threads and thus rotates, and thus moves relative to the piezoelectric actuator stator 4.

[0018] The valve body 2 includes a control chamber for accommodating a piezoelectric actuator and a liquid flow chamber for liquid circulation. The control chamber and the liquid flow chamber are isolated by a fixedly arranged sealing portion. A valve cover 1 is provided at one end of the control chamber away from the sealing portion. The piezoelectric actuator is assembled in the control chamber of the valve body. The four outer sides of the piezoelectric actuator stator 4 with piezoelectric ceramics 10 attached are in close contact with the inner side of the valve body. One end of the rotor close to the valve cover is a free end. The rotor screw rotates along the internal thread of the stator nut, thereby forming a linear motion of protruding outward or retracting inward. The other end of the rotor tightly presses on the upper end surface of the valve core. The valve core is connected to the valve body through a spring.

[0019] One end of the valve core 7 passes through the sealing portion and is located in the control chamber, and the other end is located in the liquid flow chamber. The valve core moves relative to the sealing portion. The valve core 7 and the sealing portion are sealed through a sealing ring 9 to effectively isolate the liquid and prevent liquid leakage during the movement of the valve core. A throttle port is provided at the end of the liquid flow chamber and a liquid outlet is provided on the side. The valve core 7 includes a connecting portion, a moving portion, and a sealing portion. One end of the connecting portion contacts the piezoelectric actuator rotor 5, and the other end of the connecting portion is fixedly connected to the moving portion. Moreover, the other end of the connecting portion is connected to the sealing portion through a spring 8. The sealing portion is provided at the end of the moving portion and is conical. By adjusting the position of the sealing portion relative to the throttle port, the opening degree of the throttle port is adjusted. This embodiment is applicable to any form of conical throttle valve, including the shape of the sealing portion of the throttle groove at the valve core being triangular, U-shaped, rectangular, etc. During the adjustment process of the throttle port opening degree from zero to maximum, the spring is always in a compressed state. The upper end surface of the valve core is always in close contact with the end surface of the actuator rotor through the elastic force of the spring. At the contact position between the upper end surface of the valve core connecting portion and the piezoelectric actuator rotor 5, a wear-resistant sheet 6 is pasted. In this way, when the piezoelectric actuator rotor makes a spiral extension or retraction action, the friction between the top of the rotor and the valve core can be reduced, without affecting the action effect of the rotor, and at the same time, the wear between the top of the rotor and the top of the valve core is reduced. The piezoelectric actuator stator is fixed at the displacement node position on each outer side through a slotted long cylindrical end set screw.

[0020] The working process of the above liquid precision throttle valve is as follows:

[0021] According to the flow requirement of the hydraulic servo system where the throttle valve is located, the controller issues a control instruction, the piezoelectric actuator is powered on, and two opposite piezoelectric ceramic sheets on the four surfaces of the stator receive the same-phase square wave voltage signal, and the two-phase voltage signals differ by 90° or -90°. After being powered on, the first-order bending vibration of the stator is excited. The rotor contacts the position with the maximum displacement of the stator, and the rotor obtains a driving torque through the frictional force between the threads and thus rotates. Since the excitation power supply frequency is the ultrasonic frequency, the bending conversion in the four directions is very rapid, forming the continuous rotation of the rotor and being converted into an axial linear motion.

[0022] If the hydraulic servo system requires an increase in flow rate, the two-phase driving voltage of the piezoelectric driver differs by 90°, the piezoelectric driver rotor 5 moves to the left, and the valve core 7 moves to the left accordingly, increasing the opening of the throttle port, thereby increasing the flow area of the throttle valve, thereby achieving the purpose of increasing the throttle valve flow rate; in the adjustment process of increasing the flow rate, the spring 8 stretches, but is always in a compressed state, so that the piezoelectric driver rotor 5 maintains close contact with the wear-resistant plate 6 to ensure that the movement of the valve core 7 is controlled by the piezoelectric driver rotor 5; when the flow rate increases to the flow rate required by the hydraulic servo system, the piezoelectric driver is powered off, and the rotor 5 immediately stops rotating to maintain the current flow rate.

[0023] If the hydraulic servo system requires a flow reduction, the two-phase driving voltage of the piezoelectric driver differs by -90°, the piezoelectric driver rotor 5 moves to the right, and the valve core 7 moves to the right accordingly, reducing the opening of the throttle port, thereby reducing the flow area of the throttle valve, thereby achieving the purpose of reducing the throttle valve flow; in the flow reduction adjustment process, the spring 8 shortens and is in a compressed state, so that the piezoelectric driver rotor 5 maintains close contact with the wear-resistant plate 6 to ensure that the movement of the valve core 7 is controlled by the piezoelectric driver rotor 5; when the flow is reduced to the flow required by the hydraulic servo system, the piezoelectric driver is powered off, and the rotor 5 immediately stops rotating to maintain the current flow.

[0024] Figure 2 The figure shows the structure of the piezoelectric driver, which consists of two parts: a stator 4 and a rotor 5. The stator 4 is a tetrahedral nut structure, and piezoelectric ceramics 10 are attached to the four outer sides. The piezoelectric driver is fixed at the displacement node position of each outer side of the stator 4 by a slotted long cylindrical end tightening screw 3. The rotor 5 is a screw structure.

[0025] Figure 3 The figure shows the operating principle of a piezoelectric actuator. Two opposing piezoelectric ceramics 10 on each of the four faces of the stator 4 are connected to a square wave voltage signal of the same phase, with the two-phase voltage signals shifted by 90° or -90°. The arrows on the piezoelectric ceramics in the figure indicate the polarization direction of the piezoelectric ceramics. When power is applied, the stator 4's first-order bending vibration is excited, and the rotor 5 contacts the stator 4 at its maximum displacement. Friction between the threads generates a driving torque, causing the rotor 5 to rotate. The driving voltage frequency is the same as the stator's first-order bending resonant frequency. Because the excitation power supply frequency is ultrasonic, the bending in all four directions is converted very rapidly, resulting in continuous rotation of the rotor 5, which is then converted into axial linear motion.

Claims

1. A liquid precision throttle valve based on a screw-type piezoelectric actuator, characterized in that, The invention comprises a valve body (2), a valve core (7) located in the valve body, and a piezoelectric driver, wherein the piezoelectric driver comprises a piezoelectric driver rotor (5), a piezoelectric driver stator (4) fixedly arranged in the valve body, and a driving module, wherein the piezoelectric driver rotor (5) is a screw, the piezoelectric driver stator (4) is provided with a threaded hole, the piezoelectric driver rotor is arranged in the threaded hole of the piezoelectric driver stator for threaded connection, the driving module applies a voltage signal to the piezoelectric driver stator (4), excites the first-order bending vibration of the piezoelectric driver stator (4), and causes the piezoelectric driver stator (4) to vibrate by friction between the threads. The piezoelectric driver rotor (5) obtains a driving torque and rotates, thereby moving axially relative to the piezoelectric driver stator (4). One end of the piezoelectric driver rotor (5) is always in contact with the valve core (7). An elastic component is connected between the valve core (7) and the valve body. The elastic component applies a force to the valve core to approach the piezoelectric driver rotor (5). The piezoelectric driver rotor (5) moves in a direction close to the valve core, the valve core moves to close the throttle valve and compresses the elastic component. The piezoelectric driver rotor (5) moves in a direction away from the valve core, and the elastic component pushes the valve core to move to open the throttle valve.

2. The liquid precision throttle valve according to claim 1, characterized in that: The piezoelectric driver stator (4) includes four square sides, and the driving module includes a piezoelectric ceramic (10) arranged on the side of the piezoelectric driver stator (4), two piezoelectric ceramics (10) arranged opposite to each other are connected to the same-phase square wave voltage signal, and the four piezoelectric ceramics (10) are connected to two-phase square wave voltage signals, and the two-phase square wave voltage signals differ by 90° or -90°.

3. The liquid precision throttle valve according to claim 1, characterized in that, A wear-resistant sheet (6) is provided at the contact portion between the valve core (7) and the piezoelectric driver rotor (5).

4. The liquid precision throttle valve according to claim 1, characterized in that, The valve body (2) comprises a control chamber for accommodating a piezoelectric driver and a liquid flow chamber for liquid circulation, wherein the control chamber and the liquid flow chamber are isolated by a fixed sealing portion, one end of the valve core passes through the sealing portion and is located in the control chamber, and the other end is located in the liquid flow chamber, and the valve core moves relative to the sealing portion, a throttle port is provided at the end of the liquid flow chamber and a liquid outlet is provided at the side, and the throttle port is opened or closed by the movement of the valve core.

5. The liquid precision throttle valve according to claim 4, wherein, A sealing ring (9) is provided between the valve core (7) and the sealing portion.

6. The liquid precision throttle valve according to claim 4, characterized in that, The valve core (7) includes a connecting portion, a moving portion and a sealing portion, wherein one end of the connecting portion contacts the piezoelectric driver rotor (5), the other end of the connecting portion is fixedly connected to the moving portion, and the other end of the connecting portion is connected to the sealing portion via an elastic component, and the sealing portion is arranged at the end of the moving portion.

7. The liquid precision throttle valve according to claim 6, characterized in that, The cross-sectional shape of the sealing portion includes a triangle, a U shape, and a rectangle. The position of the sealing portion relative to the throttle port is adjusted, thereby adjusting the opening of the throttle port.

8. The liquid precision throttle valve according to claim 1, characterized in that, The elastic component is a spring (8), one end of the spring (8) is connected to the valve core (7), and the other end of the spring (8) is connected to the valve body (2). The spring (8) is always in a compressed state and generates a thrust on the valve core (7).

9. The liquid precision throttle valve according to claim 4, characterized in that, The control chamber of the valve body (2) is provided with a plurality of through holes communicating with the outside world, and set screws are arranged in the through holes, and the set screws fix the stator of the piezoelectric driver.

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