CN105370958B - A kind of Piezoelectric Ceramic diaphragm type servo valve - Google Patents

Abstract

The invention discloses a piezoelectric ceramic driven membrane servo valve, which comprises an upper valve body and a lower valve body, a thin film is arranged between the upper valve body and the lower valve body, and a cylindrical balance oil is formed between the upper valve body and the thin film. An annular throttling oil chamber is formed between the diaphragm and the lower valve body, the balance oil chamber communicates with the throttling oil chamber, and a ejector rod is vertically connected between the upper valve body and the balance oil chamber, and one end of the ejector rod is connected to the diaphragm The distance or contact is set at intervals, and the other end is provided with piezoelectric ceramics for pushing the ejector rod to move; the beneficial effect of the present invention is: through precise control of the throttling gap, precise and active control of pressure and flow can be realized. By setting the center of the film It is a central island type, the central island type is rigid, and the surrounding deformation area is flexible, which improves the dynamic frequency of the film and improves the control accuracy of the throttling gap. The whole device has simple structure, reliable function and low manufacturing cost.

Description

A Piezoelectric Ceramic Drive Thin Film Servo Valve

technical field

The invention relates to a servo valve, in particular to a piezoelectric ceramic driven thin-film servo valve.

Background technique

At present, the application fields of hydraulic servo control systems are becoming wider and wider, which puts forward extremely high requirements for the performance of electro-hydraulic servo valves: high frequency response, high precision, simplicity and reliability, etc. The traditional electromagnetic servo valve can no longer meet the high-response control requirements, so the development of a new type of high-response active control servo valve has become a difficult problem in the field of hydraulic servo control.

In the research and development process of many new micro-displacement and high-response drivers, piezoelectric ceramic materials have become the preferred driving components in precision positioning systems because of their advantages such as small size, high energy density, high resolution, and fast frequency response. At the same time, due to the small output displacement, limited bearing capacity and poor shear resistance of piezoelectric ceramics, their application in fast and high-precision positioning systems is limited.

Controllable servo valves mainly include slide valves and film servo valves. The structure of the spool valve is relatively complex, and the required driving displacement is relatively large. There have been design cases of servo spool valves based on piezoelectric ceramic control. The thin-film servo valve has a relatively simple structure, and can be designed with upper and lower oil chambers to realize differential control or feedback control. One of the oil chambers is used as a throttling oil chamber, and the other oil chamber is used as a pressure balance oil chamber, and the hydraulic oil after throttling is introduced, which can greatly reduce the pressure difference on both sides of the membrane.

There are mainly two kinds of existing film throttle valves. One is a double oil chamber differential double output form, which can be used in the opposite oil chambers of hydrostatic bearings to improve the stability and load capacity of the spindle; the other is a single output form with feedback oil chambers, which can increase outlet pressure and flow stability. The above two types of film throttle valves cannot realize active servo control, and cannot actively control the pressure and flow at the outlet of the throttle valve.

Most of the existing piezoelectric ceramic-driven servo valves use elastic materials such as disc springs to ensure the two-way movement of the valve plate (valve stem), thereby increasing the force on the piezoelectric ceramics. Therefore, it is necessary to use large-volume piezoelectric materials. higher cost.

After searching, there is no design case of membrane servo valve with pressure balance oil cavity directly driven by piezoelectric ceramics.

Contents of the invention

The object of the present invention is to provide a piezoelectric ceramic driven membrane servo valve with high frequency response and controllable output flow.

In order to achieve the above object, the present invention adopts the following technical solutions:

A piezoelectric ceramic driven membrane servo valve, including an upper valve body and a lower valve body, a thin film is arranged between the upper valve body and the lower valve body, a cylindrical balance oil chamber is formed between the upper valve body and the thin film, and the thin film and the lower valve body An annular throttling oil cavity is formed between the lower valve body, the gap between the film and the lower valve body is the throttling gap, the balance oil cavity is connected with the throttle oil cavity, and the upper valve body and the balance oil cavity are vertically connected There is a ejector rod, one end of the ejector rod is at a set distance or in contact with the film, and the other end is provided with a piezoelectric ceramic for pushing the ejector rod to move; the piezoelectric ceramic is connected to the piezoelectric ceramic driver, and the displacement of the ejector rod is actively controlled through the piezoelectric ceramic , and then control the action of the film, the film produces elastic deformation to reduce the throttle gap, so that the outlet flow decreases; the ejector rod moves up, increases the throttle gap, and the outlet flow increases. Accurate flow control can be achieved by precisely controlling the piezoelectric ceramics For the purpose, the structure is simple, but the effect is better.

Further, adjusting gaskets are provided between the membrane and the upper valve body, and between the membrane and the lower valve body, and the initial throttling gap can be adjusted by changing the height of the adjusting gaskets.

Furthermore, the push rod is arranged in the axial center hole of the upper valve body, sealed by a sealing ring, and can move up and down.

Further, a piezoelectric ceramic base covering the piezoelectric ceramic is provided on the upper valve body, and the bottom of the piezoelectric ceramic base is fixed to the upper valve body by screws.

Further, the piezoelectric ceramic base is provided with a locking device for pressing the piezoelectric ceramic.

Further, a metal ball is provided between the piezoelectric ceramic and the push rod.

Further, gaskets are provided at both ends of the piezoelectric ceramic, and metal balls are arranged in the grooves between the gasket and the end surface of the push rod.

Further, the locking device is a screw, a tip or a metal ball is arranged between the piezoelectric ceramic and the screw, and the conical positioning tip is arranged at the center of the end of the washer.

Further, a plurality of through holes arranged symmetrically with respect to the center line of the valve are provided between the balance oil chamber and the throttling oil chamber.

Further, an oil inlet pipeline is provided in the lower valve body, and the end of the oil inlet pipeline communicates with the center of the bottom of the throttling oil chamber.

Further, the middle part of the film is in the shape of a central island, which is rigid and only produces displacement; the ring-shaped area around the central island is extremely thin and flexible, and can produce elastic deformation under the push of the push rod.

Further, an oil outlet pipeline communicating with the throttling oil chamber is provided in the lower valve body; both the oil inlet pipeline and the oil outlet pipeline are L-shaped.

The working principle of the invention is to control the extension or shortening of the piezoelectric ceramics by controlling the change of the driving voltage of the piezoelectric ceramics. When the driving voltage is increased, the piezoelectric ceramics elongate, pushing the ejector pin to press down on the film, and the film produces elastic deformation, which reduces the flow rate at the outlet of the servo valve; when the driving voltage is reduced, the piezoelectric ceramics shortens, and the film due to its own elastic deformation And the pressure difference forms an upward resultant force to push the ejector rod upwards, increasing the throttling gap, and increasing the flow rate at the servo valve outlet.

The beneficial effects of the present invention are:

1) By using the piezoelectric ceramic driver, the response frequency of the servo valve is improved, which can be used for high-frequency precise control.

2) Accurate and active control of pressure and flow is realized by precisely controlling the throttling gap.

3) By setting the center of the membrane as a central island, the central island is rigid, and the surrounding deformation area is flexible, which improves the dynamic frequency of the membrane and improves the control accuracy of the throttling gap.

4) By setting a balance oil chamber, the pressure difference on both sides of the membrane is greatly reduced. The force of piezoelectric ceramics is less than a quarter of that of the force without a balance oil chamber under the same conditions. Therefore, piezoelectric materials with smaller volumes can be selected, reducing the material cost of the servo valve by more than 50%.

5) By using the present invention to control each oil chamber of the static pressure bearing, the active control of the motion track of the static pressure main shaft can be realized.

6) The whole device has simple structure, reliable function and low manufacturing cost.

Description of drawings

Fig. 1 is a structural diagram of a piezoelectric ceramic driven thin-film servo valve of the present invention;

Among them: 1. Lower valve body, 2. Film, 3. Adjusting gasket, 4. Upper valve body, 5. Seal ring, 6. Push rod, 7. Metal ball, 8. Piezoelectric ceramic gasket Ⅰ, 9. Piezoelectric ceramics, 10. Piezoelectric ceramic gasket Ⅱ, 11. Locking screw, 12. Piezoelectric ceramic base, 13. Oil supply inlet, 14. Hydraulic oil outlet, 15. Throttle oil cavity, 16. Throttle Clearance, 17, oil chamber connecting hole, 18, balance oil chamber.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

Example 1

A piezoelectric ceramic driven thin film servo valve, as shown in Figure 1, includes a housing consisting of a lower valve body 1, an upper valve body 4 and a piezoelectric ceramic base 12, the central hole 13 of the lower valve body 1 is The hydraulic oil inlet and the annular throttling oil cavity 15 of the lower valve body 1 are connected with the hydraulic oil outlet 14 . There is a circular pressure balance oil chamber 18 inside the upper valve body 4 . Between the upper valve body 4 and the lower valve body 1 is an elastic metal film 2 and adjusting gaskets 3 on both sides. The film 2 is designed as an island-shaped flexible hinge structure with a thick middle throttling part and a thin elastically deformed annular area around it. Four communication holes 17 connecting the throttling oil chamber 15 and the pressure balance oil chamber 18 are evenly distributed in the flexible hinge area. The central island of the membrane 2 and the annular boss at the center of the lower valve body 1 form a throttling gap 16 with a controllable gap. The piezoelectric ceramic base 12 is internally equipped with a drivable piezoelectric ceramic 9 . Both ends of the piezoelectric ceramics are bonded to a gasket 10 and a gasket 8 , the center of the gasket 10 is fixed by a locking screw 11 , and the gasket 8 is connected to the ejector rod 6 through a metal ball 7 . The push rod 6 is installed in the axial hole of the upper valve body 4, sealed by the sealing ring 5, and can move up and down. The lower end of the push rod 6 is against the center of the film 2 .

The pressure balance oil chamber 18 leads to the throttled hydraulic oil, which offsets most of the pressure difference on the lower side of the membrane 2, so that the resultant force formed by the elastic deformation force of the membrane and the pressure difference is within the direct bearing range of the piezoelectric ceramics. It can effectively prevent piezoelectric ceramics from being damaged due to overload.

The center of the gasket 10 has a tapered positioning tip, and the center of the gasket 8 has a tapered hole for installing the metal ball 7, so as to ensure that the piezoelectric ceramic 9 only bears an evenly distributed axial force, and effectively prevents the piezoelectric ceramic 9 from being affected by damage by shearing.

The working principle of the thin-film servo valve is to control the elongation displacement of piezoelectric ceramics by controlling the driving voltage of piezoelectric ceramics. When the driving voltage is increased, the piezoelectric ceramic 9 stretches, pushes the ejector rod 6 to press down on the film 2, and the film 2 produces elastic deformation, reduces the throttling gap 16, and reduces the flow rate at the outlet of the servo valve; when the driving voltage is reduced, The piezoelectric ceramic 9 shortens, and the membrane 2 forms an upward resultant force due to its own elastic deformation force and pressure difference to push the ejector rod 6 to move upward, increasing the throttling gap 16 and increasing the flow rate at the outlet of the servo valve. Therefore, by precisely controlling the driving voltage of the piezoelectric ceramic, the throttling gap of the servo valve can be controlled to change according to the given requirements, so as to achieve the purpose of precise flow control.

The above is only a preferred embodiment of the present invention, and it should be pointed out that for those of ordinary skill in the art, some improvements and modifications can be made without departing from the principle of the present invention. It should be regarded as the protection scope of the present invention.

Claims (8)

1. A piezoelectric ceramic driven membrane servo valve is characterized in that it comprises an upper valve body and a lower valve body, a thin film is arranged between the upper valve body and the lower valve body, and a cylindrical gap is formed between the upper valve body and the thin film. Balance oil chamber, a ring-shaped throttling oil chamber is formed between the film and the lower valve body, the balance oil chamber communicates with the throttle oil chamber, there is a vertically connected ejector rod between the upper valve body and the balance oil chamber, and one end of the ejector rod Set distance or contact with the film, the other end is provided with a piezoelectric ceramic for pushing the ejector rod to move, a metal ball is arranged between the piezoelectric ceramic and the ejector rod, and the middle part of the film is in the shape of a central island. 2 . The thin-film servo valve according to claim 1 , wherein a piezoelectric ceramic base covering the piezoelectric ceramic is provided on the upper valve body. 3 . 3. The thin-film servo valve according to claim 2, wherein a locking device for pressing the piezoelectric ceramic is provided on the piezoelectric ceramic base. 4. The thin-film servo valve according to claim 1, characterized in that gaskets are provided at both ends of the piezoelectric ceramic. 5. The membrane servo valve according to claim 3, wherein the locking device is a screw, and a tip or a metal ball is arranged between the piezoelectric ceramic and the screw. 6 . The thin-film servo valve according to claim 1 , wherein a plurality of through holes arranged symmetrically with respect to the centerline of the valve are provided between the balance oil chamber and the throttling oil chamber. 7 . 7. The thin-film servo valve according to claim 1, 2 or 3, wherein an oil inlet pipeline is arranged in the lower valve body, and the end of the oil inlet pipeline communicates with the center of the bottom of the throttling oil chamber. 8. The thin-film servo valve according to claim 1, 2 or 3, wherein an oil outlet pipeline communicating with the throttling oil chamber is arranged in the lower valve body.