CN110805583B - Piezo-Driven Nozzle Shutter Pressure Servo Valve with Main Spool Hydrodynamic Compensation - Google Patents

Abstract

The invention discloses a piezoelectric ring-driven nozzle baffle plate pressure servo valve with hydrodynamic compensation of a main valve core, comprising an upper casing, an adjustment component, a first nozzle, a second nozzle, a lower casing, a valve core, a first Return spring, second return spring, oil filter, first shuttle valve and second shuttle valve. The invention uses the piezoelectric sheet to drive the baffle to replace the original electric-mechanical method of the torque motor, avoids the shortcomings of the traditional torque motor such as complex structure, high installation requirements and poor reliability, and uses the baffle to replace the baffle to avoid the thin and long metal plate. The occurrence of frequent flutter and whistling improves the system stability and helps to reduce the volume and weight of the servo valve to a certain extent. At the same time, the piezoelectric drive has higher tolerance to harsh environments such as high temperature and strong magnetic field interference than the torque motor; it can greatly compensate for the steady-state hydraulic force that varies with the opening degree and load pressure during the movement of the valve core, which is helpful for improving the static accuracy of the pressure servo valve. has obvious effect.

Description

Piezo-Driven Nozzle Shutter Pressure Servo Valve with Main Spool Hydrodynamic Compensation

technical field

The invention relates to an aircraft electro-hydraulic servo control element, in particular to a piezoelectric sheet-driven nozzle baffle plate pressure servo valve with hydraulic compensation of a main valve core.

Background technique

The electro-hydraulic servo valve realizes the conversion and precise control of electrical and hydraulic signals through hydraulic technology and automatic control technology. It is the core component of the electro-hydraulic servo control system, and its performance directly affects and determines the performance of the entire control system. Due to its fast response, good linearity and compact structure, the double-nozzle flapper servo valve has good static and dynamic characteristics, and is the most widely used in the industrial field. However, the torque motor of the double-nozzle flapper servo valve has a complex structure and is prone to vibration and whistling, which seriously affects its reliability and service life. At the same time, the torque motor has a slow response speed and poor anti-interference ability, which limits its application range. Piezoelectric sheet is a new type of electro-mechanical conversion structure, which has the advantages of compact structure, fast response and strong anti-interference ability. However, the displacement of the piezoelectric sheet is small, and it is not easy to be used as an actuating mechanism for a large flow valve. The present invention utilizes the feature that the pressure servo valve works within a small opening range, utilizes this new driving technology as a driving mechanism, and designs a hydraulic compensation mechanism to improve the linearity of the servo valve when the oil supply pressure is high.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a pressure servo valve driven by a piezoelectric sheet with a main valve core with hydrodynamic compensation for the defects involved in the background technology.

The present invention adopts the following technical solutions for solving the above-mentioned technical problems:

Piezoelectric ring-driven nozzle baffle pressure servo valve with hydraulic compensation of main spool, including upper casing, adjustment assembly, first nozzle, second nozzle, lower casing, valve core, first return spring, second return Spring, oil filter, first shuttle valve and second shuttle valve;

The adjustment assembly includes a fixed cylinder, N annular piezoelectric sheets, N+1 O-shaped nitrile rings, a first baffle plate and a second baffle plate;

The outer diameter of the O-shaped nitrile ring is larger than the outer diameter of the piezoelectric sheet, and the inner diameter of the O-shaped nitrile ring is smaller than the inner diameter of the piezoelectric sheet; the N+1 O-shaped nitrile rings and the N piezoelectric sheets are alternately stacked and identical. shaft, forming a drive part with O-rings on both sides;

The second baffle plate includes a second baffle plate and a connecting rod, one end of the connecting rod is vertically fixed with the second baffle plate, and the other end is provided with a thread; the first baffle plate includes a first baffle plate and a connecting portion, The connecting portion is fixedly connected with the first baffle plate, and the connecting portion is provided with a threaded hole that matches the thread on the connecting rod; The connecting part is threadedly connected, and the driving part is clamped between the second baffle and the connecting part; the first baffle and the second baffle are arranged in parallel;

The fixed cylinder is a hollow cylinder, two end faces of which are respectively provided with through holes for the first baffle plate and the second baffle plate to pass through; the driving member is arranged in the fixed cylinder, and each O-shaped nitrile on the driving member is provided with through holes. The outer wall of the ring is abutted against the inner wall of the fixed cylinder, and the two end faces of the fixed cylinder clamp both sides of the driving member;

The upper casing is provided with a cavity; the fixing cylinder is fixed in the cavity of the upper casing, so that the first baffle and the second baffle are vertically arranged; the side of the upper casing and the fixing cylinder is The wall is matched with through holes for the driving wires of the N piezoelectric sheets to extend;

The first nozzle and the second nozzle are arranged on both sides of the upper casing, and the first nozzle and the second nozzle extend into the cavity of the upper casing and face the first baffle plate and the second baffle plate respectively, And when the N piezoelectric sheets are not driven, the distance between the first nozzle and the first baffle, and the distance between the second nozzle and the second baffle are equal;

The lower casing is provided with a feedback cavity D1, a compensation cavity A1, a main cavity, a compensation cavity A2, and a feedback cavity D2 in sequence from left to right, and the lower casing is provided with a secondary cavity for installing an oil filter under the main cavity ; The lower casing is also provided with an oil inlet, a first control oil port and a second control oil port for communicating with the outside world;

Both ends of the valve core are provided with coaxial connecting rods, and the valve core is provided with first to third convex rings in sequence from left to right; the first to third convex rings of the valve core are arranged on the lower shell In the main cavity of the body, both ends protrude into the compensation cavity A1 and the compensation cavity A2 respectively, and the connecting rods at both ends protrude into the feedback cavity D1 and the feedback cavity D2 respectively; the first to third convex rings connect the lower shell The main cavity is divided into control cavity B1, oil passing cavity C1, oil passing cavity C2 and control cavity B2 from left to right, and the oil supply cavity E1 is formed between the right side of the outer wall of the first convex ring and the inner wall of the lower shell , An oil supply cavity E2 is formed between the left side of the outer wall surface of the third convex ring and the inner wall of the lower casing, and an oil return cavity is formed between the outer wall surface of the second convex ring and the inner wall of the lower casing; the outer wall surface of the first convex ring There is a groove on the left side of the outer wall of the first convex ring, a throttle groove F1 is formed between the groove on the left side of the outer wall of the first convex ring and the inner wall of the lower shell, and a groove is formed on the right side of the outer wall of the third convex ring. A throttle groove F2 is formed between the groove on the right side of the outer wall and the inner wall of the lower shell;

When the valve core slides to the right, the throttle groove F1 is connected with the oil supply chamber E1, and the oil passage chamber C1 is connected with the oil return chamber; when the valve core slides to the left, the throttle groove F2 is connected with the oil supply chamber E2, and the oil is connected The cavity C2 is communicated with the oil return cavity;

The first return spring is arranged in the feedback cavity D1, one end is fixedly connected with the lower casing, and the other end is fixedly connected with the connecting rod at one end of the valve core; the second return spring is arranged in the feedback cavity D2, One end is fixedly connected with the lower casing, and the other end is fixedly connected with the connecting rod at the other end of the valve core; the first return spring and the second return spring are used to provide pre-tightening force, and the N piezoelectric When the plate is not driven, the preload provided by the first return spring and the second return spring are equal;

The nozzle cavity of the first nozzle and the control cavity B1 are communicated through pipes; the nozzle cavity of the second nozzle and the control cavity B2 are communicated through pipes; the bottom of the upper casing cavity and the oil return The cavities are communicated through pipes;

The auxiliary cavity is communicated with the control cavity B1, the oil supply cavity E1, the oil supply cavity E2, the control cavity B2 and the oil inlet respectively through pipes; the oil filter is arranged in the auxiliary cavity and is used for filtering impurities in the oil , Protect the nozzle, the outer wall of the oil filter and the inner wall of the sub-chamber of the lower casing form a cavity. After the oil flows into the oil filter from the oil inlet, it flows into the control cavity B1 and B2 after being filtered by the oil filter, and then flows into the oil supply through the cavity. Cavity E1, oil supply cavity E2;

A fixed throttling element is arranged in the pipeline between the auxiliary cavity and the control cavity B1 and the control cavity B2;

The oil return cavity is provided with an oil return port;

The first shuttle valve and the second shuttle valve are symmetrically arranged in the lower casing, and each includes a first oil inlet port, a second oil inlet port and an oil outlet port; the first oil inlet port of the first shuttle valve They are respectively connected with the oil return port and the throttle groove F1 through pipelines, the second oil inlet port and the first control oil port are connected through pipelines, and the oil outlet interface is connected with the compensation chamber A1 through pipelines; The first oil inlet port of the two shuttle valves is connected with the oil return port and the throttle groove F2 respectively through pipelines, the second oil inlet port and the second control oil port are connected through pipelines, and the oil outlet port is connected with the Compensation cavity A2 is communicated through pipeline;

A fixed throttle element is provided in the pipeline between the first oil inlet port of the first shuttle valve, the first oil inlet port of the second shuttle valve and the oil return port to ensure that the first shuttle valve and the oil return port are connected. The oil pressure of the first oil inlet port of the second shuttle valve is a preset pressure threshold;

The first control oil port is also communicated with the oil passage chamber C1 and the feedback chamber D2 respectively through pipes; the second control oil port is also communicated with the oil passage chamber C2 and the feedback chamber D1 respectively through pipes.

As a further optimized solution of the piezoelectric ring-driven nozzle baffle plate pressure servo valve with hydrodynamic compensation of the main spool of the present invention, a nozzle return is provided in the pipeline between the bottom of the upper casing cavity and the oil return cavity. Oil restrictor to prevent the oil in the oil return cavity from flowing into the upper casing cavity.

As a further optimized solution of the piezoelectric ring-driven nozzle baffle plate pressure servo valve with hydrodynamic compensation of the main valve core of the present invention, the bottom of the end faces on both sides of the fixed cylinder is provided with through holes, so that the accumulated liquid in the fixed cylinder flows into the upper shell in the body cavity.

As a further optimized solution of the piezoelectric ring-driven nozzle baffle plate pressure servo valve with the hydraulic compensation of the main spool of the present invention, a metal film is provided on the outside of the piezoelectric sheet, so that the piezoelectric sheet is isolated from the oil, and the piezoelectric sheet is improved. service life.

The invention also discloses a hydraulic compensation method for the pressure servo valve driven by the piezoelectric ring with the hydraulic compensation of the main valve core, comprising the following steps:

Step 1), adjust the control voltage of each piezoelectric sheet to zero, the distances from the first nozzle to the first baffle, the second nozzle to the second baffle are the same, and the nozzle chamber pressures of the first nozzle and the second nozzle are equal , the pressures of the control chambers B1 and B2 of the lower casing are the same, and the valve core is in the neutral position, the oil supply chamber E1 is closed by the first convex ring of the valve core, and the oil supply chamber E2 is closed by the third convex ring of the valve core;

Step 2), adjust the control voltage of each piezoelectric sheet to a preset voltage threshold, and the preset voltage threshold is a positive value. At this time, the N ring-shaped piezoelectric sheets are synchronously deformed to the right, and the first baffle plate is deformed to the right. , The second baffle moves to the right synchronously with the deformation generated by the N annular piezoelectric sheets, the distance from the first baffle to the first nozzle increases, the distance from the second nozzle to the second baffle plate decreases, and the pressure of the control chamber B1 When the pressure is lowered, the pressure of the control chamber B2 increases, and the main spool slides to the left; the oil inlet is communicated with the oil passage chamber C1 through the auxiliary chamber of the lower casing and the oil supply chamber E1, and the oil flows out from the first control oil port through the control chamber C1 ; The first control oil port is communicated with the oil return cavity; the oil inlet is communicated with the throttle groove F2 through the auxiliary cavity of the lower casing and the oil supply cavity E2, and the oil flows into the oil return port; the throttle groove F1 is closed, and the first No oil passes through the first oil inlet port of the shuttle valve, and its second oil inlet port is communicated with the first control oil port, and the oil flows into the compensation chamber A1 through the second oil inlet port; the first oil inlet port of the second shuttle valve It is connected with the oil inlet, the second oil inlet port is connected with the second control oil port, and the oil pressure of the first oil inlet port is relatively high, so the oil passes through the auxiliary chamber, the oil supply chamber E2, the throttle groove F2 and the second shuttle The first oil inlet port of the valve flows into the compensation chamber A2; the feedback chamber D1 communicates with the second control oil port; the feedback chamber D2 communicates with the first control oil port; the compression amount of the first return spring increases, the second The compression of the return spring is reduced;

Step 3), restore the control voltage of each piezoelectric sheet to zero, at this time, the N annular piezoelectric sheets return to the initial position, the first nozzle to the first baffle, the second nozzle to the second baffle If the distance is the same, the pressures of the nozzle chambers of the first nozzle and the second nozzle are the same, and the pressures of the control chambers B1 and B2 of the lower casing are the same; the valve core returns to the neutral position under the action of the return spring.

Compared with the prior art, the present invention adopts the above technical scheme, and has the following technical effects:

1. The use of piezoelectric sheet to drive the baffle plate to replace the original torque motor electro-mechanical method can avoid the traditional torque motor with complex structure, high installation requirements and poor reliability. At the same time, the piezoelectric drive has higher tolerance to harsh environments such as high temperature and strong magnetic field interference than the torque motor;

2. The use of baffles instead of baffles avoids the occurrence of high-frequency flutter and whistling of thin and long metal plates, improves system stability, and helps to reduce the volume and weight of the servo valve to a certain extent;

3. Although the output force of the piezoelectric sheet is smaller than that of the conventional stack, its displacement is large and the structure is compact. It is an ideal driver for the nozzle baffle type jet hydraulic valve. The drive and pre-stage hydraulic amplifier have fast response and wide adjustment range;

4. The hydraulic power compensation design of the main spool can greatly compensate the steady-state hydraulic power of the spool moving with the change of opening and load pressure, which has a significant effect on improving the static accuracy of the pressure servo valve. Therefore, the pressure servo valve has good linearity.

Description of drawings

Fig. 1 is the structure sectional view of the present invention;

Fig. 2 is the structural schematic diagram that the piezoelectric sheet and its outer metal film are matched in the present invention;

3 is a schematic diagram of the working state and fluid flow direction when the valve core moves leftward from the zero position in the present invention;

4 is a schematic diagram of the working state and the fluid flow direction when the valve core moves to the right from the zero position in the present invention;

FIG. 5 is a schematic diagram of the change curve of the hydraulic power and compensation force of the valve core with the opening degree of the valve core in the present invention.

In the figure, 1-upper shell, 2-fixing cylinder, 3-through holes on the upper shell and the fixing cylinder for the wires of each piezoelectric sheet to extend, 4-first baffle plate, 5-O-type nitrile ring, 6-piezoelectric sheet, 7-first nozzle, 8-second nozzle, 9-second baffle plate, 10-throttle groove F2, 11-oil supply chamber E2, 12-second shuttle valve, 13-oil filter , 14- the second control oil port, 15- oil return port, 16- oil inlet port, 17- the first control oil port, 18- the first shuttle valve in the pipeline between the second oil inlet port and the oil return port Fixed throttle element, 19-Fixed throttle element in the pipeline between secondary chamber and control chamber B1, 20-Oil supply chamber E1, 21-Return spring, 22-Second convex ring on the valve core, 23-Lower Shell, 24-through holes on both sides of the fixed cylinder, 25-metal film.

Detailed ways

Below in conjunction with accompanying drawing, the technical scheme of the present invention is described in further detail:

The present invention may be embodied in many different forms and should not be considered limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, components are exaggerated for clarity.

As shown in Fig. 1, the present invention discloses a piezoelectric ring-driven nozzle baffle plate pressure servo valve with hydrodynamic compensation of the main spool, including an upper casing, an adjustment assembly, a first nozzle, a second nozzle, and a lower casing , valve core, first return spring, second return spring, oil filter, first shuttle valve and second shuttle valve;

The adjustment assembly includes a fixed cylinder, N annular piezoelectric sheets, N+1 O-shaped nitrile rings, a first baffle plate and a second baffle plate;

The outer diameter of the O-shaped nitrile ring is larger than the outer diameter of the piezoelectric sheet, and the inner diameter of the O-shaped nitrile ring is smaller than the inner diameter of the piezoelectric sheet; the N+1 O-shaped nitrile rings and the N piezoelectric sheets are alternately stacked and identical. shaft, forming a drive part with O-rings on both sides;

The second baffle plate includes a second baffle plate and a connecting rod, one end of the connecting rod is vertically fixed with the second baffle plate, and the other end is provided with a thread; the first baffle plate includes a first baffle plate and a connecting portion, The connecting portion is fixedly connected with the first baffle plate, and the connecting portion is provided with a threaded hole that matches the thread on the connecting rod; The connecting part is threadedly connected, and the driving part is clamped between the second baffle and the connecting part; the first baffle and the second baffle are arranged in parallel;

The fixed cylinder is a hollow cylinder, two end faces of which are respectively provided with through holes for the first baffle plate and the second baffle plate to pass through; the driving member is arranged in the fixed cylinder, and each O-shaped nitrile on the driving member is provided with through holes. The outer wall of the ring is abutted against the inner wall of the fixed cylinder, and the two end faces of the fixed cylinder clamp both sides of the driving member;

The upper casing is provided with a cavity; the fixing cylinder is fixed in the cavity of the upper casing, so that the first baffle and the second baffle are vertically arranged; the side of the upper casing and the fixing cylinder is The wall is matched with through holes for the driving wires of the N piezoelectric sheets to extend;

The first nozzle and the second nozzle are arranged on both sides of the upper casing, and the first nozzle and the second nozzle extend into the cavity of the upper casing and face the first baffle plate and the second baffle plate respectively, And when the N piezoelectric sheets are not driven, the distance between the first nozzle and the first baffle, and the distance between the second nozzle and the second baffle are equal;

The lower casing is provided with a feedback cavity D1, a compensation cavity A1, a main cavity, a compensation cavity A2, and a feedback cavity D2 in sequence from left to right, and the lower casing is provided with a secondary cavity for installing an oil filter under the main cavity ; The lower casing is also provided with an oil inlet, a first control oil port and a second control oil port for communicating with the outside world;

Both ends of the valve core are provided with coaxial connecting rods, and the valve core is provided with first to third convex rings in sequence from left to right; the first to third convex rings of the valve core are arranged on the lower shell In the main cavity of the body, both ends protrude into the compensation cavity A1 and the compensation cavity A2 respectively, and the connecting rods at both ends protrude into the feedback cavity D1 and the feedback cavity D2 respectively; the first to third convex rings connect the lower shell The main cavity is divided into control cavity B1, oil passing cavity C1, oil passing cavity C2 and control cavity B2 from left to right, and the oil supply cavity E1 is formed between the right side of the outer wall of the first convex ring and the inner wall of the lower shell , An oil supply cavity E2 is formed between the left side of the outer wall surface of the third convex ring and the inner wall of the lower casing, and an oil return cavity is formed between the outer wall surface of the second convex ring and the inner wall of the lower casing; the outer wall surface of the first convex ring There is a groove on the left side of the outer wall of the first convex ring, a throttle groove F1 is formed between the groove on the left side of the outer wall of the first convex ring and the inner wall of the lower shell, and a groove is formed on the right side of the outer wall of the third convex ring. A throttle groove F2 is formed between the groove on the right side of the outer wall and the inner wall of the lower shell;

When the valve core slides to the right, the throttle groove F1 is connected with the oil supply chamber E1, and the oil passage chamber C1 is connected with the oil return chamber; when the valve core slides to the left, the throttle groove F2 is connected with the oil supply chamber E2, and the oil is connected The cavity C2 is communicated with the oil return cavity;

The first return spring is arranged in the feedback cavity D1, one end is fixedly connected with the lower casing, and the other end is fixedly connected with the connecting rod at one end of the valve core; the second return spring is arranged in the feedback cavity D2, One end is fixedly connected with the lower casing, and the other end is fixedly connected with the connecting rod at the other end of the valve core; the first return spring and the second return spring are used to provide pre-tightening force, and the N piezoelectric When the plate is not driven, the preload provided by the first return spring and the second return spring are equal;

The nozzle cavity of the first nozzle and the control cavity B1 are communicated through pipes; the nozzle cavity of the second nozzle and the control cavity B2 are communicated through pipes; the bottom of the upper casing cavity and the oil return The cavities are communicated through pipes;

The auxiliary cavity is communicated with the control cavity B1, the oil supply cavity E1, the oil supply cavity E2, the control cavity B2 and the oil inlet respectively through pipes; the oil filter is arranged in the auxiliary cavity and is used for filtering impurities in the oil , Protect the nozzle, the outer wall of the oil filter and the inner wall of the sub-chamber of the lower casing form a cavity. After the oil flows into the oil filter from the oil inlet, it flows into the control cavity B1 and B2 after being filtered by the oil filter, and then flows into the oil supply through the cavity. Cavity E1, oil supply cavity E2;

A fixed throttling element is arranged in the pipeline between the auxiliary cavity and the control cavity B1 and the control cavity B2;

The oil return cavity is provided with an oil return port;

The first shuttle valve and the second shuttle valve are symmetrically arranged in the lower casing, and each includes a first oil inlet port, a second oil inlet port and an oil outlet port; the first oil inlet port of the first shuttle valve It is communicated with the throttle groove F1 through pipelines, the second oil inlet port is communicated with the oil return port and the first control oil port respectively through pipelines, and the compensation chamber A1 of the oil outlet interface is communicated through pipelines; The first oil inlet port of the two shuttle valve is communicated with the throttle groove F2 through pipes, the second oil inlet port is communicated with the oil return port and the second control oil port respectively through pipes, and the oil outlet port is communicated with the Compensation cavity A2 is communicated through pipeline;

A fixed throttle element is provided in the pipeline between the first oil inlet port of the first shuttle valve, the first oil inlet port of the second shuttle valve and the oil return port to ensure that the first shuttle valve and the oil return port are connected. The oil pressure of the first oil inlet port of the second shuttle valve is a preset pressure threshold;

The first control oil port is also communicated with the oil passage chamber C1 and the feedback chamber D2 respectively through pipes; the second control oil port is also communicated with the oil passage chamber C2 and the feedback chamber D1 respectively through pipes.

A nozzle oil return restrictor is arranged in the pipeline between the bottom of the cavity of the upper casing and the oil return cavity to prevent the oil in the return cavity from flowing into the cavity of the upper casing.

The bottoms of the end faces on both sides of the fixing cylinder are provided with through holes, so that the accumulated liquid in the fixing cylinder flows into the cavity of the upper casing.

As shown in FIG. 2 , the outside of the piezoelectric sheet is provided with a metal film, so that the piezoelectric sheet is isolated from the oil and the service life of the piezoelectric sheet is improved.

The distances from the first nozzle to the first baffle and the second nozzle to the second baffle can be controlled by changing the excitation voltage applied to the piezoelectric sheet, that is, the input voltage of the servo valve. When the input voltage is zero, the distances from the first nozzle to the first baffle and the second nozzle to the second baffle are equal, the pressures in the two nozzle chambers are equal, the axial hydraulic pressure received by the valve core is zero, and the spool valve is in Zero position, the servo valve has no hydraulic signal output. At this time, the hydraulic force received by the valve core is zero; and the pressures of the compensation chambers A1 and A2 are equal, and the hydraulic force compensation force received by the valve core is also zero.

When a positive excitation voltage is input to the piezoelectric sheet, the piezoelectric sheet will produce a rightward convex deformation, which pushes the first baffle and the second baffle to move to the right synchronously. As a result, the distance from the second nozzle to the second baffle plate decreases, and the distance from the first nozzle to the first baffle plate increases, resulting in an increase in the pressure of the nozzle chamber of the second nozzle and a decrease in the pressure in the nozzle chamber of the first nozzle, that is, the control chamber. The pressure of B2 increases, and the pressure of control chamber B1 decreases, so the spool overcomes the resistance of the spring force (generated by the first return spring and the second return spring) and moves to the left under the action of this hydraulic pressure, and the flow direction of the oil As shown in Figure 3.

The oil supply chamber E1 is connected to the first control oil port, and the oil flows into the first control oil port from the oil supply chamber E1, which will generate a hydraulic force at the valve core along the axial direction of the valve core to the right, and its size varies with the valve core opening. Change; the oil supply chamber E2 is in a closed state, and the second control oil port is communicated with the oil return port.

For the compensation chamber A1, the spool moves to the left to close the rectangular throttle groove F1, and the oil inlet channel of the first shuttle valve is only connected to the first control oil port. Therefore, the pressure of the compensation chamber A1 is the same as the pressure value p ₁ of the first control oil port. For the compensation chamber A2, it communicates with the oil supply chamber E2 through the rectangular throttle groove F2. After the oil flows through the throttle groove F2, a pressure drop occurs. Due to the small volume change of the oil in the compensation chambers A1 and A2 at steady state, most of the oil is returned to the oil through the fixed throttling element. From the analysis of the hydraulic bridge circuit composed of the throttling groove F2 (equivalent to variable liquid resistance) and the fixed throttling element, the throttling hole can ensure that the pressure of the right compensation chamber of the spool changes correspondingly with the displacement of the spool to meet the hydraulic power requirements. compensation needs. There is a pressure difference between the hydrodynamic compensation chambers A1 and A2 on both sides of the spool, so a hydrodynamic compensation force (opposite to the direction of the hydrodynamic force) will be generated along the axial direction of the spool to the left.

When the input voltage returns to zero from a certain value, the piezoelectric sheet returns to a near-initial state, driving the baffle plate back to the neutral position, the first nozzle to the first baffle, the second nozzle to the second baffle are equal, and the third The pressures of the nozzle chambers of the first nozzle and the second nozzle both return to zero pressure. At this time, the pressures of the valve core control chambers B1 and B2 are equal. Under the action of the return spring, the slide valve returns to the zero position, and the servo valve closes again.

FIG. 4 is a schematic diagram of the working state and the fluid flow direction of the servo valve spool of the present invention when the spool moves to the right from the zero position.

The outlet of the first shuttle valve is communicated with the compensation chamber A1, and the outlet of the second shuttle valve is communicated with the compensation chamber A2. Each shuttle valve has two oil inlets, and the one with higher pressure is selected respectively (the other one is closed). For example, for the first shuttle valve, its outlet is connected to the compensation chamber A1 of the main spool, and one of its two oil inlets is the first control port pressure p ₁ , and the other is the oil supply pressure p _S through the rectangular shape on the first convex ring of the spool. Compensation pressure (slightly less than p _S ) after decompression of throttle groove F1. When the spool moves to the left from the zero position and the rectangular throttle groove F1 is not connected to _ps , the oil pressure of the compensation chamber A1 is p ₁ . At this time, the rectangular throttle groove F2 on the third convex ring is connected to the oil supply pressure _ps and the first oil inlet port of the second shuttle valve. Because the throttling pressure p _x is slightly lower than the oil supply pressure, and the pressure p ₂ of the second control port of the spool is lower (slightly greater than the return oil pressure p ₀ ), the second shuttle valve spool moves down and turns on The compensation chamber A2 pressure is p _x . Therefore, after the spool moves to the left by x _v from the zero position, its hydrodynamic compensation is _Ac (p _x -p ₁ ), where both p _x and p ₁ change with the change of x _v . Conversely, when the main spool moves to the right from the zero position, the hydraulic compensation that can be obtained by this scheme is A _c (p _x -p ₂ ). The direction is always opposite to the hydraulic force to form a cancellation and ensure the accuracy of the opening amount.

The effective working area of the hydrodynamic compensation cavity can be determined according to the size of the hydrodynamic force. The calculation formula of the hydraulic power of the valve core is:

F _s =0.43W ₁ x _v ( _ps -p _L )

Among them, W ₁ is the area gradient of the valve, x _v is the spool displacement, p _S is the oil supply pressure of the servo valve, and p _L is the load pressure of the servo valve, that is, the pressure difference between the first control oil port and the second control oil port.

When the spool moves to the left, the oil supply chamber E1 is communicated with the first control oil port, the oil supply chamber E2 is closed, and the second control oil port is communicated with the oil return port. For the compensation chamber A ₁ , the spool moves to the left to close the rectangular throttle groove F1, and the first shuttle valve is only connected to the first control oil port. Therefore, the oil pressure in the compensation chamber A ₁ is p ₁ . For the compensation chamber A ₂ , it communicates with the oil supply chamber E2 through the rectangular throttle groove F2, and it is assumed that its pressure is reduced from p _s to p _x .

Because the second control oil port is connected to the oil return port, the value of its pressure p ₂ is close to the tank pressure p ₀ (actually due to the pressure drop at the valve port of the oil flow, p ₂ is slightly larger than p ₀ ), at this time p ₂ is compared with p _S and p ₁ is small, it can be considered that p _L =p ₁ -p ₂ ≈p ₁ . Therefore, the total hydraulic power of the two series valve ports of the main spool is:

F _L =0.43W ₁ x _v (p _S -p _L )≈0.43W ₁ x _v (p _S -p ₁ )

The oil flows from the oil supply chamber E2 to the first oil inlet port of the second shuttle valve through the rectangular throttle groove F2. The rectangular throttle groove F2 is a variable liquid resistance proportional to the displacement of the spool, and its outlet pressure p _x is fixed The partial pressure of the throttling element is related to the partial pressure of the hydraulic half-bridge composed of the variable hydraulic resistance of the rectangular throttling groove and the fixed throttling element.

Specifically, it can be calculated according to the following process:

The oil produces a pressure drop from the oil supply chamber E2 through the rectangular throttle groove F2, and the flow rate of the oil flowing through the throttle groove E2 is:

Among them, C _d1 is the flow coefficient of the rectangular choke groove, W ₂ is the area gradient, ρ is the oil density, and p _x is the outlet pressure of the rectangular choke groove. Due to the small change of the liquid in the compensation chamber A2, most of the oil returns to the oil through the fixed throttling element before entering the second shuttle valve. The flow through this throttling element is:

Among them, C _d2 is the flow coefficient of the fixed throttle element, and A _h is the flow area of the fixed throttle element. Because the flow rate of the compensation chamber A2 at the exit of the second shuttle valve is extremely small, it is regarded as zero, so there is q _cin =q _c0 , namely:

Can be simplified to:

Therefore, the total hydraulic compensation force that the compensation chambers A1 and A2 can provide is:

Here A _C is the effective area of the compensation cavity spool. To compensate all the hydraulic forces, the hydraulic force and the compensation force need to be equal, namely:

F _S = F _C

After substitution, the equation can be written as:

In the formula, p ₁ varies with x _v . To simplify analysis, p ₁ can be represented using an approximate relationship. From the pressure characteristics of the cylindrical slide valve, in the small opening range, its load pressure meets the

p ₁ =K _p0 x _v (p _L =K _p0 x _v has been described above, when the opening is small, p _L ≈p ₁ )

In the formula, K _p0 is the zero pressure gain of the zero opening valve. In general calculation, K _p0 can be taken as:

Therefore, by substituting the approximate expression of p ₁ , the hydrodynamic compensation formula can be simplified to:

Further simplification of the above formula, we can get:

至此，可以通过合理设计A_C、k₁和k₂，使上式两边在x_v处于(0-0.2)mm区间内近似相等。图5为通过设计与优化获得的一组方程左右两边力的关系。图5看出，液动力补偿腔产生的总补偿力与液动力近似相等，可认为阀芯所受液动力在此范围内的各开度下均可得以充分补偿，提高了伺服阀负载压力的控制精度。in,

So far, by reasonably designing A _C , k ₁ and k ₂ , both sides of the above formula can be approximately equal when x _v is in the interval of (0-0.2) mm. Figure 5 shows the relationship between the forces on the left and right sides of a set of equations obtained through design and optimization. Figure 5 shows that the total compensation force generated by the hydraulic compensation chamber is approximately equal to the hydraulic force. It can be considered that the hydraulic force received by the valve core can be fully compensated for each opening within this range, which improves the load pressure of the servo valve. control precision.

The piezoelectric sleeve is equipped with N annular piezoelectric sheets of the same specification, and the same excitation voltage is applied. Use a large-diameter O-shaped nitrile ring to fix the outer circumference of the piezoelectric piece, and use a small-diameter O-shaped nitrile ring to fix its inner circumference. The inner circumference of the piezoelectric sheet outputs force and displacement under the action of excitation voltages of different magnitudes and polarities to drive the baffle plate, and bears a certain impact force.

The two ends of the valve core are equipped with return springs, which can make the main valve core return to the zero position after the excitation voltage is withdrawn.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as herein, are not to be taken in an idealized or overly formal sense. explain.

The specific embodiments described above further describe the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (5)

1. Piezoelectric ring driven nozzle baffle plate pressure servo valve with hydraulic compensation of main spool, characterized in that it includes an upper casing, an adjustment assembly, a first nozzle, a second nozzle, a lower casing, a valve core, a first return spring, second return spring, oil filter, first shuttle valve and second shuttle valve; The adjustment assembly includes a fixed cylinder, N annular piezoelectric sheets, N+1 O-shaped nitrile rings, a first baffle plate and a second baffle plate; The outer diameter of the O-shaped nitrile ring is larger than the outer diameter of the piezoelectric sheet, and the inner diameter of the O-shaped nitrile ring is smaller than the inner diameter of the piezoelectric sheet; the N+1 O-shaped nitrile rings and the N piezoelectric sheets are alternately stacked and identical. shaft, forming a drive part with O-rings on both sides; The second baffle plate includes a second baffle plate and a connecting rod, one end of the connecting rod is vertically fixed with the second baffle plate, and the other end is provided with a thread; the first baffle plate includes a first baffle plate and a connecting portion, The connecting portion is fixedly connected with the first baffle plate, and the connecting portion is provided with a threaded hole that matches the thread on the connecting rod; The connecting part is threadedly connected, and the driving part is clamped between the second baffle and the connecting part; the first baffle and the second baffle are arranged in parallel; The fixed cylinder is a hollow cylinder, two end faces of which are respectively provided with through holes for the first baffle plate and the second baffle plate to pass through; the driving member is arranged in the fixed cylinder, and each O-shaped nitrile on the driving member is provided with through holes. The outer wall of the ring is abutted against the inner wall of the fixed cylinder, and the two end faces of the fixed cylinder clamp both sides of the driving member; The upper casing is provided with a cavity; the fixing cylinder is fixed in the cavity of the upper casing, so that the first baffle and the second baffle are vertically arranged; the side of the upper casing and the fixing cylinder is The wall is matched with through holes for the driving wires of the N piezoelectric sheets to extend; The first nozzle and the second nozzle are arranged on both sides of the upper casing, and the first nozzle and the second nozzle extend into the cavity of the upper casing and face the first baffle plate and the second baffle plate respectively, And when the N piezoelectric sheets are not driven, the distance between the first nozzle and the first baffle, and the distance between the second nozzle and the second baffle are equal; The lower casing is provided with a feedback cavity D1, a compensation cavity A1, a main cavity, a compensation cavity A2, and a feedback cavity D2 in sequence from left to right, and the lower casing is provided with a secondary cavity for installing an oil filter under the main cavity ; The lower casing is also provided with an oil inlet, a first control oil port and a second control oil port for communicating with the outside world; Both ends of the valve core are provided with coaxial connecting rods, and the valve core is provided with first to third convex rings in sequence from left to right; the first to third convex rings of the valve core are arranged on the lower shell In the main cavity of the body, both ends protrude into the compensation cavity A1 and the compensation cavity A2 respectively, and the connecting rods at both ends protrude into the feedback cavity D1 and the feedback cavity D2 respectively; the first to third convex rings connect the lower shell The main cavity is divided into control cavity B1, oil passing cavity C1, oil passing cavity C2 and control cavity B2 from left to right, and the oil supply cavity E1 is formed between the right side of the outer wall of the first convex ring and the inner wall of the lower shell , An oil supply cavity E2 is formed between the left side of the outer wall surface of the third convex ring and the inner wall of the lower casing, and an oil return cavity is formed between the outer wall surface of the second convex ring and the inner wall of the lower casing; the outer wall surface of the first convex ring There is a groove on the left side of the outer wall of the first convex ring, a throttle groove F1 is formed between the groove on the left side of the outer wall of the first convex ring and the inner wall of the lower shell, and a groove is formed on the right side of the outer wall of the third convex ring. A throttle groove F2 is formed between the groove on the right side of the outer wall and the inner wall of the lower shell; When the valve core slides to the right, the throttle groove F1 is connected with the oil supply chamber E1, and the oil passage chamber C1 is connected with the oil return chamber; when the valve core slides to the left, the throttle groove F2 is connected with the oil supply chamber E2, and the oil is connected The cavity C2 is communicated with the oil return cavity; The first return spring is arranged in the feedback cavity D1, one end is fixedly connected with the lower casing, and the other end is fixedly connected with the connecting rod at one end of the valve core; the second return spring is arranged in the feedback cavity D2, One end is fixedly connected with the lower casing, and the other end is fixedly connected with the connecting rod at the other end of the valve core; the first return spring and the second return spring are used to provide pre-tightening force, and the N piezoelectric When the plate is not driven, the preload provided by the first return spring and the second return spring is equal; The nozzle cavity of the first nozzle and the control cavity B1 are communicated through pipes; the nozzle cavity of the second nozzle and the control cavity B2 are communicated through pipes; the bottom of the upper casing cavity and the oil return The cavities are communicated through pipes; The auxiliary cavity is communicated with the control cavity B1, the oil supply cavity E1, the oil supply cavity E2, the control cavity B2 and the oil inlet respectively through pipes; the oil filter is arranged in the auxiliary cavity and is used for filtering impurities in the oil , Protect the nozzle, the outer wall of the oil filter and the inner wall of the secondary cavity of the lower casing form a cavity. After the oil flows into the auxiliary cavity from the oil inlet, it flows into the control cavity B1 and B2 after being filtered by the oil filter, and flows into the oil supply through the cavity. Cavity E1, oil supply cavity E2; A fixed throttling element is arranged in the pipeline between the auxiliary cavity and the control cavity B1 and the control cavity B2; The oil return cavity is communicated with the oil return port through a pipeline; The first shuttle valve and the second shuttle valve are symmetrically arranged in the lower casing, and each includes a first oil inlet port, a second oil inlet port and an oil outlet port; the first oil inlet port of the first shuttle valve They are respectively communicated with the oil return port and the throttle groove F1 through pipelines, the second oil inlet port and the first control oil port are communicated through pipelines, and the oil outlet interface and the compensation chamber A1 are communicated through pipelines; the The first oil inlet port of the second shuttle valve is communicated with the oil return port and the throttling groove F2 through pipelines, the second oil inlet port and the second control oil port are communicated through pipelines, and the oil outlet port is connected with all the The compensation chamber A2 is communicated through a pipeline; A fixed throttle element is provided in the pipeline between the first oil inlet port of the first shuttle valve, the first oil inlet port of the second shuttle valve and the oil return port to ensure that the first shuttle valve and the oil return port are connected. The oil pressure of the first oil inlet port of the second shuttle valve is a preset pressure threshold; The first control oil port is also communicated with the oil passage chamber C1 and the feedback chamber D2 respectively through pipes; the second control oil port is also communicated with the oil passage chamber C2 and the feedback chamber D1 respectively through pipes. 2 . The piezoelectric ring-driven nozzle baffle plate pressure servo valve with hydrodynamic compensation of the main spool according to claim 1 , wherein the bottom of the upper casing cavity and the oil return cavity There is a nozzle oil return restrictor in the pipeline to prevent the oil in the oil return cavity from flowing into the cavity of the upper casing. 3. The piezoelectric ring-driven nozzle baffle plate pressure servo valve with hydrodynamic compensation of the main valve core according to claim 1, wherein the bottom of the end faces on both sides of the fixed cylinder is provided with through holes, so that the inside of the fixed cylinder is provided with through holes. The effusion flows into the cavity of the upper casing. 4. The piezoelectric ring-driven nozzle baffle pressure servo valve with hydrodynamic compensation of the main spool according to claim 1, wherein a metal film is provided on the outside of the piezoelectric sheet, so that the piezoelectric sheet and the oil Isolate and improve the service life of piezoelectric sheets. 5. The hydraulic compensation method based on the piezoelectric ring-driven nozzle baffle pressure servo valve with the hydraulic compensation of the main valve core according to claim 1, characterized in that, comprising the following steps: Step 1), adjust the control voltage of each piezoelectric sheet to zero, the distances from the first nozzle to the first baffle, the second nozzle to the second baffle are the same, and the pressures of the nozzle chambers of the first nozzle and the second nozzle are equal , the pressures of the control chambers B1 and B2 of the lower casing are the same, and the valve core is in the neutral position, the oil supply chamber E1 is closed by the first convex ring of the valve core, and the oil supply chamber E2 is closed by the third convex ring of the valve core; Step 2), adjust the control voltage of each piezoelectric sheet to a preset voltage threshold, and the preset voltage threshold is a positive value. At this time, the N ring-shaped piezoelectric sheets are synchronously deformed to the right, and the first baffle , The second baffle moves to the right synchronously with the deformation generated by the N annular piezoelectric sheets, the distance from the first baffle to the first nozzle increases, the distance from the second nozzle to the second baffle decreases, and the pressure in the control chamber B1 When the pressure is lowered, the pressure of the control chamber B2 is increased, and the main spool slides to the left; the oil inlet is communicated with the oil passage C1 through the auxiliary chamber of the lower casing and the oil supply chamber E1, and the oil flows from the first control oil port through the oil passage C1. outflow; the oil passage C2 is communicated with the oil return cavity; the oil inlet is communicated with the throttle groove F2 through the auxiliary cavity of the lower casing and the oil supply cavity E2, and the oil flows into the oil return port; the throttle groove F1 is closed, and the first No oil passes through the first oil inlet port of the shuttle valve, and its second oil inlet port is communicated with the first control oil port, and the oil flows into the compensation chamber A1 through the second oil inlet port; the first oil inlet port of the second shuttle valve It is connected with the oil inlet, the second oil inlet port is connected with the second control oil port, and the oil pressure of the first oil inlet port is relatively high, so the oil passes through the auxiliary chamber, the oil supply chamber E2, the throttle groove F2 and the second shuttle The first oil inlet port of the valve flows into the compensation chamber A2; the feedback chamber D1 communicates with the second control oil port; the feedback chamber D2 communicates with the first control oil port; the compression amount of the first return spring increases, the second The compression of the return spring is reduced; Step 3), restore the control voltage of each piezoelectric sheet to zero, at this time, the N annular piezoelectric sheets return to the initial position, the first nozzle to the first baffle, the second nozzle to the second baffle If the distance is the same, the pressures of the nozzle chambers of the first nozzle and the second nozzle are the same, and the pressures of the control chambers B1 and B2 of the lower casing are the same; the valve core returns to the neutral position under the action of the return spring.

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