Servo valve

Patent metadata

Field	Value
Publication number	US-10767778-B2
Application number	US-201816224837-A
Country	US
Kind code	B2
Filing date	Dec 19, 2018
Priority date	Dec 22, 2017
Publication date	Sep 8, 2020
Grant date	Sep 8, 2020

Abstract

A servo valve comprising first and second nozzles and first and second piezoelectric actuators arranged to control fluid flow through the first and second nozzles respectively. A first fluid flow path is defined between the first nozzle and the first piezoelectric actuator and a second fluid flow path is defined between the second nozzle and the second piezoelectric actuator. The first and second piezoelectric actuators are arranged such that applying a voltage to the first and second piezoelectric actuators causes a change in dimension thereof, which acts to open or restrict said first and second fluid flow paths respectively.

First claim

The invention claimed is:

1. A servo valve comprising:
first and second nozzles; and
first and second piezoelectric actuators arranged to control fluid flow through the first and second nozzles respectively, wherein:
a first fluid flow path is defined between the first nozzle and the first piezoelectric actuator;
a second fluid flow path is defined between the second nozzle and the second piezoelectric actuator; and
the first and second piezoelectric actuators are arranged such that applying a voltage to the first and second piezoelectric actuators causes a change in dimension thereof, which acts to open or restrict said first and second fluid flow paths respectively; and

the servo valve further comprising:
a servo valve housing including a pair of nozzle cavities, each housing a respective nozzle and piezoelectric actuator, wherein the piezoelectric actuators are retained in the nozzle cavities by contact between a first axial end of each piezoelectric actuator opposite a second axial end facing the nozzle and a wall defined by the respective nozzle cavity, wherein the wall is a common wall shared by the first and second nozzle cavities and separating the first and second nozzle cavities.

2. The servo valve of claim 1 , wherein the first and second piezoelectric actuators are arranged such that the change in dimension thereof increases or decreases a gap between the first and second piezoelectric actuators and the first and second nozzles respectively.

3. The servo valve of claim 1 , wherein the first and second nozzles define first and second nozzle axes, the first and second piezoelectric actuators extend along the first and second nozzle axes respectively, and the change in dimension of the first and second piezoelectric actuators causes the first and second piezoelectric actuators to expand or contract along the first and second nozzle axes respectively.

4. The servo valve of claim 3 , wherein the first and second nozzle axes are aligned with each other.

5. The servo valve of claim 1 , wherein each piezoelectric actuator comprises a piezoelectric element and a blocking element, the blocking element is at the second axial end of the piezoelectric actuator facing the respective nozzle, and comprises a surface for engaging a nozzle outlet opening in the respective nozzle.

6. The servo valve of claim 1 , further comprising a first pair of caps each configured to hermetically seal a respective one of the pair of nozzle cavities from the exterior of the servo valve housing, wherein the caps are removably secured to the servo valve housing.

7. The servo valve of claim 1 , wherein the servo valve housing further includes a spool cavity housing a spool, wherein the spool has a central spool axis, a first axial end and an opposing second axial end, and the spool is configured to translate axially along the spool axis in response to a fluid bias being placed on the spool between the first and second axial ends of the spool, and the servo valve further comprises a pair of opposing spool biasing members in contact with the first and second axial ends of the spool respectively, wherein the biasing members are configured to oppose axial translation of the spool along the central spool axis.

8. The servo valve of claim 7 , further comprising:
a supply port upstream of the first and second nozzle cavities in fluid communication with the first and second fluid flow paths via the first and second axial ends of the spool and respective first and second inlet orifices;
a return port downstream of the nozzle cavities in fluid communication with the first and second fluid flow paths and the spool; and
first and second control ports for providing fluid communication between the spool and a hydraulic actuator.

9. An actuation system comprising:
the servo valve of claim 8 ; and
a hydraulic actuator in fluid communication with the first and second control ports.

10. The servo valve of claim 1 , wherein the servo valve is configured such that each piezoelectric actuator is independently controllable.

11. A method of controlling a servo valve having first and second nozzles and first and second piezoelectric actuators, wherein a first fluid flow path is defined between the first nozzle and the first piezoelectric actuator and a second fluid flow path is defined between the second nozzle and the second piezoelectric actuator, the method comprising supplying a voltage to first and second piezoelectric actuators causing a change in dimension thereof which opens or restricts the first and second fluid flow paths defined between the first and second nozzles and first and second piezoelectric actuators respectively; and
the servo valve also having:
a servo valve housing including a pair of nozzle cavities, each housing a respective nozzle and piezoelectric actuator, wherein the piezoelectric actuators are retained in the nozzle cavities by contact between a first axial end of each piezoelectric actuator opposite a second axial end facing the nozzle and a wall defined by the respective nozzle cavity, wherein the wall is a common wall shared by the first and second nozzle cavities and separating the first and second nozzle cavities.

12. The method of claim 11 , further comprising supplying voltage to each piezoelectric actuator independently to change the axial dimension of each piezoelectric actuator independently.

13. The method of claim 12 , wherein the servo valve has a spool having a central spool axis, a first axial end and an opposing second axial end, the first nozzle is in fluid communication with the first axial end of the spool, and the second nozzle is in fluid communication with the second axial end of the spool, the method further comprising generating a fluid bias between the first and second axial ends of the spool by the opening or restricting of said first and second fluid flow paths by the first and second piezoelectric actuators respectively.

Assignees

• Hamilton Sundstrand Corp
• Hamilton Sunstrand Corp

Inventors

• Jaśkiewicz Zbigniew

Classifications

• F16K31/426 Primary

  the actuated valves being cylindrical sliding valves · CPC title

• F15B13/0435

  the pilot valves being sliding valves · CPC title

• F15B13/043

  with electrically-controlled pilot valves · CPC title

• F16K31/007

  Piezoelectric stacks · CPC title

• F15B13/0438

  the pilot valves being of the nozzle-flapper type · CPC title