Servo valve

Patent metadata

Field	Value
Publication number	US-9404513-B2
Application number	US-201414249960-A
Country	US
Kind code	B2
Filing date	Apr 10, 2014
Priority date	Apr 10, 2014
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

A servo valve includes a valve housing, a piston cylinder disposed in the housing, a piston disposed within the piston cylinder and fluidly connected on a first end to a first fluid pressure pathway and on a second end to a second fluid pressure pathway, a flapper assembly, and a flow control element disposed in the piston cylinder in a portion of the first fluid pressure pathway. The piston is configured to translate axially within the piston cylinder in response to a pressure differential between the first fluid pressure pathway and the second fluid pressure pathway. The fluid flow control element is configured to stop a flow of fluid through the first fluid pressure pathway when the piston engages the third fluid control element.

First claim

The invention claimed is:

1. A servo valve comprising:
a valve housing;
a piston cylinder disposed in the housing;
a piston disposed within the piston cylinder, the piston cylinder being fluidly connected on a first end to a first fluid pressure pathway and fluidly connected on a second end to a second fluid pressure pathway, the piston configured to translate axially within the piston cylinder in response to a pressure differential between a first fluid in the first fluid pressure pathway and a second fluid in the second fluid pressure pathway;
a flapper assembly including an activation portion and closure portion, said closure portion of the flapper assembly extending from the activation portion, said flapper assembly configured to move said closure portion to engage a first nozzle on the first fluid pressure pathway when the closure portion is in a first position and configured to move said closure portion to engage a second nozzle on the second fluid pressure pathway when the closure portion is in a second position; and
a fluid flow control element disposed in the piston cylinder in a portion of the first fluid pressure pathway and comprising a surface that is sealable with a surface of the piston, the piston configured to seal the first fluid pressure pathway and stop a flow of fluid through the first fluid pressure pathway when the piston engages the fluid flow control element.

2. The servo valve of claim 1 , wherein the piston cylinder comprises a sleeve, and the piston is disposed within the sleeve of the piston cylinder.

3. The servo valve of claim 1 , wherein the flapper assembly further comprises one or more electrical coils disposed proximal to the activation portion of the flapper assembly.

4. The servo valve of claim 1 , further comprising a second fluid flow control element disposed in the piston cylinder in a portion of the second fluid pressure pathway, the piston configured to stop a flow of fluid through the second fluid pressure pathway when the piston engages the second fluid control element.

5. The servo valve of claim 1 , wherein an outer periphery portion of the piston pressure-seals against an inner surface of the piston cylinder.

6. The servo valve of claim 1 , wherein the first fluid pressure pathway is connected on one end to a high pressure fluid pathway via a first pressure change element and on another end to a low pressure fluid pathway via the first nozzle in the first fluid pathway; and
wherein the second fluid pressure pathway is connected on one end to the high pressure fluid pathway via a second pressure change element and on another end to the low pressure fluid pathway via the second nozzle in the second fluid pathway.

7. The servo valve of claim 1 , wherein the piston includes an outer groove disposed circumferentially in a substantially cylindrical outer surface of the piston;
wherein the piston cylinder includes an opening in a sidewall of the piston cylinder fluidly connected to a high pressure fluid pathway, an opening in a sidewall of the piston cylinder fluidly connected to a low pressure fluid pathway, and an opening in a sidewall of the piston cylinder fluidly connected to an output fluid pathway;
wherein the opening to the output fluid pathway is positioned in the piston cylinder such that when the groove in the piston translates as the piston moves axially, fluid in the groove remains in fluid communication with the opening to the output fluid pathway;
wherein the opening to the high pressure fluid pathway is spaced apart from and positioned in the sidewall to a first side of the opening to the output fluid pathway, and the opening to the low pressure fluid pathway is spaced apart from and positioned in the sidewall to a second side of the opening to the output fluid pathway in an opposite axial direction from the opening to the high pressure fluid pathway;
wherein the opening to the high pressure fluid pathway is positioned in the piston cylinder such that when the groove in the piston translates as the piston moves axially in a first direction, fluid in the groove remains in fluid communication with the opening to the high pressure fluid pathway and an outer surface of the piston closes the opening to the low pressure fluid pathway; and
wherein the opening to the low pressure fluid pathway is positioned in the piston cylinder such that when the groove in the piston translates as the piston moves axially in a second direction opposite the first direction, fluid in the groove remains in fluid communication with the opening to the low pressure fluid pathway and an outer surface of the piston closes the opening to the high pressure fluid pathway.

8. The servo valve of claim 7 , wherein the piston includes a second outer groove disposed circumferentially in the substantially cylindrical outer surface of the piston;
wherein the piston cylinder includes a second opening in the sidewall of the piston cylinder fluidly connected to the high pressure fluid pathway, a second opening in the sidewall of the piston cylinder fluidly connected to the low pressure fluid pathway, and an opening in the sidewall of the piston cylinder fluidly connected to a second output fluid pathway;
wherein the opening to the second output fluid pathway is positioned in the piston cylinder such that when the groove in the piston translates as the piston moves axially, fluid in the second groove remains in fluid communication with the opening to the second output fluid pathway;
wherein the second opening to the high pressure fluid pathway is spaced apart from and positioned in the sidewall to a first side of the opening to the second output fluid pathway, and the second opening to the low pressure fluid pathway is spaced apart from and positioned in the sidewall to a second side of the opening to the second output fluid pathway in an opposite axial direction from the second opening to the high pressure fluid pathway;
wherein the second opening to the low pressure fluid pathway is positioned in the piston cylinder such that when the second groove of the piston translates as the piston moves axially in the first direction, fluid in the second groove remains in fluid communication with the second opening to the low pressure fluid pathway and an outer surface of the piston closes the second opening to the high pressure fluid pathway; and
wherein the second opening to the high pressure fluid pathway is positioned in the piston cylinder such that when the second groove of the piston translates as the piston moves axially in the second direction, fluid in the second groove remains in fluid communication with the second opening to the high pressure fluid pathway and an outer surface of the piston closes the second opening to the low pressure fluid pathway.

9. The servo valve of claim 8 , wherein the first mentioned output fluid pathway and the second output fluid pathway are operably connected to a hydraulic drive system.

10. The servo valve of claim 1 , further comprising a feedback spring connected to the closure portion of the flapper assembly on one end and the piston on another end.

11. The servo valve of claim 1 , wherein the flapper assembly is movably attached to the housing.

12. The servo valve of claim 11 , wherein the flapper assembly is rotatably attached to the housing by a pivot, wherein the pivot comprises a pivot spring.

13. A method of operating a servo valve, the method comprising:
providing a servo valve including;
a valve housing;
a piston cylinder disposed in the housing;
a piston disposed within the piston cylinder and fluidly connected on a first end to a first fluid pressure pathway and fluidly connected on a second

Assignees

• Woodward Inc

Inventors

• Baker Carthel
• Kurzynski Adam

Classifications

• F15B13/044

  operated by electrically-controlled means, e.g. solenoids, torque-motors · CPC title

• F15B9/08

  controlled by valves affecting the fluid feed or the fluid outlet of the servomotor (F15B9/06 takes precedence) · CPC title

• F15B13/0438 Primary

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