Apparatus to bias spool valves using supply pressure

Patent metadata

Field	Value
Publication number	US-9625043-B2
Application number	US-201314075804-A
Country	US
Kind code	B2
Filing date	Nov 8, 2013
Priority date	Nov 8, 2013
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

Methods and apparatus to bias spool valves using supply pressure are disclosed. An example apparatus includes a housing of a spool valve, the housing including a first port to receive a fluid at a supply pressure. The example apparatus further includes a spool within the housing. A position of the spool is to be selectively controlled via an input force acting on the spool, the position of the spool to define a path of a flow of the fluid through the spool valve from the first port to a second port of the housing. A biasing force is to bias the spool opposite the input force, the biasing force to be generated from the supply pressure applied to an end of the spool.

First claim

What is claimed is:

1. An apparatus comprising:
a housing of a spool valve, the housing including a first port to receive a fluid at a supply pressure;
a spool within the housing, a position of the spool to be selectively controlled via an input force acting on a first end of the spool, the position of the spool to define a path of a flow of the fluid through the spool valve from the first port to a second port of the housing, wherein a biasing force, acting on a second end of the spool, is to bias the spool opposite the input force, the biasing force to be generated from the supply pressure applied to the second end of the spool, the input force to be generated from an input pressure applied to the first end of the spool, the input pressure corresponding to a proportion of the supply pressure, the proportion to be less than the supply pressure;
a current-to-pressure converter to define the proportion of the supply pressure corresponding to the input pressure based on an electrical control signal; and
fluid lines to separately guide the fluid (1) indirectly to the first end of the spool via the current-to-pressure converter, (2) directly to the second end of the spool to continuously provide the biasing force when the fluid at the supply pressure is supplied, and (3) directly to the first port of the housing of the spool valve.

2. The apparatus of claim 1 , further comprising a piston coupled to the second end of the spool, the biasing force to bias the spool via the piston.

3. The apparatus of claim 1 , further comprising a bellows coupled to the second end of the spool, the biasing force to bias the spool via the bellows.

4. The apparatus of claim 1 , further comprising a diaphragm coupled to the second end of the spool, the biasing force to bias the spool via the diaphragm.

5. The apparatus of claim 1 , further comprising a spring to bias the spool to a failure position if the supply pressure is substantially reduced or zero.

6. The apparatus of claim 1 , wherein the input pressure is to be applied to a first area adjacent the first end of the spool and the supply pressure is to be applied to a second area adjacent the second end of the spool, the second area smaller than the first area.

7. The apparatus of claim 6 , wherein the second area is defined by one of a bellows, a piston, or a diaphragm.

8. The apparatus of claim 1 , further comprising first and second flow restrictors fluidly coupled in series via a chamber defined by the housing, the supply pressure to enter the chamber via the first flow restrictor, a portion of the supply pressure to escape the chamber via the second flow restrictor to define an intermediate pressure within the chamber, the biasing force to be generated by the intermediate pressure applied to the second end of the spool.

9. The apparatus of claim 1 , wherein the proportion of the supply pressure is greater than atmospheric pressure.

10. An apparatus comprising:
a spool within a spool valve to control a flow of fluid at a supply pressure through the spool valve as the spool is moved via an input force that varies in magnitude, the spool valve to define a chamber adjacent an end of the spool, wherein a biasing force is to bias the spool opposite the input force, the biasing force to be generated from a biasing pressure of the fluid within the chamber, the biasing pressure to be based on the fluid at the supply pressure being guided directly to the chamber from a supply of the fluid independent of the flow of the fluid through the spool valve, the biasing force to be applied continuously during operation of the spool valve, the spool to move to a minimum travel position by a first magnitude of the input force, an intermediate travel position by a second magnitude of the input force, and a maximum travel position by a third magnitude of the input force.

11. The apparatus of claim 10 , further comprising:
a first flow restrictor to provide fluid communication between the chamber and the fluid at the supply pressure; and
a second flow restrictor to provide fluid communication between the chamber and a second pressure lower than the supply pressure, the first and second flow restrictors disposed in series on the spool valve with the chamber disposed therebetween, wherein the first and second flow restrictors define the biasing pressure within the chamber, the biasing pressure to be between the second pressure and the supply pressure.

12. The apparatus of claim 10 , wherein the input force is generated from an input pressure applied to a second end of the spool, the input pressure to be a proportion of the supply pressure ranging from a minimum pressure to a maximum pressure corresponding to the supply pressure.

13. The apparatus of claim 12 , wherein the biasing force is less than the third magnitude of the input force corresponding to when the input pressure is at the maximum pressure.

14. The apparatus of claim 12 , further comprising a current-to-pressure converter of a digital valve controller to define the proportion of the supply pressure based on an electrical control signal.

15. The apparatus of claim 10 , further comprising a digital valve controller, wherein the spool valve is to be housed in the digital valve controller.

16. The apparatus of claim 10 , wherein the supply pressure is to be applied to a first area within the chamber adjacent the end of the spool, the input force to be generated from an input pressure applied to a second area adjacent an opposite end of the spool, the input pressure corresponding to a proportion of the supply pressure, the first area smaller than the second area.

17. An apparatus comprising:
a spool within a spool valve, the spool to be selectively moveable within the spool valve via an input force to control a flow of a supply fluid between ports in the spool valve, the supply fluid having a supply pressure; and
means for generating a biasing force to bias the spool opposite the input force, the biasing force corresponding to a biasing pressure applied to an end of the spool, the biasing pressure to be based on the supply pressure of the supply fluid, a chamber adjacent the end of the spool to be in direct fluid communication with a source of the supply fluid so that the biasing force is constantly applied to the end of the spool when the supply fluid is being supplied, the input force generated by a range of different input pressures corresponding to different proportions of the supply pressure, the range of different input pressures including a first input pressure, a second input pressure greater than the first input pressure, and a third input pressure greater than the second input pressure.

18. The apparatus of claim 17 , wherein the means for generating the biasing force includes means for reducing a first area on which the biasing pressure is applied relative to a second area on which the range of different input pressures is applied.

19. The apparatus of claim 17 , wherein the means for generating the biasing force includes means for reducing the biasing pressure relative to the supply pressure.

20. The apparatus of claim 16 , wherein a change in the supply pressure is to result in a proportional change in the biasing force.

Assignees

• Fisher Controls Int Llc

Inventors

• Winkler Richard Jay
• Metschke Christopher Steven
• Busse Bradley Dale

Classifications

• F16K31/12 Primary

  actuated by fluid ({fluid-actuated lift valves F16K1/126} ; fluid-actuated check valves F16K15/00; fluid-actuated safety valves F16K17/00) · CPC title

• F16K11/07 Primary

  with cylindrical slides · CPC title

• F15B2211/329

  actuated by fluid pressure · CPC title

• F15B2211/323

  the biasing means being adjustable · CPC title

• F16K31/1245

  with more than one valve · CPC title