초록 ▼

Two or more flow control valves may be used to provide redundant flow control for a hydraulic actuator or servoactuator. The flow control valves include a sleeve, a bypass control spool, and a primary control spool. Under normal operating conditions, each bypass control spool is stationary relative

Two or more flow control valves may be used to provide redundant flow control for a hydraulic actuator or servoactuator. The flow control valves include a sleeve, a bypass control spool, and a primary control spool. Under normal operating conditions, each bypass control spool is stationary relative to the sleeve and the flow control valve functions as a four-way hydraulic flow control valve. Each flow control valve is connected to a bypass-shutoff valve including a bypass spool that is moveable from a shut-off position to a bypass position. Upon supply pressure failure to one flow control valve, the bypass spool moves to the bypass position, reducing pressure in the corresponding actuator piston chambers. When a primary control spool becomes jammed, the corresponding bypass control spool moves within its sleeve allowing a bypass groove to port control pressure to the return line, thereby reducing pressure in the corresponding actuator piston chambers.

대표청구항 ▼

What is claimed is: 1. A hydraulic flow control system for use with a tandem hydraulic actuator, said system comprising: a flow control valve assembly including a sleeve, a bypass control spool slidingly disposed within said sleeve, and a primary control spool slidingly disposed within said bypass

What is claimed is: 1. A hydraulic flow control system for use with a tandem hydraulic actuator, said system comprising: a flow control valve assembly including a sleeve, a bypass control spool slidingly disposed within said sleeve, and a primary control spool slidingly disposed within said bypass control spool; a bypass-shutoff valve hydraulically coupled to a supply line, a return line, a pressure control line, an actuator extend line and an actuator retract line; and a restrictor-check valve assembly, wherein said restrictor-check valve assembly is hydraulically coupled to said bypass-shutoff valve and said supply line. 2. The system of claim 1, wherein said primary control spool comprises one or more lands. 3. The system of claim 1, said bypass control spool comprising one or more circumferential grooves on an outer radial surface. 4. The system of claim 3, wherein said one or more grooves include a bypass groove having first and second control edges. 5. The system of claim 4, wherein said bypass control spool is movable within said sleeve from a first position in which first and second lands connected to said first and second control edges each block an orifice in said sleeve to one or more second positions in which one of said lands does not fully block one of said orifices, allowing hydraulic fluid in a bypass-shutoff valve pressure control line to enter a return line. 6. A servoactuator control system comprising: a first flow control valve having a first primary control spool slidingly disposed within a first bypass control spool and a first fixed sleeve in which said first bypass control spool is slidingly disposed; a second flow control valve having a second primary control spool slidingly disposed within a second bypass control spool and a second fixed sleeve in which said second bypass control spool is slidingly disposed; a first bypass-shutoff valve hydraulically coupled by a first hydraulic circuit to said first flow control valve; a second bypass-shutoff valve hydraulically coupled to said second flow control valve; a first restrictor-check valve assembly hydraulically coupled to said first bypass shut-off valve; a second restrictor-check valve assembly hydraulically coupled to said second bypass-shutoff valve; and a tandem hydraulic actuator hydraulically coupled to said first flow control valve and said second flow control valve. 7. The system of claim 6, wherein said first sleeve comprises an outer radial surface having one or more circumferential grooves aligned with flow paths of said first hydraulic circuit. 8. The system of claim 7, wherein said first sleeve comprises one or more sleeve orifices and flow passages connecting one or more of said circumferential grooves to an inner radial surface of said first sleeve. 9. The system of claim 6, wherein said first bypass control spool comprises an outer radial surface having one or more circumferential grooves. 10. The system of claim 8, wherein said first bypass control spool further comprises a bypass groove having first and second control edges. 11. The system of claim 10, wherein said first bypass control spool is movable from a first position that blocks fluid flow between a control fluid path in said first hydraulic circuit and a return fluid path in said first hydraulic circuit, to one or more second positions that connect said control fluid path to said return fluid path. 12. The system of claim 11, wherein a first and second lands connected to said first and second control edges block orifices in grooves connecting said return fluid paths to said bypass groove on said bypass control spool. 13. The system of claim 6, wherein said second sleeve comprises an outer radial surface having one or more circumferential grooves aligned with flow paths of said second hydraulic circuit. 14. The system of claim 13, wherein said second sleeve comprises one or more sleeve orifices and flow passages connecting one or more of said circumferential grooves to an inner radial surface of said second sleeve. 15. The system of claim 6, wherein said second bypass control spool comprises an outer radial surface having one or more circumferential grooves. 16. The system of claim 15, wherein said second bypass control spool further comprises a bypass groove having first and second control edges. 17. The system of claim 16, wherein said second bypass control spool is movable from a first position that blocks fluid flow between a control fluid path in said second hydraulic circuit and a return fluid path in said second hydraulic circuit, to one or more second positions that connect said control fluid path to said return fluid path. 18. The system of claim 17, wherein first and second lands connected to said first and second control edges block orifices in grooves connecting said return fluid paths to said bypass groove on said second bypass control spool. 19. The system of claim 6, wherein said first primary control spool is lapped and flow-ground to said first bypass spool. 20. The system of claim 6, wherein said first bypass control spool is lapped and flow-ground to said first sleeve. 21. The system of claim 6, wherein said second primary control spool is lapped and flow-ground to said second bypass spool. 22. The system of claim 6, wherein said second bypass control spool is lapped and flow-ground to said second sleeve. 23. The system of claim 6, wherein said first primary control spool and said first bypass control spool have a diametrical clearance of approximately 0.001 in. (0.00254 mm). 24. The system of claim 6, wherein said first bypass control spool and said first sleeve have a diametrical clearance of approximately 0.001 in. (0.00254 mm). 25. The system of claim 6, wherein said second primary control spool and said second bypass control spool have a diametrical clearance of approximately 0.001 in. (0.00254 mm). 26. The system of claim 6, wherein said second bypass control spool and said second sleeve have a diametrical clearance of approximately 0.001 in. (0.00254 mm). 27. The system of claim 6, said first and second primary control spools are linked at first and second input ends, respectively, to a common input shaft. 28. The system of claim 6, wherein a first longitudinal axis of said first flow control valve and a second longitudinal axis of said second flow control valve are collinear. 29. The system of claim 6, further comprising a first sleeve lock means for locking said first flow control valve relative to a manifold. 30. The system of claim 6, further comprising a second sleeve lock means for locking said second flow control valve relative to a manifold. 31. The system of claim 6, further comprising a first hydraulic null adjustment means. 32. The system of claim 6, further comprising a first seizing detection switch in communication with said first bypass-shutoff valve, said first seizing detection switch operable to produce a failure signal when said first bypass-shutoff valve is in a bypass position. 33. The system of claim 6, further comprising a second seizing detection switch in communication with said second bypass-shutoff valve, said second seizing detection switch operable to produce a failure signal when said second bypass-shutoff valve is in a bypass position. 34. A method of providing redundant flow control for a hydraulic actuator comprising the steps of: in response to failure of a first hydraulic flow control system, porting pressurized fluid from first and second cylinder chambers on respective sides of a first piston through internal ports within a bypass spool to a return line of said first hydraulic control system; and providing flow control to a second piston of a second hydraulic flow control system, wherein said second piston is connected to said first piston. 35. The method of claim 34, wherein said step of porting pressurized fluid is in response to a hydraulic supply line failure. 36. The method of claim 34, wherein said step of porting pressurized fluid chamber is in response to an actuator jam. 37. The method of claim 34, wherein said step of porting pressurized fluid cylinder comprises moving a bypass-shutoff valve from a shut-off position to a bypass position. 38. The method of claim 34, wherein said step of porting pressurized fluid comprises displacing a bypass control spool from a null position.