초록 ▼

A constant flow rate valve has a housing in which a rotatable sleeve is positioned between the valve's inlet and outlet. Apertures in the sleeve move into alignment with the valve's inlet and outlet upon sleeve rotation to establish the fluid flow rate. A piston is movable longitudinally within the

A constant flow rate valve has a housing in which a rotatable sleeve is positioned between the valve's inlet and outlet. Apertures in the sleeve move into alignment with the valve's inlet and outlet upon sleeve rotation to establish the fluid flow rate. A piston is movable longitudinally within the sleeve bore. The piston has openings which align with the apertures in the sleeve upon longitudinal motion of the piston. Pressure ducts connect each end of the sleeve to the inlet and outlet. The piston moves in response to relative pressure changes in the inlet and outlet communicated by the pressure ducts. The area of overlap between the piston's openings and the sleeve's apertures varies with piston motion to ensure a constant flow rate in spite of relative inlet and outlet pressure changes. The ends of the sleeve are in fluid communication to control the response sensitivity of the piston.

대표청구항 ▼

What is claimed is: 1. A valve for maintaining a substantially constant fluid flow rate in response to varying pressure across said valve, said valve comprising: a housing having an inlet duct and an outlet duct; a sleeve rotatably positioned within said housing; an inlet aperture and an outlet ape

What is claimed is: 1. A valve for maintaining a substantially constant fluid flow rate in response to varying pressure across said valve, said valve comprising: a housing having an inlet duct and an outlet duct; a sleeve rotatably positioned within said housing; an inlet aperture and an outlet aperture extending through said sleeve, rotation of said sleeve aligning at least a portion of said inlet and outlet apertures with said in let and outlet ducts respectively, said fluid flow rate being proportional to a first area of overlap of at least one of said inlet and outlet apertures with one of said inlet and outlet ducts; a piston slidably positioned within said sleeve, said piston having first and second ends oppositely disposed; a conduit providing fluid communication between said first and second ends of said piston, said conduit controlling sensitivity of response of said piston to pressure changes between said inlet and outlet ducts; and an inlet opening and an outlet opening extending through said piston, sliding motion of said piston aligning at least a portion of said piston's inlet and outlet openings with said sleeve's inlet and outlet apertures respectively, said flow rate being further proportional to a second area of overlap of at least one of said inlet and outlet openings of said piston with one of said inlet and outlet apertures of said sleeve, said piston being movable in response to said pressure to vary said second area of overlap to maintain said fluid flow rate substantially constant. 2. A valve according to claim 1, wherein said inlet aperture has an elongated shape extending in a circumferential direction around said sleeve. 3. A valve according to claim 2, wherein said inlet aperture has first and second ends, said inlet aperture being wider at said first end than at said second end. 4. A valve according to claim 1, wherein said inlet opening in said piston has a T shape, the leg of said T shape being substantially aligned with the direction of motion of said piston within said sleeve. 5. A valve according to claim 1, wherein said outlet aperture has an elongated shape extending in a circumferential direction around said sleeve. 6. A valve according to claim 5, wherein said outlet aperture has first and second ends, said outlet aperture being wider at said first end than at said second end. 7. A valve according to claim 1, wherein said outlet opening in said piston has a T shape, the leg of said T shape being substantially aligned with the direction of motion of said piston within said sleeve. 8. A valve according to claim 1, further comprising a biasing member positioned within said sleeve for biasing said piston toward said first pressure duct. 9. A valve according to claim 1, further comprising a trim valve positioned within said conduit, said trim valve being adjustable to control the flow of fluid through said conduit and thereby adjust the sensitivity of response of said piston. 10. A valve adapted to maintain a constant fluid flow rate in response to varying fluid pressure across said valve, said valve comprising: a housing having an inlet duct and an outlet duct; a sleeve having a sidewall with an inlet aperture and an outlet aperture, said sleeve being positioned within said housing between said inlet and said outlet ducts, said sleeve being rotatable to position at least a portion of said inlet and said outlet apertures in overlapping relation with said inlet and outlet ducts respectively for establishing said fluid flow rate through said valve; a piston positioned within said sleeve, said piston having first and second ends oppositely disposed, said piston having an inlet opening and an outlet opening, said piston being movable to position at least a portion of said inlet and outlet openings into overlapping relation with said inlet and said outlet apertures respectively; a first pressure duct providing fluid communication between said inlet duct and a first end of said piston; a second pressure duct providing fluid communication between said outlet duct and a second end of said piston opposite said first end; and wherein said piston moves within said sleeve in response to pressure changes within said inlet said outlet ducts thereby bringing said portions of said openings in said piston into overlapping relation with said apertures in said sleeve to maintain said constant fluid flow rate. 11. A valve according to claim 10, wherein said inlet aperture has an elongated shape extending in a circumferential direction around said sleeve. 12. A valve according to claim 11, wherein said inlet aperture has first and second ends, said inlet aperture being wider at said first end than at said second end. 13. A valve according to claim 10, wherein said inlet opening in said piston has a T shape, the leg of said T shape being substantially aligned with the direction of motion of said piston within said sleeve. 14. A valve according to claim 10, wherein said outlet aperture has an elongated shape extending in a circumferential direction around said sleeve. 15. A valve according to claim 14, wherein said outlet aperture has first and second ends, said outlet aperture being wider at said first end than at said second end. 16. A valve according to claim 10, wherein said outlet opening in said piston has a T shape, the leg of said T shape being substantially aligned with the direction of motion of said piston within said sleeve. 17. A valve according to claim 10, further comprising a biasing member positioned within said sleeve for biasing said piston toward said first pressure duct. 18. A valve according to claim 10, wherein both said inlet and outlet apertures have an elongated shape extending in a circumferential direction around said sleeve. 19. A valve according to claim 18, wherein said inlet and outlet apertures each have first and second ends, said apertures being wider at said first ends than at said second ends. 20. A valve according to claim 19, wherein both said inlet and outlet openings in said piston each have a T shape, the legs of said T shapes being substantially aligned with the direction of motion of said piston within said sleeve. 21. A valve according to claim 10, further comprising a conduit providing fluid communication between said first and second ends of said piston, said conduit controlling sensitivity of response of said piston to pressure changes between said inlet and outlet ducts. 22. A valve according to claim 21, further comprising a trim valve positioned within said conduit, said trim valve being adjustable to control the flow of fluid through said conduit and thereby adjust the sensitivity of response of said piston.