초록 ▼

A valve assembly that includes a valve body defining a fluid passage. First and second ends of the fluid passage define first and second ports for fluid flow. A spring and piston are located in the fluid passage. The piston has a travel length extending between first and second positions with a thir

A valve assembly that includes a valve body defining a fluid passage. First and second ends of the fluid passage define first and second ports for fluid flow. A spring and piston are located in the fluid passage. The piston has a travel length extending between first and second positions with a third position located therebetween. The spring biases the piston from the first toward the third position and is located outside the axial piston passage. The piston at least partially defines a first, second and at least one third opening. The first opening defines a variable constriction which increases in size as the piston moves from the first to third positions. The piston end wall defines the second opening and the piston sidewall defines the third openings. Movement of the piston from the third to second position exposes the third openings increasing the area of the second port.

대표청구항 ▼

What is claimed is: 1. A valve assembly comprising: a valve body defining a fluid passage extending through said valve body, said fluid passage having a first end and an opposite second end, said first end defining a first port through which fluid is communicated to and from said fluid passage and

What is claimed is: 1. A valve assembly comprising: a valve body defining a fluid passage extending through said valve body, said fluid passage having a first end and an opposite second end, said first end defining a first port through which fluid is communicated to and from said fluid passage and said second end defining a second port through which fluid is communicated to and from said fluid passage; a biasing element; a valve member moveably disposed within said fluid passage within said valve body, said valve member having a travel length extending from a first position relative to said valve body to a second position relative to said valve body, said biasing element biasing said valve member along said travel length from said first position toward a third position disposed between said first and second positions, said valve member at least partially defining a variable first opening, a second opening and at least one third opening, said first opening defining a variable constriction in said fluid passage between said first and second ends and having an area which progressively increases as said valve member moves from said first position toward said third position, said second opening and said at least one third opening defining said second port wherein when said valve member is disposed between said first position and said third position said second port is defined substantially solely by said second opening and when said valve member is in said second position said second port is defined by both said second opening and said at least one third opening; wherein said valve member defines a valve member passage extending from said second port to said first opening, said biasing element being disposed outside said valve member passage; and wherein fluid flow through said fluid passage within said valve body in a first direction from said second end toward said first end exerts pressure upon said valve member and biases said valve member toward said first position and wherein fluid flow through said fluid passage within said valve body in a second direction from said first end toward said second end exerts pressure upon said valve member and biases said valve member toward said second position. 2. The valve assembly of claim 1 wherein said valve member is a substantially cylindrical piston. 3. The valve assembly of claim 2 wherein said piston includes an end wall disposed at a first axial end of said piston and a substantially cylindrical sidewall wherein said valve member passage is an axially extending passage through said piston defined by said sidewall, said second opening in communication with said axial passage and being defined by said end wall, said first opening disposed proximate a second axial end of said piston opposite said first axial end, said at least one third opening being defined in said side wall proximate said first axial end of said piston. 4. The valve assembly of claim 3 wherein said piston is reciprocable within a substantially cylindrical bore defined in said valve body, said first axial end of said piston being disposed within said bore and substantially preventing the flow of fluid through said at least one third opening when said piston is disposed between said first and third positions and wherein said first axial end of said piston projects beyond said bore exposing said at least one third opening and permitting fluid flow therethrough when said piston is disposed in said second position. 5. The valve assembly of claim 3 wherein said cylindrical sidewall defines a first diameter and said biasing element is a helical spring defining a second diameter, said second diameter being larger than said first diameter. 6. The valve assembly of claim 1 wherein said travel length of said valve member includes a biased travel portion between said first and third positions wherein said biasing element biases said valve member from said first position toward said third position and an unbiased travel portion between said third-position and said second position wherein said valve member is unbiased with respect to said biasing element. 7. The valve assembly of claim 1 wherein movement of said valve member from said third position to said second position increases the area of said first opening. 8. The valve assembly of claim 1 wherein said second opening is a metering orifice having a fixed area and wherein operable coupling of said biasing element and said valve member to define said variable first opening provides a pressure-compensated flow control mechanism whereby said valve assembly limits fluid flow through said fluid passage in said first direction to a predefined maximum flow rate. 9. The valve assembly of claim 1 wherein movement of said valve member from said third position to said second position increases the area of said first opening. 10. A valve assembly comprising: a valve body defining a fluid passage extending through said valve body, said fluid passage having a first end and an opposite second end, said first end defining a first port through which fluid is communicated to and from said fluid passage and said second end defining a second port through which fluid is communicated to and from said fluid passage; a biasing element; a valve member moveably disposed within said fluid passage within said valve body, said valve member having a travel length extending from a first position relative to said valve body to a second position relative to said valve body, said valve member further defining a third position along said travel length, said third position disposed between said first and second positions, said valve member at least partially defining a variable first opening and said second port, said first opening defining a variable constriction in said fluid passage between said first and second ends and having an area that progressively increases as said valve member moves from said first position toward said third position, said second port being variably sized wherein said second port defines a first area providing fluid communication with said fluid passage when said valve member is in said third position and defines a second area providing fluid communication with said fluid passage when said valve member is in said second position, said second area being greater than said first area; said travel length including a biased travel portion between said first and third positions wherein said biasing element biases said valve member from said first position towards said third position and an unbiased travel portion between said third position and said second position wherein said valve member is unbiased with respect to said biasing element; and wherein fluid flow through said fluid passage in a first direction from said second end toward said first end exerts pressure upon said valve member and biases said valve member toward said first position and wherein fluid flow through said fluid passage in a second direction from said first end toward said second end exerts pressure upon said valve member and biases said valve member toward said second position. 11. The valve assembly of claim 10 wherein said second port is defined by a second opening having a fixed area and at least one third opening, said second port being defined by said second opening when said valve member is between said first and third positions and said second port being defined by both said second opening and said at least one third opening when said valve member is in said second position. 12. The valve assembly of claim 10 wherein said valve member is a substantially cylindrical piston. 13. The valve assembly of claim 12 wherein said piston includes a substantially cylindrical sidewall defining an axially extending passage through said piston and an end wall disposed at a first axial end of said piston, said second port including a second opening defined by said end wall and in communication with said axial passage and at least one third opening defined by said sidewall and disposed proximate said first axial end of said piston, said first opening disposed proximate a second axial end of said piston opposite said first axial end. 14. The valve assembly of claim 13 wherein said piston is reciprocable within a substantially cylindrical bore defined in said valve body, said first axial end of said piston being disposed within said bore and substantially preventing the flow of fluid through said at least one third opening when said piston is disposed between said first and third positions and wherein said first axial end of said piston projects beyond said bore exposing said at least one third opening and permitting fluid flow therethrough when said piston is disposed in said second position. 15. The valve assembly of claim 13 wherein said cylindrical sidewall defines a first diameter and said biasing element is a helical spring defining a second diameter, said second diameter being larger than said first diameter. 16. The valve assembly of claim 15 further comprising a coupling member operably disposed between said spring and said piston, said coupling member operably engageable with said piston and transferring a biasing force from said spring to said piston when said piston is disposed between said first and third positions and wherein movement of said piston from said third position toward said second position operably disengages said coupling member and said piston. 17. The valve assembly of claim 10 wherein said second port includes a metering orifice having a fixed area defining said first area and wherein operable coupling of said biasing element and said valve member to define said variable first opening provides a pressure-compensated flow control mechanism whereby said valve assembly limits fluid flow through said fluid passage in said first direction to a predefined maximum flow rate. 18. A valve assembly comprising: a valve body defining a fluid passage extending through said valve body, said fluid passage having a first end and an opposite second end, said first end defining a first port through which fluid is communicated to and from said fluid passage and said second end defining a second port through which fluid is communicated to and from said fluid passage; a spring disposed within said fluid passage and engageable with said valve body; a piston moveably disposed within said fluid passage and operably couplable with said spring, said piston having a travel length extending from a first position in said fluid passage to a second position in said fluid passage, said piston further defining a third position along said travel length, said third position disposed between said first and second positions, said piston having a substantially cylindrical sidewall defining an axially extending passage through said piston and an end wall disposed at a first axial end of said piston, said piston at least partially defining a first opening, a second opening and at least one third opening, said first opening being in communication with said axial piston passage and disposed at a second axial end of said piston opposite said first axial end, said first opening defining a variable constriction in said fluid passage between said first and second ends and having a size which progressively increases as said piston moves from said first position toward said third position, said end wall of said piston defining said second opening, said second opening being in communication with said axial piston passage, said piston sidewall defining said at least one third opening proximate said end wall wherein, when said piston is disposed between said first and third positions, said second port is defined substantially solely by said second opening and when said piston is in said second position, said second port is defined by both said second opening and said at least one third opening; wherein said spring is disposed outside said axial piston passage; and wherein fluid flow through said fluid passage in a first direction from said second end toward said first end exerts pressure upon said piston and biases said piston toward said first position and wherein fluid flow through said fluid passage in a second direction from said first end toward said second end exerts pressure upon said piston and biases said piston toward said second position. 19. The valve assembly of claim 18 wherein said piston is reciprocable within a substantially cylindrical bore defined in said valve body, said first axial end of said piston being disposed within said bore and substantially preventing the flow of fluid through said at least one third opening when said piston is disposed between said first and third positions and wherein said first axial end of said piston projects beyond said bore exposing said at least third opening and permitting fluid flow therethrough when said piston is disposed in said second position. 20. The valve assembly of claim 18 wherein said cylindrical sidewall defines a first diameter and said spring is a helical spring defining a second diameter, said second diameter being larger than said first diameter. 21. The valve assembly of claim 20 wherein said piston includes a radially outwardly extending flange operably couplable with said spring. 22. The valve assembly of claim 21 further comprising a coupling member operably disposed between said spring and said flange, said coupling member having an outer perimeter disposed radially outwardly of said flange, said coupling member operably engageable with said flange and transferring a biasing force from said spring to said flange when said piston is between said first and third positions, a radially outer portion of said coupling member engaging said valve body when said piston is in said third position and movement of said piston from said third position to said second position operably disengaging said coupling member and said flange. 23. The valve assembly of claim 22 wherein said flange is received in a relief bore having a configuration preventing the entry of said coupling member to disengage said coupling member and said flange. 24. The valve assembly of claim 18 wherein movement of said piston from said third position to said second position increases the area of said first opening. 25. The valve assembly of claim 18 wherein said travel length of said piston includes a biased travel portion between said first and third positions wherein said spring biases said piston from said first position toward said third position and an unbiased travel portion between said third position and said second position wherein said piston is unbiased with respect to said spring. 26. The valve assembly of claim 18 wherein said second opening is a metering orifice having a fixed area and said valve assembly further comprises a baffle member disposed within said fluid passage wherein said variable first opening is defined between said baffle member and said piston and operable coupling of said spring and piston provides a pressure-compensated flow control mechanism whereby said valve assembly limits fluid flow through said fluid passage in said first direction to a predefined maximum flow rate. 27. The valve assembly of claim 26 wherein fluid flow through said fluid passage in said second direction is substantially unregulated by said valve assembly.