Expansion valve for preventing hunting in refrigeration system

Claim 3

An expansion valve assembly for use with a refrigeration system, comprising: housing means including first and second ports; valve means movably mounted on said housing means for controlling flow between said first and second ports, said valve means having a two part opening range bounded by a closed position and an open position and divided by a preselected part open position; actuator means operatively connected to said valve means and responsive to a fluid pressure for causing movement of said valve means in an opening direction through said positions; and biasing means coacting with said valve means for imposing on said valve means a closing force increasing (1) at a first rate as said valve means opens from said closed position to said preselected part open position and (2) at a second rate which is different from said first rate as said valve means opens beyond said preselected part open position, so as to provide a closing force inflection point at said preselected part open position, said biasing means comprising first resilient means for providing one said rate in one part of said range and second resilient means coactive with said first resilient means in the other part of said range for providing the other said rate, and means defining a lost motion space in series with said second resilient means for rendering movement of said valve means independent of said second resilient means in said one part of said opening range.

Claim 4

An expansion valve assembly for use with a refrigeration system, comprising: housing means including first and second ports; valve means movably mounted on said housing means for controlling flow between said first and second ports, said valve means having a two part opening range bounded by a closed position and an open position and divided by a preselected part open position; actuator means operatively connected to said valve means and responsive to a fluid pressure for causing movement of said valve means in an opening direction through said positions; and biasing means coacting with said valve means for imposing on said valve means a closing force increasing (1) at a first rate as said valve means opens from said closed position to said preselected part open position and (2) at a second rate which is different from said first rate as said valve means opens beyond said preselected part open position, so as to provide a closing force inflection point at said preselected part open position, said biasing means comprising first resilient means for providing one said rate in one part of said range and second resilient means coactive with said first resilient means in the other part of said range for providing the other said rate, and means defining a lost motion space in series with said second resilient means for rendering movement of said valve means independent of said second resilient means in said one part of said opening range.

Claim 5

A valve assembly according to claim 2, wherein said first resilient means is disposed in continuous engagement with said valve means for imposing a restoring force thereon causing said valve means to be normally urged in the closing direction, said second resilient means being disposed for imposing a restoring force on said valve means only after said valve means has been displaced in an opening direction past said preselected part open position.

Claim 6

A valve assembly according to claim 3, wherein the restoring forces generated by said first and second resilient means both act in a closing direction of the valve means and said lost motion space lies between said second resilient means and a surface movable with said valve means and actuator means.

Claim 7

A valve assembly according to claim 2, wherein said first resilient means coacts with said valve means, said first resilient means continuously imposing a restoring force on said valve means tending to urge same in the closing direction, said second resilient means acting on said valve means and normally tending to urge said valve means in the opening direction, said second resilient means exerting an opening force on said valve means only as said valve means is moved between said preselected part open and closed positions.

Claim 8

A valve assembly according to claim 5, wherein said valve means includes a first movable valve member disposed for coaction with a valve seat which is stationarily provided on said housing means, said second resilient means coacting on said first valve member for normally tending to move same in an opening direction, said valve means including a valve opening passing through said first valve member and a second movable valve member disposed for closing said valve opening, said first resilient means continuously urging said second valve member in a closing direction for closing said valve opening, the resilient urging of said first resilient means also continuously tending to urge said first valve member in a closing direction, and including means blocking opening of said first valve member beyond said part open position, said lost motion space lying intermediate said blocking means and a portion of said actuator means.

Claim 9

An expansion valve assembly for use with a refrigeration system, comprising: housing means including first and second ports; valve means movably mounted on said housing means for controlling flow between said first and second ports; actuator means operatively connected to said valve means and responsive to a fluid pressure for causing movement of said valve means in an opening direction, said actuator means comprising a flexible diaphragm chambered in said housing and shiftable in response to opposing pressures applied to opposite sides thereof and a connecting member coupled between said diaphragm and valve means for urging said valve means in an opening direction in response to a net pressure on one side of said diaphragm; and biasing means coacting with said valve means for urging same in a closing direction whereby said valve means is normally maintained in a closed position, said biasing means imposing a restoring force on said valve means, which restoring force increases at a first rate as said valve means is moved away from said closed position through a predetermined distance, said biasing means imposing another restoring force on said valve means as it is moved away from said closed position beyond said predetermined distance, which latter restoring force increases at a second rate which is different from said first rate, said biasing means comprising first and second bias springs and means interconnecting said first bias spring with said valve means for continuously urging said valve means in said closing direction, said second spring being responsive to opening of said valve means beyond said predetermined distance for additionally resisting opening of said valve means and means adjustably determining a lost motion space in the path between and connecting said second spring and valve means, said lost motion space being open and decreasing in size during valve means travel from the valve closed position to said predetermined opening distance and being absent during further opening of said valve means.

Claim 10

An expansion valve assembly for use with a refrigeration system, comprising: housing means including first and second ports; valve means movably mounted on said housing means for controlling flow between said first and second ports; actuator means operatively connected to said valve means and responsive to a fluid pressure for causing movement of said valve means in an opening direction, said actuator means comprising a flexible diaphragm chambered in said housing and shiftable in response to opposing pressures applied to opposite sides thereof and a connecting member coupled between said diaphragm and valve means for urging said valve means in an opening direction in response to a net pressure on one side of said diaphragm; and biasing means coacting with said valve means for urging same in a closing direction whereby said valve means is normally maintained in a closed position, said biasing means imposing a restoring force on said valve means, which restoring force increases at a first rate as said valve means is moved away from said closed position through a predetermined distance, said biasing means imposing another restoring force on said valve means as it is moved away from said closed position beyond said predetermined distance, which latter restoring force increases at a second rate which is different from said first rate, said biasing means comprising first and second bias springs and means interconnecting said first bias spring with said valve means for continuously urging said valve means in said closing direction, said second spring being responsive to opening of said valve means beyond said predetermined distance for additionally resisting opening of said valve means and means adjustably determining a lost motion space in the path between and connecting said second spring and valve means, said lost motion space being open and decreasing in size during valve means travel from the valve closed position to said predetermined opening distance and being absent during further opening of said valve means.

Claim 11

A valve assembly according to claim 7 in which said second spring is disposed in opposition to the other side of said diaphragm, and said lost motion space is disposed between said second spring and said diaphragm.

Claim 12

A valve assembly according to claim 7 in which said second spring is disposed adjacent said first spring and said lost motion space is disposed between said second spring and said valve means.

Claim 13

An expansion valve assembly for use with a refrigeration system, comprising: housing means including first and second ports; valve means movably mounted on said housing means for controlling flow between said first and second ports; actuator means operatively connected to said valve means and responsive to a fluid pressure for causing movement of said valve means in an opening direction, said actuator means comprising a flexible diaphragm chambered in said housing and shiftable in response to opposing pressures applied to opposite sides thereof and a connecting member coupled between said diaphragm and valve means for urging said valve means in an opening direction in response to a net pressure on one side of said diaphragm; and biasing means coacting with said valve means for urging same in a closing direction whereby said valve means is normally maintained in a closed position, said biasing means imposing a restoring force on said valve means, which restoring force increases at a first rate as said valve means is moved away from said closed position through a predetermined distance, said biasing means imposing another restoring force on said valve means as it is moved away from said closed position beyond said predetermined distance, which latter restoring force increases at a second rate which is different from said first rate, said biasing means comprising first and second bias springs, a spring holder operatively sandwiched between said connecting member and said first spring and movable in a valve opening direction by said connecting member and in a valve closing direction by said first spring, said valve means including a first valve member movable in an opening direction for permitting flow between said first and second ports and stopper means fixed to said first valve member for movement therewith, said spring holder being loosely disposed between said first valve member and stopper means for establishing a first lost motion space between said spring holder and stopper means, an adjusting rod carried by said housing means in backing relation to said stopper means and spaced therefrom by a second lost motion space for preventing further opening movement of said first valve member after opening movement of said valve means beyond said predetermined distance, said second spring engaging said first valve member for urging same in an opening direction, said valve means further including a passage through said first valve member and a second valve member sandwiched between said spring holder and first valve member for normally closing said passage, said spring holder being movable during opening movement of said valve means beyond said predetermined distance to close said first lost motion space and remove said second valve member from closing contact with said passage and thereby further open said valve means, whereby initial opening of said valve means is assisted by said second spring but resisted by said first spring and said further opening of said valve means is resisted by said first spring but not influenced by said second spring.

Claim 14

An expansion valve assembly for use with a refrigeration system, comprising: housing means including first and second ports; valve means movably mounted on said housing means for controlling flow between said first and second ports; actuator means operatively connected to said valve means and responsive to a fluid pressure for causing movement of said valve means in an opening direction, said actuator means comprising a flexible diaphragm chambered in said housing and shiftable in response to opposing pressures applied to opposite sides thereof and a connecting member coupled between said diaphragm and valve means for urging said valve means in an opening direction in response to a net pressure on one side of said diaphragm; and biasing means coacting with said valve means for urging same in a closing direction whereby said valve means is normally maintained in a closed position, said biasing means imposing a restoring force on said valve means, which restoring force increases at a first rate as said valve means is moved away from said closed position through a predetermined distance, said biasing means imposing another restoring force on said valve means as it is moved away from said closed position beyond said predetermined distance, which latter restoring force increases at a second rate which is different from said first rate, said biasing means comprising first and second bias springs, a spring holder operatively sandwiched between said connecting member and said first spring and movable in a valve opening direction by said connecting member and in a valve closing direction by said first spring, said valve means including a first valve member movable in an opening direction for permitting flow between said first and second ports and stopper means fixed to said first valve member for movement therewith, said spring holder being loosely disposed between said first valve member and stopper means for establishing a first lost motion space between said spring holder and stopper means, an adjusting rod carried by said housing means in backing relation to said stopper means and spaced therefrom by a second lost motion space for preventing further opening movement of said first valve member after opening movement of said valve means beyond said predetermined distance, said second spring engaging said first valve member for urging same in an opening direction, said valve means further including a passage through said first valve member and a second valve member sandwiched between said spring holder and first valve member for normally closing said passage, said spring holder being movable during opening movement of said valve means beyond said predetermined distance to close said first lost motion space and remove said second valve member from closing contact with said passage and thereby further open said valve means, whereby initial opening of said valve means is assisted by said second spring but resisted by said first spring and said further opening of said valve means is resisted by said first spring but not influenced by said second spring.