Thermostatic expansion valve with remote adjustment

Claim 1

In a thermostatic expansion valve for a refrigeration system, said valve comprising a a valve housing having a flow path therethrough, said flow path having an inlet, an outlet, and an expansion valve seat constituting a expansion port between said inlet and said outlet, said inlet and said outlet being adapted to be connected to a liquid line of the refrigeration system for the passage therethrough of pressurized refrigerant, a valve member movable toward and away from said valve seat thereby to regulate the flow of refrigerant through said flow path, a compression coil spring for biasing said valve member toward a closed position in which said valve member cooperates with said valve seat thereby to regulate the flow of refrigerant through said flow path, expansion bulb and diaphragm means operatively connected to said valve member responsive to the load on said refrigeration system, said expansion bulb and diaphragm means and said spring operating on said valve member so as to maintain the flow of refrigerant through said flow path within a desired superheat range, and means for adjusting the superheat range of the thermal expansion valve, this last-said adjustment means comprising a spring compression member engageable with one end of said spring and being selectively axially movable relative to said spring thereby to compress or relax said spring throughout a predetermined range and thereby to vary the superheat range of said thermostatic expansion valve, wherein the improvement comprises: an adjustment stem rotatable with respect to said valve housing and having a flange engageable with said valve housing so as to prevent axial movement of said stem, said adjustment stem being threadably engageable with said spring compression member and being rotatable through a plurality of revolutions thereby to effect axial movement of said spring compression member throughout said predetermined range upon rotation of said ajustment stem, an elongate flexible shaft, one end of said flexible shaft being coupled to said adjustment stem, means for sealing said adjustment stem with respect to said housing and for permitting rotation of said adjustment means relative to said housing, said flexible shaft having a drive member on its outer end and being unaffected by the compression force of said spring, rotation of said drive member effecting corresponding rotation of said adjustment stem relative to said valve housing thereby permitting convenient adjustment of the superheat range of said thermal expansion valve from a location remote from said thermal expansion valve.