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Apparatus for and method of automatically adjusting the superheat setting of a thermostatic expansion valve

  • US 4,467,613 A
  • Filed: 03/19/1982
  • Issued: 08/28/1984
  • Est. Priority Date: 03/19/1982
  • Status: Expired due to Term
First Claim
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1. In a heat pump system comprising a compressor having an inlet and an outlet, a first coil located out of doors, a second coil located indoors, said indoor and outdoor coils being in communication with one another, a shiftable valve connected to the outlet and the inlet of the compressor and to the outdoor and indoor coils, said valve being selectively shiftable between a first position in which refrigerant is delivered from the outlet of the compressor to the outdoor coil such that the heat pump system is operated in a cooling mode and a second position in which refrigerant is delivered from the outlet of said compressor to said indoor coil such that said heat pump system is operated in a heating mode, and a thermostatic expansion valve between said indoor and said outdoor coils, said thermostatic expansion valve having a thermostatic sensor in heat transfer relation with the refrigerant discharged from one of said coils for automatically varying the flow of refrigerant through said thermostatic expansion valve so as to maintain the refrigerant entering said compressor at a predetermined superheat level, said thermostatic expansion valve being pre-set at a predetermined superheat setting, wherein the improvement comprises:

  • an electric heater in heat transfer relation with said thermostatic sensor, and control means responsive to an operating parameter of said heat pump system operating parameter for varying the heat output of said heater thereby to vary said superheat setting of said thermostatic expansion valve, said control means including means responsive to said heat pump system operating parameter when the heat pump system is in its heating mode for operating said heater along a first heater power output versus said operating parameter value function and being further responsive to said heat pump refrigeration system operating parameter when the heat pump system is in its cooling mode for operating said heater along a second heater power output function versus said operating parameter value function.

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