Abstract: An improved expansion valve (10) disclosed for use with an air conditioning system (12) for an automobile. High pressure regrigerant flow is modulated through the valve by movement of a valve member (92) in response to the superheat of the low pressure refrigerant flow through a first passage (32) in the expansion valve. The low pressure regfrigerant superheat is sensed by a power element (74) containing an adsorbent and gas which deflects a diaphragm (82) to a degree related to the superheat of the low pressure flow. The diaphragm acts on an annular seal retainer (100) to modulate the position of the valve member (92). A cupshaped high pressure seal (104) is provided between the valve member (92) and wall of the passage (54) in which the valve member moves to balance the forces on the valve member exerted by the high pressure refrigerant. The balanced valve member allows use of a compact power element, permitting the body (30) of the valve (10) to be formed of plastic.

Abstract: An improved expansion valve (10) is disclosed for use with an air conditioning system (12) for an automobile. High pressure refrigerant flow is modulated through the valve by movement of a valve member (92) in response to the superheat of the low pressure refrigerant flow through a first passage (32) in the expansion valve. The low pressure refrigerant superheat is sensed by a power element (74) containing an adsorbent and gas which deflects a diaphragm (82) to a degree related to the superheat of the low pressure flow. The diaphragm acts on an annular seal retainer (100) to modulate the position of the valve member (92). A cupshaped high pressure seal (104) is provided between the valve member (92) and wall of the passage (54) in which the valve member moves to balance the forces on the valve member exerted by the high pressure refrigerant. The balanced valve member allows use of a compact power element, permitting the body (30) of the valve (10) to be formed of plastic.