REGLERBAR UPPVERMINGSANORDNING FOR EN LITEN MASSA, SERSKILT FOR ETT UTVIDGNINGSMEDEL I EN VERMEINSTELLNINGSANORDNING

摘要

The invention relates to a controlled heating system for maintaining a predetermined or set temperature in a medium of small dimensions which may be a gas, liquid or solid. A single element such as a power transistor functions as a heat transfer device for supplying heat to the medium and as a heat sensing device for sensing temperature changes in the medium which can be fed back and serve as control data for supplying make-up heat to maintain a predetermined temperature. The transistor supplies heat via heat dissipation in its collector-emitter path and senses heat changes via its base-emitter voltage which varies in response to temperature changes in the medium. The controlled heating may be applied to a valve assembly for a refrigeration plant of the kind used for controlling the flow of refrigerant from the evaporator to the compressor. The closure member for the valve unit is controlled directly or indirectly by a movable wall of an expansible chamber filled with a refrigerant medium having vapor and liquid phases. The transistor serves as a heat transfer element and as a temperature responsive sensor element.