| 摘要 |
The novelty is the low cost, versatile manner of mounting an evaporator pressure regulator valve (EPR) on a thermostatic expansion valve (TXV) to provide a compact combination valve. The TXV controls refrigerant flow to the evaporator in accordance with the pressure acting below the diaphragm and the temperature influencing the temperature responsive charged space above the diaphragm. The rider pin connecting the diaphragm to the valve is hollowed out so that the bottom of the hole in the rider pin is in the refrigerant return flow path. A restrictor is placed in the upper end of the rider pin to prevent migration of condensed refrigerant to the head chamber in the event the valve is mounted upside down. A sleeve of low thermal conductivity positioned around the rider pin where it passes through the return conduit damps temperature changes and reduces valve hunting. The EPR threads into the TXV outlet. The interior of the bellows is sealed at atmospheric pressure so the pressure on the outside of the bellows is resisted by the atmospheric pressure within the bellows as well as by the spring. When the pressure on the outside of the bellows (which is evaporator pressure in a refrigeration system) exceeds a predetermined amount, the bellows tends to collapse and the head of the bellows pulls away from the actuating pin to open the pilot valve, allowing the piston to move to the right and thus open the outlet. When the pressure falls below the desired amount, the bellows expands and moves the head of the bellows against the actuating pin to close the pilot valve. Flow through the bleed hole in the end of the piston to the pilot valve chamber rapidly raises the pressure therein so that the return spring can move the piston to close the outlet. An adapter plate is bolted to the standard TXV and carries a dome-shaped member to house the EPR and the suction line is brazed to the dome. |
