| 摘要 |
The invention entails the use of a positive displacement pump (4) magnetically coupled to an drive motor (42) located in a conduit arrangement (60) this is parallel to the liquid line of the refrigeration system as in FIG. 5. This parallel conduit arrangement also includes a pressure regulating valve that will regulate the amount of pressure added to the liquid line by the parallel pump and piping arrangement. In addition, a check valve (47) is located in the liquid line to maintain the pressure differential added to the liquid line. This parallel piping arrangement (60) is desirable in order to allow a constant, pre-determined pressure to be added to the liquid line regardless of variations in flow rate of the liquid refrigerant. In addition, the parallel piping arrangement allows the system to operate without liquid line obstruction in the event of pump failure. The present invention involves the use of a controlled variable speed drive on the pump meter so the flow rate through the pump will more closely match the variable system flow rate. In various embodiments the pump speed can be controlled, continuously and discretely, by: the amperage draw on a rack of compressors, a signal from a pressure sensor in the liquid line, a signal combined from several sensors indicating the pressure differential across the pump, a signal from a flow sensor in the liquid line at the outlet of the liquid receiver or condenser, a signal from a pressure or flow sensing device in a bypass line to vary pump speed to limit the flow of refrigerant through the bypass, a signal from a vapor sensing device in the liquid line to vary the pump speed sufficiently to eliminate the vapor, a signal from the refrigeration rack controllers so that pump speed is varied according to any number of existing inputs, a signal obtained by measuring the "condition" (amount of subcooling) of the refrigerant at the inlet to the expansion valve, and a signal from a superheat sensor at the outlet of the evaporator. The pump of the invention consists of an outer driving magnet (200), a stationary cup (201), and an O-ring seal (202). The pump further includes an inner driven magnet (203), a rotor assembly (204) and vanes (205). The pump further includes an O-ring seal (206) and a brass head (207).
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