Controls for centrifugal compressors having spin vanes in their inlets

Claim 1

A REFRIGERATION SYSTEM COMPRISING A CENTRIFUGAL REFRIGERANT COMPRESSOR, A CONDENSER, AN EXPANSION VALVE AND AN EVAPORATOR CONNECTED IN A REFRIGERATION CIRCUIT, SAID COMPRESSOR HAVING AN AXIAL SUCTION GAS INLET, SPIN VANES IN SAID INLET, MEANS FORMING A CYLINDER PASSAGE, MEANS INCLUDING A PISTON SLIDABLE IN SAID PASSAGE FOR ROTATING SAID VANES TOWARDS OPEN OR CLOSED POSITIONS, SAID PASSAGE HAVING A FIRST PORTION INTO WHICH FLUID UNDER PRESSURE IS APPLIED TO MOVE SAID PISTON IN ONE DIRECTION TO ROTATE SAID VANES TOWARDS OPEN POSITIONS, SAID PASSAGE HAVING A SECOND PORTION INTO WHICH FLUID UNDER PRESSURE IS APPLIED TO MOVE SAID PISTON IN THE OPPOSITE DIRECTION TO ROTATE SAID VANES TOWARDS CLOSED POSITIONS, A COMPRESSED FLUID SUPPLY TUBE, A FLUID RETURN TUBE, A FIRST TWO-WAY VALVE CONNECTED TO SAID TUBES AND TO SAID FIRST PASSAGE PORTION, A SECOND TWO-WAY VALVE CONNECTED TO SAID TUBES AND TO SAID SECOND PASSAGE PORTION, SAID FIRST VALVE IN A FIRST POSITION ROUTING FLUID FROM SAID SUPPLY TUBE INTO SAID FIRST PASSAGE PORTION, AND IN A SECOND POSITION ROUTING FLUID FROM SAID FIRST PASSAGE PORTION INTO SAID RETURN TUBE, SAID SECOND VALVE IN A FIRST POSITION ROUTING FLUID FROM SAID SUPPLY TUBE INTO SAID SECOND PASSAGE PORTION, AND IN A SECOND POSITION ROUTING FLUID FROM SAID SECOND PASSAGE PORTION INTO SAID RETURN TUBE, MEANS INCLUDING A FIRST SOLENOID COIL FOR ADJUSTING, WHEN ENERGIZED, SAID FIRST VALVE TO ITS SAID SECOND POSITION, AND FOR ADJUSTING WHEN DEENERGIZED, SAID FIRST VALVE TO ITS SAID FIRST POSITION, MEANS INCLUDING A SECOND SOLENOID COIL FOR ADJUSTING, WHEN ENERGIZED, SAID SECOND VALVE TO ITS SAID SECOND POSITION, AND FOR ADJUSTING, WHEN DEENERGIZED, SAID SECOND VALVE TO ITS SAID FIRST POSITION, SAID COILS BEING NORMALLY DEENERGIZED, A THERMOSTAT HAVING A LOW TEMPERATURE SWITCH AND HAVING A HIGH TEMPERTURE SWITCH WITH A DEAD-BAND BETWEEN SAID SWITCHES, MEANS INCLUDING SAID LOW TEMPERATURE SWITCH FOR ENERGIZING SAID SECOND COIL, AND MEANS INCLUDING SAID HIGH TEMPERATURE SWITCH FOR ENERGIZING SAID FIRST COIL.