Means and techniques useful in refrigeration systems

Claim 1

IN A REVERSIBLE REFRIGERATION SYSTEM OF THE CHARACTER DESCRIBED THE COMBINATION COMPRISING: A COMPRESSOR HAVING A PRESSURE OUTLET AND AN EXHAUST INLET; A FIRST COIL; A SECOND COIL; A FOUR-WAY TRANSFER VALVE INCLUDING A CASING AND A VALVE ELEMENT SLIDABLY MOUNTED IN SAID CASING; AN ELECTROMAGNETICALLY OPERATED PILOT VALVE; SAID CASING HAVING A PRESSURE INLET IN COMMUNICATION WITH THE PRESSURE OUTLET OF SAID COMPRESSOR; SAID CASING HAVING AN EXHAUST OUTLET IN COMMUNICATION WITH SAID COMPRESSOR EXHAUST INLET; MEANS INTERCOMMUNICATING ONE END OF SAID FIRST COIL WITH ONE END OF SAID SECOND COIL; SAID CASING HAVING A FIRST VALVE PORT IN COMMUNICATION WITH THE OTHER END OF SAID FIRST COIL; SAID CASING HAVING A SECOND PORT IN COMMUNICATION WITH THE OTHER END OF SAID SECOND COIL; SAID VALVE ELEMENT BEING EFFECTIVE IN A FIRST POSITION THEREOF TO INTERCOMMUNICATE SAID CASING PRESSURE INLET WITH SAID FIRST PORT AND SIMULTANEOUSLY INTERCOMMUNICATE SAID CASING EXHAUST OUTLET WITH SAID SECOND PORT: SAID VALVE ELEMENT BEING EFFECTIVE IN A SECOND POSITION THEREOF TO INTERCOMMUNICATE SAID CASING PRESSURE INLET WITH SAID SECOND PORT AND TO SIMULTANEOUSLY INTERCOMMUNICATE SAID FIRST PORT WITH SAID CASING PRESSURE EXHAUST OUTLET; SAID VALVE ELEMENT HAVING A FIRST PISTON AND A SECOND PISTON RESPECTIVELY ON OPPOSITE ENDS THEREOF WHICH DEFINE WITH SAID CASING A CORRESPONDING FIRST CASING CHAMBER AND A SECOND CASING CHAMBER; SAID PILOT VALVE INCLUDING A HOUSING DEFINING TWO CHAMBERS; MEANS INTERCOMMUNICATING SAID CASING EXHAUST OUTLET WITH EACH OF THE TWO LAST MENTIONED CHAMBERS; SAID LAST TWO MENTIONED PILOT VALVE CHAMBERS BEING SEPARATED BY A WALL PORTION; TWO FLUID CHANNELS EXTENDING THROUGH SAID WALL PORTIO AND TERMINATING RESPECTIVELY AT A CORRESPONDING VALVE SEAT, ONE OF SAID FLUID CHANNELS BEING IN COMMUNICATION WITH SAID FIRST CASING CHAMBER AND THE OTHER OF SAID FLUID CHANNELS BEING IN COMMUNICATION WITH SAID SECOND CASING CHAMBER; A VALVE ELEMENT IN ONE OF SAID PILOT VALVE CHAMBERS; RESILIENT MEANS NORMALLY URGING THE LAST MENTIONED VALVE ELEMENT INTO ENGAGEMENT WITH ONE OF SAID PILOT VALVE PORTS; A SOLENOID PLUNGER MOVABLY MOUNTED IN THE OTHER OF SAID PILOT VALVE CHAMBERS AND INCLUDING VALVE MEANS COOPERATING WITH THE OTHER OF SAID PILOT VALVE PORTS; MEANS NORMALLY URGING SAID PLUNGER TO NORMALLY CLOSE THE LAST MENTIONED PORT; AND MEANS INTERCONNECTING SAID PLUNGER AND THE VALVE ELEMENT IN SAID ONE PILOT VALVE CHAMBER.