Means for controlling lubrication of hermetic compressors

Claim 1

IN A REFRIGERATION SYSTEM, OR THE LIKE, INCLUDING A PLURALITY OF HERMETICALLY SEALED SUCTION COOLED COMPRESSORS LINKED IN PARALLEL AND EACH HAVING A CRANKCASE COMPARTMENT AND A MOTOR COMPARTMENT WITH MEANS FOR ALLOWING DRAINAGE OF OIL FROM THE LATTER TO THE FORMER AND POSITIVE VAPOR VENTING MEANS IN EACH CRANKCASE COMPARTMENT ADEQUATE TO MAINTAIN A VAPOR PRESSURE THEREIN AT LEAST AS LOW AS THE PRESSURE IN THE ASSOCIATED MOTOR COMPARTMENT, MEANS FOR MAINTAINING A DESIRED LEVEL OF LUBRICATING OIL IN THE CRANKCASE COMPARTMENTS OF ALL OPERATING COMPRESSORS WHEN LESS THAN ALL ARE IN OPERATION, SAID MEANS COMPRISING AN OIL LEVEL EQUALIZER CONDUIT ADAPTED TO BE EXTERNALLY ATTACHED CONNECTING THE CRANKCASE COMPARTMENTS OF ALL THE COMPRESSORS AT THE DESIRED OIL LEVEL, THE INTERNAL OIL FLOW PASSAGE OF SAID CONDUIT BEING DIMENSIONED AND ADAPTED TO LIMIT THE FLOW OF VAPOR THERETHROUGH FROM THE CRANK CASE OF ANY NON-OPERATING COMPRESSOR TO THE CRANK CASE OF AN OPERATING COMPRESSOR AND PREVENT RISE OF VAPOR PRESSURE IN THE LATTER BEYOND THE CAPACITY OF ITS VENTING MEANS TO MAINTAIN THEREIN A PRESSURE AT LEAST AS LOW AS THE SUCTION PRESSURE IN THE ASSOCIATED MOTOR COMPARTMENT FOR FACILITATING OIL DRAINAGE FROM THE LATTER TO THE FORMER.