Dunham-bush

Clifford T Bulkley

David N Shaw

Joseph A Gagnon

Grover Fraser

Harold W Moody, Jr

A helical screw rotary compressor for a closed loop refrigeration system such as an air conditioning system for a bus or like vehicle is connected in series with a condenser and an evaporator, in that order, with the evaporator at a raised position relative to the compressor and utilizes a vaporizable refrigerant which is miscible with a lubricating oil employed to lubricate the moving components of the screw compressor. The bus engine driven, clutch operated, helical screw rotors are mounted within parallel intersecting bores within the compressor housing. A slide valve underlies the intermeshed rotors and forms a portion of the screw compressor envelope, the rotors opening to a suction port connected to the outlet side of the evaporator above the rotors. A high pressure discharge port at one end of the intermeshed rotors leads to an auxiliary chamber bearing an unload cylinder which drives the slide valve and which opens at the top to a housing discharge port leading to the condenser. An oil separator is interposed within the auxiliary chamber above the unload cylinder. An oil drain passage leads from the auxiliary chamber to an oversized oil sump within the housing beneath the rotors. The slide valve slides in a recess within the casing underlying the rotors. On the suction port side of the recess, a further drain passage leads through a drainage check valve to the sump. This structural arrangement permits all condensed refrigerant and the oil to return by gravity flow to the oil sump whose capacity is at least 1.5 times the volume of the normal oil charge for the system. Condensed refrigerant miscible in the oil and the oil entraining the refrigerant, upon compressor shut down, accumulates in the sump but does not reach the intermeshed rotors and thus prevents clutch burnout by liquid locking during initiation of compressor operation with the clutch mechanically connecting the engine to the intermeshed helical screw rotors.

Helical screw rotary compressor for air conditioning system having

An air motor, responsive to change in pressure of a compressed air supply line acts to control the flow of hydraulic motive fluid to a hydraulic motor which drives the capacity control slide valve of a helical screw, rotary compressor feeding the supply line. To eliminate hunting of the slide valve which shifts in response to change in compressor load, a mechanical feedback from the hydraulic motor modulates the flow of motive fluid to the hydraulic motor.

Growing community of inventors

Glastonbury, CT, United States of America

Clifford T Bulkley