Abstract: A resonator in a closed fluid system includes a body having a passageway in communication with a closed fluid system wherein a piston is movable within the passageway. Each position of the piston within the passageway defines a noise attenuation frequency corresponding to a noise frequency generated by the closed fluid system. A device providing a pressurized fluid from the closed fluid system selectively moves the piston within the passageway to vary the noise attenuation frequency.

Abstract: A system is provided for attenuating noise in at least two positive displacement compressors proximately located from each other for use with at least one heating or cooling system. A lead compressor and a lag compressor have a selectably controllable rotational speed and a selectably controllable phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at a predetermined rotational speed that is substantially the same for each of the compressors. The controller controls the phase of operation of the compressors by shifting the phase of operation of the lag compressor so that an outlet pressure pulse operatively produced by the lag compressor is substantially evenly spaced between successive outlet pressure pulses operatively produced by the reference compressor.

Abstract: In a screw compressor, guide bushings are mounted within bores for the bearings which support rotor shafts for the compressor. First bushings are provided at an inlet casing of the compressor and provide guidance for a slide stop and second bushings are provided in an outlet casing of the compressor to provide guidance for a slide valve. The bushings are also mounted to the inlet and outlet casings to provide centering for two sections of the compressor rotor housing. In one embodiment the first and second bushings provide guidance for a slide valve.

Abstract: An axial flow helical screw compressor with a slide valve and slide stop mounted end to end in communication with the intermeshing rotors has means for changing the volume ratio during operation by stepwise movement of the slide stop and for changing the capacity during operation in infinitely variable fashion, both in response to system operating conditions. In the event of interference between the movements of the slide stop and slide valve, the components are designed so that the movements of the slide stop overpowers that of the slide valve.

Abstract: A radial and thrust bearing mounting particularly adapted for a helical screw type compressor, is provided in which the radial load is isolated from the thrust load to prevent the thrust bearing from carrying any substantial radial load, and in which adjustment of the axial discharge end clearance between the faces of the rotors and the discharge end of the housing cover is provided.