Abstract: A rotary air compressor system of the screw type having an intake valve designed to have a closed condition at start-up, and having intake valve controls for effecting an initial lubrication and cooling of the compressor at start-up and a reduced strain on the motor.

Abstract: A multiple displacement pump system utilizing a single fixed displacement pump having pumping elements providing both first and second sets of pumping chambers. Circuit means having a fluid utilization conduit provides for delivery of fluid to said fluid utilization conduit which is either the sum of fluid delivered from both sets of pumping chambers or from only one set of pumping chambers. Additionally, the circuit means includes various alternate forms of control dependent upon pressure in a part of the system or on speed of a mechanism utilizing the pumped fluid to establish conditions wherein fluid delivered by the system is at either a desired flow rate or within a range of flow rates at different pressures.

Abstract: A variable capacity rotary screw compressor driven by an electric motor and having an adjustable slide valve for varying compressor capacity is provided with a control system for adjusting the slide valve to regulate compressor capacity and thereby maintain a variable system condition, such as gas inlet or outlet pressure or temperature, within a predetermined range. The control system comprises first means including a current transformer for sensing changes in motor current as compressor capacity varies and a current converter connected to the current transformer for providing a first electrical signal proportional to compressor capacity. The control system also comprises means for sensing changes in the particular system condition being monitored and for providing a second electrical signal proportional thereto.

Abstract: A positive displacement gas compressor includes an inlet throttling valve which has an actuator responsive to a pressure fluid signal for closing the throttling valve. A control circuit for supplying pressure fluid to close the throttling valve includes a time delay device and a pilot operated valve which vents the pressure fluid signal holding the throttling valve closed after a predetermined time period commencing with startup of the compressor.

Abstract: A positive displacement rotary compressor is in circuit with a closable chamber disposed upstream of the compressor gas inlet and including a conduit operable to be placed in communication with the compressor discharge conduit. A control circuit is operable to sense compressor discharge pressure and at a predetermined pressure condition sequentially operate valves to shut off compressor inlet flow thereby evacuating the chamber and then placing the compressor discharge port in communication with the chamber. The compressor thereby runs unloaded or at idle at a greatly reduced inlet and discharge pressure. The operation of unloading the compressor may be controlled by sensing the chamber vacuum or by the use of time delay devices.

Abstract: An improved rpm regulator for a fuel injection pump associated with an internal combustion engine. The regulator includes a control lever, a fuel quantity control sleeve connected to the control lever, a regulating spring assembly connected to the control lever, a device for generating an rpm signal and applying a corresponding force through the control lever to the fuel quantity control sleeve in opposition to a force exerted by the regulating spring assembly and an adjustment lever connected to the regulating spring assembly for adjusting the preload exerted by the regulating spring assembly. The regulating spring assembly is improved and includes two holding members containing two compression springs so that when the two holding members are moved outwardly relative to each other the two springs are compressed. The springs are chosen and the holding members designed so as to minimize the degree of variation which can occur during a control process.

Abstract: An axially shiftable slide valve member in a rotary, helical screw compressor carries a port which senses the pressure of the working fluid in the trapped volume just before uncovering of the closed thread to the discharge port and compares that pressure with the line pressure at the discharge port and shifts the slide valve member to balance the pressures and prevent overcompression or undercompression of the compressor. The screw compressor may be provided with two identical but oppositely oriented slide valve members on opposite sides of the intermeshed helical screws with one slide valve member controlling the capacity of the compressor and the other balancing the closed thread pressure at discharge with discharge line pressure. Compressor rotation may be reversed to eliminate the need for a reversing valve where the compressor operates in heat pump or reverse flow defrost refrigeration applications, with the two slide valves trading functions.