Provided is an air compressor which helps to attain a proper discharge air temperature and which is superior in energy saving property. There are provided an air line connecting an air compressor, an oil separator, and an after cooler; an oil circulation line connecting the air compressor, the oil separator, and an oil cooler; a bearing oil supply line connecting one end of an intermediate branching portion disposed at an intermediate point of the oil circulation line between the oil cooler and the air compressor to a bearing oil supply portion of the air compressor; an intermediate portion oil supply line connecting the other end of the intermediate branching portion to an intermediate oil supply portion of the air compressor; a branching line supplying oil to the bearing oil supply portion and the intermediate oil supply portion; a blower sending air to the oil cooler and the after cooler; a bypass line connecting one end of a bypass branching portion disposed at an intermediate point of the oil circulation line between the oil separator and the oil cooler to the downstream side of the oil cooler of the bearing oil supply line; and a control valve controlling the inflow amount of the lubricating oil to the bypass line.

A positive displacement rotary compressor is designed for near isothermal compression, high pressure ratios, high revolutions per minute, high efficiency, mixed gas/liquid compression, a low temperature increase, a low outlet temperature, and/or a high outlet pressure. Liquid injectors provide cooling liquid that cools the working fluid and improves the efficiency of the compressor. A gate moves within the compression chamber to either make contact with or be proximate to the rotor as it turns.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed. A method for sizing at least two variable capacity screw compressors and a refrigeration chiller incorporating a variable capacity screw compressor are separately presented.

Systems and methods are disclosed of monitoring performance of an incompressible fluid system. The system has a positive displacement pump and a high bandwidth pressure sensor. A method comprises sensing a pressure of the fluid with the pressure sensor, determining pump ripple frequency and hence the speed of the positive displacement pump, calculating the pump flow rate, determining a flow restriction of the fluid system based on the pressure and flow, and assessing or trending the fluid system flow restriction.

A fault diagnosis device for a fluid feed system comprises a first acquiring part acquiring values as a fluid pressure and pump rotational speed before fluid injection, a second acquiring part acquiring values as a fluid pressure and pump rotational speed during fluid injection, a pump rotational speed difference calculating part calculating a pump rotational speed difference comprising a difference between a pump rotational speed during fluid injection and a pump rotational speed before fluid injection when the fluid pressure before fluid injection and the fluid pressure during fluid injection match, and an abnormality judging part judging if an abnormality has occurred in a flow rate of fluid injected from an injection device based on the pump rotational speed difference.

Systems, methods, and computer-readable mediums are provided for improving the efficiency of a filter-type oil separator in a cooling system including a compressor that pumps a mixture of lubricating oil and refrigerant through the filter-type oil separator. The filter type oil separator is configured to receive a first portion of the mixture from the compressor, and a bypass line is configured to bypass a second portion of the mixture around the filter-type oil separator. The bypass line ensures a sufficient amount of oil is present in the compressor.

Variable volume ratio compressors may be controlled using a switching parameter based on compressor speed and suction density to improve the matching of compressor volume ratio to desired discharge conditions. Delay periods may be implemented in the determination of when to change volume ratio to control the frequency of changes to the volume ratio. The switching parameter may be a product of the compressor speed and suction density. The volume ratio of the compressor may be controlled by switching valves directing pressure to a piston of a variable volume ratio system of the compressor.

A vane pump (101) for an automatic transmission includes a suction-side behind-vane pressure duct (112) and a pressure-side behind-vane pressure duct (111). The suction-side behind-vane pressure duct (112) is connected to the pressure side (116) of the vane pump (1). A valve device (113, 114) is connected to the pressure-side behind-vane pressure duct (111). During operation of the vane pump (101), a pressure-side behind-vane pressure (p DH) can be set in the pressure-side behind-vane pressure duct (111) with the valve device (113, 114).

A two-stage variable-displacement oil pump includes a casing having a suction port for suctioning oil stored in an oil tank and a discharge port for discharging, to a main gallery; an outer cam ring rotatably installed with respect to a pivot shaft provided inside the casing and having a rotary chamber therein; a rotor installed to be eccentric relative to the outer cam ring, rotating in concert with a rotation of a driving shaft, and including a plurality of vanes radially and slidably installed on an outer circumferential surface of the rotor; a support spring having one end contacting a spring support part formed on an outer side surface of the cam ring and the other end contacting an inner side surface of the casing; and a regulating chamber provided between the outer cam ring and the casing.

Variable volume ratio compressors may be controlled using a switching parameter based on compressor speed and suction density to improve the matching of compressor volume ratio to desired discharge conditions. Delay periods may be implemented in the determination of when to change volume ratio to control the frequency of changes to the volume ratio. The switching parameter may be a product of the compressor speed and suction density. The volume ratio of the compressor may be controlled by switching valves directing pressure to a piston of a variable volume ratio system of the compressor.