An embodiment of a system with a minute measure of pulsatility in a flow of a fluid is described that comprises a first pump configured to flow the fluid to a junction at a first flow rate that comprises a measure of pulsatility; and a second pump configured to flow a portion of the fluid from the junction at a second flow rate that is less than the first flow rate to produce a flow of the fluid at a third flow rate from the junction with a minute measure of pulsatility.

A variable displacement pump is provided which better distributes stress across the rotor structure thereby reducing the risk of the rotor cracking and/or failing. The variable displacement pump includes a housing, a vane control ring, a rotor, a plurality of vanes, a slider ring, a biasing means, and a regulator valve. The housing defines an inlet port and a discharge port. The rotor may be rotationally driven by a drive shaft and coaxially aligned with the drive shaft. The rotor may define a plurality of primary ribs and a plurality of corresponding secondary ribs with an aperture defined between each primary rib and secondary rib. Each primary rib defines a primary rib thickness and each secondary rib defines a secondary rib thickness which is less than the primary rib thickness.

A scroll compressor is provided, in which a fastening member fixing portion of a valve fastening member fixes the valve fastening member to a non-orbiting scroll, a valve fixing portion of the valve fastening member fixes a bypass valve to the non-orbiting scroll, and the fastening member fixing portion is located axially farther away from a compression chamber than the valve fixing portion is. This may secure a fastening thickness by which the valve fastening member that fixes the bypass valve is fastened to the non-orbiting scroll and reduce a plate thickness at a portion where bypass holes and/or a discharge port are formed, thereby decreasing dead volumes in the bypass holes and/or the discharge port.

A compressor includes: a shell forming an outer portion thereof and having lower part in which an oil pan is formed to store oil; a motor provided in the shell; a compression unit provided in the shell to compress a working gas when being driven by the motor; a frame fixed to the shell and supporting the compression unit; a shaft supported by the frame, connecting the motor and the compression unit, provided to transmit a turning force of the motor to the compression unit, and including an oil passage; and an oil pump provided at lower part of the shaft to draw oil from the pan and supply the oil into the oil passage. The pump includes a bypass valve that is opened, when a pressure of oil flowing in the oil passage is higher than a threshold pressure, to return part of the oil to the pan.

An embodiment of a system with a minute measure of pulsatility in a flow of a fluid is described that comprises a first pump configured to flow the fluid to a junction at a first flow rate that comprises a measure of pulsatility; and a second pump configured to flow a portion of the fluid from the junction at a second flow rate that is less than the first flow rate to produce a flow of the fluid at a third flow rate from the junction with a minute measure of pulsatility.

A positive displacement pump for pumping oil in a motor vehicle transmission comprises a pump stage that has a central kidney-shaped suction cavity and two kidney-shaped pressure cavities. Oil is selectively pumped via one kidney-shaped pressure cavity or the other kidney-shaped pressure cavity in accordance with the direction of rotation of the pump stage. This makes it possible to create, with little complexity, two operating stages for the positive displacement pump.

A method, system, and computer-readable medium related to control of mud motors in drilling systems, of which the method includes measuring an eccentricity of rotation of a rotor in a stator of a mud motor using a rotor-position sensor, determining a torque of the mud motor based in part on the eccentricity, and selecting a fluid flow rate, a pressure, or both of fluid delivered downhole, through the mud motor, based in part on the determined torque.

A scroll compressor is provided, in which a fastening member fixing portion of a valve fastening member fixes the valve fastening member to a non-orbiting scroll, a valve fixing portion of the valve fastening member fixes a bypass valve to the non-orbiting scroll, and the fastening member fixing portion is located axially farther away from a compression chamber than the valve fixing portion is. This may secure a fastening thickness by which the valve fastening member that fixes the bypass valve is fastened to the non-orbiting scroll and reduce a plate thickness at a portion where bypass holes and/or a discharge port are formed, thereby decreasing dead volumes in the bypass holes and/or the discharge port.

A method of operating a wellhead compressor includes selecting a plurality of operating points of the wellhead compressor, measuring the tubing pressure at the plurality of operating points of the wellhead compressor and determining an efficiency achieved by the wellhead compressor when operating at each of the operating points based on at least the measured tubing pressure at each of the operating points. A production curve is generated of well pressure as a function of flow rate from a combination of measured data and predicted data. An operating point of the wellhead compressor is selected from the production curve based on at least the efficiency of the wellhead compressor at the selected operating point and the wellhead compressor is operated at the selected operating point. The steps of the method are repeated after operating the wellhead compressor at the selected operating point for a predetermined period of time.

A Method for controlling the liquid injection of a compressor device or expander device. This compressor device includes at least one compressor element or expander element, whereby the element comprises a housing that comprises a rotor chamber in which at least one rotor is rotatably affixed by means of bearings, whereby liquid is injected into the element. The method comprises the step of providing two independent separated liquid supplies to the element, whereby one liquid supply is injected into the rotor chamber and the other liquid supply is injected at the location of the bearings. The separated liquid supplies are realised by means of a modular channelling piece of an injection module.