A method of operating a rolling piston compressor includes determining a pressure difference (?P) between a discharge pressure (P.sub.d) within a compression volume and a suction pressure (P.sub.s) within a suction volume; determining a pressure ratio (r.sub.p) equal to the discharge pressure (P.sub.d) over the suction pressure (P.sub.s); estimating a discharge pressure (P.sub.d) based at least in part on the pressure difference (?P) and the pressure ratio (r.sub.p); determining that the discharge pressure (P.sub.d) is greater than a predetermined pressure limit (P.sub.d-limit); and lowering a target speed (?.sub.target) of the rolling piston compressor.

A linear actuator system includes a linear actuator and at least one proportional control valve and at least one pump connected to the linear actuator to provide fluid to operate the linear actuator. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The linear actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover and concurrently establishes an opening of the at least one proportional control valve to adjust at least one of a flow and a pressure in the linear actuator system to an operational set point.

An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

Techniques are provided for protecting a twin screw positive displacement pump, that include a signal processor that receives signaling containing information about power, torque, speed, viscosity and specific gravity related to the operation of the twin screw positive displacement pump; and determines whether to enter an enhanced pump protection mode for the twin screw positive displacement pump based on a relationship between an actual corrected tune ratio and a tuned ratio set point (Tune Ratio SP). In operation, the signal processor determines if the actual corrected tune ratio is<=the actual corrected tune ratio set point (Tune Ratio SP), and if so, then enters the enhanced pump protection mode, else continues to use a basic pump protection mode, and also determines the actual corrected tune ratio based on a ratio of an actual corrected torque (TAcorr) divided by a tuned corrected torque (TTcorr) at a specific operating speed.

Techniques are provided for tuning a rotary positive displacement pump. The techniques include apparatus featuring a signal processor configured to the present invention may take the form of apparatus comprising a signal processor that may be configured to receive signaling containing information about actual pump performance data related to the operation of a rotary positive displacement pump; and determine corrected published pump performance data to operate the rotary positive displacement pump by compensating published pump performance data based at least partly on the actual pump performance data. The corrected published pump performance data may include a corrected published rated power, flow and slip factor, and the actual pump performance data contains information about actual power, specific gravity and viscosity related to the operation of the rotary positive displacement pump and received from a pump controller or controlling device, including a variable frequency drive.

An oil suction device including a primary suction port installed at an inflow end of a thin pipe for sucking oil in an oil storing section, and a third suction port formed in a gap between a first tapered surface and a second papered surface due to a relative movement of the thin pipe to the thick pipe. At a suction pressure of the oil pump less than a predetermined pressure, the oil suction device sucks only oil from the primary suction port, and at a suction pressure of the oil pump equal to or more than the predetermined pressure, air is sucked from the third suction port formed in a gap between the first tapered surface and a second tapered surface due to the relative movement of the thin pipe to the thick pipe.

A fluid pump includes a motor disposed within an outer housing. The motor includes a stator and a rotor in electromagnetic communication with the stator. Windings are disposed on the stator that receive an electric current for defining the electromagnetic communication. A pump element is attached to the rotor via a drive shaft. The pump element operates with the rotor to deliver a fluid through a hydraulic fluid path. A plurality of sensors measure information related to at least one of the stator, the windings, the rotor, the pump element, the fluid and the hydraulic fluid path. A controller is in communication with the windings for delivering the electric current to the windings. The controller is also in communication with the plurality of sensors for measuring and recording the information and communicating this information to one of an external memory and an external controller.

A fluid pump includes a motor disposed within an outer housing. The motor includes a stator and a rotor in electromagnetic communication with the stator. Windings are disposed on the stator that receive an electric current for defining the electromagnetic communication. A pump element is attached to the rotor via a drive shaft. The pump element operates with the rotor to deliver a fluid through a hydraulic fluid path. A plurality of sensors measure information related to at least one of the stator, the windings, the rotor, the pump element, the fluid and the hydraulic fluid path. A controller is in communication with the windings for delivering the electric current to the windings. The controller is also in communication with the plurality of sensors for measuring and recording the information and communicating this information to one of an external memory and an external controller.

A gerotor pump includes a pump head including a configuration of gerotors for pumping in operation a fluid medium from an input port arrangement to an output port arrangement, and a motor arrangement for providing mechanical power in operation for actuating the configuration of gerotors. The configuration of gerotors includes an outer gerotor and an inner gerotor that are operable to cooperate to entrap and propel the fluid medium from the input port arrangement to the output port arrangement. At least one of the outer gerotor and the inner gerotor are fabricated from a flexible material and/or are internally structured so as to exhibit a flexible peripheral exterior surface in operation. Moreover, the outer gerotor and the inner gerotor are loaded and/or are assembled together in a preloaded state, within the pump head, so that a gap formed between the gerotors whereat they mutually cooperate for entrapping and propelling the fluid medium is maintained in a flexibly compressed state when the pump is in operation. Optionally, at least one of the outer and inner gerotors is fabricated as a hybrid component including regions of a flexible material therein, and regions of an inflexible material therein. More optionally, the flexible material has a Young's modulus in a range of 1 MegaPascal (MPa) to 5 GigaPascals (GPa), and the inflexible material has a Young's modulus in a range of 2 GPa to 420 GPa. Optionally, at least one gerotor gerotor pump is includes in a gerotor pump apparatus that includes a pulse attenuating arrangement at an output port of the gerotor pump apparatus for attenuating periodic pulses and fluctuations in a fluid flow provided in use at the output port.