Abstract: The disclosed technology generally relates to a compressor housing that includes a main housing portion and an end housing portion. The main housing portion is configured to house a compressor motor and an inlet housing. The inlet housing is configured to receive vapor refrigerant downstream of the compressor motor. The main housing portion and the end housing portion are configured to interface at a mating surface of the respective housing portions and define a volume. The end housing portion includes a sensor cavity extending into the volume toward an opening of the inlet housing.

Abstract: A tip seal 1 for a scroll compressor capable of reducing a frictional force between scroll members and the tip seal where the tip seal 1 has a spiral shape for sealing a compression chamber formed between a fixed scroll and a movable scroll in a scroll compressor provided with the fixed scroll. The movable scroll having a plurality of concave parts 4 being formed by partially notching a sliding surface 5 on the scroll members, the concave parts 4 being arranged on at least one of a spiral inner peripheral surface 1b or a spiral outer peripheral surface 1a. Each of the concave parts 4 being open to the inner peripheral surface 1b or the outer peripheral surface 1a.

Abstract: A mobile chemical mixing plant includes an inlet for receiving fluid; a fluid conduit for conveying the fluid from the inlet; a container for containing a chemical therein; a chemical pump for withdrawing the chemical from the container and directing the chemical into the fluid conduit for mixing with the fluid in the fluid conduit to form a chemical mixture; and a homogenization pump for pumping the chemical mixture in the fluid conduit out of the mobile chemical mixing plant. The fluid conduit connects the chemical pump to the homogenization pump. The mobile chemical mixing plant is fixed to a trailer that is attachable to a vehicle. Because the fluid conduit directly connects the chemical pump to the homogenization pump, the mobile chemical mixing plant does not need an intervening mixing tank for mixing the fluid and the chemical.

Abstract: An exhaust assembly and a compressor including the exhaust assembly. The exhaust assembly includes an exhaust bearing seat; an intake cavity is provided at an intake end of the exhaust bearing seat; an exhaust cavity is provided at an exhaust end of the exhaust bearing seat; the intake cavity and the exhaust cavity are staggered with each other in the axial direction of the exhaust bearing seat; the exhaust bearing seat is provided with a flow passage for connecting the intake cavity with the exhaust cavity; and an oil separation structure is provided in the exhaust cavity.

Abstract: A liquid-injected screw compressor includes: a casing that houses a screw rotor and a bearing, and has a suction port and a suction chamber connected to the suction port; a suction throttle valve that is installed at the suction port, and has a housing; and an intake-gas bypass system that establishes communication between a primary side and a secondary side of the suction throttle valve. The intake-gas bypass system includes: an intake-gas bypass flow path that is provided in a wall section of the housing, and has a primary-side opening section opening into the primary side of the suction throttle valve, and a secondary-side opening section opening into the secondary side of the suction throttle valve; and a first check valve arranged in the intake-gas bypass flow path. The intake-gas bypass flow path has an external opening section that opens to an outside of the housing and that allows insertion and withdrawal of the first check valve.

Abstract: A mud motor stator or a pump comprising of a tubular outer portion; a number of lobes extending radially inwardly from the tubular outer portion, at least one of which comprises a skeletal structure and method for producing a mud motor stator or a pump comprising of placing material and bonding the material together in a pattern dictated by the design shape of the stator or pump.

Abstract: An oil circuit for lubrication and cooling of an oil-free compressor with an oil reservoir and a rotary oil pump to drive oil to the compressor element and/or the motor via an oil pipe. The rotary oil pump has a rotor mounted on a rotation shaft, and is driven by the motor of the compressor. The oil circuit is provided with a bypass pipe and a pressure-actuated bypass valve which guide a portion of the oil back to the oil reservoir without this portion of the oil passing through the compressor element and/or the motor during its way back to the oil reservoir. The oil circuit is further provided with an oil cooler in the bypass pipe. The bypass valve is in the oil pipe.

Abstract: A rotor for a rotary electric machine, the rotor including: a rotor core; a rotor shaft having a tubular shape, passing through a radially inner side of the rotor core to be coupled to the rotor core, and extending along an axial direction; an oil supply path that supplies oil to the rotor shaft, a portion to be lubricated that is disposed on a first axial side with respect to the rotor core, wherein one side in the axial direction is defined as the first axial side and another side in the axial direction is defined as a second axial side; and a lubrication oil path through which oil is supplied to the portion to be lubricated.

Abstract: A compressor may include first and second compression members, first and second bearing assemblies, a sensor, and processing circuitry. The second compression member cooperates with the first compression member to define a compression pocket. The first and second bearing assemblies rotatably support the first and second compression members, respectively. The first bearing assembly may include a bearing rotor and a bearing stator. The bearing stator may surround the bearing rotor and may include poles each having a winding. The sensor may measure a radial position of the bearing rotor relative to the bearing stator. The processing circuitry may be in communication with the sensor and may control electrical current supplied to the windings based on the radial position measured by the sensor to adjust the radial position of the bearing rotor relative to the bearing stator.

Abstract: A gerotor pump assembly, and a system and method for operating a gerotor pump assembly, result in a lubrication strategy for operating in a loss-of-prime mode. An inner drive gear may be rotated in a first direction and in a second opposite direction about an axis of rotation. The inner drive gear has a number of projections extending outwardly therefrom. An outer driven gear surrounds the inner drive gear and defines a number of recessions along an inner surface configured to engage with the projections of the inner drive gear. The outer driven gear and the inner drive gear further define at least one dynamically-changing fluid cavity therebetween. The inner drive gear and the outer driven gear define an oil transfer volume clearance between a projection and a recession in a fully engaged position. Oil is maintained within the oil transfer volume clearance as the inner drive gear is rotated.

Abstract: In a general aspect, fluid flow in a gerotor system is enhanced. In some cases, a gerotor apparatus includes inner and outer gears. The outer gear includes inward-facing teeth and an inner surface that defines an inner profile of the outer gear. The inner gear includes outward-facing teeth and an outer surface that defines an outer profile of the inner gear. The inner gear and the outer gear reside in contact such that the inner profile of the outer gear seals against the outer profile of the inner gear at multiple distinct points. One or more cutouts are defined by the inner surface of the outer gear between a neighboring pair of the inward-facing teeth, by the outer surface of the inner gear between a neighboring pair of the outward-facing teeth, or both.

Abstract: A scroll compressor includes a fixed scroll and an orbiting scroll, which are made of materials having different strengths and which include respective scroll laps. The scroll lap of the fixed scroll and the orbiting scroll having a lower material strength has a thickness satisfying tl=2a?, where tl represents scroll lap thickness, a represents basic circle radius, and ? represents phase angle. The scroll lap of the fixed scroll and the orbiting scroll having a higher material strength has a thickness satisfying th=2a?, where th represents scroll lap thickness, a represents basic circle radius, and ? represents phase angle. The scroll lap thickness th of the fixed scroll and the orbiting scroll having the higher material strength is set to be less than the scroll lap thickness tl of the fixed scroll and the orbiting scroll having the lower material strength.

Abstract: Rotor and/or stator designs and methods thereof to improve progressive cavity motor or pump durability. In one or more implementations, the rotor may have a variable outer diameter or variable stiffness along an axial length thereof. The stator may similarly have a variable inner diameter or variable stiffness, which may compliment or diverge from the variable outer diameter or variable stiffness of the rotor.

Abstract: A stator for an eccentric screw pump with an internal hollow space with a helically coiled inner contour for accommodating a rotor. The stator includes a stator core arranged in a stator casing, which stator core includes at least two radially separable core parts. According to the invention, the at least two radially separable core parts are each made from a metallic material or a technical ceramic material. The stator casing is a stator tube and is made of a metallic material. The stator casing is shrink-fitted onto the stator core. The invention also relates to an eccentric screw pump and a method for producing a stator.

Abstract: A method for operating a progressive cavity pump wherein the stator has at least first and second active stator sections that are at different locations on the stator, comprising inserting a first rotor having a first active rotor section that is aligned with the first active stator section, and rotating the first rotor relative to the first active stator section such that the aligned first active rotor and stator sections generate a pumping force. Subsequently, the first rotor is removed and a second rotor is inserted having a second active rotor section that is aligned with the second active stator section, and rotating the second rotor relative to the second active stator section such that the aligned second active rotor and stator sections generate a pumping force.

Abstract: A rotary engine casing having at least one end wall of an internal cavity for a rotor including a seal-engaging plate sealingly engaging the peripheral wall to partially seal the internal cavity and a member mounted adjacent the seal-engaging plate outside of the internal cavity. The member and seal-engaging plate having abutting mating surfaces which cooperate to define between them at least one fluid cavity communicating with a source of liquid coolant. When the casing includes a plurality of rotor housings, the end wall may be between rotor housings. A method of manufacturing a rotary engine casing is also discussed.

Abstract: A compression system is disclosed having a compressor and a seal package including a non-contact seal and one or more radial shaft seals. In one form the non-contact seal is placed in proximity to a high pressure portion of the compressor. The offset of the non-contact seal from a shaft used to drive the compressor allows some amount of pressure reduced leakage air to pass. A radial shaft seal is coupled to the shaft axial aft of the non-contact seal on the other side of the compressor and oriented to discourage further passage of the leakage air past the radial shaft seal. A vent conveys leakage air to return to the compressor. A backup radial shaft seal can be used axially aft of the first radial shaft seal. A further radial shaft seal is disposed adjacent to the backup seal and oriented in the other direction to seal lubricant for a bearing.

Abstract: A first rotor configured to rotate adjacent to a second rotor is disclosed. The second rotor includes a circular main body with a first axis of rotation and a vane extending radially from the main body. The first rotor includes a first curved surface that corresponds to a curve swept at a constant radius about a second axis of rotation, a second curved surface that corresponds to a curve swept by a leading edge of the vane when the second rotor is simultaneously rotated about the first axis of rotation and the second axis of rotation, a third curved surface that corresponds to a curve swept by a trailing edge of the vane when the second rotor is simultaneously rotated about the first axis of rotation and the second axis of rotation, and a vane-receiving groove disposed between the second curved surface and the third curved surface.

Abstract: Systems and methods are used to control operation of a rotary compressor of a refrigeration system to limit or prevent movement of rotors due to axial thrust loading resulting from rapid changes in speed of the rotors of the compressor. The operational profile of the motor is controlled to maintain acceleration torque and deceleration torque within predefined limits. The acceleration torque and deceleration torque are maintained within the predefined limits by controlling the speed of the motor, or by controlling the torque applied by the motor to the rotors during acceleration or deceleration.

Abstract: A fuel pump includes rotors that rotate, a pump housing that defines a rotor housing chamber that rotatably houses the rotors, and an outer circumferential side housing that includes a cylindrical portion formed in a cylindrical shape that surrounds the pump housing from an outer circumferential side and a narrowing potion having that narrows down with respect to the cylindrical portion. The fuel pump sucks fuel into the rotor housing chamber and then discharges the fuel due to the rotor rotating. A pump cover of the pump housing includes an inlet port that sucks fuel into the rotor housing chamber, and a sliding surface portion on which the rotors slide. An outer circumferential portion of the pump cover includes a joining portion joined to the narrowing portion, and a recessed portion that is recessed adjacent to the joining portion, the recessed portion allowing the outer circumferential portion to elastically deform.

Abstract: An enhanced elastomeric stator assembly and method of making the same is disclosed. The elastomeric stator may be structurally, thermally, and/or chemically enhanced through the incorporation of graphene particles, cross-linkable polymers, coupling agents that extend cross-links, and by the reduction of filler material. The graphene particles can be incorporated in functionalized or non-functionalized form or in a combination thereof, the functionalized graphene increasing the number of cross-links in the overall structure, thereby enhancing the structural robustness of the elastomeric stator. The compound can be formulated to have a relatively low viscosity and other characteristics that allow the material to flow through a mold cavity.

Abstract: A fuel pump includes rotors that rotate, a pump housing that defines a rotor housing chamber that rotatably houses the rotors, and an outer circumferential side housing that includes a cylindrical portion formed in a cylindrical shape that surrounds the pump housing from an outer circumferential side and a narrowing potion having that narrows down with respect to the cylindrical portion. The fuel pump sucks fuel into the rotor housing chamber and then discharges the fuel due to the rotor rotating. A pump cover of the pump housing includes an inlet port that sucks fuel into the rotor housing chamber, and a sliding surface portion on which the rotors slide. An outer circumferential portion of the pump cover includes a joining portion joined to the narrowing portion, and a recessed portion that is recessed adjacent to the joining portion, the recessed portion allowing the outer circumferential portion to elastically deform.

Abstract: Downhole tools for earth-boring applications may include a component of a steel material and including a bore. An inner surface defining the bore may be treated with a surface treatment. The surface treatment may include a nitrided region having nitrogen diffused into the steel material and a ceramic material adjacent to the nitrided region; the ceramic material defining the inner surface. Methods of making downhole tools for earth-boring applications may involve exposing a component of the downhole tool to an elevated temperature to heat the component in a nitrogen-rich environment. Nitrogen may be diffused into a steel material of the component and a nitrided region may be formed at one or more surfaces of the component. A ceramic material may be coated on the nitrided region of the component.

Abstract: A scroll compressor includes a fixed scroll; an orbiting scroll that interfaces the fixed scroll; an Oldham ring that interfaces the orbiting scroll and has a pre-unbalanced force profile; and a motor shaft that interfaces the Oldham ring. The Oldham ring pre-unbalanced force profile is in the form of a sine wave. One of the shaft and the orbiting scroll has an imbalance weight portion; wherein the imbalance weight portion provides a weighted force profile that is 180° opposite of the pre-unbalanced force profile of the Oldham ring and produces in the Oldham ring a post-unbalanced force profile that is substantially a flat line.

Abstract: This disclosure concerns an advanced nutating positive displacement device having a high power to mass ratio and low production cost. This device in one example forms an exemplary pump as will be discussed in detail. The examples disclosed herein are of the rotary positive displacement type, but in a class by themselves. The devices are formed by a nutating rotor having a face comprising lobes and valleys, and a fixed stator also having a face with lobes and valleys. The face of the rotor opposes and cooperates with the face of the stator. The opposing faces define chambers that change volume with rotation of the rotor.

Abstract: A rotor for a Wankel engine including a plurality of ribs extending from a bearing support to each one of the flanks, the plurality of ribs including, for each flank, first and second ribs connected to the flank between the recess and a respective one of the apex portions. The first and second ribs are curved along at least a portion thereof, and/or the first and second ribs are closest to the respective apex portion and connected to the flank adjacent a junction between a portion of the flank defining the recess and a respective portion of the flank connected thereto. A method of reducing pinching of apex seals in a rotor of a Wankel engine is also discussed.

Abstract: A scroll fluid machine includes: a casing; a fixed scroll having an end plate, a spiral wrap part provided on the end plate, and a flange provided outside the wrap part and fitted to the casing; and an orbiting scroll having an end plate and a spiral wrap part provided on the end plate with a plurality of compression chambers formed in a space up to the wrap part of the fixed scroll, which is provided to perform an orbiting motion, wherein the flange is provided with a deformation absorbing part which absorbs deformation due to thermal expansion of the end plate. The scroll fluid machine is improved in reliability while the compression efficiency is maintained by preventing the fixed scroll and the orbiting scroll from coming into contact with each other without increasing a clearance between the wrap parts of both scrolls.

Abstract: A progressing cavity pump system including a rotor and a stator having an inner cavity. The rotor is rotationally disposed inside the inner cavity of the stator such that rotation of the rotor relative to the stator causes material in the inner cavity to be pumped therethrough. The pump system further includes a universal joint directly or indirectly rotationally coupled to the rotor, and a cooling system thermally coupled to the universal joint and configured to cool the universal joint by active heat exchange at a position remote from the universal joint.

Abstract: A scroll pump has a tip seal between an axial end of the scroll blade of one of stationary and orbiting plate scrolls of the pump and the plate of the other of the stationary plate and orbiting plate scrolls. The scroll pump may have a ballast gas supply system and use the operation of the ballast gas supply system to assess the condition of the tip seal. Alternatively, the scroll pump may have two pressure sensors that sense pressure at two locations spaced along a compression mechanism of the pump to assess the condition of the tip seal.

Abstract: A shunt pulsation trap for a cyclic positive displacement (PD) compressor reduces gas pulsation and NVH, and improves off-design efficiency, without using a traditional serial pulsation dampener and a variable geometry. A shunt pulsation trap for a cyclic PD compressor is configured to trap and attenuate gas pulsations before discharge and includes a housing having a flow suction port, a flow discharge port, a compressor cavity, and a pulsation trap chamber adjacent to the PD compressor cavity. The pulsation trap chamber includes at least one pulsation dampening device, at least one injection port (trap inlet) branching off from the PD compressor cavity into the pulsation trap chamber and a feedback region (trap outlet) communicating with the PD compressor outlet. The associated methods of reducing pulsations are included as another aspect of the invention.

Abstract: Downhole motors include a stator, which may be formed from a steel material and comprise a bore. At least one surface of the stator may be treated with a surface treatment. The surface treatment includes a nitrided region comprising nitrogen diffused into the steel material and a ceramic material adjacent to the nitrided region; the ceramic material defining an interior surface of the stator defining the bore. Methods of making downhole motors may include exposing a stator to an elevated temperature to heat the stator in a nitrogen-rich environment. Nitrogen may be diffused into a steel material of the stator and a nitrided region may be formed at one or more surfaces of the stator. The stator may be cooled. The stator may be removed from the nitrogen-rich environment. A ceramic material may be coated on the nitrided region of the stator.

Abstract: The subject matter of this specification can be embodied in, among other things, a method that includes a gear pump includes gears having a gear root diameter and teeth having an addendum and pressure angle. A housing includes a fluid inlet and discharge, bearings configured to position the gear teeth in intermeshing contact across a fluid dam. The fluid dam includes a first face arranged at an angle to a split line, spaced apart from a center line at the split line a first distance towards the inlet, and extending from the first gear root diameter away from the center line to the first gear root diameter, and a second face arranged approximately perpendicular to the split line, spaced apart from the center line at the split line a second distance towards the outlet, and extending between the first gear root diameter and the second gear root diameter.

Abstract: Rotary components are described that include a housing comprising a rotor having a rotor working face and a gate having a gate working face and a pocket; at least one vane, wherein the vane is coupled to the rotor; at least one wiper coupled to the vane; a plurality of endplates coupled to the housing, wherein at least one of the endplates is a float plate; an intake chamber; and an outlet chamber. In addition, methods of aspirating a working medium by utilizing the rotary component having at least one float plate includes pulling the working medium into the intake chamber, depositing the working medium into a working chamber that is located between the intake chamber and the outlet chamber; maintaining the working medium in a stationary position until the vane sweeps around toward the outlet chamber; accumulating the working medium into the outlet channel of the outlet chamber; and centrifugally ejecting the working medium into the outlet chamber and out of the system.

Abstract: A rotary piston pump equipped with a motor having two counter-rotating rotary pistons. The two rotary pistons are housed in an oval pump housing. The two rotary pistons are arranged on a first output shaft and a second output shaft. The first output shaft and the second output shaft are driven and synchronized via at least one elastic element.

Abstract: A scroll compressor that includes a housing and scroll compressor bodies disposed in the housing as well as a method of operation thereof is provided. The housing is separated into different chambers by a separator. One of the scroll bodies is sealed to the separator with a floating seal arrangement including a seal interface between a floating seal of the floating seal arrangement and a hub of a fixed scroll compressor body. A seal retaining ring prevents axial motion of a seal member of the seal interface during start-up operations due to pressure imbalances across the seal member.

Abstract: An eccentric screw pump for delivering fluid and/or granular media. The pump body of the eccentric screw pump includes an inlet region, a pump unit and an outlet region. A drive unit is assigned to the inlet region. The pump unit includes a rotor and a stator, wherein the rotor moves eccentrically in the stator. The inlet region constitutes the suction side and the outlet region constitutes the pressure side of the eccentric screw pump. A bypass connection with at least one safety valve is assigned to the eccentric screw pump in order to take up and return back-flowing medium between the pressure side and the suction side of the eccentric screw pump. The bypass connection and the safety valve may also be integrated into the pump body of the eccentric screw pump.

Abstract: A Roots-type blower may include first and second meshed, lobed rotors disposed in first and second chambers of a housing. Each lobe may have first and second axially facing end surfaces defining a twist angle that may be a function, at least partially, of the number of lobes on each rotor. A blower housing may include a bearing plate that may include one or more internal pressure relief ports. A pressure relief port may be configured to relieve fluid pressure from a trapping area that may form between first and second meshed rotors.

Abstract: A gearbox assembly includes a gearbox housing and a gear located in the housing and rotatable about a central axis. One or more gear shields are fixed in the housing and at least partially surround the gear. The one or more gear shields define a cavity between the gear and the one or more gear shields. The one or more gear shields are configured such that a pumping action is created by the gear rotation to direct gearbox lubricant out of the cavity. A method of scavenging lubricant from a gearbox includes pumping a flow of lubricant circumferentially around a cavity defined between a gear and a gear shield at least partially surrounding the gear via rotation of the gear about a central axis. The flow of lubricant is urged from the cavity into a lubricant outlet. The lubricant is urged through a lubricant channel in an axial direction.

Abstract: Systems and methods are used to control operation of a rotary compressor of a refrigeration system to improve efficiency by varying the volume ratio and the speed of the compressor in response to current operating and load conditions. The volume of the axial and/or radial discharge ports of the compressor can be varied to provide a volume ratio corresponding to operating conditions. In addition, permanent magnet motors and/or control of rotor tip speed can be employed for further efficiency gains.

Abstract: An input shaft assembly is movable along an axis to absorb external impact loads. A biasing member exerts an axial load in a direction counter to potential impact loads. A stop is provided to control the application of biasing loads to control application of such axial load.

Abstract: Multistage pump comprising a plurality of components which include a plurality of pre-assembled pump modules, having at least one twin screw pump module. The multistage pump further has an elongate sleeve for housing the components, and a securing device attachable or engagable with a portion of the elongate sleeve. The securing device is operable to fixedly retain the components within the sleeve. Each of the pre-assembled pump modules has at least one thrust bearing.

Abstract: An apparatus for use in a wellbore may include a stator having a bore and a rotor disposed in the bore. Either or both of the rotor and the stator may include a layer that has an asymmetrical material property profile along at least a portion of a circumference of that layer.

Abstract: A well pump assembly includes a progressive cavity pump having a stator with an elastomeric inner portion. The stator has an axial cavity with internal lobes; a rotor with external lobes positioned within the axial cavity. An effector selectively increases and decreases a stiffness of the stator by changing a cross sectional area of the axial cavity in the stator. The effector may include a reservoir within the stator containing a fluid. A reservoir pump selectively increases and decreases a pressure of the fluid in the reservoir in response to sensing the flow rate from the progressive cavity pump and the torque of the motor. Alternately, the reservoir may contain a magneto-rheological fluid (MR fluid). A coil generates an electromagnetic field within the MR fluid to selectively increase and decrease a viscosity of the MR fluid.

Abstract: A variable flow external rotor hydraulic machine (10, 10?) has an inlet (26, 26?) an outlet (28, 28?), a rotor set having a first rotor (58, 58?) mounted for rotation about a first rotor axis and a second rotor (68, 68?) mounted for rotation about a second rotor axis, the machine being configured as either a pump or a motor, in which at least one of the first and second rotor axes is movable relative to the other to vary a leakage flow between the rotors.

Abstract: A fluid displacement system for a fluid producing subterranean well includes a well extending from a surface to a subterranean fluid bearing formation, the formation being in fluid communication with the well; and a gerotor pump in the well for pumping fluid from the formation to the surface.

Abstract: In one aspect, described is a rotor for a rotary internal combustion engine where a first face seal biased axially outwardly away from the first end face has opposed curled ends abutting a first seal element of a respective one of the adjacent apex seal assemblies, and a second face seal biased axially outwardly away from the second end face has opposed curled ends abutting a second seal element of a respective one of the adjacent apex seal assemblies.

Abstract: A rotary piston pump for the delivery of liquids and for the delivery of liquids containing solids. The rotary piston pump includes a pump housing which is provided with an inlet and an outlet. The pump housing includes a lining. Disposed in the pump housing, or inside the lining, are at least two counter-rotating rotary pistons, which form pump spaces during their rotation. During the rotational movement, the rotary pistons are sealed against one another, against the pump housing and against the lining. Disposed in the pump housing and/or in the lining, in the spatial vicinity of the inlet and/or the outlet, are means with which the pulsation can be reduced or even completely prevented.

Abstract: A rotary positive displacement pump for fluids, in particular for the lubrication oil of a motor vehicle engine (60), has a displacement that can be regulated by means of the rotation of a stator ring (112) having an eccentric cavity (113) in which the rotor (15) of the pump (1) rotates. The stator ring (112) is located in an eccentric cavity (13) of an external ring (12), which is configured as a multistage rotary piston for displacement regulation and is arranged to be directly driven by a fluid under pressure, in particular oil taken from a delivery side (19) of the pump or from a point of the lubrication circuit located downstream the oil filter (62). The invention also concerns a method of regulating the displacement of the pump (1) and a lubrication system for the engine of a motor vehicle in which the pump (1) is used.

Abstract: An oil lubrication system for a multi-stage compressor separates oil from a refrigerant at an intermediate pressure following the first stage of compression and then routes the separated oil at the intermediate pressure to the compressor suction cavity bearings at the intermediate pressure, thus avoiding further compression of oil in subsequent stages of compression. The efficiency of the multi-stage compressor can be increased by not raising the pressure of the oil through the subsequent stages of compression.

Abstract: Methods for controlling the net-displacement of a rotary fluid pressure device are disclosed. One of the net-displacement control methods (47) includes obtaining a desired input parameter (23) and a relative position (21) of a first member (43) and a second member (35) of a fluid displacement mechanism. A determination of a first and second output value is then made for each of a plurality of volume chambers (45) when the volume chambers (45) are supplied with fluid at fluid inlet and fluid outlet conditions, respectively. A total output value is then computed for each of a plurality of control valve configurations (63) and compared to the desired input parameter (23). The control valve configuration (63) with the total output value most similar to the desired input parameter (23) is then selected. A plurality of control valves (15) are then actuated in accordance with the selected control valve configuration (63).