Abstract: A progressive cavity type motor or pump including a stator insert with a reinforcing agent dispersed in a manner to improve properties of the stator insert. The reinforcing agent may be a fiber, nanotube, metal, ceramic, or polymer. A dispersing agent may be used to obtain a homogenous distribution. A magnetic reinforcing agent may be incorporated into a stator insert. The stator insert is subjected to a magnetic field to orient the magnetic reinforcing agent in a particular orientation. The magnetic field may also reposition the magnetic reinforcing agent within the stator insert. The stator insert may be formed by injection molding, transfer, or compression molding among other methods.

Abstract: A crude oil lifting system and a method utilizing a vane pump for conveying a fluid. The crude oil lifting system comprises: an oil pipe and an oil pump connected to the oil pipe. The oil pump is the vane pump. The vane pump is provided with a cylindrical stator. The stator has arranged therein a drive shaft and a rator sleeved onto the drive shaft. The drive shaft is arranged within the stator along the direction parallel to the length of the stator. An intake plate is arranged at the lower end of the stator. A discharge plate is arranged at the upper end of the stator. The intake plate, the discharge plate, and the stator form a cylindrical cavity. The rotor is arranged between the intake plate and the discharge plate. An intake opening for taking in the crude oil is arranged on the intake plate. A discharge opening for discharging the crude oil is arranged on the discharge plate.

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 (12) having an eccentric cavity (13) in which the rotor (15) of the pump (1) rotates. The stator ring (12) 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 a motor vehicle engine in which the pump (1) is used.

Abstract: A compressor may include a shell, first and second scroll members, and a seal assembly. The shell defines a first and second pressure regions. The first scroll member may include a first end plate defining a chamber. The seal assembly may surround the discharge passage and fluidly separate the first and second pressure regions from each other. The seal assembly may include first and second sealing members. The first sealing member may prevent communication between the chamber and the second pressure region when a first fluid pressure within the second pressure region is higher than a second fluid pressure within the chamber. The first sealing member may define a leakage path when the first fluid pressure is lower than the second fluid pressure. The second sealing member may fluidly separate the chamber and the second pressure region when the first fluid pressure is lower than the second fluid pressure.

Abstract: A controller for varying flow rate of a fluid from a fixed displacement pump is provided. The controller includes a pump speed control gear set, a ratio control pump, and a relief valve. The pump speed control gear set includes a sun gear configured to be driven by a prime mover, a planet carrier including one or more planet gears meshed with the sun gear, and a ring gear meshed with the planet gears. The ring gear is configured to connect to an input shaft of the fixed displacement pump. The ratio control pump includes a stationary body, and a rotor coupled to the planet carrier of the pump speed control gear set. The rotor is configured to co-act with the body to pump fluid. The relief valve is connected to the ratio control pump and configured to restrict fluid egress from the ratio control pump.

Abstract: A turbocharger is provided herein. The turbocharger includes a housing and an adjustable core at least partially circumferentially surrounded by the housing, the adjustable core having a turbine rotor coupled to a compressor rotor via a shaft. The turbocharger further includes an adjustment mechanism coupled to the adjustable core configured to adjust an axial position of the housing relative to the adjustable core in response to adjustment commands.

Abstract: A rotary thermal engine for generating mechanical energy. The rotary thermal engine includes an engine block having an enclosed interior space, a first rotor and a second rotor, a first disc coupled to the first and second rotor. A second disc is positioned between the first and second rotor, wherein the second disc pivots relative to the first disc. In addition, wherein the first and second rotors and first and second discs are at least partially enclosed within the interior space of the engine block.

Abstract: A bladed expander for recovery of thermal energy from a working fluid, comprising, a stator provided with an inlet port and an outlet port for the working, fluid, a rotor housed within the stator, and a plurality of blades set between the rotor and the stator so as to delimit between them a plurality of compartments with variable volume that increases between the inlet port and the outlet port. The stator and the rotor are subjected to a heat exchange with a hot fluid so as to carry out a transformation of expansion during which the working fluid receives thermal energy from outside.

Abstract: In order to highly precisely adjust a gap between a bearing and a gear rotor by a simple configuration, a gear pump of the present invention includes: a casing that includes an inlet and an outlet; a pair of gear rotors each of which is formed by integrating a gear portion with a shaft portion and which is disposed so as to engage with each other inside the casing; a bearing portion that supports the shaft portion so that the gear rotor is rotatable, the bearing portion being movable in the thrust direction of the gear rotor; and a gap adjustment unit that moves the bearing portion in the thrust direction so as to adjust a gap between the gear rotor and the bearing portion.

Abstract: Techniques are generally described for a progressive cavity pump and a methods for making and using a progressive cavity pump. In an example, a progressive cavity pump may include a stator, a rotor and/or a bearing. The stator may include a helical shaped interior with a first pitch. The rotor may be inside the stator. The rotor may include a helical shaped exterior with a second pitch. The second pitch may be different from the first pitch. The rotor may be effective to rotate with respect to the stator and effective to move eccentrically within the stator to define at least one cavity inside the stator. At least one bearing may be between the rotor and the stator. The bearing may be sized and shaped so that the rotor is effective to rotate inside the bearing and the bearing is effective to move eccentrically along with the rotor.

Abstract: Heat engine comprising a body (2) provided with an annular cavity (3) therein, two coaxial discoidal sectors (7, 7?) that comprises two diametrically opposite tangential pistons (7a and 7c or 7?b and 7?d) that project, both radially and axially, from their corresponding discoidal sector and can slide through the annular cavity, each pair of consecutive pistons defining a chamber (Cab, Cbc, Ccd, Cda), a means of control of the rotational speed of the two discoidal sectors that makes their respective rotational speeds to vary cyclically and in antiphase between a maximum speed and a minimum speed, so that the speed of each sector is kept at a substantial maximum for most of the duration of a half-cycle, and is kept at a substantial minimum for most of the duration of the other half-cycle, and a means (8) of integration of the speeds of the sectors into a mean speed for the power transmission shaft (9).

Abstract: A rotary vacuum pump, for instance a vane pump, has at least one circumferential groove (6) between facing side surfaces of the rotor (2) and of the rotor guide (3) for receiving a lubricating and sealing fluid. The circumferential groove (6) is a partial annular groove, which has an angular extension of less than 360° and has at least one interruption enabling creating a hydrodynamic fluid bearing in a region opposite a discharge region of the pump (1; 101; 121; 201), over the whole axial extension of the facing surfaces. A method of lubricating a rotary vacuum pump is also provided.

Abstract: In an aspect, the disclosure provides an apparatus for use downhole. In one aspect the apparatus includes a rotor with lobes disposed in stator with lobes, wherein at least one of the contours of the rotor lobe and the contour of the stator lobe is asymmetric.

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 vacuum pump and a method of controlling the operation of the vacuum pump employ an expansion chamber to reduce a pressure differential between an inlet side and an exhaust side of the pump. In particular, the expansion chamber may be used to rid the pump head of the pump of a pocket of relatively high pressure fluid that accumulates behind a poppet valve disposed over an exhaust opening. The pump itself may be used to create a level of vacuum pressure in the expansion chamber. Alternatively, a piston or diaphragm may be used. In either case, the expansion chamber is isolated from the ambient and interior of the pump head once a level of vacuum pressure is produced in the expansion chamber. Then the exhaust outlet is redirected from the ambient to the interior of the expansion chamber.

Abstract: The speed of a cooling fan of a scroll pump is controlled such that fan-generated noise can be kept low. The scroll pump includes a pump head, a pump motor, the fan, a controller and one or more sensors. The pump head includes a plate scroll set in which a tip seal is provided to create a seal between the blade and the opposing plates of the plate scrolls of the set. The speed of the fan is cycled by the controller, and the power draw on the pump motor as a result is checked. These results are used to infer the state of the pump, i.e., to discriminate several different states of the pump from one another, including a state in which a new tip seal is being worn in, and to control the speed of the fan accordingly.

Abstract: An aspect of the present disclosure involves a rotary compressor that is primarily optimized for use without the need for liquid lubricants, such as in the flow path of the fluid being compressed, and is efficient and quiet to use. The compressors described herein are efficient, run quietly, use less power, and last longer than those previously known in the art. The compressors are useful for medical applications and other clean gas applications, for instance, where lubricants could contaminate the fluid being compressed and/or increased noise and/or vibration may be problematic.

Abstract: The subject matter of this specification can be embodied in, among other things, a seal assembly that includes a compressible seal slidably mounted on a central longitudinal shaft of a rotor assembly, the seal having a first lateral surface adapted for contacting a first end surface of a first stator and a first end surface of the second stator and a first end surface of a first longitudinal vane and a first end surface of a second longitudinal vane, a compression member slidably mounted on the shaft, and a locking piston slidably mounted on the shaft, the locking piston including an opening sized to receive the shaft, an end surface adapted to contact the compression member, a circumferential surface sized to be received in the bore of the housing, and a lateral surface adapted to receive actuation fluid.

Abstract: A variable-efficiency screw compressor for use in a closed-loop system configured to perform refrigeration is provided. The variable-efficiency screw compressor includes an inlet port to draw refrigerant into the variable-efficiency screw compressor, one or more rotating screws in fluid communication with the inlet port to compress the refrigerant, forming a compressed refrigerant, a discharge port in fluid communication with the rotating screws to receive the compressed refrigerant and discharge the refrigerant, wherein the discharge port includes an adjustable piston movable within the discharge port from a first position in which volume is higher to a second position in which volume is lower, the adjustable piston arranged and disposed to adjust volume of the discharge port in response to a change in demand.

Abstract: An internal gear pump includes a pump rotor (4) in which a meshing point between an inner rotor (2) having n teeth and an outer rotor (3) having (n+1) teeth is located rearward, in a rotational direction of the rotor, relative to an eccentric axis (CL) along which a center (OI) of the inner rotor and a center (Oo) of the outer rotor are disposed. A tooth-surface curve of the outer rotor (3) near a meshing section thereof is formed by duplicating thereto a tooth-surface shape of the inner rotor (2) near a meshing section thereof.

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).

Abstract: The subject matter of this specification can be embodied in, among other things, a rotary vane actuator. A rotor assembly includes longitudinal vanes disposed radially on a central shaft, with each vane connected at their ends to a circular plates secured to the shaft. Each vane has an outer edge, wherein the shaft, a surface of each plate, and the vanes define interior pockets in the rotor assembly. A stator assembly includes two stator elements each having a first longitudinal edge and a second longitudinal edge.

Abstract: Various rotary pumps are disclosed that are designed to pump viscous fluids or slurries. Often, the seals of such pumps can become over heated. The disclosed pumps include slots disposed in the rotors and/or slots disposed in the openings through which the drive and driven shafts task so that some of the fluid being pumped through the pumping chamber can migrate through the proximal wall of the pump casing to the seal assemblies disposed on the other side of the proximal wall of the pump casing. Thus, the seal assemblies of the pumps are cooled without resorting to the use of a cooling jacket or other cooling mechanism.

Abstract: A method of operating a refrigeration system, that includes providing a plurality of compressors connected in parallel. The plurality of compressors includes a plurality of scroll compressors. The method further includes returning circulated refrigerant to the plurality of compressors, the circulated refrigerant having oil entrained therein. Returning circulated refrigerant to the plurality of compressors includes returning more oil to one of the plurality of compressors than to another of the plurality of compressors. The method also includes supplying oil from one of the plurality of compressors to at least one other of the plurality of compressors. Supplying oil from one of the plurality of compressors includes supplying oil from the one of the plurality of compressors having an opening in its housing. A fitting is assembled into the opening. The fitting protrudes through the housing into an interior portion of the housing.

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 coupling shaft assembly includes a coupling shaft with a first radial shoulder and a second radial shoulder, the first radial shoulder and the second radial shoulder each include at least one slot to provide a lubricant flow path.

Abstract: In an expansion device for use in a working medium circuit, for performing a process sequence corresponding to that of a Clausius Rankine cycle or an Organic Rankine cycle, a working unit comprising two interleaved scroll elements is provided of which one is stationary whereas the other is supported for orbiting relative to the stationary scroll element so as to form separate expansion regions between the scrolls moving, upon orbiting of the movable scroll, from the center of the interleaved scroll elements circularly outwardly with increasing volumes in which a working medium admitted at the center can expand for driving the movable scroll element.

Abstract: Rotary systems are described, which can include at least one of compressors and vacuum pumps. Each rotary system includes a corresponding piston that rotates in an orbital motion around a respective eccentric of a shaft in order to either compress fluid or function as a vacuum pump. Multiple rotary systems can be executed on parallel on a single shaft such that these rotary systems are powered by a single motor. Various components of the rotary systems are coated with an abradable coating, which minimizes friction when these components come in contact with each other. The minimized friction minimizes the wear and tear of these components. Each rotary system can be lubricated by only the fluid being processed (for example, compressed or vacuumed) by that rotary system. The use of the fluid being processed for lubrication and the abradable coatings eliminate a need for another lubricant for lubricating the rotary system.

Abstract: A ball seat assembly includes a tubular having a bore therethrough; an entry port in fluid communication with the bore; a plurality of exit ports in fluid communication with the entry port; a ball seat disposed in the each of the plurality of exit ports, wherein the ball seat is configured to receive a ball to block fluid flow through the respective exit port; and a diverter configured to block fluid flow through the bore and direct fluid flow from the bore to the entry port.

Abstract: There is provided a gas exhaust pump system capable of suppressing the inclusion of a seal gas into a process gas. The gas exhaust pump system has a main and sub pumps. The main pump has a screw rotor, a rotating shaft, a holding unit, a lubricating oil supply path, a seal housing for covering a periphery of a non-held portion by the holding unit with a predetermined gap formed with an outer periphery of the rotating shaft, a seal member interposed between the rotating shaft and the seal housing, a seal gas supply path for supplying a seal gas to the gap, and a seal gas exhaust path for exhausting the seal gas from the gap to the outside of the main pump. The sub pump is configured to reduce a pressure in the seal gas exhaust path.

Abstract: A rotary pump having a variable delivery volume, including: a casing; a delivery chamber formed in the casing; at least one delivery rotor which is rotatable in the delivery chamber; an actuating member which is arranged facing a front face of the delivery rotor or surrounds the delivery rotor, and is moveable in the casing for adjusting the delivery volume; the actuating member chargeable with an actuating force which is dependent on a fluid requirement; a track which is formed in the casing and guides the actuating member on an actuating member sliding surface in a sliding contact; and a sliding material which forms at least one of the track and the actuating member sliding surface.

Abstract: This scroll compressor includes a first fixed scroll member, an orbiting scroll arrangement including a first orbiting scroll member, a first Oldham coupling provided between the first orbiting scroll member and the first fixed scroll member and configured to prevent rotation of the first orbiting scroll member with respect to the first fixed scroll member, a fixed element opposite to the first fixed scroll member with respect to the orbiting scroll arrangement, and a second Oldham coupling provided between the orbiting scroll arrangement and the fixed element and configured to prevent rotation of the orbiting scroll arrangement with respect to the fixed element. The first Oldham coupling is slidable with respect to the first fixed scroll member along a first displacement direction, and the second Oldham coupling is slidable with respect to the fixed element along a second displacement direction transverse to the first displacement direction.

Abstract: This scroll compressor includes first and second fixed scroll members, first and second orbiting scroll members, a first Oldham coupling provided between the first orbiting scroll member and the first fixed scroll member and configured to prevent rotation of the first orbiting scroll member with respect to the first fixed scroll member, and a second Oldham coupling provided between the second orbiting scroll member and the second fixed scroll member and configured to prevent rotation of the second orbiting scroll member with respect to the second fixed scroll member. The first Oldham coupling is slidably mounted with respect to the first fixed scroll member along a first displacement direction, and the second Oldham coupling is slidably mounted with respect to the second fixed scroll member along a second displacement direction parallel with respect to first displacement direction. First and second orbiting scroll members are configured to operate in phase opposition.

Abstract: A horizontal scroll compressor assembly for compressing a working fluid and lubricated with an oil, including a housing having an axis, an interior surface, and a suction sump for collected oil located in the suction plenum, and a compression mechanism including an orbital scroll member having a thrust surface, the thrust surface and the housing interior surface axially superposed. The thrust surface is provided with an oil distribution channel extending at least partially about an axis. Oil from the suction sump received into the distribution channel urged along the distribution channel and delivered to locations between the superposed surfaces during movement of the orbital scroll member about the axis relative to the housing.

Abstract: A method for pressurizing a roll pocket of a displacement assembly of a fluid device includes providing a fluid device having a displacement assembly. The displacement assembly includes a ring defining a central bore and roll pockets disposed about the central bore. Rolls are disposed in the roll pockets. A rotor is disposed in the central bore. The ring, the rolls and the rotor define a plurality of expanding and contracting volume chambers. Fluid is communicated from a first port of the fluid device and a second port of the fluid device to each of the roll pockets so that when the volume chamber immediately before one of the roll pockets and the volume chamber immediately after that roll pocket are both in fluid communication with one of the first and second ports, that roll pocket is in fluid communication with the other of the first and second ports.

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: The present disclosure relates to a rotary vane expander for generating mechanical energy from the expansion of a gaseous medium comprising a housing, an inlet and an outlet for the gaseous medium and to a rotor arranged in the housing. Provision is made in this respect in accordance with a first aspect that the inner contour of the housing has two or more stroke regions which are in communication with the inlet for the gaseous medium so that the gaseous medium expands simultaneously in the two or more stroke regions during the operation of the energy recovery system.

Abstract: Techniques are provided for protecting a rotary positive displacement pump. The techniques include apparatus featuring a signal processor configured to receive signaling containing information about power, torque, speed, viscosity and specific gravity related to the operation of a pump; and determine whether to enter an enhanced pump protection mode for the rotary positive displacement pump based at least partly on a relationship between an actual corrected tune ratio and a tuned ratio set point (Tune Ratio SP).

Abstract: Rotary expansible chamber (REC) devices having one or more working-fluid ports that are adjustable, for example, in size or location. In some embodiments, the variable port mechanisms can be used to control any one or more of a plurality of operating parameters of a REC device independently of one or more others of the operating parameters. In some embodiments, the REC devices can have a plurality of fluid volumes that change in size during rotation of the REC device, and that transition to a zero volume condition during the rotation of the REC device. Systems are also provided that can include one or more REC devices. Methods for controlling various aspects of REC devices, including methods of controlling one or more operating parameters, are also provided.

Abstract: A hydraulic geroller (gerotor) motor, wherein an inner rotor of a revolving group has a plurality of lobes circumferentially spaced along an outer periphery of the inner rotor, and an orbiter of the revolving group includes an orbiting ring and rounded vane portions preferably formed by roller vanes contained in inner recesses of the orbiting ring for common orbiting with the orbiting ring about the fixed longitudinal axis. The orbiter also has fixed for orbiting therewith, fluid windows for directing fluid from the fluid ports to the revolving group. The windows may be formed in an integral portion of the orbiter or in a valve plate mounted for common orbiting with the orbiting orbiter. The valve plate cooperates with a stationary commutator plate or assembly to provide an efficient arrangement for the delivery and exhaust of hydraulic pressure fluid to and from the hydraulic motor.

Abstract: A compressor assembly method may include locating a first scroll member on a bearing housing of a compressor having a second scroll member located axially between the first scroll member and the bearing housing. A first outer radial surface on the bearing housing and a second outer radial surface on the first scroll member with an alignment assembly may be engaged to concentrically align the bearing housing and the first scroll member. The first scroll member may be coupled relative to the bearing housing.

Abstract: A screw compressor includes a housing having an inlet for receiving gas to be compressed by the compressor and an outlet for discharging pressurized compressed gas. A pair of meshing threaded rotors, each rotor having an axis and being rotatably received in the housing, each rotor having a first end near the inlet and a second end near the outlet. A bearing rotatably carrying each rotor about its axis and positioned near the first end and the second end of each rotor. A conduit formed in the housing in selectable fluid communication with at least one bearing and a force generating source from a pressurized fluid source, the force generating source selectably providing a force in a radial direction relative to the axis of the at least one bearing.

Abstract: The invention provides a pump comprising a pump inlet, a pump outlet, at least two threaded rotors and a pressure controlled valve, the pressure controlled valve being capable of controlling re-circulation of fluid from the pump outlet to the pump inlet. The pressure controlled valve can be a control valve. The invention also provides a multiple stage pump assembly comprising at least two pumps arranged in series, wherein at least one of the pumps is the aforementioned pump.

Abstract: Disclosed herein is a single screw gas compressor having a housing including a cylindrical bore, a primary and secondary gate rotors mounted for rotation in the housing, each gate rotor having a plurality of gear teeth, a main rotor rotatably mounted in the bore and having a plurality of grooves and a plurality of threads, wherein each groove meshingly engages at least one of the gear teeth from each gate rotor, a primary economizer port in communication with the cylindrical bore, and a secondary economizer port in communication with the cylindrical bore.

Abstract: A method for manufacturing roller pockets in a stator of a gerotor device generally includes providing a stator having a cavity including a generally cylindrical section defining a central axis and a plurality of roller pockets angularly spaced around a periphery of the cylindrical section. Each roller pocket is configured to receive a respective roller, which acts as an internal tooth of the gerotor device. Each roller pocket defines a generally cylindrical roller pocket bearing surface. The method further includes grinding each roller pocket bearing surface of each roller pocket with a grinding wheel rotating about a rotational axis perpendicular to the central axis. A stator for a gerotor device is also described.

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 hydraulic motor having a cooling system includes a stator, a rotor that rotates and orbits in the stator, a drive link connected to the rotor, and a housing connected with the stator. The housing includes a working fluid inlet port, a working fluid outlet port, a cooling fluid inlet port, and a cooling fluid outlet port. Each port extends through the housing and is configured to connect with a different associated external fluid line. Pressurized fluid enters the working fluid inlet port to rotate and orbit the rotor en route to the working fluid outlet port. The cooling fluid ports are isolated from the working fluid inlet port and the working fluid outlet port within the housing.

Abstract: An apparatus is disclosed that includes a fluid inlet in fluid communication with a valve assembly, the valve assembly structured to selectively permit the flow of a motive fluid from the fluid inlet to a fluid driven motor, wherein the valve assembly further includes a first plunger including a plurality of axially extending fluid channels, wherein the plunger is selectively movable by an actuator in a manner such that as the plunger is displaced farther away from a closed position, the number of axially extending fluid channels placed in fluid communication with the fluid inlet increases, and wherein the axially extending fluid channels permit the flow of the motive fluid from the fluid inlet to the fluid driven motor.

Abstract: A method of operating a refrigeration system uses a plurality of compressors in connected parallel. The method includes returning refrigerant and oil to the compressors, the refrigerant also having oil entrained therein, separating the oil entrained in the refrigerant, and returning more of the oil entrained in the refrigerant to a lead compressor of the plurality of compressors regardless of whether the lead compressor is operating. The method also includes connecting the oil sumps of all of the plurality of compressors such that oil is supplied from the lead compressor to at least one non-lead compressor of the plurality of compressors when the at least one non-lead compressor is operating.

Abstract: A method of operating a refrigeration system having at least three compressors, in which each compressor has an oil sump with oil at an oil level. The method includes separately connecting the oil sumps of the at least three compressors. Each separate connection allows oil flow only between the oil sumps of two of said compressors thereby preventing bypass flow. The method further includes flowing oil between oil sumps of the at least three compressors and along the separate connections to tend to equalize the oil levels among the oil sumps of the at least three compressors.