Abstract: A rotary chambered fluid energy-transfer device includes a housing with a central portion having a bore formed therein and an end plate forming an arcuate inlet passage, with a radial height and a circumferential extent. The device also includes an outer rotor rotatable in the central portion bore with a female gear profile formed in a radial portion defining a plurality of roots and an inner rotor with a male gear profile defining a plurality of lobes in operative engagement with the outer rotor. A minimum radial distance between an outer rotor root and a corresponding inner rotor lobe define a duct end face proximate the end plate, wherein the duct end face has a radial height substantially equivalent to the inlet passage radial height at a leading edge of the inlet passage.

Abstract: A variable output assembly including a hydraulic pump disposed on a pump running surface located on a center section, end cap or other hydraulic mounting member. The pump may be a gerotor or other rotatable pump body. A support member is disposed between the pump running surface and the pump and includes a pump support surface having openings to permit fluid communication between the support member and the pump running surface. The support member is movable between neutral and a plurality of positions corresponding to forward and reverse directions of the output. In forward and reverse positions, the support member permits fluid communication between the pump and a first porting system, and in the neutral position the support member permits fluid communication between the pump and a sump through the support surface openings and a second porting system.

Abstract: A distributor assembly (12) includes a distributor housing (102) and a valve selector plate (104). The distributor housing (102) includes an axial bore (106) extending in an axial direction through the distributor housing. The valve selector plate (104) is disposed in the axial bore (106) and is rotatable around a rotational axis (130) parallel to the axial direction between a first orientation and a second orientation. The valve selector plate (104) includes a first substantially planar face (132), a second substantially planar face (134), axial passages (136) radially offset from the rotational axis (130) and extending through the valve selector plate (104) from the first face (132) to the second face (134), and at least one fluid blocking section (138) configured to block axial flow through the distributor assembly. Each fluid blocking section (138) is interposed between and radially aligned with the axial passages (136) with respect to the rotational axis (130).

Abstract: A rotary pump device is provided in which a drive shaft is inserted into a center hole of a cylinder that forms rotor chambers, and into outer rotors and inner rotors of rotary pumps. In the rotary pump device, seal mechanisms that include hollow-shaped resin members and annular rubber members are arranged on an opposite side to the cylinder with respect to the rotary pumps. Metal rings are arranged in hollow portions of the resin members in the seal mechanisms so that the drive shaft is inserted into an inner periphery of the metal rings with a minimum clearance.

Abstract: A gear pump rotor is provided including a combination of an inner rotor and an outer rotor whose numbers of teeth are different by one, and the discharge amount of the pump is increased by an increase of the tooth depth. At least one of an addendum curve and a dedendum curve of an inner rotor is formed by a locus of one point on formation circles that satisfy moving conditions that the formation circles move from moving start points to moving end points while changing the distances from an inner rotor center to the centers of the formation circles. The centers of the formation circles move by a distance in the radial direction of a base circle, and the formation circles rotate by an angle at a constant angular velocity in the same directions of the moving directions of the formation circles.

Abstract: A housing includes a pump chamber, which rotatably receives an inner rotor and an outer rotor that define a pressure chamber therebetween. An inlet port of the housing is communicated with the pressure chamber to supply fluid into the pressure chamber. An outlet port of the housing is communicated with the pressure chamber to discharge the fluid from the pressure chamber. An axial size of an axial clearance, which is formed between an axial end surface of the pump chamber and an axial end surface of the inner rotor, differs from an axial size of an axial clearance, which is formed between the axial end surface of the pump chamber and an axial end surface of the outer rotor.

Abstract: An internal gear pump (1) is proposed for conveying a fluid by a driven pump gear wheel (3) and a ring gear (4), as a gear pair residing in an enclosure, which are, for instance, meshing and hereby generating a sealed area. Hereby, viewed cross-sectionally, a sickle shaped part (5) is provided for sealing the free space, located nearly opposite to the sealed area, whereby a first end piece (12) and a second end piece (13) of the part (5) are assigned to a high pressure area. In accordance with the invention, the two end pieces (12, 13) of the part (5) are constructed differently.

Abstract: A gerotor pump having an outer rotor defining an inner surface of the outer rotor, a thrust plate, a pressure plate, an inlet chamber for fluid intake through the thrust plate to be pressurized, and an outlet chamber for outputting pressurized fluid from the pressure plate. The gerotor pump includes an inner rotor assembly in rotating engagement with the outer rotor. The inner rotor assembly rotating about an axis, the inner rotor assembly comprises a rotor body, wherein the rotor body includes N (an integer greater than one) vane slots defining a first sealing surface, and the rotor body includes N inner openings around the axis, each of the inner opening adjoining a vane slot; and a plurality of vanes defining a second sealing surface, wherein the vane is disposed in the vane slot and in sealing engagement with the rotor body via the first and second sealing surfaces. The inner rotor assembly is in sealing engagement with the outer rotor by the vane engaging on the inner surface of the outer rotor.

Abstract: A balance shaft module equipped with a dual pump including a main oil pump and a sub-oil pump may include a pump rotor rotatably coupled to a housing, a discharge space formed in the housing for discharging oil in the sub-oil pump, a pulse chamber formed in the housing to increase the discharge space, wherein the oil discharged through the discharge space is merged with the oil flowing through the pulse chamber such that discharge pulse pressure is reduced, and an eccentric washer having a discharging opening space formed by cutting off a portion inward from the outside, wherein the discharge opening space of the eccentric washer is connected to the discharge space to fluid-communicate with the discharge space of the pump rotor.

Abstract: A rotary fluid pressure device includes a gerotor gear set having a ring gear and a star gear orbitally moveable about a longitudinal axis relative to the ring gear. The star gear includes an annular spacer ring disposed at one end of the star gear. A brake pin is moveable along the longitudinal axis into and out of interlocking engagement with the annular spacer ring. The brake pin includes an outer surface for engaging an interior surface of the spacer ring. The outer surface of the brake pin and the interior surface of the spacer ring are each angled relative to the longitudinal axis to engage each other in a tapered engagement, to generate an axial force along the longitudinal axis to move the brake pin out of engagement with the star gear in response to a torque being applied to the star gear.

Abstract: A progressive cavity pump includes at least one inner rotor with Z external threads and at least one outer rotor with Z+1 internal threads. The outer rotor has radial bearings at both ends, whereas the inner rotor has a radial bearing only on one side, preferably the inlet side. There is arranged, on the same side as the bearing of the inner rotor, a conventional gear, for example a wheel gear, for maintaining a stable ratio between the rotational speeds of the inner and outer rotors exactly equal to (Z+1)/Z.

Abstract: A pump having an actuator mounted on a rotatable shaft, and a pump mounted on the shaft, which is selectively engageable with the actuator. When the actuator is actuated, the pump will receive rotational force from the shaft, creating a pumping. action.

Abstract: Disclosed is a pump for generating at least two volume flows having a different pressure. Said pump comprises a pump cover, a pump housing, and a wheel set that is eccentrically mounted therein. The pump housing is provided with a suction slot and a pressure slot which are separated from each other by means of a first sealing web and a second sealing sew that is located opposite therefrom. The pressure slot is subdivided into a high pressure chamber and a low pressure chamber with the air of at least one additional sealing web, each pressure chamber being provided with a delivery port.

Abstract: In an inner wall surface of a casing, grooves are formed that correspond to end faces of an outer rotor and an inner rotor, and seal members are disposed within the grooves, the seal members presses against the end faces of the outer rotor and the inner rotor. Inclined portions are provided in sealing portions of resin members of seal members, the sealing portions covering a closed portion. With this configuration, an internal pressure in the closed portion causes the inclined portions to separate from an outer rotor and an inner rotor when a brake fluid pressure within the closed portion increases to the point that the brake fluid is excessively compressed, releasing the brake fluid that is inside the closed portion. It is therefore possible to prevent the brake fluid pressure from increasing excessively within the closed portion.

Abstract: A gerotor pump includes an inner ring and an outer ring. The inner ring is rotateable about an axis, where the inner ring has an outer diameter contact surface. The outer ring has an inner diameter contact surface that defines a central opening. The central opening receives the inner ring, and a portion of the inner diameter contact surface engages a portion of the outer diameter contact surface of the inner ring. A motor including a rotor and a stator that surrounds the rotor is included. The rotor surrounds the outer ring and exerts a driving force on the outer ring such that the outer ring rotates about the inner ring. The inner diameter contact surface of the outer ring and the outer diameter contact surface of the inner ring create a plurality of chambers. Rotation between the inner ring and the outer ring expand and contract the chambers to expel fluid from the gerotor pump.

Abstract: An oil pump rotor includes an inner rotor formed with n (n: a natural number) external teeth, and an outer rotor formed with n+1 internal teeth which are in meshing engagement with each of the external teeth. And the oil pump rotor is used in an oil pump that includes a casing having a suction port for drawing in fluid and a discharge port for discharging fluid and conveys the fluid by drawing in and discharging the fluid due to changes in volumes of cells formed between surfaces of the internal teeth and surfaces of the external teeth during rotations of the rotors under meshing engagement therebetween.

Abstract: A rotary positive displacement pump employs the higher pressure available at a region within the rotor chamber after the outlet port to augment the force of a biasing spring in a control system. A biasing spring with a lower spring force can thus be employed in the control system, resulting in a pump pressure output characteristic which can more closely match the operating speed varying working fluid requirements for devices supplied by the pump.

Abstract: A trochoid pump, comprising a driving shaft, wherein a drive gear comprising of a bevel gear is fixed on one end thereof and an inner rotor is penetrated onto the other end thereof, an outer rotor, the center of which is decentered to the inner rotor, wherein both rotors are covered with the cap and the casing, a first regulatory structure, wherein the driving shaft or a means of control fixed on the driving shaft regulates an one-way movement to the casing, a second regulatory structure, wherein an end face on the other side of the driving shaft is engaged with one end of the cap and regulates the other way movement of the cap, wherein the thrust of the driving shaft is axially regulated by the first regulatory structure and by the second regulatory structure.

Abstract: A hydraulic machine has a gear wheel (2) with outwardly extending teeth and a gear ring (4) with inwardly extending teeth formed by rollers each of which is supported in a pocket (8) in the gear ring, and pressurized spaces are formed between the gear wheel and the inwardly extending teeth. To keep the wear of the machine small, each pocket (8) has at least two different radii (R1, R2, Rn) whereby a radius (R2, Rn) at a smaller displacement from the edge (12) of the pocket is larger than a radius (R1) at a larger displacement from the same edge (12) of the pocket (8).

Abstract: A telescoping gear pump comprises a bolt, a Bellville washer, a wear plate, a seal housing, a seal spring, a spur gear including a wear lobe, a seal ring and a case drain path, a shaft, a ring gear including a wear lobe, seal ring, and a case drain path, seal, a bolt assembly including a Bellville washer and bolt, and a pressure plate. The assembly provides pressure to a fluid to maintain a seal within a telescoping pump/motor during operation. The wear lobe reduces wear while maintaining fluid pressure.

Abstract: An electric pump unit that may be compactified and that may be reduced in weight and cost is provided. An electric pump unit is configured such that a pump chamber having an oil suction port and an oil discharge port is formed on an inner side of a motor stator that is fixedly provided on an inner periphery of a synthetic resin unit housing and only part of an inner peripheral side of which is exposed to an inside of the unit housing, a pump outer rotor is arranged on an inner side of the motor stator in the pump chamber so as to be able to rotate using an inner periphery of the motor stator as a guide, a pump inner rotor that is supported for rotation by the unit housing is arranged on an inner side of the pump outer rotor, and a motor rotor is formed such that a permanent magnet is held by a synthetic resin permanent magnet holding portion that is provided by integral molding on an outer periphery of the pump outer rotor.

Abstract: A multi-drive pump may include a pump housing, an inlet port, an outlet port, a primary pump gear, a secondary pump gear, a first internal mechanical drive mechanism coupled to the primary pump gear and a second internal mechanical drive mechanism and an internal electro-magnetic drive mechanism coupled to the secondary pump gear. The pump housing may define an internal volume fluidly coupled to the inlet port and the outlet port. The primary pump gear and the secondary pump gear may be positioned in the pump housing and coupled to one another. Rotation of the primary pump gear and the secondary pump gear draws fluid into the inlet port and expels fluid from the outlet port. The primary pump gear may be rotated by the first internal mechanical drive mechanism and the secondary pump gear may be rotated by the second internal mechanical drive mechanism and the internal electro-magnetic drive mechanism.

Abstract: A pump comprises a driving rotor and a driven rotor that are positioned in a housing such that, as the driving rotor and the driven rotor rotate, the teeth of the driving rotor and the teeth of the driven rotor mesh to form a positive displacement seal. The teeth of the driving rotor and the driven rotor are configured such that seals between the inlet side and the discharge side of the pump are formed between only the leading surfaces of the teeth of the driving rotor and the trailing surfaces of the teeth of the driven rotor.

Abstract: A variable output assembly including a hydraulic pump disposed on a pump running surface located on a center section, end cap or other hydraulic mounting member. The pump may be a gerotor or other rotatable pump body. A support member is disposed between the pump running surface and the pump and includes a pump support surface having openings to permit fluid communication between the support member and the pump running surface. A motor assembly may be hydraulically connected to the pump running surface by a first porting system, and a sump is hydraulically connected to the pump running surface by a second porting system. The support member is movable between neutral and a plurality of positions corresponding to forward and reverse directions of the output.

Abstract: An oil pump includes a shaft bearing bore, a drive shaft supported by the shaft bearing bore, an annular space between an inner peripheral surface of the shaft bearing bore and an outer peripheral surface of the drive shaft, a communication passage portion formed on the side of a pumping chamber inside the shaft bearing bore, and a communication groove formed opposite to the communication passage portion inside the shaft bearing bore. The communication passage portion is communicated between a discharge port and the annular space, and the communication groove is communicated with the annular space. Oil is stored in the annular space from the discharge port via the communication passage portion, and the oil flows into sliding clearance spaces of first and second journal portions via the annular space and the communication passage portion and the communication groove.

Abstract: According to an aspect of the present invention, an electric pump includes: a housing; an outer rotor; an inner rotor; a base member facing one side surface of the outer rotor and one side surface of the inner rotor; a side plate member, having a facing surface facing the other side surface of the outer rotor and the other side surface of the inner rotor and a non-facing surface opposed to the facing surface; a shaft; a suction port; a discharge port; a negative pressure applied region; a positive pressure applied region; and a relief valve, discharging the fluid from the positive pressure applied region to a non-facing surface side of the side plate member when a pressure applied at the positive pressure applied region exceeds a predetermined value.

Abstract: To maintain the functionality as a compact and inexpensive motor-mounted internal gear pump and also offer further inexpensiveness and reliability. The motor-mounted internal gear pump 80 has a pump part 81 including: an inner rotor 1, an outer rotor 2, a pump casing and an internal shaft 5. The pump casing has flat inner surfaces facing both end faces of the inner rotor 1 and the outer rotor 2. The internal shaft 5 includes a bearing 51 which is inserted into an axial hole of the inner rotor 1 and a fitting part 53 extending from both its ends in both axial directions. The pump casing includes two pump casing members 3, 4 as separate members with flat inner surfaces 25, 26 respectively.

Abstract: The present disclosure relates to a vehicle transmission with fluid pump having a recirculation circuit. The recirculation circuit is configured to direct fluid from an outlet of the pump to an inlet during pump cycling. A method of manufacturing a fluid pump for use in a vehicle transmission is also disclosed.

Abstract: The present invention enables the manufacture of a trochoid pump having a crescent which has been considered theoretically impossible by employing an inner rotor of a trochoid pump. An inner rotor having a predetermined number N of teeth that is equal to or larger than 4 is formed in advance.

Abstract: The present invention enables the manufacture of a trochoid pump having a crescent which has been considered theoretically impossible, by employing an inner rotor of a trochoid pump. An inner rotor having a predetermined number N of teeth that is equal to or larger than 4 is formed in advance.

Abstract: A bearing is located with movement of an outer race in the longitudinal direction of a drive shaft being restricted, and the drive shaft is fixed to an inner race with the press fit, so that, it is possible to prevent the drive shaft from escaping. In addition, the inner race is longer than the outer race. Therefore, it is possible to obtain sufficient strength of the press fit of the drive shaft in the inner race while suppressing the size of the outer race (in other words, suppressing the size of the pump device). As a consequence, the size of the pump device can be suppressed while increasing reliability of the function for preventing the drive shaft from escaping.

Abstract: A gear pump is provided and includes an inlet port which terminates, in the pumping direction of the rotor set, in a radially inwardly extending ramp portion. The ramp portion operates to direct working fluid from an inlet radially inwardly into a pumping chamber of the rotor set which is passing over the ramp portion. By closing the pumping chamber at a radially inwardly point, the filling efficiency of the pumping chamber is improved, reducing cavitation and/or operating noise of the pump.

Abstract: A lube pump is provided for supplying lubricant to various components of a power transmission unit of the type used in motor vehicles. The lube pump includes a pump assembly and a coupling mechanism for releaseably coupling the pump assembly to a driven shaft. The coupling is operable to release the pump assembly when the rotary speed of the shaft exceeds a threshold value.

Abstract: A gear pump has a pump housing formed with a gear receiving recess, a pump cover coupled with the pump housing to cover the gear receiving recess, a hydraulic passage that uses the gear receiving recess as a passage part thereof, and annular inner and outer gears operatively installed in the gear receiving recess. The inner and outer gears are of a bevel type and meshed with each other in such a manner as to bias the inner gear in a direction to reduce the thickness of the passage part when the inner gear is rotated while turning the outer gear therearound.

Abstract: An internal gear pump has a first port opening into pumping chambers and provided at one side with respect to a first axis interconnecting a confinement portion of the pumping chambers having a maximum volumetric capacity and a deeply-meshed-engagement portion of the pumping chambers having a minimum volumetric capacity, a second port opening into the pumping chambers and provided at the opposite side with respect to the first axis, a first pressure introduction passage intercommunicating the first port and a first-port side area of a clearance space defined on an outer periphery of an outer rotor, and a second pressure introduction passage intercommunicating the second port and a second-port side area of the clearance space. The clearance space of a direction of a second axis perpendicular to the first axis is dimensioned to be greater than the clearance space of a direction of the first axis.

Abstract: The invention relates to a hydrostatic, slow-speed rotary cylinder engine comprising a power part (1) which acts as an output, said power part comprising a central, stationary stator (4), a rotary cylinder (6) which is used as a rotor and a shaft (2) which is mounted in a central manner on both sides of the roller bearings (10, 11) which are arranged directly adjacent to the power part (1). Supply and discharge of tooth chambers comprising the working fluid is controlled by means of a disk-shaped rotational valve (3) which is mounted in a continuously centered manner in relation to the shaft (2) and the stator (4). A toothed wheel drive is arranged between a shaft external toothing (14) and an internal toothing (17) of a stationary internal toothed ring (28; 92) as a synchronous drive for the rotational valve (3). The toothed wheel drive is subsequently arranged in the leakage oil region of the engine and is formed by a planetary gear (80) or, preferably, by an eccentric gear (30).

Abstract: In an internal gear pump of the present invention, a first angle that is formed by a first straight line that connects a rotation axis of an inner rotor to a tooth tip portion of an external tooth in the rotational direction of the inner rotor and an outer rotor, and a second straight line that connects the rotation axis to a meshing portion of the external tooth is not less than 1.4 times the size and not more than 1.8 times the size of a second angle that is formed by a third straight line that connects the rotation axis to a tooth bottom of the external tooth, and the second straight line.

Abstract: A pump assembly includes a pump housing, a stator ring supported within the pump housing, and a pump ring also rotatably supported within the pump housing. The pump ring interfaces with the stator ring to define a plurality of variable volume pressure chambers. A cover plate covers the stator ring and pumping ring within the pump housing. The cover plate is axially displaceable relative to the pump housing and defines a wall of each of the pressure chambers. Pressure within the pressure chambers induces linear movement of the cover plate away from the stator ring and the pump ring.

Abstract: A hydraulic machine has a gear wheel (2) with outwardly extending teeth and a gear ring (4) with inwardly extending teeth formed by rollers each of which is supported in a pocket (8) in the gear ring, and pressurized spaces are formed between the gear wheel and the inwardly extending teeth. To keep the wear of the machine small each pocket (8) has at least two different radii (R1, R2, Rn) whereby a radius (R2, Rn) at a smaller displacement from the edge (12) of the pocket is larger than a radius (R1) at a larger displacement from the same edge (12) of the pocket (8).

Abstract: According to one embodiment of the invention, a gerotor apparatus includes an outer gerotor having an outer gerotor chamber, an inner gerotor, at least a portion of which is disposed within the outer gerotor chamber, and a synchronizing apparatus operable to control the rotation of the inner gerotor relative to the outer gerotor. The inner gerotor includes one or more entrance passages operable to communicate a lubricant into the outer gerotor chamber.

Abstract: To provide a rotor apparatus of a pump in which pressure release in the air gap between an oil seal and an inner rotor is conducted smoothly and good durability and sealing ability of the oil seal is maintained and which has a very simple structure and allows the increase in size to be avoided. The rotor apparatus of a pump includes a drive shaft in which a plurality of arcuate circumferential surface sections centering on an axial center and a plurality of flat surface sections are disposed alternately, and an inner rotor having a mounting hole into which the drive shaft is inserted. In the mounting hole, arcuate inner peripheral sections corresponding and equal in number to the arcuate circumferential surface sections and flat surface inner peripheral sections corresponding and equal in number to the flat surface sections are formed alternately.

Abstract: An oil pump includes pump chambers each having a volume varied by engine drive and for pressurizing oil inhaled through an inlet port and discharge it through an outlet port, and a branch passage connected between upstream and downstream sides of the outlet port at branch and confluent points, wherein the branch passage in the vicinity of the confluent point is shifted in pulse-pressure phase with respect to the outlet port.

Abstract: An oil pump includes a pump cover covering a recess in a side face of a pump body to form a gear compartment therebetween. A drive gear and a rotatably driven gear are meshed and mounted in the gear compartment. Working spaces R are formed by the engagement of the meshed gear teeth. Discharge ports are formed in both the pump body and the pump cover in communication with the gear compartment. A notch is formed in the pump body at the bottom of the gear compartment and extends from the front end of the discharge port in the pump body to the rear end of a discharge area for the working spaces. Another notch is formed in the inner side face of the pump cover, and extends from the front end of the discharge port in the cover to the rear end of the discharge area.

Abstract: A pump case of an electric pump is constructed by coupling a first pressed member formed with a cylindrical part for holding a first rolling ball bearing rotatably supporting a rotary shaft, and a second pressed member formed with a recess for receiving an inner rotor provided at a tip end of the rotary shaft to each other. Because the first pressed member and the second pressed member are formed by deep-drawing work, it is possible to achieve simplification of the structure and reduction of the cost, as compared with the pump case which has been produced from an aluminum die casting or the like, as in the related art.

Abstract: According to one embodiment of the invention, an engine system comprises a housing, an outer gerotor, an inner gerotor, a tip inlet port, a face inlet port, and a tip outlet port. The housing has a first sidewall, a second sidewall, a first endwall, and a second endwall. The outer gerotor is at least partially disposed in the housing and at least partially defines an outer gerotor chamber. The inner gerotor is at least partially disposed within the outer gerotor chamber. The tip inlet port is formed in the first sidewall and allows fluid to enter the outer gerotor chamber. The face inlet port is formed in the first endwall and allows fluid to enter the outer gerotor chamber. The tip outlet port is formed in the second sidewall and allows fluid to exit the outer gerotor chamber.

Abstract: A gerotor pump includes an outer rotor having a first toothed surface and lobes that extend inwards. An inner rotor is eccentrically aligned relative to the outer rotor and includes a second toothed surface and lobes that extend outwards. Planetary gears are located between the outer rotor and the inner rotor. Each planetary gear has a third toothed surface that intermeshes with the first toothed surface and the second toothed surface.

Abstract: The invention relates to an internal gear pump including: a rotor member including an outer rotor provided with inner teeth to which a torque supplied from a driving device is transmittable; an inner rotor provided with outer teeth engageable with the inner teeth of the outer rotor so to be driven by a rotation of the outer rotor, wherein a rotation axis of the inner rotor is eccentric with respect to a center of the rotor member; a pair of housings provided on opposite sides of the rotor member and the inner rotor to support the rotor member and the inner rotor; and at least one rolling bearing provided between at least one of the housings and the rotor member.

Abstract: In pump rotors and used in an internal gear pump, which includes an inner pump rotor having outer gear teeth; an outer pump rotor having inner gear teeth that mesh with the outer gear teeth ; and a casing having a pumping-in port through which a fluid is pumped in, and a pumping-out port through which the fluid is pumped out, and pumps in and pumps out the fluid by changing the cell volume formed between gear tooth surfaces of the rotors and so as to carry the fluid when the rotors and mesh with each other and rotate, the rotors are formed from a sintered material of Fe—Cu—C and have a density of not less than 6.6 g/cm3 and not more than 7.1 g/cm3, and the outer circumferential surface of the outer pump rotor and the end surfaces perpendicular to rotation axes of the rotors and are non-grinded surface and have a ten point height of irregularities Rz of not less than 4 ?m and not more than 10 ?m.

Abstract: To provide an internal gear pump capable of preventing small vibrations due to pressure differences at the outlet port side of a crescent disposed between the outer rotor and the inner rotor, so that fatigue failure does not occur in the crescent over a long time period, whereby the durability can be increased. The internal gear pump includes a rotor unit, in which an inner rotor is disposed within an outer rotor on the inner peripheral side and a crescent is disposed in the gap between the inner rotor and the outer rotor, the rotor unit being housed in a pump casing. Outer cells are formed by the crescent and the outer rotor. Inner cells are formed by the crescent and the inner rotor. Linking of the outer cells and the outlet port, and linking of the inner cells 6 and the outlet port, start substantially simultaneously.

Abstract: Besides the conventional pump timing in rotary hydraulic devices, a series of constant and variable restrictions have been applied to condition the pressurized flow used to internally precompress the volume or volumes to be displaced. This multiple staged orifices feature reduces the outgassing associated with the pressurized flow passing through a single restriction, such as a metering groove. The pressurization of the outgassed fluid will cause noise and erosive wear of the pump internal containment surfaces.