Abstract: An oil pump emits less noise by properly forming the profiles of teeth of an inner rotor and an outer rotor thereof which engage each other, whereby decreasing sliding resistance and rattle between the tooth surfaces of the rotors. The rotors of the oil pump are formed so the inner rotor having “n” teeth is formed such that the tooth tip profile and tooth space profile thereof are formed using cycloid curves which are formed by rolling a first circumscribed-rolling circle and a first inscribed-rolling circle along a base circle, respectively, and the outer rotor having “n+1” teeth is formed such that the tooth tip profile and tooth space profile thereof are formed using cycloid curves which are formed by rolling a second circumscribed-rolling circle and a second inscribed-rolling circle along a base circle, respectively, and in such a manner that the following equations are satisfied: øBo=øBi; øDo=øDi·(n+1)/n+t·(n+1)/(n+2); and øAo=øAi+t/(n+2).

Abstract: A rotary fluid pressure device has a first oil passage with relatively high pressure fluid therein surrounding the gear set; a plurality of second oil passageways connecting the first oil passageway to the expanding and contracting oil chambers; and fluid non-return valves in each of the second oil passageways to permit the flow of oil therethrough only in a direction to the oil chambers from the first oil passageway to the oil chambers.

Abstract: A pump chamber defines a capacity increased in a first certain angle range and decreased in a second certain angle range. An intake port is open in an increase range where the pump chamber moves from a minimum capacity position to a maximum capacity position. A discharge port is open in a decrease range where the pump chamber moves from the maximum capacity position to the minimum capacity position, the discharge port being biased to the minimum capacity position. A seal land portion seals a communication between the intake port and the discharge port via the pump chamber. A reduced portion is defined between a communication portion and the pump chamber. A bypass path connects the communication portion with the discharge port. A relief valve intervened in the bypass path opens the bypass path with a pressure of the communication portion increased to or over a set pressure.

Abstract: A bottom portion of an intake port is provided with a sloped bottom surface formed of a plane such that sloped bottom surface approaches the side surfaces of external teeth and internal teeth from an upstream side to a downstream side in rotational direction of two rotors. Fluid that flows in the intake port is regulated by the sloped bottom surface and smoothly guided into individual inter-teeth chambers that are expanding. Since the sloped bottom surface on the bottom portion of the intake port is formed of a plane without spiral or twisting, design and manufacturing of a gear pump is extremely easy.

Abstract: A noise-reduced internal gear pump incorporating an inner rotor having an addendum formed by a smooth curve and a dedendum formed by a hypocycloid. The tooth profile of the outer rotor is determined by the following steps. The center Oi of an inner rotor 1 is revolved around the center Oo of the outer rotor so as to form a circle S having a diameter of 2e+t, where “e” is the amount of eccentricity between the inner and outer rotors and “t” is the maximum value of the interrotor clearance between the outer rotor and the inner rotor pressed against it. The inner rotor 1 is rotated on its axis 1/n times while its center Oi makes one revolution in the circular orbit S, where “n” is the number of teeth of the inner rotor. The envelope of the group of the tooth profile-curves of the inner rotor formed by its revolution is used as the tooth profile of the outer rotor.

Abstract: Improved gerotor pumps comprising laterally constrained floating rings, thereby providing an orthogonal degree-of-freedom and allowing gerotor sets positioned therein to establish their own preferred mesh orientation, and additionally wherein the outer rotor of the gerotor set is forcibly positioned against the inner rotor of the gerotor set at the gerotor set's in-mesh position whereat there is little relative motion between the inner and outer rotors, thereby resulting in a substantially friction- and wear-free meshing action of the gerotor set.

Abstract: A pair of interacting gear rims of rotary machine has been invented as a basic structural element for engines, motors and compressors. This is the most simple and most effective design to predetermine the optimal ratio of volumes of expansion and compression processes only at the expense of the form of profile of contact surface of pair gear rims of the rotary machine. This is the ideal basic element for engines, working according to an extended indicator diagram, and for single stage compressor, working with multistage effect. Applications: light and heavy vehicle engines; space power systems; heat pump systems; solar, thermal, nuclear energy systems.

Abstract: A rotary pump such as a trochoid pump is composed of a housing and a rotating structure including an inner rotor and an outer rotor. The rotating structure is rotatably enclosed in a rotor space formed in the housing. The rotor space is divided into a low pressure space communicating with an inlet port and a high pressure space communicating with an outlet port by a pair of peripheral seals disposed in radial grooves formed in an inner periphery of the housing and by a side seal disposed in an axial space between the rotating structure and the housing. The side seal is disposed in the axial space not to cover sidewalls of the radial grooves belonging to the high pressure space, so that the side seal is bent by the pressure in the high pressure space to effectively seal the axial space.

Abstract: An oil pump for a vehicle engine. The oil pump includes an oil pump housing and a gerotor. The oil pump housing includes a cavity that defines an inside diameter. The gerotor is positioned within the cavity, is rotatable relative to the housing, and defines a thickness and an outside diameter. The distance between the inside diameter and the outside diameter is non-uniform across the thickness.

Abstract: A pump chamber defines a capacity increased in a first certain angle range and decreased in a second certain angle range. An intake port is open in an increase range where the pump chamber moves from a minimum capacity position to a maximum capacity position. A discharge port is open in a decrease range where the pump chamber moves from the maximum capacity position to the minimum capacity position, the discharge port being biased to the minimum capacity position. A seal land portion seals a communication between the intake port and the discharge port via the pump chamber. A reduced portion is defined between a communication portion and the pump chamber. A bypass path connects the communication portion with the discharge port. A relief valve intervened in the bypass path opens the bypass path with a pressure of the communication portion increased to or over a set pressure.

Abstract: A gerotor pump for pressurizing gasoline fuel is capable of developing pressures up to 2.0 MPa with good mechanical and volumetric efficiency and satisfying the durability requirements for an automotive fuel pump. The pump has been designed with optimized clearances and by including features that promote the formation of lubricating films of pressurized fuel. Features of the improved pump include the use of a shadow port in the side plate opposite the outlet port to promote balancing of high fuel pressures on the opposite sides of the rotors. Inner and outer rotors have predetermined side clearances with the clearances of the outer rotor being greater than those of the inner rotor in order to promote fuel pressure balance on the sides of the outer rotor. Support of the inner rotor and a drive shaft on a single bushing with bearing sleeves maintains concentricity. Additional features are disclosed.

Abstract: The invention relates to a self-centering gear pump, in particular for conveying and metering free-flowing paste and liquids, but operating within various temperature ranges during the conveying process by means of a drive gear mounted axially an a central smooth motor shaft without a positive-fit connection and an eccentrically located hollow gear that meshes on its interior face and rotates within a cylindrical housing. Said housing is closed on both sides by lateral walls.

Abstract: Two-inner gears are overlapped with each other through a partition wall and are eccentrically arranged at an inner peripheral side of an outer gear, and eccentric directions of both the inner gears are shifted from each other by 180° to the opposite side. By this, loads in an outer diameter direction due to a rise in fuel pressure affect one outer gear from the two inner gears oppositely to each other by 180°, so that an eccentric load is not generated, and sliding resistance of the outer gear to a cylindrical casing becomes small. Further, the number of teeth of the outer gear is made odd, and the number of teeth of the inner gears is made even.

Abstract: In a rotary pump in which axial end surfaces of outer and inner rotors is in pressurized direct contact with an axial end surface of a second side plate to form a mechanical sealing, both of the axial end surfaces of the outer and inner rotors and the axial end surface of the second side plate are provided with radial line grinding stripes. Teeth gap portions formed by the outer and inner rotors in mesh communicate with an outer circumference gap between the circumference of the outer rotor and inner circumference of a center plate and also with a shaft hole of the inner rotor through extremely slight gaps formed by concave and convex of the radial line grinding stripes so that contact surface between the outer and inner rotors and the second side plate is well lubricated to reduce torque loss.

Abstract: A gerotor motor having an inner gerotor positioned within an outer gerotor, a housing radially surrounding the outer gerotor, a cover plate positioned adjacent the outer gerotor and pressure balance grooves extending between the outer gerotor/cover plate interface and a region of radial clearance between the outer gerotor and the housing. Three such balance grooves are disclosed. They include an inlet balance groove, an outlet balance groove and an axial balance groove. These grooves serve to balance axial and radial hydraulic pressure forces acting on the outer gerotor. The resulting net pressure force is substantially independent of both inlet and outlet pressure.

Abstract: The present invention involves a gear assembly of a fuel pump for improved supply of fuel to an automotive engine from a fuel tank. The assembly includes an inner gear and an outer gear matingly cooperating with the inner gear for rotation about an axis. The assembly further includes a pump cover including a cover surface adjacent the inner and outer gears and a pump body including a body surface adjacent the inner and outer gears opposite the pump cover. The cover surface has a primary inlet porting and a secondary outlet porting formed thereon and separated between seal areas. The body surface of the pump body includes a primary outlet porting and a secondary inlet porting separated between seal areas. In use, the inlet portings and the outlet portings of the pump body and the pump cover cooperate together, respectively, such that fuel entering through the inlet portings pass therethrough at a rate at which the gear assembly moves.

Abstract: At a boundary area between a high-pressure portion in which a discharge port of a fuel pump is disposed and a low-pressure portion in which an intake port is disposed, a pressure relief groove extending along the boundary area is formed so as to be communicated with the outside of the pump by pressure relief hole. Alternatively, a slit is formed communicated with the outside. Accordingly, a fuel at a high-pressure area portion can be drained with reliability. Further, by communicating the above pressure relief groove with a positioning pin insertion port, a single hole can serve both as a positioning pin insertion hole and a pressure relief hole.

Abstract: The invention relates to an internal geared wheel pump without a filler piece, comprising a housing, an internal geared wheel (3) which rotates in the housing and an external geared pinion (2) which is rotationally mounted in the housing and which meshes with the geared wheel. The teeth of the pinion define a suction area and a pressure area in the gearing, by complete engagement with the tooth spaces fo the geared wheel and by sealing contact with tooth crows of the geared wheel in an engagement-free geared wheel area which lies approximately diametrically opposite the tooth space engagement. The toothing of the geared wheel and the pinion is an involute or cycloid toothing, the tooth crowns having a rounded peripheral surface (23, 34).

Abstract: A housing for a micro pump or like micro system has at least three structured elements which are layered and which respectively form a support plate, a connecting block and a base element with a further plate-shaped layered structure element located between the connecting block and the support plate and serving with the axially oriented or circumferentially-oriented channel section for conveying fluid between the connecting block and the support plate.

Abstract: An internal gear oil pump rotor assembly which enables the construction of an oil pump that is compact and has high performance. In the oil pump rotor assembly having an inner rotor and an outer rotor, the number of teeth “Zi” of the inner rotor with trochoid tooth profiles is set to be equal to or fewer than “6”, and a ratio Si/So is set so as to satisfy the following inequalities: 0.8≦Si/So≦1.3, where Si is a cross-sectional area of one external tooth which is formed outside a root circle that is formed along the bottoms of the external teeth of the inner rotor, and So is a cross-sectional area of one internal tooth which is formed inside a root circle that is formed along the bottoms of the internal teeth of the outer rotor.

Abstract: An oil pump rotor assembly for an oil pump which enables reduction of noise while preventing pump performance and mechanical efficiency from being degraded. In this oil pump rotor assembly, the tooth tip profile of each of at least one of external teeth of an inner rotor and internal teeth of an outer rotor the inner rotor is formed such that a base cycloid curve is divided at a midpoint thereof to obtain two tooth curve segments, and the two tooth curve segments are separated by a predetermined distance along the circumference of a base circle or in the direction of a tangent of the base cycloid curve drawn at the midpoint thereof and are smoothly connected to each other using a curve or a straight line.

Abstract: In the rotary pump, a high pressure outer circumference chamber, which is formed around an outer circumference of an outer rotor and communicates with a discharge port, presses radially inward first defined parts among the outer circumference of the outer rotor that are positioned radially outside second defined parts adjacent to teeth gap portions whose volume are largest and smallest among teeth gap portions communicating with an intake port. Teeth top clearance between the outer and inner rotors at the second defined part is reduced due to pressure difference between the discharge pressure applied to the first defined parts and the intake pressure applied to the second defined parts.

Abstract: To reduce noise caused by pulsation generated when fluid is expelled, in a trochoidal pump comprising an inner rotor and outer rotor having trochoidal toothed shapes.

Abstract: A kind of gear is provided with shorter teeth, transition teeth and at least one longer tooth. The cross-section of the longer tooth is of a hawk beak shape, and the profile of the longer tooth is smoothly connected in series by a convex section, a tip section, a concave section, and a leading section The two sides of the longer tooth are each provided with a transition tooth which neighbors a shorter tooth on the opposite side of the longer tooth. The pair of engaging gears according to this invention have advantages of reducing the fluid leakage, canceling the inertia of the rotors, and minimizing the vibration and noise. This invention also discloses a fluid machine for conveying, compressing or expanding liquid or gaseous fluids, which includes a casing comprising a housing, an upper end cover and a lower end cover. At least one pair of engaging gears which includes one driving rotor according to this invention and one driven rotor according to this invention is accommodated in the housing.

Abstract: The invention is related to a toothed rotor set for a pump or engine consisting of a rotating outer rotor, which has an approximately star-shaped bore. The bore has a fine inner tooth system and an inner rotor aligned eccentrically inside it. The inner rotor has oil pockets for planetary gears. The planetary gears also have a fine tooth system with the help of which they roll on the fine teeth of the outer rotor. The planetary gears thus build a tooth system that translates into an outer tooth system. The outer tooth system has one tooth less than the inner tooth system of the outer rotor.

Abstract: The present invention involves a gear assembly having a lifting feature for a fuel pump for supplying fuel to an automotive engine from a fuel tank. The gear assembly comprises an inner gear and an outer gear in mating relationship with the inner gear. The inner gear has a substantially disc shape with an outside camming surface and having an inner cover face and an inner body face. The inner gear has a center aperture formed therethrough defining an axis of rotation perpendicular to the inner cover and inner body faces. The inner cover face has a plurality of inner concave grooves radially formed thereon and spaced apart from each other to provide lifting of the inner gear when rotating about the axis. The outer gear has a substantially planar shape. The outer gear includes an annular wall having an inside camming surface slideably engaging about the outside camming surface to matingly cooperate with the inner gear for rotation about the axis.

Abstract: A gerotor pump is provided that includes a pump housing having a pump cover and a pump end plate. The pump cover defines an open end, an axial bore, and a bottom end. The pump end plate engages the open end of the pump cover thereby enclosing the axial bore of the pump cover and creating an inner cylindrical chamber in the pump housing. A wear plate and a gerotor gear set assembly are operatively disposed within the inner cylindrical chamber such that the gerotor gear set assembly is operatively disposed between the wear plate and the pump end plate. A biasing member is disposed between the bottom end of the pump cover and the wear plate, and is adapted to operatively bias the wear plate against the gerotor gear set assembly and the pump end to create an axial zero tolerance condition between the pump elements.

Abstract: A displacement-type ring gear machine (pump or motor) including:

Abstract: A hydraulic transmission pump assembly includes a pump adapted to provide fluid under pressure to predetermined components in a transmission, an electric motor operatively coupled to the pump, and a line pressure control device in electrical communication with the electric motor. The line pressure control device is operable to control the electric motor as to cause it to drive the pump when engine speeds are below a predetermined level such that the pump provides fluid at a predetermined volume and pressure to the transmission during this operating condition. A differential gear assembly is also included that is interposed between an engine and the electric motor, the differential gear assembly acting to drive both the pump and the electric motor when engine speeds are above the predetermined level such that the pump provides fluid at a predetermined volume and pressure to the transmission and the electric motor provides generated electricity.

Abstract: A modular oil pump for use in combination with an internal combustion engine having a dry sump lubrication system. The device features a first gerotor pump having an intake port engageable in communication with at least one engine sump and having an discharge port engageable in sealed communication with a fluid reservoir for the dry sump system. A second gerotor pump, engageable in sealed communication with the fluid reservoir has a discharge port fluidly engageable with the engine lubrication system oil supply conduit. Both the first pump and second pump are assembled from separate housings, and cooperatively engaged inner and outer gears sized for rotation and in line mounting on the engine crankshaft inside a cavity in the housings. The volume pumping capacity of the first pump at a ratio to efficiently drain fluid and gas from the engine sumps and supply the reservoir with a constant supply of lubrication fluid.

Abstract: A toothing of a toothed wheel, consisting of tooth tips (3k) and tooth roots (3f) of teeth which are formed by second or higher order curves, wherein said curves point tangentially toward each other at their ends, and wherein at least the curves forming the tooth tips (3k) or at least the curves forming the tooth roots (3f) are not cycloids.

Abstract: The invention relates to an internal-gear pump for pumping fuel in an internal combustion engine, having an internal-toothed annular gear and an external-toothed pinion that cooperates with the annular gear to generate a pumping action. To increase the pump capacity at starting rpm and to lengthen the service life of the internal-gear pump, the pinion is supported radially movably, eccentrically to the annular gear, on a bearing journal. Moreover, a device is provided in order to compensate for the radial play (R) between the pinion and the annular gear.

Abstract: The invention concerns a tooth set for a hydraulic machine, particularly a steering unit, with a toothed ring, having teeth, which are formed by means of inserts arranged in a housing, and a gear wheel arranged inside the toothed ring. It is endeavoured to simplify the production of such a tooth set. For this purpose, each inset (10) has, at least at its ends, a plate-like shape and the ends are fixed in the housing (11) in corresponding slots (17, 18).

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: 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: A gerotor assembly includes a pressure chamber with an integral eccentric ring for a motor vehicle hydraulic differential for use in hydraulic limited slip differentials for axles, transfer case center differentials and similar devices. The gerotor pump assembly in accordance with the present invention includes a housing having an integral ring which provides a pressure chamber for a piston, an eccentrically positioned recess for a inner rotor and an outer rotor and a location for a pressure limiting system. The gerotor pump assembly is of a non-reversing gerotor pump configuration using known methods to produce a unidirectional fluid flow.

Abstract: An oil pump emits less noise by properly forming the profiles of teeth of an inner rotor and an outer rotor thereof which engage each other, whereby decreasing sliding resistance and rattle between the tooth surfaces of the rotors.

Abstract: An improved hydraulic motor system, suitable for driving an automotive cooling fan or the like. The system is driven by grade gerotor set and an idle gerotor set which are stacked between a center plate and against a rear wall of a cylindrical cavity in a front face of a manifold. A fluid-tight chamber is established by securing an end frame can around the stacked gerotor sets and against the perimeter of the manifold cavity. Tightness of the seal is controlled by positioning a resilient cover plate against the end frame can from a position opposite the manifold, and adjustably clamping the resilient cover against the manifold until the resilient cover has undergone a predetermined amount of elastic deformation.

Abstract: An internal gear pump that does not contain any filler elements comprises a housing (1) and a bearing ring (5), which is accommodated inside a recess (13) of the housing in a manner that permits it to transversally move in relation to its axis but not to rotate. The internal gear pump also comprises an internal-geared ring gear (3), which is mounted inside the bearing ring in a manner that permits it to revolve, and a pinion (2), which is mounted inside the housing in a manner that permits it to rotate and which meshes with said ring gear. The inner peripheral surface of the housing recess (13) coaxially extends in relation to the pinion (2), and the bearing ring, which is eccentrically arranged with regard to the pinion axis (15), can pivot in relation to the housing recess about a parallel pivotal axis (22, 23) that is parallel to the axis thereof. The bearing ring can pivot without the tight contact between the tooth tips of the pinion (2) and ring gear (3) being lost.

Abstract: A rotary type lubrication pump for a vehicle transfer case and a method of producing the lubrication pump, the lubrication pump having an inner gear and an outer gear produced by molding a synthetic polymer, and a pump body and a pump cover produced by stamping steel.

Abstract: A housing for a micropump has a layered structure of at least three elements including a support plate having an axial recess for supporting an internally toothed outer wheel, a connector block provided with an inlet and outlet for supplying and delivering the fluid to be pumped, and a base element for receiving an axially oriented or clamping device for at least one further plate shaped structure element having channel segments for conveying fluid from the connections to the recess of the support plate.

Abstract: The invention relates to a rotary piston engine having at least two rotary pistons, both being formed as gearwheels mounted in a rotatable fashion on mutually perpendicular axes in a housing providing a closed seal for the pistons on both faces as well as around their circumferences, and being at one point in a sliding, mutually sealing engagement of gear teeth with each other.

Abstract: At a boundary area between a high-pressure portion in which a discharge port of a fuel pump is disposed and a low-pressure portion in which an intake port is disposed, a pressure relief groove extending along the boundary area is formed so as to be communicated with the outside of the pump by means of pressure relief hole. Alternatively, a slit is formed communicated with the outside. Accordingly, a fuel at a high-pressure area portion can be drained with reliability. Further, by communicating the above pressure relief groove with a positioning pin insertion port, a single hole can serve both as a positioning pin insertion hole and a pressure relief hole.

Abstract: A trochoid pump composed of an inner gear and an outer gear is used as a fluid pump such as a fuel pump for an automotive vehicle. An inner imbalance load inherently developing in the pumping chambers is suppressed or canceled by an outer imbalance load generated by pressurizing fluid introduced into blade ditches formed on an outer periphery of the outer gear. Positions of a pressure-introducing port and a pressure-releasing port for the blade ditches are selected so that the outer imbalance load is imposed in a direction opposing the inner imbalance load. An amount of the outer imbalance load is made equal to an amount of the inner imbalance load to eliminate undesirable effects of the inner imbalance load.

Abstract: An internal gear pump has a housing, a toothed ring provided with inner teeth, a bearing ring supporting the toothed ring in the housing rotatably about a rotary axis, a toothed gear provided with outer teeth and engaging with the toothed ring, the toothed gear being rotatable in the housing about a rotary axis, the toothed gear or the toothed ring being rotatably driven, the rotary axis of the toothed ring being offset relative to the rotary axis of the toothed gear, and an adjusting device associated with the bearing ring for moving the bearing ring in a radial direction relative to the rotary axis of the toothed ring in the housing for an adjustment and for blocking it in an adjusted position.

Abstract: A gerotor pump is provided that includes a pump housing having a pump cover and a pump end plate. The pump cover defines an open end, an axial bore, and a bottom end. The pump end plate engages the open end of the pump cover thereby enclosing the axial bore of the pump cover and creating an inner cylindrical chamber in the pump housing. A wear plate and a gerotor gear set assembly are operatively disposed within the inner cylindrical chamber such that the gerotor gear set assembly is operatively disposed between the wear plate and the pump end plate. A biasing member is disposed between the bottom end of the pump cover and the wear plate, and is adapted to operatively bias the wear plate against the gerotor gear set assembly and the pump end to create an axial zero tolerance condition between the pump elements.

Abstract: The invention relates to an internal-gear pump for pumping fuel in an internal combustion engine, having an internal-toothed annular gear (11) and an external-toothed pinion (3) that cooperates with the annular gear (11) to generate a pumping action.

Abstract: The invention concerns a micropump for the substantially continuous delivery of a mass flow, the micropump having a sleeve axis and an offset axis of rotation. An internal rotor meshes with an external rotor in a sleeve and at least one outlet-side pressure opening in a first end-face termination part. Both rotors have a dimension smaller than 10 mm. The invention further concerns a micromotor of similar construction in which the diameter of the rotors and the casing are below 10 mm. The pump and motor are extremely miniaturized yet still permit a continuous flow with high feed pressure and high output.

Abstract: The invention is related to a toothed rotor set for a pump or engine consisting of a rotating outer rotor, which has an approximately star-shaped bore. The bore has a fine inner tooth system and an inner rotor aligned eccentrically inside it. The inner rotor has oil pockets for planetary gears. The planetary gears also have a fine tooth system with the help of which they roll on the fine teeth of the outer rotor. The planetary gears thus build a tooth system that translates into an outer tooth system. The outer tooth system has one tooth less than the inner tooth system of the outer rotor.

Abstract: An oil pump apparatus includes an oil pump housing having a first suction port, a second suction port and a discharge port in the circumferential direction thereof. A shape of the end portion in the anti-rotational direction at the second suction port is formed to be along a shape of the end portion on the rotational direction side of one pump chamber which is sealed momentarily between the two suction ports, and a shape of the inner circumferential end portion of the first suction port is formed to be along the rotational trace of the end portion on the anti-rotational direction side of the pump chamber. A plural first pockets are formed on the driven rotor, and a second pocket is formed on the pump housing to communicate between the pump chamber and one of the first pockets when the pump chamber is communicated to the first suction port.