Abstract: A gear pump for moving elastomeric material includes a housing, a first beveled gear, a second beveled gear, and a drive mechanism. The housing has first and second side plates, an internal gear chamber, a material inlet communicating with the chamber, and a material outlet communicating with the chamber. The first beveled gear is disposed within the chamber. The first beveled gear is rotatably mounted about a first axis of rotation to the housing. The second beveled gear is disposed within the chamber. The second beveled gear is rotatably mounted about a second axis of rotation to the housing. The second beveled gear engages the first beveled gear such that rotation of the first beveled gear in a first direction affects rotation of the second beveled gear in a second opposite direction. The first axis of rotation is parallel to the second axis of rotation. The drive mechanism directly drives rotation of the first beveled gear and simultaneously and indirectly drives rotation of the second beveled gear.

Abstract: A rotor assembly is provided for a compressor assembly having a housing defining an inlet port, outlet port, and a rotor cavity in communication with the inlet port and outlet port. The rotor assembly includes a rotor body having a plurality of lobes formed thereon and rotatably mountable within the rotor cavity of the housing. The rotor body has a first end, substantially adjacent to the inlet port, and a second end, substantially adjacent to the outlet port, when mounted within the housing. Each of the plurality of lobes has an outer radius that is greater at the first end than at the second end.

Abstract: A gear pump has two engaging gearwheels disposed between a suction chamber and a pressure chamber, with the gearwheels borne on bearing axles that are connected to the gearwheels. The gearwheels and the bearing axles are each manufactured of the same material as a homogenous workpiece. This provides for both simple construction of the gear pump and good pump operating properties. Preferably the gearwheels and bearing axles are made of a synthetic material.

Abstract: A gear pump for operating with reduced likelihood of cavitation occurrences in the fluid being pumped thereby, the pump having a pair of gears each supported on a corresponding one of a pair of gear with teeth provided in each gear that mesh with at least one tooth of the other when such teeth have been rotated into a meshing region in the gear plane, and with one of the gear shafts being rotatably connectable to a motor. Bearing structures rotatably support corresponding ones of each of the pair of gear shafts with the bearing structures having bearing surfaces adjacent those gear sides. A pressurized fluid passageway is provided in at least one of the bearing structures across from the meshing region and extending between surface openings at the bearing surface of that bearing structure that are positioned on opposite sides of an alignment axis in that bearing surface, the surface openings being separated from one another by at least the width of a tooth provided in the pair of gears.

Abstract: A rotary lobe pump comprises a pump body having a driving means and an outer casing, and an insert that can be replaced. The replaceable insert comprises a housing formed of a plastic material and having an inlet port, an outlet port and internal surfaces defining a pumping chamber. The replaceable insert also includes a pair of lobed rotors arranged for rotation within the pumping chamber. The housing includes apertures through which the lobed rotors may be rotationally driven, so that the lobed rotors mesh together for pumping a fluid from the inlet port to the outlet port.

Abstract: The invention is to reduce flutter and wear and improve the serviceability and wear life of tip seals for roots blower and screw type compressor superchargers where used for improved supercharger output and efficiency. As the seals travel over the outlet opening, the seals move outward in their slots, leading to flutter which may shorten their useful lives. As each seal reaches the center of the outlet opening, it is forced back into its groove by engaging a valley of the mating rotor with the likelihood of increased wear. The invention provides longitudinally spaced support bars extending laterally across the opening in the directions of rotation of the rotors. The support bars have inner surfaces machined with the associated rotor cavity bores and thus smoothly support the seals as they ride over the support surfaces. The support reduces the flexing of the seals and the resultant wear.

Abstract: A plurality of convex portions that protrude radially outward from a plurality of positions separated in the circumferential direction are provided on the outer peripheral surface of a driven gear. Each convex portion has, in the circumferential direction of the driven gear, a rising surface that rises from a minimum diameter position to a maximum diameter position in the direction opposite the rotational direction of the driven gear, and a falling surface that falls from that maximum diameter position to a minimum diameter position that is adjacent to and in back of that maximum diameter position with respect to the rotational direction of the driven gear. The circumferential length of the falling surface is greater than the circumferential length of the rising surface.

Abstract: A supercharger has an inner wall defining an inner cavity for receiving lobed rotors for rotation therein, a low-pressure inlet and a high-pressure outlet. A sound attenuator is associated with the housing and located adjacent to the high-pressure outlet. The sound attenuator has a tuner chamber and circumferentially spaced tuner ports fluidly connecting the tuner chamber with the internal cavity of the housing to define a Helmholtz resonator. A land is defined between the circumferentially spaced tuner ports such that the high-pressure outlet and low-pressure inner chambers defined between the rotor lobes and the inner wall are fluidly connected when the rotor lobes are in alignment with the land to reduce the pressure differential between the high-pressure outlet and the low-pressure inner chambers.

Abstract: There is disclosed a Roots type pump in which two rotors are rotated synchronously in a pump chamber to compress fluid therein, wherein respective stop positions of the rotors in the pump chamber at a time of stopping the pump are determined independently of each other.

Abstract: In a gear pump equipped with a pump assembly formed from a driving gear supported by a driving shaft, a driven gear supported by a driven shaft, a pair of side plates disposed at both sides in an axial direction of driving and driven shafts, and a seal block that seals tips of the gears and forms a first fluid chamber by installation onto the side plates, and a casing that houses the pump assembly and forms a second fluid chamber therein, ribs are provided for at least one member of the side plates or the seal block, and fluid tightness between the first and second fluid chambers is secured by exerting pressure between the side plates and seal block and additionally plastically deforming the ribs. By this, it is possible to provide the gear pump which is capable of achieving improvement of the seal integrity while reducing the parts count.

Abstract: A fuel pump includes a housing having a cavity. The cavity has a rear surface, and a drive gear and driven gear are disposed in the cavity and in mesh with one another for pressurizing fluid. A floating wear plate and a fixed wear plate are disposed in the cavity and are in contact with the drive gear and the driven gear. A flow orifice is formed as part of the floating wear plate, and a portion of the pressurized fluid flows through the flow orifice to an area between the rear surface of the cavity and the floating wear plate, causing the floating wear plate to apply force to the drive gear and driven gear, and causing the drive gear and driven gear to apply force to the fixed wear plate, thereby compensating for any wear of the drive gear, driven gear, and wear plates.

Abstract: An intake assembly, such as a supercharger assembly, is provided for an internal combustion engine. The intake assembly includes a housing having a wall defining an inlet passage through which intake air enters the intake assembly. A plurality of stiffening ribs is provided on the wall opposite the inlet passage and at least partially defines at least one cavity. A plate is mounted to the wall of the housing and further defines the at least one cavity. The wall defines at least one orifice configured to provide communication between the inlet passage and the at least one cavity. The at least one cavity and the at least one orifice cooperate to form at least one resonator. A method of forming the intake assembly having integral resonators is also provided.

Abstract: A fluid pumping device is disclosed. The fluid pumping device includes a housing having a front end and a rear end, a fluid discharge opening in the front end of the housing, a pump assembly, a crank assembly rotatably connected to the pump assembly wherein the crank assembly operates the pump assembly, and a fluid storage reservoir connected to the gear housing from which fluid is drawn into the gear housing to be pumped through the fluid discharge opening.

Abstract: A gear pump (1) that discharges a fluid by rotating while a pair of gears (11, 12) are intermeshed includes a body (2) into which the respective gears (11, 12) are incorporated, a housing (3, 4) that contacts the body (2), a number of particles (30) that are interposed between an end surface (25, 26) of the body (2) and an end surface (28, 29) of the housing (3, 4), which contact each other, to prevent positional deviation between the body (2) and the housing (3, 4), and a fastening member (17 to 20) that fastens the housing (3, 4) to the body (2).

Abstract: In the case of speed-regulated high-power drives and with simultaneously high demands on accuracy or dynamics, the object of the invention is to reduce a very high level of complexity of the power electronics (high clock frequency), the motor (high precision) and mechanical transmission (low-play transmission elements). For this purpose, the invention proposes a drive device for rotational and/or t translational movements. The drive has a plurality of drives for the joint, mechanically coupled driving of a working machine or for moving a mass. It also has a control device. At least one drive is intended to provide the power (as a power drive). At least one further drive is provided and mechanically coupled as a servo-drive for controlling or regulating the accuracy and/or dynamics of the overall drive. The control device controls and regulates the at least two mechanically coupled drives.

Abstract: A pair of Northey rotors for a vacuum pump, in which each rotor comprises two opposing, substantially parallel faces, and a peripheral surface located between the opposing faces. In order to reduce damage caused by pumping a gas stream containing liquid or solid particulates, a plurality of grooves is located on the peripheral surface for accommodating the particulates.

Abstract: A gear pump comprises a drive gear being mounted for rotation about a first axis and having a plurality of gear teeth at a radially outer location. A driven gear is mounted for rotation about a second axis, and having a plurality of teeth at a radially outer location. The drive gear teeth engage the driven gear teeth at a contact face to cause the driven gear to rotate. Slots are formed in the contact face of one of the drive and driven gear teeth.

Abstract: A gear pump comprises a first gear to be connected to a source of drive, and having a first plurality of gear teeth. A second gear has a second plurality of teeth engaged with the first gear teeth. The first gear teeth contact the second gear's teeth on a contact face, causing the second gear to rotate. The first plurality of teeth is greater than the second plurality of teeth.

Abstract: An internal gear pump (1) for conveying a fluid by a driven pump gear wheel (3) and a ring gear (4), as a gear pair located within an enclosure, which at least partially mesh with one another. A sickle shaped part (5) is provided for sealing the free space located substantially opposite to the sealed area. A first end piece (12) and a second end piece (13) of the sickle shaped part (5) are assigned to pressure areas of the internal gear pump (1). In accordance with the invention, the two end pieces (12, 13) of the part (5) are constructed differently so as to avoid, or reduce as much as possible, both cavitations and noise.

Abstract: An improved geared hydraulic apparatus, comprising a pair of meshing gearwheels, mounted to be reciprocally rotatable in a casing between an inlet side and an outlet side for a fluid having, in use, a substantially transverse flow with respect to the axes of rotation of the gearwheels. The meshing gearwheels create, during their reciprocal rotation, progressive meshing configurations between respective co-operating teeth. In at least one of said progressive meshing configurations is defined, in at least one cross-section of the gearwheels, at least one closed area between respective fluid entrapment teeth. The closed area decreases until it is substantially cancelled out at and around at least one other, separate progressive meshing configuration between the aforesaid respective co-operating teeth.

Abstract: A Roots vacuum pump stator is arranged to house a pair of intermeshing rotors, said stator being characterised in that it comprises a director or deflector arranged to direct solid material entrained in a gas pumped through the pump towards the outlet. In other words, the stator according to the present invention has a means for directing or deflecting powder or solid material entrained in a gas being pumped directly towards an outlet of the pump or out of the pump. The directing means can comprise a channel disposed between the arcuate surface and the outlet, said channel comprising a portion that engages the arcuate surface prior to the bottom-dead-centre position and which extends away from the rotor's axis of rotation towards the pump outlet.

Abstract: A gear pump comprises a casing having an inlet, an interior, and an outlet. An inlet gear is positioned at the inlet and pressurizes fluid received at the inlet. A drive gear is positioned at the outlet of the casing, the drive gear receiving fluid pressurized by the inlet gear to output pressurized fluid at the outlet. A speed-reduction gear is meshed to the drive gear and connected to the at least one inlet gear, the speed-reduction gear having a greater number of teeth than the drive gear to reduce a rotational speed from the drive gear to the inlet gear, such that the inlet gear has a lower speed that the drive gear. An input shaft is coupled to the drive gear and receives a rotational input to actuate the drive gear.

Abstract: Rotary seals in a telescoping gear pump/motor a feature that allows the seal to shift radially relative to other components while maintaining the seal integrity and without compromising the function of the bearings or the bushings needed to bear the load.

Abstract: A motor and a method of operating the motor are described. The motor may have a female rotor shaft having mounted thereon a female compression rotor, a female power rotor, and a spur gear. The motor may also have a male rotor shaft having mounted thereon a male compression rotor, a male power rotor and a power rotor gear. A housing containing the foregoing may have a front housing plate, a compression rotor case, an isolator plate, a power rotor case, a rear housing plate, and a gear cover adjacent the rear housing plate. The various female and male rotors are engaged with one another within the housing.

Abstract: A bi-directional converter between pressure and rotational force includes engaging rotation members that continue to rotate while being adjacent to each other without collision; the rotation members and an outer wall form an enclosed space; rotation shafts of the rotation members are mutually engaged by gear wheels; the rotation members are synchronized and rotate in opposite directions; the rotation members are rotated by a volume change of the enclosed space by application of pressure from outside; and the volume of the enclosed space is changed by rotational force to generate a pressure difference. The bi-directional converter includes an open-close mechanism opening and closing supply exhaust paths inside the rotation member and disposed to the rotation shaft or the outer wall according to a rotation angle.

Abstract: The invention relates to a gear pump in which the amplitudes of the pressure impulses in a pressure chamber can be significantly reduced by a suitable embodiment of a first groove and/or a second groove. The circumferential walls of a pump chamber containing the pressure chamber, in an angular range extending toward the pressure chamber, each have a respective groove communicating with the pressure chamber, by which grooves a radial spacing between the outer circumference of two gear wheels disposed in the pump chamber and the circumferential walls is increased.

Abstract: An oil cooler oil pump assembly for an internal combustion engine has an oil cooler and an oil pump configured to draw in oil from the oil pan and convey it to the oil cooler. The oil cooler is arranged on the exterior side of the oil pan. The oil pump is integrated into the oil pan, wherein oil pump and oil cooler are immediately or closely coupled to one another by a connecting pipe.

Abstract: An external toothed wheel pump, comprising a delivery chamber comprising an inlet and an outlet for a fluid; a first feed wheel and a second feed wheel which can be rotationally driven for delivering the fluid and are in a toothed engagement with each other which separates the outlet from the inlet; and sealing surfaces which axially face the feed wheels and form axial sealing gaps with the feed wheels, wherein at least one of the sealing surfaces comprises a relieving pocket on a high-pressure side of the delivery chamber only and except for the relieving pocket, extends circumferentially up to at least the root circle and tip circle of the axially facing feed wheel.

Abstract: A system for enabling fluid flow is provided which includes a plurality of frusto-conical elements, central and outer spherical shells which enclose the frusto-conical elements, constraining means which constrain the elements between the central and outer spherical shells, and input and output means for allowing fluid flow into and out of the system. The geometry of the frusto-conical elements and their alignment within the system allows the formation of chambers between adjacent elements and their central and outer shells. The elements are free to roll about one another within the system in a synchronized manner. This synchronized rolling is results in a cyclical change in volume of those chambers.

Abstract: The invention provides a rotary motor comprising a first rotor member rotatable about a first axis; and a transmission system for rotating the first rotor member and the second rotor member; characterised in that the first rotor member and the second rotor member are adapted to rotate at variable angular velocities.

Abstract: A method of manufacturing a rotor to be used in a dual-rotor lobe pump system for pumping a material at a periodic rate is provided. The method includes selecting a desired periodic flow rate for the material, selecting a number of lobes for the rotor, and selecting either a thickness of the rotor or a spacing between the dual-rotors' axes of rotation in the lobe pump. The method also includes determining the profile for the rotor based on the desired periodic flow rate, so that when the rotor is operated within the dual-rotor lobe pump system, the material can be pumped at substantially the desired periodic flow rate. In another embodiment of the invention, a lobe pump rotor profile is formed by the method described above.

Abstract: A variable capacity pump/motor has a meshing internal and external gear set disposed between an upper mandrel and a lower mandrel, each including a flange extending towards the gears to divide a pump/motor chamber into suction and discharge chambers. The inner gear is fixed and the external gear is axially moveable with respect thereto. The external gear and the upper mandrel move in response to changing pressures in the casing, allowing the motor to vary displacement and the pump to vary its output based on supplied fluid pressure or based on the speed of the prime mover. An external configuration includes a pair of meshing gears mounted on separate shafts in a casing. One gear is fixed and the other is axially moveable with respect thereto and moves in response to changing pressures in the casing. Each of the gears is sealed by a seal/bushing on a free end thereof.

Abstract: A drive transmission mechanism for transmitting torque between two or more rotary shafts in synchronization with one another without need for lubrication thereby eliminating occurrence of oil contamination, and an oil-free fluid machine equipped with the mechanism, are provided. A magnetic drive disk and a synchronization gear are attached to a rotary shaft connected to a drive motor, a magnetic drive disk and a synchronization gear is attached to a rotary shaft, torque transmission from the rotary shaft to the rotary shaft is carried out in two ways, via the magnetic drive disks and via the synchronization gears and at least one of the synchronization gears is made of plastic material. With the construction, torque transmit load between the rotary shafts via the synchronization gears is decreased, and a plastic gear or gears can be adopted for synchronization gears without reducing life of the gears without need for lubrication oil.

Abstract: Gearwheel pump, having a housing with at least two intermeshing gears with shafts supported by slide bearings lubricated with pumping medium (M) fed from a suction side to a pressure side, a return duct which leads pumping medium which flows outward through the plain bearing back to the suction side, and a valve (5) having a stationary part and a moveable part (20, 21). The valve (5) has a setting characteristic which runs, as a first approximation, linearly at least in one region, wherein the setting characteristic is defined by a differential pressure (?p) across the valve as a function of a setting path (x) in the valve (5) thereby significantly improving capability for setting the pressure in the transition region between the plain bearing and a dynamic seal of a driveshaft which is guided outward.

Abstract: In a gas compressor, housing heads are disposed to define an internal space with a housing, and two rotors housed in the internal space are rotatable to form in the internal space a compression chamber. The housing has an inner wall surface opposed to at least outer peripheral surfaces of the two rotors, and the housing heads are provided in correspondence to the respective rotors. One end portion of a rotary shaft of each rotor is supported by the housing, and other end portion of the rotary shaft of each rotor is supported by the housing heads. The housing heads have a first outer peripheral portion corresponding to the inner wall surface of the housing, and a second outer peripheral portion larger than the first outer peripheral portion. Furthermore, the first outer peripheral portion of the housing heads is fitted onto the inner wall surface of the housing.

Abstract: A hot melt adhesive metering pump assembly, and an integral reservoir tank fluidically connected thereto and the hot melt adhesive metering pump assembly comprises a plurality of rotary, gear-type metering pumps which are arranged in a compact, longitudinally spaced manner upon a drive gear manifold. All of the driven gears of pumps are respectively driven by manifold pump drive gears which are rotatably mounted upon a common motor-driven rotary drive shaft rotatably disposed within the drive gear manifold, and a first side wall member of a base portion of the reservoir tank is integrally connected to a side wall portion of the drive gear manifold, while a second side wall member of the base portion of the reservoir tank is provided with a plurality of hose connections to which hot melt adhesive delivery hoses are to be connected so as to respectively convey the precisely metered amounts of the hot melt adhesive material toward the applicator heads.

Abstract: The invention relates to a gear pump with two engaging gearwheels (9, 10) between a suction chamber and a pressure chamber, whereby the gearwheels are borne on bearing axles (11, 12) connected to the gearwheels. In accordance with the invention the gearwheels and the bearing axles are each manufactured of the same material as a homogenous workpiece. This allows simple construction of the gear pump with good operating properties at the same time. Preferably the gearwheels and bearing axles are made of synthetic material.

Abstract: A rotary blower with noise abatement jacket enclosure having multiple interconnected and synchronized parallel multi-lobe rotors with the same number of lobes for propelling flow from a suction port to a discharge port of an inner casing without internal compression. The noise abatement jacket enclosure is shaped to surround the blower and to conform generally to its body contours, but is oversized to provide adequate cooling spaces with outer skin of the blower. It comprises a forced air cooling jacket comprising an inner and outer cover, a sound absorbent layer comprising an inner and outer surface, the inner surface in contact with the blower outer cooling cover, and a sound barrier layer comprising an inner surface in contact with the outer surface of the sound absorbent layer.

Abstract: A Roots-type blower with helical cycloidal rotors features relief recesses in the chamber walls, isolated from the input and output ports. The relief recesses counter variation in leakback flow with angular position intrinsic to helical cycloidal rotors, attenuating a noise source.

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: The invention provides a twin-shaft, dry-running rotary piston machine (1) comprising two rotary pistons (8) supported in a housing (2) via shafts (4) and roller bearings (6) with rolling elements, said rotary pistons are horizontally arranged and mesh with each other in opposite directions, so as to define a conveying chamber; two oil chambers (10) arranged in said housing (2) at opposite front sides of the conveying chamber in the area of the roller bearings (6) and provided to be at least in part filled with lubricating oil, two splash elements (12), with per oil chamber (10) one splash element (12) being arranged on the shafts (4) in such a manner that every shaft (4) carries a total of only one splash element (12); and at least two connection channels (14) connecting the two oil chambers (10) with each other.

Abstract: A torsion damping mechanism for a rotary blower is provided that includes an input hub adapted to engage a first end of a torsion spring and an output hub adapted to engage a second end of the torsion spring. An intermediate hub is fixed for rotation with a first drive member. A bearing member includes an inner portion connected for rotation with the intermediate hub and an outer portion connected for rotation with the output hub. The bearing member may be a one-way bearing that permits torque to flow from the output hub into the intermediate hub and the first drive member when the output hub is driven in a first rotational direction, and permits the output hub to rotate relative to the intermediate hub with no substantial torque transfer therebetween when the output hub is driven in a second rotational direction.

Abstract: There is disclosed a Roots type pump in which two rotors are rotated synchronously in a pump chamber to compress fluid therein, wherein respective stop positions of the rotors in the pump chamber at a time of stopping the pump are determined independently of each other.

Abstract: An adjusting valve adjusting valve for adjusting the delivery volume of a displacement pump includes a valve casing, a valve piston which is mounted such that the valve piston can be moved within the valve casing, a valve spring which counteracts a force exerted by the valve-actuating pressure on the valve piston, and an adjusting device serving to adjust the valve piston in the direction of or counter to the force exerted by the valve-actuating pressure. A displacement pump exhibiting an adjustable delivery volume, includes a pump casing, a delivery chamber formed in the pump casing and a delivery member and the adjusting valve for adjusting the delivery volume, arranged in a flow of the fluid delivered by the delivery member.

Abstract: In a variable displacement type gear pump, each of a main gear pump portion and a sub gear pump portion has a drive gear, a driven gear engaging with the drive gear, and an urging portion applying radial load to the drive and driven gears. A bypass passage returns fluid in a discharge-side space of the sub gear pump portion to a suction passage. An opening and closing valve opens the bypass passage in a small displacement operational state. A drive shaft supports the main drive gear and the sub drive gear. A driven shaft supports the main driven gear and the sub driven gear. The drive gears and the driven gears are rotated in accordance with a rotation of the drive shaft. The drive and driven shafts transmit the radial load in the main gear pump portion to the sub gear pump portion in the small displacement operational state.

Abstract: A pump, in particular a hydraulic pump for a power steering system, has a housing. The pump is a prefabricated structural unit in which the end faces of the housing are closed by a flange and by a cover, respectively. The flange and the cover are braced against each other by at least one holding part.

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: The rotary piston machine has a bypass channel, which is formed through two openings (15, 16) provided in a sidewall (6) of its delivery housing (4) and a channel (17) extending into this sidewall (6) in such a way that the bypass channel (17) is restricted on one side by a wall area of the sidewall (6) and on the opposite side by a channel cover (19) embedded in this sidewall (6). The housing (25) of a pressure relief valve (14) is formed cup-shaped in the channel cover (19) in whose cylindrical inner surface (27) a closing member (2) is operated piston-like. The machine which is designed from few individual parts is suitable especially for the space-saving and direct coupling in the engine space of a motor vehicle, in which its pressure relief valve (14) provided in the bypass channel overcomes the disadvantages of the rotational speed-dependent pressure difference between suction and pressure sides.

Abstract: A side face of a pump gear is formed into a stepped face such that an annular region extending radially from a diameter which is smaller than a dedendum circle diameter of the pump gear and larger than the outer diameter of a pump gear bearing to the addendum circle diameter of the pump gear is recessed by a certain depth to increase the side gap in the recessed annular region. Therefore, the side gap in the recessed annular region is larger than a side gap in a region between the diameter smaller than the dedendum circle diameter of the pump gear and larger than the outer diameter of the pump gear bearing to the outer diameter of the pump gear bearing.

Abstract: Provided is a vacuum pump having a rotation body cleaning unit. The vacuum pump includes a case provided with rotation guide holes at opposite end parts. The case includes a rotation body placed inside the case and including a rotation shaft having opposite ends rotatably supported by the rotation guide holes and a number of lobes provided in the rotation shaft at predetermined intervals. Further, a cleaning part is supported by the case and placed in a space between the lobes and cleans the rotation body.