The present invention comprises: a blank forming step in which a casing blank (70) is formed by die-casting, the casing blank (70) having a first cylindrical section (41), a second cylindrical section (42), and an annular section (44) which includes a recess (71) recessed toward one side in an axial direction (O) from a first surface (44a) facing the other side in the axial direction (O); and a cutting step in which the inner peripheral surface (42a) of the second cylindrical section (42) and a second surface (44b) of the annular section (44), the second surface (44b) facing the one side in the axial direction (O), are cut to connect the recess (71) to a compression section containing space (42A) within the second cylindrical section (42), thereby forming a flow passage. In the blank forming step, the casing blank (70) is formed such that a part of a side surface (71a) of the recess (71) is disposed radially outside the inner peripheral surface (42a) of the second cylindrical section (42).

Provided is an internal gear pump requiring fewer machining steps, allowing inexpensive manufacture, and offering high safety from the standpoint of function. The internal gear pump 1 comprises: a trochoid 4 in which an inner rotor 3 having a plurality of outer teeth is eccentrically and rotatably accommodated in an outer rotor 2 having a plurality of inner teeth, the outer teeth meshing with the inner teeth, and in which a suction-side chamber for suctioning liquid and a discharge-side chamber for discharging liquid that has been suctioned into the suction-side chamber are formed in between the inner teeth and outer teeth; a casing 5 in which is formed a recess 5a for accommodating the trochoid 4; and a cover 6 for closing off the recess 5a of the casing 5. At least some of the casing 5 is a body injection-molded from a resin composition. The invention also comprises a groove 5d in a portion of the recess 5a of the casing 5 in which the outer periphery is sealed, with a sealing ring 13 installed therein, and bushings 7 made from sintered metal that are provided integrally during injection molding in bolt fixing hole portions.

A liquid pump having an electric motor, a pump assembly, which is driven by the electric motor, and a housing wherein the electric motor and the pump assembly are arranged, wherein the housing is in the form of a one-piece, injection-moulded pot having a base and side walls, wherein the pump assembly bears against the base, and the electric motor is arranged on the open side of the housing remote from the base.

A vacuum booster assembly includes, but is not limited to, a booster housing defining a booster chamber and including a gas inlet and a gas outlet; a first rotor positioned within the booster chamber and adapted for rotation therein, the first rotor including a first shaft and at least two lobes defining a first lobe profile; and a second rotor positioned within the booster chamber and adapted for rotation therein, the second rotor including a second shaft and at least two lobes defining a second lobe profile, wherein the first and second rotors are formed from a metal having a coefficient of thermal expansion from about 1 (10.sup.-6 in/in * K) to about 13 (10.sup.-6 in/in * K), and wherein at least one of the outer surface of the first rotor, the outer surface of the second rotor, or the booster chamber includes a coating.

A screw rotor is made out of polymer. The screw rotor includes a shaft with a rotor body on it. The polymer of the shaft is reinforced with fibers. The shaft features elements that engage the rotor body or corresponding elements on the rotor body, such that the elements prevent an axial and/or rotational movement of the shaft with respect to the rotor body.

A cast for producing end plates for a pump assembly, the cast comprising a base portion and a pair of projections, the pair of projections providing material to machine bearing assembly housings for accommodating drive and idler shafts in the pump assembly. Also provided is an inner plate bushing for an end plate in a pump assembly, the inner plate bushing comprising a collar extending from a flange, the collar to be inserted into a mounting recess in the end plate with the flange seating flush with a surface of the end plate, the surface area of an end of the collar being larger than an inner surface of the flange.

A rotor for a mud motor includes a core having a first outer shape, and a shell positioned around the core, the shell having a second outer shape that is different from the first outer shape, the second outer shape defining one or more lobes and one or more cavities that are configured to engage a bore of a stator during rotation of the rotor relative to the stator. A thickness of the shell varies as proceeding around the core, from a non-zero minimum thickness to a maximum thickness.

A stator for use in a positive displacement motor or a progressing cavity pump. The stator comprises an elastomer mix preferably including rubber and a fiber reinforcement. The fiber reinforcement includes a plurality of fibers. The elastomer mix is formed into a stator via an injection molding process. The injection molding process includes a shear flow step in which shear flow is induced in the elastomer mix while the elastomer mix is in an uncured state. The shear flow modifies the orientation of the fibers into an advantageous modified fiber orientation. Shear flow is induced preferably via differential rotation of injection mold assembly elements during the injection molding process. Methods of manufacturing the stator are also disclosed.

A rotating electric machine includes a plurality of iron cores, arid a plurality of supporting members. At least one of the iron cores is supported by one of the supporting members via a resin member. At least one of the iron core and the supporting member supporting the iron core via the resin member has an elastic deformation portion configured to press the resin member against an other one of the iron core and the supporting member supporting the iron core. A method of manufacturing a rotating electric machine includes forming a resin member on an elastic deformation portion by injection molding, and fixing an iron core and a supporting member to each other while elastically deforming the elastic deformation portion.

Provided is an internal gear pump in which a casing and a cover can be easily positioned to each other when the casing and the cover are assembled, and they can be prevented from separating or falling off. In an internal gear pump 1, at least one of a casing 5 and a cover 6 is a molded body of a resin composition and the like. The casing 5 and the cover 6 are fixed with a plurality of protrusion parts protruding from one of the casing 5 and the cover 6 fitted in the other. The protrusion parts protrude from the casing of metal bushes 9 fixed to the casing 5, and the casing 5 and the cover 6 are integrated by bolts 13 passing through the metal bushes 9 across these two members.