A suction side end part of a suction guide passage and a discharge side end part of a discharge guide passage are opposed to each other with a gap therebetween. At a deviation angle at which contraction of a pump chamber starts, an outer peripheral part of the discharge side end part is formed along an inner tooth, and an inner peripheral part of the discharge side end part is formed along an outer tooth. A working tool that rotates and cuts circularly is moved around on a pump housing in a single continuous line to form an outline of the discharge guide passage, thereby forming the discharge guide passage. The working tool is moved around on the pump housing in a single continuous line to form an outline of the suction guide passage, thereby forming the suction guide passage.

A rotary pump includes: a pump rotor having a flat rotor side surface facing in an axial direction; a housing body having an opening in the axial direction and a flat flange surface formed around the opening, the housing body rotatably housing the pump rotor in the opening such that the rotor side surface is flush with the flange surface; and a cover member having a flat mating surface that is fixed while being pressed against the flange surface by fastening of a bolt, and a flat sliding/guiding surface that slides and guides the rotor side surface. The cover member is formed of a crosslinked fluororesin and a metal body. The metal body is provided with the mating surface, and a recess obtained by recessing an area corresponding to the sliding/guiding surface, in the axial direction with respect to the mating surface.

An example apparatus includes an outer rotor having a first axial face and a second axial face opposite the first axial face, wherein the first axial face comprises a circumferential contour defining a plurality of lobe faces, and wherein the second axial face comprises a transformed circumferential contour defining a corresponding plurality of lobe faces, where the transformed circumferential contour comprises at least one of a scale transformation of the circumferential contour or a rotational transformation of the circumferential contour; and an inner rotor configured to rotate eccentrically within the outer rotor, thereby forming a gerotor element for a fluid pump.

A scroll assembly includes an orbiting scroll and a cross ring. The orbiting scroll is configured to have a bottom plate. A plurality of bayonets and two positioning slots are provided on the outer peripheral surface of the bottom plate. The bayonets are adapted to be clamped by a chuck of a turning tool. The two positioning slots are arranged centrally symmetrically relative to the center of the orbiting scroll. Each of the positioning slots comprises two radial vertical surfaces, a circumferential vertical surface and an opening facing outwards in the radial direction. The cross ring is configured to have an annular body and two positioning pins. The lower surface of the bottom plate is slidably fitted on the upper surface of the annular body, each of the positioning pins is inserted into a corresponding positioning slot, and the positioning pins can slide back and forth relative to the positioning slot, so that the orbiting scroll can slide back and forth relative to the cross ring in the radial direction of the orbiting scroll. An annular groove adapted for being formed by turning is provided on the lower surface of the bottom plate of the orbiting scroll, and a chamfer is formed on the edge of the annular groove formed by the intersection of the circumferential vertical surface of the positioning groove and the lower surface of the bottom plate.

A method of manufacturing pumps of different performances for use in a blood treatment device, preferably a dialysis machine, having a pump housing or a pump housing portion for supportingly holding two gear wheels in meshing engagement. The method includes the step of primary shaping of a universal pump housing blank with all features common to the different pumps as well as with such oversizes as to allow machining for manufacturing all different pumps from the same primary-shaped pump housing blank. The method also includes the step of individualizing the universal pump housing blank by machining in the region of the oversizes to achieve the respective performance.

Disclosed are a movable scroll device for a scroll compressor and a method for manufacturing same. The method includes: manufacturing the movable scroll device by means of casting steps, so that the movable scroll device includes a movable scroll end plate, with a movable scroll blade provided on a first side face of the movable scroll end plate; and a hub vertically extending outwards from the middle of a second side face of the movable scroll end plate; and fabricating at least one centroid adjustment recess on the hub. By the method, the centroid of the movable scroll device can be adjusted in a more flexible, precise, active and targeted manner.

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 method of machining, with a formed tool, a first rotor and a second rotor with mutually complementary meshing threads involves rotating a first workpiece about a longitudinal axis of the workpiece. The tool makes one or more passes along the longitudinal axis of the workpiece as the workpiece rotates so as to remove material, thereby forming the flanks of each helix of the first rotor's thread. The value of at least one of the parameters that collectively define the relative position and relative movement of the workpiece and formed tool is varied during each pass so as to vary the lead of the thread. The above steps are repeated for a second workpiece, thereby forming the second rotor. Adjustments are made to at least one of said parameters during one or more of the passes in order to maintain mutually complementary shapes of the threads of the rotors.

A crescent internal gear pump includes a front cover, an end cover, a ring gear and a pinion gear disposed within a gear housing in an eccentric, intermeshing relationship. The housing is disposed intermediate the front cover and the end cover. A crescent is disposed radially intermediate the ring gear and the pinion gear. The crescent partially extends into a correspondingly shaped slot in the end cover. The gear housing, the ring gear, and the pinion gear can have substantially the same thickness. A shim can be disposed intermediate the end cover and the gear housing for establishing a desired clearance therebetween.

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.