A rotary internal combustion engine includes a rotor housing having a peripheral wall circumscribing a rotor cavity and a rotor disposed within the rotor cavity. A side housing is secured to the rotor housing and a plate defines a seal running surface for the rotor. The plate is disposed between a portion of the side housing and the rotor housing and at least one shim is disposed between the plate and the side housing for spacing the plate apart from contact with the side housing.

An upper piston of a rotary compressor is formed to satisfy 0.7Hcy1/1000ro1.2Hcy1/1000, Cro10.1, Cro20.1, and Cro1Cro20.007. Here, Cro1 indicates a length (mm) of an upper side piston outer circumferential chamfer portion in a height direction, and Cro2 indicates a length (mm) of the upper side piston outer circumferential chamfer portion in a normal line direction of a piston outer circumferential surface. An upper vane is formed to satisfy 0.7Hcy1/1000v1.2Hcy1/1000, Cv10.06, Cv20.06, and Cv1Cv20.003. Here, Cv1 indicates a length (mm) of an upper side vane ridge line chamfer portion in a height direction, and Cv2 indicates a length (mm) of the upper side vane ridge line chamfer portion in a normal line direction of a vane tip end surface.

Method for increasing the smoothness of the free surface area of a PFA film, provided on a component by sequentially exposing it to a temperature higher than its melting temperature so as to melt at least the free surface area, lowering the temperature to solidify the melted portion, remelting the free surface area by exposing it to a temperature of at least the PFA melting temperature and again lowering the temperature. The PFA film may be provided on Al.sub.2O.sub.3, Ni or NiF.sub.2 film.

In the present invention, polishing lines 71f are connected to an outer circumferential high-pressure region, but are not connected to each area that is a low-pressure region. In this configuration, the polishing lines 71f are connected to the outer circumferential high-pressure region where there is high discharge pressure, so high-pressure brake fluid is introduced within the polishing lines 71f. Therefore, a pushback effect is obtained, wherein gear pumps 19 and 39 are pushed back on the basis of the high-pressure brake fluid pressure. Furthermore, the polishing lines 71f are connected to the outer circumferential high-pressure region but are not connected to each area that is a low-pressure region, so high-pressure can be maintained within the polishing lines 71f, and a reduction in the pushback effect can be prevented. Accordingly, a decrease in the loss torque reduction effect can be prevented, and the loss torque can be further reduced.

Fluid delivery devices using a pair of meshed external gears, in spite of no reciprocating component for fluid delivery enabling low rotational vibration, the high noise due to the trapping phenomenon, and the teeth bouncing contact due to undesired large backlash heretofore afforded in the gear manufacturing process, restrict the employments in the industrial field requiring quiet environment such as electric motor vehicles or room services. Accordingly, a gear pump or motor or a gear refrigerating compressor comprising a shaft gear and a driven gear meshed rotatably within a gear chamber formed with a housing and opposite side walls, which delivers fluids from a inlet chamber to a outlet chamber; a backlash of the meshed gears having fluid-leak-tight clearance; a closed chamber provided in a internal portion of at least a side wall; an opening provided on a side wall from which a communication passage extends to a closed chamber; and at least a elastic disc capsule contained in the closed chamber, comprising a pair of concaved elastic disc plate abutted and sealed against each other with gas inside, of which occupying volume varies elastically subject to the fluid pressure therein enabling to absorb or expel the squeezed fluid in the trapped interstice during the trapping period of the interstice, whereby the fluid entrapped in the interstices isolated by the fluid-leak-tight backlash suppressing the pressure transmission inwardly or outwardly, whereof volumetric variation during the trapping period is compensated by the compression or expansion of the elastic disc capsule, suppressing pressure pulse and air bubble generation and eliminating the teeth bouncing contact, achieving a low noise, low vibration and high efficiency gear pump or motor or refrigerating compressor.

A screw compressor for compressing a working medium sucked through a suction opening and discharging the compressed working medium through a delivery opening, wherein the screw compressor includes: a male rotor and a female rotor that rotate while meshing with each other; a casing that houses the male rotor and the female rotor and is provided with a bore which forms a working chamber designed, together with the male rotor and the female rotor, to compress the working medium; a drive unit that rotationally drives at least one of the male rotor and the female rotor; a working chamber closing unit that forms a suction port for sucking the working medium into the working chamber and closes the working chamber when the working chamber reaches a specified capacity; and a suction space that connects the suction opening and the suction port to allow communication therebetween.

A pump housing includes: a slide surface, along which inner and outer gears are slid; a suction guide passage, which is recessed from the slide surface and guides the fuel at a suction side; a discharge passage, which is recessed from the slide surface-and guides the fuel at a discharge side; and a communication groove, which is recessed from the slide surface and is shaped into an arcuate form that extends along a circumcircle of the inner gear. The communication groove is communicated with the suction groove and the discharge passage through two opposite groove end parts, respectively, of the communication groove.

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 scroll compressor includes a first chamfered portion formed at a distal end potion of a spiral blade of a fixed scroll, a second chamfered portion formed at a distal end portion of a spiral blade of an orbiting scroll, a third chamfered portion formed at a bottom portion of the spiral blade of the fixed scroll, and a fourth chamfered portion formed at a bottom portion of the spiral blade of the orbiting scroll. An expression of 0<{(Av1+Av2)/2}/Ac<110.sup.4 is satisfied where a sectional area of a space between the first chamfered portion and the fourth chamfered portion is defined as Av1, a sectional area of a space between the second chamfered portion and the third chamfered portion is defined as Av2, and a sectional area of a compression chamber is defined as Ac.

A mud motor for use in a wellbore may include a stator and rotor. The tolerance between the stator and rotor may be varied along the length of the mud motor to, for example, reduce wear of the stator at predetermined locations. The tolerance may range from an interference fit to a clearance fit. The tolerance may vary multiple times across the length of the mud motor.