Abstract: A broaching method for finishing an outer peripheral surface of a resin layer of a resin-coated lobe-type rotor for a rotary fluid machine of a Roots type, which includes the steps of forming, with a leading grooving cutter, at least one chip-breaker groove in the outer peripheral surface of the resin layer, such that the chip-breaker groove extends in a broaching direction parallel to an axis of rotation of the rotor. The method further includes the steps of finishing at least a portion of the outer peripheral surface of the resin layer with a trailing finish cutter having a cutting edge contour corresponding to the portion of the outer peripheral surface of the resin layer, which is finished by the finish cutter after the chip-breaker groove is formed therein by the grooving cutter. A composite broach or formed broach having the grooving and finish cutters is fed such that the grooving cutter leads the finish cutter in the broaching direction.

Abstract: A Roots pump having a plurality of rotor assemblies each including a light-alloy rotor, a steel shaft press-fitted in a bore of the rotor and a lock pin which is inserted through the rotor and the shaft to prevent removal of the shaft from the rotor. The lock pin is located substantially at an axial center of a press-fitted portion of the shaft accommodated the axial bore. The shaft has a timing gear at one end thereof for meshing with a timing gear of the shaft of the adjacent rotor assembly. The shaft further has a plurality of engagement teeth provided at one of opposite ends of the press-fitted portion on the side of the timing gear. The engagement teeth are at least partially embedded in an inner surface defining the axial bore of the rotor, upon press-fitting of the press-fitted portion in the axis bore, to thereby prevent a rotational movement of the shaft relative to the rotor.

Abstract: A broaching machine for broaching an outer surface of a rotor of a rotor assembly which includes a support shaft projecting from opposite end faces of the rotor for supporting the rotor rotatably about its axis. The machine includes a backing plate for backing the rotor assembly such that one of the end faces of the rotor is held in contact with backing plate. The circumferential position of the rotor assembly is established by a positioning pin which extends from the backing plate, and engages a hole formed in the rotor. The machine includes a first centering device which has a center engageable with one of opposite ends of the support shaft so as to hold and center the support shaft at the one end, and a second centering device having a V-block and a retainer block which are engageable with the other end of the support shaft so as to hold and center the support shaft at the other end.

Abstract: A Roots-type rotary fluid machine having resin-coated rotors fluid-tightly accomodated in a chamber formed in a housing structure which consists of a generally cup-shaped main housing body having a bore closed at its one end and open the other end, and a covering member which closes the open end of the bore in the housing body. The housing body includes a fillet portion which bridges an inner flat surface defining the bottom of the bore and facing one end face of each rotor, and an inner peripheral surface defining the periphery of the bore and facing the outer peripheral surface of each rotor. The fillet portion is formed along a line of intersection of extensions of the inner flat surface and the inner peripheral surface of the housing body, and inwardly into the bore from this line of intersection. The fillet portion has a generally triangular shape in cross section taken in a direction perpendicular to the above line of intersection.

Abstract: Method and apparatus for broaching an outer surface of a resin layer of a resin-coated part whose external side surface is coated with the resin layer, wherein a backing plate is used to back the resin-coated part such that the plate is held in contact with an end face of the part at which a movable broach terminates a broaching cut in a direction along the outer surface of the resin layer. The backing plate has an external profile similar to a cutting edge contour of the broach. The backing plate is positioned on a work bed of the broaching apparatus such that its external profile is inwardly spaced from the cutting edge contour of the broach a plane perpendicular to the direction of movement of the broach. The backing plate, which forms a part of a work-holding fixture, serves to protect the resin layer from breakage, chipping or other defects at the end of a broaching pass along the outside of the resin-coated part.

Abstract: A broaching method for finishing an outer peripheral surface of a resin layer of a resin-coated lobe-type rotor for a rotary fluid machine of a Roots type, which includes the steps of forming, with a leading grooving cutter, at least one chip-breaker groove in the outer peripheral surface of the resin layer, such that the chip-breaker groove extends in a broaching direction parallel to an axis of rotation of the rotor. The method further includes the steps of finishing at least a portion of the outer peripheral surface of the resin layer with a trailing finish cutter having a cutting edge contour corresponding to the portion of the outer peripheral surface of the resin layer, which is finished by the finish cutter after the chip-breaker groove is formed therein by the grooving cutter. A composite broach or formed broach having the grooving and finish cutters is fed such that the grooving cutter leads the finish cutter in the broaching direction.

Abstract: A solenoid valve for hydraulic control, comprises: a stationary iron core; a guide pipe; a return spring; a plunger; and a valve body.Firstly, the plunger is made slidable immediately on the inner periphery of a columnar recess of the stationary iron core, whereby a magnetic reluctance of a magnetic path formed when a current is passed is decreased, so that an attracting force can be increased accordingly.Furthermore, the plunger made hollow is made slidable on the outer periphery of the guide pipe and the valve body is fixed to and disposed at an end portion of the plunger, so that these movable members can be rendered light in weight.Further, a member for guiding the sliding of the plunger (a guide pipe) is disposed on the inner periphery of the plunger made hollow, further, this guide member is made hollow, and a return spring is incorporated in this guide member, so that the solenoid valve as a whole can be rendered very compact.

Abstract: A lubrication device in a transmission in which change-speed gears rotatable on a hollow shaft are arranged to be supplied with lubricating oil through an axial blind bore in the shaft. The lubrication device includes an oil collector mounted in a casing assembly for the transmission and located above an open end of the axial blind bore in the shaft to receive lubricating oil picked up in the casing assembly, an oil feed pipe extending from the collector into the open end portion of the bore, and a pump impeller assembly mounted in the open end portion of the bore to impel the lubricating oil from the feed pipe toward the closed end of the bore during rotation of the hollow shaft.