Abstract: There is provided a sliding part in which a surface coverage ratio of copper in the sliding part increases. A bearing which is the sliding part is formed by filling the raw powder into the filling portion of the forming mold, compacting the raw powder to form a powder compact, which is sintered. A copper-based raw powder is composed of a copper-based flat raw powder whose diameter is smaller than that of an iron-based raw powder and an aspect ratio larger than that of the iron-based raw powder, and a copper-based small-sized raw powder whose diameter is smaller than that of the copper-based flat raw powder. The copper is allowed to segregate at the surface of the sliding part. The surface of the bearing is covered with the copper-based small-sized raw powder and the copper-based flat raw powder, thereby the surface coverage ratio of copper can be increased.

Abstract: In an internal gear pump of the present invention, a first angle that is formed by a first straight line that connects a rotation axis of an inner rotor to a tooth tip portion of an external tooth in the rotational direction of the inner rotor and an outer rotor, and a second straight line that connects the rotation axis to a meshing portion of the external tooth is not less than 1.4 times the size and not more than 1.8 times the size of a second angle that is formed by a third straight line that connects the rotation axis to a tooth bottom of the external tooth, and the second straight line.

Abstract: A reciprocating engine includes: an inner stator having an axis; a mover that has a cylindrical shape and is placed coaxially around the inner stator, and that moves reciprocatingly along the axis; and an outer stator that has a cylindrical shape and is placed coaxially around the mover, wherein the outer stator has: an aperture portion that is formed in an inner circumferential surface thereof that faces the mover; an internal space that opens via the aperture portion; and a wound wire coil that is placed inside the internal space, and wherein the mover has: a field magnet portion; and restoring magnet portions that are provided respectively at both end positions along the axis of the field magnet portion.

Abstract: A Cu—Ni—Sn copper-based sintered alloy has a composition including 10 to 40% by mass of Ni, 5 to 25% by mass of Si, and the remainder containing Cu and inevitable impurities, and if necessary, 0.1 to 0.9% by mass of P, 1 to 10% by mass of C, 0.3 to 6% by mass of calcium fluoride or 0.3 to 6% by mass of molybdenum disulfide. In the structure of the alloy, a phase of a composition containing Cu(4-x-y)NixSny (where x: 1.7 to 2.3, y: 0.2 to 1.3) is dispersed.

Abstract: An oil pump rotor assembly is disclosed. An inner rotor formed with n external teeth is based on cycloid curves which are generated by a first circumscribed-rolling circle and a first inscribed-rolling circle by rolling the first circumscribed-rolling circle and first inscribed-rolling circle along an inner base circle. An outer rotor formed with n+1 internal teeth (n+1 is the number of teeth) is based on cycloid curves which are generated by a second circumscribed-rolling circle and a second inscribed-rolling circle by rolling the second circumscribed-rolling circle and second inscribed-rolling circles along an outer base circle.

Abstract: A surface treatment layer 11 is formed on a surface 10 of a through-hole 1 so that the surface 10 has an angle X of contact with solution L which is smaller than an angle Y of contact of a die 2 per se with the solution L. When the solution L is applied, the wetting action of the solution L relative to the through-hole 1 is improved so that the solution L can be extended over the surface treatment layer 11, eventually over the entire surface of the through-hole 1. Consequently, the entire surface thereof can be formed with a crystallized layer by performing water evaporation. As a result, molding at higher temperature can be realized, and high-density compacts can be stably obtained. Further, the solution L in which the lubricant is dissolved in a solvent into a homogeneous phase, is applied to a molding portion 1A, and then evaporated to thereby form crystals thereon, thus forming the crystallized layer.

Abstract: A hydroxy fatty acid salt having an average particle diameter of from 5 ?m to 100 ?m with a composition of from 0.3 wt % to 2 wt %, and more preferably, from 0.5 wt % to 2 wt % is added to a raw material powder in powder metallurgy, and worm molding is performed. In addition, a hydroxy fatty acid salt having an average particle diameter of 50 ?m or less is attached on a mold in advance, and after that, the warm molding is performed. As a hydroxy fatty acid salt, 12-hydroxy lithium stearate is suitably used.

Abstract: This iron-based sintered alloy contains 0.05 to 3% by mass of calcium carbonate or 0.05 to 3% by mass of strontium carbonate. As a result, an iron-based sintered alloy having excellent machinability is obtained.

Abstract: A crankshaft and an mounting hole have two main circular arc parts on the same circle; and two connecting parts for connecting the adjacent main circular arc parts, and have a cross-sectional shape in which the connecting parts facing each other are substantially parallel. The connecting parts of the mounting hole are formed in the shape of a large circular arc which projects inward. The torque of the crankshaft is transmitted to the mounting hole in a state where the connecting parts of the crankshaft and the connecting parts of the mounting hole which are formed in the shape of a large circular arc come into line contact with each other; therefore, the value of any local stress generated in the mounting hole can be reduced.

Abstract: Oxide-coated Fe powder for producing various electromagnetic circuit components requiring high resistivity is provided. The oxide-coated Fe powder is a Mg-containing oxide film-coated iron powder coated with an Mg—Fe—O ternary-based deposition film at least containing (Mg, Fe)O. The (Mg,Fe)O is a crystalline MgO-dissolving wustite. The Mg—Fe—O ternary-based oxide deposition film has a sulfur-enriched layer containing a higher concentration of sulfur than that of central portion of the iron powder, fine crystalline texture having a grain size of 200 nm or less, and the outermost surface is substantially composed of MgO. A composite soft magnetic material using the Mg-containing oxide film-coated iron powder is also provided.

Abstract: There is provided a sliding part in which a surface coverage ratio of copper in the sliding part increases. A bearing which is the sliding part is formed by filling the raw powder into the filling portion of the forming mold, compacting the raw powder to form a powder compact 6, and sintering the powder compact 6. A copper-based raw powder is composed of a copper-based flat raw powder 2 having an average diameter smaller than that of an iron-based raw powder 1 and an aspect ratio larger than that of the iron-based raw powder 1, and a copper-based small-sized raw powder 3 having the average diameter is smaller than that of the copper-based flat raw powder 2. The copper is allowed to segregate at the surface of the sliding part.

Abstract: An inner rotor having excellent corrosion resistance, which has an outer gear serving as a component of an internal gear pump, and an outer rotor having excellent corrosion resistance, which has an inner gear engaging with the outer gear. The inner rotor and outer rotor of are made of Cu—Ni-based sintered copper alloy that contains 12 to 50% by mass of Ni, 5 to 20% by mass of Sn, 0.5 to 5% by mass of C, and if necessary, further contains 5 to 20% by mass of Zn, 0.1 to 0.9% by mass of P, and a balance being Cu and inevitable impurities.

Abstract: A rotor pump assembly is disclosed which reduces noise emitted from an oil pump while preventing pumping performance and mechanical efficiency thereof from being decreased by properly forming the profiles of teeth of an inner rotor and an outer rotor which are engageable with each other. The tooth profile of an inner rotor and/or an outer rotor has curved lines obtained by dividing a cycloid curve into two segments to be separated from each other, and in which the separated segments are smoothly connected to each other using a straight line or a curve.

Abstract: A bearing for a motorized fuel pump is made of a Cu—Ni based sintered alloy, composed of: 21 to 35% by mass of Ni, 5 to 12% by mass of Sn, 3 to 7% by mass of C, 0.1 to 0.8% by mass of P, and the balance of Cu and inevitable impurities. A matrix of the bearing is formed with pores with a porosity of 8 to 18%, and the P component is predominantly included at the grain boundary, and free graphite is distributed along the insides of open pores that are open to the surface and extending into the bearing. In this bearing, a Sn rich alloy layer containing equal to or more than 50% by mass of Sn is formed on the insides of the open pores and near openings of the open pores.

Abstract: A crankshaft and an mounting hole have two main circular arc parts on the same circle; and two connecting parts for connecting the adjacent main circular arc parts, and have a cross-sectional shape in which the connecting parts facing each other are substantially parallel. The connecting parts of the mounting hole are formed in the shape of a large circular arc which projects inward. The torque of the crankshaft is transmitted to the mounting hole in a state where the connecting parts of the crankshaft and the connecting parts of the mounting hole which are formed in the shape of a large circular arc come into line contact with each other; therefore, the value of any local stress generated in the mounting hole can be reduced.

Abstract: In pump rotors and used in an internal gear pump, which includes an inner pump rotor having outer gear teeth; an outer pump rotor having inner gear teeth that mesh with the outer gear teeth; and a casing having a pumping-in port through which a fluid is pumped in, and a pumping-out port through which the fluid is pumped out, and pumps in and pumps out the fluid by changing the cell volume formed between gear tooth surfaces of the rotors and so as to carry the fluid when the rotors and mesh with each other and rotate, the rotors are formed from a sintered material of Fe—Cu—C and have a density of not less than 6.6 g/cm3 and not more than 7.1 g/cm3, and the outer circumferential surface of the outer pump rotor and the end surfaces perpendicular to rotation axes of the rotors and are non-grinded surface and have a ten point height of irregularities Rz of not less than 4 ?m and not more than 10 ?m.

Abstract: There is provided an oil-impregnated sintered bearing which enable to prevent oil leakage from an outer peripheral surface 7 of an bearing body 2. The oil-impregnated sintered bearing 1 includes a bearing body 2 which is made of a porous sintered alloy containing vacancies 8 and has a bearing hole 3 in which a rotary shaft can be inserted, wherein the vacancies 8 opened on an outer peripheral surface 7 of the bearing body 2 are crushed. The vacancies 8 may be crushed in the state of a green compact P, or in the state of a sintered alloy after sintering the green compact P. Consequently, the oil leakage from the outer peripheral surface 7 of the bearing 1 can be prevented, and oil pressure in the bearing hole 3 can be preserved.

Abstract: A sinter of stable quality is produced by molding a powder for powder metallurgy. This process includes successively conducting the following steps: charging a powder and a solid lubricant into a mold compact formation in which the powder charged into the mold is compacted; releasing the compact from the mold (1); and the powder for powder metallurgy is charged again into the mold after the release step. The compact is sintered to produce a sinter. The temperature of the mold is set at a value in the range of from the boiling point of water to the melting point of the solid lubricant. The compact can be continuously formed without causing, e.g., a failure in the feeding of the powder for powder metallurgy. The sinter obtained by sintering the compact is almost even in strength and density. Thus, a stable sinter almost even in strength and density can be produced.

Abstract: An object of the present invention is to provide a composite soft magnetic sintered material that has high density, high mechanical strength and high relative magnetic permeability at high frequencies and, in order to achieve this object, the present invention provides a method of producing the composite soft magnetic sintered material, which comprises mixing a composite soft magnetic powder, that consists of iron powder, Fe—Si based soft magnetic iron alloy powder, Fe—Al based soft magnetic iron alloy powder, Fe—Si—Al based soft magnetic iron alloy powder, Fe—Cr based soft magnetic iron alloy powder or nickel-based soft magnetic alloy powder (hereinafter these powders are referred to as soft magnetic metal powder) of which particles arc coated with a ferrite layer which has a spinel structure, with 0.05 to 1.

Abstract: A hydroxy fatty acid salt having an average particle diameter of from 5 ?m to 100 ?m with a composition of from 0.3 wt % to 2 wt %, and more preferably, from 0.5 wt % to 2 wt % is added to a raw material powder in powder metallurgy, and worm molding is performed. In addition, a hydroxy fatty acid salt having an average particle diameter of 50 ?m or less is attached on a mold in advance, and after that, the warm molding is performed. As a hydroxy fatty acid salt, 12-hydroxy lithium stearate is suitably used.