Abstract: An oil ring mechanism of a piston includes a circumferential ring groove formed in an outer peripheral surface of the piston, and a two-piece oil ring having a ring-shaped ring main body that is arranged in the ring groove and urged in the outer peripheral direction inside the ring groove by a coil expander arranged on the inner peripheral side of the oil ring main body. On lower side surface on a crankcase side of a side wall surface of the ring groove that is on the opposite side of the ring groove from an engine combustion chamber, first and second recessed portions that reduce the abutment area where a lower surface of the ring main body abuts against the lower side surface formed in a lower side abutment surface that serves as a surface for abutting against the lower surface of the ring main body.

Abstract: A wire material for a coil expander capable of manufacturing a coil expander that is unlikely to cause disadvantages such as abnormal wear and resultant reduction in strength The wire material for a coil expander is used for a coil expander of a combination piston ring having a piston ring and the coil expander for pressing and urging the piston ring outward in the radial direction thereof, wherein a cross-sectional shape thereof is a rectangular shape, and when the coil expander is formed by using the wire material for a coil expander, the surface of the wire material for a coil expander, constituting an outer peripheral surface of the coil expander, is formed into a convex curved shape.

Abstract: It is an object of the present invention to provide a valve seat product in which the amount of hard particles added to improve the wear resistance of a valve seat of an internal combustion engine is increased, and is excellent in the mechanical strength and machinability.

Abstract: An object of the present invention is to provide a cylinder structure reduced in mutual damage caused by a sliding operation of a piston ring and a cylinder liner when the piston ring having a linear expansion property which follows linear expansion of the cylinder liner made of an aluminum alloy is used. In order to achieve the object, a combination structure of the piston ring and the cylinder liner for an internal combustion engine described below is employed. In the cylinder liner for an internal combustion engine, the inner circumferential surface satisfies the conditions, a ten-point height of roughness profile (RzJIS94) of 0.5 ?m to 1.0 ?m, a core roughness depth (Rk) of 0.2 ?m to 0.4 ?m, a reduced peak height (Rpk) of 0.05 ?m to 0.1 ?m and a reduced valley depths (Rvk) of 0.08 ?m to 0.2 ?m. In the piston ring, the sliding surface against to an inner circumferential surface in the cylinder liner satisfies the conditions, a ten-point height of roughness profile (RzJIS94) of not more than 1.

Abstract: A three-piece oil ring and a combination of the three-piece oil ring and a piston, those capable of realizing improved sealing property and reduction in lubrication oil consumption with avoiding generation of sticking even at low tension and thin width of the ring. The three-piece oil ring includes a spacer expander 10 and two side rails. The spacer expander has a radially inner end portion provided with seating tabs 13 protruding in an axial direction and having radially outer inclined surfaces for urging inner peripheral surfaces of the first and second side rails. The spacer expander has a radially outer end portion provided with side rail support portions 14 projecting in the axial direction for supporting axial end faces of the first and second side rails. A seating tab angle of the outer inclined surface relative to an axis is in a range of 10 to 20 degrees, and a ratio of 2X/Y is in a range of from 0.04 to 0.

Abstract: A steel product having a composition which contains by mass C: 0.01 to 1.9%, Si: 0.01 to 1.9%, Mn: 5.0 to 24.0% with balance consisting of Fe and unavoidable impurities and a steel product described above which further contains Cr: 18.0% or below and/or Ni: 12.0% or below in addition to the above essential elements. The above steel products may each further contain Al: 1% or below and/or N: 0.3% or below and the above steel products may each further contain one or more elements selected from among Nb, Ti, Zr, Mo and Cu in a total amount of 4.0% or below. The steel products can sufficiently follow the thermal expansion of a cylinder made of an aluminum alloy and thus enables the production of a piston ring which is suitable for use as a piston ring to slide on the inner face of a cylinder bore made of an aluminum alloy in an internal combustion engine and which can retain excellent sealing properties.

Abstract: The invention provides a flake graphite cast iron being highly strong and excellent in workability such as cutting performance, which is suitable for use, for example, in internal combustion engine parts and the like, and a production method thereof without using a misch metal. Specifically, the flake graphite cast iron according to the invention includes an A-type graphite with a uniformly and disorderly distributed existence form without directionality; and has a chemical composition containing 2.8 to 4.0 mass % of C, 1.2 to 3.0 mass % of Si, 1.1 to 3.0 mass % of Mn, 0.01 to 0.6 mass % of P, 0.01 to 0.30 mass % of S and the remainder being Fe and inevitable impurities, wherein the ratio (Mn/S) of the Mn content to the S content is within a range of 3 to 300.

Abstract: A method for manufacturing a shaft member having a sintered part bonded thereto is simple and provides an increased process yield and a high accuracy in position and angle of the sintered part. A green compact is prepared by subjecting a metal or alloy powder to a compression molding. A projection formed on an outer peripheral surface of the shaft member is embedded into the green compact, while chipping partially the green compact with the projection, to combine the green compact with the shaft member. Then, a sintering is carried out.

Abstract: A preform main body of an iron species preform for forming a metal matrix composite inserted in an aluminum species alloy base material to be cast-in is bored with a first to fourth through holes communicating an inner peripheral face and an outer peripheral face. In a cast-in step, shrinkage in a peripheral direction of the inner peripheral face and the outer peripheral face of the iron species preform in accordance with solidification of the melted aluminum species alloy is uniformly received by shrinkage in accordance with solidification of the melted aluminum species alloy invading the through holes, movement thereof in the peripheral direction is restrained, a clearance can be prevented from being brought about at an interface, a cast-in performance is excellent and a stable bonding strength of the interface is achieved.

Abstract: An iron species preform for forming a metal matrix composite is inserted in an aluminum species alloy member to be cast-in. The aluminum species alloy member has bearing faces having a section in a semicircular arc shape. An inner peripheral face of the iron species preform is provided with a plurality of inner side grooves. The inner side groove includes flat portions and groove bottom portions continuous to two end edges continuous to the inner peripheral face and opposed to each other. In a cast-in step, shrinkage in a peripheral direction accompanied by solidifying a melted aluminum species alloy is uniformly received by the respective inner side grooves, movement in the peripheral direction is restrained, a clearance at an interface can be prevented from being brought about, so that a cast-in performance is excellent, and stable bonding strength and close contact of the interface can be ensured.

Abstract: An oil ring for an internal combustion engine capable of securing an area of an oil-passing hole without deteriorating the strength of the oil ring. To achieve this the oil ring is provided with an oil-passing hole including: two arc portions disposed at both ends in circumferential direction, so as to be opposed to each other; two parallel straight portions disposed so that a widthwise direction distance therebetween is longer than a width of the arc portion; and inclined portions for connecting the arc portions and the parallel straight portions to each other.

Abstract: There is provided a piston ring which can effectively prevent aluminum adhesion phenomenon to the piston ring. The piston ring includes a piston ring main body and a surface coating film on either upper or lower surface of the piston ring main body, or both the upper and lower surfaces of the piston ring. The surface coating film includes heat-resistant resin and copper based powder contained therein.

Abstract: A piston ring includes a piston ring body and a surface coating film formed on at least one of upper and lower surfaces of the piston ring body. The surface coating film comprises a heat-resistant resin and a metal powder contained in the heat-resistant resin, and a phosphate coating film is formed, as base coating film of the surface coating film, on a surface on which the surface coating film of the piston ring body is formed.

Abstract: A piston ring includes a piston ring body and a surface coating film formed on at least one of upper and lower surfaces of the piston ring body. The surface coating film has a most outside surface layer including a heat-resistant resin and a metal powder contained in the heat-resistant resin and a base bottom layer formed nearest the piston ring body and including a heat-resistant resin. The base bottom layer may also include a metal powder.

Abstract: A combination of a cylinder liner and a piston ring, wherein the cylinder liner includes, silicon: 23.0-28.0% by weight, magnesium: 0.80-2.0% by weight, copper: 3.0-4.5% by weight, iron: 0.25% by weight or less, nickel: 0.01% by weight or less, wherein surface roughness profile of the inner circumference surface has Rz=0.5 to 1.0 ?m, Rk=0.2 to 0.4 ?m, Rpk=0.05 to 0.1 ?m, Rvk=0.08 to 0.2 ?m, wherein the piston ring includes carbon: 0.6-0.7% by weight, chrome: 13-14% by weight, molybdenum: 0.2-0.4% by weight, silicon: 0.25-0.50% by weight, manganese: 0.2-0.5% by weight, and wherein carbides with the diameter of 5.0 ?m and less are 4-10%.

Abstract: A generally circular compression piston ring having an outer peripheral surface, an inner peripheral surface, and a pair of end faces splitting the circular shape in a radial direction thereof for defining a gap portion. The ring has a first portion including a notched portion formed at the inner peripheral surface and extending over a predetermined circumferential length portion starting from the end face, and a second portion other than the first portion. The second portion has a radial thickness ranging from 2.0 mm to 6.0 mm. The notched portion is a plane shape gradually reaching the outer peripheral surface toward the end face. The end face has a radial thickness ranging from 0.2 times to less than 0.5 times as large as the radial thickness of the second portion. The outer peripheral surface defines a center serving as a center of a center angle, and the predetermined circumferential length portion is defined by the center angle ranging from 26.5 degrees to 14 degrees.

Abstract: A three-piece oil ring and a combination of the three-piece oil ring and a piston, those capable of realizing improved sealing property and reduction in lubrication oil consumption with avoiding generation of sticking even at low tension and thin width of the ring. The three-piece oil ring includes a spacer expander 10 and two side rails. The spacer expander has a radially inner end portion provided with seating tabs 13 protruding in an axial direction and having radially outer inclined surfaces for urging inner peripheral surfaces of the first and second side rails. The spacer expander has a radially outer end portion provided with side rail support portions 14 projecting in the axial direction for supporting axial end faces of the first and second side rails. A seating tab angle of the outer inclined surface relative to an axis is in a range of 10 to 20 degrees, and a ratio of 2X/Y is in a range of from 0.04 to 0.

Abstract: It is a main object of the present invention to provide an oil ring which is capable of reducing sliding friction even in a high speed revolution region of a piston, and capable of reducing the consumption of oil.

Abstract: The disclosed is a combination of a cylinder liner and a piston ring which contacts to a inner circumference surface of the cylinder liner at the pressure of 0.03 to 0.2 MPa, wherein the composition of the cylinder liner includes, silicon: 23.0 to 28.0% by weight, magnesium: 0.80 to 2.0% by weight, copper: 3.0 to 4.5% by weight, iron: 0.25% by weight or less, nickel: 0.01% by weight or less, and the rest: unavoidable impurities and aluminum, and wherein surface roughness profile of the inner circumference surface has Rz 0.5 to 1.0 ?m, Rk=0.2 to 0.4 ?m, Rpk=0.05 to 0.1 ?m, Rvk=0.08 to 0.2 ?m, meanwhile, wherein the composition of a piston ring includes carbon: 0.6 to 0.7% by weight, chrome: 13 to 14% by weight, molybdenum: 0.2 to 0.4% by weight, silicon: 0.25 to 0.50% by weight, manganese: 0.2 to 0.5% by weight, and the rest: unavoidable impurities and iron, and wherein carbides with the diameter of 5.

Abstract: A piston for an internal-combustion engine includes a through-hole communicating with the inner space of the piston formed in an oil-ring groove into which an oil ring is fitted and a through-hole connected with a second-ring groove, the through-hole having an opening spreading from the lower portion of the bottom of the second-ring groove in a top-to-bottom direction of the piston to the lower surface of the second-ring groove and linearly extending to the inner space of the piston; and a combination of the piston and piston rings of the three-ring type for an internal-combustion engine, the end gaps of compression rings among the piston rings being set in a predetermined range.