Abstract: A core of a fast reactor including a sodium plenum installed above a core fuel, which is capable of reliably reducing a void reactivity, and an operation method thereof are provided. The core of a fast reactor including the sodium plenum installed above the core fuel is characterized in that a tip of a primary control rod is inserted into a core fuel region, and a tip of a backup control rod is arranged above an upper end of the core fuel region for operation.

Abstract: A power converter includes first and second components on which male and female fitting members of each of a plurality of pairs of fitting members are arranged, with a pair of first alignment keys formed in the first and second components as reference positions. The first and second components are coupled to each other by the female fitting member clamping an insertion portion of the male fitting member inserted between first and second clamping portions of the female fitting member arranged so as to face each other in a state where the pair of first alignment keys are positionally aligned. The first and second clamping portions are each bent so as to form one of protrusions toward one of surfaces thereof facing each other. A gap is formed in a distal end portion of each of the first and second clamping portions.

Abstract: An electric power converter includes a first board, a second board, and a first board-to-board connector that electrically and mechanically connects the first board and the second board. The first board-to-board connector includes a male fitting member and a female fitting member. Each of a first clamp portion and a second clamp portion of the female fitting member includes a first contact forming portion and a second contact forming portion that are curved in a protruding shape, and a first spring portion and a second spring portion that are connected to the first contact forming portion and the second contact portion, respectively, and that are curved in corrugated shapes. An insert clamped between the first contact forming portion and the second contact forming portion forms an electrical contact, and the first spring portion and the second spring portion are independently deformable.

Abstract: A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.

Abstract: A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.

Abstract: A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.

Abstract: There is provided a highly heat conductive piston ring for an internal combustion engine capable of exhibiting a gas seal function and a heat transfer function for a long period of time in a stable manner when used in an automobile gasoline engine having a high compression ratio. The highly heat conductive piston ring for an internal combustion engine is a piston ring for an internal combustion engine having an Mn—Cr steel as a base material, the Mn—Cr steel including C in the range of from 0.52 to 0.65 mass %, Si in the range of from 0.15 to 0.35 mass %, Mn in the range of from 0.60 to 1.00 mass %, Cr in the range of from 0.60 to 1.00 mass %, P in the range of 0.04 mass % or less, S in the range of 0.04 mass % or less, a slight amount of components (total content of Al, Ni, and Cu) in the range of from 0.05 to 3.0 mass %, and a remnant being Fe and unavoidable impurities.

Abstract: A multi-piece oil ring includes an oil ring main member in which two rails are connected together by a columnar part and which has a roughly I-shaped cross section; and a coil expander disposed in an inner circumferential groove formed on the inner circumferential surface of the columnar. Each rail in the oil ring main member possesses a sliding section protuberance whose tip possesses a jutting portion. The axial length of the jutting portion is 0.02-0.18 mm. The change rate of the axial length of the individual jutting portion is in the range of 0 to 80% at least in a region of from its sliding surface to be faced to a cylinder, which is positioned at the tip of the jutting portion, to a position of 0.03 mm away from the aforementioned sliding surface in the radial direction of the oil ring main member.

Abstract: A multi-piece oil ring includes an oil ring main member in which two rails are connected together by a columnar part and which has a roughly I-shaped cross section; and a coil expander disposed in an inner circumferential groove formed on the inner circumferential surface of the columnar. Each rail in the oil ring main member possesses a sliding section protuberance whose tip possesses a jutting portion. The axial length of the jutting portion is 0.02-0.18 mm. The change rate of the axial length of the individual jutting portion is in the range of 0 to 80% at least in a region of from its sliding surface to be faced to a cylinder, which is positioned at the tip of the jutting portion, to a position of 0.03 mm away from the aforementioned sliding surface in the radial direction of the oil ring main member.

Abstract: A multi-piece oil ring includes an oil ring main member in which two rails are connected together by a columnar part and which has a roughly I-shaped cross section; and a coil expander disposed in an inner circumferential groove formed on the inner circumferential surface of the columnar. Each rail in the oil ring main member possesses a sliding section protuberance whose tip possesses a jutting portion. The axial length of the jutting portion is 0.02-0.18 mm. The change rate of the axial length of the individual jutting portion is in the range of 0 to 80% at least in a region of from its sliding surface to be faced to a cylinder, which is positioned at the tip of the jutting portion, to a position of 0.03 mm away from the aforementioned sliding surface in the radial direction of the oil ring main member.

Abstract: A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.

Abstract: The second compression ring is formed such that the outer peripheral surface shape has a tapered face, and the radial cross-sectional shape is a rectangular ring, a scraper ring, or a Napier ring, and has a piston ring base and a hard film provided at least on an outer peripheral sliding surface thereof. The piston ring base is composed of a low-alloy steel or carbon steel having a Vickers hardness of Hv 350 Hv 550. The outer peripheral sliding surface is formed so that the axial length is from 0.01 to 0.30 mm between the outer edge end part of the tapered outer peripheral sliding surface and an imaginary line contacting with a lower end surface where a curved surface having a diameter that decreases gradually inward from the outer edge end part toward the lower end in the axial direction is parallel to a ring underside.

Abstract: There is provided a highly heat conductive piston ring for an internal combustion engine capable of exhibiting a gas seal function and a heat transfer function for a long period of time in a stable manner when used in an automobile gasoline engine having a high compression ratio. The highly heat conductive piston ring for an internal combustion engine is a piston ring for an internal combustion engine having an Mn—Cr steel as a base material, the Mn—Cr steel including C in the range of from 0.52 to 0.65 mass %, Si in the range of from 0.15 to 0.35 mass %, Mn in the range of from 0.60 to 1.00 mass %, Cr in the range of from 0.60 to 1.00 mass %, P in the range of 0.04 mass % or less, S in the range of 0.04 mass % or less, a slight amount of components (total content of Al, Ni, and Cu) in the range of from 0.05 to 3.0 mass %, and a remnant being Fe and unavoidable impurities.

Abstract: A rotation-transmitting mechanism capable of obtaining a high deceleration ratio in a small number of stages, and a conveying apparatus and driving apparatus using the rotation-transmitting mechanism are provided. In one form, a rotation-transmitting mechanism includes an inner rotating body and an outer rotating body arranged coaxially with the inner rotating body. Further, the rotation-transmitting mechanism includes a driving rotating body and rotating body arranged on an input side (lower stage), and two planetary rotating bodies arranged on an output side (upper stage). When the driving rotating body is rotated by a motor on the input side, the two planetary rotating bodies revolve around the inner rotating body while rotating on the output side. At this time, the planetary rotating bodies revolve very slowly around the inner rotating body.

Abstract: The present invention provides a steel part for machine structural use whose fatigue strength and toughness are improved and a manufacturing method thereof. A steel part made of a steel containing, in mass %, C: 0.05 to 0.20%, Si: 0.10 to 1.00%, Mn: 0.75 to 3.00%, P: 0.001 to 0.050%, S: 0.001 to 0.200%, V: exceeding 0.20 to 0.25%, Cr: 0.01 to 1.00%, Al: 0.001 to 0.500%, and N: 0.0080 to 0.0200%, and a balance being composed of Fe and inevitable impurities, in which a steel structure contains a bainite structure having an area ratio of 95% or more, a bainite lath width is 5 ?m or less, V carbide having an average grain diameter of not less than 4 nm nor more than 7 nm dispersedly exists in the bainite structure, and an area ratio of V carbide in the bainite structure is 0.18% or more.

Abstract: The second compression ring is formed such that the outer peripheral surface shape has a tapered face, and the radial cross-sectional shape is a rectangular ring, a scraper ring, or a Napier ring, and has a piston ring base and a hard film provided at least on an outer peripheral sliding surface thereof. The piston ring base is composed of a low-alloy steel or carbon steel having a Vickers hardness of Hv 350 Hv 550. The outer peripheral sliding surface is formed so that the axial length is from 0.01 to 0.30 mm between the outer edge end part of the tapered outer peripheral sliding surface and an imaginary line contacting with a lower end surface where a curved surface having a diameter that decreases gradually inward from the outer edge end part toward the lower end in the axial direction is parallel to a ring underside.

Abstract: A high-quality internal combustion engine oil ring which stably keeps oil consumption low for a long period and in which the shapes of an upper rail and a lower rail can be formed at low cost with high accuracy. The internal combustion engine oil ring has a recessed stepped portion formed at a corner of a sliding surface of an outer peripheral sliding projection in sliding contact with a cylinder inner wall surface of at least one of a first rail and a second rail constituting an oil ring main body, in a shape in vertical cross-section along a sliding direction of the first rail and second rail, and a wall surface of the recessed stepped portion has an arcuate surface having a radius of curvature of 0.02 mm to 0.08 mm.

Abstract: The second compression ring is formed such that the outer peripheral surface shape has a tapered face, and the radial cross-sectional shape is a rectangular ring, a scraper ring, or a Napier ring, and has a piston ring base and a hard film provided at least on an outer peripheral sliding surface thereof. The piston ring base is composed of a low-alloy steel or carbon steel having a Vickers hardness of Hv 350 Hv 550. The outer peripheral sliding surface is formed so that the axial length is from 0.01 to 0.30 mm between the outer edge end part of the tapered outer peripheral sliding surface and an imaginary line contacting with a lower end surface where a curved surface having a diameter that decreases gradually inward from the outer edge end part toward the lower end in the axial direction is parallel to a ring underside.

Abstract: The present invention provides a steel part for machine structural use whose fatigue strength and toughness are improved and a manufacturing method thereof. A steel part made of a steel containing, in mass %, C: 0.05 to 0.20%, Si: 0.10 to 1.00%, Mn: 0.75 to 3.00%, P: 0.001 to 0.050%, S: 0.001 to 0.200%, V: exceeding 0.20 to 0.25%, Cr: 0.01 to 1.00%, Al: 0.001 to 0.500%, and N: 0.0080 to 0.0200%, and a balance being composed of Fe and inevitable impurities, in which a steel structure contains a bainite structure having an area ratio of 95% or more, a bainite lath width is 5 ?m or less, V carbide having an average grain diameter of not less than 4 nm nor more than 7 nm dispersedly exists in the bainite structure, and an area ratio of V carbide in the bainite structure is 0.18% or more.

Abstract: A high-quality internal combustion engine oil ring which stably keeps oil consumption low for a long period and in which the shapes of an upper rail and a lower rail can be formed at low cost with high accuracy. The internal combustion engine oil ring has a recessed stepped portion formed at a corner of a sliding surface of an outer peripheral sliding projection in sliding contact with a cylinder inner wall surface of at least one of a first rail and a second rail constituting an oil ring main body, in a shape in vertical cross-section along a sliding direction of the first rail and second rail, and a wall surface of the recessed stepped portion has an arcuate surface having a radius of curvature of 0.02 mm to 0.08 mm.