Nippon Piston Ring Co., Ltd.

Honda Motor Co., Ltd.

Atsushi Chiba

Kazuhiro Fujimura

Iwao Hiraishi

Makoto Kajiwara

Naoyuki Akimoto

Dai Arai

Takashi Tetsuka

Takashi Hotei

Hiroyuki Sugiura

Katsuaki Ogawa

Masazumi Naito

Tensei Hayashi

Kazuhiro Sameshima

Michihiro Ito

Kenichi Tamura

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.

Method for producing piston ring with recess

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.

Multi-piece oil ring

A power unit having a crankcase and peripheral devices wherein a driving source for a gear shifting device is disposed so as to be displaced below the crankcase. An engine includes a gear speed change mechanism having a plurality of gear pairs for changing the speed of a rotational force of a crankshaft. A gear shifting device includes at least a plate-shaped shift arm rocking about a shift spindle to perform a gear pair changing operation on the gear speed change mechanism. A crankcase houses the gear speed change mechanism and the gear shifting device with an oil pan attached to a lower portion of the crankcase. A communicating hole communicating with the oil pan is formed in a bottom portion of the crankcase with the bottom portion being located below the shift arm, and a rocking range of the shift arm partly overlaps the communicating hole.

Power unit

A shift position detecting device where a shift position determining member is provided for determining a shift position based on a combination of switching modes of three switches corresponding to at least one of a plurality of projection rows each having a plurality of projection portions in a one-by-one basis, and '1, 1, 1' indicative of an ON state of each switch is allocated as a detection logic at a neutral position arranged between a first speed position and a second speed position, wherein a change in friction at the time of a shift operational to the neutral position is alleviated thus giving an operational feeling with no discomfort to a rider. Two projection rows that are objects to be detected by two specified switches among the three switches are formed so as to change switching modes of the specified switches from an OFF state to an ON state.

Shift position detecting device

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.

Piston ring

Provided is a piston ring such that it is possible to sufficiently inhibit adhesive wear when the piston ring is mounted to a piston for a diesel engine in which at least the piston ring groove in the piston is formed from steel or cast iron. Disclosed is a piston ring mounted to a piston for a diesel engine, wherein the load length ratio (Rmr2) (in accordance with JIS B0601:2001) of the top surface and bottom surface of the piston ring satisfies each of the following conditions: Rmr2 (0.5%, 0.3[mu]m)=20% and Rmr2 (0.5%, 0.4[mu]m)=40%.

A shift position detecting device that determines a shift position based on a detection logic formed of a combination of turning on or off of a plurality of switches that are fixedly arranged at least one by one at positions corresponding to a plurality of detecting object portion rows mounted on a shift drum. An accurate shift position can be detected even if there is an irregularity in switching timings of switching modes of the plurality of switches. A shift position detecting member establishes the shift position as a new shift position and outputs shift position information, while when the detection logic after the transition is a detection logic other than the detection logic corresponding to the changeable shift position, sets the new shift position not yet established and outputs information corresponding to non-establishment of the shift position.

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.

Growing community of inventors

Saitama, Japan

Atsushi Chiba