Honda Motor Co., Ltd.

Masakazu Hoshino

Ryo Hatae

Nozomi Okada

Kohei Omori

An internal combustion engine includes: a crankshaft supported via a bearing; a balancer drive gear; a balancer shaft; and a one-way clutch mechanism that transmits to the crankshaft a drive force to start the internal combustion engine. In the internal combustion engine, the bearing includes an oil seal built therein, the oil seal sealing a crank chamber of the crankcase. The one-way clutch mechanism includes a case fixed to the crankshaft and a starter driven gear provided relatively rotatably with respect to the case and driven by the drive force. The starter driven gear includes a thrust bearing portion that abuts on the balancer drive gear in an axial direction of the crankshaft.

Internal combustion engine

A technique for making air less likely to enter a strainer in an internal combustion engine in which the strainer is supported by a drain bolt. In an internal combustion engine in which a drain bolt supports a strainer and is configured to discharge a drain is attached to a bottom of a sump. A drain hole into which the drain bolt is screwed and a strainer hole are arranged coaxially. A crankcase is provided with an oil passage through which oil is returned to the sump. The oil passage includes a first passage through which the oil flows in a direction away from the strainer, a return passage that turns around from a forefront end of the first passage, and a second passage through which the oil flows from a forefront end of the return passage toward the strainer.

A piston structure for a four-stroke internal combustion engine is provided, enabling an increase in the intake efficiency and a favorable ignitability to improve the performance of the internal combustion engine. In a piston structure for a four-valve four-stroke internal combustion engine, a piston crown includes: an intake-side inclined flat surface formed in a single plane by bottom surfaces of a pair of intake valve recesses and an intake-side common flat surface; and an exhaust-side inclined flat surface formed in a single plane by bottom surfaces of a pair of exhaust valve recesses and an exhaust-side common flat surface. The intake-side inclined flat surface and the exhaust-side inclined flat surface are formed into a pent-roof shape with a ridge line at an intersection therebetween. The exhaust-side inclined flat surface extends into the intake valve recesses, and the ridge line is located on a side of the intake valve recesses.

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Wako, Japan

Masakazu Hoshino