Mazda Motor Corporation

Kolbenschmidt K. K.

Hiroaki Muranaka

Shuma Aoki

Naohiro Yamaguchi

Yoshitaka Wada

Masaki Fukuma

Masanori Hashimoto

Hiroshi Hosokawa

Hisashi Okazawa

Shuji Takuma

Daisuke Tabata

Daisuke Matsumoto

Kimio Ishida

Hiroyuki Takeshige

Masaki Takahara

Sho Ishigaki

Kazuyuki Teshima

Yoshikazu Nishiyama

In a spark-ignition internal combustion engine in which a protrusion including an intake-side inclined surface and an exhaust-side inclined surface is formed on a top surface of a piston, and a cavity is formed in the protrusion at a position associated with a spark plug. The cavity includes a bottom surface and a tubular peripheral surface, and is formed in such a way that a ratio of a depth of the cavity with respect to a diameter of the cavity is 0.3 or smaller.

Spark-ignition internal combustion engine

In a spark-ignition internal combustion engine in which a protrusion including an intake-side inclined surface and an exhaust-side inclined surface is formed on a top surface of a piston, and a cavity is formed in the protrusion at a position associated with a spark plug, the intake-side inclined surface and the exhaust-side inclined surface are formed in such a way that an inclination angle of the exhaust-side inclined surface is smaller than an inclination angle of the intake-side inclined surface, and a difference in inclination angle between the intake-side inclined surface and the exhaust-side inclined surface is 4 degrees or larger.

In a spark-ignition internal combustion engine in which a protrusion including an intake-side inclined surface and an exhaust-side inclined surface is formed on a top surface of a piston, and a cavity is formed in the protrusion at a position associated with a spark plug, the intake-side inclined surface and the exhaust-side inclined surface are formed in such a way that a ratio of a length of the exhaust-side inclined surface with respect to a length of the intake-side inclined surface is 1.25 or larger in a cross section passing through a center axis of the piston and orthogonal to an axis direction of a crankshaft.

A cooling structure of a multi-cylinder engine is provided, which includes cylinder bores formed in a cylinder block, a water jacket surrounding the bores, a cylinder head, and a water jacket spacer accommodated in the water jacket and having a peripheral wall formed corresponding to the cylinder bores. A length of the peripheral wall in cylinder bore axial directions is substantially the same as that of the water jacket. The peripheral wall forms, inside the water jacket, inner and outer channels, and a width of the inner channel is less than that of the outer channel. Communicating holes communicating the inner and outer channels are formed in the peripheral wall at locations between adjacent cylinder bores, respectively. Inter-bore channels into which some cooling fluid flowing from the outer channel into the inner channel flows are provided to parts of the cylinder block between the adjacent cylinder bores, respectively.

Cooling structure of multi-cylinder engine

An oil supply system for an engine is provided, which includes an oil pressure controller for controlling a variable displacement oil pump to adjust a discharge pressure thereof to reach a target oil pressure corresponding to an operating state of the engine, the variable displacement oil pump capable of adjusting a discharge amount of oil, a load detector for detecting an engine load, and an oil temperature detector for detecting an oil temperature. When the engine load is low, to increase an amount of oil mist flowing inside a crank case of the engine, the oil pressure controller controls the variable displacement oil pump to increase the discharge amount as the oil temperature becomes lower, the oil mist generated by the oil flowing out of a bearing part rotatably supporting at least a crankshaft and being atomized, the engine load being considered low when below a predetermined reference load.

Oil supply system for engine

An oil ring to be attached to a ring groove of a piston for an engine is provided. The oil ring includes two annular ring bodies having a common axis and arranged in tandem, and an expander for biasing the ring bodies radially outward. A sliding surface is formed at an outer circumference of each ring body to bulge radially outward and slides on a cylinder inner circumferential surface. The sliding surface of one of the ring bodies has a tip portion and first and second curved surfaces. In cross sections of the first and second curved surfaces, the first and second curved surfaces are connected while tangent lines to the cross sections at the tip portion align with each other, and when positional change rates are compared between points on the first and second curved surfaces, a change rate of the first curved surface is lower.

Oil ring

The present invention provides a piston for a spark-ignition engine, comprising: a land part, an upper surface part of which has a crown partforming a combustion chamber; a pair of skirt partsextending downward from a peripheral part of the land partand facing each other in a radial direction thereof; a pair of sidewall partscoupling side end parts of the pair of skirt partsto each other; and a pin boss partthat is formed in each of the sidewall parts. The present invention can inhibit the generation of HC produced at the time of combustion, while thermally protecting a top ringfitted into a top ring grooveon an outer circumferential surface of the land part. The crown partis configured by a flat base surfaceand a bulging partbulging upward above the base surface, and a thinned partprovided in the land partis formed deep such that the deepest part thereof is positioned inside the bulging part

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Higashihiroshima, Japan

Hiroaki Muranaka