Mazda Motor Corporation

Arata Matsue

Yasushi Inoue

Masako Shinohara

Takashi Ohtsuru

Takeshi Kageyama

Takashi Mitsuhara

A cylinder block for a multi-cylinder engine is provided with a water jacket partly on an intake side of a row of cylinders and partly on an exhaust side of the row of cylinders and a water guide passage through which cooling water is introduced into the water jacket. The cylinder block is provided with oil return passages each of which extends straight from top to bottom of the cylinder block between each adjacent cylinders. A branch oil return passage branches off from a middle portion of the rearmost oil return passage and extends rearward up. A generally triangular director pillar having a bolt hole, that is defined by first to third side walls, is disposed with the first side wall adjacent to a foremost cylinder placed approximately perpendicularly to a line passing center axes of the foremost cylinder and the bolt hole, an edge line facing the first wall placed in an interface between the water jacket and the water guide passage and the second and third side walls placed so as to direct a cooling water stream partly to the water jacket on the intake side and partly to the water jacket on the exhaust side, respectively.

Engine block structure for reciprocating engine

A cylinder block reinforcement construction for an engine includes a reinforcement member fixed to a skirt portion of a cylinder block of the half-skirt type and fastened to each of bearing caps bearing the crankshaft of the engine. The reinforcement member is formed in a platelike configuration and a substantially dishlike sectional shape and includes a bottom face portion, side face portions rising from both side ends of the bottom face portion, and flange portions provided at upper edges of the side face portions so as to be fastened to the skirt portion. The reinforcement member is provided, at positions corresponding to respective of the bearing caps and spaced in the axial direction of the crankshaft, with protuberant portions for attachment to respective of the bearing caps. The bottom face portion may be provided with bottom vent holes, each being provided between adjacent of the protuberant portions at a position corresponding to the respective cylinder. The area of each bottom hole at a location where the piston disposed directly thereabove is accompanied by an adjacent piston reciprocated in phase therewith is greater than the area of bottom holes at other locations.

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Hiroshima, Japan

Arata Matsue