Mazda Motor Corporation

Ryota Joya

Taku Kuramashi

Tomonori Nishida

A multi-cylinder engine exhaust structure disclosed herein includes: four branched exhaust pipes respectively communicating with four cylinders classified into two groups, each being comprised of two of the four cylinders with discontinuous exhaust strokes; two intermediate collecting pipes, each being formed by combining associated two of the four branched exhaust pipes respectively communicating with the two cylinders in an associated one of the two groups; a last collecting pipe formed by combining these intermediate collecting pipes; and an exhaust gas purifier coupled to an exhaust gas downstream end of the last collecting pipe. Two of the four branched exhaust pipes respectively communicating with two of the four cylinders to be activated as two active cylinders while the engine is performing a cylinder-cutoff operation are shorter than the two other branched exhaust pipes respectively communicating with the two other cylinders to be deactivated as two idle cylinders during the cylinder-cutoff operation.

Exhaust structure for multi-cylinder engine

An exhaust pipe structure is the exhaust pipe structure with a catalyst converter provided immediately close to an engine and includes a plurality of exhaust passages and a collecting portion. The collecting portion arranged between the first exhaust passage provided at an end side and a second exhaust passage includes a first guiding portion, a second guiding portion, and a rotating/guiding portion. The exhaust gas introduced from the first exhaust passage and the exhaust gas introduced from the second exhaust passage are guided obliquely downward by the first guiding portion and the second guiding portion, respectively, and are then rotated and guided by the rotating/guiding portion in respective directions opposite to each other to flow toward the catalyst converter.

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Hiroshima, Japan

Ryota Joya