Yamaha Hatsudoki Kabushiki Kaisha

Tatsuya Aoyama

Yuta Shimizu

Ryo Tomii

Hisatoshi Kinoshita

Kazuteru Iwamoto

Tatsuya Kasahara

Atsuya Hidai

Atsushi Hirano

Katsuhisa Abe

An engine unit, including: a plurality of cylinders respectively cooperating with a plurality of pistons; a plurality of individual exhaust pipes configured to allow exhaust gases from the plurality of cylinders to respectively flow therethrough; an exhaust manifold, including a merge portion into which the individual exhaust pipes merge, and a catalyst disposed downstream thereof; a group of pre-catalyst oxygen sensors disposed between the cylinders and the catalyst for all paths of the exhaust gases flowing into the catalyst from the plurality of cylinders; a post-catalyst oxygen sensor disposed in the exhaust manifold, downstream of the catalyst in the flow direction of the exhaust gas; and a control device configured to detect a cylinder-to-cylinder imbalance in air-fuel ratio between the plurality of cylinders, and a deterioration of the catalyst, using detection results of pre-catalyst and post-catalyst oxygen sensors without using an air-fuel ratio sensor.

Individual throttle-type or unequal interval combustion-type multi-cylinder engine unit

A catalyst deterioration determining device for use in a straddled vehicle having an engine, a transmission that transmits motive power of an engine, and a catalyst that cleans an exhaust gas from the engine. The catalyst deterioration determining device includes a running state acquirer that acquires a plurality of running states, a state determiner that stores a plurality of allowable conditions, each of which is a condition for determining work in regard to a degradation state of the catalyst to be executed and is based on a relationship among a plurality of gear ratios of the transmission, an intake state of the engine and a rotation speed of the engine, and determines whether the plurality of running states acquired by the running state acquirer satisfy the plurality of allowable conditions, and a determination executor that executes the determining work based on a result of the determination by the state determiner.

Catalyst degradation determining device for straddled vehicle and straddled vehicle including same

A catalyst degradation determining device for a straddled vehicle that includes an engine, a catalyst for cleaning an exhaust gas from the engine, and a throttle valve that is controllable by cruise control of the straddled vehicle to keep a traveling speed of the straddled vehicle constant. The catalyst degradation determining device includes a determiner that determines whether the cruise control is being executed, and an execution controller. The execution controller is configured to determine a degradation state of the catalyst while controlling an air-fuel mixture supplied through the throttle valve to the engine, in a case where the determiner determines that the cruise control is not being executed, and at least one running state of the straddled vehicle satisfies at least one predetermined allowable condition, and not to determine the degradation state of the catalyst in a case where the determiner determines that the cruise control is being executed.

Growing community of inventors

Shizuoka, Japan

Tatsuya Aoyama