Yamaha Hatsudoki Kabushiki Kaisha

Atsushi Hirano

Hisatoshi Kinoshita

Kazuteru Iwamoto

Atsuya Hidai

Tatsuya Kasahara

Yuta Shimizu

Tatsuya Aoyama

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 straddled vehicle on which a part used for performing an inspection for a leak of gas from an evaporative emission system is mounted such that a weight balance of the straddled vehicle is maintained and mass concentrates includes a canister-integrated-leak-detection device that detects a leak of gas from an evaporative emission system. The canister-integrated-leak-detection device configured in a state where at least one of a vent valve or a suction pump is integrated with a canister is supported via a common attaching member to intersect with at least one of a virtual-left-right-center plane that includes a center in a left-right direction and is perpendicular to the left-right direction, a virtual-front-rear-center plane that includes a center in a front-rear direction and is perpendicular to the front-rear direction, or a virtual-up-down-center plane that includes a center in an up-down direction and is perpendicular to the up-down direction in the vehicle.

Straddled vehicle

A vehicle includes at least one of an electric vent valve configured to open and close an outside-air-introduction passage of a canister or an electric suction pump configured to suck gas in a gas passage through which the gas flows. The canister and at least one of the vent valve or the suction pump are disposed such that at least one of a virtual-left-right-center plane that includes a center in a left-right direction and is perpendicular to the left-right direction, a virtual-front-rear-center plane that includes a center in a front-rear direction and is perpendicular to the front-rear direction, or a virtual-up-down-center plane that includes a center in an up-down direction and is perpendicular to the up-down direction is located between a gravity center of the canister and at least one of a gravity center of the vent valve or a gravity center of the suction pump.

A vehicle includes a frame, a seat, a storage box, an engine body at least partially overlapping with the seat when seen from above, an intake system component, a fuel system component, an evaporative emission system, a pressure sensor, and at least one of an electric vent valve or an electric suction pump. At least one of the pressure sensor, the vent valve, or the suction pump is supported by at least one of a frame, a storage box, an engine body, an intake system component, or a fuel system component.

A gas-leak-detection device for detecting a gas leakage from an evaporative emission system includes an electric-wire-connection portion and a passage connection portion that are disposed to overlap with at least one of appearance components in a vehicle when the vehicle is seen in a viewing direction, and are disposed closer to the at least one appearance component than a center plane perpendicular to the viewing direction when the vehicle is in an upright state, the center plane being one of an imaginary-lateral-center plane that is an imaginary vertical plane perpendicular to the left-right direction, an imaginary-longitudinal-center plane that is an imaginary vertical plane including a center in the front-rear direction and being perpendicular to the front-rear direction, or an imaginary-vertical-center plane that is an imaginary horizontal plane including a center in the top-bottom direction and being perpendicular to the top-bottom direction.

Growing community of inventors

Shizuoka, Japan

Atsushi Hirano