Yamaha Hatsudoki Kabushiki Kaisha

Masaki Torigoshi

Hisatoshi Kinoshita

Yoshihiko Moriya

Makoto Kuroiwa

Hayatoshi Sato

Naoki Makita

Yuuji Araki

Ryusuke Kato

Yoshitaka Momiyama

Hiroki Tanabe

Toshihiko Takahashi

Hitoshi Takikawa

Akira Ishizaki

Naoto Tajima

Masahiko Ito

A straddled vehicle including a vehicle body frame, an engine unit, and at least one front wheel. The engine unit includes a turbocharger, and an engine body including a cylinder head and a cylinder head cover. The cylinder head cover is fixed to a first surface of the cylinder head. The turbocharger is fixed to a second surface of the cylinder head, a surface of the turbocharger through which the turbocharger is fixed to the cylinder head being a third surface. When the vehicle body frame is in an upright state, a turbocharger rotation axis, the second and third surfaces are positioned above a first horizontal plane in which the front axle lies, above a second horizontal plane in which the crankshaft axis lies, and below a third horizontal plane in which a front end of the first surface lies, in the upward-downward direction of the straddled vehicle.

Straddled vehicle

A straddled vehicle having an engine unit. The engine unit includes an engine body having a cylinder axis tilting forward, a radiator including a radiator core, a turbocharger including a turbine wheel and a compressor wheel, and an intercooler including an intercooler core. In a side view, at least a part of the intercooler core, a part of the turbine wheel and a part of the radiator core are within an area enclosed by a first connecting line, a second connecting line, an engine-body front-surface and a wheel rear-surface. In an upward-downward or forward-backward direction of the cylinder axis, the intercooler-core upper end is more upward than the turbine-wheel upper end, the intercooler-core front end is more frontward than the turbine-wheel front end, the intercooler-core lower end is more upward than the radiator-core upper end, and the radiator-core rear end is more frontward than both the turbine-wheel rear end and the intercooler-core rear end.

A straddled vehicle having an engine unit supported by a vehicle body frame. The engine unit includes an engine body, a turbocharger, and an exhaust device. The exhaust device includes an exhaust pipe and a muffler that are connected to each other to form a portion of an exhaust passage, to allow the exhaust gas passed through the turbocharger to pass therethrough, and a first catalyst and a second catalyst that are arranged in this order along a direction in which the exhaust gas flows through the exhaust pipe. The exhaust pipe has an upstream end thereof connected to the turbocharger, a downstream end thereof connected to the muffler, and a corner section that is bent in at least a part thereof between a downstream end of the first catalyst and an upstream end of the second catalyst, the catalysts not being arranged in the corner section.

In a vehicle, a rod of a waste gate valve actuator reciprocates along a virtual plane which is parallel to both the central axis of a connecting shaft of a turbocharger and the cylinder axis of a cylinder hole. When viewed in the left or right direction of the vehicle, a main catalyst of a catalyst portion is provided forward of the cylinder axis of the cylinder hole. The flow direction of the exhaust gas in the main catalyst intersects with the reciprocating direction of the rod of the waste gate valve actuator when viewed in a direction orthogonal to both the central axis of the connecting shaft of the turbocharger and the central axis of the cylinder hole.

An engine includes a cylinder, an exhaust port, an exhaust valve, a secondary air supply pipe, and an electromagnetic valve. The electromagnetic valve is opened in a predetermined time period after a point in time when a lift amount of the exhaust valve reaches about half a maximum value during a time period in which an opening of the exhaust port is opened. This causes air to be supplied from a secondary air supply pipe to the exhaust port.

Engine and vehicle

A secondary air supply system includes a CPU, a first air supply pipe, a second air supply pipe, a first shut-off valve, and a second shut-off valve. First ends of the first air supply pipe and the second air supply pipe are connected to an air cleaner box and the other ends thereof are connected to an exhaust port. The CPU controls opening/closing of the first shut-off valve and the second shut-off valve based on a state of an engine. The first shut-off valve and the second shut-off valve are selectively opened by the CPU, so that air in the air cleaner box is supplied to the exhaust port through the first air supply pipe and/or the second air supply pipe.

Secondary air supply system and vehicle

A secondary air supply system includes a CPU, a ROM, an air supply pipe, and an air amount adjusting valve. One end of the air supply pipe is connected to an air cleaner box and the other end is connected to an exhaust port. Secondary air in the air cleaner box is supplied to the exhaust port through the air supply pipe. An amount of the secondary air to be supplied from the air supply pipe to the exhaust port is adjusted by the air amount adjusting valve. A target air-fuel ratio depending on a state of the engine is stored in the ROM. The CPU controls the air amount adjusting valve based on the state of the engine so that an air-fuel ratio in the exhaust port is the target air-fuel ratio.

In an exhaust system, a first oxygen sensor is attached to an exhaust pipe connected to a standard cylinder in which the amount of injected fuel is the closest to the average of the amounts of fuel injected in a plurality of cylinders. A controller calculates the air-fuel ratio of the standard cylinder based on the value detected by the first oxygen sensor. Then, based on the difference between the calculated air-fuel ratio of the standard cylinder and a predetermined target air-fuel ratio, the amount of correction to the amount of fuel injected in the standard cylinder is determined such that the air-fuel ratio of the standard cylinder is equal to the target air-fuel ratio. Furthermore, based on the amount of correction to the amount of fuel injected in the standard cylinder, the amounts of correction of the other cylinders are determined.

Growing community of inventors

Shizuoka, Japan

Masaki Torigoshi