Yamaha Hatsudoki Kabushiki Kaisha

Yasuo Nakao

Kazuhiko Nomura

Shunji Minami

Nobuo Norimatsu

Several embodiments of induction systems for internal combustion engines that improve the charging efficiency, particularly at low speeds are disclosed. Each embodiment employs a plenum chamber upstream of the engine throttle valve and a reed type check valve admits air to the plenum chamber so as to improve charging efficiency at low speeds by maintaining an air flow in the induction system. In accordance with some embodiments, a supercharger is also employed which discharges into the plenum chamber upstream of the throttle valve. This arrangement minimizes pulsation effects from the supercharger being transmitted to the engine intake ports. In addition, the reed type check valve can be employed in many of the embodiments to bypass the supercharger under conditions when the supercharger is not generating any significant boost. The location of the reed type check valve relative to the plenum chamber and throttle valve of the engine minimizes pulsations from being transmitted from the intake ports back to the check valve. In several embodiments an air cleaner housing is formed integrally with the plenum chamber to afford a more compact assembly.

Induction system for internal combustion engines

Several embodiments of induction systems for internal combustion engines that improve the charging efficiency, particularly at low speeds. Each embodiment employs a plenum chamber upstream of the engine throttle valve and a reed type check valve admits air to the plenum chamber so as to improve charging efficiency at low speeds by maintaining an air flow in the induction system. In accordance with some embodiments, a supercharger is also employed which discharges into the plenum chamber upstream of the throttle valve. This arrangement minimizes pulsation effects from the supercharger being transmitted to the engine intake ports. In addition, the reed type check valve can be employed in many of the embodiments to bypass the supercharger under conditions when the supercharger is not generating any significant boost. The location of the reed type check valve relative to the plenum chamber and throttle valve of the engine minimizes pulsations from being transmitted from the intake ports back to the check valve. In several embodiments an air cleaner housing is formed integrally with the plenum chamber to afford a more compact assembly.

An exhaust system for a multicylinder motorbike internal combustion engine. Each cylinder has a respective exhaust pipe. The pipes merge and discharge into a chamber, from which chamber a plurality of silencers, fewer in number than the cylinders, discharges exhaust gases to the atmosphere.

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Iwata, Japan

Yasuo Nakao