Yamaha Hatsudoki Kabushiki Kaisha

Takumori Yoshida

Akira Yamada

Sadayuki Shinmura

Several embodiments of induction systems for internal combustion engines that improve maximum power and also provide good running at low and medium speeds with a good torque curve throughout the engine speed range. Each embodiment includes a pair of intake passages that serve each chamber of the engine through a respective pair of intake valves. The intake passages are each tuned to serve a different running condition of the engine.

Intake system for multiple intake valve type engines

An embodiment of an induction system for internal combustion engines that permits maximum power output while at the same time insuring good running at low speeds without loss in mid-range torque. Independent intake passages communicate with each chamber of the engine. A throttle valve arrangement is included that includes a first manually operated throttle valve positioned in a common portion of the intake passages, a second manually operated throttle valve that is positioned in the first intake passage between the first throttle valve and the chamber, and a third throttle valve positioned in the second intake passage between the first throttle valve and the chamber. A linkage system interconnects the first and second throttle valves so that the second throttle valve is opened at a predetermined degree of opening of the first throttle valve. The linkage causes the first and second throttle valves to reach their fully opened position simultaneously. The third throttle valve is automatically positioned in response to intake system vacuum.

Intake control system of engine

Several embodiments of induction systems for internal combustion engines that achieve high power outputs without sacrificing low and medium speed running characteristics or without adverse transitional effects. Each embodiment employs a pair of intake valves connecting with each combustion chamber and served by separate intake passages. A control valve is positioned at one of the intake passages and is operated so that the idle and low load requirements are primarily served by the other intake passage. An interconnecting passage interconnects the two intake passages downstream of the control valve and close to the engine valves to improve transitional performance and mid-range torque. In one embodiment of the invention the control valve is operated in response to engine speed and load as sensed in the induction system. In another embodiment an unbalanced control valve is employed that is operated by pressure differences in the induction system. In yet another embodiment the control valve is operated in response to the exhaust gas pressure. In still another embodiment a piston type control valve is employed.

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Iwata, Japan

Takumori Yoshida