| 摘要 |
PURPOSE:To prevent lowering of output due to the pulsation of intake air by employing a straight intake tube associated with no throttle valve from an intake port to an open end of an air chamber disposed in the upstream thereof and arranging a pressure wave reflector for squeezing a portion of the intake tube at the open end of the air chamber of said intake tube. CONSTITUTION:A straight intake tube 30A associated with no throttle valve nor a member for blocking a pulsating intake air such as a carburetor is employed between an intake port 26A and an air chamber 32A disposed in the upstream thereof. A reflector 40A is arranged at an open end section 42A of the intake tube 30A to the air chamber 32A, then an actuator 100 is driven by the output from a controller 104 produced through detection of rotation 102 and the reflector 40A is closed in specific rotation area of engine. When the reflector 40A is closed, negative pressure wave of pulsating intake air pressure wave counter flowing through the intake tube 30A is reflected as it is by the reflector and cancels out a positive pressure wave occurring at the open end 42A. Consequently, lowering of the volume efficiency is prevented and the engine power performance can be improved.
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