| 摘要 |
PURPOSE: A resonator for offsetting intake noise of a surge tank is provided to change noise offset frequency depending on working state of an engine. CONSTITUTION: A resonator(4) is connected with a surge tank(1) through two neck parts(5,6). One of the neck parts is a low speed channel(8) with smaller sectional area(A1) and longer length(L1). The other of the neck parts is a high speed channel(9) with larger sectional area(A2) and shorter length(L2). A valve(10) rotates centering on a hinge axis(11) to selectively open and close the channels and rotated by an actuator. The lengths and sectional areas of the neck parts of the resonator are designed correspondingly with characteristic operation area of an engine, for example, low speed of 2000RPM and high speed of 3500RPM. An electronic control unit detects through an RPM sensor when the engine runs at low speed, and controls an actuator so that the valve cuts off the high speed channel and opens the low speed channel. The resonator and the surge tank are connected through the low speed channel thereby to damp noise frequency corresponding with the RPM. The electronic control unit controls the actuator when the engine runs at high speed so that the valve cuts off the low speed channel and opens the high speed channel. The resonator and the surge tank are connected through the high speed channel to damp noise frequency corresponding with the RPM.
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