| 摘要 |
PURPOSE:To reduce noise without lowering performance by forming an inlet pipe into a Venturi shape which spreads inside a cleaner case, and reducing the ventilation resistance of intake air. CONSTITUTION:An inlet pipe 2 which is opened inside a cleaner case 1 to introduce intake air, is formed into Venturi shape having a curvature R spreading inside the case 1. The bore of the inlet pipe 2 is gradually spread from the outer part to the inner part. By using an inlet pipe 2 having such a shape, acoustic impedance proportionate to pipe length l/sectional area Scan be increased, while reducing a resonance frequency. Accompanying this, the characteristic curve of vibration transmitting rate to a frequency is moved on the low frequency side, increasing a damping factor in the frequency area of high frequencies above the resonance frequency.
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