| 摘要 |
PURPOSE: A volume variable muffler is provided to improve noise removal and exhaust emission cleaning effects by controlling discharge of exhaust emission through enlargement or reduction of an opening of a muffler depending on rpm of an engine. CONSTITUTION: A fixed electrode is installed at a high speed terminal of a speedometer, and of which indicator rotated depending on increase of vehicle speed. If the indicator is connected with a rotary electrode of the indicator, power is supplied to a power transistor from a power supply. The power transistor applies power to a polarity change switch to magnetize polarity of electromagnets(51,52) installed in outer covers(41,42) of a muffler in opposite to polarity of fixed magnets(53,54). In the outer covers, inner covers(45,46) are installed symmetrically. Extensions(47,48) of the inner covers are connected with the magnets(51-54) via springs(55). If the rotary electrode of the indicator is connected with the fixed electrode due to increase of vehicle speed, the power transistor is turned on and the electromagnets are magnetized into polarity opposed to the permanent magnets. Thus, a repulsive force is generated and the outer covers are widened outwardly. Then, the opening of the muffler is enlarged and exhaust emission is discharged in a large quantity. Therefore, noise removal and exhaust emission cleaning effects are improved.
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