| 摘要 |
PROBLEM TO BE SOLVED: To maintain high revolutions of a supercharger at a low speed of an engine, and to improve efficiency of the supercharger by a driving mechanism of a simple constitution. SOLUTION: In this supercharger 1, a rotor 5 of a pair of rotors stored in a housing 9 and rotated and driven by an engine is provided with a shaft 7 extended to an outside of the housing 9, and a pulley 13 on a supercharger side is provided on the shaft 7. This supercharger is provided with a changeover member 25. The changeover member 25 is rotatably supported on the shaft 7, moves a movable pulley piece 13b in an axial direction while receiving urging force of a plate spring 21 by a cam engagement with the movable pulley piece 13b to change a pitch circle diameter of the pulley 13 in three steps, and is capable of supporting the movable pulley piece 13b in each step position by the cam engagement with the shaft 7. A driven side pulley on a crankshaft of the engine is provided with a spring which urges the movable pulley piece 13b to a fixed pulley piece side. Both pulleys 17 and 13 are connected to each other via a V-belt 19.
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