| 摘要 |
PROBLEM TO BE SOLVED: To prolong the period of running a drive unit at a constant speed while securing the strength of gears in winding up a power spring. SOLUTION: This spring type drive unit has a power spring 1 which is the drive power source of the unit, an output shaft 5, a gear mechanism 2 between the power spring 1 and the output shaft 5, a constant speed mechanism 3 to control the rotation of the gear mechanism 2 and make it rotate at a constant speed, switching gears 16, 17 to connect the constant speed mechanism 3 and the gear mechanism 2, a switching member drive pinion 29 integrally formed with a drive shaft 4, a switching member 6, a shaft part 30, a drive gear 8, and a wind-up pinion 7. The switching member 6 engages with the switching member drive pinion 29 in a prescribed range, oscillates together with the rotation of the drive shaft 4, and, in contact with the switching gears 16 and 17 at the end of the moving stroke when the unit is running, separates the switching gears 16, 17 from the gear mechanism 2 or the constant speed mechanism 3. A shaft part 30 whose diameter is smaller than that of the pinion 29, is nearer to the end of the drive shaft 4 than the pinion 29, and can be engaged with the wind-up pinion 7 so that the pinion 7 doesn't rotate is provided. The drive gear 8 is integrally formed with the drive shaft 4 and is incorporated in the gear mechanism 2 when the unit is running. The wind-up pinion 7 is located in the shaft part 30 of the drive shaft 4 and is incorporated in the gear mechanism 2 when the power spring is wound up.
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