| 摘要 |
PURPOSE:To relax the speed unevenness by motor thrust ripple so as to enable the driving excellent in constant velocity by attaching a dynamic vibration reducer, which has the torsional vibration system where torsional resonance frequency accords with the vibration frequency by motor thrust ripple, to a needle, and setting the resonance frequency of the torsional vibration system optionally. CONSTITUTION:A dynamic vibration reducer 19 is constructed by attaching a vibrator 20 having moment of inertial J in inertial moment to the A point of a needle 16 through a plate spring 21 of C in spring constant, and performs torsional vibration around the A point. However, since the shifting speed V of the needle 16 and the cycle a of thrust ripple are obvious at the time of design of a motor, the constants J and C of the dynamic vibration reducer 19 are so designed that the resonance frequency omega2 of the torsional vibration system may be omega2 =2pi v/a=(C/J)<1/2> =(k2/m2)<1/2>. Hereby, the speed unevenness caused by the thrust ripple of a linear DC motor 11 can be negated. Furthermore, it is possible to set the values of J and C so that the above formula may materialize by varying the position of the attachment of the vibrator 20, so constant velocity can be secured even at speed change control of a motor. |
