| 摘要 |
FIELD: process engineering.SUBSTANCE: invention relates to tools drive by DC motors. Proposed tool comprises DC motor to drive cutter, switch connected in circuit from DC power supply to DC motor, trigger switch, control assembly and drive assembly. Control assembly sets duty factor for pulse-width control over DC motor stepwise increase in said duty factor in compliance with duration of depressing trigger switch from the beginning of depressing to preset moment of starting period elapse. Drive assembly switches ON/OFF aforesaid switch in compliance with duty factor set by control assembly to drive DC motor.EFFECT: ruled out damage of motor or switching circuit by excess current.10 cl, 5 dwg |
