Electric motor for hand-held work tool - has its drive voltage reduced during motor reversal to preserve full power utilisation

摘要

Hand-held work tool, such as an electric screwdriver, is fitted with a reversible electric motor drive system. The motors pref. a universal motor, and, the system is arranged such that no loss of power occurs during motor reversal. To this end, the voltage, supplied to the drive motor rotating in a direction opposed to the working direction of rotation, is reduced. The voltage reduction is specif. achieved by means of a switching element which is inserted into the motor current loop. The switching element can specif. be switched by the switch which is used to change the polarity of the motor.