TONDEUSE A GAZON ELECTRIQUE

摘要

A battery driven electric lawn mower includes a DC motor, and mowing blade on an output shaft of the motor. A control unit is connected between the motor and the battery for increasing and decreasing the electric current supplied to the motor in accordance with an increase and decrease in load, to thereby maintain the number of revolutions per second of the motor substantially constant at or near a minimum value permitting a mowing blade to function normally under a heavy load. The control unit comprises an electric current detecting device for detecting a load current flowing in the motor, and a pulse generating device for outputting a pulse signal having a pulse width corresponding to an electric current value detected by the electric current detecting device. A pulse-responsive switch device for adjusting the electric current supplied to the motor in response to a pulse signal output from the pulse generating device. The pulse responsive switch device is connected in series with the motor. A duty ratio of the pulse signal output from the pulse generating device is increased in accordance with an increase in electric current detected by the electric current detecting device.