Hilti Aktiengesellschaft

Thomas Mueller

Konstantin Baxivanelis

Johannes Stempfhuber

Germar Meiendres

Bernd Ziegler

Markus Looser

Michael Brandner

Benedikt Beckert

An electric tool is disclosed. The tool includes an electric motor, a battery, a monitoring device for monitoring a monitoring operation-value limit, where the monitoring operation-value limit lies above an operation-value limit of the battery, an adjustable resistor component, and an operation-value controller for setting at least one operation-value of the electric motor by a pulse width modulation (PWM) duty cycle. The PWM duty cycle is a first value that is derivable from a current setting of the adjustable resistor component or a second value that corresponds to a PWM duty cycle last used for setting the at least one operation-value plus an offset value. A lower of the first value or the second value is selected for the PWM duty cycle, if an operation-value of the battery lies above the monitoring operation-value limit.

Voltage control at low temperature to avoid undervoltage switch-offs in battery-powered, hand-operated electric tools

A method to monitor the current of a handheld power tool () operated by a battery (), by at least one counter (), includes the following steps:

Method and device to monitor the current of a battery-operated handheld power tool

A method for controlling a motor () which drives a disk-shaped tool () of a power tool () and to which a motor voltage in the amount of a nominal value is applied in an 'on' position of a motor switch (), includes determination of an actual motor current (IM) applied to the motor () and comparing it to a first predetermined threshold (GW), and automatically triggering of a control process for protecting the motor () when an overload condition which is defined in that the first predetermined threshold (GW) is exceeded beyond a first predetermined limiting time period (grDt), is met, the control process including reduction of the motor voltage applied to the motor () by a magnitude that can be perceived by the user as a choke value.

Method of controlling a motor

The method of controlling a motor which drives a tool of a power tool, includes initializing an electronic device and switching the motor on in a first step (), continuously monitoring of the motor current (IM) and a battery voltage (UB) in a second step () which alternates with a third step () in which a continuous comparison of the battery voltage (UB) to a threshold value (GW) stored in a memory of the electronic device is carried out.

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Klosterlechfeld, Germany

Thomas Mueller