Andreas Stihl Ag Co. Kg

Rene Wichert

Gernot Liebhard

Kay-Steffen Gurr

Rudolf Saemann

Andreas Neubauer

Simon Trinkle

Martin Fieseler

Jochen Oerding

Christian Renz

Claudius Kischka

The invention is directed to an arrangement for dissipating heat of an electronic component mounted on a circuit board. The arrangement includes a heat sink for dissipating heat of an electronic component. In order for bottom heat of the electronic component to be dissipated, at least one heat-dissipating heat conducting section is configured on the circuit board, wherein the heat sink is connected in a heat transmitting manner to the heat conducting section of the circuit board. The heat sink by way of a foot section bears directly on the heat conducting section of the circuit board. A recess is configured in the base body of the heat sink, wherein the electronic component lies at least partially in the recess.

Arrangement for conducting heat away from an electronic component

An electric motor in a work apparatus has a power characteristic line which runs between a lower rotational speed of the electric motor and an upper rotational speed of the electric motor. The power characteristic line has a power characteristic with a pronounced maximum (M) and an operating plateau (AP) which lies in a working rotational speed range (AD) of the work apparatus. A method for operating the electric motor provides for configuring the position of the operating plateau (AP) to be variable with respect to the rotational speed of the electric motor to achieve stable operating points over a wide rotational speed range.

Method for operating a work apparatus having an electric motor

A capacitor power supply unit converts a mains voltage (U) into a lower operating voltage (V) for a controller and a supply voltage (V) for an electrical small load. A series circuit including a mains capacitor and a zener diode is connected to the mains voltage (U) whereat the supply voltage (V) for an electrical small load having a permissible operating voltage is tapped off. The capacitor power supply unit provides for the supply voltage (V) to be greater than the permissible operating voltage of the electrical small load and for the small load to be connected to the supply voltage (V) via a buck converter. Here, the buck converter is controlled as a current source having a variable operating frequency.

Capacitor power supply unit for small electrical loads with a high current requirement

A circuit for activating an electric motor in a work apparatus includes a main circuit having an electric motor, a rechargeable-battery pack, and an operating switch for activating the motor, and also a parallel branch to the battery pack and the operating switch. A capacitor is arranged in the parallel branch. To lower the electrical contact load on the operating switch, provision is made to arrange an electronic switch, which is connected in series with the capacitor, in the parallel branch. The series circuit which includes the capacitor and the electronic switch has a first and a second end. The ends form the only electrical power connection of the capacitor to the main circuit. The electronic switch in the series circuit will apply a supply voltage, which is provided by the battery pack, to the capacitor only after a period of time following closing of the operating switch has elapsed.

Circuit for activating an electric motor in a hand guided work apparatus

The invention is directed to a method for braking an electric drive motor having a stator and a rotor. The stator has field coils which have electrical phase connections for three motor phases. To generate an electromagnetic rotating field driving the rotor, the phase connections are connected to a supply voltage via switches actuated by a control unit which closes the switches depending on the rotary position of the rotor. To brake a rotating rotor, a braking current is generated by short-circuiting the phase connections. A phase short circuit is switched in between each two phase connections of the field coils with a preset temporal sequence to brake the rotor. The phase connections short-circuited are each selected corresponding to the rotary position of the rotor so that that field coil is short circuited in which the voltage induced by the magnetic field of the rotating rotor passes through its maximum.

Method for braking an electric drive motor

An electric motor includes an arrangement of windings provided for driving the rotor, with the windings being connected to an energy source to develop torque which drives the rotor. The electric circuits of corresponding ones of the windings each have a potential point, the voltage (U, U) of which is supplied to an evaluation unit via an adaptation device. The adaptation device can be operated in two switchable adaptation stages and is connected to a drive circuit that operates in dependence upon the rotational position of the rotor. The drive circuit switches the adaptation device into the first stage having a high sensitivity or into the second stage having a low sensitivity in dependence upon the rotational position of the rotor of the motor, such that the number of required analog inputs at a microprocessor in the evaluation unit can be kept low.

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Durlangen, Germany

Rene Wichert