Daimler Chrysler Ag

Temic Telefunken Microelectronic Gmbh

Josef Poeppel

Martin Ebel

Stefan Beck

In an electromagnetically actuatable device, an electromagnet is driven with a controlled current progression so that the armature of the electromagnet can be actuated at the lowest possible current level while still achieving the most rapid overall increase of the actuating current from zero to maximum amperage. A first portion or range of the current increase is carried out with a steep or jump-like current increasing characteristic. A second portion or range of the current increase is carried out with a more gradual variation of the current. The current levels at the end points of the respective ranges are selected to ensure that the electromagnet is actuated during the second range in which the current varies more gradually. Preferably, two steep or jump-like current increase ranges are respectively provided before and after the second range having the gradual current increase. The armature of the electromagnet is thereby actuated with the lowest possible energy, and the lowest possible acceleration, so that noise and wear are reduced.

Method and circuit arrangement for reducing noise produced by electromagnetically actuated devices

To control the output from an induction motor with a main winding and an auxiliary winding with multiple taps, varying output stages of the motor are adjusted by the activation of the auxiliary winding or one of its part-windings. According to the invention, the coarse adjustment of the power to be output by the motor is effected by the selection of a certain output stage and a repeating digital m-bit keying pattern generated simultaneously for the purpose of fine adjustment, so that the motor is driven alternately at the set output stage and the next higher or next lower output stage as a function of the sequential logic values of the keying pattern. By means of the process complying with the invention, precise power control is possible which can be used to advantage for the adjustment of output. In addition, a device is described to carry out the process complying with the invention, according to which a microprocessor undertakes the coarse adjustment by way of a control circuit while simultaneously generating the m-bit keying pattern, which is stored in a ring counter, which itself directs the logic values of the keying pattern to the control circuit in succession.

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Fahlenbach, Germany

Josef Poeppel