Robert Boschgmbh

Behr Gmbh & Co.

Gkr Gesellschaft Fuer Fahrzeugklima-regelung Mbh

Horst Singer

Rolf Falliano

Gerold Schultheiss

Juergen Motz

Wolfram Breitling

Reinhold Weible

Werner Hummel

Florian Richter

Uwe Maier

Michael Doster

In a protective circuit for a field-effect transistor which has at least drain-, source- and gate-terminals and is operated as a power switch, overloading of the FET is prevented in case of a power supply voltage of inverted polarity in that the switching voltage is able to be supplied to the gate terminal as a driving voltage via a charge pump. The charge pump is powered via a suitable circuit (e.g., a Graetz bridge rectifier) independently of the polarity of the applied power supply voltage. In case of incorrect polarity of the power supply voltage, the charge pump is driven to output a driving voltage via a suitable circuit (e.g., a diode connected to the base terminal).

Protective circuit for a power field-effect transistor

An electronic control circuit for controlling an electromagnetic valve having an armature, in particular for a heating and/or air-conditioning system in a motor vehicle, has an electronic switching element in series with the coil of the valve and is characterized in that the switching element controls the valve voltage (or the valve current) applied to the coil so that the valve voltage reaches a first value when the valve is switched on; then the valve voltage is reduced to a second value which is lower than the first value; and thereafter the valve voltage assumes a third value which is greater than the second value and represents a holding voltage for holding the armature in its switched-on position.

Electronic control circuit

An arrangement for controlling the rotational speed of an output rotational part of a fluid friction coupling is provided. A fan for cooling components of a motor vehicle is coupled with a driving rotational part by way of a shearing fluid whose effective fluid quantity determines the transferrable torque. The arrangement contains an adjusting unit (which can be electrically driven in a timed manner) for the variable adjustment of the effective shearing fluid quantity and contains a temperature controller stage to which the temperature of at least one medium whose temperature can be influenced by the output rotational speed is fed. The invention, the temperature controller stage is followed by a rotational speed controller stage to which, on the input side, the output signal of the temperature controller stage is fed as the dessired rotational output speed as well as the rotational driving speed and which, via of its output signal, drives the shearing fluid quantity adjusting unit of the coupling. The arrangement is usable for controlling the rotational speed of an engine fan in a motor vehicle.

Rotational speed control arrangement for a fluid friction coupling

Growing community of inventors

Tamm, Germany

Horst Singer