Ranco Inc.

Gerd Mulier

Guglielmo Rossi

Ursula Eysholdt

In a heating and/or cooling system, two heat transmitting media are blended into a blended medium with adjustable temperature. The motor (M) of a blending member is controlled pulsewise in both directions by comparison pulses from a setpoint/actual value temperature comparison. In order to provide a system which is simple to construct, which is wear-resistant and which permits a quick and accurate adjustment of the blending member, the circuit arrangement for controlling the motor (M) contains a first pulse generator (TB1), which generates pulses of constant width commencing respectively with the end of a comparison pulse and is connected to second and third pulse generators (TB2, TB3). The second and third pulse generators (TB2, TB3) generate pulses of a width proportional to the actual value or the setpoint of the temperature, respectively, which directly control the motor (M) after comparison in a comparator (CO). The blending member is advantageously the blend door for air supply into a motor vehicle or a mixing valve for liquid media.

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Munich, Georgia

Gerd Mulier