Failsafe emergency operation device for idling operation in motor

Abstract

A failsafe emergency operation device for the idling operation of motor vehicles, in particular for a digital idling charge regulation having a final control element triggered by an end stage circuit, which final control element, as a two-coil rotary adjuster, controls the cross section of an air bypass parallel to the throttle valve. A central computer (microprocessor, microcomputer) prepares a digital trigger signal for the end stage having a duty cycle which is variable depending upon the final control element position required. At the same time, at at least one position of the final control element, an end stage monitoring signal which is to be fed back is prepared and fed back to the computer, which via a separate shutoff stage for the end stage makes this end stage current-free whenever agreement does not exist between the two signals in terms of the duty cycle. A failsafe circuit is furthermore provided, which receives separate control pulses or is supplied with the duty cycle trigger signal supplied to the end stage by the computer, and in case of malfunction this failsafe circuit emits a reset signal, which likewise shuts off the end stage, resets the microcomputer, or alternatively can throw an emergency operation generator ON, which generator then supplies the end stage with an emergency operation duty cycle for triggering it.