Robert Boschgmbh

Werner Mohrle

Peter Werner

Ulrich Drews

Hans Schnurle

Wadym Suchowerskyj

Urlich Drews

A device is proposed for regulating the fuel-air ratio in the operating mixture of an internal combustion engine and for monitoring the operational readiness of a .lambda. sensor controlling the regulating device and functioning by the principle of ion conduction in solid electrolytes. The .lambda. sensor has an adjustable, constant reference voltage switched opposite to it. The reference voltage approximately equals the average sensor output voltage. The level of the resultant voltage, which is established with the aid of the resultant current and has values located symmetrically with respect to the reference voltage, is monitored by comparator devices. The output signal of the comparator devices is logically processed and furnishes a signal as to the operational readiness of the sensor. In order to generate the reference voltage, a voltage divider branch having high resistance is disposed parallel to a voltage divider branch of relatively low resistance; the latter voltage divider branch further serves to establish the threshold values of the comparator devices. Because it is independent of the current draw of the comparator devices, the desired reference voltage can be adhered to very precisely, and thus the desired regulating point at which closed-loop control or regulation begins of the regulating device can also be adhered to very precisely.

Device for regulating the fuel-air ratio in internal combustion engines

A method and an apparatus for regulating the fuel-air ratio of the operational mixture of an internal combustion engine and for monitoring the operational readiness of a .lambda. sensor controlling the regulating apparatus and functioning according to the principle of ionic conduction in fixed electrolytes. A constant reference voltage which approximately corresponds to the average sensor output voltage is connected opposite to the .lambda. sensor. The level of the resultant voltage thus established, the values of which are disposed symmetrically relative to the reference voltage, is utilized, along with the cooperation of a resultant electric current which causes a voltage drop across the temperature-dependent internal resistance of the .lambda. sensor as a gauge for the operational readiness of the .lambda. sensor. The pickup of the resultant voltage is accomplished by two comparison devices, whose logically evaluatable output signals are transformed via a logical linkage circuit into an operational readiness or unreadiness signal. A third comparison device serves the purpose of controlling the regulating apparatus. The third comparison device output is switched when the .lambda. sensor is not under the influence of any resultant electric current; as a result, no temperature-dependent shift of the switchover point relative to the internal sensor voltage occurs and regulation can be effected with the regulating apparatus in a temperature in dependent manner to a desired point in the sensor voltage curve or to a desired lambda value.

Method and apparatus for regulating the fuel-air ratio in internal

An apparatus for the open-loop or closed-loop control of the composition of the mixture desired in the combustion chamber of an internal combustion engine, which includes an exhaust gas sensor whose output signal together with other operational parameters, determines the mixture composition. The essential component of the apparatus is a storage unit with which charging and discharging sources controllable in accordance with the sensor signal are associated, wherein the magnitude of the charging and discharging signal is dependent on operational parameters. The storage unit may comprise a capacitor or a resistor-capacitor combination having one terminal connected to ground and another terminal efficiently connected with an operational voltage connection, so as to have in this manner an unequivocal association with a fixed potential.

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Stuttgart, Germany

Werner Mohrle