FUEHLER ZUM MESSEN DES ANREICHERUNGSGRADES EINES BRENNBAREN GEMISCHES UND VERFAHREN ZUM MESSEN DES ANREICHERUNGSGRADES EINES BRENNBAREN GEMISCHES

A wide range combustion mixture air/fuel ratio sensor in which an electrochemical cell supplies hydrogen gas to a palladium sensor element at a rate regulated by the output of a Wheatstone bridge circuit incorporating the sensor element. This generated hydrogen gas combines with any oxygen present in the exhaust gas through catalytic action and also maintains the level of absorbed hydrogen, and therefore the electrical resistance of the palladium sensor element, at a preselected value. The magnitude of the current applied to the electrochemical cell necessary to maintain this balance is a measure of the combustion mixture air/fuel ratio.