One should never say 'never', even if at first it sounds crazy. A Diesel engine fitted with a knocking sensor?. Actually, we've been taught that the Diesel, de facto, always knocks. Thus, we don't need to register it with a sensor, or do we? Indeed, this is exactly what the Delpi company does. Using the catch-phrase 'zero-volume-calibration', it is determined, when the engine is running, at what point the effective injection in a cylinder begins. From time to time, by gradually increasing, one after the other, from zero onwards, the injection amount for each individual cylinder, to determine when it begins to work. Anything less, is then the zero amount, to which, during normal operation, the value from the characteristics diagram must be added.
Although we speak of the 'injection amount', the only possibility to influence this is, after taking the manufacturing tolerances into consideration, (injector-volume adjustment) through the injection duration. By the way, the other CR manufacturers manage without using a knocking sensor by e.g., enriching the engine cylinder-wise so long during fuel cut-off, until a measureable thrust is registered by the reference mark sensor. The immediately preceding injection duration is saved by the control device as the zero-volume.
Up to now, we have checked the effect of a certain injection amount. So, why does a Diesel engine need a broadband sensor? Herewith, the systems relevant for the exhaust gas during operation are checked, as well as the exact adherence to the exhaust gas regulations. Let's take e,g., the exhaust gas recirculation. An error here would have, among other things, an effect on NOX content in the exhaust gas. Together with other measurement values and those from the broadband sensor, the control device now registers the condition. It can assume, from long-term differences, that the basic values have been changed (adaptive learning), or in the event of the exceeding of tolerances, it can register an error. 09/09