Abstract
Greater sophistication of control systems is driving an increase in the number of sensors installed in the engine. In response, the authors are working to develop a virtual temperature sensor that can operate on the ECU in order to reduce cost and monitor sensor reliability. This paper reports on a virtual sensor that estimates exhaust manifold gas temperature and the response model for the actual temperature sensor. The model for estimating exhaust manifold gas temperature was prepared based on the equation of energy conservation in the cylinder, and variation in indicated thermal efficiency is expressed by an empirical formula based on the measurement results. In addition, the response delay of the actual temperature sensor is modeled as a second-order transfer function with variable time constants, and variations in the time constants are calculated based on the heat transfer model. Estimated accuracy was checked in simulation of transient test cycle, and the proposed model was confirmed to have adequate accuracy as a virtual sensor.
