Engine Indicated Torque Estimation of a Naturally Aspired Gasoline Engine

The information of clutch transmitted torque is needed when controlling a clutch in a vehicle powertrain. However, engine indicated torque is a very important variable when estimating the clutch torque. The engine indicated torque is generally estimated as a function of engine rotational speed and the mass flow rate of air from an intake manifold into cylinders, which is referred as port air mass flow. The port air mass flow cannot be measured but should be estimated in a real vehicle. In previous studies, the port air mass flow was estimated using the information of the mass flow rate of air into the intake manifold through a throttle plate, which is referred as throttle air mass flow, and the information of air pressure in the intake manifold together. However, this study proposes a new estimation method of the port air mass flow using only the information of the throttle air mass flow. In addition, the engine indicated torque is estimated using the estimated port air mass flow and compared with the measured value. The estimation method of the port air mass flow and engine indicated torque, presented in this study, is verified with production engine experiments.