Combustion parameters estimation and control using vibration signal : Application to the Diesel HCCI engine

This paper proposes a method to estimate and to control the combustion timing of a diesel homogeneous charge compression ignition (HCCI) engine without cylinder pressure transducers. The principle of the proposed controller is to correct the start of injection (SoI) in order to compensate the effects of the air path errors or injection system perturbation. The controller takes as inputs the middle of combustion estimated from the vibration trace recorded with a knock sensor fitted at the surface of the engine block. The estimated combustion parameters are computed in real-time and sent to the engine control system in a cycle to cycle manner. The contribution of this paper is combustion state estimator and controller that allows to maintain the desired combustion timings. Tests are performed on a test bench to compare the estimated and measured combustion timing. The closed-loop controller is validated in steady engine conditions and the obtained results demonstrate the potential of this approach.