Research On HCCI Combustion Feedback Control With Knock Sensor And Flywheel Speed

Homogeneous Charge Compression Ignition (HCCI) combustion is considered as the new generation combustion and received a lot of attention from the world-wide automotive field due to ultra-low NOx emissions and high thermal efficiency.HCCI combustion is a complicated chemical reaction dynamic process. The combustion feedback method become to the key issues due to there is no direct control method to manage the HCCI combustion process and the feedback method become one obstacle on the way of HCCI engine industrialization. This paper proposed a new feedback method with the combining use of knock signal and flywheel instant velocity, which offers theory direction to resolve the problems laying in HCCI feedback process.By analyzing the knock sensor signal and flywheel instant velocity signal in different working condition, this paper proposed a new feedback method for HCCI combustion. It is to get combustion information with knock sensor signal and flywheel instant velocity which can replace the cylind pressure sensor and has desirable precision.Based on the coupled feedback idea, A set feedback model are build based on the 7 knock sensor signal eigenvalues and 14 flywheel instant velocity eigenvalues, including misfire detecting model, maximum pressure rise rate on the boundary model, combustion mode identification model, CA10 feedback model and CA50 feedback model. The average prediction error of CA50 feedback model in generl working condition is less than 0.7°CA which meets the requirements of closed-loop control for HCCI combustion.It is difficult to realize the realtime feedback of HCCI combustion due to the calculation of HCCI combustion feedback is a complex process and need huge computation capacity. To resolve this key problem, this paper adopt 32 bit microcontroller of multi-CPU and proposed parallel calculation implementation on the microcontroller. To release the multi-CPU's compution capacity, the instant velocity measurement model, the knock signal sample and conditioning model and the engine component drivering model's are implemented in different CPUs of the microcontroller. The parallel process is implemented through the arrangement of the realtim shedular. In this paper, the combustion feedback uint is build with parallel calculation implementation and the whole feedback calculation needs 2.698ms with the multi-CPU microcontroller and the parallel implementation, which meet the real-time requirement of the HCCI close-loop control system.