Experimental realisation of predefined diesel combustion processes using advanced closed-loop combustion control and injection rate shaping

Abstract

In this paper, a combustion control algorithm is presented that, in combination with rate shaping, allows closed-loop control of a cylinder pressure trace. Given this system, it is possible to control the behaviour of the entire combustion process. The paper starts with an explanation of the control algorithm that was developed based on iterative learning control. Consequently, the so-called α-process, which comprises a constant pressure rise, is presented as an example of the additional degrees of freedom gained. Based on the exact analysis of experimental results and combustion simulations, the effects of a peak pressure limitation on the emission behaviour of a single-cylinder engine powered by an α-process are analysed in detail. The capability of the developed control system to isolate certain effects of ideal combustion processes gives a wide range of possible further investigations. However, for practical applications, the use of injection rate shaping is coupled with high hardware costs. Therefore, an additional concept study regarding the possible realisation of the developed control system with a conventional common-rail injector is presented. In this study, it is shown that injectors without rate-shaping capabilities are able to solve the feedback control problem through multiple injection strategies.