Combustion parameter evaluation of diesel engine via vibration acceleration signal

Abstract

Efficient combustion control has increasingly become a quality requirement for automobile manufacturers because of its impact on pollutant and greenhouse gas emissions. In view of this, the management system development of modern internal combustion engines is mainly aimed at combustion control. The real-time detection of in-cylinder pressure characteristic parameters has a considerable significance on the closed-loop combustion control of the internal combustion engine. This paper presents a detection method in which the start of combustion, peak pressure, maximum pressure rise rate, and phase of maximum pressure rise rate are identified through vibration acceleration signal. In order to analyze the relationship between vibration and in-cylinder pressure signal, experimental data are acquired in a diesel engine by implementing various injection strategies and engine operating conditions (speed and load). The results show that the start of combustion can be detected by analyzing its relationship with the peak position of the filtered vibration signal, and the phase of the maximum pressure rise rate can be identified by examining its relationship with the zero-cross position that is adjacent to the right of the peak position. Moreover, the filtered vibration signals are also truncated in the same length and utilized as inputs for algorithms to detect the peak pressure and the maximum pressure rise rate. The algorithms are mainly performed on data compression (or feature extraction) and target regression. Major algorithms, such as one-dimensional convolutional neural network, compression sensing, wavelet decomposition, multilayer perceptron, and support vector machine, are tested. Various experimental results verify that for the test engine the phase detection accuracy of the start of combustion and maximum pressure rise rate is less than 1.7°CA for a 95% prediction interval width. For the detection of the peak pressure and maximum pressure rise rate, the normalized error threshold is set as 0.05, then the accuracies can be not less than 95%.

Assessment of the effectiveness of mounting the aircraft piston combustion engine on a test stand

“…Regardless of the research objectives and evaluation criteria as well as limiting conditions (internal and external), the primary action of the scientific approach to research on modern systems is to ensure the most faithful representation of the course of dynamic processes in operating and accompanying parameters, such as in the case of mapping: rotational speed or valve clearance of the engine in its vibration equivalent [2,7], identification of specific vibration parameters during the process of transporting ingredients of the feeding process [14] or bearing lubrication conditions [15], assessment of thermodynamic processes occurring in turbojet or piston engines [29,33], the impact of a specific fuel on the efficiency of the combustion process and emissions of harmful exhaust gas components [1820, 36]. This is particularly important in the case of diagnosis using vibroacoustic processes, which may have different partial goals and application areas, such as: searching for the most effective method of reducing the number of parameters used to evaluate [23], using vibrations to assess the operation of multi-stage wind turbine gearboxes [24,35], methodology for research process depending on the type of process and its nature [26], taking into account safety criteria in the diagnostic assessment [30], using the process of optimizing structures and systems with high dynamics of changes in thermodynamic processes [37].…”