The Research Of The Main Operating Parameters Of The Gasoline Engine To Knocking

Knock combustion is a very complex combustion phenomenon. Knock beyond a certain range, will give undesirable impacts to the gasoline, such as emissions, reducing the performance of the gasoline engine will exacerbate the piston bearing and main bearing wear, or even serious, will cause the connecting rod bearing alloy cracks and so on. But when the knock is in a light range, which is beneficial not only to the dynamic performance of the gasoline, and which is also beneficial to the economy. Therefore, the knock is in a certain range, which is beneficial not only gasoline firmware itself, and also which is better to improve the performance of gasoline.The knock is generated by many parameters of the gasoline engine, this paper discusses the relationship between knock and ignition. With the development of the automotive electronic control technology, researchers know the parameters of the ignition. This paper mainly study from two aspects of the knock ignition control system:(1) Establishment of knock detection model:In this paper, the knock signal can be measured by the body vibration method, where a pressure sensor is mounted for the knock detection. The knock sensor collect the knock signal and use discrete wavelet transform knock signal characteristic values analysis and extraction, and the knock intensity evaluation index I.D. value be judged on the knock intensity. During knock detection system is established, taking into account the accuracy of knock signal acquisition in the design of the filter center frequency control knock module and knock window control module, this can effectively handle different conditions, the extraction and analysis of knock signal more accurately;(2) Establish knock ignition control strategies:carry over signal processing knock signal by comparison and evaluation knock intensity, there will be three situations:no knock condition, critical condition and severe knock state. This paper use three different knock ignition control methods according to three state:1, no knock, a rapid knock ignition advance angle correction module;2, the critical knock, created the ignition advance angle tuning module;3, severe knock, created a rapid retreat ignition advance angle module. By establishing knock detection module and ignition control strategy module for knock control, and it is implemented at ACSET software. And it test at AVL test bench for calibration tests and performance tests. The results showed that:(1) In the knock calibration, at the low speed and load, because the knock tendency is small, so the ignition advance angle can be appropriately increased; At high speed and high load, because the knock tendency is large, the ignition advance angle should be appropriately reduced;(2) The full load characteristics test analysis, as result of the knock ignition control, the gasoline engine dynamic and economy have improved at low speed region. At the high speed region, appropriate to reduce the ignition advance angle, dynamic and economy decreased.Generally speaking, aim to control the knock, at low speed and low load, it should be appropriately increased ignition advance angle; At high-speed and high-load, it should need to lose some power and economy, so as to prevent the occurrence of knocking.