On-line diagnosis and control method for knockings of internal-combustion engine

Abstract

The invention belongs to the technical field of an internal-combustion engine and relates to an on-line diagnosis and control method for knockings of the internal-combustion engine. The on-line diagnosis and control method comprises the following steps: utilizing a sensor for a pressure in a cylinder and a photoelectric encoder to synchronously determine a crank angle signal of the pressure in the cylinder of an engine; analyzing by introducing the determined signal into an on-line diagnostic processor for the knockings of the engine; adjusting a work load of the engine, so as to cause the engine to work in a low-speed heavy-load work area in which the knockings are easy to generate; on-line comparing an analysis result of the processor and judging whether a pressure peak under each crank angle, a rise rate of the pressure in the cylinder, an oscillating feature of the pressure in the cylinder and a frequency feature of a knocking center exceed respective preset knocking threshold values or not; confirming whether the engine is subjected to knockings or not according to a final diagnosis result; and if the engine is subjected to knockings, timely adjusting the parameters of angular advance for engine ignition, air-fuel ratio, and the like, through EGU, and performing feedback control till the knockings are eliminated. According to the on-line diagnosis and control method for the knockings of the internal-combustion engine, the problem of the knockings of the modern internal-combustion engine is effectively identified and restrained under the conditions of promoted fuel economy and reduced low-emission of the internal-combustion engine.

Description

Technical field [0001] The invention relates to an online knock diagnosis and control method of an internal combustion engine, in particular to a miniaturized gasoline engine knock diagnosis and control method. Background technique [0002] In the field of internal combustion engines, the engine relies on igniting the high-temperature and high-pressure combustible mixture when the piston is compressed near the top dead center, and converts the heat energy generated by combustion into kinetic energy to output power and torque to the outside. However, under certain conditions (such as high compression ratio, early ignition, etc.), the engine may knock or knock. Knocking is a phenomenon of large high-frequency pressure fluctuations in the combustion chamber caused by abnormal combustion, that is, when the normal flame advances in the combustion chamber, the part of the unburned mixture that is at the final combustion position is under high temperature and high pressure. Under ...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to overcome the defect that the indirect measurement method (vibration, noise signal) and a single pressure signal cannot accurately identify the occurrence of knocking in the prior art, and propose an online diagnosis and control method for internal combustion engine knocking. The in-cylinder pressure and its fluctuation characteristics and frequency characteristics of engine knock combustion are used to diagnose and control internal combustion engine knock online, especially the knock phenomenon of miniaturized gasoline engines, so that it can effectively improve fuel economy and reduce low emissions of internal combustion engines. Identifying and suppressing detonation problems in modern internal combustion engines to advance the internal combustion engine industry

Images