Virtual cylinder pressure detection method of engine

Abstract

The invention discloses a virtual cylinder pressure detection method of an engine, which is used for realizing real-time optimal control of a combustion process of a gasoline engine, and comprises thefollowing steps of: calibrating a Weber function for combustion prediction by utilizing average experimental data of test working condition points; utilizing a combustion model based on the Weber function to calculate to obtain a predicted cylinder pressure curve, and further obtaining a predicted maximum burst pressure phase; analyzing a collected actual crankshaft signal of the engine, and obtaining the maximum burst pressure phase close to the actual situation based on the actual crankshaft angular velocity information; and comparing the predicted maximum burst pressure phase with the actually measured maximum burst pressure phase, if the predicted maximum burst pressure phase is consistent with the actually measured maximum burst pressure phase, outputting the predicted cylinder pressure curve, otherwise, adjusting the combustion phase in the Weber function, performing iterative computation, enabling the predicted maximum burst pressure phase to be consistent with the actual maximum burst pressure phase, and then outputting the maximum burst pressure phase. Real-time optimal control over the combustion process of the engine is facilitated, and therefore the purposes of oil saving and emission reducing are achieved.

Description

technical field [0001] The invention relates to the technical field of engine combustion process control, in particular to an engine virtual cylinder pressure detection method based on combustion model prediction and combustion information feedback. Background technique [0002] Combustion feedback control technology is an important technology development direction to improve engine performance in practical applications. At present, most of the internal combustion engines used in vehicles have adopted electronic control systems. However, in the current electronic control system of the engine, the combustion control adopts the open-loop control method based on the MAP diagram. Moreover, in the MAP-based control, all control parameters of the same type of engine are set to be the same, and only some parameters will be corrected and adjusted according to certain sensor parameters when the individual engine is running. The combustion process is the core of the engine's working...

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Problems solved by technology

However, neither the crankshaft speed change information nor the body vibration information is a direct measurement of the combustion process, and can only provide indirect combustion information.

Therefore, although the variable information measured by the two will contain certain combustion information, the combustion information can only be extracted from the signal

The noise of the two signals itself is large, and there is no theoretical correlation for information extraction and can only rely on experience. The signal-to-noise ratio is poor, and the measured value is very unreliable, and it is difficult to be used for actual closed-loop control.

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