Why does a gasoline engine have an optimal ignition advance angle under each working condition?

Under the condition of maximum power and minimum fuel consumption of gasoline engine, there is an optimal ignition advance angle corresponding to each working condition.

Ignition advance angle correction value: the electronic control unit further optimizes the basic ignition advance angle according to certain correction characteristics according to sensor signals such as engine intake temperature, coolant temperature, throttle opening, air-fuel ratio of mixed gas, starting switch, air conditioning switch and related switch signals, so as to make the engine have the best ignition performance.

Extended data:

Precautions:

If the advance angle is too large, the ignition is too early when the mixture is compressed, and the combustion pressure has reached the maximum before the piston reaches the highest point, then the mixture has done reaction work and the engine can hear a special knocking sound. This is the so-called engine knock, fuel consumption increases and power output decreases.

If the combustion speed of the mixture is fixed, the time from ignition to complete combustion of the mixture is fixed. However, with the increase of engine speed, at the same time, the crankshaft will rotate more. In order to obtain the maximum combustion pressure at the top dead center of compression stroke 10 ~ 15, it is only necessary to ignite in advance, that is, to increase the ignition advance angle. Therefore, the higher the rotational speed, the greater the ignition advance angle is required.

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