What is the meaning of ignition advance angle?
2 Answers
Ignition advance angle refers to the spark plug firing before the piston reaches the compression top dead center, igniting the combustible mixture in the combustion chamber. More information about ignition advance angle is as follows: 1. The role of the optimal ignition advance angle is to ensure that the maximum gas expansion phase occurs during the piston's power stroke under various operating conditions, resulting in the highest efficiency, minimal vibration, and the least time spent on temperature rise. 2. The most significant factors affecting the ignition advance angle are engine speed and the combustion speed of the mixture. As the speed increases, the time required to rotate through the same angle decreases, requiring a larger advance angle to achieve the corresponding advance time.
I remember when I was repairing a car, the mechanic told me that the ignition timing is the setting for when the spark plug starts to ignite before the piston reaches the top dead center. Why ignite in advance? Because gasoline takes time to fully burn after ignition, usually a few thousandths of a second. When the engine is running at high speed, the piston moves very quickly. If you wait until the piston reaches the top dead center to ignite, by the time the air-fuel mixture fully burns, the piston has already moved downward, wasting energy. This ignition advance angle is automatically adjusted based on vehicle speed and engine load: at high speeds, the advance angle needs to be larger to ensure explosive power; under low load, it is adjusted smaller for fuel efficiency and smooth operation. If not adjusted properly, too much advance can cause knocking and damage the engine, while too little advance results in insufficient power. I once repaired an old car with incorrect ignition timing—it made a clattering noise when accelerating and was particularly fuel-thirsty.
