1. Description
(gasoline) spark advance angle: play a piston reaches the compression top dead center, during which time the crank angle turned referred ignition timing from the ignition advance angle.
igniting the mixed gas from the combustion to burn a time course, the optimum ignition advance angle role in various conditions is the gas expansion work of the piston in the maximum segment trend downward stroke. In this way the maximum efficiency, minimum vibration, low temperature rise.
impact spark advance biggest factor is speed. As the speed increases, the angle rotated the same time becomes short, only a larger lead angle to give the corresponding time advance.
In theory the minimum ignition advance angle is 0 degrees, but only in order to prevent ignition of air-fuel mixture during the power stroke (which could cause loss of power) tends to 5 degrees or more, which is starting angular rotational speed required. The maximum ignition timing can not be too large, generally can not exceed 60 degrees, otherwise it will highlight the problems of vibration and temperature, the efficiency will drop. Crankshaft speed is actually limited.
2, the optimum ignition advance angle
premature ignition, knocking will cause the piston up blocked, reducing the efficiency of thermal load, mechanical load, vibration, and increased noise, which is supposed to prevent of. Late ignition, a gas difficult to work, high fuel consumption, low efficiency and large exhaust sound. Regardless of ignition early or late, it will affect the lifting speed. Optimum ignition angle is affected by many factors, if the car to work under ideal conditions, the following factors must be considered:
1, the cylinder temperature and cylinder pressure. The higher the faster combustion, ignition advance angle to be smaller. Effect of the cylinder temperature and cylinder pressure factors: engine compression ratio, temperature, cylinder temperature, load. Everyone in the car temperature changes of seasons have different performance is due to this.
2, gasoline octane. That is, the stronger the gasoline grade, the higher the resistance to knocking, allowing greater spark advance corresponding angle.
3, the gas mixture ratio. Too thick too lean burn rate are slow, the need to increase the ignition advance angle. This mainly depends on the degree of throttle opening,Altitude.
In the case of unexpected, some vehicles are also fitted with a knock sensor, automatically reduce the ignition advance angle when the knocking occurs.
Obviously, to complete such a complex modulation, by conventional analog igniter it is difficult to accomplish. Only single-chip igniter, to high-speed, accurate, consistent optimum ignition timing.
3, how to check and adjust the ignition timing
(1) inspection, adjustment platinum contact
Check whether there is burning platinum contact traces traces if application No. 0 sandpaper or sand bar to gently wipe marks. Since the contact surface of the platinum contact only a thin layer of carbide, if Over time, the cemented carbide is worn away, the contact time to be replaced, the contact surface of the contact percentage of not less than 80. Platinum contact gap is generally 0.4 ~ 0.5mm.
(2) check, the ignition advance angle
is removed in advance from the sub-chamber vacuum compensation device vacuum hose, and a hose connected to the two block a mouth, the engine idling time while the lamp checking ignition timing advance ignition. For TJ376Q engine and TJ370Q engine, the ignition advance angle is 5 ° + 2 ° (850 + 50f / min); For JL368Q engine, the ignition advance angle of 7 ° (900r / min); CFGFda462Qv motive, which spark advance of 10 ° + 1 ° (900r / min); 276Q for the engine, the ignition advance angle of 6 ° + 2 ° (900r / min).
The method can be used to switch the distributor housing to the ignition advance angle. When the counterclockwise rotation of the distributor housing, the ignition advance angle increases; when rotated clockwise distributor housing, the ignition advance angle will be reduced.
(3) Verify the ignition advance angle
starting the engine, repeatedly pressed the accelerator, if the engine was strongAnd no unusual percussion sound, it indicates that the ignition timing is appropriate. Timing light can also be used to confirm that the ignition advance angle: With increasing engine speed, the timing marks will increase towards the ignition advance angle direction.