Geely JL481Q, Руководство пользователя

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G
asoline engine does work by utilizing spark-plug-created arc to ignite the combustible mixture that is compressed by
the piston during its compression stroke and making them burning. It is necessary for any spark plug to have ignition
energy enough to form an electric arc at some most appropriate crank angle.
The ignition system is mainly composed of ignition coil that generates high voltage ranging from 10KV to 35KV based on
the transient process of the circuit, ignition module, and parts that distribute high-tension electricity to various cylinders,
i.e. distributor, high-tension line, spark plug, etc. There are two main parameters to be controlled according to the engine’s
working condition: a. The power-on time when the current begins to flow through the primary winding, i.e. power-on time
control; b. The time when the current passing through the primary winding is cut off, i.e. ignition timing control
1. Power-on time control
When the primary winding for the ignition coil is powered on, the primary current strength will increase exponentially with
time. The high voltage generated when the primary current is cut off depends on this current strength at this moment. So,
it is generally hoped that the primary winding is powered on until it is saturated. But on the contrary, long-time poweron will
lead to the ignition coil’s overheat, thereby resulting in energy loss, heat-related faults, etc. Hence both aspects shall be
considered for the most optimal power-on time.
Because the change rate of the primary current strength varies with the battery’s voltage, the final most optimal power-on
time can be determined after being corrected according to the battery’s voltage change.
In order to solve the above inconsistency, the ignition system is equipped with a constant current control device, which can
enable a strong current to pass through the ignition coil within a short time.
2. Ignition timing control
For the purpose that the engine can effectively convert thermal energy into mechanical energy, we hope that the highest
combustion pressure occurs when its crank rotates to some point after reaching the top dead center.
From ignition to the point when the highest combustion pressure occurs, it requires a period of time, which is determined
by combustion delay time, flame propagation time, etc. It varies with compression ratio, gasoline quality, air-fuel ratio,
engine load, etc. So, the ignition timing control shall be based on the engine’s working condition.
3. Electronic ignition system
Electronic ignition system can specify ignition-timing characteristics without limitation and enable the optimal correct
ignition timing at any time; compared with mechanical ignition system featuring simple ignition timing characteristics, it can
increase the engine’s output power by 2% to 5%, and furthermore improve fuel economy and emission characteristic.
Electronic gasoline injection engine adopts a non-contact electronic ignition system that has no pulse generator or igniter;
ECU-controlled electronic ignition system can be divided into two types: distributor-type electronic ignition system and
non-distributor-type electronic ignition system. MR479Q/MR479QA/MR481QA/JL481Q engine adopts the ECU-controlled
distributor-type ignition system based on sequential ignition
(1) ECU. Electronic ignition system and fuel injection control system share the same ECU. ECU makes correction to
sensor signals related to engine speed, amount of inlet air (engine load), etc., by using a built-in microcomputer to control
the power-on time and the power-off time (ignition time) of primary current.
Chapter 8 Ignition System
1. Ignition Control
Section 1 Introduction to Ignition System
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