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1 Ignition System
Introduction:
in a gasoline engine, the combustible gas mixture in the cylinders is by spark ignited, gasoline engine for this cylinder cover with a spark plug head extends into the combustion chamber. All the equipment is capable of time between the spark plug electrode is called the ignition system, ignition system usually consists of a battery, a generator, distributor, ignition coil and the spark plug and other components.
Category:
according to different engine operation modes may be divided into spark ignition (SI Spark Ignition) engines and compression ignition (CI Compression Ignition) engine, petrol engine belongs to spark ignition engines, diesel engines and compression-ignition engines belong. Gasoline engines belong to both spark ignition engine, its ignition must be completed by the ignition system. Gasoline engine cylinder intake and the fuel-air mixture, spark ignited at the end of the compression stroke, so that the mixture ignited to produce strong pressure, push the piston downward movement of work. For this purpose a set of means capable of generating a spark in the cylinder gasoline engine tops, called the ignition system.
Function:
The ignition system when the engine is operating in the role of engine speed and any load different engines, provides sufficient at an appropriate timing voltage sufficient to ignite the spark plug to produce a spark mixture in the cylinder, so that optimum combustion engine efficiency. Ignition system comprises a base unit power supply (battery), an ignition trigger device, the ignition timing control means, high voltage generator (high voltage winding), high-voltage distribution device (distribution boards), and the ignition plug high-voltage wiring. Modern spark advance is controlled by means already modified engine management computer, computer collection engine speed, intake manifold pressure or air flow, throttle position, battery voltage, temperature, knocking signal, calculating the optimum ignition timing advance angle, and then send the ignition signal, to controlSystem object of the ignition timing.
Principle:
gasoline engine ignition system is a gasoline engine, means for mixing gas by electric discharge gas engine ignition. Its function is based on the timing of the cylinder firing order to provide sufficient high voltage energy to the spark plug, a spark is generated between the spark plug electrodes, thereby igniting the compressed fuel mixture in the cylinder.
Typically the ignition system, the ignition coil by a power supply, distributor (including breaker) and the spark plug and other components. Wherein the primary coil power supply, the breaker and the ignition coil portion constituting the low-voltage circuit; secondary winding of the ignition coil, distributor and a spark plug constituting the high-voltage circuit portion.
from the beginning of the ignition coil, the secondary coil and the core composition. The crude primary coil wire and less turns, and the number of turns of fine wire coil, is equivalent to a step-up transformer.
a mechanical breaker and two kinds of transistors, mechanical application of the more common. When the engine is running, the camshaft rotating the cam driving distributor, breaker contacts open and close control. When the low-voltage circuit breaker is closed, i.e. a low pressure primary coil current, a magnetic field is formed in the ignition coil. When the current reaches a certain value, the low-voltage circuit breaker is disconnected, the magnetic flux disappears, the spark plug electrodes 10 to 24 kV is induced electromotive force in the secondary coil, successively passed through the distributor corresponding cylinder, i.e., to generate electricity spark. When the contact is open, the primary coil induces electromotive force sense by the arcing between the contacts caused by erosion, and slow the rate of loss of magnetic flux, electromotive force induced in the secondary winding reduced. To eliminate the self-induced emf, parallel to the contacts of the one microfarad capacitor 0.15 to 0.30.
The ignition system can be divided into different power supply battery and magneto ignition system, an ignition system, both the operating principle is substantially the same, only slightly different low-voltage circuits. Usually with a car battery, battery ignition systems are used. In applications requiring high reliable and not with the battery, such as the aircraft engine, gasoline and tractor small gasoline engine is often used magneto ignition system.
Fault Detection and Exclusion:.
1 fault circuit
In its ignition system fault ignition systemThe location may be divided into two cases: the failure low voltage circuit and a high voltage circuit failure.
(1) low voltage circuit common fault:
is less than the electrical storage battery; line connection failure or disorder; Ground battery failure; or a Hall sensor is damaged distributor; ignition switch is damaged or defective wiring ; transistorized ignition control unit is damaged or defective wiring. Low-voltage circuit failure diagnosis method mostly used by the ammeter or voltmeter ray troubleshooting point.
(2) high-voltage circuit common failure:
or high-voltage drain off; distributor cap rupture breakdown; distributor distributor rotor ablation rupture breakdown; spark plug electrode gap is too large or too small; excessive spark plug fouling; damage spark plug insulator; ignition coil wiring damage or loss.
Most high voltage circuit faults using high-pressure fire test method, i.e. the center of the distributor cylinder a high-voltage or high-voltage disconnect, placed at a distance of 3-6mm thread cylinder, starting the engine test fire, sparks and strong spark , indicating that the ignition system is working properly. .
2 does not operate the ignition system
(1) Symptom: With the ignition, start the engine, the engine no response; high-pressure fire test, no high voltage spark. .
(2) Analysis and Diagnosis
3 premature ignition timing
(1) Symptom: idling operation is not smooth, easy to turn off; the time of acceleration, the engine has severe knocking sound.
(2) Failure Analysis: The fault is primarily the ignition timing adjustment or an ignition angle of misalignment due to misalignment assembly.
(3) exclusion method: even better ignition tester, the ignition advance angle to a predetermined value. .
late ignition 4
(1) Symptom: heavy sound muffler, carburetor tempering hard acceleration, the higher the engine coolant temperature, cars weakness.
(2) Analysis and Fault Diagnosis: ignition angle is not correct.
(3) exclusion method: to a predetermined value of the ignition angle.
5. The spark plug failure
The main fault as follows: spark plug fouling, overheating phenomena such as oil, and
spark plug fouling: the end portion of the insulator, the spark plug electrode and the shell is often covered with a relatively thick soft dark gray powder fouling.
The spark plug oil: Symptom: an end portion of the insulator, the spark plug electrode and the shell covered oil.
The spark plug overheating: melting center electrode, an insulator top loose, fluffy, off-white crusty most end of the insulator.
6. The engine backfires and blasting
If there are to launch both tempering blasting sound, and very serious, it is mostly high-voltage sub-cylinder inserted in the wrong caused. If the phenomenon is not serious, but intermittent occurrence, like a regular, then mostly cracked distributor cap, so that the fire caused between the cylinder channeling. Ignition advance angle from the correct position is too large, tempering can cause the exhaust pipe or blasting.
7. Overheating and engine knocking
Engine knock occurs most easily in the medium speed load is large. In the case of the correct grade of fuel, mostly due to the detonation ignition timing caused by too much.
In the case of knocking, the engine will be warmed up rapidly. On the other hand, the ignition advance angle too far behind, late ignition, the engine temperature will be high. Without knocking, the water temperature is too high, most are not caused by the ignition system, but if the engine is accompanied by weakness, acceleration insensitive, you should check whether the ignition advance angle is too small.