The simple explanation of the ignition coil is to enable the spark plug to "generate sparks" and ignite the part of the mixed gas in the cylinder. It is a transformer responsible for converting the low-voltage current of the vehicle into high-voltage electricity. Under normal circumstances, each cylinder is equipped with a set of ignition coils and spark plugs. Among the many parts of the car, many play a key role, and the ignition coil is one of them. The service life of the ignition coil is generally 100,000 kilometers or even longer. However, the ignition coil should not be underestimated at ordinary times. If there is any abnormality, it must be treated with caution. The damage to the ignition coil is relatively easy to judge. When the engine suddenly shakes abnormally (after driving for a long kilometer) while the vehicle is driving, accompanied by an obvious loss of power, then you have to consider that it may be the ignition coil. problem. Once the ignition coil is abnormal, the spark plug will not work, and then the mixed gas in this cylinder will not detonate. When the vehicle loses a cylinder, the lack of power is natural. Do you want to know more about ignition coils?
The role of the ignition coil
The additional resistor in the low-voltage circuit of the ignition coil has the effect of balancing the high-voltage spark. When the current passes through the primary coil, a magnetic field is generated, and it takes a period from the beginning of the current to the saturation of the magnetic field (that is, to reach the highest level). When the engine is at low speed, the magnetic field can reach saturation. When the engine is at high speed, due to the shortened time, the magnetic field cannot reach saturation, the generated secondary voltage will be insufficient, and the spark will also be weakened.
Ignition coil classification
According to the magnetic circuit, the ignition coil is divided into the open magnetic type and the closed magnetic type.
1. Open the magnetic circuit ignition coil
1. The open magnetic circuit type ignition coil is generally a pot-shaped structure. It consists of several silicon steel sheets laminated to form a rod-shaped iron core, and the secondary coil and primary coil are respectively wound on the outside of the iron core. The secondary coil is an enameled wire with a wire diameter of 0.05-1mm, and the number of turns is 20,000-30,000. The wire diameter of the primary coil is 0.5-1.0 mm, thicker than the secondary coil, and the number of turns is only 150-300. The primary coil is wound outside the secondary coil, so the change of magnetic flux generated by the secondary coil is the same as that of the primary coil. The winding direction of the primary coil and the secondary coil is the same, the beginning of the secondary coil is connected to the high voltage output connector, the end is connected to the beginning of the primary coil, and connected to the "+" terminal of the shell, and the end of the primary coil is connected to the shell The "one" connection column of the igniter is connected to the collector of the power transistor in the igniter, and the igniter controls the on-off of the primary coil current.
2. The magnetic steel sleeve constitutes a magnetic circuit, and the magnetic force lines of the upper and lower parts of the core pass through the air. The magnetic resistance of the magnetic circuit is large, the leakage of magnetic flux is large, and the conversion efficiency is low, generally only about 60%. According to the number of low-voltage terminals, it is divided into two terminal types and three terminal types. The three-terminal post-type ignition coil is equipped with additional resistors, and its low-voltage terminal posts are marked with "-", "+" and "+ switch" respectively, and the additional resistor is connected between "+" and "+ switch"; The column ignition coil has no additional resistance, only two terminals marked with "+" and "-". Whether it is a three-terminal or two-terminal open magnetic circuit ignition coil, its internal structure is the same. The secondary winding uses enameled wire with a diameter of 0.06-0.10mm to wind 11000-23000 turns on the insulating paper tube; the primary winding uses enameled wire with a diameter of 0.5-1.0mm to wind 240-370 turns.
2. Closed magnetic circuit ignition coil
1. The iron core of the closed magnetic circuit ignition coil is closed, and all the magnetic flux passes through the inside of the iron core. The magnetic permeability of the iron core is about 10,000 times that of air, so the open magnetic circuit ignition coil wants to obtain the same as the closed magnetic circuit ignition coil. With the same magnetic flux, the primary coil must have a larger magnetomotive force (ampere-turns). Therefore, a primary coil with more turns and a larger wire diameter must be used; the number of turns of the primary coil is large, and if the same turns-to-Chen ratio is to be obtained, the number of turns of the secondary coil must also be increased. Therefore, the open magnetic circuit ignition Coil miniaturization is impossible. On the contrary, the closed magnetic circuit ignition coil can effectively reduce the magnetomotive force of the coil due to its small magnetic resistance, and miniaturize the ignition coil. At present, the closed magnetic circuit ignition coil has been quite miniaturized, and can be combined with the igniter, and even integrated with the spark plug. The combustible compressed gas in the cylinder is ignited by the spark plug. The traditional ignition coil is an open magnet type, and its iron core is made of silicon steel sheets of about 0.3mm, and the secondary and primary coils are wound on the iron core. The closed magnetic type uses an iron core similar to III to wind the primary coil, and the secondary coil is wound outside, and the magnetic line of force is formed by the iron core to form a closed magnetic circuit. The advantages of the closed magnetic ignition coil are less magnetic flux leakage, small energy loss, and small size, so electronic ignition systems generally use closed magnetic ignition coils.
2. In recent years, closed magnetic circuit ignition coils with high energy conversion efficiency have been used in electronic ignition systems of automobiles. Compared with the traditional ignition coil, its iron core is in the shape of a "mouth" or "say" with a small air gap. The magnetic flux generated by the primary winding in the iron core forms a closed magnetic circuit through the iron core, which reduces the loss of magnetic flux leakage, so the conversion efficiency is high, up to 75%. In addition, the closed magnetic circuit ignition coil also has the advantages of small size, lightweight, and little interference to radio.