Calculation of ignition coil of gasoline engine

The usual ignition coil has two groups of coils, primary coil and secondary coil. Thick enameled wire is used for primary coil, generally with 0.5- 1 mm enameled wire for about 200-500 turns; Fine enamelled wire for secondary coil is generally 0. 1mm, about 15000-25000 turns. One end of the primary coil is connected to the low-voltage power supply (+) on the vehicle, and the other end is connected to the switching device (circuit breaker). One end of the secondary coil is connected with the primary coil, and the other end is connected with the output end of the high-voltage line to output high-voltage electricity.

The reason why the ignition coil can change the low-voltage electricity on the car into high voltage is because it is the same as the ordinary transformer, and the turn ratio of the primary coil is greater than that of the secondary coil. However, the working mode of ignition coil is different from that of ordinary transformer. The working frequency of ordinary transformer is fixed at 50Hz, which is also called power frequency transformer, while the ignition coil works in pulse form, which can be regarded as a pulse transformer, which repeatedly stores and releases energy at different frequencies according to different engine speeds.

When the primary coil is connected to the power supply, with the increase of current, a strong magnetic field is generated around it, and the iron core stores magnetic field energy; When the switching device disconnects the circuit of the primary coil, the magnetic field of the primary coil decays rapidly, and the secondary coil will induce high voltage. The faster the magnetic field of the primary coil disappears, the greater the current at the moment of current disconnection, the greater the turn ratio of the two coils, and the higher the voltage induced by the secondary coil.

Coil type

According to the magnetic circuit, the ignition coil is divided into two types: open magnetic type and closed magnetic type. The traditional ignition coil is magnetic-opening type, and its core is made of silicon steel sheet of about 0.3 mm, and the secondary and primary coils are wound around the core. In the closed magnetic type, a primary coil and a secondary coil are wound outside with an iron core shaped like III, and magnetic lines of force are formed by the iron core to form a closed magnetic circuit. The advantages of closed magnetic ignition coil are small magnetic leakage, less energy loss and small volume, so closed magnetic ignition coil is widely used in electronic ignition system.

Coil distribution

There are many manufacturers of ignition coils in China, but generally speaking, the overall distribution of ignition coils is obvious, that is, Shanghai, which is dominated by the Yangtze River Delta, Wenzhou Ruian, which is famous for its auto parts, and Hunan Province. Among them, the domestic ignition coil is better, and the enterprise with the same quality and technology as foreign technology is Naite enterprise mainly based on Ryan.

Numerical control ignition

In the high-speed gasoline engine of modern automobile, the ignition system controlled by microprocessor, also known as digital electronic control ignition system, has been adopted. The ignition system consists of microcomputer, various sensors and ignition actuator.

In fact, in modern engines, the two subsystems of gasoline injection and ignition are controlled by the same ECU and share a set of sensors. Sensors are basically the same as those in electronically controlled gasoline injection system, such as crankshaft position sensor, camshaft position sensor, throttle position sensor, intake manifold pressure sensor and knock sensor. Among them, the deflagration sensor is a very important sensor for electronically controlled ignition (especially for engines with exhaust gas turbochargers). It can monitor whether the engine is deflagrating and the degree of deflagration, and use it as a feedback signal to make ECU command to realize ignition advance, so that the engine can achieve high combustion efficiency without deflagration.

According to the structure, digital electronic controlled ignition system (ESA) can be divided into distributor type and distributor-free type (DLI). The distributor type electronic control ignition system only uses one ignition coil to generate high voltage electricity, and then the distributor ignites the spark plugs of each cylinder in turn according to the ignition sequence. Because the on-off work of the primary coil of the ignition coil is undertaken by the electronic ignition circuit, the distributor cancels the circuit breaker device and only plays the role of a high-voltage distributor.