I. Introduction

    In the ignition system,Ignition Coil  for igniting the engine cylinder to provide air and fuel mixture ignition energy of the implementation of parts. It is based on the principle of electromagnetic induction, through the shutdown and open the ignition coil primary circuit, primary circuit of the current increases and then decreases abruptly, so that would be induced in the secondary spark plugs ignite the necessary high voltage. Ignition coil can be considered a special kind of pulse transformer, it's low-voltage 10-12V into 25000V or higher voltage.

    2, Ignition Coil  structure and development of

    Automotive ignition system has undergone a circuit breaker (with contacts), electronic ignition (no contact), fuel injection (process control), etc.. With the development of ignition system, car ignition coil structure is toward small, lightweight, energy-oriented direction. At present, there are two Chinese automobile ignition coil structure typical.

    1. Oil Ignition Coil  open magnetic circuit

    (1) component parts

    Oil Ignition Coil open magnetic circuit is widely used in China. The outline structure shown in Figure 1, mainly by the primary winding, secondary coil winding, low terminal, high-voltage output terminal and the high-voltage insulation fill material and shell and other components. Judging from the internal structure of the three major components:
    a. Core: core open form of the ignition coil magnetic circuit.

    b. Secondary coil windings: the soft core around the copper wire on the secondary winding, directly around the core containing thousands of turns on the turn or even thousands of leads.

    c. Primary coil winding: 250 turns around from the wire 100 formed in the secondary winding around the outside. The primary winding of the positive, negative and positive extreme case on the negative extremist connected; secondary winding of the anode and cathode primary winding connected with the shell on the high-voltage negative output connection. Secondary winding turns and the primary winding wire line turns ratio to determine the output voltage of the coil.
    (2) Work
    Mainly through the primary coil winding of the current storage as a magnetic field. When the primary coil winding current suddenly
Cut off (disconnect the circuit through the ground-side power transistor), the magnetic field decay, the induced electromotive force to a secondary coil winding, the EMF voltage enough to spark discharge, which we call inductive discharge ignition. There is also a capacitor discharge ignition systems, often referred to as CDI ignition.

    (3) the shortcomings of Oil ignition coil

    a. Open magnetic circuit structure, a greater flux leakage, low conversion efficiency

    b. Insulating silicone oil will be volatile, overflow, resulting in decreased insulation breakdown easily

    c. Larger

    2. Closed magnetic circuit of solid-type ignition coil

    With the development of modern science and technology, solid-type ignition coil magnetic closure came into being, its applications are more and more widely, much to replace the ignition coil immersed open magnetic trend.

    Closed magnetic circuit of solid-type ignition coil primary winding from the low-voltage coils, high voltage winding circle, closed magnetic circuit core, shell and solid filler and other components. The ignition coil's iron core is a closed magnetic circuit, greatly enhancing the energy conversion efficiency, increase the output voltage, making it easier spark plug ignition. In addition, to reduce eddy current losses caused by core, multi-use 0.35 or 0.5mm of silicon steel quartet built on word or mouth shape, and opened a gap of about 1.5mm in order to avoid core saturation, increased conversion efficiency. The use of solid filler is mainly thermosetting epoxy resin, pressure, good insulation, heat dissipation, sealing is excellent.

    Whether from the structure or from the output voltage, the solid ignition coil closed magnetic circuit has many advantages:

    a. Closed magnetic circuit structure, the magnetic field lines concentrated, high energy conversion efficiency

    b. High voltage insulation, heat dissipation, good performance, high reliability

    c. Smaller to adapt to the needs of car space
    Ignition coil manufacturing process changes and development

    In 80 years, China's automobile ignition coil manufacturing low level are basically immersed open magnetic circuit structure, the primary coil winding secondary winding up on the outside winding, secondary winding around the use of hierarchical level process between layers of paper with a polyester film or a high voltage capacitor insulation; core with columnar open; with silicone oil and other materials for insulation and heat insulation; turned cylinder shell with additional resistance.

    Closed magnetic circuit of solid-type ignition coil secondary winding winding around a multi-groove structure with skeleton-type processing technology, which allows the long winding machine CNC winding, which increases efficiency but also improves the reliability of the ignition coil. Primary coil winding placed outside the core, secondary winding up on the outside of the primary winding. In order to reduce radio interference, in the high-pressure side, and some ignition coils into a small ceramic high-voltage resistors. With A, B pair of the main vacuum chamber were epoxy resin under high vacuum infusion, warming oven for curing. Product pressure, heat, reliability is very high.

    Third, the performance parameters of ignition coil

    Ignition coil main performance parameters:

 a. Sub-peak output voltage

 b. Secondary output voltage rise rate

 c. The duration of the secondary output voltage

 d. Secondary output voltage oscillation amplitude attenuation ratio

 e. Energy spark ignition coil

    The main performance parameters determine the performance of the ignition coil, ignition coil manufacturing process determine the quality.

    Fourth, changes in performance ignition coil and Development

    With the constant changes in the ignition system, car ignition coil structure and properties of the higher demands. To meet the high compression ratio engine, the special requirements of lean mixture and low temperature, high-speed, coke and other adverse conditions, spark plugs, ignition can provide enough energy, it makes a high-energy ignition systems and high-energy ignition coils. Modern ignition coil primary resistance is very small, about from the previous 1.5Ω dropped to around 0.5 ~ 0.8Ω, or even down to 0.25Ω, so the primary input current according to Ohm's law can be effectively increased. Another primary inductance 10 from the previous few mH reduced to about 4 ~ 6mH now, so that the ignition coil on a fast charge capability, to produce the same at high speed sufficient ignition energy. Figure 5 for the snow Fulan "pioneer" double-cab pickup truck with the ignition coil output waveform under low and high contrast test chart. Figure 6 shows the latest of a pen ignition coil, spark plugs to connect it directly, almost no energy loss, has been applied in many models, such as Shanghai Volkswagen's AUDI.