I. Introduction to the Classification of Automotive Electronic Ignition System \x0d\ Components of automotive electronic ignition system: sensors and their interfaces, microcomputers, actuators and other components. \x0d\ function: Calculate and judge according to various engine parameters sent by sensors, and then conduct ignition timing, which can save fuel and reduce adjustment, thus causing air pollution. Determine the best ignition advance angle and power-on time. Parts include: ECU, power supply, ignition coil and spark plug. \x0d\ At present, the electronic ignition systems used in automobiles at home and abroad are mainly divided into contact electronic ignition systems and non-contact electronic ignition systems. No matter what kind of electronic ignition system, electronic components (transistors) are used as switches to connect or disconnect the primary circuit of the ignition system, and high voltage electricity is generated through the ignition coil. \x0d\ 1。 Contact electronic ignition system \x0d\ Contact electronic ignition device adopts the method of reducing contact current to reduce contact spark and improve ignition performance. It is a semiconductor auxiliary ignition device. In addition to the traditional ignition system, there are power supply, ignition switch, distributor, ignition coil and spark plug. In the circuit of the primary winding of the ignition coil, an ignition control circuit composed of triode VT, resistor and capacitor is added. The contacts of the circuit breaker are connected in series in the base circuit of the triode to control the turn-on and turn-off of the triode. \x0d\ Turn on the ignition switch SW. When the contacts of the circuit breaker are closed, the base circuit of the triode is turned on, so that the triode is saturated and turned on, and the primary circuit of the ignition coil is turned on. Its path is as follows: the transistor base current is from battery "+"→ ignition switch SW → ignition coil primary winding n 1→ additional resistor Rf → transistor emitter e and base B→ resistor R2 → disconnector contact K→ grounding → battery "-". The current range of the primary winding of the ignition coil is from battery "+"→ ignition switch SW → ignition coil N 1 primary winding → additional resistance Rf → emitter e and collector c of triode → ground → battery "-". So that the magnetic field energy is accumulated in the iron core of the ignition coil. \x0d\ When the contacts of the disconnector are separated, the base circuit of the triode is cut off, and the triode changes from on to off, which cuts off the circuit of the primary winding of the ignition coil, and the primary current quickly drops to zero, resulting in high voltage generated in the secondary winding of the ignition coil, which breaks through the spark plug gap and ignites the mixed gas. \x0d\ When the engine is working, the contacts of the circuit breaker are constantly closed and separated, which controls the on-off of the triode and the primary circuit, and controls the work of the ignition system. \x0d\ 2。 Contactless electronic ignition system \x0d\ Contactless electronic ignition system uses sensors to replace the contacts of circuit breakers, generates ignition signals, controls the on-off of ignition coils and the work of the ignition system, which can overcome all the shortcomings related to contacts and is widely used in automobiles at home and abroad. Contactless electronic ignition system is mainly composed of ignition signal generator (sensor), ignition controller, ignition coil, distributor and spark plug. The distributor mainly includes distributor, centrifugal advancer and vacuum advancer, and their functions, structures and working principles are completely the same as those of the corresponding parts of the traditional ignition system. \x0d\ For example, the schematic diagram of the contactless ignition system of FAW-Volkswagen Jetta car, when the ignition switch is turned on, when the ignition signal generator (Hall effect sensor) sends out an ignition signal and outputs a positive pulse with a certain amplitude, it will trigger the ignition controller to turn on the power transistor and make the primary circuit of the ignition coil conductive. The primary current is determined by the "+"pole of the power supply. Ignition switch? "+"terminal of ignition coil? Ignition coil primary winding L 1 "- "Ignition coil terminal, ignition controller, grounding and power supply"-"pole. Because there is current in the primary winding of the ignition coil, a magnetic field is formed in the ignition coil to convert electric energy into magnetic energy and store it. \x0d\ Ignition signal generator: The ignition signal generator replaces the cam in the circuit breaker of the traditional ignition system, and is used to determine the position of the piston in the cylinder, and convert the non-electric piston position signal into a pulse electric signal and send it to the ignition controller, thus ensuring the spark plug to ignite at the right time. So the ignition signal generator is actually a sensor, which senses the working state of the engine and sends out the ignition signal. There are many kinds of magnetic pulses, such as Hall effect and photoelectric effect. \x0d\ magnetic pulse ignition signal generator \x0d\ magnetic pulse ignition signal generator is made by using the principle of electromagnetic induction. It is generally installed in the distributor and consists of a signal rotor and an inductor. The signal rotor is driven by the distributor shaft, and its rotating speed is the same as that of the distributor shaft; The inductor is fixed on the bottom plate of the distributor and consists of a permanent magnet, an iron core and an induction coil wound on the iron core. The outer edge of the signal rotor has convex teeth, and the number of convex teeth is equal to the number of cylinders of the engine. The magnetic field lines of the permanent magnet start from the N pole of the permanent magnet, pass through the convex teeth of the rotor through the air gap, and then return to the S pole of the permanent magnet through the air gap and the iron core of the induction coil to form a closed magnetic circuit. When the engine is not working, the signal rotor does not move, the magnetic flux passing through the induction coil does not change, and the induced electromotive force will not be generated. The voltage signal output by the two leads of the induction coil is zero. \x0d\ When the rotor rotates, the magnetic flux passing through the iron core changes gradually. Every time the salient teeth of the rotor turn around the iron core, a positive and negative pulse signal will be generated in the coil. In this way, when the engine is working, the rotor rotates continuously, and the convex teeth of the rotor alternately sweep beside the coil iron core, so that the magnetic flux in the coil iron core changes continuously, and the induced electromotive force with varying magnitude and direction is induced in the coil of the sensor. When the engine is working, the sensor continuously inputs this pulse voltage signal as the ignition signal to the ignition controller. When the rotating speed increases, the change rate of magnetic flux in the induction coil increases, so the induced electromotive force increases in direct proportion. It can be seen that the AC signal output by the magnetic pulse ignition signal generator is greatly influenced by the engine speed. The higher the rotating speed, the stronger the signal, and the more reliable the trigger to the ignition controller circuit, but it may damage the related components in the circuit. Therefore, it is necessary to add components such as voltage regulator to the circuit to limit the voltage. However, when the rotating speed is too low, the alternating signal output by the magnetic pulse ignition signal generator is too weak, which leads to the unreliable triggering of the ignition controller circuit, which is easy to cause problems such as the difficulty in starting the engine and the inability to reduce the idle speed. Therefore, the design should ensure that the signal output by the ignition signal generator is strong enough when the engine runs at the lowest speed. Generally speaking, when the rotating speed changes, the signal voltage output by the magnetic pulse ignition signal generator can change between 0.5 ~ 100v, which can be used not only for ignition control, but also for other sensing signals such as rotating speed. Magnetic pulse ignition signal generator is widely used because of its simple structure and low cost. \x0d\ Hall effect ignition signal generator (Hall sensor) \x0d\ Hall effect ignition signal generator is installed in the distributor. It consists of Hall trigger, permanent magnet and grooved rotor driven by distributor shaft. Hall trigger (also called Hall element) is a semiconductor substrate with integrated circuits. When a DC voltage is applied across the flip-flop, a current I passes through it. If there is an external magnetic field in the direction perpendicular to the current, a voltage UH is generated in the direction perpendicular to the current and the magnetic field, which is called Hall voltage. This phenomenon is called the Hall effect. \x0d\ Hall effect ignition signal generator works by Hall effect of Hall element, that is, it uses the phenomenon that DC voltage and magnetic field act on Hall trigger at the same time to generate voltage signal, so that the sensor can generate ignition signal when the engine is working. The working principle of the Hall generator is that when the rotor blade enters between the permanent magnet and the Hall trigger, the magnetic field lines of the permanent magnet are bypassed by the rotor blade and cannot act on the Hall trigger, and the magnetic induction intensity through the Hall element is approximately zero, and the Hall element does not generate voltage; With the rotation of the signal rotor, when the gap part of the rotor enters between the permanent magnet and the Hall trigger, the magnetic field lines act on the Hall trigger through the gap, and the magnetic induction intensity of the Hall element increases. Under the combined action of applied voltage and magnetic field, the output end of Hall element outputs Hall voltage. When the engine is working, the rotor rotates constantly, and the gap between the rotor passes alternately between the permanent magnet and the Hall trigger, so that a changing voltage signal is generated in the Hall trigger, which is shaped into a regular square wave signal by the internal integrated circuit and input into the ignition control circuit to control the ignition system to work. \x0d\ Hall effect ignition signal generator has more stable performance, good durability, long service life and high ignition accuracy than magnetic pulse ignition signal generator, and is not affected by temperature, dust and oil pollution. In particular, the output voltage signal is not affected by the engine speed, which makes the engine have good low-speed ignition performance and easy to start, so it is widely used. \x0d\ photoelectric effect ignition signal generator \x0d\ photoelectric effect ignition signal generator is based on photoelectric effect principle, triggered by infrared or visible light beam, and mainly consists of shutter (signal rotor), shutter shaft, light source and light receiver (photosensitive element). The light source can be an incandescent lamp or a light emitting diode. Because light-emitting diodes are more resistant to vibration and high temperature than incandescent lamps, they can work continuously at the ambient temperature of 150℃ and have a long service life, so most of them are used as light sources now. Usually, the infrared beam emitted by the light emitting diode is focused by an approximately hemispherical lens, so as to reduce the beam width, increase the beam intensity, facilitate the reception of the light receiver and improve the working reliability of the ignition signal generator. The optical receiver can be a photodiode or a phototransistor. The light receiver is opposite to the light source and separated by a certain distance, so that the infrared beam emitted by the light source can be focused and irradiated on the light receiver. \x0d\ The shading sheet is generally made of metal or plastic and installed on the distributor shaft and under the distributor head. The outer edge of the shading disk is between the light source and the light receiver, and there are notches on the outer edge of the shading disk, the number of which is equal to that of the engine cylinders. The gap allows the infrared beam to pass through, and the rest of the solid part can block the beam. When the shutter rotates with the distributor shaft, the light beam emitted by the light source to the light receiver is blocked alternately by the shutter, so that the light receiver (photodiode or phototransistor) is alternately turned on and off to form an electric pulse signal. When the electrical signal is introduced into the ignition controller, the on-off of the primary current can be controlled, thus controlling the operation of the ignition system. Every time the shutter rotates, the number of electrical signals output by the optical receiver is equal to the number of cylinders of the engine, and each cylinder is ignited just once. \x0d\ Ignition controller: The ignition controller replaces the contact of the traditional interruption device of the ignition system, shapes and amplifies the ignition signal output by the ignition signal generator, converts it into an ignition control signal, and controls the on-off of the current in the primary winding of the ignition coil, thus generating high-voltage electricity in the secondary winding for the ignition of the spark plug. The basic circuit of ignition controller includes shaping circuit, switching signal amplification circuit, power output circuit and so on. \x0d\ Distributor: The distributor of electronic ignition system is different from that of traditional ignition system. The main difference is that the electronic ignition system cancels the circuit breaker (contact and cam) and capacitor, and increases the ignition signal generator (signal rotor and sensing part). Some ignition controllers can automatically adjust the ignition advance angle with the change of engine speed, so these distributors remove the centrifugal advance adjustment mechanism and only keep the vacuum advance adjustment mechanism, while the structure of the distributors remains unchanged. Structure of hall distributor for electronic ignition system. \x0d\ Ignition coil: The ignition coil used in the electronic ignition system is controlled by the ignition controller, so its primary current can be increased, and the inductance and resistance of the ignition coil are generally small. Therefore, it cannot be interchanged with the ignition coil of the traditional ignition system in general. Electronic ignition systems mostly use closed magnetic circuit ignition coils. \x0d\ Spark plug: Due to the improvement of ignition energy of ordinary electronic ignition system, the electrode gap of spark plug is larger than that of traditional ignition system, generally 0.8 ~1.0 mm; In order to adapt to the combustion of lean mixture, some even reach 1.0 ~ 1.2 mm, and there are great differences among various models, so the inspection, adjustment and maintenance should be carried out in strict accordance with the original vehicle specifications. High-voltage line: In order to reduce radio interference, the high-voltage line used in electronic ignition system is a high-voltage damping line with a certain resistance, and the resistance value is generally between several thousand ohms and tens of thousands of ohms; Spark plug plug and distributor also have a certain resistance, usually several thousand ohms. \x0d\ II。 Advantages of electronic ignition system: \x0d\ 1) It can reduce contact sparks, avoid contact ablation and prolong contact service life; Some can also cancel the contact, thus overcoming all the shortcomings related to the contact and improving the ignition performance. \x0d\ 2) can increase the primary current, increase the secondary voltage, and improve the ignition performance of the engine at high speed, which is not limited by contacts. The low-voltage current of the traditional ignition system is generally less than 5A, while the low-voltage current of the electronic ignition system can be increased to 7 ~ 8A, and the secondary voltage can reach 30kV. \x0d\ 3) Due to the improvement of secondary voltage and ignition energy, it is insensitive to carbon deposition of spark plug, and can increase the electrode gap of spark plug and ignite a thinner mixture, which is beneficial to improve the power, economy and exhaust purification performance of the engine. \x0d\ 4) greatly reduces the interference to the radio station. \x0d\ 5) Simple structure, light weight, small volume and convenient use and maintenance.