Electronic ignition system … .
An electronic ignition system is an ignition system in which the creation and distribution of high voltage current to the engine cylinders is accomplished by means of electronic devices. The system is otherwise known as the microprocessor-based ignition system.
It should be noted that the contact-transistor ignition system and the contactless ignition system also include electronic components, but these systems already have their established names.
On the other hand, the electronic ignition system has no mechanical contacts, so it is essentially a contactless ignition system.
Electronic ignition system On modern vehicles, the electronic ignition system is an integral part of the engine management system. This system controls the combined injection and ignition system, and on recent car models also a number of other systems – the intake and exhaust systems and the cooling system.
There are many designs of electronic ignition systems (Bosch Motronic, Simos, Magneti-Marelli, etc.) which differ in design. Electronic ignition systems can be divided into two types:
distributor ignition systems; direct ignition systems. The first type of electronic ignition systems uses a mechanical distributor, which supplies high voltage current to a specific spark plug. In direct ignition systems, the high-voltage current to the spark plug is supplied directly from the ignition coil.
However, an electronic ignition system has the following general device:
1)power source; 2)ignition switch; 3)input sensors; 4)electronic control unit; 5)igniter; 6)ignition coil; 7)high voltage wires (on some types of system); 8)spark plugs.
The input sensors record the current engine operating parameters and convert them into electrical signals. The electronic ignition system uses input sensors that are part of the engine management system in its operation:
1)camshaft position sensor; 2)mass flow sensor; 3)detonation sensor; 4)air temperature sensor; 5)coolant temperature sensor; 6)air pressure sensor; 7)throttle position sensor; 8)accelerator pedal position sensor; 9)fuel pressure sensor; 10)oxygen sensor; 11)and others.
Nomenclature of sensors on different car models may vary.
Electronic engine control unit processes signals of the input sensors and forms control actions on the igniter.
The igniter is an electronic board which ensures that the ignition is switched on and off. The igniter is based on a transistor. When the transistor is open, current flows through the primary winding of the ignition coil; when closed, it cuts off and induces high voltage current in the secondary winding.
The electronic ignition system can have a single common ignition coil, individual ignition coils or dual ignition coils.
A common ignition coil is used in an electronic ignition system with distributor. Individual ignition coils are installed directly on the spark plug, so there is no need for high-voltage wires.
Dual ignition coils are also used in direct ignition systems. On a four-cylinder engine, two such coils are installed, one for cylinders 1 and 4 and one for cylinders 2 and 3. Each coil generates high voltage current on the two leads, so the ignition spark always occurs simultaneously in two cylinders. It ignites the fuel-air mixture in one of the cylinders, while in the other it occurs at idle.
Working principle of the electronic ignition system
The electronic control unit calculates the optimum system parameters in accordance with the signals from the sensors. The ignition is actuated by the igniter, which supplies voltage to the ignition coil. Current starts to flow in the primary coil circuit of the ignition coil.
When the voltage is interrupted, a high voltage current is induced in the secondary coil winding. The high voltage current is fed through the high voltage cables or directly from the ignition coil to the corresponding spark plug. The spark created in the spark plug ignites the fuel-air mixture.
As the engine speed changes, the engine crankshaft speed sensor and camshaft position sensor send signals to the electronic control unit, which in turn performs the necessary ignition advance angle change.
When the engine load is increased, the ignition advance angle is controlled by the mass air flow sensor. The detonation sensor provides additional information about the ignition and combustion of the air-fuel mixture. Other sensors provide additional information about the engine operation modes.
Electronic ignition system
Electronic ignition system
In the electronic ignition system, which is one of the most important components of a modern car, high voltage current is generated and distributed through electronic devices. The electronic system has many distinct advantages and also makes it easier to start the engine in winter.
The electronic ignition system is a system in which a high voltage current is created and distributed by electronic devices. The electronic ignition system of modern cars, which controls the injection and ignition systems, is an important part of the engine management system. In the latest cars, the same system is responsible for the operation of the intake and exhaust systems, as well as the cooling system.
To date, the market is presenting such ignition systems as Bosch, Simos, Motronic, Magneti-Marelli, each of which is structurally different from the others. In general, we can say that the electronic ignition systems are divided into direct ignition systems and systems with distributor. The latter work from a mechanical distributor, which delivers high voltage current to a specific spark plug. Where direct ignition systems are concerned, the current is supplied directly from the ignition coil.
Design of the electronic ignition system
Any electronic ignition system has components such as a power supply, input sensors and ignition switch, electronic control unit, igniter, coil and spark plugs. Some systems also have high voltage wires.
The input sensors are responsible for capturing the current engine operating parameters, converting them into electrical signals. The nomenclature of the sensors may vary slightly depending on the vehicle model.
The electronic control unit processes the signals coming from the input sensors, acting in turn on the igniter. The igniter, which is based on a transistor, is a kind of electronic board that turns the ignition on/off. When the transistor is open, current flows through the primary winding of the coil. If the transistor is closed, the transistor is cut off and the current is conducted through the coil’s secondary.
An electronic ignition system can have different coils: one common coil, individual coils or twin coils. Common coils are used in systems that have a distributor. Individual coils are installed directly on the spark plug, so high-voltage wires are not used in such a system.
Dual coils are used in direct ignition systems. If the engine has four cylinders, a single coil is installed on the 1st and 4th as well as on the 2nd and 3rd cylinders, each of which is responsible for generating current on two leads, which is why the ignition sparks simultaneously appear in two cylinders. In one, the fuel-air mixture is ignited, in the other, the ignition is idle.
1 – controller; 2 – ETC solenoid valve; 3 – screw sensor; 4 – coolant temperature sensor; 5, 6 – inductive start and angle impulse sensors; 7 – ignition coils; 8 – spark plugs; 9 – ignition switch; 10 – accumulator battery; 11 – fuse and relay box
The electronic control unit reacts to the signals from the sensors and calculates the optimum parameters for the operation of the system. First of all, the ECU acts on the igniter which energizes the ignition coil, in the primary winding of which a current starts flowing.
When the voltage is interrupted, the current is induced in the secondary winding of the coil. Directly from the coil or through the high-voltage wires, the current is sent to a specific spark plug, where a spark is produced to ignite the fuel-air mixture.
If the speed of the crankshaft changes, the crankshaft speed sensor and the camshaft position sensor send signals directly to the ECU, which changes the ignition advance angle.
If the engine load increases, the ignition advance angle is controlled by the air flow sensor. The detonation sensor provides important additional information on ignition and combustion of the air-fuel mixture.
The advantages of electronic ignition systems
Electronic ignition systems have many advantages:
– possibility of application on any types of carburetor engines; – increase in the secondary voltage by 1.3-1.5 times, which can be 20-30 kV in any engine operating mode; – long service life of the interrupter contacts, which can reach 150 thousand km and more; – increased gap between the spark plug electrodes, which reaches 1-1.2 mm; – easier engine starting in winter; – time saving in preventive and adjusting works.
Among the disadvantages of electronic ignition systems, the complexity and high cost of the system stands out in the first place, but all the disadvantages are compensated by the above advantages.
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