An ignition coil (also called spark coil ) is an induction coil in a car ignition system that converts low-voltage batteries into the thousands of volts required to create electric sparks. in the spark plug to ignite the fuel. Some windings have internal resistors, while others depend on wire resistors or external resistors to limit the current flowing to the coil from the 12 volt supply of the car. The cable coming out of the ignition coil to the distributor and the high voltage cable that flows from the distributor to each spark plug is called the spark plug or high voltage. Initially, any ignition coil system required the point of contact of the mechanical breaker and capacitor (condenser). Newer electronic ignition systems use power transistors to provide pulses to the ignition coil. Modern passenger cars can use one ignition coil for each engine cylinder (or a pair of cylinders), eliminating spark plugs prone to error and distributors to route high voltage pulses.
Ignition systems are not required for diesel engines that rely on compression to ignite fuel/air mixtures.
Video Ignition coil
Basic principles
An ignition coil consists of a laminated iron core surrounded by two copper wire reels. Unlike power transformers, the ignition coil has an open magnetic circuit - the iron core does not form a closed loop around the roll. The energy stored in the core magnetic field is the energy transferred to the spark plug.
The primary winding has relatively few wire loops. The secondary winding consists of thousands of smaller wire loops, isolated from high voltage by enamel on wire and an oiled paper insulation layer. Rolls are usually inserted into metal cans or plastic boxes with insulated terminals for high voltage and low voltage connections. When the contact breaker closes, it allows the current from the battery to flow through the primary winding of the ignition coil. The current does not flow instantly due to the inductance of the coil. The current flowing in the coil produces a magnetic field in the core and in the air around the core. The current must flow long enough to store enough energy in the field for sparks. After the current has reached full level, the contact breaker will open. Because it has a capacitor connected to it, the primary winding and capacitor form a tuned circuit, and when the stored energy oscillates between the inductor formed by the coil and the capacitor, the magnetic field that changes in the coil core induces many larger voltages in the secondary coils. More modern electronic ignition systems operate on exactly the same principle, but some rely on charging capacitors up to about 400 volts rather than charging the inductance of the coils. The opening time of the contact (or transistor shift) must be matched to the piston position in the cylinder so that the spark may be given time to ignite the air/fuel mixture to extract the most likely angular momentum. This is usually a few degrees before the piston reaches the dead center. The contact is driven from the shaft driven by the camshaft engine, or, if electronic ignition is used, the sensor on the machine shaft controls the pulse time.
The amount of energy in the spark required to ignite the fuel-air mixture varies depending on the pressure and composition of the mixture, and at the engine speed. Under laboratory conditions as little as 1 millijoule is required in every spark, but the practical coil should provide more energy than this to allow for higher pressures, rich or slender mixes, losses in ignition cables, and plug fouling and leakage. When the gas speed is high in the spark gap, the arc between the terminals bounces away from the terminal, making the bow longer and requiring more energy in each spark. Between 30 and 70 milli-joules are delivered in every spark.
Maps Ignition coil
Materials
Previously, the ignition coil was made with varnish coils and high-insulated insulated paper, inserted in a steel can and with oil or asphalt for insulation and moisture protection. The coil on a modern car is casted in a filled epoxy resin that pierces every cavity inside the winding.
A single spark system has one coil per spark plug. To prevent premature sparking at the start of the main pulse, a secondary spark diode or splice is installed in the coil to block the back pulse to be formed.
In coils intended for double spark systems, the secondary winding has two terminals isolated from the primer, and each terminal is connected to the spark plug. With this system, no additional diodes are needed as there will be no air fuel mix in the inactive plugs.
In low inductance coil, less primary rotation is used, so the primary current is higher. It is not compatible with the capacity of mechanical break point, so solid-state switching is used.
Use in car
Initial gasoline-based combustion engine (gasoline) uses a magneto ignition system, since no battery is mounted to the vehicle; magnetos is still used in piston engined aircraft to keep the engine running in the event of a power failure. The voltage generated by the magneto depends on the speed of the engine, making the start difficult. A battery-operated coil can provide high voltage sparks even at low speeds, making starting easier. When batteries become common in automobiles for cranking and lighting, ignition coil systems replace magneto ignition.
In older vehicles, a single coil will serve all the spark plugs through the ignition distributor. Notable exceptions are Saab 92, some Volkswagen, and Wartburg 353 which has one coil of ignition per cylinder. Flat twin cylinder 1948 CitroÃÆ'¡n 2CV uses one double coil without distributor, and only breaker contact, in splash system wasted.
Modern ignition system
In modern systems, distributors are eliminated and ignition is precisely controlled electronically. Smaller coils are used with one coil for each spark plug or one coil that serves two spark plugs (eg two coils in a four-cylinder engine, or three coils in a six-cylinder engine). A large ignition coil puts about 40 kV, and a small one like from a lawnmower puts about 15 kV. These coils can be mounted remotely or they can be placed on top of the spark plug (coil-on-plug or Direct ignition) . Where one coil serves two spark plugs (in two cylinders), it is through a "splash wasted" system. In this setting, the coil produces two sparks per cycle to the second cylinder. The fuel in the cylinder near the end of its compression step is ignited, while the spark on its companion approaching the exhaust tip has no effect. Wasted spark systems are more reliable than single coil systems with distributors and cheaper than coil-on-plug.
Where coils are applied individually per cylinder, they can all be contained in a single mold block with multiple high-voltage terminals. This is usually called a coil pack.
Poor coil packets can cause jams, poor fuel consumption or power loss.
Related scrolls
- An Oudin coil is a disruptive discharge coil.
- Low voltage coil
See also
- Electromagnetism
- Faraday's induced law
- The flyback converter
- flyback transformer
- Magnetic field
Patent
- AS. Patent 609,250 , " Electric Lighting for Gas Engine ", Nikola Tesla, 1898.
- AS. Patent 1,391,256 - Structure of induction coil - Arthur Atwater Kent - 1921
- AS. Patent 1,474,152 - Induced Coil - Arthur Atwater Kent - 1923
- AS. Patent 1,474,597 - Induced Coil - Arthur Atwater Kent - 1923
- AS. Patent 1,569,756 - Ignition Coil - Arthur Atwater Kent - 1926
- AS. Patent 1,723,908 - Ignition System - Ernst Alexanderson - 1929
References
External links
Source of the article : Wikipedia
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