Car Ignition Systems: Types and Functions

Posted on Dec 9, 2024 in Technology

Ignition Systems

Comparison of ignition systems.

Conventional Ignition

Offers good performance for normal requirements (capable of generating up to 20,000 sparks per minute, i.e. it can meet the demands of a 4-cylinder engine up to 10,000 RPM, but may have issues with 6 and 8 cylinder engines). The technical implementation of the switch, subjected to heavy loads by electric current passing through the primary coil, is a compromise between the switching behavior at low rotation speed and contact bounce at high speed. Issues due to condensation of water, dirt, combustion, etc. reduce the voltage available considerably.

Electronic Ignition

There is a higher voltage available at the spark plug, especially at high engine speeds. Using a small bounce breaker contacts, this system can work without disruption up to 24,000 sparks per minute. The switch is not subjected to heavy loads of power so that its duration is much greater, thus reducing maintenance and troubleshooting. The capacitor is deleted in this type of ignition.

Contactless Electronic Ignition

These models meet even greater demands. The switch is replaced by a pulse generator (“inductive” or “Hall effect”) that is maintenance-free. The number of sparks is 30,000. As a result of the lower impedance of the coils used, the rise of the high voltage is faster and, consequently, the ignition voltage is less sensitive to electrical leads.

Integral Electronic Ignition

By eliminating mechanical systems for spark advance correction and applying electronic components, more accurate advance curves are obtained, which can accommodate whatever law, complying fully with anti-pollution legislation. The maintenance of these systems is virtually zero.

Electronic Ignition for Fuel Injection

In the current systems of electronic fuel injection combined with an integral electronic ignition, many of the sensors are common and the self-control unit (ECU) governs both systems. Within these systems, some still use the distributor, while others delete it entirely (DIS static electronic ignition).

Capacitor Discharge Ignition

This system applies to motors operating at a high number of revolutions using high voltage plugs. The extremely rapid rise in voltage makes installation insensible to electrical leads. However, the spark is very short.

BOSCH manufacturer makes a particular classification of their ignition systems.

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Function of Ignition Systems

What is the ignition circuit? The power circuit used in gasoline engines is in charge of creating an electrical spark inside the cylinders to cause combustion of the air-fuel mixture at the appropriate time. The component in charge of generating a high voltage to cause the electrical spark is the “coil.” The coil is a transformer that converts the 12 V battery voltage into a high voltage on the order of 12,000 to 15,000 V. Once the high voltage is generated, a distribution element is needed to send it to each of the cylinders in a timely manner, taking into account that multi-cylinder engines work in a cycle with a given order for each cylinder explosion (e.g. engine 4 cylinder firing order: 1-3-4-2). The element that is responsible for distributing the high tension is the “distributor or Delco.” To cause the electrical spark within each of the cylinders, an item called “the spark plug” is needed, with as many spark plugs as the number of cylinders in the engine.

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In the diagram below we see a “conventional ignition” also called “ignition switch.”

Coil

There is little to say about the coil, as it is an element that gives few problems, and if it fails, it is replaced (no repair). The ignition coil is nothing more than an electrical transformer that converts battery voltage into a high voltage pulse that makes the spark jump between the electrodes of the spark plug.

The coil is composed of an iron core in the form of a bar, consisting of sheets of magnetic plate on which is wound the secondary winding, comprising many turns of fine copper wire (between 15,000 and 30,000) properly insulated from itself and the core. On top of this winding is wound the primary winding, consisting of several hundred turns of thick wire, insulated from each other and the secondary. The relationship between the number of turns of both windings (primary and secondary) is between 60 and 150.

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The set consisting of both windings and core is surrounded by a magnetic plate and fill mass, so as to maintain it perfectly inside the metal container or casing of the coil. Generally, they are immersed in a bath of high dielectric oil, which acts as an insulator and coolant.

Although essentially all the coils are equal, there are some special characteristics. One of these is the one that has two primary windings. One of the windings is used only during start (auxiliary primary winding), once the engine is launched, this winding is disconnected. This system is used to compensate the voltage drop that occurs during startup when the engine is powering the starter motor, which is known, this device consumes lots of electricity. The auxiliary primary winding is only used at boot time, using the switch (I) (C ignition) that puts it in circuit, this increases the magnetic field and hence the stress on the secondary winding the coil increases. Once started the engine at the time that is left to operate the ignition key, switch (I) opens and disconnects the auxiliary primary winding, leaving in place only the primary winding.

To mitigate the effects of voltage drop when the engine is started, some coils have a resistance (R) at the entrance of the primary winding of the coil connected in series with, which is taken out of service at the time of startup and when the engine is already running.

The Distributor

The distributor, also called Delco, evolved while they did on systems, now coming to disappear in the last ignition systems. In the breaker ignition systems, it is the most complex and fulfills more functions.

In addition to distributing the high voltage as its name suggests, it controls the power failure of the primary winding through the switch, thus generating the high voltage. It also fulfills the mission of advancing or delaying the point of ignition in the cylinders by a “centrifugal governor” who acts in accordance with the number of engine revolutions and a “regulatory vacuum” that acts combined with the centrifugal governor as the engine load (as this more or less set foot on the accelerator pedal). The Delco distributor is driven by the camshaft, turning the same number of turns east and half the crankshaft. The distributor drive is not always the same; at about the drive is transmitted through a pinion-pinion, leaving the dealer in a vertical position with respect to the camshaft (right figure). In other distributors, it is directly driven by the camshaft without any transmission, leaving the dealer in a horizontal position (figure below).

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Ignition with Electronic Help

The conventional ignition switch benefits from the application of electronics in the automotive world, thus saving the inconvenience of the ignition switch, which are: the occurrence of misfire at high revs the engine and premature wear contacts switch, which requires putting the vehicle through the shop every few miles. This type of power is called “using electronic ignition” (right figure), the switch is no longer in charge of cutting the power to the coil, this is done by a transistor (T). The switch only has control functions so that it does not require putting the vehicle through the workshop so often, it eliminates the capacitor is no longer necessary and the failure at high speed improved to some extent and there comes a time when switch contacts causing the usual bounce misfire.

Contactless Electronic Ignition

An important development came to the Delco distributor caused by the substitution of the “switch” mechanical element, by a “pulse generator” which is an electronic element. With this type of distribution was achieved on a system called “electronic ignition without contacts” as shown in the diagram in figure below.

The distributor equipped with “pulse generator” is equal to that used in conventional ignition systems, i.e. with the elements of change of ignition point (“centrifugal regulator” and “regulatory vacuum”) and most constructive elements. The fundamental difference is in replacing the switch by a pulse generator and the elimination of the condenser.

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The pulse generator can be of type: “inductive” and “Hall effect.”

The inductive pulse generator is one of the most used in power systems. It is located on top of replacing the switch distributor, the electrical signal generated is sent to the electronic unit that manages the power failure of the primary winding of the coil to generate the high voltage that is sent to the spark plugs. The pulse generator is constituted by a conference call rotor blades, magnetic steel, which during its rotation produces a variation of the magnetic flux permanent magnet thereby inducing a voltage in the coil being delivered to the electronic unit. The wheel has blades as many cylinders does the engine and as it approaches each of the induction coil, the tension is rising ever more rapidly until it reaches its maximum value when the coil and the blade are facing (+ V). With distance along the blade rotation, the voltage changes very rapidly and reaches its maximum negative value (-V). This voltage change occurs on and the momentum thus originated in the dealer being delivered to the electronic unit. When the blades of the wheel are not faced with the induction coil ignition does not occur.

The “Hall effect” pulse generator is based on creating a magnetic barrier to periodically interrupt, it generates an electrical signal that is sent to the electronic control unit determines the flash point.

This generator consists of a fixed part consists of a Hall integrated circuit and a permanent magnet with conductive parts. The mobile part of the generator is formed by a drum shutter, which has a series of screens so as to have the engine cylinders. When a shutter screens lies in the gap of the magnetic barrier, preventing magnetic field deflects the magnetic field passes to the integrated circuit. When the shutter drum screen leaves the gap, the magnetic field is detected again by the integrated circuit. Just then the ignition occurs. The width of the screen determines the driving time of the coil.

To distinguish whether a distributor has a pulse “inductive” or “Hall effect” only have to look at the number of wires from the distributor to the ECU electronics. If it takes only two cables is a pulse generator dealer “inductive” in case of carrying three wires were a pulse generator distributor for “Hall effect.”

For the proper functioning of the pulse generator should check the distance between the fixed and mobile part of the generator, which must always maintain the distance that the manufacturer recommends.

Integral Electronic Ignition

Once again the distributor develops while the system is improved this time on items disappear correction ignition timing advance (centrifugal regulator “and” regulatory vacuum “) and the pulse generator, the to be replaced by electronic components. The dealer in this type of ignition is confined to distribute, as its name indicates, the high voltage from the coil to each spark plug.

The type of ignition system that we refer to now is called “integral electronic ignition” and their interesting features compared to earlier ignition systems are using:

An inductive pulse generator

It consists of a ring gear that is coupled to the engine flywheel and a magnetic sensor in front of her. The sensor consists of a permanent magnet is wound around a coil which induces a voltage each time you pass a tooth sprocket front of him. As a result, detects the rotational speed of the engine. The crown gear has a tooth and its corresponding hole, wider than the other, located 90 ° before each position pms When you pass this tooth in front of the sensor voltage is induced is higher, which indicates to the electronic control the piston reached the pms 90 ° of rotation later.

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A depression sensor

Its function is to transform the value of depression is in the intake manifold into an electrical signal that is sent and interpreted by the electronic control unit. Its constitution is similar to that used in the distributors (“regulatory vacuum”), the difference in his way of working is now limited to a core move that travels inside the coil of an oscillator whose frequency varies according to power of the position occupied by the core with respect to the coil.

The electronic control unit

The unit of “integral electronic ignition” receive signals from the sensor or pulse generator to determine the number of engine rpm and its position with respect to pms, also receives sensor signals from depression to know the engine load. In addition to receiving these signals takes into account the temperature of the engine by a sensor that measures the temperature of the coolant (water off) and a sensor that measures intake air temperature. With this information the control unit calculates the point of ignition advance.

In these systems on some engines include a sensor that is installed chopped near the combustion chambers, capable of detecting at start of dive. When the torque is high (e.g. going up a slope) and an engine speed is low, too much advance at power tends to produce a detonation at the wrong called “crushed” (connecting rod bearing noise). To correct this phenomenon is necessary to reduce engine performance by adopting a lower advance curve The sensor has to be chopped a microphone that generates a small voltage when the piezoelectric material that is built has a deformed caused by the detonation of the mixture inside the engine cylinder.

Ignition Systems

Electronic ignition for fuel injection.

Existing systems for electronic fuel injection combined with an integral electronic ignition drawing many of the sensors that are common and own electronic control unit ECU to govern both systems.

There are two types of electronic ignition: conventional (figure below left) with distributor, in which the ECU determines the spark leap instantly into each cylinder and the dealer deals the spark to each spark plug firing order appropriate and static electronic ignition (DIS), which suppresses the dealer. DIS ignition system (figure below right) uses a double coil with four high voltage outputs.

1 – UCE.
2 – Coil.
3 – or Delco distributor.
4 – Spark Plugs.
5 – amp.
6 – double coil with 4 outputs.
Amplifier has the function of amplifying the control signal that instructs the ECU to the coil.

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Using this type of coil has the disadvantage of the lost spark. As we know these coils are sparks of two cylinders at the same time, when only one is needed, the missing spark can cause an explosion in the admission in those large engines valve crossing.

To avoid this problem by using a coil for each cylinder (see figure below). all controlled by the ECU, also has the advantage of this system to remove high-voltage cables that connect the coils to the spark plugs.

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Spark Plugs

At the end of this article, let this element is responsible for breaking the electric spark between the electrodes to ignite the fuel-air mixture located within the combustion chamber in the engine cylinder. The most important part of the spark plugs are the electrodes which are subjected to all chemical and thermal influences that develop within the combustion chamber, significantly affecting the quality of the spark and hence on the ignition. To protect the electrodes of the adverse conditions in which to work and therefore extending its duration, are used in manufacturing special alloys based on nickel, but manganese, silicon and chromium for the purpose of raising the working temperature limit.

Heat range spark plugs is the most important feature of bulbs and is a function of the thermal conductivity of the insulator and the electrodes also depends on the design of the insulation (length and width at the bottom, next to the electrodes). Overall heat range spark plugs should be higher, the higher the power per liter of engine displacement.

According to the heat range spark plugs are divided into:

Colder plug.

The spark plug of high grade cold or heat is formed by an insulator generally short and thick at the bottom so that heat dissipation is carried out more quickly using high-compression engines (greater than 7 / 1) and high speed.

Hot plug

The hot spark or low-grade thermal insulator is long and pointed, evacuating the heat more slowly, and is used in low compression engines (less than 7 / 1) and low speed.

As you can see this classification of the spark plugs today and for many years is not feasible under the circumstances extremely opposed engine operating in urban traffic (slow speed and many starts and stops), or on the highway (high speed maintained for a long time.) It was necessary to expand the range of degree heat to get a plug that works well on both conditions, so I come to the spark plugs “multigrade”, covering various degrees heat.

If you unscrew the spark plug of the head and look at the state and color of the electrodes, we know that the engine is working conditions, for example, burning too much oil, and so on in advance.

Types of plugs:

Standard candles: The electrodes protrude from the plug, have good contact with the mixture and wear large reserve burn, being used in production vehicles. The spark plug of figure (A). has an easy adjustment of the electrodes, not the (B) which makes available the adjustment of the electrodes, but has the advantage of facilitating the ignition with the engine idling.

The spark plug (C) is used in two-stroke engines with easy contact with the mixture, a large reservation to wear and easy starting at idle, but does not allow any adjustment.

Special Spark: among them we have the internal electrode (not protrude from the plug), used in competition vehicles. Not present a risk of overheating, no reservation to wear burn or allow adjustment of the electrodes.

Another special plug is the mass of a platinum electrode, which has several advantages, including their resistance to chemical attack from the combustion of the mixture, so that the length in miles of these plugs is much higher. The distance between electrodes can regulate. The disadvantage of these candles is that they are quite expensive.

To change the distance between electrodes, we must bear in mind that the setting is always on the ground electrode and not on the center electrode to prevent deterioration of the porcelain insulator. The distance between the electrodes will be 0.6 to 0.65 mm. checked with a feeler gauge.