The purpose of the ignition system is to create a spark that lights the fuel-air mixture in the engine cylinder. This should be done in the right moment and at a speed of up to several thousand times per minute, for each cylinder in the engine. If the occurrence of a spark deviates only to a small fraction of a second, the engine will work poorly or not work at all.
The ignition system sends extremely high voltage to the candle on each cylinder, during the piston is in the upper dead point, compression tact. There is a gap between the central and lateral electrodes of the spark plug in which high voltage slides. This is where the spark arises.
The voltage that is supplied to the spark plugs is located somewhere between 20,000 and 50,000 volts and above. The operation of the ignition system consists in the production of high voltage from the 12 volt source and submit it to each cylinder in a certain order, exactly at the right time.
Let’s see how it is done.
The ignition system solves two problems. Firstly, it should create a fairly high voltage (20,000 +) so that the arc occurs through the gap of the spark plug, thus creating the spark is strong enough to light the fuel-air mixture. Secondly, it must control the deadlines so that the spark arises at the right time and send it to the desired cylinder.
The ignition system consists of two sections, the first and second circuit. The low voltage of the primary circuit operates from 12 to 14, 5 volts and is responsible for generating the signal to the spark plugs at the exact time and is to send the signal to the ignition coil. The ignition coil is a component that converts a 12 volt signal into a high voltage 20,000 + volt. As soon as the voltage was increased, it goes to the secondary circuit, which then directs the charge to the desired light of the ignition at the right time.
Fundamentals.
All cars work on direct current, or from direct current. This means that the current moves in one direction, from the positive terminal of the battery to the minus terminal of the battery. In the case of a car, the minus terminal of the battery is connected by a cable directly to the body and engine block. The body and any metal components in contact with it is called the Earth. This means that the scheme that must be sent back to the current minus side of the battery can be connected to any metal part of the car.
Now back to the ignition system. The basic principle of the ignition system has not changed over more than 75 years. What has changed is the method by which the spark is created and how it is distributed.
There are currently three different types of ignition systems. In the mechanical ignition system, the mechanical and electric parts were used, and electronics were not used. When understanding the mechanical system, it will be easier to understand the new electronic and computer ignition systems, so do not miss it. The electronic ignition system began its way in the production of cars in the early 70s and became popular because it provides better control and increased the reliability of the system. Finally, the ignition distribution system with computer control became available in the mid-80s. This system does not contain moving parts, so reliability was significantly improved. Most of these systems do not require maintenance, except replacing the spark plugs.
Let’s look in detail each system and see how they work.
Mechanical ignition system.
Distributor (Trumbler) Center for the mechanical ignition system and solves two problems. Firstly, he is responsible for the launch of the ignition coil to create a spark at a certain moment. Secondly, the Trumbler is responsible for the direction so that the spark arises in the right cylinder (which is why it is called the distributor.)
When you insert the key to the ignition lock and turn the key to the launch position, you send the current from the battery, through the wire, directly to the positive (+) side of the ignition coil. Inside the coil, a series of copper windings, which are wound around the coil and emerge from a negative (-) side of the coil. From there, the conductor takes the current to the trambler and connected to a special button on / off, called points. When the points are closed, the current goes directly to the ground. When the current flows from the ignition lock, through the reel windings, to the ground, it forms a strong magnetic field inside the coil.
The points consist of a fixed contact point, which is attached to the plate inside the trambler, and the mobile contact -mounted moving points installed at the end of the spring -loaded lever diverge 4, 6 or 8 times per full revolution (depending on the number of cylinders in the engine) of the rotating shaft inside the trambler. The rampart of the trambler rotates to the beat of the engine, makes one full revolution for every two engine speeds. When the shaft rotates, the cam pushes the contacts to open and close them. Each time the contacts are open, the flow of the current is interrupted through the reel, thereby the magnetic field collapses and high voltage is released through the secondary windings of the coil. This overvoltage comes out of the upper part of the coil and through the high -voltage coil wires.
Now we have a voltage necessary for the spark of the spark plug, but we still have to direct it to the correct cylinder. The central wire goes from the coil directly to the center. Under the lid is a rotor, which is installed on the upper part of the rotating shaft. The rotor (runner) has a metal strip at the top, which is in constant contact with the center of the covers of the trambler. He receives a high impulse voltage from the coil and sends it at the other end of the rotor, which rotates alternately in contact with each terminal of the spark plug inside the lid. Rotating the shaft, the rotor sends the voltage to the desired wire of the spark plug, which in turn sends it to the spark plugs. The voltage enters the spark plugs to the central electrode, then it slips through the gap on the tip of the spark plug, creating a spark suitable for ignition of the fuel-air mixture inside this cylinder.
The description that you just read is a simplified version, but should be useful for visualizing the process, we missed several things that make up this type of ignition system. For example, we did not talk about the capacitor, which is connected to the contacts, and we are not talking about the early ignition system. Let’s look at each section and study it in more detail.
Egnition lock.
There are two separate schemes that go from the ignition lock to the coil. One circuit passes through the resistor in order to remove about 15%, the voltage to protect contacts from premature wear. Another circuit sends the full voltage of the battery to the coil. The only time that this scheme is used during launch. Since the starter consumes a significant amount of energy to start the engine, additional voltage is necessary to power the coil. Therefore, when the key is turned into a spring -loaded launch position, the full voltage of the battery is used. As soon as the engine started up, the driver releases the key to the working position, and directs the current through the resistor to the primary winding of the coil.
Sparklor distributor (Trumbler).
When removing the cover of the trambler, you will see contacts and capacitor. The capacitor can store a small amount of current. When the contacts begin to open, the current flowing through contacts is looking for alternative ways to the Earth. If there were no capacitor, the current will try to jump through the interval between the contacts, since they begin to open. To allow, the contacts will quickly burn out, and you would hear interference on the automobile radio receiver. To prevent this, the capacitor acts as a path to the ground.. Since the arches through the contacts are eliminated, the contacts will last longer and there is no interference on the radio.
Contacts require periodic adjustment so that the engine works more efficiently. This is because the friction of the fist and contact wear out the surface of contact and over time the gap between the contacts changes. There is a way to measure the gap to see whether contacts need to be needed. It consists in measuring the clearance between open contacts.
Adjustment is carried out with an unemployed engine and a tile -removed engine with a lid. It is necessary to weaken the motionless contact and move it a little, then measure the gap using the probe, and tighten it in the right position.
Ignition coil.
The healing coil is nothing more than an electric transformer. It contains primary and secondary windings. The primary winding contains from 100 to 150 turns of heavy copper wires. This wire should be isolated so that the voltage does not jump from the cycle to the cycle (short circuit). If this happened, she will not be able to create the primary magnetic field required. The primary wire scheme passes in a coil through a positive conclusion, the cycles around the primary winding, and goes through a negative conclusion.
The secondary winding diagram contains from 15,000 to 30,000 turns of thin copper wire, which should also be isolated from each other. Secondary winding sits inside the primary winding. To further increase the magnetic field of the coil around the winding, it is wrapped in soft iron. To resist the heat, the coil is filled with oil.
Ignition coil is the heart of the ignition system. A strong magnetic field is created through the coil.
The ignition is an angle.
The spark arises at the moment when the contacts open, with the help of a fist rotating in the trimbler.
The exact installation of contacts is important for the engine for proper operation. It is necessary to change the time of sparking, depending on the revolutions and the load of the engine. If we can move the site on which the contacts are located, we could change the time of spark in accordance with the needs of the engine.
Why do we need an early ignition when the engine increases speed?
Когда возникает искра на свече зажигания в камере сгорания, она воспламеняет все топливо и смеси на кончике свечи зажигания. The fuel that surrounds the candle is lit. This fuel continues to expand at a certain speed, which is always the same, regardless of engine speed. It does not push the piston down until it fills the combustion chamber and has no way out. So, the faster the engine rotates, the earlier the caviar should arise, to obtain maximum power.
There are two mechanisms that allow you to change the ignition angle: centrifugal and vacuum.
The centrifugal system for changing the angle of the urgent in relation to engine speeds uses a couple of spring -loaded counterweights, which, under the influence of centrifugal force, change the position of the fist to the shaft of the trambler. When the shaft rotates faster, the counterweights stretch, overcoming the force of the spring, changing the position of the upper shaft, in relation to the lower, as a result of which we get an early ignition.
Vacuum mechanisms work by changing the position of contacts in relation to the Trambler body. The engine produces a vacuum while working with a closed throttle. In other words, your leg is not on the gas pedal. In this situation, little fuel and air enters the combustion chamber.
Vacuum mechanisms use diaphragms connected to the vacuum line that move the site on which the contacts are located. When the throttle is open, the vacuum acts at the diaphragm, which in turn moves the site with contacts, thus we get an early ignition.
Ignition wires.
These cables are designed to work from 20,000 to more than 50,000 volts, sufficient stresses to throw you across the room if you encounter it. The work of the wires is to transfer this enormous power to the spark plug without leakage. The spark plug wires should withstand the heat of the engine, as well as sharp weather changes. The ignition wires are quite thick, but most of the thickness is insulated, and in the center a very thin conductor. The insulation lends itself to the heat of the engine and begins to harden, the cracks form, dry, or break. When this happens, they will not be able to provide the necessary voltage to the spark plugs. To eliminate this problem, the ignition wires must be replaced.
The ignition wires go from the tile cover to the spark plugs in a certain order. This is called “ignition” and is part of the engine design. Each spark plug should work at the end of the compression tact. Each cylinder has a compression stroke at different times, so it is important that a separate spark plug transmits the voltage to the desired cylinder.
For example, the procedure for operating cylinders on the V8 engine is 1, 8, 4, 3, 6, 5, 7, 2. The cylinders are numbered from the front to the rear with the cylinder No. 1 on the front left of the engine. So cylinders on the left side of the engine with numbers 1, 3, 5, 7, and on the right side with numbers 2, 4, 6, 8. On some engines, the right side is 1, 2, 3, 4, and on the left side 5, 6, 7, 8. Repair manual will show you the correct operating procedure for engine cylinders.
Spark plug.
The last link, in the chain of the ignition system, candles.
Modern spark plugs fulfill their task for a very long period and do not require maintenance. These electric miracles are of different configurations and thermal ranges, for proper operation in this engine.
The thermal range of spark plugs dictates whether the temperature will be sufficient to burn any rest that is collected on the tip of the candle, but not hot, so as not to cause early ignition in the engine. Early ignition occurs when the spark plugs are heavily heated and light the fuel-air mixture prematurely, until the spark arises. Most of the spark plugs contain a resistor to suppress the radio interference. The gap on the spark plugs is also important and should be installed before the spark plugs are installed in the engine. If the gap is too large, there may not be a spark. If the gap is too small, the spark may not be enough to light a poor fuel-air mixture, which also leads to interruptions.
Electronic ignition system.
(from the 1970s to the present day)
This section will describe the main differences between the early mechanical system and more new electronic systems. If you are not familiar with how the ignition system works in general, I strongly recommend that you first read the previous section of the mechanical ignition system.
In the electronic ignition system, contacts and capacitor were replaced by electronics. In these systems there are several ways used to replace contacts and condenser to cause the discharge of the coil. One way, a metal wheel with teeth is used, as a rule, one for each cylinder. This is called an anchor. Magnetic pulse, when the tooth passes, sends a signal to the control unit to the ignition coil.
Another system uses a hall sensor and a rotor with slots to send an electronics signal, which has come for the launch of the coil. These systems still use the ignition aids and the trambler mechanism.
The advantage of this system, in addition to the fact that it does not need to maintain, is that the control module can operate much higher than the primary voltage than mechanical contacts. So the coil can create a much better spark, about 50,000 volts instead of 20 thousand volts on a mechanical system. In this system there is only one wire from the ignition lock to the coil, the primary resistor is no longer needed.
On some cars, the control module is installed inside the trambler, instead of contacts. On other designs, the control module is installed outside the trambler with external wiring.
Higher voltage, allow the use of a wider gap on the spark plugs. A more powerful spark provides ignition of a poorer mixture, which has improved fuel efficiency.
The early electronic systems were limited and did not have computing capacities, so that the lead was regulated using centrifugal and vacuum mechanisms.
On later systems, inside the trambler is empty and all processes are carried out using a sensor, which monitors the position of the gear wheel on the crankshaft or camshaft. These devices are called the crankshaft position sensors or the distribution shaft position sensors. In these systems, the operation of the tummer is exclusively for the distribution of the spark on the desired cylinder using the tile and rotor cover. The computer processes the advance angle required for the uninterrupted operation of the engine.
Electronic ignition distribution system.
(from the 1980s to the present day).
New systems came from the mechanical system (Trambler). The electronic ignition distribution system is completely not attended, without moving parts. These systems are fully controlled by an on -board computer. Instead of a trambler, several coils are used, each of which serves one or two spark plugs. A typical 6-cylinder engine has 3 coils that are installed together in the “package”.,
The spark plug wire leaves each side of individual coils and goes to the appropriate spark plugs. One spark plug works on the compression stroke, for ignition of the fuel-air mixture, while other spark plugs, they are inactive on the tact of the release. On some cars, there are separate coils for each cylinder installed directly on the spark plug. This design completely excludes high voltage wires, for even greater reliability. Most of these systems use candles that are designed for a large run, which reduces the cost of maintenance.