The purpose of the ignition system is to generate a very high voltage from the 12- volt battery of the car and send it in turn to each spark plug, igniting the mixture of fuel and air in the combustion chambers of the engine.
The ignition system is responsible for generating the spark in the combustion chamber in a timely manner to start the car engine. In order to understand correctly how the ignition system works we need to study what happens in the combustion chamber:
The Four Times:
A gasoline combustion engine runs through cycles that can be divided into four times:
1. ADMISSIONAt this time the piston is at the top (the highest point where the piston can reach is called the PMS top dead center) and begins to lower the valves open and inject the fuel air mixture, suction that creates the piston in its descent causes the mixture or fuel to enter the cylinder. During this phase, the exhaust valve remains fully closed.
2. COMPRESSIONDuring this phase the mixture is compressed, for which the piston rises from the lowest point (to the lowest point where the piston can reach it is called the bottom dead center), to the highest of the cylinder, while the crankshaft It covers half a turn. The valves remain closed and the gases that have filled the cylinder occupy a smaller and smaller space. The maximum compression value is reached when the piston is at the end of the upward stroke.
3. EXPANSION OR EXPLOSION Itbegins when the piston is pushed down, from the Upper Dead Point (PMS) to the Lower Dead Point (PMI), by the gases left from the combustion of the mixture. In this phase, the inertia of the engine is not the one that produces the work, but it is the explosion itself that impels the piston, whose movement is transformed into work that will eventually move the car.
4. ESCAPEin this phase the piston pushes, in its upward movement, the combustion gases that leave through the exhaust valve that remains open. Upon reaching the maximum upper stroke point, the exhaust valve is closed and the intake valve is opened, the cycle being restarted.
Now, we know how the engine works and its four times, now what is the relationship between this and the ignition system? The answer is that the ignition system is responsible for generating the spark so that the explosion occurs in the third time, that is, in the first time the mixture of gasoline and air is injected, in the second time this mixture is compressed and in the third time the ignition system generates the spark and the explosion occurs and in the fourth time the gases are discarded.
All this makes us understand that it is not enough for the ignition system to generate the spark for the explosion, but that it must be generated at the right time, for example if the spark is generated in the first time the engine will not start because the mixture has not yet been compressed, and if a spark were generated in the fourth time that would disturb the operation of the engine since at that time there is no fuel mixture and nothing will happen, when any of these situations occur it is said that the engine NOT IN TIME.
So that the ignition can occur successfully and the spark is generated in a timely manner, the ignition system is designed with a series of components that ensure that the work is done in an orderly and synchronized way, let us now know the components of the Ignition system.
1. The CoilThe coil is composed of a rod-shaped iron core, consisting of sheets of magnetic sheet, on which the secondary winding is wound, formed by a large number of fine copper wire turns (between 15,000 and 30,000 ) properly isolated from each other and the core. Above this winding is wound the primary winding, formed by a few hundred coils of coarse thread, isolated from each other and from the secondary. The relationship between the number of turns of both windings (primary and secondary) is between 60 and 150.
When the ignition key is opened, the (+) current is connected to the coil; but, for this to work, you also need the (-) signal; This signal comes to you, through the work done by the distributor in one of its functions.
When the coil has both poles connected, the current flows into the primary winding, producing a strong magnetic field , within the circuit; but; when the connection is cut, a magnetic field collapse induces a high voltage current , within the secondary circuit.
The connection cut, or negative signal [-] is performed as a result of the function that make the components of the distributor, responding to the rotation or rotation , of its main axis; synchronized to the rotation of the camshaft.
The high voltage is exiting the turret of the coil, turning to through a cable to the distributor, which uses the same rotor, for distribution to the spark plugs.
HOW TO TEST IF THE COIL IS GOOD?With the tester on the ohm scale, we select the lowest, we place the tips of the tester on the terminals of the primary winding, that is to say where the positive wires are connected, which comes from the hinge and the negative wires that come from the ignition module, we take the reading of the tester and write down, so that the primary winding is good it must have full continuity , that is to say a resistance of less than 5 ohm.
Then we test the secondary winding for this with the tester on a 200Kohm high resistance scale we put one of the tester's tips on the negative of the coil, (where the power that comes from the module is connected) and the other tip at the output of High voltage, take the reading and there should be a resistance of no more than 15000 ohm if it is an oil coil and no more than 25000ohm if it is a dry coil.
2. The distributorThe distributor also called delco has evolved at the same time as the ignition systems did, now disappearing in the latest ignition systems. In breaker ignition systems, it is the most complex element and which has more functions, because in addition to distributing the high voltage as its name implies, it controls the current cut of the coil's primary by means of the breaker thus generating the high voltage.
It also fulfills the mission of advancing or delaying the ignition point in the cylinders by means of a "centrifugal regulator" that acts according to the number of revolutions of the motor and a "vacuum regulator" that acts in combination with the centrifugal regulator according to the engine load (depending on the accelerator pedal).
The distributor or delco is driven by the camshaft by turning the same number of turns as this and half as the crankshaft. The form of operation of the distributor is not always the same, in some the drive is by means of a pinion-pinion transmission, the distributor being left in a vertical position with respect to the camshaft. In others the distributor is driven directly by the camshaft without any transmission, leaving the distributor in a horizontal position
Vertical Distributor with respect to the camshaft.
E l distributor has two functions: one is to make the function of a switch [switch] high speed; and the other is to distribute the current it receives from the coil, between the spark plugs. E n other words distributor rotor, gives synchronized turns to the turns engine
3. Ignition ModuleIt is responsible for receiving the signal from the transmitter to proceed with the power cut [-] to the coil, thus replacing the traditional platinum (dots) and capacitor.
The ignition modules vary according to the make and model of the vehicle, here are some images of ignition modules.
The distributor cap and the rotor:
The distributor cap has a central connector, and around it the amount of as many connectors as cylinders has the engine. Well: the coil sends the spark to the central connector of the lid Inside the lid and widened in the distributor is the rotor The function of the rotor is to turn, but in its structure it has assembled a lamina from its center towards the end of its figure This lamina receives in its center the spark that sends the coil and at the end when making its spin distributes it, between the connectors that carry spark to the spark plugs. It is appropriate to mention: The rotor is possessed, and locks in the central axis; but; there is no connection between them; The spark should only jump into the spark plug connectors.
The spark that distributes the rotor, does so in an orderly manner, that is, at each turn it delivers the spark to the spark plug connectors, following only the order from right to left, or from left to right, depending on the way, in which of turns the distributor.
High Voltage CablesThese are the ones that take the spark from the coil to the distributor , and from the distributor to the spark plugs
The spark plugsThey are responsible for delivering the spark in the combustion chamber, supporting the heat of the explosion, which is generated as a result.
The Ignition System :Well we knew each of the components of the system now we will see how the complete set works:
THE IGNITION SYSTEMWhen you activate the ignition key on the first pass through a cable, the ignition coil and the ignition module are supplied, when you activate the key to start the engine it starts to rotate due to the starting action, and with the the rotor also rotates, the distributor rotor that emits a signal to the ignition module at a time when the current must be cut off to the ignition coil so that the high voltage spark is sent to the spark plugs, when the module cuts the current, The ignition coil generates the high voltage spark and sends it to the distributor, there the rotor distributes it to each spark plug according to the engine ignition time, and finally the spark plug generates the spark just at the moment when the piston is in the PMS thus producing engine ignition.
Ignition System FaultsThe engine will not start:
- Check: That the coil and the ignition module get current when passing the key in the first pass.
- Make sure the engine is on time and the starting order is correct.
- Make sure spark plugs reach.
- Make sure the rotor is in good condition.
- This can happen for several things:
- The ignition coil is failing.
- The ignition module is not cutting off the power.
- The pickup coil or sensors that signal the module are failing.
- No current is coming through the wire that powers the ignition coil.
Loss of motor strength
- On poorly synchronized.
- Spark plugs with excess use or poorly calibrated.
- Supply circuit of the primary coil circuit with voltage drops.
Engine pulls and with explosions at the intake and exhaust
- High voltage coil in poor condition.
- Spark plugs in bad condition.
- Automatic feed systems in poor condition.
- High voltage cables with current leakage to ground.
- High voltage cables changed from cylinder.
Electronic ignition system OperationThe electronic ignition system was developed to increase confidence and performance in the ignition system. This system operates very similar to the conventional ignition system, the difference is that the electronic systems lack plates, condenser and distributor cam. They are capable of delivering high voltage necessary to burn the air-gasoline mixture and in addition to this, electronic systems require less maintenance since they lack moving parts.
The electronic ignition system consists of a distributor-type magnetic button, an electronic control module, a double or single resistive ballast (regulating resistor) and a conventional coil. The remaining components of the system such as the distributor cap, the rotor and the spark advance mechanism, the spark plugs and spark plug wires are apparently similar to those of the conventional ignition system.
In the distributor there is a reluctor (gearwheel) and a pickup coil that replace the plates and the cam of the distributor of the conventional system. When the distributor arrow is rotating, the reluctor teeth approach the pickup coil, then at this moment, a signal is generated and transmitted to the control module. The control module connects to the transistorized source to allow or stop the flow of current in the primary winding of the coil.
When the teeth of the reluctor pass in front of the pickup coil, at this moment another signal is transmitted to the control module, to turn the source of the transistor on or off. This interruption of current flowing in the primary of the coil collapses in a magnetic field, which at the same time induces a high voltage in the secondary of the coil to ignite the spark plugs and burn the air-gasoline mixture in the combustion chamber.