Зажигание CDI — особая электронная система, which was called condenser ignition. Since the switching function in the node performs a thyristor, such a system is also often called a thyristor.
History of creation
The principle of operation of this system is based onusing a discharge capacitor. Unlike the contact system, the principle of interruption is not used in CDI ignition. Despite this, the contact electronics has a capacitor, whose main task is to eliminate interference and increase the intensity of spark generation at the contacts.
Individual elements of the ignition system CDIintend for accumulation of the electric power. For the first time such devices were created more than fifty years ago. In the 70s, rotary-piston-type engines began to be equipped with powerful capacitors and installed on vehicles. This type of ignition is in many respects similar to energy storage systems, but it also has its own characteristics.
How does CDI ignition work?
Принцип работы системы строится на использовании DC, unable to overcome the primary winding of the coil. A charged capacitor is connected to the coil, in which all the direct current is accumulated. In most cases, in a similar electronic circuit is quite high voltage, reaching several hundred volts.
Design
CDI electronic ignition consists of variousparts, among which there is necessarily a voltage converter, whose action is aimed at charging the storage capacitors, the storage capacitors themselves, electrical switch and coil. As an electric switch, both transistors and thyristors can be used.
Disadvantages of the capacitor discharge ignition system
Installed on cars and scooters ignitionCDI has several drawbacks. For example, the creators too complicated its design. The second minus can be called a short duration pulse level.
The virtues of a CDI system
Capacitor ignition has its ownadvantages, including a steep front of high-voltage pulses. This characteristic is especially important in cases where the installation of CDI ignition on the "IL" and other brands of domestic motorcycles. Candles of such transport are often filled with a large amount of fuel due to improperly tuned carburetors.
For the functioning of the thyristor ignition is notrequires the use of additional sources that generate current. Such sources, such as a rechargeable battery, are required only for a motorcycle factory using a kick-starter or an electric starter.
Ignition system CDI uses considerablepopular and often installed on scooters, chainsaws and motorcycles of foreign brands. It was hardly used for the domestic motor industry. Despite this, you can meet the ignition of the CDI in Java, cars GAZ and ZIL.
The principle of operation of electronic ignition
Diagnostics of the CDI ignition system is very simple, as is the principle of its operation. It consists of several main parts:
- Rectifying diode.
- Rechargeable capacitor.
- Ignition coil.
- Switching thyristor.
System layout may vary.The principle of operation is based on charging through a rectifier diode of a capacitor and its subsequent discharge to the step-up transformer by means of a thyristor. At the output of the transformer, a voltage of several kiloVolts is formed, which leads to the fact that an air space breaks through between the electrodes of the spark plug.
The whole mechanism mounted on the enginemaking it work in practice is somewhat more difficult. The CDI twin-ignition design is a classic scheme that was first used on Babette mopeds. One of the coils - low-voltage - is responsible for controlling the thyristor, the second, high-voltage, is charging. Using one wire, both coils are connected to ground. The output of the charging coil is fed to input 1, and the output of the thyristor sensor to input 2. Spark plugs are connected to the output 3.
Spark modern systems are served when reaching about 80 volts at input 1, while the optimal voltage is 250 volts.
Varieties of the scheme CDI
В качестве датчиков тиристорного зажигания может use a Hall sensor, coil or optocoupler. For example, the Suzuki scooters use a CDI circuit with a minimum number of elements: the thyristor opens in it a second half-wave voltage removed from the charging coil, while the first half-wave charges the capacitor through a diode.
Interrupter ignition set tothe engine is not equipped with a coil that could be used as a charging. In most cases, these motors install step-up transformers that raise the voltage of the low-voltage coil to the required level.
Model aircraft are not completedmagnet rotor, because it requires maximum savings in both the dimensions and weight of the unit. Often a small magnet is attached to the motor shaft, next to which a Hall sensor is placed. A voltage converter that boosts 3–9 V batteries to 250 V charges the capacitor.
Removal of both half-waves from the coil is possible only when using a diode bridge instead of a diode. Accordingly, this will increase the capacitance of the capacitor, which will lead to the amplification of the spark.
Ignition timing adjustment
Настройка зажигания осуществляется с целью receiving a spark at a certain point in time. In the case of stationary stator coils, the magnet-rotor is turned to the required position relative to the crankshaft pin. Keyways grooves sawn in those schemes where the rotor is attached to the key.
In systems with sensors, their position is corrected.
The ignition timing is given in referenceengine data. The most accurate way to determine a CPP is to use a car stroboscope. Sparking occurs in a certain position of the rotor, which is marked on the stator and the rotor. To the high-voltage wire of the ignition coil is attached to the wire clip from the included strobe. After that, the engine starts, and the tags are illuminated with a stroboscope. The position of the sensor changes until all the marks coincide with each other.
System malfunctions
CDI ignition coils extremely rarefail, despite popular opinion. The main malfunctions are associated with the combustion of windings, damage to the case or internal breaks and short circuits of wires.
The only way to disable the coil is to start the engine without connecting mass to it. In this case, the starting current passes to the starter through the coil, which does not withstand and bursts.
Ignition System Diagnosis
CDI system health check - prettya simple procedure that every car owner or moto owner can handle. The entire diagnostic procedure consists of measuring the voltage applied to the power coil, checking the mass supplied to the motor, the coil and the switch, and checking the integrity of the wiring leading to the system consumers.
The appearance of the spark on the spark plug of the engine directlydepends on whether the coil is powered from the switch or not. No electrical consumer can work without proper power. The check, depending on the result obtained, either continues or ends.
Outcomes
- The absence of sparks at the incoming power to the coil requires checking the high voltage circuit and ground.
- If the high-voltage circuit and the mass are fully functional, then the problems are most likely with the coil itself.
- In the absence of voltage at the terminals of the coil, it is measured at the switch.
- If there are voltage andits absence at the coil terminals is most likely due to the fact that there is no mass on the coil or the wire uniting the coil and the switch is broken - the break must be found and repaired.
- The absence of voltage on the switch indicates malfunctions of the generator, the switch itself or the induction sensor of the generator.
CDI Ignition Coil Testing Techniquecan be used not only for motorcycles, but also for any other vehicles. The diagnostic process is simple and consists in step-by-step testing of all parts of the ignition system with the determination of specific causes of malfunctions. To find them is quite simple if you have the necessary knowledge about the structure and principle of operation of the CDI ignition.
