Electronic Ignition Systems: Types and Advantages
Electronic Ignition Systems
Findings
First, clean and adjust the spark plugs. Clean the high-tension wires, distributor cap, and coil. Check the spark plugs while the engine is running. Connect a voltmeter to the positive terminal of the coil; it should show the same voltage as the battery. Verify that impulses are reaching the module by connecting an AC voltmeter. Check the pulse generated by the coil with an ohmmeter connected at both ends; it should indicate a resistance value. Test continuity. Connect the ohmmeter between one of its connectors and ground; the value should be infinite. A lower value indicates a deviation in the coil’s ground connection.
Electronic Ignition Assistance
The breaker no longer directly interrupts the current to the coil; this is now handled by a transistor. The breaker only has control functions, eliminating the need for a condenser. Using a transistor as a switch allows for handling much higher currents than a breaker, enabling the use of coils with primary windings exceeding 10A.
Advantages over Conventional Ignition:
- Modern switches support currents up to 5A, while transistors can handle up to 15A.
- Higher current capacity allows for ignition coils with fewer primary windings (low impedance). This reduces the time to reach maximum primary current when the breaker closes, as the coil’s inductance is lower. The magnetic field builds up much faster.
- The breaker only handles the transistor’s base current (300-500mA), eliminating the classic “sparking” seen in conventional ignition. The condenser is no longer needed, as the transistor performs the rapid current cut-off function.
Centrifugal Regulator
This device uses two eccentric weights that move on a plate. The weights rotate on a pivot and are connected to the cam by springs. The entire assembly is driven by the distributor shaft. At idle, the springs hold the weights at rest. As engine speed increases, centrifugal force moves the weights outward, rotating the cam sleeve. This advances the distributor’s rotation, causing the cam to open the breaker contacts earlier than at idle. The maximum advance angle is 30° (measured at the crankshaft).
Vacuum Regulator
The vacuum advance adjusts ignition timing based on engine load. It acts on the breaker plate, rotating it counterclockwise relative to the cam. This causes the contacts to open earlier, providing ignition advance.
Integral Electronic Ignition
This system uses:
- An engine speed sensor (replaces the centrifugal regulator).
- A pressure sensor (measures engine load and replaces the vacuum regulator).
Advantages:
- Better ignition timing control based on engine demands.
- Ability to include control parameters.
- Improved starting, idling, and fuel consumption.
- Collection of more operating data.
- Knock regulation capability.
Operation:
The vacuum sensor signal indicates engine load. This signal, along with engine speed, creates a three-dimensional ignition timing map. For each speed and load point, the optimal ignition timing is determined.
Pulse Induction Ignition
The breaker in the distributor is replaced by a pulse generator. These pulses are sent to an additional module, which determines the primary current cut-off timing and spark plug firing. The permanent magnet and induction coil (with its core) form the stator (a fixed unit). Inside, the rotor (part of the distributor shaft) rotates, replacing the cam in conventional ignition.
Operation:
Rotor rotation changes the gap between the rotor teeth and the stator, causing magnetic flux variation. This induces an alternating voltage in the coil, proportional to the rotational speed (0.5-100V).
Hall Effect Ignition
This system uses a magnetic barrier to periodically interrupt a magnetic field. This generates an electrical signal sent to the electronic control unit, which determines the ignition timing. The Hall effect distributor has a shutter drum (made of diamagnetic material) attached to the distributor shaft, with slots corresponding to the engine cylinders. The shutter is placed between a semiconductor crystal and an electromagnet. When a metal screen is between the semiconductor and the electromagnet, the magnetic field is deflected. When a slot is between them, the semiconductor receives the magnetic field and generates the “Hall effect.” As the engine rotates, the shutter opens and closes the magnetic field, generating a square wave signal sent to the ignition module. The Hall sensor is powered by the control unit (7.5V).