Here's how a distributor functions:
1. Mechanical Distributor:
a) Contact Breaker Points: In a mechanical distributor, a set of contact breaker points open and close repeatedly as the distributor rotates. These points interrupt the flow of current in the primary circuit of the ignition coil.
b) Distributor Shaft: The distributor shaft, driven by the camshaft or crankshaft, rotates in synchronization with the engine's operation.
c) Distributor Cap and Rotor: The distributor cap sits atop the distributor housing. Inside the cap are metal contacts connected to the spark plug wires. The rotor, mounted on the distributor shaft, rotates within the cap and sequentially makes contact with these terminals.
d) Ignition Timing: As the distributor shaft rotates, the rotor aligns with the corresponding spark plug terminals at the precise moment when ignition is required for each cylinder. This ensures that the spark plugs fire at the correct time, controlled by the engine's timing settings.
2. Electronic Distributor (Electronic Ignition System):
a) Hall Effect Sensor or Optical Sensor: Instead of mechanical contact breaker points, electronic distributors use a hall effect sensor (magnetic) or an optical sensor (light-based) to detect the position of the distributor shaft.
b) Electronic Control Module (ECM): The ECM receives the signals from the sensor and calculates the appropriate ignition timing based on various engine operating parameters.
c) Ignition Coil and Power Transistor: The ECM controls the ignition coil's primary circuit using a power transistor. When the transistor receives a signal from the ECM, it allows current to flow through the coil, generating a high voltage in the secondary circuit.
d) Ignition Timing: Just like in a mechanical distributor, the rotating shaft in an electronic distributor ensures that the rotor aligns with the appropriate spark plug terminals at the correct time, based on the signals provided by the ECM.
By precisely controlling the timing of spark ignition in each cylinder, the distributor ensures that the engine runs smoothly, efficiently, and delivers optimum performance. In modern vehicles, the function of the distributor has largely been replaced by more sophisticated electronic ignition systems such as direct ignition or coil-on-plug systems.
