About Distributor system of car

1. Presentation on Distributor system
Submitted By,
Rakibul
Sec-A, 8Th sem.
B.Tech (ME)

2. Distributor
• The distributor is the heart of the ignition system.
• Its three basic functions are
1. to trigger the firing of the ignition coil
2. to control timing advance
3. to route or distribute the coil's high voltage output to the individual
spark plugs.
• A distributor is an enclosed rotating shaft used in spark-ignition
internal combustion engines that have mechanically-timed ignition.
• The distributor also houses a mechanical or inductive breaker switch
to open and close the ignition coil's primary circuit.

3. Photo of a distributor

4. Description
• A distributor consists of a rotating arm or rotor inside the distributor
cap, on top of the distributor shaft, but insulated from it and the body
of the vehicle.
• The distributor shaft is driven by a gear on the camshaft on most
overhead valve engines, and attached directly to a camshaft on most
overhead cam engines.
• The distributor rotor directs the ignition coil's high voltage output to
the various spark plug terminals in the distributor cap.
• The condition of the cap and rotor are very important, as is the "air
gap" or distance between the tip of the rotor and cap terminals.

5. Various parts of distributor system

6. Camshaft
• The camshaft uses lobes (called cams) that push against the valves to
open them as the camshaft rotate.
• Springs on the valves return them to their closed position.
• This is a critical job, and can have a great impact on an engine's
performance at different speeds.

7. Operation of camshaft

8. Distributor cap
• The distributor cap is the cover that protects the distributor's internal
parts and holds the contacts between internal rotor and the spark
plug wires.
• The distributor cap has one post for each cylinder, and in points
ignition systems there is a central post for the current from
the ignition coil coming into the distributor.
• some engines have two spark plugs per cylinder, so there are two
leads coming out of the distributor per cylinder.

9. Rotor
• The rotor is present at the top of the distributor shaft.
• It is driven by the camshaft of engine and hence synchronized to it.
• The rotor is pressed against a carbon bush on the central terminal of the
distributor cap.
• The central terminal of the distributor is connected to the ignition coil.
• As the camshaft rotates, it rotates the distributor shaft. Due to this the
rotor attached to the distributor shaft also starts rotating.
• When the outer edge of the rotor passes to each internal plug terminal in
distributor cap, it fires each spark plug in correct sequence.

10. Contact Breaker
• It is mechanically designed breaker point. Its one end is fixed and
other end is movable.
• It is attached to the breaker assembly. Its main function is to makes
and breaks the primary circuit current.
• When the lobes of the cam pushes the cam follower of the contact
breaker, the points of the breaker which were touching each other
moves apart and breaks the primary current to flow through the
primary winding of the ignition coil.

11. DISTRIBUTOR WEAR
• Wear in the distributor drive gear can introduce play that can retard
timing.
• While worn distributor shaft bushings can result in erratic timing.
• Both conditions can affect engine performance, fuel economy and
emissions.
• If the distributor is worn, replacement is the only repair option.

12. Distributor Shaft
• It is a shaft which lies in the middle of the ignition distributor .
• It is connected directly to the camshaft of the engine through a gear
drive.
• It consists of a cam which is used to break the point of the contact
breaker.

13. Capacitor
• Its main function is store charge(electricity) and deliver once it stored
enough energy.
• It is used to prevent the overheating of the contact point of the
contact breaker.
• It helps in production of high voltage current by reverse the current
flow through the primary coil.

14. Spark Advance Mechanism
• It is a mechanism which is used to advance the spark in the spark
ignition engine.
• We have generally two types spark advance mechanism and i.e.
centrifugal advance spark and vacuum spark advance mechanism.
• Its main function is to ignite the fuel before the piston reaches the
TDC.
• This allows the complete burning of the air-fuel mixture with in the
cylinder and results in the maximum pressure on the piston.

15. Ignition System Distributor
• Its first job is to distribute the high voltage from the coil to the
correct cylinder. This is done by the cap and rotor.
• The coil is connected to the rotor, which spins inside the cap
• The rotor spins past a series of contacts, one contact per cylinder.
• As the tip of the rotor passes each contact, a high-voltage pulse
comes from the coil.
• The pulse arcs across the small gap between the rotor and the
contact (they don't actually touch) and then continues down the
spark-plug wire to the spark plug on the appropriate cylinder.

16. Working
• As the ignition distributor shaft rotates, it rotates the cam and rotor.
• When the cam pushes the cam follower of the contact breaker, the contact
points of the contact breaker opens and collapses the primary current
through the primary winding.
• This produces a high voltage current in the secondary winding. The high
voltage current produced is transfer to the distributor’s central terminal.
• The current from the central terminal reaches to the outer edges of the rotor
through the carbon bush. As the rotor comes in front of the internal terminal
of the spark plug in the distributor cap, the high voltage electrical pulses (or
surge) pass to the spark plug and it produces a spark within the cylinder
head.
• The distributor produces spark in each of the spark plug in in correct
sequence and in correct amount of time.
• In this way the ignition distributor works.

17. Battery ignition system

18. working

19. Applications
• Ignition distributor are used in battery ignition system, magneto
ignition system as well as in electronic ignition system.

20. Symptoms of a defective distributor
• One of the symptoms of a faulty distributor includes the shaking of
the vehicle while driving.
• This is often due to the rotor that does not rotate properly.
• A defective distributor also causes difficulty while starting the
automobile.
• The caps on the distributor are more prone to wearing out.
• A bad distributor cap will emit a high-pitched squealing noise when
the vehicle is started.

21. Modern ignition systems
• Newer ignition systems do not have distributors.
• They have multiple ignition coils, each dedicated to a spark plug or
one ignition coil for two spark plugs.
• The Engine Control Unit (ECU) controls the ignition system.
• Modern ignition system also known as distributor-less ignition
system.

22. THANK YOU