All Topics  
Distributor

 
Distributor

 
   Email Print
   Bookmark   Link
 

 

Distributor
 
 
  Topics Distributor Topic Home

A distributor is a device in the ignition system
Ignition system

An ignition system is a system for igniting a fuel-air mixture. It is best known in the field of internal combustion engines but also has other applications, e.g....
 of an internal combustion engine
Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...
 that routes high voltage
High voltage

The term high voltage characterizes electrical circuits, in which the voltage used is the cause of particular safety concerns and insulation requirements....
 from the ignition coil
Ignition coil

An ignition coil is an induction coil in an automobile's ignition system which transformer the Car battery 12 volts to the thousands of volts needed to spark the spark plugs....
 to the spark plug
Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed Particulate gasoline by means of an electric spark....
s in the correct firing order
Firing order

The firing order is the sequence of power delivery of each cylinder in a multi-cylinder reciprocating engine. This is achieved by sparking of the spark plugs in a gasoline engine in the correct order, or by the sequence of fuel injection in a Diesel engine....
.






Discussion
Ask a question about 'Distributor'
Start a new discussion about 'Distributor'
Answer questions from other users
Full Discussion Forum



Encyclopedia


Distribcap
Breakerpoints
A distributor is a device in the ignition system
Ignition system

An ignition system is a system for igniting a fuel-air mixture. It is best known in the field of internal combustion engines but also has other applications, e.g....
 of an internal combustion engine
Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...
 that routes high voltage
High voltage

The term high voltage characterizes electrical circuits, in which the voltage used is the cause of particular safety concerns and insulation requirements....
 from the ignition coil
Ignition coil

An ignition coil is an induction coil in an automobile's ignition system which transformer the Car battery 12 volts to the thousands of volts needed to spark the spark plugs....
 to the spark plug
Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed Particulate gasoline by means of an electric spark....
s in the correct firing order
Firing order

The firing order is the sequence of power delivery of each cylinder in a multi-cylinder reciprocating engine. This is achieved by sparking of the spark plugs in a gasoline engine in the correct order, or by the sequence of fuel injection in a Diesel engine....
. The first high-tension distributor was developed around 1904, independently by Napier
Napier & Son

D. Napier & Son Limited was a Great Britain engine and brass era automobile manufacturer and one of the most important aircraft engine manufacturers in the early- to mid-20th Century....
, Bouton
Bouton

Bouton is a French language word that can be translated to button.It may refer to:* De Dion-Bouton, a French automobile manufacturer* Synaptic bouton, part of a chemical synapse...
, and Winton
Winton

Winton is the name of:...
.

It 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 ("earth"). The distributor shaft is driven by a gear on the camshaft
Camshaft

The camshaft is an apparatus often used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve....
. (Usually the distributor shaft extends to also drive the oil pump
Oil pump

Oil pump may refer to:* A Submersible pump, often used to pump oil out of wells* A Pump jack, often used to pump oil out of wells* An Oil pump , a part of the lubrication system that transports engine oil...
.) The metal part of the rotor contacts the central high voltage cable from the coil via a spring loaded carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 brush
Brush (electric)

A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electric motors, alternators and electric generators....
. The metal part of the rotor arm passes close to (but does not touch) the output contacts which connect via high tension cables to the spark plug
Spark plug

A spark plug is an electrical device that fits into the cylinder head of some internal combustion engines and ignites compressed Particulate gasoline by means of an electric spark....
 of each cylinder
Cylinder (engine)

A cylinder is the central working part of a reciprocating engine, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically casting from aluminum or cast iron before precision features are machined into it....
. As the rotor spins within the distributor, electrical current is able to jump the small gaps created between the rotor arm and the contacts due to the high voltage created by the ignition coil.

The distributor shaft has a cam
Cam

A cam is a projecting part of a rotating wheel or shaft that strikes a lever at one or more points on its circular path. The cam can be a simple tooth, as is used to deliver pulses of power to a steam hammer, for example, or an Eccentric disc or other shape that produces a smooth reciprocating motion in the follower which is a lever...
 that operates the contact breaker
Contact breaker

A contact breaker is a type of electrical switch, and the term typically refers to the switching device found in the distributor of the ignition systems of spark-ignition internal combustion engines....
. Opening the points causes a high induction voltage in the system's ignition coil
Ignition coil

An ignition coil is an induction coil in an automobile's ignition system which transformer the Car battery 12 volts to the thousands of volts needed to spark the spark plugs....
.

The distributor also houses the centrifugal advance unit: a set of hinged weights attached to the distributor shaft, that cause the breaker points mounting plate to slightly rotate and advance the spark timing with higher engine rpm
Revolutions per minute

Revolutions per minute is a units of measurement of frequency: the number of Turn completed in one minute around a rotation around a fixed axis....
. In addition, the distributor has a vacuum
Vacuum

A vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty," but in reality, no volume of space can ever be perfectly empty....
 advance unit that advances the timing even further as a function of the vacuum in the inlet manifold
Manifold (automotive engineering)

In automotive engineering, an intake manifold or inlet manifold is the part of an engine that supplies the fuel/air mixture to the cylinder s....
. Usually there is also a capacitor
Capacitor

A capacitor or condenser is a Passive component electronic component consisting of a pair of electrical conductor separated by a dielectric....
 attached to the distributor. The capacitor is connected parallel
Series and parallel circuits

In electronics, components of an electronic circuit can be connected in series or in parallel. Components connected in series are connected along a single path, so the same electric current flows through all of the components....
 to the breaker points, to suppress sparking
Electric arc

An electric arc is an electrical breakdown of a gas which produces an ongoing Plasma Electrostatic discharge, resulting from a current flowing through normally Electrical conductance media such as air....
 and prevent wear of the points.

Around the 1970s the primary breaker points were largely replaced with Hall effect sensor
Hall effect sensor

A Hall effect sensor is a transducer that varies its output voltage in response to changes in magnetic field. Hall sensors are used for proximity switching, positioning, speed detection, and current sensing applications....
s. As this is a non-contacting device and the primary circuit is controlled by solid state electronics, a great amount of maintenance in point adjustment and replacement was eliminated. This also eliminates any problem with breaker follower or cam wear, and by eliminating a side load extends distributor shaft bearing
Bearing (mechanical)

A bearing is a device to allow constrained relative motion between two parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can handle....
 life. The remaining secondary (high voltage) circuit was as described above, using a single coil and a rotary distributor.

Distributor cap

A distributor cap is used in an automobile
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
's engine
Internal combustion engine

The internal combustion engine is an engine in which the combustion of a fuel occurs in a combustion chamber inside and integral to the engine. In an internal combustion engine it is always the expansion of the high temperature and pressure gases that are produced by the combustion which apply force to the movable component of the engine, such as...
 to cover the distributor and its internal rotor.

The distributor cap is a prime example of a component that eventually succumbs to heat and vibration. It is a relatively easy and inexpensive part to replace if its bakelite
Bakelite

Bakelite is a material based on the thermosetting plastic phenol formaldehyde resin polyoxybenzylmethylenglycolanhydride, developed in 1907?1909 by Demographics of Belgium Dr....
 housing does not break or crack first. Carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 deposit accumulation or erosion of its metal terminals may also cause distributor-cap failure.

The distributor cap has one post for each cylinder, and in points ignition systems there is a central post for the coil voltage
Voltage

Electrical tension is the potential difference between two points of an electrical or electronic circuit, expressed in volts. It is the measurement of the potential for an electric field to cause an electric current in an electrical conductor....
 coming into the distributor. In HEI (High Energy Ignition) systems, there is not a central post, and the ignition coil sits on top of the distributor. On the inside of the cap there is a terminal that corresponds to each post, and the plug terminals are arranged around the circumference of the cap according to the firing order
Firing order

The firing order is the sequence of power delivery of each cylinder in a multi-cylinder reciprocating engine. This is achieved by sparking of the spark plugs in a gasoline engine in the correct order, or by the sequence of fuel injection in a Diesel engine....
 in order to send the secondary voltage to the proper spark plug at the right time.

The "rotor" head is attached to the top of the distributor shaft which is driven by a gear on the engine's camshaft
Camshaft

The camshaft is an apparatus often used in piston engines to operate poppet valves. It consists of a cylindrical rod running the length of the cylinder bank with a number of oblong lobes or cams protruding from it, one for each valve....
 and thus synchronized to it. This rotor is pressed against a carbon
Carbon

Carbon is a chemical element with chemical symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalence?making four electrons available to form covalent bond chemical bonds....
 brush
Brush (electric)

A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electric motors, alternators and electric generators....
 on the center terminal of the distributor cap which connects to the ignition coil either through the top and wired directly to the coil in HEI systems, or via the center terminal in points ignition systems and remotely connected to the coil. The rotor is constructed such that the center tab is electrically connected to its outer edge so that voltage coming in to the center post travels through the carbon point to the outer edge of the rotor. As the camshaft rotates, the rotor spins and its outer edge passes each of the internal plug terminals to fire each spark plug.

Cars
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
 that use a mechanical distributor often fail if they run into deep puddles because the water that leaks into the distributor shorts the electric current that should go through the spark plug, rerouting it directly to the body of the vehicle. This, in turn, causes the engine to stop as the fuel is not ignited in the cylinders. This problem can be fixed by opening the distributor's cap and wiping the cam and the contacts dry with tissue paper or by blowing hot air on them.

Direct ignition

Modern engine designs have done away with the distributor and coil, instead performing the distribution function in the primary circuit electronically and applying the primary (low-voltage) pulse to individual coils for each spark plug. In some cars, the coils are mounted together in a 'coil pack'; others utilize a coil located very near to or directly on top of each spark plug (Direct Ignition or coil-on-plug). This avoids the need to switch very high voltages, which is very often a source of trouble, especially in damp conditions. These systems also allow finer levels of ignition control by the engine computer, which assists in increasing power output, decreasing fuel consumption and emissions, and implementing features such as Active Fuel Management
Active Fuel Management

Active Fuel Management is a trademarked name for the automobile variable displacement technology from General Motors Corporation. It allows a V6 or V8 engine to "turn off" half of the cylinders under light-load conditions to improve Fuel economy in automobiles....
.

See also

  • Engine Control Unit (ECU)
    Engine Control Unit

    An engine control unit is an electronic control unit which controls various aspects of an internal combustion engine's operation. The simplest ECUs control only the quantity of fuel injected into each cylinder each engine cycle....
  • Timing mark
    Timing mark

    A timing mark is an indicator used for setting the timing of the ignition system of an engine, typically found on the crankshaft pulley or the flywheel, being the largest radius rotating at crankshaft speed and therefore the place where marks at one degree intervals will be furthest apart....