Spark Ignition System
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ScribdTranslationsSpark Ignition System
Uploaded by
ScribdTranslationsSPARK IGNITION SYSTEM
The ignition system being one of the basic components for the proper functioning
of combustion engines, has always been subject to constant studies and research
to improve the system, in order to achieve greater performance in the thermal
engine.
Due to the exceptional characteristics offered by the field of electronics in all
electrical applications, which is becoming increasingly popular every day, its
application to the automotive sector has been studied for some time, especially in
the ignition sector, and currently systems have been achieved that have
considerably improved the operation of the circuit and engine performance.
Traditional ignition, despite its degree of perfection, presents, due to the way its
components work, major drawbacks in the ignition and performance of engines,
since the system is based on feeding a primary coil at very rapid intervals, to
create the flow variation and thus obtain the high voltage impulse in the secondary,
so that the spark jumps in the spark plugs.
HISTORY OF THE AUTOMOTIVE IGNITION SYSTEM
It was around the year 1860 that the French citizen Étienne Lenoir invented the
spark plug, an element commonly used in today's automobiles. But this element
could not generate the spark necessary for the engine to run if there was no
ignition system.
The ignition system was invented around 1911 by Mr. Franklin Kettering. This type
of ignition is known as the Kettering system, which consists of points (tips or
contacts), a capacitor and a coil. This system became the standard in the
automotive industry.
Classic ignition system
How the automotive ignition system works
As part of the engine there is a “distributor” where the platinum plates are housed
and which open and close with the help of a small spring. This closing and opening
action is applied to a “coil” (a term only used in the motoring field that does not
have the same meaning as coil/inductor in electronics) which produces a spark.
Inside the distributor is a “rotor” that determines which of the spark plugs will get
the spark. This spark must appear at the moment when there is the appropriate
combination of fuel and air in the cylinder, necessary for the explosion to occur.
The explosion is necessary for the piston in this cylinder to move, turn the engine
and the car to run.
Distributor in classic automotive ignition system
Each time the distributor system (device that distributes the spark to each cylinder
of the car) sends a signal to the ignition control system, the latter passes a current
through the primary winding of the “coil” (the coil of cars works like a transformer).
When the signal that causes current to pass through the primary winding ceases to
exist, it causes a high voltage to appear on the secondary winding (because the
coil opposes sudden changes in current, it collapses, generating a high
voltage/tension at its terminals).
This voltage in the primary winding of the “coil” reflects in the secondary winding a
voltage increased by 100 or more times. It must be remembered that the coil (in
cars) is like a voltage boosting transformer. This voltage can be between 9,000 and
15,000 volts or more and is channeled to each of the spark plugs or candles
through the cables that come out of the distributor.
The “capacitor” has a large value. When the points open, the capacitor counteracts
the violent collapse of the coil's secondary, just long enough for the points to move
far enough apart so that the electromotive force (EMF) generated in the coil cannot
jump from one point to the other.
BASIC DIAGRAM OF THE CLASSIC IGNITION SYSTEM
The ignition system ignites the air-fuel mixture which is compressed inside the
cylinder.
The ignition system is required to generate sufficient spark to ignite the air-fuel
mixture and to generate these sparks with the distribution that corresponds to the
operating condition of the engine, as well as to be extremely durable.
IGNITION SYSTEM COMPONENTS
Ignition Coil
This device generates the high voltage necessary for ignition. The secondary coil is
wrapped around the core, which is made of thin iron plates in bonded layers. On
this, the primary coil is wound. Current is intermittently sent to the primary coil
according to the opening and closing of points in the distributor, and the secondary
coil wound around the core generates the high voltage delivered by the coil.
In modern systems the voltage to a main or independent coil per
cylinder is controlled through the ECU by electronic control,
eliminating the distributor.
What is a Coil?
The principle on which the function of the coil is based can be considered one of
the great achievements of science, since, to date, it remains unchanged. The coil
is composed of two circuits: Primary circuit "1"; and Secondary circuit "2"; The
primary circuit is a winding of approximately 250 turns; the secondary circuit is a
winding of approximately 20,000 turns of thinner wire. When the ignition key is
turned on, the current (+) is connected to the coil; but for it to work, it also needs
the current (-); this current reaches it through the work performed by the distributor
in one of its circuits. When the coil has both poles connected, current flows inside
the primary winding, producing a strong magnetic field within the circuit, but when
the current is cut off, a collapse of the magnetic field induces a high voltage current
within the secondary circuit. This high voltage is what comes out through the coil
turret, going through a cable to the distributor, which uses the rotor to distribute it
between the spark plugs.
Distributor
The distributor consists of a power distribution section
which distributes the current to each of the spark plugs
according to the discharge sequence, an ignition
signal generator which sends current intermittently to
the ignition coil and an advancer which controls the
ignition timing according to the engine conditions.
High Voltage Cable
These are wires that reliably transmit the high
voltage generated in the ignition coil to the
spark plugs. The conductors (wire core) of
these cables are covered with a thick layer of
insulating rubber to prevent loss of high voltage.
These wires connect the ignition coil to the
distributor and from the distributor to the spark
plugs.
Spark Plugs
The high voltage current (10 to 30 Kv) from
the distributor generates a high
temperature spark between the center and
ground electrodes of the spark plug to
ignite the compressed air-fuel mixture. This
ignites the air-fuel mixture in the cylinder. Spark plugs are divided into high thermal
value type and low thermal value type spark plugs, depending on the degree of
dispersion (thermal value) of heat received when the air-fuel mixture is burned.
That degree is expressed with a number. Generally, spark plugs that are
appropriate for the engine and vehicle model are selected, then a specific type of
spark plug should be used.
Most of the time, the specified spark plugs are clearly described in the Service
Specifications included with the engine items in the Repair Manual.
BREAKER
It is only used in engines with platinum ignition
in very old vehicles.
It is located inside the distributor and is
responsible for periodically interrupting the
current in the primary winding of the coil. This
interruption is achieved by the opening of the
platinum plates, which is controlled by the cam,
which rotates induced by the distributor shaft
that is synchronized with the engine.
COMPARISON OF IGNITION SYSTEMS
Conventional ignition
It offers good performance for normal demands (capable of generating up to
20,000 sparks per minute, i.e. it can meet the demands of a 4-cylinder engine up to
10,000 rpm) For 6 and 8 cylinder engines it would cause more problems). The
technical execution of the breaker, subjected to high loads by the electric current
passing through the primary of the coil, constitutes a compromise between the
switching behaviour at low rotation speed and the rebound of the contacts at high
speed. Derivations due to condensation of water, dirt, combustion residues, etc.
reduce the available voltage to a very considerable extent.
Electronically assisted ignition
There is greater voltage available at the spark plugs, especially at high engine
speeds. By using a low bounce contact breaker, this system can be made to
operate without disturbances up to 24,000 sparks per minute. The breaker is not
subjected to large electrical current loads, so its lifespan is much longer, which
reduces maintenance and breakdowns of this type of ignition. The capacitor is
removed.
Electronic ignition without contacts
These models meet even higher demands. The switch is replaced by a pulse
generator ("inductive" or "Hall effect" which are maintenance-free. The number of
sparks is 30,000. Due to the lower impedance of the coils used, the high voltage
rise is faster and, consequently, the ignition voltage is less sensitive to electrical
derivations.
IGNITION SYSTEM DIAGRAM WITH ECU
STARTING SYSTEM
The starting or ignition system is responsible for supplying mechanical, rotary and
electrical energy to the car's engine for ignition. The engine starting or ignition
system consists of the battery, starter motor, ignition switch and wiring. To
understand how the car's starter/ignition system works, the electrical diagram gives
us a very simple way to do so. In addition, the electrical diagram of the
starter/ignition circuit helps us diagnose and correct problems at the time of
ignition.
COMPRESSION IGNITION SYSTEM
All types of motor vehicles rely on engines to
propel the vehicle. There are several different
types of IC engines available, such as spark
ignition and compression ignition. Depending on the operating systems, each
engine will have advantages and disadvantages over each other based on how
each engine works. Combustion chamber
For engines to operate, fuel is pumped into a chamber so it can be ignited. Internal
combustion engines spray the fuel completely into the engine cylinder. The spark
ignition engine, on the other hand, pumps fuel into an intake system where the fuel
is mixed with air before entering the engine cylinder and igniting.
The compression ignition engine relies on hot air passing into the engine cylinder
which is under very high pressure. The compression engine is less efficient during
the process of mixing air and fuel to create combustion, leading to the spark
ignition engine having a higher power ratio than the compression engine.
However, because the compression
engine does not operate with a
throttle, it has a higher part-load
efficiency than spark ignition. This
means that the compression engine
can better maintain the vehicle's
speed.