All About ignition coils - Beru.pdf

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Ignition Technology
Diesel Cold-Start Technology
Cooling
Sensors
All about ignition coils
Technical
Information
No. 07
®
Perfection
built in
2
Table of Contents
Introduction
The spark-ignition engine
Operation of ignition coils in the spark-ignition engine
Demands on modern ignition coils
3
4
4
5
Ignition coils –
design and mode of operation
Ignition technology terminology
How many ignition sparks does an engine need?
Ignition coil specifications / characteristics
5
6
7
7
Ignition coils –
types and systems
Canister-type ignition coils
Electronic distributor ignition coils
Double-spark ignition coils
Ignition coil rails
Plug shaft / plug / smart plug top coil ignition coils
Dual coil ignition coils
8
8
9
9
11
11
13
Ignition coil – production
Step-by-step to a precision product
Tested quality
The genuine article and fakes
14
14
15
15
Workshop tips
Reasons for replacement
Professional removal / installation
Special tool for ignition coil replacement
Testing and checking
Step-by-step defect identification
17
17
18
18
20
21
Self-test
22
3
Introduction
Fewer emissions, lower fuel consumption, higher
ignition voltage, restricted space in the drive unit and
engine compartment: The design demands on modern
ignition coils are constantly increasing. Although the
task of spark-ignition engines remains the same: the
fuel / air mixture must be ignited at the right time with
the optimum ignition energy so that complete combusti-
on occurs. To reduce fuel consumption and emissions
and to increase the efficiency, engine technologies are
constantly developed further – and thus also the BERU
ignition systems.
In particular, the company runs its own R&D departments
at its Ludwigsburg, Germany headquarters and in Asia,
in which ignition technologies are driven forward in
cooperation with the international automotive industry.
Thus BERU ignition coils are being precisely adapted to
the requirements of modern spark-ignition engines such
as turbocharging, downsizing, direct injection, lean mix,
high exhaust gas recirculation rates etc. In the process,
the company is able to fall back on a whole century of
valuable experience as an ignition technology expert.
BERU ignition coils are produced in state-of-the-art
facilities at its own production plants in Ludwigsburg
and Muggendorf, Germany, as well as in Asia. BERU
supplies OEM's with ignition coils for nearly all signi-
ficant European volume applications. The company
currently offers a range of over 400 ignition coils to the
maintenance and repair markets – needless to say in
original equipment quality. Today the market penetration
of the range in VW vehicles is 99%, in BMW Group
vehicles 80%, in the VW Group as a whole 95% – and
today the range is being continuously extended in
accordance with market requirements.
4
The spark-ignition engine
Operation of ignition coils in the spark-ignition engine
Optimum ignition of the compressed fuel / air mixture has been
one of the greatest challenges for designers since the early days
of engine construction. In the case of ignited sparked engines,
this conventionally occurs in sequence with the compression cycle
by an electrical spark from the spark plug. So that the voltage
can make the jump between the electrodes, a charge must first
be accumulated by the vehicles' low voltage electrical system,
then stored and finally discharged at the spark plug at the ignition
timing. This is the job of the ignition coil as an integral part of the
ignition system.
An ignition coil must be exactly attuned to the respective ignition
system. The required parameters include:
The spark energy, which is available to the spark plug
The spark current at the time of the spark discharge
The combustion duration of the spark at the ignition plug
The ignition voltage under all operating conditions
The spark count at all speeds
Spark-ignition engines with turbocharger or direct fuel injection
require higher spark energies. The high voltage connection
between ignition coil and spark plug must be functional and safe.
This is where BERU comes in with high-quality ignition cables
with suitable contacts or high-voltage ignition coil connectors.
5
Demands on modern ignition coils
Ignition coils in the ignition systems of modern cars generate
voltages of up to 45,000 V. It is essential that misfiring – and as
a consequence incomplete combustion – is avoided. It is not
only that the vehicles' catalytic converter could be damaged.
Incomplete combustion also increases emissions and thus envi-
ronmental pollution.
Ignition coils are – regardless of the system (static high voltage
distribution, rotating high voltage distribution, double spark coil,
single spark coil) – electrically, mechanically and chemically
highly stressed components of the spark-ignition engines. They
must perform faultlessly under a wide variety of installation con-
ditions (on the body, engine block or directly on the spark plug in
the cylinder head) over a long service life.
Plug shaft ignition coils are mounted
deep in the engine compartment
and must withstand extreme thermal
loads.
Ignition coils: electrical, mechanical, thermal,
electrochemical requirements
Temperature range -40 °C to +180 °C
Secondary voltage to 45,000 V
Primary current 6 to 20 A
Spark energy 10 mJ up to approx. 100 mJ (at present)
or 200 mJ (future)
Vibration range to 55 g
Resistance to gasoline, oil, brake fluid
Ignition coils – design and mode of operation
Ignition coils work on the transformer principle. They basi-
cally consist of a primary winding, a secondary winding, the
iron core and a housing with isolation material, nowadays
two-component epoxy resin.
On the iron core of individual thin steel sheets two coil
elements are applied e.g.:
The primary winding is made of thick copper wire with
approx. 200 windings (diameter approx. 0.75 mm²),
The secondary winding is made of thin copper wire with
approx. 20,000 windings (diameter approx. 0.063 mm²)

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