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A14 | Technical information
Spark plug spark techniques
Spark Plug with AIR-GAP spark techniques
Front electrode,
Centre electrode
When it forms the arc directly between
the centre electrode and the ground
electrode, the ignition spark passes
through the air-fuel mixture located
between the electrodes.
The advantages
High level ignition reliability throughout
the plug’s entire service life.
Good cold starting behaviour
Low engine voltage requirements
Side electrode,
Centre electrode
Shaped ground
electrode,
Centre electrode
Together with the increased space
between the electrodes, the sharp
V-groove edges resulting from the
ground electrode’s shape ensure that
the ignition spark’s thermal energy is
transferred easily and more effectively
into the air-fuel mixture.
This leads to a pronounced flame core
and complete combustion irrespective
of operating conditions
The advantages
High levels of ignition reliability due to
the instantaneous arcing of the spark
and immediate ignition of the A/F
mixture
Additional cold start reliability even
when battery voltage is low. Improved
combustion protects the engine and in
particular the catalytic converter.
Since misfiring is avoided, fuel
consumption drops even more.
Spark plugs with SURFACE-GAP spark techniques
Side electrode,
Centre Electrode
or
Side electrode,
insulator Centre
electrode
The ground electrodes are arranged so
that only particularly long and powerful
surface-gap sparks are generated
The advantages
Improved ignition reliability throughout
the spark plug’s entire service life.
Optimal protection of the catalytic
converter(s).
Particularly low level of ignition voltage
required.
Self cleaning effects in case of
soothing.
Extended operating life thanks to
design with several ground electrodes.
Spark plugs with AIR-SURFACE spark techniques
Side electrode,
Centre Electrode
or
Side electrode,
insulator Centre
electrode
Spark plugs featuring the air-surface
spark principle are being used
increasingly in Original Equipment
applications. For reliable ignition, the
ignition spark selects the best route to
take from the centre electrode it either
functions as an air spark or as an airsurface
spark.
With an air spark, when ignition takes
place the arc jumps across directly from
the centre to the ground electrode.
The air-surface plug on the other hand
uses existing charge carriers to travel
to the insulator nose from where it then
jumps across, as an air spark, to the
ground electrode.
The advantages
Increased ignition reliability throughout
the spark plug’s entire service life
Improved cold start characteristics
Low ignition-voltage requirement
Self cleaning effects in case of sooting
Optimal protection of the catalytic
converter(s)
The configuration with several ground
electrodes increases the plug’s life.
Bosch Automotive Aftermarket 2008