Bosch Automotive A product history

8 | Supplement 2 | Journal of Bosch History
The Daimler Phoenix
truck was the first motor
vehicle to be equipped
with a Bosch magneto
ignition device as standard
equipment.
hitherto, the magneto ignition device was
unsuitable for such an engine. The device
itself was capable of delivering a maximum
of 200 sparks per minute, yet the small
De Dion-Bouton engine ran at a maximum
speed of 1,800 rpm and thus required
900 ignition sparks per minute.
The solution for high-speed engines
Arnold Zähringer, Bosch’s factory manager,
came up with the solution. Instead of moving
the ponderous armature itself through
the magnetic field, he left this job to a lightweight
metal sleeve which he laid around
the armature. Zähringer’s invention was
patented for Bosch. The innovative ignition
device had in theory solved a major problem
for the young automotive industry –
ignition in high-speed internal-combustion
engines in vehicles. However, the complicated
break-spark rodding needed to create
the ignition spark in the combustion chamber
remained a weakness in its design.
This rodding had to be redesigned for every
engine. It also required considerable maintenance
and was prone to breakdown.
High voltage and spark plugs
In the summer of 1901, therefore, Robert
Bosch gave his colleague Gottlob Honold
the brief of designing a magneto ignition
system without break-spark rodding. After
just a few months, Honold presented his
high-voltage magneto ignition system,
based on what was known as electric arc
ignition. By means of two coils on the
armature, it generated a high-voltage current.
This was conducted to a spark plug
via a simple cable connection. The highvoltage
current jumped the gap between
its electrodes in the form of a spark.