100 years of Bosch spark plugs – the spark that fired
the development of the automobile
On January 7, 2002, it will be exactly a hundred years since Bosch was awarded the patent for the first spark plug. Designed to be combined with a high-tension magneto ignition system, the spark plug solved what Carl Benz had described as the most fundamental obstacle to early motoring.
Together with improvements in production technology, it was the spark plug that laid the foundations for the rapid increase in automobile production over the decades that followed.
Nowadays, the Bosch spark plug, which has been developed and improved continuously over the decades, plays a key role in the clean and efficient combustion needed for reliability, fuel economy, and the operation of catalytic converters. Despite the tremendous increase in demands on spark plugs, the service life of a spark plug is now about 12,000 to 18,000 miles, some 20 to 30 times further than the figure 90 years ago. Some special spark plugs even have a service life of 60,000 miles.
Even, in the last few years, Bosch has shown the potential still offered by this elderly product – adapting it for new developments in engine technology such as four-valve cylinder heads or lean mix engines. The latest example is the Volkswagen Lupo FSI, the first mass-produced car with a very low-consumption gasoline engine featuring both direct injection and stratified charging. Bosch not only supplies the entire injection and ignition system but each Lupo FSI is fitted with Bosch spark plugs developed specially for this engine.
Design variants and special materials such as platinum and yttrium allow Bosch spark plugs to be used in a wide variety of applications.
Countless different types of spark plug can also be produced by changing the type, number and shape of the electrodes. The current Bosch spark plug catalogue includes 26 different electrode designs, each designed to help engines meet ever more stringent emission limits at the same time as ensuring greater efficiency and higher power output.
Decades of experience and a sustained development effort in close cooperation with virtually all the major vehicle producers have made Bosch one of the world's leading Original Equipment and aftermarket suppliers of spark plugs and the market leader in Europe.
All the leading car-makers fit Bosch spark plugs as standard equipment: Bosch customers include Audi, BMW, Cadillac, Citroën, Fiat, Daimler-Chrysler, Mitsubishi, Opel, Peugeot, Porsche, Renault, Seat, Skoda, Suzuki, Toyota, Volvo and VW. The range now includes more than 1,250 different models because many modern engines call for their own tailor-made spark plugs.
All in all, Bosch has developed more than 20,000 different types of spark plug over the past 100 years. To find out which Bosch spark plug to use not only for your car, but also for your lawnmower, power saw or boat, all you need to do is go to the www.bosch.com web site.
In 1902, Bosch produced about 300 spark plugs. Now the company's plant in Bamberg alone produces about a million spark plugs every working day and world-wide production is about 350 million spark plugs per year.
Bosch also produces spark plugs at plants in India, Brazil, China and Russia for local markets and manufacturers. In total, Bosch has produced more than seven billion spark plugs. Laid end to end, they would stretch all the way to the moon.
100 years of Bosch spark plugs
1902:
Bosch is granted a patent for a new type of spark plug combined with a high-tension
magneto on January 7. The first systems are supplied to Daimler-Motorengesellschaft
in Bad Cannstatt on September 24, 1902.
1902 onwards:
Production starts at a few hundred units per year.
1914:
The first spark plug factory is founded in Stuttgart.
1927:
Bosch introduces the term "heat range", which has remained the standard
measure of the thermal capacity of a spark plug.
1939:
The Bamberg spark plug factory is founded.
1953:
The first Bosch spark plug with a composite centre electrode, ensuring reliable
cold starting and a longer service life, is used on the Mercedes Benz 300 SL
gull-wing.
1968:
The Bamberg plant produces the billionth spark plug.
1976:
Mass production of the Thermoelastic plug with a composite centre electrode
starts.
1980s:
Spark plugs are adapted to changes in fuels and engine design: lead-free petrol,
catalytic converters and four valves per cylinder.
1983:
Platinum centre electrodes and composite materials with noble metal alloys give
spark plugs the potential to last over 35,000 miles.
1991:
The Bosch spark plug with surface/air gap prevents carbon fouling, timing drift
and misfiring even in operation with frequent short trips.
1995:
A nickel yttrium electrode prolongs the service life of spark plugs.
2000:
The seven billionth Bosch spark plug is produced.
Supply of tailor-made spark plugs for the first direct injection stratified
charge gasoline engine begins.
7 January 2002:
The Bosch spark plug reaches its first century.
Facts and figures about Bosch spark plugs
Annual Bosch spark plug production: more than 350 million (1902: about 300).
Material required for daily production of more than a million spark plugs: 29 t of steel, 1.8 t of nickel, 0.7 t of copper, 15 km of nickel wire, 2.5 kg of platinum and 20 t of aluminium oxide for insulators.
Total production since 1902: more than 7.5 billion Bosch spark plugs.
Bosch spark plug types currently available: 1250 with 26 different electrode designs.
Bosch spark plug types produced since 1902: more than 20,000.
Smallest Bosch spark plug: 40 mm long (e.g. for lawnmowers).
Largest Bosch spark plug: 150 mm long (e.g. for stationary gas engines).
Performance of a standard Bosch spark plug: up to 100 sparks per second or more than 20 million sparks over a useful life of 20,000 km.
Working conditions of Bosch spark plugs: voltage up to 30,000 V, temperatures up to 1,000 ºC, pressures up to 100 bar (equivalent to the pressure underwater at a depth of 1,000 m); hot, extremely aggressive mixture of petrol vapour, combustion products and fuel and oil residues.
Service life of Bosch spark plugs: standard plugs 20,000 to 30,000 km, special plugs up to 100,000 km.
Bosch spark plug production plants: Bamberg (Germany), Aratú (Brazil), Engels (Russia), Naganathapura (India) and Nanjing (China).
Vehicle producers with Bosch park plugs as original equipment: Audi, BMW, Citroën, Daewoo, DAF, Fiat, Lancia, Daimler-Chrysler, Holden, Mitsubishi, Nissan, Nedcar, Opel, Peugeot, Piaggio (scooters), Porsche, Renault, Rotax (small engines), Seat, Skoda, SsangYong, Suzuki, Toyota, Vauxhall, Volvo, VW.
Applications of Bosch spark plugs: cars, motorcycles and scooters, commercial vehicles, engines for boats and jet-skis, gardening and forestry equipment, stationary gas engines, emergency generator sets, water pumps and small engines.