This year marks the 100th anniversary of the first commercially viable high-voltage spark plug, patented in 1902 by German automotive pioneer Robert Bosch, who designed it as part of a magneto-based ignition system he developed.
That first year saw the manufacture of only about 300 spark plugs by Robert Bosch Gmbh., the Stuttgart, Germany-based company that subsequently grew in tandem with the automobile's popularity.
Today, the 115-year-old company turns out approximately 1 million spark plugs a day at its largest plant in Bamberg, Germany, and worldwide, its production totals about 350 million spark plugs annually. In the 100 years since its founder patented the development, the company estimates it has produced more than 7 billion spark plugs. That's enough plugs to stretch almost 217,500 miles-or from here to the moon-if laid end to end.
Bosch's current spark plug line includes more than 1,250 different product models, with 26 different electrode designs.
In all, the company claims it has developed more than 20,000 different types of spark plugs-not to mention a string of technical breakthroughs adding to the product's performance and life span. Such improvements not withstanding, today's spark plug still bears a remarkable similarity to Mr. Bosch's original design, the company proudly points out.
Prior to the patented Bosch design, several earlier attempts had been made to achieve a spark-producing mechanism, but none had proven practical for automobile use. The availability of a reliable automotive spark plug was pivotal in the early development of the internal combustion engine, which at that time was plagued by an inability to sustain continuous, reliable ignition of the fuel-air mixture. Fouling was a particular problem in early auto engines, and spark plugs had to be removed and cleaned regularly.
Then, as now, auto racing figured heavily in the advancement of such technology. In 1903, a Mercedes equipped with the Bosch magneto ignition system won the Gordon Bennett Race in Ireland-one of the earliest auto races in history. The resulting commercial success of the company's ignition system in automobiles led to the manufacture of spark plugs for motorcycles, airplanes and dirigibles as well.
In the century since, advances in spark plug technology have contributed to longer service life and more complete combustion, greatly reducing exhaust emissions and contributing substantially more power and efficiency to the vehicle.
Not much changed in spark plug design during the product's first 80 years, but the last two decades have brought dramatic improvements in its materials and design.
The early 1980s saw the introduction of a copper core, surrounded by nickel-chromium-one of several subsequent ``firsts'' claimed by Bosch. That design offered improved heat transfer, a wider heat range and greater resistance to plug fouling. It went on to become the standard of the industry, the company said.
However, in 1985, the company claimed the development of a platinum core that could provide better resistance to corrosion and erosion, thereby providing substantially longer service life. In that design, the center electrode is made entirely of platinum that has been ``sintered'' or heat-fused into an extended ceramic insulator. Because the material is so resistant to erosion and corrosion, the company contends that its platinum spark plugs never need to be re-gapped.
The year 1998 saw the introduction of the Bosch Platinum+4 spark plug (containing four times the amount of platinum as its predecessor, the Bosch Platinum) and four electrodes to deliver a more powerful spark. Two years later, the company rounded out the product line with the Bosch Platinum2-so named because it has double the platinum of the first-generation Bosch Platimum plug and two ground electrodes. The company's U.S. offices are in Broadview.