Bosch ignition coil

An ignition coil (also called a spark coil) is an induction coil in an automobile's ignition system.

How it works[]

This specific form of the autotransformer, together with the contact breaker, converts low voltage from a storage battery's 12 volts into thousands of volts, (high voltage) required by spark plugs in an internal combustion engine.


In modern ignition systems each spark plug has its individual coil, sitting right on top of it, in a so called Direct Ignition (DI) module.

Early history[]

The disruptive discharge Tesla coil [1] is an early predecessor of the "ignition coil" in the ignition system. Tesla also gained Template:US patent, "Electrical Igniter for Gas Engines", on August 16, 1898. It used the principles of the ignition coil used today in automobiles. A. Atwater Kent [2], in 1921, patented the modern form of the ignition coil.

Related coils[]

  • A Oudin coil [3] is a disruptive discharge coil.


  • Template:US patent

    Bosch ignition coil

  • Template:US patent - Induction coil structure - Arthur Atwater Kent - 1921
  • Template:US patent - Induction coil - Arthur Atwater Kent - 1923
  • Template:US patent - Induction coil - Arthur Atwater Kent - 1923
  • Template:US patent - Ignition coil - Arthur Atwater Kent - 1926
  • Template:US patent - Ignition system - Ernst Alexanderson [4]- 1929
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