Ignition distributor for internal combustion engine

Abstract

An ignition distributor includes a distributor housing having a cup-shaped cylindrical partition wall accommodated in an annular recess of a driven pulley mounted on an end portion of a camshaft, the partition wall having an annular bottom portion arranged in the annular recess to provide a circular opening, a distributor rotor of generally cylindrical shape fixed to the end portion of the camshaft and housed within the partition wall, the rotor having an annular flange formed at its outer periphery with an annular rim which is opposed to the annular bottom portion of the partition wall to form a first annular passage, and a distributor cap coupled with an open end of the partition wall to cover the rotor, the cap having a cylindrical extension wall extending therefrom into the interior of the partition wall and being arranged concentrically with the partition wall to form an annular space in communication with the first annular passage and a rotor space in which the rotor is arranged. The extension wall of the cap having an inner end slightly spaced from the annular rim of the rotor flange to form a second annular passage for communication between the annular and rotor spaces. The annular space is communicated with a source of negative pressure to discharge the air therefrom, while the rotor space is communicated with the atmospheric air to introduce fresh air thereinto.