In a distributor assembly having an ignition coil therein, for use with an internal combustion engine, the positional relationship between the ignition coil and a magnetic sensitive detector, which detects a proper ignition timing, is selected so that the leakage flux from the ignition coil does not cause the magnetic sensitive detector to malfunction. According to one arrangement the magnetic sensitive direction of the detector is arranged perpendicular to the leakage flux from the ignition coil. According to the other arrangement the magnetic sensitive direction of the detector is arranged to intersect a radial line from the axis of the main magnetic flux of the ignition coil at an angle other than 90 degrees so that the flux variation in the detector is expedited by the appearance and disappearance of the leakage flux. In the both arrangements, the axis is arranged parallel to a rotary shaft to which a signal rotor is attached, where the rotation of the signal rotor is arranged to cause the detector to change its output signal by detecting the variation in magnetic flux.

To eliminate frictional effects by stationary elements (17, 37, 47) with respect to a sleeve (16, 36, 46) which rotates with a shaft (11) of a distributor, but is adjustable with respect to the instantaneous position about the shaft by a centrifugal spark advance mechanism (15), the nonrotatable elements (17, 37, 47) are secured from a support plate (22, 32, 49) which is positioned intermediate the sleeve and the distributor rotor, the support plate being journalled by bearings (23, 33, 44, 45) directly on the shaft. A load-dependent vacuum chamber can be linked directly to the support plate for additional load-dependent spark timing adjustment.

A stator and a rotor are provided, the latter being coaxial with the stator and connected with the shaft which is driven by the combustion engine. During the rotation of the rotor the same can assume at least two angular positions relative to the stator. A first group of pole pieces is provided on the rotor or stator and these are equi-angularly spaced about the same projecting on radii which extend outwardly from the axis of rotation. A second group of pole pieces are provided on the stator or rotor, spaced angularly about the same and including at least two sets each of which is composed of a second plurality of pole pieces which is identical with the first plurality. The pole pieces of the first group are all simultaneously juxtaposed with one each of the pole pieces of one of the sets when the rotor is in one of its angular positions, and they are all simultaneously juxtaposed with one each of the pole pieces of the other set when the rotor is in the other of its angular positions. The angular distance through which the rotor travels in its direction of rotation from its one to its other angular position is different from the angular distance which it travels in the same direction to return from the other to its one position.

A magnetic sensor device in the ignition system for an internal combustion engine includes a reluctor plate of magnetizable material mounted on a shaft of magnetizable material driven rotatably in synchronism with the rotation of the engine drive shaft. The reluctor plate includes a plurality of radial arms preferably equal in number to the cylinders of the engine. A circular cylindrical permanent magnet structure having alternately poled permanent magnet sections, equal in number to twice the cylinders of the engine, is mounted at one end thereof on a collector plate of magnetizable material. The reluctor plate is positioned adjacent the opposite end of the permanent magnet structure with the rotatably driven shaft extending centrally through the collector plate and permanent magnet structure. A coil assembly is mounted within the permanent magnet structure so that rotation of the reluctor plate with respect to the permanent magnet structure produces flux lines through the coil assembly varying between a predetermined positive and negative amplitude, to in turn, produce a corresponding output voltage at the coil assembly. Alteration of the position and/or relative dimensions of the magnet sections of the permanent magnet structure may be used to change "dwell."

A distributor for a contactless ignition apparatus of an internal combustion engine is disclosed. An ignition control circuit unit of contactless type is comprised of a case containing the ignition control IC circuit and a mold resin of the pick-up coil integrally formed with the case. The distributor contains closed magnetic circuit-forming means comprising a distributor shaft rotatable in synchronism with the engine, a reluctor or rotor fixed on the shaft and having claws in the number corresponding to the number of engine cylinders, a stator having a pair of claws opposed to the claws of the reluctor and mounted on the movable base of the angle advancer for advancing the ignition timing in response to a negative vacuum pressure, and a permanent magnet for generating a closed magnetic circuit through the reluctor stator and shaft. The pick-up coil of the ignition control circuit unit is arranged to cross the closed magnetic circuit, which unit is fixed within the distributor.