The present invention relates to an ignition distributor for detecting the rotary position or the like of an internal combustion engine to generate ignition timing control signals.
There is an ignition device for controlling the ignition timing of an internal combustion engine in an automobile or the like.
FIG. 13 is a schematic explanatory diagram of an ordinary ignition device used in an automobile. In FIG. 13, a reluctor 101 is mounted to a shaft 102 rotating in proportion to the rotation of an internal combustion engine. The reluctor 101 rotates with the rotation of the shaft 102. The reluctor 101 includes protrudes the number of which is more than or equal to the number of the cylinders of the internal combustion engine, being disposed in the vicinity of a stator 104 combined to a permanent magnet 103. A closed magnetic circuit is formed by the reluctor 101, the stator 104, the permanent magnet 103 and a pole piece 113. The size of the gap between the reluctor 101 and the stator 104 is changed with the rotation of the reluctor 101. The magnetic resistance of the magnetic circuit is changed with the size of the gap between the reluctor 101 and the stator, the magnetic flux density in the magnetic circuit being changed by the change of the magnetic resistance of the magnetic circuit.
FIG. 14 is an explanatory diagram of the above-mentioned magnetic circuit, FIG. 15 showing an equivalent circuit of the magnetic circuit. The configuration of FIG. 13 is different from that of FIG. 14 because FIG. 13 shows an abstract example of the ignition device, and FIG. 14 shows a concrete example of the magnetic circuit. In FIGS. 14 and 15, reference numeral R1 represents a magnetic resistor between the top end portion of the pole piece 113 and reluctor 101, reference numeral R2 representing a magnetic resistor from the side surface of the pole piece 113 through a gap to the side surface of the reluctor 101, reference numeral R3 representing a magnetic resistor between the shaft 102 and one end portion of the stator 104. Reference numeral R4 represents a magnetic resistor from the permanent magnet 103 to the side surface of the stator 104, reference numeral R5 representing a magnetic resistor from the permanent magnet 103 to the other end portion of the stator 104. The resistance value of the magnetic resistor R1 is changed with the rotation of the reluctor 101, the linkage of the magnetic flux of a pickup coil 105 being changed with the change of the resistance value of the resistor R1.
An ignition control signal 106 having wave form as shown in FIG. 16 is generated by means of the change in the linkage of the magnetic flux. The ignition control signal 106 is supplied to an ignition signal amplifier 107 as shown in FIG. 13 from the pickup coil 105. The ignition signal amplifier 107 controls ignition signals supplied to an ignition coil 109 on the basis of an ignition threshold voltage 108 as shown in FIG. 16. In a concrete example, as shown in FIG. 16, when the ignition control signal 106 is larger than the ignition threshold voltage 108, an ignition signal 110 supplied to the primary side of the ignition coil 109 is made to be large level. When the ignition control signal 106 is smaller than the ignition threshold voltage 108, the ignition signal 110 is made to be small level. When the ignition signal 110 is made to be small, the magnet flux in the magnetic core of the ignition coil 109 is greatly changed, so that high voltage is induced in the secondary side of the coil 109. The high voltage induced in the secondary side of the coil 109 is distributed from an ignition plug 112a to an ignition plug 112d of each cylinder of the internal combustion engine through a distribution part 111, so that the ignition is carried out. The rotary shaft 102 of the reluctor 101 is interlocked to the rotary shaft of the distribution part 111, as designated by a dotted line in FIG. 13.