公开(公告)号：JPH05133312A

公开(公告)日：1993-05-28

申请号：JP5439191

申请日：1991-03-19

Applicant: MARELLI AUTRONICA

Inventor： JIYURIAANO CHIKAREESE ,  MARUKO DEIAKO ,  JIYANRUIIJI MOREERO

IPC: F02P3/04 ,  F02P3/045 ,  F02P3/05 ,  F02P3/055

Abstract: PURPOSE: To prevent the generation of supervoltage in a secondary coil by raising the gate voltage of a transistor gradually and cutting off the transistor after current in a primary coil is increased progressively. CONSTITUTION: A pulse generator 10 generates pulses in a frequency higher than the reciprocal of the minimum time interval of the two changes of a control logic signal from a control unit 5. When the unit 5 outputs a signal C during engine operation, a transistor 6 is cut-off. Drain current VD is maintained at high level. When gate potential of the transistor 6 reaches the conductive level, the drain current VD is lowered promptly across a threshold with respect to a comparator 12. At that time, the comparator 12 supplies a signal P from the pulse generator 10 to a current generator to increase the gate potential of the transistor 6 gradually in response to each pulse of the signal P, and reduce the drain potential progressively. In this way, it is possible to prevent overvoltage in a secondary coil and the generation of wrong spark.