Browse Prior Art Database

AUTOMOTIVE IGNITION DESIGN

IP.com Disclosure Number: IPCOM000005744D
Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2001-Nov-01
Document File: 1 page(s) / 56K

Publishing Venue

Motorola

Related People

Richard J. Valentine: AUTHOR [+2]

Abstract

Conventional automotive ignition systems comprise a high voltage Darlington bipolar transistor that switch- es an ignition coil's current for igniting the internal combustion engine gasoline air fuel mixture. However, the use of the bipolar transistor results in a substantial power loss that severely effects the heat dissipation, and therefore operation, of the system.

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0 M MOWROLA

Technical Developments Volume a October 1988

AUTOMOTIVE IGNITION DESIGN

by Richard J. Valentine and Thomas L. Huettl

   Conventional automotive ignition systems comprise a high voltage Darlington bipolar transistor that switch- es an ignition coil's current for igniting the internal combustion engine gasoline air fuel mixture. However, the use of the bipolar transistor results in a substantial power loss that severely effects the heat dissipation, and therefore operation, of the system.

   Referring to the single figure, an automotive ignition system is disclosed that includes a new transistor device 1 coupled between the ignition coil 2 and a current sensing network 3. The current sensing network 3 includes acurrent sensing resistor4 and an amplifier5 forcontrolling the maximum drain current level. Capacitor 6 and resistor 7 increase the stability of the feedback loop throughout a wide range of possible ignition coil voltage and current adjustments.

   Transistors 6 and 9 improve the turn off speed of the transistor device 1 and insure its gate voltage level is clamped to ground when the engine control computer 10 output is in a low state. The network including tran- sistors 9 and 10 may be adjusted for slower or faster fall times set by resistor 11. The transistor device 1 will have a storage time phenomenon, which determines its maximum turn off speed, i.e., five microseconds, even with a gate turnoff speed of less than 500 nanoseconds.

Diodes 12,13 and 14...