GB830492A - Apparatus for indicating the proportion of mis-fires occurring in a spark-ignition internal combustion engine - Google Patents

Abstract

830,492. Electric tests. ESSO RESEARCH ENGINEERING CO. May 9, 1958 [July 18, 1957], No. 22767/57. Class 37. In apparatus for continuously indicating the proportion of mis-fires occurring in a sparkignition I.C. engine, pulses synchronous with mis-fires of the engine are used in conjunction with a potential proportional to the speed of the engine to produce further pulses of constant amplitude, the duration of which is inversely proportional to the engine speed. As shown, a lead from the primary coil of the ignition circuit (not shown) is connected to a rectifier 1, positive pulses A thereby produced being fed to a monostable trigger circuit 2 which supplies a series of positive pulses of equal duration and amplitude to an integrating circuit 11 to produce a potential representative of the engine speed, and a series of negative pulses B of fixed duration to a differentiating circuit 3 to produce a series of positive-negative pulses C. Simultaneously, pulses from the ignition circuit H.T. wire, which vary in intensity according to whether a fire or a mis-fire occurs, are applied, directly or by capacity coupling, to a tuned oscillator circuit 7 to produce a series of damped oscillations D which are rectified at 8 and supplied to a potentiometer 9 which is tapped so that, while pulses initiated by normal ignition operate a trigger circuit 10 to produce negative pulses F of duration greater than that of the pulses B, pulses resulting from misfires do not operate circuit 10. Pulses C and F are added at 4; when ignition is normal, the resultant pulse G is wholly negative and is blocked by a rectifier 5; on the occurrence of a mis-fire, in the absence of pulse F the rectifier passes the positive portions K of pulses C to operate a mis-fire counter 6; they are also amplified at 13 and supplied to a trigger circuit 12 to produce pulses of constant amplitude, of frequency depending on the frequency of mis-firing and of duration depending inversely on the potential supplied to the circuit 12 from the integrating circuit 11. These pulses are fed to an integrating circuit 14 and a meter 15, both of which may be comprised by a voltmeter.