GB666973A - Improvements in or relating to means for testing the ignition systems of internal-combustion engines - Google Patents

Abstract

666,973. Cathode-ray testing apparatus. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. March 8, 1949 [June 11, 1948], No. 15860/48. Class 37. [Also in Group XXVII] In an apparatus for testing the ignition system of an internal-combustion engine comprising a radio receiver R, an oscillograph CRO, and means, such as a lead RL, for connecting the oscillograph to the output of the receiver R so as to receive an input therefrom and give indications corresponding to ignition interference which may have reached the receiver R via a fault in the screening, there is provided means, such as the capacity pick-up PU on one of the sparking plug lead conduits SP, for synchronizing the time-base of the oscillograph with the engine so that any particular interference input to the receiver R may be identified in relation to a particular cylinder of the engine. The " X " plates of a double-beam cathode-ray oscillograph are connected to a time-base oscillator (not shown) whilst the " Y " plates of the upper beam are connected to a magneto MG, each peak of the trace indicating the firing of a sparking-plug, and the " Y " plates of the lower beam are connected to the output of the receiver R. If one of the conduits SP is leaky a peak will occur on the lower trace beneath the peak of the plug with which the leaky conduit is associated. If the screened manifold is faulty the lower trace will exhibit a peak beneath each peak in the upper trace. A single beam oscillograph may be used and the two " Y " deflections may either be combined or displayed alternately by means of mechanical or electronic switching. The apparatus may be set up to perform both the function of testing the screening and the ignition circuits.and equipment. Reference has been directed by the Comptroller to Specification 563,502.