Ignition coil test apparatus.

摘要

An ignition analyzer apparatus (10) for testing the condition of the ignition coil (8) of an internal combustion engine performs the testing while the engine is running and without requiring removal of a spark plug wire. The apparatus includes a test circuit (124) connected in parallel with the ignition points (82) (or solid state circuit interrupter) of the ignition system. When the ignition coil test is performed, a gating pulse is supplied to the test circuit (124) immediately before the points (82) are to open for a selected cylinder. This gating pulse causes the test circuit (124) to provide a low resistance in parallel with the points (82) when the points (82) open. This allows a reduced primary current to flow through the ignition coil (80) and prevents the production of a voltage pulse large enough to fire the spark plug (88A-88F) for the selected cylinder. While the points (82) are open and the test circuit (124) is providing a low resistance path, the current flow through the test circuit (124), and thus the primary current flowing through the coil (80) is measured. The gating pulse ends approximately half-way between the "points open" time of the selected cylinder and the "points open" time of the next cylinder so that the rotor (106) of the distributor (86) is between distributor terminals (108A-108F). When the gating pulse ends, the test circuit (124) changes to a nonconductive state, and since the points (82) have not yet closed, the primary current is interrupted and a high voltage secondary test signal is induced in the secondary (96) of the ignition coil (80). This test signal cannot, however, fire a spark plug (88A-88F) since the rotor (106) is in between distributor terminals (108A-108F), and since the reduced amplitude of the primary current prevents arc-over from the rotor (106) to the distributor terminals (108A-108F). The measured primary current and the measured high voltage secondary test signal are used to provide an indication of ignition coil (80) condition.