Robert Boschgmbh

Jurgen Fresow

Bert Wurst

The ignition coil of the system has its primary serially connected with a transistor which controls current flow therethrough. Ignition pulses are provided by an ignition pulse source, for example an inductive transducer. The recurrence rate of the ignition pulses is analyzed and a corresponding control signal is obtained which controls the timing interval of a timing circuit, the timing circuit determining the ON, or connected time, of the transistor or similar controlled switch in series with the primary of the ignition coil. Analysis of the recurrence rate is, simply, done in a pair of integrators, alternately effective and storing the time interval between alternate, succeeding ignition pulses, which permits control of current flow through the ignition coil for a period of time just sufficient for current flow to reach saturation without, however, causing current flow while the circuit is saturated, thus preventing unnecessary heating of the ignition coil and associated components. Alternate integration of alternate signals permits efficient operation also under high-speed operating conditions.

Ignition system for internal combustion engines

A universally applicable system should permit easy matching of ignition timing characteristics to specific engines. In order to control a digital electronic ignition system, a marker signal is generated when a piston has reached a predetermined angular position with respect to upper dead center (UDC) position, and additional marker signals are generated as the piston moves, for example by sensing the teeth on a starwheel coupled to the engine or, for example, in an automotive engine by providing signals each time a tooth of the starter gear passes by a transducer. Two counter stages are provided which go through two count cycles for any one ignition event. The marker starts counting of both counters. The first counter stage counts for a predetermined time interval to provide a speed-dependent output number which is stored in a multiplex or memory stage, the output of which is blocked while the second counter counts. Upon the second count cycle, the second counter provides an output signal representative of an angular position with respect to UDC position, which is representative of the count state stored in the multiplex or memory circuit when deriving the speed-representative number. By changing the initial or final count during the second count cycle in the second counter, the ignition timing as a function of additional operating parameters can be considered.

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Schwieberdingen, Germany

Jurgen Fresow