Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1989-04-05
1990-07-17
Nelli, Raymond
Internal-combustion engines
Charge forming device
Fuel injection system
36443103, F02P 700
Patent
active
049414461
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is directed to an ignition and fuel injection back-up system for emergency running or starting internal combustion engines in which a Hall sensor drum is driven synchronously with a cam shaft of the engine and delivers a timing pulse to a computer at the beginning of an ignition cycle, the computer controls the ignition, possibly while taking into account additional engine data, and the Hall sensor drum has a cut out portion for every cylinder or every second cylinder, which cut out portions cause a corresponding quantity of timing pulses whose trailing edges occur at a uniform rotational angle before the top dead center of the respective cylinder.
In ignition systems with cylinder recognition, it is known to utilize Hall sensor drums in the ignition distributor, which sensor drum comprises a cut out portion which produces one timing pulse per 720.degree. crankshaft revolution. During the timing pulse, a reference mark is derived e.g. from the toothed rim or from the flywheel of the crankshaft. This reference mark occurs once per revolution of the crankshaft, so that only every second reference mark occurs in the time period of a timing signal. Accordingly, the timing signal and the reference mark together designate the beginning of an ignition cycle from which an exact determination of the optimal ignition times for respective cylinders of the engine can be effected in a microprocesor while taking into account additional engine data, particularly while taking into account the speed or rate of rotation. In the event of the failure of the transmitter for the reference mark or the speed, respectively, in such a system, the engine can no longer continue to be operated.
SUMMARY OF THE INVENTION
In contrast, an ignition and injection system according to the invention is characterized in that one of the cut out portions of the sensor drum is constructed so as to be wider than the others and causes a wider timing pulse relative to the rest of the timing pulses, and in that the beginning of an ignition cycle is detected when an additional reference mark derived from a toothed rim or from the flywheel of the crankshaft occurs during the wider timing pulse. The invention has the advantage that the additional cut out portion in the sensor drum which are assigned to the individual top dead centers of the cylinders produce a timing signal in each instance by means of a Hall sensor, from which a defined fixed ignition angle can be determined. An enlarged cut out portion or phase window, which produces a wider timing pulse, indicates the beginning of an ignition cycle when a reference mark occurs in this phase window. The other phase windows must be sufficiently narrow so that the second reference mark does not occur therein in the course of two revolutions, so that an unambiguous cylinder recognition is ensured. In practice, for emergency running and possibly starting, the timing pulses represent the closing time for the ignition coil and the injection pulses, respectively, wherein the ignition spark is produced during the occurrence of the trailing edge of the timing pulses. This has the advantage not only that an emergency running ignition angle function is realized in a simple manner in the event of disturbance, but also that an earlier commencement of ignition, and accordingly shorter starting times, are achieved also when starting the engine.
The ignition angle can lie e.g. 10.degree. before the top dead center. Moreover, the speed can be determined from the time interval between the trailing edges, and a closing time which is adapted to the speed and during which the ignition coil is charged can be determined by the computer, as can the injection time. An optimization of the emergency running ignition angle function is achieved by means of this step. The emergency running function can also be improved in that the speed is determined from the fixed trailing edges, a delay time for the commencement of closing and a delay time for the ignition being determined from the la
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Denz Helmut
Moz Rudolf
Uttenweiler Winfried
Nelli Raymond
Robert & Bosch GmbH
Striker Michael J.
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