Internal-combustion engines – Combustion chamber means combined with air-fuel mixture...
Patent
1993-10-26
1995-09-05
Nelli, Raymond A.
Internal-combustion engines
Combustion chamber means combined with air-fuel mixture...
F02P 514
Patent
active
054471362
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention concerns an ignition system according to the introductory part of claim 1.
In a modern ignition system for internal combustion engines, in particular for motor vehicles, there are a group of requirements some of which seem incompatible.
To obtain a good level of efficiency, the timing of the ignition of the fuel/air mixture in the cylinder must be very precise. For this high ignition energy must be provided. If one assumes normal operation, this high energy must be applied to the spark plug for only a short time. However, under unfavorable conditions, burning of the fuel/air mixture cannot be assured with short ignition current phases. For this reason, high voltage capacitor ignition, which is favorable for normal operation, has not been able to prevail.
Because of the exhaust regulations and because of the use of catalytic converters, misfires are extremely undesirable. In order to avoid misfiring, the prior art consists in significantly over-dimensioning the electrical ignition energy. This occurs in the known ignition systems according to the introductory part of claim 1, among other things, in that the ignition current is maintained for a relatively long time interval after the jump of the spark independently of the ignition process.
The prior art technology in this regard has the disadvantages that it damage (destruction of the catalytic converter) by timely service intervention. firing precision as well as the service life of the spark plugs.
The object of the invention is to provide an ignition system according to the introductory part of claim 1 which offers high protection against misfires with extensively minimized burning of the spark plug electrodes.
The preceding object is accomplished through the characteristics of claim 1.
In the ignition system according to the invention, the ignition current for each ignition process is maintained after the jumping of the spark in each case only as long as is absolutely necessary for burning of the fuel/air mixture. Under normal conditions, this time is very short. However, under severe conditions it can also be relatively long. By means of the adjustment of the duration of the ignition current permitted by the ignition system according to the invention to the respective need, burning of the electrodes of the spark plugs is overall largely reduced. Furthermore, the ignition system according to the invention can very simply also be used to indicate increased danger of backfires and/or the occurrence of misfires, by additionally monitoring if and when burning occurs within the predetermined maximum time interval until the switching off of the ignition device for the individual cylinders.
The subclaims concern preferred embodiments of the ignition system according to claim 1.
The invention is explained below with reference to two exemplary embodiments using the drawings.
The figures depict:
FIG. 1 the block diagram of the first embodiment, and
FIG. 2 the block diagram of the second embodiment.
In both exemplary embodiments depicted in the drawings, the ignition device individually allocated to each cylinder of the internal combustion engine for each cylinder has a separate ignition module, which can be switched on and off rapidly, i.e., virtually without delay and permits delivery in the switched-on state of an ignition current of indefinite length to the respective spark plug. Furthermore, the individual firings in the cylinders or the absence of burning during the maximum switched-on time of the ignition module is detected by sensor, and the respective ignition module is switched off immediately after successful burning of the fuel/air mixture in the associated cylinder. An ignition device suitable for this is described, for example, in patent application P 39 28 726.2 dated Aug. 30, 1989. The sensor required for this may also be used simultaneously as a knock sensor. It is also possible to use a shared acoustic sensor.
The basic idea of the ignition system according to the invention is to permit a spark to be applied in each case
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Hartmann Ingrid
Mai Udo
Nelli Raymond A.
Vogt Electornic AG
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