EP0608229A1

EP0608229A1 - Ignition system for internal combustion engines.

Info

Publication number: EP0608229A1
Application number: EP92907839A
Authority: EP
Inventors: Udo Mai; Uwe Hartmann
Original assignee: Vogt Electronic AG
Current assignee: Vogt Electronic AG
Priority date: 1991-04-30
Filing date: 1992-04-03
Publication date: 1994-08-03
Anticipated expiration: 2012-04-03
Also published as: DE59207020D1; JPH06506747A; DE4114087A1; WO1992019863A1; US5447136A; EP0608229B1

Abstract

Un système d'allumage se caractérise par une fiabilité élevée concernant les ratés d'allumage et par une usure minimale des bougies d'allumage. A cet effet, chaque dispositif d'allumage (5), parmi plusieurs dispositifs d'allumage qui sont individuellement associés à chaque cylindre, est enclenché en synchronisation avec le moment prescrit d'allumage du cylindre correspondant, peut fournir dans son état enclenché, un courant d'allumage à la bougie d'allumage pendant une période indéterminée, et est déclenché immédiatement de manière réglable par un capteur (1) qui détecte la combustion dans le cylindre lorsque le mélange carburant/air dans le cylindre s'est enflammé. Le dispositif d'allumage (5) est déclenché dans tous les cas pour chaque cylindre, une fois une période maximale prédéterminée écoulée, même lorsque la combustion n'a pas eu lieu. Dans un autre mode de réalisation, le dispositif d'allumage (5) est déclenché dans tous les cas une première fois, indépendamment du capteur (1), une fois qu'une durée qui correspond au délai normal entre l'enclenchement du dispositif d'allumage et la combustion s'est écoulée, et n'est enclenché de nouveau que lorsque le capteur (1) ne détecte pas ou ne détecte plus de combustion.An ignition system is characterized by high reliability with regard to misfiring and minimal spark plug wear. To this end, each ignition device (5), among several ignition devices which are individually associated with each cylinder, is engaged in synchronization with the prescribed ignition moment of the corresponding cylinder, can provide in its engaged state, a ignition current to the spark plug for an indefinite period, and is triggered immediately in an adjustable manner by a sensor (1) which detects combustion in the cylinder when the fuel/air mixture in the cylinder has ignited. The ignition device (5) is triggered in any case for each cylinder, once a predetermined maximum period has elapsed, even when combustion has not taken place. In another embodiment, the ignition device (5) is triggered in all cases a first time, independently of the sensor (1), once a duration which corresponds to the normal delay between the switching on of the device of ignition and combustion has elapsed, and is only triggered again when the sensor (1) does not detect or no longer detects combustion.

Description

description

Ignition system for internal combustion engines

The invention relates to an ignition system according to the introductory part of patent claim 1.

A number of demands are made of a modern ignition system for internal combustion engines, in particular of motor vehicles, which sometimes seem to be incompatible

To achieve good efficiency, the ignition of the fuel / air mixture in the cylinder must be very precise in time. A large ignition energy must be provided for this. Assuming normal operation, this high energy only has to be applied to the spark plug for a short time. In unfavorable conditions, the ignition of the fuel-air mixture with short ignition current phases is not guaranteed. For this reason, the high-voltage capacitor ignition (HKZ), which is in itself advantageous for normal operation, has not been able to establish itself.

Misfire is extremely undesirable because of emissions regulations and the use of catalysts. In order to avoid misfires, it is state of the art to considerably oversize the electrical ignition energy. This is done in the known ignition systems according to the introductory part of claim 1, inter alia, in that the ignition current after the ignition spark has skipped is maintained for a relatively long period of time regardless of the ignition process.

The known related technology has the disadvantages that it

- Ultimately, misfires cannot be prevented with certainty.

^_ Does not provide information on misfiring to avoid consequential damage (destruction of the catalytic converter) through timely service.

- A high spark plug burn-up causes the ignition precision and the service life of the spark plugs to be reduced.

The invention has for its object to provide an ignition system according to the introductory part of claim 1, which offers high security against misfires with largely minimized spark plug wear.

The above object is achieved by the features of claim 1.

In the ignition system according to the invention, the ignition current for each ignition process is only maintained for as long as is absolutely necessary to ignite the fuel-air mixture after the ignition spark has jumped over. In normal cases, this period is very short. It can also be relatively long under difficult conditions. As a result of the matching of the ignition current duration to the respective requirement made possible by the ignition system according to the invention, the spark plug burn-up is minimized as far as possible. In addition, the ignition system according to the invention can also be used in a very simple manner for one indicate the occurrence of misfires and / or the occurrence of misfires increased risk by observing zusätz¬ Lich, if and when within the vorbestimm ^¬ th maximum time until shutdown of Zündein¬ direction for individual cylinders flashings the stattfin¬.

The subclaims relate to preferred configurations of the ignition system according to claim 1.

The invention is explained in more detail below using two exemplary embodiments with reference to the drawing.

The drawing shows:

Fig.l the block diagram of the first embodiment, and

2 shows the block diagram of the second embodiment.

In both of the exemplary embodiments shown in the drawing, the ignition device individually assigned to each cylinder of the internal combustion engine has a separate ignition module for each cylinder, which can be switched on and off quickly, ie practically without delay, and one in the switched-on state can supply unlimited combustion current to the respective spark plug. In addition, the individual inflammations in the cylinders or the absence of enflammations during the maximum on-time of the ignition modules are sensed and the respective ignition module is switched off immediately after the ignition of the fuel / air mixture in the associated cylinder. A suitable ignition device is described, for example, in patent application P 39 28 726.2 dated August 30. Described in 1989. The sensor required for this can also be used as a knock sensor. It could also be a common acoustic sensor can be used.

The basic idea in the ignition system according to the invention is to have an ignition spark applied only until the fuel / air mixture is ignited in the cylinder. Most of the time, this process is very short and, accordingly, the required electrical ignition energy is small. In rare cases where there is no immediate ignition, the ignition current continues to flow through the spark plug until the mixture becomes ignitable. The amplitude of the ignition current preferably increases progressively in order to facilitate the ignition process. The same also applies to the high voltage if there is initially no sparking. The ignition processes are preferably monitored not only with regard to the occurrence or non-occurrence of inflammations but also with regard to the time period between the target ignition point and the actual ignition, and if longer ignition delays occur more frequently, this fact can be recorded in the on-board computer and the driver be displayed as a warning of an increased risk of misfiring. This enables early service intervention before misfires occur. On the other hand, the display of misfires draws the user's attention to the fact that the further operation of the engine is immediately at high risk for it or for parts thereof, e.g. the catalyst.

In the embodiment according to FIG. 1, the ignition module provided separately for each cylinder is designated by 5. For each cylinder there is a separate sensor in the form of a pressure sensor that responds to the pressure prevailing in the cylinder.

The sensor 1 sends its signal of the mixture pressure to a comparator 2. This compares the signal with a reference limit voltage, which is selected so that only signals from sensor 1 reach the comparator output, which are triggered by a pressure in the cylinder that is greater than the compression. An OR gate 3 transmits these signals to a flip-flop 4, which was previously set by ignition timing electronics 7, and resets it. The FF 4 switches the ignition module 5 on in the set state and off in the reset state. Regardless of the comparator 2, the FF 4 is reset via the OR gate 3 if there is no ignition after about half a crankshaft rotation by a signal from the ignition timing electronics 7 and the ignition is therefore switched off in any case. This process is recognized and displayed (error signal). If the switching on of the ignition and the ignition of the mixture coincide very closely, the ignition timing is delayed by the ignition timing electronics 7 in order to avoid knocking. A further error signal, which may be output via a separate line, is delivered by the ignition timing electronics 7, if there is ignition, the time between the switching on of the ignition module for the desired ignition time p _. point and the ignition, however, exceeds a predetermined duration. To form the error signals, the ignition timing electronics 7 receive information from the output of the FF 4 about the switch-on and switch-off times of the respective ignition modules 5.

Instead of the pressure sensor 1, an optical sensor could also be used for each of the cylinders.

In the exemplary embodiment according to FIG. 2, a conventional sound sensor for knock detection is used as sensor 1 'for detecting the explosive ignition in the individual cylinders. The ignition timing electronics 7 'here take over the switching on and off of the respective ignition modules 5', of which just as in the embodiment 1 is provided separately for each cylinder. A multiple switch 10 controlled by the camshaft sensor 6 'creates time windows for differentiating the individual cylinders. A circuit arrangement is arranged downstream of each time window, which essentially corresponds to the circuit arrangement with components 2, 3 and 4 in the embodiment according to FIG. 1 and performs the same function as this. The components are designated 2 ', 3' and 4 'here. Just as in FIG. 1, the ignition electronics 7 receive information about the piston positions through the camshaft sensor designated here 6 ', which delivers a signal corresponding to the instantaneous angular position of the camshaft. The power supply for the ignition modules 5 'is provided by a power supply unit 8' which corresponds to the power supply unit 8 provided for the same purpose in the embodiment according to FIG. 1.

The setting of the FF 4 'and its resetting at the end of the predetermined maximum period of time is carried out in the ignition timing electronics 7' by the usual microprocessor 11, which is also provided in the embodiment according to FIG. 1 (not shown there) and which controls the engine Signals corresponding to operating data, the signals of the camshaft sensor 6 'and, if appropriate, further signals which have been entered into it and are important for the operation of the machine are evaluated and linked in a program-controlled manner.

The embodiment according to FIG. 2 thus differs from the embodiment according to FIG. 1 essentially in that instead of a separate sensor 1 for each

Cylinder, a sensor 1 'common to all cylinders is provided.

According to claim 11, a modification to the above-described mode of operation is that for each of the cylinders, the ignition device, in the case of the embodiment Examples according to FIGS. 1 and 2, ie the relevant ignition module, switched on for the desired target ignition time as there, after one of the normal ignition delays, ie the delay that normally occurs between the switching on of the ignition and the Time of ignition, corresponding time period switched off again independently of the sensor and only switched on again within the predetermined maximum time period provided for the ignition process with ignition, if necessary repeatedly, if the sensor responsible for the cylinder does not Inflammation reports or has reported. This procedure allows an inertia of the sensors and / or the increase in pressure in the cylinder associated with the ignition to be taken into account in such a way that, in the normal case, there is no unnecessary extension of the spark plug burning time. The above-mentioned error and warning signals can of course also be formed and displayed in this case by appropriate monitoring.

Claims

1. Ignition system for internal combustion engines with an individually assigned to the cylinders, controlled on and off and suitable for delivering an unlimited combustion current to the spark plugs suitable ignition device (5, 5 '), characterized by at least one sensor (1,1') for detecting the Inflammation of the fuel / air mixtures in the individual cylinders and by electronics controlled by this sensor (1 ') / these sensors (1), which the ignition device (5,5') for the respective cylinder immediately after the ignition has occurred in it, in any case, it switches off after a predetermined maximum period of time following the target ignition timing.

2. Ignition system according to claim 1, characterized by one sensor (1) for each cylinder.

3. Ignition system according to claim 2, characterized in that the sensor (1) is a pressure sensor or an optical sensor.

4. Ignition system according to claim 1, characterized by a single sensor (l ¹ ) for several or all cylinders.

5. Ignition system according to claim 4, characterized in that the sensor (I ¹ ) is a vibration sensor.

6. Ignition system according to claim 5, characterized in that the vibration sensor is a microphone or piezoelectric element mounted on the internal combustion engine.

7. Ignition system according to one of the preceding claims, characterized in that the sensor (l ¹ ) / the Senso¬ ren (1) are also used to detect knocking.

8. Ignition system according to one of the preceding claims, characterized in that the electronics measures the delay between the target ignition timing and the ignition for each individual cylinder and delivers a display signal if delays are of a predetermined size exceed, occur frequently.

9. Ignition system according to one of the preceding claims, characterized in that the electronics deliver a geson¬ deres display signal when there are no flames in the cylinders.

10. Ignition system according to one of the preceding claims, characterized in that the ignition device (5,5 ') delivers a progressively increasing ignition voltage and / or a progressively increasing ignition current for each cylinder for each ignition process.

11. Modification of the ignition system according to one of the preceding claims, characterized in that the electronics, the ignition device (5,5 ') after a period corresponding to the normal ignition delay, independently of the sensor (1') / the sensors (1 ) switches off again immediately and only then within the pre-determined overall for the ignition process with ignition The maximum period of time is switched on again, if necessary at repeated times, if the sensor (1, 1 ') responsible for the respective cylinder does not report or have reported no ignition.