Title of Invention

DEVICE FOR MONITORING THE COMBUSTION PROCESS IN INTERNAL COMBUSTION ENGINES

Abstract A device for monitoring the combustion process in internal combustion engines is propesed, direct monitoring which is assigned to individual combustion processes, in particular individual combustion chambers being possible. This is achieved using a waveguide which projects into the combustion chamber.
Full Text

ROBERT BOSCH GMBH, 70442 Stuttgart
Device for monitoring the combustion process in internal combustion engines
Prior art
In internal combustion engines, in particular in diesel engines, the combustion dynamic has always played a large role in achieving the objective of good engine characteristics. The most precise possible control of the optimum ignition time and the most exact possible metering of the fuel quantity injected by the injection system are advantageous in this regard. In recent engine developments, the possibilities of intervening in the dynamics of the combustion in a controlling fashion have been further improved.
Hitherto, the combustion process has been monitored by checking the exhaust gas values. The Lambda probes which have come into circulation in particular in conjunction with controlled catalytic converters sense the composition of the exhaust gas and use it to obtain information on the combustion process. On the basis of this information it is possible to intervene in the engine control in a regulating fashion.
This form of combustion monitoring has the disadvantage that it does not take place directly in the combustion chamber, as a result of which there is a certain delay time between the respective combustion process which is taking place, the acquisition of the necessary information from the analysis of the exhaust gas and the subsequent regulating intervention in the engine control. Furthermore, the examination of the exhaust gas has the disadvantage that during the exhaust gas analysis averaging is performed over the combustion processes which take place in different combustion chambers, i.e. in different cylinders in conventional internal combustion engines. According to

the prior art* the examination of the exhaust gas cannot be used to consider individual combustion processes, in particular even individual cylinders, in a differentiated way-Advantages of the invention
The object of the invention is therefore to propose a device for monitoring the combustion in which the abovementioned delay time is reduced and in which it is possible to monitor individual combustion processes, in particular in a way which is differentiated with respect to individual combustion chambers.
This object is achieved by means of the characterizing features of Claim 1, taking the prior art specified at the beginning as a starting point.
Advantageous embodiments and developments of the invention are possible by virtue of the measures specified in the subclaims.
Accordingly, a monitoring device according to the invention is characterized in that a waveguide for electromagnetic radiation is integrated into a component which leads into a combustion chamber of an internal combustion engine. This measure makes it possible to observe, outside the combustion chamber, the electromagnetic radiation occurring during the combustion, and acquire information on the dynamics of the combustion process accordingly.
In this context, the radiation occurring in the visible or infra-red ranges is preferably analyzed, and the waveguide is correspondingly matched to this wavelength range. Because very high temperatures occur during the combustion, the main part of the radiation spectrum emitted by the hot, compressed gas in the combustion chamber is located in the abovementioned wavelength range.

The maximum intensities of the emitted radiation are thus present in this wavelength range and can be sensed by means of a sensor at the output of the waveguide. The intensity of the emitted radiation can be picked up resolved with respect to time, from which ir is already possible to obtain important information on the combustion dynamics. In particular, the ignition time and the duration of the fuel injection, for example, can be detected from this. Such an intensity distribution can also be used as a basis for drawing conclusions about the quantity of injected fuel.
In one development of the invention, a sensor which is suitable for frequency analysis is arranged at the output of the waveguide. By means of frequency analysis of the emission spectrum in the interior of the combustion chamber it is possible to draw a precise conclusion about the temperature prevailing there. Conventional pyrometers also operate according to this principle. The temperature profile in the interior of the combustion chamber can therefore be sensed resolved with respect to time using such a sensor device in conjunction with the waveguide according to the invention.
The waveguide is preferably integrated into a component which is present in any case in known engines and leads into the combustion chamber. These components can be the spark plugs in spark-ignition engines, for example, or the glow plugs in diesel engines.
The material of the waveguide is preferably selected in such a way that it has essentially the same coefficient of thermal expansion as that of the adj acent material. Because very high temperatures may prevail, at least temporarily, in the interior of the internal combustion engine, between 900°C and 1000°C in the case of diesel engines, the aforesaid selection of material ensures that the stresses occurring at the limits of the material are minimal so that a permanently good connection is ensured between the

waveguide and the adjacent material. A good material connection is indispensable to ensure the seal of the component, for example of the glow plug.
In one development of the invention, the component is fabricated from ceramic material. In particular in the case of glow plugs, more recent developments have in any case already tended towards selecting a structure made of ceramic material because, in addition to the high level of temperature-resistance, this also makes it possible to implement glow plugs which have a fast reaction time and a long service life.
Using ceramic materials is also advantageous in terms of the implementation of a waveguide according to the invention because a large number of glasses which are suitable as waveguides have a similar degree of thermal expansion, with the result that the integration of the waveguide into the corresponding component is simplified.
In one particular embodiment of the invention, a conventional lightguide is embedded into the material of a glow plug. Such cable-shaped or rod-shaped lightguides are commercially available and therefore readily available. Light-guiding fibres or fibre bundles are also possible. In all cases, the wave-guiding function is ensure by means of the arrangement of the material with a varying refractive index, so that light is directed in the longitudinal direction of the waveguide.
In a glow plug, the waveguide can be embedded either into a current-conducting layer or else even into an insulating layer. This is preferably decided on an application-specific basis depending on the materials present in a respective glow plug and the material of the light guide, such that the embedding is possible in the easiest possible way on the basis of these material properties.

As has already been repeatedly mentioned, high temperatures prevail in the interior of the combustion chamber. At least the end of the waveguide which projects into the interior of the combustion chamber must be capable of withstanding these temperatures. This can cause problems under certain circumstances with lightguides which are currently commercially-available. In this case, for example the front end, i.e. the one projecting into the combustion chamber, of the waveguide can be arranged in such a way that it does not lead into the region of the tip of the glow plug but rather further behind it. The temperature-loading of the glow plug decreases from the inwardly projecting tip towards the rear end.
In one advantageous embodiment, the waveguide can also be constructed by means of peripheral layering of different layers which are transparent in the visible or infra-red range and which have different refractive indices. High-temperature-resistant glasses with the necessary optical characteristics are already available for this design, said glasses being compatible, in terms of their thermal expansion behaviour, with the ceramics used in glow plugs.
The information acquired with the monitoring device according to the invention is used to perform active control of an internal combustion engine. For this purpose, a regulating unit is provided for regulating different engine control parameters. For example, the ignition time can be performed [sic] on the basis of the sensor signal picked up at the output of the waveguide. Furthermore, for example, the injection quantity and/or even the time profile of the injection of the fuel can be controlled on the basis of this sensor signal.
Finally, the air intake system can also be controlled by means of the regulating unit on the basis of such a sensor signal.

All the known or future control parameters for influencing the engine characteristics can ultimately be regulated in an optimum way using the monitoring device according to the invention.
Moreover, the monitoring device can also be used to check the function of engine components, for example the fuel injectors. Satisfactory functioning of the fuel injectors is of the utmost importance for the service life of the engine. A fuel injection which is too long or which takes place at the wrong time can lead to overheating of the engine and thus to an engine defect. The monitoring device according to the invention can thus detect a malfunction in a fuel injector in good time, and the fuel injector can be replaced or repaired.
Basically, it is conceivable to use the monitoring device according to the invention to perform all checking processes which are provided by the acquired information. It would also be conceivable, for example, to monitor the engine compression on the basis of the internal temperatures sensed in the combustion chamber.
Exemplary embodiment
An exemplary embodiment of the invention is illustrated in the drawing and will be explained in more detail below with reference to the figures.
In detail:
Fig. 1 shows a schematical longitudinal section through a glow plug with a monitoring unit according to the invention,
Fig. 2 shows a rear view of a glow plug according to Fig. 1,
Fig. 3 shows a further embodiment of a glow plug according to the invention,
Fig. 4 shows a third embodiment of a glow plug according to the invention, and

Fig. 5* shows an enlarged detail of the portion of Fig. 4 indicated by V.
The monitoring device 1 according to Fig. 1 is integrated into a glow plug 2 composed of 2 conductive layers 3, 4 and an intermediate insulating layer 5. In the present case a light guide 6 is embedded into the conductive layer 3. It leads into the region of the tip 7 of the glow plug.
A glow plug housing 8 is indicated in the rear region of the glow plug 2 and is insulated from the conductive layer 4 by means of an insulating layer 9.
Contact is made with the conductive layers 3, 4 by means of two contact faces 10, 11, the conductive layer 3 in this case being connected to the earth of the engine by means of the contact face 11.
The design according to Fig. 3 corresponds essentially to the exemplary embodiment described above, the lightguide 6 now being embedded into the interior of the insulating layer 5.
In contrast, in the embodiment according to Fig. 4, the waveguide 12 is applied to the periphery by means of a layered structure 13. This layered structure 13 is illustrated by way of example in Fig. 5 in an enlarged view. It is composed of three glass layers 14, 15, 16. The glass is selected in each case in such a way that total reflection takes place at the interface between the outer glass layers 15, 16 and the inner glass layer 14. In this way, light in the interior of the glass layer 14 is directed in a- leftward direction to the rear end of the glow plug (see arrow) in terms of the illustration according to Fig. 4. In this exemplary embodiment, the waveguide 11 is arranged, as it were, as an outer tube around the glow plug 2.

t of reference numerals:
Monitoring device Glow plug Conductive layer Conductive layer Insulating layer Lightguide Tip of glow plug Glow plug housing Insulation Contact face Contact face Waveguide Layered structure Glass layer Glass layer Glass layer




Claims:
1- Device for monitoring the combustion process in internal combustion engines, a component which leads into a combustion chamber being provided, characterized in that the component . (2) which leads into the combustion chamber comprises a waveguide (6, 12) for electromagnetic radiation.
2. Device according to Claim 1, characterized in that the waveguide (6, 12) is conductive in the visible or in the infra-red range.
3. Device according to one of the preceding claims, characterized in that a sensor for sensing the intensity of the incoming radiation is provided at the output of the waveguide (6, 12).
4. Device according to one of the preceding claims, characterized in that a sensor which is suitable for frequency analysis of the incoming radiation is provided at the output of the waveguide (6, 12) .
5. Device according to one of the preceding claims, characterized in that the component which leads into the combustion chamber is a glow plug (2) or a spark plug.
6. Device according to one of the preceding claims, characterized in that the material of the waveguide (6, 12) has a coefficient of thermal expansion which is matched to the coefficient of thermal expansion of the adjacent material.
7. Device according to one of the preceding claims, characterized in that the component (2) which projects into the combustion chamber comprises ceramic material.
8. Device according to one of the abovementioned claims, characterized in that the waveguide (6, 12) is embedded into the material of the component (2) which projects into the combustion chamber.

9. Device 0 according to one of the preceding claims, characterized in that the waveguide (6) is embedded into a conductive layer (3, 4) and/or into an insulating layer (5) of a glow plug (2).
10. Device according to one of the preceding claims, characterized in that the waveguide (12) is formed by peripheral layering (13) of different layers (14, 15, 16) which are transparent in the visible and/or infra-red wavelength range and have different refractive indioes.
11. Device according to one of the preceding claims, characterized in that a regulating unit is provided for controlling the ignition time on the basis of the sensor signal picked up at the output of the waveguide (6, 12).
12. Device according to one of the preceding claims, characterized in that a regulating unit is provided for controlling the injection quantity and/or the time profile of the injection of the fuel on the basis of the sensor signal picked up at the output of the waveguide (6, 12) .
13. Device according to one of the preceding claims, characterized in that a regulating unit is provided for controlling the air intake system on the basis of the sensor signal picked up at the output of the waveguide (6, 12) .
14. Device according to one of the preceding claims, characterized in that a monitoring unit is provided for monitoring engine components on the basis of the sensor signal picked up at the output of the waveguide (6, 12).
15. Device according to one of the preceding claims, characterized in that the monitoring unit is provided for monitoring the function of fuel injectors.
16. Glow plug for an internal combustion engine, characterized in that a monitoring device (1) according to one of the preceding claims is provided.

17. Spark plug for an internal combustion engine, characterized in that a monitoring device (1) according to one of the preceding claims is provided.

18. Device for monitoring the combustion process in internal combustion
engines substantially as herein described with reference to the
accompanying drawings.
19. Spark plug substantially as herein described with reference to the
accompanying drawings.


Documents:

in-pct-2001-488-che-abstract.pdf

in-pct-2001-488-che-claims filed.pdf

in-pct-2001-488-che-claims granted.pdf

in-pct-2001-488-che-correspondnece-others.pdf

in-pct-2001-488-che-correspondnece-po.pdf

in-pct-2001-488-che-description(complete)filed.pdf

in-pct-2001-488-che-description(complete)granted.pdf

in-pct-2001-488-che-drawings.pdf

in-pct-2001-488-che-form 1.pdf

in-pct-2001-488-che-form 19.pdf

in-pct-2001-488-che-form 26.pdf

in-pct-2001-488-che-form 3.pdf

in-pct-2001-488-che-form 5.pdf

in-pct-2001-488-che-other documents.pdf

in-pct-2001-488-che-pct.pdf


Patent Number 212004
Indian Patent Application Number IN/PCT/2001/488/CHE
PG Journal Number 02/2008
Publication Date 11-Jan-2008
Grant Date 13-Nov-2007
Date of Filing 04-Apr-2001
Name of Patentee M/S. ROBERT BOSCH GMBH
Applicant Address Postfach 30 02 20, 70442 Stuttgart
Inventors:
# Inventor's Name Inventor's Address
1 KUGLIN, Eckart Kraehwinkelweg 21, D-71229 Leonberg
2 GEISSINGER, Albrecht Theodor-Heuss-Strasse 41 D-75147 Mühlacker
3 LINDEMANN, Gert Lerchenweg 10 D-72805 Lichtenstein
4 LOCHER, Johannes C.P.O. Box 4703, Rok-1064 Seoul
5 DRESSLER, Wolfgang Steinhaldenweg 7, D-71665 Vaihingen/Enz
6 LINDNER, Friederike Immelmannstrasse 24, D-70839 Gerlingen
7 ROTHACKER, Volker Brombergerstrasse 24, D-74321 Bietigheim-Bissingen
8 KERN, Christoph Wilhelmstrasse 5, D-71546 Aspach
PCT International Classification Number F02D 35/02
PCT International Application Number PCT/DE99/02895
PCT International Filing date 1999-09-11
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 19846356.1 1998-10-08 Germany