EP0632864A1

EP0632864A1 - Arrangement for determining the parameters of an internal combustion engine.

Info

Publication number: EP0632864A1
Application number: EP94900001A
Authority: EP
Inventors: Ingobert Adolf; Guenther Herdin; Michael Hoetger; Walter Picker; Franz Pockstaller
Original assignee: Jenbacher Energiesysteme AG
Current assignee: Jenbacher Energiesysteme AG
Priority date: 1993-01-28
Filing date: 1993-10-27
Publication date: 1995-01-11
Anticipated expiration: 2013-10-27
Also published as: DE59306980D1; DK0632864T3; JPH07505694A; US5560338A; US5505177A; ATE155850T1; ES2105595T3; WO1994017297A1; AT301U1; EP0632864B1

Abstract

An arrangement for determining the parameters of an internal combustion engine, in particular an Otto engine operating with gaseous fuels, has at least one optical sensor for observing the emission of light caused by the combustion in a combustion chamber of the internal combustion engine and at least one photodetector for converting the light emitted into electric signals which are processed in an evaluation unit. In order to achieve a rapid and accurate regulation, the evaluation unit (11) has an arrangement (15) for determining the maximum or mean intensity of the light emitted during each combustion cycle on the basis of the corresponding electric signal. The evaluation unit (11) further has a regulating unit (17) which regulates at least one engine parameter depending on the intensity maxima.

Description

Device for recording engine parameters

Internal combustion engine

The invention relates to a device for detecting engine parameters of an internal combustion engine, in particular a gasoline engine operated with gaseous fuels, with at least one optical sensor for observing the light emission caused by the combustion in a combustion chamber of the internal combustion engine and with at least one photodetector Conversion of the light emission into electrical signals, which are processed in an evaluation device.

It has already been proposed to use the light emission caused by the combustion in a combustion chamber in order to regulate engine parameters. The light is led out of the engine without disturbing the other combustion processes via an optical pick-up which is attached to the engine and generally a light-guiding element leading into the combustion chamber (in the simplest case a so-called combustion chamber window). The optical pickup can also be integrated in the spark plug.

So far, a control signal for controlling the ignition timing has mainly been obtained from the position of the light emission over time.

From DE-OS 35 05 063 a control device for a motor is known in which the difference between the maximum value of the light intensity and one of several

Maximum values formed mean represents the controlled variable. When this difference is formed, the information goes about the absolute value; of the maximum value is lost. The known control device ultimately serves to regulate the uneven running of the engine. With which engine parameters, in particular with which fuel-air ratio

ßBUtfT (REGEL26} Ratio (lambda) the desired smoothness occurs is irrelevant there. There is therefore no regulation to a specific fuel-air ratio.

The object of the invention is to create a device of the type mentioned at the outset with which it is possible to precisely control at least one engine parameter.

According to the invention this is achieved in a device of the type mentioned in that the

Evaluation device comprises a device for determining the intensity maximum of the light emission of each combustion cycle in the corresponding electrical signal and the evaluation device further comprises a control unit which controls at least one engine parameter as a function of the intensity maxima.

While the position of the light emission was evaluated over time in the known proposals, it is proposed according to the invention, the level of the

To use intensity maximums of the light emission in order to record an engine parameter and preferably to control engine parameters via a control unit. Such an engine parameter is, in particular, the fuel-air ratio (lambda). However, other engine parameters such as the ignition timing, the boost pressure, the engine temperature etc. can in principle be regulated depending on the intensity maximum or the integral value of the intensity of the light emission of each combustion cycle. The maximum of the light emission, which is reflected in the electrical signal of the photodetector, can easily be determined by an electronic evaluation device and fed to the actual value input of a control device which then adjusts or controls at least one motor parameter as a function thereof. In order to smooth fluctuations in the light emission in individual successive combustion cycles, it is expedient for the device for determining the intensity maximum to be followed by an averager which emits a signal corresponding to the mean value from the intensity max a of a predeterminable number of combustion cycles, and that the output of the mean value generator is connected to the actual value input of the control unit. The maximum intensity can be averaged over 20 to 100 cycles, for example.

A further preferred embodiment is characterized in that the evaluation device has a device for detecting misfires, which on the one hand receives signals related to the light emission and on the other hand receives signals dependent on a sensor from the crankshaft angle or the piston position of the engine and which provides an output signal at its output for an electrical signal below a threshold value at a point in time or time window dependent on the crankshaft angle or on the piston position in which the ignition normally takes place. The signals emitted by the device for detecting misfires can, for example, be counted and can cause an emergency shutdown of the engine if there are a certain number or frequency of misfires.

It is also possible to feed the signals from the device for detecting misfires to the mean value generator. In order to avoid falsified averages, this can simply ignore combustion cycles with misfires in the averaging. It has been shown in particular in the investigation of gas engines that the radicals formed during the ignition emit light in a certain frequency range, particularly in the ultraviolet range (approx. 200 nm to 350 nm). By means of an optical bandpass filter, which is preferably connected upstream of the photodetector, one can now specifically evaluate a specific spectral range, a so-called spectral window, and use the maximum light emission occurring in this spectral window to regulate motor parameters. In the case of a gas engine, it has been found that the intensity of the radiation in the UV region is strongly dependent on the combustion gas / air ratio, a higher intensity occurring with smaller lambda values. This can be used to achieve lambda control on the basis of the light intensity of the UV emission. At the same time, it is of course also possible to regulate other engine parameters, for example the ignition timing on the basis of the light emission of each combustion cycle.

From a design point of view, it is particularly advantageous if a bandpass filter, preferably a colored glass filter, is arranged in or on the optical pickup, for example by using specially doped

It is possible for types of glass that the material which does not conduct outward from the combustion chamber itself has bandpass filtering properties and can therefore form a bandpass filter per combustion chamber if this is desired.

A further advantageous embodiment of the invention consists in that in a multi-cylinder internal combustion engine for cylinder-selective control of the engine parameters, an optical pickup is arranged on the combustion chamber of each cylinder, each with its own photodetector and its own evaluation device belongs to a control unit which controls the engine parameters of the respective cylinder as a function of the electrical signals and adjustable setpoints corresponding to the light emission of the respective cylinder. The cylinder-selective control of engine parameters, for example the fuel-air ratio for each cylinder individually, permits more precise control and operation of the engine. In principle, it is of course also conceivable and possible, depending on the light emission of at least one combustion chamber, to control one or more engine parameters for several combustion chambers simultaneously.

Further advantages and details of the invention are explained in more detail in the following description of the figures.

Show it:

1 shows a schematic cross section through the cylinder head area of a cylinder with an optical pick-up inserted, FIG. 2 shows in a block diagram the evaluation device for an exemplary embodiment of the invention, and FIG. 3 schematically shows a multi-cylinder internal combustion engine with a cylinder-selective combustion gas Air-mixture control as a function of the light emission from the individual combustion chambers. Fig. 4 shows a self-calibration device in one

Block diagram

The optical sensor (probe), designated overall by 1, is inserted in the cylinder head 7 of a cylinder of an internal combustion engine and held by means of a union nut 3. The optical pickup 1 comprises a light-conducting glass rod 2, which extends into the combustion chamber 9 above the bulb 8. In addition, the optical pickup comprises an optical waveguide plug adapter 4, which makes it possible to detachably connect an optical waveguide to the outer end of the glass rod 2, in particular in the form of a flexible optical fiber 6, via an optical waveguide plug 5. For this purpose, only the optical fiber connector 5 must be inserted into the optical fiber connector adapter 4 in the direction of the arrow 10. So it is possible that

Light that is generated during combustion in the combustion chamber 9 is first fed to an evaluation device via the glass rod 2 and then via the flexible optical fiber 6. The flexible optical fiber allows the electronic evaluation device to be installed remotely and can be easily replaced in the event of damage.

2 is an exemplary embodiment of such an evaluation device 11. The light detected by an optical pick-up 1 from a combustion chamber is supplied to the electronic evaluation device 11 via an optical fiber 6 (for example, which is particularly transparent to the UV range). The optical fiber 6 can also be detachably connected to the evaluation device. At the input of the evaluation device, a photodetector 12 (for example a UV photodiode with a spectral sensitivity range from 185 to 1150 nm) converts the light into electrical signals, which are then amplified in an amplifier 13 and in one

High pass or band pass filter 14 are filtered. The electrical signals corresponding to the light emission are then passed by a device 15 for determining the intensity maximum of the light emission of each combustion cycle. The output signal present on line 16 thus reflects the maximum intensity of the light Emission of each combustion cycle again, it being possible, for example, for a high-pass filter or band-pass filter to be integrated in the optical pickup in order to observe only one spectral window. The filter can be formed by the glass rod 2, which consists of special glass. However, it is also possible to use a special filter element. Measurements have shown, among other things, that the radicals which arise during the ignition emit light in the ultraviolet range (approx. 200 nm to 350 nm). The intensity of this

Radiation is very strongly dependent on the lambda (high intensity with a small lambda). A relatively precise lambda control can thus be implemented on the basis of the light intensity of the UV emission. Knocking can also be detected by means of UV emission.

The same applies to the wavelengths around 600 nm (solid-state radiators), these wavelengths being considerably easier to transmit and detect. Knock detection is more difficult at these wavelengths, since the solids continue to glow when knocked and the higher-frequency knock information is thus partially lost. As a compromise, it is beneficial to effectively observe a wavelength window of approximately 185 to 600 nm. Since the UV photodiode is below

185 nm is insensitive anyway, an optical high-pass filter is sufficient for this, which is only permeable to wavelengths smaller than 600 nm.

In principle, the signal present on line 16 could be fed to the control unit 17, which then controls an engine parameter (for example the fuel / air ratio) via an output amplifier 18 and a motor parameter adjustment device (for example a mixture adjustment device 19). To avoid fluctuations in the individual combustion cycles smoothing, however, it is more advantageous if the output signals on line 16 are averaged over a number of, for example, 10 to 100 cycles, for example 30 cycles, that is to say the mean value of the intensity maxima is determined over a predeterminable number of combustion cycles. This takes place in the mean value generator 18, the output 19 of which is connected to the actual value input 20 of the control unit 17.

As an alternative to the embodiment described, instead of the maximum value, the integral value of the light intensity can be used for the averaging during the burning period. In and of itself, the signals of both methods are identical, but the integral values have a smoother course over the lambda than the peak values (= maximum values). However, this requires a greater computing effort to obtain the integral values.

The probe drift (eg due to contamination of the combustion chamber probe) can be compensated for by a self-calibration device which acts, for example, on an additional input 36 of the amplifier 14 for the drift correction. With this device, the contamination can be determined during engine operation and a respective correction signal can be generated (FIG. 4).

A light pulse is fed into the optical waveguide from the self-calibration device 37 at an arc-controlled angle. This light pulse continues via the optical waveguide 6 and the combustion chamber window 6 into the combustion chamber, from where it is reflected. The reflected pulse then returns to the self-calibration device 37. The intensity of the reflected pulse is a measure of the pollution of the combustion chamber window. With this size can then For example, the evaluation device is tracked (input 36). The self-calibration process is started by the self-calibration trigger device 38 whenever no combustion is taking place (e.g. change TDC or during compression). This is the same combustion chamber window and the same optical waveguide as in the evaluation unit described above. The evaluation device and the self-calibration device are decoupled via optics.

In addition, a device 21 for detecting misfires is provided in FIG. 2, which signals are related to the light emission via the line 16 and signals dependent on the crankshaft angle or the piston bearing of the engine via a sensor 22 receives. Transducers for detecting the crankshaft angle or the piston bearings of the engine are well known to the person skilled in the art and need not be described in more detail here. They generally emit a certain trigger signal at a certain motor position. The device 21 for the detection of misfires now checks whether light emission occurs in a certain time window, which is determined by the trigger signal from the sensor 22. This should normally be the case if the ignition is successful. If this is not the case, it outputs a corresponding signal at its output 23, which indicates a misfire. This signal can be supplied to a logic block "inhibit" in the mean value generator 18, which causes those combustion cycles in which combustion misfires occur to be disregarded when averaging. This means that there is no falsification of the mean value for individual misfires. Misfires can also be communicated via line 34 to the emergency shutdown device 35, which, however, switches off the engine at a certain frequency of misfires.

The part of the evaluation device essentially comprising parts 1, 6, 12, 13, 14, 15 (and possibly 18) represents an "optical lambda probe ^M , which is a function of the absolute value of the fuel-air ratio provides a corresponding analog signal at output 19. Such a lambda probe can also be marketed and used independently of the following control unit, but it is of course also possible to implement the electrical components of the lambda probe and control unit 17 together.

The control unit 17 comprises a setpoint generator 25 via which the desired setpoint of the motor parameter can be set. A control difference xd results from the comparison of the set value w with the actual value x (intensity maximum averaged over several cycles in a spectral window). This is fed to stage 26, which then emits an actuating signal for regulating an engine parameter at its output. The control loop is thus closed.

In stage 14, as indicated by dashed lines 28, control differences xd of several optical sensors 1 can be connected. This level then takes, for example, the greatest value of all connected control differences for the calculation of the manipulated variable y. For example, in a multi-cylinder internal combustion engine which is only equipped with a single gas lift mixer, the combustion gas / air ratio can be regulated as a function of the light emission in all cylinders. However, cylinder-selective control is also conceivable and inexpensive, as is shown, for example, in FIG. 3. A five-cylinder internal combustion engine 29 is shown there as an example. The optical pickups 1, which are each connected to the electronic evaluation device 11 'via flexible optical fibers 6, extend into the combustion chamber of each cylinder. This electronic evaluation device 11 'essentially comprises five evaluation devices 11, as shown in FIG. 2. Each of these evaluation devices 11 receives, via a line 30, a signal determined by a transducer 31, which indicates the crankshaft angle. A cylinder-selective control of engine parameters takes place via the evaluation devices 11, in the embodiment of the combustion gas shown in FIG. Air ratio of each individual cylinder. For this purpose, a control line 32 leads from each evaluation device 11 to the individual adjusting devices 33 for the combustion gas / air ratio. With this device it is therefore possible to regulate specific engine parameters in a cylinder-selective manner as a function of the light emission of each combustion cycle.

Claims

Patent claims:

1.Device for detecting engine parameters of an internal combustion engine, in particular a gasoline engine operated with gaseous fuels, with at least one optical sensor for observing the light emission caused by the combustion in a combustion chamber of the internal combustion engine and with at least one photodetector for converting the light emission into electrical signals are processed in an evaluation device, characterized in that the evaluation device (11) comprises a device (15) for determining the maximum or the integral value of the light emission of each combustion cycle in the corresponding electrical signal and preferably an the absolute value of the maximum or the Provides integral value reflecting output signal.

2. Device according to claim 1, characterized in that the means (15) for determining the maximum or the integral value is followed by an averager (18) which emits a signal corresponding to the mean value from the intensity maxima or intensity integral values of a predeterminable number of combustion cycles.

3. Device according to claim 1 or 2, characterized gekenn¬ characterized in that the evaluation device has a device (21) for detecting misfires, which on the one hand with the light emission coherent signals and on the other hand by a sensor (22) from the crankshaft angle or Piston position of the engine receives signals and which, when an electrical signal is below a threshold value, at a time or time window dependent on the crankshaft angle or on the piston position, in which normally the ignition takes place, on its output (23) delivers an output signal.

4. Device according to claim 2 and 3, characterized in that the output (23) of the device (21) for detecting misfires is connected to the averager (18), and the averager (18) is designed such that he ignores combustion cycles with misfires when averaging.

5. Device according to claim 3 or 4, characterized gekenn¬ characterized in that the output (23) of the device (21) for detecting misfires with an emergency shutdown device (35) connected to a stop from a certain number or a certain frequency of misfires of the internal combustion engine.

6. Device according to one of claims 1 to 5, characterized in that an optical filter (2), preferably high-pass filter, the photodetector (1) is connected upstream.

7. Device according to claim 7, characterized in that the filter characteristic of the filter and the sensitivity range of the photodetector are selected such that there is also a wavelength observation window lying in the UV range.

8. Device according to claim 6 or 7, characterized gekenn¬ characterized in that the detected wavelength range is between 150 and 650 nm.

9. Device according to one of claims 1 to 8, characterized in that between the optical pickup (1) At least one flexible optical fiber (6) is arranged on the motor (29) and the evaluation device (11).

10. Device according to one of claims 6 to 9, characterized in that an optical filter, preferably a colored glass filter (2) is arranged in or on the optical pickup (1).

11. The device according to claim 10, characterized in that the light from the combustion chamber to the outside Ma¬ material (2), preferably glass, itself has bandpass filtering properties and preferably forms the only optical bandpass filter per combustion chamber.

12. Device for controlling motor parameters with a device according to one of claims 1 to 11, characterized in that the evaluation device (11) further comprises a control unit (17) which, depending on the intensity maxima or integral values of the Intensity regulates at least one motor parameter.

13. The device according to claim 2 and 12, characterized gekenn¬ characterized in that the output (19) of the averager (18) with the actual value input (29) of the control unit (17) is connected.

14.Device for controlling engine parameters of an internal combustion engine, in particular a gasoline engine operated with gaseous fuels, with at least one optical sensor for observing the light emission caused by combustion in a combustion chamber of the internal combustion engine and with at least one photodetector for converting the light emission into electrical signals are processed in an evaluation device, in particular according to one of claims 1 to 12, characterized in that at a multi-cylinder internal combustion engine (29) for cylinder-selective control of the engine parameters, an optical sensor (1) is arranged on the combustion chamber (9) of each cylinder, each of which has its own photo detector and its own evaluation device (11) with a control unit, the engine parameters of the respective cylinder are regulated as a function of the electrical signals and adjustable setpoints corresponding to the light emission of the respective cylinder.

15. Device according to claim 14, characterized in that a common device (31) for detecting the crankshaft angle or piston position is provided for all evaluation devices (11).

16. Device according to one of claims 1 to 15, characterized in that a mixture adjustment device (19, 33) is provided, via which the composition of the fuel-air mixture supplied to the internal combustion engine can be regulated as a function of the light emission in the combustion chamber.

17. Device for calibrating an optical pickup in an internal combustion engine, in particular for one

Device according to one of claims 1 to 16, marked by a light source which transmits light to the receiver, and furthermore a detection device for detecting the light drive returning from the sensor.

18. The device according to claim 17, characterized in that the light is then sent to the sensor when it receives no measuring light caused, for example, by combustion in the combustion chamber.

19. Use of a device according to one of claims 1 to 18 for regulating engine parameters of an internal combustion engine, in which the gas-air mixture is passed through a compressor, preferably a turbocharger, before it enters the combustion chambers.

20. Use of an optical pickup, with which the light emission in a combustion chamber of an internal combustion engine is detected, and an evaluation device connected to it, which supplies an electrical signal corresponding to the maximum or the integral value of the light emission of a combustion cycle, for regulating the Force-air ratio of the internal combustion engine to a predetermined value.