Method for operating an internal combustion engine, and controller for carrying out the method

Abstract

The invention relates to a method for operating an internal combustion engine with fuel which is combusted using a spark plug. According to the invention, the aging of the spark plug, in particular the aging of an electric resistor of the spark plug, is monitored during the operation of the internal combustion engine, wherein electromagnetic radiation of the spark plug is detected for monitoring purposes. The invention additionally relates to a controller for carrying out the method.

Claims

1. A method for operating an internal combustion engine with a fuel ignited by means of a spark plug, the method comprising: monitoring aging of the spark plug during the operation of the internal combustion engine, and detecting electromagnetic radiation of the spark plug.

2. The method as claimed in claim 1, wherein a current electrical resistance of the spark plug is determined on the basis of the detected electromagnetic radiation.

3. The method as claimed in claim 1, wherein changes in the electromagnetic radiation of the spark plug are detected and compared with a characteristic resistance profile of a known wear model.

4. The method as claimed in claim 3, wherein the remaining life of the spark plug until its failure is estimated on the basis of the recorded changes in the electromagnetic radiation and the known wear model.

5. The method as claimed in claim 1, wherein an operating strategy of the internal combustion engine is adjusted on the basis of the detected electromagnetic radiation.

6. The method as claimed in claim 1, wherein an antenna is used for the detection of the electromagnetic radiation of the spark plug.

7. The method as claimed in claim 1, wherein data generated during the detection of electromagnetic radiation are processed in a control unit of the internal combustion engine.

8. The method as claimed in claim 1, wherein data generated during the detection of electromagnetic radiation are processed in an external control unit, wherein the data are transmitted to the external control unit wirelessly via a telematics and/or cloud service.

9. The method as claimed in claim 1, wherein classification algorithms stored in the control unit are used to distinguish the electromagnetic radiation of the spark plug from other radiation in the environment, for the calculation of the current electrical resistance, or both.

10. The method as claimed in claim 1, wherein a detected altered electromagnetic radiation is assigned to a previously defined damage class.

11. An electronic control unit configured to claim 1 monitor aging of a spark plug during operation of an internal combustion engine, detect, via an antenna, electromagnetic radiation of the spark plug, determine a current electrical resistance of the spark plug based on the detected electromagnetic radiation, and compare changes in the detected electromagnetic radiation with a characteristic resistance profile of a wear model.

12. An electronic control unit as claimed in claim 11, further configured to estimate a remaining life of the spark plug based on changes in the electromagnetic radiation and the wear model.

13. An electronic control unit further comprising at least one classification algorithm and wherein the electron control unit is configured to distinguish the electromagnetic radiation of the spark plug from other radiation in the environment using the at least one classification algorithm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in more detail below on the basis of the attached drawings. In the figures:

(2) FIG. 1 shows a spark plug known from the prior art,

(3) FIG. 2 shows a graphical representation of a characteristic resistance profile of a spark plug over its lifetime, and

(4) FIG. 3 shows a graphical representation of a prediction model.

DETAILED DESCRIPTION

(5) The spark plug shown in FIG. 1 is used in externally ignited internal combustion engines to ignite a fuel air mixture with a spark between two electrodes 1, 2. For this purpose, a high-voltage pulse is directed to a first electrode 1 by a system insulated from the motor, from which a spark then jumps across to the further electrode 2. The thermal energy of the jumping spark then ignites the fuel-air mixture.

(6) The first electrode 1 is accommodated in a central cavity 3 of a sleeve-shaped insulator 4 and is therefore also referred to as a central or middle electrode. It consists of a nickel alloy and has a copper core. The further electrode 2 is a ground electrode 2 which is spaced apart from the first electrode 1. It also consists of a nickel alloy. The spark plug technology and the service life can be influenced by their arrangement and/or geometry.

(7) In the central cavity 3 of the sleeve-shaped insulator 4, a connection bolt 5 is accommodated at the other end, which is preferably made of steel and is thus electrically conductive. The required high-voltage pulse is fed to the middle electrode 1 via the connection bolt 5. To limit the ignition current, an electrical resistance 6, which is realized in the present case by a glass melt 7, is arranged between the connection bolt 5 and the middle electrode 1. The electrical resistance 6 reduces the burn-off and thus the wear of the middle electrode 1. In addition, the electrical resistance 6 reduces the electromagnetic radiation emitted to the environment.

(8) In the present case the sleeve-shaped insulator 4 is surrounded by a likewise sleeve-shaped housing 8, which is made of steel in the present case and is nickel-plated for protection against corrosion. The housing 8 can be used, for example, for fixing the spark plug in a cylinder head of an internal combustion engine of an engine. A sealing ring 9 arranged on the outside of the housing 8 is used to seal a combustion chamber of the internal combustion engine. To insulate the connection bolt 5 and the middle electrode 1 from the housing 8, the insulator 4 consists predominantly of alumina.

(9) The spark plug, in particular the electrical resistance of the spark plug, is subject to aging processes. A characteristic resistance curve over the lifetime of the spark plug is shown in FIG. 2.

(10) As can be seen from the profile of FIG. 2, the electrical resistance can initially increase in the short term, for example due to a formation of the glass melt or ceramic that serves as the electrical resistance. After that, the electrical resistance decreases, first quickly and then slowly but continuously. As a result, electrode burn-off and electromagnetic radiation increase. Shortly before the end of the spark plug life, the electrical resistance rises again, so that failure of the spark plug can occur.

(11) In order to prevent this, according to the method according to the invention, the aging of the spark plug or the aging of the electrical resistance of the spark plug in the combustion engine is monitored, so that the spark plug can be replaced in good time. The replacement is therefore state-based and not time-related. This allows maintenance intervals to be extended and time and costs to be saved.

(12) In order to monitor the aging of the spark plug or the aging of the electrical resistance of the spark plug, the electromagnetic radiation of the spark plug is detected during the operation of the internal combustion engine. Electromagnetic radiation increases when the electrical resistance decreases, so that due to this physical relationship the electrical resistance can be determined on the basis of the detected electromagnetic radiation.

(13) If aging of the electrical resistance has been detected, the operating strategy can be adjusted during operation of the internal combustion engine to compensate for the disadvantages resulting from the aging, such as an increased electrode burn-off and/or increased electromagnetic coupling. In this way, progressive aging can be counteracted, which in turn favors longer maintenance intervals.

(14) As can be seen from FIG. 3 by way of example, a prediction model can be created with the help of the detected electromagnetic radiation. For the preparation of the prediction model of FIG. 3, the changes in electromagnetic radiation detected by means of a radiation receiver were assigned or classified in advance. Based on the historical profile of the assigned damage classes, a certain development, in this case the failure of the spark plug, can be predicted, which occurs when a predetermined threshold value 10 is reached.

(15) The prediction can be made within a confidence band 11, the width of which is specified in FIG. 3 with the dimension x. Furthermore, it can be calculated after how many kilometers and/or how many further operating hours the ignition plug is likely to fail, so that the spark plug can be replaced beforehand.

(16) At known operating points of the internal combustion engine, such as the engine speed, the dwell angle and/or the ignition time, the relevant electromagnetic radiation can be distinguished from other radiation in the environment by means of appropriate classification algorithms, for example by means of data mining.

(17) Furthermore, the state of the spark plug resistance can be calculated with the help of these classification algorithms.

(18) The proposed method can be used not only for internal combustion engines of motor vehicles, but also in the case of stationary internal combustion engines, which are used to generate energy, for example. Due to the size of such engines, the advantages of the invention are particularly evident here.

(19) Irrespective of whether they are stationary or mobile internal combustion engines, existing internal combustion engines can be upgraded during retrofitting of engines which are suitable for carrying out the method according to the invention. For this purpose, only a suitable radiation receiver, such as a directed antenna, has to be arranged in the engine compartment and connected to a control unit and/or an evaluation device in a data-transmitting manner. This does not necessarily have to be an engine control unit but can also be realized by means of suitable external hardware.