DE102008004905A1 - Method for detecting leakages in exhaust system of internal combustion engine, particularly in motor vehicle, involves recording and analyzing sounds developed during operation of internal combustion engine - Google Patents

Abstract

The method involves recording and analyzing the sounds developed during operation of an internal combustion engine inside or outside the exhaust system (1), particularly compared with one another. The recording of sounds is executed by two acoustic sensors (6.1,6.2) in the proximity of the exhaust system, and an analysis of the recording is executed in a time and frequency range. An independent claim is included for a device for detecting leakages in an exhaust system of an internal combustion engine, particularly in a motor vehicle.

Description

The The invention relates to a method and a device for detection of leaks in an exhaust system of an internal combustion engine, in particular on a motor vehicle.

With increasing demands on the emission behavior of motor vehicles, correspondingly high demands are placed on the tightness of the exhaust systems of motor vehicles. Especially in modern diesel vehicles, the emission standard Euro 6 The exhaust systems include multiple interfaces, for example between an exhaust gas turbocharger and a pipeline, and between the pipeline and an exhaust aftertreatment box. These interfaces require the testing of their tightness in order to ensure the operability of the exhaust system.

From the DE 10 2004 013 435 A1 a method for leak testing of an exhaust system of an internal combustion engine is known in which the air in the exhaust system is pumped out and the negative pressure generated thereby is checked and the result of the test is used to assess the tightness.

One such procedure requires a relative complex arrangement for generating and measuring the negative pressure and is applicable only when the engine of the motor vehicle. Small leaks are not detected in a short measurement period or require a correspondingly longer measurement duration. A Localization of the leak is not possible.

It is therefore an object of the invention, an improved method and a simplified device for detecting leaks to indicate an exhaust system of a motor vehicle.

The The object is achieved by a method having the features of claim 1. The device concerning the task according to the invention by the features specified in claim 11 solved.

advantageous Further developments are the subject of the dependent claims.

at a method for detection according to the invention of leaks in an exhaust system of an internal combustion engine, in particular on a motor vehicle, are at a in operation located internal combustion engine inside and / or outside recorded and analyzed the noise occurring in the exhaust system, especially compared with each other. There are different Spectra from within (air pressure fluctuations) and / or outside (Leakage leakage noise) of the exhaust system occurring Sounds optionally at different positions, in particular detected outside the exhaust system and compared with each other. A allows such carried out during operation of the system measurement a quick and easy as well as robust exhaust system test on a leak.

in the Detail is a first record of sounds by means of two acoustic sensors near the exhaust system carried out. Subsequently, a first analysis the first recording in the time and / or frequency domain, for example by means of a suitable frequency analysis program.

there be recorded frequencies, amplitudes and orders of the Noises determined. Next is at least a second Recording of noise is performed at the one of the acoustic sensors near a to be examined area of the exhaust system is performed. Finally, a second analysis of the second record performed in the time and / or frequency domain, with a Difference between those at the first analysis and the second analysis obtained data is determined. From the determined difference can be concluded whether the exhaust system in the investigated area is tight or not, because in case of a leak not only the outside the exhaust system typical noises but also additional Leakage noises occur.

With the method according to the invention is a fast Detecting leaks within a few seconds while in progress Internal combustion engine possible. In addition, the process also provides a place of leaks. By the difference measurement between two acoustic sensors can be an absolute volume and frequency position of the sounds are disregarded stay.

Preferably For example, in the first recording, both acoustic sensors are essentially arranged in the same position to the exhaust system, so no significant differences between the sounds of the first Recording occur.

Especially the first record will be in a tightly accepted area the exhaust system performed. This can be, for example be an uninterruptible pipeline.

The second recording, however, is preferred in each case at an interface performed between two components of the exhaust system, for example, between an exhaust gas turbocharger and a pipeline and between the pipeline and an exhaust aftertreatment box.

While the second record remains the other of the acoustic sensors preferably in the same place as in the first recording, in particular then, if it is largely ensured that there are no leaks available.

For the difference can in particular be specified at least one threshold value by means of which the area examined at the second record classified as leaking or leaking.

to Recording the sounds is preferably a stereo probe microphone used, in which the two acoustic sensors are integrated.

Regarding The device is at least one acoustic sensor at different Positions arranged outside the exhaust system, wherein the detected by the acoustic sensor noise signals an analysis unit for evaluation, in particular for comparison can be fed. Here is or are the or the acoustic Sensors at different positions in the exhaust system, in particular Can be arranged outside of this.

in the Following are exemplary embodiments and advantages of Invention explained in more detail with reference to drawings.

there demonstrate:

1 an exhaust system in a first step of a method for detecting leaks, and

2 the exhaust system in a second step of the method for detecting leaks.

each other corresponding parts are the same in both drawings Provided with reference numerals.

In 1 is an exhaust system 1 an internal combustion engine of a motor vehicle shown. Exhaust gases of the internal combustion engine are after passing through an exhaust gas turbocharger 2 through a pipeline 3 an exhaust aftertreatment box 4 fed. The turbocharger 2 is at an interface 5.1 with the pipeline 3 connected.

The exhaust aftertreatment box 4 closes over the interface 5.2 to the pipeline 3 at. The interfaces 5.1 . 5.2 are susceptible to leaks and must be checked to ensure emission limits. This is done with the internal combustion engine by means of two acoustic sensors 6.1 . 6.2 First, a first record of noise is performed.

The sounds are in an analysis unit 7 recorded and analyzed in the time and / or frequency domain. In particular, frequencies, amplitudes and orders of the first record are determined.

In 2 is the exhaust system 1 out 1 shown. Deviating from 1 here is the acoustic sensor 6.1 for a second recording near the interface 5.1 positioned. The acoustic sensor 6.2 remains in the previous position.

The sounds are back in the analysis unit 7 recorded and analyzed in the time and / or frequency domain.

Based of differences found between those in the analysis of the first and the second record obtained may be inferred whether the digit examined in the second recording is a Leaking.

For the interface 5.2 another second record is made in the same way.

The second recording and analysis can be done for more than two interfaces 5.1 to 5.n or other areas to be investigated.

The acoustic sensor 5.1 . 5.2 can be guided along the area to be examined during the second recording.

The first record may alternatively be in another area of the exhaust system 1 , but preferably in a range assumed to be tight.

For the difference can in particular be specified at least one threshold value by means of which the area examined at the second record classified as leaking or leaking.

For recording the sounds preferably a stereo probe microphone is used, in which the two acoustic sensors 6.1 . 6.2 are integrated.

1

exhaust system

2

turbocharger

3

pipeline

4

Abgasnachbehandlungsbox

5

interface

6

audible sensor

7

analysis unit

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004013435 A1 [0003]

Cited non-patent literature

• - Euro 6 [0002]

Claims (13)

Method for detecting leaks in an exhaust system ( 1 ) of an internal combustion engine, in particular on a motor vehicle, characterized in that when the internal combustion engine is in operation inside and / or outside the exhaust system ( 1 ) occurring noises and analyzed, in particular compared with each other. Method according to claim 1, characterized in that a first recording of noises by means of two acoustic sensors ( 6.1 . 6.2 ) near the exhaust system ( 1 ) and a first analysis of the first recording in the time and / or frequency range is carried out so that at least a second recording of noises is carried out, in which one of the acoustic sensors ( 6.1 . 6.2 ) in the vicinity of an area of the exhaust system to be examined ( 1 ), wherein a second analysis of the second recording in the time and / or frequency domain is performed, whereby a difference between the data obtained in the first analysis and the second analysis is determined. Method according to claim 2, characterized in that in the first recording both acoustic sensors ( 6.1 . 6.2 ) substantially in the same position to the exhaust system ( 1 ) to be ordered. A method according to claim 2 or 3, characterized in that the first record in an assumed as dense area of the exhaust system ( 1 ) is carried out. Method according to one of the preceding claims 2 to 4, characterized in that the first recording on an uninterruptible pipeline ( 3 ) is carried out. Method according to one of the preceding claims 2 to 5, characterized in that the second record at an interface ( 5.1 to 5.n ) between two components of the exhaust system ( 1 ) is carried out. Method according to claim 5 or 6, characterized in that the second record is recorded once at the interface ( 5.1 ) between an exhaust gas turbocharger ( 2 ) and the pipeline ( 3 ) and once at the interface ( 5.2 ) between the pipeline ( 3 ) and an exhaust aftertreatment box ( 4 ) is carried out. Method according to one of the preceding claims 2 to 7, characterized in that the other of the acoustic sensors ( 6.2 . 6.1 ) remains in the same position at the second recording as at the first recording. Method according to one of the preceding claims 2 to 8, characterized in that for the difference at least one threshold is given, by means of which at The second record examined area classified as leaking or leaking becomes. Method according to one of the preceding claims, characterized in that a stereo probe microphone is used to record the noise, in which acoustic sensors ( 6.1 . 6.2 ) are integrated. Device for detecting leaks in an exhaust system ( 1 ) of an internal combustion engine, in particular on a motor vehicle, characterized in that at least one acoustic sensor ( 6.1 . 6.2 ) is provided, which is in internal combustion engine inside and / or outside of the exhaust system ( 1 ) detected position-related, wherein the detected values of the acoustic sensor or sensors ( 6.1 . 6.2 ) an analysis unit ( 7 ) which can supply the values of the acoustic sensor (s) ( 6.1 . 6.2 ), in particular compares with each other. Apparatus according to claim 11, characterized in that the one or more acoustic sensors ( 6.1 . 6.2 ) at different positions in the exhaust system ( 1 ), in particular outside this can be arranged or are. Apparatus according to claim 11 or 12, characterized in that the one or more acoustic sensors ( 6.1 . 6.2 ) are integrated in a stereo probe microphone.