Process and device for the analysis of the acoustic characteristic of an exhaust gas flap

1. A process for the analysis of an acoustic characteristic of an exhaust gas flap for an exhaust system of an internal combustion engine, wherein the exhaust gas flap comprises a flap diaphragm and a flap body wherein the flap diaphragm is adjustable in the flap body, the process comprising the steps of:

applying a measurement noise to the exhaust gas flap, wherein the measurement noise is a single tone;

detecting disturbing noises originating at the exhaust gas flap and generating a disturbing noise time course;

generating a disturbing noise frequency course based on the disturbing noise time course;

comparing the disturbing noise frequency course with a reference disturbing noise frequency course in at least one predetermined frequency range; and

evaluating of the acoustic characteristic of the exhaust gas flap based on the comparison, wherein a quality of the exhaust gas flap is evaluated as a desired quality, when the disturbing noise frequency course is below the reference disturbing noise frequency course in at least one predetermined frequency range.

2. A process in accordance with claim 1 , wherein the step of applying a measurement noise to the exhaust gas flap comprises:

integrating the exhaust gas flap into an analysis device;

providing the analysis device, wherein the analysis device comprises:

a sound feed duct area to be positioned in a sound flow direction upstream of the flap body adjoining the flap body;

a sound removal duct area to be positioned in a sound flow direction downstream of the flap body adjoining the flap body; and

a measurement noise source for generating the measurement noise to be sent via the sound feed duct area to the exhaust gas flap.

3. A process in accordance with claim 1 , wherein:

the measurement noise has a frequency less than/equal to 40 Hz; or

the measurement noise has a frequency in the range of 20 Hz to 40 Hz.

4. A process in accordance with claim 1 , wherein the disturbing noise frequency course is generated by means of Fourier analysis comprising fast Fourier transformation.

5. A process in accordance with claim 1 , wherein:

the reference disturbing noise frequency course is determined on the basis of disturbing noise frequency courses generated in association with a plurality of exhaust gas flaps; or

the reference disturbing noise frequency course is selected in association with a measurement noise generated for the step of applying a measurement noise to the exhaust gas flap.

6. A device for the analysis of an acoustic characteristic of an exhaust gas flap for an exhaust system of an internal combustion engine, wherein the exhaust gas flap comprises a flap diaphragm, which is adjustable in a flap body, the device comprising:

a sound feed duct area to be positioned in a sound flow direction upstream of the flap body adjoining the flap body;

a sound removal duct area to be positioned in a sound flow direction downstream of the flap body adjoining the flap body or/and provided by the flap body;

at least one measurement noise source configured to generate a single tone measurement noise to be sent via the sound feed duct area to the exhaust gas flap;

at least one noise sensor for the detection of disturbing noises sent along the sound removal duct area;

an actuating unit for an actuation of the at least one measurement noise source for the generation of a measurement noise; and

an analysis device for the receipt of an output signal of the at least one noise sensor, which output signal represents a disturbing noise time course, wherein the analysis device is configured to generate a disturbing noise frequency course based on the disturbing noise time course and to compare the disturbing noise frequency course with a reference disturbing noise frequency course in at least one predetermined frequency range and to evaluate the acoustic characteristic of the exhaust gas flap based on the comparison.

7. A device in accordance with claim 6 , wherein the actuating unit is configured to actuate the at least one measurement noise source for the generation of different measurement noises.

8. A device in accordance with claim 6 , wherein:

the measurement noise has a frequency less than/equal to 40 Hz; or

the measurement noise has a frequency in the range of 20 Hz to 40 Hz.

9. A device in accordance with claim 6 , wherein the disturbing noise frequency course is generated by means of Fourier analysis comprising fast Fourier transformation.

10. A device in accordance with claim 6 , wherein the analysis device is further configured to evaluate a quality of the exhaust gas flap as a desired quality, when the disturbing noise frequency course is below the reference disturbing noise frequency course in at least one predetermined frequency range.

11. A device in accordance with claim 6 , wherein:

the analysis device is further configured to determine the reference disturbing noise frequency course on the basis of disturbing noise frequency courses generated in association with a plurality of exhaust gas flaps; or

the analysis device is further configured to select the reference disturbing noise frequency course in association with a measurement noise generated for the step of applying a measurement noise to the exhaust gas flap.

12. A process for the analysis of an acoustic characteristic of an exhaust gas flap for an exhaust system of an internal combustion engine, the process comprising the steps of:

providing an exhaust gas flap structure comprising a flap diaphragm and a flap body, wherein the flap diaphragm is adjustable in the flap body, the exhaust gas flap structure comprising an exhaust gas flap structure acoustic quality;

applying a single tone measurement noise to the exhaust gas flap structure;

detecting disturbing noises generated by the exhaust gas flap structure and generating a disturbing noise time course based on the disturbing noises generated by the exhaust gas flap structure;

generating a disturbing noise frequency course based on the disturbing noise time course;

comparing the disturbing noise frequency course with a reference disturbing noise frequency course in at least one predetermined frequency range;

evaluating the acoustic characteristic of the exhaust gas flap structure based on the comparison;

determining the exhaust gas flap structure acoustic quality as a desired acoustic quality when the disturbing noise frequency course is below the reference disturbing noise frequency course in at least one predetermined frequency range.

13. A process in accordance with claim 12 , wherein the step of applying a measurement noise to the exhaust gas flap structure comprises:

integrating the exhaust gas flap structure into an analysis device;

providing the analysis device, wherein the analysis device comprises:

a sound feed duct area to be positioned in a sound flow direction upstream of the flap body adjoining the flap body;

a sound removal duct area to be positioned in a sound flow direction downstream of the flap body adjoining the flap body; and

a measurement noise source for generating the measurement noise to be sent via the sound feed duct area to the exhaust gas flap structure.

14. A process in accordance with claim 12 , wherein:

the measurement noise has a frequency less than/equal to 40 Hz; or

the measurement noise has a frequency in the range of 20 Hz to 40 Hz.

15. A process in accordance with claim 12 , wherein the disturbing noise frequency course is generated by means of Fourier analysis comprising fast Fourier transformation.

16. A process in accordance with claim 12 , wherein:

the reference disturbing noise frequency course is determined on the basis of disturbing noise frequency courses generated in association with a plurality of exhaust gas flap structures; or

the reference disturbing noise frequency course is selected in association with a measurement noise generated for the step of applying a measurement noise to the exhaust gas flap structure.