Device and method for the early recognition and prediction of unit damage

• US 20050049835A1
• Filed: 07/03/2002
• Published: 03/03/2005
• Est. Priority Date: 09/07/2001
• Status: Active Grant

• Current Assignee: Ramsle Technology Group GmbH LLC (Intellectual Ventures LLC)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Spiegelberg, Gernot, Schwarzhaupt, Andreas, Mayer, Christian-Michael
• Granted Patent: US 7,039,557 B2
• Time in Patent Office: Days
• US Class Current: 702/184
• CPC Class Codes: G07C 3/00 Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
• CPC Class Codes: G07C 5/00 Registering or indicating the working of vehicles
• CPC Class Codes: G07C 5/0808 Diagnosing performance data testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005

Abstract

The present invention relates to a device and a method for the early detection and prediction of damage to assemblies in machine plants, in particular also to mobile machine plants. For this purpose, the structure-borne sound of the machine system is sensed by a sensor (1) and output as an acceleration signal and analyzed in a digital signal processor (DSP). In this context, in order to avoid negative influences of ambient vibrations or structure-borne sounds which are not associated with the state of the machine plant, the acceleration signal is firstly transformed into the frequency domain by means of a fast-Fourier transformation, and the data obtained in this way is then transformed again into the time domain by means of cepstrum analysis so that resonance data relating to individual shock pulses (a cepstrum) is obtained in the time domain. This cepstrum is then compared with a comparison cepstrum which is available in accordance with load signals and rotational speed signals for the present operating state in a new machine plant in a storage device. When limiting values are exceeded, the diagnostic signal, in particular information relating to the assembly which is diagnosed as damaged and its predicted remaining service life, are displayed for the user and an emergency operating mode is initiated.

Claims

1-18. -18. (Cancelled).

19. A device for early detection and prediction of damage to assemblies in a machine plant, comprising:

at least one sensor for sensing structure-borne sound of the machine plant to be monitored, and emitting a measuring signal;

an analog/digital converter device for converting the measuring signal into a digital measuring signal;

a digital signal processor with a fast-Fourier transformation device for carrying out a transformation of the digital measuring signal into the frequency domain, and a cepstrum analysis device for generating resonance data relating to individual shock pulses in the time domain from the fast-Fourier-transformed digital measuring signal; and

a storage device having stored therein a parent cepstrum for a new machine plant for various operating states, together with an empirical value matrix relating to damaged assemblies and assembly components and anticipated remaining service lives;

wherein,

the digital signal processor compares the present cepstrum and a reference cepstrum representative of a new machine plant, which reference spectrum is selected in response to rotational speed information and load information, is assigned to this operating state and is read out of the storage device;

a monitoring device monitors the comparison result of the present cepstrum and associated reference cepstrum to detect instances in which limiting values are exceeded, and forwards information relating to the digital signal processor formed by means of upward transgression of the limiting values; and

the digital signal processor determines, in response to the information provided by the monitoring device from the present cepstrum, a damaged assembly or assembly component with reference to the empirical value matrix, and its predicted remaining service life, and outputs to a central processor unit for further processing, a diagnostic signal, including information relating to damaged assemblies and their predicted remaining service life.

20. The device as claimed in claim 19, wherein, to determine the predicted remaining service life of a damaged assembly or assembly component, the digital signal processor also takes into account stored information regarding the history of the machine plant.

21. The device as claimed in claim 19, wherein the central processor unit displays the information contained in the diagnostic signal, relating to damaged assemblies and their predicted remaining service lives, on a display device for the user or transmits said information by telemetry to a corresponding workshop or a machine plant operator.

22. The device as claimed in claim 19, wherein, in response to diagnostic signal for the assemblies which are diagnosed as damaged, the central processor unit implements an emergency operating mode to prevent or reduce further damage to the damaged assembly and to ensure further availability of the machine plant.

23. The device as claimed in claim 22, wherein, if further possibilities for an emergency operating mode are present, the central processor unit displays such possibilities to the user for selection, so that the user can select an emergency operating mode in accordance with the alternative which suits him best.

24. The device as claimed in claim 19, wherein the machine plant is one of a drive train, a drive train component and a steering system.

25. The device as claimed in claim 24, wherein, when damage to the transmission is diagnosed in the emergency operating mode, a gear speed corresponding to such damage is jumped over, or the power or speed is reduced.

26. The device as claimed in claim 24, wherein, when a defect is diagnosed in the retarder as a drive train component in the emergency operating mode, the retarder is switched off, and the brake system assumes its function.

27. The device as claimed in claim 24, wherein, when a defect is diagnosed in the brake as a drive train component in the emergency operating mode, the function of the brake is taken over by the retarder.

28. The device as claimed in claim 19, wherein a wavelet analysis device is used to detect a damaged assembly.

29. A method for early detection and prediction of damage to assemblies in a machine plant, said method comprising:

sensing structure-borne sound from the machine plant, and issuing of a measuring signal;

converting the measuring signal into a digital measuring signal;

transforming the digital measuring signal into the frequency domain, using a fast-Fourier transformation;

generating resonance data relating to individual shock pulses in the time domain, by means of cepstrum analysis;

a digital signal processor comparing a present cepstrum with a reference cepstrum that is representative of a new machine plant and is selected in response to rotational speed information and load information, assigned to this operating state and read out of a storage device;

monitoring results of comparison of the present cepstrum and associated reference cepstrum, to detect instances in which limiting values are exceeded; and

informing the digital signal processor such upward transgression of the limiting values;

determining a damaged assembly or assembly component and its predicted remaining service life from the present cepstrum by means of an empirical value matrix; and

issuing a diagnostic signaling, in which information relating to damaged assemblies and their predicted remaining service lives is contained, to a central processor unit for further processing.

30. The method as claimed in claim 29, wherein, when predicted remaining service life of a damaged assembly or assembly component is determined, stored information relating to history of the machine plant is also taken into account.

31. The method as claimed in claim 29, further comprising at least one of:

displaying information contained in the diagnostic signal relating to damaged assemblies and their predicted remaining service life or a user; and

transmitting said information by telemetry to a corresponding workshop or a machine plant operator.

32. The method as claimed in claim 29, further comprising:

implementing an emergency operating mode in response to the diagnostic signal for the assemblies which are diagnosed as damaged, to prevent or reduce further damage to the assembly which is diagnosed as damaged, and to ensure further availability of the machine plant.

33. The method as claimed in claim 32, further comprising:

if a plurality of possibilities are present for an emergency operating mode, said plurality selection are displayed for a user, so that the user can select a most desired an emergency operating mode.

34. The method as claimed in claim 32, wherein, if the damaged machine plant is a drive train, a gear speed corresponding to damage to the gearbox is jumped over, or the engine power or engine speed is reduced, as an emergency operating mode when such damage is diagnosed.

35. The method as claimed in claim 32, wherein, if the machine system is a drive train, the retarder is switched off and the brake system also assumes its function as an emergency operating mode if a defect is diagnosed in the retarder.

36. The method as claimed in claim 32, wherein, if the machine system is a drive train, the function of the brake is also assumed by the retarder in the emergency operating mode if a defect is diagnosed in the brake as drive train component.