Method and device for the diagnosis of defects in components of chassis systems of motor vehicles

A method of diagnosis of a defect in a component of a motor vehicle chassis system, the method comprising the steps of:

• filtering vibrations, that are produced by at least one rotating component (1) due to an imbalance (4), with a band pass filter of either a first order or a higher order to filter out a frequency range which depends on a speed of rotation of the rotating component and which contains the imbalance-induced vibrations of the rotating component, and the frequency range which depends on a speed of rotation of the rotating component including either frequency of the rotational speed or a harmonic of the rotational speed of the rotating component;
• receiving and storing signals, via an evaluation device, over a specified measurement duration the signals being transmitted from at least one sensor (8) that is arranged on a wheel carrier side and is associated with the component (3) to be diagnosed and from at least one sensor (9) that is arranged on a vehicle body side and is associated with the component (3) to be diagnosed, the sensors (8, 9) transmitting values for at least one measurable physical movement parameter, such that in the evaluation device (7), amplitudes of the sensor signals are sorted by increasing frequency and mechanical impedance of the transmission chain, i.e. resistance that opposes propagation of the vibrations, is determined;
• comparing the determined mechanical impedance of the component (3) to be diagnosed with a known impedance of the component (3) to be diagnosed when the component (3) to be diagnosed is in an undamaged condition;
• and
• if a deviation of the impedance determined for the component (3) to be diagnosed from the known impedance thereof in the undamaged condition exceeds a specified threshold value, then
• recognizing a defect of the component (3) to be diagnosed,
• emitting a fault code, and
• generating a fault-flag.

A device for diagnosis of a defect in a component of motor vehicle chassis system, the device comprising:

• an evaluation device (7) having either an internal storage means or being connected to an external storage means,
• at least one sensor (8) associated with at least one component (3) to be diagnosed and arranged on a wheel carrier side,
• at least one sensor (9) associated at least with the component (3) to be diagnosed and arranged on a vehicle body side such that the at least one sensor (8) on the wheel carrier side and the at least one sensor on the vehicle body side produce input signals for the evaluation device (7), and
• an output signal from at least one wheel rotational speed sensor (6) also being sent to the evaluation device (7) so that in the evaluation device (7), vibrations produced by rotating components (1), owing to an imbalance (4), are filterable by a band pass filter of either a first order or a higher order such that a frequency range that depends on wheel rotational speed, which contains vibrations of the rotating components induced by imbalance, are filtered out,
• the frequency range that depends on the driving speed being determinable by the signals from the wheel rotational speed sensor (6) so that a middle of the filtered-out frequency range is determined by the frequency of the measured wheel rotational speed, and in the evaluation device (7), amplitudes of the sensor signals are sorted by increasing frequency and mechanical impedance of the transmission chain are determinable, the evaluation device (7) comparing the mechanical impedance determined for the component (3) to be diagnosed with a known impedance thereof when the component (3) to be diagnosed is in an undamaged condition, and if a deviation of the impedance determined for the component (3) from the known impedance thereof in the undamaged condition is recognized, the deviation exceeding a specified threshold value, a defect of the component (3) to be diagnosed is recognized and the evaluation device (7) emits a fault code and generates a fault-flag.

A method of diagnosis of a defect in rotating a component of a vehicle, the method comprising the steps of:

• measuring, during operation of the component, at least one first movement parameter of an element that drives the rotating component;
• measuring, at least one second movement parameter, either of the rotating component or of a component following the rotating component;
• and
• comparing the two movement parameters to determine the defect in the rotating component of the vehicle.