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

Abstract

A method for the diagnosis of defects in components of motor vehicle chassis systems. Vibrations produced by rotating components of the chassis system due to an imbalance are filtered such that the frequency range which depends on the wheel rotation speed and contains the imbalance-induced vibrations of the rotating components is filtered out. The signals from sensors associated with the component and arranged on the wheel carrier side and the vehicle body side, are received and stored. The amplitudes of these signals are sorted by increasing frequency and the mechanical impedance of the transmission chain is determined and compared with the known impedance of that component undamaged. If a deviation of the determined impedance for the component and the known impedance of the undamaged component is recognized, then the component is determined to have a defect and a flag is set.

1 - 13 . (canceled) 
     
     
         14 . 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. 
   
     
     
         15 . The method of diagnosis of the defect in the component of the motor vehicle chassis system according to  claim 14 , further comprising the step of additionally comparing, in the evaluation device ( 7 ), the impedance determined for the component ( 3 ) to be diagnosed with known impedances of the component ( 3 ) to be diagnosed, when the component has either known defects or damage, identifying a closest agreement with the known impedances, and assuming, from the closest agreement, that the component ( 3 ) to be diagnosed is in whichever condition is represented by the known impedance that most closely corresponds to the impedance determined, and if an agreement of the impedance determined with the impedance of the component ( 3 ) to be diagnosed when the component is in a damaged condition is recognized, then producing a further fault code which can be read out by a diagnosis unit ( 11 ), during an inspection of the motor vehicle, to obtain further information about the defect, whereby, depending on the type of defect, the further fault code can also initiate safety measures in the vehicle. 
     
     
         16 . The method of diagnosis of the defect in the component of the motor vehicle chassis system according to  claim 14 , further comprising the step of, as a result of the fault-flag in a display unit of the vehicle, requesting an inspection. 
     
     
         17 . The method of diagnosis of the defect in the component of the motor vehicle chassis system according to  claim 14 , further comprising the step of, as a result of the fault-flag in a display unit of the vehicle, requesting an inspection and producing one of a visual and an acoustic signal to alert a driver. 
     
     
         18 . The method of diagnosis of the defect in the component of the motor vehicle chassis system according to  claim 14 , further comprising the step of transmitting values for at least one of movement path, acceleration, speed, angle, rotation speed, turning rate, extension, thrust and torsion with the at least one sensor ( 8 ) arranged on the wheel carrier side and the at least one sensor ( 9 ) arranged on the vehicle body side deliver. 
     
     
         19 . The method of diagnosis of the defect in the component of the motor vehicle chassis system according to  claim 14 , further comprising the step of dynamically determining the specified measurement duration so that measurement ends when a specified frequency interval occurs. 
     
     
         20 . The method of diagnosis of the defect in the component of the motor vehicle chassis system according to  claim 14 , further comprising the step of either increasing or adjusting the imbalance of the rotating components ( 1 ) by an eccentric. 
     
     
         21 . 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.   
     
     
         22 . The device for diagnosis of the defect in the component of motor vehicle chassis system according to  claim 20 , wherein further known impedances of the component ( 3 ) to be diagnosed, which characterize either known defects or damage, are stored by the storage means of the evaluation device ( 7 ), and the impedance determined for the component ( 3 ) to be diagnosed is compared with the further known impedances of the component ( 3 ) to be diagnosed, when the component has either a defect or is damaged, whereby a closest agreement of the impedance is identified and the device assumes that the component ( 3 ) is in whichever condition is represented by the known impedance that most closely corresponds to the determined impedance. 
     
     
         23 . The device for diagnosis of the defect in the component of motor vehicle chassis system according to  claim 20 , wherein the device is either installed permanently and securely in a motor vehicle as an on-board diagnosis system, or the sensors ( 8 ,  9 ) and an eccentric for producing an adjustable imbalance ( 4 ) are either temporarily attachable to the corresponding components or are functionally connectable with the vehicle so that, in a latter case, the evaluation device ( 7 ) is designed as an external evaluation device ( 7 ) which is temporarily connectably to the vehicle in order to facilitate diagnosis during maintenance. 
     
     
         24 . 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.   
     
     
         25 . The method according to  claim 23 , further comprising the step of determining the imbalance of the rotating component by virtue of the comparison of the first and the second movement parameters which are at least one of rotation speed, torque, thrust and torsion. 
     
     
         26 . The method according to  claim 23 , further comprising the step of filtering a time variation of the at least one second movement parameter by a band pass filter whose transmission frequency band includes the frequency of the at least one first movement parameter. 
     
     
         27 . The method according to  claim 23 , further comprising the step of defining the at least one first movement parameter as a parameter that characterizes the movement of a wheel of the vehicle.