DE102017109647A1 - Method for detecting damage to a wheel bearing - Google Patents

Abstract

The invention relates to a method for monitoring a wheel bearing of a vehicle with the following steps:
Detecting at least one force (F _{X, Y, Z} ) at determinable time intervals and along a spatial direction,
wherein the at least one force acts on a wheel bearing,
wherein the at least one force is detected by at least one force detection sensor device,
- Determining a damage of the wheel bearing from the at least one detected force.
Further, the invention will be a computer program product storing executable code for the method.

Description

The invention relates to a method for monitoring a wheel bearing of a vehicle and to a computer program product which stores executable code for the method.

Prior art systems detect wear or damage to wheel bearings based on their speed signal. For this purpose, a frequency evaluation of the speed signal is performed and evaluated.

Such methods are for example from DE 10 2013 211 704 A1 and the DE 10 2011 088 746 A1 known.

The accuracy of determining damage to a wheel bearing can be improved.

It is therefore an object of the present invention to provide a method for monitoring a wheel bearing of a vehicle, which improves the accuracy of the determination of a damage of a wheel bearing and thus also increases the safety for vehicle occupants.

This object is achieved by the features of the independent claim. Further advantageous developments are the subject of the dependent claims.

In a first aspect of the present invention, a method according to the invention for monitoring a wheel bearing of a vehicle preferably comprises the following steps.

Advantageously, a step comprises detecting at least one force at determinable time intervals and along a spatial direction. In this way, the forces in different spatial directions can be detected.

Conveniently, the at least one force acts on a wheel bearing of a motor vehicle. Consequently, the forces acting on a wheel bearing, for example, while driving, can be detected.

It is also advantageous if the at least one force is detected by at least one sensor device for force detection. The at least one sensor device is therefore means for the purpose of detection. In other words, by means of the at least one sensor device, the at least one force acting on a wheel bearing can be detected.

A further step of the method preferably comprises determining a damage of the wheel bearing from the at least one detected force. In this step, therefore, the detected forces are evaluated and preferably inferred damage or just no damage or on the condition of the wheel bearing.

Preferably, the step of determining comprises a transmission, in particular continuous transmission, of the at least one detected force to an evaluation unit. In this way, the detected force values are fed to an evaluation.

Conveniently, the step of creating in the evaluation unit comprises evaluating the at least one detected force as a function of time and by means of a transformation from the time domain into an image area. Preferably, it is evaluated by means of a Fourier transformation. In this way, values determined in the time domain can be transformed into the frequency domain using a transformation, for example.

Furthermore, it is preferred that the step of creating, in particular in the step of evaluating, in the evaluation unit, calculating image area values, in particular frequency values, takes place after transformation of the at least one detected force. Thus, concrete values for frequencies can now be calculated. Of course, other frequency analyzes are conceivable.

In a further preferred step of the creation, a comparison of the calculated image area values, in particular frequency values, with reference values for the calculated image area values is undertaken. By means of this comparison, it is possible to conclude on a possible damage to a wheel bearing or on its condition.

Conveniently, the reference values are stored in a memory of the evaluation unit, wherein preferably each reference value characterizes damage to a wheel bearing.

Another preferred step of the method includes outputting a damage message when preferably the amount of one of the calculated image area values is equal to or greater than an associated reference value. Consequently, a reference value not only represents the type of damage, such as a bearing damage, but also characterizes a threshold as of when the calculated image area values or values are to be regarded as bearing damage, for example. Also, the output allows a detected damage of a wheel bearing to be forwarded to, for example, a control unit or to an output unit for indicating the damage.

Another preferred step of the method includes detecting the rotational speed of a motor vehicle wheel.

Conveniently, the rotational speed is detected by a rotational speed sensor, in particular by a rotational speed sensor of an antilock brake system unit.

Additionally or alternatively (and / or), it is possible that the rotational speed is detected by the at least one sensor device for force detection. This has the advantage that a separate speed sensor is not absolutely necessary and thus manufacturing costs can be saved.

Furthermore, it is favorable if the method comprises determining a damage or a state of a wheel bearing from the detected rotational speed and from the at least one detected force. Using this combination of sensed speed and detected force, it is possible to increase the accuracy of monitoring a wheel bearing.

Conveniently, the step of determining further in the evaluation unit comprises determining the determinable time intervals for detecting the at least one force.

Preferably, the determination of the time intervals depends on the rotational speed, and preferably the time intervals become shorter as the rotational speed increases. The determination of the determinable time intervals is thus dependent on the speed, whereby no unnecessary data sets are generated at low speeds of a vehicle tire or even in the state of a vehicle.

Conveniently, the step of determining comprises a transmission, in particular continuous transmission, of the detected rotational speed and / or of the at least one detected force to an evaluation unit. Thus, various data are available for determining the condition or damage to a wheel bearing.

Preferably, the step of determining, in the evaluation unit, comprises evaluating the detected rotational speed and / or evaluating the detected rotational speed from vibrations of the at least one detected force as a function of time and by means of a transformation, in particular a Fourier transformation. In this way, frequency characteristics such as the Fourier transform, such as data for detected forces such as data for detected forces, can be used to deduce characteristic frequencies for the speed of a vehicle wheel.

It is also advantageous if the step of determining in the evaluation unit comprises calculating image area values, in particular frequency values, after the transformation of the detected rotational speed has taken place. A transformation allows the values acquired in the time domain to be transferred into an image area, in particular in the case of a Fourier transformation in a frequency range.

Conveniently, the step of determining further comprises comparing the calculated image area values for the detected speed with reference values for the calculated image area values.

Preferably, the reference values are stored in a memory of the evaluation unit, wherein conveniently each reference value characterizes damage to a wheel bearing.

Consequently, a reference to the current state of a wheel bearing is possible by means of the comparison step. That is, it can be determined whether or not a wheel bearing has damage.

Conveniently, the step of determining also includes outputting a damage message of the wheel bearing, if preferably the amount of one of the calculated image area values corresponds to an associated reference value or is greater.

Furthermore, it is advantageous if the step of determining comprises a transmission, in particular continuous transmission, comprising at least one detected force to an evaluation unit. Thus, measurement data from, for example, a sensor to the evaluation, where they can be further processed.

Advantageously, the step of determining in the evaluation unit comprises evaluating the at least one detected force as a function of time, preferably by averaging over a determinable time interval. By evaluating as a function of time, the time profile of the at least one detected force can be analyzed. For example, to reduce the amount of data, it is possible to average over a determinable time interval.

It is also advantageous if the step of determining in the evaluation unit comprises calculating the difference between the at least one evaluated, detected force and a force reference value for the predetermined spatial direction, wherein preferably the force reference value represents a threshold, exceeding this characterizes a damaged wheel bearing.

Furthermore, it is advantageous if the step of determining an outputting the state of the wheel bearing or outputting a Confirmation message includes, if favorably, the determined difference is less than or equal to zero. In this way, for example, a warning message can be output to a user via a display device if the determined difference from the at least one evaluated, detected force to the force reference value is preferably zero or negative. That is, preferably, that the force reference value is exceeded as the upper limit, and the wheel bearing is damaged.

Furthermore, it is preferable that detecting at least one force comprises detecting three forces along three spatial directions oriented perpendicular to each other to form a coordinate system. Thus, forces in any spatial directions can be detected.

The forces preferably act on a wheel bearing of a motor vehicle during driving operation. As a consequence, the wheel bearing is controllable while driving or while driving.

It is also preferred if each force is detected by a separate sensor device. As a result, the measurement accuracy can be increased.

Furthermore, it can be provided that the sensor device is designed as a magnetic sensor for detecting the inverse magnetostriction, in particular on a bearing element of a wheel bearing, and / or as a strain gauge and / or as an inductive or capacitive measuring device. By means of the aforementioned sensor devices, a precise detection of forces is possible, whereby a method for monitoring a wheel bearing can be carried out with high accuracy.

Preferably, the method comprises outputting a damage message for a wheel bearing to a control unit of a vehicle. Thus, the state of a wheel bearing can be displayed or output, for example, on a display device of a vehicle.

Finally, to the first aspect of the present invention, it should be mentioned that the steps mentioned above can be combined with one another.

Thus, it is possible, for example, that damage to a wheel bearing or the state of a wheel bearing from at least one detected force and / or from the detected rotational speed of the vehicle tire can be determined.

A second aspect of the present invention includes a computer program product.

It is expressly understood that the features of the method as mentioned in the first aspect can be used individually or in combination with one another in the computer program product.

In other words, the features mentioned above under the first aspect of the invention relating to a method for monitoring a wheel bearing of a vehicle can also be combined here with further features in the second aspect of the invention.

Advantageously, the computer program product stores executable code for the method according to the above-described first aspect of the present invention.

The computer program product may be, for example, a memory, such as a USB memory, a CD and / or a hard disk.

Of course, it is also possible that the computer program product is formed as an information storage element, such as a ROM, within a vehicle.

Hereinafter, the inventive idea presented above is expressed in other words in addition.

This idea preferably relates - in simplified form - to a method for monitoring a wheel bearing of a vehicle by means of a wheel force measurement.

By, for example, the wheel force measurement by means of inverse magnetostriction, preferably the forces in all spatial directions as well as, conveniently, the rotational speed of a wheel bearing can be determined.

It is also possible to close the condition of a wheel bearing or to carry out a damage detection of a wheel bearing.

With the help of the measured quantities of forces acting on a vehicle tire, for example, a model can be fed with the help of which the wear of a wheel bearing or damage to a wheel bearing can be determined.

Furthermore, so-called missuse cases can preferably be detected and counted by the force measurement, which have a significant influence on the service life of a wheel bearing.

This can be done for example by means of a force measurement or when detecting three forces along three spatial directions, which are oriented perpendicular to each other to form a coordinate system. Thus, so-called missuse cases can be detected and counted.

In a missuse case, a force reference value is preferably exceeded, which favorably comprises a significant influence on the service life of a wheel bearing. A force reference value can for example be stored in a memory of an evaluation unit, wherein preferably each force reference value represents a threshold whose exceeding characterizes damage to a wheel bearing.

• 1 eine Schnittansicht auf ein Radlager;
• 2 einen stark schematisierten Ablauf des erfindungsgemäßen Verfahrens zur Überwachung eines Radlagers eines Fahrzeuges; und
• 3 einen stark schematisierten Teilaspekt des erfindungsgemäßen Verfahrens zur Überwachung einer Fahrwerkskomponente eines Fahrzeuges.

The invention will be explained in more detail with reference to an embodiment in conjunction with accompanying drawings. Here are shown schematically:

• 1 a sectional view of a wheel bearing;
• 2 a highly schematic sequence of the method according to the invention for monitoring a wheel bearing of a vehicle; and
• 3 a highly schematic partial aspect of the method according to the invention for monitoring a chassis component of a vehicle.

1 shows a sectional view of a wheel bearing 1 for carrying out the method according to the invention.

Consequently, using the wheel bearing 1 the inventive method for monitoring a wheel bearing of a vehicle can be performed.

Shown in more detail 1 a wheel bearing 1 with a magnetic sensor unit 2 as well as with a first bearing element 3 and a second bearing element 7 and interposed rolling elements.

Here is the first bearing element 3 around the axis of rotation A rotatable while the second bearing element 7 is formed stationary.

The magnetic sensor unit 2 has two magnetized elements 5 . 6 on the first bearing element 3 as well as one to the elements 5 . 6 spaced magnetic sensor 4 on, which can detect magnetic fields or their change.

2 shows a highly schematic sequence of the method according to the invention for monitoring a wheel bearing of a vehicle.

This method preferably uses a wheel bearing 1 , as in 1 shown.

A procedure will be briefly described below by way of example.

In a first step, initially three forces F _{X, Y, Z} detected along three spatial directions, which are oriented perpendicular to each other to form a coordinate system. Here are the forces F _{X, Y, Z} recorded in determinable or changeable time intervals.

The forces are the forces F _{X, Y, Z} pointing to the wheel bearing 1 to 1 while driving.

The forces of the sensor device 2 or from the magnetic sensor unit 2 detected.

The magnetic sensor unit 2 is with a magnetic sensor 4 for detecting the inverse magnetostriction on the first bearing element 5 of the wheel bearing 1 educated. Alternatively, it is also possible to use strain gauges and / or inductive or capacitive measuring elements.

This is followed by the state of the wheel bearing in a further step from the detected forces 1 determines or determines whether damage to the wheel bearing 1 is present. How this works in detail is described below.

So first are the detected forces F _{X, Y, Z} to an evaluation unit R transmitted continuously.

In the evaluation unit R then become the detected forces F _{X, Y, Z} as a function of time and using a Fourier transform from the time into an image area or in a frequency range transferred and evaluated.

In other words, image area values or frequency values are calculated by transformation or frequency analysis.

Subsequently, the calculated frequency values are compared with reference values for the calculated image range values or frequency values.

The reference values are in a memory of the evaluation unit R deposited, with each reference value damaging the wheel bearing 1 characterized.

The rotational speed of the wheel bearing is parallel or simultaneously or also subsequently for determining damage from detected forces 1 detected.

The speed will be D of the wheel bearing 1 from the sensor device 2 detected for force detection.

Alternatively, it is also possible that the speed D is detected by a speed sensor, in particular a speed sensor of an anti-lock brake system unit.

So it will be the detected forces F _{X, Y, Z} and the detected speed D to the evaluation unit R transmitted continuously.

In the evaluation unit R becomes the detected speed D from vibrations of the detected forces F _{X, Y, Z} as a function of time and evaluated by means of a Fourier transformation.

Also in the evaluation unit R be the aforementioned determinable time intervals for detecting the forces F _{X, Y, Z} determined, wherein the determinable time intervals of the speed D are dependent, and wherein the time intervals become shorter with increasing speed.

Following this, after the transformation, the detected speed D Frequency values are calculated and then compared for the detected speed with reference values for the calculated frequency values.

Again, the reference values are in a memory of the evaluation unit R deposited, with each reference value damaging the wheel bearing 1 characterized.

In a final step then a damage message to a control unit P of a vehicle when the magnitude of one of the calculated frequency values for the speed and / or the detected forces is equal to or greater than an associated reference value.

Because the reference value not only represents the type of damage, such as a bearing damage, but also characterizes a threshold from when the calculated or the calculated frequency values are to be regarded as bearing damage.

3 shows a highly schematic partial aspect of the method according to the invention for monitoring a chassis component of a vehicle.

So first, the procedure as above too 1 and 2 described, expire.

Furthermore, it is possible in addition to that by means of the force measurement or by the detection of three forces F _{X, Y, Z} Along three spatial directions that are oriented perpendicular to each other to form a coordinate system, so-called missuse cases are detected and counted.

In a missuse case, a force reference value X is exceeded, which has a significant influence on the life of the wheel bearing 1 Has.

In such a case, as in 3 shown exceeds a detected force on the wheel bearing 1 the force reference value X. This fact is sent to the control unit P which archives these missuse cases for later reading out.

The individual steps of the method presented above can be stored as executable code for a computer program product, for example in the form of a USB memory or a CD-ROM or a ROM.

LIST OF REFERENCE NUMBERS

1

Wheel bearings

2

Magnetic sensor unit

3

first bearing element

4

magnetic sensor

5

magnetized element

6

magnetized element

7

second bearing element

A

axis of rotation

D

rotation speed

F _{X, Y, Z}

Force / forces

R

evaluation

P

control unit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102013211704 A1 [0003]
• DE 102011088746 A1 [0003]

Claims (4)

Method for monitoring a wheel bearing of a vehicle, comprising the following steps: detecting at least one force (F _{X, Y, Z} ) at determinable time intervals and along a spatial direction, the at least one force acting on a wheel bearing, the at least one force of at least one Sensor device is detected for force detection, - Determining damage to the wheel bearing from the at least one detected force. Method according to Claim 1 in which the step of determining comprises the following method steps: transmission, in particular continuous transmission, of the at least one detected force to an evaluation unit (R), in the evaluation unit, evaluation of the at least one detected force as a function of time and by means of a transformation from time in an image area, in particular by means of a Fourier transformation, in the evaluation unit, calculating image area values, in particular frequency values, after transformation of the at least one detected force, comparison of the calculated image area values, in particular frequency values, with reference values for the calculated image area values, wherein the reference values are stored in a memory of the evaluation unit (R), each reference value characterizing damage to a wheel bearing, - issuing a damage message if the amount of one of the calculated image area Values associated with a reference rt is equal to or greater. Method according to Claim 1 or 2 , with the further steps: - detecting the rotational speed (D) of a motor vehicle wheel, wherein preferably the rotational speed (D) is detected by a rotational speed sensor, in particular a rotational speed sensor of an antilock brake system unit, and / or preferably the rotational speed (D) of the at least one sensor device is detected for force detection, - Determining a damage of a wheel bearing from the detected speed and from the at least one detected force. Method according to Claim 3 wherein the step of determining comprises the following method steps: transmitting, in particular continuously transmitting, the detected rotational speed (D) and / or the at least one detected force (F _{X, Y, Z} ) to an evaluation unit (R), - in the evaluation unit (R), evaluating the detected rotational speed (D) and / or evaluating the detected rotational speed (D) from oscillations of the at least one detected force (F _{X, Y, Z} ) as a function of time and by means of a transformation, in particular a Fourier transformation in the evaluation unit (R), calculation of image area values, in particular frequency values, after transformation of the detected rotational speed, comparison of the calculated image area values for the detected rotational speed with reference values for the calculated image area values, wherein the reference values are stored in a memory of the evaluation unit (R), each reference value characterizing damage to a wheel bearing, - issuing a damage tion message of the wheel bearing, if preferably the amount of one of the calculated image area values corresponds to an associated reference value or greater.

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