# US 9,038,468 B2 · Apparatus and method for determining a damage state of a wheel bearing

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- Number: US 9,038,468 B2
- Document ID: US9038468B2
- Status: Granted
- Kind: B2
- Application number: 13/634,635
- Filed: 2011-02-10
- Published: 2013-01-10
- Granted: 2015-05-26
- Earliest claimed: 2010-03-26
- Assignees: Schaeffler Technologies AG & Co. KG
- Applicants: Jens Heim
- Inventors: Jens Heim
- Web page: https://patentgrep.com/patent/US9038468B2

## CPC

- G01M 13/04: Bearings
- G01M 13/045: Acoustic or vibration analysis
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

An apparatus and a method for determining a damage state of a wheel bearing (12), in which a wheel (15) with a tire (9) arranged on a rim (8) in such a manner that the wheel can be rotated on an axle, in a motor vehicle, in particular during maintenance work on the motor vehicle. In order to avoid the wheel bearing (12) being accessed unnecessarily, a sensor unit (1) which communicates with an evaluation unit and is removably fastened radially outside a screw circle (11) of the rim (8) is provided for the purpose of determining the damage state.

## Claims

### Claim 1

An apparatus for determining a state of damage of a wheel bearing, in which a wheel with a tire arranged on a rim is rotatably provided on an axle of a motor vehicle, the apparatus comprising: a sensor unit which communicates with an evaluation unit for determining a state of damage, said sensor unit is removably attached directly to the rim at an attachment point located radially outside a screw circle of the rim.

### Claim 2 (depends on 1)

The apparatus as claimed in claim 1, wherein the sensor unit is attached clamped between the tire and a rim flange of the rim.

### Claim 3 (depends on 1)

The apparatus as claimed in claim 1, wherein the sensor unit is attached in a reversibly materially joined fashion to a rim bed of the rim.

### Claim 4 (depends on 1)

The apparatus as claimed in claim 1, wherein the sensor unit contains an at least single-axis measuring acceleration sensor.

### Claim 5 (depends on 1)

A method for determining a state of damage of a wheel bearing using the apparatus corresponding to claim 1, the method comprising: during maintenance on a motor vehicle, attaching the sensor unit which communicates with an evaluation unit to the wheel, detecting composite signals (S) of the sensor unit which are dependent on a wheel speed (n) of the wheel and on solid-borne sound, on the rotating wheel, separating solid-borne sound signals of the wheel bearing from the composite signals (S), comparing the solid-borne sound signals with comparison data which are relevant for the state of damage, determining a state of damage which results from the comparison, and removing the sensor unit from the wheel again.

### Claim 6 (depends on 5)

The method as claimed in claim 5, wherein the solid-borne sound signals are acquired by filtering of the composite signals (S).

### Claim 7 (depends on 5)

The method as claimed in claim 5, wherein the solid-borne sound signals are acquired from elimination of a rotational-speed-dependent component.

### Claim 8 (depends on 7)

The method as claimed in claim 7, wherein the rotational-speed-dependent component is determined by using sensor signals of a rotational-speed-detection device which is fixedly arranged in the motor vehicle.

### Claim 9 (depends on 5)

The method as claimed in claim 5, wherein the relevant comparison data are matched to a geometric embodiment of the wheel bearing.

### Claim 10 (depends on 5)

The method as claimed in claim 5, wherein the wheel is at least roughly balanced after mounting of the sensor unit.