Sensor Unit for a Vehicle

• US 20160163131A1
• Filed: 06/11/2014
• Published: 06/09/2016
• Est. Priority Date: 06/20/2013
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Steinlechner, Siegbert, Scheuing, Jan, Schroeder, Christoph
• Granted Patent: US 9,911,250 B2
• Time in Patent Office: Days
• CPC Class Codes: B60C 9/00 Reinforcements or ply arrangement of pneumatic tyres inserts having reinforcing means B60C5/08; bead structure, e.g. turnup or overlap construction, B60C15/00
• CPC Class Codes: B60Q 9/00 Arrangement or adaptation of signal devices not provided for in one of main groups B60Q1/00 - B60Q7/00 , e.g. haptic signalling
• CPC Class Codes: G01M 17/013 Wheels
• CPC Class Codes: G07C 5/0808 Diagnosing performance data testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005

Abstract

The disclosure relates to a sensor arrangement for a vehicle having at least one rotation-speed detection apparatus, which continuously detects a state variable and outputs said state variable to an evaluation and control unit which receives and evaluates signals which are output by a rotation-speed detection apparatus, wherein the evaluation and control unit carries out a first evaluation process with the detected state variable and ascertains a rotation speed of at least one vehicle wheel, the rim of said vehicle wheel being fastened to a corresponding wheel hub by means of wheel fastening means. According to the disclosure, the evaluation and control unit carries out a second evaluation process and identifies and monitors, on the basis of the continuously detected state variable, mechanical play between the vehicle wheel and the corresponding wheel hub in order to detect detached wheel fastening means.

Claims

1. A sensor arrangement for a vehicle, the sensor arrangement comprising:

at least one evaluating and control unit; and

at least one rotational speed detecting device configured to (i) continuously detect at least one state variable and (ii) output to the at least one evaluating and control unit,

wherein the at least one evaluating and control unit is configured to (i) perform a first evaluating process using the detected at least one state variable, (ii) determine a rotational speed of at least one wheel of the vehicle, the at least one wheel having a wheel rim fastened to a corresponding wheel hub by way of wheel fastening means, (iii) perform a second evaluating process, and (iv) based upon the continuously detected at least one state variable, identify and monitor a mechanical play between the at least one wheel and the corresponding wheel hub so as to detect loosened wheel fastening means.

2. The sensor arrangement as claimed in claim 1 wherein:

the at least one rotational speed detecting device comprises an encoder disc having a predetermined number of encoding regions and an allocated sensor, each encoding region being configured to generate in the allocated sensor a measuring pulse of the detected at least one state variable having an individual pulse duration; and

the at least one evaluating and control unit is configured to, in the second evaluating process, determine the individual pulse duration for each encoding region.

3. The sensor arrangement as claimed in claim 2, wherein the at least one evaluating and control unit is configured to, in the second evaluating process, calculate a mean pulse duration over a wheel rotation as a quotient derived from a sum of the determined individual pulse durations of the encoding regions that are provided on the encoder disc and the predetermined number of the provided encoding regions.

4. The sensor arrangement as claimed in claim 3, wherein the at least one evaluating and control unit is configured to, in the second evaluating process, determine a periodic variation of the individual pulse durations over the wheel rotation.

5. The sensor arrangement as claimed in claim 4, wherein the at least one evaluating and control unit is configured to, in the second evaluating process, perform a transformation of the periodic variation into a frequency domain using at least one of filtering and Fourier transformation.

6. The sensor arrangement as claimed in claim 4, wherein the at least one evaluating and control unit is configured to determine amplitudes of spectral lines of a frequency spectrum of the periodic variation of the individual pulse duration, a frequency of said spectral lines corresponding to an integer multiple of a wheel rotational speed multiplied by a number of wheel fastening means.

7. The sensor arrangement as claimed in claim 6, wherein the evaluating and control unit is configured to (i) compare the determined amplitudes of the spectral lines with predetermined threshold values and (ii) identify loosened wheel fastening means in response to the determined amplitudes at least one of equaling and exceeding the predetermined threshold values.

8. The sensor arrangement as claimed in claim 4, wherein the evaluating and control unit is configured to (i) determine a slippage angle of slippage that occurs in load changing situations between the at least one wheel and the corresponding wheel hub as a short term sum based on a difference between an instantaneous wheel rotational speed and a mean wheel rotational speed, the instantaneous wheel rotational speed being calculated from the individual pulse duration, the mean wheel rotational speed being calculated from at least one of the mean pulse duration and the short term sum by way of the periodic variation and (ii) evaluate said slippage angle so as to identify the mechanical play between the at least one vehicle wheel and the corresponding wheel hub.

9. The sensor arrangement as claimed in claim 8, wherein the at least one evaluating and control unit is configured to identify loosened wheel fastening means of the at least one wheel in response to the value of the determined slippage angle is at least one of equal to a predetermined threshold value and within a predetermined tolerance range around the predetermined threshold value.

10. The sensor arrangement as claimed in claim 1, wherein the rotational speed detecting device is embodied as at least one of a magnetic rotational speed detecting device and an optical rotational speed detecting device.

11. The sensor arrangement as claimed in claim 1, wherein the at least one evaluating and control unit is configured to indicate loosened wheel fastening means using at least one of an optical warning signal and an acoustic warning signal.