METHOD AND DEVICE FOR CHECKING THE WHEEL SUSPENSION OF A VEHICLE

Abstract

A device for checking the wheel suspension of a vehicle, in particular, of a motor vehicle, includes: a device for determining the wheel normals and/or the center of rotation of a wheel of the vehicle; a device for determining the movement trajectory of the wheel normals and/or of the center of rotation of the wheel during a movement of the vehicle; and a comparison and evaluation device, which is configured to compare the determined movement trajectory of the wheel normals and/or of the center of rotation of the wheel to a predefined movement trajectory, and to output a defect message when the deviation of the determined movement trajectory from the predefined movement trajectory exceeds a predefined limiting value.

Claims

1-10. (canceled)

11. A method for checking the wheel suspension of a vehicle, comprising: (A) determining at least one of wheel normals and a center of rotation of at least one wheel of the vehicle; (B) moving the vehicle and determining points of a movement trajectory of at least one of the wheel normals and the center of rotation of at least one wheel, during the movement of the vehicle; (C) determining a deviation of the movement trajectory of at least one of the wheel normals and the center of rotation acquired in step (B) from a predefined movement trajectory; and (D) outputting a defect message, when the deviation exceeds a predefined limiting value.

12. The method as recited in claim 11, wherein the vehicle is a motor vehicle.

13. The method as recited in claim 11, wherein the method includes, in step (B), pushing the vehicle by muscle power or mechanically.

14. The method as recited in claim 11, wherein the method includes, in step (B), moving the vehicle by the power of an engine of the vehicle.

15. The method as recited in claim 11, wherein the method includes mounting at least one measuring target to at least one wheel of the vehicle and optically monitoring the measuring target to determine at least one of the wheel normals and the center of rotation, and the movement trajectory of the at least one of the wheel normals and the center of rotation.

16. The method as recited in claim 11, wherein the method includes constructing a circle, which is, on average, a shortest possible distance from determined points of the movement trajectory.

17. The method as recited in claim 16, wherein the method includes determining at least one of: i) a sum of distances of the points of the movement trajectory from at least one of the circle, and ii) a number of points of the movement trajectory which are more than a predefined distance from the circle, and outputting a defect message, if at least one of the sum and the number of points exceeds a predefined limiting value.

18. The method as recited in claim 17, wherein the method includes: determining a fitting curve, which runs through all points of the movement trajectory; ascertaining the curvature of the fitting curve and comparing it to the curvature of the circle; and outputting a defect message when the difference between the curvature of the fitting curve and the curvature of the circle exceeds the predefined limiting value.

19. The method as recited in claim 11, wherein the method includes inferring a type of defect of the wheel suspension from at least one of: a type and a degree of the deviation of the movement trajectory of at least one of the wheel normals and the center of rotation determined in step (B) from a predefined movement trajectory.

20. A device for checking the wheel suspension of a vehicle, comprising: (a) a device which is configured to determine at least one of wheel normals and a center of rotation of a wheel of the vehicle; (b) a device which is configured to determine a movement trajectory of the at least one of the wheel normals and the center of rotation of the wheel, during a movement of the vehicle; and (c) a comparison and evaluation device which is configured to compare the determined movement trajectory of the at least one of the wheel normals and the center of rotation of the wheel to a predefined movement trajectory, and to output a defect message when the deviation of the determined movement trajectory from the predefined movement trajectory exceeds a predefined limiting value.

21. The device as recited in claim 20, wherein the vehicle is a motor vehicle.

22. The device as recited in claim 20, wherein at least one of: i) the device for determining the at least one of the wheel normals and the center of rotation of a wheel of the vehicle, and ii) the device for determining the movement trajectory of the at least one of the wheel normals and the center of rotation of the wheel, are configured to optically detect at least one of the wheel and a measuring target mounted to the wheel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 shows a schematic view of an exemplary embodiment of a device of the present invention for checking the wheel suspension of a vehicle.

[0032] FIG. 2 shows a schematic view of a wheel equipped with a measuring target.

[0033] FIG. 3 shows a projection of the movement locus of the wheel normals with respect to an ideal circle, in the case of an intact wheel suspension.

[0034] FIG. 4 shows a projection of the movement locus of the wheel normals with respect to an ideal circle, in the case of a defective wheel suspension.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0035] FIG. 1 shows a schematic view of an exemplary embodiment of a device 1 of the present invention for checking the wheel suspension of a vehicle 2.

[0036] Vehicle 2 includes four wheels 4a, 4b, 4c, 4d, in each instance, two at a front axle 6a and at a rear axle 6b of vehicle 2; each of the wheels 4a, 4b, 4c, 4d being attached to its respective axle 6a, 6b by a link 7 and a transverse control arm 8.

[0037] On the outside of vehicle 2, a measuring target 5 is mounted to each wheel 4a, 4b on the left side of vehicle 2, in direction of travel F, in such a manner, that it moves together with respective wheel 4a, 4b and, in particular, rotates together with wheel 4a, 4b.

[0038] A device 1 of the present invention includes an image recording device 10, which is configured to record images of a vehicle 2 that is moved past image recording device 10, in particular, images of wheels 4a, 4b of vehicle 2, that is, images of measuring targets 5 mounted to wheels 4a, 4b, and is configured to supply them to an image analyzing device 12. Image analyzing device 12 is configured to determine, from the images recorded by image recording device 10, the center of rotation Z of the wheel 4a, 4b of vehicle 2 rolling past image recording device 10, as well as the movement trajectory p(t) of center of rotation Z.

[0039] Device 1 of the present invention also includes a comparison and evaluation device 14, which is configured to compare the movement trajectory p(t) of center of rotation Z of a wheel 4a, 4b acquired by image recording device 12, to a predefined movement trajectory K, which may be a function of, in particular, the type of vehicle 2 and/or of wheel 4a, 4b, and, in this context, to quantitatively determine, in particular, a deviation between the movement trajectory p(t) actually recorded at vehicle 2 and predefined movement trajectory K, in order to control an output device 16, which is also part of a device 1 of the present invention, in such a manner, that it outputs a defect message, which may be, e.g., an optical and/or an acoustic defect message, if the deviation of acquired movement trajectory p(t) determined in this manner from predefined movement trajectory K exceeds a predefined limiting value.

[0040] Vehicle 2 may be pushed past image recording device 10 manually by at least one person, or driven past image recording device 10 by its own (engine) power. Also, a pushing apparatus not shown in FIG. 1 may be provided, which is configured to move vehicle 2 past image recording device 10. In this context, care must be taken that wheels 4a, 4b, 4c, 4d of vehicle 2 are loaded and roll on the ground or on guide tracks placed on the ground, which are not shown in FIG. 1.

[0041] FIG. 2 schematically shows the view of a wheel 4a of motor vehicle 2, as it is monitored by image recording device 10.

[0042] A measuring target 5 in the form of a measuring board is attached to the rim of wheel 4a in such a manner, that it rotates together with wheel 4a about a center of rotation Z.

[0043] Several measuring marks 15 are provided, which take the form of, in particular, reflecting measuring marks 15 (retroreflective markers) that allow image recording device 10 to measure the rolling movement of wheel 4a in an optimum manner.

[0044] FIG. 3 shows the projection of points of movement trajectory p(t) of the wheel normals and the optimum circular path K ideally expected for the case of an intact wheel suspension 7, 8.

[0045] FIG. 4 shows the projection of points of movement trajectory p(t) of the wheel normals with respect to the circular path K ideally expected for the case of a defective transverse control arm 7.

[0046] In FIGS. 3 and 4, it is readily apparent that the points of movement trajectory p(t) of the wheel normals in the case of a defective transverse control arm 7 (FIG. 4) have, on average, a markedly greater deviation from ideal circular path K than in the case of an intact transverse control arm (FIG. 3).

[0047] By quantitatively determining the average deviation of the points of movement trajectory p(t) from predefined, ideal circular path K, a measure of the deviation may be determined, which may be compared to a limiting value predefined for the specific type of vehicle, in order to detect damage to the wheel suspension.

[0048] In order to be able to determine the deviation quantitatively, the method may include determining the sum of the distances of the points of movement trajectory p(t) from (ideal) circular path K and outputting a defect message, if the sum of the deviations of all points exceeds a predefined limiting value.

[0049] Alternatively, or in addition, the number of points p(t), which are more than a predefined distance from circle K, may be determined, in order to output a defect message when the number of these points exceeds a predefined limiting value.

[0050] The method may also include determining a fitting curve, which runs through all points of the cycloid, ascertaining the curvature of the fitting curve and comparing it to the curvature of circle K, in order to output a defect message when the difference between the curvature of the fitting curve and the curvature of circle K exceeds a predefined limiting value.

[0051] In one expanded specific embodiment, the type of defect of wheel suspension 7, 8 may be inferred from the quantity and/or the quality of the deviation, and appropriate information and recommendations for further diagnostic and/or repair steps may be presented to the user.