Method and apparatus for optically scanning a vehicle wheel

• US 20020018218A1
• Filed: 07/19/2001
• Published: 02/14/2002
• Est. Priority Date: 07/19/2000
• Status: Active Grant

• Current Assignee: FLEXcon Company Incorporated, Snap-On Equipment Gmbh (Snap-On Incorporated)
• Original Assignee: Snap-On Equipment Gmbh (Snap-On Incorporated)
• Inventors: Brennan, John, Conheady, Paul, Lowe, Helen
• Granted Patent: US 6,535,281 B2
• Time in Patent Office: Days
• US Class Current: 356/602
• CPC Class Codes: G01M 1/32 by adding material to the body to be tested, e.g. by correcting-weights

Abstract

A method and an apparatus for scanning a vehicle wheel, wherein a location on the wheel is sensed by means of a light team emitted by a light source and is reflected to a position-sensitive receiver. The spacing of the sensed location relative to a reference location is measured from the directions of the emitted beam and the reflected beam. The light source and the position-sensitive receiver are synchronously pivoted about a common axis by means of a rotary drive including a stepping motor for successive measurement steps. A rotary angle sensor supplies signals proportional to the rotary position of the stepping motor to an evaluation system.

Claims

1. A method of optically scanning a vehicle wheel, wherein

a location is sensed on the wheel by means of a light beam emitted by a light source and reflected to a position-sensitive receiver,

the spacing of the sensed location relative to a reference location is measured from the directions of the emitted beam and the reflected beam, and

the emitted beam and the position-sensitive receiver are pivoted synchronously about a common axis in a measurement plane which intersects the rim surface of the wheel at an approximately right angle, for successive measurement steps.

2. A method as set forth in claim 1

wherein said angle is an obtuse angle.

3. A method as set forth in claim 1

wherein the successive measurement steps are carried out in a measurement plane which extends outside the axis of the wheel and parallel to the axis of the wheel.

4. A method as set forth in claim 1

wherein the axis of the wheel is arranged horizontally and the successive measurement steps are carried out in a measurement plane which extends below the axis of the wheel.

5. A method as set forth in claim 4

wherein the successive measurement steps are carried in a horizontally extending measurement plane.

6. A method as set forth in claim 1

wherein the emitted beam is further used to sense a radially extending region of the wheel disk portion.

7. A method as set forth in claim 6

wherein the emitted beam is further used for determining angular positions of base points of spokes extending radially from a central part of the wheel disk portion.

8. A method as set forth in claim 1

wherein when the wheel is rotating lateral displacement in the axial direction of the sensed locations of the wheel which are on a given radius are ascertained, and wherein the emitted beam is emitted at least during one revolution of the wheel in the direction corresponding to the given radius.

9. A method as set forth in claim 1

wherein in the scanning procedure firstly a location on the wheel which is closer to the axis of the wheel is sensed with the emitted beam and then the emitted beam is pivoted towards the periphery of the wheel.

10. A method as set forth in claim 1

wherein the spacing of the sensed location relative to the reference location is determined from the measurement signals of the positionsensitive receiver by means of one-dimensional triangulation and from the respective rotary angle position of the emitted beam and the beam reflected by the sensed location.

11. A method as set forth in claim 1

wherein after a wheel unbalance measurement procedure has been carried out the emitted beam is directed on to the balancing location on the wheel at which unbalance compensation is to be effected.

13. Apparatus as set forth in claim 12

wherein the measurement shaft is arranged horizontally, and further including means carrying the light source and the receiver pivotably in a plane beneath the measurement shaft.

14. Apparatus as set forth in claim 12

wherein the pivot axis extends perpendicularly to the axis of the measurement shaft.

15. Apparatus as set forth in claim 14

wherein the pivot axis is outside the measurement shaft axis.

16. Apparatus as set forth in claim 12

wherein the measurement shaft is supported on a frame by way of pivotably interconnected support plates of a force-measuring device, and

wherein the stepping motor is arranged between the support plates and the light source and the receiver is arrange beneath the support plates.

17. Apparatus as set forth in claim 12 including

means biasing the light source and the receiver towards a rest position.

12. Apparatus for optically scanning a vehicle wheel to be balanced, comprising

a measurement shaft,

mounting means for mounting the wheel to the shaft for rotation about a wheel axis,

a light source operable to direct an emitted light beam on to a location on the wheel,

a position-sensitive receiver operable to receive a beam reflected by the sensed location on the wheel,

a rotary drive including a stepping motor for synchronous pivotal movement of the light source and the receiver about a common pivot axis,

an electronic evaluation system operable to evaluate measurement values of the position-sensitive receiver for ascertaining the spacing of the location on the vehicle wheel which is sensed by the light source from a reference location, and

a rotary angle sensor operable to supply a signal proportional to the respective rotary angle position of the stepping motor to the evaluation system.