METHODS AND SYSTEMS FOR WHEEL BALANCER MATCHING AND FLAT SPOT CORRECTION

• US 20080282799A1
• Filed: 05/12/2008
• Published: 11/20/2008
• Est. Priority Date: 05/17/2007
• Status: Active Grant

• Current Assignee: Hunter Engineering Company
• Original Assignee: Hunter Engineering Company
• Inventors: Douglas, Michael Wayne, Scribner, David Merrill, Clasquin, Joel Allen
• Granted Patent: US 7,881,879 B2
• Time in Patent Office: Days
• US Class Current: 73/460
• CPC Class Codes: G01M 1/16 by oscillating or rotating the body to be tested

Abstract

Methods and systems for a computer implemented method of analyzing a vehicle wheel assembly including a tire and a rim is provided. The method includes removably mounting a wheel assembly on a shaft having a longitudinal axis and being rotatable about the longitudinal axis to rotate the wheel assembly, applying a substantially radial force to the wheel assembly during rotation thereof, and measuring variations in the radial force from at least one of radial runout, tire uniformity, and tire flatspotting. The method also includes determining a condition of the wheel assembly based on a spectral density analysis of the measured variations.

Claims

1. A computer implemented method of analyzing a vehicle wheel assembly including a tire and a rim, said method comprising:

removably mounting a wheel assembly on a shaft having a longitudinal axis and being rotatable about the longitudinal axis to rotate the wheel assembly;

applying a substantially radial force to the wheel assembly during rotation thereof;

measuring variations in the radial force from at least one of radial runout, tire uniformity, and tire flatspotting; and

determining a condition of the wheel assembly based on a plurality of radial harmonics of the measured variations.

2. A method in accordance with claim 1 wherein determining a condition of the wheel assembly comprises utilizing a spectral density analysis of the plurality of radial harmonics of the measured variations.

3. A method in accordance with claim 1 further comprising:

measuring vibrations resulting from imbalance in the wheel assembly; and

determining a condition of the wheel assembly based on a spectral density analysis of the measured vibrations.

4. A method in accordance with claim 1 further comprising outputting a value of the measured vibrations, the value determined using spectral density analysis.

5. A method in accordance with claim 1 further comprising controlling the radial force applied to the wheel assembly during rotation using a load roller.

6. A method in accordance with claim 1 further comprising controlling an inflation pressure of the wheel assembly.

7. A method in accordance with claim 1 further comprising indicating to a user a relative rotational mounting position of the tire with respect to the wheel rim to minimize the radial force variation using spectral density analysis.

8. A method of matching a tire to a wheel rim, the method comprising:

mounting a wheel assembly on a spindle, the wheel assembly comprising the tire mounted on the bare wheel;

determining a plurality of radial force variation harmonics of the wheel assembly;

analyzing the plurality of radial force variation harmonics; and

based on the analysis outputting a relative rotational mounting position of the tire with respect to the wheel rim.

11. A method in accordance with claim 8 wherein determining radial force variation of the wheel assembly comprises applying a radial force to the tire using a load roller.

12. A method in accordance with claim 8 wherein the wheel rim is a bare wheel rim prior to mounting the tire thereon, said method further comprising:

mounting the bare wheel rim on a spindle of a wheel balancer;

determining the run-out of the bare wheel rim;

13. A method in accordance with claim 8 wherein determining radial force variation of the wheel assembly comprises determining a run out of the wheel rim using a non-contact method.

9. A method of matching a tire to a wheel rim of a wheel, the method comprising:

mounting a wheel assembly on a spindle;

determining radial force variation of the wheel assembly;

analyzing the radial force variation using spectral density analysis; and

outputting a relative rotational mounting position of the tire with respect to the wheel rim utilizing said spectral density analysis.

10. A method in accordance with claim 9 further comprising:

repeating the steps of claim 9 with at least one additional wheel and wheel assembly;

calculating a spectral density analysis value that would result from the mounting of each tested tire on each tested wheel rim;

matching the tested tires with the tested wheel rims utilizing said spectral density analysis value.

14. A wheel balancer comprising:

a shaft adapted for receiving a wheel assembly, said shaft having a longitudinal axis and being rotatable about said axis so as to rotate the wheel assembly removably mounted thereon;

a sensor assembly for measuring rotation of the shaft about said longitudinal axis;

a vibration sensor assembly for measuring vibration of the wheel assembly as the wheel assembly is rotated;

a motor operatively connected to the shaft for rotating said shaft about said longitudinal axis, thereby to rotate the wheel assembly;

a load roller for applying a generally radial force to the wheel assembly;

a sensor for measuring a variation of the radial force during rotation of said wheel assembly; and

a control circuit configured to determine flatspotting of the tire utilizing at least one of the measured vibration of the wheel assembly and the measured radial force variation.

15. A wheel balancer in accordance with claim 14 wherein said control circuit is configured to determine a flat spot based on a signature of the measured radial force variation.

16. A wheel balancer in accordance with claim 14 wherein said control circuit is configured to determine a flat spot based on a signature of a spectral density analysis of the measured radial force variation.

17. A wheel balancer in accordance with claim 14 wherein said control circuit is configured to determine at least one of a temporary flat spot and a permanent flat spot.

18. A wheel balancer in accordance with claim 14 configured to spin the wheel assembly with a load applied by the load roller to facilitate at least one of reducing the flat spot and eliminating the flat spot.

19. A wheel balancer in accordance with claim 14 further configured to output an indication of flatspotting and information relating to the location and magnitude of the flat spot to a user.

20. A wheel balancer in accordance with claim 14 wherein said control circuit is configured to determine what a condition of the tire would be without the flat spot.

21. A wheel balancer comprising:

a shaft adapted for receiving a wheel assembly, said shaft having a longitudinal axis and being rotatable about said axis so as to rotate the wheel assembly removably mounted thereon;

a sensor assembly for measuring rotation of the shaft about said longitudinal axis;

a vibration sensor assembly for measuring vibration of the wheel assembly as the wheel assembly is rotated;

a motor operatively connected to the shaft for rotating said shaft about said longitudinal axis, thereby to rotate the wheel assembly;

at least one of a non-contact sensor configured to measure a radial runout of the wheel assembly and a contact sensor configured to track an outer peripheral surface of the wheel assembly with insufficient force to deform the outer peripheral surface; and

a control circuit configured to determine flatspotting of the tire utilizing at least one of the measured vibration of the wheel assembly and the measured radial runout.