Method of correcting variations in radial force between a tire and the ground

• US 5,060,510 A
• Filed: 06/20/1990
• Issued: 10/29/1991
• Est. Priority Date: 06/30/1989
• Status: Expired due to Term

• Current Assignee: Compagnie Generale Des Etablissements Michelin
• Original Assignee: Michelin & CIE Compagnie Generale Des Etablissements Michelin
• Inventors: Rousseau, Jean-Baptiste
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/540,902
• Time in Patent Office: 496 Days
• Field of Search: 73/146, 152/539, 152/543
• US Class Current: 73/146
• CPC Class Codes: B29D 2030/0635 Measuring and calculating tyre uniformity, e.g. using mathematical methods
• CPC Class Codes: B29D 2030/0637 Correcting by adding material
• CPC Class Codes: G01M 1/326 the body being a vehicle wheel
• CPC Class Codes: G01M 17/024 combined with tyre surface correcting or marking means

Abstract

A method of correcting the variations of radial force between a tire and the ground, including measuring on a uniformity machine the variation in radial force of the tire/mounting-rim rolling assembly, reconstituting a radial variation on basis of the harmonic variations to be corrected, and effecting said correction by means of wedges in the form of circular rings placed between the mounting rim and the beads of the tire.

Claims

1. A method of correcting defects in uniformity of a tire mounted on a rim the rim flanges of which have a portion perpendicular to the axis of rotation, which includes rolling the tire mounted , inflated and under load on the drum of a uniformity machine, graphically recording the variation in radial force of the rolling assembly consisting of tire and rim, and removing the tire from its rim, characterized by the fact that:

the variation in radial force (F_R) is broken down into its harmonics of the 1st to 16th order;

the variations in the harmonics are checked with respect to control limits which are not to be exceeded;

a variation of radial force (F_Rn) which takes into account the harmonic of the highest order which it is necessary to correct and all harmonics of lower order is recomposed;

the amplitude of the variation (F_Rn) thus obtained is determined as well as the circumferential positions of the optimums (maximum F_M and minimum F_m) of this variation (F_Rn); and

by placing, between the vertical walls (23) of the rim flanges (20) and the corresponding walls of the beads (12) on each side of the tire (1), a compensation wedge (30) in the form of a circular ring, the outside radius (R₁) of which is at least equal to the radius (R_T) of the point of tangency (T) between the upper rounded portion (24) and the vertical wall (23) of the flange of the rim (20), the inner radius (R₂) of which is at most equal to the radius (R_S) of the point of tangency (S) between the vertical wall (23) and the lower rounded portion (22) of the flange of the rim and the thickness (e) of which is constant radially over the height (H), and variable circumferentially between a maximum value (e_M) at the level of the maximum value (F_M) of the variation in radial force (F_Rn) and substantially proportional to the amplitude (A) of the variation (F_Rn) and a minimum value (e_m) of 0.3 mm at the level of the minimum value (F_m) of the variation (F_Rn), the value of the thickness (e) between these two extremes (e_M) and (e_m) for the point of the wedge (30) corresponding to the value (F) of the radial force measured being such that the quantity e-0.3 in mm is proportional to the quantity F-F_m, the compensation wedge being made of a plastic or elastomeric simple or composite material of a density of at most 1.2.

2. A method according to claim 1, characterized by the fact that the compensation wedge (30) has a thickness (e) which decreases from a maximum value (e_M) at the level of the maximum value (F_M) of the first harmonic (F_R1) of the variation in radial force (F_R) to a minimum value (e_m) of 0.3 mm at the level of the minimum value (F_m) and increases from said minimum value to the maximum value (e_M), the variation of (e) as a function of the circumferential position being a sine function.

3. A method according to either of claims 1 and 2, characterized by the use of wedges (30) of a height (h) greater than the height (H) of the vertical wall (23) of the flange of the rim (20) and of quasi-trapezoidal cross-section, the bases of said section being parallel to the vertical wall (23) and the other two sides of said section forming an angle (α

) of between 40° and

50°

with said bases.

4. A method according to either of claims 1 and 2, characterized by the use of compensation wedges (30) of a height (h) greater than the height (H) of the vertical wall (23) of the flange of the rim (20) and of parallelogram-shaped cross-section, the inner development of the wedge (30) being slightly less than the quantity 2π

R_J, R_J being the nominal radius of the rim.

6. A method according to claims 1 or 2, characterized by the fact that the compensation wedges (30) are of plastic material and placed and maintained, either on the rim (20) or on the bead (12) of the tire (1) by simple adhesion by means of adhesive paper.

7. A method according to claims 1 or 2, characterized by the fact that the compensation wedges (30) are of filled elastomeric material and are applied on the beads (12) of the tire (1) by means of a connecting rubber and dissolution layers, the bead-wedge assembly undergoing localized partial vulcanization by the application of heat.

5. A method of correcting defects in uniformity of a tire mounted on a rim, the seats of which form an angle of 15°

±

1°

with the axis of rotation of the tire, including measuring the amplitude and the circumferential positions of the optimums of the variation in radial force of the first harmonic by rolling on a uniformity machine, characterized by the fact that after measurements and demounting of the tire, there is placed between the seats (21) of the rim (20) and the seats of beads (12) of the tire (1) on each side of the tire (1), a compensation wedge (30) having a cross section in the shape of a parallelogram, the width (1_c) of which is at least equal to 80% of the width (1) of the bead (12), the thickness (e) of which, measured perpendicular to the seats (21) of the rim (20), is constant over a cross section but variable circumferentially between a value (e_M) which is maximum at the level of the minimum value (F_m) of the radial force F_R1) and a minimum value (e_m) of 0.3 mm at the level of the maximum value (F_M), the value (e_M) being proportional to the amplitude (A₁) of the variation (F_R1), the value of the thickness (e) at a point of the wedge corresponding to the radial force (F) being such that e-0.3 mm is proportional to F-F_m, the compensation wedge being made of a plastic or elastomeric simple or composite material of a density of at most 1.2.

8. A method of making an annular compensation wedge ring for correcting the defects in the uniformity of a tire by being placed between vertical portions of the mounting rim and the beads of the tire comprising the steps of determining the variation in radial force of the inflated tire under load over a complete revolution and forming the annular compensation wedge ring of a plastic or elastomeric material having a density of at most 1.2 and a thickness which is at least 0.3 mm, the wedge being of constant thickness radially over its height and of variable thickness circumferentially, the circumferential variation in thickness varying from a minimum thickness value at the location of minimum radial force to a maximum thickness at the location of maximum radial force, the variation in thickness having the same direction as the variation in radial force.

9. A method as set forth in claim 8 in which the variation in radial force is determined for different orders or harmonics and including the steps of recomposing variation in the radial force for the range of harmonics determined and varying the circumferential thickness of the annular compensation wedge ring on the basis of the recomposed variation in radial force.

10. A method of making an annular compensation wedge ring for correcting defects in uniformity of a tire by being placed between the beads of a tire and the seats of a rim which form an angle of 15°

±

1°

with the axis of rotation of the tire comprising determining the amplitude and the circumferential positions of the optimums of the variation in radial force of the first harmonic of the inflated tire under load over a complete revolution and forming the annular compensation wedge ring of plastic or elastomeric material having a density of at most 1.2 and a thickness which is at least 0.3 mm, the thickness of the wedge ring, measured perpendicular to the seat of the rim, being constant axially over its length but variable circumferentially between a maximum value at the location of the minimum value of the radial force and a minimum value at the location of the maximum value of the radial force, the variation in thickness varying inversely as the variation in radial force between minimum and maximum.