JP2989762B2 - How to correct tire imbalance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire imbalance correcting method capable of effectively reducing radial force variation (RFV) and suppressing vehicle vibration and the like.

[0002]

2. Description of the Related Art Since automobiles run at high speeds, the weight balance of a tire and rim assembly, which is called a so-called wheel balance, is a very important factor in dimensional accuracy such as the roundness of a tire and in steering stability. Becomes

Conventionally, in order to maintain the wheel balance, for example, as shown in FIG. 7, a tire and rim assembly a mounted on a horizontal tire axis i is rotated, and the lowest point is reached when the vehicle naturally stops. The weight of the unbalanced point K and the weight of the unbalanced point are measured, and a weight is attached to the position of the rim opposite to the point of importance K, thereby generating a moment opposing the point of importance. At least the static imbalance was fixed.

[0004]

However, such a conventional correction method cannot sufficiently suppress the dynamic imbalance at the time of tire rotation or the like, and in particular, the vehicle vibration such as an increase in the low-order component of RFV. And the like.

[0005] The causes of this are as follows: 1) The emphasis of the unbalance generally occurs on the tread portion of the tire. Therefore, when the weight against the imbalance is attached to the rim, the emphasis on the ground due to the rotation of the tire. 2) In the case of a radial tire or the like, whose manufacturing method is complicated, there are many cases where a plurality of imbalances are important.
It can be inferred that the conventional method of representing the imbalance with one emphasis cannot accurately capture the imbalance.

Accordingly, the present inventors have conducted research based on the above presumption. As a result, the following could be determined. That is, a plurality of axes on the tire equatorial plane intersecting with the tire axis are determined at equal angular intervals in the tire circumferential direction, and for each axis,
The shaft core rotatably supports the assembly horizontally; at this time, a weight such that the moment around the axis centered by the weight of the left half portion and the right half portion of the assembly balances, the tire equatorial plane on the inner surface of the tread portion. By mounting the tire at the upper position, it is possible to make the static weight balance more uniform over the entire circumference of the tire even when a plurality of unbalanced points exist on the tire. In addition, by reducing the weight W of the weight determined for each shaft core to 0.8 to 0.9 times M / L, which is a value in which the left and right moments are perfectly balanced, the residual force can be removed and dynamics can be eliminated. It has been found that the balance can be greatly improved.

That is, according to the first aspect of the present invention, a plurality of axes which intersect with the tire axis and pass on the tire equatorial plane are virtually provided at equal angular intervals, and a moment around each axis is provided. The determined weights are attached to the inner surface of the tread portion, and the weight of each weight is obtained by the equation (1). In particular, the generation of low-order RFV can be effectively reduced, and the above-mentioned problems can be solved. It is intended to provide a method for correcting unbalanced tires.

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention comprises at least two tires intersecting with the tire axis and passing on the tire equatorial plane, and the tire circumference. A virtual axis centered at an equal angle in the direction is defined as a rotation center, and the axis center is determined by the weight of one half of the tire, which is a virtual half of the tire on an axis plane including the axis center and orthogonal to the tire equatorial plane. While measuring the moment difference M = | M1-M2 | between the surrounding moment M1 and the moment M2 due to the weight of the other tire half, the difference between the moment M1 and the inner half of the tread portion in the tire half on the side where the moment becomes smaller is measured. In addition, a weight having a weight W satisfying the following expression (1) is attached to each axis at a position where the tire equatorial plane and the plane including the tire axis and perpendicular to the axis intersect. Thing You. W = C × M / L (1) C: coefficient (0.8 to 0.9); L: distance between shaft surface and weight;

As described above, in the present invention, two or more axes are set for a tire, and a moment difference M due to the weight of the right and left tire halves around the axis is measured. I have. Therefore, even when the tire tread has a plurality of emphasis points, by dividing the plurality of emphasis points into an emphasis on one half and an emphasis on the other half, the imbalance is adjusted around the axis. And the weight can be statically balanced by weight attachment. Moreover, since such weights are set for each of a plurality of shaft cores provided at equal angular intervals, the balancing can be performed uniformly over the entire circumference of the tire.

On the other hand, the weight W of each of the weights is expressed by the following equation (1).
Is set with the value. W = C × M / L (1)

That is, since the weight W of the weight is reduced to 0.8 to 0.9 times the weight M / L required to completely balance the left and right tire halves, the weight is reduced to the ground. In this case, the residual force generated in the process can be largely removed. as a result,
In combination with the weight arrangement based on the shaft center, the dynamic imbalance can be corrected more uniformly and accurately, and in particular, the lower order R
The occurrence of FV can be suppressed and vehicle vibration can be reduced.

It is considered that the residual force is suppressed as described below. That is, as shown in FIG. 5, when the tread portion has an unbalance emphasis K, the centrifugal force F acting on the emphasis causes the tire axis to have a vertical load fluctuation component expressed by the following equation (2) when the tire is idling. Lateral force variation (RFV) is generated. RFV = 2F × cos ωt (2)

However, in actuality, the centrifugal force F is canceled out by the reaction force from the road surface when the important point K comes into contact with the ground, and becomes zero, and accordingly, the RFV is exactly as shown in FIG. It is expressed as a sum with the wave curve f2, and this curve f2 causes the residual force.

When the rectangular wave curve f2 is numerically analyzed by, for example, a Fourier series, the amplitude of the nth-order component of the curve f2 is-(4F / nπ) × sin (nJ / 2R). Here, R is the tire radius and J represents the ground contact length. This means that the RFV in the grounded state changes (decreases) in the nth-order component as compared with the RFV in the idling state by T = −4 / nπ × sin (nJ / 2R) (3) Therefore, the weight for balancing is determined by the following equation.
It is presumed that the nth-order component of the RFV in the grounded state can be removed by setting the value to 2R)｝ times. Actually, for example, values of a tire for a normal passenger car (R = 0.3 m, J = 0.1) are added to the tire radius R and the contact length J.
5m), the change amount T of the RFV is −0.
158F (primary component), -0.153F (secondary component),
-0.145F (3rd order component), -0.134F (4th order component), -0.121F (5th order component), -0.106F
(6th order component), -0.089F (7th order component), -0.0
72F (8th order component), -0.055F (9th order component),-
0.038F (10th-order component). Therefore, by setting the weight weight coefficient C to 0.80 to 0.9 as in the present application, particularly the first to fourth-order low-order components of RFV become large. As a result, vehicle vibration is reduced.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. In this example, the measurement and correction of the unbalance of the tire itself is performed under the condition that the tire is incorporated in a completely balanced reference rim. Thereby, the shape of the tire can be kept constant and the measurement error can be reduced. However, the measurement or the like may be performed on the tire alone as required. FIG. 1 shows an assembly 1 of a tire 2 and a reference rim 3.
In the figure, a tire 2 has a pair of bead portions 5 supported by being seated on a reference rim 3, a sidewall portion 6 extending radially outward from each bead portion 5, and an outer end portion between the bead portions 5. And a tread portion 7 which follows the tread portion.

The reference rim 3 includes a pair of rim sheets 10 for receiving a bead bottom of the bead portion 5 and each rim sheet 10.
And a disk portion 1 extending inward in the tire radial direction from the well 11 and attached to the tire shaft.
2, each rim sheet 10 is provided with a rim flange 13 along the outer surface of the bead portion 5. By attaching a weight 15 on the inner surface of the tread portion 7, the imbalance of the assembly 1, that is, the tire 2, is corrected.

The method for correcting imbalance includes a step of setting at least two axes 16 virtually on the tire 2 and a step of measuring a moment difference M between left and right around each axis 16. And a weight mounting step of mounting a weight 15 having a weight W determined by the equation (1) at a position on the inner surface of the tread portion 7 in the tire half portion on the side where the moment is small.

As shown in FIG. 2, the axis setting step includes, as shown in FIG. 2, at least two pieces of the tire 2 crossing the tire axis I and passing on the tire equatorial plane CO.
This is a step of virtually setting the second and third three shaft cores 16A, 16B, and 16C at equal angles of 60 degrees in the tire circumferential direction. The first, second, and third shaft cores 16A, 16A
B and 16C are respectively arranged horizontally.

The moment measuring step is a step of measuring the moment of the tire 2 around the axis, in this example, the moment of the assembly 1 for each axis 16A, 16B, 16C. That is, for example, the first shaft core 16
As described on behalf of A, the assembly 1 includes a shaft core 16A.
And an axis plane 17A orthogonal to the tire equatorial plane CO is set, and the axis plane 17A virtually divides the assembly 1 into two assembly halves 1L and 1R. At this time, the shaft core 1 due to the weight of one assembly half portion 1L
6A moment M1 and the other assembly half 1R
Difference M = | M from the moment M2 due to the weight of
1-M2 | is compared and measured. Here, the reference rim 3
Are balanced, the moment difference M matches the moment difference between the tire halves 2L and 2R of the tire 2.

For example, as shown in FIG. 3, the moment difference M pivotally supports the assembly 1 about the axis 16A, and the assembly 1 is balanced around the axis 16A to be horizontal. It can be easily measured as a necessary correction moment consisting of the correction load f.

In addition, as shown in FIG. 1, the weight attaching step includes the assembly half portion, for example, the assembly portion 1 on the side of the moments M1 and M2 where the moment is smaller.
R, the step of attaching a weight 15 to the center of the inner surface of the tread portion 7 of the tire 2, wherein the weight 15
Is mounted at a position where a plane 19A including the tire axis I and perpendicular to the shaft surface 17A intersects the tire equatorial plane CO.

Here, the weight W of the weight 15 needs to satisfy the following equation (1), and C is 0.8 to 0.8.
0.9, M is the moment difference, L is the axial surface 1
The distance between 7A and the weight 15 is shown. W = C × M / L (1)

The value of M / L in the equation (1) is determined by applying the correction moment at a position separated by a distance L from the shaft surface 17A in order to balance the assembly 1 horizontally in the moment measuring step. The weight W coincides with the correction load f at the time, and the weight W can be easily derived.

Equation (1) indicates that the weight W of the weight 15 set for each axis is 0.8 to 0.9 of the correction load f.
Means equivalent to double. Therefore, the low-order component of RFV generated when the unbalance emphasis touches the ground can be greatly reduced by the weight 15, and in particular, vehicle vibration and the like can be suppressed.

[0025]

[Example 1] The emphasis of imbalance (3
0g) and an assembly of a tire of 205 / 65R15 having a tire size of 205/65 and a reference rim of rim size of 6JJ × 15, and when rotated at a peripheral speed of 120 km / h, the centrifugal force F acting on the important point and the important point grounds. The amount of change in the primary component of the RFV and the ratio of the amount of change to the centrifugal force F were measured, and the measurement results are shown in Table 1.

[0026]

[Table 1]

As shown in the table, a change amount of about 0.17 times the centrifugal force F occurs in the temporary component of the RFV at the time of contact with the ground, and therefore, 0.83 times the centrifugal force F acting on the important point. It turns out that it is necessary to use a considerable weight as a balancer.

[0028]

[Example 2] Tire size 2 without emphasis on imbalance
Using an assembly of a 05 / 65R15 tire and a reference rim having a rim size of 6JJ × 15, the value of the primary component of RFV when rotated at a peripheral speed of 120 km / h was measured. Also, an assembly having a plurality of unbalanced points inside the tread portion of the tire is used, and a conventional correction method, that is, a method represented by one weight, and a correction method of the present application, that is, a plurality of, for example, three shaft cores are used. The imbalance was corrected using a method of setting and attaching a weight satisfying the expression (1) for each axis. Then, the value of the primary component of the RFV when the corrected assembly was rotated at 120 km / h was measured, and the results are shown in Table 2.

[0029]

[Table 2]

As shown in the table, the tire with the imbalance corrected by the method of the present invention can correct the dynamic imbalance with high accuracy even when a plurality of unbalanced points exist on the tread portion. The primary component of RFV can be greatly reduced.

[0031]

Since the present invention is configured as described above,
RFV can be effectively reduced, and vehicle vibration and the like can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating an assembly of a tire and a rim used in the present invention.

FIG. 2 is a schematic perspective view of an assembly illustrating a shaft center setting step.

FIG. 3 is a schematic side view of the assembly illustrating a moment measuring step and a weight attaching step.

FIG. 4 is a schematic plan view of the assembly illustrating a moment measuring step and a weight attaching step.

FIG. 5 is a diagram for explaining a relationship between a centrifugal force acting on an important point and RFV.

FIG. 6 is a diagram showing a change in RFV.

FIG. 7 is a diagram illustrating a conventional balance correction method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Assembly 1L, 1R Assembly half part 2 Tire 3 Reference rim 15 Weight 16A, 16B, 16C, 16 Axis 17A, 17 Axis 19A, 19 Plane which makes a right angle I Tire axis CO Tire equatorial plane

Claims (1)

(57) [Claims] 1. A method for correcting imbalance of a tire around a tire axis, wherein at least two virtual axes intersecting with the tire axis and passing on the tire equatorial plane and separated by an equal angle in the tire circumferential direction. A moment M1 around the axis due to the weight of one of the tire halves and the other half of the tire due to the imaginary bisecting of the tire on the axis including the axis and orthogonal to the tire equatorial plane with the center as the rotation center. The difference between the moment M2 and the moment M2 due to the weight of the tire is measured. On the other hand, the tire equatorial plane and the tire axis are placed on the inner surface of the tread portion in the tire half on the side where the moment is small. At a position where a plane that includes and intersects a plane perpendicular to the axis plane,
A tire imbalance correcting method, wherein a weight having a weight W satisfying the following equation (1) is attached to each axis. W = C × M / L (1) C: coefficient (0.8 to 0.9); L: distance between shaft surface and weight;