JP2001206024A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic radial tire effectively reducing road noise over a wide range from a low frequency area to a high frequency area without any deterioration in uniformity or riding comfortableness. SOLUTION: In the pneumatic tire constructed of a tread part, side wall part, and a bead part and provided with a carcass layer, in which a cord is arranged at about 90 deg. to the tire equator and folded back in a bead core, and a belt reinforcing layer arranged between the radial outside of the carcass layer and a tread rubber layer, a plurality of lines in which equally shaped projections are arranged in the tire circumference direction at fixed intervals are formed on the outside surface of a side wall part on at least one side, and using the projections in the line adjacent to a rim line as a reference, the phase of the projections in another line are shifted in arrangement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire having reduced road noise from a low frequency range to a high frequency range without deteriorating uniformity and riding comfort.

[0002]

2. Description of the Related Art When a vehicle such as an automobile travels on a relatively rough road surface, noise called road noise is generated in a vehicle cabin. This road noise is one of the noises related to the tire, and the tire is vibrated by the unevenness of the road surface,
This vibration travels along the propagation path of the rim, axle, body,
Eventually, noise will be generated in the passenger compartment.

In recent years, sensibilities have been valued, and reductions in in-vehicle noise such as road noise have been demanded as automobiles have become more sophisticated and quieter.

[0004] The tire vibration mode of interest here is a mode in which the shoulder portion and the maximum width portion generally serve as nodes of vibration, and the tread center portion, the buttress portion, and the upper portion of the bead serve as antinodes of vibration. There has been known a technique capable of reducing road noise by reducing the amplitude by increasing the weight of a certain portion.

For example, as a method of reducing road noise in a low frequency range of 80 Hz to 160 Hz, as shown in FIG. 9, a ridge (9) extending in the tread direction from the vicinity of the rim line on the outer surface of the side portion is provided in the tire circumferential direction. As a method of forming a plurality of wires at intervals (Japanese Patent Application Laid-Open No. 10-76816), and a method of reducing a road noise in a high frequency range of 250 Hz to 400 Hz, a side rubber is formed radially outward from the maximum width position of the side surface. Although a method of providing an annular convex portion formed of the same rubber (Japanese Patent Application Laid-Open No. 9-109621) has been proposed, it is impossible to simultaneously reduce road noise in both frequency ranges from a low frequency range to a high frequency range. It was difficult.

Further, in the above-described method, there is a problem that a difference in rigidity of a sidewall portion occurs between a portion having a ridge and a portion not having a ridge, and the vibration of the tire is increased, so that a decrease in uniformity and riding comfort cannot be avoided. Was.

As shown in FIG. 10, it is attempted to provide a notch (93) in the tire circumferential direction in the ridge (10) to improve the riding comfort, but in this case, the uniformity is inevitably deteriorated.

When an annular convex portion is provided in the circumferential direction of the tire, the convex portion serves as a node of vibration and a new vibration mode is formed in another portion, so that a sufficient road noise reduction effect cannot be obtained. It is not preferable because it leads to an increase in tire weight.

[0009]

SUMMARY OF THE INVENTION According to the present invention, by appropriately arranging a ridge on the outer surface of at least one side wall of a tire, uniformity and riding comfort are not deteriorated, and weight of the tire is increased. It is an object of the present invention to provide a pneumatic radial tire that suppresses road noise and effectively reduces road noise from a low frequency range to a high frequency range.

[0010]

The present invention provides a tread portion,
A carcass layer composed of a sidewall portion and a bead portion, arranged at an angle of about 90 ° to the tire equator and folded by a bead core, and a belt reinforcing layer disposed between a radial outside of the carcass layer and a tread rubber layer In the pneumatic radial tire provided with the above, on the outer surface of at least one side wall portion, a plurality of rows in which protrusions of the same shape are provided at regular intervals in the tire circumferential direction are formed, and further adjacent to the rim line A pneumatic radial tire characterized in that the phases of the ridges of the other rows are shifted with respect to the ridges of the other row.

As described above, by providing the ridge on the sidewall portion, the torsional rigidity can be increased without increasing the lateral rigidity of the tire, road noise in a low frequency range can be reduced, and the ridge is dispersed. This can prevent the ride quality from deteriorating.

The ridge end of each step is formed so as to overlap with the ridge end of any other row in the tire radial direction, and the amount of overlap is 60 mm or less. Can be maintained.

Further, in a row in which the shape of the ridge becomes an antinode of the tire vibration mode, a mass such as increasing the thickness of the ridge or extending in the circumferential direction is added to the ridge in other rows. By changing the weighting, the vibration mode can be changed, and road noise in a high frequency range can be reduced.

Further, in the overlap portion of the row adjacent to the ridge, a notch in the tire circumferential direction is provided between the ridges, so that the tire is easily bent in the radial direction, and the riding comfort is maintained.

The thickness of the ridge is in the range of 0.5 mm to 5.0 mm in thickness from the surface of the sidewall, and the total area of the rim of the ridge is 5% of the surface area of the sidewall.
If it is less than the lower limits of both values, the effect of reducing road noise will not be obtained, and if it exceeds the upper limit, the weight of the tire will increase, which is not desirable.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a half sectional view of a pneumatic radial tire showing one embodiment of the present invention. The tire (T) of the present invention comprises a tread portion (1), a sidewall portion (2), and a bead portion (3), and is arranged in a code at an angle of approximately 90 ° with respect to the tire equator, and is turned over by a bead core (4). This is a pneumatic radial tire having a general structure including (5) and a belt reinforcing layer (6) disposed between a radially outer side of the carcass layer and a tread rubber layer.

As shown in the tire half sectional view of FIG. 1, on the outer surface of the sidewall portion, ridges (71) (72) (73) extending in the tire radial direction from the vicinity of the rim line (8).
Are formed outside the tire from the sidewall surface reference plane (A) so as to radially divide the sidewall portion, and cuts (91) and (92) having a width of 1 mm or more are provided in the tire circumferential direction between the ridges. ing.

FIG. 2 is a side view of the side wall portion of the tire of the present invention in the area where the ridge is formed. In each row dividing the sidewall portion in the radial direction, ridges (71), (72), and (73) having the same shape are formed on the entire circumference of the sidewall portion at regular intervals in the tire circumferential direction. The ridges in the matching row are shifted in phase in the tire circumferential direction, and the overlap (81) (82) amount is set to 0.

By providing the ribs on the sidewall portions in the above-described configuration, the torsional rigidity can be increased without increasing the lateral rigidity of the tire, and road noise in a low frequency range of 80 Hz to 160 Hz can be effectively reduced. Can be reduced.

Further, by dispersing the ridges, there is no difference in rigidity of the side wall portion, the tire vibration can be suppressed, and the deterioration of uniformity and riding comfort can be prevented. Further, if the shapes of the ridges in the same row are different, the rigidity varies in the sidewall portion in the tire circumferential direction, and the uniformity and the riding comfort are reduced. Therefore, the ridges in the same row need to have the same shape. .

FIG. 3 shows the ridges (71) and (72) of each row.
(73) The phase is shifted stepwise with reference to the ridges (71) in the row adjacent to the rim line, and each ridge in the adjacent row is formed by overlapping (83) (84) at its end. Notches (91) and (92) having a width of 1 mm or more are provided between the ridges of the overlap portion. If the overlap amount exceeds 60 mm, the rigidity of the side wall portion locally increases in the overlap portion, which leads to deterioration of uniformity and riding comfort. Therefore, the overlap amount needs to be 60 mm or less.

As shown in FIG. 4, if there is no overlap of the ridges in the circumferential direction of the sidewall portion and there is a gap (C1), (C2) or (C3) in the tire radial direction between the ridges, The ridge must be formed at least partially in the circumferential direction of the sidewall (including the overlap amount 0 in FIG. 2) because the rigidity of the portion locally decreases and uniformity and riding comfort deteriorate. There is.

Further, if the ridges are continuously provided in the tire radial direction, the stiffness of the ridges increases and the riding comfort deteriorates. Therefore, by providing a notch having a width of 1 mm or more between the ridges, the tire is provided. Can easily bend, and can absorb vibrations at the time of riding over a protrusion and prevent deterioration of ride comfort. If the depth of cut is less than 1 mm, the amount of deflection of the tire is small, and a sufficient effect cannot be obtained.

As described above, it is not necessary to arrange the ridges in each row in a stepwise manner as described above, and the ridges in each row may be alternately or randomly arranged as shown in FIG. .
However, in this case as well, in order to prevent the uniformity or the ride quality from being deteriorated, it is necessary to provide at least one ridge in one row in the tire radial direction.

FIG. 6 shows a projection (7) of a buttress portion.
This is an example in which 7) is made longer than the ridges (75) and (76) of the other rows to increase the mass addition, and the weight is changed with respect to the ridges of the other rows. The vibration mode of the buttress part is changed by the increase, and 250 Hz
Road noise in a high frequency range of up to 400 Hz can also be reduced.

The above-mentioned increase / decrease in mass is caused not only by the length of the ridge, but also by
It is also possible to increase or decrease the row width or the thickness of the ridge, or a combination thereof. In general, the antinode position of the tire vibration mode is a buttress portion for tires having an aspect ratio of 50% or more,
% Or less, the maximum width position is set, but it can be appropriately set depending on the tire size, the reinforcing structure inside the tire, and the shape of the sidewall portion.

The shape of the ridge need not be rectangular, but may be a parallelogram type ridge (7) as shown in FIGS.
8) In addition to the elliptical ridges (79), rhombic shapes, triangular shapes, etc., deformations and combinations thereof, and design of the sidewall portions by making the ridge side surfaces beveled or rounded, etc. It can be applied to the above-mentioned increase and decrease of the mass while having it.

The rubber thickness of the ridge is in the range of 0.5 mm to 5.0 mm as a thickness from the sidewall surface reference plane (A). Is preferably in the range of 5% to 40%.

If the rubber thickness is less than 0.5 mm, it is necessary to increase the area of the ridge in order to secure mass, and the difference in rigidity in the circumferential direction of the side wall portion is small, and the effect of reducing road noise is exhibited. On the other hand, if it exceeds 5.0 mm, the road noise in the low frequency range tends to deteriorate, and the tire weight further increases, which is not preferable.

Further, the reason why the total area of the outer peripheral portions of the protrusions is formed in the range of 5% to 40% of the outer surface area of the sidewall portion is the same as the above.

Therefore, the present invention can be achieved by appropriately designing the thickness and the total outer area of the ridge in combination with the shape and arrangement of the ridge.

(Embodiment) Each of the ridges has a rubber thickness of 2
mm, the outer surface area was set to 30% of the side wall part area, and a comparative test was performed on a tire having ridges arranged on both side wall parts according to the following drawings.

In the test tire, the phases of the three rows of ridges as shown in FIG. 2 were shifted stepwise, and the overlap amount was set to 0. Among the three rows of ridges as shown in FIG. The length of the ridge (77) hitting the buttress portion is made longer than the other rows to give weight, and the overlap amount between the ridges is 10 mm.
Example 2 in which the overlapping portions (81, 82) are provided and the cuts (91, 92) having a width of 1 mm are provided between the ridges, and Comparative Example 1 and FIG. Comparative Example 2 in which the ridges as shown are united without being divided into rows, and Comparative Example 2 in which the ridges of Comparative Example 2 are separated into three rows as shown in FIG. Example 3, Comparative Example 4, in which there is no overlap between the ridges in each row and there is a gap (C1, C2, C3) of 5 mm between the ridges as shown in FIG. Comparative Example 5 having a width of over 65 mm, Comparative Example 6 having a ridge thickness of more than 5 mm and 6 mm, and a ridge outer surface area of 4% of the sidewall area.
With respect to Comparative Example 7, which is more than 0% and is 45%, a test was performed by the following method for uniformity (indicated as U / F in the table), riding comfort, and road noise (indicated as R / N in the table). Table 1 shows the results.

The test tires of the above Examples and Comparative Examples have the same internal structure such as a belt layer and a carcass layer and design specifications such as a tread groove pattern, and have a size of 215 / 65R.
15 radial tires.

The uniformity is JASO C 607
The radial force variation was measured according to -87. It is indicated by an index with Comparative Example 1 being 100, and the larger the value, the better.

The ride comfort and road noise are 20 domestically produced.
The same test tires were mounted on all the wheels of a 00cc minivan, and evaluations were made in actual vehicle tests. Ride comfort is the average of sensory evaluations by two drivers. The higher the value, the better.

The road noise was measured by two passengers on the driver's seat and the right side of the rear seat, and the vehicle was running at a constant speed of 60 Km / h according to the meter reading. The measurement was performed by measuring noise.
The higher the value, the better.

[0039]

[Table 1] As shown in Table 1, the first embodiment reduces the road noise in the low frequency region by the effect of shifting the phase of the ridge, and the second embodiment further reduces the vibration mode by the effect of weighting the ridge row of the buttress portion. And the road noise was reduced in both the low-frequency range and the high-frequency range, while maintaining uniformity and riding comfort.

In Comparative Examples 2, 3, 4 and 5, the low frequency road noise was reduced due to the effect of providing the ridges, but the high frequency road noise was not improved. The ride is getting worse. Further, in Comparative Examples 6 and 7, the thickness of the ridge is too large or the area is too large, so that the lateral rigidity is increased, and the low frequency band road noise is deteriorated.

[0041]

As described above, according to the pneumatic radial tire of the present invention, ridges of the same shape are provided on the outer surface of at least one side wall portion of the tire at regular intervals in the tire circumferential direction. Formed in multiple rows and shifted the phase from the ridges in the row adjacent to the rim line with the ridges in the other rows. Road noise can be effectively reduced over a range.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a tire showing one embodiment of the present invention.

FIG. 2 is a side view of a sidewall portion showing one embodiment of the present invention.

FIG. 3 is a half side view of a side wall portion showing another embodiment of the present invention.

FIG. 4 is a half side view of a sidewall portion when there is a gap between ridges in each row.

FIG. 5 is a half side view of a sidewall portion showing another embodiment of the present invention.

FIG. 6 Same as above.

FIG. 7 is a side view of a side wall showing a modified example of the ridge of the present invention.

FIG. 8 Same as above.

FIG. 9 is a side view of a sidewall portion of Comparative Example 2.

FIG. 10 is a half side view of a side wall portion of Comparative Example 3.

[Explanation of symbols]

 T: Pneumatic radial tire A: Sidewall surface reference plane C1, C2, C3: Gap between ridges in each row 2: Sidewall section 3: Bead section 8: Rim line 71, 72, 73 , 74 ... ridges 75, 76, 77 ... ridges 78, 79 with modified weights 81, 82, 83, 84 ... overlapping portions of ridges 91, 92 ... over Notch between ridges of wrap part 9, 10… ridge of comparative example 93… notch of ridge

Claims (6)

[Claims] 1. A carcass layer comprising a tread portion, a sidewall portion, and a bead portion, wherein cords are arranged at an angle of substantially 90 ° with respect to the tire equator, and the carcass layer is folded back by a bead core. In a pneumatic radial tire having a belt reinforcing layer disposed between the layers, at least one of the side walls has an outer surface provided with ridges of the same shape at regular intervals in the tire circumferential direction. A pneumatic radial tire in which a plurality of rows are formed, and the phases of the ridges in the other row are shifted with respect to the ridges in the row adjacent to the rim line. 2. The ridge end of each row is formed so as to overlap with the ridge end of any other row in the tire radial direction, and the overlap amount is 60 mm or less. The pneumatic radial tire according to claim 1. 3. The pneumatic radial according to claim 1, wherein weights are changed with respect to the ridges of the other rows in a row in which the shape of the ridges is the antinode of the tire vibration mode. tire. 4. The tire according to claim 1, wherein a notch in the tire circumferential direction is provided between each of the ridges in an overlap portion of an adjacent row of the ridges. Pneumatic radial tire. 5. The pneumatic device according to claim 1, wherein a rubber thickness of the ridge is in a range of 0.5 mm to 5.0 mm as measured from a side wall surface. Radial tire. 6. The pneumatic radial according to claim 1, wherein the total area of the projections of the projections ranges from 5% to 40% of the surface area of the sidewall portion. tire.