JPH0281708A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To obtain a pneumatic tire with sufficient rigidity distribution by making reinforcing elements for strips less in the ratio of amplitude to the wave length of the corrugation at one side of both side edges as compared with the ratio in the center area of a belt. CONSTITUTION:Corrugated strips B1, B2 making plural numbers of cord or filament arranged in corrugation all together around a toroidal carcass 2 as reinforcing elements and coated with high polymer material lower in its elastic modulus are used as a belt 3 contributing to strengthen a crown. Rigidity of a tread can be made greater at side edges of the belt 3 as compared with that in the center part by making reinforcing elements for strips B1, B2 less in a ratio a/lambda of amplitude a to wave length lambda of the corrugation at least on one side of both side edges as compared with that of the center area of the belt 3, and it is possible therewith to suppress tread side edge protrusion generated in the case of high speed revolution under charging the tire in its inner pressure namely expansion in tire diameter effectively.

Description

[Detailed Description of the Invention] (Industrial Application Field) With regard to reinforcing the crown of the carcass of pneumatic tires, especially pneumatic tires that run at ultra-high speeds, so-called so-called problems that tend to occur at the shoulders of the tread during high-speed running The following describes the development results that have focused on improving the durability of the belt, which contributes to crown reinforcement, while appropriately avoiding the deterioration of ground contact due to protrusion and standing waves.

Pneumatic tires for use in some passenger cars that are suitable for running at ultra-high speeds suffer from problems such as poor ground contact and the formation of standing waves due to the protrusion of both tread shoulders during high-speed running.

In addition, in heavy-duty radial tires, generally called wide base tires, which have a relatively small tire flatness, both shoulders tend to protrude from the center of the tread due to internal pressure filling, resulting in poor ground contact and the need to strengthen the crown of the carcass. Distortion occurs at the ends of the belt in the width direction, which can lead to malfunctions.

(Prior Art) Attempts have been made to change the relationship between each part of the reinforcing member, that is, the belt and the breaker, depending on the central part and both shoulder parts of the tread.

Here, reinforcing cords made of conventionally widely used organic fiber yarns and metal wires, particularly steel wires, are arranged in parallel to each other, and the rubberized cord cloth coated with rubber is cut diagonally. When reinforcing with a so-called cross belt consisting of multiple layers of diagonal members stacked in a direction that intersects each other across the equatorial plane, the reinforcing cord is continuous from one shoulder to the other. In order to change the rigidity at the center and both sides of the belt, methods such as dividing the reinforcing layer and changing the cord angle of each cord, or adding additional reinforcing layers on both sides of the belt have been used.

However, these methods have disadvantages in manufacturing, such as the labor involved in dividing and adding the reinforcing layer, the increase in the number of parts, which reduces productivity, and the disadvantages of creating a step in rigidity at the position of division and addition. There are problems in terms of the durability of the belt or breaker, such as separation failure easily occurring from this position due to an increase in the stress concentration source of the belt.
In addition, the rigidity of the reinforcing layer is changed at the center of the crown and both shoulders by adding a reinforcing layer with reinforcing cords arranged along the equator only on both sides of the belt. There are problems in that the number and weight of tires increase and productivity decreases.

(Problems to be Solved by the Invention) The problems of the prior art as described above have been fundamentally solved, and the tread can be strengthened by a completely new carcass crown reinforcement means that has the necessary and sufficient rigidity distribution without increasing the number of members. It is an object of the present invention to provide a pneumatic tire that is useful for reinforcement.

(Means for Solving the Problems) The present invention has a toroidal carcass moored by at least a pair of bead cores, and a plurality of cords are aligned in a wavy or zigzag shape around the toroidal carcass. Alternatively, a pneumatic tire having a reinforcing filament as a reinforcing element and a corrugated strip coated with a polymeric material having a lower modulus of elasticity as a belt for reinforcing the crown of the toroidal carcass; The reinforcement element has a ratio (a)/(λ) of the amplitude (a) to the wavelength (λ) of its waveform or zigzag shape.
In this pneumatic tire, at least one of both side edges of the belt is made smaller than the central region of the belt.

wherein the value of the amplitude to wavelength ratio (a)/(λ) gradually decreases toward the side edges of the belt, and the belt has at least one wavy or jagged strip;
the orientation of the reinforcing elements is substantially parallel to the equatorial plane of the tire; occupy at least 2
A strip-shaped laminated reinforcing body having a laminated structure in which nodule regions are formed that intersect with the reinforcing elements of the book, and the reinforcing elements of wavy or jagged strips are oriented in the same direction. It is even more preferable to do so.

In either case, there are sometimes multiple pairs of bead cores for mooring the toroidal carcass, and the present invention can be applied to any of them. The plies may be suitably selected to provide body reinforcement to suit the intended use, such as various organic fiber cords or metal (or steel wire) cords.

It is important that the rough round reinforcing means for this toroidal carcass, that is, the strip generally embedded inside the tread rubber as a belt, satisfies the above-mentioned constitution of the present invention, and the main part thereof is shown in FIG.

In the figure, 1 indicates tread rubber, 2 indicates a toroidal carcass, and 3 indicates a belt as a means for reinforcing the crown of the carcass 2.
This belt 3 is marked with the order number from the carcass 2 side B
It consists of two corrugated or jagged strips, distinguished by .

The reinforcing elements of the belt 3 can also be suitably selected from various organic fiber cords or metal, particularly steel wire cords.

(Function) For strips whose reinforcing elements are a plurality of cords or filaments occupying the layers of each strip BI+82 in a wave or zigzag shape, when the shape of the reinforcing elements is changed, the average axis of the reinforcing elements (i.e. For example, the angle between the reinforcing element and the average axis at the position where the reinforcing element intersects the center line of the reinforcing element (which bisects the distance between the maximum and minimum vertices of the waveform that are adjacent to each other and follows the direction of orientation). changes.

The larger the amplitude a or the shorter the wavelength λ of a wave-shaped or zigzag-shaped reinforcing element, the larger the angle becomes, and conversely, the smaller the amplitude a or the longer the wavelength λ, the smaller the angle becomes. Similar to the cord angle in a belt made of diagonal members made of multiple layers of diagonally cut cord rubberized cloth stacked in a direction in which the cords intersect with each other, the larger the angle of the reinforcing element with the average axis, the more the average axis The stiffness in the direction begins to decrease. In other words, the larger the ratio a/λ of the amplitude a to the wavelength λ, the lower the stiffness in the average axial direction.

In this way, the rigidity of the reinforcing member can be changed depending on the shape of the reinforcing element, which is wave-shaped or zigzag-shaped.

Therefore, by changing the shape of the reinforcing elements within the same strip, it is possible to change the stiffness distribution without adding any additional members. In comparison, it is useful in that it is possible to change the stiffness without increasing the terminal part of the reinforcing cord, and furthermore, by continuously changing the shape of the reinforcing element, the stiffness can be changed continuously. As a result, the rigidity difference is alleviated, and problems such as separation at the dividing position, which occur when dividing and arranging conventional diagonally cut cord rubberized cloth, are completely resolved, and the rigidity distribution is appropriate according to the required performance. In other words, we can obtain .

Here, when two layers of wavy or zigzag cords or filaments are stacked in a direction that crosses each other, as in a cross belt, the a/λ ratio is assumed to be the same across the width of the belt. For example, the amplitude a
If you try to make the rigidity and elastic modulus smaller by increasing the strip, the enveloping property of the strip and eventually the belt will improve and the worry of the cord breaking when running in turns will be reduced, but the rigidity of the strip will decrease too much and it will be difficult to control when running in turns. It is difficult to obtain sufficient performance, and care must be taken because if the a/λ ratio is made too small, there is an increased risk that the cord will break or separation will occur at the ends of the cord.

The stiffness of the tread is increased in the central region at the side edges of the belt by making the a/λ ratio of the reinforcing elements of the strip smaller in at least one of the side edges than in the central region of the belt. As a result, it is possible to effectively suppress the protrusion of the tread side edge, that is, the expansion of the tire diameter, which occurs when the tire rotates at high speed under internal pressure.

(Example) Figure 1 (a) and (b) show tire size 185/T.
A specific example of the present invention is illustrated for the case of OR13, in which a belt 3 consisting of two layers of rubberized strips using a single steel filament (0.5 mm diameter) as a reinforcing element is reinforced with the crown of a toroidal carcass 2. The figure shows a case in which the tread rubber is embedded inside the tread rubber 1. In this example, the toroidal carcass 2 has a radial structure using nylon cord (1890d/3) and is moored around a pair of bead cores (not shown).

In the figure, B indicates the strip of the belt 3, and the subscripts indicate the order of stacking from the one closest to the toroidal carcass 2.

Note that the state of intersection of reinforcing elements between adjacent strip layers is shown by broken lines for the reinforcing elements of the strip B1 immediately below the portion overlapping with the outermost strip B2.

In this example, the reinforcing element has a wave shape, and the amplitude at the center of the width of the belt 3 is 2 mm and the wavelength is 18 mm, that is, the ratio of the amplitude to the wavelength is a.
/λ-0,11, while at the ends of both shoulders of belt 3 a/λ=
The a/λ ratio is made to decrease continuously from the center of the width of the belt to both sides so that it becomes 0.06, and in this example, the rigidity along the circumference of the belt 3 is increased at both side edges.

Here, the amplitude a is 172 peak-to-peak, and it goes without saying that the wavelength is the pitch length of the wave.

As another example 2, the same as shown in FIG. 2 (for a passenger car size 185/70R13 tire, B2 of the belt 3 is a strip made of corrugated steel filament (0.5 mm φ) and is vibrated at the center of the crown. Width=2111In
, the wavelength is 18 mm, a/λ = 0.11, and the ratio of amplitude and wavelength is continuously changed from the center to both shoulders so that a/λ = 0.06 at the strip axial ends of both shoulders. Placed small. On the other hand, B is a strip in which filaments inclined at an angle of 45° with respect to the tire equatorial plane are arranged parallel to each other. Further, as Example 3, an evaluation was also performed on the belts B1 and B2 of Example 2 in which B2 was the belt layer closest to the carcass. For comparison with these, as shown in Fig. 3, a strip of size 185/70R13 is provided with strips B I' + BZ"' made of IX5 steel cord layers intersecting each other at an angle of 18" to the equator as a crossing belt 3'. A comparative example of a tire and a comparative example of the same size, which is equipped with two intersecting belts (angle 15°) and a reinforcing layer B in which nylon cords are arranged substantially parallel to the equator, as shown in Figure 4. 2 was prepared and a comparative test was conducted together with Example 1.2.

The test compared speed and weight. Furthermore, the weight increases the cost and causes a worsening of rolling resistance.

In the high-speed test, the drum was run on the drum under conditions of normal internal pressure and normal load, and the speed at which standing waves were generated was measured.

In addition, in Examples 1 and 2, the adjacent strip B1°82
Alternatively, within the strip Bz for the strip B+, the waveforms are changed at the center and both shoulders of the belt 3, but depending on the required rigidity distribution, only one of the adjacent reinforcing layers is placed at the center and both shoulders. You can also arrange the waveforms in different sections.

Furthermore, Figure 5 is an example of a flat heavy load radial tire of size 11/70 R22.5, with belt ply, Bl
"+82' consists of diagonal cord layers arranged at an angle of 45° with respect to the equatorial plane, and strips B, r8
4' has an amplitude of 2.0 mm at the center of belt 3, a wavelength of 18 mm, and an a/λ ratio of 0.11, and strips B and l have an a/λ ratio of 0.04 at the belt ends, and strip B4
is 0.06.

(Effects of the Invention) According to the present invention, the rigidity at the tread side edge corresponding to the side edge of the belt is advantageously realized without the need for any additional members, so that the high-speed performance of the pneumatic tire is improved by reducing the tire weight. The improvement is advantageously achieved without requiring any increase and without compromising durability.

[Brief explanation of the drawing]

Figures 1 and 2 are a developed view of the belt and a cross-sectional view of the main parts of the tire for the example, Figures 3 and 4 are similar developed views and a cross-sectional view of the comparative example, and Figure 5 is a separate view. FIG. 3 is a similar exploded view and cross-sectional view of the embodiment. 1... Tread rubber 2... Toroidal carcass 3... Belt patent applicant Brideston Co., Ltd. Figure 3 (a) <b) 2 Toy F Autumn h-h Figure 4 (a) ib ) 2 Troy F゛addition h-6s Figure 5 (a) (b

Claims (1)

[Claims] 1. It has a toroidal carcass moored by at least a pair of bead cores, and around this toroidal carcass is reinforced a plurality of cords or filaments aligned in a wave or zigzag pattern. A pneumatic tire having at least one corrugated strip coated with a polymeric material having a lower modulus of elasticity as an element and as a belt for reinforcing the crown of the toroidal carcass; The reinforcement element has a ratio (a) of the amplitude (a) to the wavelength (λ) of its waveform or zigzag
)/(λ) is smaller at at least one of both side edges than in the central region of the belt. 2. The pneumatic tire according to claim 1, wherein the value of the ratio of amplitude to wavelength (a)/(λ) gradually decreases toward the side edges of the belt. 3. Claim 1, characterized in that the belt has at least one wavy or jagged strip, and the orientation of the reinforcing elements is substantially parallel to the equatorial plane of the tire.
Or a pneumatic tire described in 2. 4. The belt cross-overlaps at least two undulating or zigzag strips with at least two reinforcing elements, each reinforcing element of each strip occupying a layer of adjacent wavy or zigzag strips. Claim 1 or 2 characterized in that the reinforcing body is made of a band-shaped laminated reinforcing body having a laminated structure in which nodular regions are formed and reinforcing elements of wavy or zigzag strips are aligned in the same direction. Pneumatic tires listed in.