JPH01106707A - Pneumatic bias tire for heavy load - Google Patents

Abstract

PURPOSE:To reduce the occurrence of tire failure, and to improve durability in the title tire to be used at a mining site or the like by discontinuously arranging a plurality of reinforcement layers between ply layers and between bead cores in a specified range. CONSTITUTION:A first reinforcement layer 31 and a second reinforcement layer 32 are discontinuously arranged between ply layers 25p and between bead cores 22 to reinforce carcass layers 25. And the first reinforcement layer 31 is arranged in the region ranging from the side part 25b of a second ply layer bundle 25B to a bead part 25a and between a sixth ply 25p6 and a seventh ply 25p7, and is made up of inner and outer reinforcement layers 31a, 31b. Further, the second reinforcement layer 32 is arranged in the region ranging from the side part 25b of a third ply layer bundle 25c to the bead part 25a and between a ninth ply 25p9 of a third ply layer bundle 25c and a tenth ply 25p10. By this constitution, the occurrence of tire failure can be reduced, so that the durability can be improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a pneumatic bias tire for heavy loads, for example,
The present invention relates to a pneumatic bias tire for use in mining and construction sites where sharp rocks, ores, felled stumps, etc. are scattered, and particularly for construction vehicles where large, high-horsepower vehicles run under heavy loads.

(Prior Art and its Problems) As a conventional pneumatic bias tire for heavy loads, there is one shown in FIG. 9, for example.

In FIG. 9, l is a pneumatic bias tire for heavy loads, and pneumatic bias tires 1 for heavy loads are 2
Consisting of a pair of first bead core 2A and second bead core 211, and a rubber-coated organic fiber cord (hereinafter simply referred to as cord) 3, each bead core 2A, 2. In between, from the bead part 5a to the side part 5b and the shoulder part 5c, respectively.
The carcass 5 is comprised of a first ply layer bundle 5A, a second ply layer bundle 511, and a third ply layer bundle 5c, which are arranged in a toroidal shape extending over the crown part 5d. The first and second ply layer bundles 5A and 58 have bead cores 2^, 2. The third ply layer bundle 5c ends and is fixed at the bottom of one bead core 2a, 2m. The carcass 5 has a plurality of ply layers 5 in which cords 3 are arranged in parallel at predetermined intervals, that is, at a predetermined number of strokes.
The cords 3 are arranged in a direction crossing the circumferential direction of the tire, the cords are arranged so as to cross each other between adjacent ply layers, and are wound and fixed around a bead core. A cylindrical tread 7 is provided outside the crown portion 5d of the carcass 5 in the tire circumferential direction and covers the carcass 5. Further, a side wall 8 is provided outside the bead portion 5 a s side portion 5 b and shoulder portion 5 C of the carcass 5 to cover the carcass 5 . carcass 5
A breaker 9 is provided between the tire and the tread 7 to reduce impact from the outside of the tire.

However, when such heavy-duty pneumatic bias tires are used at mining and construction sites, they tend to be damaged by cuts caused by rocks and stumps scattered at the site, and their resistance to this (hereinafter referred to as cut resistance) In addition, resistance to bursting due to cant and impact (hereinafter referred to as burst resistance) is required as a usage property.

Furthermore, in recent years, as vehicles have become larger and have higher horsepower, pneumatic bias tires for heavy loads have been installed on such vehicles. As the various forces to be applied (e.g. traction force) become larger, the deformation of the tire increases and the fatigue burden increases on the carcass from the side section to the bead section, especially the carcass at the bead section. Cord breakage due to cord fatigue, so-called CB
U (cord breaking up) failures (hereinafter referred to as CBU failures) are more likely to occur. In other words, resistance to C
The BU property was insufficient, and the bead section was the weakest point of carcass fatigue.

In order to solve these demands and weaknesses, the following methods have been used in the past.

There is one in which the entire carcass is reinforced by increasing the number of cords in the ply layer or by increasing the number of plies in the carcass to continuously strengthen the spaces between the bead cores. However, in these products, in order to alleviate the strain around the cords and prevent the glabellar peeling failure of the ply layer (hereinafter referred to as separation thin failure), the residual void ratio between the cords in the same ply must exceed a certain limit. Therefore, there is a limit to the increase in the number of strokes. In addition, when the number of plies in the carcass is increased, the thickness of the carcass becomes excessive, which increases the internal heat generation of the carcass, especially in the crown area, which reduces the adhesive strength between the cord and rubber and increases the thermal fatigue of the cord, resulting in separation failure. and CBU failure is likely to occur. In addition, since the tensile strain of the cord that occurs when filling the internal pressure decreases, the compressive strain of the cord increases when a load is applied, which increases the mechanical fatigue of the cord, especially in the bead carcass, making CBU failure more likely. There is.

Furthermore, increasing the number of plies in unnecessary parts and increasing the number of cords impedes economic efficiency. In other words, even though it is a pneumatic tire for construction vehicles, the characteristics required for the tire differ depending on its use. For example, cut resistance and burst resistance are the most important for tires for dump trunks, which are used for transportation only on rough terrain. In contrast, tires for wheel loaders, which are vehicles used for loading work, suffer from bead formation during long periods of loading work on relatively good roads or during excavation work that causes large deformation of the tire. Since the carcass of the CBU is likely to cause CBU failure,
Reinforcement of these areas is of utmost importance. Therefore, it is only necessary to cover the weakest point according to the characteristics required by the use of the tire, and there is no need to increase the strength of the entire carcass.

Furthermore, as proposed in Japanese Patent Publication No. 56-26561, there is a carcass carcass in which a reinforcing ply layer is inserted from the side part to the bead part to increase the rigidity of the carcass. However, this reinforcing ply layer is located between the ply layer bundles, such as the first ply layer bundle 5 in FIG. Since the reinforcing ply layer is interposed between the five reinforcing ply layer bundles, the strain generated near the end of the reinforcing ply layer increases, leading to separation failure and CBU failure.

Therefore, the present invention provides a discontinuous reinforcing ply layer (hereinafter referred to as reinforcing layer) between specific ply layers of the carcass and between the bead cores.
By providing a pneumatic bias tire for heavy loads, the carcass is effectively, economically, and purposefully reinforced to suit the usage conditions of the tire, eliminating the occurrence of tire failure and improving durability. The purpose is to

(Means for Solving the Problem) In order to effectively, economically, and purposefully arrange a reinforcing layer on the carcass that is suitable for the usage conditions of the tire, the present inventors carried out observation tests on a large number of failed tires, Heat generation tests, tire deformation behavior tests, etc. were conducted.

As a result, the following findings were obtained and the present invention was achieved.

In FIG. 3, 11 is a conventional tire used in the test, and the same components as in FIG. 9 are given the same reference numerals. Tire 1
1 crown part 11d1 shoulder part 11c, side part 1
1b and bead portion 11a constitute corresponding portions of carcass 5 including crown portion 5d to bead portion 5a, respectively.

First, the bead portion 11a and the side portion 11 of the tire 11.
Let us explain about b.

The magnitude of the compressive strain that the cord 3 of the inner and outer ply layers of the carcass 5 receives when a large tire for construction vehicles, for example, tire size 26.5-25, is transferred is shown in Fig. 4. As shown by the lengths of arrows 15 and 17, there is a large difference between the bead portion (5a) and side portion 5b of the carcass 5. In other words, in the inner ply layer 5p+, the compressive strain of the cord 3 is The magnitude 15 of the cord 3 has a peak value from the shoulder portion 5C of the carcass 5 to its maximum width position 5m.In addition, in the outer ply layer 5pz, the magnitude 17 of the compressive strain of the cord 3 is the same as that of the carcass 5. from the side portion 5b of the bead portion 5
The compressive strain of the cord 3 is particularly large at the bead portion 5a. Then, a large compressive strain of the cord 3 in the bead portion 5a of the outer ply layer 5pz occurs repeatedly due to tire displacement, resulting in fatigue failure of the cord in the bead carcass and CBU failure.

Furthermore, the compressive strain ε in the cord direction of the cord 3 of the bead portion 5a of the carcass 5 is as shown in FIGS.
The strain was decomposed into three strains: 1 and shear strain εrs in the tire circumferential direction, and the ratio of the magnitudes of the components was investigated. As a result, the following formula: circumferential shear strain ε, ) = (radial strain εr):
(Circumferential strain εt)=s:3:i It was found that the shear strain εrs in the circumferential direction was the largest.

Next, the crown portion lid of the tire 11 will be explained.

A large tire 11 for a construction vehicle with a tire size of 24.00-49, for example, is inflicted on the crown lid of the tire 11 at a mining or construction site during transfer, and the injury distribution is as shown in FIG. . This distribution clearly represents the distribution of external forces that the tire receives during transfer. According to this, the area receiving cuts and external forces is the tire 11.
It extends from the crown center 13 of the crown portion lid to the vicinity of the shoulder 14.

Further, when the tire rides on a protrusion or the like during transfer, the tension applied to the cord extends over a considerable distance from the center of the protrusion, as shown in FIG. Moreover, in the crown part 5d of the carcass 5, the heat generation temperature distribution of the carcass 5 is as shown in FIG.
a second ply layer outside the temperature of the ply layer bundle 5;5. The temperature of the shoulder 14 is higher than that of the crown center 13.

Based on these findings, the present inventors conducted various studies and discovered the following points.

When reinforcing the strength of the carcass in order to increase the cut resistance and burst resistance of the tread and the crown of the carcass, the reinforcing layer from the side part of the carcass to the bead part is removed, and conversely, the reinforcing layer from the side part to the bead part is C resistance up to
When reinforcing the rigidity of the carcass to enhance the BU properties, the reinforcing layer at the crown portion of the carcass is removed. Furthermore, it has been found that when reinforcing both of the above-mentioned parts at the same time, it is effective and economical to remove the reinforcing layer near the shoulder part of the carcass. In other words, one or two discontinuous areas of the reinforcing layer are created between a pair of bead cores depending on the purpose.
It has been found that it is desirable to have an intermittent reinforcing layer.

In addition, in order to prevent separation failure of the reinforcing layer, the direction of the cord of the reinforcing layer and the direction of the cord of the ply layer adjacent to the reinforcing layer are opposite to each other with respect to the tire equatorial plane. It has been found that it is desirable to overlap and interpose two reinforcing layers with cords arranged in opposite directions relative to the tire's equatorial plane.

In addition, in order to effectively enhance the CBU resistance of the carcass at the bead section, the reinforcing layer placed between the side section and the bead section suppresses distortion near the cord ends of the reinforcing layer, and improves the separation resistance of the carcass. In order to prevent CBU failure without degrading performance, it is desirable to avoid the inner ply layer of the carcass where a large compressive strain is applied to the cord from the shoulder area to the maximum width position of the cross section of the carcass, and place the cord between the outer ply layers. I found out.

In addition, the reinforcing layer placed in the crown part in order to effectively enhance the cut resistance and burst resistance of the crown carcass is designed to reduce separation resistance due to a decrease in adhesive strength between the cord and rubber due to heat generation, and to prevent thermal fatigue. In order to prevent the strength of the cord from decreasing due to heat generation, it has been found that it is desirable to avoid the outer ply layer of the carcass, where the heat generation temperature is high, and to arrange it between the inner ply layers.

The present inventors further conducted intensive research and arrived at the invention of the present application.

A pneumatic bias tire for heavy loads according to the first invention of the present application is made up of a pair of bead cores and rubber-coated organic fiber cords, which are arranged so that the cord direction intersects the tire circumferential direction and intersects each other, and between the bead cores. In a pneumatic bias tire for heavy loads, comprising a carcass having a plurality of ply layers that extend continuously from the bead portion through the side portions to the crown portion in a toroidal manner and are wound and fixed around a bead core. The reinforcing layer is disposed discontinuously between the bead cores and reinforces the carcass, and the reinforcing layer has a total number n of plies from the outermost ply layer between the side part of the carcass and the bead part.
It is characterized by being provided between two-thirds of the ply layer.

Here, the reason why the reinforcing layer is provided between the outermost ply layer of the carcass and the ply layer that is 2/3 of the total number of plies is that it is provided from the shoulder to the ply layer that exceeds 2/3 of the total number of plies. When installed between the inner ply layers where the compressive strain applied to the cord is large towards the maximum middle position of the carcass cross section,
This is because the strain occurring in the vicinity of the cord end of the reinforcing layer becomes large, which may conversely lead to separation failure and CBU failure.

In addition, only one pair of the reinforcing layers is interposed between the same ply layers, and the direction of the cord of the reinforcing layer and the direction of the cord of the ply layer adjacent to the reinforcing layer are mutually different from each other. It is desirable that the cord directions of the two reinforcing layers be arranged in opposite directions to each other with respect to the equatorial plane.

Further, the reinforcement angle between the cord direction of the reinforcing layer and the tire radial direction is +35° to +55° and -35° to -55°.
A range of ° is desirable. Here, the reason why the reinforcement angle is set to the above range is that it is most effective in increasing carcass rigidity against circumferential shear strain, and if the reinforcement angle is less than ±35°, the effect of increasing rigidity is small; This is because, if it exceeds .degree., the rigidity load on the cord of the reinforcing layer becomes too large, and the reinforcing layer itself may cause a CBU failure.

Further, the bead core is composed of a plurality of bead core bodies,
Preferably, a ply layer bundle consisting of a plurality of ply layers is wound around each bead core body, and the reinforcing layer is interposed between braying layers in the ply layer bundle. This is because when the reinforcing layer is interposed between a plurality of ply layer bundles, the strain generated near the cord ends of the reinforcing layer increases, leading to a decrease in separation resistance and CBU resistance.

Furthermore, when the bead core is made up of a plurality of first and second bead cores, and a ply layer bundle made up of a plurality of ply layers is wound around each bead core, two It is desirable that the stacked reinforcing layers are also rolled back at the same time, and the ends of each rolled up reinforcing layer are approximately equal to the distance difference l between the ply layer ends and the ply layer ends of the ply layers adjacent on both sides of the reinforcing layer. 1/2
It is desirable to be located in

Further, the reinforcing layer may be of a so-called offset type in which two reinforcing layers having the same width are pasted in a shifted manner in the width direction, or one in which two reinforcing layers with different widths are pasted together with their centers in the width direction aligned. desirable.

(Function) The reinforcing layer is provided between the eyebrows of the carcass, and from part of the shoulder to the maximum middle position of the cross section of the carcass, avoiding the inner ply layer where the compressive strain of the cord is large. The strength of the carcass from the to the bead portion is effectively increased, and the rigidity thereof is increased. Therefore, the compressive strain of the cord and the ends of the cord is small, and CBU failure due to mechanical fatigue failure of the cord is less likely to occur.

In addition, if only one pair of reinforcing layers are interposed between the same ply layers and that ply layer is wound back around the bead core, the number of ends of the reinforcing layer is two because the reinforcing layer is also wound back at the same time. By shifting the edge of the reinforcing layer that is rolled back from the edge of the ply layer, CBU failure becomes more difficult to occur without reducing separation resistance. In addition, since the reinforcing layer is interposed discontinuously between the bead cores, the carcass is not needlessly reinforced, so it can be reinforced economically.

Next, the pneumatic bias tire for heavy loads according to the second invention of the present application is composed of a pair of bead cores and rubber-coated organic fiber cords, and the cord directions are arranged to intersect with the tire circumferential direction and intersect with each other, A pneumatic bias tire for heavy loads, comprising: a carcass having a plurality of ply layers that extend continuously from the bead part through the side part to the crown part between the bead cores in a toroidal shape and are wound and fixed around the bead core; A two-ply reinforcing layer is disposed discontinuously between the bead cores between the brie layers and reinforces the carcass, and the reinforcing layer is arranged between the side part of the carcass and the bead part, and has two of the total number of briai pieces from the outermost ply layer. It is characterized in that it is provided between up to /3 ply layers and between the innermost ply layer and 2/3 ply layers of the total number of ply layers at the crown portion of the carcass.

Here, explanations of those having the same configuration as those according to the first invention of the present application will be omitted, and only the differences will be explained.

Furthermore, the reason why the reinforcing layer is provided in the crown part of the carcass between the innermost ply layer of the carcass and the ply layer that is 2/3 of the total number of plies is that it is 2/3 of the total number of ply layers. If it is provided between the outer braai layers beyond the ply layer, the heat generation temperature of the ply layer is high, so the strength of the reinforcing layer cord decreases due to thermal fatigue, and the adhesive strength between the cord and the rubber decreases. This is because separation resistance decreases.

Further, when a plurality of the reinforcing layers are arranged from the inside to the outside between the innermost ply layer of the carcass and two-thirds of the total number of ply layers in the crown part of the carcass, each reinforcing layer is arranged in the tire axial direction. The width of the inner reinforcing layer is narrower than that of the outer reinforcing layer in order to gradually increase the strength of the carcass toward the crown center in response to external forces and the frequency of cuts. Preferably, the edge of the reinforcing layer between the innermost carcass layers is located in the intermediate area between the crown center and the shoulder, and the edge of the reinforcing layer between the outermost carcass layers is preferably located in the intermediate area between the shoulder and the maximum width position of the carcass cross section. It is desirable to provide the

This prevents the high heat generation near the shoulder area from becoming even higher due to excessive carcass wall thickness, prevents deterioration of separation resistance and thermal fatigue of the cord, and places the reinforcing layer end at a position where the compressive strain of the inner ply layer is large. This is also to prevent them from being placed in the same position.

Further, among the reinforcing layers, the cord direction of the reinforcing layer disposed in the crown portion of the carcass is the same as the cord direction of the adjacent ply layer in order to cross each other with respect to the tire equatorial plane, as in the first invention. It is desirable to interpose only one pair of reinforcing layers between the ply layers, with the cord arrangement intersecting the tire equatorial plane at approximately the same angle as the cord direction of the ply layers.

This is because when the tire runs over a protrusion, the tire wraps around the protrusion due to the pantograph deformation of the cord, creating a large so-called enveloping effect that cushions and absorbs the impact when the tire runs on the protrusion.

(Function) The reinforcing layer of the tire of the first invention of the present application is the same as described above, and will therefore be omitted.

The reinforcing layer is provided at the crown part of the carcass between specific ply layers of the carcass, avoiding the outer ply layer that generates high temperature, and changing the width of the reinforcing layer in stages, so that the cord of the reinforcing layer is The strength of the carcass at the crown portion is effectively increased without deterioration due to thermal fatigue or deterioration in separation resistance. Therefore, cut resistance and burst resistance are improved.

(Example) Embodiments of the present application will be described below based on the drawings.

FIG. 1 is a diagram showing an embodiment of a pneumatic bias tire for heavy loads according to the first invention of the present application.

First, the configuration will be explained. In FIG. 1, 21 is a pneumatic bias tire for heavy loads, which has a tire size of 23.5-25 24PRLa class and is mainly used for loading work on good roads. The pneumatic bias tire 21 for heavy loads has two pairs of inner first bead cores 22A.
and an outer second bead core 228 (hereinafter represented by 22) and a rubber-coated 1890 d/2 nylon cord (hereinafter simply referred to as a cord) 23, with a bead portion 25 between each of the bead cores 22A and 22B.
The carcass 25 has ten ply layers 25p arranged in a toroidal manner from a to a crown part 25d through side parts 25b and shoulder parts 25c. The carcass 25 is a first to third ply layer bundle 25 which is arranged sequentially from the inside to the outside of the tire and bundles ply layers 25p.
It is composed of A to 25C. In addition, the ten ply layers 25p are arranged from the inside of the tire to the outside of the first ply 25p.
They are arranged in the order of 1st to 10th brushes 25p+o.

In each ply layer bundle, the first ply layer bundle 25A winds four ply layers 25p from the inside to the outside of the first bead core 22A, and the second ply layer bundle 25. is 4 ply layers 25
p to the second bead core 22. from the inside to the outside to form the third braai layer bundle 25. The two ply layers 25p are passed from the outside of the bead portion 25a through the bead heel 27 to the bead toe 2.
It ends inside 8 and is fixed.

The layer ends 25q of each ply layer 25p are 30cm apart from each other.
They are arranged to have a step difference Ls.

The cords 23 of the ply layer 25p are arranged in a direction that intersects the tire circumferential direction at a cord angle θ of about 36° in the tire equatorial plane E, and are arranged so that they intersect with each other alternately on the left and right from the inside to the outside of the carcass. placed first
Bead core 22A and second bead core 22. It is wrapped around and fixed. The number of cords 23 in each ply layer bundle is 19/25 in the first ply layer bundle 25A and 19/25 in the second ply layer bundle in the crown portion of the carcass. is 14
14 pieces/25mm, 3rd ply layer bundle 25C/25+
It is n.

A first reinforcing layer 31 and a second reinforcing layer 32, which are two superimposed layers.
are arranged discontinuously between the bead cores 22 between the ply layers 25p to reinforce the carcass 25. The first reinforcing layer 31 extends from the side portion 25b of the second ply layer bundle 258 to the bead portion 25a of the second ply layer bundle 25. 6th ply 2
5p, and the seventh braai 25p7.

The first reinforcing layer 31 extends from the carcass 25 from the bead portion 25a to the side portion 25b inside the second bead core 22B.
The inner reinforcing layer 31 extends to near the maximum width position of 25 m.
a, and a second bead core 22.a continuous to the inner reinforcing layer 31a.
and an outer reinforcing layer 31b extending from the bead portion 25a to the side portion 25b on the outside of the bead portion 25a. As shown in FIG. 1(b), the outer end 31c of the outer reinforcing layer 31b is
The outer ends 31c of the sheets have an anti-tip difference Ms of 300 and the adjacent sixth and seventh plies 25p6 and 2
5p and each end has a step difference Ns of 15tm.

The second reinforcing layer 32 is the side portion 2 of the third ply layer bundle 25C.
5b to the bead portion 25a, the third ply layer bundle 25
The side portion 25b of the third ply layer east 25C is arranged between the 91st lie 25p and the 10th ply 25p+o of C.
It is provided so as to pass through the bead heel 27 of the bead portion 25a from above the maximum width position 25m and terminate at the bead toe 28.

The first reinforcing layer 31 and the second reinforcing layer 32 each consist of a rubber-coated 1890 d/2 66 nylon cord 34, and the number of strokes is approximately 14/25 fins. 1st
The reinforcing layer 31 and the second reinforcing layer 32 each consist of a pair of reinforcing layers stacked together, and the cords 34 of the reinforcing layer
The cord directions are arranged to intersect each other and intersect with the cords 23 of the adjacent ply layer 25p at an angle of ±45° with respect to the radial direction of the tire. Reference numeral 35 denotes a breaker, and the breaker 35 is arranged outside the crown portion 25d of the carcass 25 so as to cover the crown portion 25d. Breaker 35 is rubber coated 840 d/
There are two breaker layers made of 2.66 nylon cord. 37 is a tread placed between the shoulders 36, and 38 is a sidewall placed from the shoulder 36 to the vicinity of the bead heel 27, both of which cover the outside of the carcass 25.

Next, the effect will be explained.

The first reinforcing layer 31 and the second reinforcing layer 32
The cords 34 are arranged between the specific braai layers 25p while avoiding the inner ply layer 25p of the carcass 25 where the cords 34 have a large compressive strain, and the cord direction of the cords 34 of the reinforcing layer is ± with respect to the radial direction of the tire. Since it is provided at an angle of 45°, the strength of the carcass 25 from the side portion 25b to the bead portion 25a of the carcass 25 is enhanced, and in particular, the rigidity in the tire circumferential direction is significantly enhanced. Therefore, the compressive strain of the cords 23 of the carcass 25 and the first reinforcing layer 31, the cords 34 of the second reinforcing layer 32, and the ends of the cords is small, and CBU failure due to fatigue fracture of the cords is less likely to occur. In addition, the first and second reinforcing layers 31 and 32 are the ply layers 25p.
There is only one pair of two layers in between, so
The number of reinforcing layer ends 31c interposed between the ply layers 25p is small, and CBU failure is less likely to occur without deteriorating separation resistance between the ply layers 25p. Also, 1st.
2 reinforcing layers 31 and 32 are attached to the bead portion 2 of the carcass 25.
It is interposed only between the side part 5a and the side part 25b, and the shoulder part 2
The carcass 25 is discontinuously arranged between the bead cores 22 so as not to be interposed from the crown part 5c to the crown part 25d, and the carcass 25 is not needlessly reinforced, so the reinforcement of the carcass 25 is efficient, economical, and inexpensive. Can be done.

Next, the effects of the present invention, which were confirmed through tests, will be explained. The number of ply layers 25p of the carcass 25 has been significantly reduced from the conventional 14 to 10. In addition, as a result of a comparative test at the site of use, the tire lifespan was 20% longer than that of conventional tires.
It was possible to increase it by 30%.

Next, an embodiment of the second invention of the present application will be described.

FIG. 2 is a diagram showing an embodiment of a pneumatic bias tire for heavy loads according to the second invention of the present application.

First, the configuration will be explained. In FIG. 2, 41 is a pneumatic bias tire for heavy loads, and the pneumatic bias tires 41 for heavy loads have a tire size of 26.5-
25 20PRLa class, mainly used for excavation and transportation work in rough ground. In the pneumatic bias tire 41 for heavy loads, the same components as in the embodiment of the pneumatic bias tire for heavy loads according to the first invention (FIG. 1) are given the same reference numerals, and the description thereof will be omitted.

The pneumatic bias tire 41 for heavy loads has a carcass 2
In order to increase the strength and rigidity of the carcass 25 from the bead portion 25a to the side portion 25b of No. 5, the carcass 25 from the bead portion 25a to the side portion 25b is The first reinforcing layer 31 and the second reinforcing layer 32 are provided only in the period up to this point to enhance CBU resistance without causing a decrease in separation resistance, and to enhance cut resistance and burst resistance. This is a case where a reinforcing layer is provided only on the crown portion 25d of the carcass 25.

In the pneumatic bias tire 41 for heavy loads, 2
The 3rd to 4th reinforcing layers 43 to 44, which are stacked on top of each other, are the ply layer 2.
5p, discontinuously arranged in the crown portion 25d between the bead cores 22 to reinforce the carcass 25.

That is, the third reinforcing layer 43 is arranged between both shoulders 36 of the crown part 25d 25m east of the first ply layer and between the third ply 25p and the fourth braai 25p4 25m east of the first ply layer, and The crown portion 25d of No. 25 is reinforced. The third +fa strong layer 43 is the shoulder part 2
5c to bead portion 25a are not arranged.

The fourth reinforcing layer 44 extends from the sixth ply 25 between the crown portion 25d and the shoulder portion 25c of the second ply layer bundle 251.
p and the seventh braai 25p, and reinforces the carcass 25 from the crown portion 25d to the shoulder portion 25c. Further, a first reinforcing layer 31 is arranged from the side portion 25b to the bead portion 25a between the same ply layers. Width W4 of the third reinforcing layer 43. is narrower than the width W44 of the fourth reinforcing layer 44, and the reinforcing layer reinforcing the inner ply layer 25p of the carcass 25 is narrower than the width W44 of the fourth reinforcing layer 44.
End portion 43 of two layers of reinforcing layer 43 and fourth reinforcing layer 44
a and 44a are each configured to have a step difference T of 40 fins from each other. The third to fourth reinforcing layers 43 and 44 are each rubber-coated 1890 d/
Consists of 2 66 nylon cord 34, the number of strokes is approximately 1
4 pieces/25 fl. The third reinforcing layer 43 and the fourth reinforcing layer 44 each consist of a pair of reinforcing layers made by stacking two ζ sheets, and the cord directions of the cords 34 of the reinforcing layers intersect with each other and are at an angle of ±36° with respect to the equatorial plane E of the tire. The cords 23 are arranged to intersect with the cords 23 of the adjacent ply layers 25p at an angle. 35 is a breaker, breaker-3
5 is arranged outside the crown part 25d of the carcass 25 so as to cover the crown part 25d. Breaker 35 is a three layer breaker consisting of rubber coated 840 d/2 66 nylon cord.

Next, the effect will be explained.

The third reinforcing layer 43 and the fourth reinforcing layer 44
A specific ply Ji of the carcass 25 between the braai layers 25p of
25p and avoiding the outer ply layer 25p of the carcass 25 where the carcass 25 has a high heat generation temperature, and the cord direction of the cords 34 of these reinforcing layers is ±36° with respect to the tire equatorial plane E. Since the cords 23 of the adjacent ply layer 25p intersect each other and the cord angles are the same, the cords of the third reinforcing layer 43 and the fourth reinforcing layer 44 have a reduced strength due to thermal fatigue and a reduced adhesive strength with rubber. There was no decrease in separation resistance due to carcass 2.
The strength of the crown portion 25d of No. 5 is increased without losing the envelope effect, and the cut resistance and burst resistance are significantly improved. In addition, only a pair of reinforcing layers are interposed by overlapping two sheets of the same ply between the eyebrows, and the edges of the reinforcing layers are small, and the edges of the reinforcing layers are offset from each other, so separation failure is even less likely to occur and separation resistance is greatly improved. can.

Further, since the third reinforcing layer 43 and the fourth reinforcing layer 44 are arranged so as to have a discontinuous zone between the bead cores 22, the carcass 25 is not needlessly reinforced.
Reinforcement of the carcass can be done effectively and economically and inexpensively. This can greatly improve the durability of the carcass.

Next, the effects of the present invention, which were confirmed through tests, will be explained. The number of ply layers in the carcass has been reduced from 14 to 10. In addition, the results of comparative tests at the site of use,
Tire life can be increased by 20% to 30% compared to conventional tires.

(Effects) As explained above, according to the first invention of the present application, the reinforcing layer is provided discontinuously between the bead cores between specific carcass layers of the carcass, that is, only between the side part of the carcass and the bead part. As a result, the strength and rigidity of the carcass during this period can be increased and CBU failures can be prevented. For this reason, the carcass can be reinforced effectively, economically, and for different purposes suited to the usage conditions of the tire, and the durability performance of the tire can be significantly improved.

Further, according to the second invention of the present application, in addition to the effects of the first invention of the present application, by providing the reinforcing layer discontinuously between the bead cores between specific ply layers of the carcass, that is, only in the crown portion of the carcass, During this time, the strength of the carcass is increased, and the cut resistance and burst resistance can be improved without causing a decrease in separation resistance. Therefore, the carcass can be reinforced effectively, economically, and for different purposes, depending on the usage conditions of the tire, and the durability of the tire can be significantly improved.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are views showing an embodiment of a pneumatic bias tire for heavy loads according to the first invention of the present application, FIG. Figure (b) is a sectional view of the main part. FIG. 2 is a partial sectional view showing an embodiment of a pneumatic bias tire for heavy loads according to the second invention of the present application. Figures 3 to 9 are diagrams showing the structure and characteristics of conventional tires tested regarding invention 1.2 of the present application;
The figure is a partial cross-sectional view, Figure 4 is a diagram showing the compressive strain that the cord of the carcass receives during load transfer, and Figures 5 (a) to (
d) is a conceptual diagram showing an overview of the compressive strain in the cord direction, the compressive strain in the tire radial direction, the compressive strain in the tire circumferential direction, and the shear strain in the circumferential direction, which are applied to the cord in the bead portion of the carcass, respectively;
The figure is a graph showing the injury distribution of cuts at the time of transfer.
The figure is a graph showing the tension distribution applied to the cord when it rides on the protrusion, and FIG. 8 is a graph showing the temperature distribution at the crown portion of the carcass. FIG. 9 is a partial sectional view showing a conventional tire. 21...Pneumatic bias tire for heavy loads,
22A, 22. ...Bead core, 23...
... Nylon cord, 25 ... Carcass, 25a ... Bead part, 25b ... Side part, 25c ... Shorter part, 25d ... ...Crown part, 25p...Ply layer, 31...First reinforcing layer, 32...Second reinforcing layer, 34...Reinforcing layer Cord, 43... Third reinforcing layer, 44... Fourth reinforcing layer.

Claims (2)

[Claims] (1) Consisting of a pair of bead cores and rubber-coated organic fiber cords, the cords are arranged so that the cord direction intersects the tire circumferential direction and intersects each other, and between the bead cores there is a continuous toroidal pattern from the bead part through the side part to the crown part. A pneumatic bias tire for heavy loads, comprising: a carcass having a plurality of ply layers wound around and fixed to a bead core across the ply layers; The reinforcing layer is provided between the side part of the carcass and the bead part, and between the outermost ply layer and two-thirds of the total number of plies in the ply layer. A pneumatic bias tire for heavy loads. (2) Consisting of a pair of bead cores and rubber-coated organic fiber cords, the cords are arranged so that the cord direction intersects the tire circumferential direction and intersects each other, and between the bead cores there is a continuous toroidal pattern from the bead part through the side part to the crown part. A pneumatic bias tire for heavy loads, comprising: a carcass having a plurality of ply layers wound around and fixed to a bead core across the ply layers; The reinforcing layer is provided between the side part of the carcass and the bead part, and between the outermost ply layer and a ply layer corresponding to 2/3 of the total number of plies of the carcass, and A pneumatic bias tire for heavy loads, characterized in that the ply layer is provided between the innermost ply layer and two-thirds of the total number of ply layers in the crown portion of the ply layer.