JPH04358906A - Pneumatic bias tire for construction vehicle - Google Patents

Abstract

PURPOSE:To provide high stability with anti-side cut performance and weight reduction provided by specifying the relation of respective line segments with regard to a tread end and a protector, and the relation of total thickness from plural points to a point where normal lines reach the inner surface of a carcass respectively. CONSTITUTION:There are provided at least a bias a bias carcass ply, a tread 1 provided with a lug groove 2 on the outside of the bias carcass ply, and a side wall 5 provided with a ring-formed protector 7 which protrudes toward the outside of a tire in the tire. With this constitution, viewing the meridian sectional surface of the tire, a line AC from a tread end A toward the inner side in a diametrical direction and a line BC from the top point B of the outside in a diametrical direction of the protector 7 toward the inside of the tire are made to cross at a point C, and the respective lines AC, BC are made to approximate to a straight line. If total thickness from the respective points A-C to points where normal lines reach the inner surface of a carcass are taken as TA, TB, and TC respectively, they are set so as to satisfy the relationship of 2.2<=TA/TC<=3.0, 1.0<=TB and TC<=1.2.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a pneumatic bias tire for construction vehicles, particularly a pneumatic tire used for wheel loaders mainly used for loading. This invention relates to a tire that maintains a light weight and has good stability against rolling, etc.

0002

[Prior Art] Pneumatic tires for construction vehicles operating on rough ground such as civil engineering sites and quarries are
If a stump or a chunk of rock rubs the side of the tire,
Or, it often pierces this side part, causing cuts and cracks. Therefore, in order to protect the side parts of tires for vehicles used in this type of work, an annular protector that protrudes outward in the width direction of the tire is installed slightly inside the shoulder part in the direction of the rotational axis. It is common to form the
No. 1). Such an annular protector is intended to minimize cuts and cracks on the side portion of the tire due to contact with rock masses and the like, and to protect the side portion of the tire by blowing these away.

However, in recent years, there has been a demand for tires to be lighter in weight in order to save energy, and pneumatic tires for construction vehicles are no exception. In order to reduce weight, there is a trend to make the entire tire thinner, and from the tire side, one of the targets is changing the shape of the annular protector. However,
On the other hand, a protector shape is desired that allows the annular protector to be clearly identified from the user's evaluation of the tire's appearance.

[0004] In order to meet the above-mentioned demands, the inventors of the present invention, while conducting intensive research, developed an air compressor for construction vehicles that made the overall structure of the tire thinner and lighter, and formed a conventional annular protector thereon. It has become clear that there are new problems with tires that have never been seen before. For example, in the case of a loader with a bucket, it has been found that during tapping loading, the rolling of the vehicle body, especially the bucket portion, increases and at the same time, the loader becomes difficult to fit. When the cause of this was investigated, it was found that when the bucket tilted to its maximum, a type of buckling phenomenon appeared near the confluence of the surface of the tire buttress and the aforementioned annular protector. did. That is, especially for loader tires, the width of the tread portion is made wide in order to improve the overall wear resistance and prevent rocks from getting stuck, i.e., cut, and the tread width accounts for about 85 to 95% of the maximum width of the tire. It becomes.

[0005] For this reason, the side surface of the tire from the shoulder portion to the beet portion, that is, the buttress portion, has a substantially vertical shape. With this tire shape, if the entire tire is made thinner and an annular protector is formed radially inside the buttress portion, a constriction will occur at the intersection of the buttress portion and the annular protector portion.
Therefore, when a large unbalanced load is applied to one side of the tread of a tire during tipping, such as with a loader with a bucket, compressive strain is concentrated on this constriction, resulting in a buckling-like phenomenon. It was found that this occurs.

[0006]

SUMMARY OF THE INVENTION The present invention addresses the need to reduce the weight of tires by providing an annular protector that is clearly distinguishable in appearance, and furthermore, the present invention addresses the need for reducing the weight of tires by attaching an annular protector that is clearly distinguishable in appearance. An object of the present invention is to provide a pneumatic bias tire for a construction vehicle that does not cause a buckling phenomenon in the bent portion. That is, the problem to be solved is to achieve the same rolling size as a tire before weight reduction or an OR tire without a side annular protector, and to obtain the same rolling convergence characteristic.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention employs the following characteristic tire structure. That is, the gist of the present invention is to provide a bias carcass ply of at least four or more plies made of organic fiber cord, a tread having lug grooves on the outside of the carcass ply,
In a pneumatic tire equipped with a sidewall having an annular protector projecting outward from the tire, when viewed from the meridional section of the tire, ■ a line AC pointing radially inward from the tread edge A and a radial direction of the protector. A line BC extending from the outer vertex B toward the inside of the tire intersects at point C, and the lines AC and BC are approximately approximated by straight lines. The total thickness obtained by TA and T are respectively
If B and TC, then 2.2≦TA/TC≦3.
0, 1.0≦TB/TC≦1.2, the pneumatic bias tire for construction vehicles is characterized by satisfying the following, preferably a straight line -The vertical distance to X is h1, and the vertical distance from point B to line Y-Y passing through point A and parallel to the axis of rotation is h.
2 and the tire cross-sectional height is SH, then 0.02≦
h1 /SH≦0.03, 0.06≦h1 /h2
≦0.15, and if α is the inclination angle inward of the tire where line BC intersects straight line XX, then 20 degrees≦α
≦35 degrees, and in particular, it is preferable that the bottom of the lug groove be located radially outward from the intersection point C that opens to the buttress portion.

[0008]

[Function] Fig. 1 is a sectional view of the tire of the present invention, in which 1 is a tread portion, 2 is a lug groove formed in this tread portion 1 from both sides toward the center obliquely and taperingly, and 3 is a lug groove formed in this tread portion 1 from both sides toward the center. These lugs are divided by lug grooves 2. The side surface of the tire continues from the end of the tread portion 1 to a buttress portion 4, a sidewall portion 5, and a bead portion 6.
An annular protector 7 having a trapezoidal or triangular cross section is formed between the sidewall portion 5 and the sidewall portion 5. 8 in the figure is a carcass part. and a buttress portion 4 extending in the tire radial direction from the end A of the tread portion 1, and an annular protector 7.
Let C be the intersection point between the radially outward vertex B and the line inward of the tire. Note that a somewhat curved surface may be formed at this intersection C portion.

For example, when the loader bucket is lifted and the vehicle is driven on an uneven road surface, the vehicle body rolls left and right, and a large unbalanced load acts on the vicinity of the end A of the tread portion 1. As mentioned above, in conventional loader tires, the buttress portion 4 is formed approximately at right angles to the surface of the tread portion 1 in order to make the width of the tread portion 1 as wide as possible. . Therefore, due to the large unbalanced load generated at the end A of the tread portion 1, the buttress portion 4 has a small bending component protruding outward from the tire, while a large radial compression component almost perpendicular to the road surface is applied to the buttress portion 4. As a result, a buckling phenomenon occurs at the intersection C between the buttress portion 4 and the annular protector 7.

[0010] The present invention specifies the positional relationship between the buttress portion 4 and the inner surface of the carcass of the annular protector 7, thereby making it difficult for buckling-like phenomena to occur without sacrificing the desire to reduce the weight of the tire. Particularly preferably, the positional relationship between the two can be further specified to bring about a remarkable effect. That is, when a large unbalanced load acts on the end A of the tread portion 1, the bending component distribution from the end A to the apex B of the annular protector 7 across the intersection C that causes a buckling phenomenon is made as uniform as possible. In particular, the bending stiffness level difference (drop) near the intersection C is reduced, and at the same time, its absolute value is increased. Therefore, by increasing the gauge between the inner surface of the carcass near the intersection C and conversely decreasing the gauge between point A and the inner surface of the carcass and between point B and the inner surface of the carcass, the buckling This makes it difficult for this phenomenon to occur.

In the present invention, if the thickness from the end A of the tread portion 1 to the inner surface of the carcass is TA, the thickness from point C is TC, and the thickness from point B is TB. , the ratio of TA and TC is within 2.2 to 3.0,
By setting the ratio between TB and TC within 1.0 to 1.2, the compressive strain in the radial direction near the intersection C can be significantly reduced, and the thickness of TA and TB can be reduced to improve TC.
By increasing the thickness of the tire, the distribution of bending stiffness between point A and point B can be made more uniform, making buckling-like phenomena less likely to occur, and as a result, it is possible to reduce the weight of the tire. It has become. Furthermore, the distribution of the composite bending value of the cross section from the TA part to the TB part decreases sequentially from the TA part, reaches the minimum value at the TC part, and then remains almost the same or increases slightly towards the TB part. This suppresses the occurrence of buckling phenomena.

[0012] Among these, the ratio of TA and TB is 2.1 to 2.1.
If it is set to 2.6, it is particularly effective because the bending component is made uniform. Here, if the value of this ratio is less than 2.1, the buckling phenomenon at the intersection C can be suppressed, but the desired T
Attempting to maintain A increases the value of TC, which makes it impossible to reduce the weight of the tire, which is one of the challenges.
On the other hand, if an attempt is made to obtain a TC that can reduce the weight of the tire, the TA becomes too small, which is a problem and causes a significant reduction in the wear life, which is a basic characteristic of tires. On the other hand, if the value of this ratio exceeds 3.0, it will be difficult for the tire to absorb the load by bending outward, especially when the tire is overloaded or a large unbalanced load is applied. Compressive strain tends to concentrate, a buckling phenomenon occurs, and the rolling size, restorability, and convergence are less than permissible.

Next, if the ratio of TB and TC is less than 1.0, not only the side cut resistance of the annular protector will be insufficient, but also the shape will not give a sense of reliability to the user. It is difficult to do this, and if this value exceeds 1.2, points B and C
Since the distance between points A and C is shorter than the distance between points A and C, the gradient of the bending resultant change becomes too large, resulting in the same problem as described above.

[0014] Tire size 26.5-25 20PR
(Nylon cord 1890 denier/2 14 ply)
The bending stiffness value of the OR tire was determined by FEM analysis. The results are shown in Table 1, and it was found that the bending stiffness value was improved by significantly reducing TA and TB while slightly increasing TC compared to the conventional OR tire. That is, 13 mm at the TA section and 8 mm at the TB section.
While the gauge of mm is thinner, the thickness of the TC portion is increased by 4 mm. This gauge up at the TC section is achieved by inserting the same rubber as the carcass outside from the 5th ply to the 8th ply in the center of the carcass.

On the other hand, the buttress portion 4 and the annular protector
Regarding the length (width) relationship centered on the intersection C of No. 7, a straight line perpendicular to the rotational axis of the tire and passing through the intersection C is defined as XX, and the tire diameter of the line BC with respect to this straight line XX is The inclination angle in the direction is α, the distance from the vertex B of the annular protector 7 to the straight line X-X is h1, and the vertical distance from this vertex B to the line Y-Y passing through point A and parallel to the rotation axis is h2 , where the tire cross-sectional height is SH, α is 20 degrees or more and 35 degrees or less, and the ratio between h1 and h2 is 0.06 or more and 0.15
Hereinafter, the ratio between h1 and SH is 0.02 or more, 0.03
or less, and the ratio of h2 and SH is 0.2 or more, 0.35
Tires that satisfy the following conditions are most effective. If the inclination angle α is less than 20 degrees, the appearance of the annular protector will be damaged and the function of this protector will be insufficient, and if it exceeds 35 degrees, weight reduction will be maintained and buckling at point C will be prevented. It would be impossible. Further, the height h1 of the annular protector should be determined based on appearance, side cut resistance, and rolling stability, and from this point of view it is appropriate to use the cross-sectional height SH as a reference. That is, h1 /SH is 0.02
If it is less than 0.03, problems in terms of rolling stability will be less likely to occur, but the appearance will be poor and the side cut resistance will be insufficient.On the other hand, if it exceeds 0.03, the latter will be good but the rolling - Problems will arise with ring stability. On the other hand, the ratio of h2 to SH is less than 0.2 and 0.35
If it exceeds this, the position of the annular protector will be inappropriate for preventing side cuts.

On the other hand, in order to avoid the buckling phenomenon, ensure stability, and provide a good appearance, the tread width should be made as large as possible, and the cross-section of the tire should be The ratio to width SW is 0.82 to 0.9
1, and in terms of tire stability, the difference h0 in the tire radial direction between the center of the tread portion 1 and the edge A of the tread portion 1 should be large, and in practical use. From above, it is desirable that the ratio to the tire cross-sectional height SH is within the range of 0.07 to 0.13, taking into account the wear life. Note that the bottom of the lug groove 2 is the buttress part 4.
The opening position is h3 outward in the tire radial direction from the intersection C.
If it is inward, it will promote the buckling phenomenon, which is not preferable.

[0017]

[Example] Taking the above conditions into account, the following test tires were prepared and tested. Tire Size: 26.5-25 20PR, OR Tire Tire Structure The tread part has a pattern in which lug grooves are arranged in two rows, slanting left and right in the circumferential direction of the tire, and the carcass is made of nylon cord. (1890 denier/2) ply 1
Four sheets were used. Also, the bead is triple bead ((4)-
(4)-(4)-2) was adopted.

[0018] Furthermore, the tire dimensions were as follows.

Although the annular protector of such a tire looks good, it is a tire that is expected to have problems with rolling stability, and although the tire weight is close to the target value, it is still a little heavy.

[0020] This tire does not have an annular protector, and is expected to have good rolling stability, but its wear life is poor, and since there is no annular protector, side cut resistance may be poor. Predictable. Moreover, the weight of the tire is also heavy.

(Experiment) Measurement results for the above examples, conventional tires and comparative tires, indoor test results, and actual vehicle footage
The ring test results are shown in Tables 1 and 2. The test conditions were a normal internal pressure of 3.5 kgf/cm2, a load of 160% of the normal load (20.3 tons/piece), and the tests were conducted under a heavy load. The amount of vertical deflection and static spring constant were collected using a normal indoor static load tester as supporting data for the actual vehicle feeling test results, and both are expressed as an index with the conventional tire set as 100. The smaller the value for the former, the larger the value for the latter, the better. In addition, the weight is also 100% compared to the conventional tire.
It was displayed as .

Next, in a feeling test on an actual vehicle (loader), the bucket of the loader is raised, and when this bucket is lowered from side to side, the amount of rolling of the vehicle body and the resilience/convergence are evaluated. The performance was evaluated on a five-point scale based on the operator's feeling. This actual vehicle feeling test has an evaluation value of 3.5
The above is the permissible range for an actual vehicle.

[0023]

[Table 1]

[0024]

[Table 2]

The results show that the tire having the shape of the present invention has a remarkable effect of improving rolling stability while ensuring side cut resistance and weight reduction.

[0026]

[Effects] As described above, the present invention limits each structure of the tire and organically combines them, thereby ensuring side cut resistance and meeting the demands of the times for tire weight reduction. However, it was able to provide a tire with good stability, and its contribution to industry was significant.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a tire of the present invention.

[Explanation of symbols]

1. Tread section 2..Lug groove 3..Lug 4..Buttress section 5..Side wall section 6..Bead section 7..Annular protector 8..Carcass section A..Tread End B of the part... Radial outer vertex C of the annular protector... Intersection α between the buttress part and the annular protector... Straight line X-X
The inclination angle h1 of the line BC in the tire radial direction inward against the tire radial direction.The distance h2 from the vertex B of the annular protector to the straight line XX.The distance h3 from the vertex B to the straight line YY.
Distance SH from the point of intersection C where the bottom of the lug groove opens to the buttress part...Tire cross-sectional height straight line X-X...A straight line perpendicular to the axis of rotation of the tire and passing through point C

Claims (3)

[Claims] Claim 1: At least four cords made of organic fiber cords.
In a pneumatic tire equipped with a bias carcass ply larger than the ply, a tread having a lug groove on the outside of the carcass ply, and a sidewall having an annular protector projecting outward from the tire, in a meridional section of the tire, Looking at it, ■ A line AC running radially inward from the tread edge A and a line BC running inward from the radially outer vertex B of the protector intersect at point C, and the lines AC and BC are almost straight lines. Approximately, 2.2≦TA/TC≦3.0, 1. Let TA, TB, and TC be the total thickness of the normal line to the inner surface of the carcass from points A, B, and C, respectively. 0≦TB
A pneumatic bias tire for construction vehicles, characterized by satisfying /TC≦1.2. [Claim 2] From point B to intersection point C perpendicular to the axis of rotation of the tire.
h1 is the vertical distance from point B to line Y-Y passing through point A and parallel to the rotation axis is h2.
If the tire cross-sectional height is SH, then 0.02≦h1 /SH≦0.03, 0.06≦h
1/h2 ≦0.15, and line BC and straight line X
2. The pneumatic bias tire for construction vehicles according to claim 1, wherein α is the angle of inclination within the tire where the angle -X intersects with 20 degrees≦α≦35 degrees. 3. The pneumatic bias tire for construction vehicles according to claim 1, wherein the bottom of the lug groove is located radially outward from the intersection point C that opens to the buttress portion.