JP3074399B2 - Pneumatic bias tire for construction vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic bias tire for construction vehicles, and more particularly to a pneumatic tire used for a wheel loader mainly for loading, which has a small side cut and a tire. The present invention relates to a tire having good stability against rolling and the like while maintaining light weight.

[0002]

2. Description of the Related Art Pneumatic tires for construction vehicles operating on rough ground such as civil engineering sites and quarries are known as:
Stumps and rock masses rub the side of the tire,
Alternatively, cuts and cracks often occur due to sticking into the side portions. Therefore, in the case of a vehicle tire used for this type of work, an annular protector projecting outward in the width direction of the tire is provided slightly inward in the rotation axis direction from the shoulder portion to protect the side portion. It is generally formed beforehand (Japanese Patent Publication No. 61-1768).
No. 1). Such an annular protector is intended to minimize the cutting and cracking of the side portion of the tire due to contact with a rock mass or the like, and to protect the side portion of the tire by splashing them. However, in recent years, weight saving of tires has been required for energy saving measures, and pneumatic tires for construction vehicles are no exception. In order to reduce the weight, there is a tendency that the entire tire is made thinner. When viewed from the tire side, the shape change of the annular protector is one of the objects. On the other hand, on the other hand, a protector shape that allows the annular protector to be clearly identified is desired from the user's evaluation of the appearance of the tire.

[0003] The inventors of the present invention have been diligently studying to meet the above-mentioned demands, and have been working to reduce the weight of the tire by reducing the overall structure thereof, and to provide a conventional pneumatic vehicle with a conventional annular protector. It has been found that there is an unprecedented problem with tires containing tires. For example, in the case of a loader with a bucket, it has been found that, at the time of a tapping load, the rolling of the vehicle body, particularly the bucket portion, becomes large and the accommodation becomes poor. After investigating the cause, it was found that a kind of buckling-like phenomenon appeared near the confluence of the surface of the buttress portion of the tire and the surface of the annular protector when the bucket was tilted to the maximum. did. That is, the width of the tread portion is particularly wide in the tire for the loader in order to improve the wear resistance as a whole and to prevent the rock from being caught or cut, and the tread width is about 85 to 95% of the maximum tire width ratio. It has become. For this reason, the side surface of the tire from the shoulder portion to the beat portion, that is, the buttress portion has a shape that is almost vertical. In this tire shape,
If the entire tire is made thinner and an annular protector is formed radially inside the buttress portion, a constriction occurs at the intersection of the buttress portion and the annular protector portion. When a large unbalanced load is applied to one side of the tread portion of the tire at the time of taping, it has been found that compressive strain is intensively applied to the constricted portion, thereby causing a buckling phenomenon.

[0004]

SUMMARY OF THE INVENTION The present invention addresses the need to reduce the weight of tires by providing an annular protector which is clearly identifiable in appearance, and furthermore, the constriction of the annular protector which is clearly identifiable in appearance. It is an object of the present invention to provide a pneumatic bias tire for a construction vehicle which does not cause a buckling phenomenon of parts. That is, the same low-load tire as the tire before weight reduction or the OR tire without the annular protector on the side.
An object of the present invention is to provide a ring having the same size and to obtain the same convergence characteristics of the rolling.

[0005]

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 plies made of an organic fiber cord, a tread having a lug groove outside the carcass ply, and a side wall having an annular protector projecting outward from the tire. In a pneumatic tire provided with a tire, a line AC extending radially inward from the tread end A and a line BC extending radially outward from the vertex B of the protector in the tire in a meridional section of the tire. Intersect at point C, the line AC
And BC are approximated by a substantially straight line, and the inclination angle of the line AC to the radially outward direction with respect to the straight line XX passing through the intersection C perpendicular to the tire rotation axis is β, and the inclination angle of the line BC to the radially inward direction is Assuming α, β ≧ 6 degrees, 20 ° ≦ α ≦ 35 degrees, and 0.27 ≦ β / α ≦ 0.45 are satisfied, and the tire section height is SH, from the vertex B to the straight line XX. Distance of h
_1, the distance from the apex B until point A measured parallel to the straight line X-X and h _2, in _{0.06 ≦ h 1 / h 2 ≦} 0.15, and 0.02 ≦ h
_{1 /} SH≤0.03 It is a pneumatic bias tire for use.

[0006]

FIG. 1 is a cross-sectional view of a tire according to the present invention, in which 1 is a tread portion, 2 is a lug groove formed diagonally and tapered on the tread portion 1 from both sides toward the center, and 3 is a tread portion. The lug is divided by the lug groove 2. The side surface of the tire continues from the end of the tread portion 1 to the buttress portion 4, the side wall portion 5, and the bead portion 6.
An annular protector 7 having a trapezoidal or triangular cross-section is formed between the side wall portions 5 and 5. In the figure, reference numeral 8 denotes a carcass portion. The intersection point between the buttress portion 4 extending inward in the tire radial direction from the end A of the tread portion 1 and the line extending inward from the vertex B of the annular protector 7 inward in the tire direction is denoted by C. Note that the intersection C may have a slightly curved surface.

For example, when the loader lifts a bucket and travels on an uneven road surface, the vehicle body rolls left and right, and a large unbalanced load acts near the end A of the tread portion 1. As described above, in the conventional loading tire, since the width of the tread portion 1 is made as wide as possible, the buttress portion 4 is formed almost perpendicular to the surface of the tread portion 1. . For this reason, due to the large uneven load generated at the end A of the tread portion 1, the buttress portion 4 has a small bending component projecting outward from the tire, while a large radial compression component substantially perpendicular to the road surface is added. As a result, a buckling phenomenon occurs at the intersection C between the buttress portion 4 and the annular protector 7.

In the present invention, by specifying the positional relationship between the buttress portion 4 and the annular protector 7, the occurrence of a buckling-like phenomenon is less likely to occur without compromising the demand for reducing the weight of the tire. That is, by suppressing the change in bending stiffness from the buttress portion 4 to the annular protector 7 to a minimum, when a large unbalanced load acts on the end portion A of the tread portion 1, the intersection C where a buckling-like phenomenon occurs is determined. The bending component from the corrugated end A to the vertex B of the annular protector 7 is increased and the tensile strain component is greatly added to reduce the concentrated radial compressive strain near the intersection C. This is because the inside of the tire is originally a car
For this reason, increasing the tensile strain inside the tire due to bending makes the buckling-like phenomenon less likely to occur. In other words, in the present invention, a portion of the rubber obtained by reducing the weight of the other portion is applied to the vicinity of the intersection C, and the bending rigidity is further improved by dispersing and arranging the rubber. This leads to improved vehicle stability.

In the present invention, first, at each inclination angle at the intersection C of the buttress portion 4 and the annular protector 7, a straight line passing through the intersection C perpendicular to the tire rotation axis is defined as X.
−X, the inclination angle β of the line AC to the outside in the tire radial direction with respect to the straight line XX is 6 degrees or more, and preferably 10 degrees.
Degrees, the inclination angle α of the line BC in the tire radial direction is 20 degrees or more and 35 degrees or less, and the ratio between the inclination angles β and α is 0.27 or more and 0.45 or less. Optimally,

If the inclination angle β is less than 6 degrees, if the unbalanced load is large, buckling will occur at the point C or the tire weight will increase, and if it exceeds 10 degrees, the tread width will be too narrow, There is a possibility that bites may be easily bitten.
On the other hand, if the inclination angle α is less than 20 degrees, the appearance of the annular protector is impaired, but the function of the protector becomes insufficient.
On the other hand, if it exceeds 35 degrees, it is not possible to maintain the weight reduction and prevent buckling at the point C. Further, if the ratio of β / α is less than 0.27, even within the above ranges of β and α, the balance of the bending stiffness from the buttress portion 4 to the annular protector 7 is lost, that is, the change in bending stiffness becomes large. Buckling at point C is likely to occur. On the other hand, if the ratio β / α exceeds 0.45, the change in bending stiffness is small, but it is liable to be side cut and cannot be put to practical use. For this reason, it is important to simultaneously satisfy the ranges of β and α and the ratio of β / α.

On the other hand, the buttress portion 4, the annular protector
In the 7 central and the length (width) relationship to the intersection C of the distance from the apex B of the annular protector -7 up straight X-X h ₁ parallel from the apex B to the straight line X-X The measured distance to the end A of the tread portion 1 is h ₂ , and the section height of the tire is SH.
Then, the ratio of h ₁ to SH is 0.02 or more, 0.0
It is necessary to satisfy the condition that the ratio is not more than ₃ and the ratio between h ₁ and h ₂ is not less than 0.06 and not more than 0.15.

The height h ₁ of the annular protector should be determined from the appearance, the resistance to side cuts and the stability of rolling. In this regard, it is appropriate to use the sectional height SH as a reference. That is, when h ₁ / SH is less than 0.02, a problem does not easily occur in terms of rolling stability, but it is poor in appearance and insufficient in side cut resistance.
When this ratio exceeds 0.03, the latter becomes better,
This causes a problem in rolling stability. And also, even proper value of h ₁ is annular protector - also depending subjected to what position B - it was found that differences in the ring stability and resistance to side cut prevents effect. This should determine the value of h ₁ with respect to h ₂ ,
_{If the 1} / h ₂ ratio exceeds 0.15, the rigidity change from the vicinity of point B to point A becomes too large, causing buckling at point C, or preventing point B from becoming too close to point A to prevent side cuts. The effect becomes difficult to obtain or one of the problems occurs,
On the other hand, when the ratio of h ₁ / h ₂ is less than 0.06, the effect of preventing side cuts is weakened, but the appearance is poor. In the present invention, the point B needs to be located radially outward of the tire cross-sectional width.

On the other hand, in order to ensure the stability without causing the above-mentioned buckling-like phenomenon, and to improve the appearance, the tread width should be as large as possible. 0.82 to 0.9 as the ratio to the width SW
1, the difference h _{0 in} the tire radial direction between the center of the tread portion 1 and the end A of the tread portion 1 should be large in terms of tire stability.
From a practical point of view, taking into account the wear life, the tire section height S
The ratio with H is preferably in the range of 0.07 to 0.13. The position where the bottom of the lug groove 2 is opened to the buttress portion 4, there should be in the tire radial direction outwardly h ₃ than the intersection point C, which could be prompting the phenomenon of the seat屈状there inwardly Is not preferred.

[0014]

EXAMPLES Taking the above conditions into consideration, test tires were prepared and tested as follows. Tire size 26.5-25 20PR, off-the-road (lock pattern) tire Tire structure In the tread portion, a pattern is formed in which lug grooves are arranged in two rows in the tire circumferential direction. The carcass is a ply 1 of nylon code (1890 denier / 2)
Four sheets were used. The bead is a triple bead ((4)-
(4)-(4) -2) was adopted. The tire dimensions were as follows.

1. Tire according to the present invention Tire outer diameter OD ‥‥ 1738 mm Section height SH ｍｍ 555 mm Section width SW ６ 694 mm Crown radius CR ８００ 800 mm Tread width TW ６００ 600 mm Specified inclination angle α 傾斜 27 degrees β ９ 9 degrees provisions dimensions _{h 1 ‥‥ 13mm h 2 ‥‥ 157mm} h 3 ‥‥ 3mm h 0 ‥‥ 63mm

2. Conventional tire The tires are the same as those described above, except for the following numerical specifications. In addition, this tire is expected to remain a problem in terms of stability. Tire tread width TW ‥‥ 622 mm defining the inclination angle beta ‥‥ 4 degrees defined dimensions h ₁ ‥‥ 25mm h ₂ ‥‥ 152mm

(Experiment) Table 1 shows the results of a room test and an actual vehicle filling test of the above-described example and the conventional tire. In addition, the tire weight was measured separately. All test conditions were 3.5 kgf / cm ^{2 of} normal internal pressure and the load was 1 of normal load.
The test was carried out under a condition of 60% (20.3 tons / piece) under a large load. The amount of vertical deflection and static spring constant are taken as data supporting the actual vehicle filling test using a normal indoor static load tester, and are all indexed with the conventional tire as 100. The former is better when the numerical value is smaller, and the latter is better when the numerical value is larger. In addition, the weight was similarly set as 100 with the conventional tire.

Next, in a filling test of an actual vehicle (loader), when the loader bucket is raised and the bucket is lowered left and right, the size of the rolling of the vehicle body and the resilience and convergence. The sex was evaluated on a five-point scale by filling the operator. This actual vehicle filling test was conducted at 3.5 evaluation sites.
The above is the allowable range as a real vehicle.

[0019]

[Table 1]

From these results, it can be seen that in the tire having the shape of the present invention, the effect of improving the rolling stability while securing the side cut resistance and the weight reduction is remarkable.

[0021]

As described above, the present invention restricts the respective components of the tire as described above, and by organically combining these components, secures anti-sidecut performance and adapts to the demands of the age of lighter tires. In addition, a stable tire can be provided, and its industrial contribution is significant.

[Brief description of the drawings]

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

[Explanation of symbols]

1 tread part 2 lug groove 3 lug 4 buttress part 5 side wall part 6 bead part 7 annular protector 8 carcass part A tread End of part B {radial outer vertex of annular protector C} Intersection of buttress part and annular protector α {inclination angle β of line BC with respect to straight line XX in radial direction of tire BC}傾斜 Inclination angle of line AC outward with respect to line XX in the tire radial direction h ₀差 Difference in tire radial direction between tire cross-sectional height and end of tread portion h ₁直線 Line X from vertex B of annular protector H ₂距離 Distance from vertex B to tread end A measured in parallel with line XX h ₃距離 Distance from intersection C where the bottom of the lug groove opens to the buttress portion SH ‥‥ Tire section height straight line XX − Intersection C perpendicular to the tire rotation axis Straight line passing through

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60C 11/00-13/02

Claims (2)

(57) [Claims] 1. A bias carcass ply comprising at least four plies comprising an organic fiber cord, a tread having a lug groove outside the carcass ply, and a side wall having an annular protector projecting outward from the tire. In a pneumatic tire provided with a tire, a line C extending radially inward from the tread end A and a line BC extending radially inward from the vertex B of the protector toward the tire in the meridional section of the tire are point C. , The lines AC and BC are approximated by a substantially straight line, the inclination angle of the line AC toward the radial direction outward with respect to the line XX passing through the intersection C perpendicular to the tire rotation axis is β, and the radial direction of the line BC If the angle of inward inclination is α,
β ≧ 6 degrees, 20 degrees ≦ α ≦ 35 degrees, and 0.27 ≦ β
/Α≦0.45, the tire section height is SH, the distance from the vertex B to the straight line XX is h ₁ , and the distance from the vertex B to the point A measured in parallel with the straight line XX is h ₂ , 0.06 ≦ h ₁ / h ₂ ≦ 0.15 and 0.02 ≦ h
_A pneumatic bias tire for construction vehicles, wherein _{1 /} SH ≦ 0.03 is satisfied. 2. The pneumatic bias tire for construction vehicles according to claim 1, wherein the position where the bottom of the lug groove is opened to the buttress portion is radially outward from the intersection C.