JP2003146019A - Tire for agricultural machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire for an agricultural machine that excels in vibrational ride comfort by suppressing a vibration at travel due to a high lug of the tire for an agricultural machine, especially a rolling vibration at good road travel. SOLUTION: The tire for an agricultural machine has a plurality of circumferentially spaced lugs in a tire tread, whose width is equal to or smaller than an overall tire width. A tread end diameter is set smaller than an outside tire diameter by 12 to 20% of the tread width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire used for an agricultural machine used in a mud or a wetland.

[0002]

2. Description of the Related Art In recent years, as housing and land development has expanded from urban areas to their surroundings, agricultural land is often adjacent to residential areas, and road conditions are improving. There are increasing opportunities for agricultural machinery such as tractors and rice transplanters that have finished working on the ground to travel on good roads such as paved roads.

By the way, a tire mounted on an agricultural machine has a relatively high height at a distance in the tire tread circumferential direction because the traction when traveling in a field such as a mud or a wetland is important. In general, a high lug pattern is formed in which high lugs are arranged in an eight shape and the tread width is set larger than the total width of the tire.

This high lug pattern tire certainly exhibits excellent traction in mud and the like,
In particular, since the vibration riding comfort on a paved road is inferior, it is essential to improve the vibration riding comfort in the current situation where the number of times the agricultural machine travels on a good road is increased as described above.

As a measure for suppressing the running vibration of this kind of tire, it is adopted to provide a lug pattern in which the lugs partially overlap each other in the tread circumferential direction or the width direction. It wasn't enough.

Further, from the viewpoint of suppressing vibration riding comfort, especially rolling, a tire in which the tread width is restricted within the total width of the tire has been proposed, but improvement in overall vibration riding comfort is still sufficiently satisfactory. It is not at the level that it does, and further improvement is desired.

[0007]

Therefore, the present invention is
It is an object of the present invention to provide a tire for agricultural machinery, which is excellent in vibration riding comfort, in which vibration during traveling due to a high lag in the tire for agricultural machinery, particularly rolling vibration during traveling on a good road is suppressed.

[0008]

The gist of the present invention comprises:
It is as follows. (1) The tread of the tire, having a plurality of lugs arranged at intervals in the circumferential direction, a tire for agricultural machinery whose tread width is within the total width of the tire, in the widthwise cross section of the tire, Agricultural machinery tires with the diameter of the tread edge smaller than the outer diameter of the tire by 12 to 20% of the tread width.

(2) The surface contour shape of each lug in the widthwise cross section of the tire is smaller than the radius of curvature in the central area of the tread, and the radius of curvature in the outer side areas thereof is small. Tires for agricultural machinery.

(3) In the above (1), a step is provided in the vicinity of the boundary between the tread central region and the outer side regions thereof so that the diameter difference from the tread central region is 1 to 5% of the tread width. The tire for agricultural machinery described.

(4) The tire for agricultural machinery as described in (2) or (3) above, wherein the central region of the tread is a region of 40 to 60% of the tread width centered on the equator of the tire.

(5) The tire for agricultural machinery as described in (2), (3) or (4) above, wherein the radius of curvature in the central region of the tread is equal to or larger than the outer diameter of the tire.

[0013]

FIG. 1 shows a cross section in the width direction of a tire for agricultural machinery according to the present invention. This agricultural machine tire has a plurality of lugs 2 which are arranged at intervals in the circumferential direction of the tread in the tread half portion with the tire equatorial plane O of the tread 1 as a boundary. The extending width of the lug 2 to the outside in the tread width direction is within the total width of the tire. Therefore, the tread width TW is restricted to the range equal to or less than the total width SW of the tire.

The lug 2 is such that, in the tire widthwise cross section, the diameter Eh of the tread end E is smaller than the outer diameter H of the tire by 12 to 20% of the tread width TW, in other words, the outer diameter of the tire. It is important that the drop height δ of the tread edge E with respect to the tread central area TC, which is caused by the difference between H and the diameter Eh of the tread edge E, is 6 to 10% of TW.

Here, the tread edge E is a boundary between the tread surface portion and a padless portion connecting from the tire side portion, that is, a boundary between the surface portion 2a of the lug 2 and the side end surface 2b of the lug 2. By the way, the above-mentioned tread width TW is a distance between both treads E.

In a tire for agricultural machinery, generally, when the tread width is increased, the traction property is improved, but the vibration riding comfort on a good road tends to be deteriorated. This is because when the tread width is large, the point of action of the load center, which is added to the lugs that are distributed to the left and right of the tread surface during running, shifts greatly in the tread width direction between the left and right lugs. , It is thought that this is mainly because the rolling becomes large. Therefore, it is preferable to reduce the tread width from the viewpoint of vibration riding comfort. However, if the width is made too narrow, the excellent traction performance, which is the basic performance of the tire for agricultural machinery, will be impaired, so the balance between the two becomes important. Further, if the tread width is made larger than the total width of the tire, it causes problems such as bringing mud adhered to the outside of the paddy field when used in the paddy field, and lifting soil during field cultivation work. Therefore, here, the tread width TW is restricted to a range equal to or less than the total width SW of the tire.

Next, it is necessary to regulate the falling height δ of the tread end E in order to further improve the vibration riding comfort. That is, if the falling height δ of the crown shape of each lug 2 is 6% or more of the tread width TW, the contact pressure when the lug 2 contacts the ground, that is, the surface pressure near the tread end E becomes small, and the lug 2 Since the contact width of the lug is substantially reduced, the load center when each lug contacts the ground shifts to the tread width center side. Then, the above-mentioned action point of the load center is suppressed from largely deviating in the tread width direction alternately between the left and right lugs, so that the rolling is effectively suppressed. When the drop height δ is 6% or more of TW, the adverse effect on the traction performance is in a negligible range.

On the other hand, when the drop height δ exceeds 10% of TW,
The surface area of the lug, which is involved in the traction force of the tire, is reduced, and the traction force is significantly reduced, which hinders the cultivating work on paddy fields and upland fields.

Here, in order to set the falling height δ to 6 to 10% of TW, the surface contour of each lug 2 in the widthwise cross section of the tire is compared with the radius of curvature R1 in the tread central region TC, Advantageously, the shape is such that the radius of curvature R2 in the outer lateral region TS is smaller. That is, the radius of curvature R1
By forming the tread side region TS with a smaller radius of curvature R2, the drop height δ of the tread E with respect to the tread central region TC is set to 6% or more of TW.

It is preferable that the tread central region TC is a region of 40 to 60% of the tread width TW centered on the equator O of the tire and the remaining both side regions are tread side regions TS. Because, in order to prevent the tread pressure in the region near 50% of the tread width TW from becoming lower than in the region on the shoulder side, a region near 50% of the tread width TW, that is, a region of 40 to 60% of the tread width TW. In order to balance the surface pressure between the region near 50% of the tread width TW and the region on the shoulder portion side by making the boundaries of the regions having different radii of curvature correspond to each other. If this surface pressure balance is lost, uneven wear will occur.

Also, the radius of curvature R in the tread central region TC
1 is preferably equal to or larger than the outer diameter H of the tire. That is, the tread pressure distribution in the tread central region can be made uniform by setting a large radius of curvature R1.

On the other hand, the radius of curvature R2 in the tread side area TS
Is preferably smaller than the radius of curvature R1 in order to reduce the high tread pressure in the tread side region and suppress uneven wear.

Further, another method of setting the drop height δ to 6 to 10% of TW will be described below. That is, as shown in FIG. 2, the tread central area TC and the outer side area T
By providing a step 3 having a diameter difference with the central region of the tread near the boundary with S, the drop height δ of the tread E with respect to the central region TC of the tread is set to 6% or more of TW.

At this time, it is preferable that the diameter difference x from the tread central area TC is 1 to 5% of the tread width TW. Because, if it is less than 1%, the step becomes too low, and it becomes difficult to sufficiently exert the effect of the above step. Meanwhile, 5
When it exceeds%, the area of the lug is greatly reduced, and the traction performance is significantly reduced.

Here, the position where the step 3 is provided is near the boundary between the tread central area TC and the side area TS, more specifically, the tread width T on both sides centering on this boundary.
It is preferably provided within a width of 10% of W.

Even when the step 3 is provided, the tread central area TC is set to 40 mm of the tread width TW.
~ 60% and central area TC and lateral area TS
It is recommended to set the radii of curvature R1 and R2 in the above range to the above range.

[0027]

EXAMPLES As shown in FIGS. 1 and 2, according to various specifications shown in Table 1, the size is AGS 13.6-26.
4PR T13H agricultural machine tires were prototyped. In addition, the other structure was produced in accordance with general tires for agricultural machines of the size.

[0028]

[Table 1]

Each tire thus obtained was mounted on a standard rim and adjusted to an internal pressure corresponding to the maximum load capacity.
We measured the instrumentation and evaluated the driver's feeling of vibration riding comfort when the vehicle was mounted on the rear wheel of a horsepower two-wheel drive tractor and traveled straight on a concrete road at a speed of 16km / h. The results are shown in Table 2.

The instrumental measurement relating to the vibration riding comfort was carried out by measuring the acceleration in the lateral direction of the vehicle with an accelerometer mounted on the floor immediately below the driver's seat. Then, this measurement result is displayed as an index when the vibration level of the conventional tire is 100. The smaller this index, the better the vibration riding comfort.

[0031]

[Table 2]

[0032]

According to the present invention, it is possible to improve the running performance on a good road, particularly the vibration riding comfort, without lowering the traction required when running on a wet field, a soft land or a mud. it can.

[Brief description of drawings]

FIG. 1 is a view showing a cross section in the width direction of a tire for agricultural machinery of the present invention.

FIG. 2 is a view showing a cross section in the width direction of another agricultural machine tire of the present invention.

[Simple explanation of symbols]

1 tread 2 rugs 3 steps TW tread width SW tire total width Outer diameter of H tire

Claims (5)

[Claims] 1. A tire for agricultural machinery having a tread width of a tire within a total width of the tire, wherein the tread of the tire has a plurality of lugs arranged at intervals in the circumferential direction thereof. The tire for agricultural machinery, wherein the diameter of the tread end is smaller than the outer diameter of the tire by 12 to 20% of the tread width. 2. The surface contour shape of each lug in the widthwise cross section of the tire is compared with the radius of curvature in the central region of the tread,
The tire for agricultural machinery according to claim 1, wherein a radius of curvature in a side area outside the tire is small. 3. The step according to claim 1, wherein a step is provided near a boundary between the tread central area and an outer side area thereof so that a diameter difference from the tread central area is 1 to 5% of a tread width. Tires for agricultural machinery. 4. The tire for agricultural machinery according to claim 2, wherein the central region of the tread is a region of 40 to 60% of the tread width centered on the equator of the tire. 5. The radius of curvature in the central region of the tread is equal to or larger than the outer diameter of the tire, 2, 3 or 4.
The tire for agricultural machinery described in.