JP2003205709A - Tire for agricultural machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method in which the weight of a tire for agricultural machines, in particular, the weight of a lug can be reduced without any partial wear or any change in the rolling circumferential length. <P>SOLUTION: In the tire for agricultural machines in which a plurality of lugs extending in an inclined direction to the tire equator from the tire equator to the tread end side are disposed with intervals in the circumferential direction of the tread, the lug is extended from the tire equator to the tread end side via at least one folding part, and the width of parts except end parts on the tire equator side and folding parts is reduced. <P>COPYRIGHT: (C)2003,JPO

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 Tires mounted on agricultural machines such as tractors and rice transplanters are typically tires described in Patent Document 1 because traction when traveling in fields such as mud and wetlands is important. It is customary to have an exemplary rug pattern. That is, as shown in FIG. 1, generally, a lug pattern is formed in which lugs 2 having a relatively high height are arranged in an eight shape at intervals in the circumferential direction of a tread 1 of a tire.

In the tire for agricultural machinery having such a relatively large lug, when the weight is intended to be reduced in order to improve fuel efficiency, it is effective to reduce the weight of the lug which has a large specific gravity. Here, since the rug requires a certain height to obtain traction, it is a reasonable measure to reduce the width of the lug, but the lug rigidity becomes low and the tire rolls. It causes the disadvantage that the movement of the lag during movement becomes large. In other words, the rate of lag wear progresses faster,
The tire life is shortened, and partial wear of the lug progresses, causing uneven wear.

Further, when the lug rigidity becomes low, the rolling circumference per one rotation of the tire changes less than the original circumference of the tire when traveling on a pavement. This is because the rigidity of the lug becomes low and the lug collapses and deforms when traveling on a paved road. As described above, when the tires, in other words, the rolling circumference as designed is not achieved on the pavement, particularly when the tire is mounted on a four-wheel drive vehicle, the rolling circumference changes at the front and rear wheels. If it occurs, slip will occur in one of the tires, causing uneven wear and knocking.

In addition, as shown in FIG.
As shown in (1), the recess 3 may be provided mainly from the viewpoint of design, and the recess 3 is also effective for reducing the weight of the lug.
However, the recess 3 is usually provided in a similar shape to the contour shape of the end surface of the buttress portion of the lug, and since the recess 3 has an edging surrounding the recess 3, when the tire is used in a field, the recess 3, especially When traveling, mud easily adheres to the portion 3a on the back side of the rug, which causes a problem of being taken out of the field.

[0006]

[Patent Document 1] Japanese Patent Laid-Open No. 11-115417

[0007]

Therefore, the present invention is
It is an object of the present invention to propose a method for achieving weight reduction of tires for agricultural machines, particularly weight reduction of lugs without causing uneven wear or the above-mentioned change in rolling circumference.

[0008]

The gist of the present invention comprises:
It is as follows. (1) From the equator of the tire to the tread end side, a lug extending in a direction inclined with respect to the equator of the tire, a tire for agricultural machines in which a plurality of lugs are arranged at intervals in the circumferential direction of the tread,
At least 1 lug from the equator of the tire to the tread edge
A tire for an agricultural machine, characterized in that the tire extends through two bent portions and has a narrow width at the equator-side end of the tire and at the portion excluding the bent portions.

(2) In the above (1), a recess (agitation) is formed on the end face of the buttress portion of the lug, which extends from the end face to the kicking side of the lug and communicates with the lug groove on the kicking side. Part).

(3) In the above (1) or (2), the width of the portion of the lug adjacent to the equatorial end of the tire and the bent portion is 50 to 90 times the width at the end and the bent portion. % For agricultural machine tires.

(4) In the above (1), (2) or (3),
The opening width of the recess in the tire radial direction is 1.3 with the lug groove side as the starting side.
Agricultural machine tire characterized by up to 2.5 times.

(5) A tire for agricultural machinery according to any one of the above (1) to (4), characterized in that the starting end of the lug on the stepping side is located away from the equator of the tire.

(6) A tire for agricultural machinery according to any one of (1) to (5) above, wherein an end surface of the lug on the equatorial side of the tire has a direction intersecting the extending direction of the lug.

(7) In any one of the above items (1) to (4), the end portion of the lug on the equatorial side of the tire has a tip wall surface parallel to the rotation axis of the tire, and the tip wall surface is the tire. An agricultural machine tire characterized by being inclined at an angle of 25 to 45 ° with respect to a plane including the rotation axis of.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows a surface of a tire for agricultural machinery according to the present invention, in which a main portion of a tread is developed in a circumferential direction.
This tire for agricultural machinery has a plurality of lugs 4 arranged at intervals in the circumferential direction of the tread in each half of the tread with the tire equatorial plane O of the tread 1 as a boundary.

Each lug 4 extends from the tire equator O to the tread end E side in a direction inclined with respect to the tire equator O,
And at least 1 from the equator O of the tire to the side of the tread edge E
In the illustrated example, it extends through two bent portions 5a and 5b.

Further, at the lug 4, the equator O of the tire
The width of the portion excluding the end portion 4a and the bent portions 5a and 5b on the side is as shown by a dotted line in FIG.
It is important to narrow the width in comparison with a and 5b.

Here, when the lug height is the same, the lug rigidity and the lug width are basically in a proportional relationship, so that as shown in FIG. 4, the area of the dotted line portion reduces the lug rigidity. It is expected that. Then, the deformation (movement) of the lug during rolling of the tire, which affects the above-mentioned change in the rolling circumference.
Since the amount is inversely proportional to the lug rigidity, a decrease in lug rigidity due to a decrease in area leads to an increase in the amount of lug deformation, and in the worst case, a decrease in the tire performance.

However, the amount of deformation of this lug depends on the end 4a.
Since the lugs are greatly affected by the rigidity of the bent portions 5a and 5b, and the lug is continuous from the equator O of the tire to the tread end E, as shown in FIG. 3 or FIG. It has been newly found that the area of the lug 4 can be reduced without increasing the deformation amount of the lug if the portion where the width of the lug 4 is narrowed is the portion excluding the end 4a and the bent portions 5a and 5b. That is, according to the present invention,
By narrowing the width of the portion excluding the end portion 4a and the bent portions 5a and 5b, the amount of deformation of the entire lug can be suppressed to the same level as the conventional one, and the weight of the lug can be reduced.

The width of the narrow portion of the lug, specifically, the portion adjacent to the end 4a and the bent portions 5a and 5b of the lug 4 is the width of each of the end 4a and the bent portions 5a and 5b. Width of 50
It is preferably about 90%. That is, as shown in FIG. 3, the width a ₁ at the end 4a and the width b of the portion adjacent to the width a _1
1 and a ₁ : b ₁ = 100: 50 to 90 are satisfied, and similarly, the width a ₂ at the bent portion 5 a and the width b _{2 of} the portion adjacent thereto
A ₂ between: b ₂ = 100: 50 to 90 and a between the width a ₃ in the bent portion 5b and the width b ₃ of the portion adjacent thereto _3:
It is advantageous to satisfy b ₃ = 100: 50 to 90, respectively.

This is because the end portion 4a and the bent portion 5 are
The width of the adjacent parts in each part of a and 5b is
If it is less than 50%, it becomes difficult to secure the required rug rigidity, while if it exceeds 90%, it becomes difficult to reduce the weight and cost of the lug.

The term "width of the lug" used herein means that when the lug is divided with the bent portion as a boundary, the lugs extend in the extending directions L ₁ , L ₂ ,
It means the width in the direction orthogonal to L ₃ (see FIG. 4). Each width of the end portion 4a and the bent portions 5a and 5b is the maximum width in each portion, and the width of the portion adjacent to the one end portion and the bent portion is the minimum width in the adjacent portion. Here, the extending direction is based on the sides on the stepping side of the lug, for example, the sides 4c, 4d, and 4e in FIG. 4, in each section with the ends and the bent portions as boundaries, that is, with these sides. The parallel line is the extending direction. In addition, when the side of the reference lug on the stepping side is a curve, the line segment connecting the end portion and the bent portion is set as each side.

Next, in the tire for agricultural machinery of the present invention,
As shown in FIG. 5, the end surface 4 b of the buttress portion of the lug 4
In addition, a recess 7 is provided, which is widened from the inside of the end face to the kicking side of the lug 4 and communicates with the lug groove 6 on the kicking side. Thus, the tire may be provided with a design property.

That is, the buttress surface of the lug 4 that has entered the soil as the tire rolls receives the tangential force from the soil in the tire circumferential direction due to the rotation of the tire, so that the concave surface provided on the end surface 4b of the lug is depressed. If there is an edge as shown in FIG. 2, a vertical force is applied to the step portion (portion 3a in FIG. 2), which becomes a nucleus to which mud adheres.

On the other hand, in the recess 7 provided according to the present invention, as shown in FIG. 5, the end of the recess 7 is the lug groove 6.
Since there is no step portion in the related art described above, that is, there is no nucleus to which mud adheres, it is possible to avoid the adhesion of mud to the recess.

Here, regarding the opening width of the recess 7 in the tire radial direction, when the starting side is c and the lug groove 6 side is d, it is advantageous that d: 1.3 to 1.7 c. That is, when the opening width d on the lug groove 6 side is about the same as the opening width c on the starting point side, the tire radial direction force generated during tire rolling causes two sides in the tire circumferential direction of the recess (upper and lower sides in FIG. 5). The above vertical force is also applied to the edge (corresponding to the side), and as a result, it becomes a nucleus of mud adhesion. This phenomenon can be avoided by preventing a vertical force from being applied to the edges of the above two sides. For that purpose, it is recommended that d: 1.3 to 1.7 c.

Further, the starting end of the lug 4 on the stepping side, that is, the starting end 4s in FIG. 3 is located at a position separated from the equator O of the tire. It is advantageous in preventing the adhesion.

Further, the end of the lug 4 on the equator O side of the tire, that is, the end 4a on the stepping side has a direction intersecting with the extending direction of the lug, while maintaining the above-mentioned performance for preventing mud adhesion. , It is effective to secure the rigidity of the land portion near the end of the lug on the stepping side.

By the way, the end of the lug on the stepping side generally has a tip wall surface having a shape along the contour thereof. In the example shown in FIG. 3, the tip wall surface of the end 4a extends in the traveling direction. It has a protruding mountain shape. When traveling through a wetland or a field, at the end 4a having such a mountain-shaped tip wall surface, the soil is distributed by the portion protruding in the traveling direction of the mountain-shaped tip wall surface, and the soil escapes to both sides, Tires tend to sink slightly in the soil. Then, it was newly found that this sinking reduces the traction force of the agricultural machine tire.

That is, when the sinking amount of the tire increases, the amount of soil discharged accompanying the forward movement of the tire also increases and the running resistance increases, so that the traction force is substantially reduced.

Therefore, as shown in FIG. 7, at the step-side end 4a of the lug 4 shown in FIG. When it is advanced in the field, the soil is the end 4a.
Gives a structure that cannot escape on both sides of. That is, since the front end wall surface 8 parallel to the rotation axis of the tire is in direct contact with the ground in the traveling direction of the tire and contacts the ground, soil can be laid under the front end wall surface 8 and pressed. As a result of the rugs riding on this solidified soil, the above-mentioned sinking is avoided and improved traction is achieved.

The tip wall surface 8 parallel to the rotation axis of the tire must be provided so as to correspond to at least the leading edge portion on the stepping side of the end portion 4a as shown by the dotted line of the tip wall surface 8 in FIG. There is. Specifically, as shown in FIG. 7C, a boundary point P of the end portion 4a separated from the tire equator O (in the example of FIG. 7, an inflection point between the end portion 4a and its adjacent area). ), The width t of the tip wall surface 8 is preferably about 30 to 80% of the distance T from the point P to the equator O of the tire.

Of course, a tip wall surface 8 may be provided in parallel with the rotation axis of the tire over the entire area of the end portion 4a. For example, in the lug pattern shown in FIG. 8, the entire area of the end portion 4a is parallel to the rotation axis of the tire, and in this case, the tip wall surface 8 that is parallel to the rotation axis of the tire is provided over the entire area of the end portion 4a. As a result, it is possible to obtain the best effect for suppressing the depression by expanding the width.
Also in the example of FIG. 8, it is preferable that the width t of the tip wall surface 8 covers about 30 to 80% of the distance T from the point P to the equator O of the tire.

In addition, the vicinity of the end 4a on the stepping side is a portion where soil is likely to be clogged because the interval between the lugs is the narrowest. Become. 7 (b) and 8 (b) in providing the above-mentioned tip wall surface 8 here.
It is advantageous to improve the soil discharge property by setting the inclination angle α of the tip wall surface with respect to the surface including the rotation axis of the tire in the range of 25 to 45 °.

That is, the relationship between the inclination angle of the tip wall surface 8 with respect to the surface including the rotation axis of the tire, the traction force, and the amount of mud clogging near the tread center is shown in FIGS. 9 and 10, respectively. It can be seen that the inclination angle α should be in the range of 25 to 45 ° to satisfy the above condition. In addition,
Regarding the amount of mud clogging, excellent results have been obtained with an inclination angle α in the range of 40 to 50 °, but as the inclination angle α exceeds 45 ° and approaches horizontal, the edge effect due to lag is impaired. As a result, the total traction force decreases, so it is preferable that the angle is 45 ° or less. Further, considering the effect of weight reduction, it is advantageous that the inclination angle α is 30 ° or about 5 ° before and after the inclination angle α.

[0036]

EXAMPLE FIG. 1 (conventional example) According to the conditions shown in FIG. 3 (invention example 1), FIG. 7 (invention example 2) and FIG. 8 (invention example 3), the size is changed under various specifications shown below. Produced 9.5-24 tires for agricultural machinery for the rear wheels. In addition,
Other constructions were made according to the general practices for agricultural machine tires of that size.

[0037]

Each of the tires thus obtained was mounted on a standard rim, adjusted to the internal pressure and applied load shown in Table 1, and
The items were attached to the rear wheels of a 25-hp tractor or subjected to a drum test, and each item was evaluated according to the conditions shown in Table 1. For the front wheels, tires for agricultural machinery of size 6-14 were commonly used. The result is 100 for the conventional tire.
It is also shown in Table 1 by the index when.

[0039]

[Table 1]

[0040]

According to the present invention, it is possible to realize weight reduction without impairing the basic performance as a tire for agricultural machinery.

[Brief description of drawings]

FIG. 1 is a view showing a tread pattern of a conventional tire for agricultural machinery.

FIG. 2 is a perspective view showing a lug of a conventional agricultural machine tire.

FIG. 3 is a view showing a tread pattern of the tire for agricultural machinery of the present invention.

FIG. 4 is a view showing a tread pattern of the agricultural machine tire of the present invention.

FIG. 5 is a perspective view showing a lug of the agricultural machine tire of the present invention.

FIG. 6 is a diagram illustrating a method for evaluating uneven wear of a lug.

FIG. 7 is a view showing another tread pattern of the agricultural machine tire of the present invention.

FIG. 8 is a view showing another tread pattern of the agricultural machine tire of the present invention.

FIG. 9 is a diagram showing a relationship between an inclination angle of a tip wall surface with respect to a surface including a rotation axis of a tire and a traction force.

FIG. 10 is a diagram showing a relationship between an inclination angle of a tip wall surface with respect to a surface including a rotation axis of a tire and a mud clogging amount.

[Explanation of symbols]

1 tread 2 rugs 3 recess 4 rugs 4a end 4b end face 5a, 5b Bent section 6 lug groove 7 recess 8 Tip wall surface

Claims (7)

[Claims] 1. A tire for an agricultural machine in which a plurality of lugs extending from the equator of the tire toward the tread end side in a direction inclined with respect to the equator of the tire are arranged at intervals in the circumferential direction of the tread, wherein the lugs are Agriculture extending from the equator of the tire to the end of the tread through at least one bend, and narrowing the width of the tire excluding the end on the equator and the bend Machine tire. 2. The recess according to claim 1, wherein the end surface of the buttress portion of the lug has a recess that extends from the inside of the end surface to the kicking side of the lug and communicates with the lug groove on the kicking side. A characteristic tire for agricultural machinery. 3. The tire according to claim 1 or 2, wherein the width of the portion of the lug adjacent to the equator side end of the tire and the bent portion is
Agricultural machine tire characterized by having a width of 50 to 90% at the end and the bent portion. 4. The tire radial direction opening width of the recess according to claim 1, 2 or 3, wherein the lug groove side is the starting side of 1.3 to 2.5.
A tire for agricultural machinery characterized by being doubled. 5. The method according to any one of claims 1 to 4,
A tire for agricultural machinery, characterized in that the leading end of the lug on the stepping side is located away from the equator of the tire. 6. The method according to any one of claims 1 to 5,
The tire for agricultural machinery is characterized in that the end surface of the lug tire on the equator side has a direction intersecting with the extending direction of the rug. 7. The method according to any one of claims 1 to 4,
The end of the lug on the equatorial side of the tire has a tip wall surface parallel to the rotation axis of the tire, and the tip wall surface is inclined at an angle of 25 to 45 ° with respect to the plane including the rotation axis of the tire. A tire for agricultural machinery, which is characterized by