JP2009280086A - Lug tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lug tire can improve vibration ride comfort performance especially during traveling on a good road without degrading traction performance. <P>SOLUTION: A plurality of thin grooves 18 extending in a tire circumference direction are formed on a tread of a lug 14 in a tire width direction to reduce rigidity of the tread part of the lug 14, and to buffer rolling vibration during driving on a good road, thus improving vibration ride comfort performance. The vibration ride comfort performance can be improved without changing the shape of the lug 14, therefore, the original performance of the lug, that is the traction performance on a rough road, such as a field is not degraded. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lag tire having a plurality of lugs in a tread, and more particularly, to a lag tire having improved vibration ride comfort performance without reducing traction performance.

Conventionally, in agricultural machinery tires in which a plurality of lugs are formed in the shape of a square with a predetermined interval on the tread, the tread width is set as wide as possible to ensure the traction performance, which is the most basic performance. For example, it has been generally performed to set the tread width wider than the total tire width.
In such conventional agricultural machine tires, the traction performance and the vibration ride performance are basically in a trade-off relationship, and the vibration ride comfort must be sacrificed to ensure the predetermined traction performance. There was a problem.

Accordingly, various methods for improving the vibration ride comfort performance of such agricultural machine tires have been proposed and realized (for example, Patent Document 1 and Patent Document 2).
For example, as a technique for improving the vibration ride comfort performance, it is known to form each lug so as to overlap with other lugs in the tire circumferential direction or the tire width direction.
JP 2006-224784 A JP 2004-299459 A

  By the way, in recent years, there are increasing opportunities for vehicles equipped with agricultural machinery tires to travel on good roads such as paved roads, so that the vibration riding comfort performance of agricultural machinery tires, which has not been noticed so much in the past, is attracting attention. It has become. As described above, methods for improving the vibration riding comfort performance of agricultural machinery tires have been proposed and realized. However, with these methods, the vibration riding comfort performance, which is in a trade-off relationship with traction performance, is achieved to a level that satisfies the user. There was a problem that it could not be improved.

  In recent years, agricultural machinery tires have been provided that improve the ride comfort of the vibration without substantially reducing the traction performance by making the total width of the tire and the tread width substantially the same. In the market, it has been strongly desired to provide tires for agricultural machinery with further improved vibration ride performance.

  In view of the above-described facts, the present invention has an object to provide a lag tire having improved vibration ride comfort performance, particularly vibration ride comfort performance when traveling on a good road, without reducing traction performance.

  In the lag tire according to claim 1, a plurality of narrow grooves extending in the tire circumferential direction are formed in the tire width direction on the tread surface of the lug provided in the tread.

Next, the operation of the lag tire according to claim 1 will be described.
Generally, in the lag tire, 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 increased, the load center acting point applied to the lugs that are distributed to the left and right of the tread surface during running shifts greatly between the left and right lugs alternately in the tread width direction. This is mainly due to the increased roll.
Although it is preferable that the tread width is as narrow as possible from the aspect of good road vibration, the tread width cannot be extremely reduced because of a contradictory relationship with the traction property.

  In the lag tire according to claim 1, a plurality of narrow grooves extending in the tire circumferential direction are formed on the tread surface of the lug provided in the tread in the tire width direction, thereby reducing the rigidity of the tread surface portion of the lug and traveling on a good road. The running vibration at the time, especially the rolling vibration can be buffered, and thereby the ride performance can be improved.

  Further, in the lag tire according to the first aspect, the vibration ride comfort performance can be improved without changing the shape of the lug, so that the original performance of the lag, that is, the traction performance on a bad road such as a farm field is not deteriorated.

  According to a second aspect of the present invention, in the lag tire according to the first aspect, the diameter at the tread end is smaller than the outer diameter of the tire within a range of 12 to 20% of the tread width.

Next, the operation of the lag tire according to claim 2 will be described.
In the cross section of the tire in the width direction, the lug has a diameter at the tread end that is smaller by 12 to 20% of the tread width than the outer diameter of the tire (diameter at the tire equatorial plane), in other words, the outer diameter of the tire. It is preferable that the drop height of the tread end with respect to the central area of the tread, which is caused by the above difference between the diameter of the tread and the tread end, is 6 to 10% of the tread width.

  In order to further improve the vibration ride comfort, it is necessary to regulate the drop height of the tread edge. That is, if the drop height is 6% or more of the tread width of each lug, the contact pressure when the lug contacts the ground, that is, the surface pressure near the tread end is reduced, and the ground contact width of the lug is substantially reduced. Therefore, the load center when each lug contacts the ground is shifted to the tread width center side. Then, since the phenomenon that the point of action of the load center described above is largely shifted in the tread width direction alternately between the left and right lugs is suppressed, the roll is also effectively suppressed.

When the falling height is less than 6% of the tread width, the vibration ride comfort cannot be further improved. When the drop height is 6% or more of the tread width, the adverse effect on the traction property is in a negligible range.
On the other hand, if the falling height exceeds 10% of the tread width, the surface area of the lug involved in the traction force of the tire is reduced, and the traction force is significantly reduced. For example, when used for agricultural work, paddy fields and upland fields Will interfere with the cultivation work.

  According to a third aspect of the present invention, in the lug tire according to the second aspect, the contour of the tread surface of the lug in the cross section in the tire width direction is set such that the curvature radius on the tread end side is smaller than the curvature radius on the tread center side. Has been.

Next, the operation of the lag tire according to claim 3 will be described.
Compared to the outer diameter of the tire (the diameter at the tire equator) by setting the tread contour shape of the lug in the tire width direction cross section to be smaller at the curvature radius at the tread end side than the curvature radius at the tread center side Thus, the tread end diameter can be reduced. Therefore, as in the lag tire of claim 2, in order to set the fall height to 6 to 10% of the tread width, the tread surface contour of each lug in the cross section in the width direction of the tire is compared with the radius of curvature at the center side of the tread. Thus, it is advantageous that the radius of curvature at the tread end side is reduced.

  According to a fourth aspect of the present invention, in the lug tire according to the third aspect, the tread surface contour shape of the lug in the cross section in the tire width direction is set such that the radius of curvature on the tread center side is equal to or greater than the outer diameter of the tire. ing.

Next, the operation of the lag tire according to claim 4 will be described.
In the tread contour shape of the lug in the cross section in the tire width direction, the tread center pressure distribution on the tread center side can be made uniform by setting the curvature radius on the tread center side to be equal to or greater than the outer diameter of the tire.

  According to a fifth aspect of the present invention, in the lag tire according to any one of the first to fourth aspects, the narrow groove extends over a region of 70% or more in the tire width direction in the tread surface of the lug. Is formed.

Next, the operation of the lag tire according to claim 5 will be described.
By forming the narrow groove in a region of 70% or more of the tread surface of the lug in the tire width direction, it is possible to sufficiently buffer the rolling vibration during driving on a good road.

The groove width of the narrow groove is preferably set to 1.5 mm or less.
Moreover, it is preferable to set the groove depth dimension of a narrow groove in the range of 10 to 30% of the height dimension of the lug measured on a tire equatorial plane.
Moreover, it is preferable to set the arrangement | positioning space | interval of a narrow groove in the range of 5-20 mm.

  Since the lag tire of the present invention has the above-described configuration, it is possible to improve the vibration ride comfort performance, particularly the vibration ride comfort performance when traveling on a good road, without reducing the traction performance.

Below, the lag tire 10 which concerns on one Embodiment of this invention is demonstrated according to FIG. 1 thru | or FIG. Note that the lag tire 10 of the present embodiment is a pneumatic tire for agricultural machinery for agricultural vehicles (for example, agricultural tractors, etc.), and the internal structure other than the tread 12 to be described later is a general bias structure, so the description is omitted. Omitted.
As shown in FIG. 1, the tread 12 of the lug tire 10 of the present embodiment has a plurality of protruding lugs 14 that extend obliquely from the center side in the tire width direction toward the outer side with respect to the tire axial direction. .
The lugs 14 are formed at predetermined intervals in the tire circumferential direction alternately on the left and right sides of the tire equatorial plane CL.
Note that the recesses of the tread 12 other than the lugs 14 are referred to as lug grooves 16.

As shown in FIG. 2, the tread surface of the tread 12 of the present embodiment has an end portion on the outer side in the tire width direction on the tire equatorial plane CL, that is, the tread end 12E on the inner side in the tire radial direction. The groove depth of the lug groove 16 of the tread 12 increases from the tire equatorial plane CL toward the tread end 12E.
The tread 12 of the present embodiment is arranged in a central area 12C straddling the tire equatorial plane CL, and continuously disposed in the central area 12C on both sides of the central area 12C in the tire width direction, and the curvature of the tread when viewed in the tire width direction cross section. The side area 12S is different from the central area 12C in radius.

In the present embodiment, since the outer end portion of the tread surface of the lug 14 is square in the tire width direction cross section, the tire width between the tread end 12E on the left side in the tire width direction and the tread end on the right side in the tire width direction (not shown in FIG. 2). It is assumed that the distance along the direction indicates the tread width TW.
For example, as shown in FIG. 3, when the outer end portion of the tread surface of the lug 14 is not square in the tire width direction cross section (for example, an arc shape), the tread surface (curvature radius R2 portion) of the left lug 14 is extended. A first intersection P1 of a line (two-dot chain line) and an extension line (two-dot chain line) of the lug outer wall of the left lug 14, and an extension line of the tread surface of the right lug 14 and a right lug (not shown) The distance along the tire width direction with the second intersection with the extension line of the outer side wall indicates the tread width TW.

  Here, the central area 12C of the tread 12 preferably satisfies the range of 40 to 60% of the tread width TW with the tire equatorial plane CL as the center. In addition, as shown in FIG. 2, the range of the center area 12C of the tread 12 is measured along the tire width direction.

Further, when the curvature radius of the tread surface of the tread 12 in the tire width direction cross section is viewed, it is preferable to set the second curvature radius R2 of the side section 12S smaller than the first curvature radius R1 of the central section 12C. In the present embodiment, the second curvature radius R2 of the side section 12S is set smaller than the first curvature radius R1 of the central section 12C.
Further, the first radius of curvature R1 is preferably set equal to the tire radius indicated at H _C or above, and more preferably be set to more than double in the tire radial H _C. In the present embodiment, the first radius of curvature R1 is set to be infinite, that is, a straight line.

Furthermore, in the Ragutaiya 10, it is preferable to set a small diameter _{H E} at the tread end 12E to the outer diameter of the tire (2 × _{H C)} in the range 12 to 20% of the tread width TW. In other words, when the distance in the tire radial direction between the outer end portion of the tread 12 on the outer side in the tire width direction of the lug 14 and the point on the tire equatorial plane CL of the tread 12 which is the maximum diameter of the tire is set to the height H1. The falling height H1 is preferably set to be 6 to 10% of the tread width TW.

A plurality of narrow grooves 18 extending in the tire circumferential direction are formed on the tread surface of the lug 14 in the tire width direction.
The groove width of the narrow groove 18 is preferably set to 1.5 mm or less (a cut having no groove width may be used), and the groove depth dimension d of the narrow groove 18 is the lug 14 measured on the tire equatorial plane CL. The height (= lag groove depth) of the dimension D is preferably set within a range of 10 to 30%, and the arrangement interval P of the narrow grooves 18 is preferably set within a range of 5 to 20 mm.

  The narrow groove 18 is preferably formed over a region of 70% or more of the tread surface of the lug 14 in the tire width direction. In the present embodiment, the narrow groove 18 is formed over the entire tread surface of the lug 14.

(Function)
According to the lag tire 10 of the present embodiment, since a plurality of narrow grooves 18 extending in the tire circumferential direction are formed in the tire width direction on the tread surface of the lug 14, the rigidity of the tread surface portion decreases, and the roll vibration during running on a good road Is buffered, which improves ride comfort performance. Moreover, in this lag tire 10, since the vibration riding comfort performance can be improved without changing the shape of the lug 14, the traction performance on a bad road such as a farm field is not deteriorated.

Further, the lag tire 10 has a diameter H _E at the tread end 12E smaller than the outer diameter (2 × H _C ) of the tire within a range of 12 to 20% of the tread width TW, that is, a drop height H1. However, by setting it within the range of 6 to 10% of the tread width TW, it is possible to further improve the vibration ride comfort without reducing the traction force. Note that if the drop height H1 is less than 6% of the tread width TW, it is impossible to further improve the vibration ride comfort performance. On the other hand, when the drop height H1 exceeds 10% of the tread width TW, the traction force is remarkably reduced, which may hinder the cultivation work of paddy fields and upland fields.

In tread contour shape of the lug 14 in the tire width direction cross-section, the curvature radius R1 in the central zone 12C by equal to or greater than the outer diameter of the tire (2 × H _C), the tread pressure distribution in the central zone 12C It can be made uniform.

  In the present embodiment, the narrow groove 18 is formed on the entire tread surface of the lug 14, but may not be formed on the entire tread surface. However, in order to sufficiently buffer the rolling vibration during traveling on a good road, it is preferable to form the region in a region of 70% or more in the tire width direction.

  In addition, when the groove width of the narrow groove 18 exceeds 1.5 mm, a problem that mud is clogged in the narrow groove 18 becomes obvious and there is a possibility that the buffering effect may be lost. In addition, there is a strong adverse effect on the wear life, and there is a possibility that practicality cannot be secured.

  If the groove depth dimension d of the narrow groove 18 is less than 10% of the height dimension (lag groove depth dimension) D of the lug 14 measured on the tire equatorial plane CL, the vibration reduction effect due to buffering is not sufficient. . On the other hand, if the groove depth dimension d of the narrow groove 18 exceeds 30% of the height dimension D of the lug 14 measured on the tire equatorial plane CL, there is a risk that adverse effects on wear life and durability due to insufficient rigidity cannot be ignored. There is.

  Further, if the arrangement interval P of the narrow grooves 18 is less than 5 mm, there is a possibility that the adverse effect on the wear life and durability due to insufficient rigidity cannot be ignored. If the arrangement interval P of the fine grooves 18 exceeds 20 mm, vibration due to buffering may occur. The reduction effect is not sufficient.

  If the range of the central area 12C is less than 40% of the tread width TW, the flat part (or a part close to the flat) seen in the cross section in the tire width direction is reduced, leading to a reduction in the lug projection area contributing to the traction and the traction property. If the range of the central area 12C exceeds 60% of the tread width TW, the flat portion (or a portion close to the flat) increases, so the lag projection area increases and the traction improves. Since the drop height H1 from the road surface in the partial area 12S decreases, the LFV deteriorates and the vibration ride comfort performance deteriorates. Therefore, it is preferable that the central area 40 of the tread 22 satisfies a range of 40 to 60% of the tread width TW.

In the above embodiment, the narrow groove 18 extends along the tire circumferential direction, but may be inclined with respect to the tire circumferential direction as long as it is within 30 ° with respect to the tire circumferential direction. When the inclination angle of the narrow groove 18 with respect to the tire circumferential direction exceeds 30 °, the buffering effect against the rolling vibration cannot be sufficiently exhibited.
In the above-described embodiment, the internal structure of the lag tire 10 is configured as a bias structure. However, the present invention is not limited to this configuration, and may be configured as a radial structure or a solid structure.

(Test example)
In order to confirm the performance improvement effect of the present invention, one type of tire of a conventional example and one type of tire of an example to which the present invention was applied were prepared, and vibration measurement by a measuring instrument and vibration ride performance were evaluated. . The purpose of the test is to evaluate whether the vibration ride performance has been improved.

  Next, the test tire will be described. All of the test tire sizes are AGS 13.6-26 4PR T13H tires, and each test tire is assembled on a standard rim specified in JATMA YEAR BOOK (2008 edition, Japan Automobile Tire Association Standard). Used for testing. Table 1 shows the specifications of the test tire.

  In a test related to comparative evaluation, vibration (amplitude level) was measured using a measuring instrument. Furthermore, these test tires were mounted on agricultural vehicles and one person was on board, and the passengers evaluated the feeling. The test conditions for comparative evaluation are as follows.

<Vibration ride performance actual vehicle test>
Traveling road type: Concrete paved road Traveling speed: 16km / h (straight running)
Agricultural vehicle type: agricultural tractor (41 hp)

The evaluation value of the vibration measurement is shown in Table 1 as an index display with the vibration level (amplitude) of the conventional example as 100. Moreover, it is assumed that the smaller the evaluation value, the better the result. As shown in Table 1, in the measurement of the vibration level (amplitude) using a measuring instrument, the vibration level of the example is greatly reduced.
Furthermore, it was confirmed that the vibration level (amplitude) of the example was lowered to a level that does not cause a problem even in the feeling evaluation by the occupant.

It is a top view which shows the tread pattern of the lag tire which concerns on one Embodiment of this invention. It is sectional drawing along the tire rotating shaft of the lag tire shown in FIG. It is a tire width direction sectional view of a lug.

Explanation of symbols

10 Lag tires 14 Lugs 18 Narrow grooves

Claims (5)

  A lag tire in which a plurality of narrow grooves extending in the tire circumferential direction are formed in a tire width direction on a tread surface of a lug provided in a tread.   The lag tire according to claim 1, wherein a diameter at a tread end is made smaller within a range of 12 to 20% of a tread width with respect to an outer diameter of the tire.   The lug tire according to claim 2, wherein the tread contour shape of the lug in the cross section in the tire width direction is set such that the curvature radius on the tread end side is smaller than the curvature radius on the tread center side.   The lug tire according to claim 3, wherein the tread contour shape of the lug in the cross section in the tire width direction is set such that the radius of curvature on the center side of the tread is equal to or greater than the outer diameter of the tire.   The lag tire according to any one of claims 1 to 4, wherein the narrow groove is formed over a region of 70% or more of the tread surface of the lug in the tire width direction.

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