JP4540102B2 - Heavy duty pneumatic tire - Google Patents

Description

The present invention relates to a heavy duty pneumatic tire used for trucks and the like, and more particularly to a shelf provided in a main groove of the tire.

Heavy load pneumatic tires used for trucks and the like are gradually worn out by use, and as a result, the groove depth becomes shallower. Therefore, tire performance such as slip prevention gradually declines from the initial performance. When the wear progresses more than a certain level, the tire is replaced. Marks for replacement of tires include JATMA TWI (tread wear indicator) indication provided at the position of the remaining groove of 1.6 mm, and a groove depth of 50 as a mark of the tire for running on snow and icy roads. % Platform.

However, the TWI display shows the minimum groove depth necessary to maintain safety, and tires worn so far often have cut flaws up to the belt position. It is uneconomical. The platform is a mark for a so-called studless tire, and has no meaning as a mark other than the tire. Therefore, a new display that informs when it is possible to regenerate the heavy-duty pneumatic tire is required.

In providing a new display, it should not be confused with a TWI display or platform. In this respect, as a method of knowing wear by a method other than the method of providing a protrusion on the groove bottom such as TWI display or a platform, there is a method based on the degree of wear of the buttress portion. However, since the degree of wear of the buttress portion and the remaining groove depth are not necessarily in a proportional relationship, it has not been a sufficient judgment criterion as a mark for whether or not it can be used as a recycled tire. Therefore, the mark for the recycled tire must be a means for directly knowing the remaining groove bottom depth.

Here, as a method of notifying the degree of tire wear on the basis of the groove bottom without being confused with the TWI display or the platform display, a method of providing a colored protrusion in the tire groove (Patent Document 1) or a tire drain groove A coloring method (Patent Document 2) has been proposed. However, since the tire uses carbon black as a raw material, a method of coloring a part of the tire is not realistic.
Utility Model Registration No. 3067056 JP-A-8-258517

An object of the present invention is to provide a mark for tire wear so as not to be confused with a TWI display or a platform, etc., at a right position that can be used as a reclaimed tire by recapping. It is not to be lowered.

  As a result of intensive studies, the present inventor has provided a shelf that touches only one side surface of the land portion at the bottom of the main groove, or each side surface contacts the land portion facing the main groove. A mark of a regenerated tire in which a shelf composed of two paired shelves is provided on the bottom of the main groove, and the height of the shelf is 2.5 to 3.5 mm from the bottom of the main groove. The above-mentioned problems have been solved with the main means being to achieve the optimum height.

The heavy-duty pneumatic tire of the present invention has a shelf height of 2.5 to 3.5 mm from the bottom of the main groove, and is therefore optimal as a mark for a recycled tire by recapping.

The heavy duty pneumatic tire of the present invention is
Whether the side surface of the shelf part or the side surface of the one shelf part is in contact with only one side wall of the land part,
Or when the land part is composed of two paired shelf parts,
The side surface of the one shelf portion is in contact with only one side wall of the land portion,
Since the side surface of the other one shelf part is composed of two one shelf parts facing only the side wall of the other land part facing the side wall of the land part where the one one shelf part contacts . It is not confused with TWI display or platform display. Further, as a secondary effect, it can contribute to the uneven wear prevention performance of the tire.

Further, the heavy-duty pneumatic tire of the present invention has a preferable number of 1 to 12 shelves per main groove, so that even in the case where shelves are provided, particularly in the middle wear stage to the last wear stage. The tire drainage performance can be maintained.

Furthermore, in the heavy duty pneumatic tire of the present invention, even if only the center or shoulder of the tread progresses in wear , the shelf is provided at the bottom of the main groove of either the center groove or the shoulder groove. It can be a mark as a recycled tire.

Furthermore, when the heavy-duty pneumatic tire of the present invention is composed of two single shelves in which the shelves are paired, the shape of one single shelves constituting the shelves is the other single shelves. By making it a preferable mode of any shape among the rotational shape of the part shape, the specular shape, the fitting shape, or the similar shape of any of the above shapes, the visibility as a mark is increased, and the design property Also excellent.

Hereinafter, an embodiment of a heavy duty pneumatic tire according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the mode shown in the drawings. FIG. 1 is a plan view of a tire tread surface provided with a shelf according to the present invention. FIG. 2 is a plan view of a tire tread surface provided with a shelf according to another embodiment of the present invention. 3 is an AA end view of the shelf 3 indicated by a dashed line between AA in FIG.

The heavy duty pneumatic tire of the present invention has at least a main groove 1 continuous in the tire circumferential direction carved in a tread and a land portion 2 partitioned by the main groove 1. It is a concept of existing at a relatively high position in relation to the groove, and specifically includes patterns such as ribs, ribs / lags, blocks, and the like. Although there are various tire grooves, the main groove 1 referred to in the present invention is used in a commonly used meaning, and specifically, in the tire circumferential direction among the grooves carved in the tread. It means something that is continuous. In a tire with a pattern in which the main groove 1 is carved, only one main groove 1 is rarely carved, and there are usually a plurality of main grooves 1.

In the present invention, a shelf 3 extending upward from the bottom of the main groove 1 is provided for marking the recycled tire by recapping. The number of the main grooves 1 provided with the shelf 3 may be one or plural. Providing the shelves 3 in the plurality of main grooves 1 is preferable because the degree of wear at each place can be known even when the degree of wear differs from place to place.

In particular, since the difference in the degree of wear is generally severe in the center which is the center and the shoulder which is the end, the shelf 3 is provided at the bottom of the main groove 1 of the center groove and the shoulder groove among the main grooves 1. It is preferable that it is provided. In this case, the appropriate replacement period is when the wear reaches the mark of the shelf 3 provided in any of the main grooves.

  The shelf 3 is a so-called protrusion that extends upward from the bottom of the main groove 1. The shelf 3 can be configured with a single protrusion, but the two protrusions can also be configured as a pair. In this case, each protrusion is referred to as a single shelf 4, 4 'in the present invention. As a method of providing the shelf portion 3, it is simple and efficient to provide the shelf portion 3 with a mold at the time of tire molding as one of the tire patterns, instead of providing the shelf portion 3 with an adhesive or the like after manufacturing the tire. In addition, since the shelf 3 is not cut off in the middle, it is excellent in terms of performance.

  In the case where the shelf portion 3 is configured by itself, the side surface of the shelf portion 3 is either one of the side walls of the land portion 2 facing both sides of the main groove 1 and one of the land portions 2. Only the side wall is in contact with the side surface. When the shelf 3 is composed of two paired shelves 3, the side surface of the one shelf 4 is in contact with only one side wall of the land 2 and the other The side surface of the one shelf part 4 ′ is in contact with only the side surface of the land part 2 facing the side wall of the land part 2 with which the one piece shelf part 4 is in contact. By doing in this way, it is because it can distinguish clearly from the TWI display which touches the land part 2 both side wall, and the platform display which is distant from the land part 2 both side wall.

  Here, the fact that the side surface of the shelf 3 contacts only the side wall of one land portion 2 does not mean that there is no contact with the other land portion side wall in any manner. For example, as shown in FIG. 3, when the groove bottom has a round shape, the side surface and the bottom surface of the groove portion are continuously formed, and the boundary is not necessarily clear. For this reason, there is a possibility that the determination of what range is the side and what range is the bottom is different for each person. In this regard, in the present invention, for example, even in the form of the shelf portion 3 in FIG. 3, only the bottom portion and one side wall may be in contact. This is because the main reason why the side surface of the shelf 3 is in contact with only one land portion 2 in the present invention is that it may be confused with the TWI display if it contacts both. is there. Considering such an effect, the judgment of whether or not the side surface of the shelf 3 is in contact with the side wall of the land 2 is based on the recognition of the general public when the tire tread is viewed from the outside particularly in a new state. It can be said that it should be judged based on whether or not the land portion 3 is confused with the TWI display, that is, whether or not the land portion 3 appears to be in contact with the opposite land portion side surface. In the case of FIG. 3, when the shelf 3 is viewed from the tread surface of the tire, it can be said that the TWI display is not confused, and it is determined that it is in contact with only one land side wall.

When the shelves 3 are alternately in contact with the opposite side walls of the land 2, the shelves 3 are considered to be composed of two paired one shelves 4, 4 ′, or the single shelves 3. However, in the present invention, the shelf portion 3 is composed of the single shelf portions 4 and 4 'facing each other.

  The maximum length position in the tire width direction of the shelf part 3 and the single shelf parts 4 and 4 ′ in the present invention (for example, the apex position in the case of the triangular shelf part 3) and the land facing The shortest distance from the part is preferably 1.0 mm or more, and preferably 3.0 mm or less. This is because if the distance is too narrow, it seems to be in contact with the side walls of both land portions 2 at first glance, which may be confused with the TWI display. On the other hand, the fact that this distance is too wide is because the tire width length of the shelf 3 is small, so that it may not be noticeable as a mark.

The height of the shelf 3 is 2.5 to 3.5 mm from the bottom of the main groove 1. This is because it is optimal as an indication of when it can be replaced as a recycled tire by recapping. That is, if the height is too high, it is still uneconomical because it can be used as a mark by the shelf 3, and if it is too low, the possibility of reproduction is reduced. Furthermore, because the side surface of the shelf portion 3 having such a height is in contact with the side wall of the land portion 2, a secondary effect that the uneven wear resistance of the tire is improved can be obtained. In the end view of FIG. 3, the height measurement position of the shelf 3 is indicated by h. That the height of the shelf 3 is 2.5 to 3.5 mm from the bottom of the main groove 1 means that h in FIG. 3 is 2.5 to 3.5 mm.

Since the shelf part 3 in the present invention can contribute to the improvement of uneven wear resistance of the tire, an attachment method capable of maximizing the effect can be adopted. Specifically, if the center portion and the shoulder portion are compared, uneven wear is more likely to occur in the shoulder portion. Therefore, when the shelf 3 is provided in the shoulder groove that divides the land portion 2 on the shoulder side, the shelf portion 3 that is in contact with only the side wall of the land portion 2 on the shoulder outer peripheral side is provided to improve uneven wear resistance. it can.

The circumferential width of the shelf 3 and the single shelves 4, 4 ′ is preferably 5 to 20 mm. If the width of the shelf 3 or the single shelf 4 or 4 'is too wide, not only may the tire drainage be affected, but the appearance may be inferior. Because there is. On the other hand, if the width is too narrow, it becomes inconspicuous, so that not only the value as a mark is lowered, but also the uneven wear resistance characteristic obtained by the present invention is not exhibited.

As for the number of shelves 3 provided per one main groove 1, it is preferable to provide a large number of shelves 3 because it is possible to see the shelves 3 without moving the tires regardless of the position of the tires. This may affect the drainage of the tire. Therefore, considering the balance between the two, the preferred number of shelves 3 in the present invention is 1 to 12 per main groove 1. However, in the case of the shelf 3 composed of the two single shelves 4, 4 ' facing each other , 1 to 12, that is, 2 to 24 in terms of the number of the single shelves 4, 4' is a preferable range. And

  When there are a plurality (2 to 12) of the shelf portions 3 in one main groove 1, it is preferable that the distance in the main groove direction from one shelf portion 3 to the adjacent shelf portion 3 is equal. That is, it is preferable that the shelves 3 are installed at equal intervals in the circumferential direction of the main groove. This is because, in order to maintain the tire drainage, it is preferable that the length of the partition portion of the main groove 1 sandwiched between the shelves 3 is as long as possible in any portion. That is, when the distance from the shelf 3 to the adjacent shelf 3 is long, it becomes easy to provide a lateral groove or the like for draining water existing in the partition part in the partition part of the main groove sandwiched between the shelf parts 3. This is because even if the shelf 3 is present, the drainage performance of the tire is not lowered. From such a viewpoint of ensuring drainage, the tread of the tire of the present invention is such that at least one or more lateral grooves connected to the partition portions are provided in the partition portions of all the main grooves 1. Is preferred.

  In addition, in the case where the shelf part 3 is composed of two paired shelf parts 4 and 4 ′, the preferred range is 2 to 24 when viewed from the one shelf part, while the shelf part 3 is independent. It seems that it is seemingly unbalanced that the preferred number when present is 1-12. However, as described above, the drainage performance of the tire is more affected by the length of the partition portion of the main groove 1 sandwiched between the shelves 3 than the number of the shelves 3 or the single shelves 4 and 4 ′. Is.

  There are no particular restrictions on the shape of the shelf 3 or the single shelf 4. If it is a simple shape, it has the advantage that manufacture with a metal mold | die is easy. On the other hand, since it is conspicuous if it is a complicated shape, there is an advantage that the mark effect is large. Examples of specific shapes include triangles, quadrilateral polygons, L-shapes such as those shown in FIGS. 1 and 2, or shapes that are half of these, and shapes that are half arrow shapes In addition, examples include, but are not limited to, a semicircular shape, a shape with a motif such as a star shape or a flower shape. As shown in FIGS. 1 and 2, the shape of the shelf 3 need not be the same. Since the shelf 3 as a mark also affects the design of the tire, the shape has many subjective factors, and a shape with excellent aesthetics can be selected as appropriate. Among them, a shape that is inexpensive because it is easy to manufacture a mold and that is sufficiently conspicuous as a mark, such as a triangular shape, a quadrangular shape, a shape in which an arrow shape is halved, and a shape that makes a pair with a side wall shape of an opposite land portion are preferable . Furthermore, the shape of the alphabet font is preferable because it can have the meaning as an initial letter or abbreviated letter such as trademark meaning or symbolic meaning.

  Moreover, in the case of the shelf part 3 comprised from two paired one shelf parts 4 and 4 ', the shape of one piece shelf part 4 is the rotation shape of the shape of the other piece shelf part 4', and a mirror body shape. It is preferable that the shape is any of a fitting shape or a similar shape of any one of the above shapes. By adopting such a shape, the unity of the two single shelf parts 4 and 4 ′ is produced, so that it is conspicuous as a mark and generally excellent in aesthetic appearance. In the shelf 3 composed of the two single shelves 4 and 4 ′ shown in FIGS. 1 and 2, one single shelf 4 is the same size as the other single shelf 4 ′ with a 180-degree rotation shape. The example in the case of this shape is shown.

(Verification of the appropriate height of the shelf)
In order to obtain a recycled tire by recapping, the height of the shelf portion was verified to be preferable. The verification experiment was conducted in the actual running test. The conditions for the tires used were as follows.
Tire size: 11R22.5
Rim size: 22.5 "X8.25"
Air pressure: 700KPa
Test vehicle: 2-D truck vehicle Shelf mounting position: Front wheel (steering wheel)
Shelf shape: triangular shape shown in FIGS. 2 and 3 Shelf circumferential width: 5.0 mm
Load: 100% (JATMA specified load)
Road surface condition: 100% paved Traveling speed: 50-80km / h

  When the height of the shelf is 1.0, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0 (mm) under the above conditions, the vehicle runs until it reaches the shelf. The mileage, durability and renewability were confirmed. The results are shown in Table 1.

  Here, renewability means the reproducibility of the tire. Generally, whether or not a tire can be regenerated is determined by whether or not the belt is damaged. Therefore, a case where there is no damage to the belt is indicated as ◯, and a case where separation from the belt is observed is indicated as △ Therefore, the case where cut flaws reaching the belt are seen was marked as x.

  From the verification of Example 1, as the shelf becomes lower, the travel distance to reach the shelf becomes naturally longer. However, the separation amount of the belt becomes larger, the durability is lowered, and the renewability is also deteriorated. From this verification, it can be seen that the shelf height should be 2.5 to 3.5 mm in order to earn as much travel distance as possible and ensure durability and renewability.

(Verification of the number of shelves and tire drainage)
An experiment was conducted to check whether drainage (ease of draining rainwater during running) was hindered by setting multiple shelves. The verification experiment was conducted in the actual running test. The conditions of the used tire etc. are as follows.
Tire size: 11R22.5
Rim size: 22.5 "X8.25"
Air pressure: 700KPa
Test vehicle: 2-D truck vehicle Shelf mounting position: Front wheel (steering wheel)
Shelf shape: triangular shape shown in FIGS. 2 and 3 Shelf circumferential width: 5.0 mm
Load: 100% (JATMA specified load)
Road surface condition: 100% paved Traveling speed: 50-80km / h

  Confirm wetness (drainage) at the middle stage (remaining groove: 50%) and end stage (remaining groove: 25%) when the number of shelves is 6, 12, 18, 24 under the above conditions. did. The results are shown in Table 2.

  From Table 2, it can be seen that the number of shelves is preferably 12 or less in order not to impede drainage in the middle and final stages of wear.

(Verification of shelf height and uneven wear resistance)
A confirmation experiment was conducted on the effect of the height of the shelf on the uneven wear resistance of the tire. The verification experiment was conducted in the actual running test. The conditions of the used tire etc. are as follows.
Tire size: 11R22.5
Rim size: 22.5 "X8.25"
Air pressure: 700KPa
Test vehicle: 2-D truck vehicle Installation position: Front wheel (steering wheel)
Shelf shape: triangular shape shown in FIGS. 2 and 3 Shelf circumferential width: 5.0 mm
Number of shelves: 12 locations on the circumference of the main groove Load: 100% (JATMA specified load), Road surface condition: 100% Pavement Travel speed: 50-80Km / h, Travel distance: 10000Km

When the height of the shelf was 1.0, 3.0, 5.0 (mm) and the shelf was not used under the above conditions, the partial wear was confirmed. The results are shown in Table 3.

From Table 3, it was found that there was a secondary effect that uneven wear resistance was improved when the shelf was provided, compared to when there was no shelf. And it turned out that the effect is fully exhibited in height 3.0mm.

It is a top view of the tire tread surface which provided the shelf of the present invention. It is a top view of the tire tread surface which provided the shelf of another mode of the present invention. FIG. 3 is an AA end view of the shelf portion shown in FIG. 2.

1 Main groove 2 Land 3 Shelf 4,4 'Single shelf

Claims (5)

In a heavy duty pneumatic tire having at least a plurality of main grooves engraved in the tread and continuous in the tire circumferential direction, and a land portion partitioned by the main grooves,
In any one or more of the main grooves, a shelf extending upward from the bottom of the main groove,
The shelf is
The height from the bottom of the main groove is 2.5 to 3.5 mm,
The side of the shelf is in contact with only one side wall of the land ,
About the main groove which has the said shelf part, the said shelf part exists per 1 main groove, The heavy tire for heavy loads characterized by the above-mentioned . In a heavy duty pneumatic tire having at least a plurality of main grooves engraved in the tread and continuous in the tire circumferential direction, and a land portion partitioned by the main grooves,
In any one or more of the main grooves, the main groove has a shelf portion that is composed of two opposing single shelf portions that extend upward from the bottom portion of the main groove,
Of the one shelf part,
The side surface of the one shelf portion is in contact with only one side wall of the land portion,
The side surface of the other one shelf part is in contact with only the side wall of the other land part facing the side wall of the land part where the one piece shelf part contacts,
The shelf has a height from the bottom of the main groove of 2.5 to 3.5 mm ,
About the main groove which has the said shelf part, the said shelf part exists per 1 main groove, The heavy tire for heavy loads characterized by the above-mentioned . 3. The heavy duty pneumatic tire according to claim 1 , wherein there are a plurality of the shelf portions per one main groove, and the distance between the adjacent shelf portions in the main groove direction is equal . The heavy-duty pneumatic tire according to any one of claims 1 to 3, wherein the shelf is present at the bottom of each of the main grooves of the center groove and the shoulder groove. The shape of one shelf part constituting the shelf part composed of the two opposing shelf parts is the rotational shape, the mirror body shape, the fitting shape of the other one shelf part, or any one of the above The heavy duty pneumatic tire according to claim 2, wherein the pneumatic tire is any one of the similar shapes.

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