JP2001260613A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a good sand running performance at a low cost and moving performance during high speed running on a paved road. SOLUTION: The outer surface of a tread 22 is partitioned by six circumferential grooves 32 extending substantially circumferentially along the tread 22 into seven ribs 34, 36. Ribs positioned at both most outer ends in the axial direction of the tread 22 in the seven ribs 34, 36 are used as shoulder ribs 36. The shoulder ribs 36 are provided with a plurality of grip grooves 38 extending toward the center of the tire, respectively, over the entire circumference at substantially constant interval. The lower groove 38A of the grip groove 38 is formed in the extending shape with the same width in orthogonal direction to the surface of the shoulder ribs 36, and the upper groove 38B is formed so as to expand in the sector form from the end of the lower groove 38A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low cost, pneumatic tire having excellent running performance on sandy ground and at the same time, running performance at high speed on a pavement road. It is suitable for a pneumatic tire having the same.

[0002]

2. Description of the Related Art Conventionally, tread patterns such as rib type, lug type, rib lug type and block type have been known as tread patterns of pneumatic tires used in vehicles. Then, as a pneumatic tire having a bias structure mounted on a vehicle running on sand, for example, the outer surface of the tread is axially divided into a plurality by a circumferential groove extending in a circumferential direction of the tread, and a plurality of circumferential grooves are formed in the circumferential direction of the tread. A rib type one in which the ribs of the book extend is used.

[0003] In particular, in order to improve running performance on sand,
In some tires, a grip groove is formed in this outer rib along a direction substantially perpendicular to the direction in which the outermost rib located on the outermost side of the tread extends. It is known that the greater the depth of the grip groove and the greater the volume of the grip groove, the easier it is to grip the sand when traveling on sand, and the more the sand traveling performance is improved.

[0004] On the other hand, even a vehicle equipped with sand running tires does not always run on sand lands in the Middle East and Africa where sand lands can be run. When traveling to, the vehicle will travel on a paved road. In such an area, when the vehicle leaves the city, the amount of vehicles decreases, and the road becomes a wide and straight pavement road. Traveling becomes possible.

[0005]

However, in the case of a tire for running on a sand in which a grip groove is provided on the outer rib, the provision of the grip groove significantly reduces the tread rigidity of the shoulder portion. For this reason, traveling at high speed on a pavement road with such tires not only deteriorates straight running performance and causes a wobble phenomenon on the vehicle, but also deteriorates braking performance and steering performance, and as a result, exercise during high speed traveling on pavement road. The performance deteriorates, and it becomes difficult to drive the vehicle at will of the driver.

On the other hand, in order to achieve both sandy road performance and pavement road performance, not only a grip groove is provided but also a breaker which is a belt-like reinforcing material is arranged in the tread to reduce the rigidity of the shoulder portion. By controlling, the exercise performance on the pavement can also be improved. However, by providing the grip groove and the breaker, both the sandy road running performance and the high-speed pavement road running performance can be achieved, but the tire manufacturing cost increases with the arrangement of the breaker.

[0007] In other words, even with such tires having both the sandy road running performance and the high-speed running performance on a pavement road, if the price rises with an increase in the manufacturing cost, it is possible to meet the demands of customers. It does not become. The present invention has been made in view of the above-described circumstances, and has as its object to provide, at low cost, a pneumatic tire which has excellent running performance on sandy ground and dynamic performance during high-speed running on a paved road.

[0008]

The pneumatic tire according to the present invention has a plurality of ribs defined by a plurality of circumferential grooves extending along the circumferential direction of the tread and each extending along the circumferential direction of the tread. A pneumatic tire provided with a grip groove for gripping sand and preventing slippage between the sand and the outermost rib of the tread among these ribs, The lower side of the cross-sectional shape extending in the same width along the crossing direction forms the back side of the grip groove. The side is constituted.

The operation of the pneumatic tire according to claim 1 will be described below. By dividing the outer surface of the tread by a plurality of circumferential grooves extending along the circumferential direction of the tread,
The pneumatic tire has a tread pattern having a plurality of ribs each extending along the circumferential direction of the tread. Outer ribs located on the outermost side of these ribs are provided with grip grooves for gripping sand and preventing slippage with sand. Further, the cross-sectional shape of the lower side groove portion forming the back side of the grip groove is formed so as to extend with the same width along a direction intersecting with the surface of the outer rib, and forms the opening side of the grip groove. The cross-sectional shape of the upper groove is formed so as to fan out from the end of the lower groove.

[0010] Therefore, since the tire is provided with a grip groove for gripping the sand and preventing slippage between the tire and the sand, the tire does not run idle even on the sand, so that it is difficult to stack and the vehicle can run reliably. And sand running performance can be secured at a high level. And although the tread rigidity of the shoulder part is reduced by providing this grip groove,
The upper groove is formed so as to fan out from the end of the lower groove that extends with the same width of the grip groove, and the cross-sectional shape of the grip groove is made substantially Y-shaped, so that the rigidity of the shoulder required for the tire is reduced. Secured. Along with this, it is possible to lower the standard for securing the expected rigidity of the breaker, and it is possible to omit the breaker and reduce the width of the breaker, and to reduce the tire manufacturing cost while maintaining the various performance required for the tire. It became possible to maintain. In other words, it is possible to achieve, at a low cost, various performances required at the time of traveling on sandy ground and traveling at high speed on a pavement road at a high level.

The operation of the pneumatic tire according to claim 2 will be described below. The present invention operates in the same manner as in the first aspect, but further has a configuration in which a grip groove is provided on the outer rib so as to extend toward the center of the tire. That is, when the tire travels in the sand, the grip is provided on the outermost one of the plurality of ribs so as to extend toward the center of the tire and arranged on the side surface of the tire. The grooves firmly grip the large amount of sand present on the side of the tire to further improve the grip, thereby further increasing the power to move forward without sinking in the sand.

The operation of the pneumatic tire according to claim 3 will be described below. The present invention operates in the same manner as the first and second aspects, but further has a configuration in which the depth of the outermost circumferential groove among the plurality of circumferential grooves is the same as the depth of the grip groove. Have. In other words, by setting the cross-sectional shape of the grip groove to be substantially Y-shaped, the rigidity of the shoulder portion required as a tire can be secured, so that a decrease in the tread rigidity of the shoulder portion leads to a decrease in the exercise performance when traveling on a high-speed pavement road. Without having to worry about the problem, it is possible to improve the grip performance when traveling on sandy ground by making the depth of the grip groove the same as the depth of the outermost circumferential groove.

The operation of the pneumatic tire according to claim 4 will be described below. The present invention operates in the same manner as the first to third aspects, except that the width of the lower groove portion of the grip groove is set to 2 to 15 mm. In other words, when the width is less than 2 mm, the rigidity of the shoulder portion is increased, so that the traveling performance on the pavement road can be ensured, but the traveling performance on sandy ground decreases. Conversely, if the width exceeds 15 mm, the traveling performance on sandy ground is improved, but the steering performance on a good pavement road is reduced.

The operation of the pneumatic tire according to claim 5 will be described below. The present invention operates in the same manner as the first to fourth aspects, but further has a configuration in which the depth of the lower side groove portion of the grip groove is set to be not more than １ ／ of the depth of the entire grip groove. . In other words, when the depth of the lower side groove portion exceeds half of the depth of the entire grip groove, the rigidity of the shoulder portion increases as the volume of the grip groove decreases,
Although the traveling performance on the pavement can be ensured, the traveling performance on sandy ground is reduced.

The operation of the pneumatic tire according to claim 6 will be described below. The present invention operates in the same manner as the first to fifth aspects, but further has a configuration in which the inclination angle of the wall surface forming the upper side groove portion of the grip groove is 5 ° to 60 °. In other words, when the inclination angle of the wall surface forming the upper side groove portion is less than 5 °, the rigidity of the shoulder portion increases as the volume of the grip groove becomes smaller, so that the traveling performance on the pavement road is improved, The sandy road running performance will be reduced. Conversely, when this angle exceeds 60 °, the running performance on sandy ground is improved, but the running performance on a pavement road is reduced, and vibration and uneven wear are liable to occur.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic tire according to an embodiment of the present invention is shown in FIGS. 1 to 5 and will be described with reference to these drawings. FIG. 1 shows a sand tire having a bias structure as an example of a pneumatic tire 10 according to the present embodiment,
A carcass (not shown) constituting the skeleton of the pneumatic tire 10 is formed by a plurality of layers of members (not shown) in which nylon cords are alternately arranged obliquely with respect to the equatorial plane PL of the pneumatic tire 10. Have been.

In the vicinity of both ends of the carcass, a pair of bead cores 14 (only one is shown) each of which is formed by winding and bundling a steel wire in a ring shape is arranged.
Both ends of the carcass are wound around the pair of bead cores 14, respectively. Furthermore, this bead core 14
A bead filler 16 made of hard rubber and formed into a tapered shape is embedded in the gap between the carcass on the upper side of the above. As described above, the carcass is arranged so as to straddle the pair of bead cores 14, and the carcass is embedded in the crown 18 so as to penetrate the crown 18 serving as the top of the pneumatic tire 10.

On the other hand, a carcass is also arranged on a sidewall 24 of the pneumatic tire 10 which is a portion connecting between the bead core 14 and the crown portion 18, and an inner liner forms the innermost layer of the pneumatic tire 10. I have.

The crown portion 18 has a tread 2 which is an outer skin made of rubber material and grounded on the road surface.
2 are arranged. 1 and 3 showing a typical example of a tread pattern of a pneumatic tire 10 according to the present embodiment.
As shown in FIG. 5, the rib 34 is defined by six circumferential grooves 32 (only three are shown) extending substantially along the circumferential direction of the tread 22, and the outer surface of the tread 22 is seven land portions. , 36 (only four tires are shown) of the pneumatic tire 10.

Further, a shoulder portion 30 is located between the sidewall 24 and the crown portion 18, and is defined by a circumferential groove 32 of the seven ribs 34 and 36, and is defined by an axial direction of the tread 22. The ribs located at the outermost ends on the shoulder portion 30 are shoulder ribs 36 which are outer ribs.

As shown in FIG. 2, a pair of shoulder ribs 36 (only one is shown) are provided with grip grooves 38 extending toward the center of the pneumatic tire 10 so as to make one round along the circumferential direction of the pneumatic tire 10. Are arranged. The grip groove 38 includes a lower groove 38A that forms the back side of the grip groove 38 and an upper groove 38B that also forms the opening side. And FIG.
5 showing a cross section taken along line 5-5 of FIG.
The cross-sectional shape of A is formed so as to extend with the same width along the orthogonal direction which is the direction intersecting with the surface of the shoulder rib 36, and the cross-sectional shape of the upper side groove 38B is the upper end of the lower side groove 38A. It is formed so as to fan out from the part.

Further, the width dimension W of the lower groove portion 38A of the grip groove 38 is 2 to 15 mm, and the depth dimension H1 of the grip groove 38 shown in FIG. The size is the same as the depth dimension H2 of the groove 32. Further, as shown in FIG. 5, the depth dimension H3 of the lower groove portion 38A of the grip groove 38 is not more than 1/2 of the depth dimension H1 of the entire grip groove 38.
Here, the depth dimension H2 of the outermost circumferential groove 32 is about 6 to 9 mm.

As shown in FIG. 5, the inclination angle θ of each of a pair of wall surfaces 38C forming the upper side groove portion 38B of the grip groove 38 with respect to a perpendicular line V perpendicular to the tire surface is 5 ° to 60 °. Angle. Further, the pitch P of the grip groove 38 along the tire circumferential direction shown in FIG. 3 is set to 35 to 100 mm.

On the other hand, as shown in FIGS. 2 and 3, there is a gap between the hump portion 42 and the buttress portion 44 of the shoulder rib 36, which is closer to the inner peripheral side of the pneumatic tire 10 than the grip groove 38. A concave portion 40 for increasing the grip force is formed while being connected to the grip groove 38. Therefore, since the pneumatic tire 10 is connected to the grip groove 38, the same number of the recesses 40 as the number of the grip grooves 38 are provided in the pneumatic tire 10.

Then, in order to secure the cross-sectional area S of the concave portion 40 shown in FIG.
Is set to 2 to 15 mm, and the ratio of the recess 40 in one pitch of the grip groove 38 along the circumferential direction of the tire is 30 to 80%.

Next, the operation of the pneumatic tire 10 according to the present embodiment will be described below. The outer surface of the tread 22 is defined by a plurality of circumferential grooves 32 extending along the circumferential direction of the tread 22 so that the outer surface of the tread 22 has seven ribs 34 and 36 respectively extending along the circumferential direction of the tread 22. The pneumatic tire 10 has a tread pattern. The outermost shoulder rib 36 of the ribs 34, 36 is provided with a grip groove 38 extending toward the center of the tire, and a portion closer to the tire inner peripheral side with respect to the grip groove 38. Recess 40
Are formed.

Further, the cross-sectional shape of the lower side groove portion 38A constituting the back side of the grip groove 38 is formed so as to extend at the same width along a direction orthogonal to the surface of the shoulder rib 36, and The cross-sectional shape of the upper groove portion 38B constituting the opening side of 38 is formed so as to fan out from the upper end portion of the lower groove portion 38A.

As described above, since the tire is provided with the grip groove 38 for gripping the sand and preventing slippage between the tire and the sand, the tire does not rotate idly on the sand, so that a high level of running performance on the sand can be ensured. .

More specifically, when a vehicle equipped with a tire having a tread pattern formed only on the outer peripheral surface runs on a soft sandy ground, the tire sinks greatly into the sand and the sand is wrapped around the front and side surfaces of the tire. In addition, the tire spins idly without being able to secure sufficient force to move forward, and it becomes easy to stack.
However, in the present embodiment, a shape is provided on the outermost shoulder rib 36 of the seven ribs 34 and 36 so as to extend toward the center of the tire on the side surface of the pneumatic tire 10. Has a grip groove 38. Therefore, when traveling on sandy ground with the pneumatic tire 10, the grip groove 38 firmly grips a large amount of sand present on the side surface of the pneumatic tire 10 to greatly improve the gripping property. Improved the ability to move forward without sinking in the sand.

Although the tread rigidity of the shoulder portion 30 is reduced by providing the grip groove 38, the lower groove portion 38 extending at the same width as the grip groove 38 is provided.
The upper side groove portion 38B is formed so as to spread in a fan shape from the upper end portion of A, and the cross-sectional shape of the grip groove 38 is substantially Y-shaped, so that the rigidity of the shoulder portion 30 required as a tire is secured. Along with this, it is possible to lower the standard for securing the expected rigidity of the breaker, and it is possible to omit the breaker and reduce the width of the breaker, and to reduce the tire manufacturing cost while maintaining the various performance required for the tire. Can be maintained. In other words, it is possible to achieve, at a low cost, various performances required at the time of traveling on sandy ground and traveling at high speed on a pavement road at a high level.

Further, in the present embodiment, since the concave portion 40 is formed while being connected to the grip groove 38, the sand easily flows from the grip groove 38 into the concave portion 40, and more sand is formed in the concave portion 40. I was able to grab it.
For this reason, the presence of the concave portion 40 makes it more difficult for the pneumatic tire 10 to idle even on a sandy ground, so that the sandy ground running performance is further improved.

On the other hand, in the present embodiment, the grip groove 38
Is approximately Y-shaped, rigidity of the shoulder portion 30 required as a tire can be secured. Therefore, the grip groove 3 can be formed without considering a decrease in rigidity of the shoulder portion 30.
By making the depth 8 the same as the depth of the outermost circumferential groove 32, the grip performance can be further enhanced.

On the other hand, in the present embodiment, a plurality of grip grooves 38 arranged along the circumferential direction of the pneumatic tire 10 are provided.
The width dimension W of the lower groove portion 38A was 2 to 15 mm.
In other words, if the width dimension W of the grip groove 38 is less than 2 mm, the rigidity of the shoulder portion 30 is increased and traveling performance on a pavement road can be ensured, but the volume of the lower groove portion 38A becomes too small, so that the sand can be sufficiently grasped. And the running performance on the sand decreases. On the other hand, if the width W is increased, the volume of the lower groove portion 38A is increased, so that the grip force is greatly improved.

However, even a vehicle equipped with tires for traveling on sandy ground often travels on a general road until reaching a sand dune. For this reason, when the width dimension W of the lower side groove portion 38A exceeds 15 mm, the sandy ground running performance is improved, but the steering performance on the pavement road is reduced. Therefore, the upper limit value is set to 15 mm. Further, as a range of a more preferable value of the width dimension W of the lower groove portion 38A of the grip groove 38 that further satisfies these conditions, a range of 3 to 10 mm can be considered.

In order to secure the grip force, it is important that the grip groove 38 has a structure that allows the sand to be easily gripped by the sand when the tire rotates on the sand ground, and that the sand once caught in the grip groove 38 to be hardened. Therefore, the inclination angle θ of the wall surface 38C of the upper groove portion 38B of the grip groove 38 in FIG.
Is set to 5 ° to 60 °.

That is, the wall surface 38 of the upper groove 38B
When the inclination angle θ of C is less than 5 °, the running performance on a pavement road is improved, but the rotation of the tire causes the grip groove 38 to rotate.
When the vehicle separates from the sand, the solidified sand is easily broken under the load to which the load of the vehicle is applied. As a result, the grip performance is reduced, and the running performance on sandy ground is deteriorated. On the other hand, when the inclination angle θ of the wall surface 38C of the upper side groove portion 38B exceeds 60 °, the sand running performance is improved as the sand is easily solidified, but the running performance on the pavement road is reduced and the vibration is reduced. And uneven wear easily occur. In addition, in order to secure a greater grip force, it is desirable that the inclination angle θ of the wall surface 38C be 10 ° to 45 °.

Further, in this embodiment, the grip grooves 3
8 has the same depth as the depth H2 of the outermost circumferential groove 32 of the plurality of circumferential grooves 32, as well as the lower groove 38A of the grip groove 38.
Is not more than の of the depth H1 of the entire grip groove 38.

That is, the lower groove portion 38 of the grip groove 38
If the depth A exceeds 1/2 of the depth of the entire grip groove 38, the rigidity of the shoulder portion 30 increases as the volume of the grip groove 38 decreases, so that traveling performance on a pavement road is secured. Although it is possible, the running performance on sandy ground will be reduced. Further, in order to more reliably achieve both traveling performance on a pavement road and traveling performance on sandy ground, the depth dimension H3 of the lower groove portion 38A is set to one of the depth dimension H1 of the entire grip groove 38.
To と す る is desirable.

Next, regarding the example of the pneumatic tire 10 described in the present embodiment, the width dimension W of the lower groove 38A and the depth dimension H3 of the lower groove section 38A with respect to the depth dimension H1 of the entire grip groove 38 are described. , The inclination angle θ of the upper groove 38B, and the four types of pneumatic tires with different conditions regarding the presence / absence of a breaker were respectively subjected to an actual vehicle evaluation test. The results are shown in Table 1 below.

[0040]

[Table 1]

Here, the actual vehicle evaluation is a driver's response evaluation (feeling evaluation) of the traveling performance, and the grip feeling, the bank feeling, the slip feeling, the braking feeling at the time of high-speed running on a paved road, and Maneuvering stability and the like are included in the evaluation contents. In addition, the higher the score, the higher the evaluation. Five points are evaluated as the highest points, and three or more points are evaluated as having no practical problem.

As shown in Table 1, all the tires corresponding to the embodiment both have a sandy road running performance and a high speed running performance on a pavement road.
It turns out that it is in the range of 5 points from the point. Here, in Table 1, the unit of the width dimension W, the depth dimension H1, and the depth dimension H3 is mm, and the unit of the inclination angle θ is degree.

As the pneumatic tire according to the present invention,
A tire having both a grip groove and a breaker, or a tire having a grip groove but no breaker is conceivable. However, since the cross-sectional shape of the grip groove is substantially Y-shaped, a shoulder portion necessary for the tire is provided. Therefore, any tire can be used.

Furthermore, various tires to which the present invention can be applied are conceivable, and the name of the tire is 9.00.
-15, 9.00-16, etc.
It is more suitably used for sand tires that are marked with R SAND SERVICE, SAND TIRE, DESERT TIRE and the like. In the above embodiment, the number of the circumferential grooves 32 extending substantially along the circumferential direction of the tread 22 is six, and the ribs 34,
Although 36 are seven, the number of circumferential grooves and the number of ribs are not limited to these values, and may be other numbers.

[0045]

Since the pneumatic tire of the present invention has the above-described structure, it is possible to secure excellent running performance on sandy grounds at low cost and also to secure the kinetic performance during high-speed running on a pavement road. Has the effect.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pneumatic tire according to one embodiment of the present invention.

FIG. 2 is an enlarged side view showing a main part of a side surface of the pneumatic tire according to one embodiment of the present invention.

FIG. 3 is a developed view showing a main part of the pneumatic tire according to the embodiment of the present invention in a developed manner.

FIG. 4 is an enlarged sectional view showing a main part of the pneumatic tire according to one embodiment of the present invention, and is a sectional view taken along line 4-4 in FIG.

FIG. 5 is an enlarged sectional view taken along a circumferential direction of a main part of the pneumatic tire according to one embodiment of the present invention.
5-5 is a sectional view taken along line 5-5.

[Explanation of symbols]

 10 Pneumatic tire 32 Circumferential groove 34 Rib 36 Shoulder rib 38 Grip groove 38A Lower groove 38B Upper groove

Claims (6)

[Claims] 1. A tread having a plurality of ribs defined by a plurality of circumferential grooves extending along the circumferential direction of the tread and extending respectively along the circumferential direction of the tread, and the outermost one of the ribs located at the outermost position of the tread. A pneumatic tire provided with a grip groove on an outer rib for gripping sand and preventing slippage between the outer rib and a cross-sectional shape extending at the same width along a direction intersecting the surface of the outer rib. The pneumatic tire is characterized in that the lower side groove portion forms the back side of the grip groove, and the upper side groove portion has a cross-sectional shape extending in a fan shape while being connected to the lower side groove portion, and the opening side of the grip groove is formed. 2. The pneumatic tire according to claim 1, wherein the grip groove is provided on the outer rib so as to extend toward the center of the tire. 3. The pneumatic tire according to claim 1, wherein the depth of the outermost circumferential groove out of the plurality of circumferential grooves and the depth of the grip groove are the same. . 4. The width of the lower groove portion of the grip groove is set to 2-15.
The pneumatic tire according to any one of claims 1 to 3, wherein the diameter is set to mm. 5. The pneumatic tire according to claim 1, wherein the depth of the lower groove portion of the grip groove is not more than half the depth of the entire grip groove. 6. The pneumatic tire according to claim 1, wherein an inclination angle of a wall surface forming an upper groove portion of the grip groove is 5 ° to 60 °.