KR20190077957A - Kerf of Tire - Google Patents

Abstract

The present invention relates to a tread kerf of a tire having a rounded edge to increase performance of preventing irregular wear and chip-cut of the tire. According to the present invention, a block is formed by a main groove formed in the circumferential direction of a tread or shoulder, a flat kerf is formed at a predetermined depth in the tire width direction from a side of the block, a rounded kerf is formed in a tire width direction end of the flat kerf in the depth direction of the block, and the rounded cuff is formed in a conical or elliptical cone shape having a narrow upper side (tire surface) and a wide lower side (tire bottom). According to the present invention, the performance of preventing the irregular wear and chip-cut of the tire can be increased, and the secondary performance (ride and handling performance, grip performance, etc.) of the tire can be increased. When the kerf is applied to the shoulder of the tire, braking force is reduced to further increase the effect of preventing irregular wear.

Description

Kerf of Tire < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cuff of a tire, and more particularly to a tread cuff of a tire having a round edge for improving the performance of preventing irregular wear and chipping of a tire.

Generally, a tire is one of the components constituting a vehicle and directly contacts the road surface. The air inside the tire absorbs the shock caused by the unevenness of the road surface by applying a buffering action like a spring, thereby enhancing the ride feeling.

Such a tire includes a tread which is a rubber layer in contact with the road surface, a side wall connected to the tread and a side wall of the tire, a bead portion connected to the side wall and fixed to the rim of the vehicle, , A carcass that is installed inside the tire and forms a skeleton with a high fatigue resistance against swaying motion of the sidewall, and a carcass that is disposed between the tread and the carcass to protect the carcass and improve the rigidity of the tread surface Belt. The tread is composed of a block and a groove, and a cuff (Kerf) is formed in the block, so that the rigidity of the block is appropriately adjusted to satisfy the required performance of the tire.

The tires formed by forming blocks in treads (for example, TBR tires, such as trucks and bus tires) are formed with cuffs (or sipes) in order to adjust the rigidity of the blocks to improve the tractive force and traction. When the tire is worn, the stiffness of the block increases as it wears. When the stiffness of the block is increased, the tractive force is decreased and the tractive force is decreased. As a result, the slip occurs when the cornering is performed, which may cause an accident.

Accordingly, in the pneumatic tire of Korean Patent Publication No. 2002-0039981, the cross-sectional area of the inner bottom portion of the cuff is formed larger than the surface cross-sectional area of the cuff so that the cross-sectional area of the cuff is enlarged as the wear progresses Sectional area of the cuff is increased as the wear progresses, thereby reducing the surface area of the unit block, thereby reducing the rigidity of the whole block. In order to increase the cross-sectional area of the cuff as it goes to the inner bottom portion, in particular, by increasing the change amount of the cross-sectional area of the cuff stepwise and observing the surface area of the cuff, it is possible to detect the degree of wear of the tire, So that the overall cross-sectional area is increased, and at the same time, there is less interference with the drawing when the tire is taken out from the vulcanizing mold.

U.S. Patent No. 4723584 and U.S. Patent No. 6,196, 888 disclose a tread cuff of a tire having a rounded edge for improving the performance of preventing irregular irregular wear and tear of the tire, Lt; / RTI > Such a tread cuff having a round edge is formed by rounding an edge portion of a cuff among cuffs formed at 30 to 90 degrees in the circumferential direction of the tire from the main groove formed in the circumferential direction of the tread, This structure prevents chip and cut phenomenon which may be caused by stress concentration at the cuff end while lowering the rigidity of the rib of the cuff.

However, in such a conventional tread cuff, there is a problem that the edge portion of the cuff is rounded with a certain curvature to limit secondary performance (ride, handling, grip performance, etc.) of the tire.

Korean Patent Publication No. 2002-0039981 (published on May 30, 2002).

United States Patent No. 4723584 (Registered on Feb., 1988)

U.S. Patent No. 6196288 (Registered on March 23, 2001)

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problems, and it is an object of the present invention to improve a round part of a cuff to prevent irregular wear and tear (chip- And to provide a cuff of a tire which further improves.

In order to achieve the above object, a cuff of a tire according to the present invention is constituted by a main groove formed in a circumferential direction of a tread or a shoulder, a flat cuff is formed at a side surface of the block at a predetermined depth in a tire width direction, Rounded cuffs are formed along the depth direction of the block, and the round cuffs are formed in a conical shape or a conical shape with the upper side (tire surface) narrower and the lower side (tire base side) wider.

The upper diameter or the upper average equivalent diameter of the round cuff is 1.2 mm to 2.4 mm and the lower diameter or lower average equivalent diameter of the round cuff is 3.0 mm to 4.0 mm. The width (thickness, T1) of the flat cuff is formed smaller than the upper diameter of the round cuff.

According to the cuff of the tire of the present invention, it is possible to further improve the performance for preventing irregular wear and tear (chip-cut) phenomenon of the tire and further improve the secondary performance (ride and handling performance, grip performance, etc.) And when the tire is applied to the shoulder of the tire, the braking force is reduced to further improve the irregular wear reduction effect.

1 is a view showing a part of a tread of a tire to which a cuff is applied according to an embodiment of the present invention.
2 is a perspective view showing a cuff of a tire according to an embodiment of the present invention.
Figs. 3 (a) to 3 (c) are an elevational view, a plan view, and a side view of the cuff of Fig. 2;
4 is a graph showing the results of friction energy evaluation for a conventional round cuff and a round cuff of the present invention.
5 is a photograph showing a state in which the tire is irregularly worn according to the braking force acting on the tire.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that, in the drawings, the same components are denoted by the same reference symbols as possible. Further, the detailed description of known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some of the components in the drawings are exaggerated, omitted, or schematically illustrated.

1 is a view showing a part of a tread of a tire to which a cuff is applied according to an embodiment of the present invention. The cuff 100 according to the embodiment of the present invention forms the block 12 by the main groove 11 formed in the circumferential direction of the tread 10 of the tire and the side surface 12a of the block 12, In the width direction of the tire. The cuff of the present invention may be provided in a block formed in a shoulder of a tire.

Fig. 2 is a perspective view showing a cuff of a tire according to an embodiment of the present invention, and Figs. 3 (a) to 3 (c) are an elevation view, a plan view and a side view (left side view) of the cuff of Fig. As shown in the figure, the cuff 100 includes a flat cuff 110 formed to be flat at a certain depth in the width direction of the tire from the side surface 12a of the block 12 and a flat cuff 110 formed at the end of the flat cuff 110 in the tire width direction. And a round cuff 120 formed in a depth direction.

The flat cuff 110 is of a flat plate type having a certain length L1 in the width direction of the tire and a certain length L2 in the depth direction of the block. The width (thickness, T1) of the flat cuff 110 is formed to be smaller than the upper diameter of the round cuff 120, which will be described later.

The round cuff 120 is formed in a conical shape with the upper side (tire surface) narrower and the lower side (tire base side) wide. The round cuff may be formed in a cone shape. The upper diameter D1 of the round cuff 120 is 1.2 mm to 2.4 mm and the lower diameter D2 of the round cuff 120 is 3.0 mm to 4.0 mm. In the case where the round cuff 120 is an outer conical shape, the upper diameter and the lower diameter indicate an average diameter (equivalent diameter). The average diameter or equivalent diameter refers to the diameter of the circular cross-sectional area when the cross-sectional area of the ellipse is taken as the circular cross-sectional area.

The greater the diameter of the round cuff 120, the better the tear at the cuff end. Since the diameter of the round cuff 120 is increased from the upper side (the tire surface) to the lower side (the tire base side), the braking force is reduced as the tread or shoulder of the tire is worn, and thus the irregular wear and tear Cut can be improved. Thereby improving traction performance after mid-wear.

Particularly, in the case of the shoulder portion or the shoulder portion of the tread, irregular wear and chipping occur while being subjected to lateral drag during running, which is remarkably improved.

FIG. 4 is a graph showing the results of friction energy evaluation for a conventional round cuff and a round cuff according to an embodiment of the present invention, and FIG. 5 is a photograph showing a state in which the tire is irregularly worn according to a braking force acting on the tire.

4, the width T1 of the flat cuff 110 is 0.7 mm, the length L1 of the flat cuff on the upper side is 3 mm, the distance from the entrance of the flat cuff to the center of the round cuff is An upper diameter D1 of the round cuff 120 is 1.2 mm, a lower diameter D2 of the round cuff is 3 mm and a depth L2 of the cuff (flat cuff and round cuff) is 5 mm . In the evaluation test of Fig. 4, the conventional example shows an experimental example in which a cylindrical cuff having the same size as that of the embodiment of the present invention and having a diameter of 1.2 mm is used as the round cuff.

In FIG. 4, the y axis represents the force in the running direction, the driving force when the vehicle is in the + direction, and the breaking force when the vehicle is in the -. - The larger the value, the greater the braking force at the time of travel. In the graph, the conventional example shows a case of a cylindrical round cuff, and the embodiment of the present invention shows a case of a conical round cuff having a larger diameter toward the lower side. As can be seen, the embodiment of the present invention has a smaller braking force in the middle section of the x-axis than the conventional example.

The larger the braking force is in comparison with the other portions, the faster the wear occurs. FIG. 5 shows a photograph of the tread portion of the tire in which irregular wear is caused by such braking force.

In the case of a conical round cuff having a large diameter on the lower side as in the embodiment of the present invention, the contact area of the tread block becomes smaller as the wear on the tire surface progresses, so that the round cuff itself serves as a semi-groove And the traction performance is improved.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of the present invention in order to facilitate the understanding of the present invention and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: cuff
110: flat cuff 120: round cuff
D1: Upper diameter of the round cuff D2: Lower diameter of the round cuff
L1: length of the flat cuff L2: depth of the cuff
T1: width of flat cuff (thickness)

Claims (3)

A tread or a shoulder, the main groove being formed in the circumferential direction of the tread or shoulder,
A flat flat cuff having a predetermined depth in the tire width direction is formed on the side surface of the block,
A rounded round cuff is formed along the depth direction of the block at an end portion of the flat cuff in the tire width direction,
Wherein the round cuff is formed as a conical shape or a conical shape having a narrower upper side (tire surface) and a lower side (tire base side). The method according to claim 1,
The upper side diameter or the upper side average equivalent diameter of the round cuff is 1.2 mm to 2.4 mm,
Wherein a lower diameter or a lower average (equivalent) diameter of the round cuff is 3.0 mm to 4.0 mm. The method according to claim 1,
And the width (thickness) (T1) of the flat cuff is smaller than the upper diameter of the round cuff.

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