Patent Description:
A pneumatic tire is configured to include an inner liner that forms the inside of the tire, a body ply stacked on the outside of the inner liner, a belt stacked on the outside of the body ply, a tread stacked on the outside of the belt, sidewalls forming both side portions of the tire, and a bead coupled to a wheel.

In addition, the tread which grips a road surface has a specifically shaped pattern formed to enhance grip force, drainage, braking force, noise dispersion, or the like, and a shape of the pattern significantly affects a tire performance on rainy and snowy roads and a handling performance. Hence, the shape of the pattern is a major factor in tire development. A kerf is a deep groove which is often cut in a transverse direction in a tread block to have a narrow width of <NUM> or narrower, and the kerf provides cushioning to bring about a comfortable ride while enabling a ground gripping surface to be even and enhancing grip force. In addition, the kerf has a function of facilitating rapid drainage to increase driving force and braking force.

Recently, the pattern design tends to more focus on performance rather than on a simple design and an external appearance. A pattern performance technology is subdivided and changed into fine ranges for tire performance.

In addition, when a snow tire rotates on a road surface, the edge effect due to the kerf enables the snow tire to be driven and braked, and thus it is possible to ensure a snow performance of the tire during running of a vehicle.

The kerf which is applied to the snow tire for the edge effect reduces strength of a tread rubber block, thus resulting in degrading the tire performance on a dry road surface. In this respect, in order to secure the strength of a block by improving a confinement performance by a kerf in a perpendicular direction from a surface of a tire, application of a 3D kerf element is increased. In general, when a snow tire with a kerf is driven, there occurs a phenomenon in which a block of the snow tire collapses too much or a leading portion of the block is rolled inward in a moving direction of the tire, and thus there often occurs a phenomenon of a reduction in frictional force due to friction with a road surface.

The edge effect occurs at the leading portion of a tread block during driving and occurs at a tailing portion of the block during braking, and thus there occurs a phenomenon of an increase in ground grip pressure more than that at other portions in the block. The increase in ground grip pressure in a condition where a hydroplaning and a snow layer are formed between a road surface and a tire causes a friction coefficient to be increased by breaking the hydroplaning and the snow layer. A problem arises in that, as density of kerfs increases, an existing kerf structure causes the strength of a block to be decreased and has no effect on the wet and snow performance due to a reduction in edge effect with a reduction in ground grip pressure which results from an increase in block sliding and an increase in ground grip surface, or an abnormal wear phenomenon occurs.

Pneumatic tires comprising sipes, i.e., slits in a tread stock, which have different shapes, are known from <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

Publications <CIT>, <CIT> and <CIT> describe 3D kerf elements to be inserted into a kerf. These 3D kerf elements may comprise different geometrical shapes, such as an arrow-shape, a zig-zag shape as well as mesh and honeycomb structures.

An object of the invention to solve the above-described problem is to provide a pneumatic tire with a 3D kerf element which improves a snow performance by inserting the 3D kerf element into a kerf groove of a tire tread, the 3D kerf element including a top surface having a wave shape and a side surface having a trapezoid shape.

In addition, another object of the invention to solve the above-described problem is to provide a pneumatic tire with a 3D kerf element which improves a ground grip force and handling and braking performances of the tire by causing an interlocking phenomenon between blocks as one or more 3D kerf elements come into close contact with and are fixed between one or more blocks while being inserted into one or more kerf grooves.

Technical objects to be achieved by the invention are not limited to the technical objects mentioned above, and the following description enables other unmentioned technical objects to be clearly understood by a person of ordinary skill in the art to which the invention pertains.

The present invention provides a pneumatic tire according to claim <NUM>. Further developments of the invention are defined in the dependent claims.

Hereinafter, the invention is to be described with reference to the accompanying drawings. However, the invention can be realized as various different examples and thus is not limited to an embodiment described herein. Besides, a part unrelated to the description is omitted from the drawings in order to clearly describe the invention, and similar reference signs are assigned to similar parts through the entire specification.

In the entire specification, a case where a certain part is "connected to (attached to, in contact with, or coupled to)" another part means not only a case where the parts are "directly connected" to each other, but also a case where the parts are "indirectly connected" to each other with another member interposed therebetween. In addition, a case where a certain part "comprises" a certain configurational element does not mean that another configurational element is excluded but means that other configurational elements can be further included unless specifically described otherwise.

Terms used in this specification are only used to describe a specific embodiment and are not intentionally used to limit the invention thereto. A singular form of a noun includes a plural meaning of the noun unless obviously implied otherwise in context. In this specification, words such as "to comprise" or "to include" are to be understood to specify that a feature, a number, a step, an operation, a configurational element, a member, or a combination thereof described in the specification is present and not to exclude a possibility of presence or addition of one or more other features, numbers, steps, operations, configurational elements, members, or combinations thereof in advance.

Hereinafter, an embodiment of the invention will be described in detail with reference to the accompanying drawings.

<FIG> is a perspective view in one direction illustrating a pneumatic tire with a 3D kerf element according to the embodiment of the invention.

First, a tire <NUM>, into which a 3D kerf element <NUM> is inserted, and a tire wheel <NUM> which supports the tire <NUM> are to be described.

With reference to <FIG>, the tire <NUM> has a tread <NUM> and a shoulder <NUM> formed at a side surface of the tread <NUM>. In addition, although not illustrated in <FIG>, a belt, an inner liner, a cap ply, a carcass, a bead, or the like can be formed on the tire <NUM>, and these configurational elements correspond to known technologies. Hence, the detailed description thereof is to be limited.

The tread <NUM> includes a groove <NUM>, a kerf groove <NUM>, and a block <NUM>.

The groove <NUM> is sunken toward a center of the tread <NUM> and is formed in a circumferential direction of the tire <NUM>, thus, fulfilling a function of drainage, and one or more (three in <FIG>) grooves <NUM> are formed as illustrated in <FIG>.

The kerf grooves <NUM> are sunken toward the center of the tread <NUM> and are formed in a central axis direction of the tire <NUM>. When the tread <NUM> is formed in a vertical direction based on <FIG>, the kerf grooves <NUM> is formed in a horizontal direction, and one or more (<NUM> in <FIG>) kerf grooves <NUM> are formed as illustrated in <FIG>.

In addition, a shape of the kerf groove <NUM> is not limited to the shape illustrated in <FIG>, and the kerf groove is formed to have a shape such that the 3D kerf element <NUM> to be described below is inserted to come into close contact with one or more blocks <NUM>.

In this respect, a side surface of the one or more blocks <NUM> can be formed in parallel with one or more blocks <NUM> to be parallel to a side surface of the 3D kerf element <NUM>.

The blocks <NUM> are divided by the one or more grooves <NUM> and the one or more kerf grooves <NUM>, and one or more (<NUM> in <FIG> and <NUM> as individual blocks such as first blocks and second blocks) blocks <NUM> are formed as illustrated in <FIG>.

The blocks <NUM> grip a road surface and enable a vehicle to be stopped due to a frictional force.

In the invention, reference signs are assigned to a pair of blocks among adjacent blocks for the description.

The pair of blocks are a first block 213a and a second block 213b.

The first block 213a and the second block 213b are divided by the groove <NUM> and the kerf groove <NUM>, and thus the first block 213a and the second block 213b are positioned to be separated from each other as much as the kerf groove <NUM> is formed.

The shoulder <NUM> is formed at a side of the tread <NUM> and comes into close contact with the tire <NUM> when the tire <NUM> is mounted on the tire wheel <NUM>.

With reference to <FIG>, the tire wheel <NUM> includes a cylindrical rim <NUM> having both sides which are open, a disc <NUM> positioned at a central portion of the rim <NUM>, and one or more spokes <NUM> which connect the rim <NUM> and the disc <NUM>.

Hereinafter, a pneumatic tire with a 3D kerf element according to the embodiment of the invention is to be described with reference to <FIG>.

With reference to <FIG>, the pneumatic tire with a 3D kerf element according to the embodiment of the invention includes the 3D kerf element <NUM> and the tire <NUM>.

The 3D kerf element <NUM> is inserted into and fixed in the kerf groove <NUM> formed between a pair of adjacent blocks, and one or more 3D kerf elements are formed to be inserted into the one or more kerf grooves <NUM>.

In addition, since the one or more 3D kerf elements <NUM> come into close contact with and are fixed between the one or more blocks <NUM> as being inserted into the one or more kerf grooves <NUM>, an interlocking phenomenon between blocks occurs to improve a ground grip force and handling and braking performances of the tire <NUM>.

The 3D kerf element <NUM> according to the embodiment is manufactured of one of stainless steel (SUS304, SUS301, SUS420J2, and SUS630) materials by performing bending thereon. The 3D kerf element <NUM> can be manufactured by performing 3D printing on one material of maraging steel, SUS630, and Ti powder, in addition to the stainless steel materials.

In addition, the frictional force changes depending on a shape of the 3D kerf element <NUM>, and the detailed description thereof is to be provided below.

In this respect, the 3D kerf element <NUM> has a flat portion, a recessed portion, and a protruded portion.

<FIG> is a partially-detailed view illustrating enlargement of region S in <FIG>.

The flat portion comes into close contact with and is fixed between the pair of adjacent blocks 213a and 213b among the one or more blocks <NUM>.

With reference to <FIG>, the flat portion includes a first flat member <NUM>, a second flat member <NUM>, a third flat member <NUM>, and a fourth flat member <NUM> which are one or more flat members having a flat-plate shape.

The first flat member <NUM> has the flat-plate shape and is positioned inside the kerf groove <NUM> at one side.

The second flat member <NUM> has the same shape and size as the first flat member <NUM> and is coupled to the first flat member <NUM>.

The third flat member <NUM> has the flat-plate shape, has the same shape and size as the first flat member <NUM> and the second flat member <NUM>, and is positioned inside the kerf groove <NUM> at the other side.

The fourth flat member <NUM> has the same shape and size as the third flat member <NUM> and is coupled to the third flat member <NUM>.

The first and second flat members <NUM> and <NUM> are positioned on the left side based on <FIG>, and the third and fourth flat members <NUM> and <NUM> are positioned on the right side based on <FIG>.

The recessed portion has a predetermined curvature and is formed to recess in one direction of the circumferential direction of the tire <NUM>. The recessed portion includes a first recessed member <NUM>, a second recessed member <NUM>, a third recessed member <NUM>, and a fourth recessed member <NUM> which are one or more recessed members.

As illustrated in <FIG>, the first recessed member <NUM> is connected to the first flat member <NUM>. Specifically, one side of the first recessed member <NUM> is connected to the other side of the first flat member <NUM>, and the other side of the first recessed member <NUM> is connected to one side of a first protruded member <NUM>.

In addition, the first recessed member <NUM> is formed to recess downward so as to have a predetermined curvature as illustrated in <FIG>.

Here, a radius R1 of the first recessed member <NUM> is preferably <NUM>; however, the radius is not limited thereto.

The second recessed member <NUM> is connected to the second flat member <NUM> and is coupled to the first recessed member <NUM>. Specifically, one side of the second recessed member <NUM> is connected to the other side of the second flat member <NUM>, and the other side of the second recessed member <NUM> is connected to one side of a second protruded member <NUM>.

In addition, the second recessed member <NUM> is formed to recess downward so as to have a predetermined curvature as illustrated in <FIG>.

As illustrated in <FIG>, the third recessed member <NUM> is connected to a first protruded member <NUM>. In addition, the third recessed member <NUM> is formed to recess downward so as to have a predetermined curvature as illustrated in <FIG>.

Here, the radius R1 of the third recessed member <NUM> is preferably <NUM> as the radius of the first recessed member <NUM>; however, the radius is not limited thereto.

The fourth recessed member <NUM> is connected to a second protruded member <NUM> and is coupled to the third recessed member <NUM>. In addition, the fourth recessed member <NUM> is formed to recess downward so as to have a predetermined curvature as illustrated in <FIG>.

According to the invention, the top surface of the 3D kerf element <NUM> has a wave shape which bends alternately one or more times, the top surface being parallel to a surface of the tread <NUM>.

Specifically, the first and second recessed members <NUM> and <NUM>, the first and second protruded members <NUM> and <NUM>, the third and fourth recessed members <NUM> and <NUM>, and the third and fourth protruded members <NUM> and <NUM> described above are coupled to each other in consecutive order, and thus a wave shape is formed as a whole as illustrated in <FIG>.

<FIG> is a cross-sectional view taken along line a-b in <FIG>.

According to the invention, a side surface of the 3D kerf element <NUM> has a trapezoid shape which bends alternately one or more times, the side surface being parallel to the one or more blocks <NUM>.

Regarding a feature described above, the third and fourth recessed members <NUM> and <NUM> formed between the first and second blocks 213a and 213b are illustrated as an example in <FIG> and are described in detail based thereon.

A thickness f of the 3D kerf element <NUM> is <NUM> to <NUM> and preferably <NUM>. In <FIG>, the thickness is the thickness f of the third and fourth recessed members <NUM> and <NUM>. Besides, the same is true of thickness f of the first and second flat members <NUM> and <NUM>, the third and fourth flat members <NUM> and <NUM>, the first and second recessed members <NUM> and <NUM>, the first and second protruded members <NUM> and <NUM>, or the third and fourth protruded members <NUM> and <NUM>.

In addition, a shortest distance (j + j) from one end of a recessed part of the 3D kerf element <NUM> to one end of a protruded part of the 3D kerf element <NUM> is twice a shortest distance j between both ends of the third and fourth recessed members <NUM> and <NUM> illustrated in <FIG>, and the shortest distance (j + j) is <NUM> to <NUM> and preferably <NUM>.

In addition, in <FIG>, a depth g of the third and fourth members <NUM> and <NUM> is <NUM>.

Also, a radius R2 of a bent part of the fourth recessed member <NUM> is <NUM>, and an angle between a horizontal line in a right-left direction and a tangent line of the third recessed member <NUM> based on <FIG> is <NUM> degrees.

The protruded portion has one or more protruded members <NUM>, <NUM>, <NUM> and <NUM> which have a predetermined curvature and are formed to protrude in the other direction of the circumferential direction of the tire <NUM>.

The protruded portion includes the first protruded member <NUM>, the second protruded member <NUM>, the third protruded member <NUM>, and the fourth protruded member <NUM>.

The first protruded member <NUM> is connected to the first recessed member <NUM>. Specifically, one side of the first protruded member <NUM> is connected to the other side of the first recessed member <NUM>, and the other side of the first protruded member <NUM> is continuously connected to one side of the third recessed member <NUM>.

In addition, the first protruded member <NUM> is formed to have a predetermined curvature.

The second protruded member <NUM> is connected to the second recessed member <NUM> and is coupled to the first protruded member <NUM>. Specifically, one side of the second protruded member <NUM> is connected to the other side of the second recessed member <NUM>, and the other side of the second protruded member <NUM> is continuously connected to one side of the fourth recessed member <NUM>.

In addition, the second protruded member <NUM> is formed to have a predetermined curvature, and the radius R1 of the second protruded member <NUM> is preferably <NUM> as the radius of the first recessed member <NUM> and the third recessed member <NUM>; however, the radius is not limited thereto.

The third protruded member <NUM> is connected to the third recessed member <NUM>. Specifically, one side of the third protruded member <NUM> is connected to the other side of the third recessed member <NUM>, and the other side of the third protruded member <NUM> is continuously connected to one side of the third flat member <NUM>.

In addition, the third protruded member <NUM> is formed to have a predetermined curvature.

The fourth protruded member <NUM> is connected to the fourth recessed member <NUM> and is coupled to the third protruded member <NUM>. Specifically, one side of the fourth protruded member <NUM> is connected to the other side of the fourth recessed member <NUM>, and the other side of the fourth protruded member <NUM> is continuously connected to one side of the fourth flat member <NUM>.

The flat portion, the recessed portion, and the protruded portion described above are continuously connected. Specifically, the first and second flat members <NUM> and <NUM>, the first and second recessed members <NUM> and <NUM>, and the first and second protruded members <NUM> and <NUM> are connected in consecutive order, and a shortest distance d1 between both ends of the first and second recessed members <NUM> and <NUM> is <NUM> equal to a shortest distance d2 between both ends of the first and second protruded members <NUM> and <NUM>.

In addition, the third and fourth flat members <NUM> and <NUM>, the third and fourth recessed members <NUM> and <NUM>, and the third and fourth protruded members <NUM> and <NUM> are connected in consecutive order, and a shortest distance d3 between both ends of the third and fourth recessed members <NUM> and <NUM> is <NUM> equal to a shortest distance d4 between both ends of the third and fourth protruded members <NUM> and <NUM>.

Also, a shortest distance (d1 + d2) from one end of the first and second recessed members <NUM> and <NUM> connected to the first and second flat members <NUM> and <NUM> to the other end of the first and second protruded members <NUM> and <NUM> is <NUM> to <NUM> and preferably <NUM>.

In addition, a shortest distance (d3 + d4) from one end of the third and fourth recessed members <NUM> and <NUM> connected to the third and fourth flat members <NUM> and <NUM> to the other end of the third and fourth protruded members <NUM> and <NUM> is <NUM> to <NUM> and preferably <NUM>.

<FIG> is a perspective view illustrating shapes of the 3D kerf element of the pneumatic tire with a 3D kerf element according to the embodiment of the invention. <FIG> is a perspective view illustrating actual shapes of the 3D kerf element of the pneumatic tire with a 3D kerf element according to the embodiment of the invention.

The 3D kerf element <NUM> of the invention is provided to cause an interlocking phenomenon to occur between the blocks <NUM> applied to a pattern formed at the tread <NUM> of the tire <NUM> such that a ground grip force and handling and braking performances of the tire <NUM> are improved, and the frictional force changes depending on the shape of the 3D kerf element.

In this respect, in the invention, an experiment was carried out, in which the shape of the 3D kerf element <NUM> was realized as a zigzag shape, a trapezoid shape, a wave shape, or the like. <FIG> illustrates the zigzag shape and the trapezoid shape as examples of the shape of the 3D kerf element <NUM>.

<FIG> illustrates 3D kerf elements manufactured to have a zigzag shape, a trapezoid shape, a wave-trapezoid shape, a semi-trapezoid shape in order to evaluate the frictional force depending on the shape of the 3D kerf element <NUM>, before the 3D kerf element is applied to a tire.

In <FIG>, (a) illustrates an exemplary 3D kerf element designed to have a zigzag shape at the surface of the tread <NUM> of the tire <NUM> and a zigzag shape in a depth direction from the surface of the tread <NUM>, (b) illustrates an exemplary 3D kerf element designed to have a trapezoid shape at the surface of the tread <NUM> of the tire <NUM> and a trapezoid shape in the depth direction from the surface of the tread <NUM>, (c) illustrates an inventive 3D kerf element designed to have a wave shape at the surface of the tread <NUM> of the tire <NUM> and a trapezoid shape in the depth direction from the surface of the tread <NUM>, and (d) illustrates an exemplary 3D kerf element designed to have a trapezoid shape at the surface of the tread <NUM> of the tire <NUM> and a semi-trapezoid shape in the depth direction from the surface of the tread <NUM>.

Experimental results thereof are shown in Table <NUM> and Table <NUM> provided below.

Table <NUM> shows results of evaluation of individual samples manufactured of SUS304 plates by performing the bending thereon, the samples having the zigzag shape in (a) of <FIG>, the trapezoid shape in (b) of <FIG>, the inventive wave-trapezoid shape in (c) of <FIG>, and the semi-trapezoid shape in (d) of <FIG>. First, in a dry condition, the 3D kerf element <NUM> has a difference in degree of the frictional force as Wave-Trapezoid Shape > Zigzag Shape = Semi-Trapezoid Shape > Trapezoid Shape, it was confirmed that when the 3D kerf element has the wave-trapezoid shape, the maximum frictional force is generated.

Next, in a wet condition, the 3D kerf element <NUM> has a difference in degree of the frictional force as Wave-Trapezoid Shape = Trapezoid Shape = Zigzag Shape > Semi-Trapezoid Shape, and it was confirmed that when the 3D kerf element has the semi-trapezoid shape, the minimum frictional force is generated.

Lastly, in a snow condition, the 3D kerf element <NUM> has a difference in degree of the frictional force as Trapezoid Shape > Zigzag Shape > Wave-Trapezoid Shape > Semi-Trapezoid Shape, and it was confirmed that when the 3D kerf element has the trapezoid shape, the maximum frictional force is generated.

As a result of evaluation of the frictional force, the frictional force was relatively high with the zigzag shape and the trapezoid shape; however, a defect rate was high due to those complicated shapes when the sample was manufactured of the SUS304 material by performing the bending thereon.

In addition, as a result of evaluation of design strength of the manufactured inventive wave-trapezoid shape and semi-trapezoid shape, the strength of the inventive wave-trapezoid shape was found to be higher than the strength of the semi-trapezoid shape by about <NUM>%, and thus the 3D kerf element having the inventive wave-trapezoid shape was determined to be applied to a mold.

Table <NUM> shows evaluation of snow performance, and the tire <NUM> was manufactured as a <NUM>/45R18V tire for all seasons. As a result of performance evaluation, the snow handling was more improved by <NUM>% than a general kerf, the snow braking was more improved by <NUM>% than the general kerf, and the snow acceleration was more improved by <NUM>% than the general kerf.

According to the above-described configuration, an effect of the invention is as follows. The snow performance can be improved by inserting a 3D kerf element into a kerf groove of a tire tread, the inventive 3D kerf element including a top surface having a wave shape and a side surface having a trapezoid shape.

In addition, according to the above-described configuration, another effect of the invention is as follows. Since one or more 3D kerf elements come into close contact with and are fixed between one or more blocks as being inserted into one or more kerf grooves, an interlocking phenomenon between blocks can occur to improve a ground grip force and handling and braking performances of the tire.

Effects of the invention are to be construed not to be limited to the above-mentioned effects but to include any effect that can be derived from configurations of the invention described in the detailed description of the preferred embodiment and claims of the invention.

The description of the invention described above is provided as an example, and a person of ordinary skill in the art to which the invention pertains can understand that it is possible to easily modify the invention to another embodiment without changing the technical idea or essential feature of the invention. Therefore, the embodiments described above have to be understood as exemplary embodiments in every aspect and not as examples to limit the invention. For example, each configurational element described as a single unit can be realized in a distributed manner. Similarly, the configurational element described in a distributed manner can be realized in a combined manner.

Claim 1:
A pneumatic tire with a 3D kerf element, comprising:
one or more 3D kerf elements (<NUM>); and
a tire (<NUM>) having a tread (<NUM>) and a shoulder (<NUM>) formed at a side surface of the tread (<NUM>),
wherein the tread (<NUM>) has:
one or more grooves (<NUM>) that are sunken toward a center of the tread (<NUM>) and are formed in a circumferential direction of the tire (<NUM>);
one or more kerf grooves (<NUM>) that are sunken toward the center of the tread (<NUM>) and are formed in a central axis direction of the tire (<NUM>); and
one or more blocks (<NUM>) which are divided by the one or more grooves (<NUM>) and the one or more kerf grooves (<NUM>),
wherein the one or more 3D kerf elements (<NUM>) come into close contact with and are fixed between the one or more blocks (<NUM>) as being inserted into the one or more kerf grooves (<NUM>),
wherein a top surface of the 3D kerf elements (<NUM>) has a wave shape which bends alternately one or more times, the top surface being parallel to a surface of the tread (<NUM>), characterized in that
the 3D kerf elements have a trapezoid shape in the depth direction from the surface of the tread (<NUM>).