PNEUMATIC TIRE

A pneumatic tire includes a tread portion having a tread surface for making contacting with a road surface and a groove recessed inward from the tread surface and extending along a circumferential direction, and a plurality of noise reflectors protruding from the groove and disposed spaced apart from each other along the circumferential direction. The groove includes a groove bottom surface spaced apart by a predetermined distance from the tread surface in a radial direction of the pneumatic tire and a plurality of groove side surfaces connected to the groove bottom surface and each including a connection curved surface having a predetermined curvature. Each of the noise reflectors includes a support surface supported by the connection curved surface and the groove bottom surface and a protrusion surface located on a side opposite to the support surface and disposed to be spaced apart from the connection curved surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2021-0001500 filed on Jan. 6, 2021, the disclosures of which are incorporated herein in its entirety by reference for all purposes.

TECHNICAL FIELD

The present disclosure relates to a pneumatic tire, and more particularly, a pneumatic tire formed so that noise generated from a groove is reduced by disposing a noise reflector in the groove.

BACKGROUND

Tires are mounted on a variety of vehicles, from small vehicles to heavy-duty vehicles, to support loads of the vehicles, and to perform a power transmission function that transmit power of the vehicles to the ground and a brake function, as well as functions for dampening vibrations and shocks from the ground that occur when the vehicles travel. In order to perform the functions of the tires, an internal air pressure is applied to the tires which play an important part in traveling and braking of the vehicles.

SUMMARY

The present disclosure provides a pneumatic tire formed so that noise generated from a groove can be reduced.

In accordance with an embodiment of the present disclosure, there is provided a pneumatic tire for reducing noise including: a tread portion including: a tread surface for making contacting with a road surface; and a groove recessed inward from the tread surface and extending along a circumferential direction of the pneumatic tire; and a plurality of noise reflectors protruding from the groove and disposed spaced apart from each other along the circumferential direction of the pneumatic tire, wherein the groove includes: a groove bottom surface spaced apart by a predetermined distance from the tread surface in a radial direction of the pneumatic tire; and a plurality of groove side surfaces connected to the groove bottom surface and each including a connection curved surface having a predetermined curvature, wherein each of the noise reflectors includes: a support surface supported by the connection curved surface and the groove bottom surface; and a protrusion surface located on a side opposite to the support surface and disposed to be spaced apart from the connection curved surface, and wherein the protrusion surface includes a protruding curved surface having a shape which goes away from a central virtual plane perpendicular to the groove bottom surface as it goes from the groove bottom surface toward an outer side in the radial direction of the pneumatic tire.

The pneumatic tire may have a meridian plane passing through a center of the pneumatic tire and perpendicular to an axial direction of the tire, the plurality of groove side surface may include a first groove side surface and a second groove side surface, the first groove side surface and the second groove side surface may be inclined so that an axial gap therebetween decreases as it goes to the groove bottom surface from the tread surface, and each of the first groove side surface and the second groove side surface may extend to be inclined with respect to the meridian surface.

A height of the noise reflector in the radial direction may be ½ or more of a length between the tread surface and the groove bottom surface.

A thickness of the noise reflector in the circumferential direction may be equal to or smaller than a separation distance between centers of the plurality of noise reflectors in the circumferential direction.

The tread portion may further include a sipe recessed inward from the tread surface and extending in a direction deviating from an extension direction of the groove to be connected to the groove, and the noise reflector may be disposed to be spaced apart from the sipe in the circumferential direction of the pneumatic tire.

According to embodiments of the present disclosure, a noise reflector may be disposed in the groove of the pneumatic tire, and thus, noise generated by the groove may be reduced.

DETAILED DESCRIPTION

With the change of the times, a proportion of unpaved roads gradually decreases, vehicles without an internal combustion engine such as electric vehicles are popularized, and noise is recently being regarded as important among the main performance of tires. The existing tire includes a tread portion in contact with a road surface, and a groove may be formed in the tread portion. The groove improves drainage. However, air flows in the groove as the vehicle travels, and thus, pipe resonance may be generated by the flowing air. There is a problem that the pipe resonance causes noise.

Hereinafter, specific embodiments for implementing the technical spirit of the present disclosure will be described with reference to the accompanying drawings.

In describing the embodiments of the present disclosure, the detailed descriptions of well-known functions or configurations will be omitted if it is determined that the detailed descriptions of well-known functions or configurations may unnecessarily make obscure the spirit of the present disclosure.

When an element is referred to as being ‘connected’ to, or ‘contacted’ with another element, it should be understood that the element may be directly connected to, or contacted with the other element, but that other elements may exist in the middle.

The terms used in the present disclosure are only used for describing specific embodiments, and are not intended to limit the present disclosure. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In addition, in the present disclosure, expressions such as an upper side, a lower side, and a side surface are described with reference to the drawings, and it should be noted in advance that if the direction of the object is changed, it may be expressed differently. For the same reason, some components in the accompanying drawings are exaggerated, omitted, or schematically illustrated, and the size of each component does not entirely reflect the actual size.

The terms used herein, including ordinal numbers such as “first” and “second” may be used to describe, and not to limit, various components. The terms simply distinguish the components from one another.

The meaning of “including” as used in the specification specifies a specific characteristic, region, integer, step, action, element and/or component, but does not exclude the existence or addition of other specific characteristic, region, integer, step, action, element, component and/or group.

Meanwhile, a radial direction “R” described below means a radial direction of a tire. An axis may mean a rotation axis of the tire, and an axial direction “A” means a direction parallel to the rotation axis of the tire. The axial direction does not necessarily pass through a center of the rotation axis of the tire, and includes a direction parallel to an extension direction of the rotation axis of the tire. In addition, a circumferential direction “C” is a direction along an outer circumferential surface of the tire and means a direction perpendicular to the radial direction. The circumferential direction may be either the clockwise direction or counterclockwise direction when viewed from a side surface of the tire.

Meanwhile, unless otherwise specified, the directions include both positive and negative directions.

Hereinafter, a pneumatic tire1according to a first embodiment of the present disclosure will be described with reference to the drawings.

Referring toFIG. 1, the pneumatic tire1according to the first embodiment of the present disclosure may include a tread portion100and a noise reflector200.

The tread portion100is disposed on an outer portion of the pneumatic tire1, corresponds to a thick rubber layer having a configuration in which the road surface is directly grounded, and may be formed of a rubber material having strong cut, impact, and abrasion resistance to protect an inside of the tire. A surface of the tread portion100may extend toward a side wall (not illustrated) of the pneumatic tire1as a portion contacting the road surface. In addition, the tread portion100may include a groove110and a sipe120to improve water discharge performance, conditional friction performance, or the like.

Referring further toFIG. 2, the groove110may be recessed inward from the surface of the tread portion100. The groove110may be formed in the circumferential direction or the axial direction of the pneumatic tire1, or may be extended in a direction deviating from the circumferential direction or the axial direction of the pneumatic tire1. Hereinafter, the groove110will be described on the basis of being formed in the circumferential direction, but is not limited thereto. In addition, the groove110may include a plurality of grooves110and the plurality of grooves110may be disposed to be spaced apart from each other. For example, the plurality of grooves110formed in the circumferential direction of the pneumatic tire1may be disposed to be spaced apart from each other in the axial direction of the pneumatic tire1. In addition, a width of the groove110perpendicular to an extension direction of the groove110may be 1.1 mm or more. The groove110may include a plurality of groove side surfaces111and112and a groove bottom surface113.

Referring further toFIG. 3, the plurality of groove side surfaces111and112may be recessed from the surface of the tread portion100. The plurality of groove side surfaces111and112are connected to the groove bottom surface113and portions connected to the groove bottom surface113may have a predetermined curvature. The predetermined curvature may be equal to or less than R5(5 mm), for example. In addition, the plurality of groove side surfaces111and112may include a first groove side surface111and a second groove side surface112. The second groove side surface112may be disposed at a position more spaced apart from a center of the tread portion100than the first groove side surface111. For example, in the plurality of groove side surfaces111and112of the groove110, the second groove side surface112located on one side (left side ofFIG. 1) in the axial direction of the pneumatic tire1with respect to a meridian plane “m” is located on one side (left side ofFIG. 1) of the first groove side surface111in the axial direction of the pneumatic tire1. In addition, in the plurality of groove side surfaces111and112of the groove110, the second groove side surface112located on the other side (right side ofFIG. 1) in the axial direction of the pneumatic tire1with respect to the meridian surface “m” is located on the other side (right side ofFIG. 1) of the first groove side surface111in the axial direction of the pneumatic tire1. In the present specification, the meridian plane “m” refers to a plane perpendicular to the axial direction while passing through a center of the pneumatic tire1. In other words, in each of the grooves110, the second groove side surface112is disposed to be farther from the meridian surface “m” than the first groove side surface111in the axial direction of the pneumatic tire1.

In addition, the first groove side surface111and the second groove side surface112may be inclined so that a gap therebetween decreases in a direction closer to the groove bottom surface113. For example, an angle “g” at which the first groove side surface111and the second groove side surface112are inclined may be in a range of 5° to 30° with respect to the radial direction of the pneumatic tire1. In other words, the angle “g” formed between each of the first groove side surface111and the second groove side surface112and the meridian surface “m” may be in a range of 5° to 30°. In addition, the plurality of groove side surfaces111and112may include connection curved surfaces111aand112aand inclined surfaces111band112b,respectively.

As described above, the connection curved surfaces111aand112aare portions of the groove side surfaces that are connected to the groove bottom surface113and formed with a predetermined curvature. The connection curved surfaces111aand112amay support the noise reflector200. The first groove side surface111may include the first connection curved surface111aconnected to the groove bottom surface113, and the second groove side surface112may include the second connection curved surface112aconnected to the groove bottom surface113.

The inclined surfaces111band112bmay be located between the connection curved surfaces111aand112aand the surface of the tread portion100. In addition, the inclined surfaces111band112bare surfaces that may be connected to a second connection unit220bof the noise reflector200to be described below. In addition, the inclined surfaces111band112bmay be inclined to form the angle “g” with the meridian surface “m” as described above. In other words, the first groove side surface111may include the first inclined surface111bconnected to the first connection curved surface111a,and the second groove side surface112may include the second inclined surface112bconnected to the second connection curved surface112a.In addition, the first inclined surface111band the second inclined surface112bmay be inclined so that an axial gap therebetween gradually decreases toward the groove bottom surface113. For example, an angle “g1” between the first inclined surface111band the meridian surface “m” and an angle g2between the second inclined surface112band the meridian surface “m” may be in a range of 5° to 30°. The angle “g1” and the angle “g2” may be the same or different from each other.

The groove bottom surface113may be connected to the plurality of groove side surfaces111and112and may extend in a direction parallel to the surface of the tread portion100. In other words, the groove bottom surface113may be located between the first groove side surface111and the second groove side surface112.

Referring further toFIG. 4, the sipe120may be recessed inwardly from the surface of the tread portion100, and may be connected to the groove110by extending in a direction that deviates from a direction in which the groove110is extended. For example, the sipe120may extend in a direction close to the sidewall or in the axial direction of the pneumatic tire1. In addition, a width of the sipe120perpendicular to an extension direction of the sipe120may be 1.0 mm or less. One side of the sipe120may be connected to the first groove side surface111or the second groove side surface112of the groove110. In addition, the sipe120may be spaced apart from the noise reflector200in the circumferential direction of the pneumatic tire1. In addition, some of the plurality of sipes120may be connected to one groove110. The plurality of sipes120are connected to the groove110, and thus, a plurality of pitches130may be formed on the surface of the tread portion100. The plurality of noise reflectors200may be disposed between the plurality of sipes120. In addition, the noise reflector200may be disposed to be spaced apart from the sipe120in the circumferential direction. For example, a gap “E” between the sipe120and the noise reflector200may be in a range between 1.5 mm and 3.0 mm. The gap “E” may be a gap between the sipe120and the noise reflector200formed closest to the sipe120among the plurality of noise reflectors200. The sipe120may include a plurality of sipe side surfaces121and122and a sipe bottom surface123.

The plurality of sipe side surfaces121and122may be recessed inward from the surface of the tread portion10. In addition, the plurality of sipe side surfaces121and122may be connected to any one of the plurality of groove side surfaces111and112. The gap “E” between the sipe120and the noise reflector200described above by the plurality of sipe side surfaces121and122may be a gap between any one of the plurality of noise reflector200and any one of the plurality of sipe side surfaces121and122formed closest thereto.

The sipe bottom surface123is connected to the plurality of sipe side surfaces121and122and may be formed in a direction parallel to the surface of the tread portion100. In other words, the sipe bottom surface123may be located between the plurality of sipe bottom surfaces123. At least a portion of the plurality of sipe bottom surfaces123may be disposed at different positions according to the length of the plurality of sipe side surfaces121and122being recessed from the surface of the tread portion100. In other words, the sipe bottom surface123may be connected to any one of the plurality of groove side surfaces111and112or the groove bottom surface113.

Referring further toFIGS. 5A to 5C, the noise reflector200may reduce noise by reducing pipe resonance generated by air flowing in the groove110. The noise reflector200may protrude from the groove110, and the plurality of noise reflectors200may be provided and disposed to be spaced apart from each other along the circumferential direction of the pneumatic tire1. In addition, the noise reflector200may protrude from at least one of the first groove side surface111and the second groove side surface112. For example, the noise reflectors200may protrude from the first groove side surface111and the groove bottom surface113and may be spaced apart from each other along the circumferential direction of the pneumatic tire1. As another example, the plurality of noise reflectors200may protrude from the second groove side surface112and the groove bottom surface113and may be spaced apart from each other along the circumferential direction of the pneumatic tire1. As still another example, first noise reflectors200awhich are some of the plurality of noise reflectors200may protrude from the first groove side surface111and the groove bottom surface113and may be disposed to be spaced apart from each other along the circumferential direction of the pneumatic tire1, and second noise reflectors200bwhich are the remainder thereof may protrude from the second groove side surface112and the groove bottom surface113and may be spaced apart from each other along the circumferential direction of the pneumatic tire1. In addition, the first noise reflectors200aand the second noise reflectors200bmay be spaced apart from each other.

Referring further toFIGS. 3, 4 and 6, a height “b” of the noise reflector200may be formed to be ½ or more of a length “B” from the surface of the tread portion100to the groove bottom surface113in the radial direction of the pneumatic tire1. For example, the height “b” of the noise reflector200may be 65% or more and 75% or less of the length “B” from the surface of the tread portion100to the groove bottom surface113in the radial direction of the pneumatic tire1. A thickness “W” of the noise reflector200in the circumferential direction of the pneumatic tire1may be 3% to 10% or less of a length of the gap between the plurality of sipes120or the pitch between the plurality of sipes120, but is not limited thereto. For example, the thickness W of the noise reflector200may be in a range of 1.0 mm to 3.0 mm In addition, the thickness W of the noise reflector200may be less than or equal to a circumferential separation distance L between the centers of the plurality of noise reflectors200. In other words, the circumferential separation distance L between the centers of the plurality of noise reflectors200may be 1 or more times and less than 2 times the thickness “W” of the noise reflector200. For example, the separation distance L may be 1.0 mm or more and 6.0 mm or less. In addition, the plurality of noise reflectors200may be disposed in the groove110in a number of 300 or more and 1000 or less. The noise reflector200may include a support surface210and a protrusion surface220.

The support surface210may be supported by the groove bottom surface113and one of the first groove side surface111and the second groove side surface112. In addition, the support surface210may also be formed into a curved surface corresponding to the connection curved surfaces111aand112a.In other words, the support surface210may be formed in a curved surface to be supported by the connection curved surfaces111aand112a,the inclined surfaces111band112b,and the groove bottom surface113. For example, the support surface210may be supported by the first connection curved surface111a,the first inclined surface111b,and the groove bottom surface113, or may be supported by the second connection curved surface112a,the second inclined surface112b,and the groove bottom surface113.

The protrusion surface220may be located on a side opposite to the support surface210and may be spaced apart from the connection curved surfaces111aand112a.The protrusion surface220may be connected to the groove bottom surface113and one of the first groove side surface111and the second groove side surface112. The protrusion surface220may include one side that is connected to the groove bottom surface113and the other side that is located on a side opposite to one side and connected to the first groove side surface111or the second groove side surface112. Hereinafter, one side of the protrusion surface220will be referred to as a first connection portion220a,and the other side of the protrusion surface220will be referred to as a second connection portion220b.The first connection portion220aand the second connection portion220bof the protrusion surface220may be connected to the support surface210. In addition, the protrusion surface220may include a protruding curved surface having a shape that goes away from a first virtual surface “V”, which is a virtual plane perpendicular to the groove bottom surface113, toward an outer side in the radial direction of the pneumatic tire1. In other words, the first connection portion220amay be closer to the first virtual surface V than the second connection portion220b.In addition, the protrusion surface220may be in contact with a second virtual surface “S”, which is a virtual plane that is perpendicular to the groove bottom surface113and passes through the first connection portion220aof the protrusion surface220.

A length “a” from the second virtual surface “S” to the second connection portion220bof the protrusion surface220based on the axial direction of the pneumatic tire1may be 20% or more and 30% or less of a maximum gap “I” between the first groove side surface111and the second groove side surface112. In other words, the noise reflector200may be 20% or more and 30% or less of the maximum distance “I” between the first groove side surface111and the second groove side surface112and may protrude from the groove bottom surface113and any one of the first groove side surfaces111and the second groove side surface112.

Hereinafter, operations and effects of the pneumatic tire1according to the first embodiment of the present disclosure will be described with further reference toFIGS. 7 to 9.

Since the noise reflector200is disposed in the groove110of the pneumatic tire1according to the first embodiment of the present disclosure, noise caused by the flow of air flowing in the groove110can be reduced.

V1, V2, and V3illustrated inFIG. 7are grooves having different shapes, and V4and V5are grooves in which different types of noise reflectors are disposed. Even when the shapes of the grooves are different, there is no change in a noise level and a noise level per unit volume. Meanwhile, as the noise reflector is provided, the noise level per unit volume was improved by 4% in V4and by 6% or more in V5. In addition, in the noise level and the noise level per unit volume, V5including the noise reflector formed long in the radial direction of the pneumatic tire1were further improved than V4. In other words, as the noise reflector200is provided on the groove bottom surface113and the groove side surfaces111and112as in V5, noise can be efficiently reduced.

In addition, as illustrated inFIG. 8, when the noise reflector200is applied to the groove110, noise can be reduced in a band of 500 hz to 800 hz than when the noise reflector200is not applied.

As illustrated inFIG. 9, even when the noise reflector200is disposed in the groove110, drainage performance of the groove110is hardly affected. V1illustrated inFIG. 9represents the drainage performance of the tire in which the noise reflector is not present, and V5represents the drainage performance of the tire to which the noise reflector200of the present disclosure is applied. In addition, V2, V3, and V4represent the tire drainage performance in a state in which protrusions of different shapes are applied to the groove. ST represents tire drainage performance in a straight traveling state, and CO represents tire drainage performance in a cornering state. According toFIG. 9, it can be seen that V5to which the noise reflector200of the present disclosure is applied has drainage performance better than those of V2, V3, and V4in ST and CO states. In addition, the drainage performance of V5may be close to the drainage performance of V1. In other words, even when the noise reflector200of the present disclosure is applied to the groove110, the groove110can efficiently discharge water.

Hereinafter, a pneumatic tire1according to a second embodiment of the present disclosure will be described with reference toFIGS. 10A and 10B. As compared with the first embodiment described above, in the second embodiment of the present disclosure, at least one of the plurality of groove side surfaces111and112may further include surface connection surfaces111cand112c.Hereinafter, these differences will be mainly described, and the same description and reference numerals refer to the above-described embodiments.

The surface connection surfaces111cand112cmay be located between the inclined surfaces111band112band the surface of the tread portion100. A length “d” of each of the surface connection surfaces111cand112cin the radial direction of the pneumatic tire1may be 25% or less of a length “B” from the surface of the tread portion100to the groove bottom surface113. In addition, the surface connection surfaces111cand112cmay be inclined to be further away from the virtual surface “V” in order to form a predetermined angle “f” with the inclined surfaces111band112b.For example, the angle “f” of each of the inclined surface connection surfaces111cand112cmay be 30° or less based on the inclined surfaces111band112b.In other words, the surface connection surfaces111cand112cmay be inclined more than the inclined surfaces111band112bwith respect to the virtual surface V.

These surface connection surfaces111cand112cmay be included in one or more of the plurality of groove side surfaces111and112. As an example, referring toFIG. 10A, the first groove side surface111may include a first surface connection surface111cdisposed between the first inclined surface111band the surface of the tread portion100, and the second groove side surface112may include a second surface connection surface112cdisposed between the second inclined surface112band the surface of the tread portion100. As another example, referring toFIG. 10B, the first groove side surface111may include a first surface connection surface111c,and the second inclined surface112bof the second groove side surface112may be directly connected to the surface of the tread portion20. As still another example, the second groove side112may include a second surface connection surface112c,and the first inclined surface111bof the first groove side surface111may be directly connected to the surface of the tread portion100. In addition, the angle “f1” between the first surface connection surface111cand the first inclined surface111band the angle “f2” between the second surface connection surface112cand the second inclined surface112bmay be formed equal to or different from each other.

Hereinafter, operation and effects of the pneumatic tire1according to the second embodiment of the present disclosure will be described.

When the noise reflector200is applied to the groove110, an area of the groove110may be reduced, and thus, the drainage performance may be reduced compared to V1as described above. When at least one of the plurality of groove side surfaces111and112includes the surface connection surfaces111cand112c,an area of the groove110can be further secured (the area is increased), and thus, reduced drainage performance can be supplemented.

The examples of the present disclosure have been described above as specific embodiments, but these are only examples, and the present disclosure is not limited thereto, and should be construed as having the widest scope according to the technical spirit disclosed in the present specification. A person skilled in the art may combine/substitute the disclosed embodiments to implement a pattern of a shape that is not disclosed, but it also does not depart from the scope of the present disclosure. In addition, those skilled in the art can easily change or modify the disclosed embodiments based on the present specification, and it is clear that such changes or modifications also belong to the scope of the present disclosure.