JP3586045B2 - Studless pneumatic tires - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pneumatic tire, in particular, a central circumferential wide groove extending linearly in the tire circumferential direction at the center of the tread so as to divide the tread into left and right, adjacent to the left and right of the central circumferential wide groove. The tread includes a pair of left and right circumferential ribs extending continuously in the tire circumferential direction and a pair of left and right circumferential narrow grooves extending in the tire circumferential direction adjacent to the circumferential ribs on the outer side in the tire axial direction. Also, the present invention relates to a studless tire used on an icy snowy road surface.
[0002]
[Prior art]
Generally, in the case of studless tires used on icy and snowy roads, in order to improve the performance on snow, the negative rate, that is, the part of the entire tread contact area where there is a groove etc. that is not actually in contact with the tread It is effective to increase the proportion occupied by the area of the area, while on the other hand, in order to improve the performance on ice, the positive rate, that is, the part of the entire apparent tread contact area that has grooves etc. and is not actually in contact with the ground It is effective to increase the area occupied by the area excluding, and the two are in a trade-off relationship.
In the case of studless tires used on icy and snowy roads, a plurality of sipes are arranged in a block formed by a plurality of circumferential grooves extending in the circumferential direction and a number of horizontal grooves intersecting these vertical grooves. Then, the water film is cut at the sipe, and the performance on ice is improved. However, if many sipes are arranged to increase the edge component in order to further improve the performance on ice, the rigidity of the block will be significantly reduced, and the block will bend or fall, causing traction and braking performance on snow. descend.
For these reasons, it has been difficult to achieve both the on-ice performance and the on-snow performance of a studless tire.
[0003]
[Problems to be solved by the invention]
There is a strong demand for improving the performance of studless tires on ice due to a decrease in the friction coefficient (μ) of a frozen road surface due to the recent warming and wintering. It goes without saying that this is a conditional requirement of "without deteriorating on-snow performance", but conventionally, as described above, the on-ice performance of a studless tire is improved without deteriorating on-snow performance. It was extremely difficult.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a studless tire excellent in performance on ice without deteriorating performance on snow by solving the above-mentioned disadvantages of the prior art.
[0005]
[Means for Solving the Problems]
To achieve the above object, the tire according to the present invention is provided at intervals in the tire axial direction, a plurality of circumferential grooves extending in the circumferential direction or substantially in the circumferential direction, and provided at circumferential intervals in the tire. In a pneumatic tire provided with a large number of lateral grooves extending in the axial direction or substantially the axial direction, and a large number of blocks formed in the tread at circumferential intervals with the circumferential grooves and the lateral grooves,
(1) A central circumferential wide groove extending linearly in the tire circumferential direction and having a groove width of 3 to 25% of the tread width is arranged at the center of the tread so as to divide the tread into right and left,
(2) A pair of left and right circumferential ribs extending continuously in the tire circumferential direction and having a rib width of 2.5 to 15% of the tread width are disposed adjacent to the left and right of the central circumferential wide groove. In the circumferential rib, a large number of sipes extending in a direction inclined with respect to the circumferential direction are arranged at equal intervals in the circumferential direction ,
(3) Long sides that extend at a small angle of 1 to 30 degrees with respect to the circumferential direction and short sides that extend at a large angle of 20 to 90 degrees with respect to the circumferential direction are alternately formed. A pair of left and right circumferential narrow grooves extending in a lightning manner with respect to the circumferential direction are disposed adjacent to the circumferential ribs on the outer side in the tire axial direction,
(4) A pair of left and right block rows extending in the tire circumferential direction are arranged adjacent to the circumferentially narrow groove on the outside in the tire axial direction, and the horizontal grooves forming the blocks of the block row are arranged in the circumferential direction. Extending in a direction inclined at an angle of 45 to 85 degrees,
(5) A studless pneumatic tire characterized in that a pair of left and right circumferential grooves extending continuously or substantially linearly in the circumferential direction are arranged between the block row and the tread end. . In order to achieve the above object, in the tire according to the present invention, the length of the long side of the circumferential narrow groove is 10 to 60% of the tread width, and the length corresponding to two blocks of the adjacent block row is used. Preferably, there is. In order to achieve the above object, in the tire according to the present invention, the groove side walls forming the central circumferential wide groove and / or the both-side circumferential grooves may extend linearly and / or zigzag in the circumferential direction. preferable.
[0006]
Generally, a studless tire used on an icy and snowy road surface is required to have a cross groove having a groove volume and an edge component sufficient for improving traction performance in order to improve performance on snow. On the other hand, in order to improve the performance on ice, the positive rate, that is, the proportion of the total area of the apparent tread contact area excluding the part that does not actually contact the ground due to the presence of grooves or the like increases, and the edge component is reduced. It is required to increase the block rigidity.
In the tire according to the present invention, the configuration is as described above, and in the tread central area, in order to secure circumferential rigidity, adjacent to the left and right of the central circumferential wide groove, there is no transverse groove, that is, the tire A pair of left and right circumferential ribs extending continuously in the circumferential direction are arranged. In the case of studless tires used on icy and snowy roads, rubber having a low hardness such as foam rubber is used for the tread rubber, so it is important to ensure tread rigidity. In a tire, a large number of sipes can be arranged on a circumferential rib in order to improve braking performance and traction performance. Also, in order to secure the edge length of the sipe and further improve the braking performance and traction performance, the circumferential rib has a large number of sipes extending in the circumferential direction at substantially equal intervals in the circumferential direction. Are located.
In the tire according to the present invention, a central circumferential wide groove extending linearly in the tire circumferential direction and having a sufficiently wide groove width of 3 to 25% of the tread width is arranged at the center of the tread so as to divide the tread into right and left. As a result, effective snow column shear force is generated, lateral grip performance is secured, and cornering characteristics and straight running performance of the tire are improved.
Thus, in the tire according to the present invention, a large number of central circumferential wide grooves and sipes extending linearly in the tire circumferential direction and having a groove width of 3 to 25% of the tread width are arranged at substantially equal intervals in the circumferential direction, The combination of a pair of left and right circumferential ribs extending continuously in the tire circumferential direction and being arranged in the central region of the tread greatly improves the running performance of the studless tire on an icy and snowy road surface.
[0007]
In the tire according to the present invention, since a pair of left and right circumferential grooves extending continuously or substantially linearly in the circumferential direction are arranged between the block row and the tread end, a strong lateral Power is exerted. Further, in order to exhibit both stronger lateral force and front-rear direction edge force, the tire according to the present invention has a long side and a circumferential side extending at a small angle of 1 to 30 degrees with respect to the circumferential direction. And a pair of left and right circumferential narrow grooves, which are formed by alternately forming short sides extending at a large angle of 20 to 90 degrees with respect to the direction and extending in a lightning-like manner with respect to the circumferential direction. The circumferential rib is disposed adjacent to the outer side in the tire axial direction.
In the tire according to the present invention, a block row is arranged adjacent to the outer side in the tire axial direction of the circumferential narrow groove extending in a lightning manner with respect to the circumferential direction. Since many are arranged at equal intervals, the rigidity tends to decrease by that much. Therefore, in order to reinforce the rigidity of the block row, it is desirable to reduce the groove width at the time of load at least so that the groove closes at the time of load cornering.
In the tire according to the present invention, a pair of left and right block rows extending in the tire circumferential direction is arranged adjacent to the circumferentially narrow groove outside the tire axial direction, and the lateral grooves forming the blocks of the block row are arranged in the circumferential direction. , It extends in a direction inclined at an angle of 45 to 85 degrees with respect to, so that an edge force in the front-rear direction is secured.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The tires of Examples 1 to 3 and the conventional tire according to the present invention will be described in detail below with reference to the drawings. All tire sizes are 185 / 70R14.
[0009]
FIG. 1 is a tread pattern (partial front view) of a tire according to a first embodiment of the present invention.
As shown in the figure, the tire of Example 1 has five circumferential grooves provided at intervals in the tire axial direction and extending in the circumferential direction or substantially in the circumferential direction. Alternatively, the tread is provided with a number of lateral grooves extending substantially in the axial direction, and a number of blocks formed at circumferential intervals with the circumferential grooves and the lateral grooves.
In the tire of the first embodiment, the central circumferential wide groove 1 extending linearly in the tire circumferential direction and having a groove width of 9 mm corresponding to about 6% of the tread width TW has a tread that divides the tread into right and left. A pair of left and right circumferential ribs 4, which are arranged at the center, extend continuously in the tire circumferential direction, and have a rib width of 10 to 15 mm corresponding to about 6 to 9% of the tread width TW, have a central circumferential wide groove 1. A large number of sipes 6 are disposed on the circumferential rib 4 at substantially equal intervals in the circumferential direction, and are arranged at a small angle of 5 degrees with respect to the circumferential direction. A pair of left and right circumferences extending in a lightning-like manner with respect to the circumferential direction, formed by alternately arranging long sides extending at a slant and short sides extending at a large angle of 68 degrees with respect to the circumferential direction. Direction narrow groove 2 is adjacent to the circumferential rib 4 on the outer side in the tire axial direction. A pair of left and right block rows 5 extending in the tire circumferential direction are disposed adjacent to the circumferentially narrow groove 2 on the outer side in the tire axial direction, and the lateral grooves 7 forming the blocks of the block row 5 are circumferentially arranged. A pair of left and right circumferential grooves 3 extending in a direction inclined at an angle of 70 to 74 degrees with respect to the direction and extending continuously linearly in the circumferential direction are arranged between the block row 5 and the tread end TE. Have been.
The length of the long side of the circumferential narrow groove 2 is 59 mm, which corresponds to about 37% of the tread width TW, and the length of the short side of the circumferential narrow groove 2 is 5 mm. The length of the long side of the circumferential narrow groove 2 is a length corresponding to two blocks of the adjacent block row 5 as illustrated.
The tire of the second embodiment is substantially the same as the tire of the first embodiment except that the outer side wall in the tire axial direction of the groove side walls forming the circumferential grooves 3 on both sides extends in the circumferential direction in a zigzag manner. .
The tire of Example 3 is substantially the same as the tire of Example 2 except that the left and right groove side walls forming the central circumferential wide groove 1 extend in a circumferential direction in a zigzag manner.
[0010]
FIG. 2 is a tread pattern (partially front view) of the tire of Conventional Example 1.
As shown in the drawing, a conventional tire has six circumferential grooves provided at intervals in the tire axial direction and extending in the circumferential direction, and two circumferential grooves extending in the circumferential direction while winding in a large wavy manner, The tread is provided with a number of lateral grooves provided at intervals in the circumferential direction and extending in the tire axial direction, and a number of blocks formed at intervals in the circumferential direction by the circumferential grooves and the lateral grooves.
[0011]
A comparison test of the on-ice performance and the on-snow performance was performed on the tires of Examples 1 to 3 according to the present invention and the conventional tire.
The test conditions were 1.9 Kgf / cm ² for the tire internal pressure, and the feeling on snow was a comprehensive evaluation of braking performance, starting performance, straightness, and cornering performance on a test course on a snow-covered snowy road. Characteristics are comprehensive evaluation of braking performance, starting performance, straightness, and cornering performance on a test track on an icy road surface. Brake performance on ice is measured when the vehicle is fully braked on a icy road at a speed of 20 km / h. The traction performance on ice is an evaluation result of a required time when the vehicle travels 20 m from a stationary state on an ice plate.
[0012]
When the evaluation results are shown as an index with the result of the conventional pneumatic tire as 100, the on-snow feeling characteristics and the on-ice feeling characteristics are all 120 for the tires of Examples 1 to 3, and the on-ice braking performance is as described above. The tires of Examples 1 to 3 were all 125. The traction performance on ice was 115 for the tires of Examples 1 and 2 and 120 for the tire of Example 3 above.
The higher the number, the better the performance.
[0013]
【The invention's effect】
From the above results, it can be seen that the tire of the example according to the present invention is a tire having better on-ice performance and on-snow performance than the conventional tire.
[Brief description of the drawings]
FIG. 1 is a tread pattern (partial front view) of a tire according to the present invention.
FIG. 2 is a tread pattern (partial front view) of a conventional tire.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Central wide groove 2 Peripheral narrow groove 3 Both circumferential grooves 4 Peripheral rib 5 Block row 6 Sipe 7 Lateral groove TW Tread width TE Tread end

Claims (3)

A plurality of circumferential grooves that are provided at intervals in the tire axial direction and extend in the circumferential direction or substantially the circumferential direction, and a large number of lateral grooves that are provided at intervals in the circumferential direction and extend in the tire axial direction or the substantially axial direction, In a pneumatic tire provided with a large number of blocks formed on the tread at intervals in the circumferential direction with the circumferential groove and the lateral groove,
(1) A central circumferential wide groove extending linearly in the tire circumferential direction and having a groove width of 3 to 25% of the tread width is arranged at the center of the tread so as to divide the tread into right and left,
(2) A pair of left and right circumferential ribs extending continuously in the tire circumferential direction and having a rib width of 2.5 to 15% of the tread width are disposed adjacent to the left and right of the central circumferential wide groove. In the circumferential rib, a large number of sipes extending in a direction inclined with respect to the circumferential direction are arranged at equal intervals in the circumferential direction ,
(3) Long sides that extend at a small angle of 1 to 30 degrees with respect to the circumferential direction and short sides that extend at a large angle of 20 to 90 degrees with respect to the circumferential direction are alternately formed. A pair of left and right circumferential narrow grooves extending in a lightning manner with respect to the circumferential direction are disposed adjacent to the circumferential ribs on the outer side in the tire axial direction,
(4) A pair of left and right block rows extending in the tire circumferential direction are arranged adjacent to the circumferentially narrow groove on the outside in the tire axial direction, and the horizontal grooves forming the blocks of the block row are arranged in the circumferential direction. Extending in a direction inclined at an angle of 45 to 85 degrees,
(5) A studless pneumatic tire characterized in that a pair of left and right circumferential grooves extending continuously or substantially linearly in the circumferential direction are arranged between the block row and the tread end. 2. The studless air-filled pneumatic tire according to claim 1, wherein the length of the long side of the circumferential narrow groove is 10 to 60% of the tread width and corresponds to two blocks of the adjacent block row. tire. The studless pneumatic tire according to claim 1, wherein a groove side wall forming the central circumferential wide groove and / or the both circumferential grooves extends linearly and / or zigzag in a circumferential direction. .

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