JPH08318708A - Pneumatic tire provided with slant groove - Google Patents

Abstract

PURPOSE: To reduce the noise of a tire by forming a projection body extended from a thread surface toward a groove bottom on the side wall of a slant groove installed on a tread periphery at some intervals in a periphery direction and forming a sipe so as to divide this projection body. CONSTITUTION: The tread pattern of a tire is provided with slant grooves 1 extended in a 90 deg. slanted direction for a tire periphery direction and these many slant grooves 1 are installed on a tread periphery at some intervals in a periphery direction and many blocks 2, 3 are formed on the tread periphery by these slant grooves 1. As the rotation direction of the tire is R direction, the block 3 is grounded in advance at the tire rolling time and the block 2 is grounded later. Four stripes of projection bodies 4 extended from the tread surface toward the groove bottom are formed on respective slant grooves 1 on the side wall of the block 2 grounded later at least at the tire rolling time out of the side walls of the slant grooves 1 and the spies 5 are formed on respective projection bodies 4 so as to divide the projection bodies 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire provided with an inclined groove extending in a direction inclined with respect to the circumferential direction.

[0002]

2. Description of the Related Art In general, a pneumatic tire provided with an inclined groove extending in a direction inclined with respect to a circumferential direction is more tired during traveling than a pneumatic tire provided with a circumferential groove extending parallel to the circumferential direction. The noise generated from the building is large, and there is a strong demand to reduce the noise. In other words, the block type or lug type tread pattern generates more noise from the tire during traveling than the rib type tread pattern. Pitch variation has been known as a technique for reducing tire noise, and has been put to practical use. This is a method for reducing tire noise based on the theory of frequency modulation, in which the circumferential length (pitch) of the minimum unit pattern that constitutes the pattern is set to two or more types, and This is a technique for reducing tire noise, in which the noise generated from the tire is dispersed into many sidebands having a low sound pressure level by appropriately arranging the tires.

[0003]

Strictly speaking, however, this pitch variation technique is a technique for making tire noise hard to hear by widely distributing the frequency of tire noise, and never the energy of noise itself. It is not decreasing.

An object of the present invention is to solve the above-mentioned problems of the prior art and to reduce the energy itself of noise generated from a pneumatic tire having an inclined groove extending in a direction inclined with respect to the circumferential direction. To reduce the tire noise in the original sense.

[0005]

In order to achieve the above object, the pneumatic tire of the present invention is a pneumatic tire provided with an inclined groove extending in a direction inclined with respect to the circumferential direction. A large number of the inclined grooves are provided on the tread circumference at intervals in the circumferential direction, and (2) among the side walls of the inclined groove, at least the side wall that comes into contact with the tire after rolling is extended from the tread surface toward the groove bottom. At least one ridge is formed in each groove, and (3) the sipe is formed so as to divide the ridge, which is a pneumatic tire.

In order to achieve the above object, in the pneumatic tire of the present invention, the protrusion height of the protrusion formed on the side wall of the inclined groove is 10 to 50% of the groove width of the inclined groove, It is preferable that the angle of the protrusions is −45 to +45 degrees with respect to the tread normal. In order to achieve the above-mentioned object, the pneumatic tire of the present invention is characterized in that the length of the sipe is 1 to 10 times the projection height of the projection strip, and the depth of the sipe is the groove depth of the inclined groove. It is preferably 10 to 90%.

[0007]

[Function] Noise generated while the tire is running includes "groove air pumping noise", "block or lug vibration noise" and "other noise (ground friction noise, tire vibration due to road surface irregularities). Sound, or air-pumping noise in recesses on the road surface, etc.) ”, but it is the former two that cause patterns such as lugs, ribs or blocks formed on the tread surface of tires by grooves. . Further, in a tire provided with a block pattern or a lug pattern, the "block or lug vibration sound" tends to be loud. For pneumatic tires with a block or lug pattern, when the tire rolls, the block or lug collides with the road surface when the discontinuity on the tread rubber surface that is the boundary between the block and the lug and lug touches the ground. Then, the impact force causes the block or lug to vibrate and emit a sound (block or lug excitation sound). Sound emission acts as a speaker, so to speak, with the side walls of the tire and the tread surface acting as a diaphragm.

In a pneumatic tire provided with an inclined groove extending in a direction inclined with respect to the circumferential direction, among the side walls of the inclined groove, the side wall which comes into contact with the ground later when the tire rolls collides with the road surface just when the ground is depressed. The impact force causes the block or lug to vibrate and emit the loudest sound.
As described above, in the pneumatic tire of the present invention, (1) a large number of the inclined grooves are provided on the circumference of the tread at intervals in the circumferential direction, and (2) at least the tire rolling on the side wall of the inclined groove. At least one projecting strip extending from the tread surface toward the groove bottom is formed in each groove on the side wall which is sometimes grounded later, and (3) since the sipe is formed so as to divide the projecting strip, The rigidity of the side wall of the inclined groove that emits the loudest sound is weakened. As a result, the input level to the block when the vehicle collides with the road surface when stepping on the ground is reduced, and the level of radiated sound is also reduced.

In the pneumatic tire of the present invention, the protrusion height of the protrusion formed on the side wall of the inclined groove is 10 to 50% of the groove width of the inclined groove, and the angle of the protrusion is the tread normal line. On the other hand, it is preferably −45 to +45 degrees. When the protrusion height of the protrusion formed on the side wall of the inclined groove is smaller than 10% of the groove width of the inclined groove, it is not possible to reduce the input level to the block when the tire collides with the road surface when stepping on the ground. On the other hand, when the protrusion height of the protrusions is greater than 50% of the groove width of the inclined groove, the groove width becomes narrow and the wet performance (drainability) deteriorates. When the angle of the ridges is smaller than −45 with respect to the tread normal, the rigidity of the ridges becomes too low, and the ridges with low rigidity serve as the core to cause uneven wear. If the body angle is greater than +45 degrees with respect to the tread normal, the rigidity of the ridges becomes too great, and the effect of reducing the input level to the block when the tire collides with the road surface when stepping on the ground is diminished.

In the pneumatic tire of the present invention, the length of the sipe is 1 to 10 times the height of the protrusion of the protrusion and the depth of the sipe is 10 to 10 times the groove depth of the inclined groove. It is preferably 90%. If the length of the sipe is less than 1 time the protrusion height of the ridge, the role of lowering the rigidity and relaxing the input energy becomes insufficient, while the length of the sipe is less than the protrusion height of the ridge. When it is more than 10 times, the steering stability of the tire deteriorates due to the decrease in rigidity of the block body. If the depth of the sipe becomes less than 10% of the groove depth of the inclined groove, the role of lowering the rigidity and relaxing the input energy becomes insufficient, while the depth of the sipe becomes less than 90% of the groove depth of the inclined groove. When the tire is large, the sipe opens when the tire touches the ground, and uneven wear is likely to occur.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a partially enlarged front view of a tread pattern of a pneumatic tire for passenger cars according to the embodiment of the present invention. 225 / 50R16. The tread pattern of the tire of the embodiment is provided with inclined grooves 1 extending in a direction inclined by 90 degrees with respect to the tire circumferential direction, and a large number of these inclined grooves 1 are provided on the tread circumference at intervals in the circumferential direction. A large number of blocks 2 and 3 are formed on the tread circumference by the inclined groove 1. Since the tire rotates in the direction of the arrow R, the block 3 comes into contact with the ground first and the block 2 comes into contact with the ground when the tire rolls. Among the side walls of the inclined groove 1, on the side wall of the block 2 that comes into contact with the ground later when the tire rolls, the protrusion strip 4 extending from the tread surface toward the groove bottom.
4 are formed in each of the slanted grooves 1, and the sipe 5 is formed on each ridge 4 so as to divide the ridge 4.
Are formed. Three similar protruding strips are formed on the side wall of the block 3 that first comes into contact with the ground when the tire rolls, but this is not an essential constituent requirement of the present invention. The projection height H of the projection strip 4 formed on the side wall of the inclined groove 1 is
The groove width W is 25%, and the angle of the protrusion 4 is 0 degree with respect to the tread normal line N. Sipe 5 provided on the protrusion 4
Is twice as long as the projection height H of the projection strip 4, and the depth of the sipe 5 is 50% of the groove depth D of the inclined groove 4.

FIG. 2 shows an example of a modified design of the projection strip 4, wherein the tip of the projection strip 4 is arcuate, and the angle of the projection strip 4 is +5 degrees with respect to the tread normal N. FIG. 3 is an example of a modified design of the protruding strips 4, the protruding strips 4 are trapezoidal, and the angle of the protruding strips 4 is −10 with respect to the tread normal N.
It is degree.

The pneumatic tire of the conventional example is the same as the pneumatic tire of Example 1 except that neither the protrusions 4 nor the sipes 5 are provided on the blocks 2 and 3.

A tire noise evaluation test was carried out on the pneumatic tires of the examples according to the present invention and the pneumatic tires of the conventional examples based on the automobile standard tire noise test method JASOC606. The test conditions are a rim of 8 J × 16, a tire internal pressure of 3.1 kgf / cm 2, a load of 500 kgf and a speed of 60 km / h. The measurement item is noise (sound pressure level) in all frequency bands.

According to the evaluation results, the noise (overall sound pressure level) of the pneumatic tires of the examples according to the present invention in all frequency bands is reduced by 1.8 dB as compared with the noise of the pneumatic tires of the conventional examples. It turned out.

[0016]

From the above evaluation results, it can be seen that the pneumatic tires of the examples according to the present invention have significantly reduced tire noise as compared with the pneumatic tires of the conventional examples.

[Brief description of drawings]

FIG. 1 is a partially enlarged front view of a tread pattern of a pneumatic tire according to the present invention.

FIG. 2 is a partially enlarged front view of the tread pattern of the pneumatic tire according to the present invention.

FIG. 3 is a partially enlarged front view of the tread pattern of the pneumatic tire according to the present invention.

[Explanation of symbols]

 1 Inclined groove 2 Block 3 Block 4 Projection strip 5 Sipe 6 Block d Sipe depth D Inclined groove depth H Projection height H L Sipe length N Tread normal R Tire rotation direction W Inclined groove Groove width

Claims (5)

[Claims] 1. A pneumatic tire provided with an inclined groove extending in a direction inclined with respect to a circumferential direction, wherein (1) a large number of the inclined grooves are provided on a tread circumference at intervals in the circumferential direction,
(2) Among the side walls of the inclined groove, at least one line of protrusions extending from the tread surface toward the groove bottom is formed in each groove on at least the side wall that comes into contact with the ground after rolling of the tire, and (3) the protrusion. A pneumatic tire having a sipe formed so as to divide a strip. 2. The pneumatic tire according to claim 1, wherein the protrusion height of the protrusion formed on the side wall of the inclined groove is 10 to 50% of the groove width of the inclined groove. 3. The pneumatic tire according to claim 1, wherein the angle of the protrusion formed on the side wall of the inclined groove is −45 to +45 degrees with respect to the tread normal. 4. The length of the sipe is 1 to 10 times the height of the protrusion of the protrusion body.
Pneumatic tire described. 5. The depth of the sipe is 1 of the groove depth of the inclined groove.
The pneumatic tire according to claim 1, wherein the pneumatic tire has a content of 0 to 90%.