JPH0427605A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce pattern noise effectively by forming respective pairs of notched grooves formed on a tire tread surface part from two types of long and short notched grooves, and communicating them with each other by sipes formed on a straight line which passes through both the notched grooves. CONSTITUTION:In four circumferential grooves 2 in a straight line formed in parallel each other on a tread surface part 1, three central area part lines 3 are blocked between the grooves, and respective shoulder land line 4 are blocked one by one at an outer side position. With this constitution, a pair of two notched grooves 5 of whose end is open to only the grooves 2 in a circumferential direction are provided at both the edge sides of the central area land lines 3 arranged substantially on a straight line which inclines at an approximately equal angle to the grooves 2 in the circumferential direction. Besides, respective pairs of notched grooves 5 are formed from two types of long and short notched grooves 5 of which notched length to the central area part lines 3 are different. Moreover, the respective pairs of the notching grooves 5 are communicated with each other by sipes 6 formed on an inclined straight line as mentioned above.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a pneumatic tire with high dynamic performance, and in particular, improves the comfort inside a vehicle by reducing pattern noise. It is something.

(Prior Art) Conventional high-performance pneumatic tires have been designed with drainage performance, wear resistance, performance on dry roads, etc. as the main objectives, and reduction of pattern noise has been considered secondary.

However, in recent years, with the trend toward higher-end automobiles, there has been a strong demand for improved interior comfort based on reduction of pattern noise in addition to these various performances.

For this reason, usually, by forming a plurality of circumferential grooves extending linearly in the circumferential direction of the tire in the tread surface of the tire, each central area land area is divided between the circumferential grooves. In order to reduce noise-generating factors, so-called block pattern tires are provided with inclined grooves in the rows that are inclined at an angle within the range that can provide the required drainage performance with respect to the tire's equatorial plane, or in other words, the circumferential groove. ,
This problem was dealt with by narrowing the width of the slanted groove, shortening the length of the slanted groove, and making the block ribbed.

This means that pattern noise, especially pitch noise, is greatly affected by the inclined grooves.
This is based on the fact that pitch noise is reduced as the groove width and groove edge length are made smaller.

(Problem to be Solved by the Invention) However, according to such conventional technology, as a natural consequence of reducing the width, length, etc. of the inclined groove, drainage performance, ground contact (comfort), etc. Since other performances are unavoidably degraded, pattern noise can usually be reduced only to the extent that these other performances and pattern noise reduction are mutually balanced.

The present invention advantageously solves the problems of the prior art, and improves the groove width, groove length, etc. of the inclined groove that is inclined at an angle within a range that can provide the required drainage performance with respect to the tire equatorial plane. The present invention provides a pneumatic tire that can more effectively reduce pattern noise, even if it is the same as those of the prior art.

(Means for Solving the Problems) The pneumatic tire of the present invention has a plurality of linear circumferential grooves, for example, formed in the tread surface of the tire, so that a plurality of circumferential grooves are formed between the circumferential grooves. A central region land row of the book is formed, and a shoulder land row is formed further outside the outermost circumferential groove, and each center region land row has one circumferential groove at both ends thereof. Two pairs of notch grooves are formed facing each other, and each pair of notch grooves is formed substantially on a straight line that is inclined at the same angle with respect to the circumferential groove. The notch grooves of each village are formed with two types of notch grooves, long and short, with different cut lengths into the central area land row, and each side edge of the central area land row is At least two types of long and short notch grooves are arranged alternately in the circumferential direction of the tire, and further,
The notch grooves of each village are made to communicate with each other by the sipes formed on the straight line, and more preferably, the length of the sipes in the tire circumferential direction is set to 174 of the unit pitch length of the notch grooves. Above, 172
In addition, the sum of the sum of the tire circumferential length of the kick-out side edge and the stepping-in side edge of each pair of notch grooves and the tire circumferential length of the sipe is calculated as follows. The unit pitch length of the groove is less than or equal to the unit pitch length of the groove.

(Function) In such a pneumatic tire, by forming each notch groove in each village with two types of notch grooves, long and short, pitch noise input is reduced compared to a case of the same length. There is a variation effect.

In addition, by arranging at least two types of long and short notch grooves alternately in the circumferential direction of the tire at each side end of the central region land row, it is possible to arrange only notch grooves of the same length in the same way as described above. This produces a variation effect of pitch noise input.

By making the notched grooves of each village communicate with each other by sipes formed on a straight line passing through both notched grooves, pattern noise can be sufficiently reduced based on the action of the sipes. It is possible to realize effective cutting and improvement of grounding performance.

Here, if the length S in the tire circumferential direction of the sipe mentioned above is set to 1/4P < S < 1/2P with respect to the unit pitch P of the notch groove, and in particular, S#l/3P, the pattern It is possible to achieve both noise reduction and wet drainage performance at a higher level.

In other words, if the length S becomes shorter than in the case described above, the length of the notched groove portion of each village, which is inclined at an angle within a predetermined range with respect to the circumferential groove, becomes too long, making pattern noise less effective. If the length S becomes longer than the above case, the length of the notched groove portion becomes too short and sufficient wet drainage performance cannot be ensured.

Also, here, the average value of the total tire circumferential length of the kick-out side edge and the stepping-in side edge of each of the pair of notch grooves and the circumferential length S of the sipe as described above are calculated. When the sum is less than or equal to the circumferential unit pitch length of the notched grooves, the pitch of the notched grooves can be made sufficiently coarse, and pattern noise can be effectively prevented from occurring.

Conversely, if the sum of these exceeds the unit pitch length of the notched grooves, all of the groove edges of one pair of notched grooves and the sipes that connect each notched groove end in contact with the road surface. The groove edges of the other pairs of notch grooves and sipes begin to collide with the road surface earlier, which inevitably increases pattern noise.

In addition, in the above-mentioned place, the average value of the total length in the tire circumferential direction of the kick-out side edge and the stepping-in side edge of each of a pair of notch grooves is, especially in a tire whose rotational direction is not specified, According to each edge of each notch groove,
This is a convenient representation of the risk of pattern noise generation, and each edge of a notch groove with a specific groove width is either the edge on the kick-out side or the edge on the tread-in side, depending on the rotation direction of the tire. In addition to this, it is taken into consideration that there is a difference in length between both edges depending on the shape of the notch groove.

Thus, with this pneumatic tire, pattern noise can be effectively reduced and cabin comfort can be greatly improved without substantially impairing other performances such as wet drainage performance and driving performance on dry roads. .

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram illustrating the tread pattern of the invention tire.

Note that the internal structure of this tire is similar to that of a radial tire for boat fishing, so illustration is omitted here.

In the figure, 1 indicates the I/red tread surface, and 2 indicates the linear circumferential grooves formed parallel to each other on the tread tread surface 1. In this example, there are four circumferential grooves. 2
defines three central region land rows 3 between them, and each shoulder land row 4 at a further outer position of each of the outermost circumferential grooves 2.

At both ends of each central area land row 3,
They are substantially equally spaced in the circumferential direction of the tire, are substantially arranged on a straight line that is inclined at substantially the same angle with respect to the circumferential groove 2, and are opposed to each other;
A pair of notched grooves 5.5 are provided, each of which connects to only one of the circumferential grooves 2, and each of the notched grooves in each village is divided into two grooves with different lengths of cut into the central area land row 3. In addition to forming the notch groove 5 of the type, the central area land row 3
The notch grooves 5 provided at each side end of the tire are of two types, long and short, which alternate in length in the circumferential direction of the tire, and the opening portion of each notch groove 5 into the circumferential groove 2 is is wider than other parts, and each of the notch grooves 5 in each village is
They are communicated with each other by the sipes 6 formed on the above-mentioned inclined straight line.

By the way, as shown in the figure, the pair of notch grooves and the sipes 6 that connect the respective notch grooves 5 are located in the middle of the three central area land rows 3. Although it is assumed that they extend in the downward direction, and in the upward right direction in the respective regions located on both sides, it is also possible to make the direction of extension in the opposite direction to that shown in the illustrated example. There is no risk that drainage performance or other performance will be impaired.

In addition, here, each shoulder land part example 4 located on the outside of the three central area land part rows 3 is extended in the same direction as the adjacent notch groove 5 across the circumferential open groove 2, and the land part A plurality of bending grooves 7 extending in opposite directions in the middle of the row 4 are formed at the same pitch as the notch grooves 5.

In the pneumatic tire configured in this manner, as described above, by forming multiple pairs of notch grooves with two types of long and short notch grooves 5, a variation effect of pitch noise input is produced. By alternately arranging two types of notch grooves 5, long and short, around the circumference of the tire at each side end of the area land row 3, a further variation effect is produced.

Moreover, here, the multiple pairs of notch grooves are made to communicate with each other by the sipes 6 formed on a straight line passing through both of the notch grooves 5, as also mentioned above.
It is possible to sufficiently improve performance such as pattern noise reduction, water film cutting, and ground contact.

Furthermore, in the illustrated preferred example, in order to achieve both pattern noise reduction and wet drainage performance at a high level, the tire circumferential length S of the sipe 6 is cut into a notch, as shown in a partially enlarged view in FIG. By setting the unit pitch length P of the groove 5 to 1/4P < S < 1/2P, more preferably S#1/3P, an increase in pattern noise due to the notch groove 5 becoming too long is prevented. On the other hand, deterioration of wet drainage performance due to the notch groove 5 becoming too short is prevented.

Preferably, the kick-out side edges TA, TI and the step-in side edges LA, L of each of the multiple pairs of notch grooves.

The average value of the total circumferential length of the tire, and the sipe 6,
The sum of the tire circumferential length S is (LA+TA)/2 + (LB+TB)/2 + S≦
P, one pair of notch grooves 5 and sipes 6
is prevented from protruding from the unit pinch length P of the notched groove 5, resulting in further reduction of pattern noise. That is, if the sum exceeds the unit pitch length P, when the tire corresponding to the unit pinch length is transferred, in addition to the edges of the notch grooves 5 of that pair, the edges of the notch grooves 5 of other pairs Since there is a region in which the edges also collide with the road surface at the same time, pattern noise due to the simultaneous collisions is inevitably increased.

Therefore, according to the tire of this example, the pitch ratio can be set to
．． 85: 1: 1.15, each of the multiple pairs of notch grooves consists of two types of long and short notch grooves, and in addition, in the notch groove pairs adjacent to each other in the circumferential direction of the tire, By reversing the long-short relationship, the pattern noise can be brought closer to white noise than when the pitch ratio is changed by a simple pitch variation, which improves the comfort of the vehicle interior. It becomes possible to significantly reduce pattern noise that impairs the image quality.

(Comparative example) The pattern noise of the invention tire and comparison tire is shown below.
Comparative tests regarding handling stability on wet road surfaces and dry road surfaces will be explained.

◎Test tire/size: PSR205/60 R15/Invention Tire The width of the tread surface of the tire having the tread pattern shown in Part 1 was 160 mm, the unit pitch length of the notch groove was 30 mm, and the outermost circumferential groove was When the groove width is 10 mm and the groove width of the other circumferential grooves is 9 mm, (1, AI + TA1) / 2 + (LB1 + TB1) / 2 in the middle central area land row.
+ S, (9+5)/2+(2+6)/2+8
= 19 and (LA2+TA2)/2 +
(LB2+TB2)/2 + S, (6+2)/
Assuming that 2+(5+9)/2+8 = 19, any of these values (19mm+) is the unit pitch length of the notch groove.
(30mm), and the tire circumferential length S (8mm) of the side is set to the unit pitch length P of the notch groove.
(30mm) P/4 < S < P/2, and (LA1 + TA1) / 2 + (LB1 + TB1) in other central area land columns
/ 2 + S, (5+2)/2+ (7+10)/
2+9 = 21 and (2+TA2 to L)
/2 + (LB2+TB2) /2 +S (8+5
)/2+(3+6)/2+9=20, and in addition to making any of these values smaller than the unit pitch length P, the sipe length S (9 mm) is changed to its unit pitch length P (
3(laIIl) P/4 <S< P/2 Comparison Tire I A tire having the tread pattern shown in Fig. 3, by making the lengths of the notch grooves in each village approximately equal. , LA + TA' = iLB + TB. Comparison tire with the same dimensions as the invention tire, except that LA + TA' = iLB + TB. ■ A block pattern tire in which the sipes of the comparative tire ■ are grooves with the same width as the respective notch grooves. ◎Test method: JIS standard. The actual vehicle was run under the standard internal pressure and standard load, and the pattern noise was 1100K/h, 8B.
By feeling evaluating the cabin noise during coasting at speeds of 60 m/h, 60 m/h, and 40 km/h, we also evaluated the steering stability on wet roads at water depths of 0 m/h and 40 km/h.
The driving stability on a dry road surface was tested by feeling-evaluating the driving performance on a just-wet test course, and the driving stability on a dry road surface was also feeling-evaluating the driving performance on a dry test course.

◎Test results The results of each of the above tests and those of the comparative tires were compared to an index of 100.
When expressed as an index, it is as shown in the table below.

It should be noted that the larger the index value, the sharper the result.

According to the above table, in the invention tire, by assigning lengths to the groove lengths of each pair of notched grooves, and reversing the length relationship between pairs of notched grooves adjacent to each other in the circumferential direction,
It is clear that pattern noise can be effectively reduced without any effect on the handling stability on wet and dry road surfaces.

(Effects of the Invention) Thus, according to the present invention, pattern noise can be effectively reduced without substantially sacrificing drainage performance, dry/wet handling stability, etc. of high-performance pneumatic tires, and the Indoor comfort can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a tread pattern showing an embodiment of the present invention, FIG. 2 is an enlarged view of the portion shown in FIG. 1, and FIG. 3 is a tread pattern of a comparative tire. 1...Tread surface portion 2...Circumferential groove 3...
・Central area land column 4...Shoulder land column 5・
・Notch groove 6... Side figure 2

Claims (1)

[Claims] 1. A plurality of circumferential grooves provided in the tread surface, and a plurality of central region land rows located between these circumferential grooves;
Shoulder land rows located further outward than the outermost circumferential grooves and two grooves provided opposite to each other at both ends of each center area land row, each opening into only one circumferential groove. A pneumatic tire comprising a pair of notch grooves, each pair of notch grooves being substantially located on a straight line inclined at the same angle with respect to the circumferential groove, Each pair of notch grooves is formed with two types of long and short notch grooves having different cutting lengths into the central area land part row, and at least two types of long and short notch grooves are formed at each side end of the central area land part row. A pneumatic tire in which notched grooves are arranged alternately in the circumferential direction of the tire, and each pair of notched grooves are communicated with each other by a sipe formed on the straight line. 2. The pneumatic tire according to claim 1, wherein the length of the sipe in the tire circumferential direction is 1/4 or more and 1/2 or less of the unit pitch length of the notched groove. 3. Calculate the sum of the sum of the tire circumferential lengths of the kick-out side edge and the step-in side edge of each pair of notch grooves, and the tire circumferential length of the sipes. The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire has a unit pitch length or less.