JP6911824B2 - tire - Google Patents

Description

The present invention relates to a tire having a tread pattern in which pattern constituent units are repeatedly arranged in the tire circumferential direction in the tread portion.

Tires having various tread patterns have been proposed depending on the vehicle on which the tire is mounted and the conditions of the road surface. In the tread pattern, for example, a pattern constituent unit composed of a groove and a block adjacent thereto is repeatedly arranged in the tire circumferential direction. It is known that in such a tire, when the pattern constituent units are formed to have the same size, annoying noise (for example, pitch noise) is generated during traveling.

The following Patent Document 1 proposes a tire with reduced pitch noise. In the tire of Patent Document 1 below, the amplitude P (k) of the 1st to kth order obtained by Fourier transforming the pulse trains separated by the length of each pattern constituent unit with each pattern constituent unit as a pulse is within a predetermined range. Limited to. In the tire of Patent Document 1 below, the peak of the amplitude P (k) can be leveled over a wide range of order k, and pitch noise can be reduced (white noise).

Japanese Unexamined Patent Publication No. 2000-177320

Although the tire of Patent Document 1 reduces pitch noise during running, it has a problem that a roaring noise is likely to occur.

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire capable of suppressing a roaring noise during traveling.

ここで、
Ｎ：タイヤ１周での模様構成単位の総数
Ｌ：タイヤ周長変数（タイヤ１周の全ての模様構成単位の長さの比の総和）
ｋ：１〜２Ｎまでの自然数
ｉ：１〜２Ｎ−１までの自然数
Ｘ（ｊ）：第１パルス列の起点からｊ番目の模様構成単位までのパルス位置（起点からｊ番目までの長さの比の和）
ｍ：模様構成単位の種類数 The present invention is a tire having a tread pattern including a row in which at least two types of pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction in the tread portion, and the row of the pattern constituent units is provided. , Each pattern constituent unit is a pulse, and the pulse is replaced with a first pulse train arranged in the order of the arrangement and at intervals of the length of each pattern constituent unit starting from one pattern constituent unit. _{Of the 1-kth-} order amplitudes P k obtained by Fourier transforming the first pulse train with the following equation (1), the maximum value P _max of the amplitude P _k satisfies the following equation (1) and is the maximum value. It is characterized in that the _{amplitude P k} of 2/3 or more of P _{max is not continuous in adjacent orders.}

here,
N: Total number of pattern constituent units in one tire lap L: Tire circumference variable (sum of the ratio of the lengths of all pattern constituent units in one tire lap)
k: Natural number from 1 to 2N i: Natural number from 1 to 2N-1 X (j): Pulse position from the starting point of the first pulse train to the jth pattern building unit (ratio of lengths from the starting point to the jth) Sum)
m: Number of types of pattern constituent units

In the tire according to the present invention, the maximum value P _max may further satisfy the following formula (2).

ここで、
Ｐ（ｊ）：第２パルス列の起点からｊ番目のパルスの大きさ In the tire according to the present invention, the row of the pattern constituent units is a pulse having a size corresponding to the length of each pattern constituent unit, and the pulse is started from one pattern constituent unit. It is replaced with a second pulse train arranged in the order of the arrangement and at intervals of the length of each pattern constituent unit, and the magnitude of each pulse of the second pulse train is the length of the pattern constituent unit corresponding to the pulse. Is defined by the ratio of the at least two types of pattern building units to the median length of the length, and the average value of the pulse sizes corresponding to the at least two types of pattern building units is 1.00. The first-order amplitude F _{1 of the 1-kth-} order amplitude F k obtained by Fourier transforming the second pulse train by the following equation (3) may be 0.6 or less.

here,
P (j): The magnitude of the jth pulse from the starting point of the second pulse train

In the tire according to the present invention, the amplitude F ₁ of the first order may be 0.5 or less.

In the tire according to the present invention, the total number N of the pattern constituent units in one round of the tire may further satisfy the following formula (4).

In the tire according to the present invention, the ratio of the lengths of the pattern constituent units may be 0.08 to 0.25.

ここで、
Ｎ：タイヤ１周での模様構成単位の総数
Ｌ：タイヤ周長変数（タイヤ１周の全ての模様構成単位の長さの比の総和）
ｋ：１〜２Ｎまでの自然数
ｉ：１〜２Ｎ−１までの自然数
Ｘ（ｊ）：第１パルス列の起点からｊ番目の模様構成単位までのパルス位置（起点からｊ番目までの長さの比の和） The present invention is a tire having a tread pattern in which four types of pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction in the tread portion, and the rows of the pattern constituent units are arranged in the tread portion. Each pattern constituent unit is a pulse, and the pulse is replaced with a first pulse train arranged in the order of the arrangement and at intervals of the length of each pattern constituent unit starting from one pattern constituent unit, and the first. _{Of the 1-kth-} order amplitudes Pk obtained by Fourier transforming one pulse train with the following equation (5), the maximum value P _max of the amplitude _Pk satisfies the following equation (5) and the maximum value P. It is characterized in that the _{amplitude P k} of 2/3 or more of _{max is not continuous in adjacent orders.}

here,
N: Total number of pattern constituent units in one tire lap L: Tire circumference variable (sum of the ratio of the lengths of all pattern constituent units in one tire lap)
k: Natural number from 1 to 2N i: Natural number from 1 to 2N-1 X (j): Pulse position from the starting point of the first pulse train to the jth pattern building unit (ratio of lengths from the starting point to the jth) Sum)

In the tire according to the present invention, the maximum value P _max may further satisfy the following formula (6).

The tire of the present invention has a tread pattern in which the tread portion includes a row in which at least two types of pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction. The row of pattern constituent units is replaced with a first pulse train in which each pattern constituent unit is a pulse and the pulses are arranged in the order of arrangement starting from one pattern constituent unit and separated by the length of each pattern constituent unit. At the same time, among the amplitudes P _{k of the 1st to kth} orders obtained by Fourier transforming the first pulse train by the following equation (1), the maximum value P _max of the amplitude P k satisfies the following equation (1).

ここで、
Ｎ：タイヤ１周での模様構成単位の総数
Ｌ：タイヤ周長変数（タイヤ１周の全ての模様構成単位の長さの比の総和）
ｋ：１〜２Ｎまでの自然数
ｉ：１〜２Ｎ−１までの自然数
Ｘ（ｊ）：第１パルス列の起点からｊ番目の模様構成単位までのパルス位置（起点からｊ番目までの長さの比の和）
ｍ：模様構成単位の種類数

here,
N: Total number of pattern constituent units in one tire lap L: Tire circumference variable (sum of the ratio of the lengths of all pattern constituent units in one tire lap)
k: Natural number from 1 to 2N i: Natural number from 1 to 2N-1 X (j): Pulse position from the starting point of the first pulse train to the jth pattern building unit (ratio of lengths from the starting point to the jth) Sum)
m: Number of types of pattern constituent units

The amplitude P _k has a correlation with the magnitude of noise energy when frequency analysis is performed on the noise (pitch noise) generated when the block constituting the pattern constituent unit touches the road surface and separates when the tire is running. Further, the first _{order 1 to k} of the amplitude P k has a correlation with the frequency of noise energy. Tire of the present invention, the maximum value P _max of the amplitude P _k is to satisfy the above formula (1), it is possible to even out the peaks of the amplitude P _k to a wide range of the order k. As a result, the tire of the present invention can reduce pitch noise (white noise).

Further, the tire of the present invention is _{configured such that the amplitude P k} of 2/3 or more of _{the maximum value P max} of the amplitude is not continuous in adjacent orders. This prevents sounds of adjacent frequencies from interfering with each other, and can suppress growl noise during traveling.

It is a development view which shows an example of the tread part of a tire. It is a diagram which shows an example of the 1st pulse train for obtaining the amplitude P _k. It is a graph which shows the relationship between the amplitude P _{k and the degree k.} It is a diagram which shows the 2nd pulse train for obtaining the amplitude F _k. It is a graph which shows the relationship between the amplitude F _{k and the degree k.} It is a graph which shows the relationship between _{the amplitude Pk of a} tire A, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire B, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire C, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire D, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire E, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire F, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire G, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire H, and the degree k. It is a graph which shows the relationship between _{the amplitude Pk of a} tire I, and the degree k.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a development view showing an example of the tread portion 2 of the tire 1. A tread pattern 3 is provided on the tread portion 2 of the tire 1 of the present embodiment.

The tread pattern 3 is formed by repeatedly arranging at least two types of pattern constituent units 4 having different lengths L in the tire circumferential direction in the tire circumferential direction. As a result, a pitch variation is formed in the tread portion 2, so that noise during traveling can be reduced. The type of the pattern constituent unit 4 can be appropriately set according to, for example, the conditions of the vehicle on which the tire 1 is mounted and the road surface. It is desirable that the pattern constituent unit 4 has, for example, about 2 to 10 types. An example is that there are five types of pattern constituent units 4 of the present embodiment.

In the present embodiment, at least one row R of the pattern constituent units in which the pattern constituent units 4 are arranged in the tire circumferential direction is provided (five rows in the present embodiment). An example is that each pattern constituent unit 4 has the same position in the tire circumferential direction as the pattern constituent unit 4 in the row R of other pattern constituent units adjacent to each other in the tire axial direction, but the position is displaced in the tire circumferential direction. It may be (out of phase).

The pattern structural unit 4 of the present embodiment is composed of one block 6 and one lateral groove 7 adjacent to the block 6 on one side in the tire circumferential direction. Therefore, the case where the tread pattern 3 of the present embodiment is a block pattern is exemplified. The block 6 is divided into a lateral groove 7 and a main groove 8 extending in the direction intersecting the lateral groove 7 and continuously extending in the tire circumferential direction.

The total number N of the pattern constituent units 4 in one lap of the tire can be appropriately set. If the total number N is small, the noise reduction effect due to the pitch variation may not be sufficiently exhibited. On the contrary, if the total number N is large, uneven wear of the tread portion 2 may easily occur. Therefore, it is desirable that the total number N of the pattern constituent units 4 in one round of the tire satisfies the following equation (4). The total number N of the pattern constituent units 4 in one round of the tire may be set for each type number m of the pattern constituent units 4. The total number N of the pattern constituent units 4 in one round of the tire may be set for each type number m of the pattern constituent units 4.

Further, the total number N of the pattern constituent units 4 in one round of the tire can improve the rigidity of the tread portion 2 per pitch by satisfying the following equation (7), so that the noise reduction effect can be exhibited. , The steering stability can be effectively improved.

When pattern building blocks 4 having different lengths L in the tire circumferential direction are arranged in the order of the size of the length L, the rate of increase in the length L between adjacent pattern building blocks 4 and 4 is appropriately set. be able to. If the rate of increase is large, the difference in rigidity between the adjacent pattern constituent units 4 and 4 becomes large, so that uneven wear may occur. Further, if the rate of increase is small, noise of a specific frequency is concentrated, and there is a possibility that the noise reduction effect due to pitch variation cannot be sufficiently exhibited. From this point of view, the ratio (rate of increase) of the lengths L of the pattern constituent units 4 adjacent to each other in the tire circumferential direction is preferably about 0.08 to 0.25.

FIG. 2 is a diagram showing an example of a first pulse train for _{obtaining the amplitude P k.} In the tire 1 of the present embodiment, the rows R (shown in FIG. 1) of the pattern constituent units in which the pattern constituent units 4 are arranged in the tire circumferential direction are shown in FIG. The pulses 11 are equal to each other, and the pulses 15 are replaced with the first pulse train 12 arranged in the order of the arrangement of the columns R starting from one pattern constituent unit 4 and with the length L of each pattern constituent unit 4 spaced apart from each other. ing. The first pulse train 12 is created over one round of the tire. Further, the first pulse train 12 is created in an arbitrary row R when a plurality of rows R of pattern constituent units are formed.

In FIG. 2, the vertical axis indicates the magnitude of the pulse 11. The horizontal axis indicates the interval at which the pulse 11 is generated. The intervals at which the pulses 11 are generated are not equal. The generation interval of the pulse 11 is an interval corresponding to the length L of each pattern constituent unit 4 shown in FIG. The generation interval of the pulse 11 of the present embodiment is set based on the ratio of the length L of the pattern constituent unit 4. Here, the "ratio of the length L of the pattern constituent unit 4" defines one reference pattern constituent unit 4S (shown in FIG. 1) as a reference among the plurality of types of pattern constituent units 4, and this It is represented by the ratio of the length L of each pattern constituent unit 4 to the length L of the reference pattern constituent unit 4S. The reference pattern configuration unit 4S is preferably a pattern configuration unit arranged at an intermediate position or a position close to the intermediate pattern configuration unit 4 when all types of pattern configuration units 4 are arranged in the order of length L.

In the tire 1 of the present embodiment, the maximum value P _max of the _{amplitude P k is among the 1-kth-} order amplitude P k (power spectral density) obtained by Fourier transforming the first pulse train 12 by the following equation (1). , It is configured to satisfy the following equation (1).

ここで、
Ｎ：タイヤ１周での模様構成単位の総数
Ｌ：タイヤ周長変数（タイヤ１周の全ての模様構成単位の長さの比の総和）
ｋ：１〜２Ｎまでの自然数
ｉ：１〜２Ｎ−１までの自然数
Ｘ（ｊ）：第１パルス列の起点からｊ番目の模様構成単位までのパルス位置（起点からｊ番目までの長さの比の和）
ｍ：模様構成単位の種類数

here,
N: Total number of pattern constituent units in one tire lap L: Tire circumference variable (sum of the ratio of the lengths of all pattern constituent units in one tire lap)
k: Natural number from 1 to 2N i: Natural number from 1 to 2N-1 X (j): Pulse position from the starting point of the first pulse train to the jth pattern building unit (ratio of lengths from the starting point to the jth) Sum)
m: Number of types of pattern constituent units

The tire circumference variable L of the above formula (1) is represented by the sum of the ratios of the lengths L of all the pattern constituent units 4 arranged over one tire circumference. The pulse position X (j) of the above equation (1) is defined by the sum of the ratios of the lengths L of the pattern constituent units from the starting point S to the jth of the first pulse train 12 as follows.
X (1) = PL (1)
X (2) = PL (1) + PL (2)
・
・
・
X (j) = PL (1) + PL (2) + ... + PL (j)
It should be noted that PL (i) (i is a natural number from 1 to N) indicates the value of the ratio of the length L of the pattern constituent units 4 arranged in the i-th order from the starting point.

FIG. 3 is a graph showing the relationship between _{the amplitude P k and the order k.} The amplitude P _k is noise when frequency analysis is performed on the noise (pitch noise) generated when the block 6 constituting the pattern constituent unit 4 shown in FIG. 1 touches the road surface (not shown) and separates from the road surface (not shown) when the tire is running. There is a correlation with the magnitude of energy. The larger the amplitude P _k , the larger the noise energy. Further, each order k corresponds to each frequency. The order k is set in the range from the first order to the second Nth order (that is, the order obtained by multiplying the number N of the pattern constituent units by 2) as shown in the above equation (1). Such order k has a correlation with the frequency of noise energy.

In the tire 1 of the present embodiment, the maximum value P _{max of the amplitude P k} is the upper limit value of the above formula (1) (that is, 18.50-0.05 N when there are two types of pattern constituent units, and the pattern constituent unit is In the case of 3 types, it is limited to 14.50-0.05N, and in the case of 5 types of pattern constituent units, it is limited to 12.00-0.05N) or less. This was discovered by the inventors based on various experimental results. In the experiment by the inventors, first, a plurality of tires having different total number N and the like of the pattern constituent unit 4 were prototyped, and the first pulse train 12 as shown in FIG. 2 was created. Next, the maximum value P _{max of the first- kth-} order amplitude (power spectral density) P k obtained by Fourier transforming the first pulse train 12 by the above equation (1) was obtained. Then, the prototype tire 1 was mounted on the actual vehicle, the sound pressure level of the pitch noise in the vehicle was measured, and the sensory test was performed by the driver. Such experiments, the inventors have found that the maximum value P _max satisfies the above formula (1), it is possible to even out the peaks of the amplitude P _k to a wide range of degree k, reduced pitch noise (White It was found that it can be made into noise).

Furthermore, the inventors have conducted experiments using a plurality of tires having different types of pattern constituent units 4, and as the number m of types of pattern constituent units 4 increases, the upper limit of the _{maximum value P max is reduced.} It was found that pitch noise can be effectively reduced. In the tire 1 of the present embodiment, the upper limit value of the above formula (1) is set for each type (2 types, 3 types, or 5 types) of the pattern constituent unit. _{As a result, in the tire 1 of the present embodiment, the upper limit value of the maximum value P max} is small and limited according to the number of types m of the pattern constituent unit 4, so that the pitch noise can be effectively reduced.

In order to reduce pitch noise more effectively, it _{is desirable that the maximum value P max} further satisfies the following equation (2).

ここで、各定数及び変数は、上記式（１）の定数及び変数と同一である。

Here, each constant and variable are the same as the constant and variable in the above equation (1).

In addition, as a result of intensive research by the inventors, when _{the peak of the amplitude Pk} is leveled over a wide range of the order k as described above, sounds of adjacent frequencies interfere with each other, and a growl is likely to occur. I found that. Based on such knowledge, the tire 1 of the present embodiment is configured so that _{the amplitude P k} of 2/3 or more of the _{maximum value P max} does not continue in the adjacent order k. As a result, the tire 1 of the present embodiment can prevent adjacent loud sounds of frequencies from interfering with each other.

Among the neighboring order k, even more than two-thirds of one number of the next amplitude P _k is the maximum value P _max, the amplitude P _k of the other order k is less than 2/3 of the maximum value P _max If so, the growl will not be so loud. Therefore, the tire 1 of the present embodiment is configured so that _{the amplitude P k} of 2/3 or more of the _{maximum value P max} is not continuous at the adjacent order k, so that the roaring noise during traveling can be suppressed. In order to effectively exert such an action, it _{is desirable that the amplitude P k} of 3/5 or more of the _{maximum value P max} is not continuous in the adjacent order k.

FIG. 4 is a diagram showing a second pulse train for _{obtaining the amplitude Fk.} In the tire 1 of the present embodiment, the pattern constituent units 4 shown in FIG. 1 are arranged in the tire circumferential direction in a row R, and as shown in FIG. 4, each pattern constituent unit 4 has a length thereof. The pulses 15 have a size corresponding to the L, and the pulses 15 are arranged in the order of the arrangement of the column R starting from one pattern constituent unit 4 and separated by the length L of each pattern constituent unit 4. It is replaced with the second pulse train 16. The second pulse train 16 is created over one round of the tire. Further, when a plurality of rows R of pattern constituent units are formed, the second pulse train 16 is created in the rows R of arbitrary pattern constituent units.

In FIG. 4, the vertical axis indicates the magnitude of the pulse 15. The horizontal axis indicates the interval at which each pulse 15 is generated. The size of each pulse 15 is the length L of the pattern constituent unit 4 corresponding to the pulse 15, and the length L of at least two types of pattern constituent units 4 (in the present embodiment, the five types shown in FIG. 1). It is defined by the ratio of the pattern constituent units LL, L, M, S, and SS to each length L) to the median value. The generation interval of each pulse 15 is an interval according to the ratio of the length L of each pattern constituent unit 4, as in the diagram showing the first pulse train 12 having the _{amplitude Pk shown in FIG.}

In the tire 1 of the present embodiment, in order to effectively reduce the above-mentioned beat noise, the first-kth-order amplitude (power spectral density) obtained by Fourier transforming the second pulse train 16 by the following equation (3) is obtained. ) _{Of F k} , the amplitude F ₁ of the first order is preferably limited to 0.6 or less.

ここで、各定数及び変数は、次に示すものを除いて、上記式（１）の定数及び変数と同一である。
ここで、
Ｐ（ｊ）：第２パルス列の起点からｊ番目のパルスの大きさ

Here, each constant and variable is the same as the constant and variable in the above equation (1) except for the following.
here,
P (j): The magnitude of the jth pulse from the starting point of the second pulse train

FIG. 5 is a graph showing the relationship between _{the amplitude F k and the order k.} The amplitude F _k is used to predict low-order components (noise energy with a low frequency in this embodiment). Similar to the amplitude P _k , the amplitude F _k has a correlation with the magnitude of the noise energy when the pitch noise is frequency-analyzed during tire running. Further, the order k has a correlation with the frequency of the noise energy, and as shown in the above equations (3) and (1), the order k is the first to the second Nth order (that is, the number N of the pattern constituent units is multiplied by 2. It is set in the range up to (order).

The first-order amplitude F ₁ affects the noise energy that fluctuates once per tire lap. Such a first-order amplitude F ₁ corresponds to noise energy having a vehicle speed of 15 to 35 km / h, for example, when the tire 1 is for a passenger car, and tends to generate a roaring sound in the vicinity of 2 to 5 Hz. In general, it is known that a roaring sound around 2 to 5 Hz is particularly unpleasant for humans. Based on the results of various experiments as described above, the inventors have found that the roaring sound as described above can be effectively suppressed by limiting _{the amplitude F 1 of the first order to 0.6 or less.} Therefore, the tire 1 of the present embodiment is configured so that the amplitude P _{k of 2/3 of the maximum value P max} is not continuous in the adjacent order k, and the amplitude F _{1 of the} primary order is limited to 0.6 or less. By doing so, it is possible to effectively suppress the roaring noise during traveling. Further, the inventors, as the number of types m of the pattern configuration unit 4 (shown in FIG. 1) is increased, and found that it is desirable to reduce the upper limit value of amplitude F ₁ of the primary number. Therefore, the tire 1 of the present embodiment can effectively reduce the roaring noise during traveling. In order to more effectively reduce such a roaring noise during running, it _{is desirable that the amplitude F 1 of the first order} is limited to 0.5 or less.

Further, the average value of the sizes of the pulses 15 corresponding to at least two types of pattern constituent units (in this embodiment, the five types of pattern constituent units LL, L, M, S, SS shown in FIG. 1) is 1. .00 is desirable. As a result, the maximum value F _max of the first-order amplitude F ₁ and the amplitude F _k can be effectively reduced, and the roaring noise during traveling can be reliably suppressed.

In the present embodiment, the case where the pattern constituent unit 4 is of 2, 3, or 5 types has been exemplified, but the present invention is not limited to such an embodiment. For example, in the tire 1 in which the pattern constituent unit 4 has four types, the amplitude P _{is out of the amplitude P k} (power spectral density) of the 1st to kth order obtained by Fourier transforming the first pulse train 12 by the following equation (5). _It is desirable that the maximum value P _{max of} k is configured to satisfy the following equation (5). In this embodiment, the same configurations as those in the previous embodiment are designated by the same reference numerals, and the description thereof may be omitted.

ここで、
Ｎ：タイヤ１周での模様構成単位の総数
Ｌ：タイヤ周長変数（タイヤ１周の全ての模様構成単位の長さの比の総和）
ｋ：１〜２Ｎまでの自然数
ｉ：１〜２Ｎ−１までの自然数
Ｘ（ｊ）：第１パルス列の起点からｊ番目の模様構成単位までのパルス位置（起点からｊ番目までの長さの比の和）

here,
N: Total number of pattern constituent units in one tire lap L: Tire circumference variable (sum of the ratio of the lengths of all pattern constituent units in one tire lap)
k: Natural number from 1 to 2N i: Natural number from 1 to 2N-1 X (j): Pulse position from the starting point of the first pulse train to the jth pattern building unit (ratio of lengths from the starting point to the jth) Sum)

In the tire 1 of this embodiment (four types of pattern constituent units 4), the maximum value P _{max of the amplitude P k} is limited to the upper limit value (that is, 16.50-0.05 N) or less of the above formula (5). NS. This was found by the results of various experiments by the inventors, as in the previous embodiment. In the tire 1 of this embodiment, when the maximum value P _max satisfies the above equation (5), _{the peak of the amplitude P k} can be leveled over a wide range of the order k, and the pitch noise is reduced (white noise). can.

In order to reduce pitch noise more effectively, it _{is desirable that the maximum value P max} further satisfies the following equation (6).

ここで、各定数及び変数は、上記式（５）の定数及び変数と同一である。

Here, each constant and variable is the same as the constant and variable in the above equation (5).

The tire 1 of this embodiment _{is configured so that the amplitude P k} of 2/3 or more of the _{maximum value P max} is not continuous in adjacent orders. As a result, the tire 1 of this embodiment can prevent the adjacent loud sounds of frequencies from interfering with each other, and can suppress the roaring sound during traveling. In order to effectively exert such an action, it _{is desirable that the amplitude P k} of 3/5 or more of the _{maximum value P max} is configured so as not to be continuous in adjacent orders k.

In the tire 1 of this embodiment, similarly to the tire 1 of the previous embodiment, the first-kth-order amplitude (power spectrum) obtained by Fourier transforming the second pulse train 16 (shown in FIG. 4) by the above equation (3). Of the density) F _k , the first-order amplitude F ₁ is preferably limited to 0.6 or less. As a result, the tire 1 of this embodiment can effectively reduce the roaring noise during traveling. In order to more effectively reduce such a roaring noise during running, it _{is desirable that the amplitude F 1 of the first order} is limited to 0.5 or less.

The average value of the sizes of the pulses 15 corresponding to the pattern constituent units (in this embodiment, the four types of pattern constituent units LL, L, S, and SS) is preferably 1.00. As a result, the maximum value F _max of the first-order amplitude F ₁ and the amplitude F _k can be effectively reduced, and the roaring noise during traveling can be reliably suppressed.

The tires of the conventional embodiments have been exemplified in the case where the tread pattern 3 is a block pattern, but the tire is not limited to such an embodiment. For example, when the tread pattern 3 is a rib pattern, the pattern constituent unit 4 is configured as a region between valleys of a zigzag groove (not shown) extending in the tire circumferential direction or between peaks. NS. When the tread pattern 3 is a lug pattern, the pattern constituent unit 4 is composed of one lug groove (not shown) and one land portion (not shown) adjacent to each other in the tire circumferential direction of the lug groove. It is composed.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments and can be modified into various embodiments.

A block pattern tire having the basic configuration shown in FIG. 1 and having the specifications shown in Table 2 was prototyped (Examples 1 to 6 and Comparative Examples 1 to 3). For each test tire, the maximum value P _{max of the amplitude P k} and the primary amplitude F ₁ were obtained. 6 to 14 are graphs showing the relationship between _{the amplitude P k of the tires A to I and the order k.} The arrangement of the pattern constituent units is as shown in Table 1. The common specifications are as follows.
Tire size: 195 / 65R15
Rim size: 15 x 6.5J
Internal pressure: 230 kPa
Load: 4.20 kN
Speed: 34km / h
Rows of pattern constituent units: 4 rows Drum surface (road surface): Friction sheet material (Product name "Safety Walk (registered trademark)" manufactured by 3M Japan Ltd.)
Ratio of lengths of pattern constituent units (rate of increase): 0.08 to 0.25
Average pulse magnitude: 1.00

<Bench noise test>
Using a drum tester with a diameter of 3.0 m, each test tire is run on the drum under the conditions of the above rim, the above internal pressure, and the above load in accordance with JASO, from 60 km / h to 20 km / h. The sound pressure when coasting was measured. The microphone used for measuring the sound pressure was fixed at a position 1 m away from the tire equatorial line in the tire axial direction and 15 cm away from the drum surface in the drum radial direction. Then, based on the time-series data of the sound pressure, the partial overalls of the frequency corresponding to the order ± 20 were calculated, and the sound pressure (pitch noise) at the speed (33-40 km / h) near the peak was obtained. Further, among the time-series data of sound pressure, wavelet transform was performed (resolution 16 Hz) based on the time-series data of sound pressure of 34 km / h, and the primary component (beating sound) was extracted. The result is displayed as an index with the sound pressure of Example 1 as 100. The smaller the number, the better.

<Vehicle noise test>
Each test tire was mounted on the right front wheel of a 1800 cc domestic passenger car under the conditions of the rim, the internal pressure, and the load. The left front wheel and the rear wheel were equipped with slick tires without a tread pattern. Then, when the vehicle is driven on a smooth road surface and coasted from 60 km / h to 20 km / h, the overall evaluation including pitch noise, growl, and pitch noise and growl is 10 depending on the driver's sensuality. It was evaluated by the point method. The higher the number, the better the result.
The test results are shown in Table 2.

As a result of the test, the examples were able to suppress the roaring noise while reducing the pitch noise during running as compared with the comparative example.

P _k amplitude k degree

Claims (8)

A tire having a tread pattern including rows in the tread portion in which at least two types of pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction.
A first row in which the pattern constituent units are arranged in the order of the arrangement and with the length of each pattern constituent unit separated from each other, with each pattern constituent unit as a pulse and the pulse as a starting point. Replace with a pulse train and
_{Of the 1-kth-} order amplitudes P k obtained by Fourier transforming the first pulse train with the following equation (1), the maximum value P _max of the amplitude P _k satisfies the following equation (1) and is the maximum. _{A tire in which the amplitude P k} of 2/3 or more of the value P _max is not continuous in adjacent orders.

here,
N: Total number of pattern constituent units in one tire lap L: Tire circumference variable (sum of the ratio of the lengths of all pattern constituent units in one tire lap)
k: Natural number from 1 to 2N i: Natural number from 1 to 2N-1 X (j): Pulse position from the starting point of the first pulse train to the jth pattern building unit (ratio of lengths from the starting point to the jth) Sum)
m: Number of types of pattern constituent units The tire according to claim 1, wherein the maximum value P _max further satisfies the following formula (2).

In the row of the pattern constituent units, each pattern constituent unit is a pulse having a size corresponding to the length thereof, and the pulse is formed in the order of the arrangement starting from one pattern constituent unit and each pattern configuration. In addition to replacing with the second pulse train arranged with the length of the unit separated,
The magnitude of each pulse in the second pulse train is defined by the ratio of the length of the pattern building unit corresponding to that pulse to the median of the length of the pattern building unit of at least two types.
The average value of the magnitudes of the pulses corresponding to the at least two types of pattern building blocks is 1.00.
The tire according to claim 1 or 2, wherein _{the amplitude F 1 of the first order is 0.6 or less among the amplitudes F k} of the 1st to kth orders obtained by Fourier transforming the second pulse train by the following equation (3). ..

here,
P (j): The magnitude of the jth pulse from the starting point of the second pulse train The tire according to claim 3, wherein the amplitude F _{1 of the first order is 0.5 or less.} The tire according to any one of claims 1 to 4, wherein the total number N of the pattern constituent units in one round of the tire further satisfies the following formula (4).

The tire according to any one of claims 1 to 5, wherein the ratio of the lengths of the pattern constituent units is 0.08 to 0.25. A tire having a tread pattern including a row in which four types of pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction in the tread portion.
A first row in which the pattern constituent units are arranged in the order of the arrangement and with the length of each pattern constituent unit separated from each other, with each pattern constituent unit as a pulse and the pulse as a starting point. Replace with a pulse train and
_{Of the 1-kth-} order amplitudes P k obtained by Fourier transforming the first pulse train with the following equation (5), the maximum value P _max of the amplitude P _k satisfies the following equation (5) and is the maximum. _{A tire in which the amplitude P k} of 2/3 or more of the value P _max is not continuous in adjacent orders.

here,
N: Total number of pattern constituent units in one tire lap L: Tire circumference variable (sum of the ratio of the lengths of all pattern constituent units in one tire lap)
k: Natural number from 1 to 2N i: Natural number from 1 to 2N-1 X (j): Pulse position from the starting point of the first pulse train to the jth pattern building unit (ratio of lengths from the starting point to the jth) Sum) The tire according to claim 7, wherein the maximum value P _max further satisfies the following formula (6).

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