JP7497583B2 - Tire, tire manufacturing method, tire design method, and method for determining arrangement of pattern constituent units - Google Patents

Description

The present invention relates to a tire having a tread portion, a tire manufacturing method, a tire design method, and a method for determining the arrangement of pattern constituent units.

Conventionally, there is known a tire having a tread pattern including rows in which at least two types of pattern constituent units are arranged in the tire circumferential direction in the tread portion. For example, the following Patent Document 1 proposes a tire in which the rows of pattern constituent units are replaced with a pulse train in which the pattern constituent units are pulses, and the maximum value _Fmax of the 1st to kth order amplitudes _Fk obtained by Fourier transforming the pulse train is limited to within a predetermined range to reduce pitch noise.

JP 2019-099131 A

However, the tire in Patent Document 1 does not take into account a tread pattern in which the length of each row of pattern components in the tire circumferential direction varies, and there was a demand for reducing pitch noise in accordance with the tread pattern.

The present invention was devised in consideration of the above-mentioned circumstances, and its main objective is to provide a tire that can reduce pitch noise in accordance with the tread pattern, a tire manufacturing method, a tire design method, and a method for determining the arrangement of pattern constituent units.

ここで、
Ｌ：タイヤ周長変数（タイヤ１周の全ての第１模様構成単位の長さの比の総和）
ｋ：１～２Ｎまでの自然数
Ｘ（ｊ）：第２パルス列の起点からｊ番目のパルス位置（起点からｊ番目までの第２パルスの間隔の和）
Ｐ（ｊ）：第２パルス列のｊ番目の第２パルスの大きさ
ｍ：第１模様構成単位の種類数 The present invention relates to a tire having a tread portion, the tread portion being provided with a tread pattern including a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction, and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction, wherein a total number Nt of the first pattern constituent units in one revolution of the tire and a total number N of the second pattern constituent units in one revolution of the tire have a greatest common divisor GCD other than 1, the first pattern constituent units are replaced with first pulses having a magnitude corresponding to the lengths of the first pattern constituent units in the tire circumferential direction, the first pattern row is replaced with a first pulse row in which the first pulses are arranged in the order of the arrangement of the first pattern constituent units and at intervals corresponding to the lengths of the first pattern constituent units in the tire circumferential direction, and adjacent Nt/GCD first pulses in the first pulse row are added together to obtain a second pulse row having N/GCD second pulses, the maximum value _Fmax of 1st to kth amplitudes _Fk obtained by Fourier transforming the second pulse row using the following formula (1) satisfies the following formula (2):

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units around one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units

In the tire of the present invention, it is preferable that the second pulse train is formed by adding two adjacent pulses of the first pulse train together to form one second pulse.

In the tire of the present invention, it is desirable that the magnitude of the first pulse is defined as the ratio of the circumferential length of the first pattern constituent unit corresponding to the first pulse to the median of the circumferential length of at least two types of the first pattern constituent units.

In the tire of the present invention, the ratio is preferably 0.05 to 0.35.

In the tire of the present invention, it is preferable that, among the 1st to kth order amplitudes _Fk , the 1st order amplitude _F1 is 2.0 or less.

In the tire of the present invention, it is preferable that, among the 1st to kth order amplitudes _Fk , the 1st order amplitude _F1 is 1.0 or less.

In the tire of the present invention, it is preferable that, among the 1st to kth order amplitudes F _k , amplitudes F _k that are ⅔ or more of the maximum value F _max do not occur consecutively in adjacent orders.

In the tire of the present invention, it is desirable that the total number Nt of the first pattern constituent units in one circumference of the tire is 30 to 90.

ここで、
Ｌ：タイヤ周長変数（タイヤ１周の全ての第１模様構成単位の長さの比の総和）
ｋ：１～２Ｎまでの自然数
Ｘ（ｊ）：第２パルス列の起点からｊ番目のパルス位置（起点からｊ番目までの第２パルスの間隔の和）
Ｐ（ｊ）：第２パルス列のｊ番目の第２パルスの大きさ
ｍ：第１模様構成単位の種類数 The present invention is a method for manufacturing a tire having a tread pattern provided in a tread portion thereof, the method including a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction, and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction, the method including a first step of replacing the first pattern constituent units with first pulses having a magnitude corresponding to the lengths of the first pattern constituent units in the tire circumferential direction when a total number Nt of the first pattern constituent units in one circumference of the tire and a total number N of the second pattern constituent units in one circumference of the tire have a greatest common divisor GCD other than 1; a second step of replacing the first pattern row with a first pulse row in which the first pulses are arranged in the order of the arrangement of the first pattern constituent units and at intervals corresponding to the lengths of the first pattern constituent units in the tire circumferential direction; a third step of acquiring a second pulse row in which Nt/GCD adjacent first pulses in the first pulse row are added together to acquire N/GCD second pulses; and a maximum value F of 1st to kth order amplitudes _Fk obtained by Fourier transforming the second pulse row using the following formula (1): and a fourth step of forming the first pattern sequence such that _max satisfies the following formula (2).

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units around one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units

ここで、
Ｌ：タイヤ周長変数（タイヤ１周の全ての第１模様構成単位の長さの比の総和）
ｋ：１～２Ｎまでの自然数
Ｘ（ｊ）：第２パルス列の起点からｊ番目のパルス位置（起点からｊ番目までの第２パルスの間隔の和）
Ｐ（ｊ）：第２パルス列のｊ番目の第２パルスの大きさ
ｍ：第１模様構成単位の種類数 The present invention is a method for designing a tire having a tread pattern provided in a tread portion thereof, the method including a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction, and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction, the method including a first step of replacing the first pattern constituent units with first pulses having a magnitude corresponding to the lengths of the first pattern constituent units in the tire circumferential direction when a total number Nt of the first pattern constituent units in one revolution of the tire and a total number N of the second pattern constituent units in one revolution of the tire have a greatest common divisor GCD other than 1; a second step of replacing the first pattern row with a first pulse row in which the first pulses are arranged in the order of the arrangement of the first pattern constituent units and at intervals corresponding to the lengths of the first pattern constituent units in the tire circumferential direction; a third step of acquiring a second pulse row in which Nt/GCD adjacent first pulses in the first pulse row are added together to acquire N/GCD second pulses; and a maximum value F of 1st to kth order amplitudes _Fk obtained by Fourier transforming the second pulse row using the following formula (1): and a fourth step of determining an arrangement of the first pattern constituent units so that _max satisfies the following formula (2).

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units around one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units

ここで、
Ｌ：タイヤ周長変数（タイヤ１周の全ての第１模様構成単位の長さの比の総和）
ｋ：１～２Ｎまでの自然数
Ｘ（ｊ）：第２パルス列の起点からｊ番目のパルス位置（起点からｊ番目までの第２パルスの間隔の和）
Ｐ（ｊ）：第２パルス列のｊ番目の第２パルスの大きさ
ｍ：第１模様構成単位の種類数 The present invention provides a method for determining a tire circumferential arrangement of pattern constituent units constituting a pattern row included in a tire tread pattern, the pattern row including a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction, and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction, the method comprising the steps of: determining a tire circumferential arrangement of pattern constituent units constituting a pattern row included in a tire tread pattern, the method including ... in the tire circumferential direction, the pattern row including at least two types of first pattern constituent units having different lengths in the tire circumferential direction, the pattern row including a first step of replacing each unit with a first pulse having a magnitude corresponding to the length of the first pattern constituent units in the tire circumferential direction; a second step of replacing the first pattern string with a first pulse string in which the first pulses are arranged in the order of the arrangement of the first pattern constituent units and at intervals corresponding to the length of the first pattern constituent units in the tire circumferential direction; a third step of acquiring a second pulse string in which Nt/GCD first pulses adjacent to each other in the first pulse string are added together to obtain N/GCD second pulses; and a fourth step of determining the arrangement of the first pattern constituent units such that a maximum value _Fmax of 1st to kth order amplitudes _Fk obtained by Fourier transforming the second pulse string using the following formula (1) satisfies the following formula (2).

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units around one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between the second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units

In the tire of the present invention, when a second pulse train is obtained by adding together Nt/GCD adjacent first pulses in a first pulse train to obtain N/GCD second pulses, the maximum value Fmax of the 1st to kth amplitudes Fk obtained by Fourier transforming the second pulse train satisfies a certain condition. In such a tire, the maximum value _Fmax of the amplitudes _{Fk is} specified taking into consideration a case in which the length of the second pattern constituent unit in the tire circumferential direction differs from the length of the first pattern constituent _unit in the tire circumferential direction, and therefore pitch noise can be further reduced.

The tire manufacturing method of the present invention includes a third step of obtaining a second pulse train in which Nt/GCD adjacent first pulses in the first pulse train are added together to obtain N/GCD second pulses, and a fourth step of forming a pattern train in which the maximum value _Fmax of the 1st to kth amplitudes _Fk obtained by Fourier transforming the second pulse train satisfies a certain condition. Since this tire manufacturing method specifies the maximum value _Fmax of the amplitudes _Fk taking into consideration a case in which the length of the second pattern constituent unit in the tire circumferential direction differs from the length of the first pattern constituent unit in the tire circumferential direction, it is possible to manufacture tires with reduced pitch noise.

The tire design method of the present invention includes a third step of acquiring a second pulse train in which Nt/GCD adjacent first pulses in the first pulse train are added together to obtain N/GCD second pulses, and a fourth step of determining an arrangement of pattern constituent units such that a maximum value Fmax of 1st to kth amplitudes _Fk obtained by Fourier transforming the second pulse train satisfies a certain condition. Since this tire design method specifies the maximum _{value Fmax} of amplitudes _Fk taking into consideration a case in which the length of the second pattern constituent units in the tire circumferential direction differs from the length of the first pattern constituent units in the tire circumferential direction, it is possible to design a tire with reduced pitch noise.

The method for determining the arrangement of pattern constituent units of the present invention includes a third step of acquiring a second pulse train in which adjacent Nt/GCD first pulses in a first pulse train are added together to obtain N/GCD second pulses, and a fourth step of determining the arrangement of pattern constituent units such that the maximum value Fmax of the 1st to kth amplitudes _Fk obtained by Fourier transforming the second pulse train satisfies a certain condition. Since this method for determining the arrangement of pattern constituent units specifies the maximum value _Fmax of the amplitudes _Fk taking into consideration a case in which the length of the second pattern constituent units in the tire circumferential direction differs from the length of the first pattern constituent units in the tire circumferential _direction , it is possible to determine the arrangement of the pattern constituent units of a tire with further reduced pitch noise.

FIG. 1 is a development view showing an example of a tread portion of a tire. FIG. 4 is a diagram showing an example of a first pulse train. FIG. 4 is a diagram showing an example of a second pulse. FIG. 11 is a diagram showing an example of a second pulse train. 1 is a graph showing the relationship between amplitude _Fk and order k. 1 is a flowchart of a method for determining an arrangement of pattern constituent units.

Below, one embodiment of the present invention will be described in detail with reference to the drawings. Note that each drawing is intended to facilitate understanding of the contents of the invention, and may include exaggerated representations, and the scales, etc., of each drawing are not strictly consistent.

Figure 1 is a development view showing an example of the tread portion 2 of a tire 1 of this embodiment. As shown in Figure 1, the tread portion 2 of the tire 1 of this embodiment is provided with a tread pattern 3.

The tread pattern 3 of this embodiment is configured to include a pattern row 5 in which a plurality of pattern constituent units 4 are arranged in the tire circumferential direction. At least two pattern rows 5 are provided, and in this embodiment, five rows are provided. The pattern rows 5 of this embodiment include a pair of first pattern rows 5A in which a plurality of first pattern constituent units 4A are arranged in the tire circumferential direction, and a pair of second pattern rows 5B in which a plurality of second pattern constituent units 4B are arranged in the tire circumferential direction.

The pattern row 5 of this embodiment further includes one third pattern row 5C in which a plurality of third pattern constituent units 4C are arranged in the tire circumferential direction. That is, the pattern constituent units 4 of this embodiment include first pattern constituent units 4A arranged in a first pattern row 5A, second pattern constituent units 4B arranged in a second pattern row 5B, and third pattern constituent units 4C arranged in a third pattern row 5C.

The first pattern row 5A of this embodiment includes at least two types of first pattern constituent units 4A with different lengths D1 in the tire circumferential direction. The types of lengths D1 of the first pattern constituent units 4A can be set appropriately depending on, for example, the vehicle on which the tire 1 is mounted and the road surface conditions. It is desirable to arrange the at least two types of first pattern constituent units 4A randomly. Such a first pattern row 5A can be expected to have a noise reduction effect due to so-called pitch variation, which disperses pitch noise over a wide frequency range and turns it into white noise.

Unless otherwise specified in this specification, the dimensions of each part of the tire 1 are values measured in a normal state. In the case of a pneumatic tire, the "normal state" refers to an unloaded state in which the tire 1 is mounted on a normal rim and adjusted to the normal internal pressure.

A "genuine rim" is a rim that is determined for each tire by the standard system that includes the standard on which tire 1 is based. For example, in the case of JATMA, it is called a "standard rim," in the case of TRA, it is called a "design rim," and in the case of ETRTO, it is called a "measuring rim."

"Normal internal pressure" is the air pressure set for each tire by each standard in the standard system, including the standard on which tire 1 is based. For JATMA, it is the "maximum air pressure." For TRA, it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." For ETRTO, it is the "INFLATION PRESSURE."

When comparing the ratio D1/Dc of the length D1 of the first pattern constituent unit 4A in the tire circumferential direction to the median Dc of the lengths D1 of at least two types of first pattern constituent units 4A in the tire circumferential direction, the absolute value of the difference in the ratio D1/Dc is preferably 0.05 to 0.35. Here, when the first pattern constituent unit 4A has five lengths ( _D1LL , _D1L , _D1M , _D1S , _D1SS ), the median Dc corresponds to the central length _D1M .

When the absolute value of the difference is 0.05 or more, the pitch variation noise reduction effect can be effectively achieved. From this perspective, the absolute value of the difference is preferably 0.10 or more, and more preferably 0.15 or more.

By making the absolute value of the difference 0.35 or less, it is possible to prevent the stiffness difference between the pattern constituent units 4 from becoming too large, and to prevent uneven wear of the tread portion 2. From this perspective, the absolute value of the difference is preferably 0.30 or less, and more preferably 0.25 or less.

The total number Nt of the first pattern constituent units 4A in one revolution of the tire can be set appropriately for the first pattern row 5A. The total number Nt of the first pattern constituent units 4A in one revolution of the tire is preferably 30 to 90.

When the total number Nt is 30 or more, the noise reduction effect of pitch variation can be fully exerted. From this perspective, the total number Nt is preferably 40 or more, and more preferably 50 or more.

By setting the total number Nt to 90 or less, uneven wear of the tread portion 2 can be suppressed. From this perspective, the total number Nt is preferably 80 or less, and more preferably 70 or less.

The first pattern structural unit 4A is composed of, for example, one block 6 and one lateral groove 7 adjacent to the block 6 on one side in the tire circumferential direction. The first pattern row 5A in this embodiment is a block pattern. It is desirable that the block 6 is divided into a lateral groove 7 and a main groove 8 that extends in a direction intersecting with the lateral groove 7 and continues in the tire circumferential direction. Note that the first pattern row 5A is not limited to a block pattern and may be, for example, a rib pattern.

The second pattern row 5B of this embodiment includes at least two types of second pattern constituent units 4B that differ in circumferential length D2. The types of second pattern constituent units 4B that differ in length D2 can be set appropriately depending on, for example, the vehicle on which the tire 1 is mounted and the road surface conditions. It is desirable to arrange the at least two types of second pattern constituent units 4B randomly. Such a second pattern row 5B can be expected to have a noise reduction effect due to so-called pitch variation, which disperses pitch noise over a wide frequency range and turns it into white noise.

The second pattern row 5B can be set as appropriate for the total number N of second pattern constituent units 4B in one revolution of the tire. In this embodiment, the total number N of second pattern constituent units 4B in one revolution of the tire is smaller than the total number Nt of first pattern constituent units 4A in one revolution of the tire. It is desirable for the total number Nt of first pattern constituent units 4A in one revolution of the tire and the total number N of second pattern constituent units 4B in one revolution of the tire to have a greatest common denominator GCD other than 1.

The circumferential length D2 of the second pattern constituent unit 4B in the tread pattern 3 is Nt/N times, or in this embodiment, twice, the circumferential length D1 of the first pattern constituent unit 4A. Such a tire 1 can form an optimal pattern constituent unit 4 depending on the axial position of the pattern row 5.

The second pattern structural unit 4B is composed of, for example, one rib 9 and at least one horizontal groove 7 with at least one end terminating within this rib 9. The second pattern row 5B in this embodiment is a rib pattern. Note that the second pattern row 5B is not limited to a rib pattern and may be, for example, a block pattern.

The third pattern row 5C of this embodiment includes at least two types of third pattern constituent units 4C with the same pitch as the circumferential length D1 of the first pattern constituent units 4A. Together with the first pattern row 5A, such a third pattern row 5C is expected to have a noise reduction effect due to so-called pitch variation, which disperses pitch noise over a wide frequency range and turns it into white noise.

The third pattern unit 4C is composed of, for example, one rib 9 and at least one horizontal groove 7 with at least one end terminating within this rib 9. The third pattern row 5C in this embodiment is a rib pattern. Note that the third pattern row 5C is not limited to a rib pattern and may be, for example, a block pattern.

Fig. 2 is a diagram showing an example of a first pulse train 11 for obtaining the amplitude _Fk . In Fig. 2, the horizontal axis represents the interval G between the first pulses 10, and the vertical axis represents the magnitude B of the first pulses 10. As shown in Figs. 1 and 2, the pitch noise of the tire 1 can be grasped by arranging the first pattern constituent units 4A by replacing them with first pulses 10 having a magnitude B corresponding to the length D1 of the first pattern constituent units 4A in the tire circumferential direction, for example.

It is preferable that the magnitude B of the first pulse 10 is defined as the ratio D1/Dc of the circumferential length D1 of the first pattern constituent unit 4A corresponding to the first pulse 10 to the median Dc of the circumferential lengths D1 of at least two types of first pattern constituent units 4A.

The magnitude B of the at least two types of first pulses 10, defined as the ratio D1/Dc, preferably has an absolute difference of 0.05 to 0.35.

When the absolute value of the difference is 0.05 or more, the pitch variation noise reduction effect can be effectively achieved. From this perspective, the absolute value of the difference is preferably 0.10 or more, and more preferably 0.15 or more.

By making the absolute value of the difference 0.35 or less, it is possible to prevent the stiffness difference between the pattern constituent units 4 from becoming too large, and to prevent uneven wear of the tread portion 2. From this perspective, the absolute value of the difference is preferably 0.30 or less, and more preferably 0.25 or less.

The first pulse train 11 of this embodiment is a first pattern train 5A in which the first pulses 10 are arranged in the order of the arrangement of the first pattern constituent units 4A, with an interval G corresponding to the circumferential length D1 of the first pattern constituent units 4A. It is preferable that the first pulse train 11 is arranged with the first pulses 10 for one revolution of the first pattern train 5A. Therefore, the total number of first pulses 10 is the total number Nt of the first pattern constituent units 4A in one revolution of the tire. Note that the first pulse train 11 may be replaced from the third pattern train 5C, for example.

It is preferable that the interval G between the first pulses 10 is defined as the ratio D1/Dc of the circumferential length D1 of the first pattern constituent unit 4A corresponding to the first pulse 10 to the median Dc of the circumferential lengths D1 of at least two types of first pattern constituent units 4A.

It is preferable that the interval G between the first pulses 10 is defined according to the length D1 in the tire circumferential direction of the first pattern constituent unit 4A corresponding to one of the pair of first pulses 10 constituting the interval G. The interval G between the first pulses 10 may be defined according to, for example, the average value of the lengths D1 in the tire circumferential direction of the two first pattern constituent units 4A corresponding to the pair of first pulses 10 constituting the interval G.

The absolute value of the difference between the interval G between at least two types of first pulses 10, defined as the ratio D1/Dc, is preferably 0.05 to 0.35.

When the absolute value of the difference is 0.05 or more, the pitch variation noise reduction effect can be effectively achieved. From this perspective, the absolute value of the difference is preferably 0.10 or more, and more preferably 0.15 or more.

By making the absolute value of the difference 0.35 or less, it is possible to prevent the stiffness difference between the pattern constituent units 4 from becoming too large, and to prevent uneven wear of the tread portion 2. From this perspective, the absolute value of the difference is preferably 0.30 or less, and more preferably 0.25 or less.

Fig. 3 is a diagram showing an example of the second pulse 12 for obtaining the amplitude _Fk , and Fig. 4 is a diagram showing an example of the second pulse train 13. In Fig. 3 and Fig. 4, the horizontal and vertical axes correspond to Fig. 2. As shown in Fig. 2 to Fig. 4, the tire 1 of this embodiment obtains the second pulse train 13 from the first pulse train 11.

The second pulse train 13 is, for example, Nt/GCD adjacent first pulses 10 in the first pulse train 11 added together to form N/GCD second pulses 12. In the present embodiment, the second pulse train 13 is exemplified by adding two adjacent first pulses 10 in the first pulse train 11 together to form one second pulse 12. Such a second pulse train 13 can grasp the pitch noise of the first pattern train 5A taking into account the influence of the second pattern train 5B.

The magnitude of the second pulse 12 is, for example, the sum of the magnitudes of the first pulses 10 that are added together. It is desirable that the magnitude of the second pulse 12 is the sum of the magnitudes of the Nt/GCD first pulses 10 that are added together, distributed to N/GCD.

The interval between the second pulses 12 can be determined appropriately according to, for example, the circumferential length D2 of the second pattern constituent units 4B. Therefore, the total number of second pulses 12 in this embodiment is the same as the total number N of second pattern constituent units 4B in one revolution of the tire. Note that when the second pulse 12 is the sum of two first pulses 10, the position of the second pulse 12 may be, for example, the midpoint of the first pulses 10 that are added together.

ここで、
Ｌ：タイヤ周長変数（タイヤ１周の全ての第１模様構成単位４Ａの長さＤ１の比Ｄ１／Ｄｃの総和）
ｋ：１～２Ｎまでの自然数
Ｘ（ｊ）：第２パルス列１３の起点からｊ番目のパルス位置（起点からｊ番目までの第２パルス１２の間隔の和）
Ｐ（ｊ）：第２パルス列１３のｊ番目の第２パルス１２の大きさ
ｍ：第１模様構成単位４Ａの種類数 As shown in FIG. 4, the tire 1 of the present embodiment is configured such that, among 1st to kth order amplitudes _Fk obtained by Fourier transforming the second pulse train 13 using the following formula (1), the maximum value _Fmax of the amplitude _Fk satisfies the following formula (2).

here,
L: tire circumference parameter (the sum of the ratios D1/Dc of the lengths D1 of all the first pattern constituent units 4A around the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train 13 (sum of intervals between the second pulses 12 from the starting point to the jth pulse)
P(j): the magnitude of the j-th second pulse 12 in the second pulse train 13 m: the number of types of the first pattern constituent units 4A

The tire circumference variable L in the above formula (1) is defined as the sum of the ratios D1/Dc of the length D1 to the median value Dc for all the first pattern constituent units 4A arranged around one circumference of the tire shown in FIG. 1.

The pulse position X(j) (j is a natural number from 1 to N) in the above formula (1) is defined by the position from an arbitrary starting point s of the second pulse train 13 to the jth second pulse 12. In other words, the pulse position X(j) is defined as the sum of the intervals PL(j) of the second pulses 12 from the starting point s to the jth second pulse 12 in the second pulse train 13, as follows:
X(1)=P L(1)
X(2)=PL(1)+PL(2)
・
・
・
X(j)=PL(1)+PL(2)+...+PL(j)

The starting point s can be selected at any position in the second pulse train 13, and may be selected, for example, at a position overlapping with the second pulse 12. When the starting point s overlaps with the second pulse 12, the first second pulse 12 is the second pulse 12 following the overlapping second pulse 12. When the starting point s does not overlap with the second pulse 12, the interval PL(1) from the starting point s to the first second pulse 12 corresponds to the length from the starting point s to the first second pulse 12.

The magnitude P(j) of the second pulse 12 in the above formula (1) is defined as the magnitude of the jth second pulse 12 from the starting point s of the second pulse train 13. In this embodiment, the magnitude P(j) of the second pulse 12 is defined as the sum of the magnitudes of the Nt/GCD first pulses 10 that are added together, distributed to N/GCD.

Fig. 5 is a graph showing the relationship between the amplitude _Fk and the order k. In Fig. 5, the horizontal axis shows the order k, and the vertical axis shows the amplitude _Fk . As shown in Fig. 5, the amplitude _Fk in this embodiment is correlated with the magnitude of noise energy when the pitch noise of the tire 1 during running is frequency analyzed.

In the tire 1 of this embodiment, the maximum value _Fmax of the amplitude _Fk is specified according to the number m of types of first pattern constituent units 4A and the total number Nt of first pattern constituent units 4A in one revolution. That is, when there are two types of first pattern constituent units 4A, the maximum value _Fmax of the amplitude _Fk is less than 13.5-0.105 Nt. When there are three types of first pattern constituent units 4A, the maximum value _Fmax of the amplitude _Fk is less than 10.5-0.055 Nt. When there are five types of first pattern constituent units 4A, the maximum value _Fmax of the amplitude _Fk is less than 10.5-0.065 Nt.

In such a tire 1, pitch noise can be further reduced because the maximum value _Fmax of the amplitude _Fk taking into account the tread pattern 3 is specified according to the number m of types and the total number Nt of the first pattern constituent units 4A. Therefore, in the tire 1 of this embodiment, even if the length D2 in the tire circumferential direction of the second pattern constituent units 4B in the tread pattern 3 differs from the length D1 in the tire circumferential direction of the first pattern constituent units 4A, pitch noise can be further reduced.

Among the 1st to kth order amplitudes _Fk , the 1st order amplitude _F1 affects the noise energy that fluctuates once per tire revolution. Such a 1st order amplitude _F1 may cause, for example, a humming noise during running and may also cause vibrations inside the vehicle during running.

Of the 1st to kth order amplitudes _Fk , the 1st order amplitude _F1 is preferably equal to or less than 2.0, and more preferably equal to or less than 1.0. Such a tire 1 can suppress humming noise during running, and can effectively suppress vibrations inside the vehicle during running.

Of the 1st to kth order amplitudes _Fk , it is desirable that amplitudes _Fk that are 2/3 or more of the maximum value _Fmax do not occur consecutively in adjacent orders k. Such a tire 1 can prevent loud sounds of adjacent frequencies from interfering with each other, and can further suppress humming noise during running.

Next, a method for determining the arrangement of the pattern constituent units 4 according to this embodiment will be described with reference to FIGS.
6 is a flowchart of the method for determining the arrangement of the pattern constituent units 4 according to the present embodiment. As shown in FIG. 6, the method for determining the arrangement of the pattern constituent units 4 according to the present embodiment is a method for determining the arrangement of the pattern constituent units 4 constituting the pattern row 5 in the tire circumferential direction for the pattern row 5 included in the tread pattern 3 of the tire 1.

The pattern row 5 of this embodiment includes a first pattern row 5A in which at least two types of first pattern constituent units 4A with different circumferential lengths D1 are arranged in the tire circumferential direction, and a second pattern row 5B in which a plurality of second pattern constituent units 4B are arranged in the tire circumferential direction. In this embodiment, the total number Nt of first pattern constituent units 4A in one revolution of the tire and the total number N of second pattern constituent units 4B in one revolution of the tire have a greatest common denominator GCD other than 1. The method for determining the arrangement of the pattern constituent units 4 of this embodiment is intended for a tread pattern 3 including such a pattern row 5.

In the method for determining the arrangement of the pattern constituent units 4 in this embodiment, a first step S1 is performed in which the first pattern constituent unit 4A is replaced with a first pulse 10 having a magnitude B corresponding to the length D1 of the first pattern constituent unit 4A in the tire circumferential direction. This first step S1 is useful for understanding pitch noise.

In the method for determining the arrangement of the pattern constituent units 4 in this embodiment, after the first step S1, a second step S2 is performed in which the first pattern sequence 5A is replaced with a first pulse sequence 11. In the second step S2, it is preferable to replace the first pulses 10 with the first pulse sequence 11 arranged in the order of the arrangement of the first pattern constituent units 4A, with an interval G corresponding to the length D1 of the first pattern constituent units 4A in the tire circumferential direction.

In the method for determining the arrangement of the pattern constituent units 4 in this embodiment, after the second step S2, a third step S3 is performed to obtain a second pulse train 13. In the third step S3, it is preferable to obtain a second pulse train 13 in which Nt/GCD first pulses 10 adjacent to each other in the first pulse train 11 are added together to obtain N/GCD second pulses 12. This third step S3 can grasp pitch noise taking into account the case where the circumferential length D2 of the second pattern constituent unit 4B differs from the circumferential length D1 of the first pattern constituent unit 4A.

In the method for determining the arrangement of the pattern constituent units 4 in this embodiment, after the third step S3, a fourth step S4 is carried out in which the arrangement of the first pattern constituent units 4A is determined. In the fourth step S4, it is desirable to determine the arrangement of the first pattern constituent units 4A so that the maximum value _Fmax of the 1st to kth amplitudes _Fk obtained by Fourier transforming the second pulse train 13 using the above formula (1) satisfies the above formula (2).

In the fourth step S4, the maximum value _Fmax of the amplitude _Fk taking into account the tread pattern 3 is defined as in the above formula (2), so that it is possible to determine the arrangement of the pattern constituent units 4 of the tire 1 with further reduced pitch noise.

Next, a method for designing the tire 1 of the present embodiment will be described with reference to FIGS.
The method for designing a tire 1 according to this embodiment is a method for designing a tire 1 having a tread pattern 3 including a first pattern row 5A and a second pattern row 5B in a tread portion 2. The first pattern row 5A according to this embodiment has at least two types of first pattern constituent units 4A with different circumferential lengths D1 arranged in the tire circumferential direction. The second pattern row 5B has a plurality of second pattern constituent units 4B arranged in the tire circumferential direction.

In this embodiment, the total number Nt of first pattern constituent units 4A in one revolution of the tire and the total number N of second pattern constituent units 4B in one revolution of the tire have a greatest common denominator GCD other than 1. The method for determining the arrangement of pattern constituent units 4 in this embodiment is intended for a tread pattern 3 that includes such a pattern row 5.

In the design method for tire 1 of this embodiment, first, a first step S1 is performed in which first pattern constituent unit 4A is replaced with a first pulse 10 having a magnitude B corresponding to the length D1 of first pattern constituent unit 4A in the tire circumferential direction. This first step S1 is useful for understanding pitch noise.

In the design method for tire 1 of this embodiment, after first step S1, a second step S2 is performed in which first pattern sequence 5A is replaced with first pulse sequence 11. In second step S2, it is preferable to replace first pulses 10 with first pulse sequence 11 arranged in the order of arrangement of first pattern constituent units 4A with intervals G corresponding to length D1 of first pattern constituent units 4A in the tire circumferential direction.

In the design method for tire 1 of this embodiment, after second step S2, a third step S3 is performed to obtain a second pulse train 13. In the third step S3, it is preferable to obtain a second pulse train 13 by adding together Nt/GCD adjacent first pulses 10 of the first pulse train 11 to obtain N/GCD second pulses 12. This third step S3 can grasp pitch noise taking into account the case where the length D2 of the second pattern constituent unit 4B in the tire circumferential direction is different from the length D1 of the first pattern constituent unit 4A in the tire circumferential direction.

In the method for designing tire 1 of the present embodiment, after the third step S3, a fourth step S4 is performed in which an arrangement of first pattern constituent units 4A is determined so that the maximum value _Fmax of the 1st to kth amplitudes _Fk obtained by Fourier transforming second pulse train 13 using the above formula (1) satisfies the above formula (2).

In the fourth step S4, the maximum value _Fmax of the amplitude _Fk taking into account the tread pattern 3 is defined as in the above formula (2), so that a tire 1 with reduced pitch noise can be designed.

Next, a method for manufacturing the tire 1 of the present embodiment will be described with reference to FIGS.
The manufacturing method of the tire 1 of this embodiment is a method for manufacturing a tire 1 having a tread pattern 3 including a first pattern row 5A and a second pattern row 5B in a tread portion 2. The first pattern row 5A of this embodiment has at least two types of first pattern constituent units 4A with different circumferential lengths D1 arranged in the tire circumferential direction. The second pattern row 5B has a plurality of second pattern constituent units 4B arranged in the tire circumferential direction.

In this embodiment, the total number Nt of first pattern constituent units 4A in one revolution of the tire and the total number N of second pattern constituent units 4B in one revolution of the tire have a greatest common denominator GCD other than 1. The method for determining the arrangement of pattern constituent units 4 in this embodiment is intended for a tread pattern 3 that includes such a pattern row 5.

In the manufacturing method of the tire 1 of this embodiment, first, a first step S1 is performed in which the first pattern constituent unit 4A is replaced with a first pulse 10 having a magnitude B corresponding to the length D1 of the first pattern constituent unit 4A in the tire circumferential direction. This first step S1 is useful for understanding the pitch noise.

In the manufacturing method of the tire 1 of this embodiment, after the first step S1, a second step S2 is performed in which the first pattern sequence 5A is replaced with a first pulse sequence 11. In the second step S2, it is preferable to replace the first pulses 10 with the first pulse sequence 11 arranged in the order of the arrangement of the first pattern constituent units 4A, with an interval G corresponding to the length D1 of the first pattern constituent units 4A in the tire circumferential direction.

In the manufacturing method of the tire 1 of this embodiment, after the second step S2, a third step S3 is performed to obtain the second pulse train 13. In the third step S3, it is preferable to obtain the second pulse train 13 by adding together Nt/GCD adjacent first pulses 10 of the first pulse train 11 to obtain N/GCD second pulses 12. Such a third step S3 can grasp pitch noise taking into account the case where the length D2 in the tire circumferential direction of the second pattern constituent unit 4B is different from the length D1 in the tire circumferential direction of the first pattern constituent unit 4A.

In the manufacturing method of tire 1 of the present embodiment, after the third step S3, a fourth step S4 is performed in which a first pattern train 5A is formed such that the maximum value _Fmax of the 1st to kth order amplitudes _Fk obtained by Fourier transforming the second pulse train 13 using the above formula (1) satisfies the above formula (2).

In the fourth step S4, the maximum value _Fmax of the amplitude _Fk taking into account the tread pattern 3 is defined as in the above formula (2), so that a tire 1 with reduced pitch noise can be manufactured.

The above describes in detail a particularly preferred embodiment of the present invention, but the present invention is not limited to the illustrated embodiment and can be modified in various ways.

A tire having the arrangement of the pattern components shown in FIG. 1 was prototyped based on the specifications in Tables 1 and 2.

The prototype tires were fitted to all wheels of an actual vehicle, and interior noise tests were conducted as sound pressure tests and sensory tests. The common specifications and test methods for the prototype tires are as follows:

<Common specifications>
Tire size: 215/60R16 95T
Rim size: 16 x 6.5J
Air pressure: 230kPa
Total number of first pattern units Nt: 72
Number of types of first pattern constituent units m: 5 types

<Sound pressure test>
Using a Japanese-made large passenger vehicle with prototype tires fitted to all wheels, the sound pressure inside the vehicle was measured while the vehicle was traveling on a test course for measuring road noise at speeds of 45 km/h, 60 km/h, and 120 km/h. The results are expressed as an index with the comparative example being set at 100, with smaller values indicating lower sound pressure and better noise performance.

<Sensory test>
Using a Japanese-made large passenger vehicle with prototype tires fitted on all wheels, the vehicle was driven on a test course for measuring road noise at speeds of 45 km/h, 60 km/h, and 120 km/h, and the interior noise was evaluated by the test driver. The results were evaluated on a 10-point scale, with the higher the score, the lower the interior noise and the better the noise performance.

The results of the test are shown in Table 2.

The test results confirmed that the tires of the embodiment had superior noise performance and reduced pitch noise compared to the tires of the comparison example.

Reference Signs List 1 Tire 2 Tread portion 3 Tread pattern 4 Pattern constituent unit 5 Pattern train 10 Pulse 11 First pulse train 12 Second pulse train 13 Third pulse train

Claims (11)

A tire having a tread portion,
The tread portion is provided with a tread pattern including a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction, and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction,
The first pattern unit and the second pattern unit each include at least one transverse groove;
a total number Nt of the first pattern constituent units in one circumference of the tire and a total number N of the second pattern constituent units in one circumference of the tire have a greatest common divisor GCD other than 1,
The first pattern constituent unit is replaced with a first pulse having a magnitude corresponding to a length of the first pattern constituent unit in a tire circumferential direction,
The first pattern string is replaced with a first pulse string in which the first pulses are arranged in the order of the arrangement of the first pattern constituent units, with intervals corresponding to the lengths of the first pattern constituent units in the tire circumferential direction;
When a second pulse train is obtained by adding Nt/GCD adjacent first pulses of the first pulse train to obtain N/GCD second pulses,
The maximum value Fmax of the first to kth amplitudes Fk obtained by Fourier transforming the second pulse train using the following formula (1) satisfies the following formula (2):
tire.

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units on one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units
The tire according to claim 1, wherein the second pulse train is formed by adding two adjacent pulses of the first pulse train together to form one second pulse. The tire according to claim 1 or 2, wherein the magnitude of the first pulse is defined as a ratio of the length in the tire circumferential direction of the first pattern constituent unit corresponding to the first pulse to the median of the lengths in the tire circumferential direction of at least two types of the first pattern constituent units. The tire of claim 3, wherein the ratio is between 0.05 and 0.35. The tire according to any one of claims 1 to 4, wherein, among the 1st to kth order amplitudes _Fk , a 1st order amplitude _F1 is 2.0 or less. The tire according to any one of claims 1 to 4, wherein, among the 1st to kth order amplitudes _Fk , a 1st order amplitude _F1 is 1.0 or less. The tire according to any one of claims 1 to 6, wherein, among the amplitudes F _k of the 1st to kth orders, the amplitudes F _k that are ⅔ or more of the maximum value F _max are not consecutive in adjacent orders. The tire according to any one of claims 1 to 7, wherein the total number Nt of the first pattern constituent units in one circumference of the tire is 30 to 90. A method for manufacturing a tire having a tread pattern provided in a tread portion thereof, the method including: a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction; and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction, the method comprising the steps of:
The first pattern unit and the second pattern unit each include at least one transverse groove;
When the total number Nt of the first pattern constituent units in one tire revolution and the total number N of the second pattern constituent units in one tire revolution have a greatest common divisor GCD other than 1,
a first step of replacing the first pattern constituent unit with a first pulse having a magnitude corresponding to a length of the first pattern constituent unit in a tire circumferential direction;
a second step of replacing the first pattern string with a first pulse string in which the first pulses are arranged in the order of arrangement of the first pattern constituent units and at intervals corresponding to the length of the first pattern constituent units in the tire circumferential direction;
a third step of acquiring a second pulse train by adding Nt/GCD adjacent first pulses of the first pulse train to obtain N/GCD second pulses;
and a fourth step of forming the first pattern sequence such that a maximum value Fmax of 1st to kth amplitudes Fk obtained by Fourier transforming the second pulse sequence using the following formula (1) satisfies the following formula (2),
A method for manufacturing tires.

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units around one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units
A method for designing a tire having a tread pattern provided in a tread portion thereof, the method including: a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction; and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction, the method comprising the steps of:
The first pattern unit and the second pattern unit each include at least one transverse groove;
When the total number Nt of the first pattern constituent units in one tire revolution and the total number N of the second pattern constituent units in one tire revolution have a greatest common divisor GCD other than 1,
a first step of replacing the first pattern constituent unit with a first pulse having a magnitude corresponding to a length of the first pattern constituent unit in a tire circumferential direction;
a second step of replacing the first pattern string with a first pulse string in which the first pulses are arranged in the order of arrangement of the first pattern constituent units and at intervals corresponding to the length of the first pattern constituent units in the tire circumferential direction;
a third step of acquiring a second pulse train by adding Nt/GCD adjacent first pulses of the first pulse train to obtain N/GCD second pulses;
and a fourth step of determining an arrangement of the first pattern constituent units so that a maximum value Fmax of 1st to kth amplitudes Fk obtained by Fourier transforming the second pulse train using the following formula (1) satisfies the following formula (2),
How tires are designed.

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units around one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units
A method for determining a circumferential arrangement of pattern constituent units constituting a pattern row included in a tire tread pattern, the method comprising the steps of:
The pattern row includes a first pattern row in which at least two types of first pattern constituent units having different lengths in the tire circumferential direction are arranged in the tire circumferential direction, and a second pattern row in which a plurality of second pattern constituent units are arranged in the tire circumferential direction,
The first pattern unit and the second pattern unit each include at least one transverse groove;
When the total number Nt of the first pattern constituent units in one tire revolution and the total number N of the second pattern constituent units in one tire revolution have a greatest common divisor GCD other than 1,
a first step of replacing the first pattern constituent unit with a first pulse having a magnitude corresponding to a length of the first pattern constituent unit in a tire circumferential direction;
a second step of replacing the first pattern string with a first pulse string in which the first pulses are arranged in the order of arrangement of the first pattern constituent units and at intervals corresponding to the length of the first pattern constituent units in the tire circumferential direction;
a third step of acquiring a second pulse train by adding Nt/GCD adjacent first pulses of the first pulse train to obtain N/GCD second pulses;
and a fourth step of determining an arrangement of the first pattern constituent units so that a maximum value Fmax of 1st to kth amplitudes Fk obtained by Fourier transforming the second pulse train using the following formula (1) satisfies the following formula (2),
A method for determining the arrangement of pattern building blocks.

here,
L: tire circumference parameter (sum of the length ratios of all the first pattern constituent units around one circumference of the tire)
k: natural number from 1 to 2N X(j): jth pulse position from the starting point of the second pulse train (sum of intervals between the second pulses from the starting point to the jth pulse)
P(j): The magnitude of the j-th second pulse in the second pulse train m: The number of types of first pattern constituent units

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