JP5103042B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that can be filled with nitrogen gas or other inert gas in addition to air, and more particularly to a tire for passenger cars, and in particular, in the circumferential direction of the tread surface, The present invention proposes a technique for effectively reducing air column resonance generated by a main groove extending continuously in a zigzag shape under the action of a resonator.

  The air column resonance sound is noise generated by resonance of air in the pipe surrounded by the main groove extending continuously in the circumferential direction of the tread tread and the road surface in the tread tread surface contact area. The sound frequency is often observed at about 800 to 1200 Hz in a general passenger car, and since the peak sound pressure level is high and the frequency band is wide, it occupies a large part of the noise generated by the tire.

  In addition, since human hearing is particularly sensitive in the above frequency band, reduction of air column resonance is effective in improving the quietness of the feeling surface.

Therefore, in order to reduce air column resonance noise, the volume of the main groove has been widely reduced, and it has also been proposed to provide a so-called groove fence that blocks the main groove. As disclosed in Patent Document 1, a resonator having a long lateral groove having only one end opened in the main groove and the other end ending in the land portion is provided, and an anti-resonance in the lateral groove is used. Techniques for reducing column resonance noise, as described in Patent Documents 2 and 3, have also been proposed for absorbing energy in the vicinity of the resonance frequency of air column resonance sound by a Helmholtz resonator.
WO04 / 103737 pamphlet Japanese Patent Laid-Open No. 5-338411 JP 2000-118207 A

  However, by reducing the groove volume of the main groove and providing a groove fence in the main groove, the drainage performance is inevitably lowered, resulting in a decrease in steering stability and resistance to wet roads. There has been a problem that there is a high risk of a decrease in the hide planing performance.

  Further, in each of Patent Documents 1 to 3, the resonator is directly opened in the circumferential main grooves extending independently of each other, and at least one is always provided in the ground plane. Since each resonator is arranged to include a resonator, the degree of freedom in designing the tread pattern is small, and it is necessary to maximize the sound reduction effect in each main groove, There is a problem that it is difficult to dispose a plurality of resonators having different resonance frequencies. In addition, in these patent documents, it is difficult to communicate the circumferential main grooves with a lateral groove or the like. Since the grooves resonate at the same resonance frequency and increase the peak value, from the viewpoint of being disadvantageous for air column resonance, the lateral grooves that open in the adjacent main grooves are intentionally omitted. Low drainage performance Problem that it is not denied even there.

  The present invention has an object to solve such problems of the prior art, and the object of the present invention is to ensure effective improvement of drainage performance, while a plurality of resonators. By sharing the main groove with multiple main grooves, the design freedom of the tread pattern can be increased, and multiple resonators with different resonance frequencies can function simultaneously for each main groove. It is in providing the pneumatic tire which can reduce effectively.

The pneumatic tire according to the present invention is provided with a plurality of main grooves having a linear shape, a zigzag shape or the like extending continuously in the circumferential direction on the tread surface, and two or more adjacent to each other. A plurality of types of resonance with different resonance frequencies, independent of other main grooves and lateral grooves, with a horizontal groove opening in the main groove, one end opening in the main groove or the lateral groove and the other end ending in the land. A horizontal groove that opens to the main groove is filled with the specified air pressure in the tire mounted on the applicable rim, and one load is applied to the tire in the contact surface with a load of 80% of the specified mass. The above arrangement is always completely included, and each resonator is filled with a specified air pressure in a tire mounted on an applicable rim, and a load of 80% of a specified mass is applied to the tire. Multiple ground planes with different resonance frequencies Resonator in which is always the arrangement mode included in full.

  Here, the “lateral groove” includes not only a groove extending in the width direction of the tread surface, but also an inclined groove extending in any direction with respect to the width direction of the tread surface.

  Here, the resonator is constituted by the branch groove itself branched from the main groove or the lateral groove, and the tire mounted on the applicable rim is filled with the prescribed air pressure, and a load of 80% of the prescribed mass acts on the tire. Under the condition, the extension length (l) of each branch groove in the ground plane is the length in the ground plane of the main groove that the branch groove opens directly or indirectly. The ratio (l / L) to the extension length (L) of the shortest main groove is preferably 0.4 or more.

  The “branch groove” here may be a tunnel-like one in the land portion, or a groove edge in contact with each other in the ground plane. It is assumed that the groove walls have such a width that the groove walls are separated from each other.

In this case, “applicable rim” refers to the rim specified in the following standards according to the tire size, and “specified air pressure” refers to the air pressure specified in accordance with the maximum load capacity in the following standards. The maximum load capacity refers to the maximum mass allowed to be loaded on the tire according to the following standards. The “specified mass” refers to the above maximum load capacity.
The air here can be replaced with an inert gas such as nitrogen gas or the like.

  The standard is an industrial standard that is valid in the region where tires are produced or used. For example, “THE TIRE AND RIM ASSOCIATION INC. YEAR BOOK” in the United States, and “THE European Tire and Rim Technical” in Europe. “STANDARDS MANUAL” of Organsation, and “JATMA YEAR BOOK” of Japan Automobile Tire Association in Japan.

Here, the tread tread surface contact condition is “a state in which a load of 80% of the specified mass is applied” is to reduce the air column resonance noise under the general use conditions of the tire. It is intended for illustration.
By the way, the extension length (l, L) of the groove here refers to the extension length of the groove center line.

  Preferably, the resonator is formed in a branch groove branched from the main groove or the lateral groove and at the tip of the branch groove in place of the above, and the cross-sectional area in the central portion is larger than that of the branch groove. It is comprised with the air chamber which opens to a tread tread surface of the cross-sectional ring part shape of this.

  Here, both “air chamber” and “branch groove” are also opened in the ground contact surface under the above-described ground contact conditions. On the other hand, “branch grooves”, like the branch grooves, may be tunnel-like in the land, or the groove edges may be in contact with each other in the ground plane. Is possible.

  In any of these cases, the resonance frequency of the resonator is preferably in the range of 600 to 1800 Hz.

  Here, in the case where the resonator is composed of a branch groove, this resonance frequency can be obtained by the equation of a side branch type resonator described later, and is composed of a branch groove and an air chamber. In this case, for example, this can also be obtained by the Helmholtz resonator formula described later.

The main grooves are two pairs of main grooves that are symmetrical with respect to the tire equator line with a tire equator line therebetween, and the transverse grooves are adjacent to each other in each half of the tread surface. It is preferable that both ends are open to the groove.

  In the pneumatic tire according to the present invention, two or more main grooves adjacent to each other are communicated with each other by a lateral groove that can be an inclined groove, and a plurality of types of resonators are opened in the main groove or the lateral groove. As a result, the resonators can be shared by the main grooves connected to each other by the lateral grooves, so that the air column resonance sounds generated in the respective main grooves are provided. In response to this, all the resonators whose resonance frequencies are selected in advance are actuated to reduce the necessary air column resonance and other sound pressure levels, effectively reducing the air column resonance itself. The sound can be reduced.

  Further, in this tire, by making the lateral groove opened to the main groove also function as a drainage groove, drainage performance on the tread road surface, and consequently, steering stability on the wet road surface can be greatly improved.

  Therefore, here, in order to ensure that one or more resonators are always present in the ground plane, each of the plurality of resonators is directly opened in each main groove extending separately. Thus, the degree of freedom in designing the tread pattern can be greatly improved, and the arrangement of a plurality of types of resonators in each main groove can be simplified.

ｌ：接地面内での分岐溝長さ（ｍ）
Ｃ：音速（ｍ／ｓ）
その共鳴周波数ｆに対応する周波数の気柱共鳴音を有効に低減させることができる。 In such a tire, when the resonator is constituted by the branch groove itself, it is based on the resonance frequency equation of the side branch type resonator shown below.

l: Branch groove length in the ground plane (m)
C: Speed of sound (m / s)
The air column resonance sound having a frequency corresponding to the resonance frequency f can be effectively reduced.

  By the way, in this case, the extension length (l) of the branch groove in the ground plane is the longest extension length in the ground plane among the main grooves opened directly or indirectly. By setting the ratio (l / L) to the extension length (L) of the short main groove to be 0.4 or more, particularly 0.4 to 0.9, the resonance frequency f of the branch groove is changed in the circumferential direction. It can be sufficiently close to a required frequency such as the air column resonance frequency of the main groove.

That is, the resonance frequency f of the resonator is better as it approaches the air column resonance frequency, and the air column resonance frequency when there is one main groove is
Speed of sound / 2x (Main groove length in ground plane + 50-60 (mm))
The air column resonance frequency when the main grooves communicate with each other is smaller than that, but in any of these cases, the branch groove extension length (l) satisfying the above numerical range is set. By selecting, the resonance frequency (f) of the side branch type resonator can be set within the range of the air column resonance frequency.

  In other words, the resonance frequency f of the branch groove is greatly different from the air column resonance frequency regardless of whether it is less than 0.4 or more than 0.9. Therefore, it is difficult to expect effective reduction of resonance noise.

ｌ_０：接地面内での枝溝長さ（ｍ）
Ｓ：枝溝の横断面積（ｍ^２）
ｒ：（枝溝の断面積／π）^1/2
Ｖ：気室の容積（ｍ^２）
Ｃ：音速（ｍ／ｓ）
に基いて、その共鳴周波数（ｆｏ）に対応する周波数の気柱共鳴音を有効に低減させることができる。 Further, when the resonator is constituted by a branch groove and an air chamber formed at the tip of the branch groove and having a larger cross-sectional area than that, for example, the resonance frequency of the following Helmholtz resonator

l ₀ : Branch groove length in the ground plane (m)
S: Cross-sectional area of branch groove (m ² )
r: (cross-sectional area of the branch groove / π) ^1/2
V: Volume of air chamber (m ² )
C: Speed of sound (m / s)
Therefore, the air column resonance sound having a frequency corresponding to the resonance frequency (fo) can be effectively reduced.

  Here, when the resonance frequency of such a resonator is in the range of 600 to 1800 Hz, generally, with respect to the peak frequency of noise including the air column resonance frequency existing in the range of about 800 to 1200 Hz, The resonance frequency of the resonator can be appropriately selected as required.

  In addition, the lateral groove that opens to the main groove is filled with a specified air pressure in a tire mounted on the applicable rim, and a load of 80% of the specified mass is applied to the tire. In the case of an arrangement mode in which more than one is completely included, it is ensured that the adjacent main grooves communicate with each other in the ground plane, and all the resonators included in the ground plane are connected to each main groove. In addition, the drainage function can always be effectively exhibited in the lateral groove itself.

  Here, with each resonator, the tire mounted on the applicable rim is filled with a specified air pressure, and a load of 80% of the specified mass is applied to the tire. When the arrangement mode is such that a plurality of resonators are always completely included, each of the plurality of resonators functions reliably and sufficiently in the ground plane so that the air column resonance sound of the main groove is generated. It can reduce more effectively.

FIG. 1 is a developed plan view schematically showing a tread pattern of a pneumatic tire according to the present invention.
In addition, since the internal reinforcement structure of a tire is the same as that of a general radial tire, illustration is abbreviate | omitted here.

  In the figure, reference numeral 1 denotes a tread surface. In the figure, the tread surface 1 is separated from the tire equator line E and is symmetrically positioned so as to be continuously linear in the circumferential direction of the tread surface 1. Two pairs of main grooves 2 and 3 extending are provided, and between the two main grooves 2 and 3 positioned adjacent to each other, the main grooves 2 and 3 extend in an arrow-shaped manner in the figure, and both ends thereof are the main grooves 2 and 3. Each of the lateral grooves 4 opened in the circumferential direction is provided at a predetermined interval in the circumferential direction. Preferably, these lateral grooves 4, more preferably, the lateral grooves 4 of each half of the tire equator line E are mounted on an applied rim. In the state where the specified air pressure is filled and the load of 80% of the specified mass is applied to the tire, one or more of the tires are always completely included in the ground plane surrounded by the phantom line in the figure. Let it be an appearance.

  Here, one of the lateral grooves 4 is opened in three or more main grooves 2 and 3 under the cross extension of the main grooves, or in the figure, a pair of main grooves 2 is provided. It is also possible to form a lateral groove that opens to 2, and according to these, all the main grooves 2, 3 can be communicated with each other via one or a plurality of lateral grooves.

  Also, in this tire, one end opens into the main groove 2, 3 or the lateral groove 4, in the figure, the main groove 2, 3, and the other end does not intersect any other groove in the land portion between the main grooves. A plurality of types of resonators 5a, 5b, 6a, 6b, and 6c having different resonance frequencies, for example, five types are provided. Here, preferably, the respective resonators, more preferably, the respective resonators in the respective halves of the tire equator line E, are filled with a prescribed air pressure in a tire mounted on the applicable rim, and the tire has a prescribed mass. In a state where an 80% load is applied, a plurality of resonators having different resonance frequencies are always completely included in a ground plane surrounded by a virtual line in the figure.

  In this figure, the resonators opened in the main grooves 2 and 3 are arranged outside the main grooves 2 and 3 in the tread tread width direction. It is also possible to arrange part or all of the resonator inside in the width direction, and in this figure, two in the main groove 2 and three in the main groove 3 in the ground plane. Each resonator is opened and arranged, but the number of arranged resonators can be reversed from that shown in the figure, and moreover, the number of arranged resonators on the ground plane Can be increased or decreased as appropriate.

  By the way, as shown in this figure, each resonator 5a, 5b, 6a, 6b, 6c is branched from the main grooves 2 and 3, and in each half, a branch groove 7 extending substantially parallel to the lateral groove 4, An air chamber 8 is formed at the tip of the branch groove 7 and has a central portion cross-sectional area larger than the cross-sectional area in the cross section perpendicular to the groove center line of the branch groove 7 and opens to the tread surface 1. .

Here, the branch groove 7 can have a groove width in which the groove walls are separated from each other in the ground plane, or is buried in a tunnel- like manner in the land, or a groove in the ground plane. It is also possible that the edges touch each other.

ｌ_０：接地面内での横溝長さ（ｍ^２）
Ｓ：枝溝の横断面積
ｒ：（枝溝の断面積／π）^1/2
Ｖ：気室の容積（ｍ^２）
Ｃ：音速（ｍ／ｓ）
として表すことができる。 Each resonator 5a, 5b, 6a, 6b, 6c that can be configured in this way is located in the ground plane, under the condition that the air chamber 8, in many cases, the branch groove 7 is also closed by the road surface. Then, in FIG. 2A, a Helmholtz type resonator schematically illustrated in a perspective view is configured, and the resonance frequency f ₀ of this resonator is as described above.

l ₀ : transverse groove length in the ground plane (m ² )
S: Cross-sectional area of branch groove r: (cross-sectional area of branch groove / π) ^1/2
V: Volume of air chamber (m ² )
C: Speed of sound (m / s)
Can be expressed as

Therefore, in this resonator, by selecting l ₀ , S, r, and V, the resonance frequency f ₀ can be adjusted within the range of 600 to 1800 Hz as required.

  It should be noted that the resonator is constituted by a branch groove 9 that is branched from the main grooves 2 and 3 as schematically illustrated in FIG. In this case, the tire mounted on the applicable rim is filled with a prescribed air pressure, and a load of 80% of the prescribed mass is applied to the tire. The ratio (l / L) of the extension length l to the extension length L of the main grooves 2 and 3 having the extension length l that is the shortest extension length in the ground plane is 0. It is 4 or more, more preferably in the range of 0.4 to 0.9.

ｌ：接地面内での分岐溝長さ（ｍ）
Ｃ：音速（ｍ／ｓ）
として表わすことができ、ここでは、ｌの選択に基いて、共鳴周波数ｆを所要に応じて、これも好ましくは、６００〜１８００Ｈｚの範囲内にて適宜に調整することができる。 As described above, the resonance frequency f of the resonator composed of the branch groove itself, that is, the side branch type resonator, is as follows.

l: Branch groove length in the ground plane (m)
C: Speed of sound (m / s)
Here, based on the selection of l, the resonance frequency f can be adjusted as appropriate within the range of 600 to 1800 Hz, if necessary.

  By the way, the branch groove 9 here can also have a groove width such that the groove walls are separated from each other in the ground plane as in the case of the branch groove 7 described above. It is also possible for the groove edges to be in contact with each other within the ground contact surface, or for the groove edges to contact each other within the ground contact surface.

として表わすことができる。 Each resonator can also be configured in such a manner that pipes having different cross-sectional areas communicate with each other as schematically illustrated in a perspective view in FIG. 2 (c). Sound pressure in each of the pipes a and b is

Can be expressed as

Thus, resonator stepped tube type as shown in FIG. 2 (c) also can function effectively in order to reduce air column resonance _{noise, l a, l b, S} a, the S _b Under selection, the resonance frequency f ₁ can be adjusted as required, preferably in the range of 600-1800 Hz.

According to the pneumatic tire configured as described above, in particular, the tread pattern thereof, the drainage performance of the tire is improved by disposing the lateral grooves 4 that allow the adjacent main grooves 2 and 3 to communicate with each other. steering stability on a wet road surface, can be increased to enable the resistance to hydro-flop training resistance, also, the main grooves 2, 3 of them were communicated, to act as a single tube that resonates at a specific resonant frequency The plurality of types of resonators can simultaneously function with respect to the main grooves 2 and 3, whereby the air column resonance can be more effectively reduced. Furthermore, the plurality of main grooves 2 can be reduced. 3, by sharing the respective resonators, it is possible to simplify the arrangement of many types of resonators while ensuring the degree of freedom in designing the tread pattern.

  An example tire having a tread pattern shown in FIG. 1 having a size of 195 / 65R15, and comparative tires 1 and 2 having respective ground contact surface patterns shown in FIGS. 3 (a) and 3 (b). The sound pressure level of the resonance sound was measured, and the noise feeling by the driver, the steering stability on the wet road surface, and the hydroplaning resistance during cornering and straight running were obtained. The results shown in Tables 1 and 2 were obtained. .

Here, the sound pressure level of air column resonance noise is the room drum test machine, when the tire filled with inner pressure of 210k P a, was loaded rolling under a load 4 kN, speed 80 km / h, the tire The noise at the side position is measured according to JASO C606, and evaluated by obtaining a partial overall value in the band of the center frequency 800-1000-1250 Hz in the 1/3 octave band,
Noise feeling is evaluated in 10 stages with the driver's feeling when driving on the dry road of the test course,
Steering stability on the wet road surface is evaluated in 10 stages with the driver's feeling when driving on the test course on the road surface where water is sprayed (water depth of about 5mm),
The hydroplaning resistance during cornering and straight traveling was evaluated by measuring the speed of occurrence of hydroplaning phenomenon when traveling on a road surface with a water depth of 6 to 10 mm.

The frequency of each resonator of FIG. 1 and FIG. 3 (b), described above, determined according to the equation of the resonant frequency f ₀ of the Helmholtz resonator, in this case, the sound velocity C was 343.7m / s.

According to Tables 1 and 2, it can be seen that the example tires show excellent results both in reducing the air column resonance and in the actual vehicle evaluation.
On the other hand, the comparative example tire 2 cannot share the resonators by the respective main grooves, and only three resonators are arranged per one, so that the result is as good as the example tires. It is impossible.

It is a development top view of a tread pattern showing an embodiment of this invention. It is a figure which illustrates the structure of a resonator. It is a figure which shows the in-ground surface pattern of a comparative example tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread tread 2, 3 Main groove 4 Horizontal groove 5a, 5b, 6a, 6b, 6c Resonator 7 Branch groove 8 Air chamber 9 Branch groove

Claims (5)

The tread surface is provided with a plurality of main grooves extending continuously in the circumferential direction, and provided with a horizontal groove that opens to two or more main grooves adjacent to each other, with one end opening to the main groove or the horizontal groove and the other end. Is provided within the land part, provided with a plurality of types of resonators independent of other main grooves and lateral grooves, with different resonance frequencies .
The horizontal groove that opens in the main groove is filled with the specified air pressure on the tire mounted on the applicable rim, and at least one load is always completely in the grounding surface with a load of 80% of the specified mass applied to the tire. And an arrangement mode included in
Each resonator is filled with a specified air pressure in a tire mounted on an applicable rim, and a load of 80% of a specified mass is applied to the tire. A pneumatic tire as an arrangement in which the resonator is always completely included .   The resonator is composed of a branch groove branched from the main groove or the lateral groove, and the tire mounted on the applicable rim is filled with a specified air pressure, and a load of 80% of the specified mass is applied to the tire. The length (l) of each branch groove in the ground plane is the length of the main groove having the shortest length in the ground plane among the main grooves in which the branch groove opens directly or indirectly. The pneumatic tire according to claim 1, wherein the ratio (l / L) to the extended length (L) is 0.4 or more.   The resonator is composed of a branch groove branched from the main groove or the lateral groove, and an air chamber formed at the tip of the branch groove and having a transverse area at the center portion larger than that of the branch groove and opening to the tread surface. The pneumatic tire according to claim 1.   The pneumatic tire according to any one of claims 1 to 3, wherein a resonance frequency of the resonator is in a range of 600 to 1800 Hz. The main grooves are two pairs of main grooves that are symmetrical with respect to the tire equator line across the tire equator line,
The pneumatic tire according to any one of claims 1 to 4, wherein both ends of the lateral groove are open to the two main grooves located adjacent to each other in each half of the tread surface.

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