JP5013731B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having a Helmholtz type resonator that suppresses air column resonance in a circumferential groove, and more particularly to a tire that can prevent a decrease in land portion rigidity.

  The air column resonance sound is noise generated by resonance of the air in the pipe surrounded by the circumferential groove extending continuously in the circumferential direction of the tread surface and the road surface in the tread surface 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, as one of the methods for reducing air column resonance, a resonator is provided that opens in the circumferential groove and ends in the land portion. The resonator is provided with an air chamber that opens on the land surface, an air chamber, There has been proposed a technique of absorbing energy in the vicinity of the resonance frequency of the air column resonance sound by a so-called Helmholtz resonator constituted by a constricted neck that provides communication with the circumferential groove.
Japanese Patent Laid-Open No. 5-338411

  It is preferable that there is always one or more such resonators in the tire tread surface, and if this number is further increased, the effect of suppressing air column resonance can be enhanced. For this purpose, the resonators are closely packed in the circumferential direction. However, if this is made dense, there is a problem that the rigidity of the land portion is lowered and noise due to the hitting sound of the resonator is increased.

  The present invention has been made in view of such a problem, and without sacrificing the suppression effect of the Helmholtz resonator on the air column resonance of the circumferential groove, noise other than the decrease in land rigidity and noise other than the air column resonance. It is an object of the present invention to provide a pneumatic tire that can prevent an increase in tire pressure.

<1> is a constriction that provides a circumferential groove continuously extending in the circumferential direction on the tread surface, opens an air chamber on the surface of the land portion at a position away from the circumferential groove, and communicates the air chamber with the circumferential groove. In the tire which arranged the resonator which consists of a neck,
At least one of the resonators disposed between the circumferential grooves adjacent to each other has two or more of the narrowing necks, and at least two of the narrowing necks are opened to different circumferential grooves,
A pneumatic tire in which the total width of the narrowed neck when viewed from the outside of the tread surface is 3 to 20% of the width of the air chamber .

  <2> is a tread surface having a tread pattern to which pitch variations are given in <1>, and at least one resonator having a resonance frequency in a range of 700 to 1800 Hz is disposed within at least one pitch length. This is a pneumatic tire.

<3> is a pneumatic tire according to <1> or <2>, wherein an opening area of the air chamber to the land surface is in a range of 50 to 600 mm ² .

< 4 > is a pneumatic tire according to any one of <1> to < 3 >, wherein the depth of the narrowed neck is 70% or less of the maximum depth of the air chamber.

< 5 > In any one of <1> to < 4 >, the maximum depth of the air chamber from the land surface is 20 to 90% of the maximum depth of the groove that divides the land portion on the tread surface. It is a pneumatic tire.

< 6 > is a pneumatic tire according to any one of <1> to < 5 >, wherein the bottom wall of the air chamber is provided with irregularities having a height of 1.6 mm or more.

< 7 > is a pneumatic tire according to any one of <1> to < 6 >, wherein a narrowed neck of the resonator is formed by sipe.

< 8 > is a pneumatic tire according to any one of <1> to < 7 >, wherein the opening shape of the air chamber to the land surface is a curved contour shape.

< 9 > is the pneumatic tire according to any one of claims 1 to 8, wherein the opening shape of the air chamber to the land surface is a quadrilateral shape in any one of <1> to < 7 >.

< 10 > is the state in any one of <1> to < 9 >, in which the tire mounted on the applicable rim is filled with a specified air pressure and a load corresponding to 80% of the specified mass is applied to the tire. Thus, the pneumatic tire is configured such that one or more resonators are always completely included in the ground plane.

< 11 > is a state in which the tire mounted on the applicable rim is filled with a prescribed air pressure and a load corresponding to 80% of the prescribed mass is applied to the tire in any one of <1> to < 10 >. Thus, the pneumatic tire is configured such that a plurality of resonators having different resonance frequencies are always completely included in the ground plane.

According to <1>, at least one of the resonators arranged between adjacent circumferential grooves has two or more constriction necks, and at least two of these constriction necks have different circumferences. Since it opens in the groove, the air column resonance of two adjacent circumferential grooves can be reduced in one air chamber, and the rigidity of the land portion is not greatly reduced, and noise other than the air column resonance can be reduced. The air column resonance suppression effect can be expressed without causing an increase.
In addition, since the total width of the narrowed neck when viewed from the tread tread surface is 3 to 20% of the width of the air chamber, the resonator can be brought closer to an ideal Helmholtz resonator model. This can increase the air column resonance suppression effect of the circumferential groove.

  <2> According to <2>, since one or more resonators having a resonance frequency in the range of 700 to 1800 Hz are disposed in each pitch length on the tread surface having a tread pattern to which pitch variation is given, the resonator is When fully entering the ground surface, the driver can effectively deal with circumferential air column resonance in the 1/3 octave band, which is often recognized as an unpleasant noise in the 1/3 octave band, Moreover, it can be made to contribute advantageously to the reduction of the discomfort with respect to the high frequency noise of 1000-2000Hz called high frequency noise.

According to <3>, of the air chamber, since the opening area of the land portion surface is in the range of 50～600Mm ^2, it is possible to suppress the noise from the tire effectively, and the opening area less than 50 mm ² In this case, in order to secure a volume corresponding to the resonance frequency region in the air chamber, the air chamber depth must be deepened, and the shape of the air chamber becomes long, and in addition to this, a further elongated neck portion requires a, there is a possibility that closed grooves Therefore becomes hard to act as a resonator, whereas, this in case of a material of more than 600 mm ^2, the length of the opening edge is long There is a concern that road surface impact noise will become apparent and early uneven wear will occur.

< 4 > According to < 4 >, since the depth dimension of the stenosis neck is set to 70% or less of the maximum depth of the air chamber, the air column resonance suppression effect can be enhanced. Since it is away from the shape of the Helmholtz resonator, the resonance suppression effect is reduced.

< 5 > According to < 5 >, the maximum depth from the land surface is 20 to 90% of the maximum depth of the groove that divides the land on the tread surface. A sufficient air chamber volume can be secured, and the air chamber can effectively function as a resonance chamber.

According to < 6 >, since the irregularities with a height of 1.6 mm or more are provided on the bottom wall of the air chamber, it is possible to advantageously prevent stone biting into the air chamber.

According to < 7 >, the narrowed neck of the resonator is formed by a sipe that opens on the surface of the land portion. Therefore, the portion of the narrowed neck is easily molded by attaching the sipe forming blade to the mold. Therefore, productivity in manufacturing a tire having such a narrowed neck can be increased.

According to < 8 >, since the opening shape of the air chamber to the surface of the land portion is a curved contour shape such as a circle or an ellipse, there is no straight portion extending in one direction on the edge of the opening. There is an advantage that the generation of noise can be advantageously suppressed and the occurrence of uneven wear on the opening edge portion can be suppressed.

According to < 9 >, since the opening shape of the air chamber to the land surface is a quadrilateral shape, the air chamber design can be performed accurately and easily due to the simple shape, and the linear edge component By designing the opening shape so as not to be parallel to the ground line, the pattern design with reduced pitch noise can be simplified.

< 10 > According to < 10 >, the tire mounted on the applicable rim is filled with the prescribed air pressure, and a load corresponding to 80% of the prescribed mass is applied to the tire. Therefore, regardless of the rotational position of the tire, at least one of the resonators can function, and air column resonance can be more advantageously suppressed.

According to < 11 >, the tire mounted on the applicable rim is filled with a specified air pressure, and a load corresponding to 80% of the specified mass is applied to the tire. Since a plurality of different resonators are always included completely, the resonance suppression effect can be applied to a wide frequency range.

  FIG. 1 is a diagram schematically showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a tread tread, in particular, a tire mounted on an applicable rim is filled with a prescribed air pressure, and the tire has a prescribed air pressure. A grounding surface 2 that contacts the road surface in a state where a load corresponding to 80% of the mass is applied is shown. 3 extends continuously on the grounding surface 2 in the circumferential direction, for example, in a straight line. A circumferential groove having an annular shape is shown.

  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 determined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States, it is "THE TIRE AND RIM ASSOCIATION INC. YEAR BOOK", and in Europe, the THE It is “STANDARDS MANUAL” of European Tire and Rim Technical Organization, and “JATMA YEAR BOOK” of Japan Automobile Tire Association in Japan.

  The land portion 4 sandwiched between two adjacent circumferential grooves 3A and 3B includes an air chamber 6 that opens on the surface of the land portion 4 at a position away from the circumferential grooves 3A and 3B, and the air chamber 6 that includes these air chambers 6. Resonators 5 each having constricted necks 7A and 7B communicating with the circumferential grooves 3A and 3B are disposed. As described above, the present invention is characterized in that it includes at least two constricted necks 7A and 7B communicating from the air chamber 6 to both the different circumferential grooves 3A and 3B, respectively. The chamber 6 can exert an effect of suppressing air column resonance with respect to the two circumferential grooves 3A and 3B. In particular, when the circumferential grooves 3A and 3B have the same resonance frequency, the circumferential grooves 3A and 3B have the same resonance frequency. On the other hand, almost the same air column resonance suppression effect as when the optimum resonator is individually attached can be exhibited.

In general, in the case of a Helmholtz type resonator in which one narrowed neck 7 is provided for one air chamber 6 as schematically shown in FIG. Under the condition that both the opening and the stenosis neck 7 are sealed by the road surface, the resonance frequency f ₀ is r, the length of the stenosis neck 7 is l ₀ , the neck cross-sectional area is S, and the air volume is V When the sound speed is c, it can be expressed by equation (1).

In addition, the resonance frequency f ₀ in the case of a Helmholtz type resonator 5 in which two narrowed necks 7A and 7B are provided for one air chamber 6 as schematically shown in FIG. Similarly, the stenosis necks 7A and 7B have radii r ₁ and r ₂ , lengths l ₀₁ and l _02, neck cross sections S ₁ and S ₂ , air chamber volume V and sound velocity c Then, it can be expressed by the formula (2).

Accordingly, the resonance frequency (f ₀ ) of the resonator 5 can be changed as required by selecting the neck cross-sectional areas (S ₁ , S ₂ ), the air chamber volume (V), etc. For the purpose of suppressing air column resonance in a general frequency band generated from the peripheral groove of the resonator 5, it is preferable that f ₀ be 700 to 1800 Hz as a resonance frequency to be included in the resonator 5. This is more preferably 700 to 1400 Hz, and the dimensions of the resonator should be set to obtain frequencies in these ranges.

In the equations (1) and (2), the coefficient 1.3 relating to r, r ₁ , and r ₂ varies depending on the literature and is generally obtained from an empirical equation. In this specification, The coefficient was 1.3.

  Further, as shown in the example of the case where there are two stenosis necks in the formula (2), when there are a plurality of stenosis necks, the cross-sectional area of the plurality of stenosis necks is the sum of the cross-sectional areas. It has been found that there is no practical problem by performing the calculation assuming that it is equivalent to one stenosis neck whose length is the average length of the neck.

Here, the opening area of the air chamber 6 to the land surface under a no-load state on the tire is set to 50 to 600 mm ² , more preferably 100 to 360 mm ² .

  By the way, in this tire, since the air chamber 6 of the resonator 5 is formed by opening the surface of the land portion 4, the vulcanization molding for the raw tire is performed so that the mold portion enters the portion corresponding to the air chamber. Even if it is carried out, the extraction of the mold part from the air chamber 6 of the product tire is always smooth and reliable regardless of whether the cross-sectional area of the air chamber 6 changes somewhat in the depth direction. As a result, the tire can be manufactured in the same manner as a conventional tire without a resonator.

  Note that such an air chamber 6 that opens on the surface of the land portion 4 also defines a sealed space in the ground contact surface 2 of the tread tread 1 under the closed condition of the opening by the road surface. In addition, the function as a resonance chamber can be sufficiently exhibited.

  In addition, the cross-sectional area and the contour shape of the air chamber 6 in the cross section parallel to the land surface can be made the same as those of the land opening toward the bottom wall side of the air chamber 6. It can be gradually increased from the air chamber 6 of the molded tire to the extent that the extraction of the mold portion is not restricted, and conversely, it can be gradually decreased.

  In addition, the opening shape to the land part surface of the air chamber 6 can also be made into an elliptical shape and other curved outline shapes, and can also be made into a square or other polygonal shapes.

  In such a resonator 5, the constriction neck 7 has a tunnel shape embedded in the land portion 4, here the block 4 a, as illustrated in the perspective view of the main part in FIG. In addition, as shown in FIG. 3B, the surface of the block 4a can be opened. Here, when the open necks 7A and 7B, such as the latter, are formed by, for example, pressing a blade of a vulcanization mold or the like, the narrow necks 7A and 7B are also easily formed in addition to the air chamber 6. can do.

  In this case, the narrowed neck 7 can also be formed by sipe. At this time, as illustrated in FIG. 3C, the shape of the sipe is a so-called flask-like shape having an enlarged space portion at the bottom. For example, portions other than the enlarged space portion have sipe walls in the ground plane. By making the narrow portion so as to be in contact with each other, the various dimensions of the constriction necks 7A and 7B can be always constant as in the case shown in FIG.

  More preferably, in such a resonator 5, the maximum depth h of the air chamber 6 from the surface of the land, in the drawing, from the block surface, the groove that defines the land 4 in the tread tread 1, and the block 4a in the drawing, for example, 20% or more of the maximum depth H of the circumferential groove 3, particularly 40 to 80%. Preferably, the maximum dimension d in the depth direction of the constriction neck 7 is 70% or less of the maximum depth h of the air chamber 6. Especially 50% or less.

  Also, the cross-sectional areas and lengths of a plurality of constriction necks (two constriction necks 7A and 7B in the case of the above embodiment) communicating with one air chamber 6 should be the same or different from each other. You can also.

  In the above description, the bottom wall of the air chamber 6 can be a flat surface, or a curved surface that is convex or concave toward the opening side thereof. As shown in an enlarged cross-sectional view along the line Y-Y in FIG. 3A, the bottom wall is convex upward for the purpose of suppressing stone biting into the air chamber 6. One or more protrusions 6a are provided, and the resulting unevenness difference δ is 1.6 mm or more, more preferably 3.0 mm or more. However, the upper limit of the unevenness difference δ is smaller than the maximum depth of the air chamber, more preferably smaller than (maximum depth of the air chamber−2 mm) because the air chamber 6 needs to be resonated without being divided. Good.

  In this case, the protrusion 6a may be formed so as to protrude from the side wall of the air chamber and be independent from the bottom wall, in other words, separated from the bottom wall.

  The arrangement of the resonator 5 having such a configuration with respect to the circumferential groove 3 is such that at least one circumferential groove is formed in the ground plane 2 under the conditions described with reference to FIG. It is preferable that one or more of the resonators 5 provided in any one of the circumferential grooves 3 is always completely included, and more preferably, each of the plurality of circumferential grooves 3 as illustrated in FIG. One or more resonators 5 are always completely included in the ground plane 2.

  More preferably, a plurality of resonators 5a having different resonance frequencies are disposed in the ground plane 2 that is grounded under the same conditions as described above, as illustrated in FIG. , 5b, 5c are always included.

  In FIG. 6, for each of all the circumferential grooves 3 extending in the ground plane 2, a plurality of resonators are included in the ground plane 2. Of these, only a plurality of resonators provided in at least one circumferential groove 3 may be included in the ground plane 2.

  FIGS. 7 and 8 are conceptual diagrams showing the ground contact surface of the tread surface in the same state as that described with reference to FIG. 1 for the tire of the modified example of the embodiment of the present invention, and the resonator 15A shown in FIG. As described above, the opening of the air chamber 16 has a rectangular shape, and the constriction necks 17A and 27A are connected to both end surfaces in the tire circumferential direction of the air chamber 16, and these can be guided to different circumferential grooves 3. Like the resonator 15B, the opening of the air chamber 26 is formed into an elliptical shape inclined in the tire circumferential direction, and the narrowed necks 17B and 27B are directed from the air chamber 26 in the tire circumferential direction and then changed in the tire width direction. It can also be configured to communicate with the circumferential groove 3.

  Further, as in the resonator 15C shown in FIG. 8, the constricted necks 17C and 27C are linearly inclined from the corner of the air chamber 16 having a rectangular opening and extend in opposite directions to each other in the tire circumferential direction. As shown in the resonator 15D, one narrowed neck 17D extends in the tire width direction and the other narrowed neck 27D extends in the tire circumferential direction from the elliptical air chamber 26, and then the tire width. It can also be changed in direction and extended.

The tire of the Example which concerns on embodiment of this invention was made as an experiment, and Experiment 1-10 shown below was conducted.

[Experiment 1]
A tire with a size of 195 / 65R15 having a resonator 15C having the shape and arrangement shown in FIG. 9 was mounted on a 6JJ rim as Example 1 and the air pressure was 210 kPa. , And rolling at a speed of 80 km / h under the action of a load of 4.47 kN, and measuring the side sound of the tire at this time according to the conditions specified in JASO C606, with a center frequency of 800− in 1/3 octave band The overall value of 1000Hz-1250Hz band was obtained.

Here, the air chamber 16 and the constricted necks 17C and 27C constituting the resonator 15C are opened in the tread surface as shown in FIG. 9, and the air chamber 16 has a tire circumferential direction length a of 36 mm and a tire width direction. It has a rectangular parallelepiped shape with a width w of 6 mm and a depth h of 4 mm. Therefore, its volume V is 864 mm ³ , and the constriction necks 17C and 27C have a width t of 0.5 in the cross section perpendicular to the extending direction. A rectangular shape (cross-sectional area S = 1 mm ² ) with mm and depth d of 2 mm was formed, and its extended length l ₀ was 6 mm. The resonance frequency f ₀ in the Helmholtz resonator obtained by using the equation (3) for these dimensions is 1014 Hz. In the calculation, the sound velocity c was 343.7 m / s.

Here, as shown in FIG. 2 (b), the above equation (3) is the cross-sectional area of the stenosis necks 7A and 7B in the resonator 5 in which the two stenosis necks 7A and 7B are communicated with the air chamber 6. S ₁ and S ₂ are both S, the cross-sectional radii are r ₁ and r ₂ are both r, and the extended lengths l ₀₁ and l ₀₂ are both l ₀ . This is effective for obtaining the resonance frequency f _{0 in the} case of having a constriction neck.

Further, the tire of Example 1 has a pitch variation, and the circumferential pitch of the resonator 15C varies depending on the pitch size, but the average circumferential pitch p of the resonator 15C over the entire circumference is 54 mm, the tire mounted on the rim under the above conditions, at the ground portion when allowed to act corresponding load to 80% of the prescribed mass, circumferential groove ground average length L _t is 140 mm.

  Further, each of the cross sections of the circumferential groove 3 had a depth of 8 mm and a width of 8 mm.

  Further, in addition to the evaluation of the tire of the above example, a tire different from that of the example only in that it has no resonator on the tread surface with respect to that of Example 1 is referred to as Conventional Example 1, and the tread Only the point of the resonator 15C arranged on the surface without one of the constricted necks 17C and the point that the width of the constricted neck 27C is doubled so that the resonance frequency does not change by eliminating the constricted neck 17C. A tire different from the example (see FIG. 10) was defined as Conventional Example 2, and these were also evaluated and compared in the same manner as in Example 1. The result was expressed as an absolute value of the difference in the overall value of the band with respect to Conventional Example 1 as an improvement effect. The larger the value, the greater the improvement effect.

  As is clear from Table 1, the tire of Example 1 shows that the resonance noise suppression effect is superior to that of Conventional Example 1 as well as that of Conventional Example 2, which means that The tire according to the present invention can extend the circumferential pitch of the resonator relative to a conventional tire having a resonator having the same air chamber size but having only one circumferential groove. This means that an equivalent resonance suppression effect can be exhibited.

[Experiment 2]
In order to investigate the relationship between the resonance frequency and the improvement effect of resonance noise suppression, the tires of Example 2-1 to Example 2-12 differing from Example 1 only in the dimensions of the air chamber 16 or the constriction necks 17C and 27C. The prototype is measured under the same conditions as in Experiment 1, and the overall value of the 1/3 octave band in the band of the center frequency 800-1000Hz-1250Hz is determined. The improvement effect in suppression [dB] was taken (the larger this value, the greater the improvement effect).

Table 2 shows the dimensions [mm] of the air chamber 16 or the constricted necks 17C and 27C, the resonance frequency f ₀ [Hz] obtained using the equation (3), and the improvement effect [dB] in the tires of the examples. The relationship between the resonance frequency and the improvement effect is shown as a graph in FIG. As a preferable range of the improvement effect, the suppression effect [dB] is set to a range of 2 or more in consideration of detection power of a general human sound pressure difference.

  As apparent from Table 2 and FIG. 11, the effect is large when the resonance frequency is 700 to 1800 Hz, and particularly when 700 to 1400 Hz, an even greater improvement effect can be obtained, which is preferable.

[Experiment 3]
In order to investigate the relationship between the opening area of the air chamber to the surface of the land and the improvement effect of resonance noise suppression, Example 3-1 differs from Example 1 only in the dimensions of the air chamber 16 or the constriction necks 17C and 27C. The tire of Example 3-10 was prototyped and measured under the same conditions as in Experiment 1 to obtain an overall value of 1/3 octave band in the band of the center frequency 800-1000 Hz-1250 Hz. The difference from Conventional Example 1 was defined as an improvement effect [dB] in suppressing resonance noise (the larger this value, the greater the improvement effect).

Table 3 shows the dimensions [mm] of the air chamber 16 or the constricted necks 17C and 27C, the resonance frequency f ₀ [Hz] obtained using the equation (3), and the improvement effect [dB] in the tires of the examples. The relationship between the opening area and the improvement effect is shown as a graph in FIG. A preferable range of the suppression effect is a range where the suppression effect [dB] is 2 or more in consideration of detection power of a general human sound pressure difference.

As is apparent from Table 3 and FIG. 12, the opening area of the air chamber to the land surface can be set to a preferable range of 50 to 600 mm ² .

[Experiment 4]
In order to investigate the relationship between the ratio of the width of the stenosis neck to the width of the air chamber and the effect of improving the resonance suppression, Example 4 differs from Example 1 only in the dimensions of the air chamber 16 or the stenosis necks 17C and 27C. 1 to Example 4-3 and Comparative Examples 4-1 and 4-2 were made on a trial basis, measured under the same conditions as in Experiment 1, and the 1/3 octave band in the band of the center frequency 800-1000Hz-1250Hz. The overall value was obtained, and the difference between the overall value and the conventional example 1 was defined as the improvement effect [dB] in suppressing the resonance noise (the larger this value, the greater the improvement effect).

Table 4 shows the dimensions [mm] of the air chamber 16 or the narrowed necks 17C and 27C, the resonance frequency f ₀ [Hz] obtained by using the equation (3), and the improvement effect [dB] in the tires of the examples and comparative examples. Shown in Further, the relationship between the ratio of the narrowed neck width to the air chamber width and the improvement effect is shown as a graph in FIG. In addition, as an indispensable range of the suppression effect, the suppression effect [dB] is set to a range of 3 or more in consideration of a general human sound pressure difference detection power.

As is apparent from Table 4 and FIG. 13, the ratio of the width of the stenosis neck to the air chamber can be in the essential range of 3 to 20 % in terms of the improvement effect in suppressing resonance noise.

[Experiment 5]
In order to investigate the relationship between the ratio of the maximum dimension in the depth direction of the stenosis neck to the maximum depth of the air chamber and the improvement effect of resonance sound suppression, the first embodiment is only the dimension of the air chamber 16 or the stenosis necks 17C and 27C. The tires of Example 5-1 to Example 5-5 with different values were made on a trial basis, measured under the same conditions as in Experiment 1, and the overall value of the 1/3 octave band in the band of the center frequency 800-1000Hz-1250Hz was obtained. The difference between the overall value and the conventional example 1 was determined as the improvement effect [dB] in suppressing the resonance noise (the larger this value, the greater the improvement effect).

Table 5 shows the dimensions [mm] of the air chamber 16 or the constricted necks 17C and 27C, the resonance frequency f ₀ [Hz] obtained using the equation (3), and the improvement effect [dB] in the tires of the examples. Further, the relationship between the ratio of the maximum dimension in the depth direction of the stenosis neck to the maximum depth of the air chamber and the improvement effect is shown as a graph in FIG. A preferable range of the suppression effect is a range where the suppression effect [dB] is 2 or more in consideration of detection power of a general human sound pressure difference.

  As is clear from Table 5 and FIG. 14, the ratio of the maximum dimension of the stenosis neck in the depth direction to the maximum depth of the air chamber is preferably set to 70% or less in terms of an improvement effect in resonance noise suppression. it can.

[Experiment 6]
In order to investigate the relationship between the ratio of the maximum depth of the air chamber to the maximum depth of the circumferential groove and the effect of improving the resonance noise suppression, only the dimensions of the air chamber 16 or the constriction necks 17C and 27C are used in Example 1. Trial tires of different Example 6-1 to Example 6-5 were prototyped and measured under the same conditions as in Experiment 1 to obtain an overall value of 1/3 octave band in the band of center frequency 800-1000Hz-1250Hz. The difference between the overall value and the conventional example 1 was defined as the improvement effect [dB] in suppressing the resonance noise (the larger this value, the greater the improvement effect).

Table 6 shows the dimensions [mm] of the air chamber 16 or the constricted necks 17C and 27C, the resonance frequency f ₀ [Hz] obtained using the equation (3), and the improvement effect [dB] in the tires of the examples. Moreover, the relationship between the ratio of the maximum depth of the air chamber to the maximum depth of the circumferential groove and the improvement effect is shown as a graph in FIG. A preferable range of the suppression effect is a range where the suppression effect [dB] is 2 or more in consideration of detection power of a general human sound pressure difference.

As is clear from Table 6 and FIG. 15, the ratio of the maximum depth of the air chamber to the maximum depth of the circumferential groove is preferably 20 to 90% in terms of the improvement effect in resonance noise suppression. it can.
20-90%

[Experiment 7]
In order to investigate the presence or absence of a stone bite and the improvement effect in resonance noise suppression when a protrusion is provided on the bottom wall of the air chamber, in addition to the tire of Example 1 having no protrusion, protrusions having different heights are provided on the bottom wall. The tires of Examples 7-1 to 7-3, which differ from Example 1 only in the points provided, were prototyped, measured under the same conditions as in Experiment 1, and 1/3 octave in the band of center frequency 800-1000Hz-1250Hz. The overall value of the band was obtained, and the difference between the overall value and the conventional example 1 was defined as the improvement effect [dB] in suppressing the resonance (the larger the value, the greater the improvement effect).

  Table 7 shows the presence or absence of stone biting and the improvement effect [dB] in the tire of each example. Moreover, the relationship between the ratio of the maximum depth of the air chamber to the maximum depth of the circumferential groove and the improvement effect is shown as a graph in FIG. A preferable range of the suppression effect is a range where the suppression effect [dB] is 2 or more in consideration of detection power of a general human sound pressure difference.

  Also, the presence or absence of stone biting was judged visually by running on a gravel road on a test course and running 5 km. The protrusions were arranged at a pitch of 2 mm in the length direction of the air chambers also in Examples 7-1 to 7-3.

  As is clear from Table 7 and FIG. 16, it is preferable to set the height of the protrusions to 1.6 mm or more in order to prevent stone biting, and even if this is somewhat large, the effect of suppressing the resonance is not significantly inhibited.

[Experiment 8]
In order to investigate the opening shape in the land portion of the air chamber 16 and the improvement effect in suppressing the resonance noise, the tire of the first embodiment has the same opening area of the air chamber 16 as the tire, and the opening shape is a circle instead of a quadrilateral. The tire of Example 8, which is different from Example 1 only, was measured and measured under the same conditions as in Experiment 1, and the overall value of 1/3 octave band in the band of center frequency 800-1000Hz-1250Hz was obtained. The difference between the overall value and the conventional example 1 was determined as the improvement effect [dB] in suppressing the resonance noise (the larger this value, the greater the improvement effect).

  The results are shown in Table 8. A preferable range of the suppression effect is a range where the suppression effect [dB] is 2 or more in consideration of detection power of a general human sound pressure difference.

[Experiment 9]
In order to investigate the number of resonators in the ground plane and the improvement effect in suppressing the resonance noise, the shape of the resonator is the same as that of the tire of Example 1, but the number of resonators on the circumference is the same as Example 1. The tires of Examples 9-1 and 9-2, which differ from Example 1 only in terms of the half of this, were prototyped and measured under the same conditions as in Experiment 1. 1 / in the band of the center frequency 800-1000Hz-1250Hz The overall value of the 3 octave band was obtained, and the difference between the overall value and the conventional example 1 was defined as the improvement effect [dB] in suppressing the resonance (the larger the value, the greater the improvement effect).

  Here, Example 9-1 and 9-2 differ in the arrangement of the resonator in the tire circumferential direction, and Example 9-1 is on the tire half circumference (the circumferential pitch of the resonator in the half circumference is the same as in Example 1). In Example 9-2, the resonators were arranged uniformly over the entire circumference (the pitch in the circumferential direction of the resonators was 108 mm, which is twice that of Example 1). Note that the length in the circumferential direction of the contact surface is 140 mm as in the first embodiment.

  The results are shown in Table 9. As a preferable range of the improvement effect, the suppression effect [dB] is set to a range of 2 or more in consideration of detection power of a general human sound pressure difference.

  As can be seen from Table 9, it is preferred to arrange this so that there is always a resonator on the ground plane.

[Experiment 10]
In order to examine the number of types of resonators and the improvement effect in suppressing resonance noise, the three types of resonators 1 to 3 having the air chambers with the dimensions shown in Table 11 are the same as the tires of Example 1. A tire of Example 10 which is different from the tire of Example 1 only in that the tires are arranged in the circumferential direction in order so as not to be adjacent to each other is experimentally manufactured and measured under the same conditions as in Experiment 1. The center frequency is 800-1000 Hz-1250 Hz. The overall value of the 1/3 octave band in the band is determined, and the difference between the overall value and the conventional example 1 is defined as the improvement effect [dB] in suppressing the resonance (the larger the value, the greater the improvement effect) .

  The results are shown in Table 10. As a preferable range of the improvement effect, the suppression effect [dB] is set to a range of 2 or more in consideration of detection power of a general human sound pressure difference.

  As is clear from Tables 10 and 11, a more excellent resonance suppression effect can be obtained by mixing a plurality of resonators having different resonance frequencies.

It is a figure showing typically an embodiment of this invention. It is a figure which shows typically a Helmholtz type resonator. It is a principal part perspective view which illustrates the formation aspect of a resonator. It is an expanded sectional view of the air chamber bottom wall which follows the YY line of Fig.3 (a). It is a figure which shows the example of suitable arrangement | positioning of the resonator in a ground plane. It is a figure which shows the further suitable example of arrangement | positioning of a resonator about a ground plane. It is a schematic diagram which shows the modification of embodiment. It is a schematic diagram which shows another modification. It is a top view which shows the contact surface of the tire of an Example. FIG. 6 is a plan view showing a contact surface of a tire of Conventional Example 2. It is a graph which shows the relationship between a resonant frequency and an improvement effect. It is a graph which shows the relationship between an opening area and an improvement effect. It is a graph which shows the ratio of the width | variety of a constriction neck with respect to the width | variety of an air chamber, and the improvement effect. It is a graph which shows the relationship between ratio of the depth direction maximum dimension of the constriction neck with respect to the maximum depth of an air chamber, and the improvement effect. The relationship between the ratio of the maximum depth of the air chamber to the maximum depth of the circumferential groove and the improvement effect It is a graph which shows the relationship between the height of the processus | protrusion of the bottom groove | channel of an air chamber, and the improvement effect.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread tread surface 2 Ground surface 3, 3A, 3B Circumferential groove 4 Land part 4a Block 5, 5a, 5b, 5c Resonator 6 Air chamber 6a Protrusion part 7, 7A, 7B Constriction neck 15A, 15B, 15C, 15D Resonator 16 Air chamber 17A, 17B, 17C, 17D Stenosis neck 26 Air chamber 27A, 27B, 27C, 27D Stenosis neck

Claims (11)

The tread surface is provided with a circumferential groove extending continuously in the circumferential direction, and an air chamber that opens to the land surface at a position away from the circumferential groove and a constriction neck that communicates the air chamber with the circumferential groove. In the tire with the container,
At least one disposed between the circumferential grooves adjacent to each other the resonator has the narrowed neck 2 or more, at least two of these narrowed neck is Ri greens open to different circumferential grooves ,
A pneumatic tire in which the total width of the narrowed neck when viewed from the outside of the tread surface is 3 to 20% of the width of the air chamber .   The pneumatic tread according to claim 1, wherein at least one resonator having a resonance frequency in a range of 700 to 1800 Hz is disposed within at least one pitch length in a tread surface having a tread pattern to which pitch variation is given. tire. Wherein the air chamber, the pneumatic tire according to claim 1 or 2 comprising an opening area of the land portion surface as a range of 50～600Mm ^2. The pneumatic tire according to any one of claims 1 to 3 , wherein a depth dimension of the narrowed neck is 70% or less of a maximum depth of the air chamber. The pneumatic tire according to any one of claims 1 to 4 , wherein the maximum depth of the air chamber from the land surface is 20 to 90% of the maximum depth of the groove that divides the land portion on the tread surface. The pneumatic tire according to any one of claims 1 to 5 , wherein the bottom wall of the air chamber is provided with irregularities having a height of 1.6 mm or more. The pneumatic tire according to any one of claims 1 to 6 forming a narrowed neck of the resonator by sipes. The pneumatic tire according to any one of claims 1 to 7 , wherein an opening shape of the air chamber to the land surface is a curved contour shape. The pneumatic tire according to any one of claims 1 to 7 , wherein an opening shape of the air chamber to the land surface is a quadrilateral shape. The tire mounted on the applicable rim is filled with the specified air pressure and a load corresponding to 80% of the specified mass is applied to the tire. The pneumatic tire according to any one of claims 1 to 9 , wherein the pneumatic tire is configured as described above. A tire mounted on the applicable rim is filled with the specified air pressure, and a load corresponding to 80% of the specified mass is applied to the tire. The pneumatic tire according to any one of claims 1 to 10 , wherein the pneumatic tire is always included completely.

Images