JP2005119480A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve drainage performance, even when wear develops. <P>SOLUTION: A closed groove 1 of a substantially circular shape in cross section which is opened on a tire grounding tread side is formed, for instance, in a tread surface of a pneumatic tire, preferably, in a block part B on a tire shoulder side having high rigidity or large grounding area in the pneumatic tire. In the closed groove 1, a widened groove part (truncated cone part) 1b having the inside widened more than an opening part on the tire grounding tread side is provided. More preferably, at least a sipe (or a narrow groove) 2 communicated with the closed groove 1 may be provided in the block part B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can suppress a decrease in drainage performance when the ground contact surface of the tire is worn.

  In general, a pneumatic tire is required to ensure not only wear resistance and traction performance on a dry road, but also performance on a wet road surface (so-called wet performance). Here, drainage performance can be cited as a part of this wet performance. If the drainage performance is not satisfied, the wet road surface causes the tire to rise due to a water film on the stepping side of the tire contact surface (so-called hydrodynamic performance). A planing phenomenon) may occur. Therefore, conventionally, in a pneumatic tire, drainage performance is secured by forming tread patterns of various shapes on the tire ground contact surface, and the hydroplaning phenomenon is prevented. Such a drainage function is mainly handled by a circumferential groove, and a lug groove, a sipe, etc. are also provided for improving lateral drainage.

  Here, block rigidity must be secured in order to prevent wear resistance and deterioration of traction performance on dry roads, and for this reason, lug grooves and sipes could not be provided at the base of the block. . For this reason, when the wear on the tire ground contact surface progresses, there is a disadvantage that the groove volume is reduced and the drainage performance is gradually lowered as compared with a new article. Therefore, as a technique for ensuring the drainage performance during the progress of wear, for example, there is a pneumatic tire disclosed in JP-A-6-191236. This pneumatic tire is made by mixing a plurality of dispersed particles in a rubber composition forming a tread. When the worn tire is worn, the dispersed particles are separated and dropped to expose a hole-like closed groove on the tire ground contact surface. To prevent a decrease in drainage performance.

JP-A-6-191236

  However, in the conventional pneumatic tire described above, a large number of dispersed particles are included inside, and the innumerable closing grooves are randomly exposed on the entire tire contact surface. As a result, the steering stability performance (hereinafter referred to as “steerability”) is deteriorated. Moreover, in order to ensure suitable drainage performance in this pneumatic tire, dispersed particles must be mixed uniformly, and from the viewpoint of productivity, an increase in cost cannot be denied. Furthermore, in order to improve drainage at the end of wear, this pneumatic tire has a two-layer structure in which the inner layer contains particles having a particle size larger than the dispersed particles on the tire surface side. Worsened and more costly.

  Accordingly, the object of the present invention is to provide a pneumatic tire that can improve the disadvantages of the conventional example and can ensure drainage performance at the time of progress of wear without causing adverse effects such as a decrease in safety. To do. A further object is to provide a pneumatic tire that can ensure such drainage performance at low cost.

  In order to achieve the above object, in the first aspect of the present invention, the tread surface is provided with a closing groove having an inwardly widened groove portion wider than the opening on the tire ground contact surface side.

  In order to achieve the above object, according to a second aspect of the present invention, in the pneumatic tire according to the first aspect, a columnar groove portion communicating with the widening groove portion is provided on the opening portion side of the closing groove.

  In order to achieve the above object, in the invention according to claim 3, in the pneumatic tire according to claim 2, when the groove depth of the closing groove is D1, and the groove depth of the columnar groove portion is D2, The depth D2 of the columnar groove is set in the range of D2 = 0 to 0.5D1.

  In order to achieve the above object, in the invention according to claim 4, in the pneumatic tire according to claim 1, 2 or 3, at least one sipe or narrow groove communicating with the closing groove is provided. .

  In order to achieve the above object, in the invention according to claim 5, in the pneumatic tire according to claim 4, the groove width W3 of the sipe or the narrow groove is set to 0.5 to 1.5 mm, and When the groove depth is D1, the groove depth D3 of the sipe or the narrow groove is in the range of D3 = 1 / 3D1 to D1.

  In order to achieve the above object, according to the invention described in claim 6, the closed groove having the widened groove portion that is wider than the opening portion on the tire ground contact surface side is provided on the tread surface, and the closed groove is provided. Surrounding continuous or discontinuous sipes or narrow grooves are provided.

  In order to achieve the above object, in the invention according to claim 7, the closed groove having the columnar groove portion on the tire ground contact surface side and having the widened groove portion that is wider than the columnar groove portion is provided on the tread surface. A continuous or discontinuous sipe or narrow groove surrounding the closed groove is provided.

  In order to achieve the above object, in the invention according to claim 8, in the pneumatic tire according to claim 7, the groove depth of the closing groove is D1, and the groove depth of the columnar groove portion is D2. The groove depth D2 of the columnar groove portion is set within the range of D2 = 0.3 to 0.5D1, the groove width W4 of the sipe or narrow groove is set to 1.0 to 2.0 mm, and the groove of the sipe or narrow groove is formed. The depth D4 is set in the range of D4 = 0.3D1 to D2.

  In order to achieve the above object, in the invention according to claim 9, in the pneumatic tire according to any one of claims 1 to 8, the groove width on the tire contact surface side in the widened groove portion is set to W1, When the groove width of the maximum widened portion in the widened groove portion is W2, the groove widths W1 and W2 are in the range of W2 / W1 = 1.2 to 2,0, and the groove depth of the closed groove is D1, main. When the groove depth of the groove is D, the groove depth D1 of the closed groove is in the range of D1 = 0.3D to 1.0D.

  According to the pneumatic tire according to the present invention, the widened groove portion that is wider than the opening portion on the tire grounding tread surface side includes the closed groove provided inward, so that the maneuverability is not deteriorated. The drainage performance after progress of wear can be improved. In addition, since such a closed groove can be formed by providing a mold for molding a tread with a protrusion having the same shape as the closed groove, the drainage performance after the progress of wear can be improved at low cost.

  In the pneumatic tire according to the present invention, a portion that is wider than the opening on the tire ground contact surface side, that is, a portion having a cross-sectional area larger than the area of the opening (hereinafter also referred to as “widening groove portion”). This is realized by providing a closed groove formed on the tread surface in the block portion (or / and rib portion) of the tread surface. For example, the closing groove is constituted by a columnar groove portion in which the tire ground contact surface side is formed in a columnar shape, and a frustum groove portion (widened groove portion) formed by expanding from the columnar groove portion toward the groove bottom. As another example, a closed groove formed in the shape of a frustum is provided by widening from the tire ground contact surface side toward the groove bottom.

  By widening the groove bottom side from the tire ground contact surface side in this way, the groove surface area (in other words, the groove volume) of the closed groove in the middle or end of wear can be increased. It becomes possible to improve performance.

  However, as the cross-sectional area of the widening groove portion becomes larger than the opening area on the tire ground contact surface side, the detachability of the protruding portion of the mold for forming the closing groove is deteriorated. In view of this, in the pneumatic tire according to the present invention, when the mold removability deteriorates, a sipe (or narrow groove) that communicates with or surrounds the closed groove is provided. As a result, when the protruding portion pushes the closing groove in the mold drawing direction, the sipe (or narrow groove) serves as a relief of the peripheral portion of the closing groove, thereby improving the mold removability.

  As described above, the pneumatic tire according to the present invention is largely divided into those in which only the closed groove having the widened groove portion is provided in the tire and those in which the closed groove and sipes (or narrow grooves) are provided in the tire. Can be separated.

  Hereinafter, specific examples of the pneumatic tire according to the present invention will be described in detail with reference to the drawings.

  Example 1 of a pneumatic tire according to the present invention will be described with reference to FIGS.

  Reference numeral 1 in FIGS. 1-1 and 1-2 denotes a closing groove provided in the block portion B of the pneumatic tire of the first embodiment. The closed groove 1 has the above-described columnar groove portion on the tire ground contact surface side and a frustum groove portion that is wider than the columnar groove portion. Specifically, in the first embodiment, as shown in FIGS. 1-1 and 1-2, the columnar groove portion 1a having a substantially circular cross-sectional shape of the columnar groove portion and the cross-sectional shape of the frustum groove portion are substantially omitted. A so-called flask-shaped closed groove 1 constituted by a circular truncated cone part 1b is illustrated.

  Further, when there is a concern about deterioration of the mold detachability as described above, as shown in FIGS. 1-1 and 1-2, a cut is made in a cross centered on the closing groove 1 and communicating with the closing groove 1. Four sipes 2 (or narrow grooves 2) are provided in the block portion B. As a result, the flask-shaped protrusion (not shown) of the mold pushes the four divided pieces around the closed groove 1 divided by the sipe 2 (or the narrow groove 2) in the mold drawing direction. Since the sipe 2 (or the narrow groove 2) becomes the above-described relief, the mold removability is improved.

  The closing groove 1 and the sipe 2 (or narrow groove 2) as described above are shown in FIG. 2, for example, a block part B having a high block rigidity or a block part B having a large ground contact area to the road surface in order to suppress a decrease in the maneuverability. Thus, it is preferable to form the shoulder block.

  Here, the pneumatic tire according to the present invention is required to have drainage performance at the time of progress of wear, but the pneumatic tire is required to have not only this but also drainage performance at the time of a new article, and further, safety performance. Therefore, on the basis of the results of the wet performance test when new, the wet performance test when worn and the safety performance test conducted under the test conditions shown below, the closed groove 1 and sipe 2 of Example 1 (practically preferred) Alternatively, the narrow groove 2) is obtained.

  In each of the above tests, the tire shown in FIG. 2 having a tire size of 205 / 55R16 was manufactured as a test tire, and mounted on a wheel having a rim size of 16 × 6 JJ under the condition of an air pressure of 200 kPa. This tire was mounted on a 2000 cc class FF (front engine / front drive) vehicle.

  First, the wet performance test at the time of a new article or at the time of wear is a wet test course in which a feeling test is performed by a test driver, and the conventional pattern tire is evaluated with an index value of “100” as will be described later. did. Here, the larger the index value, the better the wet performance.

  In addition, the above-mentioned safety performance test was conducted by a test test by a test driver in a dry test course, and was evaluated by an index value with a conventional pattern tire being “100” as described later. Here, the larger the index value, the better the steering stability performance.

  First, the groove widths W1 and W2 shown in FIG. 3 of the columnar portion 1a and the truncated cone portion 1b constituting the closed groove 1 will be described. The groove width W2 of the truncated cone part 1b is the diameter of the groove bottom part (maximum widened part).

  Here, the test result of a pneumatic tire provided with a conventional closed groove (that is, a groove formed only of a cylinder) (not provided with the sipe 2 (or narrow groove 2) according to the present embodiment) is defined as an index “100”. The closed grooves 1 having various groove width ratios W2 / W1 were evaluated. In addition, about the closed groove | channel 1 (the following patterns A and B) of groove width ratio W2 / W1 = 1.2, evaluation by the presence or absence of a sipe (or narrow groove) was also performed. In this evaluation test, the test was performed with W1 = constant (= 3), D1 = constant (= 6), and D2 = constant (= 2). The test results are shown in Table 1 below.

  According to Table 1 above, it can be seen that in each of the patterns A to E, the wet performance when new and the wet performance when worn are equal to or higher than the closed groove of the conventional pattern. However, in the closed groove 1 of the pattern E (groove width ratio W2 / W1 = 2.5), the index of the steering performance is “96”, which is worse than the conventional pattern of closed grooves. . Therefore, in the first embodiment, the closed groove 1 in the range of the groove width ratio W2 / W1 = 1.2 to 2.0 is suitable for practical use.

  Next, the depth D1 of the closed groove 1 shown in FIG. 3 and the groove depth D2 of the narrow part (columnar part 1a) shown in FIG. 3 until reaching the truncated cone part (widened groove part) 1b will be described. . First, since the closing groove 1 is provided to improve drainage performance at the time of wear, the closing groove depth D1 is 30% or more of the depth D of the main groove formed in the circumferential direction of the tire. To do. Moreover, when D2 / D1 exceeds 50%, there is a concern about deterioration of the mold removability. Therefore, the groove depth D2 of the cylindrical portion 1a is preferably set to D2 / D1 = 0 to 0.5. Here, as described above, the detachability of the mold can be improved by the sipe 2 (or the narrow groove 2). For this reason, D2 / D1 can be made larger than 0.5 depending on the position, shape and size of the sipe 2 (or narrow groove 2).

  Next, the groove width W3 and the groove depth D3 shown in FIGS. 1-1 and 1-2 of the sipe 2 (or narrow groove 2) according to the first embodiment will be described. Here, in order to evaluate the groove width W3 and the groove depth D3, a new product wet performance test and a safety performance test were performed under the test conditions described above. Since the main function of the sipe 2 (or the narrow groove 2) is to improve drainage performance when it is new or when the wear is not progressing so much, the wet performance test during wear is omitted.

  In this evaluation, the test result of the closed groove of the conventional pattern used in the evaluation of the groove width W3 of the closed groove 1 described above is taken as an index “100”, and the groove width W3 of the sipe 2 (or narrow groove 2) is different or The following patterns A to F having different groove depths D3 were evaluated. In this evaluation test, the test was performed with W1 = constant (= 3), W2 = constant (= 4), D1 = constant (= 6), and D2 = constant (= 2).

  First, Table 2 below shows test results for evaluating the groove width W3 of the sipe 2 (or the narrow groove 2). In the evaluation test of the groove width W3, the test was performed with D3 = constant (= 2).

  According to Table 2 above, it can be seen that the wet performance when new is improved in each of the patterns A to F as compared with the closed groove of the conventional pattern. However, in the pattern F (groove width W3 is 2.0 mm), the index of the steering performance is “95”, which is worse than the conventional pattern. Therefore, the groove width W3 of the sipe 2 (or narrow groove 2) is preferably in the range of 0.3 to 1.5 mm. However, in the case of the above pattern A (groove width W3 is 0.3 mm), the index of the wet performance when new is “101”, and there is little improvement margin for the wet performance when new compared to the conventional pattern. For this reason, in the first embodiment, the sipe 2 (or narrow groove 2) having a groove width W3 in the range of 0.5 to 1.5 mm is suitable for practical use.

  Then, the test result for evaluating about the groove depth D3 of the sipe 2 (or narrow groove 2) is shown in Table 3 below. In the evaluation test of the groove depth D3, the test was performed with W3 = constant (= 0.5).

  According to Table 3 above, it can be seen that the wet performance when new is improved in each of the patterns A to F as compared with the closed groove of the conventional pattern. However, in the pattern F (groove depth D3 is 7.0 mm), the index of the steering performance is “96”, which is worse than the conventional pattern. That is, when the groove depth D3 of the sipe 2 (or the narrow groove 2) exceeds the closed groove depth D1, the operability is deteriorated. Therefore, the groove depth D3 of the sipe 2 (or narrow groove 2) is preferably in the range of 1.0 to 6.0 mm. However, in the case of the pattern A (groove depth D3 is 1.0 mm), the index of the wet performance when new is “101”, and there is little improvement margin for the wet performance when new compared to the conventional pattern. Therefore, in the first embodiment, the groove depth D3 is in the range of 2.0 to 6.0 mm, in other words, the sipe 2 (or narrow groove 2) having the groove depth D3 = 1 / 3D1 to D1. Is practically preferable.

  By providing the above-described closed groove 1 of the first embodiment in the block portion B of the pneumatic tire, it is possible to improve drainage performance when the wear progresses without deteriorating the operability, particularly on the stepping side of the tire contact surface. The drainage performance in can be improved. Moreover, since the closing groove 1 can be formed by providing a mold for molding the block portion B or the like with a protruding portion having the same shape as the closing groove 1, it only improves the drainage performance when the wear progresses. Therefore, it is not necessary to take a costly measure such as a two-layer structure. Furthermore, by providing the sipe 2 (or narrow groove 2), not only the mold can be removed but also the drainage performance at the time of a new article can be improved. The drainage performance can be improved.

  Next, Example 2 of the pneumatic tire according to the present invention will be described with reference to FIGS.

  In the second embodiment, as shown in FIGS. 4A and 4B, the closing groove 1 of the first embodiment described above and a substantially circular sipe 12 (or narrow groove 12) surrounding the closing groove 1 are used. And a pneumatic tire in which is formed.

  As described above, in the second embodiment, the sipe 12 (or the narrow groove 12) surrounds the closed groove 1. In such a case, when the groove depth D4 shown in FIG. 4-2 of the sipe 12 (or narrow groove 12) becomes deeper than the groove depth D2 of the cylindrical portion 1a, there is no escape of rubber around the closed groove 1 and the mold Detachability deteriorates. Therefore, the groove depth D2 of the cylindrical portion 1a is defined as D2 = 0.3D1 to 0.5D1, and the groove depth D4 of the sipe 12 (or narrow groove 12) is defined as D4 = 0.3D1 to D2. It is preferable. As a result, the rubber around the closing groove 1 is easily moved by the sipe 12 (or the narrow groove 12), so that the mold can be removed easily.

  Furthermore, the sipe 12 (or narrow groove 12) of the second embodiment has a width larger than the width of the maximum widened portion of the closing groove 1 as shown in FIG. A circular shape is preferred. However, the sipe 12 (or narrow groove 12) may be formed with a width equal to or less than the width of the maximum widened portion if the mold removability does not deteriorate.

  Here, as in the case of Example 1 described above, the test conditions shown in Example 1 were used to evaluate the groove width W4 shown in FIG. 4A of the sipe 12 (or narrow groove 12) of Example 2. The new product wet performance test and the safety performance test are performed, and the groove width W4 of the sipe 12 (or the narrow groove 12) of Example 2 which is practically preferable is obtained. Table 4 below shows the test results.

  According to Table 4 above, it can be seen that the wet performance when new is improved in each of the patterns A to F as compared with the closed groove of the conventional pattern. However, in the pattern F (groove width W4 is 2.5 mm), the index of the steering performance is “95”, which is worse than the conventional pattern. Therefore, the groove width W4 of the sipe 12 (or narrow groove 12) is preferably in the range of 0.5 to 2.0 mm. However, in the case of the pattern A (groove width W4 is 0.5 mm), the index of the wet performance when new is “101”, and there is little improvement margin for the wet performance when new compared to the conventional pattern. For this reason, in the second embodiment, the sipe 12 (or the narrow groove 12) having the groove width W4 in the range of 1.0 to 2.0 mm is suitable for practical use.

  In addition, about each width W1, W2 of the closing groove | channel 1 in this Example 2, what is in the range of groove width ratio W2 / W1 = 1.2-2.0 similarly to Example 1 mentioned above is practically used. It shall be suitable.

  By providing the closing groove 1 and the sipe 12 (or narrow groove 12) of the second embodiment shown above in the block portion B of the pneumatic tire, the same effect as the first embodiment described above can be obtained.

  Here, in the second embodiment, one continuous encircling sipe 12 (or encircling narrow groove 12) is formed, but the present invention is not necessarily limited thereto. For example, as shown in FIG. 5A, one portion of the surrounding sipe 12 (or the surrounding narrow groove 12) may be closed. That is, it is good also as the substantially C-shaped enclosure sipe 12A (or enclosure narrow groove 12A). Further, for example, as shown in FIG. 5B, a plurality of locations of the surrounding sipe 12 (or the surrounding narrow groove 12) may be closed. That is, the enclosure sipe 12B (or the enclosure narrow groove 12B) may be divided into a plurality. Even if the closed portion is provided as described above, the drainage performance at the time of a new article can be ensured as in the case of the continuous single sipe 12 (or the enclosed narrow groove 12). For example, a seamless blade must be prepared in order to form a single continuous sipe 12, but such a seamless blade is expensive to produce. However, by providing the closed portion as described above, for example, the sipe 12 can be formed by being surrounded by a plurality of blades, so that the productivity of the blade for forming the sipe is improved, thereby contributing to cost reduction.

  In addition, when providing the surrounding sipe (or surrounding narrow groove) surrounding the closed groove as in the second embodiment, as in the second embodiment, the enclosed sipe (or the same shape as the cross-sectional shape of the closed groove) (or It is preferable to form a surrounding narrow groove.

  As described above, in each of the first and second embodiments, the closed groove having the columnar groove portion and the frustum groove portion having a substantially circular cross section and the sipes (or narrow grooves) provided in the block portion B together with the closed groove are illustrated. These are not necessarily limited to the forms described above. For example, you may provide the closed groove | channel which has the columnar groove part and frustum groove part of a cross-sectional shape like Example 3-Example 5 mentioned later.

  Here, the practically preferred size of the closing groove and sipe (or narrow groove) in such a case is a cut sipe (or a cut narrow groove) as in the first embodiment, and W1 shown in the first embodiment. It is defined using values such as W2, D1, and D2. Further, in the case of an encircling sipe (or encircling narrow groove) as in the second embodiment, it is defined using the values of W1, W2, D1, D2, etc. shown in the second embodiment.

If the cross-sectional shape of the closing groove is a circle as in the first and second embodiments or a square shape, for example, the shape of the closing groove can be defined using the groove width ratio W2 / W1, but it will be described later, for example. In the case of such an oval shape, it is difficult to define the shape from the groove width ratio W2 / W1. Therefore, in such a case, it is preferable to define the shape from the cross-sectional areas of the groove widths W1 and W2. In this case, if the cross-sectional area of the groove width W1 portion is S1 and the cross-sectional area of the groove width W2 portion is S2, the cross-sectional area ratio S2 / S1 is S2 / S1 = (W2 / W1) ² . By substituting W2 / W1 = 1.2 to 2.0, a closed groove in the range of S2 / S1 = 1.44 to 4.0 is made practically suitable.

  Example 3 of the pneumatic tire according to the present invention is shown in FIGS. 6-1 and 6-2. This pneumatic tire is provided with a flask-like closed groove 21 having an elliptical cross section and an enclosed sipe 22 (or enclosed narrow groove 22) having an elliptical shape.

  Here, when such cross-sectional widths are different, it is preferable that the cross-sectional width be arranged in the block portion B so that the longitudinal direction thereof is substantially parallel to the tire rotation direction R shown in FIG. Thereby, since the amount of bending of the rubber at the periphery of the closing groove 21 and the surrounding sipe 22 (or the surrounding narrow groove 22) can be suppressed, the block rigidity during traveling can be ensured.

  Note that the surrounding sipe 22 (or the surrounding narrow groove 22) of the third embodiment may be closed at one place as described above, or may be divided. Furthermore, a cut sipe (or a cut groove) as in the first embodiment may be used.

  Also in the pneumatic tire according to the third embodiment, the same effects as those of the first and second embodiments can be obtained.

  Example 4 of the pneumatic tire according to the present invention is shown in FIGS. 7-1 and 7-2. This pneumatic tire is provided with a flask-shaped closing groove 31 having a substantially rectangular cross section and a substantially rectangular cut sipe 32 (or a cut narrow groove 32).

  The closing groove 31 is also preferably disposed in the block portion B so that its longitudinal direction is substantially parallel to the tire rotation direction R shown in FIG.

  Instead of the cut sipe 32 (or the cut narrow groove 32) of the fourth embodiment, a surrounding sipe (or a narrow groove) as in the second embodiment may be provided.

  Also in the pneumatic tire according to the fourth embodiment, the same effects as those of the first and second embodiments can be obtained.

  Example 5 of the pneumatic tire according to the present invention is shown in FIGS. This pneumatic tire includes a round-bottomed flask-shaped closing groove 41 having a substantially circular cross section, and a substantially circular cut sipe 42 (or a cut narrow groove 42).

  Also in the pneumatic tire according to the fifth embodiment, the same effects as those of the first and second embodiments can be obtained.

  Next, Example 6 of the pneumatic tire according to the present invention will be described. The pneumatic tire of Example 6 has a closed groove formed of a frustum groove portion.

  For example, the closing groove 51 shown in FIGS. 9-1 and 9-2 is formed into a truncated cone, and the closing groove 61 shown in FIGS. 9-3 and 9-4 is formed into a quadrangular pyramid. . As described above, even if the closing groove is formed only by the frustum groove portion, the same effects as those of the above-described embodiments can be obtained.

  In addition, although the sipes (or narrow grooves) are omitted in each of these drawings, the above-described notches and surroundings may be provided as necessary.

  As described above, in each of the first to sixth embodiments, the closed groove having a circular, elliptical, or rectangular cross-sectional shape is illustrated. However, the cross-sectional shape is not necessarily limited thereto, and for example, a triangular shape, a pentagonal shape, etc. It may be a polygonal shape or a star shape. Further, the closing groove has been described as being provided in the block portion, but the closing groove according to the present invention may be provided in the rib.

  As described above, the pneumatic tire according to the present invention is useful for improving drainage performance, and is particularly suitable for improving drainage performance when wear progresses.

FIG. 1-1 is a diagram illustrating Example 1 of a closed groove and a sipe (or narrow groove) included in a pneumatic tire according to the present invention, and is a top view as viewed from the tire ground contact surface side. FIG. 1-2 is a sectional view taken along line I-I shown in FIG. 1-1. FIG. 2 is a diagram showing an example of the arrangement of the closing grooves and sipes (or narrow grooves) in the pneumatic tire according to the present invention. FIG. 3 is a side view of the first embodiment. FIG. 4-1 is a diagram illustrating Example 2 of a closed groove and a sipe (or narrow groove) included in a pneumatic tire according to the present invention, and is a top view as viewed from the tire ground contact surface side. FIG. 4B is a cross-sectional view taken along line II-II shown in FIG. FIG. 5A is a diagram illustrating another example of the sipe (or narrow groove) of the second embodiment, and is a top view seen from the tire ground contact surface side. FIG. 5-2 is a diagram illustrating still another example of the sipe (or narrow groove) of the second embodiment, and is a top view as seen from the tire contact surface side. FIG. 6-1 is a diagram illustrating Example 3 of a closed groove and a sipe (or narrow groove) included in a pneumatic tire according to the present invention, and is a top view as viewed from the tire ground contact surface side. FIG. 6B is a sectional view taken along line III-III shown in FIG. FIG. 7-1 is a diagram illustrating Example 4 of a closed groove and a sipe (or narrow groove) included in a pneumatic tire according to the present invention, and is a top view as viewed from the tire ground contact surface side. FIG. 7B is a cross-sectional view taken along line IV-IV shown in FIG. FIG. 8-1 is a diagram illustrating Example 5 of a closing groove and a sipe (or narrow groove) included in a pneumatic tire according to the present invention, and is a top view as viewed from the tire ground contact surface side. 8-2 is a cross-sectional view taken along line VV shown in FIG. 8-1. FIG. 9A is a diagram illustrating a sixth embodiment of the closing groove included in the pneumatic tire according to the present invention, and is a top view of the truncated conical groove viewed from the tire ground contact surface side. 9-2 is a cross-sectional view taken along line VI-VI shown in FIG. FIG. 9-3 is a diagram showing Example 6 of the closing groove provided in the pneumatic tire according to the present invention, and is a top view of the truncated pyramid-shaped closing groove as seen from the tire ground contact surface side. 9-4 is a sectional view taken along line VII-VII shown in FIG. 9-3.

Explanation of symbols

1,11,21,31,41,51,61 Closed groove 1a Cylindrical part 1b Frustum part 2,12,22,32,42 Sipe (or narrow groove)
B Block part R Tire rotation direction

Claims (9)

In pneumatic tires with closed grooves on the tread surface,
2. The pneumatic tire according to claim 1, wherein the closing groove has a widened groove portion that is wider than an opening portion on a tire ground contact surface side.   The pneumatic tire according to claim 1, wherein the closing groove has a columnar groove portion communicating with the widening groove portion on the opening side.   When the groove depth of the closed groove is D1, and the groove depth of the columnar groove is D2, the groove depth D2 of the columnar groove is in the range of D2 = 0 to 0.5D1. Item 3. The pneumatic tire according to Item 2.   The pneumatic tire according to claim 1, wherein at least one sipe or narrow groove communicating with the closed groove is provided. The groove width W3 of the sipe or narrow groove is 0.5 to 1.5 mm,
The pneumatic tire according to claim 4, wherein when the groove depth of the closed groove is D1, the groove depth D3 of the sipe or the narrow groove is set within a range of D3 = 1 / 3D1 to D1. In pneumatic tires with closed grooves on the tread surface,
An air comprising the closed groove having a widened groove portion that is wider than the opening portion on the tire ground contact surface side, and a continuous or discontinuous sipe or narrow groove surrounding the closed groove. Enter tire. In pneumatic tires with closed grooves on the tread surface,
The closed groove having a columnar groove portion on the tire grounding tread surface side and having a widened groove portion that is wider than the columnar groove portion on the inside, and a continuous or discontinuous sipes or narrow grooves surrounding the closed groove are provided. A pneumatic tire characterized by that. When the groove depth of the closed groove is D1, and the groove depth of the columnar groove is D2, the groove depth D2 of the columnar groove is in the range of D2 = 0.3 to 0.5D1,
The groove width W4 of the sipe or narrow groove is 1.0 to 2.0 mm,
The pneumatic tire according to claim 7, wherein a groove depth D4 of the sipe or the narrow groove is set within a range of D4 = 0.3D1 to D2. When the groove width on the tire ground contact surface side in the widening groove portion is W1, and the groove width of the maximum widening portion in the widening groove portion is W2, the groove widths W1 and W2 are in the range of W2 / W1 = 1.2 to 2,0. Inside
When the groove depth of the closed groove is D1 and the groove depth of the main groove is D, the groove depth D1 of the closed groove is set within a range of D1 = 0.3D to 1.0D. The pneumatic tire according to any one of claims 1 to 8.

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