JP2010208356A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of equalizing the rigidity in the tire circumferential direction without dropping the degree of freedom in designing the cross-sectional shape of lug grooves even in a construction in which the groove width of the lug grooves in the tire circumferential direction differs according to the length of blocks in the tire circumferential direction. <P>SOLUTION: Chamfers 7a, 7b, 7c are arranged in corners of blocks 7 with a large pitch A, medium pitch B and small pitch C respectively among blocks 7 facing the lug grooves 6 crossing vertical grooves 5, and formed so that the chamfer volume in the block 7 facing the lug groove 6 with small groove width in the tire circumferential direction becomes larger than the chamfer volume in the block 7 facing the lug groove 6 with large groove width in the tire circumferential direction, thereby, deviation of the volume of the rubber pushed in during vulcanization molding becomes small. In this case, because the volume of the rubber pushed in is equalized due to the difference in the chamfer volume of the chamfers 7a, 7b, 7c, the degree of freedom in designing the cross-sectional shape of the lug grooves 6 is not dropped. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire used in, for example, passenger cars, trucks, buses and the like.

  Conventionally, this type of pneumatic tire has a longitudinal groove extending in the tire circumferential direction, a lug groove extending in the tire width direction, and a block formed between the longitudinal groove and the lug groove. By adopting a so-called pitch variation method in which blocks with different lengths are arranged in the tire circumferential direction, noise caused by contact between the blocks and the road surface is prevented from increasing at a specific frequency, thereby reducing noise. Things are known.

  By the way, in the pneumatic tire, when the lug groove is formed at the time of vulcanization of the tire, the rubber of the tread portion is pushed by the convex portion of the mold, but the pushed rubber flows and flows below the lug groove, The thickness from the bottom of the lug groove to the tire inner surface becomes thicker as it approaches the vertical groove. However, since the groove width in the tire circumferential direction of the lug groove is formed so as to increase as the length of the block in the tire circumferential direction increases, the convexity of the mold is increased between the lug groove having a large groove width and the small lug groove. The amount of rubber pushed in by the part is biased. For this reason, there is a problem that the rigidity of the rubber becomes uneven in the tire circumferential direction, causing uneven wear. Thus, there is known a technique in which the rigidity in the tire circumferential direction is made uniform by adjusting the cross-sectional area of the lug groove (see, for example, Patent Document 1).

JP 2004-210133 A

  However, if the rigidity in the tire circumferential direction is made uniform by adjusting the cross-sectional area of the lug groove, for example, the inclination angle of the groove wall of the lug groove with a small groove width is increased, and the inclination of the groove wall of the lug groove with a large groove width is increased. There is a problem that the degree of freedom in designing the cross-sectional shape of the lug groove is greatly impaired, such as the need to reduce the angle.

  The present invention has been made in view of the above problems, and the object of the present invention is to provide a lug groove even in a configuration in which the groove width in the tire circumferential direction of the lug groove differs depending on the length of the block in the tire circumferential direction. An object of the present invention is to provide a pneumatic tire capable of making the rigidity in the tire circumferential direction uniform without impairing the design freedom of the cross-sectional shape.

  In order to achieve the above object, the present invention comprises a longitudinal groove extending in the tire circumferential direction, a lug groove extending in the tire width direction, and a block defined by the longitudinal groove and the lug groove, and has a length in the tire circumferential direction. In a pneumatic tire in which different blocks are arranged in the tire circumferential direction, and the lug groove is formed so that the groove width in the tire circumferential direction varies depending on the length of the block in the tire circumferential direction, the lug crossing the longitudinal groove At least one block facing the groove is provided with a chamfered portion, and the chamfered portion of the block facing the lug groove having a small groove width in the tire circumferential direction is a lug having a large groove width in the tire circumferential direction. It is formed so as to be larger than the chamfered volume in the block facing the groove.

  As a result, the chamfered volume of the chamfered portion in the block facing the lug groove having a small groove width in the tire circumferential direction is larger than the chamfered volume of the chamfered portion in the block facing the lug groove having a large groove width in the tire circumferential direction. Therefore, even in the lug grooves having different groove widths, the amount of rubber pushed in during vulcanization molding is reduced. In this case, the rubber push-in amount is made uniform by the size of the chamfered volume of the chamfered portion, so that the degree of freedom in designing the cross-sectional shape of the lug groove is not impaired.

  According to the present invention, even in the lug grooves having different groove widths, it is possible to reduce the bias of the amount of rubber pushed in at the time of vulcanization molding, so that the rigidity in the tire circumferential direction can be made uniform, and uneven wear resistance It is possible to improve the performance. In this case, since the design freedom of the cross-sectional shape of the lug groove is not impaired, for example, the inclination angle of the groove wall can be arbitrarily set to improve other tire performance.

Partial front sectional view of the pneumatic tire showing the first embodiment of the present invention Partial plan view of pneumatic tire Perspective view of main part of pneumatic tire Partial side sectional view showing the indented state of rubber The principal part perspective view of the pneumatic tire which shows the modification of a chamfering position The principal part perspective view of the pneumatic tire which shows the other modification of a chamfering position The principal part perspective view of the pneumatic tire which shows the modification of a chamfering part The principal part perspective view of the pneumatic tire which shows the other modification of a chamfering part The fragmentary top view of the pneumatic tire which shows the 2nd Embodiment of this invention Side sectional view of the main part of a pneumatic tire The principal part perspective view of the pneumatic tire which shows the modification of a chamfering position The principal part perspective view of the pneumatic tire which shows the modification of a chamfering part The principal part perspective view of the pneumatic tire which shows the other modification of a chamfering part Diagram showing test results

  1 to 7 show a first embodiment of the present invention. FIG. 1 is a partial front sectional view of a pneumatic tire, FIG. 2 is a partial plan view thereof, FIG. 3 is a perspective view of essential parts thereof, and FIG. FIG. 5 is a partial perspective view of a pneumatic tire showing a modified example of the chamfered position, and FIG. 6 is a perspective view of the essential part of the pneumatic tire showing another modified example of the chamfered position. FIG. 7 is a perspective view of a main part of a pneumatic tire showing a modified example of the chamfered part, and FIG. 8 is a perspective view of a main part of the pneumatic tire showing another modified example of the chamfered part.

  The pneumatic tire shown in the figure is formed between a tread portion 1 formed on the tire outer peripheral surface side, sidewall portions 2 formed on both sides in the tire width direction, and the tread portion 1 and the sidewall portions 2. A shoulder portion 3 and a bead portion 4 formed on the inner side in the tire radial direction of the sidewall portion 2, and a bead core 4 a is embedded in the bead portion 4.

  The tread portion 1 is provided with a plurality of vertical grooves 5 extending in the tire circumferential direction, a plurality of lug grooves 6 extending in the tire width direction, and a plurality of blocks 7 defined by the vertical grooves 5 and the lug grooves 6. Each block 7 is formed to have a length of any one of a large pitch A, a medium pitch B, and a small pitch C having different lengths in the tire circumferential direction. In this case, the lug grooves 6 are formed such that the groove width in the tire circumferential direction increases as the pitches A, B, and C of the blocks 7 increase. That is, the tire circumferential direction groove width a of the lug groove 6 adjacent to one side in the tire width direction of the large pitch A block 7 and the tire circumferential direction of the lug groove 6 adjacent to one side in the tire width direction of the medium pitch B block 7 And the groove width c in the tire circumferential direction of the lug groove 6 adjacent to one side in the tire width direction of the block 7 having the small pitch C are in a relationship of a> b> c.

  Further, one corner of the block 7 facing the lug groove 6 crossing the vertical groove 5 (the corner formed by the grounding surface, the groove wall on the lug groove 6 side and the groove wall on the vertical groove 5 side) is chamfered. The chamfered portion 7a of the block 7 with the large pitch A has a smaller chamfered volume than the chamfered portion 7b of the block 7 with the medium pitch B, and the chamfered portion 7b of the block 7 with the medium pitch B is the block 7 with the small pitch C. The chamfered volume is smaller than the chamfered portion 7c. In this case, the chamfered portions 7a, 7b, and 7c are formed to have different chamfered volumes according to the groove width in the tire circumferential direction of the lug groove 6 by changing the length in the tire circumferential direction and the tire width direction. Yes. That is, as shown in FIG. 3, the chamfered portions 7a, 7b, and 7c have the same length in the tire radial direction, and the chamfered portion 7a of the block 7 having the large pitch A has a tire circumferential length L1 and a tire width length. W1 is smaller than the tire circumferential direction length L2 and tire width direction length W2 of the chamfered portion 7b of the medium pitch B block 7, and the chamfered portion 7b of the medium pitch B block 7 has the tire circumferential direction length L2 and tire width. The direction length W2 is formed to be smaller than the tire circumferential direction length L3 and the tire width direction length W3 of the chamfered portion 7c of the block 7 having the small pitch C. Each chamfered portion 7 a, 7 b, 7 c is provided at least on the block 7 of the shoulder portion 3.

  In the pneumatic tire, when the lug groove 5 is formed during vulcanization molding, the rubber of the tread portion 1 is pushed in by the convex portion of the mold D as shown in FIG. The thickness t from the bottom of the lug groove 6 to the tire inner surface becomes thicker as it approaches the vertical groove 6. In this case, in this embodiment, the chamfered portions 7a, 7b, 7c of the block 7 are formed such that the chamfered volume increases as the groove widths a, b, c in the tire circumferential direction of the lug groove 6 decrease. 4a, the lug groove 6 adjacent to the large pitch A block 7 shown in FIG. 4 (a), and the pushing amount of the groove width c of the lug groove 6 adjacent to the small pitch C block 7 shown in FIG. 4 (b). In the meantime, the deviation of the amount of rubber pushed by the mold D is reduced, and the rigidity of the rubber in the tire circumferential direction is made uniform.

  Thus, according to the pneumatic tire of the present embodiment, among the blocks 7 facing the lug grooves 6 crossing the longitudinal grooves 5, the corners of the large pitch A, medium pitch B, and small pitch C blocks 7. The chamfered portions 7a, 7b, and 7c are respectively provided, and the chamfered volume in the block 7 facing the chamfered portions 7a, 7b, and 7c with the lug groove 6 having a small groove width in the tire circumferential direction is large in the tire circumferential direction. Since it is formed so as to be larger than the chamfered volume in the block 7 facing the lug groove 6, even in the lug grooves 6 having different groove widths, it is possible to reduce the bias of the amount of rubber pushed in during vulcanization molding. Thereby, the rigidity in the tire circumferential direction can be made uniform, and uneven wear resistance can be improved. In this case, the amount of rubber pushed in is uniformed by the chamfered volume of the chamfered portions 7a, 7b, 7c, so that the degree of freedom in designing the cross-sectional shape of the lug groove 6 is not impaired. It can be arbitrarily set to improve other tire performances.

  In the embodiment, among the blocks 7 facing the lug grooves 6 crossing the longitudinal grooves 5, one chamfered portion 7a, one at each corner of the block 7 having a large pitch A, a medium pitch B, and a small pitch C. 7b and 7c are shown. However, as shown in FIG. 5, chamfered portions 7a, 7b, and 7c are provided at all corners of the block 7 at the intersection of the lug groove 6 and the longitudinal groove 5, respectively. For example, the chamfered volume can be dispersed and the rigidity deviation of the block 7 can be reduced.

  In addition, as shown in FIG. 6, the number of chamfered portions 7c provided at the corners of the block 7 at the intersection of the lug groove 6 and the vertical groove 5 with a small groove width in the tire circumferential direction is the groove width in the tire circumferential direction. If the number of chamfered portions 7a is larger than the number of chamfered portions 7a provided at the corners of the block 7 at the intersection of the large lug groove 6 and the vertical groove 5, the amount of rubber pushed in is adjusted by the number of chamfered portions 7a, 7b, 7c. This is effective in achieving uniform rigidity.

  Furthermore, in the above-described embodiment, the chamfered portions 7a, 7b, and 7c are formed by changing the tire circumferential direction lengths L1, L2, and L3 and the tire width direction lengths W1, W2, and W3 to each other. Although the chamfered volume varies depending on the groove widths a, b, and c in the direction, the tire diameters of the chamfered portions 7a, 7b, and 7c are shown in FIGS. 7 (a), (b), and (c). The chamfered volume may be changed by changing the lengths H1, H2, and H3 in the direction. Further, as shown in FIG. 8, the chamfered volume may be changed by changing the shape of the chamfered portions 7a, 7b, 7c in the direction perpendicular to the surface. In this case, the chamfered portion 7a corresponding to the groove width a of the large pitch A is convex as shown in FIG. 8 (a), and the chamfered portion corresponding to the groove width b of the medium pitch B as shown in FIG. 8 (b). The chamfered portion 7c corresponding to the groove width c of the small pitch C is formed in a concave shape as shown in FIG. 8 (c).

  9 to 13 show a second embodiment of the present invention. FIG. 9 is a partial plan view of a pneumatic tire, FIG. 10 is a side sectional view of an essential part thereof, and FIG. 11 shows a modified example of the chamfering position. FIG. 12 is a perspective view of a main part of a pneumatic tire showing a modified example of the chamfered part, and FIG. 13 is a perspective view of a main part of the pneumatic tire showing another modified example of the chamfered part. . In addition, the same code | symbol is attached | subjected and shown to the component equivalent to the said embodiment.

  In the present embodiment, a chamfered portion extending in the tire circumferential direction at one corner portion (corner portion formed by the ground contact surface and the groove wall on the longitudinal groove 5 side) of the block 7 facing the lug groove 6 crossing the longitudinal groove 5. The chamfered portion 7d of the block 7 with the large pitch A has a smaller chamfered volume than the chamfered portion 7e of the block 7 with the medium pitch B, and the chamfered portion 7e of the block 7 with the medium pitch B The chamfered volume is smaller than the chamfered portion 7f. In this case, the chamfered portions 7d, 7e, and 7f are formed to have different chamfered volumes according to the groove width in the tire circumferential direction of the lug groove 6 by changing the length in the tire width direction. That is, as shown in FIG. 10, the chamfered portions 7d, 7e, and 7f have the same length in the tire radial direction, and the chamfered portion 7d of the block 7 with a large pitch A has a block W1 with a width W1 in the tire width direction. Tire width direction length W3 of chamfered portion 7e of chamfered portion 7e of chamfered portion 7e of chamfered portion 7e of chamfered portion 7e. It is formed to be smaller than that. Further, the chamfered portions 7 d, 7 e, 7 f are provided at least on the block 7 of the shoulder portion 3.

  According to the pneumatic tire of this embodiment, the chamfered volume in the block 7 facing the lug groove 6 having the chamfered portions 7d, 7e, 7f facing the small groove width in the tire circumferential direction is the tire circumferential direction, as in the above embodiment. Since the groove is formed so as to be larger than the chamfered volume in the block 7 facing the lug groove 6, even in the lug grooves 6 having different groove widths, the amount of rubber pushed in at the time of vulcanization molding is reduced. can do. Thereby, the rigidity in the tire circumferential direction can be made uniform, and uneven wear resistance can be improved. Moreover, since the design freedom of the cross-sectional shape of the lug groove 6 is not impaired as in the above embodiment, for example, the inclination angle of the groove wall can be arbitrarily set to improve other tire performance.

  In the embodiment, among the blocks 7 facing the lug grooves 6 crossing the vertical grooves 5, the large pitch A, medium pitch B and small pitch C blocks adjacent to one groove wall in the width direction of the vertical grooves 5. Although the chamfered portions 7d, 7e, and 7f are respectively provided at the corner portions of the groove 7, as shown in FIG. 11, the corner portions of the block 7 adjacent to the groove walls on both sides in the width direction of the longitudinal groove 5 are shown. If the chamfered portions 7d, 7e, and 7f are provided, the chamfered volume can be dispersed and the rigidity deviation of the block 7 can be reduced.

  In the embodiment, the chamfered portions 7d, 7e, and 7f are changed according to the groove widths a, b, and c of the lug groove 6 in the tire circumferential direction by changing the lengths W1, W2, and W3 in the tire width direction. Although different chamfered volumes are shown, as shown in FIGS. 12 (a) (b) (c), the lengths H1, H2, and H3 in the tire radial direction of the chamfered portions 7d, 7e, and 7f are changed. The chamfered volume may be made different. Further, as shown in FIG. 13, the chamfered volume may be changed by changing the shape of the chamfered portions 7d, 7e, 7f in the direction perpendicular to the surface. In this case, the chamfered portion 7d corresponding to the groove width a of the large pitch A is convex as shown in FIG. 13 (a), and the chamfered portion corresponding to the groove width b of the medium pitch B as shown in FIG. 13 (b). 7e is a flat surface, and as shown in FIG. 13C, the chamfered portion 7f corresponding to the groove width c of the small pitch C is formed in a concave shape.

  In the above embodiment, the chamfered portions 7d, 7e, and 7f are formed so that the lengths W1, W2, and W3 in the tire width direction are uniform along the tire circumferential direction. It is also possible to form the tire 6 in such a manner that the length in the tire width direction gradually increases from the larger groove width in the tire circumferential direction toward the smaller one.

  Here, when Examples 1 to 3 of the present invention and the conventional example were tested for uniformity (RFV) and uneven wear resistance, the results shown in FIG. 14 were obtained. In the conventional example, a chamfered portion is provided at one corner of the corner formed by the grounding surface of the block, the groove wall on the lug groove side, and the groove wall on the vertical groove side at the intersection of the vertical groove and the lug groove. The smaller the tire circumferential pitch, the larger the inclination angle of the groove wall of the lug groove and the smaller the chamfered portion width (the length in the tire circumferential direction and the tire width direction). In the first embodiment, one corner of the corner (first embodiment) formed by the grounding surface of the block, the groove wall on the lug groove side, and the groove wall on the vertical groove side at the intersection of the vertical groove and the lug groove. As the chamfered portion is provided in the tire, the inclination angle of the groove wall of the lug groove increases and the width of the chamfered portion (the length in the tire circumferential direction and the tire width direction) increases as the tire circumferential pitch of the block decreases. . In Example 2, both sides of the vertical groove in the corner portion (first embodiment) formed by the grounding surface of the block, the groove wall on the lug groove side, and the groove wall on the vertical groove side at the intersection of the vertical groove and the lug groove are shown. Chamfered portions are provided at the two corners located at, and the inclination angle of the groove wall of the lug groove increases as the tire circumferential pitch of the block decreases, and the width of the chamfered portion (length in the tire circumferential direction and tire width direction) The one that increases is used. In Example 3, the corner portion (second embodiment) formed by the ground contact surface of the block and the groove wall on the longitudinal groove side at the intersection of the longitudinal groove and the lug groove is chamfered at the corner portion located on one side of the longitudinal groove. As the pitch in the tire circumferential direction of the block decreases, the inclination angle of the groove wall of the lug groove decreases and the depth of the chamfered portion (the length of the tire diameter) increases. This test was performed on a tire having a tire size of 195 / 65R15 under the condition of an air pressure of 180 kPa.

  In the uniformity test, RFV is measured by the measurement method defined in JASO C60-87, and the average value of 10 tires is evaluated using an index when the conventional example is set to 100, and it is determined that the higher value is superior. did. As a result of the test, Examples 1 to 3 were superior to the conventional example in RFV.

  In the uneven wear resistance test, after running for 80 km, the difference in wear amount between the block kicking side and the stepping side edge portion was measured and its reciprocal number was indexed. In this case, it was determined that the larger the index value, the more superior. As a result of the test, Examples 1 to 3 were excellent in uneven wear resistance compared to the conventional example.

  DESCRIPTION OF SYMBOLS 1 ... Tread part, 3 ... Shoulder part, 5 ... Vertical groove, 6 ... Lug groove, 7 ... Block, 7a, 7b, 7c, 7d, 7e, 7f ... Chamfering part.

Claims (11)

A longitudinal groove extending in the tire circumferential direction, a lug groove extending in the tire width direction, and a block defined by the longitudinal groove and the lug groove are arranged, and blocks having different lengths in the tire circumferential direction are arranged in the tire circumferential direction. In the pneumatic tire in which the groove width in the tire circumferential direction is different depending on the length in the tire circumferential direction of the block,
A chamfered portion is provided in at least one of the blocks facing the lug groove that crosses the longitudinal groove, and
The chamfered portion is formed so that the chamfered volume in the block facing the lug groove with a small groove width in the tire circumferential direction is larger than the chamfered volume in the block facing the lug groove with a large groove width in the tire circumferential direction. A featured pneumatic tire. The chamfered portion is formed at the corner formed by the grounding surface of the block, the groove wall on the lug groove side, and the groove wall on the vertical groove side,
The pneumatic tire according to claim 1, wherein a chamfered portion is provided at at least one corner portion of each block at the intersection of the lug groove and the longitudinal groove. The chamfered portion is formed such that the chamfered volume differs depending on the groove width in the tire circumferential direction of the lug groove by changing the length in the tire circumferential direction and the tire width direction. Pneumatic tire. The pneumatic tire according to claim 2, wherein the chamfered portions are formed such that the chamfered volumes differ according to the groove width in the tire circumferential direction of the lug grooves by changing the length in the tire radial direction. The pneumatic according to claim 2, wherein the chamfered portions are formed so as to have different chamfered volumes according to the groove width in the tire circumferential direction of the lug grooves by changing the shape of the irregularities in the direction perpendicular to the surface. tire. The number of chamfered portions provided at the corners of the block at the intersection of the lug groove and the vertical groove having a small groove width in the tire circumferential direction is the intersection of the lug groove and the vertical groove having a large groove width in the tire circumferential direction. The pneumatic tire according to claim 2, wherein the pneumatic tire is provided so as to be larger than the number of chamfered portions provided at corner portions of the block in the portion. Forming the chamfered portion at the corner formed by the grounding surface of the block and the groove wall on the longitudinal groove side;
The pneumatic tire according to claim 1, wherein a chamfered portion is provided at at least one corner portion of each block at the intersection of the lug groove and the longitudinal groove. The pneumatic tire according to claim 7, wherein the chamfered portions are formed so as to have different chamfered volumes depending on the groove width in the tire circumferential direction of the lug grooves by changing the length in the tire width direction. The pneumatic tire according to claim 7, wherein the chamfered portions are formed so as to have different chamfered volumes depending on the groove width in the tire circumferential direction of the lug grooves by changing the length in the tire radial direction. The pneumatic according to claim 7, wherein the chamfered portions are formed so as to have different chamfered volumes according to the groove width in the tire circumferential direction of the lug grooves by changing the shape that forms irregularities in the direction perpendicular to the surface. tire. The pneumatic tire according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the chamfered portion is provided at least on a shoulder side block.

Images