JP4785552B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire such as a heavy duty pneumatic tire, and more particularly to a tread of a pneumatic tire.

  Background art will be described with reference to FIGS.

  Here, FIG. 5 is a diagram showing a general configuration of a pneumatic tire according to an embodiment of the present invention or a conventional pneumatic tire, and FIG. 6 is a pneumatic tire according to an embodiment of the present invention or conventional air. FIG. 7 is a plan development view showing a part of a tread of a conventional pneumatic tire, and FIG. 8 is a conventional pneumatic FIG. 9 is a perspective view showing a part of a sector mold used for vulcanization molding of a conventional pneumatic tire, and FIG. 9 is a perspective view of a sector mold segment used for vulcanization molding of a tire.

  As shown in FIG. 5, the general configuration of a pneumatic tire 1 such as a conventional heavy duty pneumatic tire is as follows.

  That is, the pneumatic tire 1 includes a pair of annular beads 5 that can be fitted to the rim 3, and each bead 5 includes a bead core 7. A carcass 9 as a skeleton member is integrally provided between the pair of beads 5, and the carcass 9 has a toroidal cross-sectional shape. Further, a multilayer belt 11 is provided on the outer peripheral surface of the carcass 9.

  A groundable tread 13 is integrally provided on the outer peripheral surface of the carcass 9 so as to cover the belt 11, and side walls 15 that protect the carcass 9 are respectively provided on one side surface and the other side surface of the carcass 9. It is provided integrally. An inner liner 17 that prevents air leakage is integrally provided on the inner surface of the carcass 9.

  When the pneumatic tire 1 is vulcanized and molded, a vulcanizing mold 19 as shown in FIG. 6 is used, and the general configuration of the vulcanizing mold 19 is as follows.

  That is, the lower frame (not shown) in the vulcanizer is provided with an annular lower mold 21 for mainly molding one side wall 15 and one bead 5, and the upper frame (not shown) in the vulcanizer. Is provided with an upper mold 23 for mainly molding the other side wall 15 and the other bead 5. Here, the upper frame is movable in the vertical direction relative to the lower frame. In other words, the upper mold 23 is movable in the vertical direction relative to the lower mold 21.

  As shown in FIGS. 8 and 9, the lower mold 21 is provided with an annular sector mold 25 for mainly molding the tread 13, and the sector mold 25 is composed of a plurality of arc-shaped segments 27. Thus, the plurality of segments 27 can be expanded and contracted in the radial direction of the sector mold 25. A plurality of annular groove forming projections 29 are formed inside the sector mold 25 (in other words, inside the plurality of segments 27). In addition, a large number of projection molding holes 31 are formed in each groove molding projection 29 at intervals in the mold circumferential direction Cm. Each of the groove molding projections 29 has a plurality of air escape slits 33. A number of projection molding holes 31 are formed to communicate with the end portions of the segments 27. Further, a plurality of first projecting piece molding holes 35 are formed in one side portion of each groove molding projection 29 at intervals in the mold circumferential direction Cm. A plurality of second projecting piece molding holes 37 are respectively formed on the side portions of the first projecting piece molding holes 35 so as to be spaced apart from each other in the mold circumferential direction Cm and close to the corresponding first projecting piece molding holes 35.

  Next, a specific configuration of the tread 13 of the conventional pneumatic tire 1 will be described including the relevance to molding by the vulcanization mold 19.

  That is, as shown in FIG. 7, a plurality of (for example, four) circumferential main grooves 39 extending in the tire circumferential direction C are formed on the surface of the tread 13, and the plurality of circumferential main grooves 39 are It is formed by a plurality of groove forming protrusions 29 in the sector mold 25. The two circumferential main grooves 39 on the center side are arranged so as to sandwich the tire equator line T. A plurality of ribs 41 extending in the tire circumferential direction C are partitioned in the tire width direction W by the plurality of circumferential main grooves 39.

  A large number of protrusions 43 are formed on the bottom surface of each circumferential main groove 39 at intervals in the tire circumferential direction C. The large number of protrusions 43 are formed by the large number of protrusion molding holes 31 in the groove forming protrusions 29. Has been. Here, the large number of protrusions 43 suppress the stone biting and prevent the stone from being pushed into the bottom surface side of the circumferential main groove 39 and entering the inside of the tread 13 even if the stone is bitten. A slit mark 45 is formed on the bottom surface of each circumferential main groove 39 so as to connect a large number of protrusions 43. The slit marks 45 are formed by a plurality of air escape slits 33 in the groove forming protrusions 29. Molded.

  In each of the circumferential main grooves 39, a plurality of pairs of projecting pieces 47 for reducing air column resonance are arranged at intervals, and each of the projecting piece pairs 47 is one of the circumferential main grooves 39. The first projecting piece 49 formed on the wall surface and the second projecting piece 51 formed on the other wall surface of the circumferential main groove 39 and adjacent to the first projecting piece 49 in a corresponding relationship are included. The plurality of first protruding pieces 49 are formed by the plurality of first protruding piece forming holes 35 in the groove forming protrusion 29, and the plurality of second protruding pieces 51 are formed in the plurality of groove forming protrusions 29. It is molded by the second projecting piece molding hole 37.

In addition, there exists a thing shown to patent document 1 as a prior art relevant to this invention.
JP-A-11-105511

  Incidentally, in order to reduce air columnar resonance in the circumferential main groove 39 by the protruding piece pair 47, the slit mark 45 exists between the first protruding piece 49 and the second protruding piece 51 as a matter of course. In order to avoid this, an appropriate portion of the slit mark 45 must be divided. Therefore, it is necessary to partially block (divide) the air escape slit 33 in the segment 27. On the other hand, when the air escape slit 33 in the segment 27 is partially blocked, the air remaining in the projection molding hole 31 is transferred from the air escape slit 33 to the segment 27 when the pneumatic tire 1 is vulcanized. There is a problem in that it becomes difficult to escape to the end portion, a bear defect such as the protrusion 43 occurs, and the quality of the pneumatic tire 1 is deteriorated. In particular, when there are a plurality of blocking portions of the air escape slit 33 in one segment 27, air easily accumulates between the blocking portions of the air escape slit 33, and the above-described problem becomes more prominent.

  Therefore, in order to solve the above-mentioned problem, the present invention can reduce air column resonance in the circumferential main groove by the protruding piece pair without partially blocking the air escape slit in the segment. An object is to provide a pneumatic tire having a novel configuration.

  A first feature of the present invention (a feature of the invention described in claim 1) is that a plurality of circumferential main grooves extending in the tire circumferential direction are formed on the surface of the tread, and the plurality of circumferential main grooves are a plurality of A plurality of protrusions formed on the bottom surface of at least one of the plurality of circumferential main grooves formed by a plurality of annular groove forming protrusions formed inside an annular sector mold made up of segments of Are formed at intervals in the tire circumferential direction, and the plurality of projections are formed at intervals of at least one of the plurality of groove molding projections at intervals in the mold circumferential direction. Molded by a molding hole, a slit mark is formed on the bottom surface of any one of the circumferential main grooves so as to connect a large number of the protrusions, and the slit marks are formed on any one of the groove molding protrusions by forming a number of the protrusions. Hole Formed by a plurality of air escape slits formed so as to communicate with the ends of the segments, and a plurality of pairs of projecting pieces are disposed at intervals in any one of the circumferential main grooves. The one pair is formed on one wall surface of any one of the circumferential main grooves and connected to overlap the corresponding protrusions, and the other of the circumferential main grooves A plurality of first protruding pieces formed on the wall surface and connected to overlap the corresponding protrusions, and the plurality of first protruding pieces are provided on one side of any of the groove-forming protrusions. Molded by a plurality of first projecting piece molding holes formed at intervals in the mold circumferential direction and communicating with the corresponding projecting molding holes, and the plurality of second projecting pieces are either The other side of the groove molding projection Wherein is that molded by a plurality of second projecting piece molded holes formed so as to communicate with the projection molding hole in the mold circumferential direction by an interval and correspondence.

  According to the first feature, the first projecting piece and the second projecting piece are connected so as to overlap with the corresponding projections, respectively, so that the first projecting piece is not divided and the first projecting piece is not divided. It is possible to prevent the slit mark from being present between the protruding piece and the second protruding piece. Thereby, air columnar resonance in the circumferential main groove can be reduced by the protruding piece pair without partially blocking the air escape slit in the segment.

  In addition to the first feature, the second feature of the present invention (feature of the invention described in claim 2) is that the first projecting piece and the second projecting piece in the pair of projecting pieces at normal tire internal pressure. The amount of clearance in the tire circumferential direction between the projecting pieces is 0.4 mm or more and 3.0 mm or less.

  According to a third feature of the present invention (a feature of the invention described in claim 3), in addition to the first feature or the second feature, the first projection in the pair of projecting pieces at the time of normal tire internal pressure. The gap in the tire width direction between the piece and the second protruding piece is 0.5 mm or more and 2.0 mm or less.

  A fourth feature of the present invention (a feature of the invention described in claim 4) is always formed on the tread during tire traveling in addition to any one of the first to third features. In the ground contact area, there is only one protruding piece pair in any of the tire circumferential grooves.

  According to the fourth feature, since there is only one protruding piece pair in any one of the circumferential main grooves in the ground contact region, it is compressed in any of the circumferential main grooves. It is possible to avoid the generation of a pumping sound when the air is ejected.

  According to a fifth feature of the present invention (a feature of the invention described in claim 5), in addition to any one of the first feature to the third feature, a large number of each circumferential main groove is provided. Protrusions are formed at intervals in the tire circumferential direction, and a plurality of pairs of protruding pieces are provided at intervals in each of the circumferential main grooves, and a ground contact area that is always formed on the tread during tire traveling. In each of the tire circumferential grooves, only one protruding piece pair exists, and the protruding piece pair has a phase difference in the tire circumferential direction for each circumferential main groove. It is.

  According to the fifth feature, since there is only one protruding piece pair in each of the circumferential main grooves in the ground contact region, each of the circumferential main grooves is compressed. Generation of a pumping sound when air is ejected can be avoided. Further, since the pair of projecting pieces has a phase difference in the tire circumferential direction for each circumferential main groove, noise peaks due to air column resonance in the plurality of circumferential main grooves can be dispersed.

  According to the invention of any one of claims 1 to 5, in the circumferential main groove by the protruding piece pair without partially blocking the air escape slit in the segment. Therefore, when the pneumatic tire is vulcanized and molded, it remains in the projection molding hole, the first projection piece molding hole, and the second projection piece molding hole. The air thus easily escapes from the air escape slit to the end portion of the segment, and it is possible to improve the quality of the pneumatic tire by suppressing bear defects such as the protrusions.

  An embodiment of the present invention will be described with reference to FIGS.

  Here, FIG. 1 is a plan development view showing a part of a tread of a pneumatic tire according to an embodiment of the present invention, FIG. 2A is an enlarged view of a portion A in FIG. 1, and FIG. FIG. 2A is a view taken along line BB in FIG. 2A, FIG. 2C is a view taken along line CC in FIG. 2A, and FIG. 3 is air according to an embodiment of the present invention. FIG. 4 is a perspective view showing a part of a sector mold used for vulcanization molding of a pneumatic tire according to an embodiment of the present invention. FIG. 5 is a diagram showing a general configuration of a pneumatic tire according to an embodiment of the present invention or a conventional pneumatic tire, and FIG. 6 is a pneumatic tire according to an embodiment of the present invention or conventional air. It is a figure which shows the general structure of the vulcanization mold used for the vulcanization molding of a entering tire. .

  As shown in FIG. 5, a pneumatic tire 53 such as a heavy-duty pneumatic tire according to an embodiment of the present invention has a pair of beads 5 and a skeleton member as in the general configuration of the conventional pneumatic tire 1. In addition to the carcass 9, the multilayer belt 11, the pair of sidewalls 15, and the inner liner 17, a tread 55 having a configuration different from that of the tread 13 is provided. The specific configuration of the tread 55 will be described later.

  Further, as shown in FIG. 6, the vulcanization mold 57 used when vulcanizing the pneumatic tire 53 is similar to the general configuration of the vulcanization mold 19, and the lower mold 21 and the upper mold 23. In addition to this, an annular sector mold 59 having a configuration different from that of the annular sector mold 25 is provided, and the specific configuration of this sector mold 59 is as follows.

  That is, as shown in FIGS. 3 and 4, the sector mold 59 includes a plurality of arc-shaped segments 61, and the plurality of segments 61 can be expanded and contracted in the radial direction of the sector mold 59. A plurality of annular groove forming projections 63 are formed inside the sector mold 59 (in other words, inside the plurality of segments 61). In addition, a large number of projection molding holes 65 are formed in each groove molding projection 63 at intervals in the mold circumferential direction Cm. Each of the groove molding projections 63 has a plurality of air escape slits 67. A number of projection molding holes 65 are formed to communicate with the end portions of the segments 61.

  A plurality of first protruding piece forming holes 69 are formed on one side of each groove forming protrusion 63 at intervals in the mold circumferential direction Cm, and each first protruding piece forming hole 69 is formed. Are communicated with the corresponding protrusion molding holes 65. A plurality of second projecting piece molding holes 71 are formed in the other side portion of each groove molding projection 63 at intervals in the mold circumferential direction Cm. The holes 71 communicate with the protrusion molding holes 65 having a corresponding relationship.

  Next, a specific configuration of the tread 55 of the pneumatic tire 53 according to the embodiment of the present invention will be described including the relevance to molding by the vulcanization mold 57.

  That is, as shown in FIG. 1, a plurality of (four in the embodiment of the present invention) circumferential main grooves 73 extending in the tire circumferential direction C are formed on the surface of the tread 55. The plurality of circumferential main grooves 73 are formed by a plurality of groove forming protrusions 63 in the sector mold 59. The two circumferential main grooves 73 on the center side are arranged so as to sandwich the tire equator line T.

  A plurality of ribs 75 extending in the tire circumferential direction C are partitioned in the tire width direction W by the plurality of circumferential main grooves 73. Each rib 75 may be formed with a plurality of sipes or a plurality of lateral grooves at intervals in the tire circumferential direction C. Instead of the plurality of ribs 75, a plurality of blocks are arranged around the tire circumference. It may be formed at intervals in the direction C.

  As shown in FIGS. 1 and 2 (a), (b), and (c), a large number of protrusions 77 are formed at intervals in the tire circumferential direction C on the bottom surface of each circumferential main groove 73. A large number of projections 77 are formed by a large number of projection molding holes 65 in the groove molding projection 63. Here, the large number of protrusions 77 suppress the biting of the stone and prevent the stone from being pushed into the bottom surface side of the circumferential main groove 73 and entering the inside of the tread 13 even if the stone is bitten. A slit mark 79 is formed on the bottom surface of each circumferential main groove 73 so as to connect a large number of protrusions 77. The slit mark 79 is formed by a plurality of air escape slits 67 in the groove forming protrusion 63. Molded.

  In each circumferential main groove 73, a plurality of protruding piece pairs 81 for reducing air column resonance are arranged at intervals, and each protruding piece pair 81 is one of the circumferential main grooves 73. A first protruding piece 83 formed on the wall surface and connected to the corresponding protrusion 77, and a second protruding piece 85 formed on the other wall surface of the circumferential main groove 73 and connected to the corresponding protrusion 77. And each of them. The plurality of first protruding pieces 83 are formed by the plurality of first protruding piece forming holes 69 in the groove forming protrusion 63, and the plurality of second protruding pieces 85 are formed in the plurality of groove forming protrusions 63. It is molded by the second projecting piece molding hole 71. Further, in the ground contact region 87 that is always formed in the tread 55 during tire traveling, only one pair of protruding pieces 81 exists in each circumferential main groove 73, and the protruding piece pair 81 is provided. Has a phase difference in the tire circumferential direction C for each circumferential main groove 73.

  Further, a more specific configuration of the protruding piece pair 81 is as follows.

  That is, during normal tire internal pressure, the gap amount g in the tire circumferential direction C between the first protruding piece 83 and the second protruding piece 85 in the protruding piece pair 81 is 0.4 mm or more and 3.0 mm or less. It has become.

  Here, the gap g in the tire circumferential direction C between the first protruding piece 83 and the second protruding piece 85 in the protruding piece pair 81 is set to 0.4 mm or more. Is less than 0.4 mm, when an input such as side force is applied to the pneumatic tire 53, the first projecting piece 83 and the second projecting piece 85 collide with each other, and the first projecting piece 83 or the second projecting piece 85 This is because cracks are likely to occur in the protruding piece 85. On the other hand, the gap amount g in the tire circumferential direction C between the first protruding piece 83 and the second protruding piece 85 in the protruding piece pair 81 is 3.0 mm or less. If it exceeds 3.0 mm, sound can easily escape from between the first projecting piece 83 and the second projecting piece 85, and the air column resonance in the circumferential main groove 73 cannot be sufficiently reduced. It is.

  Note that the normal tire internal pressure is generally the air specified in the “pneumatic-load capacity correspondence table” in the standard in a state where a pneumatic tire is assembled to a standard application rim compliant with JATMA, TRA, or ETRTO standards. This is when the maximum air pressure corresponding to the maximum load capacity of the tire is filled. However, the normal tire internal pressure is not necessarily limited to when the maximum air pressure is filled, and which standard is compliant depends on the country or region where the pneumatic tire is used.

  During normal tire internal pressure, the gap amount k in the tire width direction W between the first protruding piece 83 and the second protruding piece 85 in the protruding piece pair 81 is 0.5 mm or more and 2.0 mm or less. ing.

  Here, the gap amount k in the tire width direction W between the first protruding piece 83 and the second protruding piece 85 in the protruding piece pair 81 is 0.5 mm or more. This is because if k is less than 0.5 mm, water hardly flows in the circumferential main groove 73, and the drainage of the circumferential main groove 73 cannot be sufficiently improved. On the other hand, the gap amount k in the tire width direction W between the first protruding piece 83 and the second protruding piece 85 in the protruding piece pair 81 is set to 2.0 mm or less. If the distance exceeds 2.0 mm, there is a gap in the tire width direction W between the first protruding piece 83 and the second protruding piece 85 even when the tire is running, and the circumferential main groove 73 This is because the internal air column resonance cannot be sufficiently reduced.

  Then, the effect | action and effect of embodiment of this invention are demonstrated.

  Since the first projecting piece 83 and the second projecting piece 85 are connected so as to overlap with the corresponding projections 77, the first projecting piece 83 and the second projecting piece 83 are separated without dividing the slit mark 79. It is possible to prevent the slit mark 79 from being present between the protruding piece 85. Thereby, air columnar resonance in the circumferential main groove 73 can be reduced by the protruding piece pair 81 without partially blocking the air escape slit 67 in the segment 61.

  In addition, since only one groove fence 81 exists in each circumferential main groove 73 in the ground contact region 87, when compressed air is ejected in each circumferential main groove 73. Generation of a pumping sound can be avoided.

  Furthermore, since the protruding piece pair 81 has a phase difference in the tire circumferential direction C for each circumferential main groove 73, noise peaks due to air columnar resonance in the plurality of circumferential main grooves 73 can be dispersed.

  As described above, according to the embodiment of the present invention, air columnar resonance in the circumferential main groove 73 is reduced by the protruding piece pair 81 without partially blocking the air escape slit 67 in the segment 61. Therefore, when the pneumatic tire 53 is vulcanized and molded, the air remaining in the projection molding hole 65, the first projecting piece molding hole 69, and the second projecting piece molding hole 71 is removed from the air escape slit 67. It is easy to escape from the end of the segment 61 to the end portion of the segment 61, and it is possible to improve the quality of the pneumatic tire 53 by suppressing bear defects such as the protrusion 77.

  In addition, it is possible to avoid the generation of pumping noise when the compressed air in each circumferential main groove 73 is ejected, and to disperse noise peaks due to air column resonance in the plurality of circumferential main grooves 73. , Noise during traveling can be sufficiently reduced.

  In addition, this invention is not restricted to description of the above-mentioned embodiment, In addition, it can implement in a various aspect. Further, the scope of rights encompassed by the present invention is not limited to these embodiments.

It is a plane development view showing a part of tread of a pneumatic tire concerning an embodiment of the present invention. 2A is an enlarged view of a portion A in FIG. 1, FIG. 2B is a view taken along line BB in FIG. 2A, and FIG. 2C is FIG. 2A. It is the figure along the CC line | wire in FIG. It is a perspective view of a segment of a sector mold used for vulcanization molding of a pneumatic tire concerning an embodiment of the present invention. It is a perspective view which shows a part of sector mold used for the vulcanization molding of the pneumatic tire which concerns on embodiment of this invention. It is a figure which shows the general structure of the pneumatic tire which concerns on embodiment of this invention, or the conventional pneumatic tire. It is a figure which shows the general structure of the vulcanization metal mold | die used for the vulcanization molding of the pneumatic tire which concerns on embodiment of this invention, or the conventional pneumatic tire. It is a plane development view showing a part of a tread of a conventional pneumatic tire. It is a perspective view of the segment of the sector mold used for the vulcanization molding of the conventional pneumatic tire. It is a perspective view which shows a part of sector mold used for the vulcanization molding of the conventional pneumatic tire.

Explanation of symbols

53 Pneumatic tire 55 Tread 59 Sector mold 61 Segment 63 Groove molding projection 65 Projection molding hole 67 Air vent slit 69 First projection piece molding hole 71 Second projection piece molding hole 73 Circumferential main groove 75 Rib 77 Projection 79 Slit Trace 81 Protruding piece pair 83 First protruding piece 85 Second protruding piece 87 Grounding area

Claims (5)

A plurality of circumferential main grooves extending in the tire circumferential direction are formed on the surface of the tread, and the plurality of circumferential main grooves are formed into an annular plurality of grooves formed inside an annular sector mold composed of a plurality of segments. Molded by protrusions,
A plurality of protrusions are formed on the bottom surface of at least one of the plurality of circumferential main grooves at intervals in the tire circumferential direction, and the plurality of protrusions are a plurality of groove forming protrusions. Is formed by a number of projection molding holes formed at intervals in the circumferential direction of the mold on at least one of the groove molding projections,
A slit mark is formed on the bottom surface of any one of the circumferential main grooves so as to connect a large number of the protrusions, and the slit mark has a large number of the protrusion forming holes formed in any one of the groove forming protrusions. Molded by a plurality of air escape slits formed to communicate with the part,
A plurality of pairs of protruding pieces are disposed at intervals in any of the circumferential main grooves, and each of the protruding piece pairs is formed on one wall surface of any of the circumferential main grooves and has a corresponding relationship. A first projecting piece coupled to overlap the certain projection, and a second projecting piece formed on the other wall surface of any one of the circumferential main grooves and coupled to the corresponding projection. Each of the plurality of first projecting pieces is formed on one side of any one of the groove molding projections so as to be spaced from the circumferential direction of the mold and communicate with the corresponding projection molding holes. The plurality of second projecting pieces are molded by the plurality of first projecting piece molding holes, and spaced apart in the circumferential direction of the mold on the other side portion of any one of the groove forming projections and correspond to each other Formed so as to communicate with the protrusion molding hole. A pneumatic tire characterized by molded by a plurality of second protruding piece molded hole.   During normal tire internal pressure, the gap in the tire circumferential direction between the first protruding piece and the second protruding piece in the pair of protruding pieces becomes 0.4 mm or more and 3.0 mm or less. The pneumatic tire according to claim 1, wherein   During normal tire internal pressure, the gap in the tire width direction between the first projecting piece and the second projecting piece in the pair of projecting pieces is 0.5 mm or more and 2.0 mm or less. The pneumatic tire according to claim 1 or 2, characterized in that.   2. The ground contact region that is always formed on the tread during tire traveling, wherein only one of the protruding piece pairs exists in any one of the tire circumferential grooves. The pneumatic tire according to claim 3. A large number of protrusions are formed in the circumferential direction of each tire in the circumferential direction of the tire, and a plurality of pairs of protruding pieces are provided in the circumferential direction of the circumferential direction, respectively.
In the ground contact region that is always formed on the tread during tire running, only one pair of protruding pieces exists in each tire circumferential groove, and the protruding piece pair is the main circumferential member. The pneumatic tire according to any one of claims 1 to 3, wherein each groove has a phase difference in the tire circumferential direction.

Images