JP5470114B2 - Pneumatic tire - Google Patents

Description

  In the tread portion, a small block group in which a plurality of small blocks partitioned by grooves are arranged in a plurality of columns and a plurality of rows is provided in the tread portion, and a tread grounding end is provided on the outer side in the tire width direction of the small blocks. The present invention relates to a pneumatic tire provided with a buttress block row composed of buttress blocks extending across.

  Since the rolling resistance of the tire affects the fuel consumption of the vehicle, the necessity of reducing this rolling resistance has been increased in accordance with the recent consideration for environmental load. In order to reduce the rolling resistance, it is necessary to reduce the energy consumed by the stress and strain accompanying the rolling of the tire, but the bead portion and the side portion extending from the bead portion to the tire radial direction, It is known that the energy consumed in the tread portion is the largest when the energy consumed in the tread portion located across both side portions is compared.

  For the purpose of reducing this rolling resistance, for example, in the tire described in Patent Document 1, from the ground contact end of each block in the block row of the shoulder region (width direction outer portion of the tread portion) to the portion outside the tire axial direction. The structure which provides a sipe is adopted. By providing the sipe in this manner, when the tire travels and enters the ground contact area, the circumferential and axial shear strain generated from the shoulder area to the buttress area (upper side wall area) is alleviated. .

JP-A-7-228106

  By the way, in this patent document 1, as a block provided in a tread part, the rectangular parallelepiped comparatively big block (For example, it is divided into five in the tire width direction) is employ | adopted. However, even if a sipe is provided on the outer side in the tire axial direction from the grounding end of the block, in such a relatively large block, when the tire rotates and enters the grounding area, the grounding area for each block is wide. It becomes. Each block receives an impact from the road surface at the time of ground contact, but it is difficult for the block to have appropriate flexibility when the ground contact area of each block is wide. Therefore, in recent years, it has been demanded that the block on the surface of the tread has an appropriate flexibility to obtain further good rolling resistance. This flexibility has been required among the blocks on the tread surface, in particular, for blocks located in the shoulder region where the block deformation is large during impact from the road surface or cornering.

  In response to the above requirements, the applicant further effectively reduces the rolling resistance of the tire by providing a group of blocks formed by closely gathering a plurality of small blocks partitioned by grooves in the shoulder region of the tread surface. I found that I can do it. In this way, if a plurality of small blocks are provided, the ground contact area between the tire tread surface and the road surface of the block is subdivided at the time of ground contact, so that each block can have flexibility. .

However, when a large number of small blocks are arranged on the tread surface in this way, the tire width direction length of the small blocks is reduced, so that the shear rigidity in the width direction is reduced.
When the tire rolls, the tread surface that is rounded with a certain curvature is forcibly pressed against the flat ground, and the round shape is forcibly stretched straight. This occurs particularly in small blocks located in the shoulder region of the tread surface. Then, the deformation in the width direction is repeatedly performed on the small block located in the region, which is stretched when pressed against the ground and returned to the original when leaving the ground. In this way, the small block located in the shoulder region causes the most shear deformation.
In cornering, in particular, lateral force in the width direction is applied to the small blocks located in the shoulder region on the tread surface. Therefore, also by this lateral force, the small block located in the portion is most susceptible to shear deformation.

As described above, the shear deformation is most likely to occur in the small block in the shoulder region. However, as this is repeated, the small block may not withstand the shearing force, and shoulder fall wear or step down wear may occur.
It has been found that this shoulder fall wear and step down wear are most likely to occur particularly in the block rows formed by the small blocks located on the outermost side in the tire width direction among the small blocks formed in the shoulder region.

  Accordingly, it is an object of the present invention to solve the above-mentioned problems, and even if a small block is arranged in the shoulder region in order to improve the rolling resistance more effectively, the shoulder drop wear Another object of the present invention is to provide a pneumatic tire that can suppress step down wear.

In order to achieve the above object, this pneumatic tire is
Provided within the tread contact width is a small block group in which a plurality of small blocks partitioned by grooves are arranged in a plurality of columns and a plurality of rows, and across the tread contact end on the outer side in the tire width direction of the small blocks. In a pneumatic tire provided with a buttress block row consisting of extending buttress blocks,
Both regions outside the position corresponding to 80% of the tread contact width with respect to the tire equatorial plane as a shoulder region are shoulder regions, and at least a part of the small blocks constituting the small block group in the shoulder region. And place
The columns are arranged so that the small blocks constituting the adjacent columns have different phases in the tire circumferential direction,
In the shoulder region, a reference pitch length of the small block group is PL (mm), a width of the small block group is SAW (mm), and the small blocks are divided by the reference pitch length PL and the width SAW. When the number of the small blocks existing in the reference area of the group is a (pieces) and the negative rate in the reference area is N (%),
a / (PL × SAW × (1-N / 100))
The block number density S per unit actual contact area of the small block group given by is in the range of 0.003 / mm ² or more and 0.04 / mm ² or less,
The buttress block includes a first coupling portion extending in the tire width direction toward at least one first small block adjacent to the inside of the buttress block in the tire width direction;
The first small block including the first connecting portion extends in the tire width direction toward at least one second small block adjacent to the inner side in the tire width direction of the first small block. It is a pneumatic tire provided with the following connection part.

  Here, the “tread contact width” is an industrial standard effective in an area where tires are produced or used, for example, The Tire and Rim Association Inc. in the United States. Assembling the tires to the standard rims of the standard sizes described in “Year Book” in Europe, “Standard Manual” of The European Tire and Rim Technical Organization in Japan, and “JATMA Year Book” of Japan Automobile Association in Japan, This refers to the maximum width of the surface where the tire surface comes into contact with the ground in the state where the maximum load (maximum load capacity) of the single wheel in the applicable size and the air pressure corresponding to the maximum load are applied. The “tread contact end” means the outermost point of the tread contact width in the tire width direction.

  Further, the “column” referred to here means a column made up of small blocks arranged at a predetermined interval in the circumferential direction. Multiple columns are arranged in the tire width direction. And “so that the phase in the tire circumferential direction is different” means that on the tread surface, a plurality of small blocks of the same shape constituting the column are mutually in the circumferential direction with each of the small blocks constituting the adjacent column. It refers to the state of staggered arrangement.

  The “reference pitch length of the small block group” refers to the minimum unit of the repeating pattern of the small blocks in one column constituting the small block group. For example, the small block group includes a groove that divides the small block. If a pattern repeat pattern is specified, the sum of the tire circumferential length of one small block and the tire circumferential length of one groove adjacent to the tire circumferential direction of this small block is The reference pitch length of the block.

  The “small block group width SAW” refers to the total length of the small block group in the tire width direction in the shoulder side region.

  The “actual ground contact area” of the small block group refers to the total surface area of all small blocks in the reference area of the small block group, and is defined by, for example, the product of the reference pitch length PL and the width SAW. , Refers to the area obtained by subtracting the area of the groove defining each small block from the area of the reference area.

  Further, the small block “adjacent to the inside of the tire width direction of the buttress block” means that at least a part of the small blocks constituting the outermost column in the tire width direction is on the same straight line in the tire width direction as the buttress block. Say the small block located at.

  Similarly, “at least one second small block adjacent to the inner side in the tire width direction of the first small block” means at least a block among the small blocks constituting the second row from the outermost side in the tire width direction. A part refers to the small block provided on the same straight line in the tire width direction as the small block including the first connecting portion.

Moreover, it is preferable that the average heights of the first and second connecting portions are each 1/3 or more and 9/10 or less of the height of the buttress block.
The height of the connecting portion extending in the tire width direction may not be a constant height in the extending direction, as will be described later. Therefore, the “average height” of the connecting portion referred to here means an average value of different heights of the entire connecting portion when the connecting portion extends at different heights.

  Moreover, in the pneumatic tire of the said invention, the centroid of the said 1st connection part and the centroid of the said 2nd connection part may extend on the same straight line extended along a tire width direction. preferable.

  In the pneumatic tire of the above invention, an angle formed by a straight line connecting the centroid of the first small block and the centroid of the first connecting portion with the equator plane, and the second small block It is preferable that the angle formed by the straight line connecting the centroid of the second linking center and the centroid of the second connecting portion is the same as the equator plane.

  Furthermore, in the pneumatic tire according to the invention described above, it is preferable that the first and second connecting portions periodically exist in the tire circumferential direction.

  Here, the fact that the connecting portions periodically exist in the circumferential direction means a state in which the connecting portions are formed at predetermined intervals in the circumferential direction. Therefore, it is not necessary for all of the buttress blocks and the small blocks constituting the outermost row in the tire width direction and the second column from the outermost side to have a connecting portion, but there are buttress blocks and small blocks having no connecting portion. Also good.

  The shape of the surface contour of the small block is preferably a polygonal shape.

  According to the present invention, even in the case where a small block is arranged in the shoulder region in order to improve rolling resistance more effectively, in particular, the shear in the tire width direction of the small block located in the outermost row in the tire width direction. Since deformation can be reduced, it is possible to provide a pneumatic tire capable of suppressing shoulder wear and step-down wear.

Fig.1 (a) is the partial expanded view which showed the tread pattern of one Embodiment of the pneumatic tire by this invention, FIG.1 (b) is the figure which expanded a part of Fig.1 (a). . It is sectional drawing of the tire width direction of one Embodiment of the pneumatic tire by this invention. It is the partial expanded view which showed the tread pattern of other embodiment of the pneumatic tire by this invention. FIG. 6 is a partial development view showing a tread pattern of still another embodiment of the pneumatic tire according to the present invention. Fig.5 (a) is the figure which expanded the tread pattern of the pneumatic tire shown to Fig.1 (a), Furthermore, FIG.5 (b) is the figure which expanded a part of Fig.5 (a). It is sectional drawing of the tire width direction of one Embodiment of the pneumatic tire by this invention, Comprising: It is a figure for demonstrating a deformation | transformation of a tread part. Fig.7 (a) is the figure which expanded the tread pattern of one Embodiment of the pneumatic tire by this invention, FIG.7 (b) cut | disconnected along line AA 'of Fig.7 (a). It is an arrow view. FIG. 6 is a partial development view showing a tread pattern of still another embodiment of the pneumatic tire according to the present invention. FIG. 9 (a) is a partial development view showing a tread pattern of still another embodiment of the pneumatic tire according to the present invention, and FIG. 9 (b) is an enlarged view of a part of FIG. 9 (a). It is. FIG. 6 is a partial development view showing a tread pattern of still another embodiment of the pneumatic tire according to the present invention. FIG. 6 is a partial development view showing a tread pattern of still another embodiment of the pneumatic tire according to the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a partial development view showing a tread pattern of a pneumatic tire 1 (hereinafter referred to as a tire) according to an embodiment of the present invention. In the drawing, the vertical direction indicates the tire circumferential direction (direction parallel to the equator plane C), and the left-right direction indicates the tire width direction (direction orthogonal to the equator plane C).

  FIG. 2 is a cross-sectional view of the tire 1 of this embodiment in the tire width direction. As shown in FIG. 2, the tire 1 includes a tread portion 21 that forms a tread surface of the tire, and a pair of sidewall portions 20 and 20 that are connected to both ends in the width direction of the tread portion 21 via shoulder regions. Further, a carcass 8 extending in a toroidal shape between a pair of left and right bead portions 7, 7 located on the opposite side of the pair of sidewall portions 20, 20 from the shoulder region side, and a tire of a crown portion of the carcass 8 It is a tire having a tire structure according to a custom, including a belt layer 9 disposed on the radially outer side.

As shown in FIG. 1A, when the length between the tread grounding ends 2 and 2 (tread grounding width) of the tire 1 is TW, at least the tread grounding width is symmetrical with respect to the equator plane C. A plurality of small areas defined by a groove 3a and a groove 3a in a region from the outer side in the tire width direction to the ground contact edge 2 than the range W of 80% of TW (hereinafter, this region is referred to as a shoulder region SA in the present invention). It has a small block group SGb in which the blocks 4 are densely packed together.
Here, the groove 3a refers to a space in the circumferential direction formed by the small blocks constituting the column, and the groove 3b refers to a groove that intersects the groove 3a. These grooves have such a width that adjacent small blocks are not completely constrained to each other and can be individually moved, and preferably have a width of 0.7 mm to 3 mm.

  In FIG. 1A, the small block 4 is illustrated so as to be disposed over the entire contact width TW. However, the small block 4 is at least the outer side in the tire width direction of the range W (that is, the shoulder region SA). ) And the inner side in the tire width direction from the tread grounding end 2. Therefore, as shown in FIG. 3, for example, a small block 4 is provided in the shoulder region SA, and a tread pattern in which a main groove is provided in a tread portion on the inner side in the tire width direction can be obtained. In addition, although not shown here, for example, a small block 4 is provided at least in the shoulder region SA, and a tread portion on the inner side in the tire width direction is provided with a rib or a block pattern partitioned by main grooves, lateral grooves, sipes, and the like. It can also be provided.

The surface contour shape of the small block 4 is preferably a polygonal shape. This is because a sufficient contact area on the tire surface can be ensured by adopting this shape. Moreover, it is because it can mutually support the fall of a block between adjacent blocks, making each small block independently movable.
Furthermore, the surface contour shape is preferably a regular octagon as shown in FIGS. 1 (a) and 1 (b), for example. This is because if the number of corners is too small, the block cannot fall down in many directions and the flexibility is poor. In addition, if the polygon is an octagon or more, one side becomes too short, and the surface in contact with the adjacent block when falling down becomes small, making it difficult to support each other. Therefore, by making the surface contour shape a regular octagon, the block falls down in multiple directions and can sufficiently support the adjacent blocks. In addition, when the surface contour shape is a regular octagon, it is preferable that the groove | channel 3a which divides | segments a small block has circumferential direction distance to such an extent that a groove | channel does not block | close between adjacent blocks at the time of grounding. On the other hand, the groove 3b intersecting with the groove 3a (groove inclined with respect to the equator plane) is preferably formed such that adjacent blocks are close to each other to such an extent that the groove is closed at the time of ground contact.
However, the surface contour shape of the small block of the present invention is not necessarily limited to the above shape. In this way, the grooves are partitioned and the individual small blocks are freely independent so that they can have flexibility when grounded without being constrained by the adjacent small blocks (or buttress blocks described later). As long as it can move.

The surface area of the small block 4 is preferably 100 mm ² or more and 1200 mm ² or less.
By subdividing the block so that the ground contact area is in this range, the shear strain on the tread surface can be reduced and the bulging deformation of the block can be reduced. As a result, each block can be moved within an appropriate range so as to be flexible with respect to an impact from the road surface, while shearing of the block can be suppressed.
The reason why the contact area is within this range is that if the area is smaller than 100 mm ² , the contact area of each block is too small to withstand the impact from the road surface, and shearing tends to occur. Further, if it is larger than 1200 mm ² , the surface area of the block becomes too large and the flexibility of the individual blocks is lost.

  As shown in FIGS. 1 (a) and 1 (b), a plurality of columns in which the small blocks 4 are arranged at predetermined intervals in the circumferential direction are arranged in the width direction on the tire surface to form adjacent columns. The small blocks 4 to be arranged are arranged so as to have different phases in the tire circumferential direction. That is, the small blocks 4 are arranged in a staggered manner (staggered lattice shape) in the tire circumferential direction.

  Here, the phase being different in the tire circumferential direction means a state where centroids of adjacent small blocks forming adjacent columns are not located on the same straight line in the tire width direction. For example, in the example shown in FIG. 1 (a), the centroids of the small blocks 4 forming the outermost column in the tire width direction and the second column from the outermost side adjacent to the column are half blocks. The tires are shifted in the tire circumferential direction. Therefore, in this case, when attention is paid to the plurality of small blocks arranged on the tread surface in the tire width direction, the small blocks forming the columns for every other row (every other row) have the same phase in the tire width direction (that is, (The centroids are located on the same straight line).

  However, the positions of the columns having different phases in the tire circumferential direction are not necessarily different from each other by half of the blocks as described above. Therefore, although not shown, the small blocks having the same phase may not necessarily form columns for every other column, but may form columns every other column.

As described above, small blocks with a polygonal shape and small surface area are arranged on the tread surface, so that each block has flexibility and improved grounding performance for each block. And rolling resistance can be reduced.
The above effect is particularly remarkable in the shoulder region where the shear deformation of the block is most likely to occur. This is because by providing such a relatively small small block on the shoulder side, the tread portion in the vicinity of both end portions of the belt layer 9 that is dominant in rolling resistance can be subdivided (that is, the tread portion in the vicinity of the belt end). This is because the energy loss of the tread portion at the time of tire load rolling can be significantly reduced.

In addition, since the small blocks 4 are arranged in a zigzag pattern in the tire circumferential direction as described above, it is possible to exert an excellent edge effect by sequentially causing the edges of the respective small blocks to act during tire rolling. it can.
Moreover, since the contact timing to the road surface can be shifted between the small blocks 4 adjacent in the tire width direction, pattern noise can also be reduced.

  The tire 1 further has a buttress block row BGb on the tire surface from the ground contact end 2 on the outer side in the tire width direction (that is, on the outer side in the tire width direction of the ground contact width TW). This buttress block row BGb is configured by arranging a plurality of buttress blocks 6 extending in the tire circumferential direction from the tread grounding end to the widthwise outer side across the tread grounding end from the tire width direction inside.

  1 (a) and 1 (b), the tire circumferential direction length of the buttress block 6 is the same as the tire circumferential direction length of the small block 4, and the small blocks in the second row from the outermost side in the tire width direction are shown. Although the centroid of the buttress block 6 is located on a straight line drawn from the centroid of 4 outward in the width direction, the centroid is not necessarily limited to this embodiment. For example, as shown in FIG. 4, the buttress block 6 has two rows of small blocks arranged in the circumferential width of one row of buttress blocks (two small blocks are the circumferential distance of one buttress block). It may be formed as follows.

Further, in the tire 1, in the small block group SGb in the shoulder region SA, the reference pitch length of the small block 4 is PL (mm), the width of the small block group SGb is SAW (mm), and the reference pitch length. The number of small blocks 4 existing in the reference area Z (shaded area in FIG. 5A) of the small block group SGb divided by the length PL and the width SAW is a (number), and within the reference area Z When the negative rate of N is N (%)
a / (PL × SAW × (1-N / 100))
The block number density S per unit actual ground contact area of the small block group SGb is in the range of 0.003 / mm ² or more and 0.04 / mm ² or less.

  When counting the number of blocks a in the reference zone Z, if the block exists across the reference zone Z and cannot be counted as one, it is within the reference zone with respect to the surface area of the block. It is counted using the ratio of the remaining area of the remaining blocks. For example, in the case of a block straddling the inside and outside of the reference area Z and only half of the block exists in the reference area Z, it can be counted as 1/2.

  In the above formula, the “reference pitch length” refers to the smallest unit of the repeated pattern of small blocks in one block column constituting the small block group SGb. For example, one small block 4 is represented by the small block. When the pattern repeat pattern is defined by the grooves 3a and 3b that divide 4, the tire circumferential direction length of one small block and the tire circumferential direction of one groove 3a adjacent to the tire circumferential direction of this small block The reference pitch length is obtained by adding the length.

Further, “the width SAW in the tire width direction of the shoulder region SA” refers to the total length in the tire width direction of the small block group SGb in the small size of the small blocks 4 existing in the shoulder region SA. That is, when the length in the tire width direction of the small block group in each of the shoulder regions SA located on both outer sides in the tire width direction is SA1 and SA2, the width SAW is the total width of SA1 + SA2. Means.
For example, in this embodiment shown in FIG. 5A, the small block 4 and the buttress are arranged in the region SA from the outer side in the tire width direction to the ground contact edge 2 with respect to the equatorial plane C, rather than the range W of 80% of the tread ground contact width TW. The end of the block 6 is arranged. Accordingly, the tire width direction length SA1 of the small block group existing in the shoulder region SA on one side is the tire width direction length SA1 of the shoulder region SA of the buttress block 6 existing on the inner side in the tire width direction from the ground contact edge 2. The tire width direction length is subtracted. If the tread surface of the tire is symmetrical with respect to the equator plane C, the same applies to SA2, and therefore the width SAW in the tire width direction of the shoulder region SA in the embodiment of FIGS. 5 (a) and 5 (b). Means SA1 * 2.

  The “actual ground contact area” of the small block group SGb refers to the total surface area of all the small blocks in the reference area of the small block group SGb. For example, the reference pitch length PL and the width SAW of the shoulder region SA Can be obtained from the area obtained by subtracting the areas of the grooves 3a and 3b partitioning the individual small blocks 4 from the area of the reference area defined by the product of

  As described above, since the small blocks 4 are densely arranged while securing a sufficient groove area in the small block group SGb, the total edge length and edge direction components (different directions) of the small blocks 4 are adopted. The number of edges facing the surface can be increased, and an excellent edge effect can be exhibited. Further, since the size of the small block 4 is reduced and the sipe is not formed, the grounding property of each small block can be improved and high wet performance can be exhibited. Furthermore, by reducing the size of each small block 4, the distance from the central region of the small block 4 to the peripheral edge of the block can be reduced, so that the water film removal effect by the small block 4 can be improved.

Further, the negative rate N in the small block group SGb is preferably 5% to 50%. When the negative rate N in the small block group SGb is less than 5%, the groove area is too small and the drainage is insufficient, and the size of each block is too large, making it difficult to achieve the required edge effect. Because it becomes. On the other hand, if it exceeds 50%, the ground contact area becomes too small and the steering stability may be lowered. Further, when the number density S of the small blocks 4 in the small block group SGb is less than 0.003 (pieces / mm ² ), it is difficult to realize a high edge effect without forming a sipe. When the number density S exceeds 0.04 (pieces / mm ² ), the small block 4 becomes too small and it is difficult to achieve the required block rigidity.

  However, if the small block 4 is formed only on the tread surface, the small block 4 located in the shoulder region cannot withstand the shearing force due to the load received from the rim 5 that is repeated many times. May occur. And this time, the applicant has found that among the small blocks located in the shoulder region, in particular, the small blocks constituting the outermost column in the tire width direction in the ground contact region are most susceptible to shear deformation.

  Here, a mechanism in which the tread portion receives a force transmitted from the bead portion when a load is applied to the tire 1 will be described with reference to FIG. First, in the tire 1 having the structure shown in FIG. 2, when a load is applied to the tire 1 installed on the rim 5, the bead portion 7 to the sidewall portion 20, the buttress portion, the shoulder region direction perpendicular to the tread surface A load is applied to the heel (FIG. 6A). This vertical force is transmitted as stress to the tread portion 21 substantially inward in the tire width direction through the shoulder region. When this stress is transmitted, the tread portion 21 receives a force on the inner side in the width direction as shown in FIG. 6B, so that shear deformation occurs in the small block 4 near the road surface (that is, the small block 4 in the shoulder region). As a result, the deformation of the tread portion 21 when a load is applied to the tire 1 is as shown in FIG.

  Thus, although the small blocks located in the shoulder region are likely to undergo shear deformation in the width direction, among these small blocks, the small block located in the outermost column in the tire width direction of the ground contact surface is the outermost of the ground contact end 2. Because it is located nearby, it is directly stressed. Therefore, the small blocks located in the outermost column in the tire width direction are particularly susceptible to deformation due to stress.

Furthermore, a lateral force in the tire width direction is applied particularly to the small blocks located in the shoulder region of the tread surface not only when the load is applied but also during cornering. And since the small block which comprises the outermost column is arrange | positioned in the position nearest from a grounding end, it is most easy to produce a deformation | transformation also by the presence or absence of the grounding of the tread surface at the time of this cornering.
In addition, there is a groove between the outermost small column in the column and the small inner block in the tire width direction adjacent thereto (that is, the small block constituting the second column from the outermost side). Even when the outermost small block in the outermost column that has received a force falls down, it is difficult to sufficiently transmit the lateral force to the small blocks that form the second column from the adjacent outermost column.

  As described above, when the small blocks 4 are formed on the tire surface, among the small blocks located in the shoulder region, the small blocks constituting the outermost column in the tire width direction are most likely to undergo shear deformation. As a result of the repetition of the deformation, there is a problem that shoulder wear is generated.

In order to solve the above problem, in the tire 1 of the present invention, the first connection in which the buttress block extends in the tire width direction toward the first small block adjacent to the inside of the buttress block in the tire width direction. The first small block including the first connecting portion extends in the tire width direction toward the second small block adjacent to the inner side in the tire width direction of the first small block. It is characterized by providing the connection part.
According to this characteristic configuration, stress (lateral force) applied to the small blocks located in the outermost column in the tire width direction can be efficiently transmitted to other small blocks. The stress applied only to the small blocks in the column is dispersed, and shear deformation can be suppressed as compared with the conventional case.

  Below, the tire provided with the 1st and 2nd connection part which is the characteristic structure of this invention is demonstrated based on various forms.

  FIG. 7 is a view showing an embodiment of a tire according to the present invention. As shown in FIG. 7A, the connecting portion 10 is at least between the buttress block row BGb and the outermost row L1 in the tire width direction, and the second row from the outermost row L1 and the outermost row. Between the two columns L2. And, for example, the connecting portion 10a between the buttress block 6a and the small block 4a in the outermost column L1, the small block 4a in the outermost column L1, and the small block 4b in the second column L2 from the outermost column By the two connecting portions with the connecting portion 10b therebetween, the small block in the second column L2, the small block in the outermost column L1, and the buttress block in the buttress block row BGb are all connected in the tire width direction. Is done.

  In this way, by connecting the small blocks in the second row from the outermost side in the tire width direction, the small blocks in the outermost row, and the buttress block in the tire width direction, the force from the buttress block toward the ground contact end causes the tire to It is possible to suppress the deformation of the small blocks located in the outermost row in the width direction as compared with the conventional case. The three blocks of the small block in the second row from the outermost side in the tire width direction, the small block in the outermost row, and the buttress block are all connected by the connecting portion, so that the force transmitted from the buttress block is the outermost Since it is transmitted efficiently to the small blocks in the second row, the force that was received by itself in the small blocks in the outermost column in the tire width direction can be distributed to other blocks. is there.

Further, according to the present invention, since it is configured to connect from the buttress block to the small column in the second column from the outermost side in the tire width direction, the small block constituting the vertical column for two columns from the outermost in the tire width direction Thus, the force can be sufficiently absorbed in the shoulder region, and the force applied to the inner side in the width direction can be effectively suppressed.
This is because the small blocks constituting the second column from the outermost row in the tire width direction are arranged on the inner side in the width direction than the outermost row, so that the curvature at the time of contact is smaller than that in the outermost row. In other words, the small blocks in the second row from the outermost side can more firmly contact the road surface when the tire contacts the ground. Therefore, not only the outermost small blocks but also the outermost small blocks can be connected to the buttress block via the connecting part to increase the rigidity of the entire block receiving the force from the buttress block. This is because the force applied in the width direction can be sufficiently absorbed as a result.

  For the sake of explanation, in FIG. 7A, connecting portions are provided between the buttress block row and the outermost row in the tire width direction, and between the outermost row and the second row from the outermost row. Although the example of a structure to provide was shown, you may provide a connection part so that it may exist over the whole width direction. That is, in the tire according to the present invention, it is only necessary that the connecting portions are formed in at least two rows on the inner side in the tire width direction from the tire ground contact end. In this way, if the block (buttress block) on the outer side in the width direction from the tire ground contact edge is connected to two columns from the outermost side in the width direction, only the small block located in the outermost row in the width direction will be subjected to the force in the width direction. It is because it can suppress that it receives and deform | transforms conventionally.

7 (b) is an arrow view of the small block of FIG. 7 (a) cut along the line AA ′. The average height H of the connecting portion in the tire radial direction is the buttress block or It is 1/3 or more and 9/10 or less of the tire radial direction height of a small block, Preferably, it is 1/2 of the tire radial direction height of a buttress block or a small block. Accordingly, the surface contours of the small block and buttress block remain on the tire surface.
Here, as shown in FIG. 7B, the height of the connecting portion extending from the buttress block toward the small block (or from the small block to the small block) may be different within the connecting portion. Therefore, the average height H of the connecting portion means a value obtained by averaging the different heights when the height of the connecting portion extending between the blocks is different in the connecting portion. That is, it means a value obtained by dividing the area of the connecting portion in the tire cross section by the length in the tire width direction of the connecting portion.

  Thus, if the height of the connecting portion in the tire radial direction is made lower than the height of the buttress block or the small block, the groove between the blocks will not be completely blocked. That is, wet performance can be maintained, and each block can be individually grounded while remaining in an independent state. Thereby, even if it has a connection part which connects blocks and transmits the force concerning the width direction, the above-mentioned effect which a small block has can be fully exhibited.

The average height H in the tire radial direction of the connecting portion is set to 1/3 or more of the tire radial direction height of the buttress block. If the height is less than this, the connecting portion can withstand excessive lateral force. This is because there is a possibility of collapsing, and the force cannot be sufficiently transmitted between the blocks. Moreover, it is because a connection part cannot support the deformation | transformation of a block and a fall of a block may arise.
In addition, if the height is 9/10 or less, the height of the connecting portion and the height of the block become substantially the same height, and the groove between the blocks is blocked by the connecting portion in the tire width direction. Because it will be. That is, the groove provided in the circumferential direction is blocked by the connecting portion, and the drainage performance is deteriorated.
Therefore, if the average height in the tire radial direction of the connecting portion is ½ of the height in the tire radial direction of the block, the connecting portion will not collapse or the block will collapse, and good drainage will be maintained. Therefore, the force applied in the width direction can be absorbed by the entire small block located in the shoulder region, and the shear deformation of the block can be suppressed as compared with the conventional case.

  Further, when the height of the extending connecting portion is not uniform and is different, for example, as shown in FIG. 7B, it is preferable to form the connecting portion so that the center portion is the lowest. That is, it is preferable to form the connecting portion so that the portion closer to the block has a higher height and gradually decreases toward the center in the tire width direction of the connecting portion. By adopting this shape, the connection between the connecting portion and each block can be strengthened, and the force applied in the width direction can be effectively transmitted from the block to the block. And since the height of the center part of a connection part is low, it is because drainage can also be ensured.

Also, here, the connecting portion extending in the tire width direction needs to transmit the force received from the outside in the width direction to the small block on the inner side in the width direction. It is preferable that the boundary portion is configured to be widest in the tire circumferential direction. That is, it is preferable that the tire circumferential direction length in the boundary portion is equal to or greater than the tire circumferential direction length in the tire width direction central portion of the connecting portion. Thus, if the tire circumferential length along the block of the connecting portion is long enough to transmit the force from the buttress block to the small block, the connecting portion has a different circumferential length. You may have.
Specifically, the length of the connecting portion in the tire circumferential direction is 1 mm or more and less than 3 mm. The reason why the length is shorter than 3 mm is that if it is longer than this, it will be in contact with an adjacent block. The reason why it is set to 1 mm or longer is that if the length in the tire circumferential direction of the connecting portion is too short, this time. This is because the connecting portion may not exhibit a predetermined effect during stress transmission.

  In addition, what is necessary is just to form a connection part by a normal method using a metal mold | die etc. so that it may have the said shape at the time of vulcanization | cure in a tire shaping | molding process. Therefore, in the present specification, for the sake of explanation, the connecting portion and the block are described separately, but it should be noted that the connecting portion can be formed integrally with the block.

  FIG. 8 is a view showing another embodiment of a tire according to the present invention. In the example shown in FIG. 8, the connection part 10 is arrange | positioned so that the centroids of a connection part may be located on the same straight line in a tire width direction. That is, in FIG. 8 which is a partial development view of the tread pattern, when the upper side toward the paper surface is the upper side of the tread pattern, the outermost small block 4c in the tire width direction has the connecting portion 10c in the groove in the upper width direction. In the case of providing, the small block 4d connected to the small block 4c by the connecting portion 10c is now provided with the connecting portion 10d in the lower inner groove in the tire width direction.

  In this way, if the connecting part is provided along the tire width direction and the blocks are connected, the block rigidity in the shoulder area when the tire turns during rolling effectively increases the overall steering stability. Can be made.

  In addition, you may arrange | position the connection part shown in FIG. That is, the outermost small block 4c in the tire width direction is provided with a connecting portion in the groove on the lower width direction inner side, and the small block 4d adjacent to the small block 4c on the inner side in the width direction is now positioned on the inner side in the upper width direction. You may make it provide a connection part in a groove | channel.

  FIG. 9 is a view showing still another embodiment of the tire according to the present invention. In the example shown in FIG. 9 (a), the connecting portion 10 is such that the angle formed by the centroid of the small block having the connecting portion and the straight line connecting the centroids of the connecting portion and the equator plane is the same constant angle. Placed in.

  Specifically, FIG. 9B is an enlarged view of a part of FIG. 9A, which is a partial development view of a tread pattern in which a connecting portion exists over the entire tire width direction. In b), the angle between the straight line EE ′ connecting the centroid of the small block 4e and the centroid of the connecting portion 10e and the circumferential axis passing through the centroid of the small block 4e is x, and further in the tire width direction When the angle between the straight line FF ′ connecting the centroid of the outer small block 4f and the centroid of the connecting portion 10f and the circumferential axis passing through the centroid of the small block 4f is y, x and the angle y are equal and have a predetermined angle. When the connecting portion is arranged in this manner, the connecting portion is arranged obliquely from the equator plane toward the outer side in the tire width direction as shown in FIG. 9A.

  If the connecting portion is disposed obliquely as described above, the timing at which the block having the connecting portion contacts the ground during running is shifted. Thereby, pattern noise can be reduced compared with the case where a connection part is arrange | positioned in a straight line like the width direction like FIG. 8, and a vehicle interior sound can be reduced. Since the height of the connecting portion in the tire radial direction is lower than the block portion as described above, the effect is small when new, but when the wear progresses and the connecting portion comes into contact with the road surface, the connecting portion is in a straight line. Compared to the case of FIG. 8, the overall noise generation can be reduced.

Moreover, the tire having the tread pattern in FIG. 9A may be a tire having a designated rotation direction that rotates in the direction of the arrow shown in FIG. In this case, for example, the direction of rotation can be indicated by imprinting an arrow indicating the direction of rotation on the tire surface.
When the tire is rotated in the direction of the arrow in FIG. 9A, the small block on the equatorial plane comes first to ground among the buttress blocks and the small blocks connected by the connecting portion, and the tire width is sequentially determined thereafter. Each small block is grounded toward the outside in the direction.

Even in this case, by arranging the connecting portions obliquely as described above, the deformation of the small blocks can be averaged, and the shoulder drop wear and the step-down wear can be effectively suppressed.
This is because, for example, in the small blocks 4e and 4f having the connecting portion 10f in FIG. 9B, the small block 4e has a connecting portion on the stepping-out side and the small block 4f has a connecting portion on the kicking-out side. Here, since the deformation of the small block is larger than the deformation to the kicking side, the deformation on the kicking side is effective by connecting both sides with different deformation amounts by connecting parts. This is because it can be suppressed.

  Furthermore, when the connecting portion is arranged obliquely and the tire is rotated in the direction of the arrow in FIG. 9A, each small block having a connecting portion that is connected obliquely toward the outer side in the width direction is a groove on the kick-out side. And both the grooves on the outer side in the width direction can be secured. In other words, the connecting portion has a certain height although the height in the tire radial direction is lower than that of the block, and therefore, at the groove portion where the connecting portion is provided, the connecting portion may become a barrier and hinder drainage. There is. However, if the tire rotates in the direction of the arrow shown in FIG. 9 (a), the connecting portion can be formed in a state in which the groove is secured without hindering drainage, so that good drainage is also sufficiently maintained. At the same time, the above-described effects can be obtained.

  FIG. 10 is a view showing still another embodiment of the tire according to the present invention. In the example shown in FIG. 10, the connecting portion 10 is arranged obliquely in the same manner as the example in FIG. 9, but is arranged so as to be asymmetric with respect to the equator plane. As described above, the tire according to the present invention may be a mounting direction specifying tire that specifies the direction of the tire at the time of mounting by, for example, the direction stamped on the tire surface. By arranging the connecting portions in this way, the pattern noise can be reduced by shifting the grounding timing of the block having the connecting portions as in the example shown in FIG.

Furthermore, as shown in FIG. 11, the connection part 10 may arrange | position combining the case where it arrange | positions on the same straight line, and the case where it arrange | positions diagonally.
When the connecting portion is arranged in this way, two connecting portions can be provided between the buttress block and the small block in the outermost row in the tire width direction, so that the force from the buttress block is evenly applied to the inner small block. It is possible to communicate. The force from the buttress block is transmitted from the small block to the inner small block via the connecting portion.

  However, in any of the above-described embodiments, it is not necessary to provide the connecting portion in every block. For example, as shown in FIG. 9, the connecting portions can be provided periodically at predetermined intervals in the tire circumferential direction.

  Further, the shape and arrangement of the connecting portion described above, the shape and arrangement of the small block and buttress block are all examples for explaining the present invention, and these are within the scope of the present invention. The shape and arrangement can be changed as appropriate.

  According to the present invention, even when a small block is arranged in the shoulder region, the tire is particularly susceptible to deformation by transmitting force to the small block located in the second column from the outermost side in the tire width direction. It was possible to suppress the shear deformation in the width direction of the small blocks located in the outermost column in the width direction, and to suppress shoulder drop wear and step-down wear.

1 Tire 2 Grounding end
3 groove 4 small block 5 rim 6 buttress block 7 bead portion 8 carcass 9 belt layer 10 connecting portion SGb small block group BGb buttress block row SA shoulder region

Claims (7)

Provided within the tread contact width is a small block group in which a plurality of small blocks partitioned by grooves are arranged in a plurality of columns and a plurality of rows, and across the tread contact end on the outer side in the tire width direction of the small blocks. In a pneumatic tire provided with a buttress block row consisting of extending buttress blocks,
Both regions outside the position corresponding to 80% of the tread contact width with respect to the tire equatorial plane as a shoulder region are shoulder regions, and at least a part of the small blocks constituting the small block group in the shoulder region. And place
The columns are arranged so that the small blocks constituting the adjacent columns have different phases in the tire circumferential direction,
In the shoulder region, a reference pitch length of the small block group is PL (mm), a width of the small block group is SAW (mm), and the small blocks are divided by the reference pitch length PL and the width SAW. A / (PL × SAW × (1−N / 100)) where a is the number of the small blocks existing in the reference area of the group and N is the negative rate in the reference area. The block number density S per unit actual contact area of the small block group given by is in the range of 0.003 / mm ² or more and 0.04 / mm ² or less,
The buttress block includes a first coupling portion extending in the tire width direction toward at least one first small block adjacent to the inside of the buttress block in the tire width direction;
The first small block including the first connecting portion extends in the tire width direction toward at least one second small block adjacent to the inner side in the tire width direction of the first small block. A pneumatic tire comprising a connecting portion. The said 1st and 2nd connection part is formed so that height may become high in the location close | similar to a block, and it may reduce gradually toward the tire width direction center of this connection part, It is characterized by the above-mentioned. The described pneumatic tire. 3. The pneumatic according to claim 1, wherein an average height of the first and second connecting portions is 1/3 to 9/10 of a height of the buttress block. 4. tire. The first centroid of the centroid and the second connecting portion of the connecting portion, characterized in that extending on the same straight line extending along the tire width direction, one of the claims 1 to 3 one The pneumatic tire according to item . The angle formed by the straight line connecting the centroid of the first small block and the centroid of the first connecting portion with the equator plane, the centroid of the second small block and the centroid of the second connecting portion wherein the straight line connecting the door is the same and the angle formed by the equatorial plane, the pneumatic tire according to any one of claims 1-4. The pneumatic tire according to any one of claims 1 to 5 , wherein the first and second connecting portions periodically exist in a tire circumferential direction. The shape of the surface contour of the small block is characterized by a polygonal shape, the pneumatic tire according to any one of claims 1-6.

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