pneumatic tires

Abstract

To provide a pneumatic tire that can make both an improvement in travelling performance on an unpaved road of a vehicle and a reduction in air resistance in the vehicle compatible.SOLUTION: A tire 1 as one example of embodiments includes a plurality of protruding parts 50 protruding to the outside in a tire width direction with an interval in a tire circumferential direction, on a side surface 41 at an outside diameter-side of the tire which is on the outside in a tire width direction of a grounding end and on the outside in a tire radial direction of the maximum width position of the tire. The maximum height in the tire width direction of the protruding parts 50 is above 5 mm. In each protruding part 50, a first side surface 51 positioned at a rearmost end on a rear side surface in a main rotating direction of the tire and a second side surface 53 positioned at a frontmost end on a front side surface in the main rotating direction of the tire are inclined with respect to the tire radial direction, at a rear side in the tire main rotating direction α, from the inside toward the outside in the tire radial direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a protrusion that protrudes outward in the tire width direction on an outer diameter side surface of the tire. [Background technology]

[0002] Conventionally, pneumatic tires have been known that have multiple protrusions on the sidewalls of the tire that extend intersectingly in the tire circumferential and radial directions (see Patent Document 1). In the configuration described in Patent Document 1, the middle portion of the protrusions in the extension direction includes the maximum point of their protrusion height from the tire side surface, and this maximum point is located within a range of 20% of the tire cross-sectional height inward and outward in the tire radial direction from the maximum tire width position. This is said to aim to reduce air resistance on the vehicle by turbulent air flow in the tire sidewalls and to reduce air passing noise on the sidewalls of the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 008726 Summary of the Invention [Problem to be solved by the invention]

[0004] The pneumatic tire of Patent Document 1 has multiple protrusions on the tire sidewall that are inclined relative to the tire radial direction, which may reduce air resistance on a vehicle. However, this tire does not have a structure that can improve vehicle driving performance on rough terrain. To improve driving performance, it is conceivable to provide multiple high protrusions in the tire width direction as a raised structure in a region called the buttress, which is the tire's surface widthwise outer side of the tire's contact edge and radially outer than the tire's maximum width position. However, simply providing protrusions on the buttress may increase the vehicle's air resistance. For this reason, it is desirable to realize a pneumatic tire that can simultaneously improve vehicle driving performance on rough terrain and reduce air resistance on the vehicle.

[0005] An object of the present invention is to provide a pneumatic tire that can improve the running performance of a vehicle on rough ground and reduce air resistance on the vehicle at the same time. [Means for solving the problem]

[0006] The pneumatic tire of the present invention is a pneumatic tire having a surface on the tire widthwise outer side surface of the tire radially outer than the ground contact edge, the surface being spaced apart in the tire circumferential direction and protruding outward in the tire width direction, the surface being on the tire outer diameter side surface radially outer than the tire maximum width position, the maximum height in the tire width direction of each of the plurality of protrusions being 5 mm or more, and the first side surface located at the rearmost end of the rear side surface in the main rotation direction of the tire and the second side surface located at the frontmost end of the front side surface in the main rotation direction of the tire being inclined with respect to the tire radial direction, from the inner side in the tire radial direction to the outer side, toward the rear side in the main rotation direction of the tire.

[0007] With the pneumatic tire described above, when the vehicle is running, the multiple protrusions provided on the outer diameter side surface of the tire rotate with the rotation of the tire, causing the air around the tire to become turbulent with many fine vortices. This improves airflow stagnation that occurs around the tire and suppresses air from expanding from the wheel well toward the outside of the vehicle to avoid the stagnation, thereby reducing air resistance on the vehicle.

[0008] Furthermore, because the first side surface on the rear side surface in the tire main rotation direction of each protrusion and the second side surface on the front side surface in the tire main rotation direction are inclined with respect to the tire radial direction, airflow in the upper and lower parts of the tire is prevented from being significantly impeded by the side surfaces of each protrusion, unlike when both side surfaces in the tire main rotation direction of the tire outer diameter side are parallel to a straight line extending in the tire radial direction. In particular, the first side surface and the second side surface are inclined with respect to the tire radial direction toward the rear side in the tire main rotation direction from the inner side to the outer side in the tire radial direction. This makes it easier for air to flow smoothly toward the rear of the tire in the upper and lower parts of the tire due to the side surfaces of each protrusion. This also promotes turbulence of air around the tire, improving stagnation of airflow around the tire and reducing air resistance on the vehicle.

[0009] Furthermore, each protrusion protrudes in the tire width direction from the tire outer diameter side surface, and the maximum height of each protrusion in the tire width direction is 5 mm or more. This makes it easier to generate traction due to shear force when the tire side surface is partially buried in mud, sand, rocky areas, or other uneven terrain, or when it comes into contact with rocks. This improves the vehicle's driving performance on uneven terrain. This allows for both improved vehicle driving performance on uneven terrain and reduced air resistance. [Effects of the Invention]

[0010] The pneumatic tire according to the present invention can improve the running performance of a vehicle on rough ground and reduce the air resistance of the vehicle at the same time. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a perspective view showing a tire outer diameter side surface and a portion of a protrusion at a vehicle width direction outer portion of a pneumatic tire that is an example of an embodiment. FIG. [Figure 2] 1 is a schematic diagram of a front portion of a tire side surface in the traveling direction of a pneumatic tire according to an embodiment. [Figure 3] 1 is a diagram showing the direction of air flow (driving wind) flowing toward a pneumatic tire and the main rotation direction of the tire when a vehicle equipped with a pneumatic tire according to an embodiment is traveling forward. FIG. [Figure 4] 4 is a schematic enlarged view of a front portion of the tire sidewall of the pneumatic tire of FIG. 3 in the traveling direction, showing the air flow around the periphery of the pneumatic tire. [Figure 5A] FIG. 5 is a view corresponding to FIG. 4 showing a pneumatic tire of a first example of a comparative example. [Figure 5B] FIG. 5 is a view corresponding to FIG. 4 and showing a pneumatic tire of a second example of a comparative example. [Figure 6] FIG. 5 is a view corresponding to FIG. 4 showing a pneumatic tire according to another embodiment. [Figure 7] FIG. 2 is a view corresponding to FIG. 1 showing a pneumatic tire according to another embodiment. [Figure 8] 8 is a view corresponding to part A in FIG. 2 in the pneumatic tire shown in FIG. 7. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an example of an embodiment of a pneumatic tire according to the present invention will be described in detail with reference to the drawings. The embodiment described below is merely an example, and the present invention is not limited to the following embodiment. Furthermore, the present invention includes selective combinations of the components of the multiple embodiments and modified examples described below.

[0013] FIG. 1 is a perspective view showing a tire outer diameter side surface and a portion of a protrusion 50 at the outer portion in the vehicle width direction of a pneumatic tire 1 according to an embodiment. FIG. 2 is a schematic diagram of the front portion in the traveling direction of the tire side surface of the pneumatic tire 1. As shown in FIGS. 1 and 2, the pneumatic tire 1 has a tread 10 that is the portion that comes into contact with the road surface. Hereinafter, the "pneumatic tire 1" will be referred to as the "tire 1." The tread 10 has a tread pattern including a plurality of blocks, and is formed in an annular shape along the tire circumferential direction.

[0014] Hereinafter, the configuration of the tire 1 will be described mainly with reference to the outer (OUT side) portion in the vehicle width direction with respect to the center in the tire width direction. The outer shape of the tire 1 is symmetrical between the outer portion in the vehicle width direction and the inner portion in the vehicle width direction, with the exception of protrusions 50 described below.

[0015] The tread 10 includes land portions defined by, for example, multiple circumferential grooves 20, 21 and lug grooves 22 extending in the tire width direction or in a direction inclined relative to the tire width direction. The land portions are block-shaped protrusions that protrude radially outward from a reference plane of the tread 10. The reference plane is an imaginary plane along the bottom surfaces of the deepest circumferential grooves 20, 21, and refers to the outer peripheral surface of the tread 10 in the absence of any land portions. The tread 10 has a shoulder land portion 23 as the land portion located on the tire widthwise outer side of the circumferential groove 20, which is located on the outermost side in the tire width direction among the multiple circumferential grooves 20, 21. FIG. 1 illustrates a configuration in which the shoulder land portion 23 is divided into circumferentially adjacent block-shaped land portions by lug grooves 22 at multiple positions in the tire circumferential direction. The shoulder land portion may be annular and not divided into multiple land portions in the tire circumferential direction.

[0016] The tire 1 includes a sidewall 12 that is provided on the outer side of the tread 10 in the tire width direction and bulges outward most in the tire width direction, and a bead 14 that is fixed to the rim of a wheel. The sidewall 12 and the bead 14 are formed in an annular shape along the tire circumferential direction and constitute a tire side surface 40. The sidewall 12 extends radially inward from both ends of the tread 10 in the tire width direction.

[0017] The tire 1 is a pneumatic tire that is filled with air at a predetermined pressure. The tread 10 and the sidewall 12 are made of, for example, different types of rubber.

[0018] The tire side surface 40 is a profile of the outer surface in a region that is outward in the tire width direction from the ground contact edge T of the shoulder land portion 24 and continues inward in the tire radial direction. The tire side surface 40 is greatly curved so as to be convex outward in the tire width direction.

[0019] The "ground contact edge T" refers to both ends in the tire width direction of the area that comes into contact with a flat road surface when an unused tire 1 is mounted on a standard rim, inflated to the standard internal pressure, and subjected to a load that is 70% of the standard load at the standard internal pressure. In Fig. 1, to make the position of the dashed dotted line indicating the ground contact edge T easier to understand, a dashed dotted line is also shown in the space outside the ground contact surface of the shoulder land portion 23.

[0020] Here, a "regular rim" is a rim specified by the tire standard, and is a "standard rim" for JATMA, a "design rim" for TRA, and a "measuring rim" for ETRTO. "Regular internal pressure" is the "maximum air pressure" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "INFLATION PRESSURE" for ETRTO. "Regular load" is the "maximum load capacity" for JATMA, the maximum value listed in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table for TRA, and "LOAD CAPACITY" for ETRTO.

[0021] Although not shown, the tire 1 includes a carcass, a belt, and an inner liner. The carcass is a cord layer coated with rubber and forms the framework of the tire 1, which can withstand loads, impacts, air pressure, etc. The belt is a reinforcing band placed between the carcass and the rubber that makes up the tread 10. The belt tightly tightens the carcass, increasing the rigidity of the tire 1. The inner liner is a rubber layer provided on the inner surface of the carcass and maintains the air pressure of the tire 1. The bead 14 includes a bead core and a bead filler.

[0022] In the tire 1 of the embodiment, the mounting direction of the front and back of the tire 1 relative to the vehicle is specified. That is, the outer and inner sides of the tire 1 in the vehicle width direction are respectively specified. In FIG. 1, the tire 1 is mounted on the vehicle so that the right side is the outer side (OUT side) in the vehicle width direction and the left side is the inner side (IN side) in the vehicle width direction. The tire 1 also has a specified main tire rotation direction (direction of arrow α). The "main tire rotation direction" is the rotation direction of the tire 1 when the vehicle on which the tire 1 is mounted moves forward. For this reason, it is preferable that the tire 1 be provided with markings to indicate the mounting direction and rotation direction relative to the vehicle.

[0023] A symbol called a serial number is generally provided on the side of a tire. The serial number includes information such as a size code, manufacturing date (manufacturing year and week), and manufacturing location (manufacturing factory code). The mounting direction of the tire 1 on the vehicle can be specified by providing a serial number only on the tire side (sidewall 11) facing outward in the vehicle width direction, or by providing different serial numbers on the side facing outward in the vehicle width direction and the side facing inward in the vehicle width direction. A specific example is to provide a manufacturing factory code and a size code on both sides of the tire 1, and provide the manufacturing year and week only on the side facing outward in the vehicle width direction.

[0024] Furthermore, the tire side facing outward in the width direction of the vehicle may be provided with either or both of a letter or symbol indicating that the tire is on the outward side when mounted on the vehicle and a symbol indicating the direction of rotation. For example, the direction of rotation may be indicated by an arrow symbol pointing forward in the direction of rotation.

[0025] Furthermore, the tire sidewall 40 defines a tire maximum width position WP and a tire outer diameter sidewall 41. The "tire maximum width position" refers to the end of the tire section width, and is the outermost end position in the tire width direction on the outer surface of the tire 1. The tire section width is the position at which the tire width direction is maximum on the profile line of the outer surface of the tire 1 when the tire 1 is mounted on a standard rim, inflated to the standard internal pressure, and in an unloaded state. The profile line is the outline of the outer surface of the sidewall main body 13 of the sidewall 12, excluding protrusions such as rim protectors, and typically has a tire meridian cross-sectional shape defined by smoothly connecting multiple arcs.

[0026] The "tire outer diameter side surface" refers to the surface that is more outward in the tire width direction than the ground contact edge T and more outward in the tire radial direction than the tire maximum width position WP, and is a region called a buttress. Therefore, the tire outer diameter side surface 41 is the surface of the tire side surface 40 that is located more outward in the tire radial direction than the tire maximum width position WP.

[0027] In the embodiment, a plurality of protrusions 50 protrude outward in the tire width direction at intervals from a plurality of positions in the tire circumferential direction of the tire outer diameter side surface 41. In the example shown in FIG. 1 , each protrusion 50 is formed continuously from the outer ends in the tire width direction of two shoulder land portions 23 adjacent in the tire circumferential direction, but one protrusion may be formed continuously from each shoulder land portion 23, or the protrusions may be formed with a gap from each shoulder land portion 23. The inner ends in the tire radial direction of the plurality of protrusions 50 may be configured to approximately coincide with the tire maximum width position. No protrusions protruding from the tire side surface 40 and having a shape different from the protrusions 50 are formed between the plurality of protrusions 50 in the tire circumferential direction.

[0028] Each protrusion 50 has a substantially rectangular block shape, and as shown in FIG. 2, when viewed from the outside in the vehicle width direction, the outer shape of the top surface S1, where the tire width direction height is greatest, is a substantially rectangular shape that is inclined with respect to the tire radial direction, as described below. The tire radially inner side surface and both tire circumferential side surfaces of each protrusion 50 are aligned along the tire width direction. On the other hand, the tire radially outer side surface of each protrusion 50 is inclined with respect to both the tire width direction and the tire circumferential direction so as to connect the tire width direction outer end of the shoulder land portion 23 and the tire radially outer edge of the top surface S1 of the protrusion 50. In FIG. 2, only the outer shape of the top surface S1 of each protrusion 50 is shown, and the tire radially outer side surface of each protrusion 50 is not shown.

[0029] Furthermore, the maximum height of each of the plurality of protrusions 50 in the tire width direction is 5 mm or more. This improves the vehicle's running performance on uneven ground, as described below. Furthermore, in each of the plurality of protrusions 50, a first side surface 51 located at the rearmost end of the rear side surface in the tire main rotation direction (the direction of arrow α in FIG. 2 ) and a second side surface 53 located at the frontmost end of the front side surface in the tire main rotation direction are inclined relative to the tire radial direction, from the inside to the outside in the tire radial direction, toward the rear side in the tire main rotation direction. This reduces air resistance on the vehicle, as described below. In the example shown in FIGS. 1 and 2 , the rear side surface in the tire main rotation direction of each protrusion 50, including its rearmost end, is the first side surface 51, which is substantially flat overall. Furthermore, the front side surface in the tire main rotation direction of each protrusion 50, including its frontmost end, is the second side surface 53, which is substantially flat overall. As a result, the outer shape of the top surface S1 of each protrusion 50 is substantially rectangular and inclined relative to the tire radial direction.

[0030] Each protrusion 50 is made of a rubber material. The rubber material that forms each protrusion 50 may be the rubber material that forms the sidewall main body 13, or may be a rubber material different from the rubber material that forms the sidewall main body 13.

[0031] 2, the angle at which the first side surfaces 51 of the multiple protrusions 50 are inclined with respect to the tire radial direction is the same angle θ1 for all the multiple protrusions 50. The angle at which the second side surfaces 53 of the multiple protrusions 50 are inclined with respect to the tire radial direction is the same angle θ2 for all the multiple protrusions 50. The angle θ1 and the angle θ2 may be the same or different.

[0032] The angles θ1 and θ2 at which the first side surface 51 and the second side surface 53 of each protrusion 50 are inclined relative to the tire radial direction are 20 degrees or more and 70 degrees or less. The angles θ1 and θ2 are preferably 30 degrees or more and 60 degrees or less, and more preferably 40 degrees or more and 50 degrees or less. It is even more preferable that the angles θ1 and θ2 are approximately 45 degrees.

[0033] Furthermore, the first side surface 51 and the second side surface 53 of each protrusion 50 are inclined relative to the tire radial direction from the inside to the outside in the tire radial direction toward the rear side in the tire main rotation direction (rear side in the direction of arrow α).

[0034] The rear side surface of each protrusion 50 in the tire main rotation direction may have a bent portion or unevenness formed in part, as long as there is a first side surface that is inclined to a predetermined side relative to the tire radial direction as described above in the part including the rearmost end of the rear side surface in the tire main rotation direction.

[0035] The front side surface of each protrusion 50 in the tire main rotation direction may have a bent portion or unevenness formed in part, as long as the part including the foremost end of the front side surface in the tire main rotation direction has a second side surface that is inclined to a predetermined side relative to the tire radial direction as described above.

[0036] The tire 1 described above can achieve both reduced air resistance on a vehicle and improved running performance on rough ground. Specifically, when a vehicle equipped with the tire 1 is running, the multiple protrusions 50 rotate in conjunction with the rotation of the tire 1, thereby turbulently creating many fine vortices in the air around the tire.

[0037] Fig. 3 shows the direction of airflow (driving wind) flowing toward the tire 1 and the main direction of tire rotation when a vehicle 100 equipped with the tire 1 travels forward. Fig. 4 is a schematic enlarged view of the front portion of the tire sidewall 40 of the tire 1 in Fig. 3 in the traveling direction, showing the airflow around the tire 1.

[0038] As shown in Figures 3 and 4, when the vehicle 100 travels forward, the tire 1 rotates in the direction of arrow α, and the traveling wind flowing toward the tire 1 flows in the direction indicated by arrow γ. In Figure 3, only a portion of the vehicle 100 is shown, with the outline arrow indicating the traveling direction of the vehicle 100. At this time, as shown in Figure 4, on the tire outer diameter side surface 41, each protrusion 50 rotates in the direction of rotation of the tire 1 (the direction of arrow α). As a result, when the tire 1 rotates, the protrusions 50, which are inclined relative to the tire radial direction, disturb the air flow, thereby turbulently creating many fine vortices in the air around the tire 1. In Figure 4, the thick black arrows indicate the air flow near the tire side surface 40. This improves airflow stagnation around the tire 1 and suppresses air bulging from within the tire housing 101 toward the outside of the vehicle to avoid the stagnation. This reduces air resistance on the vehicle 100.

[0039] Furthermore, in tire 1, the first side surface 51 on the rear side surface in the tire main rotation direction of each protrusion 50 and the second side surface 53 on the front side surface in the tire main rotation direction, which are the surfaces at the upper or lower part of the tire that are most likely to be hit by air, are inclined with respect to the tire radial direction, and therefore, unlike when both side surfaces in the tire main rotation direction of protrusion 50 are surfaces parallel to straight lines extending in the tire radial direction, it is possible to prevent the side surfaces of each protrusion 50 from significantly impeding the flow of air at the upper and lower parts of tire 1. In this regard, first, a comparative tire will be described using Fig. 5A.

[0040] Fig. 5A is a view corresponding to Fig. 4 and shows a tire 1a of a first example of a comparative example. In the tire 1a of Fig. 5, protrusions 50a are formed at equal intervals at multiple positions in the tire circumferential direction on the tire outer diameter side surface 41. The shape of the top surface S2 located at the outermost position in the tire width direction of each protrusion 50a is approximately rectangular when viewed from the outside in the tire width direction.

[0041] On the other hand, both side surfaces of each protrusion 50a in the tire main rotation direction are parallel to a straight line extending in the tire radial direction. As a result, a first side surface 51 on the rear side surface of each protrusion 50a in the tire main rotation direction is inclined at an angle θ3 toward the front side in the tire main rotation direction with respect to the tire radial direction, while a second side surface 53 on the front side surface in the tire main rotation direction is inclined at an angle θ4 toward the rear side in the tire main rotation direction with respect to the tire radial direction. Therefore, the side on which the first side surface 51 is inclined with respect to the tire radial direction and the side on which the second side surface 53 is inclined with respect to the tire radial direction are opposite to each other. Also, in the example of FIG. 5A, the angles θ3 and θ4 are both smaller than 10 degrees.

[0042] 5A, when the protrusions 50a are located at the upper and lower portions of the tire outer diameter side surface 41 during rotation of the tire 1a, the front side surfaces of the protrusions 50a at the upper and lower portions in the vehicle traveling direction are quite close to each other in the vertical direction. As a result, as shown by arrows P1 and P2, the protrusions 50a significantly obstruct the flow of air coming from the front side in the traveling direction of the tire 1 toward the protrusions 50a located at the upper and lower portions. This reduces the effect of turbulentizing the air around the tire, thereby reducing the effect of improving air stagnation around the tire.

[0043] On the other hand, in the tire 1 of the embodiment, even when the protrusions 50 are located at the top and bottom of the tire 1 as shown in Fig. 4, the front side surfaces of the protrusions 50 in the vehicle traveling direction tend to be significantly inclined with respect to the tire radial direction, making it easier to guide the air and flow it rearward. In particular, in the tire 1, the first side surface 51 and the second side surface 53 of each protrusion 50 are inclined with respect to the tire radial direction from the inside to the outside in the tire radial direction toward the rear in the main tire rotation direction. This makes it easier for the side surfaces of each protrusion 50 at the top and bottom of the tire 1 to smoothly flow air rearward in the tire.

[0044] For example, in the lower part of tire 1 in Fig. 4, air is guided by protrusions 50 as shown by arrows P3-P4, and tends to flow smoothly from the outer side in the tire radial direction through the inner part to the rear of the tire. In this case, air tends to flow in a space that is wider than the space between protrusions 50 and the road surface.

[0045] On the other hand, in the upper part of the tire 1, as shown by arrow P5, the air is guided by the protrusions 50, making it easier to flow smoothly from the outer side in the tire radial direction to the rear of the tire. In this case, the air flow and the direction of travel of the upper protrusions 50 are substantially opposite to each other, but the inclination direction of the protrusions 50 allows the air to escape in a direction away from the protrusions 50 to the outer side in the tire radial direction. This also promotes turbulence in the air around the tire, improving stagnation of the air flow around the tire and reducing air resistance on the vehicle 100.

[0046] Furthermore, in this embodiment, each protrusion 50 protrudes in the tire width direction from the tire outer diameter side surface 41, and the maximum height of each protrusion 50 in the tire width direction is 5 mm or more. This makes it easier to generate traction due to shear force when the tire side surface is buried to some extent on uneven ground such as muddy ground, sandy ground, or rocky area, or when it comes into contact with rocks. This improves the driving performance of the vehicle 100 on uneven ground. This allows both improved driving performance of the vehicle 100 on uneven ground and reduced air resistance of the vehicle 100.

[0047] Furthermore, in the tire 1 of the embodiment, the angles θ1 and θ2 at which the first side surface 51 and the second side surface 53 of the multiple protrusions 50 are inclined relative to the tire radial direction are 20 degrees or more and 70 degrees or less, respectively. This enhances the effect of improving air stagnation around the tire. Unlike the embodiment, if the angles θ1 and θ2 are less than 20 degrees, and the protrusions are located at the upper and lower parts of the tire side as in the comparative example shown in FIG. 5A, the protrusions will approach a vertically upright state. As a result, the protrusions significantly obstruct the flow of air from the front of the vehicle toward the protrusions, thereby reducing the effect of improving air stagnation around the tire.

[0048] On the other hand, when angles θ1 and θ2 are greater than 70 degrees, for example, a protrusion corresponding to protrusion 50 near the front end of tire outer diameter side surface 41 in the traveling direction, for example, at the position indicated by point E in FIG. 4, is positioned so as to approach a vertically upright state. As a result, the air flow from the front of vehicle 100 in the traveling direction toward protrusion 50 is significantly obstructed by the protrusion, reducing the effect of improving stagnation around the tire. When angle θ is set to be equal to or greater than 20 degrees and equal to or less than 70 degrees, such inconvenience can be prevented, thereby improving the effect of improving air stagnation around the tire.

[0049] The closer the angles θ1 and θ2 are to 45 degrees relative to the radial direction, the more the airflow at the top and bottom of the tire and near the front end in the direction of travel can be prevented from being significantly impeded. For this reason, the angle θ is preferably 30 degrees or more and 60 degrees or less, more preferably 40 degrees or more and 50 degrees or less, and even more preferably approximately 45 degrees.

[0050] Fig. 5B is a view corresponding to Fig. 4 and shows a tire 1b of a second example of the comparative example. In the tire 1b of Fig. 5B, the shape of the top surface S3 located at the outermost position in the tire width direction of each protrusion 50b when viewed from the outside in the tire width direction is substantially rectangular, the same as in the configuration shown in Fig. 4.

[0051] On the other hand, both side surfaces of each protrusion 50b in the tire main rotation direction are inclined from the inner side to the outer side in the tire radial direction toward the front side in the tire main rotation direction (the direction of arrow α) with respect to the tire radial direction. That is, in tire 1b of the comparative example, the direction in which each protrusion 5 is inclined with respect to the tire radial direction is opposite to that in the embodiment of FIG. 4 with respect to the tire main rotation direction. In this comparative example, unlike the embodiment of FIG. 4, in the lower part of FIG. 5B, the protrusions 50 tend to be arranged so as to approach a vertically upright state, as in the protrusion 50 indicated by F1. Therefore, compared to the embodiment of FIG. 4, the effect of the protrusions 50 guiding air to facilitate smooth flow to the rear of the tire is reduced.

[0052] Furthermore, in the upper part of tire 1b, as in the case of protrusions 50 indicated by F2, air tends to be guided by the protrusions 50 from the outer side to the inner side in the tire radial direction, but the air flow and the direction of travel of the upper protrusions 50 face each other and collide with each other. As a result, compared to the embodiment in Fig. 4, the effect of guiding air with the protrusions 50 to facilitate smooth flow to the rear of the tire is reduced.

[0053] According to the embodiment shown in FIGS. 1 to 4, the effect of guiding the air by the projections 50 and facilitating a smooth flow to the rear of the tire is enhanced compared to such a comparative example.

[0054] 6 is a diagram corresponding to FIG. 4 and shows a tire 1c according to another embodiment. In the tire 1c of this example, the shape of the top surface S4 located at the outermost position in the tire width direction of the multiple protrusions 50c when viewed from the outside in the tire width direction is a trapezoid with the short side on the inner side in the tire radial direction and the long side on the outer side in the tire radial direction. In this example as well, the first side surface 51 located at the rearmost end of the rear side in the tire main rotation direction is inclined relative to the tire radial direction from the inner side in the tire radial direction to the outer side toward the rear side in the tire main rotation direction (the direction of arrow α). The first side surface 51 is inclined at an angle θ5 relative to the tire radial direction.

[0055] On the other hand, a second side surface 53 located at the forefront of the front side surface in the tire main rotation direction is also inclined from the inner side to the outer side in the tire radial direction toward the rear side in the tire main rotation direction (the direction of arrow α) with respect to the tire radial direction. The second side surface 53 is inclined at an angle θ6 with respect to the tire radial direction.

[0056] In the case of tire 1c of this example, the inclination angles θ5 and θ6 of the first side surface 51 and second side surface 53 of protrusion 50c are restricted to the same extent as in the configuration of Figures 1 to 4, while the lengths of the two straight lines on both sides in the tire circumferential direction connecting the short and long sides of the trapezoidal shape of top surface S4 can be increased. This makes it easier to increase the area of ​​both sides in the tire circumferential direction of protrusion 50c. Therefore, the protrusion 50c is more effective in turbulently generating air around the tire. In this example, the other configurations and functions are the same as those of the configuration of Figures 1 to 4.

[0057] In the above-described embodiments, the shape of the top surface of the protrusion 50 when viewed from the outer side in the tire width direction is rectangular or trapezoidal, but is not limited to this. As long as the first side surface 51 located at the rearmost end of the rear side surface in the tire main rotation direction and the second side surface 53 located at the frontmost end of the front side surface in the tire main rotation direction are inclined with respect to the tire radial direction toward the rear side in the tire main rotation direction from the inner side in the tire radial direction to the outer side, the top surface of the protrusion may be in various shapes, such as another polygon.

[0058] Fig. 7 is a view corresponding to Fig. 1 and shows a tire 1d according to another embodiment. Fig. 8 is a view of tire 1d corresponding to part A in Fig. 2. In tire 1d of this example, in each of a plurality of protrusions 50d, a convex element 60 having a step surface 61 is formed between a first side surface 51 and a second side surface 53 in the tire circumferential direction.

[0059] Specifically, each protrusion 50d includes an intermediate height surface 54 having an intermediate height in the protruding direction in the tire width direction, and a convex element 60 that protrudes from a portion of the intermediate height surface 54 that is inward in the tire circumferential direction from the front end of the intermediate height surface 54 in the tire main rotation direction α and has a top surface S4 that is a maximum height surface. A step surface 61 is formed on the front side surface of the convex element 60 in the tire main rotation direction. This gives the convex element 60 its maximum height in the tire width direction.

[0060] As shown in Fig. 8, when the top surface S4, which is the outer end in the tire width direction of the convex element 60, is viewed from the outside in the tire width direction, the top surface S4 has a substantially rectangular shape. Although Figs. 7 and 8 show a case where the tire radially outer end of the convex element 60 is positioned more inward in the tire radial direction than the tire radially outer end of the mid-height surface 54, the tire radially outer end of the convex element 60 and the tire radially outer end of the mid-height surface 54 may be aligned in the tire radial direction.

[0061] 8, a third side surface 62 located at the rearmost end of the rear side surface of the convex element 60 in the tire main rotation direction and a fourth side surface 63 located at the frontmost end of the front side surface in the tire main rotation direction are inclined relative to the tire radial direction toward the rear side in the tire main rotation direction from the inner side to the outer side in the tire radial direction. The fourth side surface 63 is a part or the entirety of the step surface 61.

[0062] As long as the rear side surface of each convex element 60 in the tire main rotation direction has a third side surface 62 that is inclined toward a predetermined side relative to the tire radial direction as described above in a portion including the rearmost end of the rear side surface in the tire main rotation direction, the entire rear side surface of the convex element 60 in the tire main rotation direction may have a flat third side surface 62, or may have a bent portion or unevenness formed in part.

[0063] 8, the rear side surface of the convex element 60 in the tire main rotation direction is aligned with the rear end of the mid-height surface 54 of the protrusion 50 in the tire main rotation direction α in the tire circumferential direction. Therefore, the inclination direction of the first side surface 51 of the protrusion 50 with respect to the tire radial direction is aligned with the inclination direction of the third side surface 62 of the convex element 60 with respect to the tire radial direction.

[0064] As long as the front side surface of each convex element 60 in the tire main rotation direction has a fourth side surface 63 that is inclined toward a predetermined side relative to the tire radial direction as described above in the portion including the foremost end of the front side surface in the tire main rotation direction, the entire front side surface in the tire main rotation direction may have a flat fourth side surface 63, or may have a bent portion or unevenness formed in part.

[0065] Furthermore, the angles θ7 and θ8 at which the third side surface 62 and the fourth side surface 63 of the convex element 60 are inclined relative to the tire radial direction are 20 degrees or more and 70 degrees or less. The angles θ7 and θ8 are preferably 30 degrees or more and 60 degrees or less, and more preferably 40 degrees or more and 50 degrees or less. It is even more preferable that the angles θ7 and θ8 are approximately 45 degrees.

[0066] According to the configuration of this example, in the convex element 60 having the maximum height of the protrusion 50d, the inclination direction of the third side surface 62 and the fourth side surface 63, which are both side surfaces in the tire circumferential direction, is restricted in the same manner as the first side surface 51 and the second side surface 53. This restricts the angle of the surface of the protrusion 50d that is more likely to be hit by the air flow. This further promotes turbulence of the air around the tire, further improving stagnation of the air flow around the tire and further reducing air resistance on the vehicle.

[0067] In addition, the angles θ7 and θ8 at which the third side surface 62 and the fourth side surface 63 of the convex element 60 are inclined relative to the tire radial direction are set to be equal to or greater than 20 degrees and equal to or less than 70 degrees, which further improves the effect of improving air stagnation around the tire. In this example, the other configurations and functions are the same as those in Figures 1 to 4.

[0068] 7 and 8, the convex elements may be configured to protrude from a portion of the intermediate height surface of each protrusion that is inward in the tire circumferential direction from the rear end, in the tire main rotation direction α, of the tire. In this case, a step surface of the convex element is formed at a position inward in the tire circumferential direction from the rear end, in the tire main rotation direction α, of the convex element, i.e., between the first side surface and the second side surface.

[0069] Furthermore, a configuration may be adopted in which convex elements are formed on the first height surface of each protrusion, protruding from portions that extend inward in the tire circumferential direction from both the first side surface and the second side surface. In this case, the front side surface and the rear side surface of the convex element in the tire main rotational direction α respectively become two step surfaces between the first side surface and the second side surface.

[0070] In each of the above embodiments, the protrusions 50, 50c, and 50d are formed only on the tire side surface facing outward in the vehicle width direction, but the tire mounting direction may be unspecified by forming protrusions on the tire side surface on both sides in the tire width direction. [Explanation of symbols]

[0071] 1, 1a, 1b, 1c, 1d Pneumatic tire (tire), 10 Tread, 12 Sidewall, 13 Sidewall body, 14 Bead, 20, 21 Circumferential groove, 22 Lug groove, 23 Shoulder land portion, 40 Tire side surface, 41 Tire outer diameter side surface, 50, 50a, 50b, 50c, 50d Protrusion, 51 First side surface, 53 Second side surface, 54 Mid-height surface, 60 Convex element, 61 Step surface, 62 Third side surface, 63 Fourth side surface, T Ground contact edge.

Claims

1. The tire has a surface on the outer side in the tire width direction from the ground contact edge, and the surface is on the outer side of the tire radial direction from the tire maximum width position. The tire has a plurality of protrusions that protrude outward in the tire width direction at intervals in the tire circumferential direction, The maximum height of each of the plurality of protrusions in the tire width direction is 5 mm or more, In each of the plurality of protrusions, a first side surface located at a rearmost end of a rear side surface in the tire main rotation direction and a second side surface located at a frontmost end of a front side surface in the tire main rotation direction are inclined with respect to the tire radial direction toward the rear side in the tire main rotation direction from the inner side toward the outer side in the tire radial direction, Each of the plurality of protrusions has a block shape including a tire radially outer side surface provided between tire radially outer ends of the first side surface and the second side surface, and a tire radially inner side surface provided between tire radially inner ends of the first side surface and the second side surface, and the plurality of protrusions do not overlap with the tire maximum width position, and when viewed from the outer side in the tire width direction, the shape of the plurality of protrusions is a trapezoid having a short side on the inner side in the tire radial direction and a long side on the outer side in the tire radial direction; Pneumatic tires.

2. an inclination angle θ of each of the first side surface and the second side surface of each of the plurality of protrusions with respect to the tire radial direction is equal to or greater than 20 degrees and is equal to or less than 70 degrees; The pneumatic tire according to claim 1 .

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