JP7811461B2 - pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire, and more specifically to a pneumatic tire having a protrusion that protrudes outward in the tire width direction on the outer diameter side surface of the tire.

Conventionally, pneumatic tires have been known that have multiple protrusions on the sidewalls of the tire that extend intersecting 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 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 tire's maximum width position. This is said to aim to reduce air resistance on the vehicle by turbulent air flow in the tire sidewalls and reduce air passing noise on the vehicle's sidewalls.

International Publication No. 2018/008726

The pneumatic tire of Patent Document 1 has multiple protrusions on the tire side that are inclined relative to the tire radial direction, which may reduce air resistance on a vehicle. However, this tire is not designed to 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 an area 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, there is a need for a pneumatic tire that can both improve vehicle driving performance on rough terrain and reduce air resistance on the vehicle.

The object of the present invention is to provide a pneumatic tire that can simultaneously improve a vehicle's driving performance on rough terrain and reduce air resistance on the vehicle.

The pneumatic tire according to the present invention has a surface on the tire widthwise outer side of the tire radially outer side of the tire, radially outer than the tire's maximum width position, that is provided with a plurality of protrusions spaced apart in the tire circumferential direction and protruding outward in the tire width direction, the maximum height in the tire width direction of each of the plurality of protrusions being 5 mm or more, and each of the plurality of protrusions having a first side surface located at the rearmost end of the rear side surface in the tire's main rotational direction and a second side surface located at the frontmost end of the front side surface in the tire's main rotational direction inclined radially from the inner side to the outer side in the tire radial direction toward the rear side in the tire's main rotational direction.

With the above-mentioned pneumatic tire, when the vehicle is running, multiple protrusions provided on the outer diameter side of the tire rotate in conjunction with the tire's rotation, 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 within the wheelhouse toward the outside of the vehicle to avoid this stagnation, thereby reducing air resistance on the vehicle.

In addition, because the first side surface on the rear side surface in the main tire rotation direction of each protrusion and the second side surface on the front side surface in the main tire rotation direction are inclined with respect to the tire radial direction, air flow at the top and bottom of the tire is prevented from being significantly impeded by the side surfaces of each protrusion, unlike when both side surfaces in the main tire 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 second side surface are inclined with respect to the tire radial direction, from the inside to the outside in the tire radial direction toward the rear side in the main tire rotation direction. This makes it easier for air to flow smoothly toward the rear of the tire at the top and bottom of the tire due to the side surfaces of each protrusion. This also promotes air turbulence around the tire, improving stagnation of air flow around the tire and reducing air resistance on the vehicle.

Furthermore, each protrusion protrudes in the tire width direction from the tire's outer diameter side, 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 becomes partially buried in uneven terrain such as mud, sand, or rocks, 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 on the vehicle.

The pneumatic tire of the present invention can improve a vehicle's driving performance on uneven ground while reducing air resistance.

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. 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. 1 is a diagram illustrating 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. 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 airflow around the periphery of the pneumatic tire. FIG. FIG. 5 is a view corresponding to FIG. 4 showing a pneumatic tire of a first example of a comparative example. FIG. 5 is a view corresponding to FIG. 4 showing a pneumatic tire of a second example of a comparative example. 5 is a view corresponding to FIG. 4 showing a pneumatic tire according to another embodiment of the present invention. FIG. 2 is a view corresponding to FIG. 1 showing a pneumatic tire according to another embodiment. 8 is a view corresponding to part A in FIG. 2 in the pneumatic tire shown in FIG. 7.

Below, one 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 variations described below.

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

The following describes the configuration of tire 1, focusing on the outer (OUT side) portion in the vehicle width direction, centered on the tire width center. The outer shape of tire 1 is symmetrical between the outer and inner portions in the vehicle width direction, with the exception of the protrusions 50, which will be described later.

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 the reference plane of the tread 10. The reference plane is an imaginary plane along the bottom surface of the deepest circumferential grooves 20, 21, and refers to the outer peripheral surface of the tread 10 in the absence of land portions. The tread 10 has shoulder land portions 23 as the land portions located on the tire widthwise outer side of the circumferential groove 20, which is located furthest outward in the tire width direction among the multiple circumferential grooves 20, 21. Figure 1 shows the shoulder land portions 23 divided into circumferentially adjacent block-shaped land portions by lug grooves 22 at multiple positions in the tire circumferential direction. The shoulder land portions may also be annular land portions that are not divided into multiple land portions separated in the tire circumferential direction.

The tire 1 comprises a sidewall 12 located outward in the tire width direction from the tread 10 and bulging outward most in the tire width direction, and a bead 14 fixed to the wheel rim. The sidewall 12 and bead 14 are formed in an annular shape along the tire circumferential direction and constitute the tire side surface 40. The sidewall 12 extends radially inward from both ends of the tread 10 in the tire width direction.

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

The tire side surface 40 is the profile of the outer surface in the region extending from the ground contact edge T of the shoulder land portion 24 outward in the tire width direction to the tire radially inward. The tire side surface 40 is significantly curved so as to be convex outward in the tire width direction.

"Track 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 of 70% of the standard load at the standard internal pressure. In Figure 1, to make the position of the dashed-dotted line indicating the track edge T easier to understand, dashed-dotted lines are also shown in the space outside the track surface of the shoulder land portion 23.

Here, a "regular rim" is a rim specified by tire standards, 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.

Although not shown, the tire 1 comprises a carcass, belt, and inner liner. The carcass is a rubber-coated cord layer that forms the skeleton of the tire 1, allowing it to 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 fastens the carcass, increasing the rigidity of the tire 1. The inner liner is a rubber layer attached to the inner surface of the carcass, and maintains the air pressure of the tire 1. The bead 14 also has a bead core and a bead filler.

In this 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 specified. In Figure 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 direction of rotation 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 indicating the mounting direction and rotation direction relative to the vehicle.

Tire sides generally have symbols called serial numbers. Serial numbers include 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's width, or by providing different serial numbers on the side facing outward and the side facing inward in the vehicle's width. A specific example is providing a manufacturing factory code and size code on both sides of the tire 1, and providing the manufacturing year and week only on the side facing outward in the vehicle's width.

Also, the tire side facing outward in the vehicle's width direction may be provided with either or both letters or symbols 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 can be indicated by an arrow symbol pointing forward in the direction of rotation.

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 edge of the tire cross-sectional width, and is the outermost edge position in the tire width direction on the outer surface of the tire 1. The tire cross-sectional width is the position at which the tire cross-sectional width is greatest 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.

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 the area called the 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.

In this embodiment, multiple protrusions 50 protrude outward in the tire width direction at intervals from multiple positions in the tire circumferential direction on the tire outer diameter side surface 41. In the example shown in FIG. 1, each protrusion 50 is formed continuously from the tire widthwise outer ends of two circumferentially adjacent shoulder land portions 23. However, 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 of the multiple protrusions 50 in the tire radial direction 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 multiple protrusions 50 in the tire circumferential direction.

Each protrusion 50 is in the shape of a roughly rectangular parallelepiped block. 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 widthwise height is greatest, is roughly rectangular and inclined relative 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 relative to both the tire width direction and the tire circumferential direction so as to connect the tire widthwise 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 surface of each protrusion 50 is not shown.

Furthermore, the maximum height of each of the multiple protrusions 50 in the tire width direction is 5 mm or more. This improves the vehicle's driving performance on uneven terrain, as described below. Furthermore, in each of the multiple protrusions 50, the first side surface 51 located at the rearmost end of the rear side surface in the tire's main rotation direction (the direction of arrow α in Figure 2 ) and the second side surface 53 located at the frontmost end of the front side surface in the tire's 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's main rotation direction. This reduces air resistance on the vehicle, as described below. In the example shown in Figures 1 and 2 , the rear side surface in the tire's main rotation direction of each protrusion 50, including its rearmost end, is the first side surface 51, which is generally flat. Furthermore, the front side surface in the tire's main rotation direction of each protrusion 50, including its frontmost end, is the second side surface 53, which is generally flat. As a result, the outer shape of the top surface S1 of each protrusion 50 is generally rectangular and inclined relative to the tire radial direction.

Each protrusion 50 is formed from a rubber material. The rubber material forming each protrusion 50 may be the same rubber material as that forming the sidewall main body 13, or it may be a different rubber material from that forming the sidewall main body 13.

As shown in FIG. 2, the angle at which the first side surfaces 51 of the multiple protrusions 50 are inclined relative to the tire radial direction is the same angle θ1 for all multiple protrusions 50. The angle at which the second side surfaces 53 of the multiple protrusions 50 are inclined relative to the tire radial direction is the same angle θ2 for all multiple protrusions 50. The angles θ1 and θ2 may be the same or different.

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 greater and 70 degrees or less. Angles θ1 and θ2 are preferably 30 degrees or greater and 60 degrees or less, and more preferably 40 degrees or greater and 50 degrees or less. Angles θ1 and θ2 are even more preferably approximately 45 degrees.

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

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 the portion including the rearmost end of the rear side surface in the tire main rotation direction has a first side surface that is inclined to a predetermined side relative to the tire radial direction as described above.

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

The tire 1 described above can reduce air resistance on a vehicle while improving driving performance on rough terrain. Specifically, when a vehicle fitted with tire 1 is running, the multiple protrusions 50 rotate in conjunction with the rotation of tire 1, causing the air around the tire to become turbulent with many fine vortices.

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

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. Figure 3 shows only a portion of the vehicle 100, with the outline arrow indicating the direction of travel of the vehicle 100. At this time, as shown in Figure 4, on the tire's 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's radial direction, disturb the air flow, creating numerous fine vortices that turbulently flow 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.

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 top or bottom of the tire that are most likely to be hit by air, are inclined with respect to the tire radial direction. Therefore, unlike when both sides of the protrusion 50 in the tire main rotation direction are parallel to a straight line extending in the tire radial direction, significant obstruction of air flow by the side surfaces of each protrusion 50 at the top and bottom of tire 1 can be prevented. Regarding this, a comparative tire will first be described using Figure 5A.

Figure 5A is a diagram corresponding to Figure 4 and shows a tire 1a of a first example of a comparative example. In the tire 1a of Figure 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 top surface S2, which is located at the outermost position in the tire width direction of each protrusion 50a, has a substantially rectangular shape when viewed from the outside in the tire width direction.

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, the first side surface 51 on the rear side 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 the second side surface 53 on the front side 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. Furthermore, in the example of Figure 5A, angles θ3 and θ4 are both less than 10 degrees.

In the comparative example shown in Figure 5A, when protrusions 50a are located at the upper and lower parts of the tire outer diameter side surface 41 while the tire 1a is rotating, the front sides of the protrusions 50a at the upper and lower parts, in the direction of vehicle travel, are quite close in the vertical direction. As a result, as shown by arrows P1 and P2, the protrusions 50a located at the upper and lower parts significantly obstruct the flow of air from the front side in the direction of travel of the tire 1. This reduces the effect of turbulentizing the air around the tire, and therefore reduces the effect of improving air stagnation around the tire.

On the other hand, in the tire 1 of this embodiment, as shown in Figure 4, even when protrusions 50 are located at the top and bottom of the tire 1, the front side of the protrusions 50 in the direction of vehicle travel tends to be significantly inclined relative to the tire radial direction, making it easier to guide air and flow it rearward. In particular, in the tire 1, the first side 51 and second side 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 in the main tire rotation direction. This makes it easier for air to flow smoothly rearward in the tire at the top and bottom of the tire 1 due to the side of each protrusion 50.

For example, in the lower part of tire 1 in Figure 4, air is guided by protrusions 50, as shown by arrows P3-P4, and tends to flow smoothly from the outer radial part of the tire 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.

On the other hand, at the upper part of the tire 1, as shown by arrow P5, the protrusions 50 guide the air, making it easier for it to flow smoothly from the outside 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 roughly opposite each other, but the inclination direction of the protrusions 50 allows the air to escape in a direction away from the protrusions 50 toward the outside 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.

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 terrain such as mud, sand, or rocky areas, or when it comes into contact with rocks. This improves the driving performance of the vehicle 100 on uneven terrain. This allows for both improved driving performance of the vehicle 100 on uneven terrain and reduced air resistance on the vehicle 100.

Furthermore, in the tire 1 of this 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 greater 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 top and bottom of the tire side, as in the comparative example shown in Figure 5A, the protrusions will approach a vertically upright state when these protrusions are located at the top and bottom of the tire side. As a result, the protrusions significantly impede the flow of air from the front of the vehicle in the direction of travel toward the protrusions, reducing the effect of improving air stagnation around the tire.

On the other hand, when angles θ1 and θ2 are greater than 70 degrees, the protrusion corresponding to protrusion 50 near the front end of the tire outer diameter side surface 41 in the direction of travel, for example, at the position indicated by point E in Figure 4, is positioned so as to approach a vertically upright state. As a result, the air flow from the front of the vehicle 100 in the direction of travel toward protrusion 50 is significantly obstructed by the protrusion, reducing the effectiveness of improving stagnation around the tire. Setting angle θ between 20 degrees and 70 degrees can prevent this problem, thereby improving the effectiveness of improving air stagnation around the tire.

The closer the angles θ1 and θ2 are to 45 degrees relative to the radial direction, the more they can prevent significant obstruction to the airflow at the top and bottom of the tire and near the front end in the direction of travel. Therefore, the angle θ is preferably between 30 degrees and 60 degrees, more preferably between 40 degrees and 50 degrees, and even more preferably approximately 45 degrees.

Figure 5B is a diagram corresponding to Figure 4 and shows a second comparative example tire 1b. In tire 1b in Figure 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 approximately rectangular, the same as in the configuration shown in Figure 4.

On the other hand, both side surfaces of each protrusion 50b in the main tire rotation direction are inclined from the inside to the outside in the tire radial direction toward the front of the main tire rotation direction (the direction of arrow α) relative to the tire radial direction. That is, in comparative tire 1b, the direction in which each protrusion 5 is inclined relative to the tire radial direction is opposite to that in the embodiment of Figure 4 . In this comparative example, unlike the embodiment of Figure 4 , in the lower part of Figure 5B, the protrusions 50 tend to be positioned closer to being upright in the vertical direction, as in the protrusion 50 indicated by F1. Therefore, compared to the embodiment of Figure 4 , the effect of the protrusions 50 guiding air to facilitate smooth flow to the rear of the tire is reduced.

Furthermore, at the upper part of tire 1b, as shown by the protrusions 50 indicated by F2, the air tends to be guided by the protrusions 50 from the outside to the inside in the tire radial direction, but the air flow and the direction of travel of the upper protrusions 50 face each other and collide. As a result, compared to the embodiment in Figure 4, the effect of guiding the air with the protrusions 50 to facilitate smooth flow to the rear of the tire is reduced.

The embodiment shown in Figures 1 to 4 above is more effective than the comparative example in guiding air with the protrusions 50 and making it easier for the air to flow smoothly behind the tire.

Figure 6 is a diagram corresponding to Figure 4 and shows a tire 1c according to another embodiment. In this tire 1c, 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, too, 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 (direction of arrow α). The first side surface 51 is inclined at an angle θ5 relative to the tire radial direction.

On the other hand, the second side surface 53, located at the forefront of the front side surface in the tire's main rotation direction, is also inclined from the inside to the outside in the tire's radial direction toward the rear in the tire's main rotation direction (the direction of arrow α) relative to the tire's radial direction. The second side surface 53 is inclined at an angle θ6 relative to the tire's radial direction.

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 of the tire circumferential direction connecting the short and long sides of the trapezoid that forms top surface S4 can be increased. This makes it easier to increase the area of both sides of protrusion 50c in the tire circumferential direction. This increases the effectiveness of protrusion 50c in turbulentizing the 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.

In the above embodiments, the shape of the top surface of the protrusion 50 when viewed from the outside in the tire width direction is rectangular or trapezoidal, but this 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 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, the top surface of the protrusion may be in various shapes, such as other polygons.

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

Specifically, each protrusion 50d includes an intermediate height surface 54 that has 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 the maximum height surface. A step surface 61 is formed on the front side 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.

As shown in Figure 8, when the top surface S4, which is the tire widthwise outer end of the convex element 60, is viewed from the outside in the tire width direction, the top surface S4 is approximately rectangular. Figures 7 and 8 show a case where the tire radial outer end of the convex element 60 is positioned further inward in the tire radial direction than the tire radial outer end of the intermediate height surface 54, but the tire radial outer end of the convex element 60 and the tire radial outer end of the intermediate height surface 54 may also be aligned in the tire radial direction.

Furthermore, as shown in FIG. 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 from the inside to the outside in the tire radial direction toward the rear side in the tire main rotation direction. The fourth side surface 63 is part or all of the step surface 61.

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 to a predetermined side relative to the tire radial direction in the 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 it may have a curved portion or unevenness formed in part.

In the example shown in Figure 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 relative to the tire radial direction is aligned with the inclination direction of the third side surface 62 of the convex element 60 relative to the tire radial direction.

The front side surface of each convex element 60 in the tire main rotation direction may have a fourth side surface 63 that is inclined to a predetermined side relative to the tire radial direction as described above, in a 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 curved portion or unevenness formed in part.

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 greater and 70 degrees or less. Angles θ7 and θ8 are preferably 30 degrees or greater and 60 degrees or less, and more preferably 40 degrees or greater and 50 degrees or less. It is even more preferable that angles θ7 and θ8 are approximately 45 degrees.

In this configuration, 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 circumferential side surfaces of the tire, is restricted in the same way 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.

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 set to 20 degrees or more and 70 degrees or less, which further improves the effectiveness of reducing air stagnation around the tire. In this example, the other configurations and functions are the same as those in Figures 1 to 4.

In addition, unlike the configurations shown in Figures 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, thereby having a second height surface. 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 of the convex element in the tire main rotation direction α, i.e., between the first side surface and the second side surface.

Alternatively, the first height surface of each protrusion may be configured to have a convex element protruding from the portion that extends inward in the tire circumferential direction from both the first side surface and the second side surface. In this case, the front and rear side surfaces of the convex element in the main tire rotation direction α each form two step surfaces between the first side surface and the second side surface.

In each of the above embodiments, protrusions 50, 50c, and 50d are formed only on the tire side surface facing outward in the vehicle width direction, but protrusions may be formed on the tire side surface on both sides in the tire width direction, so that the tire mounting direction is not specified.

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 Intermediate height surface, 60 Convex element, 61 Step surface, 62 Third side surface, 63 Fourth side surface, T Ground contact edge.

Claims (2)

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. 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 .