Wheels with covers

Abstract

Wheels with covers that reduce air resistance while riding. [Solution] A wheel with a cover comprises a wheel for a vehicle, having a cylindrical rim, a circular hub mounting portion located on the inner circumference of the rim and attached to an axle hub, and an annular disc surrounding the hub mounting portion and having a raised portion that protrudes on the axial front side of the wheel relative to the hub mounting portion; a disc-shaped center cover that covers at least a part of the hub mounting portion and the raised portion, with its front surface having a curved surface that is recessed toward the back side of the wheel; and an annular ring cover that covers at least a part of the flange portion and the raised portion of the rim, having a first curved surface whose inclination angle with respect to a virtual plane perpendicular to the central axis increases as it moves from the flange portion toward the central axis of the wheel, and a second curved surface whose inclination angle with respect to the virtual plane decreases as it moves from the first curved surface toward the central axis.

Description

Technical Field

[0001] The technology disclosed in the present specification relates to a wheel with a cover.

Background Art

[0002] Conventionally, wheels with a cover are known. A wheel with a cover includes a vehicle wheel and a wheel cover. The wheel cover has an annular ring cover that covers the outer peripheral edge of the surface of the wheel (the surface on the side opposite to the vehicle body), and a circular center cover that covers the central portion of the surface of the wheel. (For example, refer to Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventional wheels with a cover can reduce turbulence in the air flow (hereinafter sometimes referred to as "air flow") when a vehicle travels, but there is still room for improvement.

[0005] The present specification discloses a technology capable of solving at least part of the problems described above.

Means for Solving the Problems

[0006] The technology disclosed in the present specification can be implemented in the following modes.

[0007] (1) A wheel with a cover disclosed herein comprises a wheel for a vehicle, comprising: a cylindrical rim; a circular disc disposed on the inner circumference side of the rim, having a hub mounting portion attached to an axle hub; an annular disc surrounding the hub mounting portion, and having a raised portion that rises on the axial front side of the wheel relative to the hub mounting portion; a center cover covering the hub mounting portion, wherein the front surface of the center cover has a curved surface recessed toward the back side of the wheel; and an annular ring cover covering from the flange portion of the rim to at least a part of the raised portion, having a first curved surface whose inclination angle with respect to a virtual plane perpendicular to the central axis increases as it moves from the flange portion toward the central axis of the wheel, and a second curved surface whose inclination angle with respect to the virtual plane perpendicular to the central axis decreases as it moves from the first curved surface toward the central axis. In this configuration, the wheel with a cover comprises a center cover and a ring cover, thereby suppressing turbulence in the airflow over the front side of the wheel with a cover. Furthermore, the curved surfaces of the center cover and the ring cover alter the airflow over the front of the covered wheel. This alteration of airflow then works to suppress the spread of turbulence in the airflow along the side of the vehicle in the vehicle width direction downstream of the airflow over the front of the covered wheel. Here, the spread of turbulence in the airflow along the side of the vehicle in the vehicle width direction correlates with a deterioration of air resistance during vehicle operation. Therefore, the covered wheel with this configuration can reduce the air resistance generated by vehicle operation.

[0008] (2) In the wheel with cover described above, the wheel may have a plurality of ventilation holes along the circumferential direction of the wheel on the radially outer inclined surface of the raised portion of the wheel, and the ring cover may cover a portion of the ventilation holes. With this configuration, by covering a portion of the ventilation holes of the wheel with the ring cover, the turbulence of the air around the wheel of the wheel with cover is less likely to spread in the vehicle width direction.

[0009] (3) In the wheel with cover described above, the surface of the outer edge portion of the ring cover may be configured to be parallel to the virtual plane. With this configuration, because the surface of the outer edge portion of the ring cover is parallel to the virtual plane, the turbulence of the air around the wheel of the wheel with cover is less likely to spread in the vehicle width direction.

[0010] (4) In the wheel with cover described above, the outer edge of the center cover may be positioned further back than the top of the raised portion. With this configuration, the outer edge of the center cover is positioned further back than the top of the raised portion, so that the air around the wheel of the wheel with cover does not spread out as much in the vehicle width direction. [Brief explanation of the drawing]

[0011] [Figure 1] Schematic diagram of a covered vehicle wheel in the first embodiment [Figure 2] Schematic diagram of the cross-section at position II-II in Figure 1. [Figure 3] Schematic diagram of the wheel in the first embodiment [Figure 4] Schematic diagram of the cross-section at position IV-IV in Figure 3. [Figure 5] Enlarged schematic diagram of section E1 in Figure 2 [Figure 6] Enlarged schematic diagram of section E2 in Figure 2 [Figure 7] An explanatory diagram showing the airflow of vehicle B equipped with a comparative configuration of wheels. [Figure 8] An explanatory diagram showing the airflow of vehicle B equipped with wheels according to the first embodiment. [Figure 9] An explanatory diagram showing the airflow of vehicle B equipped with wheels according to the second embodiment. [Figure 10] An explanatory diagram showing the airflow of vehicle B equipped with wheels according to the third embodiment. [Modes for carrying out the invention]

[0012] A. First Embodiment: A-1. Configuration of the covered vehicle wheel 10: Figure 1 is a schematic diagram of a covered vehicle wheel 10 (hereinafter referred to as "covered wheel 10") in the first embodiment. Figure 2 is a schematic diagram showing the cross-sectional configuration of the covered wheel 10 at position II-II in Figure 1. Each figure shows mutually orthogonal XYZ axes for specifying direction. For convenience in this specification, the Y-axis direction is the direction parallel to the central axis L1 of the covered wheel 10 (see Figure 2), and is hereinafter referred to as the "wheel axis direction." The positive Y-axis side is referred to as the "front side," and the negative Y-axis side is referred to as the "back side." When the covered wheel 10 is mounted on vehicle B (see Figure 7), the back side of the covered wheel 10 faces towards vehicle B, and the front side of the covered wheel 10 faces away from vehicle B. The radial direction of the covered wheel 10 is referred to as the "wheel radial direction." Of the wheel radial direction, the direction toward the central axis L1 is referred to as the "inside," and the direction away from the central axis L1 is referred to as the "outside." The direction around the central axis L1 of the covered wheel 10 is called the "wheel circumferential direction." The same applies to Figure 3 and subsequent figures. Note that the wheel 20 may actually be positioned in a different orientation than that described above.

[0013] As shown in Figure 1, the covered wheel 10 comprises a vehicle wheel 20 (hereinafter referred to as "wheel 20"), a center cover 300, and a ring cover 400. The center cover 300 and the ring cover 400 are located on the front side of the wheel 20. The center cover 300 is located on the central side of the wheel 20. The ring cover 400 is located on the outer edge side of the wheel 20. The center cover 300 and the ring cover 400 will be described in detail later.

[0014] A-2. Configuration of Wheel 20: Figure 3 is a schematic diagram of the wheel 20 in the first embodiment. Figure 4 is a schematic diagram showing the cross-sectional configuration at position IV-IV in Figure 3.

[0015] As shown in FIG. 3 and FIG. 4, the wheel 20 includes a rim 100 and a disk 200. The rim 100 has a cylindrical shape that opens in the wheel axial direction. The disk 200 has a circular shape when viewed in the wheel axial direction. The disk 200 is arranged inside the rim 100.

[0016] As shown in FIG. 4, the outer peripheral surface of the disk 200 is fitted to the inner peripheral surface of the rim 100. The rim 100 and the disk 200 are integrated by welding (for example, fillet welding). The wheel 20 of the first embodiment is a so-called two-piece type wheel. The material of the rim 100 and the disk 200 is, for example, steel.

[0017] (Rim 100) As shown in FIG. 4, the rim 100 includes a pair of flange portions 110A, 110B, a pair of bead seat portions 120A, 120B, and a drop portion 130.

[0018] The pair of flange portions 110A, 110B are substantially annular when viewed in the wheel axial direction (Y-axis direction). The pair of flange portions 110A, 110B are respectively located at both ends (front side and back side) of the rim 100 in the wheel axial direction. The pair of flange portions 110A, 110B maintain the positions of the wheel 20 and the tire T in the wheel axial direction (see FIG. 7).

[0019] The pair of bead seat portions 120A, 120B are arranged between the pair of flange portions 110A, 110B in the wheel axial direction (Y-axis direction). Specifically, the front-side bead seat portion 120A is adjacent to the back side of the front-side flange portion 110A. The back-side bead seat portion 120B is adjacent to the front side of the back-side flange portion 110B. The wheel 20 supports the tire T by bringing the bead portion of the tire T into contact with the outer peripheral surface of each of the bead seat portions 120A, 120B.

[0020] The drop portion 130 is positioned between a pair of bead seat portions 120A and 120B in the wheel axis direction (Y axis direction). When viewed in the circumferential direction of the wheel, the drop portion 130 is recessed inward in the wheel radial direction relative to each bead seat portion 120A and 120B.

[0021] (Disc 200) The disc 200 has a raised portion 210, a hub mounting portion 220, and a disc flange portion 230.

[0022] The hub mounting portion 220 is the part that is attached to the axle hub h of vehicle B and is located in the center of the disc 200 when viewed in the wheel axis direction (Y axis direction). As shown in Figure 3, the hub mounting portion 220 is, for example, a plate-shaped member that spreads out in a disc shape. The hub mounting portion 220 has a hub hole 222 at its center (central axis L1). In addition, multiple bolt holes 224 (five in the first embodiment) are formed around the hub hole 222 at equal intervals in the circumferential direction of the wheel. The axle hub h of vehicle B is inserted into the hub hole 222. Vehicle B and the wheel 20 are connected by fastening with bolts and nuts n (see Figure 7).

[0023] The disc flange portion 230 is located on the outer peripheral edge side of the disc 200. The disc flange portion 230 is cylindrical with an opening in the wheel axial direction. The outer peripheral surface of the disc flange portion 230 is fitted to the inner peripheral surface of the drop portion 130 of the rim 100 (see Figure 4).

[0024] As shown in Figures 3 and 4, the raised portion 210 is located between the hub mounting portion 220 and the disc flange portion 230. The raised portion 210 is an annular shape that surrounds the hub mounting portion 220. The raised portion 210 protrudes on the front side (positive Y-axis direction). The raised portion 210 has an inner circumference portion 212, a top portion 214, and an outer circumference portion 216.

[0025] As shown in Figure 4, the top portion 214 is located on the outermost side (positive Y-axis direction) of the raised portion 210. The top portion 214 is located on the outer side (positive Y-axis direction) of the hub mounting portion 220 and the disc flange portion 230. The top portion 214 is located on the outermost side of the disc 200. When viewed from the front side of the wheel 20, the top portion 214 is approximately annular (see Figure 3). The inner circumference portion 212 of the raised portion 210 is located inside the top portion 214. The surface of the inner circumference portion 212 is a part that has an inclined surface that slopes from the back side to the front side as it moves from the outer edge of the hub mounting portion 220 toward the top portion 214. The outer circumference portion 216 of the raised portion 210 is located outside the top portion 214. The surface of the outer circumference portion 216 is a part that has an inclined surface that slopes from the front side to the back side as it moves from the top portion 214 toward the disc flange portion 230.

[0026] As shown in Figure 3, the outer periphery 216 of the raised portion 210 has a plurality of ventilation holes 218 (20 in the first embodiment) formed at equal intervals in the circumferential direction of the wheel. The ventilation holes 218 are holes that penetrate the disc 200 from the front side to the back side. In the first embodiment, the shape of the ventilation holes 218 is, for example, circular when viewed in the axial direction of the wheel. However, the ventilation holes 218 may have other shapes. Specifically, the ventilation holes 218 may be elliptical or oval in shape.

[0027] A-3. Center cover 300: Figure 5 is an enlarged view of section E1 in Figure 2. In other words, Figure 5 is an enlarged view of the cross-sectional structure of the part of the covered wheel 10 to which the center cover 300 is attached.

[0028] The center cover 300 is a disc-shaped component. The center cover 300 is attached to the wheel 20 on its front side so as to cover the hub mounting portion 220 and the inner circumference 212 of the raised portion 210 of the wheel 20. Although not shown, any method can be used to attach the center cover 300, such as fastening with screws or bolts, fitting with clips, or bonding with adhesive.

[0029] The outer edge 300A (outer circumference) of the center cover 300 is located inside and on the back side of the top 214 of the raised portion 210, and does not come into contact with the raised portion 210 over its entire circumference.

[0030] The surface 300S of the center cover 300 is a concave surface that is recessed in the direction toward the back, and is a smooth curved surface. The angle between the surface 300S of the center cover 300 and a virtual surface (for example, virtual surface S1) perpendicular to the central axis L1 increases as you move outward (towards the outer edge 300A) from the center 300P of the center cover 300. The innermost position of the surface 300S of the center cover 300 coincides with the center 300P. The width in the wheel axial direction between the outer edge 300A and the center 300P (i.e., the depth of the recess in the surface 300S) is approximately 20 mm. This width can be freely set within the range where the center cover 300 does not interfere with the front side of the wheel 20 or with the bolts and nuts n.

[0031] A-4. Ring cover 400: Figure 6 is an enlarged view of section E2 in Figure 2. In other words, Figure 6 is an enlarged view of the cross-sectional structure of the portion of the covered wheel 10 to which the ring cover 400 is attached.

[0032] The ring cover 400 is an annular member. The ring cover 400 is attached to the wheel 20 on the front side of the wheel 20 so as to cover the flange portion 110A of the rim 100 and partially cover the outer circumference 216 of the raised portion 210 of the disc 200. Although not shown, any method can be used to attach the ring cover 400, such as fastening with screws or bolts, fitting with clips, or bonding with adhesive.

[0033] The outer edge 400A of the ring cover 400 is located on the front side of the flange portion 110A of the rim 100. The inner edge 400B of the ring cover 400 is located on the front side of the outer circumference 216 of the raised portion 210. In a view along the wheel axis, the ring cover 400 covers approximately 1 / 4 of the area of ​​each ventilation hole 218.

[0034] The surface 400S of the ring cover 400 is a curved surface in which the angle (an example of a "tilt angle") between the surface 400S and a virtual plane (e.g., virtual planes S2, S3) perpendicular to the central axis L1 changes as you move from the outer edge 400A to the inner edge 400B. On the outer surface 410S on the outer edge 400A side of surface 400S (an example of a "first curved surface"), the tilt angle gradually increases as you move from the outer edge 400A side to the inner edge 400B side. On the inner surface 420S on the inner edge 400B side of surface 400S (an example of a "second curved surface"), the tilt angle gradually decreases as you move from the outer edge 400A side to the inner edge 400B side. The tilt angle at the outer edge 400A of the outer surface 410S is zero, and the tangent to the outer edge 400A coincides with the virtual plane S2. The inclination angle at the inner edge 400B of the inner surface 420S is zero, and the tangent to the inner edge 400B coincides with the virtual surface S3.

[0035] A-5. Effects of the first embodiment:

[0036] Figure 7 is an explanatory diagram showing the airflow around wheel W0 when vehicle B, equipped with the comparative wheel W0, is in motion. Wheel W0 comprises a wheel 20 and a tire T mounted on the wheel 20, but does not have a center cover 300 or a ring cover 400. Figure 8 is an explanatory diagram showing the airflow around wheel W1 when vehicle B, equipped with wheel W1 of the first embodiment, is in motion. Wheel W1 comprises a covered wheel 10 of the first embodiment, in which a center cover 300 and a ring cover 400 are mounted on the wheel 20, and a tire T mounted on the wheel 20.

[0037] As shown in Figures 7 and 8, for explanatory purposes, the front areas of the wheel 20 are defined as the first area Ar1, the second area Ar2, and the third area Ar3. The first area Ar1 is the front area of ​​the wheel 20 from the front flange portion 110A to the front raised portion 210. The second area Ar2 is the front area of ​​the wheel 20, including the hub mounting portion 220 and the inner circumference portion 212 of the raised portion 210. The third area Ar3 is the front area of ​​the wheel 20 from the rear raised portion 210 to the rear flange portion 110A. Furthermore, the area of ​​the side of the tire and the side of the vehicle B behind the wheel 20 is defined as the fourth area Ar4.

[0038] When vehicle B is in motion, multiple complex airflows are generated around wheels W0 and W1, as viewed from the perspective of wheels W0 and W1. The main airflows are airflow F1, which flows towards the rear along the side of vehicle B (including the sides of wheels W0 and W1), and airflow F2, which flows from the wheel well side of vehicle B through the ventilation holes 218 of wheel 20 to the front side of wheel 20. Airflows other than F1 and F2 will not be explained. Airflows F1 and F2 merge in the third area Ar3 and flow into the fourth area Ar4. Vortices are generated in airflows F1 and F2 due to the difference in flow velocity caused by the shape of vehicle B and wheels W0 and W1. Vortices are also generated in airflows F1 and F2 due to the difference in velocity when they merge. Airflows F1 and F2 become turbulent airflows due to the vortices generated in this way, affecting the air resistance of the vehicle. In particular, the more the turbulent airflow flowing into Area 4 (Ar4) spreads in the width direction of the vehicle, the greater the air resistance of vehicle B tends to be.

[0039] When vehicle B equipped with the comparative wheel W0 is in motion, as shown in Figure 7, turbulence occurs in the airflow F1 flowing over the front side of the wheel 20. In the first area Ar1, the airflow F1 is turbulent because the change in the surface shape of the wheel 20 relative to the direction of airflow F1 is large from the flange portion 110A of the rim 100 to the raised portion 210 of the disc 200. In the second area Ar2, the airflow F1 is turbulent because the change in the surface shape of the wheel 20 relative to the direction of airflow F1 is large at the inner circumference portion 212 of the raised portion 210 of the disc 200. Also in the second area Ar2, the airflow F1 is turbulent because the bolts and nuts n protruding from the front side of the wheel 20 rotate around the central axis L1. In the third area Ar3, the airflow F1 is turbulent because the change in the surface shape of the wheel 20 relative to the direction of airflow F1 is large from the raised portion 210 of the disc 200 to the flange portion 110A of the rim 100. Furthermore, in the third area Ar3, the merging of airflows F1 and F2 causes turbulence. This turbulent airflow then spreads in the vehicle width direction in the fourth area Ar4.

[0040] When vehicle B equipped with the wheel W1 of the first embodiment is in motion, as shown in Figure 8, turbulence occurs in the airflow F1 flowing over the front side of the covered wheel 10. However, compared to the wheel W0 of the comparative embodiment, the wheel W1 of the first embodiment has a center cover 300 and a ring cover 400 attached, which reduces the change in the surface shape of the covered wheel 10 and results in a smoother surface shape relative to the airflow F1, thus reducing the turbulence of the airflow F1. Furthermore, in the third area Ar3 where airflows F1 and F2 merge, the ring cover 400 straightens the merged airflows (airflows F1 and F2), reducing the turbulence. This turbulent airflow then spreads in the vehicle width direction in the fourth area Ar4. However, compared to vehicle B equipped with the wheel W0 of the comparative embodiment, the turbulence is reduced, and therefore the extent to which the turbulent airflow spreads in the vehicle width direction in the fourth area Ar4 is also reduced.

[0041] Furthermore, in the wheel with cover 10 of the first embodiment, the surface 300S of the center cover 300 is a concave surface that is recessed in the direction toward the back, and is a smooth curved surface. Due to these shape characteristics, in the second area Ar2, the airflow F1 is drawn toward the center cover 300, and the way the airflow flows changes. As a result, the spread of turbulent airflow that spreads in the vehicle width direction in the fourth area Ar4 can be further suppressed.

[0042] Furthermore, in the wheel with cover 10 of the first embodiment, the surface 400S of the ring cover 400 has an outer surface 410S and an inner surface 420S, which are curved surfaces in which the angle between the surface 400S and a virtual plane perpendicular to the central axis L1 changes as it moves from the outer edge 400A to the inner edge 400B. Due to these shape features, in the first area Ar1, the airflow F1 is drawn towards the ring cover 400, changing the way the airflow flows, and in the third area Ar3 where airflow F1 and airflow F2 merge, the rectification effect is further enhanced. As a result, the spread of turbulent airflow that spreads in the vehicle width direction in the fourth area Ar4 can be further suppressed.

[0043] Analysis of the Cd value of vehicle B equipped with the wheel W1 of the first embodiment showed that it was approximately 2.5% lower than the Cd value of vehicle B equipped with the wheel W0 of the comparative embodiment. In the wheel 10 with cover of the first embodiment, the width in the wheel axis direction between the outer edge 300A of the center cover 300 and the center 300P was set to approximately 20 mm. However, it was observed that the smaller this width was, such as to 10 mm or 0 mm, the less likely the Cd value was to decrease.

[0044] B. Second Embodiment: The covered wheel 10A in the second embodiment includes a wheel 20 and a center cover 300 positioned on the wheel 20. However, it does not include a ring cover 400. The wheel 20 and the center cover 300 are the same as in the first embodiment. Therefore, in the second embodiment, the description of the wheel 20 and the center cover 300 is omitted.

[0045] Figure 9 is an explanatory diagram showing the airflow around the wheel W2 when a vehicle B equipped with the wheel W2 of the second embodiment is in motion. The wheel W2 comprises a covered wheel 10A of the second embodiment, in which a center cover 300 is attached to the wheel 20, and a tire T assembled to the wheel 20.

[0046] When vehicle B equipped with the wheel W2 of the second embodiment is in motion, as shown in Figure 9, turbulence occurs in the airflow F1 flowing over the front side of the covered wheel 10. However, compared to the wheel W0 of the comparative embodiment, the wheel W2 of the second embodiment has a center cover 300 attached, which reduces the change in the surface shape of the covered wheel 10A, resulting in a smoother surface shape relative to the airflow F1, and thus the turbulence of the airflow F1 is relatively small. This turbulent airflow then spreads in the vehicle width direction in the fourth area Ar4. However, compared to vehicle B equipped with the wheel W0 of the comparative embodiment, the turbulence of the airflow is smaller, and therefore the degree of spread of the turbulent airflow in the vehicle width direction in the fourth area Ar4 is also smaller.

[0047] Furthermore, in the wheel with cover 10A of the second embodiment, the surface 300S of the center cover 300 is a concave surface that is recessed in the direction toward the back, and is a smooth curved surface. Due to these shape characteristics, in the second area Ar2, the airflow F1 is drawn toward the center cover 300, and the way the airflow flows changes. As a result, the spread of turbulent airflow that spreads in the vehicle width direction in the fourth area Ar4 can be further suppressed.

[0048] Analysis of the Cd value of vehicle B equipped with the wheel W2 of the second embodiment showed that it was approximately 0.5% lower than the Cd value of vehicle B equipped with the wheel W0 of the comparative embodiment.

[0049] C. Third Embodiment: The covered wheel 10B in the third embodiment includes a wheel 20 and a ring cover 400 positioned on the wheel 20. On the other hand, it does not have a center cover 300. The wheel 20 and ring cover 400 are the same as in the first embodiment. Therefore, in the third embodiment, the description of the wheel 20 and ring cover 400 is omitted.

[0050] Figure 10 is an explanatory diagram showing the airflow around the wheel W3 when a vehicle B equipped with the wheel W3 of the third embodiment is in motion. The wheel W3 comprises a covered wheel 10B of the third embodiment, in which a ring cover 400 is attached to the wheel 20, and a tire T assembled to the wheel 20.

[0051] When vehicle B equipped with the wheel W3 of the third embodiment is in motion, as shown in Figure 10, turbulence occurs in the airflow F1 flowing over the front side of the covered wheel 10B. However, compared to the wheel W0 of the comparative embodiment, the wheel W3 of the third embodiment has a ring cover 400 attached, which reduces the change in the surface shape of the covered wheel 10B, resulting in a smoother surface shape relative to the airflow F1, thus reducing the turbulence of the airflow F1. Furthermore, in the third area Ar3 where airflows F1 and F2 merge, the ring cover 400 straightens the merged airflows (airflows F1 and F2), further reducing the turbulence. This turbulent airflow then spreads in the vehicle width direction in the fourth area Ar4. However, compared to vehicle B equipped with the wheel W0 of the comparative embodiment, the turbulence is reduced, and therefore the extent to which the turbulent airflow spreads in the vehicle width direction in the fourth area Ar4 is also reduced.

[0052] Furthermore, in the wheel with cover 10B of the third embodiment, the surface 400S of the ring cover 400 has an outer surface 410S and an inner surface 420S, which are curved surfaces in which the angle between the surface 400S and a virtual plane perpendicular to the central axis L1 changes from the outer edge 400A to the inner edge 400B. Due to these shape features, in the first area Ar1, the airflow F1 is drawn towards the ring cover 400, changing the way the airflow flows, and in the third area Ar3 where airflow F1 and airflow F2 merge, the rectification effect is further enhanced. As a result, the spread of turbulent airflow that spreads in the vehicle width direction in the fourth area Ar4 can be further suppressed.

[0053] Analysis of the Cd value of vehicle B equipped with the wheel W3 of the third embodiment showed that it was approximately 1% lower than the Cd value of vehicle B equipped with the wheel W0 of the comparative embodiment.

[0054] D. Variations: The technologies disclosed herein are not limited to the embodiments described above and can be modified in various forms without departing from their essence, for example, the following modifications are possible.

[0055] The configuration of the wheel 20 in the above embodiment is merely an example and can be modified in various ways.

[0056] In the above embodiment, the wheel 20 is described as a two-piece type wheel, but it is not limited to this. It may also be a so-called one-piece type wheel in which the wheel rim and wheel disc are integrally formed, or a so-called three-piece type wheel comprising a wheel rim composed of two parts, an outer rim and an inner rim, and a wheel disc. Furthermore, although the material of the wheel 20 is steel, it does not have to be steel. The material of the wheel 20 may also be aluminum.

[0057] In the above embodiment, the outer edge 300A of the center cover 300 extended to the inner circumference 212 of the raised portion 210 of the wheel 20, but it may also extend to the top portion 214 or the outer circumference 216.

[0058] In the above embodiment, the ring cover 400 covers about 1 / 4 of the ventilation holes 218 of the disc 200 in the wheel radial direction, but it may cover them completely or not. Also, the tangent to the outer surface 410S of the ring cover 400 and the virtual surface S2 coincide, but they do not have to coincide. For example, the angle between the tangent to the outer surface 410S and the virtual surface S2 may be greater than 0°. The tangent to the inner surface 420S and the virtual surface S3 coincide, but they do not have to coincide. For example, the angle between the tangent to the inner surface 420S and the virtual surface S3 may be greater than 0°. [Explanation of symbols]

[0059] 10, 10A, 10B: Wheel with cover 20: Wheel 100: Rim 110A, 110B: Flange section 120A, 120B: Bead seat section 130: Drop section 200: Disc 210: Raised section 212: Inner circumference section 214: Top section 216: Outer circumference section 218: Ventilation hole 220: Hub mounting section 222: Hub hole 224: Bolt hole 230: Disc flange section 300: Center cover 300A: Outer edge 300P: Center 300S: Surface 400: Ring cover 400A: Outer edge 400B: Inner edge 400S: Surface 410S: Outer surface 420S: Inner surface Ar1: Area 1 Ar2: Area 2 Ar3: Area 3 Ar4: Area 4 B: Vehicle F1: Airflow F2: Airflow L1: Central axis S1: Virtual plane S2: Virtual plane S3: Virtual plane T: Tire W0, W1, W2, W3: Wheel h: Axle hub n: Bolt and nut

Claims

1. Wheels with covers, A cylindrical rim, A circular disc disposed on the inner circumference side of the rim, having a hub mounting portion attached to the axle hub, and an annular portion surrounding the hub mounting portion and a raised portion that protrudes on the axial side of the wheel relative to the hub mounting portion, A wheel for a vehicle, equipped with, A disc-shaped center cover that covers the hub mounting portion and at least a part of the raised portion, wherein the front surface of the center cover has a curved surface that is recessed in the direction toward the back of the wheel, An annular ring cover that covers the flange portion and at least a part of the raised portion of the rim, the ring cover having a first curved surface whose inclination angle with respect to a virtual plane perpendicular to the central axis increases as it moves from the flange portion toward the central axis of the wheel, and a second curved surface whose inclination angle with respect to the virtual plane decreases as it moves from the first curved surface toward the central axis, Wheels with covers, equipped with the feature.

2. A wheel with a cover as described in claim 1, The wheel has a plurality of ventilation holes along the circumferential direction of the wheel on the radially outer inclined surface of the raised portion of the wheel. The ring cover covers a portion of the ventilation hole. Wheels with covers.

3. A wheel with a cover according to claim 1 or claim 2, The surface of the outer edge portion of the ring cover is parallel to the virtual plane. Wheels with covers.

4. A wheel with a cover as described in claim 1, The outer edge of the center cover is located in the direction toward the back side, relative to the top of the raised portion. Wheels with covers.

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