Wheel

Abstract

This wheel comprises a plurality of barrel members and a wheel body. The barrel members each include: an outer shell part; a barrel shaft; a bearing part; a pair of receiving pieces each of which is provided with a through-hole into which the barrel shaft is inserted; and a pair of nuts each of which is provided with a screw groove and is attached to the screw thread of the barrel shaft on the outside of each of the pair of receiving pieces. The wheel body includes: a pair of plate parts that rotatably support the barrel shaft; and a body part that holds the pair of plate parts at an interval in the rotation axis direction of the wheel. Each of the pair of plate parts is provided with a groove part which is open on the outer diameter side and receives the barrel shaft.

Description

wheel

[0001] This application claims priority to Japanese Patent Application No. 2023-99154, filed on June 16, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] A wheel having a plurality of barrel members is disclosed (see, for example, Patent Document 1 or Patent Document 2).

[0003] JP 2020-26266 A JP 2021-146849 A

[0004] Wheels with multiple barrel members are required to operate stably when incorporated into a moving object as a Mecanum wheel. Furthermore, while multiple barrel members are incorporated into a wheel, there are cases where some of the barrel members need to be replaced. In such cases, good assembly ease is also required, allowing for easy attachment and detachment of the barrel members.

[0005] Therefore, one of the objects is to provide a wheel that can ensure stable operation and can be easily assembled.

[0006] A wheel according to the present disclosure includes multiple barrel members and a wheel body to which the multiple barrel members are attached on its outer periphery. The barrel members include an outer shell having a curved outer periphery whose diameter gradually increases from both longitudinal ends of the barrel member toward the center; a barrel shaft extending longitudinally and arranged to penetrate the outer shell in the longitudinal direction and having threads on both ends; a bearing portion for receiving a load applied to the barrel shaft; a pair of receivers each having a through hole into which the barrel shaft is inserted; and a pair of nuts each having a thread groove and attached to the threads of the barrel shaft outside the pair of receivers. The wheel body includes a pair of plate members each rotatably supporting the barrel shaft; and a main body portion holding the pair of plate members at a distance in the direction of the wheel's rotation axis. Each of the pair of plate members has a groove open to the outer diameter side and for receiving the barrel shaft.

[0007] According to the above wheel, stable operation can be ensured and assembly can be facilitated.

[0008] FIG. 1 is a schematic perspective view of a wheel according to a first embodiment of the present disclosure. FIG. 2 is a schematic side view of the wheel shown in FIG. 1. FIG. 3 is a schematic front view of the wheel shown in FIG. 1. FIG. 4 is a schematic rear view of the wheel shown in FIG. 1. FIG. 5 is a schematic cross-sectional view showing an enlarged portion of a wheel including one barrel member. FIG. 6 is a schematic cross-sectional view showing a state in which a nut and a receiver, which will be described later, have been removed from FIG. 5. FIG. 7 is an enlarged view of an area indicated by VII in FIG. 6. FIG. 8 is a schematic perspective view showing the appearance of a bearing unit. FIG. 9 is an exploded perspective view of the bearing unit shown in FIG. 8. FIG. 10 is a schematic perspective view showing a portion of a wheel during assembly. FIG. 11 is a view showing a state in which a structure is incorporated into a plate unit.

[0009] [Overview of the Embodiment] A wheel disclosed herein includes multiple barrel members and a wheel body to which the multiple barrel members are attached at its outer periphery. The barrel members include an outer shell having a curved outer periphery whose diameter gradually increases from both longitudinal ends of the barrel member toward the center; a barrel shaft extending longitudinally and arranged to penetrate the outer shell in the longitudinal direction and having threads at both ends; a bearing portion for receiving a load applied to the barrel shaft; a pair of receivers each having a through hole into which the barrel shaft is inserted; and a pair of nuts each having a thread groove and attached to the threads of the barrel shaft outside the pair of receivers. The wheel body includes a pair of plate members each rotatably supporting the barrel shaft; and a main body portion holding the pair of plate members at a distance in the direction of the wheel's rotation axis. Each of the pair of plate members has a groove open to the outer diameter side and for receiving the barrel shaft.

[0010] According to the wheel of the present disclosure, a barrel shaft with an attached outer shell can be supported on a pair of plate portions using a groove that accepts the barrel shaft. Because the groove is open toward the outer diameter of the wheel, the barrel shaft can be easily installed from the outer diameter of the wheel. After installing the barrel shaft, the barrel shaft attached to the pair of plate portions can be securely fixed by attaching a receiving device and tightening it with a nut. In this case, during wheel operation, a load acts on the barrel member in the inner diameter direction, but not in the outer diameter direction. Therefore, even if the plate portions have a groove, there is no problem in terms of strength. Therefore, while avoiding damage to the plate portion into which the receiving device is inserted, the retention by the receiving device and the nut can reliably prevent the barrel shaft from slipping out in the outer diameter direction. As a result, the wheel can be reliably prevented from falling off while ensuring stable operation. Furthermore, the barrel shaft can be easily removed from the outer diameter side of the wheel by removing the receiving device and the nut. In other words, there is no need for extensive disassembly, such as releasing all of the barrel shafts and removing one of the plate portions from the main body. Therefore, the barrel member can be easily replaced. As described above, such a wheel can ensure stable operation and can be easily assembled.

[0011] In the above-described wheel, the receiver may include a small-diameter region including one end in the longitudinal direction and a large-diameter region including the other end in the longitudinal direction and having an outer diameter larger than that of the small-diameter region. The plate portion may be provided with a fitting recess recessed in the longitudinal direction from the outer surface and including a groove portion. The small-diameter region may be fitted into the fitting recess. In this manner, the receiver can be fixed to the plate portion by fitting the small-diameter region of the receiver into the fitting recess. Therefore, the barrel shaft can be supported more stably, ensuring smoother rotation of the barrel member.

[0012] In the above-described wheel, the wall surfaces that define the grooves may be shaped to extend straight toward the outer diameter of the wheel. This allows the barrel shaft, with the outer shell and other components set, to be more smoothly inserted into the grooves from the outer diameter of the wheel, thereby further improving assembly.

[0013] In the above-described wheel, the barrel shaft may include a first region sandwiched between a pair of plate portions in the longitudinal direction and a second region located on both ends of the first region. The outer diameter of the first region may be larger than the outer diameter of the second region. The groove may receive the barrel shaft in the second region. This makes it easier to hook the first region onto the pair of plate portions in the longitudinal direction of the barrel shaft, making it easier to restrict longitudinal movement of the barrel shaft. This ensures more stable wheel operation.

[0014] In the wheel, the bearing portion may receive a radial load and a thrust load. This allows the bearing portion to properly receive the radial load and thrust load applied to the barrel shaft. This ensures more stable wheel operation.

[0015] In the wheel, the bearing portion may be a shell composite roller bearing including a shell outer ring. This allows the bearing that receives the radial load and the bearing that receives the thrust load to be integrated, improving the efficiency of mounting the bearing portion to the barrel shaft and reducing the number of parts. This further improves productivity.

[0016] In the above-described wheel, the shell composite roller bearing may include a ring member that also serves as one of the raceways that receives the thrust load. This allows the thrust load to be properly received by the ring member, thereby ensuring more stable wheel operation.

[0017] In the above-described wheel, the shell composite roller bearing may include a shell outer ring that constitutes an outer ring that receives radial loads. The shell outer ring may include a portion located on the outer periphery of the roller that receives thrust loads. In this way, the shell outer ring can integrate parts located on the outer diameter side of the bearing portion, thereby improving assembly efficiency. This further improves productivity.

[0018] In the wheel described above, the shell outer ring may have a thickness of 0.2 mm or more and 3.2 mm or less. This allows the shell outer ring to be efficiently manufactured by drawing or other processes while maintaining the rigidity required for a wheel component. This allows for improved productivity.

[0019] [Specific Example of Embodiment] Next, an example of a specific embodiment of the wheel of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0020] (Embodiment 1) First, embodiment 1, which is an embodiment of the present disclosure, will be described. Fig. 1 is a schematic perspective view showing a wheel in embodiment 1 of the present disclosure. Fig. 2 is a schematic side view of the wheel shown in Fig. 1. Fig. 3 is a schematic front view of the wheel shown in Fig. 1. Fig. 4 is a schematic rear view of the wheel shown in Fig. 1. In Fig. 1 and subsequent figures, the direction indicated by arrow Z is the rotational axis direction of the wheel, and the directions indicated by arrows X and Y are radial directions. The direction indicated by arrow X and the direction indicated by arrow Y are perpendicular to each other.

[0021] 1 to 4, the wheel 10a of the present disclosure is also referred to as a Mecanum wheel and is used, for example, as a wheel for a mobile object. By combining multiple Mecanum wheels and controlling the rotation speed and direction of each wheel, the mobile object can be moved in all directions without using a handle. Four wheels 10a are attached to the mobile object, for example, on the front, rear, left, and right sides. The size of the wheel 10a, for example, the length in the X direction in FIG. 2, is 150 mm.

[0022] The wheel 10a includes a plurality of barrel members 20a (ten in this embodiment) and a wheel body 11a to which the plurality of barrel members 20a are attached on the outer periphery. The wheel body 11a includes a pair of plate portions 12a, 13a and a main body portion 14a. Each of the plate portions 12a, 13a is disk-shaped and has a through-hole in the radial center. The plate portion 12a is provided with a support portion 15a that supports a barrel shaft 23a of the barrel member 20a (described later). Similarly, the plate portion 13a is provided with a support portion 16a that supports the barrel shaft. Each of the pair of plate portions 12a, 13a rotatably supports the barrel shaft. The main body portion 14a is cylindrical and has a plurality of mounting holes. The main body portion 14a holds the pair of plate portions 12a, 13a at a distance in the rotational axis direction (Z direction) of the wheel 10a. The main body portion 14a is connected to a driving source such as a motor (not shown). The wheel 10a rotates at a controlled rotation speed and in a controlled direction based on power transmitted from a motor or the like.

[0023] FIG. 5 is a schematic cross-sectional view showing an enlarged portion of a wheel 10a including one barrel member 20a. FIG. 5 corresponds to a cross-sectional view taken along the central axis of rotation of the barrel member 20a. FIG. 6 is a schematic cross-sectional view showing a state in which receivers 26a, 27a and nuts 28a, 29a, which will be described later, have been removed from FIG. 5. FIG. 7 is an enlarged view of the area indicated by VII in FIG. 6. FIG. 7 is a schematic cross-sectional view showing an enlarged bearing portion, which will be described later, in FIG. 6. In FIGS. 5, 6, and 7, the longitudinal direction of the barrel member 20a is indicated by the direction indicated by arrow L. The L direction is inclined at 45 degrees with respect to the Z direction.

[0024] Referring to Figures 5, 6, and 7, the barrel member 20a includes an outer shell 21a, a core 22a, a barrel shaft 23a, a pair of bearings 24a and 25a, a pair of receivers 26a and 27a, and a pair of nuts 28a and 29a. The outer shell 21a has a curved outer peripheral surface 31a. The diameter of the outer peripheral surface 31a gradually increases from both ends of the barrel member 20a in the longitudinal direction toward the center. That is, with regard to the diameter of the barrel member 20a, the diameter D1 is largest at the longitudinal center of the outer shell 21a of the barrel member 20a, and the diameter D2 is smallest at both ends of the outer shell 21a in the longitudinal direction (see Figure 6 in particular). In the cross-sections shown in Figures 5 and 6, the radius of curvature of the outer peripheral surface 31a of the outer shell 21a increases toward the longitudinal center. The outer shell 21a is a barrel-shaped member. The outer skin portion 21a has a hole 32a that penetrates in the longitudinal direction. The core portion 22a is disposed in the hole 32a. The outer skin portion 21a is attached so as to cover the core portion 22a. The longitudinal length of the outer skin portion 21a is longer than the longitudinal length of the core portion 22a.

[0025] The outer shell 21a has elasticity. Rubber or resin is selected as the material of the outer shell 21a. In this embodiment, the material of the outer shell 21a is urethane rubber. When resin is used as the material of the outer shell 21a, for example, POM (Polyoxymethylene) resin, PA (Polyamide) resin, or PEEK (PolyEther Ether Ketone) resin is used. The core 22a is made of a rigid member. For example, aluminum-based metal or steel is used as the material of the core 22a, and specifically, A5052 or A6063 is used.

[0026] The barrel shaft 23a is a round bar-shaped solid cylinder extending in the longitudinal direction. The barrel shaft 23a is disposed so as to penetrate the outer cover 21a in the longitudinal direction. Specifically, the barrel shaft 23a is disposed in a hole 33a that penetrates the core 22a in the longitudinal direction and is provided in the center of the core 22a. The outer peripheral surface 34a of the barrel shaft 23a contacts the inner wall surface of the hole 33a. Both ends of the barrel shaft 23a protrude from both end faces of the outer cover 21a and the core 22a, respectively. Threads 35a, 36a are provided at both ends of the barrel shaft 23a. The regions where the threads 35a, 36a are provided are exposed from both end faces of the core 22a.

[0027] The barrel shaft 23a includes a first region 17a sandwiched between the pair of plate portions 12a, 13a in the longitudinal direction, and second regions 18a located on both ends of the first region 17a. The second regions 18a are provided as a pair spaced apart in the longitudinal direction. The boundaries between the first region 17a and the pair of second regions 18a are indicated by dashed lines in Figures 5 and 6. The outer diameter of the first region 17a is larger than the outer diameter of the second regions 18a. This configuration gives the barrel shaft 23a a so-called stepped configuration.

[0028] A pair of circumferential grooves 37a, 38a recessed toward the inner diameter are provided on the outer peripheral surface 34a of the barrel shaft 23a. The circumferential grooves 37a, 38a are spaced apart in the longitudinal direction. The circumferential grooves 37a, 38a are provided in the longitudinal boundary region between the first region 17a and the second region 18a. The circumferential grooves 37a, 38a are used as relief grooves when forming a stepped structure on the barrel shaft 23a. The circumferential grooves 37a, 38a are provided closer to the center in the longitudinal direction than the threads 35a, 36a. In this embodiment, the circumferential grooves 37a, 38a are provided so as to align with both end surfaces of the outer cover portion 21a in the longitudinal direction.

[0029] Next, the configurations of the receiver 26a and the nut 28a will be described. The configuration of the receiver 27a is similar to that of the receiver 26a, so a description thereof will be omitted. Also, the configuration of the nut 29a is similar to that of the nut 28a, so a description thereof will be omitted.

[0030] The receiver 26a is a component also referred to as a collar and is made of aluminum. However, the receiver 26a may also be made of steel. The receiver 26a includes a small-diameter region 41a that includes one longitudinal end and a large-diameter region 42a that includes the other longitudinal end and has an outer diameter larger than that of the small-diameter region 41a. The receiver 26a is a hollow cylindrical member with a flange formed on one end that extends outward. The receiver 26a has a through-hole 43a that penetrates in the axial direction. The barrel shaft 23a is inserted into this through-hole 43a. The receiver 26a is attached to the barrel shaft 23a so that the small-diameter region 41a faces inward, i.e., toward the center of the barrel shaft 23a. The barrel shaft 23a is inserted into the through-hole 43a so that the large-diameter region 42a faces the longitudinal end where the thread 35a is formed, and the receiver 26a is attached to the barrel shaft 23a. Similarly, for the receiver 27a, the barrel shaft 23a is inserted into the through hole 43a so that the large diameter region 42a faces the other longitudinal end side where the thread 36a is formed, and the receiver 27a is attached to the barrel shaft 23a.

[0031] Nut 28a has a thread groove 47a formed on the inner wall surface defining hole 46a. The outer shape of the head of nut 28a is hexagonal when viewed in the longitudinal direction. Nut 28a is attached by rotating nut 28a outside of receiver 27a and tightening thread groove 47a onto thread 35a provided on the end of barrel shaft 23a. Nut 29a is similarly attached by rotating nut 29a outside of receiver 27a and tightening thread groove 47a onto thread 36a provided on the end of barrel shaft 23a.

[0032] Here, the configuration of the bearing portion 24a will be described. The configuration of the bearing portion 25a is similar to that of the bearing portion 24a, and therefore the description thereof will be omitted.

[0033] Fig. 8 is a schematic perspective view showing the appearance of bearing portion 24a. Fig. 9 is an exploded perspective view of bearing portion 24a shown in Fig. 8. For ease of understanding, the direction in which bearing portion 24a is attached is indicated by arrow L shown in Figs. 5 to 7. Referring to Figs. 8 and 9 together, bearing portion 24a receives radial loads and thrust loads. Bearing portion 24a is a shell composite roller bearing 50a including a shell outer ring 55a, which will be described later.

[0034] The shell composite roller bearing 50a includes a plurality of first rollers 51a, a plurality of second rollers 52a, a first cage 53a that holds the plurality of first rollers 51a, a second cage 54a that holds the plurality of second rollers 52a, a shell outer ring 55a, a bearing ring 56a, and a ring member 57a. The first rollers 51a receive radial loads. The second rollers 52a receive thrust loads. The bearing ring 56a and the ring member 57a are bearing rings that contact the rolling surfaces of the second rollers 52a and receive thrust loads.

[0035] Next, the configuration of the shell outer ring 55a will be briefly described. The shell outer ring 55a includes a first cylindrical portion 61a, a second cylindrical portion 62a, a bottom portion 63a, and a flange portion 64a. The bottom portion 63a has a hole 65a into which the barrel shaft 23a is inserted. The first cylindrical portion 61a and the second cylindrical portion 62a are each hollow cylindrical. The outer diameter of the second cylindrical portion 62a is larger than the outer diameter of the first cylindrical portion 61a. A plurality of first rollers 51a that receive a radial load are disposed on the inner diameter side of the first cylindrical portion 61a. The first rollers 51a roll on the outer peripheral surface 34a of the barrel shaft 23a and the inner peripheral surface of the first cylindrical portion 61a as their raceway surfaces. The flange portion 64a is disc-shaped and extends from one axial end of the first cylindrical portion 61a toward the outer diameter. The flange 64a is provided to connect one axial end of the first cylindrical portion 61a to the other axial end of the second cylindrical portion 62a. A plurality of second rollers 52a that receive a thrust load are arranged on the inner diameter side of the second cylindrical portion 62a.

[0036] The thickness T of the shell outer ring 55a is 0.2 mm or more and 3.2 mm or less. In this embodiment, the thickness T of the shell outer ring 55a is 0.5 mm. The shell outer ring 55a is formed as a single piece. The shell outer ring 55a is manufactured, for example, by drawing a steel plate.

[0037] The bearing ring 56a includes a disk-shaped portion 67a with a central hole 66a and a flange portion 68a extending in the thickness direction from the edge of the hole 66a. The bearing ring 56a is attached by inserting the barrel shaft 23a into the hole 66a. The ring member 57a is disk-shaped and has a hole 69a at its radial center that penetrates the thickness direction. The ring member 57a is disposed in the shell composite roller bearing 50a with the barrel shaft 23a inserted into the hole 66a so as to contact the flange portion 64a. The second roller 52a rolls on one surface of the bearing ring 56a and the other surface of the ring member 57a as raceways.

[0038] In this embodiment, the outer end face of the shell composite roller bearing 50a (bearing portion 24a), in this case, the end face 58a of the raceway ring 56a opposite the raceway surface, is aligned with the position of the circumferential groove 37a on the outer circumferential surface 34a of the barrel shaft 23a. The same is true for bearing portion 25a. When adjusting for longitudinal gaps due to manufacturing errors, etc., a spring washer or a simple washer may be placed in contact with end face 58a.

[0039] Next, the configuration of the wheel body 11a will be described again. The pair of plate portions 12a, 13a are provided with grooves 71a, 72a, respectively, that receive the barrel shaft 23a. In this embodiment, the grooves 71a, 72a each receive the barrel shaft 23a in the second region 18a. The groove 71a is provided in a support portion 15a provided on the outer periphery of the plate portion 12a. The groove 72a is provided in a support portion 16a provided on the outer periphery of the plate portion 13a. The grooves 71a, 72a each have a shape that opens toward the outer diameter side. In this embodiment, the wall surfaces 73a, 74a that constitute the groove 71a have a shape that extends straight toward the outer diameter side of the wheel 10a (see particularly FIG. 11 , which will be described later). The grooves 71a, 72a are provided at positions such that the central axis of the barrel shaft 23a, i.e., the central axis of rotation of the barrel member 20a, is inclined at 45 degrees with respect to the rotation axis direction (Z direction) of the wheel 10a. That is, ten grooves 71a, 72a are formed in the support portions 15a, 16a of the pair of plate portions 12a, 13a so that the central axes of rotation of the barrel shafts 23a of the ten barrel members 20a are inclined at 45 degrees each.

[0040] Furthermore, the plate portion 12a is provided with a fitting recess 76a that is recessed in the longitudinal direction from the outer surface 75a and includes the groove 71a. The fitting recess 76a has an annular recessed shape. Specifically, the fitting recess 76a is shaped to receive the small diameter region 41a of the receiver 26a. The small diameter region 41a of the receiver 26a is fitted into the fitting recess 76a. The plate portion 13a is provided with a fitting recess 78a that is recessed in the longitudinal direction from the outer surface 77a and includes the groove 72a. The fitting recess 78a has an annular recessed shape. Specifically, the fitting recess 78a is shaped to receive the small diameter region 41a of the receiver 27a. The small diameter region 41a of the receiver 27a is fitted into the fitting recess 78a. Each of the plate portions 12a, 13a has ten fitting recesses 76a, 78a formed therein, which correspond to the ten barrel members 20a.

[0041] Next, a method for assembling the wheel 10a having such a configuration will be briefly described. Figure 10 is a schematic perspective view showing a portion of the wheel 10a during assembly. Referring also to Figure 10, first, a structure 79a is prepared in a state in which the receivers 26a, 27a and nuts 28a, 29a have been removed, i.e., the outer shell 21a, core 22a, barrel shaft 23a, and bearings 24a, 25a are assembled. In this structure 79a, both ends of the barrel shaft 23a protrude in the longitudinal direction.

[0042] Then, both ends of the barrel shaft 23a protruding in the longitudinal direction are inserted into the grooves 71a and 72a. FIG. 11 is a diagram showing the state in which the structure 79a is assembled into the plate portion 12a. Referring also to FIG. 11, in this case, the central axis of the barrel shaft 23a is inclined 45 degrees with respect to the Z direction. Because the grooves 71a and 72a are open to the outer diameter side, the barrel shaft 23a can be easily inserted from the outer diameter side, as indicated by the arrows. Next, the receivers 26a and 27a are attached from both sides in the longitudinal direction. Specifically, one end of the barrel shaft 23a is inserted into the through-hole 43a from the small diameter region 41a side of the receiver 26a, and the other end of the barrel shaft 23a is inserted into the through-hole 43a from the small diameter region 41a side of the receiver 27a. At this time, the small diameter regions 41a of the receivers 26a and 27a are fitted into the fitting recesses 76a and 78a provided in the plate portions 12a and 13a, respectively. In this manner, the receivers 26a and 27a are attached to the barrel shaft 23a. Finally, nuts 28a and 29a are attached to both ends of the barrel shaft 23a. The nuts 28a and 29a are rotated and tightened to secure the barrel member 20a to the pair of plate portions 12a and 13a. In this manner, all ten barrel members 20a are secured to the plate portions 12a and 13a, and the wheel 10a is assembled.

[0043] When removing the barrel member 20a, the process is reversed. That is, the nuts 28a, 29a are rotated in the reverse direction to remove them from both ends of the barrel shaft 23a. This releases the barrel member 20a from the plate portions 12a, 13a. Next, the receivers 26a, 27a are moved in the longitudinal direction to remove them. Since the barrel shaft 23a remains inserted in the grooves 71a, 72a, the structure 79a including the barrel shaft 23a is then moved radially outward to remove it.

[0044] According to the wheel 10a, the barrel shaft 23a, to which the outer shell 21a is attached, can be supported by the pair of plate portions 12a, 13a using the grooves 71a, 72a that receive the barrel shaft 23a. Because the grooves 71a, 72a are open toward the outer diameter side of the wheel 10a, the barrel shaft 23a can be easily installed from the outer diameter side of the wheel 10a. After installing the barrel shaft 23a, the barrel shaft 23a attached to the pair of plate portions 12a, 13a can be securely fixed by attaching the receivers 26a, 27a and tightening them with nuts 28a, 29a. In this case, during operation of the wheel 10a, a load acts on the barrel member 20a in the inward direction, but not in the outward direction. Therefore, the presence of the grooves 71a, 72a in the plate portions 12a, 13a does not pose a strength problem. Therefore, while avoiding damage to the plate portions 12a, 13a into which the receiving devices 26a, 27a are inserted, the retention by the receiving devices 26a, 27a and the nuts 28a, 29a reliably prevents the barrel shaft 23a from coming loose in the longitudinal direction. As a result, the stable operation of the wheel 10a is ensured while the barrel shaft 23a is reliably prevented from falling off. Furthermore, by removing the receiving devices 26a, 27a and the nuts 28a, 29a, the barrel shaft 23a can be easily removed from the outer diameter side of the wheel 10a. In other words, there is no need for extensive disassembly, such as releasing the fixation of all the barrel shafts 23a and removing one of the plate portions 12a from the main body portion 14a. Therefore, the barrel member 20a can be easily replaced. As described above, this wheel 10a ensures stable operation and facilitates assembly.

[0045] In this embodiment, the receivers 26a, 27a include a small-diameter region 41a that includes one longitudinal end and a large-diameter region 42a that includes the other longitudinal end and has a larger outer diameter than the small-diameter region 41a. The plate portions 12a, 13a are provided with mating recesses 76a, 78a that are recessed longitudinally from the outer surfaces 75a, 77a and include the grooves 71a, 72a. The small-diameter region 41a is fitted into the mating recesses 76a, 78a. Therefore, the small-diameter region 41a of the receivers 26a, 27a is fitted into the mating recesses 76a, 78a, thereby fixing the receivers 26a, 27a to the plate portions 12a, 13a. This provides more stable support for the barrel shaft 23a and ensures smoother rotation of the barrel member 20a.

[0046] In this embodiment, the wall surfaces 73a and 74a that define the grooves 71a and 72a extend straight toward the outer diameter of the wheel 10a. This allows the barrel shaft 23a, with the outer shell 21a and other components set therein, to be more smoothly inserted into the grooves 71a and 72a from the outer diameter of the wheel 10a. This further improves assembly.

[0047] In this embodiment, the barrel shaft 23a includes a first region 17a sandwiched between the pair of plate portions 12a, 13a in the longitudinal direction, and a second region 18a located on both ends of the first region 17a. The outer diameter of the first region 17a is larger than the outer diameter of the second region 18a. The grooves 71a, 72a receive the barrel shaft 23a in the second region 18a. This makes it easier to hook the first region 17a onto the pair of plate portions 12a, 13a in the longitudinal direction of the barrel shaft 23a, making it easier to restrict longitudinal movement of the barrel shaft 23a. This ensures more stable operation of the wheel 10a.

[0048] In this embodiment, the bearings 24a and 25a receive radial and thrust loads. Therefore, the radial and thrust loads applied to the barrel shaft 23a can be appropriately received by the bearings 24a and 25a. This ensures more stable operation of the wheel 10a.

[0049] In this embodiment, the bearings 24a, 25a are shell composite roller bearings 50a that include a shell outer ring. Therefore, the bearings that receive radial loads and the bearings that receive thrust loads are integrated, which improves the efficiency of mounting the bearings 24a, 25a to the barrel shaft 23a and reduces the number of parts, thereby further improving productivity.

[0050] In this embodiment, the shell composite roller bearing 50a includes a ring member 57a that also serves as one of the raceways that receives the thrust load. This allows the ring member 57a to properly support the thrust load, thereby ensuring more stable operation of the wheel 10a.

[0051] In this embodiment, the shell composite roller bearing 50a includes a shell outer ring 55a that constitutes the outer ring that receives radial loads. The shell outer ring 55a includes a portion located on the outer peripheral side of the roller (second roller 52a) that receives thrust loads. Therefore, the shell outer ring 55a allows the parts located on the outer diameter side of the bearing portions 24a and 25a to be integrated, improving assembly efficiency and further improving productivity.

[0052] In this embodiment, the thickness T of the shell outer ring 55a is 0.2 mm or more and 3.2 mm or less. This allows the shell outer ring 55a to be efficiently manufactured by drawing or other processes while maintaining the rigidity required for a component of the wheel 10a. This improves productivity.

[0053] While the bearing portion includes a ring member in the above embodiment, the bearing portion may not include a ring member. In this case, for example, the flange of the shell outer ring may be used as one of the raceways that receives the thrust load.

[0054] In the above embodiment, the bearing portion is a shell composite roller bearing, but the bearing portion is not limited to this, and may be configured as a combination of a radial bearing that receives radial loads and a thrust bearing that receives thrust loads. Also, one of the bearings may be configured as a sliding bearing without including rolling elements such as rollers.

[0055] The present invention is intended to cover a wide range of applications, including those related to the present invention, including those related to the present invention.

[0056] 10a Wheel, 11a Wheel body, 12a, 13a Plate portion, 14a Main body portion, 15a, 16a Support portion, 17a First region, 18a Second region, 20a Barrel member, 21a Outer shell portion, 22a Core portion, 23a Barrel shaft, 24a, 25a Bearing portion, 26a, 27a Receiver, 28a, 29a Nut, 31a, 34a Outer circumferential surface, 32a, 33a, 46a, 65a, 66a, 69a Hole, 35a, 36a Thread, 37a, 38a Circumferential groove, 41a Small diameter region, 42a Large diameter region, 43a Through hole, 47a Thread groove, 50a Shell composite roller bearing, 51a First roller, 52a Second roller, 53a First cage, 54a Second cage, 55a: shell outer ring, 56a: raceway ring, 57a: ring member, 58a: surface, 61a: first cylindrical portion, 62a: second cylindrical portion, 63a: bottom portion, 64a, 68a: flange portion, 67a: disc portion, 71a, 72a: groove portion, 73a, 74a: wall surface, 75a, 77a: outer surface, 76a, 78a: mating recess, 79a: structure.

Claims

1. A wheel comprising: a plurality of barrel members; and a wheel body to which the plurality of barrel members are attached on its outer periphery, wherein the barrel members each include: an outer skin portion formed of a curved surface and having an outer periphery whose diameter gradually increases from both longitudinal ends of the barrel member towards the center; a barrel shaft extending in the longitudinal direction and arranged to penetrate the outer skin portion in the longitudinal direction, and having threads on both ends; a bearing portion for receiving a load applied to the barrel shaft; a pair of receivers each having a through hole into which the barrel shaft is inserted; and a pair of nuts each having threads and attached to the threads of the barrel shaft outside the pair of receivers; and the wheel body includes: a pair of plate portions each rotatably supporting the barrel shaft; and a main body portion holding the pair of plate portions at a distance in the direction of the rotation axis of the wheel, and each of the pair of plate portions having a groove portion open to the outer diameter side and for receiving the barrel shaft.

2. A wheel as set forth in claim 1, wherein the receiver includes a small diameter region including an end on one side in the longitudinal direction, and a large diameter region including an end on the other side in the longitudinal direction and having an outer diameter larger than that of the small diameter region, and the plate portion is provided with a fitting recess that is recessed from the outer surface in the longitudinal direction and includes the groove portion, and the small diameter region is fitted into the fitting recess.

3. A wheel according to claim 1 or claim 2, wherein the wall surfaces constituting the grooves extend straight toward the outer diameter side of the wheel.

4. A wheel as set forth in claim 1 or claim 2, wherein the barrel shaft includes, in the longitudinal direction, a first region sandwiched between the pair of plate portions and second regions located on both ends of the first region, the outer diameter of the first region being larger than the outer diameter of the second region, and the groove portion receives the barrel shaft in the second region.

5. A wheel according to claim 1 or 2, wherein the bearing portion receives a load in the radial direction and a load in the thrust direction.

6. The wheel of claim 5, wherein said bearing portion is a shell compound roller bearing including a shell outer ring.

7. A wheel according to claim 6, wherein said shell compound roller bearing includes a ring member that also serves as one of the raceways that receives a load in the thrust direction.

8. A wheel according to claim 6, wherein the shell composite roller bearing includes a shell outer ring constituting an outer ring that receives the radial load, and the shell outer ring includes a portion located on the outer peripheral side of the roller that receives the thrust load.

9. The wheel of claim 8, wherein the thickness of the outer shell ring is equal to or greater than 0.2 mm and equal to or less than 3.2 mm.

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