WHEEL SYSTEM

Abstract

Wheel assembly, which includes the following: - a main body (3) having a rotatable main body rotation area (34); - an intermediate element (4) with a ring-shaped form that surrounds the main body rotation area (34); - a tire (2) with a ring-shaped form that surrounds the intermediate element (4); - a first elastic body (51) designed to couple the intermediate element (4) and the tire (2) such that the intermediate element (4) is movable with respect to the tire (2) along a first imaginary straight line that is orthogonal to an axis of the intermediate element (4); - a second elastic body (61) designed to couple the intermediate element (4) and the main body rotation area (34) such that the intermediate element (4) is movable with respect to the main body (3) along a second imaginary line which is orthogonal to the axis of the intermediate element (4) and intersects the first imaginary line; and - a vibration damping structural unit (7) attached to the main body (3), wherein the vibration damping structural unit (7) has a weight (71) designed to be rotated in the same direction as the direction of rotation of the main body rotation range (34) at a speed twice that of the main body rotation range (34), and wherein, if a direction along the second imaginary line coincides with a vertical direction, a position of the center of mass (71a) of the weight (71) is located below a position of a rotation centerline of the weight (71).

Description

[0001] This invention relates to a wheel device with a tire having a ring-shaped form.

[0002] A wheel assembly is known that includes a drive unit housed within an annular tire for lowering the floor of a rail vehicle's body. In such a wheel assembly, according to the related technology, there is a tendency for an impact force to be transmitted from a rail to the drive unit via the tire when the rail vehicle is in motion. In particular, when the wheel assembly travels, for example, over a connection between two rows of rails, or when abnormal wear occurs on an outer circumferential surface of the tire, the impact force to which the drive unit within the tire is subjected increases. Thus, a defect in the drive unit of the wheel assembly according to the related technology can occur.

[0003] A wheel assembly has been proposed in which an intermediate element with an annular shape is arranged between a drive unit housed within a tire and the tire itself, in order to reduce the impact force transmitted from the tire to the drive unit. The intermediate element is connected to both the drive unit and the tire by a plurality of spring elements (see, for example, the list presented at the Japan Society of Mechanical Engineers, Dynamics and Design Conference 2019, Lecture number 520).

[0004] WO 2020 / 213 154 A1 describes a wheel assembly in which a rotatable section and an intermediate element are arranged coaxially with a tire. A first elastic plate couples the tire and the intermediate element. A second elastic plate couples the rotatable section and the intermediate element. If a straight line orthogonal to the tire's axis is defined as a first imaginary straight line, then the first elastic plate is arranged orthogonally to the first imaginary straight line. If a straight line orthogonal to the tire's axis and different from the first imaginary straight line is defined as a second imaginary straight line, then the second elastic plate is arranged orthogonally to the second imaginary straight line.

[0005] US 2010 / 0 319 569 A1 describes a drive unit for rail vehicles. More specifically, it comprises a gearbox housing held on an inner surface of a wheel and rotating integrally with the wheel; an input-side rotary element with eccentric parts connected to a drive source; rotary elements mounted to rotate relative to the eccentric parts to perform a rotary motion about an axis of rotation of the input-side rotary element; a rotation control element to prevent rotation of the rotary element while allowing its rotation; and a circumferential engagement element attached to the gearbox housing to rotate the gearbox housing at a reduced speed relative to the input-side rotary element by engaging with a circumference of the rotary elements.

[0006] In the wheel assembly described in "The Japan Society of Mechanical Engineers", Dynamics and Design Conference 2019, Lecture number 520, according to the related technique, a phenomenon occurs in which the intermediate element vibrates strongly relative to the tire; in particular, a "whirling" of the intermediate element occurs while the tire rotates. Consequently, the wheel assembly as a whole is more prone to vibration.

[0007] This invention has been designed to solve the problem described above, and the object of the invention is to provide a wheel device that enables the suppression of vibrations.

[0008] The problem underlying the invention is solved by a wheel device with the features of independent claim 1. Advantageous embodiments of the invention are specified in dependent claims 2 to 8.

[0009] The wheel assembly according to this invention enables the suppression of vibrations of the wheel assembly.

[0010] The drawings show in: Fig. 1 A front view illustrating a wheel assembly according to a first embodiment. Fig. 2 a sectional view along line II-II in Fig. 1. Fig. 3 a sectional view along line III-III in Fig. 1. Fig. 4 a front view to illustrate a gear mechanism according to Fig. 2. Fig. 5 a perspective view to illustrate a first elastic plate according to Fig. 1. Fig. 6 a perspective view to illustrate a state in which the first elastic plate according to Fig. 1 is attached to a tire. Fig. 7 a perspective view to show a second elastic plate according to Fig. 1. Fig. 8 a perspective view to illustrate a state in which the second elastic plate according to Fig. 1 is attached to an intermediate element. Fig. 9 a schematic view to represent a wheel assembly model, which is created by modeling the wheel assembly according to Fig. 1 will be received. Fig. 10 a front view to illustrate a state in which the wheel assembly is in accordance Fig. 1 moved on a rail. Fig. 11 a schematic view to represent a wheel assembly model, which is created by modeling the wheel assembly according to Fig. 10 will be received. Fig. 12 a front view to illustrate a state of the wheel assembly when the tire is in a rotational position that differs from a rotational position of the tire according to Fig. 10 differs, and he is subjected to an impact force from the rail. Fig. 13 a schematic view to represent a wheel assembly model, which is created by modeling the wheel assembly according to Fig. 12 will be received. Fig. 14 A schematic explanatory view to illustrate changes in the state of the wheel assembly when the wheel assembly moves according to Fig. 9 moved on a rail while rotating. Fig. 15 a graph to represent a relation between a rotational speed R [Hz] of each of the wheel devices in a comparison example A1, example B1 and example C1 and the time “t” [sec] in a numerical analysis. Fig. 16 a graph to represent a relation between a displacement D1 [mm] of a main body in the comparison example A1 in the Z-axis direction and the time “t” [sec] in the numerical analysis. Fig. 17 a graph to represent a relation between a displacement D1 [mm] of a main body in example B1 in the Z-axis direction and the time “t” [sec] in the numerical analysis. Fig. 18 a graph to represent a relation between a displacement D1 [mm] of a main body in example C1 in the Z-axis direction and the time “t” [sec] in the numerical analysis. Fig. 19 a sectional view to illustrate a wheel assembly according to a second embodiment. Fig. Figure 20 is a sectional view illustrating a wheel assembly according to a third embodiment. Fig. 21 a front view illustrating a wheel assembly according to a fourth embodiment. Fig. 22 a sectional view along line XXII-XXII in Fig. 21. Fig. 23 a sectional view to illustrate a wheel assembly according to a fifth embodiment. Fig. 24 a sectional view to illustrate a wheel assembly according to a sixth embodiment. Fig. 25 a sectional view to illustrate a wheel assembly according to a seventh embodiment.

[0011] Fig. Figure 1 is a front view of a wheel assembly according to a first embodiment. Fig. 2 is a sectional view along line II-II in Fig. 1. Fig. 3 is a sectional view along line III-III in Fig. 1. In the drawings, a wheel assembly 1 comprises a tire 2, a main body 3, an intermediate element 4, a first coupling structure unit 5, a second coupling structure unit 6, and a vibration damping structure unit 7. In this embodiment, a railway vehicle wheel assembly for attachment to the body of a railway vehicle is used as the wheel assembly 1.

[0012] The tire 2 has a ring-shaped form with an axis P at its center. Furthermore, an inner circumferential surface 21 of the tire 2 is a cylindrical surface with the axis P at its center. The tire 2 is made of a metal such as iron. The wheel assembly 1 is placed on a rail in a state where an outer circumferential surface of the tire 2 is in contact with the rail. The wheel assembly 1, placed on the rail, is moved along the rail according to the rotation of the tire 2.

[0013] The wheel assembly 1 is arranged such that the axis P of the tire 2 is aligned with a Y-axis in an orthogonal XYZ coordinate system, which is a fixed coordinate system. The orthogonal XYZ coordinate system is defined such that the Z-axis direction corresponds to a vertical direction and the Y-axis direction corresponds to a lateral direction of the vehicle body. On the Z-axis, a top surface is defined as the positive side in the vertical direction. On the Y-axis, an inside surface of the vehicle is defined as the positive side in the lateral direction.

[0014] The main body 3 is arranged within the tire 2. Under normal conditions, where no load such as the weight of the vehicle body is exerted on the wheel assembly 1, an axis of the main body 3 coincides with the axis P of the tire 2. In particular, the main body 3 is arranged coaxially with the tire 2. In this embodiment, if a direction along the axis P of the tire 2 is defined as an axial direction of the tire 2, a dimension of the main body 3 in the axial direction of the tire 2 is greater than a dimension of the tire 2 in the axial direction of the tire 2, as shown in Fig. 2 and Fig. 3 shown.

[0015] As in Fig. 2 and Fig. As shown in Figure 3, the main body 3 further comprises a fixed frame 31, a main shaft 32, a main body electric motor 33, a rotating frame 34 and a gear mechanism 35.

[0016] The fixed frame 31 is attached to the body of a rail vehicle. The fixed frame 31 is a plate-shaped element arranged orthogonally to the axis of the main body 3. A through-hole 311 is formed in the fixed frame 31.

[0017] The main shaft 32 is arranged coaxially with the axis of the main body 3. Furthermore, the main shaft 32 has a first end section 321 and a second end section 322. The first end section 321 is located on the positive side in the Y-axis direction with respect to the second end section 322. The first end section 321 is arranged in the through-hole 311. The first end section 321 is rotatably mounted on the fixed frame 31 by means of a bearing 301 installed in the through-hole 311.

[0018] The main body electric motor 33 and the gear mechanism 35 are arranged at positions between the first end region 321 and the second end region 322 in one direction along the axis of the main body 3, i.e., in the Y-axis direction. The main body electric motor 33 is arranged between the fixed frame 31 and the gear mechanism 35.

[0019] The main body electric motor 33 has a rotor 331 and a stator 332. The stator 332 has a ring-shaped form and serves as an armature, surrounding an outer circumference of the rotor 331. Thus, the main body electric motor 33 is an internal rotor type electric motor. The axes of the rotor 331 and the stator 332 coincide with the axis of the main body 3.

[0020] The rotor 331 is attached to an intermediate section of the main shaft 32, e.g., by a shrink fit. The intermediate section of the main shaft 32 is a section of the main shaft 32 located between the first end section 321 and the second end section 322.

[0021] The stator 332 is attached to the fixed frame 31. When electrical energy is supplied to the stator 332, the rotor 331 rotates integrally with the main shaft 32 about the axis of the main body 3 with respect to the fixed frame 31 and the stator 332. Consequently, the main body electric motor 33 generates a torque to rotate the rotating frame 34.

[0022] The rotary frame 34 is arranged as the main body's rotating section such that it runs coaxially to the axis of the main body 3. Furthermore, the rotary frame 34 is arranged to cover the main body's electric motor 33 and the gear mechanism 35. The rotary frame 34 has a cylindrical section 341 and a rotating plate section 342. The rotating plate section 342 is attached to the cylindrical section 341.

[0023] The cylindrical section 341 surrounds the main body electric motor 33 and the gear mechanism 35. An outer circumferential surface 344 of the cylindrical section 341 is a cylindrical surface with the axis of the main body 3 as its center point. The outer diameter of the cylindrical section 341 is smaller than the inner diameter of the tire 2. The cylindrical section 341 is rotatably mounted on the stator 332 by means of a bearing 302 mounted above an outer circumferential surface of the stator 332.

[0024] The rotary plate section 342 is positioned closer to the second end section 322 than the gear mechanism 35, specifically on a negative side in the Y-axis direction with respect to the gear mechanism 35. Furthermore, the rotary plate section 342 is arranged orthogonally to the axis of the main body 3. A through-hole 343 is formed in the rotary plate section 342, through which the main shaft 32 is inserted. The rotary plate section 342 is rotatably mounted on the main shaft 32 by means of a bearing 303 located in the through-hole 343. Consequently, the rotary frame 34 is rotatable about the axis of the main body 3 with respect to each of the following elements: the fixed frame 31, the stator 332, and the main shaft 32.

[0025] The gear mechanism 35 is arranged between the main body electric motor 33 and the turntable area 342. Furthermore, the gear mechanism 35 transmits the torque of the main body electric motor 33 to the turntable 34, such that the rotational speed of the turntable 34 is equal to half the rotational speed of the rotor 331. Consequently, when electrical energy is supplied to the stator 332, the turntable 34 rotates in the same direction as the rotor 331 at a speed equal to half the rotational speed of the rotor 331. The gear mechanism 35 is a planetary gear mechanism comprising a sun gear 351, a ring gear 352, and a plurality of planet gears 353.

[0026] Fig. Figure 4 is a front view illustrating the gear mechanism 35 according to Fig. 2. The sun gear 351 is attached to the intermediate piece of the main shaft 32, e.g. by a shrink fit. Consequently, the sun gear 351 is rotated integrally with the main shaft 32 and the rotor 331 about the axis of the main body 3.

[0027] The ring gear 352 is an annular gear that surrounds the sun gear 351. The ring gear 352 is arranged coaxially with the axis of the main body 3. Furthermore, the ring gear 352 is attached to the stator 332. Consequently, when the main shaft 32 is rotated relative to the stator 332, the sun gear 351 is rotated relative to the ring gear 352. In this embodiment, as shown in Fig. 2 and Fig. Figure 3 shows an outer diameter of the ring gear 352 equal to an outer diameter of the stator 332.

[0028] As in Fig. 2 and Fig. As shown in Figure 3, the cylindrical section 341 of the rotary frame 34 is rotatably mounted on the ring gear 352 by means of a bearing 304 mounted over an outer circumferential surface of the ring gear 352. In this embodiment, a ball bearing is used as each of the bearings 301 to 304. Each of the bearings 301 to 304 is not limited to a ball bearing and can, for example, also be a radial bearing.

[0029] The planet gears 353 are arranged between the sun gear 351 and the ring gear 352. In this embodiment, the transmission mechanism 35 has four planet gears 353. The planet gears 353 mesh with each of the sun gear 351 and the ring gear 352. When the sun gear 351 is rotated relative to the ring gear 352, the planet gears 353, acting as planet carriers, rotate around the axis of the main body 3 around the sun gear 351. Each of the planet gears 353 has a gear shaft 353a, a first gear section 353b, and a second gear section 353c.

[0030] One axis of the gear shaft 353a coincides with one axis of the planet gear 353. The gear shaft 353a is arranged parallel to the axis of the main body 3. Furthermore, the gear shaft 353a is rotatably mounted on the turntable area 342 of the rotary frame 34. Consequently, the rotational speed of the rotary frame 34 is equal to the orbital speed of each of the planet gears 353 with respect to the sun gear 351. The rotary frame 34, together with the planet gears 353, is rotated about the axis of the main body 3 synchronously with the orbital speed of the planet gears 353 with respect to the sun gear 351.

[0031] Each of the first gear section 353b and the second gear section 353c is an external gear with a plurality of teeth on an outer circumferential region. The first gear section 353b and the second gear section 353c are mounted on the gear shaft 353a. Consequently, the first gear section 353b is mounted coaxially with the second gear section 353c. The gear shaft 353a, the first gear section 353b, and the second gear section 353c are rotated integrally about the axis of the planet gear 353. The first gear section 353b and the second gear section 353c are arranged adjacent to each other in an axial direction along the gear shaft 353a.

[0032] The first gear section 353b is located in a position closer to the turntable section 342 than the second gear section 353c, i.e., on the negative side in the Y-axis direction with respect to the second gear section 353c. The first gear section 353b can be located in a position closer to the main body electric motor 33 than the second gear section 353c, i.e., on the positive side in the Y-axis direction with respect to the second gear section 353c.

[0033] The first gear section 353b is engaged with the ring gear 352. The second gear section 353c is engaged with the sun gear 351. The number of teeth of the first gear section 353b and the number of teeth of the second gear section 353c differ from each other. In this embodiment, the number of teeth of the first gear section 353b is greater than the number of teeth of the second gear section 353c.

[0034] The number of teeth for each of the sun gear 351, the ring gear 352, the first gear section 353b, and the second gear section 353c in the gear mechanism 35 is determined such that the rotational speed of the rotating frame 34 is equal to half the rotational speed of the main shaft 32. Specifically, the number of teeth for each of the sun gear 351, the ring gear 352, the first gear section 353b, and the second gear section 353c in the gear mechanism 35 is determined such that the gear ratio of the rotational speed of the rotating frame 34 to the rotational speed of the main shaft 32 is equal to 1 / 2. Consequently, when the rotor 331 completes one revolution integral with the main shaft 32, the rotating frame 34 completes half a revolution in the same direction as the rotation of the rotor 331 and the main shaft 32.

[0035] The number of teeth of the sun gear 351 is represented by z1, the number of teeth of the first gear section 353b by z2, the number of teeth of the second gear section 353c by z3, and the number of teeth of the ring gear 352 by z4. In this case, a gear ratio “i” of the rotational speed of the rotary frame 34 to the rotational speed of the main shaft 32, in particular a gear ratio “i” of the transmission mechanism 35, is expressed by the following expression (1). i=1 / ((z2 / z1)⋅(z4 / z3)+1)

[0036] If the number of teeth z2 of the first gear section 353b is equal to the number of teeth z3 of the second gear section 353c, i.e. the relation z2=z3 holds, the transmission ratio “i” of the rotational speed of the rotary frame 34 to the rotational speed of the main shaft 32 is expressed by the following expression (2). i=1 / ((z4 / z1)+1)

[0037] To specify the transmission ratio "i" as 1 / 2, a condition z1=z4 must be met in this case, in particular the condition that the number of teeth z1 of the sun gear 351 is equal to the number of teeth z4 of the ring gear 352. Therefore, the gear mechanism 35 is not feasible.

[0038] However, in this embodiment, the number of teeth of the first gear section 353b and the number of teeth of the second gear section 353c differ from each other. Consequently, the number of teeth z1 of the sun gear 351 can be specified as different from the number of teeth z4 of the ring gear 352. Thus, a gear mechanism 35 can be realized in which the gear ratio “i” of the rotational speed of the rotary frame 34 relative to the rotational speed of the main shaft 32 has the value 1 / 2.

[0039] As in Fig. As shown in Figure 1, the intermediate element 4 is an annular element that surrounds the rotating frame 34. The intermediate element 4 is arranged inside the tire 2. In particular, the tire 2 is an annular element that surrounds the intermediate element 4. In this embodiment, a wheel hub motor in which the main body 3, which includes the main body electric motor 33, is arranged inside the tire 2, corresponds to the wheel assembly 1. The intermediate element 4 is a separate element from both the tire 2 and the main body 3. In this embodiment, as shown in Figure 1, the intermediate element 4 is arranged inside the tire 2. Fig. 2 and Fig. As shown in Figure 3, the intermediate element 4 is located in the same position as a position of the tire 2 in the Y-axis direction, i.e. the axial direction of the tire 2.

[0040] Under natural conditions, where no load such as the weight of the vehicle body is exerted on the wheel assembly 1, an axis of the intermediate element 4 coincides with the axis P of the tire 2. In particular, the intermediate element 4 is arranged coaxially with the tire 2. Each of the inner circumferential surfaces 41 and 42 of the intermediate element 4 is a cylindrical surface with the axis of the intermediate element 4 as its center point. The outer diameter of the intermediate element 4 is smaller than the inner diameter of the tire 2. Furthermore, the inner diameter of the intermediate element 4 is larger than the outer diameter of the rotating frame 34. Thus, the intermediate element 4, with its annular shape, is arranged in a space between the tire 2 and the main body 3.

[0041] The first coupling structure unit 5 is arranged between the tire 2 and the intermediate element 4. Furthermore, the first coupling structure unit 5 has a pair of first elastic plates 51, which serve as the first elastic body that couples the tire 2 and the intermediate element 4 together.

[0042] The second coupling structure unit 6 is arranged between the intermediate element 4 and the rotating frame 34. Furthermore, the second coupling structure unit 6 has a pair of second elastic plates 61, which serve as a second elastic body that couples the intermediate element 4 and the rotating frame 34 together.

[0043] Now, each of the configurations of the pair of first elastic plates 51 and the pair of second elastic plates 61 is described on the basis of the orthogonal XYZ coordinate system, which is the fixed coordinate system described above, and an angle θ in a circumferential direction of the tire 2 with respect to a reference position A on the Z-axis of the orthogonal XYZ coordinate system.

[0044] As in Fig. As shown in Figure 1, if a special line of all lines perpendicular to the axis of the intermediate element 4 is designated as the first imaginary line, each of the pair of first elastic plates 51 is arranged in such a position that it intersects the first imaginary line. The first imaginary line coincides with a line extending in the x-axis direction. Furthermore, the pair of first elastic plates 51 is arranged in positions on the sides that are opposite each other with respect to the axis of the intermediate element 4 in a direction along the first imaginary line, i.e., in the x-axis direction.In particular, one of the pair of first elastic plates 51 is arranged at a position that is offset by θ = 90 degrees from the reference position A in the circumferential direction of the tire 2, and the other of the first elastic plates 51 is arranged at a position that is offset by θ = 270 degrees from the reference position A in the circumferential direction of the tire 2. The tire 2 is arranged coaxially to the intermediate element 4 such that the axis P of the tire 2 and the axis of the intermediate element 4 are located between the pair of first elastic plates 51.

[0045] Fig. Figure 5 is a perspective view of the first elastic plate 51 according to Fig. 1. Each of the first elastic plates 51 is a flat plate with a rectangular shape. A direction along the short sides of the rectangular shape of the first elastic plate 51 is defined as the width direction of the first elastic plate 51. Furthermore, a direction along the long sides of the rectangular shape of the first elastic plate 51 is defined as the length direction of the first elastic plate 51. Additionally, a direction that is orthogonal to both the width direction and the length direction of the first elastic plate 51 is defined as the thickness direction of the first elastic plate 51.

[0046] As in Fig. As shown in Figure 1, each of the first elastic plates 51 is arranged orthogonally to the first imaginary line. In particular, the thickness direction of each of the first elastic plates 51 coincides with the direction along the first imaginary line, i.e., the X-axis direction. Furthermore, the width direction of each of the first elastic plates 51 coincides with the axial direction of the tire 2, i.e., the Y-axis direction. As a result of the arrangement described above, the longitudinal direction of each of the first elastic plates 51 coincides with the Z-axis direction, which is orthogonal to both the X-axis and Y-axis directions. In particular, the pair of first elastic plates 51 is arranged parallel to a YZ plane that is orthogonal to the X-axis direction.

[0047] Both longitudinal end regions 511 of each of the first elastic plates 51 are attached to the inner circumferential surface 21 of the tire 2 as a pair of attachment end regions. A longitudinally extending intermediate region 512 of each of the first elastic plates 51 is attached to the outer circumferential surface 42 of the intermediate element 4 as a single attachment plate region.

[0048] A stiffness of the first elastic plate 51 in a direction orthogonal to the thickness direction, i.e., a stiffness lying in the plane of the first elastic plate 51, is sufficiently higher than a stiffness of the first elastic plate 51 in the thickness direction, i.e., an out-of-plane stiffness of the first elastic plate 51. Consequently, a state in which the tire 2 and the intermediate element 4 are coupled to each other by means of the first elastic plates 51 can be considered equivalent to a state in which the tire 2 and the intermediate element 4 are rigidly connected to each other in the direction orthogonal to the thickness direction of the first elastic plates 51.

[0049] Meanwhile, the out-of-plane stiffness of the first elastic plate 51 is sufficiently less than the in-plane stiffness of the first elastic plate 51. Thus, the first elastic plate 51 is elastically deformable in the thickness direction. When each of the first elastic plates 51 is elastically deformed in the thickness direction, the intermediate element 4 becomes movable in the direction along the first imaginary line, i.e., in the X-axis direction with respect to the tire 2. In particular, each of the first elastic plates 51 couples the intermediate element 4 and the tire 2 to each other, so that the intermediate element 4 becomes movable with respect to the tire 2 along the first imaginary line. Each of the tire 2 and the intermediate element 4 has one degree of freedom, which allows relative movement only in one direction along the first imaginary line, i.e.,in the X-axis direction, made possible by elastic deformation of each of the first elastic plates 51 in the thickness direction.

[0050] The outer circumferential surface 42 of the intermediate element 4 has flat areas 421 of the outer circumferential surface, as shown in Fig. Figure 1 shows the flat areas 421 of the outer circumferential surface. These flat areas are formed at positions where the longitudinally extending intermediate sections 512 of the first elastic plates 51 are each attached as a single mounting plate area. In this embodiment, the outer circumferential surface 42 of the intermediate element 4 has two flat areas 421. The flat areas 421 are formed on the outer circumferential surface 42 of the intermediate element 4 at a position that is shifted forward from the reference position A by θ = 90 degrees in the circumferential direction of the tire 2, and at a position that is shifted forward from the reference position A by θ = 270 degrees in the circumferential direction of the tire 2. Each of the flat areas 421 of the outer circumferential surface is a flat area that is arranged orthogonally to the direction along the first imaginary line, i.e., the X-axis direction.

[0051] The longitudinally extending intermediate section 512 of each of the first elastic plates 51 is attached to the outer circumferential surface 42 of the intermediate element 4 in such a way that a surface of the longitudinally extending intermediate section 512, which is orthogonal to the thickness direction of the first elastic plate 51, is held in contact with the flat area 421 of the outer circumferential surface without leaving a gap. A fastening method is used to attach the longitudinally extending intermediate section 512 of the first elastic plates 51 to the outer circumferential surface 42 of the intermediate element 4, in which, for example, a screw, a bolt, welding, or an adhesive is used.

[0052] The inner circumferential surface 21 of the tire 2 has pairs of stepped areas 211. Each pair of stepped areas 211 is formed at positions where both longitudinal end areas L 511 of each of the first elastic plates 51 are attached as a pair of fastening end areas. Thus, a number of pairs of stepped areas 211 corresponding to the number of first elastic plates 51 is formed on the inner circumferential surface 21 of the tire 2. In this embodiment, two pairs of stepped areas 211 are formed on the inner circumferential surface 21 of the tire 2.

[0053] Fig. Figure 6 is a perspective view to illustrate a state in which the first elastic plate 51 is according to Fig. 1 is attached to the tire 2. Both longitudinal end regions 511 of the first elastic plate 51 are each arranged on the pair of stepped regions 211. The pair of stepped regions 211 are arranged opposite each other in the circumferential direction of the tire 2. Each of the pair of stepped regions 211 has a bottom surface 211a and an end surface 211b. The bottom surface 211a of the stepped region is perpendicular to the direction along the first imaginary line, i.e., the X-axis direction. The end surface 211b of the stepped region extends from the bottom surface 211a of the stepped region to an inner side of the tire 2.

[0054] The end surface 211b of each of the pair of stepped areas 211 is a flat surface parallel to a flat surface containing the axis of the intermediate element 4 and the first imaginary line. The end surface 211b of each of the pair of stepped areas 211 is orthogonal to the Z-axis direction. The pair of stepped areas 211 is formed on the inner circumferential surface 21 of the tire 2 in a state where the two end surfaces 211b of the stepped area are opposite each other in the Z-axis direction.

[0055] Both longitudinal end regions 511 of the first elastic plate 51 are attached to the inner circumferential surface 21 of the tire 2 in such a way that their surfaces, which are orthogonal to the thickness direction of the first elastic plate 51, are held in contact with the bottom surfaces 211a of the stepped area without leaving a gap, or their end surfaces in the longitudinal direction of the first elastic plate 51 are held in contact with the end surfaces 211b of the stepped area without leaving a gap. A fastening method is used to attach both longitudinal end regions 511 of the first elastic plate 51 to the inner circumferential surface 21 of the tire 2, in which, for example, a screw, a bolt, welding, or an adhesive is used.

[0056] A line that differs from the first imaginary line, which is orthogonal to the axis of the intermediate element 4, is defined as the second imaginary line. Each of the pair of second elastic plates 61 is then positioned such that it intersects the second imaginary line. In this embodiment, a line that is orthogonal to both the first imaginary line and the axis of the intermediate element 4 is defined as the second imaginary line. In particular, in this embodiment, the second imaginary line coincides with a line extending in the Z-axis direction. The pair of second elastic plates 61 are arranged at positions on the sides that are opposite each other with respect to the axis P of the tire 2 in a direction along the second imaginary line, i.e., in the Z-axis direction.Thus, one of the pair of second elastic plates 61 is arranged at the reference position A of θ=0 degrees, and the other of the second elastic plates 61 is arranged at a position that is shifted forward by θ=180 degrees from the reference position A in the circumferential direction of the tire 2. The tire 2 is arranged coaxially to the intermediate element 4, such that the axis P of the tire 2 and the axis of the intermediate element 4 are located between the pair of second elastic plates 61.

[0057] Fig. Figure 7 is a perspective view of the second elastic plate 61 according to Fig. 1. Each of the second elastic plates 61 is a flat plate with a rectangular shape. A direction along the short sides of the rectangular shape of the second elastic plate 61 is defined as the width direction of the second elastic plate 61. Furthermore, a direction along the long sides of the rectangular shape of the second elastic plate 61 is defined as the length direction of the second elastic plate 61. Additionally, a direction that is orthogonal to both the width direction and the length direction of the second elastic plate 61 is defined as the thickness direction of the second elastic plate 61.

[0058] As in Fig. As shown in Figure 1, each of the second elastic plates 61 is arranged orthogonally to the second imaginary line. In particular, the thickness direction of each of the second elastic plates 61 coincides with the direction along the second imaginary line, i.e., the Z-axis direction. Furthermore, the width direction of each of the second elastic plates 61 coincides with the axial direction of the tire 2, i.e., the Y-axis direction. As a result of the arrangement described above, the longitudinal direction of each of the second elastic plates 61 coincides with the X-axis direction, which is orthogonal to both the Y-axis and the Z-axis directions. In particular, the pair of second elastic plates 61 is arranged parallel to an XY plane that is orthogonal to the Z-axis direction.

[0059] Both longitudinal end regions 611 of each of the second elastic plates 61 are attached to the inner circumferential surface 41 of the intermediate element 4 as a pair of fastening end regions. A longitudinally extending intermediate region 612 of each of the second elastic plates 61 is attached to the outer circumferential surface 344 of the rotating frame 34 as a single fastening plate region.

[0060] A stiffness of the second elastic plate 61 in a direction orthogonal to the thickness direction, i.e., an in-plane stiffness of the second elastic plate 61, is sufficiently higher than a stiffness of the second elastic plate 61 in the thickness direction, i.e., an out-of-plane stiffness of the second elastic plate 61. Consequently, a state in which the intermediate element 4 and the rotating frame 34 are coupled to each other by means of the second elastic plates 61 can be considered equivalent to a state in which the intermediate element 4 and the rotating frame 34 are rigidly connected to each other in the direction orthogonal to the thickness direction of the second elastic plates 61.

[0061] Meanwhile, the out-of-plane stiffness of the second elastic plate 61 is sufficiently less than the in-plane stiffness of the second elastic plate 61. Thus, the second elastic plate 61 is elastically deformable in the thickness direction. When each of the second elastic plates 61 is elastically deformed in the thickness direction, the main body 3 is movable in the direction along the second imaginary line, i.e., in the Z-axis direction with respect to the intermediate element 4. In particular, each of the second elastic plates 61 couples the intermediate element 4 and the rotating frame 34 to each other, such that the intermediate element 4 becomes movable with respect to the main body 3 along the second imaginary line. Both the intermediate element 4 and the main body 3 have one degree of freedom, which allows relative movement only in one direction along the second imaginary line, i.e.,h. in the Z-axis direction, made possible by elastic deformation of each of the second elastic plates 61 in the thickness direction.

[0062] The outer circumferential surface 344 of the rotating frame 34 has flat areas 345. These flat areas are formed at positions where the longitudinally extending intermediate sections 612 of the second elastic plates 61 are each attached as individual mounting plate areas. In this embodiment, the outer circumferential surface 344 of the rotating frame 34 has two flat areas 345. The flat areas 345 are formed on the outer circumferential surface 344 of the rotating frame 34 at the reference position A of θ = 90 degrees and at a position that is displaced forward from the reference position A by θ = 180 degrees in the circumferential direction of the tire 2. Each of the flat areas 345 is a flat area that extends orthogonally to the direction along the second imaginary line, i.e., the Z-axis direction.

[0063] The longitudinally extending intermediate section 612 of each of the second elastic plates 61 is attached to the outer circumferential surface 344 of the rotating frame 34 in such a way that a surface of the longitudinally extending intermediate section 612, which is orthogonal to the thickness direction of the second elastic plate 61, is held in contact with the flat area 345 of the outer circumferential surface without leaving a gap. A fastening method is used to attach the longitudinally extending intermediate section 612 of the second elastic plates 61 to the outer circumferential surface 344 of the rotating frame 34, in which, for example, a screw, a bolt, welding, or an adhesive is used.

[0064] The inner circumferential surface 41 of the intermediate element 4 has pairs of stepped regions 411. Each pair of stepped regions 411 is formed at positions where both longitudinal end regions 611 of each of the second elastic plates 61 are attached as a pair of fastening end regions. Thus, the number of pairs of stepped regions 411 corresponding to the number of second elastic plates 61 is formed on the inner circumferential surface 41 of the intermediate element 4. In this embodiment, two pairs of stepped regions 411 are formed on the inner circumferential surface 41 of the intermediate element 4.

[0065] Fig. Figure 8 is a perspective view to illustrate a state in which the second elastic plate 61 is according to Fig. 1 is attached to the intermediate element 4. Both longitudinal end regions 611 of the second elastic plate 61 are each arranged on the pair of stepped regions 411. The pair of stepped regions 411 are arranged opposite each other in the circumferential direction of the intermediate element 4. Each of the pair of stepped regions 411 has a bottom surface 411a and an end surface 411b. The bottom surface 411a of the stepped region is orthogonal to the direction along the second imaginary line, i.e., the Z-axis direction. The end surface 411b of the stepped region extends from the bottom surface 411a of the stepped region to an inner side of the intermediate element 4.

[0066] The end surface 411b of each of the pair of stepped regions 411 is a flat surface parallel to a flat surface containing the axis of the intermediate element 4 and the second imaginary line. The end surface 411b of each of the pair of stepped regions 411 is orthogonal to the Z-axis direction. The pair of stepped regions 411 is formed on the inner circumferential surface 41 of the intermediate element 4 in a state where the two end surfaces 411b of the stepped regions are opposite each other in the X-axis direction.

[0067] Both longitudinal end regions 611 of the second elastic plate 61 are attached to the inner circumferential surface 41 of the intermediate element 4 in such a way that their surfaces, which are orthogonal to the thickness direction of the second elastic plate 61, are held in contact with the bottom surfaces 411a of the stepped area without leaving a gap, or their end surfaces in the longitudinal direction of the second elastic plate 61 are held in contact with the end surfaces 411b of the stepped areas without leaving a gap. A fastening method is used to attach both longitudinal end regions 611 of the second elastic plate 61 to the inner circumferential surface 41 of the intermediate element 4, in which, for example, a screw, a bolt, welding, or an adhesive is used.

[0068] As in Fig. 1 to Fig. As shown in Figure 3, the vibration damping structure 7 is attached to the main body 3. Furthermore, the vibration damping structure 7 includes a weight 71, which serves as a counterweight. The weight 71 is attached to the second end region 322 of the main shaft 32. Consequently, the weight 71 is located at a position further away from the gear mechanism 35 than a position of the rotary plate region 342, specifically on the negative side in the Y-axis direction with respect to the rotary frame 34.

[0069] The weight 71 rotates integrally with the main shaft 32 and the rotor 331 about the axis of the main body 3. In particular, the centerline of rotation of the weight 71 coincides with the axis of the main body 3. Furthermore, the rotational speed of the weight 71 is equal to the rotational speed of the main shaft 32 and the rotor 331. Consequently, the weight 71 rotates in the same direction as the rotation of the rotating frame 34 at twice the rotational speed of the rotating frame 34.

[0070] The weight projects from the main shaft 32 in a specific radial direction, which is orthogonal to the center line of rotation of the weight 71. Consequently, the position of the center of gravity 71a of the weight 71 is defined as a position separated from the center line of rotation of the weight 71 in a direction orthogonal to the center line of rotation of the weight 71. In this embodiment, the position of the center of gravity 71a of the weight 71 is defined as a position separated from the center line of rotation of the weight 71 in a direction along the second imaginary line. The center of gravity 71a of the weight 71 moves along a circle with the center line of rotation of the weight 71 as its center point, together with the rotation of the weight 71.

[0071] The wheel assembly 1 is arranged such that the position of the center of gravity 71a of the weight 71 is on a negative side in the Z-axis direction with respect to the center line of rotation of the weight 71 in a state according to Fig. 1 is located in which the direction along the second imaginary line coincides with the Z-axis direction. If the thickness direction of each of the pair of second elastic plates 61 coincides with the Z-axis direction and the pair of second elastic plates 61 is located on the Z-axis, the position of the center of gravity 71a of the weight 71 is thus on the negative side in the Z-axis direction with respect to the rotation centerline of the weight 71. In particular, if the direction along the second imaginary line in the wheel device 1 coincides with the vertical direction, the position of the center of gravity 71a of the weight 71 is located below the rotation centerline of the weight 71.

[0072] Next, the operation of wheel device 1 will be described. Fig. Figure 9 is a schematic view illustrating a wheel assembly model created by modeling the wheel assembly 1 according to Fig. 1 is obtained. The intermediate element 4 is movable in the direction along the second imaginary line with respect to the main body 3 by elastic deformation of the pair of second elastic plates 61. The movement of the intermediate element 4 in a direction other than the direction along the second imaginary line with respect to the main body 3 is limited by the in-plane stiffness of the pair of second elastic plates 61.

[0073] The intermediate element 4 is movable in the direction along the first imaginary line with respect to the tire 2 by elastic deformation of the pair of first elastic plates 51. The movement of the intermediate element 4 in a direction other than the direction along the first imaginary line with respect to the tire 2 is limited by the in-plane stiffness of the pair of first elastic plates 51.

[0074] Consequently, the wheel device 1 has a translational vibration system with two degrees of freedom in which the intermediate element 4 can move freely in an XZ plane containing the first imaginary line and the second imaginary line with respect to the main body 3 and the tire 2.

[0075] Each of the stiffnesses of the first elastic plates 51 and the second elastic plates 61 is a plane stiffness in the circumferential direction of the tire 2. Thus, the elastic deformation of each of the first elastic plates 51 and the second elastic plates 61 is restricted in the circumferential direction of the tire 2. Each of the states in which the intermediate element 4 is coupled to the tire 2 and each of the states in which the intermediate element 4 is coupled to the rotating frame 34 in the circumferential direction of the tire 2 can be considered a rigid connection state. Thus, the rotational speed of the tire 2 becomes equal to the rotational speed of the intermediate element 4. Furthermore, the rotational speed of the intermediate element 4 becomes equal to the rotational speed of the rotating frame 34.

[0076] Fig. 10 is a front view to illustrate a state in which the wheel assembly 1 is located according to Fig. 1 moved on a rail. Fig. 11 is a schematic view of a wheel assembly model created by modeling the wheel assembly 1 according to Fig. The outer circumferential surface of the tire 2 is in contact with a rail 10 in a state where the wheel assembly 1 is placed on the rail 10. When the tire 2 is rotated, the wheel assembly 1 moves on the rail 10.

[0077] When the rotor 331 is rotated by supplying energy to the stator 332, the main shaft 32 and the sun gear 351 rotate integrally with the rotor 331. When the sun gear 351 rotates, the planet gears 353 rotate around the sun gear 351. Consequently, the rotating frame 34 rotates around the axis of the main body 3. In this way, the torque of the main body electric motor 33 is transmitted to the rotating frame 34.

[0078] The torque of the main body electric motor 33, which has been transmitted to the rotating frame 34, is transferred from the rotating frame 34 via the pair of second elastic plates 61 to the intermediate element 4. At this time, one direction of the torque transmitted from the rotating frame 34 to each of the second elastic plates 61 coincides with the direction of the in-plane stiffness of each of the second elastic plates 61. Consequently, the elastic deformation of the second elastic plates 61 is restricted, and thus the torque of the rotating frame 34 is effectively transmitted to the intermediate element 4.

[0079] The torque transmitted to the intermediate element 4 is then transferred via the pair of first elastic plates 51 to the tire 2. At this time, one direction of the torque transmitted from the intermediate element 4 to each of the first elastic plates 51 coincides with the direction of the in-plane stiffness of each of the first elastic plates 51. Consequently, the elastic deformation of the first elastic plates 51 is restricted, and thus the torque transmitted to the intermediate element 4 is effectively transferred to the tire 2. In this way, the tire 2 is rotated. Thus, in the wheel assembly 1, when the rotating frame 34 is rotated, each of the tire 2 and the intermediate element 4 is rotated in the same direction as the direction of rotation of the rotating frame 34.

[0080] Rail 10 has a plurality of rail units 10a arranged in a series. A height difference can sometimes occur at a joint between two adjacent rail units 10a. In this case, when the wheel assembly 1 runs over the joint between two rail units 10a, the tire 2 is subjected to an impact force from the rail 10.

[0081] As in Fig. 10 and Fig. As shown in Figure 11, when the tire 2 is subjected to an impact force in the direction along the second imaginary line, i.e., the direction corresponding to the Z-axis direction, the intermediate element 4 is moved by the elastic deformation of the second elastic plates 61 only in the direction along the second imaginary line with respect to the main body 3. Consequently, the impact force to which the tire 2 is subjected is absorbed by the pair of second elastic plates 61 and is thus less likely to be transmitted to the main body 3.

[0082] Furthermore, Fig. 12 a front view to illustrate a state of the wheel assembly 1 when the tire 2 is in a rotational position that differs from that of the tire 2 according to Fig. 10 differs, and he is subjected to an impact force from rail 10. Fig. 13 is a schematic view of a wheel assembly model created by modeling the wheel assembly 1 according to Fig. 12 will be received. As in Fig. 12 and Fig. As shown in Figure 13, when the tire 2 is subjected to an impact force from the rail 10 in a direction that does not coincide with either the direction along the first imaginary line or the direction along the second imaginary line, the intermediate element 4 moves in the direction along the first imaginary line with respect to the tire 2 and in the direction along the second imaginary line with respect to the main body 3. When the intermediate element 4 moves in the direction along the first imaginary line with respect to the tire 2, the first elastic plates 51 are elastically deformed. When the intermediate element 4 moves in the direction along the second imaginary line with respect to the main body 3, the second elastic plates 61 are elastically deformed.Consequently, the impact force to which the tire 2 is subjected is absorbed by the first elastic plates 51 and the second elastic plates 61, and is thus less likely to be transferred to the main body 3.

[0083] Fig. Figure 14 is a schematic, explanatory view to illustrate changes in the state of the wheel assembly 1 when the wheel assembly 1 moves according to Fig. 9 moved under rotation on rail 10. In Fig. In section 14, the direction along the first imaginary line is called the first direction ξ, and the direction along the second imaginary line is called the second direction η. When the wheel assembly 1 moves on the rail 10, a phenomenon can occur in which the intermediate element 4 "whirls" relative to the tire 2 and the main body 3, specifically a "whirl" of the intermediate element 4. Fig. Figure 14 shows changes in the state of the wheel device 1 from a state in which the second direction η coincides with the Z-axis direction to a state in which the second direction η coincides with the X-axis direction.

[0084] In Fig. When the wheel assembly 1 is rotated by 90 degrees, the intermediate element 4 rotates by 180 degrees relative to the tire 2 and the main body 3. Specifically, the intermediate element 4 rotates at a frequency twice that of the wheel assembly 1. This rotation generates a centrifugal force, causing the wheel assembly 1 to vibrate as a whole. Within the wheel assembly 1, the weight 71 of the vibration damping structure 7 acts to suppress these vibrations.

[0085] After the wheel assembly 1 has been rotated 90 degrees from an initial state in which the second direction η coincides with the Z-axis direction, i.e., the vertical direction, the second direction η coincides with the X-axis direction. At this time, the first direction ξ coincides with the Z-axis direction. As in the Fig. In the wheel assembly 1 shown on the right, the first elastic plates 51 are thus elastically deformed. At this time, the intermediate element 4 is moved towards the negative side in the Z-axis direction with respect to the tire 2, in particular downwards. Consequently, the centrifugal force acts on the intermediate element 4 towards the negative side in the Z-axis direction.

[0086] Meanwhile, the center of gravity 71a of the weight 71 is located on the negative side in the Z-axis direction with respect to the center of rotation of the weight 71, specifically below the center of rotation of the weight 71 in the initial state, in which the second direction η coincides with the Z-axis direction. Furthermore, the weight 71 is rotated in the same direction as the direction of rotation of the rotating frame 34 at a speed twice that of the rotating frame 34. When the wheel assembly 1 is rotated 90 degrees from the initial state and the second direction η coincides with the X-axis direction, the weight 71 is thus rotated 180 degrees, and the center of gravity 71a of the weight 71 is moved towards the positive side in the Z-axis direction with respect to the center of rotation of the weight 71, i.e., moved upwards. Consequently, the centrifugal force acts on the weight 71 in the positive direction in the Z-axis direction.

[0087] As described above, a centrifugal force acts when the second direction η coincides with the Z-axis direction, as in the wheel assembly 1, which is on the right side in Fig. As shown in Figure 14, the centrifugal force on the weight 71 acts in a direction that cancels out the centrifugal force acting on the intermediate element 4 towards the negative side in the Z-axis direction; that is, a centrifugal force acts on the weight 71 towards the positive side in the Z-axis direction. Specifically, the centrifugal force acts on the weight 71 in the direction of cancellation of a driving force generated by a swirling motion of the intermediate element 4.

[0088] Next, the eccentric distance of weight 71 and the mass of weight 71 are described. The eccentric distance of weight 71 is the distance from the center line of rotation of weight 71 to the center of gravity 71a of weight 71. The mass of the intermediate element 4 is represented by M, the angular velocity of the wheel assembly 1 by ω, the mass of weight 71 by "m", and the eccentric distance of weight 71 by L. As in Fig. Figure 14 shows a displacement in the vertical direction, which is the Z-axis direction, of the displacements caused by the whirling of the intermediate element 4, in particular a displacement of the intermediate element 4 in the vertical direction, shown by D.

[0089] In this case, the centrifugal force acting on the intermediate element 4 due to the swirling of the vibration system having the intermediate element 4 is expressed by the following expression (3). M⋅D⋅ω2

[0090] When the wheel assembly 1 completes one revolution, the weight 71 completes two revolutions. Therefore, the angular velocity of the weight 71 is 2ω. Thus, the centrifugal force acting on the weight 71 is expressed by the following expression (4). m⋅L⋅(2ω)2

[0091] The vibration caused by the swirling of intermediate element 4 is most strongly suppressed when expressions (3) and (4) are equal. Thus, the condition under which the vibration caused by the swirling of intermediate element 4 is most strongly suppressed is expressed by the following expression (5). M⋅D=4⋅m⋅L

[0092] If, therefore, the product of the eccentric distance L of the weight 71 and the mass "m" of the weight 71 is equal to one-quarter of the product of the displacement D of the intermediate element 4 in the vertical direction, caused by the rotation of the tire 2, and the mass M of the intermediate element 4, the vibration caused by the whirling of the intermediate element 4 is effectively suppressed. In this embodiment, the product of the eccentric distance L of the weight 71 and the mass "m" of the weight 71 is equal to one-quarter of the product of the displacement D of the intermediate element 4 in the vertical direction, caused by the rotation of the tire 2, and the mass M of the intermediate element 4.

[0093] Next, a displacement D1 of the main body 3 in the Z-axis direction, caused by a linear change in the rotational speed R [Hz] of the wheel assembly 1 from 0 [Hz] to 20 [Hz], was obtained by numerical analysis. In the numerical analysis, a wheel assembly according to comparison example A1 without the vibration damping structural unit 7, a wheel assembly according to example B1 where M = 60 [kg], m = 0.05 [kg], and L = 200 [mm] were specified, and a wheel assembly according to example C1 where M = 60 [kg], m = 0.1 [kg], and L = 200 [mm] were specified, were analyzed as targets. Thus, an example that does not satisfy expression (5) corresponds to example B1, and an example that satisfies expression (5) corresponds to example C1.In the wheel assembly 1, the displacement D1 of the main body 3 in the Z-axis direction decreases when the vibration of the wheel assembly 1, caused by the swirling of the intermediate element 4, decreases.

[0094] Fig. Figure 15 is a graph illustrating the relationship between the rotational speed R [Hz] of each of the wheel assemblies in comparison example A1, example B1, and example C1, and the time "t" [sec] in the numerical analysis. Furthermore, Fig. 16. A graph illustrating the relationship between the displacement D1 [mm] of the main body 3 in the comparison example A1 in the Z-axis direction and the time "t" [sec] in the numerical analysis. Furthermore, Fig. 17 a graph to represent a relation between the displacement D1 [mm] of the main body 3 in example B1 in the Z-axis direction and the time “t” [sec] in the numerical analysis. Fig. Figure 18 is a graph to represent a relation between the displacement D1 [mm] of the main body 3 in the comparison example C1 in the Z-axis direction and the time “t” [sec] in the numerical analysis.

[0095] As in Fig. 15 to Fig. As shown in Figure 18, it is understood that the vibration of the main body 3 in comparison example A1 begins to increase by 3.5 [sec], while the vibration of the main body 3 in examples B1 and C1 is reduced compared to comparison example A1. Furthermore, it is understood that the vibration of the main body 3 in example C1, which satisfies expression (5), is reduced more than in example B1, which does not satisfy expression (5).

[0096] In the wheel assembly 1 described above, the first elastic plates 51 are arranged orthogonally to the first imaginary line, which is perpendicular to the axis of the intermediate element 4. Furthermore, the second elastic plates 61 are arranged orthogonally to the second imaginary line, which differs from the first imaginary line. This arrangement increases the stiffness of each of the first elastic plates 51 and the second elastic plates 61 in the circumferential direction of the tire 2. Consequently, the elastic deformation of each of the first elastic plates 51 and the second elastic plates 61 in one direction of rotation of the tire 2 can be limited, thus preventing the occurrence of unnecessary vibrations of the tire 2 relative to the main body 3 in the direction of rotation of the tire 2. Therefore, the torque can be transmitted more reliably from the main body 3 to the tire 2.When the tire 2 is subjected to an external impact force, the main body 3 can be moved relative to the tire 2, while at least one of the first elastic plates 51 and the second elastic plates 61 are elastically deformed. Consequently, the impact force to which the tire 2 is subjected can be absorbed by at least one of the first elastic plates 51 and the second elastic plates 61. Thus, the impact force transmitted from the tire 2 to the main body 3 can be reduced.

[0097] Furthermore, the second imaginary line, which is orthogonal to the second elastic plates 61, is orthogonal to the first imaginary line, which is orthogonal to the first elastic plates 51. Thus, the first elastic plates 51 and the second elastic plates 61 can be arranged uniformly in the circumferential direction of the tire 2. This arrangement makes it possible to achieve a damping force for the impact force to which the tire 2 is subjected in the circumferential direction of the tire 2.

[0098] Furthermore, the axis of the intermediate element 4 is located between the pair of first elastic plates 51 and the pair of second elastic plates 61. The aforementioned positioning enables stabilization of the state in which the intermediate element 4 is coupled to the tire 2 and the state in which the main body 3 is coupled to the intermediate element 4. Consequently, the occurrence of a defect in the wheel assembly 1 can be more reliably suppressed, and thus the reliability of the wheel assembly 1 can be improved.

[0099] Furthermore, both longitudinal end regions 511 of each of the first elastic plates 51 are attached to the tire 2, and the longitudinally extending intermediate region 512 of each of the first elastic plates 51 is attached to the intermediate element 4. Thus, a more reliable condition of the first elastic plates 51 attached to the tire 2 and to the intermediate element 4 can be ensured, while allowing elastic deformation of the first elastic plates 51 in the thickness direction.

[0100] Furthermore, both longitudinal end regions 611 of each of the second elastic plates 61 are attached to the intermediate element 4, and the longitudinally extending intermediate region 612 of each of the second elastic plates 61 is attached to the rotating frame 34 of the main body 3. Thus, a more reliable condition of the second elastic plates 61 attached to the intermediate element 4 and the rotating frame 34 can be ensured, while allowing elastic deformation of the second elastic plates 61 in the thickness direction.

[0101] Furthermore, the inner circumferential surface 21 of the tire 2 has pairs of stepped areas 211. Each pair of stepped areas 211, to which both longitudinal end regions 511 of the first elastic plate 51 are to be attached, is formed at the positions where both longitudinal end regions 511 of the first elastic plate 51 are attached as a pair of attachment end regions. Thus, the first elastic plates 51 can be attached to the tire 2 more reliably, and positional displacement of each of the first elastic plates 51 relative to the tire 2 can be more reliably prevented.

[0102] Furthermore, the inner circumferential surface 41 of the intermediate element 4 has pairs of stepped areas 411. Each pair of stepped areas 411, on which both longitudinal end areas 611 of the second elastic plate 61 are to be arranged, is formed at the positions where both longitudinal end areas 611 of the second elastic plate 61 are attached as a pair of fastening end areas. Thus, the second elastic plates 61 can be attached more reliably to the intermediate element 4, and a positional displacement of each of the second elastic plates 61 relative to the intermediate element 4 can be more reliably prevented.

[0103] Furthermore, the vibration damping structural unit 7 includes the weight 71, which is rotated in the same direction as the direction of rotation of the rotating frame 34 at a speed twice that of the rotating frame 34. If the direction along the second imaginary line coincides with the vertical direction, the center of gravity 71a of the weight 71 is also located below the center line of rotation of the weight 71. Thus, at least part of the driving force generated by the movement of the intermediate element 4 with respect to the tire 2 and the main body 3 can be counteracted by the centrifugal force of the weight 71. In this way, the vibration of the wheel assembly 1 as a whole, which can be caused by the swirling of the intermediate element 4, can be suppressed.

[0104] Furthermore, the main body 3 includes the main body electric motor 33, which generates a torque for rotating the rotating frame 34. Thus, a drive source that rotates the wheel assembly 1 can be arranged within the intermediate element 4. Consequently, the wheel assembly 1 can be miniaturized.

[0105] Furthermore, the main body 3 features the gear mechanism 35, which transmits the torque of the main body electric motor 33 to the rotating frame 34, so that the rotational speed of the rotating frame 34 becomes equal to half the rotational speed of the rotor 331. The weight 71 also rotates integrally with the rotor 331. Thus, the rotational speed of the weight 71 can be set more reliably than twice the rotational speed of the rotating frame 34.

[0106] Furthermore, the gear mechanism 35 is a planetary gear mechanism comprising the sun gear 351, the ring gear 352, and the majority of planet gears 353. With this simple configuration, the rotational speed of the weight 71 can thus be set to twice the rotational speed of the rotating frame 34. Consequently, the occurrence of a defect in the wheel assembly 1 can be suppressed more reliably, thus significantly improving the reliability of the wheel assembly 1.

[0107] Furthermore, the product of the eccentric distance L of weight 71 and the mass "m" of weight 71 is equal to one-quarter of the product of the displacement D of the intermediate element 4 in the vertical direction, caused by the rotation of the tire 2, and the mass M of the intermediate element 4. Thus, the driving force generated by the turbulence of the intermediate element 4 can be effectively canceled out by the centrifugal force of weight 71. Consequently, the vibration of the wheel assembly 1 as a whole can be effectively suppressed.

[0108] If the axis of rotation of the weight 71 is offset from the axis of the main body 3, an unnecessary torque is generated in the weight 71, which does not contribute to suppressing the vibrations caused by the turbulence of the intermediate element 4. In this embodiment, the axis of rotation of the weight 71 coincides with the axis of the main body 3. Consequently, the generation of unnecessary torque can be suppressed. Furthermore, the need for an additional weight to suppress the generation of unnecessary torque is eliminated. Thus, vibrations that can be caused by the turbulence of the intermediate element 4 can be effectively suppressed with a simple configuration.

[0109] Fig. Figure 19 is a sectional view illustrating a wheel assembly according to a second embodiment. Fig. 19 corresponds Fig. 2 according to the first embodiment. A turntable section 342 of a rotary frame 34 is rotatably mounted on a second end section 322 of a main shaft 32 by means of a bearing 303. The main shaft 32 extends beyond a fixed frame 31 on the positive side in the Y-axis direction. Consequently, a first end section 321 of the main shaft 32 is located on the inside of the body in the lateral direction with respect to the fixed frame 31.

[0110] A weight 71 is attached to the first end region 321 of the main shaft 32. The weight 71 is located on the inside of the body in the lateral direction with respect to the fixed frame 31, i.e., on the positive side in the Y-axis direction with respect to the fixed frame 31.

[0111] The configuration of the weight 71 is the same as in the first embodiment. Consequently, the weight 71 is rotated in the same direction as the direction of rotation of a rotating frame 34 at a speed twice that of the rotating frame 34. Furthermore, a center of gravity 71a of the weight 71 is moved along a circle with the center line of rotation of the weight 71 as its center point, in conjunction with the rotation of the weight 71.

[0112] The wheel assembly 1 is arranged such that the position of the center of gravity 71a of the weight 71 is located on a negative side in the Z-axis direction with respect to the center of rotation of the weight 71, in a state where the direction along the second imaginary line coincides with the Z-axis direction. When the direction along the second imaginary line in the wheel assembly 1 coincides with the vertical direction, the position of the center of gravity 71a of the weight 71 is thus below the center of rotation of the weight 71. Other configurations in the second embodiment are the same as those in the first embodiment.

[0113] In the wheel assembly 1 described above, the weight 71 is attached to the first end region 321 of the main shaft 32. Thus, the weight 71 can be located on the inside, in the lateral direction of the body, relative to the fixed frame 31 attached to the body. Consequently, the dimension of a region of the wheel assembly 1 located on the outside of the fixed frame 31 in the lateral direction of the body can be reduced. Therefore, the wheel assembly 1 can be made smaller with respect to a boundary defined by a side surface of the body, thus improving the degree of freedom in the design of the wheel assembly 1.

[0114] Fig. Figure 20 is a sectional view illustrating a wheel assembly according to a third embodiment. Fig. 20 corresponds Fig. 2 according to the first embodiment. A rotary plate section 342 of a rotary frame 34 is attached to a second end section 322 of a main shaft 32. Consequently, the rotary frame 34 is rotated integrally with the main shaft 32 and a rotor 331 about an axis of a main body 3. Thus, the rotary frame 34 is rotated by the torque of a main body electric motor 33 at a speed equal to the speed of the main shaft 32 and the rotor 331.

[0115] A vibration damping structural unit 7 is arranged on the inside in the lateral direction of the body with respect to the main body 3, i.e., on a positive side in the Y-axis direction with respect to the main body 3. Furthermore, the vibration damping structural unit 7 comprises a weight 71 and a gear mechanism 72. The weight 71 is attached to the main shaft 32 by means of the gear mechanism 72. The gear mechanism 72 transmits the torque of the main body electric motor 33 to the weight 71.

[0116] The gear mechanism 72 is arranged on the inside in the lateral direction of the body with respect to the main shaft 32, i.e., on the positive side in the Y-axis direction with respect to the main shaft 32. Furthermore, the gear mechanism 72 transmits the torque of the electric motor 33 of the main body to the weight 71 such that the rotational speed of the weight 71 is twice that of the rotor 331. When electrical energy is supplied to a stator 332, the weight 71 is further rotated in the same direction of rotation as the rotating frame 34 at a speed twice that of the rotating frame 34.

[0117] The gear mechanism 72 comprises a sun gear 721, a ring gear 722, a plurality of planet gears 723, an element 725 attached to the main shaft, and a gear mechanism output shaft 726. The sun gear 721, the ring gear 722, and the multiple planet gears 723 form a planetary gear mechanism. One configuration of the planetary gear mechanism is the same as the configuration of the gear mechanism 35 in the first embodiment.

[0118] The element 725 attached to the main shaft is fixed to a first end region 321 of the main shaft 32. Consequently, the element 725 attached to the main shaft rotates integrally with the main shaft 32 and the rotor 331 about the axis of the main body 3. The element 725 attached to the main shaft is located on the inside in the lateral direction of the body with respect to the fixed frame 31, i.e., on the positive side in the Y-axis direction with respect to the fixed frame 31. The element 725 attached to the main shaft is a circular plate that is orthogonal to the axis of the main body 3. The outer diameter of the element 725 attached to the main shaft is larger than the outer diameter of the main shaft 32.

[0119] The sun gear 721 is arranged coaxially to the axis of the main body 3. Furthermore, the sun gear 721 is located on the inside in the lateral direction of the body with respect to the element 725 attached to the main shaft, i.e., on the positive side in the Y-axis direction with respect to the element 725 attached to the main shaft.

[0120] The ring gear 722 is an annular gear that surrounds the sun gear 721. As a result of this arrangement, the ring gear 722 is located on the inside of the body in the lateral direction with respect to the fixed frame 31, i.e., on the positive side in the Y-axis direction with respect to the fixed frame 31. The ring gear 722 is arranged coaxially with the axis of the main body 3. Furthermore, the ring gear 722 is attached to the fixed frame 31.

[0121] The planet gears 723 are arranged between the sun gear 721 and the ring gear 722. The planet gears 723 mesh with each of the sun gear 721 and the ring gear 722. Furthermore, the planet gears 723 are attached to the element 725, which is fixed to the main shaft. The sun gear 721 is supported by the planet gears 723, which in turn hold the sun gear 721. When the element 725 attached to the main shaft is rotated integrally with the main shaft 32 and the rotor 331, the planet gears 723 orbit the sun gear 721 around the axis of the main body 3. The orbital speed of each of the planet gears 723 with respect to the sun gear 721 is equal to the rotational speed of the rotor 331. The sun gear 721 is rotated around the axis of the main body 3 with respect to the ring gear 722 synchronously with the orbital speed of each of the planet gears 723 with respect to the sun gear 721.Each of the planet gears 723 has a gear shaft 723a, a first gear section 723b and a second gear section 723c.

[0122] One axis of the gear shaft 723a coincides with one axis of the planet gear 723. The gear shaft 723a is arranged parallel to the axis of the main body 3. Furthermore, the gear shaft 723a is rotatably attached to the element 725, which is fastened to the main shaft.

[0123] Each of the first gear section 723b and the second gear section 723c is an external gear with a plurality of teeth on an outer circumferential region. The first gear section 723b and the second gear section 723c are mounted on the gear shaft 723a. Consequently, the first gear section 723b is mounted coaxially with the second gear section 723c. The gear shaft 723a, the first gear section 723b, and the second gear section 723c are rotated integrally about the axis of the planet gear 723. The first gear section 723b and the second gear section 723c are arranged adjacent to each other in an axial direction along the gear shaft 723a.

[0124] The first gear section 723b is in mesh with the ring gear 722. The second gear section 723c is in mesh with the sun gear 721. The number of teeth of the first gear section 723b and the number of teeth of the second gear section 723c differ from each other. In this embodiment, the number of teeth of the first gear section 723b is greater than the number of teeth of the second gear section 723c.

[0125] The second gear section 723c is located in a position closer to the fixed frame 31 than the first gear section 723b, i.e., on the negative side in the Y-axis direction with respect to the first gear section 723b. The second gear section 723c can be located in a position farther from the fixed frame 31 than the first gear section 723b, i.e., on the positive side in the Y-axis direction with respect to the first gear section 723b.

[0126] The transmission mechanism output shaft 726 is attached to the sun gear 721. The transmission mechanism output shaft 726 projects inwards from the sun gear 721 in the lateral direction of the body, i.e., it projects from the sun gear 721 towards the positive side in the Y-axis direction. The transmission mechanism output shaft 726 is arranged coaxially with the axis of the main body 3. Consequently, the transmission mechanism output shaft 726 rotates integrally with the sun gear 721 about the axis of the main body 3.

[0127] The number of teeth for each of the sun gear 721, ring gear 722, first gear section 723b, and second gear section 723c in the gear mechanism 72 is determined such that the rotational speed of the gear mechanism output shaft 726 is twice the rotational speed of the rotor 331. Specifically, the number of teeth for each of the sun gear 721, ring gear 722, first gear section 723b, and second gear section 723c in the gear mechanism 72 is determined such that the gear ratio of the rotational speed of the gear mechanism output shaft 726 to the rotational speed of the rotor 331 is equal to 2. Consequently, for every one revolution of the rotor 331, the gear mechanism output shaft 726 completes two revolutions in the same direction as the rotation of the rotor 331.

[0128] The weight 71 is attached to the transmission mechanism output shaft 726. Consequently, the weight 71 rotates integrally with the transmission mechanism output shaft 726. Furthermore, the weight 71 is located on the inside in the lateral direction of the body with respect to the planetary gear mechanism of the transmission mechanism 72, i.e., on the positive side in the Y-axis direction with respect to the planetary gear mechanism of the transmission mechanism 72.

[0129] One configuration of the weight 71 is the same as that of the weight in the first embodiment. Consequently, the weight 71 is rotated in the same direction as the direction of rotation of the rotating frame 34 at a speed twice that of the rotating frame 34. The center of rotation of the weight 71 coincides with the axis of the main body 3. The center of gravity 71a of the weight 71 moves along a circle with the center of rotation of the weight 71 as its center point, in conjunction with the rotation of the weight 71.

[0130] The wheel assembly 1 is arranged such that the position of the center of gravity 71a of the weight 71 is located on a negative side in the Z-axis direction with respect to the center of rotation of the weight 71, in a state where the direction along the second imaginary line coincides with the Z-axis direction. When the direction along the second imaginary line in the wheel assembly 1 coincides with the vertical direction, the position of the center of gravity 71a of the weight 71 is thus below the center of rotation of the weight 71. Other configurations in the third embodiment are the same as those in the first embodiment.

[0131] In the wheel assembly 1 described above, the rotating frame 34 rotates integrally with the rotor 331. Furthermore, the gear mechanism 72 transmits the torque of the main body electric motor 33 to the weight 71, so that the rotational speed of the weight 71 becomes twice that of the rotor 331. Thus, the rotational speed of the weight 71 can be set more reliably to be more than twice that of the rotating frame 34. Moreover, the gear mechanism 72 only needs to transmit the torque of the main body electric motor 33 to the weight 71 and does not need to transmit the torque of the main body electric motor 33 to the rotating frame 34, which is heavier than the weight 71. Consequently, the gear mechanism 72 can be made smaller.

[0132] Furthermore, the vibration damping structure unit 7 is arranged on the inside in the width direction of the body with respect to the main body 3. Thus, the weight 71 and the transmission mechanism 72 can be arranged on the inside in the width direction of the body with respect to the fixed frame 31 attached to the body. Consequently, as in the second embodiment, the wheel assembly 1 can be reduced in size with respect to a limit defined by a side surface of the body, thus further improving the degree of freedom in the design of the wheel assembly 1.

[0133] Fig. Figure 21 is a front view illustrating a wheel assembly according to a fourth embodiment. Furthermore, Fig. 22 a sectional view along line XXII-XXII in Fig. 21. Fig. 21 corresponds Fig. 1 according to the first embodiment. Fig. 22 corresponds Fig. 2 according to the first embodiment. A weight 71 is attached to a second end region 322 of a main shaft 32. The weight 71 has a mounting seat 711 and a weight body 712.

[0134] The mounting seat 711 is a rod-shaped element that extends orthogonally to an axis of a principal body 3. The mounting seat 711 is arranged along a second imaginary line. The mounting seat 711 is attached to the second end region 322 in a state in which it extends through the second end region 322. The mounting seat 711 projects from an outer circumferential surface of the second end region 322 in a direction along the second imaginary line.

[0135] The main weight body 712 is attached to the mounting seat 711. For example, a threaded rod is used as the mounting seat 711, and a nut screwed onto the mounting seat 711 is used as the main weight body 712. The main weight body 712 is movable in a longitudinal direction relative to the mounting seat 711. Consequently, the position of the main weight body 712 relative to the mounting seat 711 is adjustable in the longitudinal direction of the mounting seat 711. When the position of the main weight body 712 relative to the mounting seat 711 is adjusted in the longitudinal direction of the mounting seat 711, the position of the center of gravity 71a of the weight 71 is set. In particular, for the weight 71, a distance from a rotational centerline of the weight 71 to the center of gravity 71a of the weight 71, i.e. an eccentric distance L of the weight 71, is adjustable.

[0136] The wheel assembly 1 is arranged such that, in a state where the direction along the second imaginary line coincides with the Z-axis direction, the position of the center of gravity 71a of the weight 71 is located on a negative side in the Z-axis direction with respect to the center of rotation of the weight 71. When the direction along the second imaginary line in the wheel assembly 1 coincides with the vertical direction, the position of the center of gravity 71a of the weight 71 is thus located below the center of rotation of the weight 71. Other configurations in the fourth embodiment are the same as those in the first embodiment.

[0137] In the wheel assembly 1 described above, the eccentric distance L of the weight 71 is adjustable. Thus, the eccentric distance L of the weight 71 can be adjusted according to a displacement D of an intermediate element 4 in the vertical direction, which is determined by the mass of a vehicle, such that expression (5) applies. Consequently, vibrations that may be caused by a turbulence of the intermediate element 4 can be further suppressed effectively.

[0138] Fig. Figure 23 is a sectional view illustrating a wheel assembly according to a fifth embodiment. Fig. 23 corresponds Fig. 2 according to the first embodiment. A main body electric motor 33 has a stator 332 and a rotor 331. The rotor 331 has an annular shape and surrounds an outer circumference of the stator 332. Thus, the main body electric motor 33 is an external rotor type electric motor. The axes of the rotor 331 and the stator 332 coincide with the axis of the main body 3.

[0139] The stator 332 is attached to a fixed frame 31. The rotor 331 is mounted to the fixed frame 31 by means of a bearing 305. A rotating frame 34 is attached to the rotor 331. The rotating frame 34 is mounted to the stator 332 by means of a bearing 306, which is located in a through-hole 343. Consequently, the rotating frame 34 is integrally rotatable with the rotor 331 about the axis of the main body 3 with respect to the stator 332 and the fixed frame 31.

[0140] A vibration damping structural unit 7 is arranged on the outside in the width direction of the body with respect to the rotating frame 34, i.e., on the negative side in the Y-axis direction with respect to the rotating frame 34. Furthermore, the vibration damping structural unit 7 is mounted on the stator 332 through the through-hole 343 of the rotating frame 34.

[0141] The vibration damping structural unit 7 comprises a weight 71 and a gear mechanism 72. The weight 71 is attached to the rotating frame 34 by means of the gear mechanism 72. The gear mechanism 72 transmits the torque of a main body electric motor 33 to the weight 71, so that the rotational speed of the weight 71 is twice that of the rotor 331. One configuration of the gear mechanism 72 is the same as the configuration of the planetary gear mechanism in the second embodiment. In particular, the gear mechanism 72 comprises a sun gear 721, a ring gear 722, and a plurality of planet gears 723.

[0142] Each of the sun gear 721 and the ring gear 722 is arranged coaxially with the axis of the main body 3. The sun gear 721 is attached to the stator 332. The ring gear 722 is an annular gear that surrounds the sun gear 721.

[0143] The planet gears 723 are arranged between the sun gear 721 and the ring gear 722. Each planet gear 723 meshes with both the sun gear 721 and the ring gear 722. Furthermore, the planet gears 723 are mounted on the rotating frame 34. The ring gear 722 is supported by the planet gears 723. When the rotating frame 34 rotates integrally with the rotor 331, the planet gears 723 orbit the sun gear 721 around the axis of the main body 3. Thus, the orbital speed of each of the planet gears 723 with respect to the sun gear 721 is equal to the rotational speed of the rotor 331. The ring gear 722 rotates about the axis of the main body 3 with respect to the sun gear 721 synchronously with the orbital speed of each of the planet gears 723 with respect to the sun gear 721.Thus, according to this embodiment, the gear mechanism 72 is a solar system type planetary gear mechanism which uses a rotational force of each of the planet gears 723 as input and a rotational force of the ring gear 722 as output.

[0144] Each of the planet gears 723 has a gear shaft 723a, a first gear section 723b, and a second gear section 723c. One axis of the gear shaft 723a coincides with an axis of the planet gear 723. The gear shaft 723a is arranged parallel to the axis of the main body 3. Furthermore, the gear shaft 723a is rotatably mounted on a turntable section 342 of the rotary frame 34.

[0145] The first gear section 723b and the second gear section 723c are attached to the gear shaft 723a. Consequently, the first gear section 723b is mounted coaxially with the second gear section 723c. The gear shaft 723a, the first gear section 723b, and the second gear section 723c are rotated integrally about the axis of the planet gear 723. The first gear section 723b and the second gear section 723c are arranged adjacent to each other in an axial direction along the gear shaft 723a.

[0146] The first gear section 723b is in mesh with the ring gear 722. The second gear section 723c is in mesh with the sun gear 721. The number of teeth of the first gear section 723b and the number of teeth of the second gear section 723c differ from each other. In this embodiment, the number of teeth of the first gear section 723b is greater than the number of teeth of the second gear section 723c.

[0147] The second gear section 723c is located in a position closer to the rotating frame 34 than the first gear section 723b, i.e., on the positive side in the Y-axis direction with respect to the first gear section 723b. The second gear section 723c can be located in a position farther from the rotating frame 34 than the first gear section 723b, i.e., on the negative side in the Y-axis direction with respect to the first gear section 723b.

[0148] A transmission ratio “i” of the gear mechanism 72, which is a planetary gear of the solar system type, is expressed by the following expression (6) using the number of teeth z1 of the sun gear 721, the number of teeth z2 of the ring gear 722, the number of teeth z3 of the first gear section 723b and the number of teeth z4 of the second gear section 723c. i=(z1 / z2)⋅(z3 / z4)+1

[0149] The number of teeth for each of the sun gear 721, the ring gear 722, the first gear section 723b, and the second gear section 723c in the gear mechanism 72 is determined such that the rotational speed of the ring gear 722 is twice that of the rotor 331. Specifically, the number of teeth for each of the sun gear 721, the ring gear 722, the first gear section 723b, and the second gear section 723c in the gear mechanism 72 is determined such that the gear ratio “i” of the rotational speed of the ring gear 722 to the rotational speed of the rotor 331 is equal to 2. Consequently, for every one revolution of the rotor 331, the ring gear 722 completes two revolutions in the same direction as the rotation of the rotor 331.

[0150] The weight 71 is attached to the ring gear 722. Consequently, the weight 71 rotates integrally with the ring gear 722. Thus, the center of rotation of the weight 71 coincides with the axis of the main body 3. Furthermore, the position of the center of gravity 71a of the weight 71 is specified as a position separated from the center of rotation of the weight 71 in a direction orthogonal to the center of rotation of the weight 71. In this embodiment, the position of the center of gravity 71a of the weight 71 is specified as a position separated from the center of rotation of the weight 71 in a direction along a second imaginary line. The center of gravity 71a of the weight 71 moves along a circle with the center of rotation of the weight 71 as its center point, together with the rotation of the weight 71.

[0151] The wheel assembly 1 is arranged such that, in a state where the direction along the second imaginary line coincides with the Z-axis direction, the position of the center of gravity 71a of the weight 71 is located on a negative side in the Z-axis direction with respect to the center of rotation of the weight 71. When the direction along the second imaginary line in the wheel assembly 1 coincides with the vertical direction, the position of the center of gravity 71a of the weight 71 is thus located below the center of rotation of the weight 71. Other configurations in the fifth embodiment are the same as those in the first embodiment.

[0152] In the wheel assembly 1 described above, the torque of the main body electric motor 33 is transmitted to the weight 71 via the gear mechanism 72, so that the rotational speed of the weight 71 becomes twice that of the rotor 331. As in the third embodiment, the rotational speed of the weight 71 can thus be set more reliably to be more than twice that of the rotating frame 34. Furthermore, the gear mechanism 72 can be made smaller.

[0153] Furthermore, the main body electric motor 33 is an external rotor type electric motor, and the gear mechanism 72 is a solar system type planetary gear mechanism. Thus, the number of moving components in the wheel assembly 1 can be reduced. Consequently, the occurrence of a defect in the wheel assembly 1 can be reliably suppressed, thus further improving the reliability of the wheel assembly 1.

[0154] Fig. Figure 24 is a sectional view illustrating a wheel assembly according to a sixth embodiment. Fig. 24 corresponds Fig. 2 according to the first embodiment. A vibration damping structural unit 7 is arranged on a rotating frame 34, which rotates integrally with a rotor 331. Furthermore, the vibration damping structural unit 7 is arranged on the outside in the lateral direction of the body with respect to the rotating frame 34, i.e., on the negative side in the Y-axis direction with respect to the rotating frame 34. The vibration damping structural unit 7 comprises a weight 71 and a vibration damping electric motor 73. In this embodiment, the vibration damping structural unit 7 does not have a gear mechanism.

[0155] The vibration damping electric motor 73 is an electric motor that differs from the main body electric motor 33. One axis of the vibration damping electric motor 73 coincides with an axis of the main body 3. The vibration damping electric motor 73 generates a torque for rotating the weight 71. The vibration damping electric motor 73 has a weight drive section 731 and a weight drive shaft 732.

[0156] The weight drive section 731 is attached to the rotating frame 34. Consequently, the weight drive section 731 rotates integrally with the rotating frame 34 about the axis of the main body 3.

[0157] The weight drive shaft 732 is rotatably mounted on the weight drive unit 731. Furthermore, one axis of the weight drive shaft 732 coincides with the axis of the main body 3. When electrical energy is supplied to the weight drive unit 731, the weight drive shaft 732 is rotated about the axis of the main body 3 with respect to the weight drive unit 731.

[0158] Each of the main body electric motor 33 and the vibration damping electric motor 73 is controlled by a controller (not shown). The controller regulates each of the main body electric motor 33 and the vibration damping electric motor 73 such that the rotational speed of the weight drive shaft 732 relative to the weight drive area 731 and the rotational speed of the rotor 331 relative to the stator 332 are set to be the same. Furthermore, the controller regulates each of the main body electric motor 33 and the vibration damping electric motor 73 such that the weight drive shaft 732 and the rotor 331 rotate in the same direction. Consequently, the weight drive shaft 732, as viewed from the fixed frame 31 and the stator 332, rotates in the same direction as the rotating frame 34, but at twice the rotational speed of the rotating frame 34.

[0159] The weight 71 is attached to the weight drive shaft 732. Consequently, the weight 71 rotates integrally with the weight drive shaft 732 about the axis of the main body 3. The centerline of rotation of the weight 71 coincides with the axis of the main body 3. Furthermore, the rotational speed of the weight 71 is equal to the rotational speed of the weight drive shaft 732. Consequently, the weight 71, viewed from the fixed frame 31 and the stator 332, rotates in the same direction as the rotation of the rotating frame 34, but at twice the rotational speed of the rotating frame 34.

[0160] One configuration of the weight 71 is the same as the configuration of the weight 71 in the first embodiment. Thus, the position of the center of gravity 71a of the weight 71 is specified as a position separated from the center of rotation of the weight 71 in a direction orthogonal to the center of rotation of the weight 71. In this embodiment, the position of the center of gravity 71a of the weight 71 is specified as a position separated from the center of rotation of the weight 71 in a direction along a second imaginary line. The center of gravity 71a of the weight 71 is moved along a circle with the center of rotation of the weight 71 as its center point, together with the rotation of the weight 71.

[0161] The wheel assembly 1 is arranged such that the position of the center of gravity 71a of the weight 71 is on a negative side in the Z-axis direction with respect to the center of rotation of the weight 71, in a state where the direction along the second imaginary line coincides with the Z-axis direction. When the direction along the second imaginary line in the wheel assembly 1 coincides with the vertical direction, the position of the center of gravity 71a of the weight 71 is thus below the center of rotation of the weight 71. Other configurations in the sixth embodiment are the same as those in the third embodiment.

[0162] In the wheel assembly 1 described above, the vibration-damping electric motor 73, which generates the torque for rotating the weight 71, is arranged on the rotating frame 34. This eliminates the need for a gear mechanism, thus simplifying the configuration of the wheel assembly 1. Consequently, the occurrence of a defect in the wheel assembly 1 can be suppressed more reliably, thereby improving the reliability of the wheel assembly 1.

[0163] In the sixth embodiment, the vibration damping structural unit 7 is arranged on the rotary frame 34. However, the vibration damping structural unit 7 can also be arranged on a main shaft 32 that rotates integrally with the rotor 331. In this case, the weight drive section 731 of the vibration damping electric motor 73 is attached to the main shaft 32. Furthermore, in this case, the vibration damping structural unit 7 can be arranged at a first end section 321 or a second end section 322 of the main shaft 32. If the vibration damping structural unit 7 is arranged at the second end section 322 of the main shaft 32, the main shaft 32 is positioned such that it extends through a turntable section 342 of the rotary frame 34.

[0164] Fig. Figure 25 is a sectional view illustrating a wheel assembly according to a seventh embodiment. Fig. 25 corresponds Fig.2 according to the first embodiment. As in the fifth embodiment, the main body electric motor 33 is thus an external rotor type electric motor. A vibration damping structural unit 7 is arranged on an outer side in a lateral direction of a body with respect to a rotating frame 34, i.e., on a negative side in the Y-axis direction with respect to the rotating frame 34. Furthermore, the vibration damping structural unit 7 is mounted on a stator 332 through a through-hole 343 of the rotating frame 34.

[0165] One configuration of the vibration damping structural unit 7 is the same as the configuration of the vibration damping structural unit 7 in the sixth embodiment. In the vibration damping structural unit 7, a vibration damping electric motor 73, which generates a torque for rotating a weight 71, is arranged on the stator 332. An axis of the vibration damping electric motor 73 coincides with an axis of the main body 3. A weight drive section 731 of the vibration damping electric motor 73 is attached to the stator 332 through the through-hole 343 of the rotating frame 34. When electrical energy is supplied to the weight drive section 731, a weight drive shaft 732 of the vibration damping electric motor 73 is rotated about the axis of the main body 3 with respect to the weight drive section 731.

[0166] Each of the main body electric motor 33 and the vibration damping electric motor 73 is controlled by a controller (not shown). The controller regulates each of the main body electric motor 33 and the vibration damping electric motor 73 such that the rotational speed of the weight drive shaft 732 relative to the weight drive area 731 is twice the rotational speed of a rotor 331 relative to the stator 332. Furthermore, the controller regulates each of the main body electric motor 33 and the vibration damping electric motor 73 such that the weight drive shaft 732 and the rotor 331 rotate in the same direction. Consequently, the weight drive shaft 732 rotates in the same direction as the rotating frame 34 at twice the rotational speed of the rotating frame 34.

[0167] The weight 71 is attached to the weight drive shaft 732. Consequently, the weight 71 rotates integrally with the weight drive shaft 732 about the axis of the main body 3. Thus, the weight 71 rotates in the same direction as the direction of rotation of the rotating frame 34 at twice the rotational speed of the rotating frame 34.

[0168] One configuration of the weight 71 is the same as the configuration of the weight 71 in the sixth embodiment. Thus, the position of the center of gravity 71a of the weight 71 is specified as a position separated from the center of rotation of the weight 71 in a direction orthogonal to the center of rotation of the weight 71. In this embodiment, the position of the center of gravity 71a of the weight 71 is specified as a position separated from the center of rotation of the weight 71 in a direction along a second imaginary line. The center of gravity 71a of the weight 71 is moved along a circle with the center of rotation of the weight 71 as its center point, together with the rotation of the weight 71.

[0169] The wheel assembly 1 is arranged such that the position of the center of gravity 71a of the weight 71 is on a negative side in the Z-axis direction with respect to the center of rotation of the weight 71, in a state where the direction along the second imaginary line coincides with the Z-axis direction. When the direction along the second imaginary line in the wheel assembly 1 coincides with the vertical direction, the position of the center of gravity 71a of the weight 71 is thus below the center of rotation of the weight 71. Other configurations in the seventh embodiment are the same as those in the fifth embodiment.

[0170] In the wheel assembly 1 described above, the vibration-damping electric motor 73, which generates the torque for rotating the weight 71, is arranged on the stator 332. This eliminates the need for a gear mechanism, thus simplifying the configuration of the wheel assembly 1. Consequently, the occurrence of a defect in the wheel assembly 1 can be suppressed more reliably, thereby improving the reliability of the wheel assembly 1.

[0171] In the seventh embodiment, the vibration damping structural unit 7 is arranged on the stator 332. However, the vibration damping structural unit 7 can also be arranged on a fixed frame 31. In this case, the vibration damping structural unit 7 is arranged on the inside of the body in the lateral direction with respect to the fixed frame 31. Furthermore, in this case, the weight drive section 731 of the vibration damping electric motor 73 is attached to the fixed frame 31.

[0172] Furthermore, in the fourth embodiment, the weight 71 with center of gravity 71a in an adjustable position is used as the weight 71 of the vibration damping structural unit 7, which is used in the first embodiment. However, the weight 71 according to the fourth embodiment, which has the center of gravity 71a in an adjustable position, can also be used as the weight 71 of the vibration damping structural unit 7 in the second, third, sixth, and seventh embodiments.

[0173] Furthermore, in each of the embodiments described above, the axis of rotation of the weight 71 coincides with the axis of the main body 3. However, the axis of rotation of the weight 71 can also be offset from the axis of the main body 3. In this way, at least part of the driving force generated by a whirl of the intermediate element 4 can be counteracted by the centrifugal force of the weight 71. Consequently, the vibration of the wheel assembly 1 as a whole can be suppressed.

[0174] Furthermore, in each of the embodiments described above, the second imaginary line is orthogonal to the first imaginary line. However, the second imaginary line need not be orthogonal to the first imaginary line, as long as the second imaginary line is a line that is orthogonal to the axis of the intermediate element 4 and differs from the first imaginary line.

[0175] Furthermore, in each of the embodiments described above, the tire 2 is made of a metal such as iron. However, the tire 2 can also be made of an elastic material, such as rubber. If the tire 2 is made entirely of metal, the wheel device 1 can be selectively subjected to energy, for example, to detect the vehicle on a rail.

[0176] Furthermore, the wheel assembly 1 is used for a rail vehicle in each of the embodiments described above. However, the wheel assembly 1 can also be used for various other vehicles or movable devices, e.g., for a car, a two-wheeled motor vehicle, and an elevator. Reference symbol list 1 Wheel assembly 2 tires 3 main bodies 4 Intermediate element 7 Vibration damping structural unit 32 Main shaft 33 Main body electric motor 34 rotating frames (main body rotation range) 35 Gear mechanism 51 first elastic plate (first elastic body) 61 second elastic plate (second elastic body) 71 weight 71a Focus 72 Gear mechanism 73 Vibration damping electric motor 306 bearings 322 End range 331 Rotor 332 Stator 343 Through hole 351, 721 Sun wheel 352, 722 Ring gear 353, 723 planetary gear 711 Mounting seat 722 Ring gear 731 Weight drive range 732 Weight drive shaft

Claims

[1] Wheel assembly comprising the following: - a main body (3) having a rotatable main body rotation area (34); - an intermediate element (4) with a ring-shaped form that surrounds the main body rotation area (34); - a tire (2) with a ring-shaped form that surrounds the intermediate element (4); - a first elastic body (51) designed to couple the intermediate element (4) and the tire (2) such that the intermediate element (4) is movable with respect to the tire (2) along a first imaginary straight line that is orthogonal to an axis of the intermediate element (4); - a second elastic body (61) designed to couple the intermediate element (4) and the main body rotation area (34) such that the intermediate element (4) is movable with respect to the main body (3) along a second imaginary line which is orthogonal to the axis of the intermediate element (4) and intersects the first imaginary line; and - a vibration damping structural unit (7) attached to the main body (3), wherein the vibration damping structural unit (7) has a weight (71) designed to be rotated in the same direction as the direction of rotation of the main body rotation range (34) at a speed twice that of the main body rotation range (34), and wherein, if a direction along the second imaginary line coincides with a vertical direction, a position of the center of mass (71a) of the weight (71) is located below a position of a rotation centerline of the weight (71). [2] Wheel device according to claim 1, wherein a distance from the center line of rotation of the weight (71) to the center of gravity (71a) of the weight (71) in the weight (71) is adjustable. [3] Wheel device according to claim 1 or 2, wherein the product of the distance from the rotational center line of the weight (71) to the center of gravity (71a) of the weight (71) and the mass of the weight (71) is equal to one quarter of the product of the displacement of the intermediate element (4) in the vertical direction caused by the rotation of the tire (2) and the mass of the intermediate element (4). [4] Wheel device according to one of claims 1 to 3, wherein the main body (3) has a main body electric motor (33) designed to generate a torque for rotating the main body rotation area (34). [5] Wheel assembly according to claim 4, wherein the main body electric motor (33) comprises the following: - a stator (332); and - a rotor (331) designed to be rotated relative to the stator (332), wherein the weight (71) is designed to rotate integrally with the rotor (331), and wherein the main body (3) has a gear mechanism (35) designed to transmit the torque of the main body electric motor (33) to the main body rotation range (34) such that the rotational speed of the main body rotation range (34) becomes equal to half the rotational speed of the rotor (331). [6] Wheel assembly according to claim 4, wherein the main body electric motor (33) comprises the following: - a stator (332); and - a rotor (331) designed to be rotated relative to the stator (332), wherein the main body rotation area (34) is designed to rotate integrally with the rotor (331), and wherein the vibration damping structural unit (7) includes a gear mechanism (72) designed to transmit the torque of the main body electric motor (33) to the weight (71) such that the rotational speed of the weight (71) becomes equal to half the rotational speed of the rotor (331). [7] Wheel assembly according to claim 5 or 6, wherein the transmission mechanism (35, 72) comprises the following: - a sun wheel (351, 721); - a ring-shaped hollow gear (352, 722) surrounding the sun gear (351, 721); and - Planet gears (353, 723) arranged between the sun gear (351, 721) and the ring gear (352, 722), wherein each of the planetary gears (353, 723) has the following: - a first gear section (353b, 723b) designed to engage with the ring gear (352, 722); and - a second gear section (353c, 723c) designed to engage with the sun gear (351, 721), wherein the first gear section (353b, 723b) is mounted coaxially to the second gear section (353c, 723c), and where the number of teeth in the first gear section (353b, 723b) differs from the number of teeth in the second gear section (353c, 723c). [8] Wheel device according to one of claims 1 to 4, wherein the vibration damping structural unit (7) has a vibration damping electric motor (73) designed to generate a torque for rotating the weight (71).

Images