Sphere rotation retaining device and sphere drive type moving appratus

Abstract

Provided is a sphere rotation retaining device characterized by including a plurality of rollers having a first rotation axis parallel to one virtual plane, a retention member for retaining the plurality of rollers, and a rotation mechanism for rotating the retention member and the rollers around a second rotation axis orthogonal to the first rotation axis, at least one of the plurality of rollers being in contact with a sphere, the roller in contact with the sphere being changed to another roller due to rotation by the rotation mechanism. Also provided is a sphere drive type moving apparatus comprising said device.

Description

Spherical rotation and holding device and spherical drive type moving device

[0001] The present invention relates to a sphere rotation holding device that holds a rotating sphere, and a sphere-driven moving device that uses the same.

[0002] There is a spherical-drive mobile device that can move in all directions by rotating a sphere. Because the spherical-drive mobile device can move in all directions, it can be used for, for example, robots, electric wheelchairs, self-propelled carts, transport carts, etc.

[0003] Patent Document 1 discloses a ball-driven omnidirectional mobile device that provides three balls and a carriage that moves the balls via rotors driven by three motors. In the ball-driven omnidirectional mobile device of Patent Document 1, the three drive balls are supported by three support ball casters and three wheel casters (idlers). Each support ball caster is in contact with the vertex of the drive ball. The wheel casters are in contact with the side of the drive ball at the same height as the center of rotation of the drive ball, and are arranged to press the drive ball against the rotor.

[0004] Patent Document 2 discloses a spherical-drive omnidirectional mobile device that provides three spheres and a carriage that moves the spheres via rotating bodies driven by three motors. Specifically, three identically shaped drive spheres are arranged at the vertices of a triangle in plan view. The three rotating bodies, which contact each sphere at two points, are driven by motors, enabling omnidirectional movement. This spherical-drive omnidirectional mobile device is supported by ball casters located at the vertices of a triangle formed outside the center of the three drive spheres, which contact and support the drive spheres. Patent Document 2 also discloses that omniwheels may be used instead of ball casters.

[0005] Japanese Patent Application Laid-Open No. 2010-30360 International Publication No. 2020-110651

[0006] The invention of Patent Document 1 is constrained by the requirement that the wheel-type caster and rotor must be positioned facing each other at the same height as the center of rotation of the driving sphere. Therefore, it is necessary to position each support ball-type caster at the vertex of the driving sphere and secure space for the wheel-type caster and rotor of the sphere. Furthermore, the ball caster structure used in the ball-driven transport devices disclosed in Patent Documents 1 and 2 consists of a single large main ball, multiple small sub-balls supporting it, and a jig that surrounds and secures them. As a result, when the large ball rotates, the smaller balls rotate in the opposite direction and move within the jig, thereby dissipating the rotational force of the large ball. However, when multiple small balls come into contact with each other during rotation, sounds are generated simultaneously or consecutively, and these sounds may combine to create noise. Furthermore, omniwheels, which can be used instead of ball casters, do not generate the noise caused by small balls coming into contact with each other like ball casters, but they require a large space above the driving sphere, which makes the entire ball-driven transport device larger.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a driving sphere holding mechanism that is compact yet reduces noise.

[0008] (1) To solve the above problem, the present invention provides a sphere rotation and holding device comprising: a plurality of rollers having a first rotation axis parallel to an imaginary plane; a holding member for holding the plurality of rollers; and a rotation mechanism for rotating the holding member and the rollers about a second rotation axis perpendicular to the first rotation axis, wherein at least one of the plurality of rollers is in contact with the sphere, and rotation by the rotation mechanism changes the roller in contact with the sphere. (2) Another invention to solve the above problem is the sphere rotation and holding device described in claim 1, characterized in that the force received from the sphere has at least a component parallel to the second rotation axis. (3) Another invention to solve the above problem is the sphere rotation and holding device described in claim 1, wherein the plurality of rollers are radial bearings and the rotation mechanism is a thrust bearing. (4) Another invention to solve the above problem is the sphere rotation and holding device described in claim 3, wherein the rotation mechanism includes a thrust bearing configured inside or directly below the arrangement of the plurality of rollers. (5) Another invention for solving the above problem is the sphere rotation and holding device according to claim 1, wherein an angle formed between an imaginary line connecting the contact point between the roller and the sphere and the center of the sphere and the second rotation axis is less than 90°. (6) Another invention for solving the above problem is the sphere rotation and holding device according to claim 1, characterized in that the plurality of rollers are arranged radially around the second rotation axis. (7) Another invention for solving the above problem is a sphere drive-type moving device comprising the sphere rotation and holding device according to any one of claims 1 to 6 and a drive device that drives the sphere.

[0009] According to the present invention, it is possible to provide a driving sphere holding mechanism that is compact yet reduces noise.

[0010]

[0023] FIG. 1 is a bottom view of a sphere-driven transport device to which this embodiment is applied;

[0024] FIG. 2 is a diagram for explaining the positional relationship between the drive sphere, silent caster, and rotor;

[0025] FIG. 3 is a side view of a sphere-driven transport device to which this embodiment is applied;

[0026] (A) is a perspective view of a sphere rotational holding device, and (B) is a cross-sectional perspective view of the sphere rotational holding device;

[0027] (A) is a diagram explaining the movement of the sphere rotational holding device and the drive sphere, and (B) is a plan view of the sphere rotational holding device and the drive sphere;

[0028] (A) to (C) are diagrams explaining how stress transmission changes depending on the positional difference between the sphere rotational holding device and the drive sphere;

[0029] (A) is a diagram showing an example of the arrangement of radial bearings in the sphere rotational holding device, and (B) is a diagram showing another example of the arrangement of radial bearings in the sphere rotational holding device;

[0029] (A) is a perspective view of a silent caster having another example of the radial bearing arrangement, and (B) is a cross-sectional perspective view of a silent caster having another example of the radial bearing arrangement. (A) is a diagram showing the back side of a conventional ball-driven mobile device, (B) is a side view showing the positional relationship between the ball and ball caster of the conventional ball-driven mobile device, and (C) is a cross-sectional view of the ball caster.

[0011] In a spherical-drive mobile device, a rotor transmits the power of a motor to a drive sphere, causing the drive sphere to rotate and move the spherical-drive mobile device. Figure 9(A) shows the rear view of a conventional spherical-drive mobile device. The drive sphere 110 is in contact with rotors 140a and 160b, and the drive sphere 110 rotates due to the rotation of rotors 140a and 160b driven by motors 180 and 220. The drive sphere 110 is supported by ball casters 240 attached to a base member 270. Note that the drive sphere 110 is not in constant contact with auxiliary support mechanisms 300 and 310; if the drive sphere 110 shifts position, the auxiliary support mechanisms 300 and 310 support the drive sphere 110. The auxiliary support mechanisms 300 and 310 are also ball casters smaller in size than the ball casters 240.

[0012] Fig. 9B is a side view showing the positional relationship between the sphere and the ball caster of a conventional sphere-driven transportation device. In Fig. 9B, the driving sphere 110 is in contact with the rotor 160b, the rotor 140a (not visible in Fig. 9B), the ball caster 240, and the running surface G at four points.

[0013] 9(C) is a cross-sectional view of a ball caster 240 used in a conventional ball-driven transport device. The ball caster 240 includes a main ball 210, multiple sub-balls 211, a dustproof seal 212, a seat 213, a case 214, and a cap 215. The multiple sub-balls 211 are packed in the gap between the main ball 210 and the seat 213. External stress on the main ball 210 is supported by the multiple internal sub-balls 211, and as the main ball 210 rotates, the multiple sub-balls 211 also rotate and move. When the multiple sub-balls 211 come into contact with each other, sounds are generated simultaneously or successively and these sounds are combined to produce noise.

[0014] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a bottom view of a spherical-body-driven transport device 1 to which this embodiment is applied. The spherical-body-driven transport device 1 is configured by combining drive spheres 11, 12, and 13, rotors 14a, 14b, 15a, 15b, 16a, and 16b, motors 18, 20, and 22, silent casters 24, 25, and 26, a base member 27, and auxiliary support mechanisms 30, 31, 32, 33, 34, and 35. The spherical-body-driven transport device 1 moves on a running surface G (see FIG. 3) by rotating the drive spheres 11, 12, and 13 that are in contact with the running surface G. For example, the spherical-body-driven transport device 1 can be used as a cart for transporting luggage, with luggage being loaded on the base member 27.

[0015] Rotors 14a and 14b are rotationally driven by the rotational force of motor 18 transmitted via a shaft or a power transmission belt. Rotors 15a and 15b are rotationally driven by the rotational force of motor 20 transmitted via a shaft or a power transmission belt. Rotors 16a and 16b are rotationally driven by the rotational force of motor 22 transmitted via a shaft or a power transmission belt. Rotors 14a and 16b rotate the driving sphere 11 they are in contact with. Rotors 14b and 15a rotate the driving sphere 12 they are in contact with. Rotors 15b and 16a rotate the driving sphere 13 they are in contact with.

[0016] In this embodiment, the drive spheres 11, 12, and 13 are all spheres of the same size (diameter) and are arranged at the vertices of an equilateral triangle. However, the drive spheres 11, 12, and 13 may each have a different size (diameter), and the three sides of the triangle with the center of each drive sphere 11, 12, and 13 as a vertex may each have different lengths. The drive sphere 11 moves the ball-drive type moving device 1 by rotating in contact with the rotors 14a and 16b and receiving a rotational driving force. The drive sphere 12 moves the ball-drive type moving device 1 by rotating in contact with the rotors 14b and 15a and receiving a rotational driving force. The drive sphere 13 moves the ball-drive type moving device 1 by rotating in contact with the rotors 15b and 16a and receiving a rotational driving force.

[0017] Drive spheres 11, 12, and 13 are in contact with silent casters 24, 25, and 26, respectively. That is, drive sphere 11 is in contact with rotors 14a and 16b, silent caster 24, and running surface G (see FIG. 3). Drive sphere 12 is in contact with rotors 14b and 15a, silent caster 25, and running surface G (see FIG. 3). Drive sphere 13 is in contact with rotors 15b and 16a, silent caster 26, and running surface G (see FIG. 3).

[0018] In the case of a spherical-drive mobile device having three drive spheres, as in this embodiment, conditions for suppressing free rotation between the drive spheres and the rotor are described in International Publication No. 2020-110651. It is preferable that the silent casters 24, 25, and 26 are arranged around the outer vertices of the triangle formed by the three drive spheres 11, 12, and 13 in a plan view. Furthermore, it is preferable that the three contact points between the drive sphere 11 and the rotors 14a, 16b, and the silent caster 24 are located above the center P1 of the drive sphere 11. Similarly, it is preferable that the three contact points between the drive sphere 12 and the rotors 14b, 15a, and the silent caster 25 are located above the center P2 of the drive sphere 12. Similarly, it is preferable that the three contact points between the drive sphere 13 and the rotors 15b, 16a, and the silent caster 26 are located above the center P3 of the drive sphere 13.

[0019] With the above-described configuration, the weight of the base member 27 and any heavy objects placed on the base member 27 can be utilized to press the drive sphere 11 from above at three contact points: the rotors 14a and 16b, and the silent caster 24. Similarly, the drive sphere 12 can be pressed from above at three contact points: the rotors 14b and 15a, and the silent caster 25. Similarly, the drive sphere 13 can be pressed from above at three contact points: the rotors 15b and 16a, and the silent caster 26. The greater the load from above, the less the drive spheres 11, 12, and 13 will spin freely relative to the rotors 14a and 16b, 14b and 15a, and 15b and 16a, respectively. In other words, a powerful torque can be generated in the drive spheres 11, 12, and 13. In other words, the drive spheres 11, 12, and 13 can generate a propulsive force with a powerful torque when pressed by the three contact points from above.

[0020] Auxiliary support mechanisms 30 and 31 are not normally in contact with drive sphere 11, but have a mechanism that contacts drive sphere 11 and corrects the positional deviation only if drive sphere 11 is misaligned to prevent it from coming off. Similarly, auxiliary support mechanisms 32 and 33 have a mechanism for correcting the positional deviation relative to drive sphere 12, and auxiliary support mechanisms 34 and 35 have a mechanism for correcting the positional deviation relative to drive sphere 13. Auxiliary support mechanisms 30, 31, 32, 33, 34, and 35 may be ball bearings or idlers.

[0021] Silent casters 24, 25, and 26 are ball rotation and holding devices that hold rotating balls, and in this embodiment, are highly quiet ball rotation and holding devices that replace conventional ball caster 240 (see FIG. 9). In this embodiment, silent casters 24, 25, and 26 all have the same structure and size, and are fixed to base member 27 so as to support drive balls 11, 12, and 13, respectively. The structure of silent caster 24 will be described in detail later, so here, the main features of silent caster 24 will be briefly described using FIG. 2.

[0022] Figure 2 is a diagram illustrating the positional relationship between the drive sphere, silent casters, and rotors. In Figure 2, the drive sphere 11 is in contact with the rotors 14a, 16b, and silent casters 24. The auxiliary support mechanisms 30, 31 prevent the drive sphere 11 from shifting position and becoming detached, and are normally not in contact with the drive sphere 11.

[0023] The silent caster 24 includes multiple rollers, one or two of which are in contact with the driving sphere 11. The rollers rotate around their rotation axis (first rotation axis) in the direction indicated by the arrow R1. The retaining member 44, which supports the multiple rollers, can rotate around a rotation axis (second rotation axis) that passes through the center of the retaining member 44 and is perpendicular to the retaining member 44, as indicated by the arrow R2. As the retaining member 44 rotates around the second rotation axis, the roller that was in contact with the driving sphere 11 separates from the driving sphere 11, and one of the other rollers that was previously out of contact comes into contact, repeating this process. In other words, the roller that contacts the sphere changes as the retaining member 44 rotates. Unlike conventional ball casters 240 (see Figure 9), the silent caster 24 eliminates the risk of multiple sub-balls coming into contact and generating noise. Therefore, the silent caster 24 is used as a sphere rotation and holding device that can reduce noise.

[0024] 3 is a side view showing a sphere-driven transportation device 1 to which this embodiment is applied. Drive sphere 11 contacts rotors 14a and 16b (see FIG. 1), silent casters 24, and running surface G. Drive sphere 12 contacts rotors 14b and 15a (see FIG. 1), silent casters 25, and running surface G. Rotors 14a and 14b contact drive spheres 11 and 12 at positions higher than center P1 of drive sphere 11 and center P2 of drive sphere 12, respectively. Similarly, although not shown, rotors 15a and 15b contact drive spheres 12 and 13 at positions higher than center P2 of drive sphere 12 and center P3 of drive sphere 13, respectively. Similarly, although not shown, rotors 16a and 16b are in contact with drive spheres 13 and 11 at positions higher than the center P3 of drive sphere 13 and the center P1 of drive sphere 11, respectively. In this embodiment, silent casters 24, 25, and 26 are also in contact with drive spheres 11, 12, and 13 at positions higher than the centers P1, P2, and P3 of drive spheres 11, 12, and 13, respectively.

[0025] Therefore, a vertical component of force acts on drive sphere 11 through rotors 14a and 16b and silent caster 24, a vertical component of force acts on drive sphere 12 through rotors 14b and 15a and silent caster 25, and a vertical component of force acts on drive sphere 13 through rotors 15b and 16a and silent caster 26. Therefore, by utilizing the weight of base member 27 and heavy objects placed on base member 27, rotors 14a, 14b, 15a, 15b, 16a, 16b and silent casters 24, 25, 26 can press drive spheres 11, 12, 13, preventing the rotors from spinning freely.

[0026] 4A is a perspective view of the sphere rotation holding device, and FIG. 4B is a cross-sectional perspective view of the sphere rotation holding device. The silent caster 24 as the sphere rotation holding device is composed of a roller 41, a support member 42, a fastening member 43, a holding member 44, thrust bearings 46a and 46b, and a caster fixing base 51.

[0027] The silent caster 24 is composed of multiple rollers 41. For example, in FIG. 4A, the silent caster 24 is composed of thirteen doughnut-shaped rollers 41. A ring-shaped support member 42 passes through the center of each of the rollers 41. The rollers 41 rotate R1 around the support member 42. Although the directions of the rotation axes (first rotation axes) of the multiple rollers 41 are different, each rotation axis is parallel to an imaginary plane perpendicular to a line L5 passing through the center of the support member 42. In other words, the multiple first rotation axes are parallel to a single imaginary plane. The rollers 41 may be radial bearings that can withstand radial forces at the contact points with the driving spheres. A "radial bearing" is a bearing that can withstand forces applied perpendicular to the rotation axis.

[0028] The roller 41 may be a ball bearing in which balls are mounted as a plurality of rolling elements around the support member 42, which is the rotating shaft. Furthermore, the roller 41 may be a roller bearing in which rollers are mounted as a plurality of rolling elements around the support member 42, which is the rotating shaft. Furthermore, the roller 41 may be a sliding bearing that retains self-lubricating properties and can be used without oil, i.e., an oil-free bearing.

[0029] The rollers 41 and the support members 42 are fixed to the holding member 44 by fastening members 43. The fastening members 43 may be any fastening members capable of fixing the rollers 41 and the support members 42 to the holding member 44, and known bolts, screws, etc. may be used. The holding member 44 also has grooves formed at the positions where the rollers 41 are to be positioned. Because the grooves of the rollers 41 extend to the outer periphery of the circular holding member 44, rotation of the rollers 41 prevents debris from accumulating around the rollers 41 and allows debris to be discharged to the outside of the silent caster 24. Because the grooves for arranging the rollers 41 extend to the outer periphery of the holding member 44, debris and dust can be easily discharged.

[0030] The retaining member 44 is plate-shaped and has a hole near the center. A shaft member 45 penetrates the center of the retaining member 44, and the retaining member 44 rotates R2 around the shaft member 45 as a second rotation axis. The shaft member 45 rotatably secures the retaining member 44 to the caster fixing base. A thrust bearing 46a, which rotates around the shaft member 45, is disposed on the front surface of the retaining member 44, and a thrust bearing 46b is disposed on the back surface of the retaining member 44. The thrust bearings 46a and 46b are disposed in the space inside the ring of the rollers 41 and the support member 42. In other words, the thrust bearings 46a and 46b are disposed in two layers in the space inside the ring of the rollers 41 and the support member 42, stacked in two layers in the direction of the imaginary line L5, which is the second rotation axis. By effectively utilizing the space inside the arrangement of the rollers 41 in this way, the thrust bearings 46a and 46b can be made compact in the direction of the imaginary line L5.

[0031] The thrust bearings 46a and 46b may be ball bearings incorporating balls as the rolling elements, or roller bearings incorporating rollers as the rolling elements. Furthermore, the thrust bearings 46a and 46b may be self-lubricating plain bearings that can be used without oil supply, i.e., oil-free bearings.

[0032] As described above, silent caster 24 as a sphere rotation and holding device is composed of a plurality of rollers 41 having a first rotation axis parallel to one imaginary plane, holding member 44 that holds the plurality of rollers 41, and a rotation mechanism that rotates holding member 44 and rollers 41 around a second rotation axis of shaft member 45 that is perpendicular to the first rotation axis. When silent caster 24 is used to run a sphere-driven mobile device, at least one of the plurality of rollers 41 is in contact with the drive sphere, and rotation around the second rotation axis changes the roller that is in contact with the drive sphere.

[0033] As described above, the spherical rotation holding device of Fig. 4(A) can be said to be a bearing that includes a plurality of radial bearings, a holding member that holds the plurality of radial bearings, a thrust bearing having a second rotation axis that is perpendicular to the first rotation axis of the plurality of radial bearings, and the plurality of radial bearings and the holding member that rotate together with the rotation of the thrust bearing about the second rotation axis. This bearing is a component that receives a load by contacting a rotating or reciprocating mating component and is suitable for supporting a shaft or the like.

[0034] 5A is a cross-sectional view illustrating the movement of the sphere rotation holding device and the drive sphere 11, and FIG. 5B is a plan view of the sphere rotation holding device and the drive sphere 11. In FIG. 5A, not all of the rollers constituting the silent caster 24 are in contact with the drive sphere 11; roller 41a is in contact, but roller 41e is not. In response to the rotation r1 of the drive sphere 11, the contacting roller 41a rotates R1. At this time, the frictional force between the drive sphere 11 and roller 41a is nearly zero, as roller 41a rotates R1 in accordance with the rotation r1 of the drive sphere 11.

[0035] Furthermore, in response to the rotation r2 of the drive sphere 11, the holding member 44 holding the multiple rollers rotates R2. In the diagram shown in FIG. 5B, one roller 41a is in contact with the drive sphere 11, and rollers 41b to 41h are not in contact with the drive sphere 11. Then, in response to the rotation R2, the roller 41a that was in contact with the drive sphere 11 becomes non-contact, and the roller 41b next to the roller 41a, which had not been in contact until then, comes into contact, and this process is repeated. At this time, the roller 41a does not rub against the drive sphere 11 in a direction perpendicular to the rotation direction R1 of the one roller 41a that was in contact, and the roller 41a separates from the drive sphere 11 and contacts the next roller 41b, repeating this process. Therefore, even in the case of rotation R2, the frictional force between the drive sphere 11 and the rollers 41 is very small.

[0036] As explained above, even when the roller 41a rotates R1 in accordance with the rotation r1 of the driving ball 11, or when the driving ball 11 and the roller 41a repeatedly come into contact and out of contact due to rotation R2, the frictional force between the driving ball 11 and the roller 41 is very small. Therefore, the silent caster 24 has improved wear resistance compared to conventional ball casters.

[0037] Figures 6(A) to 6(C) are diagrams illustrating how stress transmission changes depending on the position of the sphere rotation holding device and the drive sphere. The silent caster 24 is equipped with a thrust bearing 46, as described in Figure 4(B). In Figure 6(A), the center P1 of the drive sphere 11, the imaginary line L6 connecting the contact point between the silent caster 24 and the drive sphere 11, and the rotation axis S1 of the thrust bearing 46 are parallel. In this case, the thrust bearing 46 can absorb all of the stress from the drive sphere 11. In other words, the stress absorption effect of the thrust bearing 46 is maximized. The silent caster 24 receives a force component parallel to the rotation axis S1 from the drive sphere 11 (or via the roller 41a).

[0038] 6(B), the angle α between the center P1 of the drive sphere 11, the imaginary line L6 connecting the point of contact between the silent caster 24 and the drive sphere 11, and the rotation axis S1 of the thrust bearing 46 is greater than or equal to 0° and less than 90°. In this case, the stress from the drive sphere 11 is resolved into a component f1 in the direction of the rotation axis of the thrust bearing 46 and a component f2 in a direction perpendicular to the rotation axis, and the thrust bearing 46 can absorb the component f1 in the direction of the rotation axis of the thrust bearing 46. The silent caster 24 receives at least a component of force parallel to the rotation axis S1 from the drive sphere 11 (or via the roller 41a).

[0039] In Figure 6(C), the imaginary line L6 connecting the center P1 of the drive sphere 11 and the point of contact between the silent caster 24 and the drive sphere 11 is perpendicular to the rotation axis S1 of the thrust bearing 46. In this state, the component of the stress from the drive sphere 11 in the direction of the rotation axis of the thrust bearing 46 is zero, so the thrust bearing 46 does not absorb any force. In other words, the stress absorption effect of the thrust bearing 46 is not being exerted. The silent caster 24 does not receive any force component parallel to the rotation axis S1 from the drive sphere 11 (or via the roller 41a).

[0040] 6(D), the angle α between the center P1 of the drive sphere 11, the imaginary line L6 connecting the point of contact between the silent caster 24 and the drive sphere 11, and the rotation axis S1 of the thrust bearing 46 is 0° or less (negative). In this case, the stress from the drive sphere 11 is resolved into a component f1 in the direction of the rotation axis of the thrust bearing 46 and a component f2 perpendicular to that component, and the thrust bearing 46 can absorb the component f1 in the direction of the rotation axis of the thrust bearing 46. The silent caster 24 receives force from the drive sphere 11 (or via the roller 41a) with at least a component parallel to the rotation axis S1.

[0041] If the angle α is widened even further toward the negative side than in the state shown in Figure 6(D), the diameter of the thrust bearing will be increased to prevent the roller 41e from touching the drive sphere 11. If the diameter of the thrust bearing is increased, the silent caster 24 may not be compact. Furthermore, the state in which the roller 41e is in contact with the drive sphere 11 means that all rollers of the silent caster 24 are in contact with the drive sphere 11. In the spherical rotation and holding device of the present invention, only the roller 41a contacts the silent caster 24 and the drive sphere 11, while the roller 41e does not, thereby reducing friction between the silent caster 24 and the drive sphere 11. Therefore, it is preferable for the silent caster 24 to be in use when only the roller 41a contacts the drive sphere 11 and the roller 41e does not.

[0042] From the above, considering the stress absorption effect of the thrust bearing 46 and the contact point between the silent caster 24 and the drive sphere 11, it is desirable that the angle formed by the imaginary line L6 connecting the contact point between the roller 41a and the drive sphere 11 and the center P1 of the drive sphere 11 and the rotation axis S1 of the thrust bearing 46 is less than 90° and is within a range where all rollers of the silent caster 24 do not come into contact with the drive sphere 11.

[0043] Figure 7(A) is a bottom view showing an example of the arrangement of radial bearings in a spherical rotation holding device, and (B) is a bottom view showing another example of the arrangement of radial bearings in a spherical rotation holding device. Figure 7(A) is a bottom view showing the arrangement of eight radial bearings in a silent caster 24. Eight rollers, 41a to 41h, are arranged at equal intervals radially around the center C1 of a circular holding member 44. The arrows indicating the movement directions of each of the rollers 41a to 41h are arranged so as to converge at the center C1 of the circular holding member 44. The rotation axes of each of the rollers 41a to 41h exist on a single imaginary plane (the plane of the paper).

[0044] Furthermore, although not shown in Fig. 7A, the thrust bearing described in Fig. 4B is formed inside the arrangement of the multiple radial bearings. The "inside" refers to an area A1 formed by the radius from the center C1 of the holding member 44 to the point closest to any of the rollers 41a to 41h in a plane, and in Fig. 4A it means the inside of the circular area A1.

[0045] The silent caster 24 of the present invention may have multiple radial bearing rollers 41, and the number of rollers is not particularly limited. Furthermore, the multiple rollers 41 do not need to be arranged radially toward the center. Another embodiment of the present invention may be a silent caster having an arrangement of multiple rollers 41 as shown in FIG. 7(B). In FIG. 7(B), the arrows indicating the movement directions of the rollers 41a to 41h do not converge on the center C1 of the circular holding member 44, but are arranged at a slight incline. However, the rotation axes of the rollers 41a to 41h exist on a single imaginary plane (the plane of the paper).

[0046] Furthermore, although not shown in Fig. 7B, the thrust bearing described in Fig. 4B is formed inside the arrangement of the multiple radial bearings. The "inside" refers to the area formed by the radius from the center C1 of the holding member 44 to the point closest to any of the rollers 41a to 41h in a plane, and in Fig. 4B it means the inside of the circular area A2.

[0047] FIG. 8(A) is a perspective view of a silent caster 24 having another example of radial bearing arrangement, and FIG. 8(B) is a cross-sectional perspective view thereof.

[0048] The silent caster 24 of FIG. 8(A) has, as radial bearings, rollers 411 that reach the circular edge of the holding member 44 and rollers 412 that are arranged inside the circular holding member 44. In another embodiment of the present invention, as shown in FIG. 8(A), multiple rollers may be arranged in a staggered pattern, with rollers 411 and 412 alternately arranged. In the example of FIG. 8(A), five rollers 411 and five rollers 412 are provided, for a total of ten rollers, but more rollers may be arranged. In particular, by closely arranging the rollers, the distance between adjacent rollers can be shortened, allowing the drive ball to move more smoothly between the bearings.

[0049] In the example of FIG. 4A , the multiple rollers 41 are supported by a ring-shaped support member 42. However, in the example of FIG. 8A , rollers 411 and 412 are supported by their own shafts. Also, in the example of FIG. 8A , rollers 411 and 412 have the same diameter, and their rotation axes are on the same plane. However, rollers 411 and 412 do not have to have the same diameter, and their rotation axes may be arranged one above the other and not on the same plane. For example, if roller 411 has a larger diameter than roller 412, the perpendicular line from the center of rotation axis 421 of roller 411 to virtual line L9, which is the center of the rotation axis of the thrust bearing, and the perpendicular line from the center of rotation axis 422 of roller 412 to virtual line L9 will not intersect at the same point, resulting in a misalignment in the direction of virtual line L9. However, the rotation axes of rollers 411 and 412 are both arranged so as to be parallel to one imaginary plane (an imaginary plane perpendicular to imaginary line L9). In other words, the multiple first rotation axes are parallel to one imaginary plane.

[0050] The holding member 44 has grooves formed at the positions where the rollers 411, 412 are arranged. The grooves of the rollers 411, 412 are structured to reach the outer periphery of the holding member 44, so that as the rollers 411, 412 rotate, dirt does not accumulate around the rollers 411, 412 and is discharged to the outside of the silent caster 24. In this way, because the grooves for arranging the multiple rollers 411, 412 reach the outer periphery of the holding member 44, dirt and dust can be easily discharged.

[0051] Figure 8(B) is a cross-sectional perspective view of the silent caster 24 having another example of the arrangement of radial bearings. As shown in Figure 8(B), the silent caster 24 of this embodiment is equipped with thrust bearings 46c and 46d. The silent caster 24 is equipped with the thrust bearing 46c in which balls are arranged so as to surround the periphery of the shaft member 45. Furthermore, the silent caster 24 is equipped with the thrust bearing 46d in which a plurality of balls are arranged on the outer periphery of the thrust bearing 46c.

[0052] In the example of Fig. 4(B), thrust bearings 46a and 46b are arranged so as to be stacked in two stages in the axial direction of shaft member 45. In the example of Fig. 8(B), thrust bearings 46c and 46d having different diameters are arranged in a direction perpendicular to the axis of shaft member 45.

[0053] Furthermore, in the example of Figure 4(B), thrust bearings 46a and 46b are compactly arranged inside the radial bearing arrangement. On the other hand, in the example of Figure 8(B), radial bearing rollers 411 and 412 are densely arranged in a staggered pattern, and thrust bearings 46c and 46d are arranged directly below the radial bearings. By arranging thrust bearings directly below the radial bearings in this way, the rigidity and load-bearing capacity of the silent caster can be improved. Here, "directly below" refers to the direction opposite to the drive spheres with which radial bearing rollers 411 and 412 contact, on imaginary line L9, which is the center of the thrust bearing's rotation axis.

[0054] Furthermore, the balls used as rolling elements in thrust bearing 46d are larger than the balls used as rolling elements in inner thrust bearing 46c. By making the outer bearing larger in this way, the force from the radial bearing is received directly below the bearing, thereby increasing rigidity.

[0055] The rollers 411, 412 and thrust bearings 46c, 46d, which are the radial bearings described above, may all be configured as ball bearings, roller bearings, or oil-free bearings.

[0056] As described above, silent casters in a spherical-driven mobile device have been described as an embodiment of the spherical rotation and holding device of the present invention, but the spherical rotation and holding device of the present invention can be applied not only to mobile devices but also to joints with spherical bodies in robots, manipulators, etc. Furthermore, the spherical-driven mobile device can be used for applications such as mobile robots, electric wheelchairs, self-propelled carts, and transport carts, which can move in all directions by rotating and driving a sphere.

[0057] 8(A) can be said to be a bearing that includes a plurality of radial bearings, a holding member that holds the plurality of radial bearings, a thrust bearing having a second rotation axis that is perpendicular to the first rotation axis of the plurality of radial bearings, and the plurality of radial bearings and the holding member that rotate together with the rotation of the thrust bearing about the second rotation axis. This bearing is a component that is suitable for receiving a load in contact with a rotating or reciprocating mating component and supporting a shaft or the like.

[0058] 1...sphere-driven moving device, 11, 12, 13, 110...drive sphere, 14a, 14b, 15a, 15b, 16a, 16b, 140a, 160b...rotor, 18, 20, 22, 180, 220...motor, 24, 25, 26...silent caster, 27, 270...base member, 30, 31, 32, 33, 34, 35, 300, 310...auxiliary support mechanism, 41, 41a, 41b, 411, 412...roller, 42, 421, 422 ...Support member, 43...Tightening member, 44...Retaining member, 45...Shaft member, 46, 46a, 46b, 46c, 46d...Thrust bearing, 51...Caster fixing base, 210...Main ball, 211...Sub-ball, 212...Dustproof seal member, 213...Receiving seat, 214...Case, 215...Cap, 240...Ball caster, C1...Center of retaining member, P1, P2, P3...Center of driving sphere, G...Running surface, L5, L6, L9...Virtual line

Claims

1. A sphere rotation and holding device comprising: a plurality of rollers each having a first rotation axis parallel to an imaginary plane; a holding member that holds the plurality of rollers; and a rotation mechanism that rotates the holding member and the rollers around a second rotation axis that is perpendicular to the first rotation axis, wherein at least one of the plurality of rollers is in contact with a sphere, and the roller in contact with the sphere changes due to rotation by the rotation mechanism.

2. The sphere rotation and holding device according to claim 1, characterized in that the force received from the sphere has at least a component parallel to the second rotation axis.

3. The spherical body rotation and holding device according to claim 1, wherein the plurality of rollers are radial bearings and the rotation mechanism is a thrust bearing.

4. The spherical body rotation and holding device according to claim 3, wherein the rotation mechanism includes a thrust bearing configured inside or immediately below the arrangement of the plurality of rollers.

5. The sphere rotation and holding device according to claim 1, wherein an angle formed by an imaginary line connecting the contact point between the roller and the sphere and the center of the sphere and the second rotation axis is less than 90°.

6. The spherical body rotation and holding device according to claim 1, characterized in that the plurality of rollers are arranged radially around the second rotation axis.

7. A ball-driving moving device comprising: a ball-rotating and holding device according to any one of claims 1 to 6; and a drive device for driving the ball.

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