Wheel unit

Abstract

This wheel unit comprises: an omni wheel having a large wheel rotatable about a first rotation axis, and a small wheel provided side by side on the outer periphery of the large wheel and rotatable about a second rotation axis; two lock plates which are provided at positions sandwiching the omni wheel and can move to a spaced position that is at a distance from a proximate position close to the large wheel; and two lever plates which are provided at positions sandwiching the two lock plates and can move to a push-in position for pushing the lock plates into the proximate position and a permissive position for permitting the lock plates to move to the spaced position. The two lock plates abut the small wheel when at the proximate position, and each of the lever plates pushes the lock plate to the proximate position from at least two places.

Description

Wheel unit

[0001] The present disclosure relates to a wheel unit.

[0002] A wheel unit having a rotatable wheel and a locking mechanism that can restrict the rotation of the wheel may be attached to the bottom of an object. When an object is equipped with a wheel unit, the wheel rotates and the object can be moved simply by pushing the object. This makes it easier to move the object than if the object were lifted up and moved. Furthermore, restricting the rotation of the wheel with a locking mechanism can restrict the movement of the object.

[0003] Here, an omni-wheel may be used as the wheel of the wheel unit. The omni-wheel has, for example, a large wheel and a plurality of small wheels arranged in a line around the outer periphery of the large wheel, and by making the directions of the rotation axes of the large wheel and the small wheels different, the degree of freedom in the direction of movement is improved. Patent Document 1 discloses a wheel unit that restricts and locks the rotation of the omni-wheel using a locking mechanism that presses a brake pad from one side of the omni-wheel.

[0004] Japanese Patent Application Laid-Open No. 2019-206249

[0005] However, with the configuration disclosed in Patent Document 1, the brake pads must be pressed from one side of the omni-wheel to restrict the rotation of both the large and small wheels, so the brake pads must be pressed firmly. Furthermore, because the force applied to the omni-wheel is applied from one side, it tends to deform the omni-wheel toward the other side. Therefore, there is a risk that the durability of the omni-wheel will be reduced if the locking mechanism locks the omni-wheel.

[0006] Therefore, the present disclosure proposes a wheel unit that can more reliably lock the rotation of an omni-wheel while suppressing a decrease in the durability of the omni-wheel.

[0007] In order to solve the above-mentioned problems, one form of wheel unit according to the present disclosure comprises an omni-wheel having a large wheel rotatable around a first rotation axis and a plurality of small wheels arranged in a row on the outer periphery of the large wheel, each of the plurality of small wheels rotatable around a second rotation axis parallel to the tangent direction of a circle centered on the first rotation axis; two locking plates arranged in a first direction parallel to the first rotation axis and sandwiching the omni-wheel therebetween, and each of the locking plates is movable between a close position close to the large wheel and a separated position distant from the large wheel; and two lever plates arranged in a first direction and sandwiching the two locking plates therebetween, and movable between a pushed position where the locking plate is pushed into the close position and an allowable position where the locking plate is allowed to move to the separated position, the two locking plates abutting against the small wheels in the close position, and each of the lever plates pushing the locking plate into the close position at at least two points.

[0008] 7 is a perspective view of a wheel unit according to a first embodiment. FIG. 8 is a perspective view of a wheel unit according to a first embodiment, showing a state seen from the opposite side of FIG. 1. FIG. 9 is a view of the omni-wheel as seen along a direction perpendicular to the first rotation axis. FIG. 10 is a view of the omni-wheel and lock plate as seen along a direction perpendicular to the first rotation axis. FIG. 11 is an exploded view of the omni-wheel and lock plate. FIG. 12 is a perspective view of the omni-wheel and lock plate. FIG. 13 is a view of the lock plate provided on the left as seen from the left along the first rotation axis. FIG. 14 is a cross-sectional view taken along line VIII-VIII shown in FIG. 7. FIG. 15 is a perspective view of the omni-wheel, lever plate, and lock plate, showing a state where the lever plate is in an allowable position. FIG. 16 is a perspective view of the omni-wheel, lever plate, and lock plate, showing a state where the lever plate is in a restricted position. FIG. 17 is a perspective view of the outer shell. FIG. 18 is a perspective view showing a modified lever plate. FIG. 19 is a view showing another modified lock plate as seen along the first rotation axis. A cross-sectional view taken along line XV-XV shown in Figure 14, showing a state where the lever plate is in the permitted position. A cross-sectional view taken along line XV-XV shown in Figure 14, showing a state where the lever plate is in the pushed-in position. A cross-sectional view taken along line XVII-XVII shown in Figure 15. A cross-sectional view showing a modified example of the lock plate and lever plate, showing a state where the lever plate is in the permitted position. A cross-sectional view showing a modified example of the lock plate and lever plate, showing a state where the lever plate is in the pushed-in position.

[0009] Hereinafter, embodiments for carrying out the present technology will be described. The description will be made in the following order: 1. Schematic configuration of wheel unit 2. Omni-wheel 3. Lock plate 4. Lever plate 5. Outer body 6. Modified example 7. Summary of effects 8. Supplementary notes

[0010] <<1. Schematic Configuration of Wheel Unit>> Fig. 1 is a perspective view of a wheel unit according to a first embodiment. Fig. 2 is a perspective view of the wheel unit according to the first embodiment, showing a state seen from the opposite side of Fig. 1. The wheel unit 1 includes an omni-wheel 2, a lock plate 3, a lever plate 4, and an outer shell 5. The wheel unit 1 is attached to the bottom surface of an object, for example, and supports the object from the floor surface. The wheel unit 1 enables the object to be moved without lifting it by rotating the omni-wheel 2.

[0011] <<2. Omni-Wheel>> Figure 3 is a view of the omni-wheel as viewed along the first rotation axis. Figure 4 is a view of the omni-wheel and lock plate as viewed along a direction perpendicular to the first rotation axis.

[0012] The omniwheel 2 has a large wheel 21 and small wheels 22. The large wheel 21 is rotatably mounted on the wheel unit 1 around a first rotation axis 21a. The large wheel 21 is formed in a generally annular shape centered on the first rotation axis 21a. The configuration that enables the large wheel 21 to rotate around the first rotation axis 21a will be described in detail later. As shown in FIGS. 1 and 3 , the first embodiment illustrates an example in which the large wheels 21 are arranged in two rows, but this is not limited to this. The large wheels 21 may be arranged in a single row, or in three or more rows. The large wheels 21 arranged in multiple rows rotate synchronously with each other.

[0013] A plurality of small wheels 22 are arranged in a circumferential direction on the outer periphery of the large wheel 21. Each of the small wheels 22 is rotatable about a second rotation axis 22a that is parallel to the tangent direction of a circle centered on the first rotation axis 21a. Note that, for ease of understanding, in Figure 2, of the two rows of large wheels 21, the small wheel 22 attached to the large wheel 21 on the far side of the page is omitted.

[0014] The small wheels 22 attached to adjacent large wheels 21 are positioned at positions offset from each other in the circumferential direction. As a result, as the large wheels 21 rotate, the small wheels 22 attached to the two rows of large wheels 21 alternately come into contact with the ground, allowing the omni-wheel 2 to roll smoothly. In this way, in the omni-wheel 2, the small wheels 22 that are in contact with the ground change as the large wheels 21 rotate. In each drawing showing the wheel unit 1, the small wheels 22 that are in contact with the ground are hatched.

[0015] The second rotation axis 22a of the grounded small wheel 22 and the first rotation axis 21a of the large wheel 21 extend in directions that differ by 90 degrees. Therefore, the small wheel 22 and the large wheel 21 rotate in directions that differ by 90 degrees, improving the degree of freedom in the direction of movement of the wheel unit 1.

[0016] Here, definitions will be given for the terms of coordinate axes and directions used in the following description. First, the X-axis parallel to the first rotation axis 21a is defined. The direction along the X-axis is the left-right direction (first direction), with the positive direction side being the right and the negative direction side being the left. A ground contact point of the omniwheel is set in the wheel unit 1. The Z-axis is defined as being perpendicular to the X-axis and parallel to the direction extending from the set ground contact point toward the first rotation axis 21a. The direction along the Z-axis is defined as the up-down direction, with the positive direction side being the upside and the negative direction side being the downside. The Y-axis is defined as being perpendicular to the X-axis and the Z-axis. The direction along the Y-axis is defined as the front-rear direction, with the positive direction side being the front and the negative direction side being the rear.

[0017] <<3. Lock Plates>> The wheel unit 1 includes two lock plates 3. The two lock plates 3 are plate-shaped members that are provided in the left-right direction with the omni-wheel 2 sandwiched between them. Each of the two lock plates 3 is movable left-right between a close position that is close to the large wheel 21 and a separated position that is separated from the large wheel 21. Note that Figure 4 shows the lock plate 3 in the separated position.

[0018] When in the separated position, a gap is provided between the lock plate 3 and the small wheels 22. On the other hand, when in the close position, the lock plate 3 and the small wheels 22 come into contact. By moving the two lock plates 3 to the close position and bringing them into contact with the small wheels 22, the omni-wheel 2 is sandwiched between them from both the left and right sides, restricting the rotation of both the small wheels 22 and the large wheels 21 that are in contact with the ground.

[0019] FIG. 5 is an exploded view of the omni-wheel and lock plate. A biasing portion 6 is provided between the omni-wheel 2 and the lock plate 3. The biasing portion 6 is sandwiched between the omni-wheel 2 and the lock plate 3. The biasing portion 6 biases the lock plate 3 in the direction of moving it to the separated position. The biasing portion 6 is made of, for example, a sponge. The sponge is, for example, a urethane sponge. The sponge biasing portion 6 is compressed between the omni-wheel 2 and the lock plate 3, thereby biasing the lock plate 3 in the direction of moving it to the separated position. This keeps the lock plate 3 stably positioned in the separated position under normal conditions. This prevents the lock plate 3 from moving to the close position and coming into contact with the omni-wheel 2, which would hinder the rotation of the omni-wheel 2, or from colliding with the omni-wheel 2 and generating noise.

[0020] Furthermore, the surface of the urging portion 6 made of sponge that comes into contact with the large wheel 21 may be made of a friction-reducing material that reduces friction with the large wheel 21. The friction-reducing material is, for example, a sheet made of polycarbonate. By providing the friction-reducing material, friction between the large wheel 21 and the urging portion 6 can be reduced, reducing noise when the omniwheel 2 rotates and reducing wear on the large wheel 21 and the urging portion 6.

[0021] The biasing unit 6 may be, for example, a spring, as long as it is capable of biasing the lock plate 3 in the direction of moving it to the separated position. If a coil spring is used as the spring, the coil spring may be provided between the omni-wheel 2 and the lock plate 3 with the first rotation shaft 21a passing through the center of the coil spring.

[0022] Figure 6 is a perspective view of the omni-wheel and lock plate. Figure 7 is a view of the left lock plate as seen from the left along the first rotation axis. Note that the right lock plate 3 has the same configuration as the left lock plate 3, so detailed illustration and description of the right lock plate 3 will be omitted.

[0023] A recess 32 is formed on an outer surface 31 of the lock plate 3, which is the surface opposite to the surface facing the omni-wheel 2. The outer surface 31 is the surface facing the lever plate 4, which will be described later. In the first embodiment, an example is shown in which two recesses 32 are formed, but three or more recesses 32 may be formed. A protrusion formed on the lever plate 4, which will be described later, fits into the recess 32.

[0024] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7 . A tapered surface 32a is formed in the recess 32. The tapered surface 32a is formed, for example, by a cutting and raising process. Specifically, a through groove surrounding the area that will become the tapered surface 32a is formed with gaps at its ends, and the area surrounded by the through groove is then pressed in. The inclination direction of the tapered surface 32a is determined by its relationship with the lever plate 4, which will be described later, and will be explained together with the configuration of the lever plate 4. The recess 32 is not limited to being formed by a cutting and raising process. For example, the recess 32 may be formed by recessing the outer surface 31 by a press process.

[0025] A guide protrusion 33 is formed on the outer surface 31 of the lock plate 3. The guide protrusion 33 is formed so as to protrude from the outer surface 31. The guide protrusion 33 is formed, for example, by a cutting and raising process. Specifically, a through groove surrounding the area that will become the guide protrusion 33 is formed with a gap at its end, and the area surrounded by the through groove is raised. Note that the guide protrusion 33 is not limited to being formed by a cutting and raising process. For example, a piece that will become the guide protrusion 33 may be attached to the outer surface 31 by welding or the like.

[0026] <<4. Lever Plate>> Figure 9 is a perspective view of the omni-wheel, lever plate, and lock plate, showing the lever plate in the permitted position. Figure 10 is a perspective view of the omni-wheel, lever plate, and lock plate, showing the lever plate in the restricted position. The wheel unit 1 has two lever plates 4. The two lever plates 4 are arranged in positions sandwiching two lock plates 3 in the left-right direction. Each of the two lever plates 4 is arranged rotatably around a first rotation shaft 21a.

[0027] 11 is a perspective view of the lever plate. The two lever plates 4 are connected by a first connecting portion 7 located on the radially outer side of the omniwheel 2. Because the two lever plates 4 are connected by the first connecting portion 7, the two lever plates 4 rotate in synchronization with each other.

[0028] An operating portion 71 that protrudes forward is formed on the first connecting portion 7. Because the operating portion 71 protrudes forward, the lever plate 4 can be easily rotated by applying force to the operating portion 71 by hooking a hand or foot on the operating portion 71.

[0029] The lever plate 4 has an elongated hole 41 formed therein, which extends in the circumferential direction of a circle centered on the first rotation shaft 21a. The elongated hole 41 penetrates the lever plate 4. A guide protrusion 33 formed on the lock plate 3 is inserted into the elongated hole 41. The end of the elongated hole 41 abuts against the guide protrusion 33, thereby limiting the rotation range of the lever plate 4.

[0030] As shown in Figure 9, the position where the lever plate 4 is rotated in the direction indicated by arrow P is referred to as the allowable position. Also, as shown in Figure 10, the position where the lever plate 4 is rotated in the direction indicated by arrow Q is referred to as the pushed-in position. As shown in Figures 9 and 10, by pushing the operating part 71 downward, the lever plate 4 can be moved from the allowable position to the pushed-in position. Also, by pushing the operating part 71 upward, the lever plate 4 can be moved from the pushed-in position to the allowable position.

[0031] Two protrusions 43 are formed on the inner surface 42 of the lever plate 4 that faces the lock plate 3. That is, two protrusions 43 are formed on one lever plate 4. The two protrusions 43 may be formed, for example, by attaching a hemispherical piece to the inner surface 42 by welding or the like, or by forming a recess in the back surface of the inner surface 42 by press working or the like to cause the inner surface 42 to protrude. Alternatively, three or more protrusions 43 may be formed.

[0032] The two protrusions 43 are formed at positions that allow them to fit into recesses 32 formed in the lock plate 3 when the lever plate 4 is in the allowable position. When the lever plate 4 moves from the allowable position to the pushed-in position, the protrusions 43 move along the tapered surfaces 32a (see also Figures 6, 7, and 8) formed in the recesses 32 and come out of the recesses 32. The protrusions 43 that have come out of the recesses 32 come into contact with the outer surface 31 of the lock plate 3.

[0033] At this time, since the two lever plates 4 are connected by the first connecting portion 7 and an outer casing 5 is provided on the outside of the lever plates 4 as will be explained later, even when the two lever plates 4 are moved to the pushed-in position, they cannot move wider in the left-right direction than when they are in the allowable position.

[0034] Therefore, in the pushed-in position, the convex portion 43 formed on the lever plate 4 abuts against the outer surface 31 of the lock plate 3, pushing the lock plate 3 toward the omniwheel 2. In other words, the lock plate 3, which is biased by the biasing portion 6 in the direction of moving to the separated position, is pushed into the convex portion 43 and moved to the close position against the biasing force. Since two convex portions 43 are formed on the lever plate 4, the lock plate 3 is pushed into the close position at two locations.

[0035] By forming the convex portion 43 with a height sufficient to press the lock plate 3 against the omni-wheel 2, it is possible to press the lock plate 3 against the omni-wheel 2 and restrict the rotation of the large wheel 21 and the small wheel 22. This makes it possible to restrict the movement of an object to which the wheel unit 1 is attached.

[0036] On the other hand, when the lever plate 4 is moved to the allowable position, the convex portion 43 enters the concave portion 32 and no longer abuts against the outer surface 31 of the lock plate 3, so the biasing force of the biasing portion 6 moves the lock plate 3 to the separated position. Therefore, a gap is formed between the lock plate 3 and the omni-wheel 2, allowing the large wheel 21 and small wheel 22 to rotate. This makes it possible to push and move an object to which the wheel unit 1 is attached.

[0037] In order to reliably restrict the movement of an object to which wheel unit 1 is attached, it is necessary to restrict the rotation of the small wheels 22 that are in contact with the ground among the multiple small wheels 22 attached to the large wheel 21 of omni-wheel 2. Therefore, one of the two protrusions formed on lever plate 4 is formed in a position that pushes in the lock plate from the left and right of the small wheels 22 that are in contact with the ground when lever plate 4 is in the pressed-in position.

[0038] Furthermore, the other of the two protrusions 43 formed on the lever plate 4 is formed on the opposite side of the first rotation axis 21a from the protrusion 43 formed in a position that presses in on the grounded small wheel 22. This prevents imbalance in the force with which the lock plate 3 is pressed against the omni-wheel 2, making it possible to more reliably restrict the rotation of the omni-wheel 2.

[0039] 6 to 8, the tapered surface 32a formed in the recess 32 of the lock plate 3 is formed so that the depth of the recess 32 becomes deeper in the direction of movement of the lever plate 4 when it moves from the pushed-in position to the allowed position, i.e., in the direction indicated by arrow P. By forming the tapered surface 32a with such an inclination, when the lever plate 4 moves from the allowed position to the pushed-in position (when it moves in the direction indicated by arrow Q), the protrusion 43 is guided by the tapered surface 32a and smoothly comes out of the recess 32.

[0040] 12 is a perspective view of the outer shell 5. The outer shell 5 has housing plates 51 that sandwich the two lever plates 4 along the left-right direction, and a second connecting portion 54 that connects the two housing plates 51. Each of the two housing plates 51 has a support through-hole 52 formed in a position that overlaps with the first rotation shaft 21a.

[0041] 1 and 2, a support member 8 is inserted into the support through-hole 52. The support members 8 are also inserted inside the large wheel 21 of the omni-wheel 2, inside the lock plate 3, and inside the lever plate 4. This supports the omni-wheel 2, lock plate 3, and lever plate 4 so that they can rotate around the first rotation axis 21a relative to the housing plate 51. The lock plate 3 is fixed so that it cannot rotate around the first rotation axis 21a due to the relationship between a guide protrusion 33 formed on the lock plate 3 and a fixing through-hole 53 formed in the housing plate 51, which will be described later.

[0042] Returning to Fig. 12, each of the two housing plates 51 has a fixing through hole 53 formed therein. As shown in Fig. 2, the guide protrusions 33 formed on the lock plate 3 pass through the fixing through holes 53. There is no large gap between the fixing through holes 53 and the guide protrusions 33, and the contact of the guide protrusions 33 with the fixing through holes 53 restricts movement of the lock plate 3 in a plane perpendicular to the first rotation shaft 21a. In the first embodiment, the lock plate 3 is fixed so that it cannot rotate around the first rotation shaft 21a.

[0043] <<6. Modifications>> FIG. 13 is a perspective view showing a modification of the lever plate. In the lever plate 4 according to the modification, the protrusion 43 is formed by cutting and raising. When the protrusion 43 is formed by cutting and raising, as in the lever plate 4 according to the modification, the shape of the protrusion 43 can be freely determined depending on the shape of the through groove surrounding the area that will become the protrusion 43. This increases the design freedom for the shape of the end 43a. For example, by forming the end 43a into a tapered surface with an inclination that matches the inclination of the tapered surface 32a formed in the recess 32 of the lock plate 3, the lever plate 4 can be more smoothly inserted into and removed from the recess 32 when rotated. In other words, the inclination of the end 43a may be formed so that the height of the protrusion 43 increases in the direction of movement of the lever plate 4 when it moves from the pushed-in position to the permitted position.

[0044] 14 is a view showing another modification of the lock plate 3 as viewed along the first rotation axis 21 a. As shown in FIG. 14, in the lock plate 3 according to this modification, the recess 32 is formed as a groove that extends in an arc shape centered on the first rotation axis 21 a and has a constant width in the radial direction.

[0045] Figure 15 is a cross-sectional view taken along line XV-XV in Figure 14, showing the lever plate in the permitted position. Figure 16 is a cross-sectional view taken along line XV-XV in Figure 14, showing the lever plate in the pressed-in position. Figures 15 and 16 also show the lever plate 4 that faces the lock plate 3. Figure 17 is a cross-sectional view taken along line XVII-XVII in Figure 15.

[0046] As shown in Figures 15 and 16, the recess 32 has a tapered surface 32a formed therein, such that the depth of the recess 32 increases in the direction of movement of the lever plate 4 when it moves from the pushed-in position to the allowable position, i.e., in the direction indicated by arrow P.

[0047] 15 to 17, the protrusion 43 formed on the lever plate 4 has a tapered surface 43b that is inclined along the tapered surface 32a. Also, as shown in Fig. 17, the protrusion 43 is formed with a width that allows it to fit into the recess 32. That is, like the recess 32, the protrusion 43 is also formed in a shape that extends in an arc shape centered on the first rotation axis 21a.

[0048] As shown in Figure 15, when the lever plate 4 is in the permitted position, the convex portion 43 fits into the concave portion 32. At this time, the distance between the lock plate 3 and the lever plate 4 is small, and the lock plate 3 is in the separated position. Therefore, rotation of the large wheel 21 and the small wheel 22 of the omni-wheel 2 is permitted. Also, as shown in Figure 16, when the lever plate 4 is in the pressed-in position, the convex portion 43 moves along the tapered surface 32a, thereby disengaging from the concave portion 32. At this time, the lock plate 3 is pressed by the convex portion 43, increasing the distance between the lock plate 3 and the lever plate 4, and the lock plate 3 is in the close position. Therefore, rotation of the large wheel 21 and the small wheel 22 of the omni-wheel 2 is restricted.

[0049] The recess 32 and protrusion 43 formed in this manner align the centers of the lock plate 3 and lever plate 4 by fitting the recess 32 and protrusion 43 together. This simplifies the task of aligning the centers of the lock plate 3 and lever plate 4 during the assembly process of the wheel unit 1. Furthermore, because the lock plate 3 is pressed in by the protrusion 43, which has a constant width, the amount of pressing of the lock plate 3 is stable, and the rotation of the omniwheel 2 can be restricted more reliably with an even force.

[0050] Fig. 18 is a cross-sectional view showing a modified example of the lock plate and lever plate, showing the lever plate in the allowable position. Fig. 19 is a cross-sectional view showing a modified example of the lock plate and lever plate, showing the lever plate in the pushed-in position. The recess 32 formed in the lock plate 3 according to the modified example functions as a push-in recess. The recess 32 is formed as a groove extending along the movement direction of the lever plate 4. The recess 32 is formed so that its depth increases toward the movement direction (the direction indicated by arrow P) in which the lever plate 4 moves from the pushed-in position to the allowable position. In addition, a tapered surface 32a is formed on the bottom surface of the recess 32, smoothly changing the depth.

[0051] A positioning recess 45 is formed in the lever plate 4 at a position facing the recess 32. The positioning recess 45 does not have a shape that extends along the moving direction of the lever plate 4, unlike the recess 32.

[0052] A spherical steel ball 9 is provided between the lock plate 3 and the lever plate 4. The steel ball 9 is fitted into the recess 32 and the positioning recess 45. By fitting into the positioning recess 45, the steel ball 9 moves together with the lever plate 4. Note that, as in the above example, the recess 32 and the positioning recess 45 are formed in two or more places, and the steel ball 9 is sandwiched between each of the places.

[0053] 18, when the lever plate 4 is in the permitted position, the steel ball 9 is located deep in the recess 32. At this time, the distance between the lock plate 3 and the lever plate 4 is small, and the lock plate 3 is in the separated position. Therefore, the large wheel 21 and small wheel 22 of the omniwheel 2 are permitted to rotate.

[0054] 19, when the lever plate 4 is in the pressed-in position, the steel ball 9 moves together with the lever plate 4 and is in a shallow position in the recess 32. At this time, the distance between the lock plate 3 and the lever plate 4 increases, and the lock plate 3 is in a close position. Therefore, the rotation of the large wheel 21 and small wheel 22 of the omniwheel 2 is restricted.

[0055] In this way, even in a configuration in which steel balls 9 are sandwiched between the lock plate 3 and the lever plate 4, it is possible to restrict the rotation of the large wheel 21 and small wheel 22 of the omniwheel 2 by moving the lever plate 4 from the permitted position to the pressed position. Note that the spheres sandwiched between the lock plate 3 and the lever plate 4 need only be strong enough not to deform when sandwiched, and are not limited to steel balls.

[0056] <<7. Summary of Effects>> The wheel unit 1 described above comprises an omni-wheel 2 having a large wheel 21 rotatable around a first rotation axis 21 a and a plurality of small wheels 22 arranged in a row on the outer periphery of the large wheel 21, each of the plurality of small wheels 22 rotatable around a second rotation axis 22 a that is parallel to the tangent direction of a circle about the first rotation axis 21 a; two lock plates 3 that are arranged on either side of the omni-wheel 2 along a first direction parallel to the first rotation axis 21 a and that are movable between a close position that is close to the large wheel 21 and a separated position that is distant from the large wheel 21; and two lever plates 4 that are arranged on either side of the two lock plates 3 along the first direction and that are movable between a pushed position that pushes the lock plate 3 into the close position and an allowed position that allows the lock plate 3 to move to the separated position. Furthermore, the two lock plates 3 abut against the small wheels 22 in the close positions, and each of the lever plates 4 presses the lock plate 3 into the close positions at least at two points.

[0057] This allows the two lock plates 3 to press in from both sides and restrict the rotation of the omni-wheel 2 without deforming the omni-wheel 2 to one side. This improves the durability of the omni-wheel 2. Also, with a single operation of moving the lever plate 4 from the allowable position to the pressed-in position, the lock plate 3 can be moved to the close position and the rotation of the omni-wheel 2 can be restricted. This simplifies the operation of restricting the rotation of the omni-wheel 2.

[0058] In order to restrict the movement of an object to which an omni-wheel 2 is attached, a configuration may be adopted in which the object is supported by multiple support parts protruding from the object, lifting the omni-wheel 2 above the ground surface. In this case, the cumbersome task of extending the support parts protruding from the object to lift the omni-wheel 2 is required. Furthermore, because it is difficult to simultaneously extend multiple support parts, when the object is supported from the ground surface by the support parts alone, an uneven force is applied to the object, which may cause deformation or failure of the object. In contrast, the wheel unit 1 disclosed herein makes it possible to restrict the movement of an object by simply moving the lever plate 4, without lifting the omni-wheel 2.

[0059] Furthermore, in the wheel unit 1, one of the at least two positions where the lever plate 4 pushes the lock plate 3 is a position where the small wheel 22 in contact with the ground is pushed in. This makes it possible to more reliably restrict the rotation of the small wheel 22 in contact with the ground.

[0060] Furthermore, in the wheel unit 1, the other of the at least two locations where the lever plate 4 presses the lock plate 3 is located on the opposite side of the first rotation shaft 21a from the grounded small wheel 22. This prevents imbalance in the force with which the lock plate 3 presses against the omni-wheel 2, making it possible to more reliably restrict the rotation of the omni-wheel 2.

[0061] In addition, in the wheel unit 1, at least two recesses 32 are formed on one of the surfaces of the lock plate 3 facing the lever plate 4 and the surface of the lever plate 4 facing the lock plate 3. At least two protrusions 43 are formed on the other of the surface of the lock plate 3 facing the lever plate 4 and the surface of the lever plate 4 facing the lock plate 3. In addition, in the allowable position, each of the protrusions 43 is fitted into the recess 32, and in the pressed-in position, each of the protrusions 43 is disengaged from the recess 32 and presses the lock plate 3. As a result, by simply forming a simple structure of recesses and protrusions on the lock plate 3 and the lever plate 4, it is possible to restrict the rotation of the omniwheel 2 by moving the lever plate 4 to the pressed-in position. Note that in the first embodiment, an example was described in which the recess 32 was formed on the lock plate 3 and the protrusion 43 was formed on the lever plate 4. However, a protrusion may be formed on the lock plate 3 and a recess may be formed on the lever plate 4.

[0062] Furthermore, in the wheel unit 1, a tapered surface 32a is formed in the recess 32, and the tapered surface 32a formed in the recess 32 is formed so that the depth of the recess 32 increases in the direction of movement when the lever plate 4 moves from the pushed-in position to the allowable position. As a result, when the lever plate 4 moves from the allowable position to the pushed-in position (when moving in the direction indicated by arrow Q), the protrusion 43 is guided by the tapered surface 32a and smoothly disengages from the recess 32. This improves the operability of the lever plate 4.

[0063] In addition, in the wheel unit 1, a tapered surface is formed on the convex portion 43, and the tapered surface formed on the convex portion 43 is formed so that the height of the convex portion 43 increases as it moves in the direction of movement when the lever plate 4 moves from the pushed-in position to the allowable position.

[0064] The wheel unit 1 also includes at least two spherical portions (steel balls 9) sandwiched between the lock plate 3 and the lever plate 4. At least two positioning recesses 45 are formed on one of the surfaces of the lock plate 3 facing the lever plate 4 and the surface of the lever plate 4 facing the lock plate 3. At least two push-in recesses (recesses 32) are formed on the other of the surface of the lock plate 3 facing the lever plate 4 and the surface of the lever plate 4 facing the lock plate 3. The positioning recesses 45 position the spherical portions by fitting the spherical portions into them, and the push-in recesses are formed so that they fit the spherical portions and extend along the movement direction of the lever plate 4 moving from the pushed position to the allowable position, and become deeper in the movement direction of the lever plate 4 moving from the pushed position to the allowable position. As a result, when the lever plate 4 is moved to the allowable position, the spherical portions are positioned deep in the push-in recesses, reducing the distance between the lock plate 3 and the lever plate 4, and the lock plate 3 is positioned in the separated position. On the other hand, when the lever plate 4 is moved to the pressed-in position, the spherical portion is located in a shallow portion of the pressed-in recess, increasing the distance between the lock plate 3 and the lever plate 4, and the lock plate 3 is located in a close position. In this way, even with a configuration in which a spherical portion is sandwiched between the lock plate 3 and the lever plate 4, it is possible to restrict the rotation of the omniwheel 2 simply by moving the lever plate 4. Note that, although the first embodiment has been described using an example in which a pressed-in recess is formed in the lock plate 3 and a positioning recess 45 is formed in the lever plate 4, it is also possible for a positioning recess to be formed in the lock plate 3 and a pressed-in recess to be formed in the lever plate 4.

[0065] Furthermore, in the wheel unit 1, the two lever plates 4 are rotatable about the first rotation shaft 21a, and move between a pushed-in position and an allowed position by rotation. This makes it possible to restrict the rotation of the omniwheel 2 by the simple operation of rotating the lever plates 4. While the first embodiment has been described with an example in which the lever plates 4 are rotatable, the lever plates 4 may be configured to move between the allowed position and the pushed-in position by moving, for example, in the front-to-back or up-to-down direction.

[0066] The wheel unit 1 also includes a first connecting portion 7 located radially outward of the omniwheel 2 and connecting the two lever plates 4. This synchronizes the movements of the two lever plates 4, allowing the two lever plates 4 to be reliably moved with a single operation.

[0067] Furthermore, in the wheel unit 1, each of the two lock plates 3 is formed with a guide protrusion 33 that protrudes in a direction away from the omni-wheel 2. The two lever plates 4 are formed with elongated holes 41, into which the guide protrusions 33 are inserted and which extend circumferentially around a circle centered on the first rotation axis 21a. The end of the elongated hole 41 abuts against the guide protrusion 33, thereby limiting the rotation range of the lever plate 4. This makes it possible to limit the rotation range of the lever plate 4 with a simple configuration that involves forming the guide protrusion 33 and the elongated hole 41. Furthermore, since a separate part for limiting the rotation range of the lever plate 4 is not required, the number of parts can be reduced.

[0068] The wheel unit 1 also includes an outer shell 5 having two housing plates 51 sandwiching the two lever plates 4 therebetween along the first direction and a second connecting portion 54 connecting the two housing plates 51. Each of the two housing plates 51 is formed with a fixing through-hole 53 through which the guide protrusion 33 passes, and the guide protrusion 33 abuts against the fixing through-hole 53, thereby restricting movement of the lock plate 3 in a plane perpendicular to the first rotation axis 21a. This allows the movement of the lock plate to be restricted with a simple configuration of forming the guide protrusion 33 and the fixing through-hole 53. Furthermore, a separate part for restricting the movement of the lock plate 3 is not required, thereby reducing the number of parts.

[0069] The wheel unit 1 also includes a biasing portion 6 that biases the lock plate 3 in a direction to move it to the separated position. This keeps the lock plate 3 stably positioned in the separated position under normal conditions. This prevents the lock plate 3 from moving to the close position and coming into contact with the omni-wheel 2, thereby hindering the rotation of the omni-wheel 2 or causing noise due to collision with the omni-wheel 2.

[0070] In the wheel unit 1, the biasing portion 6 is a sponge sandwiched between the large wheel 21 and the lock plate 3. By using a sponge, the biasing portion 6 can be configured with a lightweight and simple structure.

[0071] Furthermore, in the wheel unit 1, the contact surface of the urging part 6 with the large wheel 21 is formed of a friction reducing material that reduces friction between the large wheel 21. This reduces friction between the large wheel 21 and the urging part 6, reducing noise when the omni-wheel 2 rotates and reducing wear on the large wheel 21 and the urging part 6.

[0072] In the wheel unit 1, the biasing portion 6 is a spring sandwiched between the large wheel 21 and the lock plate 3. This makes it possible to configure the biasing portion 6 using a common part called a spring.

[0073] The lever plate 4 may be configured to be electrically operated.

[0074] <<8. Supplementary Notes>> The present technology can also be configured as follows. (1) A wheel unit comprising: an omni-wheel having a large wheel rotatable around a first rotation axis and a plurality of small wheels arranged side by side on the outer periphery of the large wheel, each of the small wheels being rotatable around a second rotation axis parallel to the tangent direction of a circle centered on the first rotation axis; two lock plates arranged along a first direction parallel to the first rotation axis, with the omni-wheel sandwiched between them, and each of the lock plates being movable between a close position close to the large wheel and a separated position away from the large wheel; and two lever plates arranged along the first direction, with the two lock plates sandwiched between them, and movable between a pushed position where the lock plate is pushed into the close position and an allowable position where the lock plate is allowed to move to the separated position; the two lock plates abut against the small wheels at the close position, and each of the lever plates pushes the lock plate into the close position at at least two points. (2) The wheel unit according to (1), wherein one of the at least two locations where the lever plate presses the lock plate is a location where the small wheel that is in contact with the ground is pressed in. (3) The wheel unit according to (2), wherein the other of the at least two locations where the lever plate presses the lock plate is a location on the opposite side of the small wheel that is in contact with the ground across the first rotation axis. (4) The wheel unit according to any one of (1) to (3), wherein at least two recesses are formed on one of the surface of the lock plate facing the lever plate and the surface of the lever plate facing the lock plate, and at least two protrusions are formed on the other of the surface of the lock plate facing the lever plate and the surface of the lever plate facing the lock plate, and each of the protrusions is fitted into the recess at the allowable position and each of the protrusions is disengaged from the recess at the pressed-in position to press the lock plate.(5) The wheel unit according to (4), wherein the recess has a tapered surface formed thereon such that the depth of the recess increases toward the direction of movement of the lever plate when it moves from the pushed-in position to the permitted position. (6) The wheel unit according to (5), wherein the protrusion has a tapered surface formed thereon such that the height of the protrusion increases toward the direction of movement of the lever plate when it moves from the pushed-in position to the permitted position. (7) The wheel unit according to (6), wherein the recess and the protrusion have a constant width along the radial direction of a circle centered on the first rotation axis. (8) The wheel unit according to any one of (1) to (3), further comprising at least two spherical portions sandwiched between the lock plate and the lever plate, wherein at least two positioning recesses are formed on one of the surface of the lock plate facing the lever plate and the surface of the lever plate facing the lock plate, and at least two push-in recesses are formed on the other of the surface of the lock plate facing the lever plate and the surface of the lever plate facing the lock plate, wherein the spherical portions are fitted into the positioning recesses to position the spherical portions, and the push-in recesses are fitted into the spherical portions and extend along the movement direction of the lever plate moving from the pushed-in position to the allowed position, and are formed so that their depth increases toward the movement direction of the lever plate moving from the pushed-in position to the allowed position. (9) The wheel unit according to any one of (1) to (8), wherein the two lever plates are rotatable about the first rotation axis and move between the pushed-in position and the allowed position by rotation. (10) The wheel unit according to (9), further including a first connecting portion located radially outward of the omni-wheel and connecting the two lever plates.(11) The wheel unit according to (10), wherein each of the two lock plates is formed with a guide protrusion that protrudes in a direction away from the omni-wheel, and the two lever plates are formed with elongated holes through which the guide protrusions are inserted and that extend in a circumferential direction of a circle centered on the first rotation axis, and ends of the elongated holes abut against the guide protrusions to limit the rotation range of the lever plates. (12) The wheel unit according to (11), further comprising an outer shell having two housing plates that sandwich the two lever plates therebetween along the first direction and a second connecting portion that connects the two housing plates, and wherein each of the two housing plates is formed with a fixing through-hole through which the guide protrusion passes, and movement of the lock plate in a plane perpendicular to the first rotation axis is restricted by the guide protrusions abutting against the fixing through-hole. (13) The wheel unit according to any one of (1) to (12), further including a biasing portion that biases the lock plate in a direction to move it to the separated position. (14) The wheel unit according to (13), wherein the biasing portion is a sponge sandwiched between the large wheel and the lock plate. (15) The wheel unit according to (13), wherein the biasing portion has an abutment surface with the large wheel formed of a friction reducing member that reduces friction between the large wheel and the biasing portion. (16) The wheel unit according to (13), wherein the biasing portion is a spring sandwiched between the large wheel and the lock plate.

[0075] DESCRIPTION OF SYMBOLS 1 Wheel unit 2 Omni-wheel 21 Large wheel 21a First rotating shaft 22 Small wheel 22a Second rotating shaft 3 Lock plate 31 Outer surface 32 Recess 32a Tapered surface 33 Guide convex portion 4 Lever plate 41 Elongated hole 42 Inner surface 43 Convex portion 45 Positioning concave portion 5 Outer body 51 Housing plate 52 Support through-hole 53 Fixing through-hole 54 Second connecting portion 6 Urging portion 7 First connecting portion 71 Operating portion 8 Support member 9 Steel ball

Claims

1. A wheel unit comprising: an omni-wheel having a large wheel that can rotate around a first rotation axis and a number of small wheels arranged in a row on the outer periphery of the large wheel, each of the small wheels being rotatable around a second rotation axis that is parallel to the tangent direction of a circle that is centered on the first rotation axis; two locking plates that are arranged in a first direction parallel to the first rotation axis, with the omni-wheel sandwiched between them, and each of the locking plates is movable between a close position that is close to the large wheel and a separated position that is distant from the large wheel; and two lever plates that are arranged in a first direction, with the two locking plates sandwiched between them, and are movable between a pushed-in position that pushes the locking plate into the close position and a permitted position that allows the locking plate to move to the separated position, wherein the two locking plates abut against the small wheels in the close position, and each of the lever plates pushes the locking plate into the close position at at least two points.

2. A wheel unit as described in claim 1, wherein one of the at least two positions where the lever plate pushes the lock plate is a position where the small wheel that is in contact with the ground is pushed in.

3. A wheel unit as described in claim 2, wherein the other of the at least two locations where the lever plate pushes the lock plate is located on the opposite side of the small wheel that is in contact with the ground, across the first rotation axis.

4. A wheel unit as described in claim 1, wherein at least two recesses are formed on one of the surfaces of the locking plate facing the lever plate and the surface of the lever plate facing the locking plate, and at least two protrusions are formed on the other of the surface of the locking plate facing the lever plate and the surface of the lever plate facing the locking plate, and in the allowable position, each of the protrusions is fitted into the recess, and in the pushed-in position, each of the protrusions is disengaged from the recess and pushes in the locking plate.

5. A wheel unit as described in claim 4, wherein a tapered surface is formed in the recess, and the tapered surface formed in the recess is formed so that the depth of the recess becomes deeper in the direction of movement when the lever plate moves from the pushed-in position to the allowable position.

6. A wheel unit as described in claim 5, wherein the convex portion has a tapered surface formed thereon, and the tapered surface formed on the convex portion is formed so that the height of the convex portion increases in the direction of movement when the lever plate moves from the pushed-in position to the allowable position.

7. A wheel unit according to claim 6, wherein the recessed portion and the protruding portion are formed to have a constant width along the radial direction of a circle centered on the first rotation axis.

8. A wheel unit as described in claim 1, further comprising at least two spherical portions sandwiched between the lock plate and the lever plate and having a spherical shape, wherein at least two positioning recesses are formed on one of the surface of the lock plate facing the lever plate and the surface of the lever plate facing the lock plate, and at least two push-in recesses are formed on the other of the surface of the lock plate facing the lever plate and the surface of the lever plate facing the lock plate, wherein the spherical portions are fitted into the positioning recesses to position the spherical portions, and wherein the push-in recesses are formed so that the spherical portions fit into them and extend along the direction of movement in which the lever plate moves from the pushed-in position to the allowed position, and become deeper the further they move in the direction of movement in which the lever plate moves from the pushed-in position to the allowed position.

9. A wheel unit as described in claim 1, wherein the two lever plates are rotatable about the first rotation axis and move between the pushed-in position and the allowable position by rotation.

10. The wheel unit according to claim 9, further comprising a first connecting portion located radially outward of the omni-wheel and connecting the two lever plates.

11. A wheel unit as described in claim 10, wherein each of the two lock plates is formed with a guide protrusion that protrudes in a direction away from the omni-wheel, and the two lever plates are formed with long holes through which the guide protrusions are inserted and which extend circumferentially around a circle centered on the first rotation axis, and the ends of the long holes abut against the guide protrusions, thereby limiting the rotation range of the lever plates.

12. A wheel unit as described in claim 11, further comprising an outer shell having two housing plates sandwiching the two lever plates along the first direction and a second connecting portion connecting the two housing plates, wherein each of the two housing plates is formed with a fixing through-hole through which the guide protrusion passes, and the guide protrusion abuts against the fixing through-hole, thereby restricting movement of the lock plate in a plane perpendicular to the first rotation axis.

13. The wheel unit according to claim 1, further comprising a biasing portion that biases the lock plate in a direction in which the lock plate moves to the separated position.

14. A wheel unit according to claim 13, wherein the biasing portion is a sponge sandwiched between the large wheel and the lock plate.

15. A wheel unit according to claim 14, wherein the surface of the biasing portion that comes into contact with the large wheel is formed of a friction reducing material that reduces friction between the biasing portion and the large wheel.

16. A wheel unit according to claim 13, wherein the biasing portion is a spring sandwiched between the large wheel and the lock plate.

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