Universal caster, and suitcase, wheeled bag, wheeled chair, and cart including the same

Abstract

To provide a universal caster capable of suppressing resistance generated when a wheel and a fork turn, and to provide a suitcase, a wheeled bag, a wheeled chair, and a carriage including the universal caster.SOLUTION: The universal caster 10 has a wheel 11 rolling on a traveling surface and a fork 13 supporting an axle 12 to which the wheel 11 is attached, and is attached to an external unit U. The fork 13 is turnable with respect to the turning body 14, the turning axis P which is the turning center of the turning body 14 with respect to the external unit U and the turning axis Q which is the turning center of the fork 13 with respect to the turning body 14 are non-parallel to each other, and become non-perpendicular to each other when the turning axis P is brought into contact with the turning axis Q by the parallel movement of the turning axis P.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a swivel caster, and to a suitcase, a wheeled bag, a wheeled chair, and a cart equipped with the same. [Background technology]

[0002] Swivel casters such as those described in Patent Documents 1 and 2 are attached to the main body (hereinafter simply referred to as the "main body") of a suitcase, carry bag, wheelchair, transport cart, etc. As shown in Fig. 11(A), the swivel caster has a wheel 100, an axle 101, and a fork 102 that can rotate around a pivot 103, and the axle 101 is provided on an extension of the pivot 103 or at a position that is some distance from the pivot 103. Note that the pivot 103 referred to here is not an actual member such as a shaft, but corresponds to the axis of rotation when expressing rotational motion in physics.

[0003] Because the swivel caster has the above-mentioned structure, the axle 101 is located behind the swivel axis 103 in the direction of travel when viewed in a plane, and the axle 101 runs perpendicular to the direction of travel (the state of the swivel caster at this time is also called the "stable running state"). When a force acts on a swivel caster on a running surface 104 in a direction that is not perpendicular to the axle 101 (for example, in a direction along the axle 101), as shown in Figure 11 (B), the wheel 100, axle 101, and fork 102 of the swivel caster rotate around the pivot 103, and the caster attempts to reach a stable running state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-179003 [Patent Document 2] Japanese Patent Application Publication No. 2020-045098 Summary of the Invention [Problem to be solved by the invention]

[0005] However, at this time, a force acts on the swivel caster from the running surface 104 or the like in a direction that is not perpendicular to the axle 101, which causes a problem of large resistance when the wheel 100, fork 102, etc. turn around the turning axis 103. In particular, the smaller the angle between the direction of the force acting on the swivel caster and the axle 101, the greater the resistance during turning.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a swivel caster that can suppress the resistance that occurs when the wheel and fork turn, as well as a suitcase, wheeled bag, wheeled chair, and cart that are equipped with the same. [Means for solving the problem]

[0007] The first invention of the present invention, which meets the above-mentioned objective, provides a swivel caster that is attached to an external unit and has a wheel that rolls on a running surface and a fork that supports an axle to which the wheel is attached, and is provided with a swivel body that is rotatable relative to the external unit, and the fork is rotatable relative to the swivel body, with a swivel axis P that is the center of rotation of the swivel body relative to the external unit and a swivel axis Q that is the center of rotation of the fork relative to the swivel body being non-parallel to each other, and when the swivel axis P is brought into contact with the swivel axis Q by parallel movement of the swivel axis P, they become non-perpendicular to each other.

[0008] A suitcase according to a second invention that meets the above-mentioned object is equipped with the swivel caster according to the first invention. A wheeled bag according to a third invention that meets the above-mentioned object is equipped with the swivel caster according to the first invention. A wheeled chair according to a fourth invention that meets the above-mentioned object is equipped with the swivel caster according to the first invention. A cart according to a fifth invention that meets the above-mentioned object is equipped with the swivel caster according to the first invention. [Effects of the Invention]

[0009] The swivel caster of the first invention has a swivel body that can rotate freely relative to the external unit, and the fork can rotate freely relative to the swivel body. The swivel axis P, which is the center of rotation of the swivel body relative to the external unit, and the swivel axis Q, which is the center of rotation of the fork relative to the swivel body, are non-parallel to each other, and when the swivel axis P is brought into contact with the swivel axis Q by parallel movement of the swivel axis P, they become non-perpendicular to each other, so that the resistance generated when the wheel and fork rotate can be suppressed.

[0010] The suitcase according to the second invention, the wheeled bag according to the third invention, the wheeled chair according to the fourth invention, and the cart according to the fifth invention are equipped with the swivel casters according to the first invention, thereby reducing the resistance that occurs when the wheels and forks turn. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram of a swivel caster according to a first embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 10 is a side view of a swivel caster according to a second embodiment of the present invention. [Figure 7] FIG. [Figure 8] FIG. 10 is an explanatory diagram of the swivel caster with the thrust bearing omitted. [Figure 9] FIG. 10 is an explanatory diagram showing experimental results. [Figure 10] FIG. 10 is an explanatory diagram showing experimental results. [Figure 11] 1A and 1B are explanatory diagrams of a conventional swivel caster and an explanatory diagram showing a state in which a force is applied to the swivel caster, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, embodiments of the present invention will be described with reference to the accompanying drawings to facilitate understanding of the present invention. As shown in Figures 1 to 5, a swivel caster 10 according to a first embodiment of the present invention has a wheel 11 that rolls on a running surface R and a fork 13 that supports an axle 12 to which the wheel 11 is attached, and is a caster that is attached to an external unit U, and is provided with a swivel body 14 that is swivelable relative to the external unit U. Details will be explained below.

[0013] As shown in Figures 1 to 5, the swivel casters 10 each have a shaft 15 and a mounting seat 16 that are fixed to an external unit U. The mounting seat 16 is annular, and the shaft 15 passes through the inner periphery of the mounting seat 16. The external unit U is, for example, a suitcase body (the part of the suitcase excluding the swivel casters 10; hereinafter, "body" refers to the part of the entire product excluding the swivel casters 10 of the product), the body of a wheeled bag, the body of a wheeled chair, or the body of a cart.

[0014] Therefore, the suitcase is constituted by the swivel caster 10 and the suitcase body, the wheeled bag is constituted by the swivel caster 10 and the body of the wheeled bag, the wheeled chair is constituted by the swivel caster 10 and the body of the wheeled chair, and the cart is constituted by the swivel caster 10 and the cart body. 1, 3, 4, and 5 show only the caster support portion S of the entire external unit U to which the swivel caster 10 is attached.

[0015] In this embodiment, the portion of the shaft 15 protruding from the mounting seat 16 penetrates the caster support portion S and is fixed to the caster support portion S by a fixing device (not shown). The caster support portion S has a triangular outer edge in a plan view, and is designed so that one swivel caster 10 can be attached to each of the three corners. It goes without saying that the method of fixing the swivel caster 10 to the external unit U is not limited to this; for example, the swivel caster 10 can be attached to an external unit U that does not have a member equivalent to the caster support portion S.

[0016] The three swivel casters 10 attached to the caster support parts S (i.e., all of the multiple swivel casters 10 attached to the external unit U) are in contact with the horizontal running surface R, with the mounting seat 16 of each swivel caster 10 positioned below the caster support part S and the shaft member 15 arranged vertically. This arrangement of the swivel casters 10 is the standard arrangement, and hereinafter, unless otherwise specified, the swivel casters 10 will be described as being in the standard arrangement state. In this document, terms such as vertical, parallel, perpendicular, and horizontal that refer to positions or orientations mean substantially (for example, vertical means substantially vertical).

[0017] The upper part of the shaft 15 passes through the caster support part S, and a bearing part 17 is attached to the part that protrudes downward from the mounting seat 16. The rotating body 14 is attached to the shaft 15 via the bearing part 17 and is capable of rotating around the shaft 15. Therefore, the rotating body 14 is freely rotatable with respect to the shaft 15, the mounting seat 16, and the caster support part S (external unit U).

[0018] The rotation axis that is the center of rotation of the rotating body 14 relative to the external unit U is defined as the rotation axis P, and as shown in Figs. 1 and 4, the rotation axis P is along the axis of the shaft member 15. In this embodiment, the wheels 11 are arranged at positions that do not contact the extension line of the rotation axis P. Note that the rotation axis P and a rotation axis Q described later are not actual members such as shaft members, but refer to the central axis of rotation (axis of rotation) when expressing a rotational movement (rotational movement).

[0019] When the swivel caster 10 travels linearly on the running surface R, as shown in Fig. 1, the swivel unit 14 rotates about the swivel axis P so that the wheel 11 is located directly behind the extension of the swivel axis P (shaft member 15) (or the swivel axis P) in a plan view. The front side of the swivel caster 10 in the direction of travel when the wheel 11 is located directly behind the swivel axis P is defined as the front side of the swivel caster 10. In this embodiment, the swivel unit 14 is long in the front-to-rear direction, and as shown in Figs. 1 and 2, a weight 18 can be attached to the front side of the swivel unit 14 for balance adjustment. The weight 18 can be omitted.

[0020] As shown in Figures 1 to 4, the rear side of the rotating unit 14 becomes thicker towards the end, and a shaft 19 that passes through the rotating unit 14 is fixed to the rear end of the rotating unit 14. The shaft 19 is arranged at an angle to the shaft 15 (the shaft 19 is arranged in a direction that is neither horizontal nor vertical), and in a plan view (viewed along the shaft 15), the lower end of the shaft 19 is located on a line segment that connects the upper ends of the shaft 15 and the shaft 19.

[0021] Forks 13 are rotatably attached to the portions of shaft members 19 that protrude downward from rotating body 14. Axles 12 are fixed to forks 13 in a horizontally disposed state, and wheels 11 are rotatably attached to axles 12. In this embodiment, when viewed along the rotating axis P, wheels 11 and forks 13 are arranged in positions that do not overlap with the rotating axis P. Therefore, the fork 13, together with the wheel 11 and the axle 12, can freely rotate relative to the rotating body 14. The rotation axis that is the center of rotation of the fork 13, wheel 11, and axle 12 relative to the rotating body 14 is defined as a rotation axis Q, and as shown in Figures 1 and 4, the rotation axis Q is along the axis of the shaft member 19.

[0022] Therefore, in this embodiment, the pivot axis P and the pivot axis Q are non-parallel to each other (not parallel), and even if the pivot axis P is brought into contact with the pivot axis Q by parallel movement of the pivot axis P (even if the pivot axis P is moved without changing its orientation and brought into contact with the pivot axis Q), the pivot axis P and the pivot axis Q will be non-perpendicular to each other (will not be perpendicular).

[0023] In the swivel caster 10, the swivel body 14 can rotate around the swivel axis P, and the forks 13 and wheels 11 can rotate around the swivel axis Q, and furthermore, the direction along which the swivel axis P runs and the direction along which the swivel axis Q run are in the relationship described above. Therefore, when a force in a direction non-perpendicular to the axle 12 (hereinafter, this direction will be referred to as the "T direction") acts on the swivel caster 10, the swivel body 14 of the swivel caster 10 rotates around the swivel axis P, and the forks 13 rotate together with the wheels 11 around the swivel axis Q, ultimately attempting to reach a state in which the axle 12 is arranged perpendicular to the T direction and the wheels 11 are able to travel.

[0024] According to this embodiment, the following technical effects are achieved in the process in which the swivel caster 10 reaches its final state.

[0025] 1) When the wheel 11 and the fork 13 turn, the resistance generated in the swivel caster 10 can be suppressed (resistance force can be reduced). 2) The distance traveled by the wheel 11 from when the wheel 11 and fork 13 start to turn until the axle 12 becomes perpendicular to the T direction and the swivel caster 10 starts to run stably can be shortened (the wheel 11 can be prevented from making a detour).

[0026] In this embodiment, the outer peripheral surface of the wheel 11 that contacts the running surface R (this running surface R is the running surface on which the wheel 11 rolls) is curved so that the distance to the axle 12 becomes shorter from the center in the width direction W of the wheel 11 toward the ends in the width direction W (one side end and the other side end, respectively) as shown in Figures 2, 4, and 5. This is preferable from the viewpoint of achieving the technical effects 1) and 2) above. Moreover, in this embodiment, the radius of curvature of the outer peripheral surface of wheel 11 is half the outer diameter of wheel 11. In other words, the outer peripheral surface of wheel 11 follows the outer peripheral surface of a perfect sphere whose center is the center of wheel 11 and whose diameter is the same length as the outer diameter of wheel 11. This is even more preferable from the viewpoint of achieving the technical effects 1) and 2) above.

[0027] The above-described technical effects can also be achieved in suitcases, wheeled bags, wheeled chairs, carts, and the like that are equipped with the swivel casters 10. In this embodiment, the swivel axis P and the swivel axis Q are arranged on the same imaginary plane, which is preferable from the viewpoint of smooth running of the swivel caster 10.

[0028] Furthermore, when the swivel caster 10 attached to the external unit U travels on the running surface R, the weight of the external unit U acts on the swivel caster 10. As shown in Figure 4, the swivel caster 10 is attached to the swivel unit 14 at a position where the shaft member 19 is spaced apart from the shaft member 15, and when the swivel caster 10 travels on the running surface R, the shaft member 19 is inclined relative to the running surface R, so that the swivel unit 14 and the shaft member 19 must be highly strong, and for example, the swivel unit 14 must be made larger or the shaft member 19 must be made thicker.

[0029] In this regard, by using a thrust bearing, the strength required for the rotating body 14 and the shaft member 19 can be reduced. A swivel caster 30 according to a second embodiment of the present invention, which is equipped with a thrust bearing 31, will be described below with reference to Figures 6, 7, and 8. Note that in the swivel caster 30, the same structures as those in the swivel caster 10 are given the same reference numerals and detailed descriptions thereof will be omitted.

[0030] As shown in Figures 6 and 7, the swivel caster 30 has a thrust bearing 31 and a bearing portion 17 attached in this order facing downward to a portion of the shaft member 15 that projects downward from a mounting seat (not shown) (similar to mounting seat 16 of the swivel caster 10) along the swivel axis P. A swivel body 32 is attached to the bearing portion 17, and the swivel body 32 is swivelable around the shaft member 15. In this embodiment, the thrust bearing 31 does not contact the swivel body 32. However, the thrust bearing 31 may also contact the swivel body 32.

[0031] A shaft 19 that passes through the rotating body 32 is fixed to the rotating body 32, and a fork 33 is rotatably attached to the portion of the shaft 19 that protrudes downward from the rotating body 32. As shown in Figures 6 and 7, an opening 34 is formed in the rotating body 32 on one side (the side where the fork 33 is arranged) based on the shaft 19, and a roller 35 is rotatably attached to the other side.

[0032] 6 and 7, most of the fork 33 is located below the swivel body 32, and a portion thereof passes through the opening 34 and contacts the underside of the thrust bearing 31. Therefore, when the swivel caster 30 travels on the running surface R, the thrust bearing 31 receives at least a portion of the force that the wheel 11 receives from the running surface R directly from the fork 33. It is also possible to adjust the shape of the rotating body 32 and the positioning of the fork 33 relative to the rotating body 32 so that the fork 33 comes into contact with the thrust bearing 31 without forming an opening 34 in the rotating body 32.

[0033] As the fork 33 pivots about the shaft 19 (pivot axis Q), the portion of the fork 33 that was in contact with the thrust bearing 31 comes out of contact with the thrust bearing 31, and the portion adjacent to that portion comes into contact with the thrust bearing 31. In this embodiment, the fork 33 is formed so that the fork 33 and the thrust bearing 31 contact in a line segment (rather than at a point).

[0034] The rollers 35 protrude upward and downward from the rotating body 32, and their upper sides are in contact with the underside of the thrust bearing 31. Therefore, in this embodiment, the force that the wheel 11 receives from the running surface R is transmitted to the fork 33 via the axle 12, a portion of which is transmitted from the rollers 35 etc. to the thrust bearing 31 via the shaft member 19 and the rotating body 32, and the remainder is transmitted directly from the fork 33 to the thrust bearing 31.

[0035] The rotation axis of roller 35 is arranged so that the direction of rotation of roller 35 at the contact point between roller 35 and thrust bearing 31 is the same as the direction of rotation of the portion of thrust bearing 31 that is in contact with roller 35 (i.e., so that the frictional force generated between roller 35 and thrust bearing 31 is reduced). In this embodiment, roller 35 assists in the rotation of rotating body 32 about shaft member 15. From the viewpoint of reducing the strength required of rotating body 32 and shaft member 19 by bringing fork 33 into contact with thrust bearing 31, roller 35 may be omitted. [Example]

[0036] Next, an experiment conducted to confirm the effects of the present invention will be described. A software program was used to simulate the movement of a swivel caster according to an embodiment having swivel axes P and Q shown in Figures 1 to 5 (hereinafter simply referred to as the "embodiment"), and a swivel caster according to a comparative example having one swivel axis shown in Figure 11 (hereinafter simply referred to as the "comparison example") when a force was applied to each of them. The wheels of the example were spherical, and the wheels of the comparative example were obtained by removing both sides of the wheel in the width direction from the spherical example. A force was applied in the direction along the axle to both the example and comparative example while they were stationary, and the force was continued to be applied to simulate the movement of the swivel caster. The magnitude of the force applied to the example and comparative example was the same.

[0037] The simulation results of the wheel movement of the example and the comparative example are shown in Figures 9 and 10. In each of Figures 9 and 10, the left side shows the simulation results for the comparative example, and the right side shows the simulation results for the example. The two straight lines drawn in Figures 9 and 10 are along the direction of the force that was continuously applied to the example and the comparative example. Figures 9 and 10 show the wheel positions for each sampling period from the start of application of force to the example and the comparative example until the same amount of time has elapsed.

[0038] The results shown in FIG. 9 show that the example was able to suppress detours compared to the comparative example. From the results shown in Figure 10, the Example had already started moving and turning when the Comparative Example had not yet started turning or moving. This is thought to be because the turning resistance of the Comparative Example was greater than that of the Example, and it took a long time for the Comparative Example to start moving.

[0039] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all changes in conditions that do not depart from the gist of the present invention are within the scope of application of the present invention. For example, the outer circumferential surface of the wheel does not have to be curved. If the outer circumferential surface of the wheel is curved, the radius of curvature of the outer circumferential surface does not have to be half the outer diameter of the wheel. Also, there may be multiple wheels. Furthermore, the pivot axis P and the pivot axis Q do not have to be disposed on the same imaginary plane, and the shaft may be rotatably supported by a fork. [Explanation of symbols]

[0040] 10: Swivel caster, 11: Wheel, 12: Axle, 13: Fork, 14: Swivel body, 15: Shaft material, 16: Mounting seat, 17: Bearing part, 18: Weight, 19: Shaft material, 30: Swivel caster, 31: Thrust bearing, 32: Swivel body, 33: Fork, 34: Opening, 35: Roller, P, Q: Swivel axis, R: Running surface, S: Caster support part, U: External unit

Claims

1. A swivel caster having a wheel that rolls on a running surface and a fork that supports an axle to which the wheel is attached, and attached to an external unit, a rotating body that is rotatable relative to the external unit, The fork is rotatable relative to the rotating body, A swivel caster characterized in that a rotation axis P, which is the rotation center of the swivel body relative to the external unit, and a rotation axis Q, which is the rotation center of the fork relative to the swivel body, are non-parallel to each other, and when the rotation axis P is brought into contact with the rotation axis Q by parallel movement of the rotation axis P, they become non-perpendicular to each other.

2. The swivel caster according to claim 1, characterized in that the outer surface of the wheel that contacts the running surface is curved so that the distance to the axle becomes shorter from the widthwise center of the wheel toward the widthwise end.

3. 3. The swivel caster according to claim 2, wherein the radius of curvature of the outer peripheral surface of the wheel is half the outer diameter of the wheel.

4. Further provided is a thrust bearing attached to a shaft member along the pivot axis P and in contact with the fork, 2. The swivel caster according to claim 1, wherein the thrust bearing directly receives from the fork at least a portion of the force that the wheel receives from the running surface.

5. 5. The swivel caster according to claim 4, wherein the swivel body has an opening through which the fork is inserted.

6. The swivel caster according to any one of claims 1 to 5, characterized in that the swivel axis P and the swivel axis Q are arranged on the same imaginary plane.

7. A suitcase comprising the swivel caster according to any one of claims 1 to 5.

8. A wheeled bag comprising the swivel caster according to any one of claims 1 to 5.

9. A wheeled chair comprising the swivel caster according to any one of claims 1 to 5.

10. A cart comprising the swivel caster according to any one of claims 1 to 5.

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