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

Abstract

To provide a universal caster capable of suppressing the change of the direction of a wheel even when the wheel is separated from a traveling surface, and to provide a suitcase, a wheeled bag, a wheeled chair and a carriage equipped with the universal caster.SOLUTION: A swivel mechanism (14) having a wheel (12) that rotates about a shaft (11) and a fork (13) that supports the shaft (11) is a swivel caster (10) that swivels about a swivel axis (15), the shaft (11) is disposed at a position having a distance to both the swivel axis (15) and an extension line of the swivel axis (15), and a distance (Dg) from the swivel axis (15) to a center of gravity of the swivel mechanism (14) as viewed along the swivel axis (15) is 30% or less of a distance (Ds) from the swivel axis (15) to an axial center (C) of the shaft (11) as viewed along the swivel axis (15).SELECTED DRAWING: Figure 2

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 bodies of suitcases, carry-on bags, wheelchairs, and transport carts. As shown in Fig. 7, the swivel caster has a wheel 100, a shaft 101, and a fork 102 that can rotate around a pivot 103, and the shaft 101 is provided at a position that is a distance away from the extension of the pivot 103. Therefore, the swivel caster changes the direction of the wheel 100 in accordance with the direction of travel, and travels with the center of the wheel 100 positioned behind the pivot 103 in the direction of travel. 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. [Prior art documents] [Patent documents]

[0003] [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]

[0004] However, as shown in Fig. 8, when a conventional swivel caster is traveling with its swivel shaft 103 tilted relative to the vertical and the wheel 100 that was in contact with the running surface 104 separates from the running surface 104, the wheel 100 together with the shaft 101 and fork 102 often rotates about the swivel shaft 103 and changes direction. When the direction of the wheel 100 changes, the wheel 100 that has separated from the running surface 104 comes into contact with the running surface 104 again, which causes a problem that the smooth movement of the swivel caster is hindered. Note that Fig. 8 shows an example in which the running surface 104 is an inclined surface, but this problem is not limited to cases in which the running surface 104 is an inclined surface.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a swivel caster that can prevent the wheel from changing direction even when the wheel leaves the traveling surface, as well as a suitcase, a wheeled bag, a wheeled chair, and a cart that are equipped with the same. [Means for solving the problem]

[0006] The first invention of a swivel caster that meets the above-mentioned objective is a swivel caster in which a swivel mechanism having a wheel that rotates around a shaft and a fork that supports the shaft is swivelable around a swivel axis, the shaft is positioned at a distance from both the swivel axis and an extension of the swivel axis, and the distance Dg from the swivel axis to the center of gravity of the swivel mechanism, as viewed along the swivel axis, is 30% or less of the distance Ds from the swivel axis to the axis center of the shaft, as viewed along the swivel axis.

[0007] 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]

[0008] The caster of the first invention has a shaft positioned at a distance from both the swivel axis and the extension of the swivel axis, and the distance Dg from the swivel axis to the center of gravity of the swivel mechanism, as viewed along the swivel axis, is 30% or less of the distance Ds from the swivel axis to the axis of the shaft, as viewed along the swivel axis, so that the wheel direction can be prevented from changing even if the wheel moves away from the running surface.

[0009] 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, and therefore can prevent the wheels from changing direction even if they leave the running surface. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a front view of a swivel caster according to an embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] 10(A) to 10(C) are explanatory views showing the state in which the swivel caster descends an inclined surface. [Figure 5] FIG. 1 is an explanatory diagram of an experimental machine. [Figure 6] 10 is a graph showing experimental results. [Figure 7] FIG. 10 is an explanatory diagram of a conventional swivel caster. [Figure 8] FIG. 10 is an explanatory diagram showing a conventional swivel caster descending an inclined surface. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, with reference to the accompanying drawings, embodiments embodying the present invention will be described to aid in understanding the present invention. As shown in Figures 1, 2, and 3, a swivel caster 10 according to one embodiment of the present invention has a wheel 12 that rotates around a shaft 11 and a swivel mechanism 14 having a fork 13 that supports the shaft 11, and the swivel mechanism 14 is swivelable around a swivel axis 15.

[0012] 1, 2, and 3, the swivel caster 10 is provided with a mounting base 16 that is fixed to an object (such as a suitcase body or a bag body) to which the swivel caster 10 is to be attached. As shown in FIG. 3, the mounting base 16 has a through hole 17 formed therein so that the swivel caster 10 can be attached to the object using a screw or a bolt.

[0013] Depending on the usage environment, the mounting base 16 may be fixed to the object using adhesive tape such as double-sided tape, or adhesives such as epoxy resin, photocurable resin, thermosetting resin, and cyanoacrylate. The object and mounting base 16 may also be mechanically engaged to allow the swivel caster 10 to be attached and detached to the object. Furthermore, the swivel caster 10 may be firmly fixed to the object from the beginning, making it virtually impossible to remove the swivel caster 10 from the object.

[0014] 1, 2, and 3, the swivel mechanism 14 is made up of a shaft 11, wheels 12, forks 13, etc., and is supported on a mounting seat 16 so as to be rotatable about a swivel axis 15. The swivel axis 15 corresponds to the axis of rotation when expressing rotational motion in physics, and is not an actual member such as a shaft. In this embodiment, the swivel mechanism 14 is connected to the mounting seat 16 directly (i.e., without an intervening member such as a shaft), but the swivel mechanism 14 may also be attached to the mounting seat 16 so as to be rotatable (swivel) via an intervening member such as a shaft.

[0015] The shaft 11 is fixed to the fork 13 and passes through the center of the wheel 12. The shaft 11 is arranged horizontally with the pivot 15 arranged vertically, and the wheel 12 has a bearing portion (not shown) attached to the shaft 11 so as to be rotatable. The shaft 11 is disposed at a position that is distant from both the pivot axis 15 and the extension line of the pivot axis 15 .

[0016] Here, as shown in Figures 2 and 3, the distance from the swivel axis 15 to the center of gravity G of the swivel mechanism 14 when viewed along the swivel axis 15 (when viewed from the bottom or when viewed from above with the swivel axis 15 arranged vertically) is defined as distance Dg, and the distance from the swivel axis 15 to the axis C of the shaft 11 when viewed along the swivel axis 15 is defined as distance Ds.In this embodiment, the swivel caster 10 is designed so that the distance Dg is 30% or less of the distance Ds.

[0017] By designing in this manner, even if the wheel 12 that was in contact with the running surface moves away from the running surface with the swivel shaft 15 tilted relative to the vertical, the rotation of the swivel mechanism 14 of the swivel caster 10 is suppressed. As a result, when the swivel caster 10 is running on the running surface, even if the wheel 12 moves away from the running surface and then comes into contact with the running surface, the swivel caster 10 can continue to run smoothly.

[0018] In this regard, with the direction of travel of the swivel caster 10 being the front, for example, as shown in Fig. 4(A), when the swivel caster 10 is traveling on an inclined surface P with the center of gravity G of the swivel mechanism 14 located in front of the swivel shaft 15 and the swivel shaft 15 tilted relative to the vertical, even if the wheel 12 moves away from the inclined surface P as shown in Fig. 4(B), if the state in which the center of gravity G of the swivel mechanism 14 is located in front of the swivel shaft 15 is maintained, when the wheel 12 comes into contact with the inclined surface P again as shown in Fig. 4(C), the center of gravity G of the swivel mechanism 14 will be located in front of the swivel shaft 15, preventing excessive frictional force from occurring between the wheel 12 and the inclined surface P. As a result, the swivel caster 10 can continue to move smoothly.

[0019] From the viewpoint of stably suppressing the rotation of the swivel mechanism 14 when the wheel 12 that was in contact with the running surface separates from the running surface, it is preferable that the distance Dg be 15% or less of the distance Ds, and it is more preferable that the distance Dg be 5% or less of the distance Ds. This is because, when a person manually pulls a suitcase or carry-on bag equipped with the swivel caster 10, the inclination of the swivel shaft 12 with respect to the vertical is often 45 degrees or less, and it has been verified that if the inclination of the swivel shaft 12 with respect to the vertical is 45 degrees or less, the rotation of the swivel mechanism 14 can be stably suppressed by setting the distance Dg to 15% or less of the distance Ds. Furthermore, it has been confirmed through experimental verification that when the distance Dg is 5% or less of the distance Ds, the rotation of the swivel mechanism 14 can be stably suppressed even if the swivel caster 10 is arranged so that the swivel shaft 12 is horizontal.

[0020] In this embodiment, as viewed along the rotation axis 15, the center of gravity G of the rotation mechanism 14 and the centers (centers) of the rotation axis 15 and the shaft 11 are arranged in this order on a straight line as shown in Fig. 3, but this is not limited to this. For example, the center of gravity G of the rotation mechanism 14 may be arranged on the shaft center side of the shaft 11 with the rotation axis 15 as the reference, or the center of gravity G of the rotation mechanism 14 does not have to be arranged on a straight line passing through the centers of the rotation axis 15 and the shaft 11.

[0021] It goes without saying that the above-described effect of the swivel caster 10 (i.e., the effect of suppressing the rotation of the swivel mechanism 14 including the wheel 12 when the wheel 12 that was in contact with the running surface separates from the running surface) is also possessed by products equipped with the swivel caster 10. Therefore, suitcases, wheeled bags, wheeled chairs, carts, etc. equipped with the swivel caster 10 also have the same effect. Furthermore, for example, in the case of a cart equipped with multiple (for example, four) swivel casters 10, it is most preferable to use the swivel casters 10 of this embodiment for all four, but taking into consideration the usage environment and cost, it is also possible to use two of the four conventional casters and the other two swivel casters of this embodiment.

[0022] That is, when multiple casters are attached to a dolly or the like, using at least one of the swivel casters 10 of this embodiment allows for smoother movement and reduces noise compared to using conventional casters for all of the dolly's casters. Furthermore, even if all four of the dolly's casters 10 of this embodiment are used, depending on the usage environment, it is possible to make the position of the center of gravity G of the two front swivel casters 10 different from the position of the center of gravity G of the two rear swivel casters 10. Naturally, if the positions of the centers of gravity G of the swivel mechanisms 14 of all four swivel casters 10 are the same, noise is less likely to be generated, but the positions of the centers of gravity G of all four swivel casters 10 may be different. These can be changed as appropriate depending on the specifications and usage environment.

[0023] In this embodiment, as shown in Figures 1, 2, and 3, a counterweight 18 is attached to the fork 13 on the opposite side of the center of the wheel 12 relative to the pivot axis 15 when viewed along the pivot axis 15. Research into conventional swivel casters has shown that in many cases, the distance Dg is 80% or more of the distance Ds, and the ratio of the distance Dg to the distance Ds is at least about 50%. For such conventional swivel casters, it is possible to reduce the distance Dg to 30% or less of the distance Ds by retrofitting a counterweight 18. When the counterweight 18 is provided, the mounting position of the counterweight 18 is not limited to the above-mentioned position.

[0024] The counterweight 18 can be fixed to the fork 13 using screws or adhesive, and the position of the center of gravity G can be adjusted by adjusting the number of counterweights 18 attached (two in this embodiment). To enable adjustment of the center of gravity G with as few counterweights 18 as possible, a solid metal material with a relatively high specific gravity, such as lead, is used for the counterweight 18. To increase the durability of the counterweight 18, a counterweight 18 made of a high-specific-gravity metal with a surface coated with resin or the like is preferably used.

[0025] Furthermore, by constructing the counterweights 18 from magnets, it becomes easy to adjust the number of counterweights 18 and the position of the center of gravity G. That is, since the counterweights 18 are connected to each other by magnetic force, they are easy to attach and detach, and the number can be easily adjusted. In this case, it is preferable to use magnets with strong magnetic force, such as neodymium magnets, for the magnets used in the counterweights 18.

[0026] It is preferable that the counterweight 18 is formed integrally with the fork 13, that is, the counterweight 18 is added when manufacturing the fork 13, which will improve mass productivity. If the counterweight 18 is attached to the fork 13 after the fact as described above, it will be difficult to attach the counterweight 18, which will make it difficult to improve mass productivity.

[0027] To solve this problem, as described above, counterweights 18 made of magnets are attached to forks 13, and after adjusting the center of gravity G, the attachment position and weight of counterweights 18 on forks 13 are calculated in advance during the design stage. When designing forks 13 based on these calculated design values, it is preferable to take into account where and how much weight to attach, as well as the material of the weights and how to hold them.

[0028] By configuring the fork 13 in this manner, the mass productivity of the swivel caster 10 can be improved. For example, in the case of a swivel caster 10 that is produced in small quantities and in a wide variety of types, it is better to add the counterweight 18 later, and in the case of mass-producing swivel casters 10, it is preferable to mass-produce forks 13 with weights of specified weights at specified positions. [Example]

[0029] Next, an experiment conducted to confirm the effects of the present invention will be described. In the experiment, as shown in Fig. 5, a long plate 30 with a length of 200 mm was fixed between two wheels 32, 32a of a double-wheel type swivel caster 31, and a magnetic weight 33 was attached to the plate 30 (hereinafter referred to as the "experimental machine"). The swivel caster 31 was an HCHA8-60 manufactured by Misumi Corporation, and the distance X from the swivel shaft 34 to the axis 35 of the shafts of the wheels 32, 32a as viewed along the swivel shaft 34 was OFFSET was 17mm.

[0030] In the experimental machine, the position of the plate 30 relative to the swivel caster 10 was adjusted so that the longitudinal direction of the plate 30 was aligned with the rolling direction of the wheels 32, 32a (the direction in which the wheels 32, 32a rotate and move), the plate 30 was positioned perpendicular to the swivel shaft 34, and the swivel shaft 34 passed through the longitudinal center of the plate 30. Here, the end of the plate 30 located in the rolling direction of the wheels 32, 32a is referred to as the front end, and the end located on the opposite side is referred to as the rear end.

[0031] In the experimental machine, the entire components that rotate around the rotation axis 34, such as the wheels 32, 32a, the plate 30, and the weight 33, were defined as the rotation mechanism. The position of the center of gravity 36 of the rotation mechanism in the longitudinal direction of the plate 30 was changeable by changing the position of the weight 33 in the longitudinal direction of the plate 30.

[0032] Furthermore, the swivel mechanism was placed in a state where it was not in contact with other objects (i.e., the swivel mechanism was able to rotate freely around the swivel axis 34), and the experimental machine was tilted using a lab jack so that the longitudinal direction of the plate material 30 was tilted relative to the horizontal (i.e., the swivel axis 34 was tilted relative to the vertical), and then a turntable with an angular frequency of 2.07 Hz (48.26 seconds / 100 revolutions) was used to apply vibrations with an amplitude of approximately 10 mm to the experimental machine. In this experiment, the lab jack was used to tilt the plate material 30 by a maximum of 45 degrees relative to the horizontal.

[0033] In the experiment, the position of the center of gravity 36 of the rotation mechanism in the longitudinal direction of the plate material 30 and the inclination angle of the longitudinal direction of the plate material 30 relative to the horizontal (hereinafter simply referred to as the ``inclination angle of the plate material 30'') were fixed, and the above vibration was applied to the experimental machine for 10 seconds to measure whether the rotation angle of the rotation mechanism exceeded 90 degrees.If the rotation angle exceeded 90 degrees, the inclination angle of the plate material 30 at that time was recorded, and if the rotation angle did not exceed 90 degrees, the inclination angle of the plate material 30 was increased and the vibration was applied to the experimental machine for 10 seconds again to measure whether the rotation angle exceeded 90 degrees.

[0034] This process was repeated until the rotation angle exceeded 90 degrees, which was counted as one set. Ten sets of processing were performed for each longitudinal position of the plate material 30 at the center of gravity 36 of the rotation mechanism, and the average value of the inclination angle of the plate material 30 when the rotation angle exceeded 90 degrees in those ten sets of processing was calculated. The average value of the tilt angle of the plate material 30 when the turning angle exceeded 90 degrees was as shown in Fig. 6. The tilt angle of the plate material 30 was measured using an inclinometer.

[0035] In Figure 6, the vertical axis represents the tilt angle of the plate material 30, and the horizontal axis represents the ratio (in %) of the distance from the pivot axis 34 to the center of gravity 36 of the pivot mechanism to the distance from the pivot axis 34 to the axis 35 of the shaft. In Figure 6, when the center of gravity 36 of the pivot mechanism is located on the front side of the plate material 30 in the longitudinal direction relative to the pivot axis 34, the ratio on the horizontal axis is expressed as a negative value, and when the center of gravity 36 of the pivot mechanism is located on the rear side of the plate material 30 in the longitudinal direction relative to the pivot axis 34, the ratio on the horizontal axis is expressed as a positive value. Here, the position of the center of gravity 36 of the plate material 30 in the longitudinal direction with respect to the pivot axis 34 is defined as X G As, X G is the measured value W of the electronic scale on which the front end of the plate material 30 is placed. F and the measured value W of the electronic scale on which the rear end of the plate material 30 is placed. R Based on this, it was calculated using the following formula 1.

[0036] X G =(W F X F +W R X R ) / (W F +W R )...Equation 1

[0037] In Equation 1, X F and X R respectively represent the positions of the front and rear ends of the plate material 30 relative to the pivot axis 34, and X F =-100mm, X R = 100 mm. G The absolute value of corresponds to the distance from the pivot axis 34 to the center of gravity 36 of the pivot mechanism. In the case where the pivot angle of the plate material 30 does not exceed 90 degrees even when the tilt angle is set to the maximum of 45 degrees, the tilt angle of the plate material 30 is set to 45 degrees in FIG.

[0038] Furthermore, an experiment was conducted four times in which the experimental device was held in the hand, the tilt angle of the plate material 30 was set to 90 degrees, and the experimental device was swayed by hand, while changing the longitudinal position of the center of gravity 36 of the swivel mechanism on the plate material 30. In all four experiments, if the ratio of the distance from the swivel axis 34 to the center of gravity 36 of the swivel mechanism to the distance from the swivel axis 34 to the axis 35 of the shaft was 5% or less, the swivel mechanism did not swivel at all.

[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 shaft may be rotatably supported by a fork. In addition, there may be multiple wheels, and in the case where multiple wheels are provided, the center of the wheel refers to the center of all of the wheels. Therefore, for example, if two wheels of equal size arranged in parallel are provided, the center of the wheel is the center of the line segment connecting the centers of the two wheels.

[0040] Although the wheel is constructed by dividing it into a wheel portion and a tire portion made of a material different from that of the wheel portion, a disk-shaped wheel made of the same material may also be used. In addition, the swivel caster (shaft, wheel, fork (structure with adjusted center of gravity G), mounting base) may be made entirely of metal (stainless steel, titanium alloy, etc.) to improve durability and weather resistance, or part of it may be made of resin (preferably a high-strength resin containing carbon fiber, etc.) to reduce weight, etc. [Explanation of symbols]

[0041] 10: swivel caster, 11: shaft, 12: wheel, 13: fork, 14: swivel mechanism, 15: swivel shaft, 16: mounting seat, 17: through hole, 18: counterweight, 30: plate material, 31: swivel caster, 32, 32a: wheel, 33: weight, 34: swivel shaft, 35: shaft center, 36: center of gravity, C: shaft center, Dg, Ds: distance, G: center of gravity, P: inclined surface

Claims

1. A swivel caster in which a swivel mechanism having a wheel that rotates around a shaft and a fork that supports the shaft is swivelable around a swivel axis, The shaft is disposed at a position having a distance from both the pivot axis and an extension line of the pivot axis, A swivel caster characterized in that the distance Dg from the swivel axis to the center of gravity of the swivel mechanism, as viewed along the swivel axis, is 30% or less of the distance Ds from the swivel axis to the axis of the shaft, as viewed along the swivel axis.

2. 2. The swivel caster according to claim 1, wherein the distance Dg is 15% or less of the distance Ds.

3. 2. The swivel caster according to claim 1, wherein the distance Dg is 5% or less of the distance Ds.

4. 2. The swivel caster according to claim 1, wherein a counterweight is attached to the fork.

5. A suitcase comprising the swivel caster according to any one of claims 1 to 4.

6. A wheeled bag comprising the swivel caster according to any one of claims 1 to 4.

7. A wheeled chair comprising the swivel caster according to any one of claims 1 to 4.

8. A cart comprising the swivel caster according to any one of claims 1 to 4.

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