Two-wheel caster

Abstract

To provide a damper caster which has a high shock absorbing performance.SOLUTION: An arm member (20) being a main component of a damper caster, includes: an axle supporting member (30); a hollow portion (21) accommodating the axle supporting member (30); and a main rib (22) that surrounds the hollow portion (21). The axle supporting member (30) includes: an axle receiving portion (31) which is formed in a tadpole-like shape, and corresponds to a head of the tadpole-like shape; and a cantilever spring portion (32) which corresponds to a tail of the tadpole-like shape. The hollow portion (21) includes a spring accommodating portion (25). A compression coil spring (40) accommodated in the spring accommodating portion (25), is configured to push the axle receiving portion (31) against the main rib (22).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a dual wheel caster suitable for suitcases. [Background technology]

[0002] Travelers pack clothing and other travel necessities (hereafter referred to as "contents") into a suitcase, suitcase, or large bag (hereafter referred to as "suitcase"). Medium-sized and larger suitcases are inevitably heavy, so most are equipped with casters on the bottom. The wheels attached to the casters rotate on the floor or road surface (hereafter referred to as "floor"), so travelers can simply pull the suitcase sideways.

[0003] Incidentally, on the floor surface, there are braille blocks, carpets, floor tiles, and other unevennesses. These are collectively referred to as steps in the present invention.

[0004] When the wheels go over a step, the suitcase moves up and down. This vertical movement impacts the contents and the suitcase itself. From the viewpoint of protecting the suitcase itself and its contents, it is desirable to mitigate the vertical movement.

[0005] Therefore, shock-absorbing casters have been put to practical use in the past. Various structures of shock-absorbing casters are known (for example, see Patent Document 1 (FIGS. 2 and 6)).

[0006] Patent Document 1 will be explained with reference to the following figure. 8(a) to (d) are diagrams illustrating the basic structure and function of a conventional shock-absorbing caster. As shown in FIG. 8(a), the shock-absorbing caster 100 comprises a base member 101 fixed to the bottom of a suitcase, a fork member 103 attached to the base member 101 so as to be rotatable about a vertical axis 102, an axle 104 hung horizontally on the lower end of the fork member 103, and a wheel 105 supported by the axle 104.

[0007] As shown in FIG. 8(b), the fork member 103 is made up of a rotary bearing portion 106 extending along the vertical axis 102, and an arm portion 107 extending obliquely downward from the lower end of the rotary bearing portion 106. The arm 107 has a gourd-shaped cavity 108 along its longitudinal axis, and this cavity 108 is filled with a vibration absorbing material 109. The axle 104 is attached to the arm 107 at a substantially central lower position of the gourd-shaped gap 108 .

[0008] As shown in Fig. 8(c), in the no-load state, the width W1 at the center of gap 108 is maintained. When wheel 105 rides over a step on the floor surface, an upward force is applied to axle 104. Then, lower center point 111 of gap 108 rises. Upper center point 112 of gap 108 does not displace.

[0009] 8(d), the width of the center of gap 108 changes from W1 to W2, which is smaller. Vibration absorbing material 109 is compressed by (W1-W2), so it absorbs the shock. At the same time, part of arm 107 (the part below gap 108) is elastically deformed, so arm 107 also absorbs the shock.

[0010] When the wheel 105 passes over the step and the upward force disappears, the arm 107 returns to its original position as shown in FIG. 8(c).

[0011] As described above, the shock-absorbing caster 100 is provided, which reduces the shock when the wheel 105 travels. However, the shock-absorbing caster 100 has the following problems. First, (W1-W2) explained in Figures 8(c) and (d) is small. If (W1-W2) is small, it cannot handle large steps. If (W1-W2) is increased, the fork member 103 becomes larger, which affects the appearance and leads to increased weight and costs. There is a demand for improving shock absorbing performance without increasing costs.

[0012] Secondly, when the product is used for a long period of time and the cumulative number of times it goes over steps increases, fatigue accumulates and a crack 113 appears at one end (or both ends) of the gap 108 shown in FIG. 8(d). As a countermeasure, if the fork member 103 is made thicker, this will result in an increase in weight and cost.

[0013] Thirdly, as shown in FIG. 8(b), the gourd-shaped gap 108 is visible from the outside, which reduces the appearance.

[0014] Therefore, there is a demand for shock-absorbing casters that have high shock-absorbing performance and also have a good appearance. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] JP 2015-67100 A Summary of the Invention [Problem to be solved by the invention]

[0016] An object of the present invention is to provide a shock-absorbing caster having high shock absorbing performance and good appearance. [Means for solving the problem]

[0017] The invention according to claim 1 is a twin-wheel caster comprising a rotating shaft portion that rotates around a vertical axis, an arm member that extends obliquely downward from the lower end of the rotating shaft portion, an axle that is attached horizontally to the lower part of the arm member, a left wheel that is attached to the left end of the axle, and a right wheel that is attached to the right end of the axle, The arm member includes an axle support member that supports the axle, a hollow portion that houses the axle support member so that the axle support member can move up and down, and a main rib that surrounds the hollow portion, The axle support member has a ladle-like shape and includes an axle bearing portion corresponding to the head and having an axle hole through which the axle passes, and a cantilever spring portion corresponding to the tail and connected to the main rib, The hollow portion includes a spring storage portion that stores a compression coil spring, and the compression coil spring presses the wheel bearing portion against the main rib, and the impact generated when the left wheel and the right wheel go over a step in the floor surface is absorbed by the deflection of the cantilever spring portion and the contraction of the compression coil spring.

[0018] The invention according to claim 2 is the twin-wheel caster according to claim 1, The cavity is characterized in that it is hidden by the left wheel and the right wheel.

[0019] The invention according to claim 3 is the twin-wheel caster according to claim 2, The left wheel and the right wheel are characterized in that they have at least one window through which a part of the cantilever spring portion and a part of the compression coil spring can be seen. Effect of the Invention

[0020] In the invention according to claim 1, impact is absorbed by two actions: bending the cantilever spring portion and compressing the compression coil spring. Compared with the conventional gourd-shaped gap, the cantilever spring of the present invention can be deflected upward to a greater extent. As a result, the present invention provides a shock-absorbing caster with high shock absorbing performance.

[0021] In the invention according to claim 2, the hollow portion is hidden by the left and right wheels, so that the appearance is good. As a result, the present invention provides a shock-absorbing caster having high shock absorbing performance and good appearance.

[0022] In the invention according to claim 3, the left and right wheels have at least one window through which the cantilever spring part and the compression coil spring can be seen. In the unlikely event that the cantilever spring part and / or the compression coil spring becomes worn, the state of the cantilever spring part and the compression coil spring can be visually inspected and measures can be taken without removing the left or right wheel. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a front view of the dual-wheel caster according to the present invention. [Diagram 2] FIG. 2 is an exploded view of a dual-wheel caster. [Diagram 3] 3 is a view taken along the line 3-3 in FIG. 2, showing a side view of the arm member. [Figure 4] 4(a) and (b) are explanatory views of the operation of the arm member. [Diagram 5] FIG. 1A is a diagram for explaining Comparative Example 1, and FIG. 1B is a diagram for explaining Comparative Example 2. [Figure 6] FIG. 2 is a side view of a dual-wheel caster. [Figure 7] 13(a) and 13(b) are diagrams illustrating a modified example of a dual-wheel caster. [Figure 8] 1(a) to 1(d) are diagrams illustrating the basic structure and function of a conventional shock-absorbing caster. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. EXAMPLES

[0025] [Dual wheel casters] As shown in Figure 1, the twin-wheel caster 10 consists of a base member 11 attached to the bottom of a suitcase, a rotating shaft portion 12 attached to this base member 11 so as to be rotatable around a vertical axis 12a, an arm member 20 extending downward from the lower end of this rotating shaft portion 12, an axle (Figure 2, symbol 13) attached to the lower part of the arm member 20, a left wheel 14 attached to the left end of the axle, and a right wheel 15 attached to the right end of the axle.

[0026] As shown in Figure 2, the main components are an arm member 20, an axle 13, a left wheel 14, and a right wheel 15. The axle 13 has a head 16 at one end and a clip 17 attached to the tip, which holds the left wheel 14 and the right wheel 15 so that they do not come off. However, the structure of the axle 13 may be modified as appropriate.

[0027] In addition, a disk 18 with a hole is interposed between the left wheel 14 and the arm member 20 to prevent the boss 34 of the arm member 20 from being worn down by the rotating left wheel 14. Similarly, a disk 18 with a hole is interposed between the right wheel 15 and the arm member 20.

[0028] [Arm parts] 3, an arm member 20 extends obliquely downward from the lower end of the rotating shaft portion 12 that extends along the vertical axis 12a. This arm member 20 is a block having a hollow portion 21. This block is preferably a resin molded product or a light metal molded product. The arm member 20 comprises a main rib 22 surrounding the hollow portion 21, a plurality of cutout portions 23 in contact with the main rib 22, a secondary rib 24 surrounding these cutout portions 23, and an axle support member 30 extending from the main rib 22 to the hollow portion 21.

[0029] [Axle support member] 3, the axle support member 30 is shaped like a tadpole and consists of an axle bearing part 31 corresponding to the head and a cantilever spring part 32 corresponding to the tail, with the tip of the cantilever spring part 32 connected to the main rib 22. The axle bearing part 31 has an axle hole 33 through which the axle (FIG. 2, reference numeral 13) passes and a boss 34 surrounding this axle hole 33.

[0030] Preferably, as in the embodiment, the height dimension of the cantilever spring portion 32 is made smaller at the tip (the side connected to the main rib 22) than at the wheel bearing portion 31 side. In other words, the tip is tapered relative to the base like a tail. The advantages of this structure are as follows. The cantilever spring portion 32 is not bent overall with the same curvature, but is bent greatly near the tip.

[0031] As a result, when the left wheel 14 (and the right wheel 15) goes over a step, the wheel bearing portion 31 moves upwards quickly. After passing the step, the wheel bearing portion 31 moves downwards quickly. A tapered tail, rather than one with a constant thickness, is better able to conform to bumps and therefore more effectively absorbs shocks.

[0032] However, the stress is greatest at the tip of the tail, and the cross-sectional area of ​​the tip of the tail is small, so the stress is greatest there. After a long period of use, it is expected that the axle support 30 will be damaged. In this case, the damage will be concentrated at the tip of the tail. It is desirable to monitor this concentrated area, i.e., the tip of the tail (cantilever spring portion 32), using the window portion 19 described later in Fig. 6. If defects such as cracks can be found, repairs or other measures can be taken before a serious problem occurs.

[0033] As shown in FIG. 4( a ), the cantilever spring portion 32 extends substantially parallel to the central axis 20 a of the arm member 20 .

[0034] 3, the hollow portion 21 penetrates in the front-to-back direction of the drawing, but the multiple lightening holes 23 do not penetrate in the front-to-back direction of the drawing. However, due to the presence of the multiple lightening holes 23, the arm member 20 is sufficiently lightweight.

[0035] The hollow portion 21 has a spring storage portion 25 that stores a compression coil spring 40. An upper spring seat 26 is integrally formed with the main rib 22 at a portion facing the spring storage portion 25. A lower spring seat 35 is formed integrally with the wheel bearing portion 31 .

[0036] A compression coil spring 40 is set between the upper spring seat 26 and the lower spring seat 35. A spring axis 41 passing through the center of the compression coil spring 40 passes through the center of the upper spring seat 26, the center of the lower spring seat 35, and the center of the axis hole 33. The spring shaft 41 is provided at a position that forms an angle of approximately 90° with the longitudinal axis of the cantilever spring portion 32 .

[0037] The operation of the arm member 20 having the above-mentioned structure will be described with reference to FIGS. As shown in FIG. 4( a ), the wheel bearing portion 31 is pressed against the main rib 22 by the reaction force of the compression coil spring 40 .

[0038] The setting of the compression coil spring 40 is arbitrary, but it is recommended that the wheel bearing portion 31 be in contact with the main rib 22 even when the suitcase is filled with a predetermined weight of contents. The predetermined weight refers to the weight of the suitcase's full load of clothes. If this recommendation is followed, the state of FIG. 4(a) will generally be maintained when the suitcase is placed on the floor and when the suitcase moves laterally on a floor surface that is smooth.

[0039] When the suitcase approaches a step in the floor, an upward force is applied to the axle 13. As shown in FIG. 4(b), the cantilever spring portion 32 is deflected upward by δ, and the compression coil spring 40 is compressed by δ. The cantilever spring portion 32 is a cantilever spring, and the product of the spring constant and the amount of deflection δ of the cantilever spring portion 32 becomes a reaction force. The compression coil spring 40 generates a reaction force equal to the product of the spring constant and the amount of compression δ.

[0040] According to the formula (reaction force of cantilever spring portion 32 + reaction force of compression coil spring 40) = upward force, the shape shown in Figure 4(b) is determined when the upward force is balanced with (the sum of the reaction force due to the deflection of the cantilever spring portion 32 and the contraction of the compression coil spring 40). That is, the impact caused by the step is absorbed by the flexure of the cantilever spring portion 32 and the contraction of the compression coil spring 40 . Once you pass the step, you will return to Figure 4(a).

[0041] [Comparative Example 1] The superiority of the embodiment of the present invention over the comparative example will be described with reference to FIGS. 5(a) and 5(b). 5(a) shows Comparative Example 1. The shock absorbing caster 120 in Comparative Example 1 comprises a base member 121, a bolt 122 attached to the base member 121 from below, an arm member 123 extending diagonally downward from the lower end of the bolt 122, and a wheel 124 rotatably attached to the lower end of the arm member 123. A compression coil spring 125 is provided between the base member 121 and the arm member 123.

[0042] When the wheel 124 rides over a step 126 on the floor surface, the compression coil spring 125 contracts, and when the wheel 124 passes over the step 126, it returns to its original state. However, in the structure of Comparative Example 1, the bolt 122 is necessarily long, and the bolt 122 is bent every time it goes over the step 126. The outer diameter of the bolt 122 needs to be increased to withstand the bending, and the shock-absorbing caster 120 becomes heavy.

[0043] [Comparative Example 2] 5(b) shows Comparative Example 2. In this Comparative Example 2, the bolt 132 is short. The shock-absorbing caster 130 in Comparative Example 2 comprises a base member 131, a bolt 132 attached to the base member 131 from below, an arm member 133 extending diagonally downward from the lower end of the bolt 132, and a wheel 134 attached to the lower end of the arm member 133 so as to be freely rotatable, and the arm member 133 has a narrowed portion 135.

[0044] When wheel 134 rides over step 136 in the floor surface, constricted portion 135 deforms, and returns to its original shape when wheel 134 passes step 136. Since bolt 132 is short, there is an advantage that the outer diameter of bolt 132 can be small. On the other hand, there is a disadvantage that if constricted portion 135 is visible from the outside, the appearance is degraded.

[0045] Incidentally, the arm member 133 is made of resin or light metal. Resin and light metal inevitably suffer from creep. Creep is a phenomenon in which an object gradually undergoes permanent deformation over time when a certain load is applied to the object.

[0046] In the structure of Comparative Example 2, after a long period of use, permanent deformation occurs in the constricted portion 135, and the constricted portion 135 cannot return to its original shape, and finally breaks. If the cross-sectional area of ​​the constricted portion 135 is increased in order to avoid breakage, the deformability will decrease, and the base member 131 will move up and down every time it goes over a step 136. This movement up and down will cause the suitcase to move up and down, making it difficult to use.

[0047] [Advantages of the present invention] In this regard, according to the present invention, when going over a step, the shock to the suitcase is mitigated by the gentle bending of the cantilever spring portion 32 as shown in FIG. 4(b). In addition, since the cantilever spring portion 32 is a cantilever beam that has the property of bending up and down, the axle 13 is easily displaced upward. Therefore, the shock absorbing caster 10 having higher shock absorbing performance than the conventional one is provided.

[0048] Also, according to the present invention, most of the time (from when the suitcase is empty to when it is filled with a certain weight of contents), the wheel bearing portion 30 is pressed against the main rib 22 by the force of the compression coil spring 40 as shown in Fig. 4(a). In this state, the cantilever spring portion 32 is not deflected, so creep does not occur.

[0049] 4(a), the width in the front-to-back direction of the drawing (the width of the cantilever spring portion 32) can be increased, thereby reducing the stress in the cantilever spring portion 32. If the stress is low, no cracks will occur due to fatigue. As a result, the structure of the present invention provides a shock-absorbing caster 10 that is less susceptible to creep and cracking.

[0050] As shown in Fig. 6, most of the arm member 20 is hidden by the left wheel 14 and the right wheel 15, and the hollow portion 21 described in Fig. 3 is not visible. As a result, the appearance is greatly improved.

[0051] If the contents contain a large number of metal products, books, and paper products, the weight of the contents will exceed a certain weight. If this occurs frequently, the possibility of the cantilever spring portion 32 and the compression coil spring 40 shown in FIG. 3 becoming worn cannot be said to be zero.

[0052] [Window section] Therefore, preferably, as shown in Fig. 6, a window 19 is provided in the left wheel 14 and the right wheel 15, through which part of the cantilever spring portion 32 and part of the compression coil spring 40 can be seen through. The horizontal dimension of the window 19 is set to be the same as the width of the spring storage portion (Fig. 3, reference numeral 25).

[0053] When a defect is suspected in either or both of the cantilever spring portion 32 and the compression coil spring 40, the condition can be checked by looking through the window portion 19 without removing the left wheel 14 or the right wheel 15. It is preferable that four windows 19 are provided at a pitch of 90 degrees. First, the left wheel 14 (or right wheel 15) is manually rotated by up to 90° to reach FIG. Second, in FIG. 6, both the cantilever spring portion 32 and the compression coil spring 40 can be seen. Thirdly, the windows 19 are arranged at equal intervals, providing a good balance and improving the design.

[0054] [Example of changes to windows] As shown in FIG. 7(a), the number of window portions 19 may be one. From FIG. 7(a), the window portion 19 can be aligned with the cantilever spring portion (FIG. 6, reference numeral 32) by rotating the left wheel 14 (or the right wheel 15) clockwise by 90 degrees. That is, through one window 19, either the cantilever spring portion (FIG. 6, reference numeral 32) or the compression coil spring 40 can be selectively viewed.

[0055] 7(b), there may be a pair (two) of windows 19. Both the cantilever spring portion 32 and the compression coil spring 40 can be seen through the windows. However, since the windows 19 are provided at the 12 o'clock and 3 o'clock positions, like those on a watch, it cannot be said that the design is well balanced, and is inferior to a design with four windows. In addition, when comparing one with two, one is less noticeable and has a better design.

[0056] In other words, as long as the left wheel 14 and the right wheel 15 have at least one window portion 19 through which part of the cantilever spring portion 32 and part of the compression coil spring 40 can be seen, the cantilever spring portion 32 and the compression coil spring 40 can be visually observed, and the number of windows 19 can be selected from four, two, or one, taking into consideration both ease of use and design.

[0057] If the cantilever spring portion 32 and the compression coil spring 40 do not become worn after a predetermined number of uses, the window portion 19 may be eliminated to improve the appearance of the left wheel 14 or the right wheel 15.

[0058] Furthermore, the dual-wheel caster 10 of the present invention may be attached to the bottom of a suitcase or bag, or may be attached to a dolly, cabinet, carrier, or similar moving object. [Industrial Applicability]

[0059] The dual-wheel caster of the present invention is suitable for suitcases. [Explanation of symbols]

[0060] 10...dual-wheel caster, 12...rotating shaft portion, 12a...vertical shaft, 13...axle, 14...left wheel, 15...right wheel, 19...window portion, 20...arm member, 21...hollow portion, 22...main rib, 25...spring storage portion, 30...axle support member, 31...axle bearing portion, 32...cantilever spring portion, 33...axle hole, 40...compression coil spring, 126, 136...step.

Claims

1. A twin-wheel caster comprising a rotating shaft portion that rotates around a vertical axis, an arm member that extends obliquely downward from the lower end of the rotating shaft portion, an axle that is attached horizontally to the lower part of the arm member, a left wheel that is attached to the left end of the axle, and a right wheel that is attached to the right end of the axle, The arm member includes an axle support member that supports the axle, a hollow portion that houses the axle support member so that the axle support member can move up and down, and a main rib that surrounds the hollow portion, The axle support member has a ladle-like shape and includes an axle bearing portion corresponding to the head and having an axle hole through which the axle passes, and a cantilever spring portion corresponding to the tail and connected to the main rib, The hollow portion includes a spring storage portion that stores a compression coil spring, and the compression coil spring presses the wheel bearing portion against the main rib, and an impact generated when the left wheel and the right wheel go over a step in the floor surface is absorbed by the deflection of the cantilever spring portion and the contraction of the compression coil spring.

2. The dual wheel caster according to claim 1, A dual-wheel caster, wherein the hollow portion is hidden by the left wheel and the right wheel.

3. The dual wheel caster according to claim 2, The dual-wheel caster is characterized in that the left wheel and the right wheel have at least one window through which a part of the cantilever spring portion and a part of the compression coil spring can be seen.

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