telescopic device

Abstract

To provide an expansion device capable of preventing two belts from disengaging during expansion / contraction.SOLUTION: An expansion device according to the present disclosure is an expansion device in which a first belt 11 and a second belt 12 wound around the outside of the first belt 11 are spirally wound around a cylindrical structure 13. The second belt 12 comprises an engagement pin 12a having a fitting part 21 that is fitted into a hole 11a of the first belt 11 and an insertion part 20 that protrudes from the fitting part 21 and is inserted into the hole 11a of the first belt. The fitting part 21 has a cylindrical shape with a diameter corresponding to the holes 11a, 11b of the first belt 11, and side surfaces 20a, 20b of the insertion part 20 are inclined so that a diameter of the insertion part 20 becomes smaller toward a tip part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to a telescopic device.

Background Art

[0002] Patent Document 1 discloses a telescopic device that can be compactly stored by overlapping and winding two belts around a cylindrical structure with a half-width shift. An engagement pin that is inserted into the hole of the inner belt is attached to the outer belt, and the two belts are integrated via the engagement pin. The telescopic device can be telescoped by rotating the two belts by the power of a motor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the telescopic device described above, since the engagement pin is tapered so as to be easily inserted into the hole of the inner belt, a gap occurs when the engagement pin is inserted into the hole of the inner belt. Therefore, due to the load during telescoping, the engagement pin may come out of the hole of the inner belt, and the engagement between the two belts may be disengaged.

[0005] This disclosure has been made in view of such circumstances, and provides a telescopic device capable of suppressing the disengagement of the engagement between two belts during telescoping.

Means for Solving the Problems

[0006] The telescopic device according to this disclosure is a telescopic device in which a first belt and a second belt wound around the outside of the first belt are wound around a cylindrical structure in a spiral shape, The second belt comprises an engagement pin having a fitting portion that fits into a hole in the first belt and an insertion portion that protrudes from the fitting portion and is inserted into a hole in the first belt. The fitting portion is cylindrical in shape and has a diameter corresponding to the hole in the first belt. The side surface of the insertion portion is inclined such that the diameter of the insertion portion decreases towards the tip.

[0007] In the expandable device according to this disclosure, the fitting portion of the engagement pin has a diameter corresponding to the hole in the first belt. Therefore, the fitting portion 21 of the engagement pin is fitted into the hole in the first belt without any gaps. This prevents the engagement between the first belt and the second belt from disengaging when the expandable device expands or contracts.

[0008] The inclination of the side surface of the insertion portion may be an involute curve shape with a base circle having the same center as the cylindrical structure and a diameter less than or equal to that of the cylindrical structure. This configuration makes it easier to insert the engagement pin into the hole of the first belt.

[0009] The diameter of the base circle may be equal to the diameter of the cylindrical structure. This configuration also makes it easy to insert the engagement pin into the hole of the first belt. [Effects of the Invention]

[0010] This disclosure provides an expandable / contractable device that can prevent the engagement between the two belts from disengaging during expansion and contraction. [Brief explanation of the drawing]

[0011] [Figure 1] These are a side view and a cross-sectional view of the expandable portion of the expandable device according to Embodiment 1. [Figure 2] This is a cross-sectional view showing the shape of the engagement pin in the telescopic device according to Embodiment 1. [Figure 3] This is a cross-sectional view showing the shape of the engagement pin in the expandable device according to the comparative example. [Figure 4]This is a plan view and an enlarged view at point Q, showing the process of spirally wrapping a second belt around a cylindrical structure. [Figure 5] This is a cross-sectional view showing a modified shape of the engagement pin in the expandable device according to Embodiment 2. [Modes for carrying out the invention]

[0012] The present invention will be described below through embodiments of the invention, but the invention claimed is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential as means of solving the problem. For clarity of explanation, the following descriptions and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations have been omitted where necessary. It should be noted that the right-handed xyz Cartesian coordinate system shown in the diagram is merely a convenient representation for explaining the positional relationships of the components. Typically, the positive z-axis is vertically upward, and the xy-plane is horizontal.

[0013] (Embodiment 1) <Configuration of the expansion joint> First, the configuration of the expandable device according to Embodiment 1 will be described with reference to Figure 1. Figure 1(a) is a side view of the expandable portion of the expandable device according to Embodiment 1. Figure 1(b) is a cross-sectional view of the expandable portion of the expandable device according to Embodiment 1, and corresponds to the cross-section at the cutting line Ib-Ib in Figure 1(a).

[0014] As shown in Figure 1(a), the expandable portion 10 is constructed by spirally wrapping a first belt 11 and a second belt 12, which is wrapped around the outside of the first belt 11, around the central axis C1 of the cylindrical structure 13.

[0015] As shown in Fig. 1(a), in the telescopic part 10, the second belt 12 is wound from the outside with a half-width shift relative to the first belt 11. More specifically, the upper edge side portion of the second belt 12 overlaps from the outside with the lower edge side portion of the first belt 11 disposed above it, and the lower edge side portion of the second belt 12 overlaps from the outside with the upper edge side portion of the first belt 11 disposed below it.

[0016] As shown in Fig. 1(a), the second belt 12 is provided with engagement pins 12a and 12b. The engagement pins 12a and 12b are provided at two locations each on the upper edge side and the lower edge side at a predetermined interval in the longitudinal direction of the second belt 12.

[0017] As shown in Fig. 1(a), the first belt 11 is provided with holes 11a and 11b. The holes 11a and 11b are provided at two locations each on the upper edge side and the lower edge side at a predetermined interval in the longitudinal direction of the first belt 11.

[0018] The engagement pin 12a fits into the hole 11a, and the engagement pin 12b fits into the hole 11b. That is, in the telescopic part 10, while winding the second belt 12 around the first belt 11 with a half-width shift from the outside, the engagement pins 12a and 12b are fitted into the corresponding holes 11a and 11b.

[0019] As shown in Figs. 1(a) and (b), a spiral groove 13c is formed in the cylindrical structure 13. As shown in Fig. 1(b), in the telescopic part 10, the engagement pins 12a and 12b of the second belt 12 are fitted into the corresponding holes 11a and 11b of the first belt 11, and are slidably carried into the groove 13c of the cylindrical structure 13. In this way, the first belt 11, the second belt 12, and the cylindrical structure 13 form an integral structure.

[0020] <Configuration of the telescopic device> Next, with reference to Fig. 1, the operation of the telescopic part 10 in the telescopic device according to Embodiment 1 will be described.

[0021] First, we will explain the case where the expandable portion 10 extends in the direction of the central axis C1 (positive z-axis direction) of the cylindrical structure 13. As shown in Figure 1(a), a rotational force is applied to the cylindrical structure 13 by a motor (not shown). Here, although not shown in Figure 1(a), a storage section is provided on the radially outer side of the cylindrical structure 13 for winding and housing the first belt 11 and the second belt 12.

[0022] When the cylindrical structure 13 is rotated around the central axis C1 in the direction indicated by the arrow, the first belt 11 and the second belt 12, which were wound up in the housing, are wound up along the groove 13c and engage with each other, winding spirally around the cylindrical structure 13. In this way, the first belt 11 and the second belt 12, which are unwound from the housing, engage with each other and wind spirally around the cylindrical structure 13, thereby allowing the expandable section 10 to be extended in the direction of the central axis C1.

[0023] On the other hand, let's explain the case where the expandable portion 10 contracts in the direction of the central axis C1 (negative z-axis direction) of the cylindrical structure 13. In this case, it is rotated in the opposite direction to the direction indicated by the arrow in Figure 1(a). When the cylindrical structure 13 is rotated in the opposite direction to the direction indicated by the arrow around the central axis C1, the first belt 11 and the second belt 12, which were spirally wound around the cylindrical structure 13, move along the groove 13c, disengage from each other, and are wound back into the storage section. In this way, the first belt 11 and the second belt 12, which were spirally wound around the cylindrical structure 13, are wound back into the storage section, allowing the expandable portion 10 to be contracted in the direction of the central axis C1. Furthermore, by winding the first belt 11 and the second belt 12 back into the storage section, the first belt 11 and the second belt 12 can be stored compactly.

[0024] <Engagement pin shape> Next, the shape of the engagement pin in the telescopic device according to Embodiment 1 will be described with reference to Figure 2. Since the engagement pins 12a and 12b shown in Figure 1 have the same shape, the shape of engagement pin 12a will be described. Figure 2 is a cross-sectional view showing the shape of the engagement pin in the telescopic device according to Embodiment 1.

[0025] As shown in Figure 2, the engaging pin 12a has an insertion portion 20 and a fitting portion 21. The insertion portion 20 protrudes from the fitting portion 21 and is inserted into the hole 11a of the first belt 11. The fitting portion 21 is fitted into the hole 11a of the first belt 11.

[0026] The shape of the insertion portion 20 will be described in detail with reference to Figure 2. The insertion portion 20 has a frustoconical shape in which the side surface of the insertion portion 20 is inclined such that the diameter in the z-axis direction decreases toward the tip. In this way, because the diameter of the insertion portion 20 decreases toward the tip in the z-axis direction, the engagement pin 12a can be inserted into the hole 11a when the second belt 12 is wrapped around the first belt from the outside.

[0027] The shape of the fitting portion 21 will be described in detail with reference to Figure 2. The fitting portion 21 is cylindrical in shape with a diameter corresponding to the hole 11a of the first belt 11. Also, in Figure 2, the thickness of the fitting portion 21 (in the x-axis direction) is greater than the thickness of the first belt 11. However, it is not limited to this, and the thickness of the fitting portion 21 (in the x-axis direction) may be equal to the thickness of the first belt 11.

[0028] <Engagement pin shape in comparative example> Next, with reference to Figure 3, the shape of the engagement pin in the comparative example's expandable device will be described. The expandable device in the comparative example differs from the expandable device in Embodiment 1 in the shape of the engagement pin. Since the other components are the same, their explanation will be omitted. Figure 3 is a cross-sectional view showing the shape of the engagement pin in the expandable device of the comparative example.

[0029] As shown in Figure 3, the engaging pin 32a in the comparative example of the expandable device has an insertion portion 30 and a fitting portion 31. The insertion portion 30 is formed to protrude from the fitting portion 31.

[0030] As shown in Figure 3, the insertion portion 30 has a frustoconical shape in which the side surface 30a of the insertion portion 30 is inclined such that the diameter in the z-axis direction decreases towards the tip.

[0031] As shown in Figure 3, the fitting portion 31 has a frustoconical shape in which the side surface 31a of the fitting portion 31 is inclined such that the diameter in the z-axis direction decreases towards the tip.

[0032] Here, the angle A1 formed by the side surface 31a and the line parallel to the z-axis is greater than the angle A2 formed by the side surface 30a and the line parallel to the z-axis. In other words, the engaging pin 32a is tapered in two stages, gradually decreasing towards its tip, with the insertion portion 30 and the fitting portion 31 as the boundary.

[0033] Therefore, as shown in Figure 3, when the fitting portion 31 of the engaging pin 32a is fitted into the hole 11a of the first belt 11, a gap is created between it and the hole 11a of the first belt 11. Consequently, the engagement between the first belt 11 and the second belt 12 is easily disengaged when the expandable / contractible device expands or contracts.

[0034] In contrast, the fitting portion 21 of the engagement pin 12a shown in Figure 2 is cylindrical in shape with a diameter corresponding to the hole 11a of the first belt, and fits snugly into the hole 11a of the first belt 11 without any gaps. Therefore, the engagement between the first belt 11 and the second belt 12 is less likely to disengage when the expandable / contractable device expands or contracts.

[0035] Thus, in the expandable device according to Embodiment 1, the fitting portion 21 of the engaging pin 12a is cylindrical in shape with a diameter corresponding to the hole 11a of the first belt, and fits snugly into the hole 11a of the first belt 11. This prevents the engagement between the first belt 11 and the second belt 12 from disengaging when the expandable device expands or contracts.

[0036] (Embodiment 2) <Engagement pin shape> Next, the expandable device according to Embodiment 2 will be described. The expandable device according to Embodiment 2 differs from the expandable device according to Embodiment 1 in the shape of the engaging pin. The other components are the same as those of the expandable device according to Embodiment 1, so their description will be omitted.

[0037] First, referring to Figure 4(a), we will explain the trajectory traced by the engagement pin when the second belt 12 is spirally wrapped around the cylindrical structure 13. Figure 4(a) is a plan view of the second belt spirally wrapped around the cylindrical structure.

[0038] As shown in Figure 4(a), when the second belt 12 is spirally wrapped around the cylindrical structure 13 with point P as the fulcrum, the trajectory of the end 12e of the second belt is an involute curve IC1 with a base circle equal to the diameter of the cylindrical structure 13.

[0039] As shown in Figure 4(a), the engagement pins 42a are provided at predetermined intervals along the longitudinal direction of the second belt 12. When the second belt 12 is spirally wound around the cylindrical structure 13 with point P as the pivot point, the trajectories of the three engagement pins 42a shown in Figure 4(a) are involute curves IC2, IC3, and IC4, respectively, which are smaller than the involute curve C1. As the position of the engagement pins 42a approaches the end 12e of the second belt, the trajectory of the engagement pins 42a becomes a curve that is closer in size to the involute curve C1. The base circles of the involute curves IC2, IC3, and IC4 are, like the involute curve C1, circles with the diameter of the cylindrical structure 13.

[0040] Next, the shape of the engagement pin of the expandable device according to Embodiment 2 will be described with reference to Figure 4(b). Figure 4(b) is an enlarged view of point Q when the second belt is spirally wrapped around the cylindrical structure. Here, the engagement pin 42a that traces the trajectory of the involute curve IC2 will be described. In the following, the insertion portion 40 of the engagement pin 42a will be referred to as the tip portion on the cylindrical structure 13 side and the base portion on the fitting portion 41 side.

[0041] As shown in Figure 4(b), the engaging pin 42a has an insertion portion 40 and a fitting portion 41. The insertion portion 40 is formed to protrude from the fitting portion 41. The fitting portion 41 is the same as the fitting portion 21 of the engaging pin 12a in the telescopic device according to Embodiment 1, so its description is omitted.

[0042] As shown in Figure 4(b), the inclination of the side surface 40a of the insertion portion 40 in the engaging pin 42a has the shape of an involute curve IC2.

[0043] The angle between the side surface 40a of the engaging pin 42a and the central axis C2 of the engaging pin 42a decreases towards the tip. In other words, the side surface 40a of the engaging pin 42a has a steep slope near the base and becomes gentler towards the tip.

[0044] Thus, the inclination of the side surface 40a of the insertion portion 40 in the engaging pin 42a has the shape of an involute curve IC2, which is the trajectory of the second belt 12 spirally winding around the cylindrical structure 13. Therefore, it is easy to insert the engaging pin 42a into the hole 11a of the first belt.

[0045] Furthermore, after inserting the engagement pin 42a into the hole 11a of the first belt, the engagement pin 42a is guided along the involute curve IC2 shape with its side surface 40a in contact with the inner circumferential surface of the hole 11a until the fitting portion 41 is fitted into the hole 11a of the first belt. This makes it easy to fit the engagement pin 42a into the hole 11a of the first belt. In addition, wear of the engagement pin 42a can be suppressed.

[0046] Here, the height of the engagement pin is changed according to the depth of the helical groove of the cylindrical structure. In the expandable device of the comparative example shown in Figure 3, the engagement pin 32a has a two-stage tapered shape, so if the height of the engagement pin is changed, the inclination of the side surface of the insertion part must be redesigned to match that height. In contrast, the engagement pin 42a in the expandable device according to Embodiment 2 shown in Figure 4(b) has the shape of an involute curve IC2, so even if the height of the engagement pin is changed, the slope of the side of the insertion part will be adjusted to match that height, eliminating the need for redesign.

[0047] <Variation> Next, with reference to Figure 5, we will describe the engagement pin 62a, which is a modified example of the engagement pin 42a. Figure 5 is a cross-sectional view showing the shape of a modified example of the engagement pin in the telescopic device according to Embodiment 2. In the following, in the insertion portion 60 of the engagement pin 62a, the cylindrical structure 13 side is considered the tip, and the fitting portion 61 side is considered the base.

[0048] As shown in Figure 5, the engaging pin 62a has an insertion portion 60 and a fitting portion 61. The insertion portion 60 is formed to protrude from the fitting portion 61. The fitting portion 61 is the same as the fitting portion 21 of the engaging pin 12a according to Embodiment 1, so its description is omitted. Also in Figure 5, the shape of the engaging pin 42a corresponding to Figure 4(b) is shown by a dotted line.

[0049] As shown in Figure 5, the inclination of the side surface 60a of the insertion portion 60 in the engaging pin 62a has the shape of an involute curve IC6. The involute curve IC6 has the same center as the cylindrical structure 13 and its base circle is a circle smaller than the diameter of the cylindrical structure 13. That is, the base circle of the involute curve IC6 is smaller than the base circle of the involute curve IC2.

[0050] As shown in Figure 5, the angle between the side surface 60a of the engaging pin 62a and the line parallel to the z-axis decreases towards the tip. In other words, the side surface 60a of the engaging pin 62a has a steep slope at the base and becomes gentler towards the tip.

[0051] Now, referring to Figure 5, we compare the shapes of the engaging pin 62a and the engaging pin 42a. The engaging pin 62a has the shape of an involute curve IC6, while the engaging pin 42a has the shape of an involute curve IC2. Therefore, compared to the engaging pin 42a, the engaging pin 62a has a steeper slope from the base to the tip of the insertion portion 60, and a smaller diameter in the z-axis direction of the tip. This makes it easier to insert the engaging pin 62a into the hole 11a of the first belt.

[0052] Thus, the expandable device according to Embodiment 2 has an involute curve shape in which the inclination of the side surface of the insertion portion has the same center as the cylindrical structure and the base circle is a circle whose diameter is less than or equal to that of the cylindrical structure. This makes it easy to insert the engagement pin into the hole 11a of the first belt.

[0053] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. [Explanation of Symbols]

[0054] 10 Telescopic part 11. The First Belt 12. The second belt 13. Cylindrical structure 20, 30, 40, 60 Insertion section 21, 31, 41, 61 Fitting parts 11a, 11b holes 12a, 12b, 32a, 42a, 62a Engaging pins 12e end 13c groove 20a, 30a, 40a, 60a side view A1, A2 angle C1, C2 center axis IC1, IC2, IC3, IC4, IC6 Involute curve

Claims

1. An expandable / contractable device comprising a first belt and a second belt wrapped around the outside of the first belt, which are wound spirally around a cylindrical structure, The second belt is equipped with an engagement pin having a fitting portion that fits into a hole in the first belt and an insertion portion that protrudes from the fitting portion and is inserted into a hole in the first belt. The fitting portion is cylindrical in shape and has a diameter corresponding to the hole in the first belt. The side surface of the insertion portion is inclined such that the diameter of the insertion portion decreases towards the tip. The inclination of the side surface of the insertion portion is an involute curve shape with a base circle having the same center as the cylindrical structure and having a diameter less than or equal to the diameter of the cylindrical structure. Telescopic device.

2. The diameter of the base circle is equal to the diameter of the cylindrical structure. The expandable device according to claim 1.

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