阅读说明：本技术 盘绕线绳和移位装置 (Coiled cord and displacement device ) 是由 糸泽祐太 古村博隆 于 2020-09-17 设计创作，主要内容包括：本发明涉及盘绕线绳和移位装置。本公开提供了一种盘绕线绳,该盘绕线绳能够增加线缆长度,同时防止盘绕线绳在自然状态下在与盘绕线绳伸缩的方向正交的平面中的缠绕直径增加。第一示例性方面是一种缠绕有线缆的盘绕线绳,该线缆能够自由伸缩,盘绕线绳包括：第一层,在该第一层中,线缆在径向方向上从盘绕线绳的内侧缠绕到盘绕线绳的外侧；以及第二层,在该第二层中,线缆在径向方向上从盘绕线绳的外侧缠绕到盘绕线绳的内侧,其中第一层和第二层彼此连续地连接。(The invention relates to a coiled cord and a displacement device. The present disclosure provides a coiled cord capable of increasing a cable length while preventing an increase in a winding diameter of the coiled cord in a plane orthogonal to a direction in which the coiled cord is stretched and contracted in a natural state. A first exemplary aspect is a coiled cord wound with a cable, the cable being freely retractable, the coiled cord comprising: a first layer in which the cable is wound in a radial direction from an inner side to an outer side of the coiled wire; and a second layer in which the cable is wound from an outer side to an inner side of the coiled wire rope in a radial direction, wherein the first layer and the second layer are continuously connected to each other.)

1. A coiled cord wrapped with a cable, the cable being freely retractable, the coiled cord comprising:

a first layer in which the cable is wound in a radial direction from an inner side of the coiled wire rope to an outer side of the coiled wire rope; and a second layer in which the cable is wound from an outer side of the coiled wire rope to an inner side of the coiled wire rope in the radial direction, wherein

The first layer and the second layer are continuously connected to each other.

2. The coiled wire rope according to claim 1, wherein when the direction in which the coiled wire rope is stretched is one axial direction, a plurality of cables are stacked and integrated in the direction in which the coiled wire rope is stretched.

3. The coiled wire rope of claim 1 or 2, wherein a direction in which the cable of the first layer is wound from an inner side of the coiled wire rope to an outer side of the coiled wire rope in the radial direction is the same as a direction in which the cable of the second layer is wound from the outer side of the coiled wire rope to the inner side of the coiled wire rope in the radial direction.

4. A coiled wire according to claim 1 or 2, wherein a direction in which the cable of the first layer is wound from an inner side of the coiled wire to an outer side of the coiled wire in the radial direction is different from a direction in which the cable of the second layer is wound from the outer side of the coiled wire to the inner side of the coiled wire in the radial direction.

5. A displacement device comprising a part to be displaced and configured to displace the part to be displaced relative to a base, wherein

The displacement device further comprises a coiled wire according to any of claims 1 to 4, which stretches in accordance with the displacement of the portion to be displaced.

6. The displacement device of claim 5, further comprising a limiting member that limits elongation of the coiled wire.

7. The displacement device of claim 6, wherein the restraining member connects a first portion of the cable in a predetermined layer of the coiled wire rope, the first portion being located at an inner side of the coiled wire rope in the radial direction, to a second portion of the cable in a layer different from the predetermined layer of the coiled wire rope, the second portion being located at the inner side of the coiled wire rope in the radial direction.

8. The displacement device according to claim 6 or 7, wherein the restriction member is located in an upper side portion of the coiled wire when the coiled wire is positioned such that one side of the coiled wire in a gravity direction is set as a lower side of the coiled wire.

9. The displacement device according to any one of claims 6 to 8, wherein the length of the restriction member is shorter when the restriction member is located at a position where the frequency of expansion and contraction of the coiled wire is higher.

Technical Field

The present disclosure relates to a coiled cord and a displacement device.

Background

A general coiled cord has a structure in which a cable is wound, is elongated when the cable is stretched, and is contracted in a natural state in which the cable is not stretched. For example, the coiled cord disclosed in japanese unexamined patent application publication No. 2001-351442 has a structure in which a cable is spirally wound in the same plane in a natural state. With this structure, the coiled cord disclosed in japanese unexamined patent application publication No. 2001-351442 can be accommodated in a flat accommodation space having a thickness of about the line width of the cable in a natural state.

Disclosure of Invention

However, the applicant has found the following problems. The coiled cord disclosed in japanese unexamined patent application publication No. 2001-351442 has a structure in which a cable is spirally wound in the same plane in a natural state, and this structure causes a problem that a winding diameter of the coiled cord in a plane orthogonal to a direction in which the coiled cord is stretched (i.e., a length of the coiled cord in a radial direction) becomes large.

The present disclosure has been made in view of the above problems, and provides a coiled wire and a displacement device capable of increasing the length of a cable while preventing an increase in the winding diameter of the coiled wire in a plane orthogonal to the direction in which the coiled wire stretches and contracts in a natural state.

A first exemplary aspect is a coiled cord wound with a cable, the cable being freely retractable, the coiled cord comprising:

a first layer in which the cable is wound from an inner side to an outer side of the coiled wire rope in a radial direction, and a second layer in which the cable is wound from the outer side to the inner side of the coiled wire rope in the radial direction, wherein

The first layer and the second layer are continuously connected to each other.

In such a coiled wire, since the cables are stacked in a plurality of layers in a nested structure, the length of each of the cables can be increased while preventing the winding diameter of the coiled wire in a natural state in a plane orthogonal to the direction in which the coiled wire is stretched and contracted from increasing, as compared with the coiled wire cable disclosed in japanese unexamined patent application publication No. 2001-351442.

In the above coiled wire, when the direction in which the coiled wire is stretched is one axial direction, a plurality of the cables may be stacked and integrated in the direction in which the coiled wire is stretched.

Thus, the cables tend to be bundled together to maintain the posture of the coiled wire in the direction in which the coiled wire is stretched and contracted, and thus the posture of the coiled wire in a natural state can be prevented from collapsing.

In the above coiled wire rope, a direction in which the cable of the first layer is wound from an inner side of the coiled wire rope to an outer side of the coiled wire rope in the radial direction may be the same as a direction in which the cable of the second layer is wound from the outer side of the coiled wire rope to the inner side of the coiled wire rope in the radial direction.

In the above coiled wire rope, a direction in which the cable of the first layer is wound from an inner side of the coiled wire rope to an outer side of the coiled wire rope in the radial direction may be different from a direction in which the cable of the second layer is wound from the outer side of the coiled wire rope to the inner side of the coiled wire rope in the radial direction.

Another exemplary aspect is a displacement device comprising a part to be displaced and configured to displace the part to be displaced relative to a base, wherein the displacement device further comprises the above-described coiled wire rope which is telescopic according to the displacement of the part to be displaced.

Such a displacement device can increase the length of the cable while preventing an increase in the winding diameter of the coiled wire in a plane orthogonal to the direction in which the coiled wire extends and contracts and the height of the coiled wire in the direction in which the coiled wire extends and contracts. Further, for example, in the case of a structure in which the coiled wire is housed inside the displacement device, it is possible to secure a large amount of displacement while reducing a housing space for the coiled wire.

In the above-described displacement device, the displacement device may further include a restricting member that restricts elongation of the coiled wire.

Thus, it is possible to reduce a local load on the cable and prevent the damage of the coiled cord.

In the above-described displacement device, the restricting member may connect a first portion of the cable in a predetermined layer of the coiled wire, the first portion being located at an inner side of the coiled wire in the radial direction, to a second portion of the cable in a layer different from the predetermined layer of the coiled wire, the second portion being located at the inner side of the coiled wire in the radial direction.

In the above-described displacement device, when the coiled wire is positioned such that one side of the coiled wire in the direction of gravity is set as the lower side of the coiled wire, the restriction member may be located in an upper side portion of the coiled wire.

Thus, it is possible to reduce a local load on the cable and prevent the damage of the coiled cord.

In the above-described displacement device, when the restriction member is located at a position where the expansion and contraction frequency of the coiled wire is high, the length of the restriction member may be short.

With this structure, the load can be distributed on the coiled wire. Therefore, it is possible to reduce a local load on the cable and prevent the coiled cord from being damaged.

According to the present disclosure, it is possible to provide a coiled cord and a displacement device capable of increasing the length of a cable while preventing an increase in the winding diameter of the coiled cord in a plane orthogonal to the direction in which the coiled cord is stretched and contracted in a natural state.

The above and other objects, features and advantages of the present disclosure will be more fully understood from the detailed description given below and the accompanying drawings, which are given by way of illustration only and thus should not be taken as limitations of the present disclosure.

Drawings

Fig. 1 is an enlarged perspective view of a portion of a coiled cord according to a first embodiment;

fig. 2 is an enlarged perspective view of a portion of another coiled cord according to the first embodiment;

fig. 3 is a diagram showing a stacked cable of coiled wires according to the first embodiment;

fig. 4 is a view showing a state where a displacement device to which a coiled wire according to the first embodiment is applied is contracted;

fig. 5 is a view showing a state in which a displacement device to which a coiled wire according to the first embodiment is applied is extended;

FIG. 6 is an enlarged view of a portion of a coiled cord including an elastic member;

fig. 7 is an enlarged perspective view of a portion of the coiled wire provided with the restricting member; and is

Fig. 8 is an enlarged perspective view of a portion of another coiled wire provided with a restricting member.

Detailed Description

Specific embodiments to which the present disclosure is applied will be described in detail below with reference to the accompanying drawings. However, the present disclosure is not limited to the embodiments shown below. Furthermore, the following description and drawings are simplified as appropriate for clarity of explanation.

< first embodiment >

First, the structure of the coiled cord according to this embodiment is described. Fig. 1 is an enlarged perspective view of a portion of a coiled cord according to the embodiment. Fig. 2 is an enlarged perspective view of a portion of another coiled cord according to the embodiment. Fig. 3 is a diagram showing a stacked cable of coiled wires according to the embodiment. Note that in fig. 1 to 3, the coiled cord is simplified. In the following description, it is assumed that the coiled wire is stretched in one axial direction for the sake of clarification of the description.

As shown in fig. 1, in the coiled cord 1, the cable 2 is wound so as to be stretchable, and, in a natural state where the cable 2 is contracted, a plurality of layers around which the cable 2 is wound are stacked to be continuously formed in a direction in which the coiled cord 1 is stretchable. Specifically, in the coiled cord 1, a first layer 3 in which the cable 2 is wound from the inside of the coiled cord 1 to the outside of the coiled cord 1 in the radial direction and a second layer 4 in which the cable 2 is wound from the outside of the coiled cord 1 to the inside of the coiled cord 1 in the radial direction are formed so as to be continuously connected to each other. Further, the first layer 3 and the second layer 4 are alternately located in a direction in which the coiled cord 1 is stretched.

For example, if the coiled cord 1 is positioned such that one side of the coiled cord 1 in the gravity direction is set as the lower side of the coiled cord 1, and the coiled cord 1 is stretched and contracted in the vertical direction, the cable 2 of the first layer 3 is wound counterclockwise in the radial direction from the inner side of the coiled cord 1 to the outer side of the coiled cord 1 when the coiled cord 1 is viewed from the upper side of the coiled cord 1. On the other hand, the cable 2 of the second layer 4 is wound counterclockwise in the radial direction from the outside of the coiled wire 1 to the inside of the coiled wire 1. Further, the end of the cable 2 of the first layer 3 located on the inner side of the coiled cord 1 in the radial direction is continuously formed with the end of the cable 2 of the second layer 4 located on the upper side of the first layer 3 located on the inner side of the coiled cord 1 in the radial direction, and the end of the cable 2 of the first layer 3 located on the outer side of the coiled cord 1 in the radial direction is continuously formed with the end of the cable 2 of the second layer 4 located on the lower side of the first layer 3 located on the outer side of the coiled cord 1 in the radial direction.

By repeatedly forming the above-described first layer 3 and second layer 4, the cable 2 of the coiled cord 1 has a so-called nested structure in which the cable 2 located on the inner side of the coiled cord 1 in the radial direction is accommodated in the inner side of the cable 2 located on the outer side of the coiled cord 1 in the radial direction in a natural state in which the coiled cord 1 is contracted.

Note that the direction in which the cable 2 is wound is not limited to the counterclockwise direction as described above, but may instead be the clockwise direction. Further, as shown in fig. 2, a direction in which the cable 2 of the first layer 3 is wound from the inside of the coiled cord 1 to the outside of the coiled cord 1 in the radial direction may be different from a direction in which the cable 2 of the second layer 4 is wound from the outside of the coiled cord 1 to the inside of the coiled cord 1 in the radial direction. Therefore, when the coiled wire 1 in which the winding direction of the cable 2 of the first layer 3 is different from the winding direction of the cable 2 of the second layer 4 is used as a power supply line, the generation of a magnetic field can be prevented.

The cable 2 is a wire. The cable 2 is, for example, a signal line or a power supply line, and includes a wire material such as a conductive member covered with an insulating resin. It should be noted that, as shown in fig. 3, a plurality of cables 2 may be stacked and integrated in a direction in which the coiled cord 1 is stretched and contracted, and detailed functions thereof will be described later. For example, in fig. 3, three cables 2 are stacked and integrated in a direction in which the coiled cord 1 is stretched and contracted, and each of the cables 2 is formed as a signal line, a power supply line, and a Local Area Network (LAN) line. However, the function of the cable 2 is not limited thereto. Further, the number of cables 2 to be stacked may be any number. Note that the cross-sectional shape of the cable 2 may be any one of a circle, an ellipse, and a polygon.

Next, a structure of a displacement device to which the coiled cord 1 according to this embodiment is applied is described. Fig. 4 is a diagram showing a state in which a displacement device to which a coiled wire according to the present embodiment is applied is contracted. Note that a portion of fig. 4 is an end view. The displacement device 11 comprises, for example, a base 12, a telescopic mechanism 13, a part to be displaced 14 and the coiled wire 1, and is a neck joint part of the robot.

The base 12 is, for example, a body part of a robot. The telescopic mechanism 13 constitutes, for example, a neck of the robot so that the neck can be extended and contracted. Specifically, the telescopic mechanism 13 includes, for example, a first cylindrical rod 13a, a second cylindrical rod 13b inserted into the first cylindrical rod 13a, and a third cylindrical rod 13c inserted into the second cylindrical rod 13 b.

The first cylindrical rod 13a substantially has a cylindrical shape, for example, and one end of the first cylindrical rod 13a is fixed to the base 12. Further, a protruding portion 13d protruding inward from the first cylindrical rod 13a is provided at the other end of the first cylindrical rod 13 a.

The second cylindrical rod 13b has substantially a cylindrical shape, for example, and the outer diameter of the second cylindrical rod 13b is smaller than the inner diameter of the first cylindrical rod 13 a. Further, a first projection 13e projecting outward from the second cylindrical rod 13b is provided at one end of the second cylindrical rod 13b, and a second projection 13f projecting inward from the second cylindrical rod 13b is provided at the other end of the second cylindrical rod 13 b.

The third cylindrical rod 13c has a substantially cylindrical shape, for example, and the outer diameter of the third cylindrical rod 13c is smaller than the inner diameter of the second cylindrical rod 13 b. Further, a protruding portion 13g protruding outward from the third cylindrical rod 13c is provided at one end of the third cylindrical rod 13 c.

Each of the above-described first, second, and third cylindrical rods 13a, 13b, and 13c is extended and contracted like a so-called extendable antenna by an actuator (not shown). However, the telescopic mechanism 13 may include a member capable of being telescopic, such as a bellows member, instead of a plurality of cylindrical rods. Further, the sectional shape of each of the cylindrical rods 13a, 13b, and 13c is not limited to a circle, but may be an ellipse or a polygon.

The portion to be displaced 14 is, for example, a head of a robot, and is fixed to the other end of the third cylindrical rod 13 c. The coiled wire 1 is accommodated inside the first, second, and third cylindrical rods 13a, 13b, and 13c of the telescopic mechanism 13. Further, one end of the coiled wire 1 is connected to the base 12, and the other end of the coiled wire 1 is connected to the portion 14 to be displaced.

Next, a description is given of a state in which the displacement device to which the coiled cord 1 according to the present embodiment is applied is contracted. As shown in fig. 4, when the displacement device 11 is contracted, the second cylindrical rod 13b is substantially housed inside the first cylindrical rod 13a, and the third cylindrical rod 13c is substantially housed inside the second cylindrical rod 13 b.

At this time, the coiled cord 1 is in a natural state in which the first layer 3 and the second layer 4 are stacked in a direction in which the coiled cord 1 is stretched. In the above-described coiled cord 1, since the cables 2 are stacked in a nested structure into a plurality of layers as described above, the length of each of the cables 2 can be increased as compared with the coiled cord cable disclosed in japanese unexamined patent application publication No. 2001-351442 while preventing the winding diameter of the coiled cord 1 in a plane orthogonal to the direction in which the coiled cord 1 is stretched and contracted from being increased in a natural state.

It should be noted that, for example, in a general coiled cord, a layer in which a cable is wound in a radial direction from an inner side of the coiled cord to an outer side of the coiled cord is continuously formed in a direction in which the coiled cord is stretched. Therefore, in order to continuously form the end portion of the cable of the corresponding layer on the outside of the coiled wire in the radial direction and the end portion of the cable of the adjacent layer on the inside of the coiled wire in the radial direction, it is necessary to provide a pull-back portion of the cable between these layers.

On the other hand, in the coiled cord 1 according to this embodiment, the positions where the cable 2 of the first layer 3 is continuously connected to the cable 2 of the second layer 4 are alternately positioned in the direction in which the coiled cord 1 is stretched. That is, when a predetermined position where the cable 2 of the first layer 3 is continuously connected to the cable 2 of the second layer 4 is located outside the coiled wire 1, a position where the adjacent cable 2 of the first layer 3 is continuously connected to the cable 2 of the second layer 4 is located inside the coiled wire 1. This construction eliminates the need to provide a cable pull back between the layers like a conventional coiled cord.

Therefore, it is possible to increase the length of the cable 2 while preventing the height of the coiled wire 1 in the direction in which the coiled wire 1 is stretched from increasing and decreasing the accommodation space inside the stretching mechanism 13 that accommodates the coiled wire 1. It should be noted that, in the case where the plurality of cables 2 are stacked and integrated in the direction in which the coiled cord 1 is stretched and retracted as described above, the cables tend to be bundled together to maintain the posture of the coiled cord 1 in the direction in which the coiled cord 1 is stretched and retracted, and therefore the posture of the coiled cord 1 in a natural state can be prevented from collapsing.

Next, a description is given of a state in which the displacement device to which the coiled cord 1 according to the present embodiment is applied is elongated. Fig. 5 is a diagram showing a state in which a displacement device to which a coiled wire according to the present embodiment is applied is extended. Note that a portion of fig. 5 is an end view. As shown in fig. 5, when the actuator of the telescopic mechanism 13 is operated, the second cylindrical rod 13b protrudes from the first cylindrical rod 13a, the third cylindrical rod 13c protrudes from the second cylindrical rod 13b, and the telescopic mechanism 13 is extended, whereby the coiled wire rope 1 is extended in accordance with the displacement of the portion 14 to be displaced.

At this time, in the coiled wire 1, since the position where the cable 2 of the first layer 3 is continuously connected to the cable 2 of the second layer 4 is alternately positioned in the direction in which the coiled wire 1 is stretched, the coiled wire 1 can be smoothly stretched in the direction in which the stretching mechanism 13 is stretched.

Further, in the extended state of the telescopic mechanism 13, the protruding portion 13d of the first cylindrical rod 13a comes into contact with the first protruding portion 13e of the second cylindrical rod 13b, whereby the second cylindrical rod 13b can be prevented from coming off the first cylindrical rod 13 a. Similarly, the second projecting portion 13f of the second cylindrical rod 13b comes into contact with the projecting portion 13g of the third cylindrical rod 13c, whereby the third cylindrical rod 13c can be prevented from coming off the second cylindrical rod 13 b.

When the actuator of the telescopic mechanism 13 is operated in a state where the displacement means 11 is extended as described above and the displacement means 11 is contracted such that the first cylindrical rod 13a, the second cylindrical rod 13b and the third cylindrical rod 13c substantially overlap each other as shown in fig. 4, the coiled wire rope 1 is contracted in accordance with the displacement of the portion 14 to be displaced.

At this time, in the coiled wire 1, since the position where the cable 2 of the first layer 3 is continuously connected to the cable 2 of the second layer 4 is alternately positioned in the direction in which the coiled wire 1 is contracted and contracted, the coiled wire 1 can be smoothly contracted in the direction in which the contraction and contraction mechanism 13 is contracted.

As described above, in the coiled cord 1, since the cables 2 are stacked in a nested structure into a plurality of layers, the length of each of the cables 2 can be increased as compared with the coiled cord cable disclosed in japanese unexamined patent application publication No. 2001-351442 while preventing the winding diameter of the coiled cord 1 in a plane orthogonal to the direction in which the coiled cord 1 is stretched and contracted from being increased in a natural state. Further, in the coiled cord 1, the position where the cable 2 of the first layer 3 is continuously connected to the cable 2 of the second layer 4 is alternately located in the direction in which the coiled cord 1 is stretched and contracted, and it is not necessary to provide a pull-back portion of the cable like the ordinary coiled cord between the layers, whereby the length of the cable 2 can be increased while preventing the height of the coiled cord 1 in the direction in which the coiled cord 1 is stretched and contracted from increasing and decreasing the accommodation space inside the stretching mechanism 13 accommodating the coiled cord 1.

Therefore, the displacement device 11 to which the coiled cord 1 is applied can increase the length of the cable 2 while preventing an increase in the winding diameter of the coiled cord 1 in a plane orthogonal to the direction in which the coiled cord 1 extends and contracts and the height of the coiled cord 1 in the direction in which the coiled cord 1 extends and contracts, thereby enabling a large displacement amount to be secured while reducing the accommodation space for the coiled cord 1.

As shown in fig. 6, the coiled cord 1 may include an elastic member 5, and the elastic member 5 exhibits restoring force when the elongated coiled cord 1 is contracted to a natural state. The elastic member 5 is, for example, an elastically deformable resin or metal wire, and the elastic member 5 is formed in a shape corresponding to the cable 2 around which the cord 1 is wound in a natural state, and may be provided on the surface or inside the cable 2. Therefore, the extended coiled cord 1 may be smoothly restored to a natural state.

< second embodiment >

For example, when the displacement direction of the displacement device 11 is the vertical direction, the upper side portion of the coiled wire 1 is strongly stretched and the load on the upper side portion of the coiled wire 1 is large. Thus, for example, as shown in fig. 7, a first portion 2a of the cable 2 in a predetermined layer at an upper portion of the coiled wire 1, which is located on the inner side of the coiled wire 1 in the radial direction, and a second portion 2b of the cable 2 in a layer different from the predetermined layer, which is located on the inner side of the coiled wire 1 in the radial direction, may be connected to each other by the restriction member 21. That is, the displacement device 11 may include the restricting member 21.

The restraining member 21 is, for example, a deformable and hardly stretchable member, such as a string or a chain, and one end of the restraining member 21 may be connected to the first portion 2a of the cable 2 by a connecting means such as an adhesive, and the other end of the restraining member 21 is connected to the second portion 2b of the cable 2 by a connecting means such as an adhesive, while the restraining member 21 is inserted into the coiled cord 1. Thus, it is possible to reduce a local load on the cable 2 and prevent the coiled cord 1 from being damaged.

As shown in fig. 8, the restriction member 21 may be provided at a plurality of positions in the coiled cord 1. In this case, when the restriction member 21 is located at a position where the expansion and contraction frequency of the coiled cord 1 is higher, the length of the restriction member 21 may be shorter. For example, when the displacement direction of the displacement device 11 is the vertical direction, the length of the restriction member 21 may be shorter when the restriction member 21 is located on the upper side of the coiled wire 1. With this structure, the load can be distributed on the coiled cord 1. As a result, it is possible to reduce a local load on the cable 2 and prevent the coiled cord 1 from being damaged.

Note that the restricting member 21 may be provided at any position in the coiled cord 1, and may be provided at a position where the expansion and contraction frequency due to the displacement of the displacement device 11 is high. Further, the restricting member 21 is not limited to an adhesion means such as an adhesive, and may be fixed to the cable 2 by a fixing means such as a jig. In short, the means for connecting the restricting member 21 to the cable 2 is not limited.

The present disclosure is not limited to the above-described embodiments, and may be appropriately modified without departing from the spirit of the present disclosure.

For example, although the displacement device 11 according to the foregoing embodiment is configured to be telescopic in one axial direction, the coiled wire cord 1 may be used like an arm joint of a robot if the displacement device 11 is configured to be flexed and extended. Further, the displacement device 11 is not limited to being used as part of a robot, but may be used as part of a production machine or the like.

For example, although the coiled cord 1 according to the foregoing embodiment includes a plurality of first layers 3 and second layers 4 alternately stacked thereon, it may include at least the first layers 3 and the second layers 4. Further, the first layer 3 and the second layer 4 may be located in a portion of the coiled cord.

From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.