Tension balancer

Abstract

To provide a lightweight spring-type tension balancer.SOLUTION: A tension balancer comprises first to n-th cylindrical members, first to (n-1)-th coil springs, a rear hook attached to the first cylindrical member, a front hook attached to the n-th cylindrical member, first to (n-1)-th front spring washers and first to (n-1)-th rear spring washers, and a stopper fixed to the first cylindrical member. The first cylindrical member contains aluminum as a main component. The second to n-th cylindrical members contain iron as a main component. Details of these configurations are described in the specification.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a tension balancer that can be used for overhead lines.

Background Art

[0002] A tension balancer is attached to an overhead line such as a railway. For example, Patent Documents 1 and 2 disclose a spring-type tension balancer having a plurality of cylindrical members arranged coaxially and a coil spring arranged between the cylindrical members as a basic configuration. One end of the spring-type tension balancer is fixed to a support column, and the other end is connected to an overhead line. The coil spring is built into the tension balancer in a compressed state, and by utilizing the elastic force with which the spring tries to return to its original length, the overhead line can be pulled with an appropriate tension, and the overhead line can always be arranged substantially horizontally even when expansion and contraction due to temperature changes occur.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] One of the problems of the embodiments of the present invention is to provide a tension balancer having a novel structure. Alternatively, one of the problems of the embodiments of the present invention is to provide a spring-type tension balancer that is lightweight and does not impose a large load on the support column for fixing the tension balancer.

Means for Solving the Problems

[0005] One embodiment of the present invention is a tension balancer. The tension balancer includes first to nth cylindrical members, first to (n - 1) coil springs, a rear hook attached to the first cylindrical member, a front hook attached to the nth cylindrical member, first to (n - 1) front spring washers and first to (n - 1) rear spring washers, and a stopper fixed to the first cylindrical member. The first to nth cylindrical members are arranged such that a (m + 1)th cylindrical member selected from the first to nth cylindrical members is located within an mth cylindrical member selected from the first to nth cylindrical members. The first to (n - 1) coil springs are arranged such that an mth coil spring selected from the first to (n - 1) coil springs is sandwiched between the mth cylindrical member and the (m + 1)th cylindrical member. The first to (n - 1) front spring washers and the first to (n - 1) rear spring washers are arranged such that an mth front spring washer selected from the first to (n - 1) front spring washers and an mth rear spring washer selected from the first to (n - 1) rear spring washers surround the (m + 1)th cylindrical member and sandwich the mth coil spring in a direction parallel to the coil axis of the mth coil spring. The stopper is arranged such that the first front spring washer is sandwiched between the first coil spring and the stopper in the above direction. The first cylindrical member contains aluminum as a main component. The second to nth cylindrical members contain iron as a main component. n is selected from natural numbers of 2 or more and 5 or less, and m is a variable selected from natural numbers of 1 or more and (n - 1) or less.

Brief Description of the Drawings

[0006]

Figure 1

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Embodiments for Carrying Out the Invention

[0007] Hereinafter, each embodiment of the invention disclosed in this application will be described with reference to the drawings. However, the present invention can be implemented in various forms without departing from the gist thereof, and is not to be construed as being limited to the description of the embodiments exemplified below.

[0008] The drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual aspect for clearer explanation, but this is merely an example and does not limit the interpretation of the present invention. Also, in this specification and each figure, elements having the same functions as those already described with respect to the previously shown figures may be denoted by the same reference numerals, and redundant explanations may be omitted.

[0009] In this specification and the claims, the expression "a structure is exposed from another structure" means a mode in which a part of a structure is not covered by another structure, and the part not covered by this other structure includes a mode in which it is covered by yet another structure. Also, the mode represented by this expression includes a mode in which a structure is not in contact with another structure.

[0010] Hereinafter, the tension balancer 100, which is one embodiment of the present invention, will be described. The tension balancer 100 can be used to tension an overhead line with an appropriate tension.

[0011] 1. Overall Structure FIG. 1 shows a schematic perspective view of the tension balancer 100. The tension balancer 100 includes a plurality of cylindrical members arranged coaxially and having different outer diameters. The tension balancer 100 shown in FIG. 1 is a two-stage tension balancer and includes a first cylindrical member 120, a second cylindrical member 130, and a third cylindrical member 140. Although the tension balancer 100 shown in FIG. 1 has three cylindrical members, there is no restriction on the number of cylindrical members, for example, it may be 2 or more and 5 or less, or even 5 or more. In the tension balancer 100, a part of a cylindrical member having a smaller outer diameter is inserted into a cylindrical member having a larger outer diameter. Generally speaking, the tension balancer 100 has cylindrical members from the first to the nth (n is a natural number of 2 or more), and the outer diameters of the cylindrical members decrease in order from the first cylindrical member to the nth cylindrical member. The (m + 1)th (m is a variable selected from natural numbers of 1 or more and (n - 1) or less) cylindrical member is arranged so as to be surrounded by the mth cylindrical member, and the (m + 1)th cylindrical member slides reversibly inside the mth cylindrical member in the direction of the central axis of each cylindrical member. Hereinafter, the description will continue using the two-stage tension balancer 100 (that is, the tension balancer with n being 3).

[0012] At one end of the first cylindrical member 120 having the maximum outer diameter, a support-side attachment member (hereinafter referred to as a rear hook) 110 is directly or indirectly attached. By using this rear hook 110, the tension balancer 100 can be connected to a structure such as a support column. As an optional configuration, a clamp (not shown) for suspending the tension balancer 100 may be provided. On the other hand, at one end of a cylindrical member having the minimum outer diameter (here, the third cylindrical member 140), an overhead line-side attachment member (hereinafter referred to as a front hook) 150 connected to the overhead line is directly or indirectly attached. As will be described later, a coil spring is disposed in a compressed state between adjacent cylindrical members, and a plurality of cylindrical members and a plurality of coil springs alternate with each other. Due to the elastic force that the coil spring attempts to extend, a force is generated that causes the outer cylindrical member to draw the adjacent inner cylindrical member inward. By this force, the overhead line can be tensioned with an appropriate tension.

[0013] Hereinafter, the length direction of the tension balancer 100 is defined as the x direction, and when the tension balancer 100 is installed such that the x direction is horizontal, the vertical direction is defined as the z direction. The direction orthogonal to the x direction and the z direction is defined as the y direction. The x direction is parallel to the central axis of the tension balancer 100 and each cylindrical member, and is the direction in which the second to the nth cylindrical members slide. Also, the sides where the front hook 150 and the rear hook 110 are provided are defined as the front and rear of the tension balancer 100, respectively.

[0014] 2. Cylindrical Member Fig. 2 shows a schematic view of the end face along the chain line A-A' extending in the x direction of Fig. 1. As shown in Fig. 2, the second cylindrical member 130 and the third cylindrical member 140 are arranged in the first cylindrical member 120 in the order of decreasing inner diameter, and coil springs (the first coil spring 128 and the second coil spring 138) are arranged between adjacent cylindrical members. At one end behind the first cylindrical member 120, a first back plate 104 forming the bottom surface of the first cylindrical member 120 can be provided. The rear hook 110 may be attached to the first back plate 104 by welding or bolting, or may be fixed to the first cylindrical member 120 without passing through the first back plate 104. Also, although not shown, the first cylindrical member 120 may be provided with an opening for discharging the water that has entered inside. At one end behind the first cylindrical member 120, a dropout prevention mechanism is further provided that cooperates with the first back plate 104 to prevent the second cylindrical member 130 and the third cylindrical member 140 from dropping out. There is no restriction on the structure of the dropout prevention mechanism. In the example shown in Figs. 1 and 2, a U-shaped rod 106 is provided as the dropout prevention mechanism. The U-shaped rod 106 has a pair of legs extending in a direction perpendicular to the z direction passing through the first cylindrical member 120, and the collar 108 provided at its end prevents the U-shaped rod 106 from dropping out. The first coil spring 128 provided between the first cylindrical member 120 and the second cylindrical member 130, and the second coil spring 138 provided between the second cylindrical member 130 and the third cylindrical member 140 are both arranged in a compressed state. For this reason, the second cylindrical member 130 and the third cylindrical member 140 push the first back plate 104 backward by the elastic force trying to return to their original lengths. However, their movement is restricted by the U-shaped rod 106 and the first back plate 104, preventing the second cylindrical member 130 and the third cylindrical member 140 from dropping out.

[0015] The first cylindrical member 120 contains aluminum as a main component. That is, the first cylindrical member 120 is made of aluminum or an aluminum alloy. More specifically, the first cylindrical member 120 contains 90% or more and 100% or less of aluminum. The first cylindrical member 120 may contain elements other than aluminum, such as zinc, magnesium, copper, manganese, and silicon. For example, the first cylindrical member 120 may contain aluminum with a purity of 99% or more, which can be said to be substantially pure aluminum, or an alloy containing aluminum, zinc, magnesium, and copper, such as those called A7072, A7050, A7075, A7N01, etc., an alloy of aluminum and magnesium containing silicon, such as those called A6061, A6063, A6N01, etc., an alloy of aluminum and magnesium exemplified by A5052, A5056, A5083, A5454, etc., aluminum added with silicon exemplified by A4032, A4043, etc., or an alloy of aluminum and manganese exemplified by A3003, A3005, A3105, etc.

[0016] On the other hand, both the second cylindrical member 130 and the third cylindrical member 140 contain iron as a main component. More specifically, both the second cylindrical member 130 and the third cylindrical member 140 are made of iron, stainless steel, or invar. In the case of iron, the second cylindrical member 130 and the third cylindrical member 140 contain 98% or more and 100% or less of iron, and may contain 0.1% or more and 1% or less of carbon as an impurity. Typically, iron such as SS400 is used. In the case of stainless steel, in addition to iron, nickel, molybdenum, carbon, etc. may be further contained. For example, austenitic stainless steel, austenitic-ferritic stainless steel, ferritic stainless steel, or martensitic stainless steel may be used. In the case of invar, manganese and carbon may be contained together with iron. Also, the surfaces of the second cylindrical member 130 and the third cylindrical member 140 may be covered with a metal coating such as zinc or aluminum.

[0017] 3. Front spring washer, rear spring washer, and coil spring In front of the tension balancer 100, that is, on the side of the front hook 150, a ring-shaped first front spring washer 122 sandwiched between the first cylindrical member 120 and the second cylindrical member 130 and surrounding the second cylindrical member 130 is provided. The first front spring washer 122 closes a part of the first cylindrical member 120, and its opening serves as an opening for the second cylindrical member 130 to slide within the first cylindrical member 120 and partially expose from the first cylindrical member 120.

[0018] Similar to the first cylindrical member 120, the first front spring washer 122 may also contain aluminum as the main component, or may contain iron as the main component. The first front spring washer 122 is not fixed to the first cylindrical member 120 or the second cylindrical member 130. More specifically, the first front spring washer 122 is not fixed to the first cylindrical member 120 or the second cylindrical member 130 using welding, diffusion bonding, or fixtures such as screws and bolts. Therefore, when the elastic force of the first coil spring 128 does not exist, the first front spring washer 122 can move in the space between the first cylindrical member 120 and the second cylindrical member 130. For this reason, a stopper for preventing dropout is provided so that the first front spring washer 122 does not move forward and drop off. The stopper is arranged such that the first front spring washer 122 is sandwiched between the stopper and the first coil spring 128 in a direction parallel to the coil axis of the first coil spring 128. There are no restrictions on the configuration of the stopper, but for example, as shown in FIG. 2 and FIG. 3 which is a schematic perspective view of the tension balancer 100 seen from the front, the stopper can include a plurality of bolts 124. In this case, the bolt 124 passes through a through hole provided in the first cylindrical member 120, and its head portion functions as a stopper.

[0019] There is no restriction on the number of bolts 124, but it is preferably 3 or more and 8 or less, for example, 6. As will be described later, since the first front spring washer 122 is pushed forward by the elastic force of the compressed first coil spring 128, it is preferable that the first front spring washer 122 can evenly resist this elastic force. Therefore, it is preferable to symmetrically arrange the plurality of bolts 124. More specifically, when the number of bolts 124 is k (k is a natural number of, for example, 3 or more and 8 or less), the k bolts 124 are located on a plane perpendicular to the coil axis of the first coil spring 128, and are preferably arranged at the vertices of this planar virtual regular k-gon.

[0020] As can be understood from FIGS. 2 and 3, when the stopper includes the bolt 124, the head portion of the bolt 124 is located inside the first cylindrical member 120, and the bolt 124 is fixed to the first cylindrical member 120 by the nut 126. As shown in FIG. 4, the shape of the head portion of the bolt 124 (the shape of the plane perpendicular to the axial direction of the bolt 124) is, for example, a polygon (or a polygon with rounded corners, the same hereinafter), and it is preferable to arrange the straight portion 124a so as to be parallel to the main surface of the first front spring washer 122. By adopting this arrangement, damage to the first front spring washer 122 caused by contact with the head portion of the bolt 124 can be suppressed. The shape of the head portion is not limited to a regular polygon, and as shown in FIG. 5, it may have straight portions 124a and 124b with different lengths. In this case, either the straight portion 124a or 124b, preferably the longer straight portion 124a, is arranged so as to be parallel to the main surface of the first front spring washer 122.

[0021] On one side, at one end on the rear side of the tension balancer 100, a ring-shaped first rear spring washer 134 sandwiched between the first cylindrical member 120 and the second cylindrical member 130 and surrounding the second cylindrical member 130 is provided. The first rear spring washer 134 is fixed to the second cylindrical member 130. The first rear spring washer 134 mainly contains iron. The first rear spring washer 134 may have the same or substantially the same composition as the second cylindrical member 130. Therefore, the first rear spring washer 134 can be firmly and easily fixed to the second cylindrical member 130 by welding. However, the first rear spring washer 134 is not fixed to the first cylindrical member 120 and slides relative to the first cylindrical member 120 together with the second cylindrical member 130. In the example shown in FIG. 2, the first rear spring washer 134 is provided on the outer peripheral surface (the surface on the first cylindrical member 120 side) of the second cylindrical member 130 so as to surround the second cylindrical member 130. However, as shown in FIG. 6, the first rear spring washer 134 does not have to surround the second cylindrical member 130. In this case, a first rear spring washer 134 having an inner diameter equal to or less than the inner diameter of the second cylindrical member 130 and an outer diameter larger than the outer diameter of the second cylindrical member 130 is provided at the end of the second cylindrical member 130. Further, the first rear spring washer 134 may be integrated with the second cylindrical member 130.

[0022] The first coil spring 128 surrounds the second cylindrical member 130 and is disposed between the first front spring washer 122 and the first rear spring washer 134 in the space between the first cylindrical member 120 and the second cylindrical member 130. Therefore, the compressed first coil spring 128 pushes the first front spring washer 122 and the first rear spring washer 134 in opposite directions by the elastic force that tries to extend. The relative position of the first front spring washer 122 with respect to the first cylindrical member is fixed by a stopper, and the first rear spring washer 134 is fixed to the second cylindrical member 130. As a result, a force for pulling the second cylindrical member 130 into the first cylindrical member 120 is generated by the elastic force of the first coil spring 128. Thereby, tension can be applied to the overhead line connected to the front hook 150. The first coil spring 128 also mainly contains iron and may contain carbon, nickel, cobalt, etc. as sub-components.

[0023] Similar to the first front spring washer 122, a ring-shaped second front spring washer 132 is also provided between the second cylindrical member 130 and the third cylindrical member 140. The second front spring washer 132 is surrounded by the second cylindrical member 130 and closes a part of the second cylindrical member 130. Therefore, the opening of the second front spring washer 132 serves as an opening for the third cylindrical member 140 to slide within the second cylindrical member 130 and partially expose from the second cylindrical member 130. However, unlike the first front spring washer 122, the second front spring washer 132 is fixed to the second cylindrical member 130. Also, the second front spring washer 132 may contain iron as a main component and have the same or substantially the same composition as the second cylindrical member 130. For this reason, the second front spring washer 132 can be firmly and easily fixed to the second cylindrical member 130 by welding. In the example shown in FIG. 2, the second front spring washer 132 is fixed to the inner peripheral surface (the surface on the side of the third cylindrical member 140) of the second cylindrical member 130. However, as shown in FIG. 6, a second front spring washer 132 having an outer diameter equal to or less than the outer diameter of the second cylindrical member 130 and an inner diameter smaller than the inner diameter of the second cylindrical member 130 may be provided at the end of the second cylindrical member 130. Also, the second front spring washer 132 may be integrated with the second cylindrical member 130.

[0024] Similar to the first rear spring washer 134, a ring-shaped second rear spring washer 144 that is sandwiched between the second cylindrical member 130 and the third cylindrical member 140 and surrounds the third cylindrical member 140 is provided behind the tension balancer 100. The second rear spring washer 144 is fixed to the third cylindrical member 140. The second rear spring washer 144 also contains iron as a main component and may have the same or substantially the same composition as the third cylindrical member 140. Therefore, the second rear spring washer 144 can be firmly and easily fixed to the third cylindrical member 140 by welding. However, the second rear spring washer 144 is not fixed to the second cylindrical member 130 and slides relative to the second cylindrical member 130 together with the third cylindrical member 140. Similar to the first rear spring washer 134, the second rear spring washer 144 does not have to surround the third cylindrical member 140. In this case, a second rear spring washer 144 having an inner diameter equal to or less than the inner diameter of the third cylindrical member 140 and an outer diameter larger than the outer diameter of the third cylindrical member 140 may be provided at the end of the third cylindrical member 140 (FIG. 6). Also, the second rear spring washer 144 may be integrated with the third cylindrical member 140.

[0025] Similar to the first coil spring 128, the second coil spring 138 also surrounds the third cylindrical member 140 and is disposed between the second front spring washer 132 and the second rear spring washer 144 in the space between the second cylindrical member 130 and the third cylindrical member 140. Therefore, the second front spring washer 132 and the second rear spring washer 144 are pushed out in opposite directions by the elastic force of the compressed second coil spring 138 trying to extend. Since the second front spring washer 132 and the second rear spring washer 144 are fixed to the second cylindrical member 130 and the third cylindrical member 140, respectively, a force is generated by the elastic force of the second coil spring 138 to pull the third cylindrical member 140 into the second cylindrical member 130. Thereby, tension can be applied to the overhead line connected to the front hook 150.

[0026] When the second cylindrical member 130 and the third cylindrical member 140 slide relative to the first cylindrical member 120, the first coil spring 128 and the second coil spring 138 expand and contract. At this time, the first coil spring 128 and the second coil spring 138 rotate about the x-axis, and as a result, the second cylindrical member 130 and the third cylindrical member 140 may also rotate. Therefore, as an optional configuration, a second back plate 154 having a slit is provided on the rear side of the tension balancer 100 so as to block a part of the third cylindrical member 140, and a plate-shaped guide plate 152 passing through the slit of the second back plate 154 may be arranged. In this case, the guide plate 152 may function as a rear hook 110, or the rear hook 110 may be fixed to the end of the guide plate 152. By providing the second back plate 154 having a slit and the plate-shaped guide plate 152 passing through this slit, the rotation of the third cylindrical member 140 located innermost is prevented, so that the rotation of the cylindrical member (here, the second cylindrical member 130) located between the first cylindrical member 120 and the cylindrical member having the minimum diameter (here, the third cylindrical member 140) can also be restricted.

[0027] As described above, the tension balancer 100 has a plurality of cylindrical members and can pull the overhead line by a plurality of built-in coil springs. Further, the outermost cylindrical member of the tension balancer 100, that is, the first cylindrical member 120, contains aluminum as a main component, unlike the other cylindrical members (in the above example, the second cylindrical member 130 and the third cylindrical member 140). Therefore, the tension balancer 100 can be lightened. In fact, the inventors have confirmed that in the two-stage tension balancer 100, it is possible to reduce the weight by 10% or 15% or more compared with a tension balancer having a first cylindrical member made of iron. Therefore, by applying the embodiment of the present invention, a high strength is not required for the structure for attaching the tension balancer 100. For this reason, it becomes possible to install a tension balancer that is lightweight and low-cost.

[0028] Also, unlike the case of joining or fixing iron by welding, welding aluminum requires advanced techniques. Specifically, unlike iron, an aluminum oxide film with a high melting point is formed on the surface of aluminum, which needs to be removed before welding. In addition, aluminum has a low melting point and a high thermal conductivity, so it is prone to thermal distortion. Furthermore, due to the water of crystallization contained in the aluminum oxide film and the moisture in the atmosphere, hydrogen tends to remain in the molten aluminum. When welding is completed, due to the high thermal conductivity, the temperature of aluminum drops rapidly and solidifies. At this time, if hydrogen remains in the aluminum, cavities are formed by the hydrogen, and as a result, welding cracks may occur. Such technical difficulties cause a decrease in manufacturing yield and an increase in cost.

[0029] However, as described above, in the tension balancer 100, unlike the second cylindrical member 130 and the third cylindrical member 140, welding treatment for the first cylindrical member 120 is unnecessary. For example, the first front spring washer 122 is not joined or fixed to the first cylindrical member 120, and its relative position with the first cylindrical member 120 is only fixed by a stopper. Also, the machining accuracy of the first cylindrical member 120, the first front spring washer 122, and the stopper is determined by machining accuracy rather than welding accuracy. Considering that it is difficult to obtain high machining accuracy in aluminum welding, by applying the embodiment of the present invention, a lightweight tension balancer can be provided at low cost without requiring advanced welding techniques.

[0030] Further, a first cylindrical member 120 containing aluminum as a main component occupies most of the outermost surface of the tension balancer 100. As described above, since an aluminum oxide film is formed on the surface of aluminum by oxidation with oxygen in the atmosphere, the tension balancer 100 can have high weather resistance without forming a metal film by plating or the like. Further, since the formation of surface irregularities due to plating can be avoided, the friction between the first cylindrical member 120 and the first coil spring 128 can be reduced, and as a result, the hysteresis in the stroke-tension characteristics can be reduced. In addition, since there is no need to provide a metal film, the coloring of the outer peripheral surface of the first cylindrical member 120 can be easily performed.

[0031] 4. Modification The configuration of the tension balancer 100 according to the embodiment of the present invention is not limited to the above-described configuration, and various modifications are possible. Hereinafter, modifications will be described. Also in the modifications described below, since the first cylindrical member 120 contains aluminum as a main component, the above-described effects can be exhibited.

[0032] (1) First front spring washer As described above, when the coil spring incorporated in the tension balancer 100 expands and contracts, a force that rotates about the x-direction acts on the coil spring. For example, when the first coil spring 128 rotates, the first front spring washer 122 pressed by the first coil spring 128 also rotates, and as a result, the first front spring washer 122 and the stopper may be damaged due to friction with the stopper. Therefore, even if the first coil spring 128 rotates, the first front spring washer 122 may be configured so as not to rotate. For example, as shown in the end view (FIG. 8) along FIG. 7 and its chain curve B-B', a plurality of protrusions 122a protruding forward may be provided on the front side surface (the side opposite to the first coil spring 128) of the first front spring washer 122. The plurality of protrusions 122a are provided in the same number as the bolts 124, and are configured such that one bolt 124 is accommodated between two adjacent protrusions 122a. Thereby, the protrusions 122a interfere with the bolts 124, and as a result, rotation of the first front spring washer 122 (see the solid line arrow) can be prevented.

[0033] (2) Number of cylindrical members As described above, there is no restriction on the number of cylindrical members, and the tension balancer 100 may be, for example, a three-stage tension balancer. In this case, as shown in FIG. 9, a fourth cylindrical member 160 having an outer diameter smaller than the inner diameter of the third cylindrical member 140 is disposed within the third cylindrical member 140, and a third coil spring 148 surrounding the fourth cylindrical member 160 is disposed between the third cylindrical member 140 and the fourth cylindrical member 160. Further, a third front spring washer 142 fixed to the inner peripheral surface of the third cylindrical member 140 and a third rear spring washer 164 fixed to the outer peripheral surface of the fourth cylindrical member 160 are provided. The fourth cylindrical member 160, the third front spring washer 142, and the third rear spring washer 164 can contain iron as a main component. Therefore, the third front spring washer 142 and the third rear spring washer 164 can be firmly and easily fixed to the third cylindrical member 140 and the fourth cylindrical member 160, respectively, by welding. The fourth cylindrical member 160, the third front spring washer 142, and the third rear spring washer 164 can each have the same configuration as the third cylindrical member 140, the second front spring washer 132, and the second rear spring washer 144, and thus a detailed description thereof will be omitted.

[0034] Thus, there is no restriction on the number of stages of the tension balancer 100, that is, the number of cylindrical members. Therefore, generally speaking, as described above, the first to nth cylindrical members are arranged such that a (m + 1)th cylindrical member selected from the first to nth cylindrical members is positioned within an mth cylindrical member selected from the first to nth cylindrical members. Further, the first to (n - 1)th coil springs are arranged such that an mth coil spring selected from the first to (n - 1)th coil springs is sandwiched between the mth cylindrical member and the (m + 1)th cylindrical member. Furthermore, the first to (n - 1)th front spring washers and the first to (n - 1)th rear spring washers are arranged such that an mth front spring washer selected from the first to (n - 1)th front spring washers and an mth rear spring washer selected from the first to (n - 1)th rear spring washers surround the (m + 1)th cylindrical member and sandwich the mth coil spring in a direction parallel to the coil axis of the mth coil spring.

[0035] (3) Stopper As described above, there are no restrictions on the configuration of the stopper. Any configuration can be adopted as long as it prevents the first front spring washer 122 from falling forward and allows one or more cylindrical members arranged within the first cylindrical member 120 to slide and partially protrude from the first cylindrical member 120. Therefore, for example, as shown in FIGS. 10 and 11, a member (U-shaped bar) 112 having a U-shape may be used as the stopper. The U-shaped bar 112 has a pair of legs 112a extending in the z direction, each of which penetrates the first cylindrical member 120 twice, and although the pair of legs 112a overlap the first front spring washer 122 in the x direction, they are arranged so as not to overlap the cylindrical members (in the example shown in FIG. 1, the second cylindrical member 130 and the third cylindrical member 140) arranged within the first cylindrical member 120. Collars 114 for preventing detachment are provided on the pair of legs 112a of the U-shaped bar 112.

[0036] When using the U-shaped bar 112, as shown in FIG. 12, a pair of grooves 122b capable of accommodating the pair of legs 112a may be provided on the surface of the first front spring washer 122 as a mechanism for preventing the rotation of the first front spring washer 122. The grooves 122b are provided on the surface opposite to the first coil spring 128.

[0037] (4) Insulating film As described above, in the tension balancer 100, the outermost first cylindrical member 120 contains aluminum as a main component. On the other hand, components other than the first cylindrical member 120, for example, the first coil spring 128 and the first rear washer 134 that come into contact with the first cylindrical member 120, contain iron as a main component. Therefore, there is a difference in ionization tendency between the elements contained between the first cylindrical member 120 and other components, and this may cause electrolytic corrosion. In particular, when the tension balancer 100 is installed in a coastal area where it is easily exposed to water or water containing salt, electrolytic corrosion is likely to be promoted. For this reason, as an optional configuration, the tension balancer 100 may be provided with an insulating film 116 on the inner surface of the first cylindrical member 120 (FIG. 13). The insulating film 116 may be a film containing an engineering plastic such as polyamide or polyimide, a film containing a fluorine-containing polymer such as polytetrafluoroethylene, or a film containing a silicon-containing inorganic compound such as a silicon nitride film or a silicon oxide film, a diamond-like carbon (DLC) film, a hard chromium plating film, or the like may be used.

[0038] As described above, each of the embodiments described as embodiments of the present invention can be implemented in appropriate combination as long as they do not contradict each other. Also, based on each embodiment, those in which those skilled in the art have appropriately added, deleted, or changed the design of components are also included in the scope of the present invention as long as they have the gist of the present invention.

[0039] Also, other operational effects different from those brought about by the above-described embodiments, which are obvious from the description in this specification or can be easily predicted by those skilled in the art, are naturally understood to be brought about by the present invention.

Explanation of Reference Numerals

[0040] 100: Tension balancer, 104: First back plate, 106: U-shaped bar, 108: Collar, 110: Rear hook, 112: U-shaped bar, 114: Collar, 116: Insulating film, 120: First cylindrical member, 122: First front spring washer, 122a: Protrusion, 122b: Groove, 124: Bolt, 124a: Straight portion, 124b: Straight portion, 126: Nut, 128: First coil spring, 130: Second cylindrical member, 132: Second front spring washer, 134: First rear spring washer, 138: Second coil spring, 140: Third cylindrical member, 142: Third front spring washer, 144: Second rear spring washer, 148: Third coil spring, 150: Front hook, 152: Guide plate, 154: Second back plate, 160: Fourth cylindrical member, 164: Third rear spring washer

Claims

1. The first to nth cylindrical members, The first to (n - 1) coil springs, A rear hook attached to the first cylindrical member, A front hook attached to the nth cylindrical member, The first to (n - 1) front spring washers and the first to (n - 1) rear spring washers, and A stopper fixed to the first cylindrical member, The first to nth cylindrical members are arranged such that a (m + 1)th cylindrical member selected from the first to nth cylindrical members is located within an mth cylindrical member selected from the first to nth cylindrical members, The first to (n - 1) coil springs are arranged such that an mth coil spring selected from the first to (n - 1) coil springs is sandwiched between the mth cylindrical member and the (m + 1)th cylindrical member, The first to (n - 1) front spring washers and the first to (n - 1) rear spring washers are arranged such that an mth front spring washer selected from the first to (n - 1) front spring washers and an mth rear spring washer selected from the first to (n - 1) rear spring washers surround the (m + 1)th cylindrical member and sandwich the mth coil spring in a direction parallel to the coil axis of the mth coil spring, The stopper is arranged such that in the above direction, the first front spring washer is sandwiched between the first coil spring and the stopper, The first cylindrical member contains aluminum as a main component, The second to nth cylindrical members contain iron as a main component, n is selected from natural numbers of 2 or more and 5 or less, m is a variable selected from natural numbers of 1 or more and (n - 1), a tension balancer.

2. The first cylindrical member is made of aluminum or an aluminum alloy, the tension balancer according to Claim 1.

3. The second to nth cylindrical members are made of iron or stainless steel, the tension balancer according to Claim 1.

4. The first to (n - 1) rear spring washers are each fixed to the second to nth cylindrical members, The second to (n - 1) front spring washers are each fixed to the second to nth cylindrical members, The first front spring washer is not fixed to the first cylindrical member and is configured to be movable in the space between the first cylindrical member and the second cylindrical member in the absence of the elastic force of the first coil spring, the tension balancer according to Claim 1.

5. The tension balancer according to claim 1, wherein the stopper includes a plurality of bolts passing through the first cylindrical member.

6. The stopper includes k bolts arranged at the vertices of a virtual regular k-sided polygon on a plane perpendicular to the coil axis, where k is selected from natural numbers of 3 or more and 8 or less, the tension balancer according to claim 1.

7. The first front spring washer has a plurality of protrusions protruding in a direction opposite to that of the first coil spring, and one of the bolts is arranged between two adjacent ones of the protrusions, the tension balancer according to claim 5.

8. The stopper is a member having a U-shape, and a pair of legs of the U-shape penetrate the first cylindrical member, the tension balancer according to claim 1.

9. The first front spring washer has a pair of grooves for accommodating the pair of legs on a surface opposite to that of the first coil spring, the tension balancer according to claim 8.

10. The tension balancer according to claim 1, further comprising an insulating layer on an inner surface of the first cylindrical member.

11. The second to nth cylindrical members are coated with a metal film, the tension balancer according to claim 1.

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