Tension balancer

Abstract

The tension balancer includes first to nth cylindrical members, first to (n-1) th coil springs, a first hook attached to the first cylindrical member, a second hook attached to the nth cylindrical member, and a scale attached to the nth cylindrical member. The scale extends in a first direction parallel to central axes of the first to n-th cylindrical members, is located outside the n-th cylindrical member, overlaps the n-th cylindrical member in a second direction perpendicular to the first direction, and is stretchable in the first direction. The first to n-th cylindrical members are disposed such that a (j + 1)-th cylindrical member selected from among the first to n-th cylindrical members is surrounded by a j-th cylindrical member. The cylindrical members and the coil springs are alternately arranged. N is a natural number greater than 3, and j is a variable selected from natural numbers greater than 1 and less than (n-1).

Description

Technical Field

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

[0002] Tension balancers are installed on overhead lines used in railways and other applications to maintain appropriate tension on the overhead lines even when they expand or contract due to temperature changes. For example, Patent Documents 1 and 2 disclose a tension balancer whose basic structure includes multiple cylindrical members arranged coaxially and a helical spring disposed between the cylindrical members. Furthermore, a graduated scale is installed on the tension balancer as an indicator for measuring its displacement, thereby allowing the state of the helical spring within the tension balancer to be monitored.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2014-108766 Patent Document 2: Japanese Patent Application Publication No. 2009-303301 Summary of the Invention The problem the invention aims to solve One objective of embodiments of the present invention is to provide a tension balancer with a novel structure. Alternatively, one objective of embodiments of the present invention is to provide a tension balancer that can be used for an extended period of time with an appropriate stroke length.

[0004] means for solving problems One embodiment of the present invention is a tension balancer. This tension balancer includes a first cylindrical member to an nth cylindrical member, a first helical spring to an (n-1)th helical spring, a first hook mounted on the first cylindrical member, a second hook mounted on the nth cylindrical member, and a scale mounted on the nth cylindrical member. The scale extends in a first direction parallel to the central axis of the first to nth cylindrical members, is located outside the nth cylindrical member, overlaps with the nth cylindrical member in a second direction perpendicular to the first direction, and is configured to be extendable in the first direction. The first to nth cylindrical members are configured such that a jth cylindrical member selected from the first to nth cylindrical members is surrounded by a (j+1)th cylindrical member selected from the first to nth cylindrical members. The cylindrical members and helical springs are alternately arranged. n is a natural number of 3 or more, and j is a variable selected from a natural number of 1 or more and (n-1) or less. Attached Figure Description

[0005] Figure 1 This is a schematic perspective view of a tension balancer according to an embodiment of the present invention.

[0006] Figure 2This is a schematic end view of a tension balancer according to an embodiment of the present invention.

[0007] Figure 3A This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0008] Figure 3B This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0009] Figure 3C This is a schematic end view of a portion of the tension balancer according to an embodiment of the present invention.

[0010] Figure 4A This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0011] Figure 4B This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0012] Figure 5A This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0013] Figure 5B This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0014] Figure 6A This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0015] Figure 6B This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0016] Figure 6C This is a schematic end view of a portion of the tension balancer according to an embodiment of the present invention.

[0017] Figure 7A This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0018] Figure 7B This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention.

[0019] Figure 7C This is a schematic end view of a portion of the tension balancer according to an embodiment of the present invention.

[0020] Figure 8 This is a schematic side view of a portion of the tension balancer according to an embodiment of the present invention. Detailed Implementation

[0021] Hereinafter, various embodiments of the invention disclosed in this application will be described with reference to the accompanying drawings. However, the present invention may be implemented in various ways without departing from its spirit and is not limited to the description of the embodiments illustrated below.

[0022] To make the description clearer, the accompanying drawings sometimes schematically represent the width, thickness, shape, etc. of various parts compared to the actual aspects, but these are merely examples and do not limit the interpretation of the invention. Furthermore, the same reference numerals can be used to designate elements having the same function as those already described in this specification and the accompanying drawings, and repeated descriptions can be omitted.

[0023] In this specification and the accompanying drawings, the same reference numerals are used to generally represent multiple identical or similar structures, and hyphens followed by numbers are used after the reference numerals to represent them individually. When differentiating multiple parts within a structure, the same reference numerals are used, and letters are employed.

[0024] In this specification and claims, the expression "a structure exposed from another structure" means that a portion of a structure is not covered by another structure, and also includes the situation where the portion not covered by another structure is covered by another structure. Furthermore, this expression also includes the situation where a structure is not in contact with another structure.

[0025] In the following description, a tension balancer 100 according to one embodiment of the present invention will be described. The tension balancer 100 can be used to stretch an overhead line with appropriate tension.

[0026] 1. Overall Structure Figure 1 A schematic perspective view of a tension balancer 100 is shown. The tension balancer 100 comprises a plurality of cylindrical members arranged coaxially and having different outer diameters. Figure 1The tension balancer 100 shown is a two-stage tension balancer with three cylindrical members, comprising a first cylindrical member 110, a second cylindrical member 120, and a third cylindrical member 130. The number of cylindrical members is not limited, typically ranging from two to four, but can also be five or more. In the tension balancer 100, a portion of a cylindrical member with a smaller outer diameter is inserted within a cylindrical member with a larger outer diameter. More specifically, when the tension balancer 100 has cylindrical members from the first cylindrical member to the nth (n being a natural number greater than or equal to 2) cylindrical members, and the outer diameter of the cylindrical members gradually decreases from the first to the nth cylindrical member, the (j+1)th (j being a variable chosen from natural numbers greater than 1 and less than (n-1)) cylindrical member can be arranged in a manner surrounded by the jth cylindrical member, and the (j+1)th cylindrical member can reversibly slide inside the jth cylindrical member in the direction of the central axis of each cylindrical member. The following explanation will continue using a two-stage tension balancer 100 (i.e., a tension balancer with n=3).

[0027] At one end of the first cylindrical member 110 with the largest outer diameter, a support-side mounting member (hereinafter referred to as the first hook) 102 is directly or indirectly installed. Using this first hook 102, the tension balancer 100 can be connected to a fixed structure such as a support. Alternatively, a suspension hook 106 and / or an opening (not shown) for suspending the tension balancer 100 may be provided on the upper part of the first cylindrical member 110 during the assembly or installation of the tension balancer 100. On the other hand, at one end of the cylindrical member with the smallest outer diameter (here, the third cylindrical member 130), an overhead line-side mounting member (hereinafter referred to as the second hook) 104 for connection to the overhead line is directly or indirectly installed. As described later, helical springs are arranged in a compressed state between adjacent cylindrical members, and multiple cylindrical members and multiple helical springs are arranged alternately. The elastic force of the helical springs, which attempts to stretch, generates a force that pulls the adjacent inner cylindrical member inward from the outer cylindrical member. Using this force, the overhead line can be stretched with appropriate tension.

[0028] Hereinafter, the length direction of the tension balancer 100 is defined as the x-direction, and the vertical direction when the tension balancer 100 is set with the x-direction as the horizontal direction is defined as the z-direction. The direction orthogonal to the x-direction and z-direction is defined as the y-direction. The x-direction is the direction parallel to the central axis of the tension balancer 100 and each cylindrical component, and is the direction of sliding from the second cylindrical component to the nth cylindrical component.

[0029] 2. First cylindrical component along Figure 1 A schematic diagram of the end face of the dashed line A-A' extending in the x-direction is shown below. Figure 2 As shown. Figure 2As shown, a first back plate 140 forming the bottom surface can be provided at one end of the first cylindrical member 110 where the first hook 102 is disposed. The first hook 102 can be fixed to the first back plate 140 by welding or bolting, or it can be fixed to the first cylindrical member 110 without the first back plate 140. Additionally, although not shown, an opening for draining water that has seeped into the first cylindrical member 110 can also be provided. An anti-detachment mechanism to prevent the second cylindrical member 120 and the third cylindrical member 130 from detaching is also provided at the end where the first hook 102 is disposed. The structure of the anti-detachment mechanism is not limited, and... Figure 1 and Figure 2 In the example shown, the U-shaped rod 142 is configured as an anti-drop mechanism. The U-shaped rod 142 extends in a direction perpendicular to the z-direction and passes through the first cylindrical member 110, and is prevented from falling off by a collar 144 located at its end. The first back plate 140 moves toward the first hook 102 side by the elastic force of the first helical spring 112 located between the first cylindrical member 110 and the second cylindrical member 120, and the second helical spring 122 located between the second cylindrical member 120 and the third cylindrical member 130, but this movement is limited by the U-shaped rod 142 and the first back plate 140.

[0030] An annular first front washer 114 is provided at the end of the first cylindrical member 110 opposite to the first hook 102 (i.e., the end on the side of the second hook 104). The first front washer 114 may be configured to surround the first cylindrical member 110 and block a portion of the first cylindrical member 110. The opening of the first front washer 114 functions as an opening for allowing the second cylindrical member 120 to slide within the first cylindrical member 110, thereby exposing a portion of it. Although not shown, the first front washer 114 may not be surrounded by the first cylindrical member 110, or it may have an outer diameter that is the same as or substantially the same as the outer diameter of the first cylindrical member 110 and be configured to block a portion of the first cylindrical member 110. Alternatively, the first front washer 114 may be integrally formed with the first cylindrical member 110.

[0031] 3. Second cylindrical component The second cylindrical member 120 is disposed within the first cylindrical member 110. An annular first rear washer 124 is provided at the end of the second cylindrical member 120 on the side of the first hook 102. Figure 2In the example shown, the first rear washer 124 is disposed around the second cylindrical member 120, but the first rear washer 124 may not surround the second cylindrical member 120, or it may be disposed at the end of the second cylindrical member 120 with the same or substantially the same inner diameter as the second cylindrical member 120. The first rear washer 124 may be integrally formed with the second cylindrical member 120. The first helical spring 112 is disposed between the first front washer 114 and the first rear washer 124 in the space between the first cylindrical member 110 and the second cylindrical member 120. Therefore, the compressed first helical spring 112 pushes the first front washer 114 and the first rear washer 124 in opposite directions by the elastic force generated when attempting to extend. As a result, a force is generated that pulls the second cylindrical member 120 into the interior of the first cylindrical member 110.

[0032] Similar to the first cylindrical member 110, an annular second front washer 126 is provided at the end of the second cylindrical member 120 on the side of the second hook 104. The second front washer 126 may be configured to surround the second cylindrical member 120 and block a portion of the second cylindrical member 120. The opening of the second front washer 126 functions as an opening for allowing the third cylindrical member 130 to slide within the second cylindrical member 120 and for a portion of it to protrude from the second cylindrical member 120. Although not shown, the second front washer 126 may not be surrounded by the second cylindrical member 120, or it may be configured to block the second cylindrical member 120 by having an outer diameter that is the same as or substantially the same as the outer diameter of the second cylindrical member 120. Alternatively, the second front washer 126 may be integrally formed with the second cylindrical member 120.

[0033] 4. Third cylindrical component Similar to the second cylindrical member 120, the third cylindrical member 130 is disposed within the second cylindrical member 120, and an annular second rear washer 132 is provided at the end of the third cylindrical member 130 on the side of the first hook 102. Figure 2In the example shown, the second rear washer 132 is disposed around the third cylindrical member 130, but the second rear washer 132 may not surround the third cylindrical member 130, or it may be disposed at the end of the third cylindrical member 130 with the same or substantially the same inner diameter as the third cylindrical member 130. The second rear washer 132 may be integrally formed with the third cylindrical member 130. The second helical spring 122 is disposed between the second front washer 126 and the second rear washer 132 in the space between the second cylindrical member 120 and the third cylindrical member 130. Therefore, the compressed second helical spring 122 pushes the second front washer 126 and the second rear washer 132 in opposite directions by the elastic force generated when attempting to extend. As a result, a force is generated that pulls the third cylindrical member 130 into the interior of the second cylindrical member 120.

[0034] When the second cylindrical member 120 and the third cylindrical member 130 slide relative to the first cylindrical member 110, the first helical spring 112 and the second helical spring 122 extend and retract. At this time, the first helical spring 112 and the second helical spring 122 rotate around the x-direction, resulting in the second cylindrical member 120 and the third cylindrical member 130 also rotating. Therefore, as an arbitrary structure, a second back plate 134 with a slit can be provided on the side of the first hook 102 in a way that blocks a part of the third cylindrical member 130, and a plate-shaped guide plate 146 can be configured to pass through the slit of the second back plate 134. The guide plate 146 can be configured to pass through the first back plate 140. In this case, the guide plate 146 can be used as the first hook 102, or the first hook 102 can be fixed to the end of the guide plate 146. Since the rotation of the innermost third cylindrical member 130 is prevented by providing a second back plate 134 with a slit and a plate-shaped guide plate 146 passing through the slit, the rotation of the cylindrical member (here, the second cylindrical member 120) located between the first cylindrical member 110 and the cylindrical member with the smallest diameter (here, the third cylindrical member 130) can also be restricted.

[0035] 5. Scale and pointer components like Figure 1 and Figure 2 As shown, a scale 150 extending in a direction parallel to the central axis of each cylindrical member (i.e., the x-direction) is mounted on the innermost third cylindrical member 130. The scale 150 is located outside the third cylindrical member 130 and is configured to overlap with the first cylindrical member 110 to the third cylindrical member 130 in the z-direction. The scale 150 and the third cylindrical member 130 are fixed to each other in any manner, such that even if the cylindrical members move, the relative distance and positional relationship between the third cylindrical member 130 and the scale 150 remain constant. There are no restrictions on the method of fixing the scale 150 and the third cylindrical member 130; for example, as... Figure 1 and Figure 2 As shown, a plate-shaped front plate 152 can be fixed to the end of the third cylindrical member 130, and the scale 150 can be fixed relative to the front plate 152 by welding or bolting. Although not shown, a single rod or multiple supports can be used instead of the front plate 152 to fix the scale 150 and the third cylindrical member 130.

[0036] The outer surface of the scale 150 is marked with graduations. The graduations may be formed by, for example, strips of ink printed in a direction perpendicular to the x-direction, tape wrapped around the scale 150, or engraving.

[0037] Here, the scale 150 is configured to reversibly expand and contract in the x-direction (see reference). Figure 1 (The dashed arrow). There are no restrictions on the mechanism used for telescoping in the x-direction, such as... Figure 3A As shown, the scale 150 can be configured to include a beam 156 fixed to the third cylindrical member 130 and a cylindrical sliding member 154 that houses the beam 156. The scale is applied to the outer surface of the sliding member 154.

[0038] The beam 156 is connected directly to the third cylindrical member 130, either directly or via, for example, the front plate 152, and its relative position to the third cylindrical member 130 remains unchanged. The shape of the end face (the end face perpendicular to the x-direction) of the beam 156 can be arbitrarily set, and can be a polygon such as a circle, ellipse, or square. On the other hand, the sliding member 154 is configured as a cylinder, allowing it to move along the beam 156 in the x-direction while the beam 156 is housed. The sliding member 154 can be formed with a through hole extending in the x-direction, or it can be formed with a bottomed hole extending in the x-direction. The shape of the through hole or the bottomed hole of the sliding member 154 (the shape of the end face perpendicular to the x-direction) can be formed as long as it is suitable for the shape of the end face of the beam 156. The sliding member 154 can be configured to be detachable from the beam 156, or a stop (not shown) can be provided to prevent the sliding member 154 from falling off the beam 156.

[0039] Furthermore, to fix the scale 150 at any length, the beam 156 is provided with a plurality of through holes 156a arranged along the x-direction. Similarly, the sliding member 154 is provided with at least one through hole 154a configured to overlap with the through holes 156a. At least one through hole 154a may include a plurality of through holes 154a. Figure 3B and along Figure 3B A schematic diagram of the end face of the dashed line BB′. Figure 3CAs shown, for example, by inserting bolt 158 ​​into through holes 154a and 156a and fixing bolt 158 ​​with nut 160, the length of scale 150 can be adjusted and fixed in pitch units of through hole 156a. Furthermore, during fixing, washer 162 can be used with bolt 158 ​​and nut 160 as an arbitrary configuration. Although not shown, washer 162 can also be configured to fit the curved surface of the end face of sliding member 154.

[0040] The pointer member 170 is fixed to the outermost cylindrical member, namely the first cylindrical member 110. Therefore, this position is constant and independent of the expansion and contraction of the tension balancer 100. The pointer member 170 is configured to overlap with the scale 150 in the z-direction, and the scale 150 is held between the first cylindrical member 110 and the pointer member 170. The pointer member 170 functions as a reference for reading the graduations on the scale 150. As long as this function is achieved, the structure of the pointer member 170 can be arbitrarily determined, and the pointer member 170 can be configured to include, for example, a rod, a plate, etc., extending in the y-direction. Furthermore, the method of fixing it to the first cylindrical member 110 is also arbitrary; methods such as bolting or welding can be used.

[0041] Considering the stroke-tension characteristics of the tension balancer 100, the tension balancer 100 is used within a stroke range that allows for the acquisition of appropriate tension. The stroke length can be determined using the scale 150 and the pointer component 170, and the state of the coil spring can be monitored based on the stroke length.

[0042] However, the characteristics of mass-produced tension balancers 100 are not all the same, and there is a certain degree of deviation. Therefore, when the length of the scale 150 cannot be adjusted, the initial position of the scale 150 may sometimes be inappropriate. In extreme cases, the pointer member 170 may overlap with parts outside the scale range, or the pointer member 170 may not overlap with the scale in the z-direction.

[0043] However, in the tension balancer 100 of one embodiment of the present invention, the scale 150 is extendable and retractable in the x-direction and can be fixed at any position in the x-direction. Therefore, the length of the scale 150 can be precisely adjusted according to the characteristic deviations of the tension balancer during manufacturing, and the stroke length of the tension balancer 100 during use can be accurately determined. Therefore, a tension balancer that can be used with an appropriate stroke length for a long period of time can be provided.

[0044] 6. Variations The structure of scale 150 is not limited to the structure described above and can be modified in various ways. Examples of modifications are described below.

[0045] (1) Variation Example 1 For example, such as Figure 4A As shown, beam 156 may have a slit 156b extending along the x-direction. The slit 156b may penetrate beam 156 in the y-direction, and although not shown, it may also penetrate beam 156 in the z-direction. Here, the slit 156b has an opening in the x-direction with a length-to-width ratio (length in the x-direction / length in the z-direction or y-direction) that is, for example, 5 or more and 30 or less. The method of fixing beam 156 and sliding member 154 is also arbitrary, for example... Figure 4B As shown, one or more bolts 158 and nuts 160 that engage with bolts 158 can be used.

[0046] When slit 156b is provided, in order to prevent the sliding member 154 from moving accidentally in the x-direction, the width of slit 156b (the length in the z-direction or y-direction perpendicular to the x-direction) can be made to change continuously or intermittently in the x-direction in a periodic manner. For example, as shown in the enlarged view of slit 156b ( Figure 5A , Figure 5B As shown, the width can be continuously or intermittently changed by providing a protrusion 156c and a recess 156d on the inner wall constituting the slit 156b. The protrusion 156c and the recess 156d are formed such that the minimum width W2 of the slit 156b is less than the outer diameter of the threaded portion of the bolt 158, and the maximum width W1 is greater than the outer diameter of the threaded portion of the bolt 158. By applying such a shape to the slit 156b, it is possible to prevent the sliding member 154 from moving accidentally in the x-direction.

[0047] (2) Variation Example 2 Furthermore, the sliding member 154 does not necessarily need to completely surround the beam 156 on its end face perpendicular to the x-direction; for example, as... Figure 6A , Figure 6B and along Figure 6B A schematic diagram of the end face of the dashed line C-C' ( Figure 6CAs shown, the groove can be C-shaped. In this case, to allow visual confirmation of the scale mounted on the sliding member 154, the sliding member 154 is positioned with the C-shaped opening facing the third cylindrical member 130. Furthermore, the beam 156 is formed as a plate to fit the shape of the groove in the sliding member 154. Similar to Modified Example 1, the sliding member 154 and the beam 156 can be fixed using bolts 158 penetrating the slit 156b and the through hole 154a, nuts 160 engaging with the bolts 158, and washers 162, etc. Additionally, in the sliding member 154, besides the through hole 154a for fixing to the beam 156, one or more through holes 154b for draining rainwater, etc., can be formed. The size of the through hole 154b can be smaller than the size of the through hole 154a. Furthermore, although not shown, similar to Modified Example 1, the width of the slit 156b can be made to change continuously or intermittently along the x-direction in a periodic manner.

[0048] (3) Variation Example 3 Or, such as Figure 7A As shown, scale 150 can be configured to thread both beam 156 and sliding member 154, with sliding member 154 sliding relative to beam 156 by rotating about the x-direction. Specifically, the entire or a portion of the outer circumferential surface of beam 156 is machined with external threads, and the entire or a portion of the inner wall of cylindrical sliding member 154 is machined with internal threads. Threading beam 156 and sliding member 154 causes them to mesh with each other. Scale 150 is thus configured as follows: Figure 7B And a schematic diagram of the end face along its dashed line D-D' ( Figure 7C As shown, by rotating the sliding member 154 about the x-direction (refer to...) Figure 7B The dashed arrow indicates that the sliding member 154 can slide along the x-direction.

[0049] Or, such as Figure 8 As shown, the scale 150 can be constructed from a single component whose outer surface is threaded. In this case, only the outer surface of the scale 150 needs to be externally threaded, and a through hole needs to be provided in the structure (e.g., front plate 152) for connecting the scale 150 to the third cylindrical member, and the inner wall of the through hole needs to be internally threaded. According to this structure, the scale 150 can be adjusted to any position relative to the third cylindrical member 130, and the positional relationship between the third cylindrical member 130 and the scale 150 at that position can be fixed.

[0050] The embodiments described above, as examples of implementations of the present invention, can be appropriately combined and implemented as long as they do not contradict each other. Furthermore, any implementations by those skilled in the art that appropriately add, delete, or modify the constituent elements based on the embodiments, as long as they capture the essence of the present invention, are also included within the scope of the present invention.

[0051] Furthermore, it should be understood that even if other effects differ from those produced by each of the above embodiments, effects that are obvious from the description in this specification or that can be easily predicted by those skilled in the art are of course produced by the present invention.

[0052] Explanation of reference numerals in the attached figures 100: Tension balancer; 102: First hook; 104: Second hook; 106: Suspension hook; 110: First cylindrical component; 112: First helical spring; 114: First front washer; 120: Second cylindrical component; 122: Second helical spring; 124: First rear washer; 126: Second front washer; 130: Third cylindrical component; 132: Second rear washer; 134: First... Second backplate, 140: First backplate, 142: U-shaped rod, 144: collar, 146: guide plate, 150: scale, 152: front plate, 154: sliding member, 154a: through hole, 154b: through hole, 156: beam, 156a: through hole, 156b: slit, 156c: protrusion, 156d: recess, 158: bolt, 160: nut, 162: washer, 170: pointer member.

Claims

1. A tension balancer, wherein, have: First cylindrical component to nth cylindrical component; The first helical spring to the (n-1)th helical spring; The first hook is mounted on the first cylindrical member; The second hook is mounted on the nth cylindrical member; as well as A scale, mounted on the nth cylindrical member, extends in a first direction parallel to the central axis of the first cylindrical member to the nth cylindrical member, is located outside the nth cylindrical member, overlaps with the nth cylindrical member in a second direction perpendicular to the first direction, and is telescopic in the first direction. The first to the nth cylindrical members are configured such that a (j+1)th cylindrical member selected from the first to the nth cylindrical members is surrounded by a jth cylindrical member selected from the first to the nth cylindrical members. The cylindrical component and the helical spring are arranged alternately. n is a natural number greater than or equal to 2, and j is a variable chosen from natural numbers greater than or equal to 1 and less than (n-1).

2. The tension balancer according to claim 1, wherein, It also has: A pointer component that extends in the second direction and is disposed between the scale and the nth cylindrical component.

3. The tension balancer according to claim 1, wherein, The scale has the following characteristics: A beam, which is connected to the nth cylindrical member and extends in the first direction; as well as A sliding member that accommodates the beam, is capable of sliding along the beam, and has a scale.

4. The tension balancer according to claim 3, wherein, The beam has a plurality of through holes arranged in the first direction. The sliding member has at least one opening that overlaps with one of the through holes.

5. The tension balancer according to claim 3, wherein, The beam has a slit extending in the first direction and penetrating the beam. The sliding member has at least one opening that overlaps with the slit.

6. The tension balancer according to claim 5, wherein, The width of the slit changes periodically.

7. The tension balancer according to claim 3, wherein, The end of the beam in a plane perpendicular to the first direction is circular.

8. The tension balancer according to claim 3, wherein, The beam is plate-shaped. The end face of the sliding member in a plane perpendicular to the first direction is C-shaped.

9. The tension balancer according to claim 3, wherein, The outer periphery of the beam has a surface machined with external threads. The sliding member has an inner wall with internal threads and a bottomed hole or through hole extending in the first direction.

10. The tension balancer according to claim 3, wherein, The scale is connected to the nth cylindrical member via a front plate having a through hole with internal threads. The sliding member has a surface machined with external threads.

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