Double-tube support device

Abstract

A supporting member is fixed and attached to the outer circumference of the inner pipe, which is routed inside the outer pipe. A ring-shaped tight-fitting link is rotatably attached to the outer circumference of the supporting member, and the rotating ring-shaped tight-fitting link adheres tightly to the inner surface of the outer pipe, thereby preventing vibration between the outer and inner pipes. [Solution] A ring-shaped support 2 is fixed and attached to the outer circumferential surface 52a of the inner tube 52 of the double tube 5. Engagement grooves 24 are formed on the projection tip side of each support piece 23 of the ring-shaped support 2. A flexible annular tight-fitting link 3, having a circular outer circumferential surface side 32 with an outer diameter smaller than the inner diameter of the outer tube 51 and multiple non-circular inner circumferential surface sides 31 of different thicknesses, is rotatably mounted in the engagement grooves 24 of each support piece 23.

Description

Technical Field

[0001] The present invention relates to a device for supporting a double pipe having an outer pipe and an inner pipe piped inside thereof. In particular, a device for supporting the outer peripheral side of the inner pipe piped inside the outer pipe is fixedly attached, and an annular close contact link is rotatably attached to the outer peripheral side of the supporting device, and the annular close contact link is in close contact with the inner peripheral surface of the outer pipe, thereby preventing the outer pipe and the inner pipe from vibrating. The present invention relates to a double pipe support device.

Background Art

[0002] Piping related to special high-pressure gas and toxic gas facilities has a double pipe structure in which an alarm facility is provided according to the surrounding situation in order to prevent the gas leaked from the piping from diffusing, and an inner pipe is disposed inside the outer pipe. There are regulations. It is necessary to take measures to detect gas leakage between the inner pipe and the outer pipe of the double pipe. As such measures, the applicant has devised a leakage gas suction method (constant suction), an inert gas pressurization method (constant pressurization), a vacuum heat insulation suction method (constant negative pressure), and the like. In a double pipe structure, a gas flow path such as special high-pressure gas or toxic gas is formed inside the inner pipe, an annular ventilation gas flow path is formed between the inner pipe and the outer pipe, the outer pipe is supported by the inner pipe, and the inner pipe and the outer pipe A support device for keeping the cross-sectional area of the flow path between them constant is appropriately arranged at predetermined positions in the longitudinal direction of the outer pipe.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0004] However, when a special high-pressure gas flows through the inner tube, the gas pressure causes expansion, contraction, and vibration. Some conventional devices that support the inner and outer tubes have a structure that can damage parts due to the heat input during welding, and some have a structure that cannot prevent the outer and inner tubes from vibrating.

[0005] This invention was conceived in view of the above-mentioned problems and aims to solve them. Its purpose is to provide a double-tube support device that prevents vibration between the outer and inner tubes and is unaffected by heat input due to welding. This is achieved by fixing and attaching a support device to the outer circumference of an inner tube routed inside an outer tube, and rotatably attaching an annular contact link to the outer circumference of the support device, so that the rotating annular contact link is in close contact with the inner surface of the outer tube. [Means for solving the problem]

[0006] To achieve the above objectives, this invention provides a double pipe having an outer pipe and an inner pipe piped inside it, wherein a ring-shaped support having a plurality of support pieces protruding at equal intervals in the circumferential direction is fixedly attached to the outer circumferential surface of the inner pipe of the double pipe, an engagement groove having a groove bottom surface equidistant from the center of the ring-shaped support in the circumferential direction is formed on the tip side of the protrusion of each support piece, a flexible annular contact link having a circular outer circumferential surface side having an outer diameter smaller than the inner diameter of the outer pipe and a plurality of non-circular inner circumferential surface sides of different thicknesses is rotatably mounted in the engagement groove of each support piece of the ring-shaped support, and the inner circumferential surface side of the annular contact link with a larger thickness that rotates along the engagement groove is pressed toward the outer circumferential surface side by the engagement groove, and the outer circumferential surface side of the pressed annular contact link is brought into close contact with the inner circumferential surface of the outer pipe.

[0007] Herein, as a preferred embodiment of claim 1, claim 2 is that the annular contact link, which rotates along the engagement groove, rotates in the same direction as the outer tube, which has a non-circular cross-section on its inner surface consisting of a long inner diameter and a short inner diameter 51c, while the outer tube is rotating, the outer surface side of the annular contact link contacts a part of the non-circular inner surface of the rotating outer tube. Claim 3 is that the outer surface side of the annular contact link has a circular shape, and the inner surface side of the annular contact link is formed as a rounded non-circular shape with alternating sections of different thicknesses. Claim 4 is that the outer surface side of the annular contact link has a circular shape, and the inner surface side of the annular contact link is formed as a rounded non-circular shape with alternating sections of different thicknesses, and a plurality of sections of different thicknesses are formed at equal intervals in the circumferential direction. Claim 5 is that the outer circumferential surface of the annular contact link has a circular shape, and the inner circumferential surface of the annular contact link is formed as a rounded non-circular shape with alternating sections of different thicknesses, the sections of different thicknesses being formed at equal intervals in the circumferential direction, and the number of sections with large thickness and sections with small thickness are the same as the number of support pieces of the ring-shaped support, respectively.

[0008] Furthermore, in a preferred embodiment of claim 1, claim 6 is characterized in that the outer circumferential surface of the annular contact link has a circular shape, and on the inner circumferential surface of the annular contact link, a plurality of stepped inclined surfaces for preventing reverse rotation are formed in the same direction, each consisting of a gently sloping surface with gradually increasing thickness, an inclined surface start end with a small thickness that is the starting end of the inclined surface, an inclined surface end with a large thickness that is the ending end of the inclined surface, and a stepped surface with a height difference where the thickness changes abruptly from the inclined surface end to the adjacent inclined surface start end. Claim 7 is characterized in that the outer surface of the annular contact link has a circular shape, and on the inner surface of the annular contact link, a plurality of stepped inclined surfaces for preventing reverse rotation are formed in the same direction, each consisting of a gently sloping surface with gradually increasing thickness, an inclined surface start end with a small thickness that is the starting end of the inclined surface, an inclined surface end with a large thickness that is the ending end of the inclined surface, and a stepped surface with a height difference where the thickness changes abruptly from the inclined surface end to the adjacent inclined surface start end, and the stepped inclined surfaces for preventing reverse rotation are formed by a plurality of short inclined surfaces with small lengths in succession, and on the remaining inner surface, a long inclined surface with a large length is formed in succession. [Effects of the Invention]

[0009] According to the double-tube support device of this invention, a flexible annular contact link having a circular outer surface side with an outer diameter smaller than the inner diameter of the outer tube and a non-circular inner surface side with a different thickness is rotatably mounted in the engagement groove, and the inner surface side of the thicker portion of the annular contact link, which rotates along the engagement groove, is pressed toward the outer surface side by the engagement groove, and the outer surface side of the pressed annular contact link is brought into close contact with the inner surface of the outer tube, thereby fixing the outer tube and inner tube of the double-tube via the annular contact link and ring-shaped support, which prevents the outer tube and inner tube from vibrating and eliminates the effects of heat input due to welding, thus providing an extremely novel and beneficial effect.

[0010] According to the double-tube support device of claim 6 and claim 7, in addition to the above-mentioned effects, when the annular contact link, which is in close contact with the inner circumferential surface of the outer tube, attempts to rotate in the same opposite direction as the outer tube, some of the multiple stepped surfaces of the reverse rotation prevention stepped inclined surface formed on the inner circumferential surface side of the annular contact link come into contact with the ring-shaped support fixed to the inner tube, thereby preventing the annular contact link from rotating in the same opposite direction and preventing it from loosening. [Brief explanation of the drawing]

[0011] [Figure 1] This is an internal perspective view showing a double-tube support device, which is an embodiment-1 for carrying out this invention, installed inside a double-tube. [Figure 2] This is a perspective view of a double-tube support device showing Embodiment-1 for carrying out this invention. [Figure 3] This is a perspective view of a ring-shaped support showing Embodiment-1 of the present invention. [Figure 4] This is a perspective view of an annular tight link showing Embodiment-1 for carrying out this invention. [Figure 5] This is a cross-sectional view of an annular tight link showing Embodiment-1 for carrying out this invention. [Figure 6]It is a cross-sectional view of an outer tube showing Embodiment-1 for carrying out this invention. [Figure 7] It is a cross-sectional view when attaching a double-tube support device showing Embodiment-1 for carrying out this invention to the inside of a double tube. [Figure 8] It is a cross-sectional view after rotation of an annular close-contact link when attaching a double-tube support device showing Embodiment-1 for carrying out this invention to the inside of a double tube. [Figure 9] It is an internal perspective view of the state of attaching a double-tube support device showing Embodiment-2 for carrying out this invention to the inside of a double tube. [Figure 10] It is a perspective view of a double-tube support device showing Embodiment-2 for carrying out this invention. [Figure 11] It is a perspective view of a ring-shaped support showing Embodiment-2 for carrying out this invention. [Figure 12] It is a perspective view of an annular close-contact link showing Embodiment-2 for carrying out this invention. [Figure 13] It is a cross-sectional view of an annular close-contact link showing Embodiment-2 for carrying out this invention. [Figure 14] It is a cross-sectional view of an outer tube showing Embodiment-2 for carrying out this invention. [Figure 15] It is a cross-sectional view when attaching a double-tube support device showing Embodiment-2 for carrying out this invention to the inside of a double tube. [Figure 16] It is a cross-sectional view after rotation of an annular close-contact link when attaching a double-tube support device showing Embodiment-2 for carrying out this invention to the inside of a double tube.

Embodiments for Carrying out the Invention

[0012] Hereinafter, this invention will be described more specifically based on the embodiments for carrying out the invention described in the drawings.

[0013] 〔Embodiment-1〕 In Figures 1 to 8, the double-walled pipe 5, through which a special gas flows, consists of an outer pipe 51 and an inner pipe 52 installed inside it. The special gas flows directly through the inner pipe 52. The outer pipe 51 serves to protect against gas leaks or other issues that may occur in the inner pipe 52 through which the dangerous special gas flows directly. The outer pipe 51 and the inner pipe 52 are installed with a gap between them so that they do not come into contact.

[0014] The double-walled pipe 5, which consists of an outer pipe 51 and an inner pipe 52 routed inside it, has multiple double-walled pipe support devices 1 attached to the gap between the outer pipe 51 and the inner pipe 52 at predetermined intervals in the direction of piping, so as to prevent the inner pipe 52 and the outer pipe 51 from vibrating.

[0015] Each double-tube support 1 consists of an annular ring-shaped support 2 fixedly attached to the outer surface 52a of the inner tube 52, and an annular tight-fitting link 3 rotatably attached to the outer surface of the ring-shaped support 2.

[0016] The annular ring-shaped support 2 is attached to the outer surface 52a of the inner tube 52 by, for example, welding or adhesive. If the inner tube 52 is made of metal, such as stainless steel, the ring-shaped support 2 is attached by welding. If the inner tube 52 is made of plastic, the ring-shaped support 2 is attached by adhesive.

[0017] The annular ring-shaped support 2 is a device that is attached around the outer surface 52a of the inner tube 52, and has a circular fitting hole 21 in its central portion. This fitting hole 21 is shaped to have an inner diameter that can be fitted onto the outer surface 52a of the inner tube 52.

[0018] A circular ring 22 is formed on the outer circumference of the fitting hole 21 in the central part of the ring-shaped support 2, which is attached around the outer circumference of the outer surface 52a of the inner tube 52. Multiple support pieces 23 are formed on the outer circumference of the ring 22, protruding at equal intervals in the circumferential direction. In the figure, three support pieces 23 protrude radially from the outer circumference of the ring-shaped support 2 at equal intervals of 120 degrees in the circumferential direction.

[0019] Each protruding support piece 23 has an engagement groove 24 formed on its protruding tip side. The distance from the center of the fitting hole 21 of the annular ring 22 of the ring-shaped support 2 to the bottom surface 24a of the groove in the engagement groove 24 on the tip side of each support piece 23 is the same.

[0020] Each engagement groove 24 is formed with its groove direction directed around the circumferential surface of the outer surface 52a of the inner tube 52. An annular tight-fitting link 3 is rotatably mounted within each engagement groove 24. In other words, the annular tight-fitting link 3 is rotatably supported by the multiple engagement grooves 24 on the tip side of each support piece 23 of the ring-shaped support 2.

[0021] Each engagement groove 24 is formed from a flat groove bottom surface 24a and side wall surfaces 24b that rise from both the left and right sides of the groove bottom surface 24a. The inner circumferential surface side 31 of the annular contact link 3 contacts and slides against the flat groove bottom surface 24a of each engagement groove 24. The side wall surfaces 24b on both the left and right sides of each engagement groove 24 contact the thick left and right wide sides of the annular contact link 3, preventing it from coming out of each engagement groove 24.

[0022] As described above, the annular contact link 3 is prevented from coming off the tip side of each support piece 23 by the left and right side wall surfaces 24b within each engagement groove 24, but the groove width of each engagement groove 24 is approximately the same, large enough to accommodate the width of the annular contact link 3. The inner circumferential surface side 31 of the annular contact link 3 rotates while sliding in contact with the groove bottom surface 24a of each engagement groove 24.

[0023] The annular contact link 3 is made of a flexible resin. The annular contact link 3, which is rotatably mounted on the outer circumference of the ring-shaped support 2, is made of a material such as fluororesin that has good sliding properties with the inner circumferential surface 51a of the outer tube 51 and the outer circumferential surface 52a of the inner tube 52.

[0024] The outer circumferential surface 32 of the annular contact link 3, which is fitted into the engagement groove 24 on the tip side of the projection of the support piece 23, has a circular shape when no force is applied, and its surface is a uniform surface without irregularities in the circumferential direction. In contrast, the inner circumferential surface 31 of the annular contact link 3 is formed as a rounded, non-circular shape with parts of varying thickness when no force is applied.

[0025] The annular contact link 3 has a constant width and is sized to fit into the engagement groove 24 as described above, but the thickness of the annular contact link 3 is not constant, and the inner circumferential surface side 31 is formed with alternating thick and thin parts, creating a rounded, non-circular shape. The groove height of the side wall surface 24b of each engagement groove 24 is smaller than the large and small thicknesses of the annular contact link 3 around its entire circumference, that is, smaller than the thickness of the thin parts, and the outer circumferential surface side 32 of the annular contact link 3 always protrudes a portion from each engagement groove 24.

[0026] Therefore, each support piece 23 of the ring-shaped support 2, which has an engagement groove 24 formed on its tip side, does not have its tip directly in contact with the inner circumferential surface 51a of the outer tube 51. In other words, the outer circumferential surface side 32 of the annular tight-fitting link 3 contacts the inner circumferential surface 51a of the outer tube 51, preventing the tips of each support piece 23 from directly contacting the inner circumferential surface 51a of the outer tube 51.

[0027] The rounded, non-circular inner surface side 31 of the annular contact link 3 has a long inner radius 31a with the largest radius and a short inner radius 31b with the smallest radius, both located at a radial distance from the center of the annular contact link 3. Multiple long inner radii 31a and short inner radii 31b of different thicknesses are formed alternately at equal intervals in the circumferential direction on the inner surface side 31 of the annular contact link 3, and the inner surface side 31 has a gently wavy, non-circular shape in the circumferential direction.

[0028] Furthermore, the long inner radius 31a and short inner radius 31b, which have different thicknesses, are the same as the number of support pieces 23 in the ring-shaped support 2. For example, if three support pieces 23 are formed, then the inner circumferential surface side 31 of the annular tight-fitting link 3 has three long inner radii 31a and three short inner radii 31b, respectively.

[0029] Since the outer surface side 32 of the annular tight link 3 is circular and the inner surface side 31 is a rounded non-circular shape, the thickness of the annular tight link 3 is smallest when the inner surface side 31 is located at the long inner radius 31a, and the thickness is largest when the inner surface side 31 is located at the short inner radius 31b.

[0030] As mentioned above, the distance from the center of the fitting hole 21 in the center of the annular ring 22 of the ring-shaped support 2 to the groove bottom surface 24a in the engagement groove 24 on the tip side of each support piece 23 is the same. In contrast, the inner circumferential surface side 31 of the annular tight-fitting link 3 that contacts the groove bottom surface 24a of the engagement groove 24 has a gently wavy, non-circular shape in the circumferential direction.

[0031] Therefore, when the portion of the annular tight-fitting link 3 fitted into the engagement groove 24 of the support piece 23 is located at the long inner radius 31a of the inner circumferential surface side 31, the portion of the outer circumferential surface side 32 corresponding to the long inner radius 31a portion has the smallest thickness, and the amount of outward deformation is small. As a result, the outer circumferential surface side 32 after deformation of that portion has the smallest virtual short outer radius, which is the shortest distance from the center of the annular ring of the ring-shaped support 2.

[0032] In contrast, the inner circumferential surface side 31 of the flexible annular tight-fitting link 3 has the largest thickness when the portion located at the short inner radius 31b is inside the engagement groove 24 of the support piece 23. As a result, the outer circumferential surface side 32 of the flexible annular tight-fitting link 3 deforms outward, and the deformed outer shape of that portion has the largest virtual long outer radius, which is the distance from the center of the fitting hole 21 of the annular ring 22 of the ring-shaped support 2.

[0033] When the annular contact link 3 is not positioned at the location of each support piece 23, its outer surface side 32 has a circular shape. However, when the annular contact link 3 is fitted into the engagement groove 24 of each support piece 23, the flexible annular contact link 3 is pressed outward at its inner surface side 31, causing its outer surface side 32 to deform into a rounded, non-circular shape.

[0034] In other words, the flexible annular tight-fitting link 3 is pressed radially outward by the groove bottom surface 24a in the engagement groove 24 at the tip of each support piece 23, which is at the same distance from the center of the fitting hole 21 of the annular ring 22 of the ring-shaped support 2, causing it to deform slightly.

[0035] As a result, the outer surface side 32 of the annular contact link 3, which corresponds to the short inner radius 31b on the inner surface side 31, is pressed and pushed out radially because the annular contact link 3 has a large thickness, and as described above, its thickness increases to become a virtual long outer radius.

[0036] Conversely, on the outer surface side 32 of the annular tight-fitting link 3, which corresponds to the long inner radius 31a on the inner surface side 31, the thickness of the annular tight-fitting link 3 is small, so the thickness that is pressed and pushed out radially is small, resulting in a virtual short outer radius.

[0037] Incidentally, the inner diameter of the inner circumferential surface 51a of the outer tube 51 is of a non-circular shape, having a long inner diameter 51b with the largest diameter and a short inner diameter 51c with the smallest diameter. For this reason, the virtual long outer radius of the outer surface side 32 of the deformable flexible annular tight-fitting link 3 is adjusted to be smaller than the long inner diameter 51b of the inner circumferential surface 51a of the outer tube 51 and larger than the short inner diameter 51c of the inner circumferential surface 51a of the outer tube 51.

[0038] Next, a method for attaching the double-tube support 1 to the inside of the double-tube 5, based on the configuration of Embodiment-1 for carrying out the above invention, will be described below.

[0039] The double-tube support 1 is fixed and attached to a predetermined location on the outer surface 52a of the inner tube 52 of the double-tube 5, before the outer tube 51 is attached. If the inner tube 52 is made of metal, the ring-shaped support 2 of the double-tube support 1 is fixed and attached by welding. If the inner tube 52 is made of plastic, the ring-shaped support 2 of the double-tube support 1 is fixed and attached by adhesive.

[0040] To attach the ring-shaped support 2 to the outer surface 52a of the inner tube 52, the fitting hole 21 in the center of the ring 22 of the ring-shaped support 2 is fitted onto the outer surface 52a of the inner tube 52, and the annular ring 22 is fixed by welding or adhesive. At this time, to facilitate the subsequent rotation of the annular tight-fitting link 3, it is attached to the end of the outer tube 51 that will be attached to the outer circumference of the inner tube 52 later.

[0041] Subsequently, the inner surface side 31 of the annular contact link 3 is attached to the engagement grooves 24 of the multiple support pieces 23 formed at equal intervals in the circumferential direction of the ring-shaped support 2. At this time, the annular contact link 3 is attached so that the thinnest parts of the inner surface side 31 of the annular contact link 3, corresponding to each inner radius 31a, are aligned with the groove bottom surface 24a of the engagement groove 24 of each support piece 23.

[0042] In other words, when the outer pipe 51 is installed on the outer circumferential surface 52a side of the inner pipe 52, the piping is installed so that the virtual long outer radius of the annular tight link 3 attached to the outer circumferential surface 52a side of the inner pipe 52 does not come into contact with the long inner diameter 51b portion of the outer pipe 51, which has a larger diameter. At this time, the locations of the short inner radii 31b where the thickness of the inner circumferential surface side 31 of the annular tight link 3 is large are installed in intermediate positions where the support pieces 23 are not located.

[0043] After the outer tube 51 is fitted onto the inner tube 52, the annular contact link 3, which is attached to the outer circumference of the ring-shaped support 2 on the outer circumference surface 52a side of the inner tube 52, is rotated in the circumferential direction on the outer circumference surface 52a side of the inner tube 52. As the flexible annular contact link 3, which is fitted into the engagement groove 24 of the support piece 23, rotates, it is pressed and deformed by the groove bottom surface 24a of the engagement groove 24 of the support piece 23, causing the outer circumference surface side 32 at the virtual long outer radius point to come into contact with the short inner diameter 51c of the inner circumference surface 51a of the outer tube 51 and to adhere tightly.

[0044] The outer surface side 32 of the annular contact link 3 is in close contact with the short inner diameter 51c of the inner surface 51a of the outer tube 51, so that the outer tube 51 and the inner tube 52 are fixed together via the multiple support pieces 23 and the annular contact link 3, preventing the outer tube 51 and the inner tube 52 from vibrating relative to each other.

[0045] In other words, as the inner surface side 31 of the annular contact link 3 rotates along the engagement grooves 24 of each support piece 23 of the ring-shaped support 2, the thick portion of the inner surface side 31 of the annular contact link 3 with a short inner radius 31b is pressed toward the outer surface side 32 by the groove bottom surface 24a of the engagement groove 24 of the support piece 23, and this portion comes into close contact with the inner surface 51a of the outer tube 51. The rotating annular contact link 3 is sandwiched between the outer tube 51 and the inner tube 52, causing them to come into close contact and preventing vibration of the outer tube 51 and the inner tube 52.

[0046] [Embodiment-2] In Figures 9 to 16, the double-walled pipe 5 through which a special gas flows consists of an outer pipe 51 and an inner pipe 52 installed inside it. The special gas flows directly through the inner pipe 52. The outer pipe 51 serves to protect against gas leaks or other issues that may occur in the inner pipe 52 through which the dangerous special gas flows directly. The outer pipe 51 and the inner pipe 52 are installed with a gap between them so that they do not come into contact.

[0047] The double-walled pipe 5, which consists of an outer pipe 51 and an inner pipe 52 routed inside it, has multiple double-walled pipe support devices 101 attached to the gap between the outer pipe 51 and the inner pipe 52 at predetermined intervals in the direction of piping, so as to prevent vibration between the inner pipe 52 and the outer pipe 51.

[0048] Each double-tube support 101 consists of an annular ring-shaped support 2 fixedly attached to the outer surface 52a of the inner tube 52, and an annular tight-fitting link 103 rotatably attached to the outer surface of the ring-shaped support 2.

[0049] The annular ring-shaped support 2 is attached to the outer surface 52a of the inner tube 52 by, for example, welding or adhesive. If the inner tube 52 is made of metal, such as stainless steel, the ring-shaped support 2 is attached by welding. If the inner tube 52 is made of plastic, the ring-shaped support 2 is attached by adhesive.

[0050] The annular ring-shaped support 2 is a device that is attached around the outer surface 52a of the inner tube 52, and has a circular fitting hole 21 in its central portion. This fitting hole 21 is shaped to have an inner diameter that can be fitted onto the outer surface 52a of the inner tube 52.

[0051] A circular ring 22 is formed on the outer circumference of the fitting hole 21 in the central part of the ring-shaped support 2, which is attached around the outer circumference of the outer surface 52a of the inner tube 52. Multiple support pieces 23 are formed on the outer circumference of the ring 22, protruding at equal intervals in the circumferential direction. In the figure, three support pieces 23 protrude radially from the outer circumference of the ring-shaped support 2 at equal intervals of 120 degrees in the circumferential direction.

[0052] Each protruding support piece 23 has an engagement groove 24 formed on its protruding tip side. The distance from the center of the fitting hole 21 of the annular ring 22 of the ring-shaped support 2 to the bottom surface 24a of the groove in the engagement groove 24 on the tip side of each support piece 23 is the same.

[0053] Each engagement groove 24 is formed with its groove direction directed around the circumferential surface of the outer surface 52a of the inner tube 52. An annular tight-fitting link 103 is rotatably mounted within each engagement groove 24. In other words, the annular tight-fitting link 103 is rotatably supported by the multiple engagement grooves 24 on the tip side of each support piece 23 of the ring-shaped support 2.

[0054] Each engagement groove 24 is formed from a flat groove bottom surface 24a and side wall surfaces 24b that rise from both the left and right sides of the groove bottom surface 24a. The lower end of the groove bottom surface 24a is an end lower wall surface 24c. The inner circumferential surface side 131 of the annular contact link 103 contacts and slides against the flat groove bottom surface 24a of each engagement groove 24. The side wall surfaces 24b on both the left and right sides of each engagement groove 24 contact the thick left and right wide sides of the annular contact link 103, preventing it from coming out of each engagement groove 24.

[0055] As described above, the annular tight link 103 is prevented from coming off the tip side of each support piece 23 by the left and right side wall surfaces 24b within each engagement groove 24, but the groove width of each engagement groove 24 is approximately the same, large enough to accommodate the width of the annular tight link 103. The inner circumferential surface side 131 of the annular tight link 103 rotates while sliding in contact with the groove bottom surface 24a of each engagement groove 24.

[0056] The annular tight-fitting link 103 is made of a flexible resin. The annular tight-fitting link 103, which is rotatably mounted on the outer circumference of the ring-shaped support 2, is made of a material such as fluororesin that has good sliding properties with the inner circumferential surface 51a of the outer tube 51 and the outer circumferential surface 52a of the inner tube 52.

[0057] The outer peripheral surface 132 of the annular tight-fitting link 103, which is fitted into the engagement groove 24 on the tip side of the projection of the support piece 23, has a circular shape when no force is applied, and its surface is a uniform surface without irregularities in the circumferential direction.

[0058] In contrast, the inner circumferential surface 131 of the annular tight-fitting link 103 has multiple stepped inclined surfaces 133 for preventing reverse rotation, each having a rapidly changing height difference, and these surfaces are formed in the same direction in the circumferential direction. Each stepped surface 137 is formed in the same orientation.

[0059] Each anti-reverse rotation stepped inclined surface 133 consists of a gently sloping surface 134 with gradually increasing thickness, an inclined surface start end 135 with a smaller thickness that is the starting end of the inclined surface 134, an inclined surface end 136 with a larger thickness that is the ending end of the inclined surface 134, and a stepped surface 137 with a height difference where the thickness changes abruptly from the inclined surface end 136 to the adjacent inclined surface start end 135.

[0060] Each of the anti-reverse rotation stepped inclined surfaces 133 formed on the inner circumferential surface side 131 of the annular tight-fitting link 103 has a nearly right-angle stepped surface 137 between the starting end 135 of the inclined surface, which has a small thickness, and the adjacent ending end 136 of the inclined surface, which has a large thickness, with a height difference where the thickness changes abruptly. When this stepped surface 137 contacts the lower wall surface 24c of the end of the groove bottom surface 24a of the engagement groove 24 of the ring-shaped support 2, the annular tight-fitting link 103 is prevented from rotating in the reverse direction.

[0061] The anti-reverse rotation stepped inclined surface 133 is formed by a series of short inclined surfaces 134a with a small length, and on the remaining inner circumferential surface side 131, for example, two long inclined surfaces 134b with a large length are formed consecutively. The series of short inclined surfaces 134a are formed consecutively for about one-third of the total circumference of the inner circumferential surface side 131, for example, six of them. The long inclined surfaces 134b are formed consecutively for about two-thirds of the total circumference of the inner circumferential surface side 131, for example, two of them.

[0062] The thickness of each of the multiple short inclined surfaces 134a gradually increases toward the adjacent inclined surface end 136 in the same direction, with the short inclined surface 134a located closest to the end having the largest thickness. Conversely, the thickness of the short inclined surfaces 134a located closest to the beginning has the smallest thickness.

[0063] Similarly, the thickness of each long inclined surface 134b gradually increases towards the adjacent inclined surface end 136 in the same direction, with the thickness being greatest at the inclined surface end 136 located on the end side. Conversely, the thickness of the long inclined surface 134b is smallest at the inclined surface start end 135 located on the start side. The length of the inclined surface 134b of the long inclined surface 134b is longer than the length of the inclined surface 134 of the short inclined surface 134a, for example, about six times longer.

[0064] The stepped inclined surface 133 formed on the inner circumferential surface 131 of the annular tight-fitting link 103 serves to prevent the outer tube 51, whose inner circumferential surface 51a is in close contact with the outer circumferential surface 132 of the annular tight-fitting link 103, from rotating in the reverse direction, loosening, and vibrating.

[0065] In other words, when the annular contact link 103, which is in close contact with the inner circumferential surface 51a of the outer tube 51, attempts to rotate in the same opposite direction as the outer tube 51, some of the stepped surfaces 137 of the stepped inclined surface 133 for preventing reverse rotation, which is formed on the inner circumferential surface side 131 of the annular contact link 103, come into contact with the lower wall surface 24c of the end of the groove bottom surface 24a of the engagement groove 24 of the ring-shaped support 2 fixed to the inner tube 52, thereby preventing the annular contact link 103 from rotating in the same opposite direction.

[0066] The annular tight link 103 is prevented from rotating in the same opposite direction by the stepped surface 137 of the anti-reverse rotation stepped inclined surface 133. However, since the inner circumferential surface 51a of the outer tube 51 is in close contact with the outer circumferential surface side 132 of the annular tight link 103, the outer tube 51 is prevented from rotating in the opposite direction by the non-rotating annular tight link 103. This prevents the outer tube 51 from loosening and causing the inner tube 52 to vibrate through the ring-shaped support 2 fixed to the inner tube 52 and the annular tight link 103.

[0067] The annular contact link 103 has a constant width and is sized to fit into the engagement groove 24 as described above, but the thickness of the annular contact link 103 is not constant, and the inner circumferential surface side 131 is formed with multiple stepped inclined surfaces 133 for preventing reverse rotation, which are formed in a continuous manner in the same direction and are not circular. The groove height of the side wall surface 24b of each engagement groove 24 is smaller than the overall thickness of the annular contact link 103, that is, smaller than the thickness of the thinnest part, and the outer circumferential surface side 132 of the annular contact link 103 always protrudes a portion from each engagement groove 24.

[0068] Therefore, each support piece 23 of the ring-shaped support 2, which has an engagement groove 24 formed on its tip side, does not have its tip directly in contact with the inner circumferential surface 51a of the outer tube 51. In other words, the outer circumferential surface side 132 of the annular tight-fitting link 103 contacts the inner circumferential surface 51a of the outer tube 51, preventing the tips of each support piece 23 from directly contacting the inner circumferential surface 51a of the outer tube 51.

[0069] The non-circular inner surface side 131 of the annular tight link 103 has a long inner radius 131a, which is the largest radius, and a short inner radius 131b, which is the smallest radius, at a radial distance from the center of the annular tight link 103. The long inner radius 131a is at the inclined surface end 133c of the anti-reverse rotation stepped inclined surface 133, and the short inner radius 131b is at the inclined surface start 133b of the anti-reverse rotation stepped inclined surface 133.

[0070] Since the outer surface side 132 of the annular tight link 103 is circular and the inner surface side 131 is non-circular, the thickness of the annular tight link 103 is smallest when the inner surface side 131 is located at the long inner radius 131a, and the thickness is largest when the inner surface side 131 is located at the short inner radius 131b.

[0071] In contrast, when the inner circumferential surface side 131 of the flexible annular tight-fitting link 103 is located within the engagement groove 24 of the support piece 23, the thickness corresponding to the short inner radius 131b portion is greatest. As a result, the outer circumferential surface side 132 of the flexible annular tight-fitting link 103 deforms outward, and the deformed outer shape of that portion becomes the virtual long outer radius with the greatest distance from the center of the fitting hole 21 of the annular ring 22 of the ring-shaped support 2.

[0072] When the annular contact link 103 is not positioned at the location of each support piece 23, its outer surface side 132 has a circular shape. However, when the annular contact link 103 is fitted into the engagement groove 24 of each support piece 23, the flexible annular contact link 103 is pressed outward at its inner surface side 131, causing its outer surface side 132 to deform into a rounded, non-circular shape.

[0073] In other words, the flexible annular tight-fitting link 103 is pressed radially outward by the groove bottom surface 24a in the engagement groove 24 at the tip of each support piece 23, which is at the same distance from the center of the fitting hole 21 of the annular ring 22 of the ring-shaped support 2, causing it to deform slightly.

[0074] As a result, the outer surface 132 of the annular tight-fitting link 103, which corresponds to the short inner radius 131b on the inner surface 131, is pressed and pushed out radially because the annular tight-fitting link 103 has a large thickness, and as described above, its thickness increases to become a virtual long outer radius.

[0075] Conversely, on the outer surface side 132 of the annular tight-fitting link 103, which corresponds to the long inner radius 131a on the inner surface side 131, the thickness of the annular tight-fitting link 103 is small, so the thickness that is pressed and pushed out radially is small, resulting in a virtual short outer radius.

[0076] Incidentally, the inner diameter of the inner circumferential surface 51a of the outer tube 51 is of a non-circular shape, having a long inner diameter 51b with the largest diameter and a short inner diameter 51c with the smallest diameter. For this reason, the virtual long outer radius of the outer surface side 132 of the deformable flexible annular tight-fitting link 103 is adjusted to be smaller than the long inner diameter 51b of the inner circumferential surface 51a of the outer tube 51 and larger than the short inner diameter 51c of the inner circumferential surface 51a of the outer tube 51.

[0077] Next, a method for attaching the double-tube support 101 to the inside of the double-tube 5, based on the configuration of Embodiment-2 for carrying out the above invention, will be described below.

[0078] The double-tube support 101 is fixed and attached to a predetermined location on the outer surface 52a of the inner tube 52 of the double-tube 5, before the outer tube 51 is attached. If the inner tube 52 is made of metal, the ring-shaped support 2 of the double-tube support 101 is fixed and attached by welding. If the inner tube 52 is made of plastic, the ring-shaped support 2 of the double-tube support 101 is fixed and attached by adhesive.

[0079] To attach the ring-shaped support 2 to the outer surface 52a of the inner tube 52, the fitting hole 21 in the center of the ring 22 of the ring-shaped support 2 is fitted onto the outer surface 52a of the inner tube 52, and the annular ring 22 is fixed by welding or adhesive. At this time, to facilitate the subsequent rotation of the annular tight-fitting link 103, it is attached to the end of the outer tube 51 that will be attached to the outer circumference of the inner tube 52.

[0080] Subsequently, the inner surface side 131 of the annular tight-fitting link 103 is attached to the engagement grooves 24 of the multiple support pieces 23 formed at equal intervals in the circumferential direction of the ring-shaped support 2. At this time, the annular tight-fitting link 103 is attached so that the thinnest parts of the inner surface side 131a of the annular tight-fitting link 103 are positioned at the bottom surface 24a of the engagement groove 24 of each support piece 23.

[0081] In other words, when the outer pipe 51 is installed on the outer circumferential surface 52a side of the inner pipe 52, the piping is installed so that the virtual long outer radius of the annular tight link 103 attached to the outer circumferential surface 52a side of the inner pipe 52 does not come into contact with the long inner diameter 51b portion of the outer pipe 51, which has a larger diameter. At this time, the locations of the short inner radii 131b where the thickness of the inner circumferential surface side 131 of the annular tight link 103 is large are installed in intermediate positions where the support pieces 23 are not located.

[0082] After the outer tube 51 is fitted onto the inner tube 52, the annular tight-fitting link 103, which is attached to the outer circumference of the ring-shaped support 2 on the outer circumference surface 52a side of the inner tube 52, is rotated in the circumferential direction on the outer circumference surface 52a side of the inner tube 52. As the flexible annular tight-fitting link 103, which is fitted into the engagement groove 24 of the support piece 23, rotates, it is pressed and deformed by the groove bottom surface 24a of the engagement groove 24 of the support piece 23, causing the outer circumference surface side 132 at the virtual long outer radius point to come into contact with the short inner diameter 51c of the inner circumference surface 51a of the outer tube 51 and to adhere tightly.

[0083] At this time, since multiple stepped inclined surfaces 133 for preventing reverse rotation are formed on the inner circumferential surface side 131 of the annular tight link 103, the annular tight link 103 is rotated from the inclined surface start end 135 side, which has less thickness, to the inclined surface end end 136 side, which has more thickness, so that the stepped surface 137 of the inclined surface 134 does not hinder the rotation of the annular tight link 103.

[0084] The outer surface side 132 of the annular contact link 103 is in close contact with the short inner diameter 51c of the inner surface 51a of the outer tube 51, so that the outer tube 51 and the inner tube 52 are fixed together via the multiple support pieces 23 and the annular contact link 103, preventing the outer tube 51 and the inner tube 52 from vibrating relative to each other.

[0085] In other words, as the inner surface side 131 of the annular contact link 103 rotates along the engagement grooves 24 of each support piece 23 of the ring-shaped support 2, the thick portion of the inner surface side 131 of the annular contact link 103 with a short inner radius 131b is pressed toward the outer surface side 132 by the groove bottom surface 24a of the engagement groove 24 of the support piece 23, and this portion comes into close contact with the inner surface 51a of the outer tube 51. The rotating annular contact link 103 is sandwiched between the outer tube 51 and the inner tube 52, causing them to come into close contact and preventing vibration of the outer tube 51 and the inner tube 52.

[0086] As mentioned above, the stepped inclined surface 133 for preventing reverse rotation, formed on the inner circumferential surface 131 of the annular tight-fitting link 103, prevents the outer tube 51 from rotating in the reverse direction and prevents the outer tube 51 and the inner tube 52 from vibrating in the following manner.

[0087] In other words, when the annular contact link 103, which is in close contact with the inner circumferential surface 51a of the outer tube 51, attempts to rotate in the same opposite direction as the outer tube 51, some of the stepped surfaces 137 of the stepped inclined surface 133 for preventing reverse rotation, which is formed on the inner circumferential surface side 131 of the annular contact link 103, come into contact with the lower wall surface 24c of the end of the groove bottom surface 24a of the engagement groove 24 of the ring-shaped support 2 fixed to the inner tube 52, thereby preventing the annular contact link 103 from rotating in the same opposite direction.

[0088] The annular tight link 103 is prevented from rotating in the same opposite direction by the stepped surface 137 of the anti-reverse rotation stepped inclined surface 133. However, since the inner circumferential surface 51a of the outer tube 51 is in close contact with the outer circumferential surface side 132 of the annular tight link 103, the outer tube 51 is prevented from rotating in the opposite direction by the non-rotating annular tight link 103. Through the ring-shaped support 2 fixed to the inner tube 52 and the annular tight link 103, the outer tube 51 prevents vibration of the inner tube 52.

[0089] It should be noted that this invention is not limited to embodiments 1 and 2 described above, and various modifications can be made without departing from the spirit of this invention. [Explanation of Symbols]

[0090] 1. Double-tube support device 101 Double-tube support device 2 Ring-shaped support 21 Fitting holes 22 rings 23 Support piece 24 Engagement groove 24a Groove bottom surface 24b Side wall 24c End lower wall surface 3. Ring-shaped tight link 31 Inner surface side 31a major radius 31b Short inner radius 32 Outer surface side 103 Ring-shaped tight link 131 Inner surface side 131a major radius 131b Short inner radius 132 Outer surface side 133 Stepped inclined surface for preventing reverse rotation 134 Inclined surface 134a short inclined surface 134b long slope surface 135 Starting point of inclined surface 136 Sloped surface termination 137 Step surface 5 double tube 51 Outer tube 51a Inner surface 51b Long inner diameter 51c short inner diameter 52 Inner tube 52a Outer surface

Claims

1. In a double-walled pipe having an outer pipe and an inner pipe piped inside it, a ring-shaped support having a plurality of support pieces protruding at equal intervals in the circumferential direction is fixedly attached to the outer circumferential surface of the inner pipe of the double-walled pipe, an engagement groove having a groove bottom surface equidistant from the center of the ring-shaped support in the circumferential direction is formed on the tip side of the protrusion of each support piece, and a flexible annular tight-fitting link having a circular outer circumferential surface side having an outer diameter smaller than the inner diameter of the outer pipe and a plurality of non-circular inner circumferential surface sides of different thicknesses is rotatably mounted in the engagement groove of each support piece of the ring-shaped support, A double-tube support device characterized by pressing the inner surface side of the thicker portion of the annular contact link, which rotates along the engagement groove, toward the outer surface side with the engagement groove, thereby bringing the outer surface side of the pressed annular contact link into close contact with the inner surface of the outer tube.

2. The double-tube support according to claim 1, wherein the annular tight-fitting link, which rotates along the engagement groove, has an outer tube having a non-circular cross-section in which the inner surface consists of a long inner diameter and a short inner diameter, and the outer surface side of the annular tight-fitting link contacts a part of the non-circular inner surface of the rotating outer tube and rotates in the same direction during the rotation of the outer tube.

3. The double-tube support device according to claim 1, wherein the outer surface of the annular contact link has a circular shape, and the inner surface of the annular contact link is formed in a rounded, non-circular shape with alternating sections of different thicknesses.

4. The double-tube support according to claim 1, wherein the outer surface of the annular contact link has a circular shape, and the inner surface of the annular contact link is formed in a rounded, non-circular shape with alternating sections of different thicknesses, and a plurality of sections of different thicknesses are formed at equal intervals in the circumferential direction.

5. The double-tube support device according to claim 1, wherein the outer surface of the annular contact link has a circular shape, and the inner surface of the annular contact link is formed as a rounded non-circular shape with alternating sections of different thicknesses, multiple sections of different thicknesses are formed at equal intervals in the circumferential direction, and the number of sections with large thicknesses and sections with small thicknesses is the same as the number of support pieces for each of the ring-shaped support.

6. The double-tube support according to claim 1, wherein the outer surface of the annular contact link has a circular shape, and the inner surface of the annular contact link has multiple stepped inclined surfaces for preventing reverse rotation formed in the same direction, each consisting of a gently sloping surface with gradually increasing thickness, a starting end of the inclined surface with a small thickness, a terminal end of the inclined surface with a large thickness, and a stepped surface with a height difference where the thickness changes abruptly from the terminal end to the adjacent starting end of the inclined surface.

7. The outer surface of the annular contact link has a circular shape, and on the inner surface of the annular contact link, a plurality of stepped inclined surfaces for preventing reverse rotation are formed in the same direction, each consisting of a gently sloping surface with gradually increasing thickness, an inclined surface start end with a small thickness that serves as the starting end of the inclined surface, an inclined surface end with a large thickness that serves as the ending end of the inclined surface, and a stepped surface with a height difference where the thickness changes abruptly from the inclined surface end to the adjacent inclined surface start end, and the stepped inclined surfaces for preventing reverse rotation are formed by a plurality of short inclined surfaces of small length in succession, and the remaining inner surface has a long inclined surface of large length in succession, as described in claim 1.

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