Pipe end caps

Abstract

To improve the sealing performance of an inner tube and a corrugated tube of a composite tube having the corrugated tube with holding protrusions at tube-holding, or tube-laying to an underfloor, and to prevent a positional displacement in a tube axial direction.SOLUTION: A tube end cap 30 for use in a composite tube 1 which comprises a telescopic flexible corrugated tube 20 in which a crest part 21 and a trough part 22 are alternately formed in a tube axial direction, and an average wall thickness of the crest part 21 is equal to or thicker than 0.4 mm, and a flexible inner tube 10 cladded by the corrugated tube 20, and in which the corrugated tube 20 has elasticity, and holding protrusions 23 contacting with an external peripheral face of the inner tube 10 are formed at its internal peripheral face so as to be distributed in the tube axial direction and a circumferential direction has: a cylindrical cap part 31 fit to an outer face of the inner tube 10; a plate-shaped part 32 having introduction tapered parts 32a diagonally and protrusively arranged in a plurality of directions at an outer face of the cap part 31, and formed into a triangle shape, or a trapezoidal shape, or a shape which is formed by deforming the triangle shape and the trapezoidal shape; and a cap terminal end block part 33 for blocking a terminal end part of the cap part 31.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a pipe end cap for a composite pipe formed by covering an inner pipe with a corrugated pipe.

Background Art

[0002] Flexible resin pipes made of cross-linked polyethylene or polybutene are widely used as pipes for detached houses and apartment rooms. Recently, they have also been increasingly used as pipes for renovating old houses. In the case of a detached house, since it can be laid under the floor, the construction method for renovation is not much different from that for new construction. However, in the case of an apartment, since it cannot be laid under the floor, some characteristic construction methods have been proposed for apartment renovation.

[0003] Patent Document 1 proposes a method of partially opening a floorboard and passing a flexible resin pipe therethrough. Particular research has been conducted on covering the inner pipe with a protective member having expansion and contraction properties and covering the surface of the protective member with a covering material by compression. Therefore, further research is required for the application of a corrugated pipe coating to a protective pipe with a cover.

[0004] Patent Document 2 assumes a protective pipe with a corrugated pipe coating. However, since the locking portions of the corrugated pipe are distributed in the circumferential direction, it is not suitable for those having a sound-absorbing tape-shaped foam intermediate layer or a form in which protrusions project from the inner surface.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The locking mechanism described in Patent Document 2 is effective when the corrugated portion is somewhat rigid, but with materials of low strength, it cannot be securely fitted unless it protrudes at least in a cross shape, deforming the corrugated tube.

[0007] Furthermore, if there are intermediate layers or retaining protrusions inside, the protrusions need to be positioned to reduce these resistances or to avoid the retaining protrusions.

[0008] The present invention has been made in view of the above problems, and its object is to provide a pipe end cap that can improve the airtightness between the inner pipe and the corrugated pipe of a composite pipe equipped with a retaining projection and prevent misalignment in the pipe axis direction. [Means for solving the problem]

[0009] To solve the aforementioned problems, the present invention provides a pipe end cap for use in a composite pipe comprising: a flexible corrugated pipe having alternating peaks and valleys in the direction of the pipe axis, with an average wall thickness of 0.4 mm or more for the peaks; and a flexible inner pipe covered by the corrugated pipe, wherein the corrugated pipe is expandable and expandable, and retaining protrusions that contact the outer surface of the inner pipe are distributed in the direction of the pipe axis and circumferentially on its inner circumferential surface, the end cap comprising: a cylindrical cap portion that fits onto the outer surface of the inner pipe; a plate-like portion having a triangular, trapezoidal, or deformed thereof shape with introduction tapered portions protruding in multiple directions and diagonally on the outer surface of the cap portion; and a cap end closing portion that closes the end portion of the cap portion. [Effects of the Invention]

[0010] According to the present invention, it is possible to improve the airtightness between the inner tube and the corrugated tube of a composite tube equipped with a retaining projection, and to prevent misalignment in the axial direction of the tube. [Brief explanation of the drawing]

[0011] [Figure 1] This is a partial cross-sectional view of a composite pipe. [Figure 2] This is an enlarged detail view of section A in Figure 1. [Figure 3]It is a sectional view taken along line B-B of FIG. 2. [Figure 4] It is a perspective view of the pipe end cap according to the first embodiment of the present invention. [Figure 5] It is a half-cut side sectional view of the pipe end cap according to the first embodiment of the present invention. [Figure 6] It is a sectional view taken along line C-C of FIG. 5. [Figure 7] It is a side view of the pipe end cap according to the second embodiment of the present invention. [Figure 8] It is a half-cut side sectional view of the pipe end cap according to the second embodiment of the present invention. [Figure 9] It is a side view of the pipe end cap according to the third embodiment of the present invention. [Figure 10] It is a half-cut side sectional view of the pipe end cap according to the third embodiment of the present invention. [Figure 11] It is a side view of the pipe end cap according to the fourth embodiment of the present invention. [Figure 12] It is a half-cut side sectional view of the pipe end cap according to the fourth embodiment of the present invention. [Figure 13] (a) to (c) are side views showing various forms of the pipe end cap according to the fourth embodiment of the present invention, and (d) is a half-cut side sectional view. [Figure 14] It is a side view of the pipe end cap according to the fifth embodiment of the present invention. [Figure 15] It is a view in the direction of arrow D in FIG. 14.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described based on the accompanying drawings.

[0013] [Composite Pipe] First, the basic configuration of the composite pipe in which the pipe end cap according to the present invention is used will be described based on FIGS. 1 to 3.

[0014] As shown in Fig. 1, the composite pipe 1 includes a flexible inner pipe 10 and a flexible corrugated pipe (corrugated tube) 20 that covers the inner pipe 10. This composite pipe 1 is used, for example, as a pipe for water supply and hot water supply. In this case, the inside of the inner pipe 10 becomes a fluid passage through which fluids such as water and hot water pass.

[0015] The inner pipe 10 is formed with a constant circular cross-section over its entire length and has flexibility. As this inner pipe 10, a cross-linked polyethylene (PE-X) pipe, a polybutene (PB) pipe, a polyethylene (PE) pipe, a heat-resistant polyethylene (PE-RT) pipe, or a resin pipe containing two or more of these resins can be used. Also, a metal-reinforced resin pipe containing at least one of the above resins and metal can be used. Note that the above is an example, and there is no particular limitation on the material of the inner pipe 10 as long as it can ensure the required performance such as flexibility and fluid flowability.

[0016] The corrugated pipe 20 is made of a single-layer resin pipe, and a polyethylene (PE) pipe, a cross-linked polyethylene (PE-X) pipe, a polybutene (PB) pipe, a heat-resistant polyethylene (PE-RT) pipe, or a resin pipe containing two or more of these resins can be used. Also, the flexibility of the corrugated pipe 20 may be improved by foaming. In this case, it is preferable to use polyethylene (PE) as the main component and to have a low foaming with a foaming ratio of 1.05 to 4 times. Note that the above is an example, and there is no particular limitation on the material of the corrugated pipe 20 as long as it can ensure the required performance such as flexibility and protection for the inner pipe 10.

[0017] As shown in Figs. 1 and 2, the corrugated pipe 20 has a corrugated cross-section by arranging annular ridges 21 and annular valleys 22 alternately at the same pitch in the pipe axis direction. As shown in Fig. 2, the ridge 21 has a short cylindrical shape with a constant diameter, and the cross-sectional shape of the valley 22 is U-shaped or V-shaped. Here, one pitch P is defined as the dimension in the pipe axis direction including one ridge 21 and one valley 22. Also, the average wall thickness of the ridge 21 is set to be 0.4 mm or more.

[0018] The corrugated tube 20 further has retaining protrusions 23 that are distributed in the axial direction and circumferential direction and are independent of each other. In this embodiment, four retaining protrusions 23 are formed at equally spaced locations in the axial direction, and at equally spaced locations in the circumferential direction. Here, the retaining protrusions 23 protrude radially inward from the valleys 22, and their tips 230 are in contact with or close to the outer circumference of the inner tube 10, thereby holding the inner tube 10 substantially concentrically with the axial direction of the corrugated tube 20.

[0019] As shown in Figure 2, the retaining projection 23 has a pair of first side walls 231, 231 facing each other in the direction of the pipe axis, and as shown in Figure 3, it has a pair of second side walls 232, 232 facing each other in the direction of the circumferential axis. The pair of first side walls 231, 231 are inclined to approach each other in the radially inward direction, so that the cross section of the retaining projection 23 along the direction of the pipe axis is V-shaped. Similarly, the second side walls 232, 232 are inclined to approach each other in the radially inward direction, so that the cross section of the retaining projection 23 perpendicular to the pipe axis is approximately V-shaped. In this embodiment, the shape of the tip 230 of the retaining projection 23 as viewed from the direction of the pipe axis is a convex curve.

[0020] As shown in Figure 2, the axial dimension L of the retaining projection 23 is greater than or equal to the length of the short cylindrical section and longer than 25% of one pitch P, and in this embodiment, it is set to approximately 1.5P. The retaining projection 23 is formed so as to traverse one peak 21 and two valleys 22 in the axial direction of the pipe. The axial center of the retaining projection 23 coincides with the axial position of the one peak 21. The pair of first side walls 231 are symmetrical with respect to the axial center of the retaining projection 23 and are inclined at the same angle. The inclination angle θ1 of the first side walls 231 with respect to a plane perpendicular to the pipe axis is 5° or more, and in this embodiment, it is set to approximately 30°. The roots 231a of the pair of first side walls 231 of the retaining projection 23 are connected to the two peaks 21 adjacent to the two valleys 22 that traverse it.

[0021] As shown in Figure 3, the pair of second side walls 232 of the retaining projection 23 are symmetrical with respect to the circumferential center of the retaining projection 23 and are inclined at the same angle. The inclination angle θ2 of the second side walls 232 with respect to the plane containing the pipe axis is 5° or more, and in this embodiment, it is set to approximately 45°. The base 232a of the second side walls 232 is connected to one peak 21 and two valleys 22 that the retaining projection 23 crosses, forming a wave shape.

[0022] The corrugated tube 20 can suppress rattling of the inner tube 10 and reduce noise, as well as improve heat retention, by having the retaining protrusions 23 concentrically hold the inner tube 10. Since the retaining protrusions 23 are distributed in the direction of the tube axis, they do not affect the expansion and contraction of the corrugated tube 20 in the direction of the tube axis. In addition, since the retaining protrusions 23 are distributed in the circumferential direction, the risk of structures getting caught on them can be reduced.

[0023] Furthermore, since the pair of first side walls 231 have an inclination angle θ1 greater than 5° (approximately 30° in this embodiment) and form a V-shaped cross-section, with their bases 231a connected to the peaks 21, and the pair of second wall portions 232 have an inclination angle θ2 greater than 5° (approximately 45° in this embodiment) and form a V-shaped cross-section, with their bases 232a connected to one peak 21 and two valleys 22, the radial compressive strength can be further increased.

[0024] As described above, the retaining projection 23 is set independently of the groove width of the valley section 22. In other words, the groove width of the valley section 22 does not need to be forcibly widened in order to increase the dimension of the retaining projection 23 in the pipe axis direction. Therefore, the groove width of the valley section 22 can be limited to a width that prevents the corners of structures from getting caught, for example, the groove width of the valley section 22 can be set to 35% or less of one pitch P. However, in order to ensure expansion and contraction in the pipe axis direction (to ensure compression allowance), the groove width of the valley section 22 is set to 25% or more of one pitch P. In this embodiment, the groove width of the valley section 22 is set to approximately 30% of one pitch P. This makes it possible to easily shorten a 200 mm corrugated pipe 20 by 50 mm or more.

[0025] To prevent the corners of the structure from reaching the back of the valley 22, the groove depth of the valley 22 is made greater than the groove width. Also, the depth of the recess of the retaining projection 23, which is roughly square pyramidal, is made greater than the groove width of the valley 22. [Tube end caps] Next, an embodiment of the pipe end cap used in the composite pipe 1 described above will be explained.

[0026] <First Embodiment> As shown in Figures 4 to 6, the pipe end cap 30 according to the first embodiment of the present invention is fitted onto one axial end of the inner pipe 10 of the composite pipe 1 (see Figure 5), and is composed of a bottomed cylindrical cap portion 31 whose inner circumferential surface fits onto the outer circumferential surface of the inner pipe 10, four plate-like portions 32 that extend integrally radially outward from the outer circumference of the cap portion 31, and a disc-shaped cap end closing portion 33 that closes one axial end of the cap portion 31 (see Figure 5).

[0027] In this embodiment, the four plate-like portions 32 are arranged vertically and horizontally at equal angular pitches (90° pitches) in the circumferential direction. Therefore, these plate-like portions 32 pass through the circumferential gap between the four retaining projections 23 (see Figures 1 to 3) that protrude radially inward from the corrugated tube 20, in the direction of the tube axis, so that the plate-like portions 32 and the retaining projections 23 do not interfere with each other. As a result, the tube end cap 30 can be smoothly fitted onto the outer circumference of one axial end of the inner tube 10 without interfering with the corrugated tube 20.

[0028] Here, each plate-shaped portion 32 has an introduction tapered portion (first tapered portion) 32a, a first parallel portion 32b extending parallel to the pipe axis direction from the introduction tapered portion 32a, a second tapered portion 32c extending diagonally outward in the radial direction from the pipe axis direction end of the first parallel portion 32b, and a second parallel portion 32d extending horizontally along the pipe axis direction from the second tapered portion 32c. Here, the circumscribed circle diameter of the first parallel portion 32b of the plate-shaped portion 32 is set to be the same as the inner diameter of the valley portion 22 of the corrugated pipe 20, and the circumscribed circle diameter of the second parallel portion 32d is set to an intermediate value between the inner diameter of the valley portion 22 and the outer diameter of the peak portion 21 of the corrugated pipe 20.

[0029] As shown in Figure 5, the pipe end cap 30, configured as described above, is attached to one axial end of the inner pipe 10 by fitting the inner circumference of the cap portion 31 onto the outer circumference of the inner pipe 10 and pushing it in the axial direction (to the left in Figure 5). When the pipe end cap 30 is fitted onto the outer circumference of the inner pipe 10 in this way, the opening at one axial end of the inner pipe 10 is closed by the cap end closing portion 33 of the pipe end cap 30.

[0030] Furthermore, as described above, when the pipe end cap 30 is attached to one axial end of the inner pipe 10, as shown in Figure 5, the first parallel portion 32b of each plate-shaped portion 32 of the pipe end cap 30 fits into the inner circumference of the valley portion 22 of the corrugated pipe 20, positioning the corrugated pipe 20 radially, and the second parallel portion 32d of each plate-shaped portion 32 enters into the ridge portion 21 of the corrugated pipe 20, thereby preventing the corrugated pipe 20 from coming out of the inner pipe 10. Therefore, the airtightness between the inner pipe 10 and the corrugated pipe 20 of the composite pipe 1 equipped with the retaining projection 23 is improved, and misalignment of the corrugated pipe 20 and the inner pipe 10 in the pipe axis direction is reliably prevented.

[0031] <Second Embodiment> As shown in Figure 7, the pipe end cap 40 according to the second embodiment of the present invention is characterized in that the shape of the four plate-like portions 42 that are integrally projected radially outward from the outer circumference of the cap portion 41 is a right triangle. Here, the maximum circumscribed circle diameter of the acute-angled end of each plate-like portion 42 is set to a value midway between the inner diameter of the valley portion 22 and the inner diameter of the peak portion 21 of the corrugated pipe 20.

[0032] Therefore, in the pipe end cap 40 according to this embodiment, when the pipe end cap 40 is fitted and attached to the outer circumference of the inner pipe 10 as shown in Figure 8, the introduction tapered portion 42a of each plate-shaped portion 42 engages with the inner circumference of the valley portion 22 of the corrugated pipe 20, improving the tight seal between the corrugated pipe 20 and the inner pipe 10. In addition, the corners of the maximum diameter of each plate-shaped portion 42 of the pipe end cap 40 fit into the recesses of the peak portion 21 of the corrugated pipe 20, preventing the corrugated pipe 20 from coming out of the inner pipe 10. As a result, the airtightness between the inner pipe 10 and the corrugated pipe 20 of the composite pipe 1 equipped with the retaining projection 23 is improved, and misalignment of the corrugated pipe 20 and the inner pipe 10 in the pipe axis direction is reliably prevented.

[0033] <Third Embodiment> As shown in Figure 9, the pipe end cap 50 according to the third embodiment of the present invention has a shape that combines the shapes of the plate-shaped portion 32 according to the first embodiment and the plate-shaped portion 42 according to the second embodiment, with each plate-shaped portion 52 protruding from the outer circumference of the cap portion 51. That is, the plate-shaped portion 52 of the pipe end cap 50 according to this embodiment has an introduction tapered portion 52a, a first parallel portion 52b, and a second tapered portion 52c formed thereon.

[0034] Therefore, in the pipe end cap 50 according to this embodiment, when the pipe end cap 50 is fitted and attached to the outer circumference of the inner pipe 10 as shown in Figure 10, the first parallel portion 52b of each plate-shaped portion 52 engages with the inner circumference of the valley portion 22 of the corrugated pipe 20, thereby improving the tight seal between the corrugated pipe 20 and the inner pipe 10. In addition, the corner of the second tapered portion 52c of each plate-shaped portion 52 of the pipe end cap 50, which has the largest diameter, fits into the recess of the peak portion 21 of the corrugated pipe 20, thereby preventing the corrugated pipe 20 from coming out of the inner pipe 10. As a result, the airtightness between the inner pipe 10 and the corrugated pipe 20 of the composite pipe 1 equipped with the corrugated pipe 20 having the retaining projection 23 is improved, and misalignment of the corrugated pipe 20 and the inner pipe 10 in the pipe axis direction is reliably prevented.

[0035] <Fourth Embodiment> The pipe end cap 60 according to the fourth embodiment is characterized in that, as shown in Figure 11, each plate-like portion 62 is trapezoidal in shape, and a disc 63 serving as a cap end closing portion is integrally formed at one axial end of the cap portion 61 (the right end in Figure 11). Here, the outer diameter of the disc 63 is set to be larger than the outer diameter of the valley portion 22 of the corrugated pipe 20.

[0036] Therefore, when the pipe end cap 60 according to this embodiment is fitted and attached to the outer circumference of the inner tube 10 as shown in Figure 12, the opening at one end of the corrugated tube 20 is securely closed by the disc 63 of the pipe end cap 60. In addition, the parallel portions 62b of each plate-shaped portion 62 engage with the inner circumference of the valley portions 22 of the corrugated tube 20, increasing the airtightness between the corrugated tube 20 and the inner tube 10, and the outer circumference of the disc 63 fits into the recesses of the peak portions 21 of the corrugated tube 20, preventing the corrugated tube 20 from coming out of the inner tube 10. As a result, the opening at one end of the corrugated tube 20 is securely closed by the disc 63 of the pipe end cap 60, and the airtightness between the inner tube 10 and the corrugated tube 20 of the composite tube 1 equipped with the corrugated tube 20 having a retaining projection 23 is improved. Furthermore, misalignment of the corrugated tube 20 and the inner tube 10 in the pipe axis direction is reliably prevented.

[0037] Here, various forms of pipe end caps 60 according to this embodiment can be considered, as shown in Figures 13(a) to (d).

[0038] In other words, in the pipe end cap 60A shown in Figure 13(a), the cap portion 61 penetrates the disc 63, with one end protruding axially from the disc 63. In the pipe end cap 60B shown in Figure 13(b), a predetermined gap is formed between the plate-like portion 62 and the disc 63, and a part of the plate-like portion 62 is connected to the disc 63. In the pipe end cap 60C shown in Figure 13(c), the plate-like portion 62 and the disc 63 are not connected.

[0039] Furthermore, in the pipe end cap 60D shown in Figure 13(d), the disc 63 is composed of a stepped large-diameter portion 63a and a small-diameter portion 63b. When the pipe end cap 60D is attached to the inner tube 10 of the composite tube 1, the large-diameter portion 63a of the disc 63 closes the axial opening at one end of the corrugated tube 20, and the small-diameter portion 63b closes the axial opening at one end of the inner tube 10.

[0040] <Fifth Embodiment> As shown in Figure 14, the pipe end cap 70 according to the fifth embodiment has a tapered guide projection 74 protruding from the end face of a disc 73 integrally formed with the cap 71, and this guide projection 74 functions as a guide during the installation of the composite pipe 1. Here, the guide projection 74 is constructed by radially projecting four triangular ribs 74a from the end face of the disc 73 at equal angular pitches (90° pitches) in the circumferential direction. In addition, in the pipe end cap 70 according to this embodiment, four plate-like portions 72 are radially projected from the outer circumference of the cap portion 71.

[0041] With the pipe end cap 70 according to this embodiment, similar to the pipe end cap 60 (60A to 60D) according to the fourth embodiment, the opening at one end of the corrugated pipe 20 is reliably closed by the disc 73, and the airtightness between the inner pipe 10 and the corrugated pipe 20 of the composite pipe 1, which is equipped with a retaining projection 23, is improved. Furthermore, misalignment of the corrugated pipe 20 and the inner pipe 10 in the pipe axis direction is reliably prevented.

[0042] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the technical idea described in the claims, specification, and drawings. [Industrial applicability]

[0043] This invention can be applied, for example, to the storage of water supply and hot water pipes or to terminal jigs used during pipe installation. [Explanation of Symbols]

[0044] 1 Composite pipe 10 Inner tube 20 corrugated tube 21 Yamabe 22 Tanibe 23 Retaining protrusion 30-70 pipe end caps 31-71 Cap section 32a Introductory tapered section 32-72 Plate-like section 33 Cap end closing part 63,73 Disc (Cap end closing part)

Claims

1. A pipe end cap for a composite pipe comprising a flexible corrugated pipe having alternating peaks and valleys formed in the axial direction of the pipe, with an average wall thickness of 0.4 mm or more for the peaks, and a flexible inner pipe covered by the corrugated pipe, wherein retaining protrusions are formed on the inner circumferential surface of the corrugated pipe such that they protrude radially inward from the valleys and contact the outer circumferential surface of the inner pipe, distributed in the axial and circumferential directions, A cylindrical cap portion that fits onto the outer surface of the inner tube, A cap end closing part that closes the end of the cap part, The cap portion comprises a plurality of plate-like portions that protrude from the outer surface of the cap portion at circumferential intervals and extend in the direction of the pipe axis, The plate-shaped portion is inserted into an annular space formed between the inner tube and the inner circumference of the valley portion of the corrugated tube, and is characterized by having an introduction tapered portion that guides the corrugated tube during insertion, and a holding portion that is connected to the introduction tapered portion and in contact with the inner circumference of the valley portion of the corrugated tube to hold the corrugated tube.

2. The pipe end cap according to claim 1, characterized in that the retaining portion extends parallel to the pipe axis direction.

3. The pipe end cap according to Claim 1, characterized in that the plate-like portion has a maximum diameter portion on the opposite side of the introduction tapered portion when viewed from the holding portion, and the maximum diameter portion fits into the peak portion at the end of the corrugated pipe.

4. The pipe end cap according to claim 3, characterized in that the plate-like portion has a second tapered portion on the opposite side of the introduction tapered portion when viewed from the holding portion, and the corner of this second tapered portion is provided as the maximum diameter portion.

5. The pipe end cap according to claim 3, characterized in that the maximum diameter portion of the plate-like portion forms a surface that extends in the axial direction.

6. The pipe end cap according to claim 3, characterized in that the shape of the plate-like portion is a right-angled triangle having a straight inclined portion, the inclined portion includes the introduction tapered portion and the holding portion, and the corner of the right-angled triangle is provided as the maximum diameter portion.

7. The pipe end cap according to claim 1, characterized in that the cap end closing portion is composed of a disc having an outer diameter larger than the inner diameter of the valley portion of the corrugated pipe, and the outer circumference of the disc fits into the peak portion at the end of the corrugated pipe.

8. The pipe end cap according to claim 7, characterized in that the disc is connected to the plate-shaped portion.

9. The pipe end cap according to claim 7, characterized in that a tapered guide projection is provided on the end face of the disc opposite to the inner tube.

10. The pipe end cap according to claim 1, characterized in that the plate-like portion is positioned at an angular position in the circumferential direction that does not interfere with the retaining projection of the corrugated pipe.

Images