Resin pipe equipped with seal material

Abstract

Provided is a resin pipe, equipped with a seal material, which is capable of stably ensuring excellent sealing properties for a long period of time. Among a plurality of annular grooves 6a, 6b that are formed, at an interval in the pipe axial direction, in the outer circumferential surface of a connection end 5 of a resin pipe 2, an annular seal material 8a disposed in the forefront annular groove 6a located closest to the pipe edge of the connection end 5 is configured to have an amount of projection P1 in the pipe radial direction from the outer circumferential surface of the connection end in a manner as to be smaller than an amount of projection P2 of an annular seal material 8b disposed in the other annular groove 6b. The resin pipe 1 is connected with and secured to a connection object 11 by inserting the connection end 5 into a connection hole 11a formed in the connection object 11. As compared to said one seal material 8a, the other seal material 8b is more strongly pressed by the inner circumferential surface of the connection hole 11a, whereby a gap S between the outer circumferential surface of the connection end 5 and the inner circumferential surface of the connection hole 11a is sealed.

Description

Resin pipe with sealing material

[0001] The present invention relates to a resin pipe having a sealing material disposed at a connection end, and more particularly to a resin pipe with a sealing material that can stably ensure good sealing properties over a long period of time.

[0002] Resin pipes, which are lighter than metal pipes, are used for a variety of purposes. The connection end of a resin pipe is inserted into a connection hole of an object to be connected. A seal such as an O-ring is disposed on the outer periphery of the connection end, and this seal ensures a seal between the connection end and the connection hole (see, for example, Patent Document 1). When inserted into the connection hole, the connection end is pressed against the seal.

[0003] Compared to metal connection ends, resin connection ends have lower rigidity and are therefore more susceptible to deformation due to pressure. If the connection end deforms or is damaged more than expected, it will be difficult to adequately seal between the connection end and the connection hole. Patent Document 1 discloses placing two O-rings axially spaced apart at the connection end. However, simply increasing the number of O-rings may not ensure good sealing over the long term. Therefore, there is room for improvement in order to stably ensure good sealing over the long term.

[0004] Japanese Patent Application Publication No. 2010-249166

[0005] An object of the present invention is to provide a resin pipe with a sealing material that can stably ensure good sealing performance over a long period of time.

[0006] In order to achieve the above-mentioned object, the resin pipe with sealing material of the present invention comprises a resin pipe having a connection end that is inserted into a connection hole formed in an object to be connected, and annular sealing material that is disposed in each of a plurality of annular grooves formed at intervals in the pipe axial direction on the outer peripheral surface of the connection end of the resin pipe, wherein the amount of pipe radial protrusion from the outer peripheral surface of the connection end of the sealing material that is disposed in the most distal annular groove that is located closest to the pipe end of the connection end is set to be smaller than the amount of pipe radial protrusion from the outer peripheral surface of the connection end of the sealing material that is disposed in the annular groove that is located closer to the pipe end than the most distal annular groove.

[0007] According to the present invention, the radial protrusion of the sealing material disposed in the leading annular groove from the outer circumferential surface of the connection end is set smaller than the protrusion of the other sealing materials. This facilitates smooth insertion of the connection end into the connection hole compared to when the protrusions of each sealing material from the outer circumferential surface of the connection end are the same. This is advantageous for preventing damage to the sealing material disposed in the leading annular groove when inserting the connection end into the connection hole. Furthermore, the sealing material disposed in the leading annular groove is less likely to be excessively compressed, reducing stress over time and making it easier to ensure sealing performance over a long period of time. This is also advantageous for suppressing deformation of the resin pipe near the leading annular groove, thereby ensuring sealing performance over a long period of time. The other sealing materials bear a greater share of various external forces, allowing each sealing material to stably ensure good sealing performance over a long period of time.

[0008] FIG. 1 is an explanatory diagram illustrating the periphery of a connection end portion of a resin pipe with a sealant of the present invention in a vertical cross section. FIG. 2 is a view taken along arrow A in FIG. 1. FIG. 3 is an enlarged view of the annular groove and sealant in FIG. 1. FIG. 4 is an explanatory diagram illustrating the state in which the connection end portion of FIG. 1 is inserted into a connection hole and the resin pipe is connected and fixed to an object to be connected. FIG. 5 is an enlarged view of the annular groove and sealant in FIG. 4. FIG. 6 is an explanatory diagram illustrating the periphery of a connection end portion of another embodiment of a resin pipe with a sealant in a vertical cross section. FIG. 7 is an explanatory diagram illustrating the periphery of a connection end portion of yet another embodiment of a resin pipe with a sealant in a vertical cross section.

[0009] Hereinafter, a resin pipe with a sealing material according to the present invention will be described based on an embodiment shown in the drawings.

[0010] The embodiment of the resin pipe with sealing material 1 shown in Figures 1 to 3 includes a resin pipe 2 and a plurality of annular sealing materials 8 (8a, 8b). Various known sealing materials can be used as the sealing materials 8, such as O-rings made of various rubbers, including silicone rubber, or elastic materials, including elastomers. In this embodiment, the sealing materials 8a and 8b have the same specifications and a simple circular cross section.

[0011] This resin pipe 1 with a sealant is used as piping for various devices, such as air conditioners installed in vehicles such as automobiles. The resin pipe 2 may be straight or bent depending on the application (location of use). As will be described in detail later, as shown in FIG. 4, the connecting end 5 is inserted into a connecting hole (flow path) 11a formed in a connecting object 11, such as various devices or joint components, and the resin pipe 2 is connected to the connecting object 11. Note that in FIG. 3, the inner circumferential surface of the connecting hole 11a when the connecting end 5 is inserted into the connecting hole 11a is shown by a dashed line. A gap S exists between the outer circumferential surface of the connecting end 5 and the inner circumferential surface of the connecting hole 11a.

[0012] The resin pipe 2 is a cylinder having a pipe wall 3 made of resin, and a pipe line 4 extends in the pipe axis direction. Fluid flows through the pipe line 4 and the connection hole 11a. The tip of the resin pipe 2 in the pipe axis direction is the connection end 5. The dashed-dotted line CL in the figure indicates the axis of the resin pipe 2, which passes through the center of the cross section of the pipe line 4. The extension direction of the axis line CL is the pipe axis direction. The inner diameter of the resin pipe 2 (the diameter of the pipe line 4) is, for example, 4 mm to 20 mm, and is set to a substantially constant value over the entire pipe length.

[0013] The resin pipe 2 is formed by various known methods, such as injection molding, in which molten resin is injected into a cavity formed in a mold. The resin used to form the resin pipe 2 is selected from a variety of known injectable thermoplastic resins, depending on the performance and other requirements of the resin pipe 2. For example, polyamide, polypropylene, ABS resin, etc. are used for the resin pipe 2 used in air conditioners installed in automobiles, and nylon resin (nylon 6, nylon 66, nylon 12, nylon 11), polyethylene, polycarbonate, polystyrene, polyoxymethylene, polymethyl methacrylate, polybutylene terephthalate, acrylic, polyether ether keto, thermoplastic polyurethane, polyethylene terephthalate, and polyvinyl chloride are also suitable.

[0014] The resin pipe 2 can be made of only thermoplastic resin, but can also be made to have specifications in which various fibers (such as glass fiber or carbon fiber, either short or long) are mixed as reinforcing fibers f in a predetermined ratio (for example, 30% to 40% by mass per 100 parts by mass of resin). When the reinforcing fibers f are short fibers, their size is, for example, an outer diameter of 0.001 mm to 1.0 mm, and a length of 0.01 mm to 10 mm.

[0015] A plurality of annular grooves 6 (6a, 6b) are formed on the outer peripheral surface of the connection end 5 at intervals in the pipe axial direction. One annular groove 6a is the most distal annular groove located closest to the pipe end of the connection end 5. The other annular groove 6b is an annular groove located closer to the end of the pipe than the most distal annular groove 6a. One seal material 8a, 8b is fitted into each annular groove 6a, 6b. In the resin pipe 2 of this embodiment, the outer diameter of the connection end 5 is larger than the outer diameter of the portion other than the connection end 5 (the non-connection end). The outer diameter of the connection end 5 may be the same as or smaller than the outer diameter of the non-connection end.

[0016] In this embodiment, an annular flange fixing groove 7 is further formed on the outer peripheral surface of the plastic pipe 2, and a metal flange 9 is fitted onto the flange fixing groove 7. The annular groove 6 is located closer to the tip end in the axial direction of the pipe than the metal flange 9. The metal flange 9 is a component for fixing the plastic pipe 2 to an object 11 to be connected.

[0017] The metal flange 9 has an insertion hole 9a and a mounting hole 9b that penetrate in the pipe axial direction. The flange fixing groove 7 fits into the insertion hole 9a with the plastic pipe 2 passing through. The metal flange 9 is not essential and is provided as needed. In specifications that do not include the metal flange 9, the flange fixing groove 7 is not formed on the outer surface of the plastic pipe 2.

[0018] As shown in FIG. 3 , the leading annular groove 6a has a groove width B1 and a groove depth D1, while the other annular groove 6b has a groove width B2 and a groove depth D2. Although the groove widths B1 and B2 are the same, the groove depth D1 is greater than the groove depth D2 (D1 > D2). Because the seal materials 8a and 8b have the same specifications, the radial widths W1 and W2 of the seal materials 8a and 8b arranged in the annular grooves 6a and 6b are the same. Although the radial widths W1 and W2 of the seal materials 8a and 8b vary slightly when fitted into the annular grooves 6a and 6b, they can be considered identical. Therefore, the radial protrusion P1 (= W1 - D1) of one seal material 8a from the outer circumferential surface of the connection end 5 is set smaller than the radial protrusion P2 (= W2 - D2) of the other seal material 8b from the outer circumferential surface of the connection end 5 (P1 < P2). The difference between the protrusion amount P1 and the protrusion amount P2 is, for example, 0.05 mm or more and 1.80 mm or less.

[0019] As shown in Figure 4, the plastic pipe 2 is connected to and fixed to the object 11. To connect and fix the plastic pipe 2 to the object 11, the connection end 5 is inserted into the connection hole 11a of the object 11, and one end face of the metal flange 9 is brought into contact with the opposing surface of the object 11. The inner diameter of the connection hole 11a is set to a substantially constant value in the axial direction of the pipe within the range where the connection end 5 is inserted. Next, the fixing bolt 10 that passes through the mounting hole 9b of the metal flange 9 is screwed into a bolt hole formed in the object 11, completing the connection and fixing work.

[0020] In a connection structure in which a resin pipe 2 is connected and fixed to an object 11, the sealant 8 installed on the outer peripheral surface of the connection end 5 abuts against the inner peripheral surface of the connection hole 11a, ensuring a seal between the resin pipe 2 (connection end 5) and the connection hole 11a. More specifically, as illustrated in Fig. 5, the connection end 5 inserted into the connection hole 11a is pressed toward the axis CL together with the sealants 8a and 8b. The sealants 8a and 8b are compressed and deformed by the inner peripheral surface of the connection hole 11a, blocking and sealing the gap S between the outer peripheral surface of the connection end 5 and the inner peripheral surface of the connection hole 11a.

[0021] The gap S between the inner peripheral surface of the connection hole 11a and the outer peripheral surface of the connection end 5 is substantially constant, and is, for example, 0.065 mm or less. This gap S is calculated by (inner diameter of the connection hole 11a - outer diameter of the connection end 5) / 2. Since the inner diameter of the connection hole 11a can be known in advance, the gap S can also be known in advance.

[0022] In this resin pipe with sealant 1, one sealant 8b is pressed more strongly (in the radial direction of the pipe) by the inner circumferential surface of the connection hole 11a than one sealant 8a. When inserting the connection end 5 into the connection hole 11a, the protrusion amount P1 of the sealant 8a located in the leading-edge annular groove 6a is set smaller than the protrusion amount P2 of the other sealant 8b. This makes it easier to insert the connection end 5 into the connection hole 11a than when the protrusion amounts P1 and P2 of the sealants 8a and 8b are the same. This is therefore advantageous for preventing damage to the sealant 8a during the process of inserting the connection end 5 into the connection hole 11a.

[0023] In this resin pipe 1 with sealing material, after the connection end 5 is inserted into the connection hole 11a, the sealing material 8a, which has a relatively small protrusion amount P1, is less likely to be excessively compressed, so the compressive load over time is reduced, making it easier to ensure sealing performance over a long period of time. Since the sealing material 8a is not excessively compressed, it is also advantageous for suppressing deformation of the resin forming the vicinity of the leading-edge annular groove 6a where the sealing material 8a is located, which is advantageous for ensuring sealing performance over a long period of time.

[0024] Compared to one sealing material 8a, the other sealing material 8b is pressed more strongly between the outer circumferential surface of the connection end 5 and the inner circumferential surface of the connection hole 11a, so the other sealing material 8b bears more of the various external forces acting on the resin pipe 2 than does the sealing material 8a. Therefore, one sealing material 8a is more advantageous than the other sealing material 8b for sealing against fluids that enter between the outer circumferential surface of the connection end 5 and the inner circumferential surface of the connection hole 11a for a long period of time under better installation conditions.

[0025] In this resin pipe 1 with a sealant, the sealant 8a arranged in the leading-edge annular groove 6a first functions to seal against fluid entering between the outer circumferential surface of the connection end 5 and the inner circumferential surface of the connection hole 11a. The other sealant 8b functions as a backup for the sealant 8a and also functions to block outside air, external moisture, etc. from entering the pipe 4 and the connection hole 11a.

[0026] Generally, one sealing material 8a, which seals against fluid entering between the outer circumferential surface of the connection end 5 and the inner circumferential surface of the connection hole 11a, is placed in a harsher operating environment than the other sealing material 8b. Therefore, in this resin pipe with sealant 1, the sealing material 8a, which is placed in a harsher operating environment, is configured to be specialized for sealing against fluid flowing through the conduit 4 and the connection hole 11a under more favorable installation conditions, as described above. In this way, in this resin pipe with sealant 1, rather than simply providing dual sealing functions to each sealing material 8a, 8b, each sealing material performs different functions appropriate for its respective location, making it possible to stably ensure good sealing performance over the long term.

[0027] Furthermore, the resin pipe 1 with the sealing material is advantageous in terms of weight reduction compared to a metal pipe. As in this embodiment, by making the sealing materials 8a and 8b the same specifications and using a common sealing material 8, it is advantageous in reducing procurement costs and management costs of the sealing material 8.

[0028] In this embodiment, the crushing ratio E of the sealing material 8 calculated by the following formula (1) is set to be larger for the sealing material 8a arranged in the most distal annular groove 6a than for the sealing material 8b arranged in the annular groove 6b located closer to the opposite end of the pipe than the most distal annular groove 6a: Crushing ratio E of sealing material 8 = {(amount of protrusion P of sealing material 8 in the pipe radial direction from the outer circumferential surface of connection end 5 - gap S between the inner circumferential surface of connection hole 11a and the outer circumferential surface of connection end 5) / pipe radial thickness W of sealing material 8} × 100 (%) ... (1)

[0029] It is preferable that the compression ratio E of one sealing material 8a be set to 10% or more and 30% or less, and that of the other sealing material 8b be set to 20% or more and 40% or less. If the compression ratio E is less than 10%, there is a risk that the seal between the outer peripheral surface of the connection end 5 and the inner peripheral surface of the connection hole 11a will not be sufficiently secured. If the compression ratio E is more than 40%, there is a risk that the sealing material 8 will be excessively compressed, shortening its service life.

[0030] By setting the compression ratio E of each of the sealing materials 8 a, 8 b as described above, it is possible to maintain each of the sealing materials 8 a, 8 b in a compressed state that ensures sufficient sealing performance over a long period of time, while allowing the sealing material 8 b to bear a greater amount of various external forces than the sealing material 8 a. Since the gap S can be determined in advance, the protrusion amount P can be adjusted based on the determined gap S so that the compression ratio E becomes the desired value.

[0031] Furthermore, in this embodiment, the filling rate n of the sealing material 8 calculated by the following formula (2) is set to be larger for the sealing material 8a disposed in the most distal annular groove 6a than for the sealing material 8b disposed in the annular groove 6b located closer to the tube end than the most distal annular groove 6a: Filling rate n of sealing material 8 = {cross-sectional area of ​​sealing material 8 / (groove width B of annular groove 6 in which the sealing material 8 is disposed * (groove depth D of the annular groove 6 + gap S between the inner peripheral surface of connection hole 11a and the outer peripheral surface of connection end 5))} × 100 (%) ... (2) Here, in this embodiment, the cross-sectional area of ​​sealing material 8 is (π / 4) * (thickness W1 of sealing material 8a in the tube diameter direction) for sealing material 8a. 2 and for the sealing material 8b, (π / 4) × (diameter W2 of the sealing material 8b) 2 is.

[0032] It is preferable to set the filling rate n of one sealant 8a to 85% or less, and the filling rate n of the other sealant 8b to 98% or less. If the filling rate n of one sealant 8a exceeds 85%, the movement of the sealant 8a in the annular groove 6a is restricted too strongly, resulting in excessive load on the sealant 8a. As a result, it is disadvantageous to maintain the sealing performance for a long period of time. The lower limit of the filling rate n of the sealant 8a is, for example, 70% or 75%. If the filling rate n of the other sealant 8b exceeds 98%, there is a risk that the shape of the sealant 8a inside the annular groove 6b will be substantially fixed, resulting in an early loss of flexibility. As a result, it is disadvantageous to maintain the sealing performance for a long period of time. The lower limit of the filling rate n of the sealant 8b is, for example, 80% or 85%.

[0033] By setting the filling rate n of each of the sealing materials 8 a and 8 b as described above, it is possible to maintain each of the sealing materials 8 a and 8 b in a state in which sufficient sealing performance can be ensured over a long period of time, while allowing sealing material 8 b to bear a greater amount of various external forces than sealing material 8 a. Since the gap S can be determined in advance, the specifications of the sealing material 8 and the annular groove 6 can be adjusted based on the determined gap S so that the filling rate n becomes the desired value.

[0034] In another embodiment of the resin pipe 1 with a sealing material shown in Figure 6, in order to make the protrusion amount P1 of one sealing material 8a smaller than the protrusion amount P2 of the other sealing material 8b, the pipe radial width W2 of the other sealing material 8b is made larger than the pipe radial width W1 of the one sealing material 8a. The cross section of each of the sealing materials 8a and 8b is a simple circular shape.

[0035] The groove depths D1 and D2 of the annular grooves 6a and 6b are the same, but the groove width B2 is larger than the groove width B1 (B2>B1). In this embodiment, by adjusting the pipe radial thicknesses W1 and W2 of the sealing materials 8a and 8b, the crushing ratio E of the sealing materials 8a and 8b can be set within the appropriate range described above.

[0036] In this embodiment, the groove width B2 is increased as the pipe radial thickness W2 of the sealing material 8b is increased. Increasing W2 without increasing the groove width B2 would result in an excessively large filling rate n of the sealing material 8b. Therefore, in this embodiment, adjusting the groove width B2 while keeping the groove depths D1 and D2 the same makes it easier to set the filling rates n of the sealing materials 8a and 8b within the appropriate ranges described above.

[0037] In another embodiment of the resin pipe 1 with a sealing material shown in Fig. 7, in order to make the protrusion amount P1 of one sealing material 8a smaller than the protrusion amount P2 of the other sealing material 8b, the pipe radial width W2 of the other sealing material 8b is made larger than the pipe radial width W1 of the one sealing material 8a. However, while the cross section of one sealing material 8a is simply circular, the cross section of the other sealing material 8b is non-circular.

[0038] The annular grooves 6 a, 6 b have the same groove depths D1, D2 and the same groove widths B1, B2. In this embodiment, the crushing ratios E of the sealing materials 8 a, 8 b can be set within the appropriate ranges described above by adjusting the radial widths W1, W2 of the sealing materials 8 a, 8 b.

[0039] In this embodiment, as the radial width W2 of the other sealant 8b increases, the cross section of the sealant 8b is made non-circular to correspondingly reduce its cross-sectional area. Increasing W2 without correspondingly reducing the cross-sectional area of ​​the sealant 8b would result in an excessively large filling factor n of the sealant 8b. Therefore, in this embodiment, by adjusting the cross-sectional area of ​​the sealant 8b while maintaining the same groove depths D1 and D2 and the same groove widths B1 and B2, it is easy to set the filling factor n of each sealant 8a, 8b within the appropriate range.

[0040] In the above-described embodiment, two seal materials 8 are arranged at an interval in the tube axis direction on the outer peripheral surface of the connection end portion 5, but three or more seal materials 8 can also be arranged at intervals in the tube axis direction. In consideration of cost and maintenance, it is preferable to arrange two seal materials 8 at an interval in the tube axis direction.

[0041] REFERENCE SIGNS LIST 1 Resin pipe with sealing material 2 Resin pipe 3 Pipe wall 4 Pipe line 5 Connection end 6 (6a, 6b) Annular groove 7 Flange fixing groove 8 (8a, 8b) Sealing material 9 Metal flange 9a Insertion hole 9b Mounting hole 10 Fixing bolt 11 Object to be connected 11a Connection hole (flow path) S Gap

Claims

1. A plastic pipe with a sealing material, comprising: a plastic pipe having a connection end to be inserted into a connection hole formed in an object to be connected; and annular sealing material disposed in each of a plurality of annular grooves formed at intervals in the pipe axial direction on the outer peripheral surface of the connection end of the plastic pipe, wherein the amount of pipe radial protrusion of the sealing material disposed in the most distal annular groove located closest to the pipe end of the connection end is set to be smaller than the amount of pipe radial protrusion of the sealing material disposed in the annular groove located away from the pipe end than the most distal annular groove.

2. A plastic pipe with sealing material as described in claim 1, wherein each of the sealing materials has the same specifications, and the groove depth of the most distal annular groove is set to be greater than the groove depth of the annular groove located at a position toward the opposite end of the pipe from the most distal annular groove.

3. The resin pipe with seal according to claim 1 or 2, wherein the crushing ratio E of the seal, calculated by the following formula (1), is larger for the seal arranged in the annular groove located away from the tube end than the most extreme annular groove, and is set to 10% to 30% for the seal arranged in the most extreme annular groove, and 20% to 40% for the seal arranged in the annular groove located away from the tube end than the most extreme annular groove. Crushing ratio E of seal = {(amount of protrusion P of seal from the outer circumferential surface of the connection end in the tube diameter direction - clearance S between the inner circumferential surface of the connection hole and the outer circumferential surface of the connection end) / thickness W of the seal in the tube diameter direction} x 100 (%) ... (1) 4. The resin pipe with sealant according to any one of claims 1 to 3, wherein the filling rate n of the sealant, calculated by the following formula (2), is larger for the sealant arranged in the annular groove located at a position on the anti-pipe end side from the most proximal annular groove than for the sealant arranged in the most proximal annular groove, and is set to 85% or less for the sealant arranged in the most proximal annular groove, and 98% or less for the sealant arranged in the annular groove located at a position on the anti-pipe end side from the most proximal annular groove. Filling rate n of sealant = {cross-sectional area of ​​sealant / (groove width B of the annular groove in which the sealant is arranged x (groove depth D of the annular groove + gap S between the inner peripheral surface of the connection hole and the outer peripheral surface of the connection end))} x 100 (%) ... (2) 5. A plastic pipe with a seal material according to any one of claims 1 to 4, wherein the number of said annular grooves is two.

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