Water shut-off structure for pipe joint

Abstract

Provided is a water shut-off structure, for a pipe joint, where component versatility can be improved without decreasing watertightness.　A rubber packing 3 comprises: an annular first rubber member 4 where an inner circumferential surface 41 contacts an outer circumferential surface 100a of a pipe 100; an annular second rubber member 5 stacked on an outer peripheral surface 42 of the first rubber member 4 in a pipe radial direction Y of the pipe 100; and stacking retention means 6 for retaining the stacked state of the first rubber member 4 and the second rubber member 5. The first rubber member 4 is made of a rubber material that is harder than the second rubber member 5. In the stacked state of the first rubber member 4 and the second rubber member 5, an end part 43 on a receptacle part side of the first rubber member 4 protrudes further in a pipe axial direction X of the pipe 100 than an end part 53 on the receptacle part side of the second rubber member, and a portion of a protruding part 43a of the end part 43 is disposed between an inner end part 21a of the receptacle part and the outer circumferential surface 100a of the pipe 100. The second rubber member 5 faces a tapered surface 21c of the receptacle part 21.

Description

Watertight structure of pipe joints

[0001] The present invention relates to a waterproof structure for a pipe fitting, and more particularly to a waterproof structure for a pipe fitting that includes a fitting body having a socket portion into which a pipe is inserted, an annular rubber packing attached to the outer surface of the pipe, and a pressing means connected to the fitting body for pressing the rubber packing against the socket portion.

[0002] Conventionally, a watertight structure for a pipe joint as described above has been known, for example, as described in Patent Document 1. In this watertight structure, for example, in the case of an inserted pipe 100' shown by the dashed line in FIG. 9 , a rubber packing 3', a fitting body 2', and a pressing ring 8' (pressing means 7') corresponding to the outer diameter of the pipe 100' are used to ensure watertightness. Therefore, for a pipe 100'' having a diameter smaller than that of the pipe 100', these components cannot be used as they are, and a rubber packing, fitting body, and pressing ring having an inner circumferential surface 31'', an inner end portion 21''a, and an inner end portion 81'' corresponding to the outer diameter of the smaller-diameter pipe 100'' are required. In other words, each component must be prepared according to the outer diameter of the connecting pipe, which makes the pipe joint expensive.

[0003] For this reason, it is conceivable to standardize the joint body 2' and use, for example, a rubber packing 3" as shown in Figure 10. However, because the inner end 21'a of the socket portion 21' and the pipe 100" are separated, the compressive force applied to the rubber packing 3" escapes to the joint body 2', reducing watertightness. Furthermore, even if only the rubber packing 3' is made thicker as shown in Figure 9, the inner end 21'a is separated from the small-diameter pipe 100", making it impossible to form a compression structure for the rubber packing 3' and ensuring watertightness.

[0004] Japanese Patent Application Laid-Open No. 2003-247679

[0005] In view of the above-described conventional situation, an object of the present invention is to provide a watertight structure for a pipe joint that can improve the versatility of the part without compromising watertightness.

[0006] In order to achieve the above object, the watertight structure of a pipe fitting according to the present invention is characterized in that it comprises a fitting body having a receiving portion into which a pipe is inserted, an annular rubber packing attached to the outer peripheral surface of the pipe, and pressing means connected to the fitting body for pressing the rubber packing against the receiving portion, wherein the rubber packing has an annular first rubber member whose inner peripheral surface is in contact with the outer peripheral surface of the pipe, an annular second rubber member stacked in the radial direction of the pipe on the outer peripheral surface of the first rubber member, and stacking holding means for maintaining the stacked state of the first rubber member and the second rubber member, the first rubber member being made of a rubber material harder than the second rubber member, and in the stacked state of the first rubber member and the second rubber member, the end of the first rubber member on the receiving portion side protrudes in the axial direction of the pipe beyond the end of the second rubber member on the receiving portion side, and part of the protruding portion is located between the inner end of the receiving portion and the outer peripheral surface of the pipe, and the second rubber member faces the tapered surface of the receiving portion.

[0007] According to the above configuration, the rubber packing includes an annular first rubber member whose inner peripheral surface contacts the outer peripheral surface of the pipe, an annular second rubber member laminated on the outer peripheral surface of the first rubber member in the radial direction of the pipe, and a laminate retainer for retaining the first and second rubber members in a laminated state. This allows for standardization of the fitting body and the second rubber member, even when the outer diameter of the pipe is different, simply by manufacturing the second rubber member to match the shape of the fitting body and adjusting the first rubber member to the outer diameter of the pipe, thereby improving versatility. The first rubber member is made of a harder rubber material than the second rubber member, and in the laminated state of the first and second rubber members, the end of the first rubber member on the receiving end side protrudes in the axial direction of the pipe beyond the end of the second rubber member on the receiving end side, with a portion of the protruding portion positioned between the inner end of the receiving end and the outer peripheral surface of the pipe, and the second rubber member faces the tapered surface of the receiving end. As a result, part of the protruding portion, together with the tapered surface of the receiving portion, forms a compression structure for the second rubber member, so that the compression force from the pressing means does not escape into the inside of the fitting body, and the second rubber member is compressed and deformed near the inner end portion, improving watertightness.

[0008] In the above configuration, in the stacked state, the end of the first rubber member on the pressing means side protrudes in the tube axial direction further than the end of the second rubber member on the pressing means side, a part of the protruding portion is disposed between the inner end of the pressing means and the outer peripheral surface of the tube, and the second rubber member faces the pressing surface of the pressing means.

[0009] In any of the above configurations, annular ridges may be formed on the inner peripheral surface of the first rubber member at appropriate intervals along the axial direction of the pipe. The compressive deformation of the ridges allows smooth deformation and movement of the first rubber member in the axial direction, ensuring watertightness of the outer peripheral surface of the pipe.

[0010] In any of the above configurations, the inner circumferential surface of the first rubber member may be coated with a lubricant, which also allows the first rubber member to deform and move smoothly in the axial direction of the pipe, thereby ensuring watertightness of the outer circumferential surface of the pipe.

[0011] In any of the above configurations, the pressing means is a press ring attached to the outer circumferential surface of the pipe and fastened to the fitting body. In this case, it is desirable that the rubber hardness of the second rubber member is 65° to 75°, and the rubber hardness of the first rubber member is 3° to 15° greater than the rubber hardness of the second rubber member. If the difference in rubber hardness is greater than 15°, the degree of compressive deformation of the first and second rubber members will vary significantly, and the laminated state of the first and second rubber members may not be maintained. On the other hand, if the difference in rubber hardness is less than 3°, the first rubber member will be soft and will be more likely to deform in the axial direction of the pipe, reducing the compressive force in the diameter reduction direction. As a result, watertightness cannot be ensured.

[0012] On the other hand, in any of the above configurations, the pressing means is a union nut threadedly fastened to the outer peripheral surface of the socket portion. In this case, it is desirable that the rubber hardness of the second rubber member is 50° to 60°, and the rubber hardness of the first rubber member is 3° to 20° greater than that of the second rubber member. If the difference in rubber hardness is greater than 20°, the degree of compressive deformation of the first and second rubber members will vary significantly, and the laminated state of the first and second rubber members may not be maintained. On the other hand, if the difference in rubber hardness is less than 3°, the first rubber member will be soft and will be more likely to deform in the axial direction of the pipe, reducing the compressive force in the diameter reduction direction. As a result, watertightness cannot be ensured.

[0013] In any of the above configurations, the stacking holding means may be composed of a plurality of recesses formed at appropriate intervals along the tube axis direction on the outer peripheral surface of the first rubber member, and a plurality of protrusions formed at appropriate intervals along the tube axis direction on the inner peripheral surface of the second rubber member, whereby the stacking state is maintained by the fitting of the recesses and protrusions.

[0014] In any of the above configurations, the outer periphery of the end of the second rubber member on the receiving portion side may be tapered to face the tapered surface, and the outer periphery may be provided with a plurality of annular ridges and annular recesses alternately along the pipe axis direction. This compresses and deforms the annular ridges, causing the entire second rubber member to reduce in diameter and fit closely to the receiving portion, ensuring stronger watertightness.

[0015] According to the features of the watertight structure of the pipe joint of the present invention, it is possible to improve the versatility of the part without reducing the watertightness.

[0016] Other objects, configurations and effects of the present invention will become apparent from the following detailed description of the preferred embodiments of the present invention.

[0017] FIG. 1 is a perspective view showing a water stopping structure of a pipe joint according to a first embodiment of the present invention. FIG. 2 is a perspective view of a first rubber member. FIG. 3 is a cross-sectional view showing a state in which a press ring is assembled to a socket portion to which first and second rubber members are attached. FIG. 4 is a cross-sectional view showing a state in which the press ring has been tightened with a bolt nut. FIG. 5 is a perspective view showing a water stopping structure of a pipe joint according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a state in which a union nut has been screwed on. FIG. 7 is a cross-sectional view showing a state in which the union nut has been tightened. FIG. 8 is a view equivalent to FIG. 3 showing a modified example of a rubber packing. FIG. 9 is a cross-sectional view showing a water stopping structure of a conventional pipe joint. FIG. 10 is a cross-sectional view showing a water stopping structure of a conventional pipe joint.

[0018] Next, a first embodiment of the present invention will be described in more detail with reference to Figures 1 to 4. (Overall Overview of First Embodiment) As shown in Figure 1, a watertight structure 1 for a pipe fitting according to a first embodiment of the present invention generally comprises a fitting body 2 having a socket portion 21 into which a pipe 100 is inserted, an annular rubber packing 3 attached to the outer peripheral surface 100a of the pipe 100 (hereinafter referred to as the "pipe outer surface"), and a pressing means 7 connected to the fitting body 2 and pressing the rubber packing 3 against the socket portion 21. In this embodiment, the pressing means 7 is constituted by a pressing ring 8.

[0019] 1, 3, and 4, the joint body 2 has a generally tapered socket portion 21 and a cavity 23 for positioning the pipe end of the pipe 100, with an inner end portion 21a that protrudes toward the pipe axis at the end of the socket portion 21 on the cavity 23 side. A generally rectangular flange 22 is formed on the outer periphery 21b of the socket portion 21, and a corner 22a of the flange 22 is formed with a through hole 24 for inserting a T-head bolt 12a, which will be described later.

[0020] (Rubber gasket 3) In the water-stopping structure 1 for a pipe joint according to the present invention, the rubber gasket 3 has an annular first rubber member 4 whose inner surface 41 contacts the pipe outer periphery 100a, an annular second rubber member 5 laminated on the outer surface 42 of the first rubber member 4 in the pipe radial direction Y of the pipe 100, and a laminate holding means 6 that maintains the laminated state of the first rubber member 4 and the second rubber member 5 laminated in the pipe radial direction Y.

[0021] In the present invention, the first rubber member 4 is made of a rubber material harder than the second rubber member 5. In this embodiment, for example, the rubber hardness of the second rubber member 5 is 65° to 75° (70°±5°), and the rubber hardness of the first rubber member 4 is 3° to 15° greater than the rubber hardness of the second rubber member 5.

[0022] (First Rubber Member 4) As shown in FIG. 2 , a plurality of annular ridges 41 a are formed on the inner peripheral surface 41 of the first rubber member 4 at appropriate intervals along the tube axis direction X. Furthermore, a plurality of recesses 42 a are formed on the outer peripheral surface 42 of the first rubber member 4 at appropriate intervals along the tube axis direction X. The ridges 41 a and recesses 42 a are formed in the center of the width direction of the main body 40 of the first rubber member 4. Note that, in this embodiment, the ridges 41 a and recesses 42 a are not formed near the first end 43, which is the end on the receiving port 21 side, or the second end 44, which is the end on the pressing ring 8 (pressing means 7) side. Furthermore, in this embodiment, the rubber hardness of the first rubber member 4 is, for example, 73° to 85°. In particular, if the hardness of the first rubber member 4 is softer than this, the rubber would protrude (flow) in the tube axis direction, making it difficult to maintain the compressive force of the rubber, and thus watertightness would not be maintained.

[0023] The inner diameter of the first rubber member 4 is larger than the outer diameter of the tube 100. This allows for temporary fastening (temporary assembly) using a spacer 56, as shown in FIG. 3 . The outer diameter of the recessed portion 42a of the outer peripheral surface 42 of the first rubber member 4 (hereinafter referred to as the "outer diameter of the first rubber member 4") is slightly larger than the inner diameter of the protruding portion 51a of the inner peripheral surface 51 of the second rubber member 5 (hereinafter referred to as the "inner diameter of the second rubber member 4"). This requires the first rubber member 4 to be reduced in diameter during stacking, and the repulsive force of the rubber due to this reduction makes it less likely to come off. Note that "slightly larger" means, for example, that the outer diameter of the first rubber member 4 is 1 to 3% larger than the inner diameter of the second rubber member 5. In this embodiment, the ridges 41a and recessed portions 42a are formed on the same straight line along the tube radial direction Y (concentric circles with respect to the tube axis) on the front and back of the main body 40.

[0024] 3 and 4 , a plurality of annular protrusions 51 a are formed on the inner peripheral surface 51 of the second rubber member 5 at appropriate intervals along the tube axis direction X. A tapered surface 59 that faces the tapered surface 21 c of the socket 21 is formed on the outer peripheral portion of a first end 53, which is the end of the second rubber member 5 on the socket 21 side. This tapered surface 59 is provided with a plurality of annular protrusions 58 a and annular recesses 58 b alternately arranged along the tube axis direction X. A second end 54, which is the end on the pressure ring 8 (pressing means 7) side, abuts against the pressing surface 82 of the pressure ring 8. A positioning rib 55 is formed on the outer peripheral surface 52 of the second rubber member 5.

[0025] (Stacking holding means 6) In this embodiment, the stacking holding means 6 is made up of the recessed portion 42a of the first rubber member 4 and the protruding portion 51a of the second rubber member 5. These recessed and protruding portions fit together to firmly hold the stacked state of the first rubber member 4 and the second rubber member 5.

[0026] 3 and 4 , in the laminated state of the first rubber member 4 and the second rubber member 5, the first end 43 of the first rubber member 4 protrudes in the tube axis direction X further than the first end 53 of the second rubber member 5. A portion (tip) 43a of this protruding portion is disposed between the inner end 21a and the tube outer surface 100a. Furthermore, in this embodiment, the second end 44 of the first rubber member 4 protrudes in the tube axis direction X further than the second end 54 of the second rubber member 5. A portion (tip) 44a of this protruding portion is disposed between the inner end 81 of the press ring 8 and the tube outer surface 100a. The ridges 41a and the convex portions 42a are formed on the same straight line along the tube radial direction Y (concentric with the tube axis).

[0027] (Pressing means 7, pressing ring 8) In this embodiment, the pressing means 7 is a pressing ring 8 that is attached to the pipe outer surface 100a and fastened to the joint body 2. As shown in Figures 1, 3, and 4, the pressing ring 8 generally has a ring-shaped main body 80 that covers the pipe outer surface 100a, an inner end 81 that protrudes from the main body 80 toward the pipe axis, and a pressing surface 82 that presses the second rubber member 5. In addition, a flange 83 of the main body 80 is provided with a through-hole 84 through which a T-head bolt 12a that is fastened to the joint body 2 passes.

[0028] (Installation Procedure) Here, the installation procedure for the pipe joint will be described with reference to Figures 3 and 4. First, the second rubber member 5 is layered on the outer peripheral surface 42 of the first rubber member 4. At this time, the convex portion 51a of the second rubber member 5 is fitted into the concave portion 42a of the first rubber member 4. As described above, the outer diameter of the first rubber member 4 is slightly larger than the inner diameter of the second rubber member 5. Therefore, the repulsive force of the rubber caused by the diameter contraction of the first rubber member 4 during stacking makes the fit between the convex and concave portions more difficult to come off. Furthermore, the first rubber member 4 is harder than the second rubber member 5, and the rubber hardness of the first rubber member 4 is 3 to 15 degrees greater than the rubber hardness of the second rubber member 5. If the hardness difference is within this range, the fit between the convex and concave portions is difficult to come off, and the stacked state is maintained even during compressive deformation, which will be described later. Then, the stacked first and second rubber members 4, 5 are attached to the receiving portion 21.

[0029] As described above, the inner diameter of the first rubber member 4 is larger than the outer diameter of the pipe 100. Therefore, as shown in Figure 3, the second end 54 of the second rubber member 5 is brought into contact with the pressing surface 82 of the pressure ring 8, and a spacer 56 is sandwiched between the flange 22 of the socket portion 21 to which the first and second rubber members 4, 5 are attached and the flange 83 of the pressure ring 8, and the T-head bolt 12a and nut 12b are tightened to create a pre-assembled state. This prevents the second rubber member 5 from being pushed in during transportation to the construction site, etc. Furthermore, because the inner diameter of the first rubber member 4 is larger than the outer diameter of the pipe 100, the pipe 100 can be easily inserted in the pre-assembled state as shown in the same figure, resulting in excellent construction ease.

[0030] 4, the spacer 56 is removed and the T-head bolt 12a and nut 12b are tightened. In this embodiment, the part 44a of the protruding portion is disposed between the inner end portion 81 and the pipe outer surface 100a, so the pressing force of the pressure ring 8 acts on the second rubber member 5 via the pressing surface 82. This pressing force causes the outer periphery of the second rubber member 5 to come into contact with the tapered surface 21c of the socket portion 21 and to deform.

[0031] Here, the first end 43 of the first rubber member 4 protrudes in the tube axis direction X beyond the first end 53 of the second rubber member 5, and a portion 43a of the protruding portion is disposed between the inner end 21a and the tube outer surface 100a. The first rubber member 4 is made of a rubber material that is harder than the second rubber member 5. Therefore, the portion 43a of the protruding portion, together with the tapered surface 21c, constitutes the compression structure of the first end 53 of the second rubber member 5. As a result, the ridge 58a is compressed and deformed by the tapered surface 21c, and the entire second rubber member 5 moves along the tapered surface 21c toward the inner end 21a, reducing its diameter. When further pressed, the second rubber member 5 rolls along the tapered surface 21c, further reducing its diameter, and the tapered outer periphery 59 comes into close contact with the tapered surface 21c, improving watertightness.

[0032] Furthermore, the compressive deformation of the second rubber member 5 presses the first rubber member 4 against the tube outer surface 100a. Because the first rubber member 4 is made of a harder rubber material than the second rubber member 5, it is less likely to deform in the tube axial direction but is easily compressed and reduced in diameter in the tube radial direction. As shown in FIG. 4 , the widthwise center portion of the main body 40, where the recesses 42a are formed, is primarily compressed and deformed. The ribs 41a then compress and deform, causing the inner circumferential surface 41 to closely contact the tube outer surface 100a. Because the ribs 41a are provided on the inner circumferential surface 41, the compressive deformation of the ribs 41a facilitates deformation and movement of the first rubber member 4 in the tube axial direction. Therefore, the first rubber member 4 also moves and reduces in diameter in the tube axial direction in response to the rolling reduction of the second rubber member 5, ensuring watertightness at the tube outer surface 100a. (Overview of the Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 5 to 7 . In the following embodiments, the same components as those in the above embodiment are denoted by the same reference numerals.

[0033] (Pressing means 7, union nut 9) In the first embodiment, the pressing means 7 is the pressure ring 8, but in the second embodiment, the pressing means 7 is a union nut 9 that is screwed onto the outer peripheral surface 21b of the receiving portion 21 and tightened.

[0034] 5 to 7, the union nut 9 generally has an inner end 91 that protrudes toward the pipe axis and a pressing surface 92 that presses against the second rubber member 5. The inner circumferential surface 90a of the union nut 9 is formed with a female thread 93 that threadably engages with the male thread 25 of the socket portion 21 (described later), and the outer circumferential surface 90b is provided with an annular groove 94 that engages with the main body 11a of the locking device 11 (described later). In this embodiment, the inner end 91 is located inside the groove 94. The union nut 9 is used together with a retaining ring 10 that is attached to the outer circumferential surface 100a of the pipe and fastened by a fastening means 13, and a locking device 11 that is detachably attached to the groove 94 of the union nut 9 and maintains the connection with the retaining ring 10.

[0035] In the second embodiment, for example, the rubber hardness of the second rubber member 5 is 50° to 60° (55°±5°), and the rubber hardness of the first rubber member 4 is 3° to 20° greater than that of the second rubber member 5. Note that although the dimensions and the like of the first and second rubber members 4, 5 and stack holding means 6 differ from those of the first embodiment, their basic configurations are the same, and therefore a description thereof will be omitted. Note that in this embodiment, the rubber hardness of the first rubber member 4 is, for example, 58° to 75°.

[0036] 5 to 7 , in the second embodiment, the joint body 2 has a male thread 25 formed on its outer peripheral surface 21b. The male thread 25 is threadedly mated with a female thread 93 formed on the inner peripheral surface 90a of the union nut 9. By threading and tightening the union nut 9 into the socket portion 21, the first and second rubber members 4, 5 are compressively deformed.

[0037] 5 to 7, the retaining ring 10 has a main body 10a having a generally C-ring shape and a pair of protruding pieces 10b, 10b protruding outward from both ends of the main body 10a. The protruding pieces 10b are provided with a through-hole 10c through which a bolt 13a of the fastening means 13 is inserted. In this embodiment, the outer circumferential surface of the main body 10a is provided with a pair of receiving portions 10d, 10d that receive a hook portion 11c of a locking device 11 (described later). In addition, annular teeth 10e that prevent the pipe 100 from slipping are formed on the inner surface of the main body 10a.

[0038] (Lock device 11) As shown in Figures 5 to 7, the lock device 11 has a roughly horseshoe-shaped main body 11a, a pair of arm portions 11b, 11b extending from both ends of the main body 11a along the tube axis direction X, and hook portions 11c protruding toward the center at the ends of the pair of arm portions 11b, 11b.

[0039] (Installation Procedure) Now, with reference to Figures 6 and 7, the installation procedure for the union nut pipe joint will be described. First, the second rubber member 5 is layered on the outer peripheral surface 42 of the first rubber member 4. This is the same as in the above embodiment, so the recessed and protruding parts are less likely to come loose and the layered state is maintained even during compressive deformation. As shown in Figure 6, the retaining ring 10 is attached to the outer surface 100a of the pipe, and the union nut 9 is threaded onto the joint body 2 with the layered first and second rubber members 4, 5 interposed in the socket portion 21. Then, the main body portion 10a of the locking portion 11 is engaged with the groove portion 94 of the union nut 9, and the hook portion 10c is locked into the receiving portion 10d of the retaining ring 10.

[0040] 7, the union nut 9 is then tightened. In the second embodiment, too, the part 44a of the protruding portion is disposed between the inner end portion 91 and the outer surface 100a of the pipe, so that the pressing force of the union nut 9 acts on the second rubber member 5 via the pressing surface 92. This pressing force causes the outer periphery of the second rubber member 5 to come into contact with the tapered surface 21c of the socket portion 21 and to deform.

[0041] Also in the second embodiment, a portion 43a of the protruding portion is disposed between the inner end portion 21a and the pipe outer surface 100a, and the first rubber member 4 is made of a harder rubber material than the second rubber member 5. Therefore, also in the second embodiment, the ridge 58a is compressed and deformed by the tapered surface 21c, and the entire second rubber member 5 moves along the tapered surface 21c toward the inner end portion 21a, reducing its diameter. When further pressed, the second rubber member 5 rolls along the tapered surface 21c, further reducing its diameter, and the tapered outer periphery 59 comes into close contact with the tapered surface 21c, improving watertightness.

[0042] Furthermore, since the configuration of the first rubber member 4 is the same as that of the above embodiment, the first rubber member 4 also moves and contracts in the axial direction of the pipe in response to the rolling contraction of the second rubber member 5, so that watertightness on the outer surface 100a of the pipe can also be ensured in the second embodiment.

[0043] (Other Embodiments) Finally, the possibility of still other embodiments of the present invention will be described. In the first embodiment described above, in the laminated state of the first rubber member 4 and the second rubber member 5, the second end 44 of the first rubber member 4 protrudes in the tube axis direction X beyond the second end 54 of the second rubber member 5, and a portion 54a of this protruding portion is disposed between the inner end 81 of the pressure ring 8 (pressing means 7) and the outer peripheral surface 100a of the tube 100. However, as shown in FIG. 8 , the second end 44 of the first rubber member 4 may be disposed at a position equivalent to the second end 54 of the second rubber member 5 and may face the pressing surface 82 of the pressure ring 8. This also applies to the second embodiment, in which the second end portions 44, 54 may be disposed at a position equivalent to the second end 54 of the second rubber member 5 and may face the pressing surface 92 of the union nut 9. In the present invention, it is sufficient that a compression structure for the second rubber member 5 can be formed in the receiving portion 21, and at least the first end 43 of the first rubber member 4 must protrude in the tube axis direction X beyond the first end 53 of the second rubber member 5, with a portion 43a of this protruding portion being disposed between the inner end 21a of the receiving portion 21 and the outer peripheral surface 100a of the tube 100. In the case of Figure 8, the rubber hardness of the first rubber member 4 is, for example, 70° to 85°. Unlike Figure 4 of the first embodiment, in Figure 8, the pressing surface 82 of the pressing ring 8 suppresses deformation (protrusion) of the first rubber member 4 in the tube axis direction, so watertightness is maintained within the above numerical range.

[0044] In the first and second embodiments, the inner circumferential surface 41 of the first rubber member 4 is formed with a plurality of annular ribs 41a at appropriate intervals along the tube axis direction X. However, the ribs 41a may be omitted and a lubricant may be applied to the inner circumferential surface 41 instead. If the ribs 41a are omitted, the compressive deformation of the second rubber member 5 causes the inner circumferential surface 41 of the first rubber member 4 to adhere closely to the outer circumferential surface 100a of the tube 100. Therefore, the first rubber member 4 cannot follow the compressive deformation of the second rubber member 5 and deform or move in the tube axis direction, thereby failing to ensure watertightness. Applying a lubricant facilitates deformation and movement of the first rubber member 4 in the tube axis direction X, thereby ensuring watertightness. As described above, as long as resistance at the contact surface between the first rubber member 4 and the tube 100 is reduced, the first rubber member 4 may be formed from a highly lubricating rubber material.

[0045] In the first and second embodiments, the stack holding means 6 is configured by the recessed portions 42a on the outer peripheral surface 42 of the first rubber member 4 and the protruding portions 51a on the inner peripheral surface 51 of the second rubber member 5. However, the stack holding means 6 is not limited to this, and for example, a protruding portion may be formed on the first rubber member 4 and a recessed portion may be formed on the second rubber member 5, and these may serve as the stack holding means 6. The dimensions, shape, number, etc. of the recessed portions 42a and the protruding portions 51a may be set appropriately in a manner that allows the stacked state to be maintained.

[0046] In the first and second embodiments, the ribs 41a on the inner circumferential surface 41 of the first rubber member 4 and the recesses 42a on the outer circumferential surface 42 are aligned along the same line in the tube diameter direction, and the shape of the ribs 41a is similar to that of the convex portions 51a. However, the dimensions, shape, and number of the ribs 41a may be appropriately determined. For example, the height and width of the ribs 41a may be smaller than those of the recesses 42a and the convex portions 51a, and the number of the ribs 41a may also be smaller than those of the recesses 42a and the convex portions 51a. This makes it easier to remove the first rubber member 4 from the mold during rubber molding. Furthermore, the ribs 41a may be formed not only in the widthwise center of the main body 40 but also from the first end 43 on the receiving port 21 side to the second end 44 on the pressing means 7 side (over the entire inner circumferential surface 41).

[0047] In the second embodiment, the pressing means 7 is configured by the union nut 9, the retaining ring 10, and the locking device 11. The retaining ring 10 and the locking device 11 are not limited to those of the second embodiment, as long as they function as a union nut pipe joint.

[0048] 1, 1', 1'': Water stopping structure, 2, 2': Joint body, 3, 3', 3''': Rubber packing, 4: First rubber member, 5: Second rubber member, 6: Stacking holding means, 7, 7', 7'': Pressing means, 8, 8', 8'': Press ring, 9: Union nut, 10: Retaining ring, 10a: Body portion, 10b: Projection piece, 10c: Through hole, 10d: Receiving portion, 10e: Tooth portion, 11: Locking tool, 11a: Body portion, 1 1b: arm portion, 11c: hook portion, 12a: T-head bolt, 12b: nut, 13: fastening means, 13a: bolt, 13b: nut, 21, 21': socket portion, 21a, 21'a: inner end portion, 21b: outer periphery, 21c: tapered surface, 22: flange, 22a: corner portion, 23: cavity, 24: through hole, 25: male thread, 31', 31'', 31'': inner periphery, 40: main body portion, 4 1: inner peripheral surface, 41a: ridge, 42: outer peripheral surface, 42a: recess, 43: first end (end on the socket side), 43a: part of the protruding portion (tip), 44: second end (end on the pressing means side), 51: inner peripheral surface, 51a: convex portion, 52: outer peripheral surface, 53: first end (end on the socket side), 54: second end (side end of the pressing means), 55: positioning rib, 56: spacer, 58a: ridge, 58b: recess rib, 59: tapered surface (outer periphery of first end), 80: main body, 81, 81', 81'': inner end, 82, 82', 82'': pressing surface, 83: flange, 84: through hole, 90a: inner circumferential surface, 90b: outer circumferential surface, 91: inner end, 92: pressing surface, 93: female thread, 94: groove, 100, 100', 100'': pipe, 100a: outer circumferential surface (outer surface of pipe), X: pipe axial direction, Y: pipe radial direction

Claims

1. A waterproof structure for a pipe fitting comprising a fitting body having a receiving portion into which a pipe is inserted, an annular rubber packing attached to the outer peripheral surface of the pipe, and a pressing means connected to the fitting body for pressing the rubber packing against the receiving portion, wherein the rubber packing has a first annular rubber member whose inner peripheral surface is in contact with the outer peripheral surface of the pipe, a second annular rubber member laminated in the radial direction of the pipe on the outer peripheral surface of the first rubber member, and a lamination retaining means for maintaining the laminated state of the first rubber member and the second rubber member, wherein the first rubber member is made of a rubber material harder than the second rubber member, and in the laminated state of the first rubber member and the second rubber member, an end of the first rubber member on the receiving portion side protrudes in the axial direction of the pipe beyond the end of the second rubber member on the receiving portion side, and a part of the protruding portion is disposed between the inner end of the receiving portion and the outer peripheral surface of the pipe, and the second rubber member faces a tapered surface of the receiving portion.

2. A water-stopping structure for a pipe joint as described in claim 1, wherein, in the laminated state, the end of the first rubber member on the pressing means side protrudes in the pipe axial direction further than the end of the second rubber member on the pressing means side, a part of the protruding portion is disposed between the inner end of the pressing means and the outer peripheral surface of the pipe, and the second rubber member faces the pressing surface of the pressing means.

3. A water-stopping structure for a pipe joint as claimed in claim 1 or 2, wherein annular ridges are formed on the inner surface of the first rubber member at appropriate intervals along the axial direction of the pipe.

4. A waterproof structure for a pipe joint as claimed in claim 1 or 2, wherein a lubricant is applied to the inner peripheral surface of the first rubber member.

5. A water-stopping structure for a pipe joint as claimed in claim 1 or 2, wherein the pressing means is a pressing ring attached to the outer circumferential surface of the pipe and fastened to the joint body.

6. A waterproof structure for a pipe joint as set forth in claim 5, wherein the rubber hardness of the second rubber member is 65° to 75°, and the rubber hardness of the first rubber member is 3° to 15° greater than the rubber hardness of the second rubber member.

7. A water-stopping structure for a pipe joint as claimed in claim 1 or 2, wherein the pressing means is a union nut screwed tightly onto the outer peripheral surface of the receiving portion.

8. A waterproof structure for a pipe joint as set forth in claim 7, wherein the rubber hardness of the second rubber member is 50° to 60°, and the rubber hardness of the first rubber member is 3° to 20° greater than the rubber hardness of the second rubber member.

9. A waterproof structure for a pipe joint as described in claim 1 or 2, wherein the laminated retaining means comprises a plurality of recesses formed at appropriate intervals along the pipe axis direction on the outer peripheral surface of the first rubber member, and a plurality of protrusions formed at appropriate intervals along the pipe axis direction on the inner peripheral surface of the second rubber member.

10. A water-stopping structure for a pipe fitting as described in claim 1 or 2, wherein the outer periphery of the end of the second rubber member on the receiving portion side is tapered facing the tapered surface, and the outer periphery has a plurality of annular ridges and annular recesses alternately provided along the pipe axial direction.

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