Pipe joint assembly

Abstract

Problem: To provide a pipe joint assembly configured to prevent a seal ring from coming off due to pressurized fluid which is confined in a sealed space between two seal rings. Solution: A female pipe joint 110 includes a first annular groove 120 and a second annular groove 122 formed on an inner peripheral surface 118. The female pipe joint 110 further includes a first seal ring 124 and a second seal ring 126 respectively attached to the first annular groove 120 and the second annular groove 122. A male pipe joint 150 includes an insertion part 156 inserted into a passage 116. The insertion part 156 includes, on an outer peripheral surface 158 thereof, a ventilation recessed part 160 formed in a portion in a circumferential direction. When the female pipe joint 110 and the male pipe joint 150 are connected, a sealed space S is formed between the first seal ring 124 and the second seal ring 126. When the insertion part 156 is pulled out from the passage 116, the ventilation recessed part 160 opens the sealed space S through the inside of the second seal ring 126.

Description

Pipe joint assembly

[0001] The present invention relates to a pipe fitting assembly comprising a female pipe fitting and a male pipe fitting which are detachably connected to each other.

[0002] Typically, a sealing ring such as an O-ring is used to prevent leakage of the internal fluid between the interconnected female and male pipe fittings. The sealing ring is arranged to be crushed between the inner circumferential surface of the female pipe fitting and the outer circumferential surface of the male pipe fitting member to form a tight seal therebetween.

[0003] Seal rings are generally made of elastic materials such as rubber or plastic. Such seal rings inevitably deteriorate depending on the environment and conditions of use, and may crack or partially tear, causing the seal ring to lose its ability to maintain a proper seal. Furthermore, dust or other debris may become trapped between the seal ring and the outer circumferential surface of the male pipe fitting or the inner circumferential surface of the female pipe fitting, causing the seal ring to lose its ability to maintain a seal.

[0004] Patent Document 1 discloses an inspection fitting for connecting a plastic pipe, in which two O-rings are provided on a cover of the inspection fitting, and the two O-rings seal between the inspection fitting and the plastic pipe inserted therein. In this inspection fitting, two O-rings of different diameters are arranged in order to ensure an appropriate seal even for plastic pipes with different inner or outer diameters. When both O-rings seal the plastic pipe, even if the sealing ability of one O-ring deteriorates, the other O-ring maintains sealing ability, preventing leakage of the internal fluid.

[0005] Patent No. 7224859

[0006] Two or more seal rings are sometimes used to ensure the sealing performance of the seal rings more reliably and for a longer period of time. However, particularly when handling pressurized fluid, the sealing performance of one seal ring may be reduced, allowing the pressurized fluid to pass through that seal ring and become trapped in the space between the two seal rings. If an attempt is made to disconnect the pipe fitting assembly in this state, when the seal ring is released from its position sandwiched between the inner circumferential surface of the female pipe fitting and the outer circumferential surface of the male pipe fitting, the trapped pressurized fluid may forcefully push out the seal ring, causing it to come off its installed position.

[0007] Therefore, an object of the present invention is to provide a pipe joint assembly having two seal rings, which is capable of preventing the seal rings from coming off due to pressurized fluid trapped in the sealed space between the two seal rings.

[0008] That is, the present invention provides a pipe fitting assembly comprising a first pipe fitting and a second pipe fitting which are detachably connected to each other, wherein the first pipe fitting has a passage extending rearward from a front end opening, and the second pipe fitting has an insertion portion which is inserted rearward from the front end opening of the first pipe fitting into the passage, one of an inner circumferential surface of the passage and an outer circumferential surface of the insertion portion has a first annular groove and a second annular groove formed side by side in the direction of a longitudinal axis of the passage or the insertion portion, a first seal ring is attached to the first annular groove, and a second seal ring is attached to the second annular groove, the other of the inner circumferential surface of the passage and the outer circumferential surface of the insertion portion has an air vent recess formed in a part of the circumferential direction of the passage or the insertion portion, and when the insertion portion is inserted into the passage to connect the first pipe fitting and the second pipe fitting, the air vent recess passes inside or outside the first seal ring and then inside or outside the second seal ring, a pipe fitting assembly in which, when the first pipe fitting and the second pipe fitting are connected, the first seal ring and the second seal ring are sealingly engaged with the other surface to form a sealed space in a gap between the inner peripheral surface and the outer peripheral surface between the first seal ring and the second seal ring, and when the insertion portion of the second pipe fitting is pulled forward from the passage of the first pipe fitting from the connected state, the ventilation recess passes inside or outside the second seal ring to open the sealed space.

[0009] In this pipe fitting assembly, when the connection is released, the air vent recess formed in the insertion portion of the second pipe fitting opens the sealed space between the first seal ring and the second seal ring. By opening the sealed space, pressurized fluid that has entered the sealed space can be released. Furthermore, because this air vent recess is formed only partially in the circumferential direction, even if the second seal ring is pushed out of the second annular groove into the air vent recess by pressure in the sealed space, the portion of the second seal ring that does not face the air vent recess remains held in the second annular groove, so the entire second seal ring will not come out of the second annular groove.

[0010] Furthermore, the ventilation recess may have a first inclined surface that extends in a direction away from the second seal ring to the other surface in the connected state, and when the insertion portion of the second pipe fitting is pulled out from the passage of the first pipe fitting, the first inclined surface may push the second seal ring radially into the second annular groove.

[0011] By providing such a first inclined surface, it becomes possible to smoothly return the second seal ring, which has partially come out of the second annular groove into the ventilation recess, into the second annular groove.

[0012] Furthermore, the ventilation recess may have a second inclined surface that extends in a direction approaching the second seal ring to the other surface in the connected state, and when the insertion portion of the second pipe fitting is inserted into the passage of the first pipe fitting, the second inclined surface may push the second seal ring radially into the second annular groove.

[0013] The ventilation recess may be a groove extending approximately halfway around the circumference in the circumferential direction.

[0014] Furthermore, the ventilation recess may have a depth that is 0.4 to 0.6 times the wire diameter of the second seal ring.

[0015] Furthermore, the opening width of the ventilation recess on the outer circumferential surface in the longitudinal direction of the insertion portion may be larger than the wire diameter of the second seal ring.

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a pipe joint assembly according to the present invention will be described with reference to the accompanying drawings.

[0017] 1 is a cross-sectional view of a pipe fitting assembly according to a first embodiment of the present invention in a separated state; a perspective view of an insertion portion of a male pipe fitting; a cross-sectional view of the pipe fitting assembly of FIG. 1 in a state in the middle of being connected; a cross-sectional view of the pipe fitting assembly of FIG. 1 in a connected state; an enlarged view of part A of FIG. 4 in a connected state; an enlarged view showing a state when the supply of pressurized fluid to the flow paths of the female pipe fitting and the male pipe fitting is stopped with pressurized fluid entering the sealed space between the first seal ring and the second seal ring; an enlarged view showing a state where the vent recess of the male pipe fitting passes through the inside of the second seal ring, opening the sealed space; an enlarged view showing a state where a part of the second seal ring has been pushed out of the second annular groove by the pressurized fluid in the sealed space; an enlarged view showing a state where the second seal ring, which has been partially pushed out of the second annular groove, is pushed into the second annular groove by the first inclined surface of the vent recess; an enlarged view showing a state where the second seal ring has been returned into the second annular groove by the first inclined surface of the vent recess; and an enlarged view of a state where the pipe fitting assembly has been completely separated. Figure 13 is a cross-sectional view of a pipe fitting assembly according to a second embodiment of the present invention in a separated state. Figure 14 is a cross-sectional view of a pipe fitting assembly according to a fourth embodiment of the present invention in a separated state. Figure 15 is a cross-sectional view of the pipe fitting assembly according to the third embodiment of the present invention in a separated state. Figure 16 is a cross-sectional view of the pipe fitting assembly according to the fourth embodiment of the present invention in a connected state. Figure 17 is a perspective view of an insertion portion of a male pipe fitting according to another embodiment. Figure 18 is a view showing various modified examples of a ventilation recess of a male pipe fitting according to yet another embodiment.

[0018] As shown in FIG. 1, a pipe fitting assembly 101 according to a first embodiment of the present invention comprises a female pipe fitting (first pipe fitting) 110 and a male pipe fitting (second pipe fitting) 150 which are detachably connected to each other.

[0019] The female pipe fitting 110 includes a cylindrical female fitting body 112. The female fitting body 112 has a front end opening 114 and a passage 116 extending rearward (to the left as viewed in the figure) from the front end opening 114 along a longitudinal axis L. The passage 116 is defined by an inner circumferential surface 118. A first annular groove 120 and a second annular groove 122 are formed in the inner circumferential surface 118 of the passage 116 and are arranged side by side in the direction of the longitudinal axis L. The second annular groove 122 is located rearward of the first annular groove 120. A first seal ring 124 and a second seal ring 126 are mounted in the first annular groove 120 and the second annular groove 122, respectively. A first backup ring 128 and a second backup ring 130 are further mounted in the first annular groove 120 and the second annular groove 122, respectively.

[0020] The female pipe fitting 110 further includes a spherical locking element 134 disposed in a locking element holding hole 132 formed in the female fitting body 112, and a sleeve 138 disposed on an outer circumferential surface 136 of the female fitting body 112. The sleeve 138 is biased forward (to the right as viewed in the figure) by a spring 140.

[0021] The male pipe fitting 150 includes a cylindrical male fitting body 154 having a passage 152 extending along a longitudinal axis L. The male fitting body 154 has an insertion portion 156 that is inserted into the passage 116 of the female pipe fitting 110. A ventilation recess 160 is formed in the outer peripheral surface 158 of the insertion portion 156. The ventilation recess 160 has a first inclined surface 160a, a second inclined surface 160b, and a bottom surface 160c therebetween. The first inclined surface 160a extends from the bottom surface 160c to the outer peripheral surface 158, sloping radially outward toward the rear (left as viewed in the figure). The second inclined surface 160b extends from the bottom surface 160c to the outer peripheral surface 158, sloping radially outward toward the front (right as viewed in the figure). The ventilation recess 160 is formed in a portion of the circumference of the insertion portion 156. The male fitting 150 further includes a lock engagement groove 162 adapted to engage with the lock 134 .

[0022] As shown in FIG. 2 , in this embodiment, the ventilation recess 160 is a groove extending approximately halfway around the circumferential direction of the insertion portion 156. The bottom surface 160c of the ventilation recess 160 is composed of a central portion 160c-1 extending parallel to the outer peripheral surface 158 and two end portions 160c-2 extending from the central portion 160c-1 toward the outer peripheral surface 158 (only one end portion 160c-2 is shown in FIG. 2 ). The ventilation recess 160 is formed so that the opening width D on the outer peripheral surface 158 in the longitudinal direction of the insertion portion 156 (i.e., the direction of the longitudinal axis L) is constant in the circumferential direction. In this ventilation recess 160, the central portion 160c-1 has a constant width, while the end portions 160c-2 gradually widen toward the outer peripheral surface 158. The opening width D of the ventilation recess 160 is larger than the wire diameter of the second seal ring 126.

[0023] When connecting the female pipe fitting 110 and the male pipe fitting 150, as shown in FIG. 3 , the insertion portion 156 of the male pipe fitting 150 is inserted rearward from the front end opening 114 into the passage 116 of the female pipe fitting 110 with the sleeve 138 displaced rearward. At this time, the ventilation recess 160 first passes inside the first seal ring 124 and then passes inside the second seal ring 126. Although a portion of the inner portions of the first seal ring 124 and the second seal ring 126 temporarily enters the ventilation recess 160 slightly, the second inclined surface 160 b of the ventilation recess 160 presses the first seal ring 124 and the second seal ring 126 radially outward into the first annular groove 120 and the second annular groove 122, respectively, so that the first seal ring 124 and the second seal ring 126 are smoothly guided onto the outer circumferential surface 158 of the insertion portion 156.

[0024] As shown in Figure 4, when the male pipe fitting 150 is inserted into the female pipe fitting 110 until the locking element engagement groove 162 of the male pipe fitting 150 is positioned inside the locking element 134, the locking element 134 is pushed radially inward by the sleeve 138 and engages with the locking element engagement groove 162. The locking element 134 is pressed from the radially outward side by the sleeve 138, maintaining the engagement with the locking element engagement groove 162. This completes the connection between the female pipe fitting 110 and the male pipe fitting 150. In this connected state, the ventilation recess 160 of the male pipe fitting 150 is located behind the second seal ring 126. Furthermore, in the coupled state, the inclination direction of the first inclined surface 160a of the ventilation recess 160 is a direction in which it inclines away from the second seal ring 126 (rearward) as far as the outer circumferential surface 158, and the inclination direction of the second inclined surface 160b is a direction in which it inclines toward the second seal ring 126 (forward) as far as the outer circumferential surface 158. The first seal ring 124 and the second seal ring 126 sealingly engage with the outer circumferential surface 158 of the insertion portion 156 of the male pipe fitting 150, thereby sealingly sealing between the inner circumferential surface 118 of the female pipe fitting 110 and the outer circumferential surface 158 of the insertion portion 156 of the male pipe fitting 150.

[0025] As can be seen in FIG. 5 , when the female pipe fitting 110 and the male pipe fitting 150 are connected, a sealed space S is formed in the gap between the inner circumferential surface 118 of the female pipe fitting 110 and the outer circumferential surface 158 of the insertion portion 156, between the first seal ring 124 and the second seal ring 126. When pressurized fluid is supplied to the passage 116 of the female pipe fitting 110 and the passage 152 of the male pipe fitting 150, the pressure is applied to the second seal ring 126. When the second seal ring 126 is properly sealed, the pressurized fluid does not enter the sealed space S. However, over long periods of use, the pressurized fluid may gradually pass through the second seal ring 126 and enter the sealed space S, or the second seal ring 126 may deteriorate or be damaged, causing the pressurized fluid to enter the sealed space S. Even in such cases, the presence of the first seal ring 124 prevents the pressurized fluid from leaking outside the pipe fitting assembly 101.

[0026] When disconnecting the female pipe fitting 110 and the male pipe fitting 150, first, the supply of pressurized fluid to the passage 116 of the female pipe fitting 110 and the passage 152 of the male pipe fitting 150 is stopped. If pressurized fluid has entered the sealed space S at this time, the pressure in the passages 116 and 152 will decrease, and the first seal ring 124 and the second seal ring 126 will be pressed outward from the sealed space S by the pressure in the sealed space S, as shown in Figure 6. In this state, the insertion portion 156 of the male pipe fitting 150 is pulled forward from the passage 116 of the female pipe fitting 110, and when the ventilation recess 160 passes inside the second seal ring 126 as shown in Figure 7, the sealed space S will be opened via the ventilation recess 160. This allows the pressurized fluid in the sealed space S to be released from the sealed space S.

[0027] If a fluid under a relatively high pressure, for example, several MPa to several tens of MPa, is confined in the sealed space S, a large pressure will be applied to the first seal ring 124 and the second seal ring 126. If the vent recess 160 reaches the inside of the second seal ring 126 under such conditions, the second seal ring 126 may be pushed out of the second annular groove 122 toward the vent recess 160 by the pressurized fluid, as shown in FIG. 8 . In the pipe fitting assembly 101 according to the present invention, the vent recess 160 is formed only partially in the circumferential direction. Therefore, even in such a case, the entire second seal ring 126 will not come out of the second annular groove 122, and at least a portion of the second seal ring 126 will remain retained in the second annular groove 122. Therefore, the second seal ring 126 will not come out completely from the second annular groove 122. As the male pipe fitting 150 is further pulled out as shown in Figure 9, the portion of the second seal ring 126 that was pushed out of the second annular groove 122 is pushed radially outward toward the second annular groove 122 by the first inclined surface 160a of the ventilation recess 160. Then, as shown in Figure 10, the second seal ring 126 is pushed back to its original position within the second annular groove 122. Therefore, even if the second seal ring 126 has been partially pushed out of the second annular groove 122, when the connection between the female pipe fitting 110 and the male pipe fitting 150 is completely released as shown in Figure 11, the second seal ring 126 returns to a state where it is attached within the second annular groove 122.

[0028] In this way, in the pipe fitting assembly 101 of this embodiment, the insertion portion 156 of the male pipe fitting 150 has a ventilation recess 160 formed partially in the circumferential direction, which makes it possible to prevent the second seal ring 126 from coming off the second annular groove 122 when the pressurized fluid that has entered the sealed space S between the first seal ring 124 and the second seal ring 126 is released.

[0029] The ventilation recess 160 preferably has a depth sufficient to prevent the second seal ring 126 attached to the second annular groove 122 from contacting the bottom surface 160c in order to release the pressurized fluid within the sealed space S. When an O-ring is used as the second seal ring 126, the interference of the O-ring is typically about 20% of the O-ring's wire diameter. Therefore, the ventilation recess 160 preferably has a depth of at least 0.2 times the wire diameter of the second seal ring 126. Furthermore, if the entire wire diameter of the second seal ring 126 enters the ventilation recess 160 when the second seal ring 126 is pushed into the ventilation recess 160 due to the pressure within the sealed space S, it will be difficult to return the second seal ring 126 to the second annular groove 122. Therefore, the ventilation recess 160 preferably has a depth smaller than the wire diameter of the second seal ring 126. Therefore, the ventilation recess 160 preferably has a depth of 0.2 to 1 times the wire diameter of the second seal ring 126, and more preferably has a depth of 0.4 to 0.6 times the wire diameter of the second seal ring 126. The ventilation recess 160 in this embodiment has a depth that is approximately 0.5 times the wire diameter of the second seal ring 126. In this embodiment, the wire diameter of the first seal ring 124 is the same as the wire diameter of the second seal ring 126. The size of the ventilation recess 160 relative to the second seal ring 126 shown here simply indicates a desirable size, and the size may be outside the above range.

[0030] As shown in FIG. 12 , a pipe fitting assembly 201 according to a second embodiment of the present invention comprises a female pipe fitting (first pipe fitting) 210 and a male pipe fitting (second pipe fitting) 250 that are detachably connected to each other. In this embodiment, the female pipe fitting 210 has a passage 216 extending rearward (toward the left as viewed in the figure) from a front-end opening 214, and the male pipe fitting 250 has an insertion portion 256 that is inserted into the passage 216. A first annular groove 220 and a second annular groove 222 are formed in an outer peripheral surface 258 of the insertion portion 256, aligned in the direction of the longitudinal axis L of the insertion portion 256. A first seal ring 224 is attached to the first annular groove 220, and a second seal ring 226 is attached to the second annular groove 222. A ventilation recess 260 is also formed in the inner peripheral surface 218 of the passage 216. The ventilation recess 260 is formed only in a portion of the passage 216 in the circumferential direction.

[0031] When the insert portion 256 is inserted into the passage 216 to couple the female pipe fitting 210 and the male pipe fitting 250, the ventilation recess 260 first passes outside the first seal ring 224 and then passes outside the second seal ring 226. As shown in FIG. 13 , when the female pipe fitting 210 and the male pipe fitting 250 are coupled, the ventilation recess 260 is located in front of the second seal ring 226. The first seal ring 224 and the second seal ring 226 sealingly engage with the inner circumferential surface 218 of the passage 216, forming a sealed space S in the gap between the inner circumferential surface 218 of the passage 216 and the outer circumferential surface 258 of the insert portion 256 between the first seal ring 224 and the second seal ring 226. The ventilation recess 260 has a first inclined surface 260 a and a second inclined surface 260 b. When connected, the first inclined surface 260a is inclined radially inward toward the inner circumferential surface 218 in the direction away from the second seal ring 226 (forward), and the second inclined surface 260b is inclined radially inward toward the inner circumferential surface 218 in the direction toward the second seal ring 226 (rearward).

[0032] 13 , when the insertion portion 256 of the male pipe fitting 250 is pulled forward from the passage 216 of the female pipe fitting 210 and the vent recess 260 passes outside the second seal ring 226, the sealed space S is opened via the vent recess 260. If pressurized fluid is trapped in the sealed space S, it is released from the sealed space S via the vent recess 260. If a fluid at a relatively high pressure is trapped in the sealed space S, the second seal ring 226 may be pushed radially outward from the second annular groove 222 toward the vent recess 260 when the pressurized fluid is released. Even if the second seal ring 226 is pushed out, the entire second seal ring 226 will not come out of the second annular groove 222 because the vent recess 260 is formed only partially in the circumferential direction. As the insert 256 is further pulled out of the passage 216, the first inclined surface 260a pushes the second seal ring 226 radially inward toward the second annular groove 222. This allows the second seal ring 226 to return to its original position in the second annular groove 222, even if the second seal ring 226 has been partially pushed out of the second annular groove 222. The other configurations are the same as those of the first embodiment, and therefore will not be described here.

[0033] As shown in FIG. 14 , a pipe fitting assembly 301 according to a third embodiment of the present invention comprises a female pipe fitting (second pipe fitting) 310 and a male pipe fitting (first pipe fitting) 350 that are detachably connected to each other. In this embodiment, the male pipe fitting 350 has a passage 316 extending rearward (to the right as viewed in the figure) from a front-end opening 314, and the female pipe fitting 310 has an insertion portion 356 that is inserted into the passage 316. A first annular groove 320 and a second annular groove 322 are formed in an inner circumferential surface 318 of the passage 316, aligned in the direction of the longitudinal axis L of the passage 316. A first seal ring 324 is attached to the first annular groove 320, and a second seal ring 326 is attached to the second annular groove 322. A ventilation recess 360 is also formed in the outer circumferential surface 358 of the insertion portion 356. The ventilation recess 360 is formed only in a portion of the insertion portion 356 in the circumferential direction.

[0034] When the insert 356 is inserted into the passage 316 to couple the female pipe fitting 310 and the male pipe fitting 350, the ventilation recess 360 first passes inside the first seal ring 324 and then passes inside the second seal ring 326. When the female pipe fitting 310 and the male pipe fitting 350 are coupled as shown in FIG. 15 , the ventilation recess 360 is located behind the second seal ring 326. The first seal ring 324 and the second seal ring 326 sealingly engage with the outer circumferential surface 358 of the insert 356, forming a sealed space S in the gap between the inner circumferential surface 318 of the passage 316 and the outer circumferential surface 358 of the insert 356 between the first seal ring 324 and the second seal ring 326. The ventilation recess 360 has a first inclined surface 360 ​​a and a second inclined surface 360 ​​b. When connected, the first inclined surface 360a is inclined radially outward toward the outer peripheral surface 358 in the direction away from the second seal ring 326 (rearward), and the second inclined surface 360b is inclined radially outward toward the outer peripheral surface 358 in the direction toward the second seal ring 326 (forward).

[0035] 15 , when the insertion portion 356 of the female pipe fitting 310 is pulled forward from the passage 316 of the male pipe fitting 350 and the vent recess 360 passes inside the second seal ring 326, the sealed space S is opened via the vent recess 360. If pressurized fluid is trapped in the sealed space S, it is released from the sealed space S via the vent recess 360. If a fluid at a relatively high pressure is trapped in the sealed space S, the second seal ring 326 may be pushed radially inward from the second annular groove 322 toward the vent recess 360 when the pressurized fluid is released. Even if the second seal ring 326 is pushed out, the entire second seal ring 326 will not come out of the second annular groove 322 because the vent recess 360 is formed only partially in the circumferential direction. As the insert 356 is further pulled out from the passage 316, the first inclined surface 360a pushes the second seal ring 326 radially outward toward the second annular groove 322. This allows the second seal ring 326 to return to its original position in the second annular groove 322, even if the second seal ring 326 has been partially pushed out of the second annular groove 322. The other configurations are the same as those of the first embodiment, and therefore will not be described here.

[0036] As shown in FIG. 16 , a pipe fitting assembly 401 according to a fourth embodiment of the present invention comprises a female pipe fitting (second pipe fitting) 410 and a male pipe fitting (first pipe fitting) 450 that are detachably connected to each other. In this embodiment, the male pipe fitting 450 has a passage 416 extending rearward (to the right as viewed in the figure) from a front-end opening 414, and the female pipe fitting 410 has an insertion portion 456 that is inserted into the passage 416. A first annular groove 420 and a second annular groove 422 are formed in the outer peripheral surface 458 of the insertion portion 456, aligned in the direction of the longitudinal axis L of the insertion portion 456. A first seal ring 424 is attached to the first annular groove 420, and a second seal ring 426 is attached to the second annular groove 422. A ventilation recess 460 is also formed in the inner peripheral surface 418 of the passage 416. The ventilation recess 460 is formed only in a portion of the passage 416 in the circumferential direction.

[0037] When the insert portion 456 is inserted into the passage 416 to couple the female pipe fitting 410 and the male pipe fitting 450, the ventilation recess 460 first passes outside the first seal ring 424 and then passes outside the second seal ring 426. When the female pipe fitting 410 and the male pipe fitting 450 are coupled as shown in FIG. 17 , the ventilation recess 460 is located in front of the second seal ring 426. The first seal ring 424 and the second seal ring 426 sealingly engage with the inner circumferential surface 418 of the passage 416, forming a sealed space S in the gap between the inner circumferential surface 418 of the passage 416 and the outer circumferential surface 458 of the insert portion 456 between them. The ventilation recess 460 has a first inclined surface 460 a and a second inclined surface 460 b. When connected, the first inclined surface 460a is inclined radially inward toward the inner circumferential surface 418 in the direction away from the second seal ring 426 (forward), and the second inclined surface 460b is inclined radially inward toward the inner circumferential surface 418 in the direction toward the second seal ring 426 (rearward).

[0038] 17 , when the insertion portion 456 of the female pipe fitting 410 is pulled forward from the passage 416 of the male pipe fitting 450 and the vent recess 460 passes outside the second seal ring 426, the sealed space S is opened via the vent recess 460. If pressurized fluid is trapped in the sealed space S, it is released from the sealed space S via the vent recess 460. If a fluid at a relatively high pressure is trapped in the sealed space S, the second seal ring 426 may be pushed radially outward from the second annular groove 422 toward the vent recess 460 when the pressurized fluid is released. Even if the second seal ring 426 is pushed out, the entire second seal ring 426 will not come out of the second annular groove 422 because the vent recess 460 is formed only partially in the circumferential direction. As the insert 456 is further pulled out of the passage 416, the first inclined surface 460a pushes the second seal ring 426 radially inward toward the second annular groove 422. This allows the second seal ring 426 to return to its original position in the second annular groove 422, even if the second seal ring 426 has been partially pushed out of the second annular groove 422. The other configurations are similar to those of the first embodiment, and therefore will not be described here.

[0039] The shape of the ventilation recess can be modified as appropriate. In another embodiment of the ventilation recess 560 shown in FIG. 18, the central portion 560c-1 of the bottom surface 560c has the same shape as the central portion 560c-1 of the above embodiment, but the ends 560c-2 on both sides also have a constant width. Furthermore, the first inclined surface 560a and the second inclined surface 560b become smaller toward the ends, thereby gradually reducing the opening width D at the ends. In the embodiment shown in FIG. 19(a), the front surface of the ventilation recess 660 is a vertical surface 660b. In the embodiment shown in FIG. 19(b), the inclination angle of the first inclined surface 760a of the ventilation recess 760 is steeper, and the bottom surface 760c is wider. Furthermore, in the embodiment shown in FIG. 19(c), the ventilation recess 860 extends circumferentially for more than halfway around the circumference. The ventilation recess can also have a shape other than the above. For example, the first inclined surface may be a vertical surface or may have a shape that extends shorter in the circumferential direction. Furthermore, a plurality of circumferentially short ventilation recesses may be formed in the circumferential direction. The features of the ventilation recesses described herein may be combined with each other, and may also be similarly applied to the ventilation recesses formed on the inner circumferential surface as in the second and fourth embodiments.

[0040] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications are possible. Note that terms indicating directions such as "forward" and "rearward" in the specification and claims are used for the purpose of clearly explaining the configuration of the invention and do not necessarily indicate directions in actual use.

[0041] DESCRIPTION OF SYMBOLS 101 Pipe fitting assembly 110 Female pipe fitting (first pipe fitting) 112 Female fitting body 114 Front end opening 116 Passage 118 Inner peripheral surface 120 First annular groove 122 Second annular groove 124 First seal ring 126 Second seal ring 128 First backup ring 130 Second backup ring 132 Locking element retaining hole 134 Locking element 136 Outer peripheral surface 138 Sleeve 140 Spring 150 Male pipe fitting (second pipe fitting) 152 Passage 154 Male fitting body 156 Insertion portion 158 Outer peripheral surface 160 Ventilation recess 160a First inclined surface 160b Second inclined surface 160c Bottom surface 160c-1 Central portion 160c-2 End portion 162 Locking element engagement groove 201 Pipe fitting assembly 210 Female pipe fitting (first pipe fitting) 214 Front end opening 216 Passage 218 Inner peripheral surface 220 First annular groove 222 Second annular groove 224 First seal ring 226 Second seal ring 250 Male pipe fitting (second pipe fitting) 256 Insertion portion 258 Outer peripheral surface 260 Ventilation recess 260a First inclined surface 260b Second inclined surface 301 Pipe fitting assembly 310 Female pipe fitting (second pipe fitting) 314 Front end opening 316 Passage 318 Inner peripheral surface 320 First annular groove 322 Second annular groove 324 First seal ring 326 Second seal ring 350 Male pipe fitting (first pipe fitting) 356 Insertion portion 358 Outer peripheral surface 360 ​​Ventilation recess 360a First inclined surface 360b Second inclined surface 401 Pipe fitting assembly 410 Female pipe fitting (second pipe fitting) 414 Front end opening 416 Passage 418 Inner peripheral surface 420 First annular groove 422 Second annular groove 424 First seal ring 426 Second seal ring 450 Male pipe fitting (first pipe fitting) 456 Insertion portion 458 Outer peripheral surface 460 Ventilation recess 460a First inclined surface 460b Second inclined surface 560a First inclined surface 560b Second inclined surface 560c Bottom surface 560c-1 Central portion 560c-2 End portion 660 Ventilation recess 660b Vertical surface 760 Ventilation recess 760a: First inclined surface 760c: Bottom surface 860: Ventilation recess D: Opening width L: Longitudinal axis S: Sealed space

Claims

1. A pipe fitting assembly consisting of a first pipe fitting and a second pipe fitting which are detachably connected to each other, wherein the first pipe fitting has a passage extending rearward from a front end opening, and the second pipe fitting has an insertion part which is inserted rearward from the front end opening of the first pipe fitting into the passage, one of the inner circumferential surface of the passage and the outer circumferential surface of the insertion part has a first annular groove and a second annular groove formed side by side in the direction of the longitudinal axis of the passage or the insertion part, a first seal ring is attached to the first annular groove, and a second seal ring is attached to the second annular groove, the other of the inner circumferential surface of the passage and the outer circumferential surface of the insertion part has an air vent recess formed in a part of the circumferential direction of the passage or the insertion part, and when the insertion part is inserted into the passage to connect the first pipe fitting and the second pipe fitting, the air vent recess passes inside or outside the first seal ring and then inside or outside the second seal ring, a pipe fitting assembly in which, when the first pipe fitting and the second pipe fitting are connected, the first seal ring and the second seal ring sealingly engage with the other surface to form a sealed space in a gap between the inner circumferential surface and the outer circumferential surface between the first seal ring and the second seal ring, and when the insertion portion of the second pipe fitting is pulled forward from the passage of the first pipe fitting from the connected state, the ventilation recess passes inside or outside the second seal ring to open the sealed space.

2. The pipe fitting assembly according to claim 1, wherein the ventilation recess has a first inclined surface that extends in a direction away from the second seal ring and toward the other surface in the connected state, and wherein the first inclined surface presses the second seal ring radially into the second annular groove when the insertion portion of the second pipe fitting is withdrawn from the passage of the first pipe fitting.

3. The pipe fitting assembly according to claim 1, wherein the ventilation recess has a second inclined surface that extends at an angle to the other surface in a direction approaching the second seal ring in the connected state, and the second inclined surface presses the second seal ring radially into the second annular groove when the insertion portion of the second pipe fitting is inserted into the passage of the first pipe fitting.

4. A pipe joint assembly according to claim 1, wherein said ventilation recess is a groove extending approximately halfway around said circumference.

5. A pipe fitting assembly as set forth in claim 1, wherein said vent recess has a depth of 0.4 to 0.6 times the wire diameter of said second seal ring.

6. A pipe joint assembly as set forth in claim 1, wherein the opening width of the ventilation recess on the outer peripheral surface in the longitudinal direction of the insertion portion is larger than the wire diameter of the second seal ring.

Images