Pipe joint with valve structure

Abstract

[Problem] To provide a pipe joint capable of preventing unexpected coupling in a state in which pressure is being applied in a fluid passage. [Solution] A female pipe joint 10 is provided with: a joint body 16 having an insertion passage 20, a fluid passage 26, and a branch passage 28; a sleeve 30; a pressure receiving member 42 disposed in the branch passage 28; and a valve element 44 disposed in the fluid passage 26. The pressure receiving member 42 is displaced from a first position to a second position by pressure in the fluid passage 26. The valve element 44 is moved from a closed position to an open position by the pressure receiving member 42 when the pressure receiving member 42 is displaced to the second position. When the pressure receiving member 42 is pressed from the first position toward the second position by the pressure in the fluid passage 26 in a state in which the sleeve 30 is at a coupling release position, the pressure receiving member 42 is pressed against the sleeve 30 before the valve element 44 reaches the open position, and displacement of the sleeve 30 is impeded.

Description

Pipe fitting provided with a valve structure

[0001] The present invention relates to a pipe fitting configured to detachably connect a counterpart pipe fitting, and more particularly to a pipe fitting provided with a valve structure.

[0002] Among female pipe fittings (pipe fittings) configured to detachably connect a corresponding male pipe fitting (counterpart pipe fitting), those provided with a valve structure for preventing leakage of internal fluid are known. For example, Patent Document 1 discloses a female pipe fitting that includes a fixed valve body and a movable valve body, wherein in an unconnected state, the movable valve body is in sealing engagement with the fixed valve body by the biasing force of a spring, so that internal fluid does not leak. When this female pipe fitting is connected to a corresponding male pipe fitting, the movable valve body is pressed by the male pipe fitting, the sealing engagement with the fixed valve body is released, and the female pipe fitting is brought into an open state.

[0003] Japanese Patent No. 5317761

[0004] In the pipe fitting provided with the above-described valve structure, even if pressure is applied in the fluid passage in the unconnected state, the valve structure does not enter an open state and can maintain the closed state of the fluid passage. On the other hand, in an application where originally, it is desired to supply fluid to the male pipe fitting side at an arbitrary timing after connection in a state where no pressure is applied to the female pipe fitting side, when an attempt is made to perform connection in a state where pressure is mistakenly applied to the female pipe fitting side, there is a risk that the fluid on the female pipe fitting side may unintentionally flow to the male pipe fitting side. Further, when a high pressure is applied inside the female pipe fitting, there is also a risk that pressurized fluid may blow out to the outside or the pipe fitting may be blown off when the valve structure enters the open state during connection.

[0005] Accordingly, an object of the present invention is to provide a pipe fitting provided with a valve structure that can solve the above-described problems.

[0006] In other words, the present invention relates to a pipe fitting that detachably connects a corresponding pipe fitting, comprising: a pipe fitting body having a cylindrical wall portion extending rearward from a front end opening and defining an insertion passage for receiving the corresponding pipe fitting; a fluid passage extending from an upstream opening to a downstream opening connected to a fluid passage of the corresponding pipe fitting and having a valve seat portion between the upstream opening and the downstream opening; and a branch passage branching off from the fluid passage upstream of the valve seat portion; a locking element disposed on the pipe fitting body and displaceable between a locked position that protrudes into the insertion passage and engages with a locking groove of the corresponding pipe fitting inserted into the insertion passage, and an unlocked position that is displaced radially outward from the locked position to release engagement with the locking groove; and a pressure receiving member disposed in the branch passage and displaceable from a first position to a second position by the fluid pressure in the fluid passage. The present invention provides a pipe joint comprising: a valve body disposed within the fluid passage and displaceable between a closed position in which it is sealedly engaged with the valve seat to close the fluid passage and an open position in which it opens the fluid passage, wherein the valve body is moved from the closed position to the open position by the pressure-receiving member when the pressure-receiving member is displaced from the first position to the second position; and a sleeve disposed outside the joint body, which is displaceable between a disengaged position in which the locking element is allowed to be displaced to the unlocked position and a connected position in which the locking element is constrained to the locked position, wherein when the sleeve is in the disengaged position and the pressure-receiving member is pressed from the first position to the second position by the pressure in the fluid passage, the pressure-receiving member is pressed against the sleeve before the valve body reaches the open position, thereby preventing the sleeve from being displaced.

[0007] In this pipe joint, when the fluid pressure in the fluid passage increases while the joint is unconnected, the pressure-receiving member is pressed against the sleeve, preventing the sleeve from displacing. Therefore, when attempting to connect the joint while pressurized fluid is present in the fluid passage, the operator can easily recognize that pressurized fluid is already supplied to the fluid passage because the sleeve's displacement is being prevented. This prevents unintentional connection while pressurized fluid is present in the fluid passage.

[0008] Furthermore, the sleeve has an engagement recess into which the pressure-receiving member engages, and when the pressure-receiving member is displaced from the first position toward the second position while the sleeve is in the disengaged position, the pressure-receiving member can engage with the engagement recess.

[0009] This configuration makes it possible to more effectively prevent sleeve displacement.

[0010] Furthermore, the pressure-receiving area of ​​the pressure-receiving member can be made larger than the pressure-receiving area of ​​the valve body.

[0011] Furthermore, the valve body has a recess and a projection formed within the recess, and the pressure-receiving member has an extended portion extending into the recess and a projection formed on the extended portion, and when the pressure-receiving member is displaced from the first position to the second position, the projection of the pressure-receiving member engages with the projection of the valve body, thereby displacing the valve body toward the open position.

[0012] Furthermore, the projection of one of the valve body and the pressure-receiving member has an inclined engagement surface that is inclined with respect to the displacement direction of the valve body and a vertical engagement surface that is perpendicular to the displacement direction, and when the pressure-receiving member is displaced from the first position to the second position, the projection of the other of the valve body and the pressure-receiving member engages with the inclined engagement surface, causing the valve body to open, and when the pressure-receiving member is in the second position, the projection of the other engages with the vertical engagement surface.

[0013] This configuration makes it possible to prevent the valve body from returning to the closed position due to slight fluctuations in fluid pressure after it has opened.

[0014] Furthermore, the sleeve may be further equipped with a spring that biases it from the disengaged position toward the connected position.

[0015] Furthermore, the device may be further equipped with a spring that biases the pressure-receiving member from the second position toward the first position.

[0016] Furthermore, when the sleeve is displaced from the connection position toward the disconnection position while the pressure-receiving member is in the second position, the pressure-receiving member can interfere with the sleeve, preventing the sleeve from being displaced all the way to the disconnection position.

[0017] This configuration prevents the connection from being released while the fluid pressure in the fluid passage is high, thus preventing the high-pressure fluid inside from gushing out or the pipe joints from being blown away when the connection is released.

[0018] Hereinafter, embodiments of the pipe joint according to the present invention will be described based on the attached drawings.

[0019] This is a cross-sectional view of a female pipe fitting according to one embodiment of the present invention in an unconnected state. This is an enlarged view of section B in Figure 1A. This is an enlarged view of section C in Figure 1A. This is a perspective view of the pressure receiving member. This is a perspective view of the valve body. This is a cross-sectional view of the female pipe fitting in Figure 1A in an incomplete connection state. This is an enlarged view of section B in Figure 4A. This is a cross-sectional view of the female pipe fitting in Figure 1A in an incomplete connection state. This is an enlarged view of section B in Figure 5A. This is a cross-sectional view of the female pipe fitting in Figure 1A in a connected state. This is an enlarged view of section B in Figure 6A. This is an enlarged view of the area around the valve body when pressure is applied to the fluid passage in the connected state. This is an enlarged view of the area around the valve body when pressure is applied to the fluid passage in an unconnected state. This is an enlarged view of the area around the chuck member when the restraining member is misoperated in an unconnected state.

[0020] The pipe fitting 10 according to one embodiment of the present invention shown in Figure 1A is a female pipe fitting 10 that is detachably connected to a corresponding male pipe fitting (corresponding pipe fitting) 1. The male pipe fitting 1 has a fluid passage 2 and an annular locking groove 3.

[0021] The female pipe fitting 10 comprises a fitting body 16 having a cylindrical wall portion 12 and a flow path component 14. The cylindrical wall portion 12 defines an insertion passage 20 extending rearward (to the left in the figure) from the front end opening 18. The flow path component 14 defines a fluid passage 26 extending from the upstream opening 22 to the downstream opening 24, and a branch passage 28 branching off from the fluid passage 26. The female pipe fitting 10 further comprises a sleeve 30 positioned on the outside of the fitting body 16. The sleeve 30 is positioned to be displaceable relative to the fitting body 16 in the front-rear direction (left-right direction in the figure) between the uncoupled position (Figure 1A) and the coupled position (Figure 6A). The sleeve 30 is biased forward toward the coupled position by a spring 32. A chuck member (locking element) 34 and a spherical locking member 36 are positioned on the cylindrical wall portion 12 of the fitting body 16. The female pipe fitting 10 further includes a restraining member 38 positioned within the insertion passage 20 and a spring 40 that biases the restraining member 38 forward. The female pipe fitting 10 further includes a pressure receiving member 42 positioned within the branch passage 28 and a valve body 44 positioned within the fluid passage 26. The locking member 36 can also be a shape other than a sphere, such as a cylinder or rectangle.

[0022] As shown in Figure 1B, the chuck member 34 has a front end (one end) 46, a rear end (the other end) 48, and a central portion 50 between them. A recess 52 is formed on the outer circumferential surface of the front end 46. The chuck member 34 is positioned to be displaceable between an initial position (Figure 1B), an unlocked position (Figure 4B), and a locked position (Figure 6B). An annular elastic member (biasing member) 54 is positioned in the recess 52. The front end 46 of the chuck member 34 is biased radially inward by the annular elastic member 54, and as a result, the chuck member 34 is biased toward the initial position. Multiple chuck members 34 are arranged in a line in the circumferential direction of the cylindrical wall portion 12, and the annular elastic member 54 is positioned around the front end 46 of the multiple chuck members 34, simultaneously biasing each front end 46 radially inward. In this embodiment, the annular elastic member 54 is a metal C-ring, but it may be other members such as a rubber O-ring or an annular coil spring. Furthermore, multiple biasing members, such as rubber elastic bodies or leaf springs, may be arranged to individually bias each chuck member 34.

[0023] As shown in Figure 2, the pressure-receiving member 42 has a shaft portion 56, an annular groove 58, two extending portions 60, and circular projections 62 that protrude inward from each extending portion 60. As shown in Figure 1C, the pressure-receiving member 42 is sealed and engaged with the branch passage 28 via an O-ring 64 positioned in the annular groove 58. The pressure-receiving member 42 is displaceable along the branch passage 28 between a first position (Figure 1A) and a second position (Figure 7), and is biased toward the first position toward the fluid passage 26 by a spring 66.

[0024] As shown in Figure 3, the valve body 44 has two recesses 68 and projections 70 that protrude outward from each recess 68. The projections 70 have an inclined engagement surface 70a that is inclined forward and downward, and a vertical engagement surface 70b that extends perpendicularly from the inclined engagement surface 70a with respect to the displacement direction of the valve body 44. The valve body 44 is positioned to be displaceable between a closed position (Figure 1C) in which it seals and engages with a valve seat 72 formed between the upstream opening 22 and the downstream opening 24 of the fluid passage 26 to close the fluid passage 26, and an open position (Figure 7) in which it is separated from the valve seat 72 and opens the fluid passage 26.

[0025] In the unconnected state shown in Figures 1A and 1B, the chuck member 34 is biased by the annular elastic member 54, and its front end 46 is in an initial position protruding into the insertion passage 20. At this time, the rear end 48 of the chuck member 34 is located in the receiving recess 74 formed on the inner circumferential surface of the sleeve 30. The locking member 36 is supported from the radially inward by the restraining member 38 and is restrained in a holding position engaged with the locking groove 76 formed on the inner circumferential surface of the sleeve 30. Because the locking member 36 is engaged with the locking groove 76, the sleeve 30 is held in a disconnected position that allows displacement of the chuck member 34.

[0026] As shown in Figures 4A and 4B, when the male pipe fitting 1 is inserted into the insertion passage 20 of the female pipe fitting 10, the male pipe fitting 1 comes into contact with the front end 46 of the chuck member 34, causing the chuck member 34 to displace. Specifically, it swings around the central part 50, causing the front end 46 to displace radially outward and the rear end 48 to displace radially inward, exiting the receiving recess 74 of the sleeve 30. In this way, the chuck member 34 is in the unlocked position, and the male pipe fitting 1 can be inserted to the connecting position.

[0027] As shown in Figures 5A and 5B, when the male pipe fitting 1 is further inserted into the insertion passage 20 of the female pipe fitting 10, the restraining member 38 is pushed backward by the male pipe fitting 1. As a result, the restraining member 38 is displaced from the restrained position that restrained the locking member 36 in the holding position to a released position where the locking member 36 is no longer restrained. The released sleeve 30 is then displaced forward by the biasing force of the spring 32. As a result, the locking member 36 is displaced radially inward to a released position where it does not engage with the locking groove 76 of the sleeve 30. The sleeve 30 is prevented from being displaced further forward because the forward-facing contact surface 78 formed at its tip contacts the front end 46 of the chuck member 34.

[0028] As shown in Figures 6A and 6B, when the male pipe fitting 1 is inserted to the connection position, the locking groove 3 of the male pipe fitting 1 aligns with the front end portion 46 of the chuck member 34. The chuck member 34 is pushed by the sleeve 30 or by the biasing force of the annular elastic member 54, causing the front end portion 46 to be displaced radially inward and into the locked position. As the chuck member 34 is in the locked position, the contact surface 78 of the sleeve 30 no longer contacts the front end portion 46 of the chuck member 34, so the sleeve 30 is further displaced forward by the biasing force of the spring 32 and into the connection position. The sleeve 30 in the connection position presses the front end portion 46 of the chuck member 34 from the radially outward direction, restraining the chuck member 34 in the locked position. The downstream opening 24 of the fluid passage 26 of the female pipe fitting 10 is connected to the fluid passage 2 of the male pipe fitting 1. In this way, the male pipe fitting 1 is connected to the female pipe fitting 10 by a chuck member 34 that is restrained in the locked position.

[0029] When pressurized fluid is supplied from the upstream opening 22 of the fluid passage 26 in the connected state, and fluid pressure is applied to the fluid passage 26, the valve body 44 is pushed toward the valve seat portion 72 by that fluid pressure. At the same time, a force acts on the pressure receiving member 42 located in the branch passage 28 which is in communication with the fluid passage 26, in a direction away from the fluid passage 26 (upward in the figure). When the force that the pressure receiving member 42 receives from the pressurized fluid exceeds the biasing force of the spring 66, the pressure receiving member 42 begins to move radially outward from the first position in Figure 6A. When this happens, the projection 62 of the pressure receiving member 42 engages with the inclined engagement surface 70a of the projection 70 of the valve body 44. Here, the pressure receiving area (cross-sectional area) of the pressure receiving member 42 is larger than the pressure receiving area (cross-sectional area) of the valve body 44. Therefore, even if the same amount of fluid pressure acts on the pressure-receiving member 42 and the valve body 44, the upward force exerted on the pressure-receiving member 42 by that fluid pressure is greater than the forward force exerted on the valve body 44. When the difference between these two forces exceeds a predetermined magnitude, the pressure-receiving member 42 is displaced radially outward to a second position, as shown in Figure 7. The valve body 44 receives a rearward force from the pressure-receiving member 42 via the inclined engagement surface 70a of the projection 70, and is displaced rearward to an open position away from the valve seat 72. As a result, the fluid passage 26 is opened, and the fluid flows from the upstream opening 22 through the gap between the outer circumference of the valve body 44 and the inner circumference of the fluid passage 26, and further through the downstream opening 24 into the fluid passage 2 of the male pipe joint 1.

[0030] As shown in Figure 7, when the pressure-receiving member 42 is in the second position and the valve body 44 is in the open position, the projection 62 of the pressure-receiving member 42 engages with the projection 70 of the valve body 44 at a vertical engagement surface 70b. Therefore, the direction of the force acting from the valve body 44 on the pressure-receiving member 42 is perpendicular to the vertical engagement surface 70b, i.e., backward. Thus, in this state, the pressure-receiving member 42 does not receive a force from the valve body 44 in the direction from the second position to the first position (downward in the figure). Therefore, once the pressure-receiving member 42 is displaced to the second position, even if the pressure in the fluid passage 26 decreases to some extent, the pressure-receiving member 42 will not return to the first position unless the force received by the fluid on the pressure-receiving member 42 falls below the biasing force of the spring 66, and therefore the valve body 44 will not return to the closed position. This prevents the valve body 44 from returning to the closed position due to slight fluctuations in fluid pressure after the valve body 44 has reached the open position. Furthermore, a similar effect can be obtained by forming an inclined engagement surface and a vertical engagement surface on the projection 62 of the pressure-receiving member 42.

[0031] When the supply of pressurized fluid is stopped and the pressure in the fluid passage 26 drops below a certain level, the pressure-receiving member 42 returns to the first position due to the biasing force of the spring 66, and the valve body 44 becomes displaceable to the closed position. The valve body 44 is pushed forward by the remaining pressure in the fluid passage 26 and returns to the closed position. Although not shown in this embodiment, a spring may be provided to bias the valve body 44 from the open position to the closed position. By providing such a spring, the valve body 44 can be held in the closed position even when the pressure in the fluid passage 26 is substantially eliminated. After the pressure-receiving member 42 returns to the first position, the sleeve 30 can be displaced from the connected position to the disconnected position, thereby disconnecting the male pipe fitting 1 from the female pipe fitting 10. Note that when there is a fluid pressure above a certain level in the fluid passage 26 and the pressure-receiving member 42 is in the second position, the shaft portion 56 of the pressure-receiving member 42 protrudes significantly radially outward. In this state, if an attempt is made to displace the sleeve 30 toward the uncoupled position, the contact step portion 80 of the sleeve 30 interferes with the shaft portion 56, making it impossible to displace the sleeve 30 to the uncoupled position. In other words, when the fluid pressure in the fluid passage 26 is high, the connection between the male pipe fitting 1 and the female pipe fitting 10 cannot be released. This prevents high-pressure fluid from unexpectedly gushing out when the connection is released, or prevents the male pipe fitting 1 or the female pipe fitting 10 from being blown away by the fluid pressure.

[0032] Even in the disconnected state shown in Figure 1A, when pressurized fluid is supplied into the fluid passage 26 and the fluid pressure in the fluid passage 26 increases, the pressure-receiving member 42 is pressed from the first position to the second position as described above. However, as shown in Figure 8, the shaft portion 56 of the pressure-receiving member 42 contacts the sleeve 30, preventing the pressure-receiving member 42 from being displaced to the second position. At this time, the projection 62 of the pressure-receiving member 42 is not yet engaged with the projection 70 of the valve body 44, which is in the closed position, and therefore the valve body 44 remains held in the closed position. In other words, even when pressurized fluid is supplied to the fluid passage 26 in the disconnected state, the fluid passage 26 is not opened. Furthermore, the shaft portion 56 of the pressure-receiving member 42 is pressed against and engaged with the engagement recess 82 formed on the inner circumferential surface of the sleeve 30. This prevents the sleeve 30 from being displaced. Therefore, even if the male pipe fitting 1 is inserted to the connection position in this state, the sleeve 30 will not be displaced to the connection position by the biasing force of the spring 32. The worker can recognize that pressurized fluid is already being supplied to the fluid passage 26 of the female pipe fitting 10 because the sleeve 30 does not automatically displace to the connection position. This prevents pressurized fluid from unexpectedly flowing out when connecting. In this embodiment, an engagement recess 82 is provided in the sleeve 30 to effectively prevent displacement of the sleeve 30 when the shaft portion 56 of the pressure receiving member 42 is pressed against it, but the engagement recess 82 is not necessarily required. In order to prevent displacement of the sleeve 30, it is also possible to increase the frictional force between the sleeve 30 and the shaft portion 56 by, for example, providing fine irregularities on the inner surface of the sleeve 30 or making the upper end of the shaft portion 56 out of rubber. In this case, preventing displacement of the sleeve 30 is desirable to be so strong that the sleeve 30 does not displace even when an operator tries to manipulate the sleeve 30 with great force, but it is sufficient if it is prevented from being displaced to the connection position by the biasing force of the spring 32.

[0033] In the unconnected state shown in Figure 1A, as described above, the rear end 48 of the chuck member 34 is located within the receiving recess 74 of the sleeve 30. If, due to some incorrect operation, the restraining member 38 is pushed backward to the release position as shown in Figure 9, the locking member 36 will move to the release position and the sleeve 30 will be released. However, the rear end 48 of the chuck member 34 engages with the sleeve 30 in the receiving recess 74, preventing the sleeve 30 from being displaced to the connected position. This makes it possible to avoid a mis-lock state in which the chuck member 34 is held in the locked position due to incorrect operation of the restraining member 38. If the sleeve 30 is displaced slightly backward from the state shown in Figure 9, the locking member 36 will again be displaced radially outward to the holding position, and the restraining member 38 will be displaced forward to the restrained position, and the female pipe fitting 10 will return to the state shown in Figure 1A. Furthermore, if the locking groove 76 is positioned slightly further back relative to the locking member 36, the locking member 36 will enter the locking groove 76 when the restraining member 38 attempts to return to the forward position due to the biasing force of the spring 40, causing the sleeve 30 to be displaced backward and automatically returning to the state shown in Figure 1A.

[0034] As shown in Figures 5A and 5B, when the chuck member 34 moves from the unlocked position to the locked position, the locking member 36 releases its hold on the sleeve 30, and as described above, the inclined contact surface 78 of the sleeve 30 engages with the front end 46 of the chuck member 34. When the male pipe fitting 1 is pulled out of the fluid passage 26 in this state, the chuck member 34 returns to the unlocked position. At that time, the front end 46 of the chuck member 34 is displaced radially outward, and as a result, the sleeve 30 is pushed by the chuck member 34 at the contact surface 78, returning to the state shown in Figures 4A and 4B. That is, the sleeve 30 returns to the disconnected position. Then, when the male pipe fitting 1 is pulled out of the fluid passage 26, the sleeve 30 is held in the disconnected position by the locking member 36, and the female pipe fitting 10 returns to the disconnected state shown in Figure 1A. In other words, even if the male pipe fitting 1 is partially inserted into the fluid passage 26 and then withdrawn, it is possible to avoid a mis-lock state in which the chuck member 34 is constrained in the locked position.

[0035] Although embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, the locking element for locking the corresponding pipe fitting may be a spherical locking element instead of a chuck member. The pipe fitting of the present invention is applicable to supply lines of various fluids such as compressed air, hydraulic fluid, water, and inert gas.

[0036] 1 Male pipe fitting (corresponding pipe fitting) 2 Fluid passage 3 Locking groove 10 Female pipe fitting (pipe fitting) 12 Cylindrical wall section 14 Flow path component section 16 Fitting body 18 Front end opening 20 Insertion passage 22 Upstream opening 24 Downstream opening 26 Fluid passage 28 Branch passage 30 Sleeve 32 Spring 34 Chuck member (locking element) 36 Locking member 38 Restraining member 40 Spring 42 Pressure receiving member 44 Valve body 46 Front end (one end) 48 Rear end (other end) 50 Central section 52 Recess 54 Annular elastic member (biasing member) 56 Shaft section 58 Annular groove 60 Extended section 62 Protrusion 64 O-ring 66 Spring 68 Recess 70 Protrusion 70a Inclined engagement surface 70b Vertical engagement surface 72 Valve seat portion 74 Receiving recess 76 Locking groove 78 Contact surface 80 Contact step portion 82 Engagement recess

Claims

1. A pipe fitting that detachably connects a corresponding pipe fitting, comprising: a pipe fitting body having a cylindrical wall portion extending rearward from a front end opening and defining an insertion passage for receiving the corresponding pipe fitting; a fluid passage extending from an upstream opening to a downstream opening connected to a fluid passage of the corresponding pipe fitting and having a valve seat portion between the upstream opening and the downstream opening; and a branch passage branching off from the fluid passage upstream of the valve seat portion; a locking element disposed on the pipe fitting body and displaceable between a locked position that protrudes into the insertion passage and engages with a locking groove of the corresponding pipe fitting inserted into the insertion passage, and an unlocked position that is displaced radially outward from the locked position to release engagement with the locking groove; and a pressure receiving member disposed in the branch passage and displaceable from a first position to a second position by the fluid pressure in the fluid passage. A pipe joint comprising: a valve body disposed within the fluid passage and displaceable between a closed position in which it is sealedly engaged with the valve seat to close the fluid passage and an open position in which it opens the fluid passage, wherein the valve body is moved from the closed position to the open position by the pressure-receiving member when the pressure-receiving member is displaced from the first position to the second position; and a sleeve disposed outside the joint body, which is displaceable between a disengaged position in which the locking element is allowed to be displaced to the unlocked position and a connected position in which the locking element is constrained to the locked position, wherein when the sleeve is in the disengaged position and the pressure-receiving member is pressed from the first position to the second position by the pressure in the fluid passage, the pressure-receiving member is pressed against the sleeve before the valve body reaches the open position, thereby preventing the sleeve from being displaced.

2. The pipe joint according to claim 1, wherein the sleeve has an engagement recess into which the pressure-receiving member engages, and the pressure-receiving member engages with the engagement recess when the pressure-receiving member is displaced from a first position toward a second position while the sleeve is in the disconnected position.

3. The pipe joint according to claim 1, wherein the pressure-receiving area of ​​the pressure-receiving member is larger than the pressure-receiving area of ​​the valve body.

4. The pipe joint according to claim 1, wherein the valve body has a recess and a projection formed within the recess, the pressure receiving member has an extended portion extending into the recess and a projection formed on the extended portion, and when the pressure receiving member is displaced from a first position to a second position, the projection of the pressure receiving member engages with the projection of the valve body, thereby displacing the valve body toward the open position.

5. The pipe joint according to claim 4, wherein a projection on one of the valve body and the pressure-receiving member has an inclined engagement surface that is inclined with respect to the displacement direction of the valve body and a vertical engagement surface that is perpendicular to the displacement direction, and when the pressure-receiving member is displaced from a first position to a second position, the projection on the other of the valve body and the pressure-receiving member engages with the inclined engagement surface, causing the valve body to open, and when the pressure-receiving member is in the second position, the projection on the other engages with the vertical engagement surface.

6. The pipe joint according to claim 1, further comprising a spring that biases the sleeve from the disconnected position toward the connected position.

7. The pipe joint according to claim 1, further comprising a spring that biases the pressure-receiving member from the second position toward the first position.

8. The pipe joint according to claim 7, wherein when the sleeve is displaced from the connection position toward the disconnection position while the pressure receiving member is in the second position, the pressure receiving member interferes with the sleeve and prevents the sleeve from being displaced to the disconnection position.

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