Pipe joint provided with erroneous locking prevention function

Abstract

[Problem] To provide a pipe joint capable of more reliably preventing an erroneous locking state. [Solution] A female pipe joint 10 comprises a cylindrical wall part 12, a sleeve 30, a chuck member (locking element) 34 and a latching member 36 that are disposed on the cylindrical wall part 12, a restraining member 38 that is disposed within an insertion passage 20 in the cylindrical wall part 12, and an annular elastic member (biasing member) 54 that biases the chuck member 34 toward an initial position. The chuck member 34 has a front end part (one end part) 46 and a rear end part (the other end part) 48. In a non-connection state, the sleeve 30 is held at a connection release position by the latching member 36. The rear end part of the chuck member 34 is positioned within a receiving recess 74 formed in the inner peripheral surface of the sleeve 30. Even if the restraining member 38 is erroneously operated and the hold on the sleeve 30 by the latching member 36 is released, the rear end part 48 of the chuck member 34 is engaged with the sleeve 30, and thus the sleeve 30 is not displaced to a connection position.

Description

Pipe joint with mis-lock prevention function

[0001] The present invention relates to a pipe joint configured to detachably connect a corresponding pipe joint, and more particularly to a pipe joint provided with a mis-lock prevention function.

[0002] A conventional female pipe joint (pipe joint) configured to detachably connect a corresponding male pipe joint (corresponding pipe joint) connects the male pipe joint by engaging a spherical locking element with a locking groove formed on the outer peripheral surface of the male pipe joint. For example, in Patent Document 1, the locking element is disposed in a locking element holding hole formed in a cylindrical wall portion defining an insertion passage for receiving the male pipe joint, and the locking element is held by a collar from the inner side when the male pipe joint is not inserted into the insertion passage, which is a disclosed female pipe joint. When the male pipe joint is inserted into the insertion hole of this female pipe joint, the collar is pushed by the male pipe joint and displaced rearward, and accordingly the locking element becomes displaceable radially inward. When the locking groove of the male pipe joint is aligned with the locking element, the locking element is pushed radially inward by a sleeve disposed outside the cylindrical wall portion and engages with the locking groove of the male pipe joint. The locking element engaged with the locking groove is held from the radially outer side by the sleeve and restrained at the position engaged with the locking groove. In this way, the connection between the male pipe joint and the female pipe joint is achieved.

[0003] In the above-described female pipe joint, if the collar is inappropriately pushed, for example, when the male pipe joint is pulled out suddenly after being inserted partway, or when an incorrect male pipe joint, an elongated member, or the like is inserted into the insertion passage, the sleeve may erroneously restrain the locking element in the radially inward displaced locking position, which is so-called mis-lock.

[0004] Patent Document 1 further discloses a configuration in which, in addition to a first locking element for locking the male pipe joint, a second locking element for holding the sleeve is provided on the cylindrical wall portion defining the insertion passage, and the collar supports the second locking element from the radially inner side to hold it in a state engaged with the sleeve. In this female pipe joint, since the collar is disposed at a deep position in the fluid passage, mis-lock is less likely to occur, but mis-lock can still occur.

[0005] Furthermore, in the female pipe fitting described above, the valve is designed to open in conjunction with the rearward displacement of the collar. Therefore, if a mis-lock occurs, the valve will remain open, and there is a risk that the internal fluid will continue to leak.

[0006] Patent No. 5317761

[0007] In conventional female pipe fittings as described above, if the collar supporting the locking element is operated improperly, the locking element for locking the male pipe fitting will become stuck in the locked position. In this mis-locked state, it is possible to return to the original state by displacing the sleeve backward, but if the operator does not notice the mis-locked state and attempts to force the connection, there is a risk of damaging the female or male pipe fitting. Furthermore, if the collar and valve body are linked, in a mis-locked state the valve body will remain in the open position, causing the internal fluid to continue to leak.

[0008] Therefore, the present invention aims to provide a pipe joint that can more reliably prevent mis-locking.

[0009] In other words, the present invention provides a pipe joint for detachably connecting a corresponding pipe joint, comprising: a cylindrical wall portion extending rearward from a front end opening and defining an insertion passage for receiving the corresponding pipe joint to a predetermined connection position; and a sleeve disposed relative to the cylindrical wall portion so as to be displaceable between a disconnected position and a connected position. A locking element having one end and the other end, and positioned to be displaceable between an initial position, an unlocked position and a locked position, wherein in the initial position, the one end protrudes into the insertion passage and the other end prevents the sleeve from moving from the disengaged position to the connected position; in the unlocked position, the corresponding pipe fitting can be inserted to the connected position; in the locked position, the one end engages with the locking groove of the corresponding pipe fitting inserted to the connected position to hold the corresponding pipe fitting and the other end does not prevent the sleeve from moving; the locking element is displaceable between the initial position, the unlocked position and the locked position when the sleeve is in the disengaged position and is constrained to the locked position when the sleeve is in the connected position; and a biasing member that biases the locking element toward the initial position. A pipe joint is provided, comprising: a locking member disposed on the cylindrical wall portion and displaceable between a holding position that engages with the sleeve in the disconnected position to hold the sleeve in the disconnected position and a release position that releases the holding of the sleeve; and a restraining member disposed in the insertion passage and displaceable between a restraining position that restrains the locking member in the holding position and a release position that allows the locking member to displace to the release position, wherein the restraining member is moved from the restraining position to the release position by the corresponding pipe joint inserted into the insertion passage.

[0010] In this pipe joint, when the sleeve is in the unconnected position, the locking element, which is biased to its initial position by the biasing member, prevents the sleeve from moving from the unconnected position to the connected position. Therefore, even if the restraining member is mistakenly moved to the restrained position and the locking member moves to the released position, causing the sleeve to lose its hold, the sleeve is prevented from moving to the connected position by the locking element. This prevents a mis-locked state in which the locking element becomes locked in the unconnected state.

[0011] Furthermore, the sleeve may have a contact surface that is inclined radially outward in the direction from the disengaged position toward the connected position, so that when the locking element is in the unlocked position, the contact surface abuts against the one end, preventing the sleeve from being displaced toward the connected position.

[0012] Furthermore, when the locking element is displaced to the initial position while one end of the locking element is in contact with the contact surface, the sleeve can be pushed by the locking element on the contact surface and displaced to the release position.

[0013] Furthermore, the sleeve may have a receiving recess on its inner circumferential surface, so that when the locking element is in the initial position, the other end is located within the receiving recess.

[0014] Furthermore, the locking element may have a central portion between one end and the other end, and when displaced from the initial position to the unlocking position, it may swing around the central portion so that one end is displaced radially outward and the other end is displaced radially inward.

[0015] Furthermore, the locking elements can be arranged in a plurality in line in the circumferential direction of the cylindrical wall portion, and the biasing member can be an annular elastic member arranged around one end of the plurality of locking elements to bias each end radially inward.

[0016] Hereinafter, embodiments of the pipe joint according to the present invention will be described based on the attached drawings.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] Although embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, a pipe fitting without a valve structure may be used. Alternatively, a valve structure that is opened by the corresponding pipe fitting during the connection process may be used. The pipe fitting of the present invention is applicable to supply lines for various fluids such as compressed air, hydraulic fluid, water, and inert gas.

[0034] 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 allows a corresponding pipe fitting to be detachably connected, comprising: a cylindrical wall portion extending rearward from a front end opening and defining an insertion passage for receiving the corresponding pipe fitting to a predetermined connection position; and a sleeve disposed relative to the cylindrical wall portion so as to be displaceable between a disconnected position and a connected position; A locking element having one end and the other end, and positioned to be displaceable between an initial position, an unlocked position and a locked position, wherein in the initial position, the one end protrudes into the insertion passage and the other end prevents the sleeve from moving from the disengaged position to the connected position; in the unlocked position, the corresponding pipe fitting can be inserted to the connected position; in the locked position, the one end engages with the locking groove of the corresponding pipe fitting inserted to the connected position to hold the corresponding pipe fitting and the other end does not prevent the sleeve from moving; the locking element is displaceable between the initial position, the unlocked position and the locked position when the sleeve is in the disengaged position and is constrained to the locked position when the sleeve is in the connected position; and a biasing member that biases the locking element toward the initial position. A pipe joint comprising: a locking member disposed on the cylindrical wall portion and displaceable between a holding position that engages with the sleeve in the disconnected position to hold the sleeve in the disconnected position and a release position that releases the holding of the sleeve; and a restraining member disposed in the insertion passage and displaceable between a restraining position that restrains the locking member in the holding position and a release position that allows the locking member to displace to the release position, wherein the restraining member is moved from the restraining position to the release position by the corresponding pipe joint inserted into the insertion passage.

2. The pipe joint according to claim 1, wherein the sleeve has a contact surface that is inclined radially outward in the direction from the disengaged position toward the connected position, and when the locking element is in the unlocked position, the contact surface contacts the one end to prevent the sleeve from being displaced toward the connected position.

3. The pipe joint according to claim 2, wherein when the locking element is displaced to the initial position while one end of the locking element is in contact with the contact surface, the sleeve is pushed by the locking element on the contact surface and displaced to the release position.

4. The pipe joint according to claim 1, wherein the sleeve has a receiving recess on its inner circumferential surface, and the other end is located within the receiving recess when the locking element is in the initial position.

5. The pipe joint according to claim 1, wherein the locking element has a central portion between the one end and the other end, and when displaced from the initial position to the unlocking position, it swings around the central portion so that the one end is displaced radially outward and the other end is displaced radially inward.

6. The pipe joint according to claim 1, wherein a plurality of the locking elements are arranged in a line in the circumferential direction of the cylindrical wall portion, and the biasing member is an annular elastic member arranged around one end of the plurality of the locking elements, biasing each end radially inward.

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