Patent Publication Number: US-2022214016-A1

Title: Safety joint

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to JP2021-000751 filed on Jan. 6, 2021, the disclosure of which is incorporated herein by reference. 
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
     Not Applicable 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a filling apparatus for filling gas such as hydrogen gas used as fuel. More particularly, the present invention relates to a pipe joint for separating the filling apparatus and a gas filling nozzle from each other in an emergency while a gas is filled with the filling apparatus. 
     2. Description of the Related Art 
     For example, as show in  FIG. 8 , to a vehicle  400  using hydrogen as fuel, at a hydrogen filling station is filled hydrogen gas after a filling nozzle  202  attached to an end of a filling hose  201  of a hydrogen filling apparatus  200  and a vehicle side filling port  203  are connected with each other. The filling is performed while being controlled depending on the maximum using pressure of a hydrogen tank  204  mounted to the vehicle  400 . Here, when the vehicle  400  runs to pull the filling hose  201  while hydrogen gas is filled, for instance, parts such as the filling nozzle  202  and the filling hose  201  are broken to inject a hydrogen gas, so that it becomes a dangerous condition. Then, a pipe joint  100  for emergency releasing is mounted between the hydrogen filling apparatus  200  and the filling hose  201 , and when to the filling hose  201  is applied a tensile force more than a predetermined value, the pipe joint  100  for emergency releasing is divided to prevent the parts such as the filling nozzle  202  and the filling hose  201  from being broken. 
     As a prior art, the present applicant proposed a pipe joint for emergency releasing including: a cylindrical plug (filling nozzle side member) in which a flow path is formed; a cylindrical socket (filling apparatus side member) in which a flow path is formed; and when the plug is inserted into the socket, shutoff valves open the flow paths of the plug and the socket to communicate the flow paths with each other, and when the plug is disconnected from the socket, the shutoff valves close. In the pipe joint for emergency releasing, central axes of the flow paths of the plug and the socket do not form the same straight line; when the plug is inserted into the socket, an end of a socket side valve stem (an end, opposing the end of the socket side valve stem, of a valve element) contacts with a plug side rod accommodating case and a valve element mounted to the other side of the socket side valve stem is held at a position separated from a socket side valve seat against an elastic repulsive force of an elastic body on the socket side, and a locking member held in the plug side rod accommodating case is restricted to move radially outward by an inner wall at a socket body side opening, and a plug side valve stem contacts with the locking member and does not move toward the socket side, and a valve body provided on the plug side valve stem is held at a position separated from a plug side valve seat against an elastic repulsive force of an elastic body on the plug side (refer to Patent Document 1). This pipe joint (disclosed in the Patent Document 1) is very useful. 
     However, in the pipe joint  100  (of the Patent Document 1), when a large tensile force acts on the filling hose  201  (shown in  FIG. 8 ), and as shown in  FIG. 9 , at an initial stage of the process that the plug  10  is pulled out from the socket  22  (the stage at which the plug  10  starts to come out), the socket side rod  22  connected to the valve body  25  on the socket  20  side is placed on the plug side valve stem  2  or a cover member  3  of the valve stem. Under the condition (the state shown in  FIG. 9 ), the socket side valve body  25  positions separately from the socket side valve seat  21 E against an elastic repulsive force of a spring  23  on the socket  20  side, which causes the socket side shutoff valve  24  to be held in an open state. For that reason, at the initial stage where the plug  10  is ejected from the socket  20  (the stage where the plug  10  is beginning to be ejected), a high-pressure hydrogen gas supplied from the filling apparatus  200  ( FIG. 8 ) through the opening portion  21 C on the socket  20  side flows out to the outside of the pipe joint  100  as a so-called “outgas”. In  FIG. 9 , the outflow of the outgas is indicated by the arrow OG. 
     Prior Art document Japan Patent No. 6540967 
     BRIEF SUMMARY 
     The first to third inventions of the present application have been made in consideration of the above problems in the prior art, and the object thereof is to provide a safety joint that can immediately shut off a hydrogen gas flow path at the initial stage when a plug, which is a nozzle side member, comes out of a socket, which is a filling apparatus side member, to prevent release of outgas. 
     A safety joint ( 100 ) according to the first invention of the present application includes: a cylindrical nozzle side member (plug  10 ) with a flow path (plug side flow path R 10 ) formed inside, a shutoff valve (plug side shutoff valve V 10 ) of the nozzle side member ( 10 ) opens when the nozzle side member ( 10 ) is connected to a filling apparatus side member (socket  20 ); and the filling apparatus side member ( 20 ) with a cylindrical shape and a flow path (socket side flow path R 20 ) formed inside, the filling apparatus side member ( 20 ) can be connected to the nozzle side member ( 10 ), and when the nozzle side member ( 10 ) is disconnected from the filling apparatus side member ( 20 ), the shutoff valve (V 10 ) of the nozzle side member ( 10 ) closes and the flow path (R 20 ) of the filling apparatus side member ( 20 ) closes, the safety joint ( 100 ) (for emergency releasing) is characterized in that: central axes of the flow paths (R 10 , R 20 ) of the nozzle side member ( 10 ) and the filling apparatus side member ( 20 ) are arranged orthogonally; the nozzle side member ( 10 ) has a protruding portion (plug side protruding portion  12 ) with a diameter smaller than a region in which a valve body (plug side valve body  3 ) is housed, and the protruding portion ( 12 ) is formed with a through hole ( 12 T) that communicates the flow path ( 14 ,  15 ) of the nozzle side member ( 10 ) and the flow path ( 222 ,  223 ) of the filling apparatus side member ( 20 ); the filling apparatus side member ( 20 ) has an opening portion (through hole  220 ) into which the protruding portion ( 12 ) of the nozzle side member ( 10 ) is inserted, the opening portion ( 220 ) extending in a direction orthogonal to the flow path of the filling apparatus side member ( 20 ); the opening portion ( 220 ) is provided with a slidable closing member ( 8 ) and an elastic member (socket side spring  9 ) that urges the closing member ( 8 ) in a direction that the nozzle side member ( 10 ) comes off; and the safety joint ( 100 ) further incudes a closing member holding mechanism that holds the closing member ( 8 ) at a position separated from the nozzle side member ( 10 ) when the nozzle side member ( 10 ) and the filling apparatus side member ( 20 ) are connected. 
     In the first invention, it is preferable that the safety joint ( 100 ) further includes an extension portion ( 24 ) having a space ( 243 ) in which the opening portion ( 220 ) is extended in an opposite direction of the nozzle side member ( 10 ), and the closing member ( 8 ) is disposed between the opening portion ( 220 ) of the filling apparatus side member ( 20 ) and the space ( 243 ) of the extension portion ( 24 ). And, in the protruding portion ( 12 ) of the nozzle side member ( 10 ) is preferably formed the flow path (R 10 ) of the nozzle side member ( 10 ). In addition, no valve body is preferably arranged in the flow path (R 20 ) of the filling apparatus side member ( 20 ). Further, a sealing material (for example, O-ring  7 ) is preferably arranged at the opening portion ( 220 ) of the filling apparatus side member ( 20 ) to seal the boundary with the protruding portion ( 12 ) of the nozzle side member or the closing member  8 . 
     A safety joint ( 100 A) according to the second invention of the present application includes: a cylindrical nozzle side member (plug  10 A) with a flow path (plug side flow path R 10 A) formed inside, a shutoff valve (plug side shutoff valve V 10 ) of the nozzle side member ( 10 A) opens when the nozzle side member ( 10 A) is connected to a filling apparatus side member (socket  20 A); and the cylindrical filling apparatus side member ( 20 A) with a flow path (socket side flow path R 20 A) formed inside, a shutoff valve (socket side shutoff valve V 20 ) of the filling apparatus side member ( 20 A) opens when the filling apparatus side member ( 20 A) is connected to the nozzle side member ( 10 A); and when the nozzle side member ( 10 A) is disconnected from the filling apparatus side member ( 20 A), the shutoff valves ( 10 A,  20 A) of the nozzle side member ( 10 A) and the filling apparatus side member ( 20 A) close, the safety joint ( 100 A) (for emergency releasing) is characterized in that: central axes of the flow paths (R 10 A, R 20 A) of the nozzle side member ( 10 A) and the filling apparatus side member ( 20 A) are arranged orthogonally; the nozzle side member ( 10 A) has a protruding portion (plug side protruding portion  12 ) with a diameter smaller than a region in which a valve body (plug side valve body  3 ) is housed, and the protruding portion ( 12 ) is formed with a through hole ( 12 T) that communicates the flow path of the nozzle side member ( 10 A) and the flow path of the filling apparatus side member ( 20 A); the filling apparatus side member ( 20 A) has an opening portion (through hole  220 ) into which the protruding portion ( 12 ) of the nozzle side member is inserted, the opening portion (through hole  220 ) extending in a direction orthogonal to the flow path (in-socket flow path R 20 A) of the filling apparatus side member; in a flow path (Fa 1 ) of the filling apparatus side member are mounted a support member ( 60 ) that supports the valve body ( 30 ) of the shutoff valve (V 20 ) on the filling apparatus side so as to be separated from a valve seat (V 20 ) and an elastic body (socket side spring  40 ) that presses the valve body ( 30 ) toward the opening portion ( 220 ) side when the nozzle side member ( 10 A) is connected to the filling apparatus side member ( 20 A); the safety joint ( 100 A) further incudes: a rod ( 81 A) that can be inserted into the opening portion ( 220 ) of the filling apparatus side member ( 20 A) and can be brought into contact with a tip of the protruding portion ( 12 ) of the nozzle side member ( 10 A); a disk-shaped member ( 82 A) fixed to the rod ( 81 A); an elastic member ( 9 ) for urging the rod ( 81 A) and the disk-shaped member ( 82 A) in a direction that the nozzle side member ( 10 A) comes off, and an outer diameter of the disk-shaped member ( 82 A) is larger than an inner diameter of the opening portion ( 220 ) of the filling apparatus side member ( 20 A); and the safety joint ( 100 A) further incudes a closing member holding mechanism that holds the disk-shaped member ( 82 A) and the rod ( 81 A) at a position separated from the nozzle side member ( 10 A) when the nozzle side member ( 10 A) and the filling apparatus side member ( 20 A) are connected. 
     In the second invention, it is preferable that the safety joint ( 100 A) further includes an extension portion ( 24 ) having a space ( 243 ) in which the opening portion ( 220 ) is extended in an opposite direction of the nozzle side member ( 10 A), and the rod ( 81 A) is movable between the space ( 243 ) of the extension portion ( 24 ) and the opening portion ( 220 ) of the filling apparatus side member, and the disk-shaped member ( 82 A) moves in the space ( 243 ) of the extension portion ( 24 ) only. 
     In the first and second inventions, it is preferable that the closing member holding mechanism includes a long member ( 13 ) and a rotation locking member ( 13 L); the long member ( 13 ) extends parallel to the opening portion ( 220 ) of the filling apparatus side member ( 20 ,  20 A), an end of the long member ( 13 ) is attached (fixed) to an area ( 14 ) where the valve body (plug side valve body  3 ) of the nozzle side member is housed, another end ( 13 L) of the long member ( 13 ) extends to a vicinity of an end ( 82 ,  82 A), of the closing member ( 8 ,  8 A), separated from the nozzle side member ( 10 ,  10 A), the other end ( 13 L) is arranged at a position where the nozzle side member ( 10 ,  10 A) is locked to the rotation locking member ( 31 ) when the nozzle side member ( 10 ,  10 A) is connected to the filling apparatus side member ( 20 ,  20 A), and thereby provides a function of transmitting disengagement movement of the nozzle side member ( 10 ,  10 A) to the rotation locking member ( 31 ) via the other end ( 13 L) when the nozzle side member ( 10 ,  10 A) is disengaged from the filling apparatus side member ( 20 ,  20 A); and the rotation locking member ( 31 ) is pivotally and rotatably supported, when the nozzle side member ( 10 ,  10 A) is connected to the filling apparatus side member ( 20 ,  20 A), an end ( 31   a ) engages with an end of the closing member ( 8 ,  8 A) in such a manner as to prevent the nozzle side member ( 10 ,  10 A) from coming off the filling apparatus side member ( 20 ,  20 A), another end ( 31   b ) engages with the other end ( 13 L) of the long member ( 13 ), when the nozzle side member ( 10 ,  10 A) comes off from the filling apparatus side member ( 20 ,  20 A), movement of the nozzle side member is transmitted through the long member ( 13 ) and the other end ( 13 L) to the rotation locking member ( 31 ) and the rotation locking member ( 31 ) rotates, and the engagement between the end ( 31   a ) and the closing member ( 8 ,  8 A) is released. 
     A safety joint ( 100 B) according to the third invention of the present application includes: a cylindrical nozzle side member (plug  10 B) with a flow path (in-plug flow path R 10 B) formed inside, a shutoff valve (plug side shutoff valve V 10 ) opens when the nozzle side member ( 10 B) is connected to a filling apparatus side member (socket  20 B); and the cylindrical filling apparatus side member ( 20 B) with a flow path (in-socket flow path R 20 B) formed inside, a shutoff valve (socket side shutoff valve V 20 ) opens when the filling apparatus side member ( 20 B) is connected to the nozzle side member ( 10 B); and when the nozzle side member ( 10 B) is disconnected from the filling apparatus side member ( 20 B), the shutoff valves (V 10 , V 20 ) of the nozzle side member ( 10 B) and the filling apparatus side member ( 20 B) close, the safety joint ( 100 B) (for emergency releasing) is characterized in that: central axes of the flow paths (R 10 B, R 20 B) of the nozzle side member ( 10 B) and the filling apparatus side member ( 20 B) are arranged orthogonally; the nozzle side member ( 10 B) has a protruding portion (plug side protruding portion  12 ) having a diameter smaller than a region in which a valve body (plug side valve body  3 ) is housed, and the protruding portion ( 12 ) is formed with a through hole ( 12 T) that communicates the flow path (R 10 B) of the nozzle side member ( 10 B) and the flow path (R 20 B) of the filling apparatus side member ( 20 B); the filling apparatus side member ( 20 B) has an opening portion (through hole  220 ), into which the protruding portion ( 12 ) of the nozzle side member is inserted, extending in a direction orthogonal to the flow path (R 20 B) of the filling apparatus side member ( 20 B), and an extension portion ( 24 B) having a space ( 243 B) in which the opening portion ( 220 ) is extended in the opposite direction of the nozzle side member ( 10 B) is provided; in the flow path (R 20 B) of the filling apparatus side member ( 20 B) are mounted a support member ( 60 ) that supports the valve body ( 30 ) of the shutoff valve (V 20 ) on the filling apparatus side so as to be separated from the valve seat (V 20 ) and an elastic body (socket side spring  40 ) that presses the valve body ( 30 ) toward the opening portion ( 220 ) side when the nozzle side member ( 10 B) is connected to the filling apparatus side member ( 20 B); the safety joint ( 100 B) further incudes an opening portion closing member ( 8 B) that can slide in a space ( 243 B) of the extension portion ( 24 B) and the opening portion ( 220 ) of the filling apparatus side member ( 20 B), and an elastic member ( 9 B) that urges the opening portion closing member ( 8 B) in a direction that the nozzle side member ( 10 B) comes off; and the safety joint ( 100 B) further incudes a decompression mechanism for reducing a pressure at the opening portion ( 220 ) of the filling apparatus side member. 
     In the third invention, it is preferable that the safety joint ( 100 B) further includes an extension portion ( 24 B) having a space ( 243 B) in which the opening portion ( 220 ) is extended in an opposite direction of the nozzle side member ( 10 B), and the closing member ( 8 B) is movable between the space ( 243 B) of the extension portion ( 24 B) and the opening portion ( 220 ) of the filling apparatus side member. Further, in the third invention, it is preferable that the decompression mechanism has a small hole ( 84 ) formed in the opening portion closing member ( 8 B) and a decompression through hole ( 246 ) provided at an end of the extension portion ( 24 B) on a side separated from the nozzle side member ( 10 B). In addition, the decompression through hole ( 246 ) is preferably in communication with a pressure valve (not shown). 
     In the second and third inventions, a sealing material (for example, O-ring  7 ) for sealing the boundary with the protruding portion ( 12 ) of the nozzle side member ( 10 B) is preferably arranged at the opening portion ( 220 ) of the filling apparatus side member ( 20 B). 
     According to the safety joint of the first invention of the present application with the above-mentioned configuration, although the opening portion (through hole  220 ) into which the protruding portion ( 12 ) of the nozzle side member ( 10 ) is inserted is formed in the filling apparatus side member ( 20 ) so as to extend in a direction orthogonal to the flow path (in-socket flow path R 20 ) of the filling apparatus side member ( 20 ), and the closing member ( 8 ) slidable in the opening portion ( 220 ) and the elastic member (socket side spring  9 ) that urges the closing member ( 8 ) in the direction in which the nozzle side member ( 10 ) is disengaged are provided, when the nozzle side member ( 10 ) and the filling apparatus side member ( 20 ) are connected, the closing member ( 8 ) is held at a position separated from the nozzle side member ( 10 ) by the closing member holding mechanism. Thereby, when the nozzle side member ( 10 ) and the filling apparatus side member ( 20 ) are connected, the closing member holding mechanism does not block the flow path of the filling apparatus side member ( 20 ), and hydrogen supplied from the hydrogen filling apparatus is filled into a tank in a fuel cell vehicle with a hydrogen filling nozzle though the hydrogen supply port ( 25 ) of the filling apparatus side member ( 20 ), the flow path (R 20 ) of the filling apparatus side member, the through hole ( 12 T) formed in the protruding portion ( 12 ) of the nozzle side member ( 10 ), the flow path (R 10 ) of the nozzle side member ( 10 ), and the hydrogen outlet of the nozzle side member. If the nozzle side member ( 10 ) is pulled out from the filling apparatus side member ( 20 ) due to some trouble, at the initial stage of the pulling out, the closing member holding mechanism will not hold the closing member ( 8 ) at a position separated from the nozzle side member ( 10 ). Since the elastic member (spring  9 ) urges the closing member ( 8 ), the closing member ( 8 ) moves together with the protruding portion ( 12 ) of the nozzle side member ( 10 ) in a direction in which the nozzle side member ( 10 ) comes off. As a result, even if the closing member ( 8 ) is removed, the socket side flow path (R 20 ) is blocked by either the protruding portion ( 12 ) of the nozzle side member ( 10 ) or the closing member ( 8 ), and the socket side flow path (R 20 ) is closed, so that the hydrogen gas remaining in the socket side flow path (R 10 ) does not flow out to the outside of the safety joint ( 100 ). Then, when the nozzle side member ( 10 ) is separated from the filling apparatus side member ( 20 ), the flow rate of the high-pressure gas discharged as outgas from the safety joint ( 100 ) is extremely reduced. 
     According to the safety joint ( 100 A) of the second invention of the present application with the above-mentioned configuration, the support member ( 60 ) and the elastic body (socket side spring  40 ) that presses the valve body ( 30 ) to the opening portion ( 243 ) side are provided in the flow path (R 20 A) of the filling apparatus side member ( 20 A), the rod ( 81 A) that can be inserted into the opening portion ( 220 ) of the filling apparatus side member ( 20 A) and is capable of contacting the tip of the protruding portion ( 12 ) of the nozzle side member ( 10 A), the disk-shaped member ( 82 A) fixed to the rod ( 81 A), and the elastic member ( 9 ) that urges the rod ( 81 A) and the disk-shaped member ( 82 A) in the direction that the nozzle-side member ( 10 A) is disengaged are provided, and the outer diameter of the disk-shaped member ( 82 A) is larger than the inner diameter of the opening portion ( 220 ) of the filling apparatus side member ( 20 A), and the closing member holding mechanism that holds the disk-shaped member ( 82 A) and the rod ( 81 A) at a position separated from the nozzle side member ( 10 A) when the nozzle side member ( 10 A) and the filling apparatus side member ( 20 A) are connected is mounted. Thereby, when the nozzle side member ( 10 A) and the filling apparatus side member ( 20 A) are connected, the shutoff valve (V 20 ) of the filling apparatus side member ( 20 A) is held in an open state by the support member ( 60 ), and the hydrogen supplied from the hydrogen filling apparatus is filled in a tank inside a fuel cell vehicle with a hydrogen filling nozzle through the hydrogen supply port ( 25 ) of the filling apparatus side member ( 20 A), the flow path (R 20 A) of the filling apparatus side member ( 20 A), the through hole ( 12 T) formed in the protruding portion ( 12 ) of the nozzle side member ( 10 A), the flow path (R 10 A) of the nozzle side member ( 10 A), and the hydrogen outlet ( 5 ) of the nozzle side member ( 10 A). 
     In the second invention, when the nozzle side member ( 10 A) is ejected from the filling apparatus side member ( 20 A), at the initial stage of the ejection, the position of the through hole ( 12 T) formed on the protruding portion ( 12 ) of the nozzle side member ( 10 A) does not match the position of the flow path of the filling apparatus side member ( 20 A), thereby the protruding portion ( 12 ) of the nozzle side member ( 10 A) closes the flow path (R 20 A) of the filling apparatus side member ( 20 A). Further, when the nozzle side member ( 10 A) comes out of the filling apparatus side member ( 20 A), the closing member holding mechanism does not hold the disk-shaped member ( 82 A) and the rod ( 81 A) at positions separated from the nozzle side member ( 10 A), so that the disk-shaped member ( 82 A) is pressed against the opening portion ( 220 ) of the filling apparatus side member ( 20 A) by the elastic member ( 9 ). Here, since the outer diameter of the disc-shaped member ( 82 A) is larger than the inner diameter of the opening portion ( 220 ), when the disc-shaped member ( 82 A) is caused to be pressed against the opening portion ( 220 ) of the filling apparatus side member by the elastic member ( 9 ), the opening portion ( 220 ) of the filling apparatus side member ( 20 A) is closed. Further, the support member ( 60 ) does not hold the shutoff valve (V 20 ) of the filling apparatus side member ( 20 A) in an open state, and the shutoff valve (V 20 ) of the filling apparatus side member ( 20 A) is closed, thereby the hydrogen gas from the filling apparatus side is completely shut off by the shutoff valve (V 20 ) of the filling apparatus side member ( 20 A). 
     According to the safety joint ( 100 B) of the third invention of the present application with the above-mentioned configuration, the nozzle side member ( 10 B) has a protrusion (plug side protrusion  12 ) with a diameter smaller than the region in which the valve body (plug side valve body  3 ) is accommodated, the protrusion ( 12 ) has a through hole ( 12 T) for communicating the flow path (R 10 B) of the nozzle side member ( 10 B) and the flow path (R 20 B) of the filling apparatus side member ( 20 B) is formed in the protrusion ( 12 ), and the opening portion (through hole  220 ) into which the protrusion ( 12 ) of the nozzle side member ( 10 B) is inserted is formed so as to extend in a direction orthogonal to the flow path (R 20 B) of the filling apparatus side member ( 20 B) is formed in the filling apparatus side member ( 20 B), the extension portion ( 24 B) with the space ( 243 B) in which the opening portion ( 220 ) is extended in the opposite direction of the nozzle side member ( 10 B) is provided, in the flow path of the filling apparatus side member ( 20 B), a support member ( 60 ) that supports the valve body ( 30 ) of the shutoff valve on the filling apparatus side ( 20 B) so as to be separated from the valve seat (V 20 ) when the nozzle side member ( 10 B) is connected to the filling apparatus side member ( 20 B), and the elastic body (socket side spring  40 ) that presses the valve body ( 30 ) toward the opening portion ( 220 ) side are provided, the opening portion closing member ( 8 B) slidable in the space ( 243 B) of the extension portion ( 20 B) and the opening portion ( 220 ) of the filling apparatus side member ( 20 B), and the elastic member ( 9 B) urging the opening portion closing member ( 8 B) in the direction that the nozzle side member ( 10 B) is disconnected are provided, and the depressurizing mechanism for reducing the pressure at the opening portion ( 220 ) of the filling apparatus side member ( 20 B) is provided. With this, according to the present invention, when the nozzle side member ( 10 B) and the filling apparatus side member ( 20 B) are connected, the support member ( 60 ) supports the shutoff valve ( 30 ) of the filling apparatus side member ( 20 B) in open state, which allows the hydrogen supplied from the filling apparatus to be filled in a tank in a fuel cell vehicle with a hydrogen filling nozzle through the hydrogen supply port ( 25 ) of the filling apparatus side member ( 20 B), the flow path (R 20 B) of the filling apparatus side member ( 20 B), the through hole ( 12 T) formed in the protruding portion ( 12 ) of the nozzle side member ( 10 B), the flow path (R 10 B) of the nozzle side member ( 10 B), and the hydrogen outlet ( 5 ) of the nozzle side member ( 10 B). 
     In the third invention, when the nozzle side member ( 10 B) is ejected from the filling apparatus side member ( 20 B), at the initial stage of the ejection, since the position of the through hole ( 12 T) formed on the protruding portion ( 12 ) of the nozzle side member ( 10 B) does not match the position of the flow path of the filling apparatus side member ( 20 B), the protruding portion ( 12 ) of the nozzle side member ( 10 B) closes the flow path (R 20 B) of the filling apparatus side member ( 20 B). At that time, even if gas leaks from the boundary between the protrusion ( 12 ) of the nozzle side member ( 10 B) and the opening portion ( 220 ) of the filling apparatus side member ( 20 B), the decompression mechanism causes the gas to be discharged outside of the safety joint ( 100 B), which prevents the danger associated with the high pressure of the leaked gas. Then, when the protruding portion ( 12 ) of the nozzle side member ( 10 B) comes off from the filling apparatus side member ( 20 B), the support member ( 60 ) moves to the opening portion ( 220 ) side due to the elastic repulsive force of the elastic body (socket side spring  40 ) pressing the valve body ( 30 ) toward the opening portion ( 220 ) side, and the shutoff valve (V 20 ) of the filling apparatus side member ( 20 B) is immediately closed from the open state. Therefore, the hydrogen gas from the filling apparatus side ( 20 B) is completely shut off by the shutoff valve (V 20 ) of the filling apparatus side member ( 20 B). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory cross-sectional view showing a safety joint according to the first embodiment of the present invention in a state where a protruding portion of a nozzle side member (plug) is connected to a filling apparatus side member (socket). 
         FIG. 2  is an explanatory cross-sectional view showing a state in which the protruding portion of the nozzle side member is disconnected from the filling apparatus side member in the first embodiment. 
         FIG. 3  is an explanatory cross-sectional view showing a safety joint according to the second embodiment of the present invention in a state where a protruding portion of a nozzle side member is connected to a filling apparatus side member. 
         FIG. 4  is an explanatory cross-sectional view showing a state in which the protruding portion of the nozzle side member is disconnected from the filling apparatus side member in the second embodiment. 
         FIG. 5  is an explanatory cross-sectional view showing a safety joint according to the third embodiment of the present invention in a state where a protruding portion of a nozzle side member is connected to a filling apparatus side member. 
         FIG. 6  is an explanatory cross-sectional view showing a state in which the protruding portion of the nozzle side member is being disengaged from the filling apparatus side member in the third embodiment. 
         FIG. 7  is an explanatory cross-sectional view showing a state in which the protruding portion of the nozzle side member is disconnected from the filling apparatus side member in the third embodiment. 
         FIG. 8  is a block diagram showing an outline of a hydrogen filling facility. 
         FIG. 9  is a cross sectional view showing an initial stage of the process that a plug is pulled out from a socket in a prior art. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. First, the first embodiment will be described with reference to  FIGS. 1 and 2 . In  FIG. 1 , the safety joint of the first embodiment, entirely indicated by a reference numeral  100 , includes a nozzle side member (plug)  10  and a filling apparatus side member (socket)  20 . 
     The plug  10  has a plug body  11  and a plug protruding portion  12  integrally formed with the plug body  11 . The plug body  11  is, for example, a columnar shape, and a constricted portion  11   d  having a small diameter is formed in a roughly central portion thereof. For example, the plug protruding portion  12  is formed in a columnar shape with a diameter smaller than that of the plug body  11 , and the end portion on the side separated from the plug body  11  (left side in  FIGS. 1 and 2 ) is chamfered. 
     A second flow path  14  is formed in the plug body  11 , the end portion of the second flow path  14  separated from the socket (right side in  FIGS. 1 and 2 ) is open, an attachment  5  constituting a gas outlet is screwed into the opening portion. A first flow path  15  with an inner diameter smaller than that of the second flow path  14  is formed in a central portion of the plug protruding portion  12 , the first flow path  15  and the second flow path  14  are connected through a tapered portion (no reference numeral), a plug side shutoff valve V 10  is configured by the tapered portion that is the connection point between the first flow path  15  and the second flow path  14  and a tapered portion  3   t  of a plug side valve body  3 . 
     The plug side valve body  3  with the tapered portion  3   t  processed at the left end is housed in the second flow path  14 , and a coil spring  4  for urging the plug side valve body  3  to the socket side (left side in  FIGS. 1 and 2 ) is accommodated between the plug side valve body  3  and the attachment  5 . A through hole  16  orthogonal to the first flow path  15  is formed in the vicinity of the tip (left end) of the first flow path  15 , and steel balls  6  (bearing balls: 2 pieces in  FIGS. 1 and 2 ) are inserted in the through hole  16 . A second through hole  12 T is formed in the region on the plug body  11  side (the region on the right side in  FIGS. 1 and 2 ) with respect to the through hole  16 . In the state of  FIG. 1 , the second through hole  12 T is aligned with the extension of the center line of a flow path R 20  of the socket  20 . 
     In  FIG. 1 , a piston  2  is housed in the first flow path  15 , the piston  2  has a disk member  2   a  and a rod-shaped member  2   b , and the disk member  2   a  is provided at the end of the rod-shaped member  2   b  on the side separated from the plug body  11  (left side in  FIG. 1 ). The outer diameter of the disk member  2   a  is set such that the disk member  2   a  reliably presses the balls  6  in  FIG. 1  and slides smoothly in the first flow path  15  without play. 
     Here, in the state shown in  FIG. 1 , the plug side valve body  3  is urged to the left side in  FIG. 1  by the coil spring  4 , and the piston  2  in contact with the left end surface of the plug side valve body  3  is also urged to the left side. As a result, the disk member  2   a  of the piston  2  contacts with the balls  6  and cannot move to the region on the side (left side in  FIG. 1 ) of the balls  6  separated from the body  11  on the plug side. In other words, the disk member  2   a  of the piston  2  cannot move, by the balls  6 , in a direction (left side) that the spring  4  extends. 
     The socket  20  has a socket body  22  and an extension portion  24  of the socket body  22 . In the socket body  22 , in the lower region (the region on the side where the plug protruding portion  12  is inserted) in  FIG. 1 , is formed an opening portion  220  (through hole) in the left-right direction (horizontal direction) in  FIG. 1 . Then, the in-socket flow path R 20  extending in the vertical direction of the socket body  22  in  FIG. 1  is formed, and an opening portion is formed at an end of the in-socket flow path R 20  on the side separated from the plug protruding portion  12  (upper side in  FIG. 1 ). The in-socket flow path R 20  has a first flow path  222  in the upper region (the region on the opening portion side) in  FIG. 1  and a second flow path  223  that is continued to the first flow path  222  via a tapered portion and has an inner diameter smaller than that of the first flow path  222 . Unlike the above-mentioned prior art (Patent Document 1) and the second and third embodiments described later, the in-socket flow path R 20  in the socket  20  of the first embodiment is not provided with a valve body. 
     Immediately below the second flow path  223  (on the plug protruding portion  12  side) of the through hole  220 , a cylindrical space  224  that is concentric with the through hole  220  and has an inner diameter larger than that of the through hole  220  is formed. In other words, the cylindrical space  224  communicating with the second flow path  223  is orthogonal to the second flow path  223 . An attachment  25  constituting a gas inflow port is screwed into the opening portion at the upper end of the in-socket flow path R 20 . O-rings  7  are provided in the left and right regions of the in-socket flow path R 20  in the through hole  220 . 
     The extension portion  24  provided on the side of the socket body  22  separated from the plug  10  (left side in the drawing) has a cylindrical portion  241  and a flange  242 , and is connected to a socket body  221  with the flange  242 . A cylindrical space  243  and a spring accommodating hole  244  are formed in the cylindrical portion  241 , the cylindrical space  243  has an opening portion on the flange  242  side (left side in the figure) and has a function of sliding a closing member  8  in the cylindrical space  243 , and the spring accommodating hole  244  communicates with the cylindrical space  243  and has an inner diameter smaller than that of the cylindrical space  243 . A spring  9  is accommodated in the spring accommodating hole  244 , and the spring  9  urges the closing member  8  to the plug  10  side (right side in the figure). 
     The closing member  8  has a function of smoothly sliding in the cylindrical space  243 , and has a columnar portion  81  and a flange portion  82  with a larger outer diameter than the columnar portion  81 . The plug  10  side (right side in the drawing) of the cylindrical portion  81  is inserted into the through hole  220  formed in the socket body  22 , and slides in the through hole  220 . 
     The socket  20  is provided with a closing member holding mechanism  31  (lever), and the lever  31  has a function of holding the closing member  8  at a position separated from the plug  10  when the plug  10  and the socket  20  are connected (in the case of  FIG. 1 ). The lever  31  is rotatable around a hinge pin  32  provided in the cylindrical portion  241  of the socket  20 , and is formed in a substantially “dogleg” shape. 
     On the other hand, a retention release rod  13  is provided on the plug body  11 , and the retention release rod  13  is attached in the vicinity of the plug protruding portion  12  and extends in the longitudinal direction of the plug protruding portion  12  in a direction away from the plug body  11 . A rod tip  13 L of the retention release rod  13  is bent in an L shape, and the tip faces the lever  31  side (upper side of  FIG. 1 ). The inner side of an end  31   b  of the lever  31  (the left side in  FIG. 1 ) is engaged with the inner side of the rod tip  13 L (the right side in  FIG. 1 ). Then, in the state of  FIG. 1 , the other end  31   a  of the lever  31  is engaged with the surface of the flange portion  82  of the closing member  8  on the plug  10  side (the surface on the right side in  FIG. 1 ). Engaging the flange portion  82  of the closing member  8 , the lever  31 , and the retention release rod  13  as described above maintains the connection between the plug  10  and the socket  20 . 
     The flow of hydrogen gas in the state shown in  FIG. 1  (the state in which the plug  10  is connected to the socket  20 ) will be described with reference to  FIG. 1 . At the time of hydrogen filling, the hydrogen gas supplied from the hydrogen filling apparatus  200  (see  FIG. 8 ) via the attachment  25  side (hydrogen inflow port) passes, as indicated with the arrow F 1 , through the in-socket flow path R 20  of the socket body  22  and flows into the first flow path  15  formed in the plug protruding portion  12  via the second through hole  12 T. Here, since the O-rings  7  are provided on the left and right sides of the in-socket flow path R 20  in the through hole  220 , hydrogen is prevented from leaking from the boundary portion between the plug protruding portion  12  and the through hole  220 . As described above, in the state of  FIG. 1 , the disk member  2   a  in the piston  2  of the plug  10  cannot be moved by the balls  6  in the extension direction (left side) of the spring  4 , and the plug side shutoff valve V 10  keeps open state shown in  FIG. 1 . As a result, as shown with the arrow F 2 , the hydrogen gas that has flowed into the first flow path  15  of the plug protruding portion  12  flows in the filling hose  201  (see  FIG. 8 ) via the plug side shutoff valve V 10 , the flow path  14  of the plug  10 , and a flow path  5   i  (gas outlet) of the attachment  5 . The reference numeral R 10  in  FIG. 1  indicates an in-plug flow path. 
     Next, the case where the plug  10  is disconnected from the socket  20  will be described with reference to  FIG. 2  also. In the state shown in  FIG. 1 , when the plug  10  is disengaged from the socket  20 , the tip  13 L of the retention release rod  13  provided on the plug  10  moves in the direction that the plug  10  is disengaged (right side of  FIGS. 1 and 2 ). In  FIG. 1 , when the tip  13 L of the retention release rod  13  moves to the right side of  FIG. 2 , the lever  31  on the socket  20  side rotates counterclockwise, and the engagement between the flange portion  82  of the closing member  8  and the lever  31  is released. When the engagement between the flange portion  82  and the lever  31  is released, as shown in  FIG. 2 , the closing member  8  that has been in contact with the tip of the plug protruding portion  12  is urged by the coil spring  9  to move to the plug  10  side (to the right side in  FIG. 2 ), and is in the condition shown in  FIG. 2 . Moving the closing member  8  to the plug  10  side (to the right side in  FIG. 2 ) causes the closing member  8  to be located near the in-socket flow path R 20  of the through hole  220  as shown in  FIG. 2  to close the socket inner flow path R 20  and block the flows of hydrogen gas indicated with the arrows F 1  and F 2  in  FIG. 1 . 
     When the plug  10  is disengaged from the socket  20 , the plug protruding portion  12  moves from the state of  FIG. 1  in the direction that the plug is disengaged (right side in  FIGS. 1 and 2 ), and the balls  6  reach the cylindrical space  224 . An elastic repulsive force due to the extension of the spring  4  acts on the balls  6 , and the elastic repulsive force causes the balls  6  to constantly try to move outward in the radial direction of the plug protruding portion  12 . With this, the ball that has reached the cylindrical space  224  moves outward in the radial direction of the plug protruding portion  12  and enters the cylindrical space  224 , and the state in which the disk member  2   a  of the piston  2  is in contact with the balls  6  is released. Then, the disk member  2   a  of the piston  2  moves beyond the balls  6  in the extension direction of the spring  4  (left side in  FIGS. 1 and 2 ). As a result, due to the elastic repulsive force of the spring  4 , the plug side valve body  3  sits on the tapered portion (valve seat) which is the connection point of the second flow path  14 , and as shown in  FIG. 2 , the plug side valve body V 10  is closed, which prevents high-pressure hydrogen gas from flowing out of the plug  10  side. 
     According to the first embodiment shown in  FIGS. 1 and 2 , when the plug  10  is disengaged from the socket  20  due to an abnormal start of a vehicle or the like, the retention release rod  13  provided on the plug  10  goes to the right; the lever  31  on the socket  20  side engaged with the tip  13 L of the retention release rod  13  rotates counterclockwise; the engagement between the closing member  8  and the lever  31  is disengaged, and the spring  9  urges the closing member  8   d  so as to instantly rush into the through hole  220 , so that it is possible to block the in-socket flow path R 20  and downstream of the flow path R 20 . Further, since the O-rings  7  are provided in the left and right regions of the in-socket flow path R 20  in the through hole  220 , the flow of hydrogen gas at the boundary between the closing member  8  and the inner wall surface of the through hole  220  is also sealed. With this, the leakage of a gas such as hydrogen gas (including out gas) can be prevented. In addition, the safety joint  100  of the first embodiment has the relatively small number of constituent members (the number of parts), and their shapes are also based on a column or a cylindrical space, so that machining for the parts is extremely easy, which provides an inexpensive safety joint. 
     Next, the second embodiment will be described with reference to  FIGS. 3 and 4 . In  FIG. 3 , in a safety joint  100 A according to the second embodiment, a socket side valve body  30  and a coil spring  40  are arranged inside the first flow path  222  of the socket body  22  in a socket  20 A, and the coil spring  40  is arranged between the socket side valve body  30  and the internal side end portion of the attachment  25 . A support member  60  is arranged in the second flow path  223  below the socket side valve body  30 , and a tip of the support member  60  (the tip on the valve body side: the upper end in  FIG. 3 ) has a triangular pyramid shape and is an entirely cylindrical hollow member with an open bottom. The valve seat of the socket side shutoff valve V 20  is composed of a tapered portion which is a connecting portion between the first flow path  222  and the second flow path  223 . In the safety joint  100 A according to the second embodiment shown in  FIGS. 3 and 4 , the same members as those of the first embodiment shown in  FIGS. 1 and 2  are designated by the same reference numerals. 
     A plurality of small holes  60   a  are provided in the triangular pyramid portion of the support member  60 , and the small holes  60   a  form a part of the gas flow path. In the state where the plug  10  is connected to the socket  20 A, the open lower end of the support member  60  is in contact with the outer peripheral surface of the plug protruding portion  12 , and the socket side valve body  30  is in contact with the upper end of the support member  60 . As a result, in  FIG. 1 , the socket side valve body  30  is separated from the valve seat (the tapered portion connecting the first flow path  222  and the second flow path  223 ) by the support member  60 , and the shutoff valve V 20  is maintained in an open state. The plug  10  side is the same as that of the first embodiment of  FIGS. 1 and 2 . In  FIG. 3 , the reference numeral R 10 A indicates a flow path in the plug. 
     In the second embodiment of  FIGS. 3 and 4 , as in the first embodiment, the socket  20 A is provided with the closing member holding mechanism  31  (lever), and the plug body  11  is provided with the retention release rod  13 . However, the closing member  8 A in the second embodiment shown in  FIGS. 3 and 4  is different from the closing member of the first embodiment. The closing member  8 A has a rod-shaped member  81 A and a disk portion  82 A. The rod-shaped member  81 A extends in the through hole  220 , and the disk portion  82 A is urged to the plug  10 A side (right side in the figure) with the spring  9 . The spring  9  is housed in the spring housing hole  244  of the extension portion  24 . In the state shown in  FIG. 3  (the state in which the plug  10 A is connected to the socket  20 A), the rod tip  13 L of the retention release rod  13  is engaged with an end  31   b  of the lever  31 , and the other end  31   a  of the lever  31  is engaged with the disc portion  82 A of the closing member  8 . Similar to  FIG. 1 , the connection between the plug  10 A and the socket  20 A is maintained by engaging the lever  31 , the retention release rod  13 , and the disc portion  82 A of the closing member  8 . 
     A mode of filling the filling gas will be described with reference to  FIG. 3 . Hydrogen gas flowing from the attachment  25  (gas inlet) into the in-socket flow path R 20 A of the socket body  22  passes through the socket side shutoff valve V 20  in open state and passes through the flow path R 20 A as shown by the arrow Fa 1 . Then, it flows into the first flow path  15  formed in the plug protruding portion  12  via the second through hole  12 T formed in the plug protruding portion  12 . In the in-socket flow path R 20 A, the gas that has passed through the first flow path  222  passes through the plurality of small holes  60   a  formed on the triangular pyramid portion of the support member  60  and the internal space of the support member  60 . 
     Next, a case where the plug  10 A is disconnected from the socket  20 A will be described with reference to  FIGS. 3 and 4 . In  FIG. 4 , when the plug  10 A is disengaged from the socket  20 A (moves to the right side in  FIG. 4 ), the tip  13 L of the retention release rod  13  provided on the plug  10 A also moves to the plug side (right side in  FIG. 4 ); the lever  31  on the socket  20 A side engaged with the retention release rod  13  rotates counterclockwise; the engagement between the closing member  8 A and the lever  31  is released; and the closing member  8 A moves to the plug  10 A side (right side in  FIG. 4 ) due to the elastic repulsive force of the coil spring  9 . Then, the disk portion  82 A of the closing member  8 A urged by the coil spring  9  closes the opening portion at the end of the extension portion  24  (left side in  FIG. 4 ) of the through hole  220 . Here, since the rod-shaped member  81 A of the closing member  8 A has a smaller diameter than that of the plug protruding portion  12 , the supporting member  60  supported by the plug protruding portion  12  is pressed toward the inside of the through hole  220  (lower in the drawing) due to the elastic repulsive force of the socket side spring  40 . At the same time, the socket side valve body  30  is also pressed toward the through hole  220  side (lower in the drawing) due to the elastic repulsive force of the socket side spring  40 , and sits on the valve seat to close the socket side shutoff valve V 20 . Other configurations and effects in the second embodiment shown in  FIGS. 3 and 4  are the same as those of the first embodiment shown in  FIGS. 1 and 2 . 
     Next, the third embodiment of the present invention will be described with reference to  FIGS. 5 to 7 . The safety joint according to the third embodiment is entirely indicated by a reference numeral  100 B. The safety joint according to the third embodiment does not include the retention release rod  13  and the lever  31  in the first and second embodiments shown in  FIGS. 1 to 4 , and does not include the closing members  8  and  8 A. In the third embodiment, the extension portion  24 B of the socket  20 B and its internal configuration are different from those of the first embodiment and the second embodiment shown in  FIGS. 1 to 4 . 
     In  FIG. 5 , which shows a state in which the plug  10 B is connected to the socket  20 B, the extension portion  24 B of the socket  20 B has a cylindrical shape with a step portion. The extension portion  24 B forms a cylindrical space  243 B in which the plug  10 B side (right side in  FIG. 5 ) is open. A slider  8 B is housed in the cylindrical space  243 B, and slides therein. In the illustrated example, the inner diameter of the cylindrical space  243 B is equal to that of the through hole  220  formed in the socket body  22 . 
     On the side of the cylindrical space  243 B separated from the flange  242 B side (left side in  FIG. 5 ), a space  244 B (chamber) having an inner diameter larger than that of the cylindrical space  243 B is formed adjacent to the cylindrical space  243 B. An exhaust port  246  is formed on the chamber  244 B side end surface (left end surface in  FIG. 5 ) of the extension portion  24 B. The slider  8 B has a cylindrical shape in which the plug  10 B side (right side in  FIG. 5 ) is closed and the end side on the side where the exhaust port  246  is formed (left side in  FIG. 5 ) is open. A coil spring  9 B is interposed in the internal space  83  of the slider  8 B. A small exhaust hole  84  is formed in the vicinity of the open side end of the slider  8 B. Although not explicitly shown in the figure, the exhaust port  246  can communicate with a pressure valve (not shown). 
     An O-ring groove (reference numeral is omitted) is formed in the vicinity of the step portion of the cylindrical space  243 B with the chamber  244 B, and an O-ring  70  is interposed inside the O-ring groove. Further, a small hole  245  for pressure release is formed in a substantially central portion of the cylindrical space  243 B, and the small hole  84  for pressure release is formed in the slider  8 B also. As will be described later, during hydrogen gas filling, hydrogen gas (filled gas) leaks from the boundary between the through hole  220  and the plug protruding portion  12 , and the internal pressure of the cylindrical space  243 B increases. The pressure in the cylindrical space  243 B acts in a direction that separates the plug  10 B from the socket  20 B. Therefore, a small exhaust hole  84  and the exhaust port  246  are formed to prevent the plug  10 B from being separated from the socket  20 B due to the pressure increase in the cylindrical space  243 B in normal use. The small hole  245  for pressure relief is also formed for the same purpose. 
     The third embodiment shown in  FIGS. 5 and 6  is substantially the same as the second embodiment shown in  FIGS. 3 and 4  except for the configuration of the extension portion  24 B and the absence of the retention release rod  13 , the lever  31  and the closing member  8 A. Therefore, in the third embodiment, the mode of filling the filling gas and the hydrogen gas flow path indicated by the arrows Fb 1  and Fa 2  are substantially the same as those of the second embodiment shown in  FIGS. 3 and 4 . Further, in the third embodiment, the mode when the plug  10 B is disconnected from the socket  20 B, the plug side shutoff valve V 10  and the socket side shutoff valve V 20  are closed is substantially the same as the second embodiment of  FIGS. 3 and 4 . 
     In  FIG. 5 , hydrogen gas (filled gas) leaks from the boundary between the through hole  220  and the plug protruding portion  12  during hydrogen gas filling, and the leaked filling gas Gf flows into the cylindrical space  243 B of the extension portion  24 B to increase the internal pressure of the cylindrical space  243 B. When the internal pressure of the cylindrical space  243 B increases, the slider  8 B moves to the spring  9  side (left side in  FIG. 5 ) to compress the spring  9  and increase the volume of the cylindrical space  243 B. Further, when the cylindrical space  243 B is boosted and the end surface on the opening portion side of the slider  8 B comes into contact with the inner surface on the side separated from the plug  10 B of the chamber  244 B (left side in  FIG. 5 ), the volume of the cylindrical space  243 B does not increase any more. 
     The boosted hydrogen gas in the cylindrical space  243 B can be released to the outside of the safety joint  100 B from the small hole  245  for pressure release (the arrow Fbx in  FIG. 6 ). 
       FIG. 6  shows a state in which the tip end portion of the plug protruding portion  12  is still located in the through hole  220  of the socket  20 B in the process of disconnecting the plug  10 B from the socket  20 B. In  FIG. 6 , the tip of the plug protruding portion  12  in the plug  10 B remains in the through hole  220  of the socket  20 B, but the position of the plug protruding portion  12  is a position that does not hinder the lowering of the support member  60  even if it is pressed downward due to the elastic repulsive force of the socket side spring  40 . That is, the right opening portion of the through hole  220  is closed by the plug protruding portion  12 . Since the plug protruding portion  12  that has prevented the support member  60  from descending due to the elastic repulsive force of the socket side spring  40  is moving in the state of  FIG. 6 , the support member  60  interposed in the second flow path  223  of the socket  20 B is instantaneously lowered by the elastic repulsive force of the socket side spring  40 . As a result, the socket side shutoff valve V 20  is closed and the flow of the filling gas is also shut off. The hydrogen gas existing on the downstream side (through hole  220 ) of the socket side valve body  30  when the socket side shutoff valve V 20  is closed flows out as shown by the arrow Fbi shown by the dotted line in  FIG. 6  and flows into the cylindrical space  243 B to increase the internal pressure of the cylindrical space  243 B. However, as described above, the internal pressure of the cylindrical space  243 B can be reduced by releasing the gas from the small hole  245  for releasing the pressure of the cylindrical space  243 B. 
     In  FIG. 7 , which shows a state in which the plug  10 B is completely disconnected from the socket  20 A, the right opening portion of the through hole  220  of the socket  20 B is opened because (the plug protruding portion  12  of) the plug  10 B is completely disconnected from the socket  20 B. The internal pressure of the cylindrical space  243 B is also lowered accordingly, and due to the elastic repulsive force of the spring  9 B, the slider  8 B moves on the side where the plug  10 B is pulled out (right side in  FIG. 7 ) from the state shown in  FIG. 6  such that the spring  9 B becomes in an extended state. Since the exhaust port  246  is formed on the left end side end surface of the extension portion  24 B, even if the slider  8 B moves to the right side in  FIG. 7 , outside air does not flow in from the exhaust port  246  and the inside of the chamber  244 B does not become negative pressure. 
     In the third embodiment shown in  FIGS. 5 to 7 , the mode in which the plug side shutoff valve V 10  is open when the plug  10 B is not disconnected from the socket  20  and the mode in which the plug side shutoff valve V 10  is closed when the plug  10 B is disconnected from the socket  20  are the same as the modes described in the first embodiment shown in  FIGS. 1 and 2 . Other configurations and effects in the third embodiment shown in  FIGS. 5 to 7  are the same as those of the second embodiment shown in  FIGS. 3 and 4 . 
     Since the embodiments shown in the drawings are merely examples, and the embodiments do not limit the technical scope of the present invention. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
           2  piston 
           3  plug side valve body 
           4  coil spring 
           8  closing member 
           10  plug 
           12  plug side protruding portion 
           13  retention release rod 
           14  second flow path 
           15  first flow path 
           20  socket 
           24  extension portion 
           30  socket side valve body 
           40  coil spring 
           60  supporting member 
           100  safety joint