Patent Publication Number: US-2023144687-A1

Title: Male joint and pipe joint

Description:
TECHNICAL FIELD 
     The present invention relates to a male joint and a pipe joint. 
     BACKGROUND ART 
     Conventionally, as a pipe joint between hoses for transferring a fluid such as water or oil under high pressure, a quick pipe joint using a valve element is known (for example, PTL 1). 
     PTL 1 discloses a valve element including a valve tip end side member, a valve rear end side member, and a seal member, in which the seal member is fitted in a groove formed by the valve tip end side member and the valve rear end side member. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: JP 2018-25277 A 
       
    
     SUMMARY OF THE INVENTION 
     Technical Problem 
     In the case of PTL 1, since the groove for fitting the seal member is formed by the valve tip end side member and the valve rear end side member, there is a concern that such structure is complicated and versatility is low. 
     An object of the present invention is to provide a male joint and a pipe joint with a simpler structure. 
     Solution to Problem 
     A male joint according to the present invention includes a male joint main body having a cylindrical shape and a valve element provided coaxially with a central axis of the male joint main body in the male joint main body, wherein the valve element includes a shaft portion having a shaft shape and a valve portion having a disk shape coaxially provided at a tip end of the shaft portion; the valve portion includes a base end portion to which the tip end of the shaft portion is connected, a tip end portion opposite to the base end portion, and a side portion between the base end portion and the tip end portion; the base end portion includes a first surface intersecting with the central axis and a second surface connected to an outer edge of the first surface and extending from the first surface to the base end along the central axis; the side portion includes an annular groove centered on the central axis and a deformation portion on a base end side of the groove; the groove includes a bottom surface along the central axis and a pair of inner surfaces extending radially outward from both end portions of the bottom surface in the central axis direction; and the deformation portion includes a thin portion in which a thickness between, a connection portion between the first surface and the second surface, and a connection portion between an inner surface on a base end side of the pair of inner surfaces and the bottom surface is partially thin. 
     A pipe joint according to the present invention includes the male joint and a female joint into which the male joint is inserted. 
     Advantageous Effects of the Invention 
     According to the present invention, since the groove for mounting an O-ring is formed of a single valve portion, it is possible to provide a male joint and a pipe joint with a simpler structure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    A partial cross-sectional view of a pipe joint according to the present embodiment. 
         FIG.  2    A partial cross-sectional view of a male joint. 
         FIG.  3    A partial cross-sectional view of a valve element. 
         FIG.  4    A right side view of the valve element. 
         FIG.  5    A partially enlarged cross-sectional view of the male joint. 
         FIG.  6 A  A partially enlarged cross-sectional view of the valve element before caulking. 
         FIG.  6 B  A partially enlarged cross-sectional view in a state where the O-ring is mounted to the valve element. 
         FIG.  6 C  A partially enlarged cross-sectional view of the valve element after caulking of the valve element. 
         FIG.  7    A partial cross-sectional view of a female joint. 
         FIG.  8    A partially enlarged cross-sectional view of the valve element according to a modification. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, unless otherwise specified, a direction parallel to the central axis is simply referred to as an “axial direction”, a radial direction centered on the central axis is simply referred to as a “radial direction”, and a circumferential direction centered on the central axis, that is, around the central axis is simply referred to as a “circumferential direction”. In addition, in the present description, a “parallel direction” also includes a substantially parallel direction, and an “orthogonal direction” also includes a substantially orthogonal direction. 
     A pipe joint  10  shown in  FIG.  1    is a quick pipe joint including a male joint  12  and a female joint  14  into which the male joint  12  is inserted. Although not illustrated, the male joint  12  and the female joint  14  are connected to different pipes. The male joint  12  has a flow path  15 . The female joint  14  has a flow path  17 . The pipe joint  10  connects the male joint  12  and the female joint  14  to connect the flow path  15  and the flow path  17 . 
     (Male Joint) 
     As illustrated in  FIG.  2   , the male joint  12  includes a male joint main body  16 , a valve element  20 , a first cap  22 , a holder  32 , and a coil spring  34 , all of which are made of metal. In the male joint  12 , a first orifice  18  provided at the tip end in the axial direction can be opened and closed by the valve element  20 , and the first cap  22  is provided at the base end in the axial direction. 
     The male joint main body  16  is a cylindrical member, has the first orifice  18  at the tip end, has an outer peripheral seal surface  24  and an annular concave portion  26  on an outer periphery, and has a female screw formed on an inner peripheral surface at a base end. The outer peripheral seal surface  24  is enlarged in diameter from the tip end of the male joint main body  16  and has a smooth shape continuous in the circumferential direction. The annular concave portion  26  is on the base end side of the outer peripheral seal surface  24 , and has a concave shape with a reduced diameter and continuous in the circumferential direction. The male joint main body  16  has a tapered shape on the tip end side from the outer peripheral seal surface  24 . 
     The inner peripheral surface of the male joint main body  16  has a tapered shape toward the tip end, and has a first annular protrusion  60  at the tip end and a first seal surface  62  on the base end side of the first annular protrusion  60 . The first annular protrusion  60  annularly protrudes inward from the tip end of the male joint main body  16  toward a central axis A. The first seal surface  62  is inclined toward the central axis A toward the tip end. The first cap  22  is a cylindrical member, a male screw complementary to the female screw of the male joint main body  16  is formed on an outer peripheral surface, and is screwed into the above female screw to be fixed to the base end of the male joint main body  16 . 
     The holder  32  includes a disk-shaped bottom portion  31  having a tip end surface and a base end surface, and a shaft-shaped support portion  33  whose longitudinal direction is an axial direction and a base end of which is connected to a center of the tip end surface. A support hole  29  penetrating in the axial direction from the center of the tip end of the support portion  33  to the base end surface is formed. A plurality of holes (not illustrated) penetrating in the axial direction are formed around a connection portion between the bottom portion  31  and the support portion  33 . The base end surface of the bottom portion  31  is in contact with the tip end of the first cap  22  fixed to the male joint main body  16 . The support portion  33  is inserted into the base end of the coil spring  34 . The coil spring  34  is arranged to be able to expand and contract in the axial direction. The base end of the coil spring  34  is in contact with the tip end surface of the bottom portion  31 . 
     (Valve Element) 
     The valve element  20  includes a shaft portion  28  having a shaft shape whose longitudinal direction is the axial direction, and a valve portion  30  integrally formed at a tip end of the shaft portion  28 . A base end of the shaft portion  28  is inserted into the support hole  29  of the holder  32 . The shaft portion  28  is supported by the support portion  33  in such a way that it can move in the axial direction. 
     The valve portion  30  has a disk shape and is arranged coaxially with the shaft portion  28 . As illustrated in  FIG.  3   , the valve portion  30  includes a base end portion  36  to which the tip end of the shaft portion  28  is connected, a tip end portion  38  opposite to the base end portion  36 , and a side portion  40 , facing radially outward, between the base end portion  36  and the tip end portion  38 . 
     The base end portion  36  has a first surface  42  extending radially outward from the central axis A, a second surface  44  connected to the outer edge of the first surface  42  and extending from the outer edge of the first surface  42  toward the base end along the central axis A, and a third surface  45  extending from an inner edge of the first surface  42  toward the base end along the central axis A. The first surface  42  is an annular surface centered on the shaft portion  28 . The second surface  44  and the third surface  45  face each other in the radial direction. The second surface  44  has a cylindrical inner surface shape, in which the front end in the axial direction is connected to the outer edge of the first surface  42 , and a rear end in the axial direction extends to a base end along the central axis A. The third surface  45  has a cylindrical outer surface shape, in which the front end in the axial direction is connected to the inner edge of the first surface  42 , and a rear end in the axial direction is connected to the shaft portion  28 . 
     The inner edge of the first surface  42  is connected to the front end of the third surface  45 , and the outer edge of the first surface  42  is connected to the front end of the second surface  44 . A connection portion  47  between the outer edge of the first surface  42  and the front end of the second surface  44  is an R-shaped concave surface. 
     As illustrated in  FIG.  4   , the first surface  42  includes an annular first region  41  centered on the shaft portion  28 , and an annular second region  43 , on the radially outer side, that is concentric with the first region  41 . The inner edge of the first region  41  is connected to the front end of the third surface  45 , and the outer edge of the first region  41  is connected to the inner edge of the second region  43 . The inner edge of the second region  43  is connected to the outer edge of the first region  41 , and the outer edge of the second region  43  is connected to the front end of the second surface  44 . The base end portion  36  has the second region  43  wider than the first region  41  on the radially outer side of the first region  41 . In a case where an outer diameter of the second region  43  is R 1 , an inner diameter of the second region  43  and an outer diameter of the first region  41  are R 2 , and an inner diameter of the first region  41  is R 3 , the difference between the outer diameter R 1  and the inner diameter R 2  of the second region  43  is larger than the difference between the outer diameter R 2  and the inner diameter R 3  of the first region  41 . 
     The third surface  45  has an outer diameter similar to or smaller than the outer diameter of the support portion  33  of the holder  32 , and is inserted into the tip end of the coil spring  34 . The outer diameter of the third surface  45  is the same as the inner diameter R 3  of the first region  41 . The tip end of the coil spring  34  is in contact with the first surface  42  in the first region  41 . The coil spring  34  is arranged between the bottom portion  31  of the holder  32  and the base end portion  36  of the valve element  20  to press the valve element  20  in the tip end direction. 
     As illustrated in  FIG.  5   , the side portion  40  includes an annular groove  46  extending in the circumferential direction and a deformation portion  54  on the base end side in the axial direction of the groove  46 . The groove  46  has an opening radially outward. An O-ring  58  is mounted to the groove  46 . 
     The groove  46  has, in the cross section including the central axis A, a bottom surface  48  with a cylindrical outer surface shape along the axial direction and a pair of inner surfaces  50   a  and  50   b  extending radially outward from both end portions of the bottom surface  48  in the axial direction. A pair of outer surfaces  52   a  and  52   b  is respectively arranged on the outer side in the axial direction from the pair of inner surfaces  50   a  and  50   b . The pair of inner surfaces  50   a  and  50   b  is inclined inward in the axial direction as going radially outward. The pair of outer surfaces  52   a  and  52   b  is inclined inward in the axial direction as going radially outward. The angle with respect to the radial direction is smaller in the inner surfaces  50   a  and  50   b  than in the outer surfaces  52   a  and  52   b.    
     The pair of inner surfaces  50   a  and  50   b  intersects the bottom surface  48  at an acute angle. A connection portion  49  between the inner surface  50   a  arranged on the base end side in the axial direction in the groove  46  and the base end in the axial direction in the bottom surface  48  is an R-shaped concave surface. An axial length of the bottom surface  48  is L 1 , and an axial length between the pair of inner surfaces  50   a  and  50   b  in the opening of the groove  46  is L 2 . The length L 2  is the minimum length between the pair of inner surfaces  50   a  and  50   b . The length L 1  is longer than a wire diameter of the O-ring  58 . The wire diameter of the O-ring  58  is the thickness of the O-ring cross section. The length L 2  is shorter than the wire diameter of the O-ring  58 . A part of the O-ring  58  mounted to the groove  46  protrudes radially outward from the opening of the groove  46 . A part of the O-ring  58  may be in contact with the pair of inner surfaces  50   a  and  50   b . The O-ring  58  may be compressed by the pair of inner surfaces  50   a  and  50   b . The valve element  20  closes the first orifice  18  when the O-ring  58  comes into contact with the first seal surface  62 . 
     The outer surface  52   a  arranged on the base end side in the axial direction from the groove  46  is connected to the second surface  44  and intersects with the second surface  44  at an acute angle. R processing or chamfering processing is performed between the outer surface  52   a  and the second surface  44 . The outer surface  52   b  arranged on the tip end side in the axial direction from the groove  46  is connected to the tip end portion  38 . The outer surface  52   b  is in contact with the first annular protrusion  60 . The tip end portion  38  has a surface extending in the radial direction. 
     The deformation portion  54  is a portion deformed by caulking process to be described later. The deformation portion  54  is a portion mainly surrounded by the connection portion  49 , the inner surface  50   a , the outer surface  52   a , the second surface  44 , and the connection portion  47 . The deformation portion  54  has a thin portion  55  in which the thickness between, the connection portion  47  between the first surface  42  and the second surface  44 , and the connection portion  49  between the inner surface  50   a  and the bottom surface  48  is partially thin. The deformation portion  54  has a thick portion surrounded by the inner surface  50   a , the outer surface  52   a , and the second surface  44 . 
     A method of mounting the O-ring  58  to the valve portion  30  will be described. To start with, the valve portion  30  before the O-ring  58  is mounted will be described with reference to  FIG.  6 A . Before the O-ring  58  is mounted, the inner surface  50   a  arranged on the base end side in the axial direction in the groove  46  is formed so as to intersect the bottom surface  48  at a right angle. In other words, the inner surface  50   a  is along the radial direction, and the length L 2  is longer than the wire diameter W of the O-ring  58 . Furthermore, the inner surface  50   b  is formed in such a way that it is inclined inward in the axial direction as proceeding radially outward. Such valve portion  30  can be formed by cutting process. The length from the central axis A to the connection portion between the inner surface  50   a  and the outer surface  52   a  is formed to be equal to the length from the central axis A to the connection portion between the inner surface  50   b  and the outer surface  52   b  after the caulking process. 
     The O-ring  58  is mounted to the groove  46  having such a wide opening ( FIG.  6 B ). Since the opening is wide, the O-ring  58  can be easily mounted to the groove  46 . Next, a force is applied to the outer surface  52   a  in the tip end direction to perform caulking process. The deformation portion  54  is caulked over the entire circumferential direction until the length L 2  becomes shorter than the wire diameter W of the O-ring  58  ( FIG.  6 C ). The length L 2  may be appropriately adjusted according to a deformation amount of the deformation portion  54 . The larger the deformation amount of the deformation portion  54 , that is, the shorter the axial length L 2 , the stronger the force with which the groove  46  restrains the O-ring  58 . As described above, the O-ring  58  can be mounted to the groove  46 . 
     (Female Joint) 
     As illustrated in  FIG.  7   , the female joint  14  includes a female joint main body  66 , a distribution pipe  68  provided in the female joint main body  66 , and a sleeve  72  that moves in the axial direction between the female joint main body  66  and the distribution pipe  68  to open and close a second orifice  70 , all of which are made of metal. 
     The female joint main body  66  is a cylindrical member in which the female screw is formed on the inner peripheral surface of a base end, and includes a second cap  74  at the base end and an operation body  76  on the tip end side. The second cap  74  is a cylindrical member in which a male screw complementary to the female screw of the female joint main body  66  is formed on the outer peripheral surface, and is screwed into the female screw to be fixed to the female joint main body  66 . 
     A snap ring  78  is mounted to the outer peripheral surface of the tip end of the female joint main body  66 . The female joint main body  66  includes, on the base end side from the snap ring  78 , a through hole  82  penetrating in the radial direction and a sphere  84  accommodated in the through hole  82 . The through hole  82  has a tapered shape from the outside to the inside in the radial direction such that the sphere  84  is movable in the radial direction and does not fall off to the inside of the female joint main body  66 . A part of the sphere  84  protrudes from the through hole  82  into the female joint main body  66 . 
     The inner peripheral surface of the female joint main body  66  has a second annular protrusion  96  in the vicinity of the center in the axial direction, a first seal portion  98  on the tip end side of the second annular protrusion  96 , and a second seal portion  100  on the tip end side from the first seal portion  98 . The second annular protrusion  96  annularly protrudes inward from the inner peripheral surface of the female joint main body  66  toward the central axis A. The first seal portion  98  and the second seal portion  100  have an annular shape extending in the circumferential direction. The second seal portion  100  is in contact with the outer peripheral seal surface  24  of the male joint main body  16 . 
     The operation body  76  is a cylindrical member, is externally inserted to the tip end side of the female joint main body  66 , and is held by the female joint main body  66  when the inner surface of the tip end side comes into contact with the snap ring  78 . The operation body  76  is pressed in the tip end direction by a coil spring  80  as an elastic portion provided between the base end of the operation body  76  and the female joint main body  66 . 
     The distribution pipe  68  is a columnar member, and has the flow path  17  penetrating between the center of the base end and the second orifice  70  on the side surface on the other end side. The base end of the distribution pipe  68  is fixed to the second cap  74 . The distribution pipe  68  has a second seal surface  69  on the outer peripheral surface on the tip end side more than the second orifice  70 . 
     The sleeve  72  is a cylindrical member and has a first inner peripheral surface  86  with a cylindrical inner surface shape along the axial direction, a second inner peripheral surface  88  with a cylindrical inner surface shape provided coaxially with the first inner peripheral surface  86 , and an annular abutment surface  90 , along the radial direction, connecting a tip end of the first inner peripheral surface  86  and a base end of the second inner peripheral surface  88 . The second inner peripheral surface  88  has the inner diameter at the base end larger than the inner diameter of the first inner peripheral surface  86  and is inclined such that the inner diameter increases from the base end to the tip end. 
     A coil spring  92  as an elastic portion is provided between the sleeve  72  and the second cap  74 . The base end of the coil spring  92  is in contact with the tip end of the second cap  74 , and the tip end of the coil spring  92  is in contact with the base end of the sleeve  72 . The sleeve  72  is pressed toward the tip end side of the female joint main body  66  by the coil spring  92 . A claw  94  provided on the outer peripheral surface is in contact with the second annular protrusion  96 , so that the sleeve  72  is held in the female joint main body  66 . 
     A space between the sleeve  72  and the female joint main body  66  is sealed by the first seal portion  98 . The first seal portion  98  is always in contact with the outer peripheral surface that is the cylindrical outer surface of the sleeve  72  in the entire stroke in which the sleeve  72  moves in the axial direction. In the present embodiment, the second seal portion  100  may not be in contact with the outer peripheral surface of the sleeve  72 . Furthermore, in the present description, the seal portion is preferably a squeeze packing, and for example, an O-ring, a D-ring having a D-shaped cross section, an X-ring having an X-shaped cross section, a T-ring having a T-shaped cross section, or the like can be used. 
     A third seal portion  102  in contact with the second seal surface  69  of the distribution pipe  68  is provided on the first inner peripheral surface  86  of the sleeve  72 . When the third seal portion  102  is in contact with the second seal surface  69  of the distribution pipe  68 , the sleeve  72  closes the second orifice  70  with respect to a female opening  105 . When the sleeve  72  moves to the base end side and the third seal portion  102  separates from the second seal surface  69 , the sleeve  72  opens the second orifice  70  with respect to the female opening  105 . 
     (Operation and Effect) 
     To start with, procedures for connecting the male joint  12  and the female joint  14  will be described. Each of the first cap  22  and the second cap  74  has a female screw on the inner peripheral surface, and a tube (not illustrated) is connected thereto. 
     In the male joint  12 , the valve element  20  is at a position on the tip end side of the male joint main body  16  (hereinafter, also referred to as a starting point), and the O-ring  58  is in contact with the first seal surface  62 , so that the first orifice  18  is closed to prevent fluid leakage ( FIG.  2   ). In a state where the female joint  14  is not connected to the male joint  12 , the sleeve  72  is at a position on the tip end side of the female joint main body  66  (hereinafter, also referred to as a starting point), and the third seal portion  102  is in contact with the second seal surface  69  of the distribution pipe  68 , so that the second orifice  70  is closed with respect to the female opening  105  to prevent fluid leakage ( FIG.  7   ). 
     When the tip end of the male joint  12  is inserted into the tip end of the female joint  14  in a state where the operation body  76  is moved to the base end side, the tip end of the male joint main body  16  comes into contact with the abutment surface  90  of the sleeve  72 . When the male joint  12  is further inserted, the outer peripheral seal surface  24  pushes up the sphere  84  radially outward and enters in a state of being in contact with the second seal portion  100 , and the sleeve  72  is retracted by the male joint main body  16 . When the sleeve  72  is further retracted, the third seal portion  102  separates from the second seal surface  69 , so that the second orifice  70  opens with respect to the female opening  105 . In the female joint  14 , the first seal portion  98  is in contact with the outer peripheral surface of the sleeve  72 , and in the male joint  12 , the second seal portion  100  is in contact with the outer peripheral seal surface  24 . In this manner, the pipe joint  10  prevents fluid leakage. On the other hand, the tip end of the distribution pipe  68  comes into contact with the valve element  20 , and the valve element  20  retreats. When the O-ring  58  is separated from the first seal surface  62 , the first orifice  18  is opened. 
     The sleeve  72  stops when the rear end reaches a stop portion  67  of the distribution pipe  68 . When the sleeve  72  stops, the sphere  84  moves radially inward and enters the annular concave portion  26  partially. When the sphere  84  moves radially inward, the operation body  76  can move to the tip end side. By moving to the tip end side, the operation body  76  fixes the sphere  84  in a state of being pushed radially inward. The male joint  12  and the female joint  14  are fixed in a state of being connected by the sphere  84 . In this manner, the pipe joint  10  connects the flow path  15  and the flow path  17  by connecting the male joint  12  and the female joint  14 . The fluid supplied to the male joint  12  flows to the pipe connected to the female joint  14  via the pipe joint  10 . 
     Next, procedures for separating the male joint  12  and the female joint  14  will be described. The operation body  76  is moved to the base end side. Then, the sphere  84  can move radially outward. Next, when the male joint  12  is pulled out from the female joint  14 , the male joint  12  moves in the base end direction while pushing the sphere  84  radially outward. The sleeve  72  advances until the claw  94  comes into contact with the second annular protrusion  96  of the female joint main body  66  in a state where the abutment surface  90  is in contact with the tip end of the male joint  12 . At this time, the third seal portion  102  passes through the second orifice  70  and reaches the second seal surface  69 . In this manner, the pipe joint  10  separates the male joint  12  and the female joint  14 . In the male joint  12  separated from the female joint  14 , the first orifice  18  is closed by the valve element  20  returned to the starting point. In the female joint  14  separated from the male joint  12 , the second orifice  70  is closed with respect to the female opening  105  by the sleeve  72  returned to the starting point. 
     The groove  46  for mounting the O-ring  58  is formed in the valve portion  30 . Therefore, since the groove  46  can be formed by the single valve portion  30 , the structure of the male joint  12  can be simplified. 
     Since the deformation portion  54  has the thin portion  55  in which the thickness between, the connection portion  47  between the first surface  42  and the second surface  44 , and the connection portion  49  between the inner surface  50   a  on the base end side and the bottom surface  48 , is partially thin, the caulking process can be more easily performed. Since the deformation portion  54  has the thick portion surrounded by the inner surface  50   a , the outer surface  52   a , and the second surface  44 , it is possible to maintain a mechanical strength after the caulking process. 
     Since the groove  46  presses the O-ring  58  by being caulked, a restraining force of the O-ring  58  can be strengthened. Therefore, the valve element  20  can more reliably prevent the O-ring  58  from falling off. Since the deformation amount of the deformation portion  54  can be changed by caulking, the length L 2  can be easily adjusted. 
     Since the axial length of the bottom surface  48  is longer than the wire diameter of the O-ring  58 , that is, filling rate of the O-ring in the groove  46  does not exceed 100%, the O-ring  58  is elastically deformed. Therefore, sealability by the O-ring  58  mounted to the groove  46  can be more reliably obtained. 
     Modified Examples 
     The present invention is not limited to the above embodiment, and can be appropriately changed within the scope of the gist of the present invention. 
     In the above embodiment, the case where the inner surface  50   a  arranged on the base end side in the axial direction in the groove  46  is formed in such a way that the bottom surface  48  is intersected at a right angle before the O-ring  58  is mounted has been described, but the present invention is not limited thereto. Before the O-ring  58  is mounted, the inner surface  50   a  may be inclined inward in the axial direction of the groove  46  as proceeding radially outward with respect to the bottom surface  48 . In this case, the angle of the inner surface  50   a  with respect to the bottom surface  48  may be about the same as that of the inner surface  50   b , and the length L 2  may be shorter than the wire diameter W of the O-ring  58  within a range in which the O-ring  58  can be mounted. After the O-ring  58  is mounted to the groove  46 , a force is applied to the outer surface  52   a  in the tip end direction and further caulking process is performed, so that it is possible to form a groove in which a force for restraining the O-ring  58  is further increased with a smaller deformation amount than in the above embodiment. By reducing the deformation amount, an effect of improving dimensional accuracy of L 2  after the caulking process and an effect of suppressing wear of a jig or the like due to reduction of a caulking load are expected. 
     In the above embodiment, the case where the pair of inner surfaces  50   a  and  50   b  intersects with the bottom surface  48  at an acute angle has been described, but the present invention is not limited thereto, and only one of the pair of inner surfaces may intersect at an acute angle. For example, in the groove  110  illustrated in  FIG.  8   , the inner surface  50   b  on the tip end side in the axial direction intersects with the bottom surface  48  at a right angle. In other words, the inner surface  50   b  is along the radial direction. On the other hand, the inner surface  50   a  on the base end side in the axial direction intersects with the bottom surface  48  at an acute angle. The axial length of the bottom surface  48  is longer than the wire diameter of the O-ring  58 , and the axial length between the pair of inner surfaces in the opening provided between the tip ends of the pair of inner surfaces is shorter than the wire diameter of the O-ring  58 . Therefore, the valve element including the groove  110  can obtain a desired sealability and can more reliably prevent the O-ring  58  from falling off. 
     REFERENCE SIGNS LIST 
     
         
           10 : Pipe joint 
           12 : Male joint 
           14 : Female joint 
           16 : Male joint main body 
           20 : Valve element 
           28 : Shaft portion 
           30 : Valve portion 
           34 : Coil spring 
           36 : Base end portion 
           40 : Side portion 
           41 : First region 
           42 : First surface 
           43 : Second region 
           44 : Second surface 
           46 : Groove 
           47 : Connection portion 
           48 : Bottom surface 
           49 : Connection portion 
           50   a ,  50   b : Inner surface 
           54 : Deformation portion 
           55 : Thin portion 
           58 : O-ring 
           110 : Groove 
         A: Central axis