Abstract:
Provided is a coupling for fluid pipes, comprising a plug and a socket. The socket includes a socket body, a sleeve slidably fitted on the outer peripheral surface of the socket body and urged toward the distal end thereof, and a plurality of locking members provided on the socket body and capable of being engaged with and disengaged from an outer peripheral groove by means of the sleeve. The pipe coupling further comprises a pair of end faces provided individually on the plug and the socket and adapted to abut against each other when the plug and the socket are joined, and a shaped packing provided on one of the coupling end faces and adapted to prevent admission of external air when the coupling end faces abut against each other and to prevent the fluid from leaking out when the coupling end faces are separated from each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-242895, filed Aug. 10, 2000, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a coupling for fluid pipes, and more specifically, to a pipe coupling suitable for use with a vessel containing a chemical agent or the like that is used in the field of semiconductor manufacture, for example. 
     2. Description of the Related Art 
     Pipe couplings that are composed of a plug and a socket each are used in various chemical lines and ultrapure water lines in the fields of the semiconductor industry, bio-industry, and chemical-medical industry. 
     With the development of highly integrated semiconductor wafers in semiconductor manufacturing processes, which is involved in the rapid progress of the LSI or super LSI technology, in particular, the pipe couplings of this type are used in lines for various liquids, such as chemicals, and various treatment gases. 
     Normally, chemicals are received in vessels, which are utilized for the storage and transportation of the chemicals. In using a chemical agent in a vessel, the chemical agent is fed to the supply side in a manner such that a socket paired with a plug on the vessel is connected to and disconnected from the plug. Various vessels and pipe couplings used therein are proposed in Jpn. Pat. Publication No. 2761354 and Jpn. Pat. Appln. KOKAI Publication No. 11-193894. 
     In the pipe coupling described in Jpn. Pat. Publication No. 2761354, the distal end portion of a valve projects by a large amount from an opening in the distal end portion of a cylindrical main socket body, and a seal member seals a space between the socket and a plug on the outer peripheral surface of the plug. 
     In the pipe coupling described in Jpn. Pat. Appln. KOKAI Publication No. 11-193894, on the other hand, the distal ends of valves provided on a socket and a plug project from openings in a cylindrical main socket body and a plug body, and a seal member seals a space between the socket and a plug on the outer peripheral surface of the plug. 
     In both these pipe couplings, however, the distal ends of the valves project from the openings when the socket and the plug are connected, so that the outer peripheral surface of the plug must be sealed by means of an O-ring before the valves are opened. Thus, a space is formed between the opening of the socket and the distal end of the plug. Possibly, therefore, air may get into this space, and a fluid may drip out when the socket and the plug are separated from each other. 
     In a pipe coupling shown in FIG. 11, an O-ring  3  is provided on the end face of a socket  1  or a plug  2  without making the distal end of the valve project from an opening. When the socket  1  and the plug  2  are connected to each other, in this case, the O-ring  3  on the socket contacts the end face of the plug along a circular line. FIG. 11 shows a normal state that involves no problem. If bending force acts on the socket  1  and the plug  2 , as shown in FIG. 12, however, there is no room for the O-ring  3  to collapse. Thus, the sealing properties become so poor that fluid leakage occurs. 
     If a spring and other fluid-contacted parts in a pipe coupling are not chemical-resistant, metal is eluted into a fluid, and particles are produced in a semiconductor manufacturing process or the like. These situations must be securely avoided for the semiconductor manufacturing process, in particular. 
     Further, fluid dripping that is caused as the pipe coupling is disconnected may cause a chemical agent or the like to flow out during the storage or transportation of the vessel, thereby endangering the operation. It is necessary, therefore, that a highly dangerous chemical agent should not leak from the vessel during filling operation. 
     Furthermore, it is essential securely to prevent wrong connect between a socket and a plug. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention has been contrived in consideration of these circumstances, and its object is to provide a pipe coupling in which inflow of air can be reduced to a very low level when a socket and a plug are connected to each other and a fluid can be prevented from dripping out when the two members are separated from each other. 
     Another object of the invention is to provide a pipe coupling of which members that touch a fluid have chemical-resistance properties such that production of particles can be reduced. 
     Still another object of the invention is to provide a pipe coupling capable of securely preventing a fluid from flowing out even in case it drips. 
     An additional object of the invention is to provide a pipe coupling capable of preventing wrong connection between a socket and a plug. 
     In order to achieve the above objects, according to the present invention, there is provided a coupling for fluid pipes, comprising a plug having an outer peripheral groove; a socket capable of being connected to the plug, the socket including a socket body, a sleeve slidably fitted on the outer peripheral surface of the socket body and urged toward the distal end thereof, and a plurality of locking members provided on the socket body and capable of being engaged with and disengaged from the outer peripheral groove by means of the sleeve; a pair of end faces provided individually on the plug and the socket and adapted to abut against each other when the plug and the socket are joined; and a shaped packing provided on one of the coupling end faces and adapted to prevent admission of external air when the coupling end faces abut against each other and to prevent the fluid from leaking out when the coupling end faces are separated from each other. 
     According to this pipe coupling, inflow of air can be reduced to a very low level when the socket and the plug are connected to each other, and the fluid can be prevented from dripping out when the two members are separated from each other. If the pipe coupling is used in a semiconductor manufacturing process, for example, it can prevent the fluid from dripping out and securely prevent fluid leakage during filling operation for filling a harmful chemical agent into a vessel or the like. 
     Preferably, the shaped packing includes a body having a circular cross section and at least two ring-shaped lips protruding from one side of the body. If bending force acts on the socket and the plug, in this case, one of the lips of the packing can maintain the sealing function, so that leakage can be prevented with improved reliability. 
     Preferably, the sleeve has, on the rear end side thereof, display portions for preventing wrong connection with the plug. In this case, correct positions can be easily recognized when the sleeve of the socket is connected downward to the plug, so that the connection between the sleeve and the plug is easy. In order to prevent wrong connection, the sleeve or the plug has a projection projecting in the radial direction, and the other of the elements has an axial groove capable of receiving the projection. 
     In the case where the socket is provided with a grip portion axially extending from the rear end side of the socket body, the grip portion can be formed into an easy-to-grip shape. Therefore, the sleeve can be prevented from being unexpectedly touched as the socket is connected. Thus, wrong connection between the socket and the plug can be prevented, and the efficiency of connection and disconnection of the pipe coupling can be improved. 
     In the pipe coupling, the plug may be fixed in a cup-shaped plug holder which is capable of being attached to a vessel containing the fluid. The plug holder may includes a thread portion capable of being attached to the vessel and an opening for receiving the socket capable of being fitted with the plug, and a cap may be attached to the opening. Preferably, the cap includes an fixing portion capable of being fixed to the plug holder and a ring-shaped seal portion capable of being engaged with the inner peripheral surface of the opening. 
     In this case, the plug having its internal valve closed can be fixed in the plug holder, and the opening of the plug holder can be closed by means of the cap. If fluid dripping happens, therefore, the fluid can be prevented from flowing out of the pipe coupling, so that the pipe coupling can be used very safely. 
     If all of the members capable of touching the fluid are formed of a chemical-resistant material, the pipe coupling can be suitably used in a vessel containing a chemical agent or the like that is used in the field of semiconductor manufacture, for example. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
     FIG. 1 is a sectional view showing a connected state of a pipe coupling according to an embodiment of the present invention; 
     FIG. 2 is a sectional view showing a separate state of the pipe coupling of FIG. 1; 
     FIG. 3 is a schematic view for illustrating chemical agent feeding operation using the pipe coupling shown in FIG. 1; 
     FIG. 4 is a plan view showing a plug holder fitted with a cap; 
     FIG. 5 is a sectional view taken along line A—A of FIG. 4; 
     FIG. 6 is an enlarged view showing a part of FIG. 5; 
     FIGS. 7A and 7B are a plan view and a bottom view, respectively, of a sleeve attached to a socket; 
     FIG. 8 is an enlarged sectional view showing a normally connected state of the pipe coupling; 
     FIG. 9 is a sectional view similar to FIG. 8, showing a bent state of the pipe coupling; 
     FIG. 10 is a sectional view of a shaped packing attached to the socket; 
     FIG. 11 is a partial sectional view showing a connected state of a conventional pipe coupling; and 
     FIG. 12 is a view similar to FIG. 11, showing a bent state of the conventional pipe coupling. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the accompanying drawings, numeral  10  denotes a socket, and  11  denotes a plug that is paired with the socket  10  and can be connected to and disconnected from the socket  10 . The plug  11  is screwed in a substantially cup-shaped plug holder  12 . The socket  10 , plug  11 , plug holder  12 , and other components (fluid-contacted parts) are formed of chemical-resistant materials. Preferred materials include resins such as fluoroplastic, polyethylene, etc. 
     The rear end portion of a socket body  13  of the socket  10  extends in the axial direction and forms a grip portion  14 . In this embodiment, the grip portion  14  is formed by screwing an adapter  15  into the rear end portion of the socket body  13 . The rear part of the adapter  15  is tapered forward to facilitate gripping. An end portion of the adapter  15  is provided with an internal thread portion  17 , to which a pipe  16  (FIG. 3) for fluid supply to the semiconductor manufacturing premise is connected. 
     A slide valve  18  is slidably fitted on the inner surface of the socket body  13 . The valve  18  is elastically urged toward the distal end of the socket body  13  by means of a spring  19 . The spring  19  is formed of a metallic spring material coated with a chemical-resistant resin. An annular packing  22  is fitted in an annular groove  21  that is formed in a coupling end face  20  on the distal end side of the valve  18 . The packing  22  is formed of chemical-resistant rubber or resin and has a noncircular cross section. As shown in FIG. 10, at least two ring-shaped lips  24   a  and  24   b  protrude integrally from one side face of a packing body  23  that has a circular cross section. The lips  24   a  and  24   b  project from the coupling end face side when the packing  22  is fitted in the groove  21 . 
     The slide valve  18  is slidably fitted on the outer peripheral surface of the distal end portion of the adapter  15  by means of a packing  25  with a Y-shaped cross section for reduced sliding resistance. The inner peripheral surface of the distal end portion of the valve  18  is in engagement with a valve seat  26   a  of a valve shaft  26  that is fixed to the adapter  15 . The rear end portion of the valve shaft  26  is screwed in a holding portion  27  of the adapter  15 . The holding portion  27  has a plurality of through holes  28 . 
     Further, a sleeve  30  is slidably fitted on the outer peripheral surface of the socket body  13 . The sleeve  30  is elastically urged toward the distal end of the socket body  13  by means of a spring  29 . The spring  29  is formed of a metallic spring material coated with a chemical-resistant resin. The sleeve  30  is rotatable with respect to the socket body  13 . 
     One end of the spring  29  is in engagement with an inner stepped portion of a large-diameter portion  30   a  of the sleeve  30 , and the other end with an outwardly projecting stepped portion  13   a  which is formed on the peripheral surface of the socket body  13 . A stop ring  31  is fitted in the rear end portion of the sleeve  30 . The ring  31  is designed to engage the stepped portion  13   a , thereby preventing the sleeve  30  from slipping off. 
     As shown in FIGS. 7A and 7B, key grooves  32   a  and  32   b  for preventing wrong connection with the plug  11  are formed on the inner peripheral surface of the distal end portion of the sleeve  30 . The grooves  32   a  and  32   b  are located at a given angle (90° in this embodiment) from each other. Corresponding in angular position to the grooves  32   a  and  32   b , respectively, display portions  34   a  and  34   b  are formed on the rear end portion of the sleeve  30 . The display portions  34   a  and  34   b  facilitates position alignment with projections  33   a  and  33   b  that are formed on the plug  11 . The plug  11  and the socket  10  cannot be connected to each other if an angle θ between the key grooves  32   a  and  32   b  on the socket side is not equal to the angle between the projections  33   a  and  33   b  on the plug side. The angle θ is settled depending on the properties of a fluid used. 
     If necessary, identification portions with discriminable colors or the like may be provided in a suitable position on the socket  10 . 
     On the inner peripheral side of a small-diameter portion  30   b  of the sleeve  30 , moreover, a ball presser portion  35  and a ball relief portion  36  are formed adjacent to each other. The presser portion  35  and the relief portion  36  enable locking balls  37  to project or retract individually through a plurality of taper holes  13   b  in the socket body  13 . The balls  37  are located in the ball relief portion  36  when the socket  10  and the plug  11  are not connected to each other. When the socket and the plug are connected, the balls  37  are engaged with an outer peripheral groove  38  on the outer peripheral surface of the plug  11  by means of the ball presser portion  35 . The locking balls  37  may be replaced with locking claws or any other suitable locking members. 
     The following is a description of the plug  11 . As shown in FIG. 5, an external thread portion  11   a  on the rear end portion of the plug  11  is screwed in an internal thread portion  12   a  of the plug holder  12 , which is formed of a chemical-resistant resin, such as polyethylene, fluoroplastic, etc. An O-ring  39  is interposed between the plug  11  and the plug holder  12 . As shown in FIGS. 8 and 9, a planar end face  11   b  of the plug  11  serves as an abutting surface for the lips  24   a  and  24   b  of the packing  22 . 
     The plug  11  contains therein a valve  42 , which is elastically urged to rest against a valve seat  42   c  (FIG. 8) by means of a bellows-shaped spring  41  of a chemical-resistant resin. The valve  42  has radial through holes  42   a . A valve stopper  42   b  on the rear end portion of the plug  11  stops the valve  42  that is pressed against the urging force of the spring  41 . 
     Jig attachment grooves  43 , four in number according to this embodiment, are arranged at an equal interval on the inner periphery of the upper end portion of an opening  12   c  of the plug holder  12 . Further, the upper end of the plug holder  12  is provided with an attachment groove  12   b  for fixing an attachment portion  44   a  that is coupled to a disk-shaped cap  44  by means of a connecting piece  44   d . Projecting pieces  44   b  and a knob portion  44   c  that can be fitted in the attachment grooves  43  are formed on the outer periphery of the cap  44 . A ring-shaped seal portion  45 , which hangs down from the lower surface of the cap  44 , is removably fitted in the opening  12   c  of the plug holder  12 . Furthermore, sealing ridges  40  are formed on the outer peripheral surface of the seal portion  45 , whereby the sealing properties of the seal portion  45  in the opening  12   c  are maintained. A mounting hole  12   d  for a siphon pipe  46  is formed in the lower part of the plug holder  12 . An external thread portion  12   e  is formed on the outer periphery of the upper part of the holder  12 . The external thread portion  12   e  is screwed in an internal thread portion  47   a  on the upper wall portion of a vessel  47 , that contains a chemical agent or the like, with a packing  47   b  interposed between the holder  12  and the vessel  47 . 
     The following is a description of operation according to this embodiment. 
     In mounting the plug holder  12  on the upper wall portion of the vessel  47 , a jig (not shown) is attached to the jig attachment grooves  43 , and the holder  12  is screwed into the internal thread portion  47   a . The leaked fluid never pools in the attachment grooves  43 , and the projecting pieces  44   b  of the cap  44  get into the grooves  43 , so that there is no possibility of the fluid flowing out. As shown in FIG. 3, the vessel  47  is provided with two plug holders  12 , through which the chemical agent in the vessel  47  can be supplied. 
     When an operator pinches the knob portion  44   c  of the cap  44 , the cap  44  can be detached from the opening  12   c  of the plug holder  12 . As this is done, the cap  44  cannot be easily disengaged from the plug holder  12 , since the attachment portion  44   a  is fixed to the attachment groove  12   b  of the holder  12  by means of the connecting piece  44   d . In connecting the plug  11  in the plug holder  12  and the socket  10  in this state, the operator first selects the socket  10  corresponding to the plug  11 . The operator holds the grip portion  14  of the socket  10 , rotates the sleeve  30 , thereby aligning the display portions  34   a  and  34   b  on the rear end face of the sleeve  30  with the projections  33   a  and  33   b  of the plug  11 , and inserts the socket  10  into the plug  11 . Thereupon, the key grooves  32   a  and  32   b  are aligned with the projections  33   a  and  33   b , respectively. If they fail to be aligned, the distal end face of the sleeve  30  abuts against the projections  33   a  and  33   b , so that the socket  10  cannot be inserted into the plug  11 . Thus, the plug  11  and the socket  10  can be prevented from being wrongly connected to each other. 
     Since the grip portion  14  extends so that its rear portion is tapered forward, it can be grasped with ease, and therefore, the socket  10  can be easily connected to the plug  11 . 
     If the socket  10  continues to be inserted after the socket  10  and the plug  11  are aligned as a pair, the distal end face of the plug  11  and the coupling end face  20  of the slide valve  18  of the socket  10  engage each other with the shaped packing  22  between them. The slide valve  18  is pushed into the socket  10  and lifted from the valve seat  26   a  of the valve shaft  26 , resisting the urging force of the spring  19 . Further, the valve  42  is pushed into the plug  11  by means of the distal end face of the valve shaft  26 , resisting the urging force of the bellows-shaped spring  41 , whereupon a passage for the socket  10  and the plug  11  is formed. 
     On the other hand, the locking balls  37  in the socket body  13  are allowed to move toward the center of the socket  10  and engage the outer peripheral groove  38  of the plug  11 , whereupon the socket  10  and the plug  11  are connected to each other, as shown in FIG.  1 . 
     In a normally connected state, the two lips  24   a  and  24   b  of the shaped packing  22  abut against the planar end face  11   b  of the plug  11  to seal the space between them, as shown in FIG.  8 . If any bending forces act on the socket  10  and the plug  11 , as shown in FIG. 9, one of the lips  24   a  and  24   b  can keep the sealing function, so that leakage can be prevented with improved reliability. 
     FIG. 3 shows the way in which the chemical agent in the vessel  47  is supplied by means of a vacuum pump to the field of semiconductor manufacture through the pipes  16 . The vessel  47  is provided with two plugs, namely a supply plug and a plug for preventing negative pressure in the vessel  47 . The socket  10  is connected to each of the plugs. 
     In separating the socket  10  from the plug  11 , the sleeve  30  in the state of FIG. 1 is pulled upward. Thereupon, the locking balls  37  are brought to the level of the ball relief portion  36 . If the socket  10  is pulled upward when the balls  37  are allowed to move in the diametrical direction, the balls  37  are disengaged from the outer peripheral groove  38  of the plug  11 . At the same time, the slide valve  18  is caused to slide toward the distal end of the socket  10  and rest against the valve seat  26   a  of the valve shaft  26  by means of the urging force of the spring  19 , thereby closing the passage. Further, the valve  42  of the plug  11  is restored to its original position by means of the urging force of the spring  41 , thereby closing the passage. If the socket  10  is pulled upward in FIG. 1, furthermore, the coupling end face of the slide valve  18  of the socket  10  and the end face of the plug  11  are separated from each other, whereupon the sealing function of the shaped packing  22  is released. 
     Thus, the pipe coupling of the invention is a highly valuable coupling to be attached to a chemical agent vessel, in particular, without the possibility of the fluid dripping out when the socket  10  and the plug  11  are separated from each other. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.