Abstract:
The invention is directed to a fluid mixture delivery instrument which excludes entry of air during fluid delivery. The instrument has a main chamber part and a plurality of branch pipes which extend in different directions from the chamber part. The branch pipes are configured with slitted rubber stoppers with closures to which connection tubes can be inserted for the delivery of fluid with exclusion of air.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a fluid mixture delivery instrument in which a plurality of infusion tubes or the like for medical purposes are joined and drug solutions or the like flow between all of these infusion tubes. 
       BACKGROUND OF THE INVENTION 
       [0002]    Conventionally, certain drug solutions or physiological saline etc. are supplied inside the body of a patient using a plurality of infusion tubes, and in such cases all of the infusion tubes are linked in communication or blocked using a fluid mixture delivery instrument for a medical stopcock or the like. There are instruments such as this among fluid mixture delivery instruments which are equipped with a plurality of branch pipes and which have a rubber stopper which can be pierced by an injection needle or the like attached to the inside of certain of the branch pipes; (see for example Japanese Unexamined Patent Application Laid-Open 200416437. 
         [0003]    These fluid mixture delivery instruments are equipped with two branch pipes which extend horizontally from a main body portion and an injector connection port which is formed at the top of the main body portion. Then, provision is made in said injector connection part for a sealing valve body in which an insertion part which passes vertically through is formed. Consequently, it is possible for a twist-lock type injector and the inside of the main body of the fluid mixture delivery instrument to be linked in communication, by means of the insertion of the twist-lock type injector into the insertion part of the sealing valve body. By virtue of this, it is possible for a drug solution to be injected inside the main body of the fluid mixture delivery instrument from the twist-lock type injector, and for a drug solution to be extracted from the main body of the fluid mixture delivery instrument. 
         [0004]    However, with a conventional fluid mixture delivery instrument as described above, when the twist-lock type injector is inserted into the insertion part of the sealing valve body, the lower part of the sealing valve body is pushed out into a space part inside the fluid mixture delivery instrument and protrudes. 
         [0005]    Consequently, there are problems in that air is liable to remain around the portion of the sealing valve body which is protruding into the space part inside the fluid mixture delivery instrument, and a troublesome operation is needed to remove the air inside the fluid mixture delivery instrument and inside the tubes of the infusion line. Furthermore, there are also problems in that bacteria are easily produced inside the fluid mixture delivery instrument due to the fact that air remains. 
         [0006]    In view of this situation, the aim of the present invention is to provide a fluid mixture delivery instrument with which air is unlikely to remain inside. 
       SUMMARY OF THE INVENTION 
       [0007]    The invention is directed to a fluid mixture delivery instrument equipped with a mixture delivery instrument main body generally comprising a chamber part and a plurality of branch pipes which extend in different respective directions from the chamber part and which include an upper branch pipe extending at least upwards; and a rubber stopper which is attached to the upper branch pipe and which closes off the upper branch pipe by means of the closure of a slit passing through the inside, and also which links in communication the inside of the chamber part and the inside of a connection pipe by means of the insertion of the connection pipe into the slit, and the fluid mixture delivery instrument is such that the rubber stopper is configured by a fixing piece which is fixed to the upper branch pipe and a rubber stopper main body which is joined to the fixing piece and which is pushed inside the upper branch pipe by means of the insertion of the connection pipe into the slit, and when the rubber stopper main body is pushed inside the upper branch pipe by means of the connection pipe, the lower surface of the rubber stopper main body which is positioned inside the upper branch pipe becomes a roughly level surface in a state in which it is in close contact with the inner peripheral surface of the upper branch pipe. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0008]      FIG. 1  is a plan view showing the fluid mixture delivery instrument pertaining to the first mode of implementation of the present invention. 
           [0009]      FIG. 2  is a front view of the fluid mixture delivery instrument. 
           [0010]      FIG. 3  is a side view of the fluid mixture delivery instrument. 
           [0011]      FIG. 4  is a cross-sectional view of the fluid mixture delivery instrument. 
           [0012]      FIG. 5  is a cross-sectional view showing a state in which the male luer part is inserted into the rubber stopper of the fluid mixture delivery instrument of  FIG. 4 . 
           [0013]      FIG. 6  is a cross-sectional view showing the relationship between the main body and the valve body of the fluid mixture delivery instrument. 
           [0014]      FIG. 7  is an oblique view showing the valve body. 
           [0015]      FIG. 8  is a front view showing a state in which the syringe is attached to the fluid mixture delivery instrument. 
           [0016]      FIG. 9  is a cross-sectional view of the fluid mixture delivery instrument pertaining to the second mode of implementation of the present invention. 
           [0017]      FIG. 10  is a cross-sectional view showing a state in which the male luer part is inserted into the rubber stopper of the fluid mixture delivery instrument of  FIG. 9 . 
       
    
    
     EXPLANATION OF SYMBOLS  
       [0000]    
       
           10  . . . mixture delivery instrument main body; 
           11  . . . chamber part; 
           12  . . . downstream branch pipe; 
           13  . . . upper branch pipe; 
           14  . . . upstream branch pipe; 
           16 ,  44  . . . joining aperture edge part; 
           16   a ,  44   a  . . . auxiliary joining part; 
           17 ,  47  . . . joining member; 
           20 ,  40  . . . rubber stopper; 
           21 ,  41  . . . rubber stopper main body; 
           22  . . . fixing piece; 
           23  . . . slit; 
           28   a  . . . male luer part; 
           30  . . . valve body; 
           42  . . . upper fixing piece; 
           43  . . . lower fixing piece; 
         A, B . . . fluid mixture delivery instrument. 
       
     
       DETAILED DESCRIPTION OF THE INVENTION 
     (First Mode of Implementation) 
       [0035]    The fluid mixture delivery instrument pertaining to a first mode of implementation of the present invention will be described in detail below using the figures.  FIG. 1  to  FIG. 3  show the fluid mixture delivery instrument A pertaining to this mode of implementation, and said fluid mixture delivery instrument A is configured by a mixture delivery instrument main body  10 , a rubber stopper  20  (see  FIG. 4  and  FIG. 5 ) attached inside the mixture delivery instrument main body  10 , a cover member  25  and a valve body  30 . Then, the mixture delivery instrument main body  10  is configured by a cylindrical chamber part  11  which is short in the axial direction and three branch pipes comprising a downstream branch pipe  12 , an upper branch pipe  13 , and an upstream branch pipe  14 , which are joined maintaining an angle of 90 degrees to the outer peripheral surface of the chamber part  11 . 
         [0036]    As shown in  FIG. 4  and  FIG. 5 , the axial direction to the chamber part  11  is arranged facing to the front and rear directions (the left/right direction in  FIG. 4  and  FIG. 5 ), and a roughly cylindrical shape with a closed off rear part is formed. Then, a prescribed gap is provided on the inner surface of the rear wall part  11   a  of the chamber part  11  between the inner peripheral surfaces of the chamber part  11 , and an annular engagement part  11   b  which extends forward is formed. Furthermore, through-holes  15   a ,  15   b ,  15   c  (see  FIG. 4  to  FIG. 6 ) are formed in roughly the centre of the axial direction of the chamber part  11 . Among these through-holes  15   a ,  15   b ,  15   c , the position of the centre part of the through-hole  15   b  is formed slightly offset to the front side than the position of the centre part of the other through-holes  15   a ,  15   c.    
         [0037]    The downstream branch pipe  12  is provided in a portion of the chamber part  11  corresponding to the through-hole  15   a , and the inside of the chamber part  11  and a flow channel  12   a  which is formed inside the downstream branch pipe  12  are linked in communication by way of said through-hole  15   a . Furthermore, the diameter of the through-hole  15   b  is set to be larger than the diameters of the through-holes  15   a ,  15   c . A joining aperture edge part  16  which configures part of the upper branch pipe  13  is provided in a portion of the chamber part  11  corresponding to said through-hole  15   b , and the inside of the chamber part  11  and the flow channel  13   a  which is formed inside the joining aperture edge part  16  are linked in communication by way of the through-hole  15   b.    
         [0038]    Furthermore, an auxiliary joining part  16   a  which surrounds the joining aperture edge part  16  in a state in which a gap is maintained with the joining aperture edge part  16  is formed on the outer peripheral side of the joining peripheral edge part  16 , on the outer peripheral surface of the chamber part  11 , and a partitioning wall  16   b  for partitioning the front and rear of the flow channel  13   a  is formed on both the left and right sides of the inner peripheral surface of the joining peripheral edge part  16 , in a state of bridging. Furthermore, the upstream branch pipe  14  is provided in a portion of the chamber part  11  corresponding to the through-hole  15   c , and the inside of the chamber part  11  and a flow channel  14   a  which is formed inside the upstream branch pipe  14  are linked in communication by way of said through-hole  15   c.    
         [0039]    The downstream branch pipe  12  is formed integrally with the chamber part  11 , and it is configured by a base end part  12   b  on the chamber part  11  side, and a male luer part  12   c  on the tip end side which is formed to be narrower than the base end part  12   b . Furthermore, the male luer part  12   c  is formed to taper at its end so that the tip end side portion is narrower than the base end part  12   b  side portion. Then, an engaging protruding part  12   d  is formed along the circumference of the outer peripheral surface of the downstream branch pipe  12 , at the boundary part between the base end part  12   b  and the male luer part  12   c.    
         [0040]    The upper branch pipe  13  is configured by the joining aperture edge part  16  and the auxiliary joining part  16 a which have been described above, and a roughly cap-shaped joining member  17 . Said joining member  17  is configured by a short cylindrical body with a larger diameter on the lower part side, which gets steadily smaller moving upwards, and a lower end peripheral edge part  17   a  which is formed with a roughly annular shape is inserted between the joining aperture edge part  16  and the auxiliary joining part  16   a , and fixed to the chamber part  11 . Furthermore, the cover member  25  for fixing the rubber stopper  20  with the joining member  17  is attached to the outer peripheral side of the joining member  17 . 
         [0041]    The upper part  26  of the cover member  25  is formed with a short, roughly cylindrical shape with a size such that it can engage with the top outer periphery of the joining member  17 , and the lower part  27  of said cover member is formed with a short, roughly cap shape with a larger diameter than that of the lower end peripheral edge part  17   a  of the joining member  17 , and said shape is an ellipse which is long in the longitudinal direction when viewed in a plane. Then, the cover member  25  is detachably attached to the upper branch pipe  13  by means of the engagement of the upper part  26  with the top outer periphery of the joining member  17 , and by means of the engagement of the lower end inner peripheral surface of the lower part  27  with the outer peripheral surface of the auxiliary joining part  16   a . Furthermore, an annular ceiling part  26   a  extends from the upper end part towards the inside of the upper part  26  of the cover member  25 , and at its tip end a roughly annular engagement piece  26   b  with a smaller diameter than the outer peripheral surface of the upper part  26  extends downwards. Then, the rubber stopper  20  is fixed by means of the engagement of said cover member  25  and the joining member  17 . 
         [0042]    The rubber stopper  20  is made of an elastic member such as synthetic rubber or an elastomer, and it is configured by a thick disc-shaped rubber stopper body  21  and a roughly cylindrical fixing piece  22  which is formed around the rubber stopper main body  21 . The rubber stopper main body  21  and the fixing piece  22  are joined by each of their lower part side portions, and their upper part side portions are in a state of separation. Then, as shown in  FIG. 4 , the rubber stopper  20  is attached to the cover member  25  by means of the insertion of the engagement piece  26   b  between the rubber stopper main body  21  and the fixing piece  22  in the rubber stopper  20 , and the rubber stopper  20  is fixed by the joining member  17  and the cover member  25  by means of the attachment of the cover member  25  in this state to the upper branch pipe  13 . 
         [0043]    In other words, the upper part side portion of the fixing piece  22  is surrounded by the upper part  26 , the ceiling part  26   a  and the engagement piece  26   b  of the cover member  25 , and also the fixing piece  22  is prevented from breaking free from between the upper part  26  of the cover member  25  and the joining member  17 , due to the fact that the joining part of the rubber stopper main body  21  and the fixing piece  22  in the rubber stopper  20  is pinched by the upper end part of the joining member  17  and the lower end part of the engagement piece  26   b . By virtue of this, a state is achieved in which the fixing piece  22  is fixed and the rubber stopper main body  21  can move from the upper part  26  of the cover member  25  due to the fact that it is strongly push-pressured. Furthermore, when the rubber stopper main body  21  moves, the portion around the fixing piece  22  and the joining part between the fixing piece  22  and the rubber stopper main body  21  extends. 
         [0044]    Furthermore, a slit  23  which passes through between the inside of the upper branch pipe  13  and the outside of the upper branch pipe  13  for forming part of the flow channel  13   a  of the upper branch pipe  13  is provided in the rubber stopper main body  21  of said rubber stopper  20 . Said slit  23  is in a state of closure due to the elasticity of the rubber stopper  20  when the flow channel  13   a  of the upper branch pipe  13  is not in use. Furthermore, a flow channel can be formed which is linked in communication with the flow channel  13   a  inside a male luer part  28   a  by means of the insertion of the male lure part  28   a  of a syringe  28  (see  FIG. 8 ), for example, into the slit  23  of the rubber stopper  20  when the flow channel  13   a  of the upper branch pipe  13  is in use. 
         [0045]    By virtue of this, a drug solution housing part  28 b of the syringe  28  and the inside of the upper branch pipe  13  are linked in communication. Furthermore, at this time, the area between the male luer part  28   a  and the peripheral surface of the slit  23  reach a state of close contact due to the elasticity of the rubber stopper  20 . In addition, the peripheral edge part of the lower surface of the rubber stopper main body  21  comes into close contact with the inner peripheral surface of the branch pipe  13 . Then, the rubber stopper main body  21  is push-pressured downwards by means of the male luer part  28   a , and its lower surface becomes a level surface, as shown in  FIG. 5 . In other words, when said rubber stopper main body  21  is push-pressured downwards inside the upper branch pipe  13  by means of the male luer part  28   a , and when the male luer part  28   a  is inserted inside the slit  23 , the lower surface is preformed so as to become a level surface. 
         [0046]    The upstream branch pipe  14  is integrally formed with the chamber part  11 , and the flow channel  14   a  which comprises a tapered hole part is formed inside. Said flow channel  14   a  is linked in communication with the through-hole  15   c , and a portion thereof on the through-hole  15   c  side is formed as a taper in which the diameter gets smaller closer to the through-hole  15   c , and the diameter gets larger moving away from the through-hole  15   c . Furthermore, the upstream side portion of the flow channel  14   a  (the right side portion in  FIG. 6 ) is formed as a taper in which the diameter gets steadily larger moving closer to the aperture part of the upstream branch pipe  14 . Then, a joining screw part  14 b is formed on the outer peripheral surface of the aperture part of the upstream branch pipe  14 . 
         [0047]    The valve body  30  is configured by a roughly cylindrical valve main body  31  and an operating part  32  which is joined to the front end part of the valve main body  31 . Then, the valve main body  31  is arranged inside the chamber part  11 , in a state in which its tip end part is inserted between the inner peripheral surface of the chamber part  11  and the engagement part  11   b , and said valve main body rotates in the axial direction of the chamber part  11  by means of the operation of the operating part  32 . Furthermore, as shown in  FIG. 7 , two groove parts  33 ,  34  are formed in a row in the axial direction on the outer peripheral surface of the valve main body  31 . The groove part  33  is configured by a cut-out groove which extends over a rough semi-circle along the circumference on a portion of the outer peripheral surface of the valve main body  31  which is slightly further rearwards than the centre in the axial direction. 
         [0048]    Furthermore the groove part  34  is configured by a roughly L-shaped cut-out groove which comprises a circumferential direction groove part  34   a  which extends along the outer peripheral surface of the valve main body  31 , parallel to the groove part  33  on a portion of the outer peripheral surface of the valve main body  31  which is slightly further forwards than the centre in the axial direction, and an axial direction groove part  34   b  which extends to the rear side in the axial direction, curving away from one end part of the circumferential direction groove part  34   a . Then, the axial direction groove part  34   b  of the groove part  34  is provided in a position which maintains a prescribed gap with one end part of the groove part  33 , and the other end part of the circumferential direction groove part  34   a  of the groove part  34  is positioned on one side (the front side in  FIG. 7 ) further along in the circumferential direction than the other end part of the groove part  33 . 
         [0049]    The length of the groove part  33  and the groove part  34  along the circumferential direction of the valve main body  31  is set to be both equal and roughly semi-circular on the circumference, and the gap between the groove part  33  and the circumferential direction groove part  34   a  of the groove part  34 , and the gap between the groove part  33  and the axial direction groove part  34   b  of the groove part  34  is set to be equal. Then, a barrier part  35  which runs along the outer peripheral surface of the valve main body  31  is formed between the groove part  33  and the circumferential direction groove part  34   a  of the groove part  34 . Furthermore, the valve body  31  which is arranged inside the chamber part  11  is in a state in which the portion where the groove part  33  and the axial direction groove part  34   b  of the groove part  34  are formed matches the position of the through-holes  15   a ,  15   c , and the portion where the circumferential direction groove part  34   a  of the groove part  34  is formed is opposite the front part side portion on the inner peripheral surface of the chamber part  11 . 
         [0050]    Furthermore, the portion where a barrier part  35  on the outer peripheral surface of the valve main body  31  is formed is in a state in which it faces a portion which is slightly further forwards than the through-hole  15   b  and the centre of the inner peripheral surface of the chamber part  11 . Consequently, as shown in  FIG. 6 , when the valve body  31  is positioned so that the barrier part  35  faces upwards, the groove part  33  is opposite the through-hole  15   c , and the inside of the chamber part  11  and the upstream branch pipe  14  are linked in communication via the groove part  33 . Furthermore, the rear part side of the axial direction groove part  34   b  in the groove part  34  is opposite the through-hole  15   a , and the inside of the chamber part  11  and the downstream branch pipe  12  are linked in communication via the groove part  34 . 
         [0051]    In this case, the partitioning wall  16   b  is positioned over the barrier part  35 , and the upper surface of the barrier part  35  and the lower surface of the partitioning wall  16   b  are in contact in a very close state. Then, a space part which forms the flow channel  13   a  of the upper branch pipe  13  is positioned on top of the partitioning wall  16   b , and therefore the groove part  33  and the groove part  34  are linked in communication via the flow channel  13   a . Accordingly, in this state, it is possible for a drug solution or the like to flow into the downstream branch pipe  12  from the upstream branch pipe  14 , via the chamber part  11  and the upper branch pipe  13 . In this case, the drug solution or the like which flows inside the groove part  33  from the upstream branch pipe  14  goes over the partitioning wall  16   b  and flows into the groove part  34 . Consequently, the drug solution or the like passes through inside the flow channel  13   a  at the top of the chamber part  11 , and it is possible to suppress the phenomenon of air or the like remaining inside the chamber part  11  and inside the flow channel  13   a.    
         [0052]    From this state, when the valve body  30  is rotated one way to make the groove part  33  face the through-hole  15   a , and also the outer peripheral surface of the valve main body  31  is made to face the through-hole  15   c , the inside of the chamber part  11  and the downstream branch pipe  12  are linked in communication, and there is a block between the inside of the chamber part  11  and the upstream branch pipe  14 . Furthermore, from the state in  FIG. 6 , when the valve body  30  is rotated the other way to maintain a state in which the groove part  33  is made to face the through-hole  15   c , and also the outer peripheral surface of the valve main body  31  is made to face the through-hole  15   a , there is a block between the inside of the chamber part  11  and the downstream branch pipe  12 , and the inside of the chamber part  11  and the upstream branch pipe  14  are linked in communication. 
         [0053]    In this way, it is possible for both the downstream branch pipe  12  and the upstream branch pipe  14  to be linked in communication with the inside of the chamber part  11 , and for only one of them to be linked in communication with the chamber part  11 , by means of the rotational operation of the valve body  30 . Moreover, the operating part  32  is equipped with three operating pieces  32   a ,  32   b ,  32   c , and said operating pieces  32   a ,  32   b ,  32   c  are formed maintaining an angle of 90 degrees, so as to correspond to the downstream branch pipe  12 , the upper branch pipe  13  and the upstream branch pipe  14 , respectively. 
         [0054]    Furthermore, as shown in  FIG. 8 , it is possible to detachably attach the syringe  28  to the upper branch pipe  13 . Said syringe  28  is equipped with the drug solution housing part  28   b  which houses a drug solution or the like and the male luer part  28   a  which has a narrow diameter and is cylindrical in shape, and it is possible for the male luer part  28   a  to link the inside of the drug solution housing part  28   b  and the flow channel  13   a  of the upper branch pipe  13  in communication, by means of the insertion of the male luer part  28   a  inside the slit  23  of the rubber stopper  20 . When said male luer part  28   a  is inserted inside the slit  23  of the rubber stopper  20 , the male luer part  28   a  presses against the rubber stopper main body  21  at the inner peripheral surface of the joining member  17 , and while moving it opens out the slit  23 . 
         [0055]    At this time, the joining part of the rubber stopper main body  21  and the fixing piece  22  turns around from upwards to downwards and extends. By virtue of this, the rubber stopper main body  21  is held down at the joining member  17  by means of the push-pressure force of the male luer part  28   a , and it descends to a state in which it is in close contact with the inner peripheral surface of the joining member  17 . Then, when the male luer part  28   a  is inserted inside the slit  23  and is linked in communication with the inside of the chamber part  11 , as shown in  FIG. 5 , the lower surface of the rubber stopper main body  21  becomes a level surface. Furthermore, there is close contact between the inner peripheral surface of the joining member  17  and the rubber stopper main body  21 , and between the male luer part  28   a  and the peripheral surface of the slit  23  due to the elastic force of the rubber stopper  20 . 
         [0056]    Consequently, as shown in  FIG. 6 , the upstream branch pipe  14  and the downstream branch pipe  12  are caused to be linked in communication, and while the drug solution or the like flows from the upstream branch pipe  14  side towards the downstream branch pipe  12  side, other drug solutions or the like from the syringe  28  can be mixed with said drug solution or the like, as shown in  FIG. 8 . Furthermore, in a state in which there is a block between the inside of the chamber part  11  and the upstream branch pipe  14 , other drug solutions or the like can flow from the syringe  28  to the downstream branch pipe  12 . 
         [0057]    With this configuration, in the case where two types of drug solution are supplied inside the body of the patient (not shown in the figures), the rear end part of an infusion tube (not shown in the figures) to which is connected an indwelling needle which is made to pierce the patient and remain there is firstly connected to the downstream branch pipe  12 . Next, the male luer part provided at the tip end part of the infusion tube which extends from a container or the like housing one of the drug solutions to be supplied to the patient is connected to the upstream branch pipe  14 . Next, in a state in which another drug solution is sucked inside the drug solution housing part  28   b  of the syringe  28 , the male luer part  28   a  is made to penetrate the slit  23  of the rubber stopper  20 . 
         [0058]    Then, the drug solution passes inside the infusion line which includes the chamber part  11 , and after all the air inside the infusion line has been expelled to the outside, and in a state in which the indwelling needle is made to pierce the patient&#39;s body and remain there, the drug solution is supplied to the patient by sending the drug solution in the container or the like to the patient. Furthermore, the drug solution inside the drug solution housing part  28   b  of the syringe  28  is also appropriately injected inside the chamber part  11  via the flow channel  13   a  of the upper branch pipe  13 . When the air inside the infusion line in this case is expelled to the outside, the lower surface of the rubber stopper main body  21  becomes a level surface, and the inner peripheral surface of the joining member  17  and the rubber stopper main body  21 , and the male luer part  28   a  and the peripheral surface of the slit  23  respectively reach a state of close contact. 
         [0059]    Consequently, locations where air remains are unlikely to be created inside the chamber part  11 . In other words, air is unlikely to remain in any of the space parts inside the chamber part  11  because these have become the flow channel for the drug solution. By virtue of this, the phenomenon of air being mixed in with the drug solution which is supplied to the patient is suppressed. Then, when the supply of drug solution from the syringe  28  is finished, and the male luer part  28   a  is withdrawn from the slit  23 , the push-pressuring from the male luer part  28   a  on the rubber stopper main body  21  is released, and also the state shown in  FIG. 4  is returned to due to the restoring force of the fixing piece  22 . Furthermore, thanks to this fluid mixture delivery instrument A the inside of the upper branch pipe  13  is closed off by the rubber stopper  20 , and therefore it is possible to suppress the phenomenon of air entering the chamber part  11 , and bacteria propagating. 
         [0060]    In this way, with the fluid mixture delivery instrument A pertaining to this mode of implementation, when the male luer part  28   a  is inserted into the slit  23  and the syringe  28  is linked in communication with the chamber part  11 , the lower surface of the rubber stopper main body  21  which is pushed inside the joining member  17  becomes a roughly level surface in a state in which it is in close contact with the inner peripheral surface of the joining member  17 . Consequently, there are no longer any space parts where air might remain between the lower surface of the rubber stopper main body  21 , the inner peripheral surface of the joining member  17  and the rubber stopper main body  21 , and between male luer part  28   a  and the peripheral surface of the slit  23 . As a result, it is possible to suppress the need for the troublesome operation for removing air inside the chamber part, and to suppress the generation of bacteria inside the chamber part. 
         [0061]    Furthermore, with the fluid mixture delivery instrument A, when the rubber stopper main body  21  moves vertically, the joining member  17  which is in contact therewith forms a roughly cylindrical shape in which the lower part side portion diameter is larger and the upper part side portion diameter is smaller, and therefore when the rubber stopper main body  21  is pushed onto the lower part side of the joining member  17 , it descends while deforming so as to expand in the horizontal direction. Consequently, the movement distance of the rubber stopper main body  21  becomes smaller, and the length of extension of the joining part of the rubber stopper main body  21  and the fixing piece  22  also becomes smaller. As a result, the fixing piece  22  etc. is not subjected to any excessive force, and it is possible to prevent damage to the rubber stopper  20 . Furthermore, the amount of deformation of the rubber stopper main body  21  is also small, and also the lower surface of the rubber stopper main body  21  readily becomes a level surface when it descends. In addition, the upper branch pipe  13  is configured by the joining aperture edge part  16  which is integrally formed with the chamber part  11  and the joining member  17  which is attached to the joining aperture edge part  16 , and therefore the upper branch pipe is easily produced. 
       (Second Mode of Implementation) 
       [0062]      FIG. 9  and  FIG. 10  show a fluid mixture delivery instrument B pertaining to a second mode of implementation of the present invention. With this fluid mixture delivery instrument B, the thickness of a lower end peripheral edge part  47   a  which is formed with a roughly annular shape on a joining member  47  is set to be less than the thickness of the lower end peripheral edge part  17   a  of the joining member  17 . Furthermore, an annular ceiling part  46   a  curves and extends obliquely downwards and inwards from the upper end part of the upper part  46  of a cover member  45 , and an engagement piece  46   b  whose thickness is set to be greater than that of the abovementioned engagement piece  26   b  extends downwards at its tip end. The upper surface of the rubber stopper main body  41  in the rubber stopper  40  is formed as a curved surface with the central part sinking downwards, and the lower surface of the rubber stopper  40  is formed as a curved surface in which the central part curves upwards with greater curvature than the upper surface. 
         [0063]    Consequently, the rubber stopper main body  41  is formed roughly disc-shaped with a thick peripheral edge part and a thin central side, an upper fixing piece  42  is formed in the upper part side portion on the outer peripheral surface of the rubber stopper main body  41 , and a long lower fixing piece  43  is formed to extend downwards to the lower end outer peripheral part of the rubber stopper main body  41 . Then, the lower fixing piece  43  of the rubber stopper  40  is fixed, along with a lower end peripheral edge part  47   a  of a joining member  47 , by insertion between a joining aperture edge part  44  and an auxiliary joining part  44   a . Furthermore, the upper fixing piece  42  of the rubber stopper  40  is fixed by an engagement piece  46   b  of the cover member  45  and an upper end part of the joining member  47 . The configuration of the other parts of this fluid mixture delivery instrument B is the same as that of the fluid mixture delivery instrument A which has been described above. Accordingly, a description of identical components having identical references will be omitted. 
         [0064]    Because this configuration is adopted, when the male luer part  28   a  is inserted inside the slit  23  of the rubber stopper  40 , the male luer part  28   a  presses against the rubber stopper main body  41  on the inside of the joining member  47 , and while moving it opens out the slit  23 . At this time, the rubber stopper main body  41  moves downwards, while the upper fixing piece  42  is made to extend, and also the lower fixing piece  43  is made to contract. Then, when the male luer part  28   a  is inserted inside the slit  23  and it is linked in communication with the inside of the chamber part  11 , the lower surface of the rubber stopper main body  41  becomes a level surface, as shown in  FIG. 10 . 
         [0065]    In other words, this is because when said rubber stopper main body  41  is also push-pressured downwards inside the upper branch pipe  13  by means of the male luer part  28   a  and when the male luer part  28   a  is inserted inside the slit  23 , the lower surface is preformed to become a level surface. Furthermore, a state of close contact due to the elasticity of the rubber stopper  40  is reached between the upper end part of the joining member  47  and the rubber stopper main body  41 , and the male luer part  28   a  and the peripheral surface of the slit  23 . According to this fluid mixture delivery instrument B, a space part in which air might remain is unlikely to be produced on the lower surface of the rubber stopper main body  41 , and therefore it is possible to suppress the need for the troublesome operation for removing air inside the chamber part  11 , and to suppress the generation of bacteria inside the chamber part. 
         [0066]    Furthermore, when the male luer part  28   a  is removed from the rubber stopper main body  41 , the rubber stopper main body  41  is returned to a position on the aperture part side of the joining member  47  due to the restoring force of both the upper fixing piece  42  and the lower fixing piece  43 , and the slit  23  is closed off due to the restoring force of the rubber stopper main body  41 . In this case, the rubber stopper main body  41  is supported by means of the upper fixing piece  42  and the lower fixing piece  43 , and therefore it is firmly supported. Other efficacious actions of this fluid mixture delivery instrument B are the same as those of the fluid mixture delivery instrument A described above. 
         [0067]    Furthermore, the fluid mixture delivery instrument pertaining to the present invention is not limited to the modes of implementation described above, but can be appropriately modified. For example, in the modes of implementation described above, a stopcock type device equipped with a valve body  30  is used as the fluid mixture delivery instrument, but a device may be used as the fluid mixture delivery instrument pertaining to the present invention which is not equipped with a valve body, but which allows the flow of drug solution or the like from the upstream branch pipe to the downstream pipe which is constantly linked in communication, and also which makes it possible for other drug solutions or the like to flow from the upper branch pipe to the chamber part. Furthermore, it is possible to use a fluid mixture delivery instrument which is not equipped with an upstream branch pipe, in which the branch pipes are configured by an upper branch pipe and a downstream branch pipe alone. 
         [0068]    Furthermore, in the first mode of implementation described above, the fixing piece  22  of the rubber stopper  20  is formed with a roughly cylindrical shape which is formed around the rubber stopper main body  21 , but said fixing piece  22  may be configured by two or more linear or band-shaped members which are arranged to maintain a gap on the peripheral surface of the rubber stopper main body. Similarly, the upper fixing piece  42  and the lower fixing piece  43  in the second mode of implementation may also be configured by a plurality of linear or bandshaped members. 
         [0069]    With the fluid mixture delivery instrument of one embodiment of the present invention configured in the manner described above, when a connection pipe, the male luer part of a syringe, for example, is inserted into the slit of the rubber stopper main body and the connection pipe links in communication with the chamber part, if the rubber stopper main body is pushed inside the upper branch pipe by means of the connection pipe, the lower surface of the rubber stopper main body which is positioned inside the upper branch pipe becomes a roughly level surface in a state in which it is in close contact with the inner peripheral surface of the upper branch pipe. Consequently, it is unlikely for a space part to be produced in which air can remain between the lower surface of the rubber stopper main body and the inner peripheral surface of the upper branch pipe, and the rubber stopper main body and the inner peripheral surface of the upper branch pipe. 
         [0070]    In other words, no unevenness is produced on the lower surface of the rubber stopper main body, and therefore when a drug solution or the like flows inside the chamber part, the drug solution or the like goes through the whole portion of the space part inside the chamber part. Consequently, it is possible to suppress the phenomenon of air remaining inside the chamber part. As a result, it is no longer necessary to carry out the troublesome operation needed to remove the air inside the chamber part, and also it is possible to suppress the generation of bacteria inside the chamber part. Furthermore, when the supply of a drug solution or the like has finished and the connection pipe is taken out from the rubber stopper main body, the rubber stopper main body returns to its original position by means of the restoring force of the fixing piece, and the slit is closed off by means of the restoring force of the rubber stopper main body. 
         [0071]    Moreover, the plurality of branch pipes pertaining to one embodiment of the present invention constitute pipes which are provided with fluid flow channels which respectively extend from the chamber part, and they are configured by the upper branch pipe and one other pipe or a plurality of other pipes. Furthermore, no provision is made for a valve body, or a stopcock type device which is provided with a valve body for linking prescribed branch pipes in communication, or for blocking them, and it is possible to use, as the fluid mixture delivery instrument, an instrument of the type in which drug solutions or the like are allowed to flow between branch pipes which are always linked in communication. 
         [0072]    Furthermore, other features of one configuration of the fluid mixture delivery instrument pertaining to the present invention lie in the fact that the fixing piece of the rubber stopper is fixed to the aperture part side of the upper branch pipe. By virtue of this, when the supply of a drug solution or the like has finished and the connection pipe is taken out from the rubber stopper main body, the rubber stopper main body returns to a position on the aperture part side of the upper branch pipe by means of the restoring force of the fixing piece, and therefore the aperture part of the upper branch pipe can be reliably closed off. 
         [0073]    Furthermore, other additional features of one configuration of the fluid mixture delivery instrument pertaining to the present invention lie in the fact that the fixing piece of the rubber stopper is configured by an upper fixing piece which is fixed to the aperture part side of the upper branch pipe, and a lower fixing piece which is fixed to the inside of the upper branch pipe. By virtue of this, when the rubber stopper main body is pushed inside the upper branch pipe, the upper fixing piece extends and the lower fixing piece contracts. Consequently, when the connection pipe is taken out from the rubber stopper main body, the rubber stopper main body returns to a position on the aperture part side of the upper branch pipe by means of the restoring force of both the upper fixing piece and the lower fixing piece, and the slit is closed off by means of the restoring force of the rubber stopper main body. In this case, the rubber stopper main body is supported by means of the upper fixing piece and the lower fixing piece, and therefore firm attachment is possible. 
         [0074]    Furthermore, other additional features of one configuration of the fluid mixture delivery instrument pertaining to the present invention lie in the fact that the upper branch pipe forms a roughly cylindrical shape in which the diameter on the chamber part side portion is larger, and the diameter on the aperture side is smaller, and when the rubber stopper main body is pushed inside the upper branch pipe, it descends while deforming so as to expand in the horizontal direction. 
         [0075]    When the connection pipe is inserted into the slit of the rubber stopper and the rubber stopper main body is pushed inside the upper branch pipe, the fixing piece or the portion around the joining part between the fixing piece and the rubber stopper main body extends, but it is possible for the movement distance of the rubber stopper main body to be made smaller due to the fact that the diameter of the chamber part side of the upper branch pipe, in other words the inside, is made larger. Consequently, the length by which the fixing piece or the portion around the joining part extends is also made smaller, and no excessive force is exerted on the fixing piece or the portion around the joining part. By virtue of this, the rubber stopper is unlikely to be damaged. Furthermore, the rubber stopper main body does not undergo any more than slight deformation, and also the lower surface of the rubber stopper main body can easily be made a level surface when it is pushed inside the upper branch pipe. 
         [0076]    Furthermore, other additional features of one configuration of the fluid mixture delivery instrument pertaining to the present invention lie in the fact that the upper branch pipe is configured by a joining aperture edge part which is formed integrally with the chamber part and a roughly cylindrical separating member which is attached to the joining aperture edge part. By virtue of this, it is easy to produce a roughly cylindrical upper branch pipe with a large diameter in the chamber part side portion, and a small diameter on the aperture part side. 
         [0077]    Furthermore, other additional features of one configuration of the fluid mixture delivery instrument pertaining to the present invention lie in the fact that a valve body which links in communication with an arbitrary branch pipe from among the abovementioned plurality of branch pipes by means of the movement of said valve body inside the chamber part is arranged inside the abovementioned chamber part. By virtue of this, it is possible to arbitrarily switch the state of linking in communication or blocking of each of the infusion tubes which are joined to the fluid mixture delivery instrument. Furthermore, the movement of said valve body involves rotation in the axial direction and movement in the axial direction.