Patent Publication Number: US-2007112246-A1

Title: Tubular member and endoscopic instrument

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a tubular member which is used with an endoscope in an endoscopic surgery, and also relates to an endoscopic instrument having the tubular member.  
      2. Description of the Related Art  
      In endoscopic surgery, an endoscopic instrument of which a treatment portion such as a forceps or the like is disposed on a distal end of a sheath is used. For example, in Japanese Unexamined Patent Application, First Publication No. 2000-52029, a connecting member which connects the treatment portion of the endoscopic instrument with the distal end of the sheath is disclosed.  
      Depending on the type of surgery, in order to change the flexibility of the sheath on the way of the sheath, it is performed that one sheath is connected to another sheath which differs from the one sheath. For example, in Japanese Utility Model Application, First Publication No. H05-15914, an endoscopic instrument which includes the different sheaths connected to each other is disclosed.  
     SUMMARY OF THE INVENTION  
      A tubular member of the present invention is formed like a tube, and is connected to an end of a sheath. The tubular member includes: a main body portion; a sheath receiving portion which is disposed at at least one end of the main body portion, and which is engaged with the inside or the outside of the end of the sheath; and a sheath connecting portion which is disposed between the main body portion and the sheath receiving portion, and which is fixed to the end of the sheath. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a view showing the construction of an endoscopic instrument of the first embodiment.  
       FIG. 2  is a partial cross-sectional view showing the construction of a tubular member, and showing a state in which adjacent sheaths are connected to each other.  
       FIG. 3  is a side view showing a state in which the sheath and a tubular member are connected when the sheath is bent.  
       FIG. 4  is a partial cross-sectional view showing a first variant relative to the tubular member and a method for connecting the sheaths of this embodiment.  
       FIG. 5  is a side view showing a state in which the sheath and a tubular member are connected when the sheath is bent.  
       FIG. 6  is a view showing the construction of an endoscopic instrument of the second embodiment.  
       FIG. 7  is a partial cross-sectional view showing the construction of a tubular member, and showing a state in which a treatment portion and a sheath are connected to each other.  
       FIG. 8  is a partial cross-sectional view showing a first variant relative to the tubular member and a method for connecting the sheaths of this embodiment.  
       FIG. 9  is a partial cross-sectional view showing a second variant relative to the tubular member and a method for connecting the sheaths of this embodiment.  
       FIG. 10  is a partial cross-sectional view showing a third variant relative to the tubular member and a method for connecting the sheaths of this embodiment.  
       FIG. 11  is a partial cross-sectional view showing a fourth variant relative to the tubular member and a method for connecting the sheaths of this embodiment.  
       FIG. 12  is a partial cross-sectional view showing a fifth variant relative to the tubular member and a method for connecting the sheaths of this embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First Embodiment  
      An endoscopic instrument of a first embodiment is shown in  FIG. 1 . As shown in  FIG. 1 , the endoscopic instrument I includes: an operation portion  2  which is operated by an operator; a first sheath  3  which extends from the operation portion  2 ; a second sheath  4  which extends from a distal end  3   a  of the first sheath  3 ; a treatment portion  5  which is disposed on a distal end  4   a  of the second sheath  4 ; and a tubular member  6  which connects the first sheath  3  and the second sheath  4 .  
      The first sheath  3  and the second sheath  4  are formed like a tube, external diameters thereof are approximately 2 to 4 millimeters, and internal diameters thereof are approximately 0.5 to 3 millimeters. The first sheath  3  and the second sheath  4  are made of metal, and are formed in a coil-shape. Thus, the first sheath  3  and the second sheath  4  have flexibility. The first sheath  3  is a flat coil sheath which is formed by winding a plate-shaped wire rod like a coil, and the second sheath  4  is a round coil sheath which is formed by winding a round wire rod like a coil. Since the shape and thickness of the wire rod of the first sheath  3  differ from that of the second sheath  4 , the bending flexibility is different relatively. Therefore, the second sheath  4  is able to bend easily.  
      The treatment portion  5  is a clip, including: a clip main body  5   c ; a cover  5   d  which is formed like a tube; and an operating wire  5   e . Two hook portions  5   a  are formed on each end of the clip main body  5   c , and the clip main body  5   c  is bent so that a ring portion  5   b  is formed on a proximal end of the treatment portion  5   c . The operating wire  5   e  is inserted into the cover  5   d , and is connected to the ring portion  5   b  of the clip main body  5   c . The diameter of the ring portion  5   b  is set so as to be larger than the internal diameter of the cover  5   d . The cover  5   d  is able to be attached to the second sheath  4  so as to insert the second sheath  4  into a proximal end of the cover  5   d . The operating wire  5   e  is inserted into the first sheath  3  and the second sheath  4 , and is connected to the operation portion  2  which is disposed on a proximal end  3   b  of the first sheath  3 .  
      As shown in  FIG. 1 , the operation portion  2  includes a holding portion  2   a  and a slider  2   b  which is able to move along the holding portion  2   a  in an axis direction of the holding portion  2   a . The operating wire  5   e  is connected to the slider  2   b . When the slider  2   b  is pulled toward a proximal end of the holding portion  2   a , the ring portion  5   b  of the treatment portion  5  is drawn into the cover  5   d , thus the ring portion  5   b  is contracted corresponding to the internal diameter of the cover  5   b . Therefore, the hook portions  5   a  arranged at both ends of the clip main body  5   c  are closed. As a result, it is possible to nip a predetermined part with the hook portions  5   a.    
      As shown in  FIG. 2 , the tubular member  6  is formed in a tube-shape approximately, and is made of metal. The tubular member  6  includes: a main body portion  7  which is disposed between the first sheath  3  and the second sheath  4  so that an axis of the main body portion  7  matches that of the first sheath  3  and the second sheath  4 ; a first sheath receiving portion  8  and a first sheath connecting portion  10  which are disposed on a proximal end portion of the main body portion  7 ; and a second sheath receiving portion  9  and a second sheath connecting portion  11  which are disposed on a distal end portion of the main body portion  7 .  
      The first sheath receiving portion  8  is engaged inside of the first sheath  3 , and the first sheath connecting portion  10  is disposed between the main body portion  7  and the first sheath receiving portion  8 . The second sheath receiving portion  9  is engaged inside of the second sheath  4 , and the second sheath connecting portion  11  is disposed between the main body portion  7  and the second sheath receiving portion  9 . The external diameter of the first sheath receiving portion  8  is substantially equal to the internal diameter of the first sheath  3 , and is set so as to be removably attached in the axial direction with ease. Similarly, the external diameter of the second sheath receiving portion  9  is equal to the internal diameter of the second sheath  4 , and is set so as to be removably attached in the axial direction with ease.  
      A step portion  10   a  which contacts the distal end  3   a  of the first sheath  3  engaged with the first sheath receiving portion  8  is formed on the first sheath connecting portion  10 . Similarly, a step portion  11   a  which contacts a proximal end  4   b  of the second sheath  4  is formed on the second sheath connecting portion  11 . The first sheath  3  and the tubular member  6  which are made of metal are heated at the first sheath connecting portion  10 , and are connected to each other by forming a welding portion  12  so as to weld the first sheath  3  and the tubular member  6  in a circumferential direction using a laser beam. Similarly, the second sheath  4  and the tubular member  6  are heated at the second sheath connecting portion  11 , and are connected by forming a welding portion  13  so as to weld the second sheath  4  and the tubular member  6  in a circumferential direction using a laser beam. Note that, the length in an axial direction of the first sheath receiving portion  8  and the first sheath connecting portion  10  which are engaged with the first sheath  3 , and the length in an axial direction of the second sheath receiving portion  9  and the second sheath connecting portion  11  which are engaged with the second sheath  4 , are approximately 1 to 5 millimeters.  
      Next, the action of this embodiment will be explained.  
      As shown in  FIG. 2 , the distal end  3   a  of the first sheath  3  is fixed to the first sheath connecting portion  10  of the tubular member  6  by the welding portion  12  so as to prevent the first sheath  3  from separating from the sheath connecting portion  10  in an axial direction. Further, the first sheath  3  is supported in a radial direction so as to oppose bending by the first sheath receiving portion  8  of the tubular member  6 , which is closer to a proximal end of the tubular member  6  than the welding portion  12 . Similarly, the proximal end  4   b  of the second sheath  4  is fixed to the second sheath connecting portion  11  of the tubular member  6  by the welding portion  13  so as to prevent the second sheath  4  from separating from the tubular member  6  in an axial direction. Further, the second sheath  4  is supported in a radial direction so as to oppose bending by the second sheath receiving portion  9  of the tubular member  6 , which is closer to a proximal end than the welding portion  13 .  
      In the endoscopic instrument  1 , for example, the first sheath  3 , the tubular member  6 , the second sheath  4  and the treatment portion  5 , which are connected as a single body as described above, are inserted into a channel of the endoscope, and used. At this time, the first sheath  3  and the second sheath  4 , which have flexibility, are bent, but the tubular member  6  is not bent. Thus, between the tubular member  6  and the first sheath  3 , and between the tubular member  3  and the second sheath  4 , an axial force which causes separation acts, and a bending action occurs. That is, in each of the first sheath  3  and the second sheath  4 , a stress caused by bending and a stress caused by separation are generated.  
      As shown in  FIG. 3 , for example, since the second sheath  4  is supported in the radial direction by the second sheath receiving portion  9 , the stress caused by bending is generated at a position  4   c  corresponding to a distal end  9   a  of the second sheath receiving portion  9  of the tubular member  6 . On the other hand, the stress caused by separation is generated at the welding portion  13  which fixes the proximal end  4   b  of the second sheath  4 . At this time, the second sheath  3  is not restricted in an axial direction at the second sheath receiving portion  9 , that is, the second sheath  3  is free to move along the second sheath receiving portion  9 . Accordingly, the spiral wire rod forming a coil extends due to the stress, and the second sheath  3  gets longer along the second sheath receiving portion  9 . As a result, the stress caused by bending is dispersed, and is diffused.  
      Similarly, in the first sheath  3 , as shown in  FIG. 2 , the stress caused by bending is generated at a position  3   c  corresponding to a distal end  8   a  of the first sheath receiving portion  8 , and the stress caused by separation is generated at the welding portion  12 . Further, the stress caused by bending is dispersed at the first sheath receiving portion  8 , and is diffused.  
      As described above, it is possible to move the positions at which the stress caused by bending and the stress caused by separation are generated, and it is possible to disperse the stress caused by bending and the stress caused by separation. Therefore, it is possible to prevent the first sheath  3  from bending deformation and rupturing at the position  3   c  corresponding to the proximal end  8   a  of the first sheath receiving portion  8 , and to prevent the second sheath  4  from bending deformation and rupturing at the position  4   c  corresponding to the distal end  9   a  of the second sheath receiving portion  9 .  
      Further, in the present embodiment, the first sheath  3  and the first sheath connecting portion  10  are connected by laser beam welding, and the second sheath  4  and the second sheath connecting portion  11  are also connected by laser beam welding. By this welding, it is possible to obtain high-strength and high-workability. On the other hand, since the laser beam welding follows heating, materials degenerate by heating in the welding portions  12  and  13  and the vicinity thereof, and accordingly the materials become fragile. However, since the stress caused by bending does not act on the welding portions  12  and  13  or the vicinity thereof, it is possible to obtain advantages using laser beam welding.  
      In addition, each of the step portions  10   a  and  11   b  is formed on the first sheath connecting portion  10  and the second sheath connecting portion  11 . Thus, since each of the distal end  3   a  of the first sheath  3  and the proximal end  4   b  of the second sheath  4  contacts the step portions  10   a  and  11   a , it is possible to engage the first sheath  3  with the first sheath receiving portion  8  reliably, and it is possible to engage the second sheath  4  with the second sheath receiving portion  9  reliably. In addition, since the step portions  10   a ,  11   a  are provided, an area in which the first sheath  3  and the first sheath connecting portion  10  are in contact and an area in which the second sheath  4  and the second sheath connecting portion  11  are in contact are expanded. As a result, it is possible to raise the connection-strength of the welding portions  12  and  13 .  
      As described above, it is possible for the tubular member  6  to reliably connect the above two sheaths without any as bending deformation or rupturing. Accordingly, it is possible to extend an insertion portion of the endoscopic instrument, and to change the flexibility and the material of the sheath according to the type of operation. Further, when the two coil-sheaths are connected as in the present embodiment, if each of the coil-sheaths is multiplexed, and if the number of wire rods of one of the coil-sheaths differs from that of wire rods of the other of the coil-sheath, it is possible to connect the two coil-sheaths easily.  
      In this embodiment, two sheaths are connected to each other through the tubular member  6 , however, this invention is not to be considered as limited by above. Three sheaths may be connected through a plurality of tubular members.  
      In  FIG. 4  and  FIG. 5 , a first variant of the present embodiment is shown. As shown in  FIG. 4 , in a tubular member  20  of this variant, the external diameter of a first sheath receiving portion  21  is set so as to be provided with a gap  23  between the first sheath  3  and the first sheath receiving portion  21 . Similarly, the external diameter of a second sheath receiving portion  22  is set so as to be provided with a gap  24  between the second sheath  4  and the second sheath receiving portion  22 . In detail, the size of each of the gaps  23  and  24  is set so as to be within 0.2 millimeters.  
      As shown in  FIG. 5 , in the tubular member  20  of this variant, the gap  24  is deformed so as to become closer, for example, when the second sheath  4  is bent. Therefore, it is possible to disperse the stress caused by bending at the position  4   c  of the second sheath  4  in the axial direction of the second sheath receiving portion  22 . Further, as shown in  FIG. 4 , it is possible to disperse the stress caused by bending at the position  3   c  of the first sheath  3  in the axial direction of the first sheath receiving portion  21 . Therefore, it is-possible to obtain a high reliability relative to-the bending deformation and the rupturing at the position  3   c  of the first sheath  3  and the position  4   c  of the second sheath  4 .  
     Second Embodiment  
      In  FIG. 6 , an endoscopic instrument of a second embodiment is shown. In this embodiment, the same components are given the same reference numerals used in the above embodiment, and an overlapping description thereof is omitted.  
      As shown in  FIG. 7 , an endoscopic instrument  30  of this embodiment includes: a sheath  31  which is equivalent to the insertion portion extended from the operation portion  2 ; a treatment portion  32  which is disposed on a distal end  31   a  of the sheath  31 ; and a tubular member  33  which connects the sheath  31  with the treatment portion  32 . The sheath  31  is made of metal, and is formed like a coil, and has flexibility.  
      As shown in  FIG. 7 , the treatment portion  32  is a biopsy forceps which includes: a pair of cups  32   c  which can be opened or closed around a shaft  32   a  as a center, and which is provided with a teeth portion  32   c ; a cover  32   d  which supports the shaft  32   a ; and an operating wire  32   e  which is connected to the pair of cups  32   c . The pair of cups  32   c  opens by moving forward the operating wire  32   e  in an axial direction, and closes by moving backward the operating wire  32   e  in the axial direction. As shown in  FIG. 6 , the operating wire  32   e  is inserted into the sheath  31 , and is connected to the slider  2   b  of the operation portion  2  which is disposed on a proximal end  31   b  of the sheath  31 . That is, when the slider  2   b  is moved forward on the holding portion  2   a  of the operation portion  2 , the operating wire  32   e  moves forward, and when the slider  2   b  is moved backward on the holding portion  2   a  of the operation portion  2 , the operating wire  32   e  moves backward. Therefore, it is possible to open or close the pair of cups  32   c.    
      As shown in  FIG. 7 , the tubular member  33  is formed like a tube, and is made of metal. The tubular member  33  includes: a main body portion  34  which is disposed between the sheath  31  and the treatment portion  32  so that an axis of the main body portion  34  matches that of the distal end  31   a  of the sheath  31 ; a sheath receiving portion  35  which is disposed on a proximal end portion of the main body portion  34  and which is engaged inside of the sheath  31 ; and a sheath connecting portion  36  which is disposed on the main body portion  34  and the sheath receiving portion  35 .  
      Further, a step portion  36   a  which contacts the distal end  31   a  of the sheath  31  engaged with the sheath receiving portion  35  is formed on the sheath connecting portion  36 . The sheath connecting portion  36  and the sheath  31  which are made of metal are heated at the sheath connecting portion  36 , and are connected by forming a welding portion  37  so as to weld the sheath connecting portion  36  and the sheath  31  in a circumferential direction using a laser beam.  
      A through hole  34   e  which penetrates the main body portion  34  from a side surface of the main body portion  34  in a radial direction is formed at a distal end of the main body portion  34 . The cover  32   d  is inserted into a distal end of the tubular member  33 , and has a through hole  32   f  which corresponds to the through hole  34   a  of the main body portion  34 . A pin  38  is inserted into the through hole  34   a  of the main body portion  34  and the through hole  32   f  of the treatment portion  32 . Therefore, the treatment portion  32  is fixed with the tubular member  33 .  
      Next, the action of this embodiment will be explained.  
      As shown in  FIG. 7 , the sheath  31  is fixed with the sheath connecting portion  36  by the welding portion  37  so as to prevent the sheath  31  from separating from the sheath connecting portion  36  in an axial direction. Further, the sheath  31  is supported in a radial direction so as to oppose bending by the sheath receiving portion  35  of the tubular member  33 , which is closer to a proximal end of the tubular member  33  than the welding portion  37 .  
      When the sheath  31  is bent, an axial force which causes separation is generated, and a bending action occurs, between the tubular member  33  and the sheath  31 . Therefore, a stress caused by bending and a stress caused by separation are generated in the sheath  3 . Since the sheath  31  is supported in the radial direction by the sheath receiving portion  35 , the stress caused by bending is generated at a position  31   c  corresponding to a proximal end  35   a  of the sheath receiving portion  35  of the tubular member  33 . On the other hand, the stress caused by separation is generated at the welding portion  37  which fixes the distal proximal end  31   a  of the sheath  31 . At this time, the sheath  31  is not restricted, and is free in an axial direction. Therefore, the sheath  31  being supported by the sheath receiving portion  35  is extended by the stress. As a result, the stress caused by bending is dispersed, and is diffused.  
      As described above, a position at which the stress caused by bending is generated differs from a position at which the stress caused by separation is generated, thus the stress caused by bending and the stress caused by separation are dispersed. Therefore, it is possible to prevent the sheath  31  from bending deformation and rupturing at the position  31   c  of the sheath  31  corresponding to the distal end  35   a  of the sheath receiving portion  35 . Since the stress caused by bending does not act on the welding portion  37  and the vicinity thereof, it is possible to obtain advantages using laser beam welding (that is, high-strength and high-workability). Further, since the step portion  36   a  is formed on the sheath connecting portion  36 , it is possible to reliably engage the sheath  31  with the sheath receiving portion  35  by contacting the sheath  31  and the step portion  36   a . Furthermore, since an area in which the sheath  31  and the sheath connecting portion  36  are in contact is expanded, it is possible to raise the connection strength of the welding portion  37 .  
      As described above, it is possible for the tubular member  33  to reliably connect the sheath  31  and the treatment device  32  without such bending deformation or rupturing. Note that, an example where the biopsy forceps is used as the treatment device  32  is given, however, this present invention is not limited to this. It is possible to use a kind of forceps such as a holding forceps and a clipping forceps instead of the biopsy forceps. Further, it is possible to reliably connect various treatment portions such as a high-frequency snare and a clip, using the tubular member  33 .  
      In  FIG. 8 , a first variant of the present embodiment is shown. As shown in  FIG. 8 , in this variant, a case in which an internal diameter of a sheath  39  is smaller than an external diameter of the sheath receiving portion  35  of the tubular member  33  is shown. A circumferential face of the sheath  39  is ground at a distal end  39   a  of the sheath  39 , and a diameter of the distal end  39   a  is set so as to engage the distal end  39   a  with the sheath receiving portion  35 . As to this, it is preferable to process the distal end  39   a  of the  25  sheath  39  so as to engage the tubular member with the sheath.  
      In  FIG. 9 , a second variant of the present embodiment is shown. As shown in  FIG. 9 , in this variant, there is not a step portion on a sheath connecting portion  41  of a tubular member  40 . However, in the tubular member  40 , a welding portion  42  is formed on the sheath connecting portion  41 . Therefore, advantages as described above can be obtained.  
      In  FIG. 10 , a third variant of the present embodiment is shown. As shown in  FIG. 10 , in this variant, an internal diameter of a sheath receiving portion  46  of a tubular member  45  is substantially equal with the external diameter of the first sheath  31 , and is set so as to be removably attached in axial direction with ease. Further, a step portion  47   a  of a sheath connecting portion  47  is formed inside. Therefore, the sheath receiving portion  46  is engaged with the outside of the sheath  31 , and the distal end  31   a  of the sheath  31  contacts the step portion  47   a . Further, in the sheath connecting portion  47 , the distal end  31   a  of the sheath  31  is discontinuously connected to the sheath receiving portion  46  at a plurality of locations in a circumferential direction, by laser-welding outside of the sheath connecting portion  47 . Therefore, a welding portion  48  is formed.  
      As described above, since the sheath receiving portion  46  of the tubular member  45  is engaged outside of the sheath  31 , advantages as described above can be obtained. Further, in this case, the welding portion  48  between the sheath  31  and the sheath connecting portion  47  of the tubular member  45  is inside of the sheath connecting portion  47 , however, both can be connected to each other by laser-welding outside of the sheath connecting portion  47 . Further, similarly to this variant, if the welding portion  48  has strength in the axial direction, the sheath  31  and the sheath connecting portion  47  may be discontinuously connected to each other in a circumferential direction, but continuously connecting.  
      In  FIG. 11 , a fourth variant of the present embodiment is shown. As shown in  FIG. 11 , in this variant, a sheath  50  and tubular member  51  are made of resin. A distal end  50   a  of the sheath  50  and a sheath connecting portion  52  are connected to each other through a welding portion  53  which is formed by ultrasonic welding. As described above, if the sheath  50  is made of resin, the tubular member  51  is also made of resin. Thus the sheath  50  and the tubular member  51  may be fixed to each other by welding. Further, when the sheath  50  is bent, a position  50   b  at which a stress caused by bending is generated may shift relative to the welding portion  53  in the axial direction. Therefore, the advantages as described above can be obtained.  
      In  FIG. 12 , a fifth variant of the present embodiment is shown. As shown in  FIG. 12 , in this variant, the distal end  50   a  of the sheath  50  is engaged outside of the sheath connecting portion  52  of the tubular member  51 , and a ring  54  which is made of metal is engaged outside of the distal end  50   a  of the sheath  50 . A rod is inserted inside of the sheath  50 , then the ring  54  is pressed toward the center of the sheath  50  from outside thereof, and plastically deformed. Therefore, the distal end  50   a  of the sheath  50  is fixed to the sheath connecting portion  52 . According to this fixing method, the advantages as described above can be obtained.  
      The contents of the embodiments as described above are not to be considered as limiting to each of embodiments, and they may be combined suitably. In each of the embodiments, connecting methods for connecting the distal end of the sheath to the sheath connecting portion of the tubular member are explained. However, this invention is not to be considered as limited to these connecting methods. The sheath and the tubular member may be fixed to each other at at least a limited area of the sheath connecting portion, while predetermined strength is obtained.