Patent Publication Number: US-2013245376-A1

Title: Tube assembly for endoscope and attaching method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a tube assembly for an endoscope and an attaching method. More particularly, the present invention relates to a tube assembly for an endoscope in which plural sections are connected to one another by use of inner and outer sleeves, and strength in attachment between the inner and outer sleeves with sealing material can be stable, and an attaching method for the tube assembly. 
     2. Description Related to the Prior Art 
     An endoscope is a medical instrument used widely for diagnosis and treatment. The endoscope includes an elongated tube assembly for entry in a body cavity, and a handle manually operated by a doctor or operator. The elongated tube assembly includes a tip device, a steering device and a flexible tube device. The tip device includes an imaging unit with an image sensor such as a CCD, CMOS sensor. The steering device includes a plurality of link elements connected in series. 
     Various internal elements are incorporated in the elongated tube assembly, including wire devices, a signal cable, a light guide device, an instrument channel, a fluid supply channel and the like. The wire devices are operable for pull in response to steering wheels on the handle. The signal cable is connected with the imaging unit. The instrument channel is used for entry of a treatment device. The fluid supply channel supplies air and water. Ends of the internal elements are fixedly mounted on the tip device. In the course of coupling the steering device to the flexible tube device, the internal elements are previously contained in those. If screws are used for connecting the steering device to the flexible tube device, elements such as anti-drop rings or seals for preventing drop of the screws are entered together, structurally to enlarge a diameter of the elongated tube assembly. The anti-drop rings may project radially to a considerable extent, and interfere with a wall of the body cavity in the course of the entry of the endoscope. 
     To solve the problem with the screws, JP-A 7-084192 discloses a connection structure without screws. A connector for connecting the tip device to the steering device is suggested, is disposed between a protection mesh or net of the steering device and an outer sleeve of the tip device, and includes an annular groove. The protection mesh covers an outer surface of the steering device, and has an end portion entered in the annular groove. The connector is fitted in the outer sleeve. Flow openings are formed in the outer sleeve. Flowing solder material as sealing material is injected through the flow openings for filling the annular groove to connect the tip device to the steering device firmly. 
     In JP-A 7-084192, the presence of the protection mesh between the connector and the outer sleeve reduces a distribution channel for the solder. It is impossible to check whether the annular groove is filled with the solder. A problem arises in that the strength of the soldering is uneven according to instability in a range of flow of the solder. The decrease in the strength due to the shortage of the sealing material occurs not only with the solder but also with an adhesive agent of a liquid state. Furthermore, fluidity of the flowing solder material should be maintained for the purpose of penetrating the solder through the protection mesh. A soldering iron must contact portions of the soldering. Heat generated by the soldering may damage the internal elements. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing problems, an object of the present invention is to provide a tube assembly for an endoscope in which plural sections are connected to one another by use of inner and outer sleeves, and strength in attachment between the inner and outer sleeves with sealing material can be stable, and an attaching method for the tube assembly. 
     In order to achieve the above and other objects and advantages of this invention, a tube assembly for an endoscope is provided, including a first section, and a second section disposed to extend from the first section to a proximal side in an axial direction. The tube assembly includes an inner sleeve. An outer sleeve receives one end portion of the inner sleeve in the axial direction, for connection of the second section to the first section. At least one flow opening is formed through the outer sleeve, and opposed to an outer wall surface of the inner sleeve upon receiving the inner sleeve in the outer sleeve. A distribution groove is formed in at least one of the outer wall surface of the inner sleeve and an inner wall surface of the outer sleeve, to extend from the flow opening according to a circumferential direction. At least one seal cavity is formed in at least one of the outer wall surface of the inner sleeve and the inner wall surface of the outer sleeve, to extend from the distribution groove to a sleeve end of the outer sleeve in an externally open form. Sealing material is supplied in the flow opening, charged in the distribution groove and the seal cavity, for attaching the outer sleeve to the inner sleeve. 
     The distribution groove is annular. 
     The distribution channel includes a first distribution groove formed in the outer wall surface of the inner sleeve. A second distribution groove is formed in the inner wall surface of the outer sleeve, and disposed in alignment with the first distribution groove upon mounting the inner sleeve in the outer sleeve. 
     The seal cavity includes a first seal cavity formed in the inner sleeve to extend from the first distribution groove in the axial direction. A second seal cavity is formed in the outer sleeve to extend along the first seal cavity from the second distribution groove to a sleeve end of the outer sleeve. 
     The first seal cavity includes an open end area disposed outside the sleeve end of the outer sleeve. 
     The distribution channel includes plural distribution channels arranged adjacently to one another in the axial direction. 
     In another preferred embodiment, the distribution channel is in a helical shape with plural turns. 
     In one preferred embodiment, the at least one flow opening is a plurality of flow openings formed in the outer sleeve and arranged substantially equidistantly in a circumferential direction thereof. 
     The at least one seal cavity is plural seal cavities of which a number is equal to or larger than a number of the flow opening. 
     The at least one flow opening is plural flow openings, and the seal cavities are offset from the flow openings in a circumferential direction of the outer sleeve. 
     In still another preferred embodiment, the seal cavities are aligned with the flow opening in the axial direction. 
     The first section is a steering device, and the second section is a flexible tube device. 
     The inner sleeve is disposed at an end of the steering device, and the outer sleeve is disposed at an end of the flexible tube device. 
     The steering device includes first to Nth link elements, arranged serially in the axial direction toward the flexible tube device, and connected with one another movably. The inner sleeve is the Nth link element. 
     Furthermore, a cover sleeve is mounted on at least the steering device, for covering the inner and outer sleeves. 
     Also, an attaching method for an endoscope having a tube assembly is provided, the tube assembly including a tip device having an internal element, a steering device, mounted on a proximal side of the tip device, for steering operation, and a flexible tube device disposed to extend from the steering device to a proximal side in an axial direction, wherein an inner sleeve is used to constitute a proximal end of the steering device, an outer sleeve is used to constitute a distal end of the flexible tube device, one end portion of the inner sleeve is receivable in the outer sleeve in the axial direction, for connection of the flexible tube device to the steering device. The attaching method includes a step of forming at least one flow opening through the outer sleeve, the flow opening being opposed to an outer wall surface of the inner sleeve upon receiving the inner sleeve in the outer sleeve. A distribution groove is formed in at least one of the outer wall surface of the inner sleeve and an inner wall surface of the outer sleeve, to extend from the flow opening according to a circumferential direction. At least one seal cavity is formed to extend from the distribution groove to a sleeve end of the outer sleeve in an externally open form upon receiving the inner sleeve in the outer sleeve. A cable and an elongated element are penetrated through the steering device and the flexible tube device in connection with the internal element. The inner sleeve is mounted in the outer sleeve upon penetrating the cable and the elongated element through the flexible tube device. After the mounting step, sealing material is supplied in the flow opening, to charge the distribution groove and the seal cavity with the sealing material. 
     The sealing material is flowing solder material. 
     Consequently, it is possible to keep strength in attachment between the inner and outer sleeves with sealing material in a stable state, because the sealing material can spread in the distribution channel and the seal cavity for tight contact. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the present invention will become more apparent from the following detailed description when read in connection with the accompanying drawings, in which: 
         FIG. 1  is a plan illustrating an endoscope; 
         FIG. 2  is a vertical section illustrating an elongated tube assembly; 
         FIG. 3  is a perspective view illustrating a solder joint; 
         FIG. 4  is a perspective view illustrating the solder joint in an assembled state; 
         FIG. 5  is a perspective view illustrating a state of the solder joint filled with solder; 
         FIG. 6  is a vertical section, partially broken, illustrating the same as  FIG. 5 ; 
         FIG. 7  is a perspective view illustrating another preferred solder joint having three distribution channels in an inner sleeve; 
         FIG. 8  is a vertical section, partially broken, illustrating the solder joint; 
         FIG. 9  is a perspective view illustrating one preferred solder joint having three helical distribution channels in an inner sleeve; 
         FIG. 10  is a vertical section, partially broken, illustrating the solder joint; 
         FIG. 11  is a perspective view illustrating still another preferred solder joint having four pairs of seal cavities; 
         FIG. 12  is a cross section illustrating the solder joint; 
         FIG. 13  is a perspective view illustrating a state of the solder joint filled with the solder; 
         FIG. 14  is a perspective view illustrating one preferred solder joint having two flow openings; 
         FIG. 15  is a cross section illustrating the solder joint; 
         FIG. 16  is a perspective view illustrating a state of the solder joint filled with the solder. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE PRESENT INVENTION 
     In  FIG. 1 , an endoscope  2  includes an elongated tube assembly  10  or insertion tube, a handle  11  and a universal cable  12 . The elongated tube assembly  10  is entered in a body cavity of a patient. The handle  11  is mounted on a proximal end of the elongated tube assembly  10 . The universal cable  12  extends from the handle  11 . A processing apparatus (not shown) is connected by the universal cable  12  with the endoscope  2 . The elongated tube assembly  10  includes a tip device  13 , a steering device  14  and a flexible tube device  15 . The steering device  14  is mounted on a proximal end of the tip device  13 , and bendable for steering. The flexible tube device  15  extends from a proximal end of the steering device  14 . The flexible tube device  15  is as long as several meters for reach of the tip device  13  to a target site in the body cavity. A solder joint  16  or connector connects the steering device  14  to the flexible tube device  15 . 
     An imaging unit is incorporated in the tip device  13 , and includes a lens system and an image sensor such as a CCD, CMOS sensor. Object light from an object in the body cavity is received through the lens system, and is detected by the imaging unit for imaging, to generate an image signal. A signal cable (not shown) is penetrated through the elongated tube assembly  10  and the handle  11 , and transmits the image signal from the image sensor a processing apparatus through the universal cable  12 . The processing apparatus processes the image signal in image processing of various functions. A monitor display panel (not shown) is driven by the processing apparatus to display the image. 
     At least one lighting window is formed in the tip device  13 . There is a light source apparatus (not shown) in connection with the universal cable  12 . In  FIG. 2 , the endoscope  2  has a wire coil  27  or winding, and a light guide device  28  extending through the wire coil  27 . The light guide device  28  guides light from the light source apparatus through the elongated tube assembly  10  and the handle  11 , and emits the light toward an object in the body cavity. 
     An instrument opening  17  is formed in the handle  11 , and used for penetration of a medical instrument for treatment, for example, forceps, injection needle and the like. An instrument channel  18  is formed through the elongated tube assembly  10 , and communicates with the instrument opening  17 . A distal instrument opening (not shown) is formed in the tip device  13 . The instrument channel  18  extends to the distal instrument opening. 
     A fluid supply button  19  and a suction button  20  are disposed on the handle  11 . A fluid channel (not shown) is formed through the elongated tube assembly  10 . The fluid supply button  19  is depressible for supply of air or water through the fluid channel. A nozzle (not shown) is formed in the tip device  13 . The air or water from the fluid channel is ejected by the nozzle. The suction button  20  is depressed for suction and discharge of body fluid or other waste fluid from the body cavity through the instrument channel  18 . 
     In  FIG. 2 , the steering device  14  includes a plurality of link elements  21  and pins  22 . The link elements  21 , for example 16 links, are connected serially by the pins  22  in a pivotally movable manner. A flexible cover sleeve  23  of rubber covers the link elements  21  for protection. A first one of the link elements  21  at a distal end is attached firmly to the tip device  13 . A proximal link element  31  is included in the link elements  21  in the steering device  14 , and constitutes an inner sleeve  32  of the solder joint  16 . A steering wheel  24  is disposed on the handle  11 , and is rotatable for bending the steering device  14  up and down. A steering wheel  25  on the handle  11  is rotatable for bending the steering device  14  to the right and left. The tip device  13  can be oriented in a desired direction in the body cavity. 
     The flexible tube device  15  includes a winding  35  of a strip  34  of metal, a mesh sleeve  36  and encapsulant  37 . The mesh sleeve  36  is constituted by mesh of wires of metal. The encapsulant  37  is disposed around the mesh sleeve  36  for encapsulation in a form of a jacket or sheath. The solder joint  16  has an outer sleeve  33 , to which the encapsulant  37  at an end of the flexible tube device  15  is connected in a fluid tight manner. 
     The solder joint  16  is described now by referring to  FIGS. 3-6 . A first distribution groove  41  or distribution channel is formed in the outer wall surface of the inner sleeve  32  and extends circumferentially in  FIG. 3 . A first seal cavity  42   a  or sub groove is formed in the inner sleeve  32 , and extends from the first distribution groove  41  in a direction (proximal) away from a sleeve end of the inner sleeve  32 . Also, first seal cavities  42   b ,  42   c  and  42   d  or sub grooves are formed in the inner sleeve  32  and arranged with the first seal cavity  42   a  equidistantly in relation to a circumferential direction. 
     A receiving surface  43  is formed inside the outer sleeve  33  between sections of large and small inner diameters. The sleeve end of the inner sleeve  32  becomes engaged with the receiving surface  43  when the inner sleeve  32  is mounted in the outer sleeve  33 . Also, a second distribution groove  44  or distribution channel is formed in an inner wall surface of the outer sleeve  33 , and extends circumferentially. 
     A flow opening  46  or gate is formed in the outer sleeve  33 . Flowing solder material  45  such as molten solder or solder paste (sealing material) is injected into the flow opening  46 . The flow opening  46  communicates with the second distribution groove  44 . A second seal cavity  47   a  or sub groove is formed in the outer sleeve  33 , and extends from the second distribution groove  44  to a sleeve end of the outer sleeve  33 . Also, second seal cavities  47   b ,  47   c  and  47   d  or sub grooves are formed in the outer sleeve  33 , and are arranged with the second seal cavity  47   a  equidistantly in relation to a circumferential direction. 
     An imaging unit is incorporated in the tip device  13 . Various elongated elements are penetrated through the steering device  14  and the flexible tube device  15 , including a signal cable from the imaging unit, the light guide device  28 , the instrument channel  18 , a fluid supply channel, a control wire and the like. 
     In  FIG. 4 , the inner sleeve  32  at the end of the steering device  14  and the outer sleeve  33  at the end of the flexible tube device  15  are combined together. The first distribution groove  41  is radially aligned with the second distribution groove  44  to define a distribution channel (one space). The first seal cavities  42   a - 42   d  are open to the outside with open end areas having a size OA in  FIG. 6 . A space between the inner and outer sleeves  32  and  33  is locally larger at the first and second distribution grooves  41  and  44 , and utilized for injection of the solder  45  in the circumferential direction. 
     The solder  45  is injected through the flow opening  46  into the first and second distribution grooves  41  and  44 , and then flows into the first seal cavity  42   a  and the second seal cavity  47   a . The solder  45  flows further in the circumferential direction in the first and second distribution grooves  41  and  44 , and comes in the first seal cavities  42   b  and  42   d  and the second seal cavities  47   b  and  47   d  as illustrated in  FIG. 5 . When the first and second distribution grooves  41  and  44  are filled with the solder  45  completely, the solder  45  enters the first seal cavity  42   c  and the second seal cavity  47   c  as illustrated in  FIG. 6 . 
     Thus, it is possible to check a condition of flow of the solder  45  into the first seal cavities  42   a - 42   d  and the second seal cavities  47   a - 47   d . Strength of soldering can be maintained. Also, fluidity of the solder  45  can be high in addition to higher stability in an amount of the solder  45 , because an area of flow of the solder  45  within the solder joint  16  is made large. It is unnecessary to apply a soldering iron (or hot bar apparatus) to the flow opening  46  for the purpose of increasing fluidity of the solder  45 . An increase in the temperature of the solder joint  16  due to the soldering iron can be prevented, so that damages to internal elements can be prevented. Even if the solder  45  moves away from the surfaces of the first and second distribution grooves  41  and  44 , the solder  45  in the solid state keeps the inner sleeve  32  on the outer sleeve  33  without drop, because the solder  45  keeps the first and second distribution grooves  41  and  44  positioned without offsetting. 
     Note that each of the first seal cavities  42   a - 42   d  has an open end area disposed outside the outer sleeve  33  with the size OA. However, the first seal cavities  42   a - 42   d  can be covered by the outer sleeve  33  without an open end area. 
     In  FIG. 7 , a second preferred tube assembly of the invention is illustrated. The first embodiment is repeated but with a difference in that an inner sleeve  51  has three first distribution grooves  52   a ,  52   b  and  52   c  or distribution channels in contrast with the first distribution groove  41  of the inner sleeve  32 . Elements similar to those of the first embodiment are designated with identical reference numerals. 
     In  FIG. 8 , annular projections  53  or wall ridges are defined between the first distribution grooves  52   a - 52   c . An outer sleeve  54  has the flow opening  46 . A height of the annular projections  53  is predetermined so that the flow opening  46  communicates with the first seal cavity  42   a . In the same manner as the first embodiment, the inner sleeve  51  is mounted in the outer sleeve  54 . The solder  45  is injected into the flow opening  46 , flows through the first distribution grooves  52   a - 52   c  and reaches the first seal cavities  42   a - 42   d.    
     Strength of soldering can be maintained, because an area of the contact with the solder  45  can be large with the shape of the first distribution grooves  52   a - 52   c . Also, the annular projections  53  of the first distribution grooves  52   a - 52   c  can function for reinforcement. A problem of a small strength may occur in the first embodiment in that walls are formed with a limited thickness under the first and second distribution grooves  41  and  44  of a predetermined depth, but the reinforcement of the annular projections  53  can solve the problem. The height of the annular projections  53  can be in such a range that the solder  45  can flow into the first seal cavities  42   a - 42   d  and the second seal cavities  47   a - 47   d . Also, an upper end of the annular projections  53  can contact an inner wall surface of the outer sleeve  54  in a state of entry of the inner sleeve  51  in the outer sleeve  54 . Furthermore, a cutout may be formed through a portion of the annular projections  53  for flow of the solder  45  in an axial direction, so that the first distribution grooves  52   a - 52   c  can communicate with one another in the axial direction. It is possible to change the number of the first distribution grooves  52   a - 52   c  and their interval. 
     In  FIG. 9 , a third preferred tube assembly of the invention is illustrated. The first embodiment is repeated but with a difference in that an inner sleeve  61  has a helical distribution groove  62  or distribution channel in contrast with the first distribution groove  41  of the inner sleeve  32 . 
     In  FIG. 10 , a helical projection  63  is defined between turns of the helical distribution groove  62  in a form of a helical thread. An outer sleeve  64  has the flow opening  46 . A height of the helical projection  63  is predetermined so as to communicate the flow opening  46  with the first seal cavity  42   a . In the same manner as the first embodiment, the inner sleeve  61  is combined with the outer sleeve  64 . The solder  45  is injected into the flow opening  46 , flows through the helical distribution groove  62  and reaches the first seal cavities  42   a - 42   d.    
     Thus, strength of soldering can be maintained, because an area of the contact with the solder  45  can be large with the shape of the helical distribution groove  62 . Fluidity of the solder  45  can be high because of the inclination of the helical distribution groove  62 . Also, the helical projection  63  of the helical distribution groove  62  can function for reinforcement. A problem of a small strength may occur in the first embodiment in that walls are formed with a limited thickness under the first and second distribution grooves  41  and  44  of a predetermined depth, but the reinforcement of the helical projection  63  can solve the problem. The sectional shape of the helical projection  63  may be quadrilateral or trapezoidal in a manner different from the shape according to the embodiment. Also, an upper end of the helical projection  63  may contact an inner wall surface of the outer sleeve  64  in the state of combining the inner sleeve  32  with the outer sleeve  33 . Furthermore, a cutout may be formed through a portion of the helical projection  63  for flow of the solder  45  in the axial direction. It is possible to change the number of the turns of the helical distribution groove  62  and their interval. 
     In the embodiment, the outer sleeve  64  has the second distribution groove  44 . However, the outer sleeve  64  may not have the second distribution groove  44 . 
     In  FIG. 11 , a fourth preferred embodiment is illustrated. The first embodiment is repeated but with a difference in that four flow openings  72   a ,  72   b ,  72   c  and  72   d  or gates are formed in an outer sleeve  71  equiangularly between those. An inner sleeve  74  is combined with the outer sleeve  71 . First seal cavities  75   a ,  75   b ,  75   c  and  75   d  or sub grooves are formed in the outside of the inner sleeve  74 . Second seal cavities  73   a ,  73   b ,  73   c  and  73   d  or sub grooves are formed between the flow openings  72   a - 72   d  inside the outer sleeve  71 . The first seal cavities  75   a - 75   d  are aligned with respectively the second seal cavities  73   a - 73   d  when the inner sleeve  74  is mounted in the outer sleeve  71 . Elements similar to those of the above embodiments are designated with identical reference numerals. 
     The inner sleeve  74  is mounted in the outer sleeve  71  by aligning the first seal cavities  75   a - 75   d  with respectively the second seal cavities  73   a - 73   d . In  FIG. 12 , the solder  45  is injected in the first and second distribution grooves  41  and  44  through the flow opening  72   a . The solder  45  flows circumferentially along the first and second distribution grooves  41  and  44  and then into the first seal cavities  75   a  and  75   d  and the second seal cavities  73   a  and  73   d.    
     Similarly, the solder  45  is injected into the flow opening  72   b  and flows into the first seal cavities  75   a  and  75   b  and the second seal cavities  73   a  and  73   b . The solder  45  is injected into the flow opening  72   c  and flows into the first seal cavities  75   b  and  75   c  and the second seal cavities  73   b  and  73   c . The solder  45  is injected into the flow opening  72   d  and flows into the first seal cavities  75   c  and  75   d  and the second seal cavities  73   c  and  73   d . In  FIG. 13 , the first and second distribution grooves  41  and  44  are filled with the solder  45  completely. 
     In the embodiment, the solder  45  is supplied in four times. Thus, a duration for soldering at each one of the four times is shorter than for soldering of all the solder  45  at one time. It is possible to prevent overheating internal elements with the solder  45 . It is possible to check the flow of the solder  45  through the open end areas of the first seal cavities  75   a - 75   d  and the second seal cavities  73   a - 73   d . Strength of the soldering can be high. 
     In  FIG. 14 , a fifth preferred embodiment is illustrated. The first embodiment is repeated but with a difference in that two flow openings  82   a  and  82   b  or gates are formed in an outer sleeve  81  symmetrically with reference to the axial direction. An inner sleeve  84  is disposed in the outer sleeve  81 . First seal cavities  85   a ,  85   b ,  85   c  and  85   d  or sub grooves are formed in an outer wall surface of the inner sleeve  84 . Second seal cavities  83   a ,  83   b ,  83   c  and  83   d  or sub grooves are formed in an inner wall surface of the outer sleeve  81 , extend from the second distribution groove  44  to a sleeve end of the outer sleeve  81 , and are arranged equidistantly. The first seal cavities  85   a - 85   d  are aligned with respectively the second seal cavities  83   a - 83   d . Elements similar to those of the above embodiments are designated with identical reference numerals. 
     The outer sleeve  81  is mounted on the inner sleeve  84  in the same manner as the above embodiments. In  FIG. 15 , the solder  45  is injected through the flow opening  82   a  into the first and second distribution grooves  41  and  44 . Then the solder  45  flows to the first seal cavity  85   a  and the second seal cavity  83   a  from the first and second distribution grooves  41  and  44 . The solder  45  comes to flow circumferentially through the first and second distribution grooves  41  and  44 , and enters the first seal cavities  85   b  and  85   d  and the second seal cavities  83   b  and  83   d.    
     The solder  45  is injected into the flow opening  82   b  and flows through the first and second distribution grooves  41  and  44  into the first seal cavity  85   c  and the second seal cavity  83   c . Also, the solder  45  flows circumferentially through the first and second distribution grooves  41  and  44 , and flows into the first seal cavities  85   b  and  85   d  and the second seal cavities  83   b  and  83   d . In  FIG. 16 , the first and second distribution grooves  41  and  44  are filled with the solder  45  completely. 
     In the embodiment, the solder  45  is supplied in two times. Thus, a duration for soldering at each one of the two times is shorter than for soldering of all the solder  45  at one time. It is possible to prevent overheating internal elements with the solder  45 . It is possible to check the flow of the solder  45  through the open end areas of the first seal cavities  85   a - 85   d  and the second seal cavities  83   a - 83   d . Strength of the soldering can be high. 
     The features of the above embodiments can be combined with one another in a suitable manner for the purpose. The number of the flow openings and seal cavities may be one, or two or more. The positions and arrangement of the flow openings and seal cavities may be changed suitably. 
     In the above embodiments, the distribution grooves are formed in the circumferential direction in the inner and outer sleeves. However, it is possible to form a plurality of distribution grooves shaped arcuately and arranged circumferentially, for example, two, three or four distribution grooves, according to the number of the flow openings. It is preferable to form seal cavities at ends of respectively the distribution grooves. The seal cavities are kept from clogging with solder overflowing from adjacent flow openings. Soldering can be checked reliably in the seal cavities. Also, a duration for soldering at one time can be shortened. The internal elements can be protected from damages even with heat from the soldering. 
     In the above embodiments, the steering device is connected to the flexible tube device by the solder joint. However, the feature of the invention can be used for connection between the tip device and the steering device, or between the flexible tube device and the handle, in a structure with the inner and outer sleeves. Also, the feature of the invention can be used for connection of one of the inner and outer sleeves to a proximal link element in the steering device, or to the mesh sleeve or the winding  35  of the strip  34 . 
     In contrast with the solder joint  16  described above, an outer sleeve can be used at the end of the steering device  14 , and an inner sleeve can be used at the end of the flexible tube device  15 , for soldering according to the invention. 
     In the above embodiments, the two sleeves are cylindrical. However, sleeves according to the invention may be shaped in a form of an elliptical cylinder, a polygonal prism, a frustum of a cone, and the like. 
     Also, first and second sleeves with an equal diameter may be used in place of the inner and outer sleeves. A sleeve end of the first sleeve can have a smaller diameter, and can be entered in the second sleeve. 
     In the embodiments, the sealing material is the flowing solder material  45 . However, the sealing material of the invention may be adhesive agent of a liquid state for attaching the inner sleeve to the outer sleeve, or filler, sealant or the like. 
     Although the present invention has been fully described by way of the preferred embodiments thereof with reference to the accompanying drawings, various changes and modifications will be apparent to those having skill in this field. Therefore, unless otherwise these changes and modifications depart from the scope of the present invention, they should be construed as included therein.