Abstract:
A transmission device for transmitting a force and a torque between a handling device and a tool of a medical instrument includes transmission members interconnected in a hinged manner. A convex coupling portion of a first transmission member is in each case held interlockingly in a concave coupling portion of an adjacent second transmission member in such a way that a rotation of the first transmission member about its longitudinal axis causes a rotation of the second transmission member about its longitudinal axis. A convex coupling portion of a first transmission member is in each case held interlockingly in a concave coupling portion of an adjacent second transmission member in such a way that a tensile force can be transmitted between the first transmission member and the second transmission member.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a transmission device for transmitting a force and a torque between a handling device and a tool of a medical instrument, and to a method for producing a transmission device. 
     BACKGROUND OF THE INVENTION 
     The expectations placed on medical instruments for microinvasive interventions are constantly increasing. A variety of medical instruments comprising a tool with a gripping or cutting function at the distal end, wherein the tool is rotatable about the longitudinal axis of the shaft, are already available and in widespread use. The gripping function or cutting function and the rotation of the tool can be controlled for example by means of a single transmission rod that transmits longitudinal forces and torques. In addition, a possibility of angling the shaft at a hinge arranged to the proximal side of the tool has been provided more recently. This presupposes a flexibility of the transmission rod in the region of the hinge. 
     An angle drive device with a multiplicity of movement transmission segments engaging with one another is described in DE 39 23 609 A1. Each movement transmission segment comprises a head portion and a socket portion with a polygonal cross section in each case. The head portion of a movement transmission segment engages in a socket portion of an adjacent movement transmission segment. However the angle drive device does not enable any transmission of tensile forces. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to create an improved transmission device for transmitting a force and a torque between a handling device and a tool of a medical instrument, an improved tool for a medical instrument, an improved medical instrument, and an improved method for producing a transmission device. 
     This object is achieved by the subjects of the independent claims. 
     Developments are specified in the dependent claims. 
     A transmission device for transmitting a force and a torque between a handling device and a tool of a medical instrument comprises transmission members interconnected in a hinged manner, wherein a convex coupling portion of a first transmission member is in each case held interlockingly in a concave coupling portion of an adjacent second transmission member in such a way that a rotation of the first transmission member about its longitudinal axis causes a rotation of the second transmission member about its longitudinal axis, wherein a convex coupling portion of a first transmission member is in each case held interlockingly in a concave coupling portion of an adjacent second transmission member in such a way that a tensile force can be transmitted between the first transmission member and the second transmission member. 
     The transmission device is designed in particular for a medical instrument for microinvasive surgical interventions and has a shaft between the handling device and tool. The transmission device is provided and designed to transmit a torque and to transmit both compressive forces and tensile forces in the shaft. The transmission members connected in a hinged manner are provided and designed in particular to be arranged in a curved or curvable or flexible or resilient region of the shaft. 
     So that a rotation of a first transmission member about its longitudinal axis causes a rotation of a second transmission member about its longitudinal axis, the transmission members are coupled to one another in particular in a torsionally rigid manner or are coupled to one another in a manner suitable for the transmission of torques. In particular, the convex coupling portion of a transmission member and the concave coupling portion of an adjacent transmission member each have corresponding polygonal cross sections, for example hexagonal cross sections. 
     By means of a transmission device having the described features, not only can torques and compressive forces be transmitted, but also tensile forces. For example, this may make it possible to control a rotation and both an opening and a closing of jaw parts of a tool at the distal end of a shaft that can be curved or angled, as is already known from medical instruments with a rigid, straight shaft. 
     In a transmission device as is described here, in particular a first retaining region is provided on the convex coupling portion of a first transmission member and a second retaining region is provided on the concave coupling portion of an adjacent second transmission member, and the first retaining region and the second retaining region are interlockingly interconnected so as to take up a tensile force between the first transmission member and the second transmission member. 
     In a transmission device as is described here, and relative to a sectional plane containing the longitudinal axis of the first transmission member, the first retaining region in particular is adjacent to a concave region of the contour of the transmission member, wherein the second retaining region has a substantially convex contour. 
     The contour of the first retaining region itself in the sectional plane is convex in particular. The second retaining region may have a sliding face, of which the form is matched to the form of the surface of the first retaining region or corresponds thereto. The substantially convex contour of the second retaining region can be concave in the region of the sliding face. 
     In a transmission device as is described here, the first retaining region on the first transmission member is formed in particular by the edge of a groove, wherein the second retaining region on the second transmission member has the form of a collar, which engages in the groove on the first transmission member. 
     The groove is in particular a peripheral, radially outwardly open groove occupying the entire periphery of the first transmission member (in particular in a plane perpendicular to the longitudinal axis thereof). The groove in particular forms the above-mentioned concave region of the contour of the first transmission member in the sectional plane containing the longitudinal axis. The first retaining region is formed in particular by a shoulder-shaped region on the first transmission member, which simultaneously is an edge region or a flank of the groove. The second retaining region on the second transmission member in particular has the form of a peripheral, substantially closed and radially inwardly protruding collar. The collar in particular has the form of a complete or almost complete circular ring. 
     In a transmission device as is described here, the first retaining region is formed in particular by a taper of the first transmission member on a side, facing away from the second transmission member, of the convex coupling portion of the first transmission member. 
     In a transmission device as is described here, a sleeve, which surrounds the concave coupling portion, in particular forms the radially inwardly protruding collar. 
     The provision of the radially inwardly protruding collar on a sleeve may enable a cost-effective manufacturing process, in which for example the convex coupling portion for a first transmission member is initially arranged in the sleeve and is then joined to the first transmission member, whereupon the sleeve is joined to the second transmission member. 
     In a transmission device as is described here, the sleeve in particular comprises a slit, which is parallel to the longitudinal axis of the second transmission member. 
     In a transmission device as is described here, the first retaining region on the first transmission member is formed in particular by a taper of the first transmission member on a side, facing away from the second transmission member, of the convex coupling portion, wherein the slit in the sleeve has a width that is no smaller than a minimum width of the taper. 
     The convex coupling portion can be formed in one piece with other regions of the first transmission member, for example by means of machining methods. The taper can then be guided between the convex coupling portion and the rest of the first transmission member through the slit in the sleeve until the collar on the sleeve engages behind the convex coupling portion. The sleeve can then be joined to the second transmission member. The taper in particular has the form of a neck or a waist. 
     A tool for a medical instrument comprises a transmission device as is described here. 
     A medical instrument comprises a transmission device as is described here. 
     In a method for producing a transmission device, a plurality of transmission members each having two coupling portions are provided, wherein one of the plurality of transmission members has a sleeve with a slit extending from the first end to the second end of the sleeve and a radially inwardly protruding collar at the second end of the sleeve. A taper on a convex coupling portion on a first transmission member is guided from the first end through the slit as far as the second end of the sleeve. A concave coupling portion on a second transmission member is introduced into the sleeve, wherein the convex coupling portion on the first transmission member is introduced into the concave coupling portion on the second transmission member. The sleeve is joined to the second transmission member. 
     The described method can enable simple and cost-effective production of a transmission device, in particular of a transmission device having the above-described features. In particular, all transmission members are identical and each have a sleeve with a slit extending from the first end to the second end of the sleeve. Alternatively, two or more different types of transmission members are provided, wherein each individual transmission member may have, at each end, at one end or at neither end, a sleeve with a radially inwardly protruding collar. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments are explained in greater detail hereinafter with reference to the accompanying figures, in which: 
         FIG. 1  shows a schematic illustration of a medical instrument; 
         FIG. 2  shows a schematic sectional illustration of a flexible portion of transmission device along sectional plane A-A; 
         FIG. 3  shows a further schematic sectional illustration of the flexible portion from  FIG. 2  along sectional plane B-B; 
         FIG. 4  shows a further schematic sectional illustration of coupling members from  FIGS. 2 and 3 ; 
         FIG. 5  shows a further schematic sectional illustration of the coupling members from  FIG. 4 ; 
         FIG. 6  shows a schematic sectional illustration of a further flexible portion of a transmission device; 
         FIG. 7  shows a schematic flow diagram. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a schematic illustration of a medical instrument  10  having a proximal end  11  and a distal end  12 , between which a shaft  14  with a hinge  16  extends. The shaft  14  is in particular rigid and straight on the proximal side of the hinge  16  and has a longitudinal axis  18 . The hinge  16  is formed by a flexible or resilient portion of the shaft  14  or by a hinged connection of two rigid portions of the shaft  14 . 
     At the proximal end  11 , the medical instrument  10  has a handling device  20  with a stationary grip part  21  and a movable grip part  22 . The movable grip part  22  is in particular pivotable about a pivot axis perpendicular to the drawing plane in  FIG. 1 . A first position of the movable grip part  22  is illustrated in  FIG. 1  by solid lines. A second position of the movable grip part  22  is illustrated in  FIG. 1  by dashed lines. The handling device  20  further has a turning wheel  23 , which is rotatable about the longitudinal axis  18  of the shaft  14 . 
     At the distal end  12  of the medical instrument  10 , a tool  30  with two pivotable jaw parts  31 ,  32  is provided. In  FIG. 1 , it is indicated by two arrows that the pivotable jaw parts  31 ,  32  can each be pivoted about an assigned pivot axis perpendicular to the drawing plane in  FIG. 1  between closed positions and open positions. The closed positions are illustrated in  FIG. 1  by solid lines, and the open positions are illustrated in  FIG. 1  by dashed lines. Furthermore, the tool  30  with the jaw parts  31 ,  32  is rotatable about an axis of rotation  38 , which in particular is the longitudinal axis of the tool  30 . 
     The handling device  20  at the proximal end  11  and the tool  30  at the distal end  12  of the medical instrument  10  are coupled by means of a transmission device  40 , in particular a transmission rod, in the shaft  14 . The transmission device  40  comprises a flexible portion  46 , which is explained below with reference to  FIGS. 2 to 6 . The transmission device  40  in particular couples the movable grip part  22  of the handling device  20  and the turning wheel  23  on the handling device  20  on the one hand to the tool  30  on the other hand. 
     In particular, a manual movement of the movable grip part  22  on the handling device  20  is transmitted to the jaw parts  31 ,  32  by an axial movement of the transmission device  40  parallel to the longitudinal axis  18  of the medical instrument  10  and, on the distal side of the flexible portion  46 , parallel to the axis of rotation  38  of the tool  30  and causes opening or closing pivot movements of the jaw parts  31 ,  32 . A rotation of the turning wheel  23  about the longitudinal axis  18  is transmitted to the tool  30  by a rotation of the transmission device  40  about the longitudinal axis  18  and, on the distal side of the flexible portion  46 , about the longitudinal axis  38  of the tool  30  and causes a rotation of the tool  30  about its axis of rotation  38 . 
     For transmission, with little play and little friction, of longitudinal forces and torques, the transmission device  40  is mounted in the shaft  14  with little play and little friction and is rigid or unresilient with regard to compressive forces and tensile forces and is also torsionally rigid or rigid in terms of a torsion about its longitudinal axis. This is also true in particular for the flexible portion  46 . 
       FIG. 2  shows a schematic sectional illustration of an exemplary embodiment of the flexible portion  46  of the transmission device  40  from  FIG. 1 . The sectional plane A-A in  FIG. 2  is parallel to the drawing plane in  FIG. 1  and in particular contains the longitudinal axis  18  of the shaft  14  and the longitudinal axis  38  of the tool  30 . The flexible portion  46  comprises a plurality of transmission members  50 ,  60 , which are identical in terms of design and of which the longitudinal axes  58 ,  68  likewise lie in the sectional plane A-A in  FIG. 2 . 
     Each transmission member  50 ,  60  comprises a convex coupling portion  51 ,  61  and a concave coupling portion  55 ,  65 . In the sectional plane A-A in  FIG. 2 , the convex coupling portions  51 ,  61  each have a substantially circular cross section. Each transmission member  50 ,  60  has a taper or a neck  52 ,  62  or a peripheral groove  53 ,  63  between the convex coupling portion  51 ,  61  and the concave coupling portion  55 ,  65 . 
     The concave coupling portions  55 ,  65  comprise recesses  56 ,  66 , which, in the sectional plane A-A, each have a substantially rectangular cross section and are surrounded by a wall  57 ,  67 . Each concave coupling portion  55 ,  65  further comprises a sleeve  70 . Each sleeve  70  has a substantially cylindrical wall  74 , which surrounds the wall  57 ,  67  around the recess  56 ,  66  like a casing. The sleeve  70  further has a radially inwardly protruding collar  76 . The sleeves  70  are joined, in particular welded, to the concave coupling portions  55 ,  65 . 
     In each case, the convex coupling portion  51  on a first transmission member  50  engages in the concave coupling portion  65  on a second, adjacent transmission member  60 . The collar  76  on the sleeve  70  of the concave coupling portion  65  of the second transmission member  60  engages in part in the groove  53  on the first transmission member  50  and bears against a shoulder-shaped region  54  on the convex coupling portion  51  of the first transmission member  50 . The sliding face provided on the collar  76  for bearing against the shoulder-shaped region  54  on the convex coupling portion  51  of the first transmission member  50  has, in accordance with the substantially spherical cross section of the convex coupling portion  51  in the sectional plane A-A, in particular the form of an annular cutout of a spherical surface. 
     By virtue of the at least partial engagement of the collar  76  of a transmission member  60  in the groove  53  on the adjacent transmission member  50  or by virtue of the bearing of the collar  76  of a transmission member  60  against the shoulder-shaped region  54  on the convex coupling portion  51  of the adjacent transmission member  50 , it is not only compressive forces that can be transmitted between the transmission members  50 ,  60 , but also tensile forces. Tensile forces can therefore also be transmitted through the entire flexible portion  46  of the transmission device  40 . The illustration in  FIG. 2  shows that the interlocking coupling of the transmission members  50 ,  60  is hinged. The longitudinal axes  58 ,  68  of adjacent transmission members  50 ,  60  can therefore be tilted relative to one another within a predetermined angular range. 
       FIG. 3  shows a further schematic sectional illustration of the flexible portion  46  from  FIG. 2 . The position of the sectional plane B-B illustrated in  FIG. 3  perpendicular to the longitudinal axis  68  of a transmission member  60  is indicated in  FIG. 2 . The position of the sectional plane A-A illustrated in  FIG. 2  is indicated in  FIG. 3 . 
     In the sectional plane B-B, both the convex coupling portion  51  and the inner surface of the wall  67  each have a substantially hexagonal cross section. The substantially hexagonal cross sections, corresponding to one another, of the convex coupling portion  51  of the first transmission member  50  and of the wall  67  of the concave coupling portion  65  of the second transmission member  60  cause an interlocking coupling of the transmission members  50 ,  60 , which enables transmission of a torque between the transmission members  50 ,  60 . 
     The outer surface of the wall  67  and the wall  74  of the sleeve  70  each have substantially the form of a circular-cylinder casing. Deviating from this, the sleeve  70  has a slit  78 , of which the width in the sectional plane B-B is at least as large as the diameter of the neck  52  (see  FIG. 2 ). The radially inner contour of the collar  76  of the sleeve  70  and also of the extension of the slit  78  into the collar  76  is illustrated in a dashed line. The collar  76  therefore does not have the form of a closed circular ring, but, deviating from this, a gap corresponding to the slit  78 . 
       FIG. 4  shows a schematic sectional illustration of a first transmission member  50  and of a sleeve  70  of a second transmission member, of which further components are not visible in  FIG. 4 . The sectional plane in  FIG. 4  is perpendicular to the sectional plane A-A in  FIG. 2  and perpendicular to the sectional plane B-B in  FIG. 3  and contains the longitudinal axis  58  of the transmission member  50 . The sectional plane in  FIG. 4  in particular runs in the middle of the slit  78  in the sleeve  70  and parallel to the edges thereof. 
     The transmission member  50  is shown by solid lines and hatched cross-sectional area in an initial position, in which the longitudinal axis  58  of the transmission member  50  is perpendicular to the longitudinal axis of the sleeve  70 . From this initial position, the convex coupling portion  51  of the transmission member  50  is introduced from the first end  71  thereof into the sleeve  70 , by means of the movement purely in translation indicated by the straight arrow, until the convex coupling portion  51  of the transmission member  50  bears substantially against the collar  76  of the sleeve  70 , and the neck  52  of the transmission member  50  is arranged in the slit  78  in the sleeve  70 . The configuration thus achieved is indicated by dashed contours. 
     As is indicated in  FIG. 4  by a curved arrow, the transmission member  50  is then pivoted about an axis perpendicular to the drawing plane in  FIG. 4  and, in so doing, is pivoted about the convex coupling portion  51  until the longitudinal axis of the transmission member  50  is substantially parallel to the longitudinal axis of the sleeve  70 . The configuration thus achieved is likewise indicated by dashed contours. In this configuration, the neck  52  of the transmission member  50  is no longer arranged in the slit  78  in the sleeve  70 , but substantially in the middle of the collar  76  at the second end  72  of the sleeve  70 . 
       FIG. 5  shows a further schematic sectional illustration of the transmission member  50  and of the sleeve  70  from  FIG. 4  in the configuration that is present at the end of the movement described with reference to  FIG. 4 . The transmission member  50  and the sleeve  70  are illustrated together with a further transmission member  60 . A movement of the transmission member  50  together with the sleeve  70  relative to the further transmission member  60  is indicated by a straight arrow. With this movement, the convex coupling portion  51  of the transmission member  50  is introduced into the recess  66  on the further transmission member  60 . At the same time, the sleeve  70  is drawn over the wall  67  around the recess  66  on the further transmission member  60 , or the wall  67  is introduced into the sleeve  70 . When the configuration illustrated in  FIG. 2  is reached, the sleeve  70  and the further transmission member  60  are joined, in particular by welding, soldering or adhesive bonding. 
       FIG. 6  shows a schematic sectional illustration of a further exemplary embodiment of the flexible portion  46  of the transmission device  40  from  FIG. 1 . The sectional plane in  FIG. 6  corresponds to the sectional plane in  FIG. 2 . 
     The exemplary embodiment in  FIG. 6  differs from the exemplary embodiment in  FIGS. 2 to 5  in that not all transmission members are identical. Instead, transmission members  80 ,  90  of two different types or designs are provided and are arranged alternately. A transmission member  80  of the first type has two convex coupling portions  81 ,  83  with a taper or a neck  82  between the convex coupling portions. A transmission member  90  of the second type has two concave coupling portions  91 ,  93 . 
     Each individual convex coupling portion  81 ,  83  of a transmission member  80  of the first type corresponds in terms of form and function to the convex coupling portion  51 ,  61  of a transmission member  50 ,  60  in the exemplary embodiment from  FIGS. 2 to 5 . Each individual concave coupling portion  91 ,  93  of a transmission member  90  of the second type corresponds in terms of spatial form and function to the concave coupling portion  55 ,  65  of a transmission member  50 ,  60  in the exemplary embodiment from  FIGS. 2 to 5 . In particular, each transmission member  90  of the second type therefore has two sleeves  70 . The sleeves correspond to the exemplary embodiment in  FIGS. 2 to 5 . 
     The interlocking, hinged coupling between a convex coupling portion  81 ,  83  of a transmission member of the first type and a concave coupling portion  91 ,  93  of a transmission member  90  of the second type corresponds to the interlocking mechanical coupling between a convex coupling portion  51  of a transmission member and a concave coupling portion  65  of an adjacent transmission member  60  in the exemplary embodiment illustrated above with reference to  FIGS. 2 to 5 . The exemplary embodiment, illustrated in  FIG. 6 , of the flexible portion  46  of the transmission device  40  therefore enables transmission of compressive forces and tensile forces and also of torques, similarly to the exemplary embodiment illustrated above with reference to  FIGS. 2 to 5 . The flexible portion  46  according to the exemplary embodiment illustrated in  FIG. 6  can also be produced in accordance with the method presented above with reference to  FIGS. 4 and 5  for the exemplary embodiment in  FIGS. 2 to 5 . 
       FIG. 7  shows a schematic flow diagram of a method for producing a transmission device. Although the method is also suitable for producing a transmission device having features that differ from those presented above with reference to  FIGS. 1 to 6 , reference signs from  FIGS. 1 to 6  will be used hereinafter by way of example to facilitate comprehension. 
     In a first step  101 , a plurality of transmission members  50 ,  60 ;  80 ,  90  each having two coupling portions  51 ,  61 ,  55 ,  65 ;  81 ,  83 ,  91 ,  93  are provided. The provision of the plurality of transmission members comprises provision  102  of a sleeve  70  as a component of one of the transmission members  50 ,  60 ;  80 ,  90 . The sleeve  70  provided in the second step  102  has a slit  78 , which extends from the first end  71  to the second end  72  of the sleeve  70 . The sleeve  70  further has a radially inwardly protruding collar  76  at the second end  72  of the sleeve  70 . 
     In a third step  103 , a taper or a neck  52 ;  82  on a convex coupling portion  51 ;  81 ,  83  on a transmission member  50 ;  80  is guided from the first end  71  through the slit  78  as far as the second end  72  of the sleeve  70 . The third step  103  is performed for example as presented above with reference to  FIG. 4 . 
     In a fourth step  104 , the convex coupling portion  51 ;  81 ,  83  on the first transmission member  50 ;  80  is introduced into the concave coupling portion  65 ;  91 ,  93  on the second transmission member  60 ;  90 . Here, the concave coupling portion  65 ;  91 ,  93  on the second transmission member  60 ;  90  is simultaneously introduced into the sleeve  70 . In a fifth step  105 , the sleeve  70  is joined, in particular welded, soldered or adhesively bonded, to the second transmission member  60 ;  90 . 
     REFERENCE SIGNS 
     
         
           10  medical instrument 
           11  proximal end of the medical instrument  10   
           12  distal end of the medical instrument  10   
           14  shaft of the medical instrument  10   
           16  hinge on the shaft  14   
           18  longitudinal axis of the medical instrument  10   
           20  handling device at the proximal end  11  of the medical instrument  10   
           21  stationary grip part of the handling device  20   
           22  movable grip part of the handling device  20   
           23  turning wheel on the handling device  20   
           30  tool at the distal end  12  of the medical instrument  10   
           31  first jaw part on the tool  30   
           32  second jaw part on the tool  30   
           38  axis of rotation of the tool  30   
           40  transmission device 
           46  flexible portion of the transmission device  40   
           50  transmission member 
           51  convex coupling portion of the transmission member  60   
           52  neck of the transmission member  50   
           53  groove on the transmission member  50   
           54  shoulder-shaped region on the convex coupling portion  51   
           55  concave coupling portion on the transmission member  50   
           56  recess on the concave coupling portion  55   
           57  wall around the recess  56   
           58  longitudinal axis of the transmission member  50   
           60  transmission member 
           61  convex coupling portion of the transmission member  60   
           62  neck of the transmission member  60   
           63  groove on the transmission member  60   
           64  shoulder-shaped region on the convex coupling portion  61   
           65  concave coupling portion on the transmission member  60   
           66  recess on the concave coupling portion  65   
           67  wall around the recess  66   
           68  longitudinal axis of the transmission member  60   
           70  sleeve of the transmission member  60   
           71  first end of the sleeve  70   
           72  second end of the sleeve  70   
           74  cylindrical wall of the sleeve  70   
           76  edge at the second end  72  of the sleeve  70   
           78  slit in the sleeve  70   
           80  transmission member of a first type 
           81  first convex coupling portion of the transmission member  80   
           82  neck of the transmission member  80   
           83  second convex coupling portion of the transmission member  80   
           84  shoulder-shaped region on the first convex coupling portion  81   
           88  longitudinal axis of the transmission member  80   
           90  transmission member of a second type 
           91  first concave coupling portion of the transmission member  90   
           93  second concave coupling portion of the transmission member  90   
           96  recess on the concave coupling portion  95   
           97  wall around the recess  96   
           98  longitudinal axis of the transmission member  90   
           101  first step (provision) 
           102  second step (provision) 
           103  third step (guidance through) 
           104  fourth step (introduction) 
           105  fifth step (joining)