Abstract:
A medical instrument includes instrument parts which can be releasably connected to one another. One part includes a hollow-cone-shaped receiving space and another part includes a cone-shaped coupling section which can be inserted into the receiving space to connect the parts. The coupling section includes a locking receiver for a locking element of the receiving space and which can be brought into and out of engagement with the locking receiver. A securing element moves between a position holding the locking element in a locking position, and a position releasing the locking element. An actuation element projects into the receiving space of the first instrument part, engages into the locking receiver in the locking position of the locking element and is movable in the direction of its middle axis. The middle axis of the actuation element is aligned in the proximal direction obliquely to a middle axis of the receiving space.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2014 205 080.4 filed Mar. 19, 2014, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a medical instrument. 
       BACKGROUND OF THE INVENTION 
       [0003]    With medical instruments, there often exits the need to releasably connect instrument parts to one another in a gas-tight and fluid-tight manner. One example of this is endoscopic shank instruments, with which an exchangeable working insert which is led through the shank of the instrument is fixed at the proximal end of the shank in a gas-tight or fluid-tight manner. 
         [0004]    Cone connections, which are secured from unintended release by way of positive-fit means, are particularly suitable for creating a gas-tight or fluid-tight connection of such instrument parts. In this context, it is known to lock the cone connection by way of a bayonet closure, wherein an end section of a second instrument part which corresponds to the receiving space of the first instrument part is inserted into this conically designed receiving space, and the two instrument parts are positively and non-positively connected to one another with an externally attached clamping ring forming part of the bayonet closure. The creation of the connection of the two instrument parts is comparatively uncomfortable since the clamping ring must be brought into a prescribed position by way of a suitable rotation, before the connection of the two instrument parts as well as for the release of the connection. 
       SUMMARY OF THE INVENTION 
       [0005]    Against this background, it is an object of the invention, to create a medical instrument, with which two instrument parts can be connected to one another in a quick and uncomplicated manner and in a further development of the invention can be separated from one another just as quickly and simply. 
         [0006]    The medical instrument according to the invention comprises at least two instrument parts which are releasably connectable to one another. A first instrument part is provided with a hollow-cone-shaped receiving space, whereas a second instrument part comprises a cone-shaped coupling section which can be inserted into the receiving space of the first instrument part, for connecting these two instrument parts. The conicities of the receiving space formed on the first instrument part and of the coupling section formed on the second instrument part preferably correspond, so that an at least fluid-tight and preferably gas-tight contact or connection of the first and second instrument part arises. 
         [0007]    The coupling section of the second instrument part comprises at least one locking receiver for a locking element which is arranged on the first instrument part and can be engaged with and disengaged from the locking receiver. With regard to the locking receiver, it is preferably the case of a recess or deepening, which is formed on the outer side of the coupling section of the second instrument part and which in the introduction direction of the coupling part into the receiving space, is distanced to the end of the coupling section which can be introduced into the receiving space of the first instrument head. The locking element which is preferably formed by a pin, usefully in the region of the receiving space of the first instrument part, is movably arranged relative to the second instrument part in a manner such that it can be engaged with the locking receiver formed on the coupling part of the second instrument part, for the positive connection of both instrument parts, and can be disengaged again for separating the two instrument parts. For this, the locking element usefully engages into the receiving space of the first instrument part. A securing element is provided, in order to be able to fix the locking element in its position engaging into the locking receiver. This element is movable between a first position, in which it holds the locking element in the locking position, and a second position, in which is releases the locking element. 
         [0008]    According to the invention, the securing element is coupled in movement to an actuation element which projects into the receiving space of the first instrument part and in the locking position of the locking element engages into the locking receiver of the second instrument part. This actuation element which is preferably designed in a pin-like manner is movable in the direction of its middle axis which is aligned in the proximal direction obliquely to a middle axis of the receiving space. I.e., the middle axis of the actuation element runs obliquely to the introduction direction of the coupling section of the second instrument part into the receiving space of the first instrument part. The middle axis of the actuation element is advantageously aligned at an angle between 45° to maximal 90° and preferably an angle of 55° obliquely to the middle axis of the receiving space. 
         [0009]    If the coupling section of the second instrument part is introduced into the receiving space of the first instrument part, then the coupling section with its outer side contacts the end of the actuation element which projects into the receiving space of the first instrument part and on account of the alignment of the actuation element obliquely to the introduction direction of the coupling part and on account of the cone-shaped design of the coupling part moves this actuation element out of the receiving space of the first instrument part. The securing element which is coupled in movement to the actuation element is moved by way of this movement of the actuation element from its first position into its second position, in which it releases the locking element. The end of the locking element which projects into the receiving space of the first instrument part, on account of this can firstly be forced out of the receiving space by the coupling section of the second instrument part. With a further movement of the coupling section of the second instrument part into the receiving space of the first instrument part, the actuation element engages into a recess which is formed on the outer side of the coupling section of the second instrument part and with which recess it is preferably the case of a locking receiver. The securing element by way of this can move back again into its first position, in which it pressure-impinges the locking element in the direction of the coupling section of the second instrument part, and when the locking receiver formed on the coupling section of the second instrument part is located directly in front of the locking element, then presses it into the locking receiver and holds it in this locking position. Accordingly, with the medical instrument according to the invention, a secure connection of its first instrument part to its second instrument part can be created in a rapid and simpler manner solely by way of the introduction of the coupling section of the second instrument part into the receiving space of the first instrument part. With a suitable material selection of the locking element and of the coupling section of the second instrument part, for example if the locking instrument and the coupling section are designed of a metallic material, then the user of the instrument according to the invention hears a detent noise which notifies him of a secure connection of the two instrument parts of the instrument. 
         [0010]    The locking receiver formed on the coupling section of the second instrument part preferably runs over the whole outer periphery of the coupling section. Preferably, a groove extending over the whole outer periphery of the coupling section is accordingly formed on the outer lateral surface of the coupling section. This design measure has the advantage that the first and the second instrument part can be connected to one another independently of a relative rotational position, since the locking element and the actuation element can engage into the locking receiver formed on the coupling section of the second instrument part, independently of this rotation position. The connection of the two instrument parts is further simplified due to this. 
         [0011]    The locking receiver further preferably has a trapezoidal cross section. Thus, one preferably envisages the width of a groove which extends around the outer periphery of the coupling section of the second instrument part and which forms the locking receiver continuously reducing in the radial direction of the coupling section, and the groove accordingly being delimited by two side walls which lie opposite one another and which taper to one another in an oblique manner in the radial direction of the coupling section. 
         [0012]    A trapezoidal cross section of the locking receiver is particularly advantageous if, as is envisaged according to a further preferred design, an end section of the locking element which engages into the locking receiver is designed in a truncated-cone-like manner. The gradient of the end section of the locking element which is designed in a truncated-cone-like manner and at least the gradient of the side wall of the locking receiver which is at the front in the introduction direction of the second instrument part hereby usefully correspond to one another, so that the end section which is designed in truncated-cone-like manner bears on this side wall in a surfaced (flat) manner in the locking position of the locking element in the locking receiver. This measure permits an adequate self-locking of the locking element in the locking receiver and moreover reduces the proneness of the locking receiver and/or of the locking element to wear, on separating the second instrument part from the first instrument part, i.e. on withdrawing the coupling section of the second instrument part from the receiving space of the first instrument part. 
         [0013]    A through-hole which is aligned transversely to the connection direction of the first and second instrument part is advantageously formed on the first instrument part for the movable arrangement of the locking element on this first instrument part. The locking element usefully extends through the through-hole and runs out in the receiving space. Hereby, the locking element is advantageously dimensioned such that its projects on an outer side which is away from the receiving space of the first instrument part, when the locking element is located in its locking position. 
         [0014]    The securing element which holds the locking element in a first position in its locking position and releases it in a second position, is preferably formed by a sleeve which is displaceably arranged on the outer side of the first instrument part in the connection direction of the two instrument parts. Accordingly, the securing element or the sleeve forming the securing element is displaceable from its first position into its second position, and vice versa, in the axial direction of the receiving space. The securing element is usefully arranged in a region on the outer side of the receiving space which is formed on the first instrument part. 
         [0015]    In one advantageous further development of the securing element, a contact surface for the locking element, i.e. for its end projecting outwards at the outer side on the first instrument part, and which is aligned a obliquely to the movement direction of the locking element is formed inner side of the securing element. This obliquely aligned contact surface of the securing element is usefully designed such that the locking element is pushed by the securing element in to its locking position, in the first position of the securing element, wherein the distance of the contact surface of the securing element to the end of the locking element which projects out of the first instrument part at the outer side increases with a movement of the securing element into its second position, so that a continuously increasing free space results between the outer side of the first instrument part and the securing element which is arranged around this, into which free space the locking element can retreat or move back on separating the second instrument part from the first instrument part, and is then no longer engages with the locking receiver formed on the coupling section of the second instrument part. 
         [0016]    As has been already noted, the actuation element projecting into the receiving space of the first instrument part moves out of the receiving space, and the securing element which is coupled in movement thereto is moved from its first position into its second position, in which it releases the locking element, on introducing the coupling section of the second instrument part into the receiving space of the first instrument part. The securing element must be moved back into its first position again as soon as the coupling section of the second instrument part is inserted so far into the receiving space of the first instrument part that the actuation element and the locking element can engage into the locking receiver formed on the coupling section of the second instrument part, by which means the actuation element and the locking element are pressed into the locking receiver. In this context, it is particularly advantageous if the securing element is moved automatically into its first position. The securing element is preferably actively connected to a spring element in a manner such that the securing element is moved into the first position by way of a spring force produced by the spring element, for this purpose. 
         [0017]    Usefully, a through-hole is formed on the first instrument part for the movable arrangement of the actuation element on this first instrument part. This through-hole, due to the oblique alignment of the middle axis of the actuation element which is envisaged according to the invention, typically tapers counter to the connection direction of the two instrument parts, obliquely or at right angles to the middle axis of the receiving space. 
         [0018]    The coupling of movement of the actuation element to the securing element, with the instrument according to the invention is preferably not effected via a fixed connection of the actuation element and securing element, but instead via a loose contact of these two elements. A contact surface aligned obliquely to the connection direction of the two instruments is advantageously formed on the inner side of the securing element, also for the actuation element for this. This obliquely aligned contact surface on the securing element leads to a force component which thus moves the securing element in the insertion direction of the second instrument part and acts in the movement direction of the securing element, acting upon the securing element when the actuation element is moved out of the receiving space on introducing the coupling part of the second instrument part into the receiving space of the first instrument part. 
         [0019]    The securing element preferably has a contact surface for the locking element and which is designed in a bevelled manner, as well as a contact surface for the actuation element and which is designed in a bevelled manner. The contact surface for the locking element and the contact surface for the actuation element are usefully aligned at different angles to the connection direction of the two instrument parts. The purpose of this different angle of the two contact surfaces provided on the securing element is to control the movement procedure or point in time of engagement of the actuation element and locking element into the locking receiver formed on the coupling section of the second instrument part. The angles of the two contact surfaces which are formed on the securing element are usefully selected in a manner such that firstly the actuation element and thereafter the locking element engage into the locking receiver formed on the second instrument part. 
         [0020]    The securing element must be manually moved into its second position, in which it releases the locking element, for separating the second instrument part from the first instrument part. Thus, the securing element is advantageously coupled in movement to the grip part, in order to simplify the handling of this securing element. The grip part can be a separate part which is fixedly connected to the securing element or it can form an integral component of the securing element. Usefully, the grip part is designed and arranged in a manner such that it can be actuated just as well by left-handed persons and right-handed persons, from each peripheral position of the first instrument part. Thus, the grip part can advantageously be designed in an annular manner wherein it is arranged on the outer lateral surface of the securing element. 
         [0021]    An end region of the locking element and of the actuation element and contacting the coupling section of the second instrument part in each case is advantageously provided with a low-friction coating. Accordingly, the end region of the locking element which projects in the receiving space of the first instrument part, as well as the end region of the actuation element which projects in the receiving space are provided with a coating which improves the sliding characteristics of the locking element and of the actuation element on contact of the coupling section of the second instrument part. Wear is reduced and in the best case is prevented on account of this measure, at the coupling section of the second instrument part as well as at the locking element and the actuation element. Such materials as are applied in the construction of sliding bearings can e.g. be used as coating materials. It is to be noted that as the case may be, the actuation element and the locking element can be formed completely from a sliding-bearing-optimized material instead of a coating provided on the locking element and the actuation element. 
         [0022]    One further advantageously envisages forming a contact surface to the coupling section of the second instrument part and which is bevelled in a manner such that its contacts the coupling section in a surfaced which is to say flat manner, on the end of the actuation element which projects into the interior of the first instrument part, as a further measure. 
         [0023]    The invention is hereinafter explained in more detail by way of an embodiment example shown in the drawings. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    In the drawings, shown in a schematically simplified manner and in different scales in each case: 
           [0025]      FIG. 1  in a perspective representation showing the connection region of a medical instrument with two instrument parts which are to be connected; 
           [0026]      FIG. 2  is an enlarged sectioned view showing the connection region of the instrument according to  FIG. 1 , in the non-locked condition; and 
           [0027]      FIG. 3  is a representation according to  FIG. 2 , in the locked condition. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0028]    With the medical instrument represented in  FIG. 1 , it is the case of an endoscopic instrument with a first instrument part in the form of a hollow shank  2  which can be introduced into the inside of the body, and with a second instrument part in the form of a working insert  4  which can be inserted into the hollow shank  2  and is connectable to the hollow shank  2  in a gas-tight manner. 
         [0029]    The hollow shank  2  is formed by a tube  6 , at whose proximal end a coupling device  8  is arranged for fixing the working insert  4 . For this, the working insert  4  comprises a coupling section  10  which is introduced into a receiving space  12  which is open to the proximal side and which is formed on the coupling device  8  of the hollow shank  2   
         [0030]    The coupling section  10  of the working insert  4  has a distal region  14  which tapers in a cone-shaped manner in the distal direction. A cylindrically designed region  15  of the coupling section  10 , on which a groove with a trapezoidal cross section and extending over the entire periphery of the coupling section  10  is formed, connects to the proximal end of the region  14  of the coupling section  10 . This groove forms a locking receiver  18 , whose significance will be dealt with in a more detailed manner hereinafter. 
         [0031]    In a manner corresponding to the shaping of the coupling section  10  of the working insert  4 , the receiving space  12  formed on the coupling device  8  of the hollow shank  2 , at the proximal side comprises a cylindrically designed region which distally merges into a conically tapering region. A through-hole  20  which extends from a radial outer side of the coupling device  8  transversely to a middle axis A of the hollow shank  2  to the receiving space  12  runs out at the cylindrical region of the receiving space  12 . The through-hole  20  comprises a radial widening  22  adjacently to the outer side of the coupling device  8 . 
         [0032]    A locking element  24  is guided in an axially displaceable manner in the through-hole  20  and serves for positively fixing the coupling section  10  of the working insert  4  in the receiving space  12  of the coupling device  8  of the hollow shank  2  The locking element  24  is formed by a pin. This pin comprises a cylindrical base body which tapers in a truncated-cone-shaped manner in an end section projecting into the receiving space  12 . A head which projects radially beyond the outer periphery of the base body is formed on the other end of the base body, wherein the outer diameter of the head corresponds to the inner diameter of the widening  22  formed on the through-hole  20 . The head of the locking element  24  forms a contact shoulder which comes into contact on a shoulder formed by the widening  22  of the through-hole  20  and in this manner limits the movement path of the locking element  24 . The locking element  24  is dimensioned such that it always projects out of the through-hole  20  at the end of this through hole which is away from the receiving space  12 , independently of its displacement position. 
         [0033]    A further through-hole  26  runs out at the cylindrical region of the receiving space  12 , in a manner roughly diametrically opposite the through-hole  20 . This through-hole  26  runs obliquely through the outer wall of the coupling device  8 , wherein its middle axis B in the proximal direction is aligned at an angle obliquely to the middle axis A of the hollow shank  2  or of the receiving space  12 . An actuation element  28  is axially displaceably guided in the through-hole  26  and the significance of this will be explained in more detail hereinafter. 
         [0034]    The coupling device  8  in the region of the proximal end of this is surrounded by a component which forms a securing element  30  for the locking element  24 . The securing element  30  is displaceable in the direction of the middle axis A on the coupling device  8 , wherein it is secured against a rotation movement about the middle axis A by way of a keyway connection to the coupling device  8 , which is not evident from the drawings. 
         [0035]    The securing element  30  has an essentially sleeve-like base body, on which two tongues  32  and  34  extending in the distal direction are formed at the distal side. The tongues  32  and  34  are arranged in a manner such that the tongue  32  with its inner side facing the outer side of the coupling device  8  contacts the locking element  24 , and the tongue  34  with its inner side facing the outer side of the coupling device  8  contacts the actuation element  28 . The contact of the tongue  32  with the locking element  24  is effected via a contact surface  36  which is formed on the inner side of the tongue  32  and which is aligned obliquely to the middle axis A of the hollow shank  2  in a manner such that the radial distance of the securing element  30  to the outer side of the coupling device  8  increases in the proximal direction. The tongue  34  contacts the actuation element  28  via a contact surface  38  which is formed on the inner side of this tongue and which is likewise aligned obliquely to the middle axis A of the hollow shank  2  The obliqueness of the contact surface  38  is also such that the radial distance of the securing element  30  to the outer side of the coupling device  8  increases in the proximal direction. 
         [0036]    The securing element  30  in the direction of the middle axis A of the hollow shank  2  is supported on a spring element  40  in the form of a helical spring. This spring element  40  is arranged between an annular shoulder  42  formed on the outer periphery of the coupling device  8  of the hollow shank  2  and a shoulder formed on the outer side of the securing element  30  at the transition of the conical base body to the tongues  32  and  34 . 
         [0037]    The securing element  30  is connected to the grip part  44 . This grip part  44  is arranged peripherally around the securing element  30  and is designed in an essentially sleeve-like manner, wherein the grip part  44  comprises a radially outwardly projecting annular shoulder  46  at its proximal end, for an improved handling. 
         [0038]    The connection of the working insert  4  to the hollow shank  2  with the endoscopic instrument represented in the drawings is effected as follows: 
         [0039]    The spring element  40 , before the working insert  4  is inserted into the hollow shank  2 , presses the securing element  30  into a first position, in which the securing element  30  via its tongue  32  holds the locking element  24  in its locking position, in which the truncated-cone-shaped end section of the locking element  24  projects into the receiving space  12  formed on the coupling device  8  of the hollow shank  2  The actuation element  28  is simultaneously also pressed by the tongue  34  of the securing element  30  into a position, in which the end section of the actuation element  28  projects into the receiving space  12 . 
         [0040]    If, as is represented in  FIG. 2 , the working insert  4  is now inserted via the opening of the receiving space  12  into the hollow shank  2 , then the region  14  of the coupling section  10  of the working insert  4  and which is formed in a cone-like manner comes into contact with a blunt tip which is formed at the end of the actuation element  28  which projects into the receiving space  12 . The actuation element  28  is moved further in the direction out of the receiving space  12  with a further introduction movement of the working insert  4  in the distal direction. A force component acting in the direction of the middle axis A of the hollow shank  2  is exerted onto the securing element  30 , due to the fact that the actuation element  28  contacts the bevelled contact surface  38  formed on the tongue  34  of the securing element  30 , and this force component pushes the securing element  30  in the distal direction into its second position against the action of the spring element  40 . The locking element  24  by way of this can firstly escape out of the receiving space  12  on contact with the region  14  of the coupling section  10  of the working insert  4 , said region designed in a cone-like manner. As soon as the locking receiver  18  which is formed on the coupling section  10  is located directly in front of the end of the through-hole  26  which faces the receiving space  12 , the actuation element  28  slips into the locking receiver  18 , by which means the contact of the actuation element  28  with the securing element  30  is released, so that the spring element  40  moves the securing element  30  again in the direction of its first position. Hereby, the securing element  30  via the contact surface  36  formed on its tongue  32  pushes the locking element  24  into the locking receiver  18 , in which the locking element  24  is held by the securing element  30  on reaching its second position. 
         [0041]    The securing element  30 , via the grip part  44  connected thereto is pushed in the distal direction against the effect of the spring element  40 , for releasing the working insert  4  from the hollow shank  2 . The locking element  24  and the actuation element  28  are released from the securing element  30  by way of this, so that the locking element  24  and the actuation element  28  can be pressed out of the receiving space  12  on withdrawing the coupling element  10  of the working insert  4  out of the receiving space  12  of the coupling device  8  of the hollow shank  2 , and the working insert  4  can be separated from the hollow shank  2  without any problem. 
         [0042]    While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.