Instrument

1. An instrument ( 30 ) with an elongated first hollow shaft ( 42 ), an end effector ( 60 ) which is arranged on a distal end of the first hollow shaft ( 42 ), and an actuation unit ( 19 ) arranged on a proximal end of the first hollow shaft ( 42 ), wherein the actuation unit ( 19 ) comprises a first wheel ( 32 ) which is connected non-rotatably with the first hollow shaft ( 42 ), characterised in that the first hollow shaft ( 42 ) is axially displaceable in relation to the first wheel ( 32 ) and is in threaded engagement with a second wheel ( 33 ) adjacent the first wheel ( 32 ), and wherein the second wheel ( 33 ) is axially non-displaceable in relation to the first wheel ( 32 ), and further including a second shaft ( 41 ) disposed within the hollow first shaft ( 42 ) and configured to drive a working movement of the end effector ( 60 ), and wherein the second shaft ( 41 ) is coupled to a fourth wheel ( 31 ) of the actuation unit ( 19 ).

2. The instrument ( 30 ) according to claim 1 , characterised in that the first shaft ( 42 ) extends through a shaft sleeve ( 44 ) which is connected, at a proximal end, rotatably and axially immovably, with one of the wheels ( 32 , 33 ) and that the end effector ( 60 ) is coupled on the distal ends of the first shaft ( 42 ) and the shaft sleeve ( 44 ) in order to swivel around a swivel axis ( 78 ) oriented transversely to the shaft sleeve ( 44 ) by means of a swivel mechanism ( 79 ) and is driven through a relative movement between the first shaft ( 42 ) and shaft sleeve ( 44 ).

3. The instrument ( 30 ) according to claim 2 , characterised in that the shaft ( 42 ) has a flexible region which extends at least partially through the swivel mechanism ( 79 ).

4. The instrument ( 30 ) according to claim 2 , characterised in that the end effector ( 60 ) is rotatable around an axis of rotation ( 76 ) which is swivelable around the swivel axis ( 78 ), and the rotation is controlled through a rotation of the first shaft ( 42 ).

5. The instrument ( 30 ) according to claim 2 , characterised in that the swivel mechanism ( 79 ) comprises a proximal member ( 61 ) firmly connected with the distal end of the shaft sleeve ( 44 ) and a distal member ( 62 ) connected with the first shaft ( 42 ) which is driven in a swivelling action through an axial displacement of the first shaft ( 42 ) relative to the proximal member ( 61 ).

6. The instrument ( 30 ) according to claim 5 , characterised in that each the two members ( 61 , 62 ) has a bolt ( 73 , 74 ) and a guide slot ( 72 , 75 ) in which a bolt ( 73 , 74 ) of the other member is displaceable in order to guide the swivelling movement of the distal member ( 62 ).

7. The instrument ( 30 ) according to claim 2 , characterised in that the actuation unit ( 19 ) comprises a third wheel ( 34 ) which is connected, non-rotatably and axially immovably, with the shaft sleeve ( 44 ).

8. The instrument ( 30 ) according to claim 1 , characterised in that the second shaft ( 41 ) is coupled non-rotatably to the fourth wheel ( 31 ) and is axially displaceable together with the first shaft ( 42 ).

9. The instrument ( 30 ) according to claim 1 , characterised in that the second shaft ( 41 ) has a flexible region which extends at least partially through the swivel mechanism.

10. The instrument ( 30 ) according to claim 1 , characterised in that at least two wheels ( 31 , 32 , 33 , 34 ) of the actuation unit ( 19 ) are coupled together via a roller bearing ( 47 ) and are mounted so as to be axially immovable relative to one another.

11. The instrument ( 30 ) according to claim 10 , characterised in that the roller bearing ( 47 ) is a radial bearing, an outer ring of which is accommodated in one of the two wheels ( 31 , 32 , 33 , 34 ) and an inner ring of which is pushed onto the other wheel ( 31 , 32 , 33 , 34 ).

12. The instrument ( 30 ) according to claim 10 , characterised in that a plurality of driving-force-transmitting elements ( 36 ) are distributed on the periphery of one of the wheels ( 31 , 32 , 33 , 34 ) which transmits a driving force overlaps axially with the roller bearing ( 47 ).

13. The instrument ( 30 ) according to claim 1 , wherein said instrument further includes a third wheel ( 34 ) and a fourth wheel ( 31 ), said instrument characterised in that at least one of the wheels ( 31 , 32 , 33 , 34 ) is equipped with ferromagnetic bodies ( 36 ) on its periphery.

14. The instrument ( 30 ) according to claim 1 , characterised in that the actuation unit ( 19 ) is enclosed by a germ-proof, sleeve-formed barrier ( 59 ).

15. The instrument ( 30 ) according to claim 1 , characterised in that the actuation unit ( 19 ) is configured to be pushed, releasably, in the longitudinal direction of the shaft ( 42 ), into a cavity of a drive unit ( 8 ).

16. The instrument ( 30 ) according to claim 15 , characterised in that the drive unit ( 8 ) includes a plurality of drive modules ( 18 ) arranged in a staggered manner in the longitudinal direction, and wherein each of said plurality of drive wheels interacts with a respective one of the wheels ( 31 , 32 , 33 , 34 ).

17. The instrument ( 30 ) according to claim 1 , characterised in that the actuation unit ( 19 ) includes at least one motor drive which drives at least one of the wheels ( 31 , 32 , 33 , 34 ).