MEDICAL DEVICE

Description

[0001] The invention relates to a medical device with a joint arrangement which is designed for a pivoting movement of a first joint part relative to a second joint part, with a first joint part which comprises two joint legs arranged at a distance from one another and a joint pin which extends between the joint legs along a longitudinal axis and which determines a pivot axis of the joint arrangement, and with a second joint part which is partially received between the two joint legs and which is penetrated by a joint recess, wherein the joint pin is pivotably received in the joint recess.

[0002] Such a joint arrangement is used, for example, in a holder for a medical instrument, wherein it can be provided that the medical instrument is fixed with a clamping device, wherein the clamping device comprises a joint arrangement.

[0003] US 2013 / 0144395 A1 describes a joint assembly referred to as a distal wrist assembly. A second wrist frame comprises a distal fork head with two prongs. The ends of a pivot pin are received in through holes in the prongs. Between the prongs, the pivot pin passes through a through hole in a first jaw part and through holes adjacent to its ends in a proximal fork-shaped second jaw part.

[0004] US 4,491,436 describes a pivot pin assembly. The pivot pin assembly includes a bore in an intermediate component, a pivot pin, and a friction-reducing element containing an inner ring and an outer ring. The outer ring is press-fitted into the bore in the intermediate component and held in position by a pair of snap rings.

[0005] The object of the invention is to provide a joint arrangement which ensures low friction for a pivoting movement of the two joint parts relative to each other, even when high forces are temporarily introduced.

[0006] This object is achieved for a joint arrangement of the type mentioned at the outset with the features of claim 1. It is provided that the joint pin and the joint recess have a central contact area with a touching contact between the joint pin and the joint recess and, on both sides of the contact area, release areas extending up to the joint legs without touching contact between the joint pin and the joint recess in order to ensure an exclusively central force transmission between the joint pin and the joint recess.

[0007] The exclusively central force transmission ensures that the joint pin can perform an evasive movement in the two release areas when forces are applied to the two joint parts, and can thereby be elastically deformed. This avoids undesirable friction effects between the joint pin and the joint recess, which could lead to long-term damage to the joint arrangement. When force and / or torque are applied to the two joint parts, the joint pin is deformed in an S-shape away from the contact area in the respective release area. If force is applied to the two joint parts exclusively in a direction transverse to the longitudinal axis, the joint pin is deformed in an S-shape that is mirror-symmetrical to a mirror plane that is aligned normal to the longitudinal axis.If, however, a torque is introduced onto the two joint parts, with the torque being directed around a torque axis that is transverse to the longitudinal axis, an S-shaped deformation of the joint pin takes place in the respective release areas axes symmetrical to the torque axis.

[0008] Advantageous further developments of the invention are the subject of the subclaims.

[0009] It is expedient if the joint recess is designed as a stepped bore with a centrally arranged guide bore that has a smaller cross-section than the clearance bores adjacent to it on either side. This enables cost-effective production of the guide bore, since only the clearance bores need have a larger cross-section, while the guide bore has a smaller cross-section, the profile of which is adapted to the profile of the joint pin in such a way that the joint pin can form a sliding bearing with the guide bore. It is preferably provided that the guide bore and the clearance bores are each circularly cylindrical and, in particular, are arranged coaxially to one another. In addition, it can be provided that the cross-sections of the two clearance bores are identical.

[0010] Preferably, the hinge pin is formed with a constant profile between the hinge legs. Preferably, the hinge pin has a circular profile and is thus designed as a circular cylinder, which allows for a cost-effective manufacturing method for the hinge pin.

[0011] In an alternative development of the invention, the hinge pin is designed with a centrally arranged guide section which has a larger cross-section than the release sections adjacent to it on either side. This makes it possible to achieve particularly advantageous elasticity for the hinge pin, since the centrally arranged guide section, due to its larger cross-section, can be designed to be dimensionally stable within the scope of the maximum forces intended for the hinge arrangement, while the adjacent release sections, due to their smaller cross-section, can be elastically deformed even at forces significantly below the maximum forces intended for the hinge arrangement. Preferably, both the guide section and the adjacent release sections are each circularly cylindrical and arranged coaxially to one another.

[0012] In a further embodiment of the invention, the joint recess is designed as a bore with a constant profile. This allows the joint recess to be produced by a single manufacturing process, in particular a drilling process.

[0013] It is advantageous if the hinge pin is designed with a centrally arranged guide section that has a larger cross-section than the clearance sections adjacent to it on both sides, and if the hinge recess is designed as a stepped bore with a centrally arranged guide bore that has a smaller cross-section than the clearance holes adjacent to it on both sides. By adapting the cross-sections of the clearance sections to the cross-sections of the clearance holes, an advantageous adjustment of the desired elasticity for the hinge arrangement can be achieved.

[0014] Preferably, opposing surfaces of the joint legs form a sliding guide with adjacent surfaces of the second joint part, with play, and the joint pin and the joint recess are coordinated with one another in such a way that when the second joint part tilts relative to the first joint part about a tilting axis oriented transversely to the longitudinal axis, the joint pin undergoes exclusively elastic deformation. The sliding guide between the two joint parts serves in particular to absorb forces or force components that are aligned parallel to the longitudinal axis of the joint pin and are not supported by the joint pin and the corresponding joint recess. Furthermore, the sliding guide between the two joint parts serves to limit tilting between the first joint part and the second joint part about a tilting axis oriented transversely to the longitudinal axis.Due to the elasticity of the hinge pin, larger tilt angles between the two joint parts can be accommodated compared to known joint arrangements implemented with rigid hinge pins. This allows, for example, a clamping fixture equipped with a joint arrangement according to the invention to adapt favorably to different external geometries of the objects to be clamped, without having to accept undesirable stiffness of the joint arrangement.

[0015] It is expedient if an extension of the central contact area in the direction of the longitudinal axis is less than 30 percent, preferably less than 25 percent, of an extension of one of the release areas in the direction of the longitudinal axis.

[0016] In an advantageous development of the invention, it is provided that a cross-sectional area of ​​the guide bore is less than 50 percent, preferably less than 40 percent, in particular less than 30 percent, of a cross-sectional area of ​​the relief bore.

[0017] In a further embodiment of the invention, it is provided that a cross-sectional area of ​​the release section is less than 50 percent, preferably less than 40 percent, in particular less than 30 percent, of a cross-sectional area of ​​the guide section.

[0018] Advantageous embodiments of the invention are illustrated in the drawing. Figure 1 shows a schematic representation of a medical device comprising a joint arrangement as a component of a clamping device, Figure 2 shows a schematic detailed representation of the clamping device according to the Figure 1, Figure 3 a schematic plan view of the clamping device according to the Figure 2 , Figure 4 a detailed view of the clamping device according to the Figures 2 and 3 with a first embodiment of a joint arrangement, in which the joint pin is designed with a centrally arranged guide section which has a larger cross section than the release sections adjacent to it on both sides, Figure 5 shows a detailed representation of the clamping device according to the Figures 2 and 3with a second embodiment of a joint arrangement in which the joint recess is designed as a stepped bore and the joint pin has a constant profile, Figure 6 shows a schematic representation of a joint pin with an exclusive introduction of radial forces, and Figure 7 shows a schematic representation of a joint pin with an exclusive introduction of a torque about a torque axis oriented transversely to a longitudinal axis of the joint pin.

[0019] One in the Figure 1 The medical device 1 shown is designed purely as an example as a mobile support arm for a medical instrument not shown in detail, for example an endoscopic camera system.

[0020] The medical device 1 comprises a base frame 2 equipped with casters 3 and having a column 4 extending substantially vertically upward. A first support arm section 5 is arranged on the column 4, adjustable in height and pivotable about a vertical axis. At an end region remote from the column 4, the first support arm section 5 is coupled to a second support arm section 6, which in turn is pivotably mounted on the first support arm section 5 about a vertical axis (not shown).

[0021] At an end region of the second support arm section 6 facing away from the first support arm section 5, a gripping arrangement 8 is formed, purely by way of example, with the interposition of a ball joint 7, which comprises a fixed gripper claw 9 and a movable gripper claw 10. The fixed gripper claw 9 and the movable gripper claw 10 form a joint arrangement 11, which enables the pivoting relative movement of the movable gripper claw 10 with respect to the fixed gripper claw 9.

[0022] As can be seen from the schematic representation of the Figure 3can be removed, the fixed gripper claw 9 is fork-shaped at an end region facing away from the ball joint 7 and comprises two spaced-apart joint legs 15, 16, between which the movable gripper claw 10 is received purely as an example. Thus, the fixed gripper claw 9 with its joint legs 15, 16 forms a first joint part 17, while the movable gripper claw 10 forms a second joint part 18. The two joint parts 17, 18 are pivotally connected to one another by means of a joint bolt, wherein in the Figures 4 and 5 different embodiments of joint arrangements are shown.

[0023] Purely exemplary, the Figure 3the mutually facing surfaces 43, 44 of the two joint legs 15, 16 and the mutually opposing surfaces 45, 46 of the second joint part 18 are arranged in such a way that no bearing play is discernible for the plain bearing, which is formed by these surfaces 43 to 46 for the two joint parts 17, 18. In practice, the respective opposing surfaces 43 and 45 or 44 and 46 will each have a slight distance from one another in order not to jeopardize the smooth running of the joint arrangement 11. Accordingly, the second joint part 18 can, upon introduction of a torque which is normal to the plane of representation of the Figure 3 is aligned, cause a tilting of the second joint part 18 relative to the first joint part 17, as symbolically shown in the Figure 7 is shown.

[0024] At the Figure 4In the first embodiment of a joint arrangement 30 shown, the two joint legs 15 and 16 of the first joint part 17 as well as the second joint part 18 are penetrated by a purely exemplary circular cylindrical through-bore 31, which can also be referred to as a joint recess with regard to the second joint part 18. In the through-bore 31, in addition to the sectional view of the Figure 4A hinge pin 32, shown as an individual part, is provided, which is received, for example, in a frictionally engaged manner in the two hinge legs 15 and 16 and which forms a pivot bearing with the second hinge part 18. For this purpose, the hinge pin 32 comprises a centrally arranged guide section 33, which is adapted to a preferably circular profile of the through-bore 31 in such a way that a sliding relative movement between the guide section 33 and the second hinge part 18 provided with the through-bore 31 is possible. At each end, the hinge pin 32 is provided with holding sections 34, 35, which are fixed in a force-locking manner in the hinge legs 15, 16 and thus ensure a rotationally fixed connection between the hinge pin 32 and the first hinge part 17.

[0025] On both sides of the guide section 33, release sections 36, 37 extend along a longitudinal axis 38 serving as the pivot axis for the second joint part 18 up to the holding sections 34 and 35, respectively. The release sections 36 and 37 have a considerably smaller cross-section, in particular a considerably smaller diameter, than the guide section 33. This geometric design of the joint pin 32 ensures that force is transmitted between the second joint part 18 and the joint pin 32 fixed to the first joint part 17 exclusively in the region of the guide section 33 and that the release sections 36 and 37, due to their considerably smaller cross-sections compared to the guide section 33, enable advantageous elasticity for the joint arrangement 33.

[0026] At the Figure 5In the second embodiment of a joint arrangement 50 shown in FIG. 1, in which the joint pin 52 is frictionally received in guide sections 53, 54 of the joint legs 15, 16 and has a constant profile along a longitudinal axis 55, the joint recess formed as a through-bore 51 is implemented as a stepped bore. The through-bore 51 comprises a centrally arranged guide bore 56, the cross-section of which is adapted to the cross-section of the joint pin 52 in order to form a pivotable sliding bearing. Adjacent to the guide bore 56 on both sides extend clearance bores 57, 58, which ensure the clearance areas without contact between the joint pin 52 and the through-bore 51 serving as the joint recess.

[0027] From the purely schematic representation of the Figures 6 and 7, which relate to the hinge pin 32 according to the first embodiment of the hinge arrangement 30, but also apply in a similar way to the hinge arrangement 50, it can be seen that when a purely radial force 40 is introduced, which is suspended in the guide section 33 via the second hinge part 18, an S-shaped deformation of the two release sections 36, 37 takes place mirror-symmetrically to a mirror plane 41.

[0028] When a torque 42 is introduced around a plane normal to the plane of the Figure 7 aligned torque axis on the guide section 33, however, results in a tilting of the guide section 33 relative to the holding sections 34 and 35, in which the release sections 36 and 37 are also each deformed in an S-shape, whereby the geometric relationship between the two release sections 36 and 37 is a mirror image around the torque axis.

Claims

1. A medical device having a joint arrangement (11; 30; 50) which is designed for a swivelling movement of a first joint part (17) relative to a second joint part (18), having a first joint part (17), which comprises two joint limbs (15, 16) arranged spaced apart from one another, and a joint pin (32; 52), which extends between the joint limbs (15, 16) along a longitudinal axis (38; 55) and which determines a pivot axis (38; 55) of the joint arrangement (11; 30; 50), and having a second joint part (18) which is received in regions between the two joint limbs (15, 16) and which is penetrated by a joint recess (31; 51), wherein the joint pin (32; 52) is received in a pivotally movable manner in the joint recess (31; 51), wherein the joint pin (32; 52) and the joint recess (31; 51) have a central contact region (33; 56) with a touching contact between joint pin (32; 52) and the joint recess (31; 51) and clearance regions (36, 37; 57, 58) which adjoin on both sides of the contact region (33; 56) and extend up to the joint limbs (15, 16), at least partially within the joint recess (31; 51) and without touching contact between joint pin (32; 52) and joint recess (31; 51), in order to ensure an exclusively central force transmission between the joint pin (32; 52) and the joint recess (31; 51).

2. The medical device according to claim 1, characterised in that the joint recess (51) is designed as a stepped bore with a centrally arranged guide bore (56) which has a smaller cross-section than the clearance bores (57, 58) adjoining it on both sides.

3. The medical device according to claim 2, characterised in that the joint pin (52) between the joint limbs (15, 16) is formed with a constant profiling.

4. The medical device according to claim 1, characterised in that the joint pin (32) is formed with a centrally arranged guide section (33) which has a larger cross-section than the clearance sections (36, 37) adjoining it on both sides.

5. The medical device according to claim 4, characterised in that the joint recess (31) is designed as a bore with a constant profiling.

6. The medical device according to claim 1, characterised in that the joint pin is designed with a centrally arranged guide section which has a larger cross-section than the clearance sections adjoining it on both sides, and in that the joint recess is designed as a stepped bore with a centrally arranged guide bore which has a smaller cross-section than the clearance bores adjoining it on both sides.

7. The medical device according to claim 1, characterised in that opposing surfaces (43, 44) of the joint limbs (15, 16) form a sliding guide with play with adjacent surfaces (45, 46) of the second joint part (18) and in that the joint pin (32; 52) and the joint recess (31; 51) are matched to one another in such manner that, when the second joint part (18) is tilted relative to the first joint part (17) about a tilting axis aligned transversely to the longitudinal axis (38; 55), there is an exclusively elastic deformation of the joint pin (32; 52).

8. The medical device according to one of the preceding claims, characterised in that an extension of the central contact region (33; 56) in the direction of the longitudinal axis (38; 55) is less than 30 percent, preferably less than 25 percent, of an extension of one of the clearance regions (36, 37; 57, 58) in the direction of the longitudinal axis (38; 55).

9. The medical device according to claim 2 or 3, characterised in that a cross-sectional area of the guide bore (56) is less than 50 percent, preferably less than 40 percent, in particular less than 30 percent, of a cross-sectional area of the clearance bore (57, 58).

10. The medical device according to claim 4 or 5, characterised in that a cross-sectional area of the clearance section (36, 37) is less than 50 percent, preferably less than 40 percent, in particular less than 30 percent, of a cross-sectional area of the guide section (33).