Coupling and medical instrument having a coupling

Abstract

The invention relates to a coupling (2) for a medical instrument, comprising a rotatably drivable rotor shaft (6) and a lever shaft (4), which has a coupling section (8) that can be axially pushed into the rotor shaft (6) for a form-fitting torque-transmitting coupling, and an orientation section (18) that is adapted to the rotor shaft (6), the coupling section (8) is axially spaced apart from the shaft shaft (4), and wherein the coupling section (8) is axially spaced apart from the coupling section (8), and wherein the coupling section (8) is axially spaced apart from the coupling section (8), and wherein the coupling section (8) is axially spaced apart from the coupling section (8), and wherein the coupling section (8) is axially spaced apart from the coupling section (8). The coupling section (8) is designed such that the lever shaft (4) is oriented into the predetermined rotational position during the coupling before the coupling section (8) of the lever shaft (4) engages with the rotor shaft (6) in a form-fitting torque-transmitting manner. Furthermore, the present disclosure relates to a medical instrument having such a coupling (2).

Description

Technical Field

[0001] The present disclosure relates to a coupling for a medical instrument, in particular a handheld instrument, which is used to connect a shaft to a rotatably driven rotor shaft in a torque-transmitting manner. In addition, the present disclosure relates to a medical instrument, in particular a handheld instrument, having such a coupling. Background Art

[0002] In handheld instruments, it is often necessary to be able to establish a detachable torque-transmitting connection to a rotatably driven rotor shaft in order to be able to convert the rotation directly into a rotation of a tool of the handheld instrument or indirectly into a coupled movement of the tool, such as bending. For a torque-transmitting connection between two components, a coupling is often used, with which the torque can be transmitted, for example, in a form-locking manner. Such a coupling is known, for example, from DE 10 2012 101 259 A1 or DE 10 2021 118 412 A1.

[0003] However, in the case of a positive-locking torque transmission, it is important that the components to be connected to one another are first oriented to a certain rotational position relative to one another in order to first be able to achieve a positive-locking connection, but this takes place inside the components, depending on the design of the coupling used, and therefore cannot be visually checked or controlled. It is possible that the user must laboriously test in which rotational position a positive-locking connection can be achieved, and the user may not know whether the coupling is engaged, which in turn can lead to incorrect use of the handheld device. Summary of the invention

[0004] The object of the present disclosure is to reduce or avoid the disadvantages of the prior art. In particular, a coupling for a medical instrument, in particular a handheld instrument, and a medical instrument, in particular a handheld instrument, having such a coupling are to be provided, wherein the risk of incorrect use due to an unsuccessful torque-transmitting connection can be eliminated or at least reduced. At the same time, the coupling should be designed as simply and compactly as possible and enable a reliable torque transmission.

[0005] The object on which the present disclosure is based is achieved by a coupling for an instrument, in particular a handheld instrument, having the features of claim 1 and by an instrument, in particular a handheld instrument, having the features of the coordinated claim. Advantageous developments are the subject matter of the dependent claims and are described in more detail below.

[0006] More specifically, the object is achieved by a coupling for a medical instrument, in particular a handheld instrument, which has a rotor shaft and a shaft that can be rotatably driven, preferably by a drive unit, which is designed, for example, as a handpiece. The shaft can be rotationally coupled to a drive shaft, for example, and the rotation of the drive shaft can in turn be coupled to the rotation of a tool or to the bending of the tool.

[0007] The shaft has a coupling section, in particular in the form of a polygonal profile, preferably a hexagon, which can be axially inserted into the rotor shaft for a preferably direct positive-locking torque-transmitting coupling ( / connection). That is, the rotor shaft has a coupling section, in particular in the form of a polygonal profile, preferably a hexagon, which is complementary to the coupling section of the shaft, in the coupled state, and the coupling section of the shaft engages with the coupling section in a positive-locking, torque-transmitting manner. In other words, the coupling section of the shaft for coupling, i.e. for moving from an uncoupled state, in which the rotor shaft and the shaft are separated from each other in a torque-transmitting manner or are not connected to each other in a torque-transmitting manner, into a coupled state, in which the rotor shaft and the shaft are connected to each other in a torque-transmitting manner, can be axially inserted into the rotor shaft (or the coupling section of the rotor shaft). In particular, the shaft and the rotor shaft are connected by a positive-locking hub connection, preferably by a direct positive-locking hub connection, for example a polygonal profile / polygonal profile, a spline shaft profile or a toothed shaft profile. That is, the coupling section of the shaft preferably cooperates directly with the coupling section of the rotor shaft (that is, not via a radially displaceable latching element, but via a rigid or radially non-displaceable coupling section) for the transmission of torque. For example, the coupling section of the shaft can be designed in the form of an (external) hexagon and the coupling section of the rotor shaft can be designed in the form of an (internal) hexagon. Alternatively, an indirect positive-locking shaft-hub connection, such as a parallel key connection, can be used.

[0008] The shaft has an orientation section, which is coordinated with the rotor shaft in such a way that the orientation section orients the shaft about its longitudinal axis into a predetermined rotational position during coupling, that is, when the shaft is axially inserted into the rotor shaft. That is, the rotor shaft has an orientation contour that is complementary to the orientation section of the shaft, along which the orientation section is oriented into a predetermined rotational position during coupling, that is, when the two coupling sections are axially inserted into each other. In other words, the orientation section of the shaft and the orientation contour of the rotor shaft are adaptively configured in such a way that the orientation section and the orientation contour can only (completely) enter into engagement in one or more specific orientations (with respect to the longitudinal axis of the shaft or rotor shaft). For example, the orientation contour is the inverse of the orientation section or has contact surfaces distributed in the circumferential direction for contacting the surface of the orientation section. Due to the cooperation / guidance of the orientation section and the orientation contour, the shaft is rotated into the correct position relative to the rotor shaft (ie, azimuthally correctly oriented), so that in particular the coupling section of the shaft is oriented in a matching manner with the coupling section of the rotor shaft.

[0009] According to the disclosure, the orientation section is axially spaced apart from the coupling section of the shaft so that the shaft is oriented to a predetermined rotational position during coupling before the coupling section of the shaft and the rotor shaft enter into a form-locking torque-transmitting engagement. That is, the shaft has a spacing section, which is axially constructed between the coupling section and the orientation section of the shaft and has such a large axial length that the orientation is carried out by the orientation section at the time of axial insertion of the spacing section (and not yet the coupling section) in the axial region of the coupling section of the rotor shaft on the orientation contour. Therefore, before the end of this orientation, the form-locking torque-transmitting connection between the two coupling sections does not yet exist, because otherwise the form-locking torque-transmitting connection between the two coupling sections would prevent further relative rotation between the shaft and the rotor shaft, or would prevent the coupling process, that is, further axial insertion, when there is no orientation between the shaft and the rotor shaft. This has the advantage that automatic orientation can be achieved when the shaft is inserted into the rotor shaft.

[0010] According to a preferred embodiment, the axial distance between the coupling section and the orientation section of the shaft, i.e. the axial length of the spacing section, can be greater than the axial length of the coupling section of the rotor shaft. This ensures that the orientation can be completed before the coupling section of the shaft is axially embedded in the coupling section of the rotor shaft or before axial embedding is attempted in the absence of orientation.

[0011] According to a preferred embodiment, the orientation contour can be directly connected axially to the coupling section of the rotor shaft in the uncoupled state. That is, in the uncoupled state, there is preferably no distance between the orientation contour and the coupling section of the rotor shaft. This has the advantage that the axial distance between the coupling section and the orientation section of the shaft, that is, the axial length of the spacing section, must be selected only slightly greater than the axial length of the coupling section of the rotor shaft in order to ensure the function. The required length of the shaft can thus be kept as short as possible.

[0012] According to an alternative embodiment, the orientation contour can be axially spaced apart from the coupling section of the rotor shaft in the uncoupled state. That is, in the uncoupled state, there is a (predetermined) distance between the orientation contour and the coupling section of the rotor shaft. According to a refinement of the alternative embodiment, the axial distance between the coupling section and the orientation section of the shaft, that is, the axial length of the spacing section is greater than the sum of the axial length of the coupling section of the rotor shaft in the uncoupled state and the (predetermined) distance between the coupling section of the rotor shaft and the orientation contour. Therefore, even when there is a (predetermined) distance between the orientation contour and the coupling section of the rotor shaft, it can be ensured that the orientation is completed before the coupling section of the shaft is axially embedded in the coupling section of the rotor shaft.

[0013] According to a preferred embodiment, the orientation contour can be formed by an inclined surface, which is inclined relative to the axial direction and the radial direction and encloses an acute angle with the longitudinal plane of the rotor shaft (i.e., the longitudinal plane including the longitudinal axis of the rotor shaft). This means that the orientation contour is in a plane that is inclined relative to the longitudinal plane. In other words, the orientation contour is constructed at an axially and radially inclined contact surface. Due to the axial and radial inclination, the orientation section rotates around the longitudinal axis of the shaft with increasing axial insertion and contacts the contact surface in a planar manner. Alternatively, the orientation section of the shaft can also be formed in the form of an inclined surface or a recess complementary thereto.

[0014] According to a preferred embodiment, the orientation section can be pyramidal, that is to say constructed in the form of a pyramid, the center axis of which corresponds to the longitudinal axis of the shaft. In particular, the number of sides of the coupling section of the shaft can correspond to the number of sides of the pyramid or a multiple of the number of sides. Thus, the rotational symmetry between the coupling section of the shaft and the orientation section and thus the correct orientation of the coupling section with respect to the shaft can be ensured. Preferably, the orientation section can be constructed in the form of a triangular pyramid. Alternatively, the orientation contour of the rotor shaft can also be formed in the form of a pyramid or a recess complementary thereto.

[0015] According to a preferred embodiment, the coupling portion can have a driven element separated from the rotor shaft, on which an orientation profile is constructed. Therefore, the driven element can also be replaced. That is to say, the orientation profile is not constructed integrally with the rotor shaft. The driven element can preferably be accommodated in the rotor shaft axially movably and connected to the rotor shaft in a rotationally fixed manner. The rotationally fixed connection between the rotor shaft and the driven element can preferably be achieved by a flattened portion on the approximately circular outer circumference of the driven element (and a corresponding complementary receiving portion on the rotor shaft). Axial movability is suitable in order to avoid that the driven element does not prevent the rod shaft from being further axially pushed into the rotor shaft after successful orientation.

[0016] According to a refinement of the preferred embodiment, the driven element can be axially displaceable against the spring preload. The driven element can preferably be in its spring preloaded position in the coupled state. That is, the driven element is pressed axially toward the coupling section of the rotor shaft due to the spring preload, so that the axial distance between the coupling section of the rotor shaft and the driven element, that is, the orientation contour, is pressed toward zero. It is thus ensured that the driven element is in an axial position in the uncoupled state in which the orientation section can engage in the orientation contour.

[0017] According to a preferred embodiment, the coupling portion may have an insert separated from the rotor shaft, on which the coupling section of the rotor shaft is constructed. Therefore, the insert can also be replaced. That is, the coupling section of the rotor shaft is not integrally constructed on the rotor shaft. Preferably, the insert can be axially fixed in the rotor shaft and connected to the rotor shaft in a rotationally fixed manner. The rotationally fixed connection between the rotor shaft and the insert can preferably be achieved by a flattened portion on the approximately circular outer circumference of the insert (and a corresponding complementary receiving portion on the rotor shaft). Axial fixing is advantageous in order to ensure that the insert is in such an axial position in the uncoupled state, at which the coupling section of the shaft can be embedded in the coupling section of the rotor shaft.

[0018] According to a preferred embodiment, the rotor shaft can have a stepped inner diameter so that an axial contact surface for the insert is formed on the axial side facing away from the shaft. This has the advantage that an axial stop is formed for the insert, which limits the axial movement of the insert on its axial side facing away from the shaft.

[0019] According to a preferred embodiment, the coupling can have a fastening element which is axially fixedly connected to the rotor shaft on the axial side of the insert facing the shaft, preferably by a screw connection, so that an axial contact surface for the insert is formed on the axial side facing the shaft. This has the advantage that an axial stop is formed for the insert, which limits the axial movement of the insert on its axial side facing the shaft.

[0020] According to a development of a preferred embodiment, the fixing element can preferably have a screw-in geometry, in particular in the form of an (inner) hexagon, for screwing the fixing element into a rotor shaft, which has a larger diameter than the coupling section of the shaft. This screw-in geometry provides the possibility of screwing the fixing element into the rotor shaft. Since the (inner) diameter of the screw-in geometry is greater than the (outer) diameter of the coupling section of the shaft, the orientation of the shaft, in particular the rotation about the longitudinal axis of the shaft, is not adversely influenced by the fixing element when the coupling section is in the axial region of the fixing element.

[0021] According to a preferred embodiment, the orientation section and the orientation profile can each be formed by at least one inclined surface, wherein each of the inclined surfaces is inclined in the axial direction and in the radial direction and is configured to flatly abut against the inclined surface of a respective other of the orientation sections and the orientation profiles, wherein the orientation section and the orientation profile have a different number of inclined surfaces and / or different orientations of the inclined surfaces about the longitudinal axis. By means of the different shapes of the orientation section and the orientation profile, a flat abutment can be supported with increasing axial embedding. In contrast to an exact form correspondence, in which jamming may occur depending on the rotational position, in particular in a "tooth-to-tooth" position, the axial insertion and rotation are gently guided.

[0022] The basic object of the present disclosure is also achieved by a medical instrument, in particular a handheld instrument. The handheld instrument has a coupling as described, a drive unit, for example, configured as a handpiece, connected to a rotor shaft of the coupling in a torque-transmitting manner, and a drive shaft connected to a shaft in a torque-transmitting manner. The drive shaft can be coupled to a tool in such a way that a rotation of the drive shaft causes a rotation or bending of the tool.

[0023] According to a preferred embodiment, the device can have a rod sleeve in which the shaft is accommodated in an axially fixed and rotatable manner. Preferably, the coupling has no axial fixing for accommodating the shaft in an axially fixed manner in the rotor shaft. This has the advantage that the coupling can be designed particularly compactly. Due to the axial fixing of the shaft in the rod sleeve, axial fixing in the rotor shaft is not absolutely necessary.

[0024] According to a preferred embodiment, the device can have a housing in which the drive unit is (axially fixed) accommodated. Preferably, the rod sleeve can have a rod coupling for axial and radial / rotationally fixed connection with the housing. The axial fixation of the shaft can thus be achieved indirectly via the rod sleeve and the housing.

[0025] In other words, the present disclosure relates to a handpiece having a direct transmission of torque from a rotor shaft to a tool rod, including orientation, so that the transmission of torque to a coupled tool or coupled rod is carried out directly through the rotor shaft of the drive unit without any additional intermediate connection. Here, a mechanical device constructed in the rotor shaft and a special tool geometry or rod geometry are used for the automatic orientation of the rotor shaft and the tool / rod to each other. Preferably, the transmission of torque can be carried out in a form-locking manner through a hexagonal geometry. In particular, in order to transmit torque between the handpiece and the rod, a special coupling is used, which is particularly compact due to its integration in the rotor shaft. For maximum comfort when coupling the rod, the coupling is designed as a plug-and-play coupling. Specifically, the drive shaft is connected to the coupling section in a rotationally fixed manner. The drive is achieved through a hexagonal rod. This is followed by a cylindrical part with a pyramid, which is spaced apart from the hexagon so that an automatic orientation is carried out before the hexagon is embedded in the insert of the rotor shaft. There is no need to axially fix the drive shaft, so that a corresponding engagement section on the coupling section can be omitted and the installation space can be reduced. The drive shaft is axially fixed in the rod and the rod has a special coupling geometry for axial and radial fixing.

[0026] The insert can be arranged in particular inside the rotor shaft, preferably completely inside the rotor shaft. The insert can preferably be arranged on the distal end section of the rotor shaft. The driven element can be arranged inside the rotor shaft, in particular completely inside the rotor shaft. The driven element is preferably arranged near the insert and is more preferably axially spaced apart from the insert. The spring can preferably be arranged near the driven element or at least partially in the proximal end section of the driven element, and preferably applies an axial preload to the driven element. The spring is preferably accommodated inside the rotor shaft, further preferably completely inside the rotor shaft. In general, the insert, the rotor shaft and the spring are preferably arranged completely inside the rotor shaft, further preferably in a sequence starting from the distal end section of the rotor shaft. In other words, the coupling is integrated into the rotor shaft. A particularly compact structural form is thereby achieved.

[0027] The coupling section of the shaft is designed in particular such that it can be inserted into the rotor shaft, in particular via an insert, in order to engage with the output element within the rotor shaft or to engage an orientation section within the rotor shaft with an orientation contour. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of a coupling for a machine according to the present disclosure for a torque-transmitting connection between a shaft shaft and a rotor shaft in an uncoupled state,

[0029] Figure 2 is a perspective view of an insert forming a coupling section of a rotor shaft,

[0030] Figure 3 is a perspective view of the driven element forming the orientation profile of the rotor shaft,

[0031] Figure 4 is a three-dimensional view of the fixing element for axially fixing the insert,

[0032] Figure 5 is a schematic diagram of a coupling portion for connecting and transmitting torque between the rod shaft and the rotor shaft in a coupled state,

[0033] Figure 6 is a three-dimensional view of the rod shaft and the rod that accommodates the rod shaft,

[0034] Figure 7 is a perspective view of an apparatus having a coupling according to the present disclosure, and

[0035] Figures 8 to 11 are different views of the coupling at different points in time between an uncoupled state and a coupled state. DETAILED DESCRIPTION

[0036] Figure 1 A coupling 2 for a medical instrument, in particular a handheld instrument, according to the disclosure is shown. The coupling 2 has a shaft 4 and a rotor shaft 6, which are connected to one another in a torque-transmitting manner in the coupled state of the coupling 2 and are separated from one another in a torque-transmitting manner in the uncoupled state of the coupling 2. For coupling, that is, for shifting from the uncoupled state into the coupled state, the shaft 4 and the rotor shaft 6 can be pushed axially into one another.

[0037] The shaft 4 has a coupling section 8. In the embodiment shown, the coupling section 8 is designed in the form of an outer hexagon 10. The coupling section 8 is designed integrally with the shaft 4. Alternatively, the coupling section 8 can also be designed on a component separate from the shaft 4, which is connected to the shaft 4 in a rotationally fixed and axially fixed manner.

[0038] The rotor shaft 6 has a coupling section 12 which is designed to be complementary to the coupling section 8 of the shaft 4. In the embodiment shown, the coupling section 12 is designed in the form of an inner hexagon 14. In the coupled state, the coupling sections 8, 12 are preferably directly connected to each other in a form-locking manner to transmit torque. The coupling section 12 is formed on an insert 16 which is separate from the rotor shaft 6 and is connected to the rotor shaft 6 in a rotationally fixed manner, in particular inserted into the rotor shaft 6 which is designed as a hollow shaft.

[0039] The shaft 4 has an orientation section 18. The orientation section 18 is configured on the end of the shaft 4, in particular on the proximal end. In the illustrated embodiment, the orientation section 18 is configured in the form of a pyramid extending in the longitudinal direction of the shaft 4. The pyramid is configured in the form of a triangular pyramid, that is, the pyramid has three sides. The orientation section 18 is configured integrally with the shaft 4. Alternatively, the orientation section 18 can also be configured on a component separate from the shaft 4, which is connected to the shaft 4 in a rotationally fixed manner and axially fixed.

[0040] The rotor shaft 6 has an orientation contour 20. The orientation contour 20 is used to accommodate and orient the orientation section 18 to a predetermined rotational position around the longitudinal axis of the shaft 4 or the rotor shaft 6. In particular, the orientation contour 20 is configured so that when the orientation section 18 is axially pushed into the orientation contour 20, the coupling section 8 of the shaft 4 is oriented relative to the coupling section 12 of the rotor shaft 6. In the embodiment shown, the orientation contour 20 is formed in the form of an inclined surface 22, which is inclined relative to the axial direction and the radial direction. The inclined surface 22 forms an acute angle with the longitudinal plane of the rotor shaft 6, that is, the plane including the longitudinal axis of the rotor shaft 6. The orientation contour 20 is constructed on a driven element 24 separated from the rotor shaft 6, which is connected to the rotor shaft 6 in a rotationally fixed manner, in particular, is inserted into the rotor shaft 6 configured as a hollow shaft. The driven element 24 is axially displaceably accommodated in the rotor shaft 6 (see Figure 5 ).

[0041] In other words, the orientation contour 20 is configured to be adapted to the orientation section 18 in such a way that the orientation section 18 and the orientation contour 20 can only (completely) engage in one or more specific orientations. For example, the orientation contour 20 is the inverse of the orientation section 18 or has contact surfaces distributed in the circumferential direction for contacting the surface of the orientation section 18. Due to the cooperation / guidance of the orientation section 18 and the orientation contour 20, the shaft 4 is rotated into the correct position relative to the rotor shaft 6 (that is, azimuthally correctly oriented), so that in particular the coupling section 8 (that is, the outer hexagon 10) is oriented in a matching manner with the coupling section 12 (that is, the inner hexagon 14).

[0042] The shaft 4 has a spacer section 26. The spacer section 26 is arranged axially between the coupling section 8 and the orientation section 18. In particular, the coupling section 8 is directly connected to the spacer section 26 on one side and the orientation section 18 is directly connected to the spacer section 26 on the other side. The outer contour of the spacer section 26 is coordinated with the coupling section 12 of the rotor shaft 6, so that when the spacer section 26 is axially in the region of the coupling section 12, the shaft 4 can rotate freely relative to the rotor shaft 6. Preferably, the spacer section 26 can have an outer diameter that is smaller than the inner diameter of the coupling section 12. The spacer section 26 is constructed in the form of a cylinder 28 in the embodiment shown. The spacer section 26 is constructed integrally with the shaft 4. Alternatively, the spacer section 26 can also be constructed on a component separate from the shaft 4, which is connected to the shaft 4 in a rotationally fixed and axially fixed manner.

[0043] According to one aspect of the disclosure, the orientation section 18 is axially spaced apart from the coupling section 8 of the shaft 4, so that when the shaft 4 is axially inserted into the rotor shaft 6, the shaft 4 is oriented in a predetermined rotational position before the coupling section 8 of the shaft 4 and the coupling section 12 of the rotor shaft 6 enter into a form-locking, torque-transmitting engagement. This is achieved in particular by the axial distance between the coupling section 8 and the orientation section 18 of the shaft 4, i.e., the axial length of the spacing section 26 being greater than the axial length of the coupling section 12 of the rotor shaft 6.

[0044] In the uncoupled state, the orientation contour 20 is directly connected to the coupling section 12 of the rotor shaft 6 in the axial direction. That is, the driven element 24 rests on the insert 16 in the uncoupled state (see Figure 1 ). Alternatively, the orientation contour 20 can also be arranged in the uncoupled state axially spaced apart from the coupling section 12. In this case, the axial distance between the coupling section 8 and the orientation section 18 of the shaft 4, that is, the axial length of the spacing section 26 can be greater than the sum of the axial length of the coupling section 12 of the rotor shaft 6 and the axial distance between the orientation contour 20 and the coupling section 12 of the rotor shaft 6.

[0045] Figure 2The insert 16 is shown in a perspective view. The insert 16 has a first, approximately circular outer circumference section 30, on which a flattened portion 32 is formed. The rotor shaft 6 has a first, inner circumference section complementary to the first outer circumference section 30 of the insert 16, so that the insert 16 is received in the rotor shaft 6 in a rotationally fixed manner due to the flattened portion 32. The insert 16 has a second, approximately circular outer circumference section 34, which has a larger diameter than the first outer circumference section 30, so that a radial step with an axial contact surface 36 is formed axially between the two outer circumference sections 30, 34. The rotor shaft 6 has a second, inner circumference section complementary to the second outer circumference section 32 of the insert 16, so that the insert 16 rests on the rotor shaft 6 with its axial contact surface 36. Thus, a proximal axial stop for the insert 16 is formed in the rotor shaft 6.

[0046] Figure 3 The output element 24 is shown in a perspective view. The output element 24 has a substantially circular outer circumferential section 38, on which a flattened portion 40 is formed. The rotor shaft 6 has an inner circumferential section complementary to the outer circumferential section 38 of the output element 24, so that the output element 24 is received in the rotor shaft 6 in a rotationally fixed manner due to the flattened portion 40.

[0047] Figure 4 A perspective view of a fixing element 42 is shown. The fixing element 42 serves to fix the insert 16 axially in the rotor shaft 6. The fixing element 42 is connected to the rotor shaft 6 in an axially fixed manner and is arranged on the distal side of the insert 16. The inner diameter of the fixing element 42 is smaller than the outer diameter of the insert 16, so that the fixing element 42 rests axially on the insert 16 (or the insert 16 cannot be guided axially through the fixing element 42). Therefore, a distal axial stop for the insert 16 is formed in the rotor shaft 6.

[0048] In the embodiment shown, the fixing element 42 is configured as a threaded sleeve 44, which has an external thread on its outer circumference. The rotor shaft 6 has an inner circumference section complementary to the external thread, that is to say a corresponding internal thread, so that the threaded sleeve 44 can be screwed into the rotor shaft 6. In order to screw the threaded sleeve 44 into the rotor shaft 6, the threaded sleeve 44 has a screw-in geometry 46 on its inner side, which is configured as an inner hexagon in the embodiment shown. Preferably, the inner diameter of the screw-in geometry 46 is larger than the outer diameter of the coupling section 8 of the shaft 4, so that when the coupling section 8 is axially in the region of the screw-in geometry 46, the shaft 4 can rotate freely relative to the rotor shaft 6. The screw-in geometry 46 increases toward its distal end via a funnel section 48.

[0049] Figure 5The longitudinal section of the coupling 2 in the coupled state is shown. As the shaft 4 is gradually pushed axially into the rotor shaft 6, the shaft 4 moves the driven element 24. The driven element 24 can be accommodated in the rotor shaft 6 in an axially movable manner against the spring force of the spring 50. The shaft 4 is pushed into the rotor shaft 6 until the two coupling sections 8, 12 are preferably completely in a form-locking torque engagement with each other. Therefore, in the coupled state, the orientation section 18 and the spacing section 16 (on the proximal side of the insert 16) protrude axially beyond the insert 16.

[0050] Figure 6 A three-dimensional view of a rod sleeve 52 of an instrument is shown, in which a drive shaft 54 ​​is (centrally) accommodated. The drive shaft 54 ​​is connected to the rod shaft 4 in a fixed manner, i.e., in a torque-transmitting / rotationally fixed manner and axially fixed. The drive shaft 54 ​​is axially fixed in the rod sleeve 52 and is rotatably supported relative to the rod sleeve 52. The rod sleeve 52 has an axial coupling geometry 56 (here in the form of a circumferential groove) and a radial coupling geometry 58 (here in the form of two axial projections distributed on the circumference), by which the rod sleeve 52 can be fixed axially and radially.

[0051] Figure 7 A stereoscopic view of the instrument is shown. It can be seen here that on the distal side, the tool 60 is accommodated in the rod sleeve 52. The tool 60 can preferably be coupled to the drive shaft 54 ​​or to the rod shaft 4 in a torque-transmitting manner. The rod sleeve 52 can be coupled to a housing 62, in which a drive unit is accommodated. Here, the rotor shaft 6 can be driven in rotation by the drive unit.

[0052] Figures 8 to 11 2 shows the flow of the coupling process of the coupling unit 2. That is, Figure 8-11 Different views of the coupling 2 are shown at different points in time between the uncoupled state and the coupled state.

[0053] exist Figure 8 The shaft 4 has not yet been axially inserted into the rotor shaft 6. The shaft 4 and the rotor shaft 6 are freely rotatable relative to each other. The coupling 2 is in an uncoupled state.

[0054] exist Fig. 9 and Fig.10 In the embodiment of the present invention, the shaft 4 is axially pushed into the rotor shaft 6 so that the orientation section 18 of the shaft 4 is in contact with the orientation contour 20 of the rotor shaft 6. The coupling section 8 of the shaft 4 is not yet in the axial region of the coupling section 12 of the rotor shaft 6. The shaft 4 and the rotor shaft 6 can rotate freely relative to each other. The coupling 2 is still in the uncoupled state. By axially pushing in, the orientation section 18 is guided along the orientation contour 20 so that the sides are in contact with each other (see in particular Fig.10 As a result, the shaft 4 is rotated about its longitudinal axis into a predetermined rotational position.

[0055] exist Fig.11 In the embodiment of the present invention, the shaft 4 is axially pushed into the rotor shaft 6, so that the orientation contour 20 (in the form of the driven element 24) is axially pushed back against the spring preload. The coupling section 8 of the shaft 4 is located in the axial region of the coupling section 12 of the rotor shaft 6. The shaft 4 and the rotor shaft 6 are in a form-locking engagement with each other. The coupling 2 is in the coupled state.

Claims

1. A coupling (2) for a medical instrument, in particular a handheld instrument, A rotatably drivable rotor shaft (6) and a shaft (4), the shaft having a coupling section (8) having a polygonal contour, preferably a hexagonal shape, and an orientation section (18), which can be axially inserted into the rotor shaft (6) for a coupling that preferably transmits torque directly in a positive locking manner, the orientation section being coordinated with the rotor shaft (6) in such a way that, during coupling, it orients the shaft (4) about its longitudinal axis into a predetermined rotational position, in, The orientation section (18) is axially spaced apart from the coupling section (8) of the shaft (4) so ​​that the shaft (4) is oriented into the predetermined rotational position during the coupling before the coupling section (8) of the shaft (4) engages with the rotor shaft (6) in a form-locking, torque-transmitting manner.

2. The coupling portion (2) according to claim 1, characterized in that: The rotor shaft (6) has a coupling section (12) which is complementary to the coupling section (8) of the shaft (4), in particular with a polygonal contour, preferably in the form of a hexagon, with which the coupling section (8) of the shaft (4) engages in a positively locking, torque-transmitting manner in the coupled state, The axial distance between the coupling section (8) and the orientation section (18) of the shaft (4) is greater than the axial length of the coupling section (12) of the rotor shaft (6).

3. The coupling portion (2) according to claim 2, characterized in that: The rotor shaft (6) has an orientation contour (20) which is designed complementary to an orientation section (18) of the shaft shaft (4), and the orientation section (18) is oriented along the orientation contour when coupled into a predetermined rotational position. The orientation contour (20) in the uncoupled state directly adjoins the coupling section (12) of the rotor shaft (6) in the axial direction.

4. The coupling part (2) according to any one of claims 1 to 3, characterized in that: The orientation contour (20) is formed by an inclined surface (22) which is inclined relative to the axial direction and the radial direction and which encloses an acute angle with a longitudinal plane of the rotor shaft (6).

5. The coupling part (2) according to any one of claims 1 to 4, characterized in that: The orientation section (18) is pyramidal and is preferably designed in the form of a triangular pyramid.

6. The coupling part (2) according to any one of claims 1 to 5, characterized in that: The coupling (2) has a driven element (24) which is separate from the rotor shaft (6), on which the orientation contour (20) is formed and which is accommodated axially displaceably in the rotor shaft (6) and is connected to the rotor shaft (6) in a rotationally fixed manner, preferably via a flattened portion (40) on the approximately circular outer circumference of the driven element (24).

7. The coupling part (2) according to claim 6, characterized in that: The driven element (24) is axially movable against a spring preload and is in its spring-preloaded position in a coupled state, wherein preferably, a spring (50) for applying the spring preload is arranged proximally of the driven element (24) or is at least partially accommodated in an end section proximal to the proximal side of the driven element (24), wherein the spring (50) is further preferably arranged within the rotor shaft (6).

8. The coupling part (2) according to any one of claims 1 to 7, characterized in that: The coupling (2) has an insert (16) which is separate from the rotor shaft (6), is arranged inside the rotor shaft (6), preferably on the far side of the driven element (24), on which a coupling section (12) of the rotor shaft (6) is formed and the driven element is axially fixedly fixed in the rotor shaft (6) and is preferably connected to the rotor shaft (6) in a rotationally fixed manner via a flattened portion (32) on the approximately circular outer circumference of the insert (16).

9. The coupling part (2) according to claim 8, characterized in that: The coupling (2) has a fixing element (42) which is axially fixedly connected to the rotor shaft (6) on the axial side of the insert facing the shaft, preferably by a screw connection, so that an axial contact surface for the insert (16) is formed on the axial side facing the shaft (4). The fastening element (42) preferably has a screw-in geometry (46), in particular a hexagonal shape, for screwing the fastening element (42) into a rotor shaft (6) having a larger diameter than the coupling section (8) of the shaft (4).

10. The coupling portion (2) according to claim 8, characterized in that: The insert (16) and the output element (24) are preferably arranged completely within the rotor shaft (6), wherein the insert (16) is preferably arranged distally of the output element (24), more preferably at a distal end section of the rotor shaft (6).

11. The coupling part (2) according to any one of claims 3 to 7, characterized in that: The coupling section (8) of the shaft (4) is designed such that it can be inserted into the rotor shaft (6), in particular through the insert (16), in order to bring the orientation section (18) in the rotor shaft (6) into engagement with the orientation contour (20).

12. The coupling part (2) according to any one of claims 1 to 11, characterized in that: The orientation section (18) and the orientation profile (20) are each formed by at least one inclined surface, wherein each of the inclined surfaces is inclined in an axial direction and in a radial direction and is configured to lie flat against an inclined surface of the respective other of the orientation section (18) and the orientation profile (20), wherein the orientation section (18) and the orientation profile (20) have a different number of inclined surfaces and / or different orientations of the inclined surfaces about the longitudinal axis.

13. A medical instrument, in particular a handheld instrument, comprising a coupling part (2) according to any one of claims 1 to 12, a drive unit preferably constructed as a handheld part connected to the rotor shaft of the coupling part (2) in a torque-transmitting manner, and a drive shaft (54) connected to the rod shaft of the coupling part (2) in a torque-transmitting manner.

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