Coupling, and medical instrument having a coupling

Abstract

The present invention relates to a coupling (2) for a medical instrument, comprising: a rotatably drivable rotor shaft (6) and a non-circular shank (4), which has a coupling portion (8) that can be axially inserted into the rotor shaft (6) for form-fittingly torque-transferring coupling; and an orienting portion (18), which matches the rotor shaft (6) such that, during coupling, the non-circular shank (4) is oriented in a predefined rotational position about its longitudinal axis, wherein the orienting portion (18) is axially spaced apart from the coupling portion (8) of the non-circular shank (4) such that, during coupling, the non-circular shank (4) is oriented in the predefined rotational position before the coupling portion (8) of the non-circular shank (4) comes into form-fittingly torque-transferring engagement with the rotor shaft (6). The invention also relates to a medical instrument having such a coupling (2).

Description

[0001] Coupling and medical instrument with coupling Description

[0002] Technical area

[0003] The present disclosure relates to a coupling for a medical instrument, in particular a handheld instrument, for the torque-transmitting connection of a shaft to a rotatably drivable rotor shaft. Furthermore, the present disclosure relates to a medical instrument, in particular a handheld instrument, comprising such a coupling.

[0004] For hand instruments, it is often necessary to be able to establish a detachable, torque-transmitting connection to a rotary-driven rotor shaft in order to be able to convert the rotation directly into the rotation of a tool of the hand instrument or indirectly into a coupled movement, such as bending the tool. Couplings are typically used to create a torque-transmitting connection between two components, allowing the torque to be transmitted, for example, in a form-fitting manner. Such couplings are known, for example, from DE 10 2012 101 259 A1 or DE 10 2021 118412 A1.

[0005] However, with positive torque transmission, it is crucial that the components to be connected are first aligned in a specific rotational position to enable the positive connection to be established. However, depending on the design of the coupling used, this occurs inside the components and thus cannot be visually inspected or controlled. This may require a user to laboriously test the rotational position in which a positive connection can be established, and the user may remain unclear as to whether a coupling engagement has occurred, which in turn can lead to misuse of the handheld instrument. Summary of the Disclosure

[0006] The present disclosure is based on the object of reducing or avoiding disadvantages of the prior art. In particular, a coupling for a medical instrument, in particular a hand-held instrument, and a medical instrument, in particular a hand-held instrument, with such a coupling are to be provided, in which the risk of misuse due to unsuccessful torque-transmitting connection can be eliminated or at least reduced. At the same time, the coupling should be as simple and compact as possible and enable reliable torque transmission.

[0007] The problem underlying the present disclosure is solved by a coupling for an instrument, in particular a hand-held instrument, having the features of patent claim 1 and by an instrument, in particular a hand-held instrument, having the features of the independent patent claim. Advantageous further developments are the subject of the dependent claims and are described in more detail below.

[0008] More specifically, the object is achieved by a coupling for a medical instrument, in particular a handheld instrument, comprising a rotor shaft, preferably rotatably driven by a drive unit designed, for example, as a handpiece, and a shaft shaft. The shaft shaft can, for example, be rotationally coupled to a drive shaft, the rotation of which, in turn, can be coupled to the rotation of a tool or to the angling of the tool.

[0009] The shaft has a coupling section, in particular in the form of a polygonal profile, preferably a hexagon, which can be inserted axially into the rotor shaft for a preferably direct, positive-locking torque-transmitting coupling (A / connection). This means that the rotor shaft has a coupling section complementary to the coupling section of the shaft, in particular in the form of a polygonal profile, preferably a hexagon, with which the coupling section of the shaft is in positive-locking torque-transmitting engagement in the coupled state. In other words, the coupling section of the shaft is for coupling, iefor displacement from an uncoupled state, in which the rotor shaft and the shaft shaft are separated from one another in a torque-transmitting manner / are not connected to one another in a torque-transmitting manner, into a coupled state in which the rotor shaft and the shaft shaft are connected to one another in a torque-transmitting manner, can be inserted axially into the rotor shaft ( / into the coupling section of the rotor shaft). In particular, the shaft shaft and the rotor shaft are connected via a positive-locking shaft-hub connection, preferably via a directly positive-locking shaft-hub connection, such as a polygonal profile / multi-edged profile, a splined shaft profile or a splined shaft profile. This means that the coupling section of the shaft shaft preferably interacts directly with the coupling section of the rotor shaft (i.e. not via radially displaceable locking elements, but via rigid or radially immovable coupling sections) for torque transmission.For example, the coupling section of the shaft can be designed in the shape of an (external) hexagon, and the coupling section of the rotor shaft in the shape of an (internal) hexagon. Alternatively, an indirectly positive shaft-hub connection, such as a keyway, could be used.

[0010] The shaft has an alignment section that is matched to the rotor shaft in such a way that the alignment section aligns the shaft shaft in a predetermined rotational position about its longitudinal axis during coupling, i.e. when the shaft shaft is axially inserted into the rotor shaft. This also means that the rotor shaft has an alignment contour that is complementary to the alignment section of the shaft shaft, along which the alignment section is aligned in the predetermined rotational position during coupling, i.e. when the two coupling sections are axially inserted into one another. In other words, the alignment section of the shaft shaft and the alignment contour of the rotor shaft are designed to match such that the alignment section and the alignment contour can only (fully) engage in one or more specific orientations (relative to the longitudinal axis of the shaft shaft or rotor shaft).For example, the alignment contour is a negative form of the alignment section or has circumferentially distributed contact surfaces for contacting surfaces of the alignment section. Due to the interaction / guidance of the alignment section and the alignment contour, the shaft rotates into the correct position relative to the rotor shaft (i.e., is correctly aligned), so that, in particular, the coupling section of the shaft is aligned to match the coupling section of the rotor shaft.

[0011] According to the present disclosure, the alignment section is axially spaced from the coupling section of the shaft shaft such that the shaft shaft is aligned in the predetermined rotational position during coupling before the coupling section of the shaft shaft comes into positive torque-transmitting engagement with the rotor shaft. This means that the shaft shaft has a spacer section formed axially between the coupling section and the alignment section of the shaft shaft and has such a large axial length that alignment via the alignment section on the alignment contour occurs at a time of axial insertion at which the spacer section (and not yet the coupling section) is located in the axial region of the coupling section of the rotor shaft.Thus, the positive torque-transmitting connection between the two coupling sections does not yet exist before the alignment is completed, since the positive torque-transmitting connection between the two coupling sections would otherwise prevent further relative rotation between the shaft and the rotor shaft, or if the shaft and rotor shaft were not aligned, the coupling process, i.e., further axial insertion, would be blocked. This has the advantage that automatic alignment can be achieved when inserting the shaft into the rotor shaft.

[0012] According to a preferred embodiment, an axial distance between the coupling section and the alignment section of the shaft, i.e., the axial length of the spacing section, can be greater than an axial length of the coupling section of the rotor shaft. This ensures that the alignment can be completed before the coupling section of the shaft shaft axially engages the coupling section of the rotor shaft or, in the absence of alignment, attempts to axially engage it.

[0013] According to a preferred embodiment, the alignment contour can axially connect directly to the coupling section of the rotor shaft in the uncoupled state. This means that in the uncoupled state, there is preferably no distance between the alignment contour and the coupling section of the rotor shaft. This has the advantage that the axial distance between the coupling section and the alignment section of the shaft, i.e., the axial length of the spacing section, only needs to be selected slightly larger than the axial length of the coupling section of the rotor shaft to ensure proper function. Thus, the minimum required length of the shaft can be kept as short as possible.

[0014] According to an alternative embodiment, the alignment contour can be axially spaced from the coupling section of the rotor shaft in the uncoupled state. This means that in the uncoupled state, a (predetermined) distance exists between the alignment contour and the coupling section of the rotor shaft. According to a further development of the alternative embodiment, the axial distance between the coupling section and the alignment section of the shaft, i.e., the axial length of the spacing section, can be greater than the sum of the axial length of the coupling section of the rotor shaft and the (predetermined) distance between the alignment contour and the coupling section of the rotor shaft in the uncoupled state.Thus, even if the (predetermined) distance between the alignment contour and the coupling section of the rotor shaft is present, it can be ensured that the alignment is completed before the coupling section of the shaft shaft axially engages the coupling section of the rotor shaft.

[0015] According to a preferred embodiment, the alignment contour can be formed by an inclined surface that is inclined to the axial and radial directions and forms an acute angle with a longitudinal plane of the rotor shaft, i.e. a longitudinal plane containing the longitudinal axis of the rotor shaft. This means that the alignment contour lies in a plane that is inclined to the longitudinal plane. In other words, the alignment contour is formed on an axially and radially adjusted contact surface. Due to the axial and radial adjustment, the alignment section rotates about the longitudinal axis of the shaft with increasing axial insertion and rests flat against the contact surface. Alternatively, the alignment section of the shaft shaft can also be formed in the form of the inclined surface or a recess complementary thereto.

[0016] According to a preferred embodiment, the alignment section can be pyramid-shaped, i.e., in the form of a pyramid whose central axis corresponds to the longitudinal axis of the shaft. In particular, the number of edges of the coupling section of the shaft can correspond to a number of side faces or a multiple of the number of side faces of the pyramid. This ensures rotational symmetry between the coupling section of the shaft and the alignment section, and thus correct alignment with respect to the coupling section of the shaft. Preferably, the alignment section can be designed in the form of a triangular pyramid. Alternatively, the alignment contour of the rotor shaft can also be formed in the form of the pyramid or a recess complementary thereto.

[0017] According to a preferred embodiment, the coupling can have a follower element that is separate from the rotor shaft and on which the alignment contour is formed. This means that the follower element can also be replaced. This means that the alignment contour is not formed integrally with the rotor shaft. Preferably, the follower element can be accommodated in the rotor shaft so that it can be axially displaceable and connected to the rotor shaft in a rotationally fixed manner. The rotationally fixed connection between the rotor shaft and the follower element can preferably be realized via a flattened portion on the essentially circular outer circumference of the follower element (and a corresponding complementary receptacle on the rotor shaft). The axial displaceability is expedient to prevent the follower element from preventing further axial insertion of the shaft shaft into the rotor shaft after alignment has been completed.

[0018] According to a further development of the preferred embodiment, the tracking element can be axially displaceable against a spring preload. Preferably, the tracking element can be in its spring-preloaded position in the coupled state. This means that the tracking 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 tracking element, i.e., the alignment contour, is pushed toward zero. This ensures that, in the uncoupled state, the tracking element is located at an axial location at which the alignment section can engage the alignment contour.

[0019] According to a preferred embodiment, the coupling can have an insert that is separate from the rotor shaft and on which the coupling section of the rotor shaft is formed. This means that the insert can also be replaced. This means that the coupling section of the rotor shaft is not formed integrally with the rotor shaft. Preferably, the insert can be secured 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 realized via a flattened portion on the essentially circular outer circumference of the insert (and a corresponding complementary receptacle on the rotor shaft). The axial securing is expedient to ensure that the insert, in the uncoupled state, is located at an axial location at which the coupling section of the shaft can engage with the coupling section of the rotor shaft.

[0020] According to a preferred embodiment, the rotor shaft can have a stepped inner diameter, forming an axial contact surface for the insert on an axial side facing away from the shaft. This has the advantage of forming an axial stop for the insert, which limits axial movement of the insert on its axial side facing away from the shaft.

[0021] According to a preferred embodiment, the coupling can have a securing element that is axially fixedly connected to the rotor shaft on an axial side of the insert facing the shaft, preferably via a threaded connection, so that an axial contact surface for the insert is formed on an axial side facing the shaft. This has the advantage that an axial stop is formed for the insert, which limits axial movement of the insert on its axial side facing the shaft. According to a further development of the preferred embodiment, the securing element can preferably have a screw-in geometry, in particular in the form of a (socket) hexagon, for screwing the securing element into the rotor shaft, which has a larger diameter than the coupling section of the shaft. The screw-in geometry provides the possibility of being able to screw the securing element into the rotor shaft.Because the (inner) diameter of the screw-in geometry is larger than an (outer) diameter of the coupling section of the shaft, an alignment of the shaft, in particular a rotation about the longitudinal axis of the shaft, when the coupling section is located in the axial area of ​​the locking element, is not impaired by the locking element.

[0022] According to a preferred embodiment, the alignment section and the alignment contour can each be formed by at least one inclined surface, wherein each of the inclined surfaces is inclined to the axial direction and the radial direction and is designed for flat contact with an inclined surface of the other of the alignment section and the alignment contour, wherein the alignment section and the alignment contour have a different number of inclined surfaces and / or a different orientation of the inclined surfaces about the longitudinal axis. Due to the different shapes of the alignment section and the alignment contour, the flat contact can be supported with increasing axial immersion. In contrast to an exact shape correspondence, which can lead to jamming depending on the rotational position, in particular in a "tooth-on-tooth" position, the axial insertion and rotation are guided smoothly.

[0023] The underlying object of the present disclosure is also achieved by a medical instrument, in particular a handheld instrument. The handheld instrument comprises a described coupling, a drive unit, designed for example as a handpiece, connected to the rotor shaft of the coupling in a torque-transmitting manner, and a drive shaft connected to the shaft shaft in a torque-transmitting manner. The drive shaft can be coupled to a tool in such a way that rotation of the drive shaft causes rotation or bending of the tool. According to a preferred embodiment, the instrument can have a shaft sleeve in which the shaft shaft is received in an axially secured and rotatably mounted manner. Preferably, the coupling has no axial securing means for axially fixedly receiving the shaft shaft in the rotor shaft. This has the advantage that the coupling can be designed to be particularly compact.Due to the axial securing of the shaft in the shaft sleeve, axial securing in the rotor shaft is not absolutely necessary.

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

[0025] In other words, the present disclosure relates to a handpiece with direct torque transmission from a rotor shaft to a tool shaft, including alignment, so that torque is transmitted to a coupled tool or shaft directly via the rotor shaft of the drive unit without additional intermediaries. A mechanism built into the rotor shaft and a special tool or shaft geometry ensure automatic alignment of the rotor shaft and the tool / shaft with respect to one another. Torque transmission can preferably be achieved via a positive fit using a hexagonal geometry. In particular, a special coupling is used for torque transmission between the handpiece and the shaft, which coupling is particularly compact due to its integration into the rotor shaft. For maximum convenience when coupling the shaft, the coupling is designed as a plug-and-play coupling.Specifically, the drive shaft is connected to a coupling section for rotational movement. The drive is provided via a hexagonal shaft. Directly adjacent to this is a cylindrical portion with a pyramid, which is spaced from the hexagon in such a way that automatic alignment occurs before the hexagon engages the rotor shaft insert. It is not necessary to fix the drive shaft axially, so corresponding engagement sections on the coupling section can be eliminated and the installation space can be reduced. The drive shaft is axially secured in the shaft, and the shaft has its own coupling geometry for axial and radial locking.

[0026] The insert can be arranged in particular within, preferably completely within, the rotor shaft. The insert can preferably be arranged at a distal end section of the rotor shaft. The tracking element can be arranged within, in particular completely within, the rotor shaft. The tracking element is preferably arranged proximally from the insert and more preferably axially spaced therefrom. The spring can preferably be arranged proximally from the tracking element or at least partially in a proximal end section of the tracking element and preferably exerts an axial prestressing force on the tracking element. The spring is preferably accommodated within, more preferably completely within, the rotor shaft. In summary, the insert, the rotor shaft and the spring are preferably arranged, preferably completely, within the rotor shaft, more preferably in this order starting from a distal end section of the rotor shaft.In other words, the coupling is integrated into the rotor shaft, resulting in a particularly compact design.

[0027] The coupling section of the shaft is designed in particular such that it can be inserted into the rotor shaft, in particular by means of the insert, in order to engage with the follower element within the rotor shaft or to engage the alignment section within the rotor shaft with the alignment contour.

[0028] Short description of the characters

[0029] Fig. 1 is a schematic representation of a coupling for an instrument according to the present disclosure for torque-transmitting connection between a shaft and a rotor shaft in an uncoupled state,

[0030] Fig. 2 is a perspective view of an insert forming a coupling section of the rotor shaft, Fig. 3 is a perspective view of a follower element forming an alignment contour of the rotor shaft,

[0031] Fig. 4 is a perspective view of a locking element for axially securing the insert,

[0032] Fig. 5 is a schematic representation of the coupling for the torque-transmitting connection between the shaft and the rotor shaft in a coupled state,

[0033] Fig. 6 is a perspective view of the shaft and a shaft receiving the shaft,

[0034] Fig. 7 is a perspective view of the instrument with the coupling according to the present disclosure, and

[0035] Figs. 8 to 11 are different representations of the clutch at different times between the uncoupled state and the coupled state.

[0036] Description of a preferred embodiment

[0037] Fig. 1 shows a coupling 2 for a medical instrument, in particular a handheld instrument, according to the present disclosure. The coupling 2 has a shaft 4 and a rotor shaft 6, which are connected to one another in a torque-transmitting manner when the coupling 2 is coupled, and separated from one another in a torque-transmitting manner when the coupling 2 is uncoupled. For coupling, i.e., for displacement from the uncoupled state to the coupled state, the shaft 4 and the rotor shaft 6 can be axially inserted into one another.

[0038] The shaft 4 has a coupling section 8. In the illustrated embodiment, the coupling section 8 is designed in the form of an external hexagon 10. The coupling section 8 is formed integrally with the shaft 4. Alternatively, the coupling section 8 could also be formed on a component separate from the shaft 4, which is connected to the shaft 4 in a rotationally fixed and axially fixed manner.

[0039] The rotor shaft 6 has a coupling section 12, which is complementary to the coupling section 8 of the shaft 4. In the illustrated embodiment, the coupling section 12 is designed in the form of a hexagon socket 14. In the coupled state, the coupling sections 8, 12 are connected to one another, preferably directly, in a form-fitting manner, in a torque-transmitting manner. The coupling section 12 is formed on an insert 16 separate 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, which is designed as a hollow shaft.

[0040] The shaft 4 has an alignment section 18. The alignment section 18 is formed at one end of the shaft 4, in particular at a proximal end. In the illustrated embodiment, the alignment section 18 is in the form of a pyramid extending in the longitudinal direction of the shaft 4. The pyramid is in the form of a triangular pyramid, i.e. the pyramid has three side surfaces. The alignment section 18 is formed integrally with the shaft 4. Alternatively, the alignment section 18 could also be formed on a component separate from the shaft 4, which is connected to the shaft 4 in a rotationally fixed and axially fixed manner.

[0041] The rotor shaft 6 has an alignment contour 20. The alignment contour 20 serves to receive and align the alignment section 18 in a predetermined rotational position about a longitudinal axis of the shaft 4 or the rotor shaft 6. In particular, the alignment contour 20 is designed such that when the alignment section 18 is axially inserted into the alignment contour 20, the coupling section 8 of the shaft 4 is aligned with the coupling section 12 of the rotor shaft 6. In the illustrated embodiment, the alignment contour 20 is formed in the form of an inclined surface 22 that is inclined to the axial and radial directions. The inclined surface 22 forms an acute angle with a longitudinal plane of the rotor shaft 6, i.e., a plane containing the longitudinal axis of the rotor shaft 6.The alignment contour 20 is formed on a follower element 24 that is separate from the rotor shaft 6 and is rotationally connected to the rotor shaft 6, in particular, it is inserted into the rotor shaft 6, which is designed as a hollow shaft. The follower element 24 is axially displaceably received in the rotor shaft 6 (see Fig. 5).

[0042] In other words, the alignment contour 20 is designed to match the alignment section 18 in such a way that the alignment section 18 and the alignment contour 20 can only (fully) engage in one or more specific orientations. For example, the alignment contour 20 is a negative form of the alignment section 18 or has contact surfaces distributed in the circumferential direction for contacting surfaces of the alignment section 18. Due to the interaction / guidance of the alignment section 18 and the alignment contour 20, the shaft 4 rotates into the correct position relative to the rotor shaft 6 (i.e., is correctly aligned), so that, in particular, the coupling section 8 (i.e., the external hexagon 10) is aligned to match the coupling section 12 (i.e., the internal hexagon 14).

[0043] The shaft 4 has a spacer section 26. The spacer section 26 is arranged axially between the coupling section 8 and the alignment section 18. In particular, the coupling section 8 directly adjoins the spacer section 26 on one side, and the alignment section 18 adjoins the spacer section 26 on the other side. An outer contour of the spacer section 26 is matched to the coupling section 12 of the rotor shaft 6 in such a way that the shaft 4 is freely rotatable relative to the rotor shaft 6 when the spacer section 26 is located axially in the region of the coupling section 12. Preferably, the spacer section 26 can have an outer diameter that is smaller than an inner diameter of the coupling section 12. In the illustrated embodiment, the spacer section 26 is designed in the form of a circular cylinder 28. The spacer section 26 is formed integrally with the shaft 4.Alternatively, the spacing section 26 could also be formed on a component separate from the shaft 4, which is connected to the shaft 4 in a rotationally fixed and axially fixed manner. According to one aspect of the disclosure, the alignment section 18 is axially spaced from the coupling section 8 of the shaft 4 such that upon axial insertion of the shaft 4 into the rotor shaft 6, the shaft 4 is aligned in the predetermined rotational position before the coupling section 8 of the shaft 4 comes into positive torque-transmitting engagement with the coupling section 12 of the rotor shaft 6. In particular, this is achieved in that an axial distance between the coupling section 8 and the alignment section 18 of the shaft 4, i.e. an axial length of the spacing section 26, is greater than an axial length of the coupling section 12 of the rotor shaft 6.

[0044] In the uncoupled state, the alignment contour 20 axially adjoins the coupling section 12 of the rotor shaft 6. This means that the follower element 24 rests against the insert 16 in the uncoupled state (cf. Fig. 1). Alternatively, the alignment contour 20 could also be arranged axially spaced from the coupling section 12 in the uncoupled state. In this case, the axial distance between the coupling section 8 and the alignment section 18 of the shaft 4, i.e. the axial length of the spacer section 26, can be greater than a sum of the axial length of the coupling section 12 of the rotor shaft 6 and an axial distance between the alignment contour 20 and the coupling section 12 of the rotor shaft 6.

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

[0046] Fig. 3 shows a perspective view of the follower element 24. The follower 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 follower element 24, so that the follower element 24 is non-rotatably received in the rotor shaft 6 due to the flattened portion 40.

[0047] Fig. 4 shows a perspective view of a securing element 42. The securing element 42 serves to axially secure the insert 16 in the rotor shaft 6. The securing element 42 is axially fixedly connected to the rotor shaft 6 and arranged on a distal side of the insert 16. An inner diameter of the securing element 42 is smaller than an outer diameter of the insert 16, so that the securing element 42 axially bears against the insert 16 (or the insert 16 cannot be axially guided through the securing element 42). Thus, a distal axial stop for the insert 16 is formed in the rotor shaft 6.

[0048] In the illustrated embodiment, the securing element 42 is designed as a threaded sleeve 44 having an external thread on its outer circumference. The rotor shaft 6 has an inner circumferential section complementary to the external thread, i.e., a corresponding internal thread, so that the threaded sleeve 44 can be screwed into the rotor shaft 6. For screwing the threaded sleeve 44 into the rotor shaft 6, the threaded sleeve 44 has a screw-in geometry 46 on its inner side, which in the illustrated embodiment is designed as a hexagon socket. Preferably, an inner diameter of the screw-in geometry 46 is larger than an outer diameter of the coupling section 8 of the shaft 4, so that the shaft 4 is freely rotatable relative to the rotor shaft 6 when the coupling section 8 is located axially in the region of the screw-in geometry 46. The screw-in geometry 46 increases in size via a funnel section 48 towards its distal end. Fig.Figure 5 shows a longitudinal section of the coupling 2 in the coupled state. With increasing axial insertion of the shaft 4 into the rotor shaft 6, the shaft 4 displaces the follower element 24. The follower element 24 is axially displaceably received in the rotor shaft 6, counter to the spring force of a spring 50. The shaft 4 is inserted into the rotor shaft 6 until the two coupling sections 8, 12 are preferably fully engaged with each other in positive torque engagement. Thus, in the coupled state, the alignment section 18 and the spacer section 16 protrude axially (on a proximal side of the insert 16) beyond the insert 16.

[0049] Fig. 6 shows a perspective view of a shaft sleeve 52 of the instrument, in which a drive shaft 54 ​​is received (centered). The drive shaft 54 ​​is fixedly connected, i.e., torque-transmitting / rotatably and axially fixed, to the shaft shaft 4. The drive shaft 54 ​​is axially secured in the shaft sleeve 52 and rotatably mounted relative to the shaft sleeve 52. The shaft 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 over the circumference, by means of which the shaft sleeve 52 can be secured axially and radially.

[0050] Fig. 7 shows a perspective view of the instrument. It can be seen that a tool 60 is accommodated in the shaft sleeve 52 on a distal side. The tool 60 can preferably be coupled to the drive shaft 54 ​​or to the shaft shaft 4 in a torque-transmitting manner. The shaft sleeve 52 can be coupled to a housing 62, which in turn accommodates a drive unit. The rotor shaft 6 can be driven in rotation by the drive unit.

[0051] Figs. 8 to 11 show a sequence of a coupling process of clutch 2. This means that Figs. 8 to 11 show different representations of clutch 2 at different times between the uncoupled state and the coupled state. In Fig. 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. Clutch 2 is in the uncoupled state.

[0052] In Fig. 9 and Fig. 10, the shaft 4 is axially inserted into the rotor shaft 6 until the alignment section 18 of the shaft 4 comes into contact with the alignment 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 are freely rotatable relative to one another. The coupling 2 is still in the uncoupled state. By axially inserting it, the alignment section 18 is guided along the alignment contour 20 so that the side surfaces abut one another (see in particular the top view in Fig. 10). As a result, the shaft 4 is rotated about its longitudinal axis into the predetermined rotational position.

[0053] In Fig. 11, the shaft 4 is axially inserted into the rotor shaft 6 to such an extent that the alignment contour 20 (in the form of the follower element 24) is pushed back axially 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 positive engagement with each other. The coupling 2 is in the coupled state.

Claims

Claims 1. Coupling (2) for a medical instrument, in particular a hand instrument, with a rotary-driven rotor shaft (6) and a shaft shaft (4) which has a Coupling section (8), in particular in the form of a polygonal profile, preferably a hexagon, which can be inserted axially into the rotor shaft (6) for a preferably direct, positive-locking torque-transmitting coupling, and has an alignment section (18) which is matched to the rotor shaft (6) in such a way that, during coupling, it aligns the shaft shaft (4) in a predetermined rotational position about its longitudinal axis, wherein the alignment section (18) is axially spaced from the coupling section (8) of the shaft shaft (4) in such a way that, during coupling, the shaft shaft (4) is aligned in the predetermined rotational position before the coupling section (8) of the shaft shaft (4) comes into positive-locking torque-transmitting engagement with the rotor shaft (6).

2. Coupling (2) according to claim 1, characterized in that the rotor shaft (6) has a coupling section (12) which is designed complementarily to the coupling section (8) of the shaft shaft (4), in particular in the form of a polygonal profile, preferably a hexagon, with which the coupling section (8) of the shaft shaft (4) is in positive torque-transmitting engagement in a coupled state, wherein an axial distance between the coupling section (8) and the alignment section (18) of the shaft shaft (4) is greater than an axial length of the coupling section (12) of the rotor shaft (6).

3. Coupling (2) according to claim 2, characterized in that the rotor shaft (6) has an alignment contour (20) which is complementary to the alignment section (18) of the shaft shaft (4), along which the alignment section (18) is aligned in the predetermined rotational position during coupling, wherein the alignment contour (20) in an uncoupled state axially adjoins the coupling section (12) of the rotor shaft (6) directly.

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

5. Coupling (2) according to one of claims 1 to 4, characterized in that the alignment section (18) is pyramid-shaped and is preferably designed in the form of a triangular pyramid.

6. Coupling (2) according to one of claims 1 to 5, characterized in that the coupling (2) has a follower element (24) which is separate from the rotor shaft (6), on which follower element the alignment contour (20) is formed and which is received in the rotor shaft (6) in an axially displaceable manner and is connected in a rotationally fixed manner to the rotor shaft (6), preferably via a flattened portion (40) on the substantially circular outer circumference of the follower element (24).

7. Coupling (2) according to claim 6, characterized in that the follower element (24) is axially displaceable against a spring preload and the follower element (24) is in its spring-preloaded position in the coupled state, wherein a spring (50) for applying the spring preload is preferably arranged proximally from the follower element (24) or is at least partially received in a proximal end section of the follower element (24), wherein the spring (50) is further preferably arranged within the rotor shaft (6).

8. Coupling (2) according to one of claims 1 to 7, characterized in that the coupling (2) has an insert (16) which is separate from the rotor shaft (6) and which is arranged inside the rotor shaft (6), preferably distally from the follower element (24), on which insert the coupling section (12) of the rotor shaft (6) is formed and which is secured axially fixed in the rotor shaft (6) and is connected in a rotationally fixed manner to the rotor shaft (6), preferably via a flattened portion (32) on the substantially circular outer circumference of the insert (16).

9. Coupling (2) according to claim 8, characterized in that the coupling (2) has a securing element (42) which is connected axially fixedly to the rotor shaft (6), preferably via a threaded connection, on an axial side of the insert facing the shaft, so that an axial contact surface for the insert (16) is formed on an axial side facing the shaft shaft (4), wherein the securing element (42) preferably has a screw-in geometry (46), in particular a hexagon socket, for screwing the securing element (42) into the rotor shaft (6), which has a larger diameter than the coupling section (8) of the shaft shaft (4).

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

11. Coupling (2) according to 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 alignment section (18) within the rotor shaft (6) into engagement with the alignment contour (20).

12. Coupling (2) according to one of claims 1 to 11, characterized in that the alignment section (18) and the alignment contour (20) are each formed by at least one inclined surface, wherein each of the inclined surfaces is inclined to the axial direction and radial direction and is designed for planar contact with an inclined surface of the other of the alignment section (18) and the alignment contour (20), wherein the alignment section (18) and the alignment contour (20) have a different number of inclined surfaces and / or a different orientation of the inclined surfaces about the longitudinal axis.

13. Medical instrument, in particular hand instrument, with a coupling (2) according to one of claims 1 to 12, a preferably designed as a handpiece, with the rotor shaft of the coupling (2) transmitting torque connected drive unit and a drive shaft (54) connected to the shaft of the coupling (2) in a torque-transmitting manner.

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