Medical or dental-medical handpiece having a rotary part mounted in a roller bearing

#The invention relates to a medical or dental-medical handpiece according to the preamble of claim 1.

#A medical or dental-medical handpiece is an object which is put to use for working the human body or natural or artificial parts thereof, such as prostheses, with a tool. The tool is in most configurations a material removing tool which acts on the body with a rotational movement or with a movement going back and forth. As drive there serves a rotational motor which may be arranged in the handpiece itself or in a so-called connection part with which the handpiece is releasably connected by means of a plug-in, in particular a plug-in/turn coupling having a coupling recess in one the one part and a coupling pin, engaging the coupling recess, on the other part. Also in the presence of a back and forth going tool drive, the drive movement is derived from a rotary movement which at least one rotary part carries out and for this purpose is rotatably mounted in the inner ring of a roller bearing having the inner ring and an outer ring. For axially positioning the inner ring and/or the outer ring of the roller bearing it is usual to provide shoulder surfaces on which the roller bearing ring concerned bears and thus is restricted against an axial movement.

#It is further known to provide, for the axial sealing of the gap between an outer ring and a bearing bushinging surrounding it, a sealing ring of elastic material which sits in an inner ring groove in the inner surface of the bearing bushinging and presses elastically against the outer surface of the outer ring. Such a configuration can be taken for example from WO 01/01879 A1. Here, there is also involved the type of construction of a handpiece indicated in the introduction. The arrangement of shoulder surfaces for the axial restriction of an outer ring and/or inner ring of the roller bearing makes the construction of a handpiece of the kind concerned more difficult, since because of the at least one shoulder surface in each case a particular installation and removal direction is predetermined for the roller bearing.

#Below, advantageous configurations of the invention will be described in more detail with reference to exemplary embodiments and drawings.

#There is shown:

#FIG. 1 a handpiece in accordance with the invention, in a side view, which together with a so-called connection part forms a treatment instrument;

#The treatment instrument, designated in its entirety by 1 in FIG. 1, consists of a rearward instrument part, namely a so-called connection part 2, and a forward instrument part, namely the so-called handpiece 3, which are releasably connected with one another by means of a coupling 4 in particular a plug-in coupling, preferably a plug-in/turn coupling. With the present exemplary embodiment there is arranged at the forward end of the treatment instrument 1 a holder device 5 for a tool 6, whereby the tool 6 may stand out to the side or forwardly. The handpiece may extend straight (not illustrated) or curved (indicated by chain lines) to the side away from the tool 6, or angle shaped. The plug-in/turn coupling is formed by means of a coupling recess 7, round in cross-section, and in coupling pin 8 which can be inserted therein with slight play for movement. With the present exemplary embodiment, the coupling recess 7 is arranged at the rearward end of the handpiece 3, and the substantially cylindrical coupling pin 8 extends from the connection part 2 forwardly. In the coupled condition the coupling recess 7 and the coupling pin 8 are releasably latched to one another by means of a latching device 9. This has a latching element 9 which is mounted radially moveably in the one coupling part and is biassed by means of a spring force into a latching position, crossing the dividing gap, in which the latching element 9a engages into a ring groove in the other coupling part. Such a latching device 9 is self-actingly latched upon coupling and upon uncoupling can be overcome by the manual exercise of an axial pulling force, whereby the latching element 9a is self-actingly forced into its release position.

#The connection part 2 is connected with a flexible supply line 2a, which is connected with a non-illustrated control apparatus. The handpiece 3 is preferably freely rotatably mounted on the coupling pin 8, through which handling is improved. Through the plug-in/turn coupling 4 there extends at least one media line 11 for a treatment or drive medium, e.g. water, compressed air, or a water/air mixture (spray). The media line 11 can extend axially through the radial dividing gap (not illustrated) or Z-shaped through a hollow cylindrical dividing gap between the coupling recess 7 and the coupling pin 8, whereby the media line 11 crosses the dividing gap in the region of a ring groove in the coupling pin 8 or in the coupling recess 7, so that in any rotary position the passage of media is ensured. To both sides of the passage, the dividing gap is sealed by means of a sealing ring 8a which may be arranged in a ring groove in the wall of the coupling recess 7 or in the outer surface of the coupling pin 8. Through this a free rotatability through 360E and more is ensured. The media line 11 extends from the rearward end of the treatment instrument 1 to its forward end region, whereby it may run partially as a channel in the instrument body or as a tube or pipeline. The media line 11 opens out in the forward end region of the treatment instrument 1, out of this, whereby the outlet opening 11a is directed towards the treatment site or to the tip of the tool 6.

#With all exemplary embodiments of the invention, for which the same or similar parts are provided with the same reference signs, the handpiece 3 has a rotary part 12 mounted rotatably therein in a roller bearing. With the exemplary embodiment according to FIG. 1 there is involved a so-called turbine handpiece with an arc-shaped curved or angled shaft 13. This can be formed in one piece or consist of a rearward and a forward shaft section 13a, 13b, which are fixedly connected with one another at the beginning of the arc or at the apex of the angle. At the forward end of the shaft 13 there is located a thickened head 14 in which a turbine T is arranged with a turbine wheel 15 which is rotatably mounted in the head 14 around an axis of rotation 16 extending transversely of the shaft 13 or its longitudinal middle axis 13c and in the angle or base plane of the shaft 13. The turbine wheel 15 is located in a turbine chamber 17 into which a media line 11b for compressed air opens and is directed towards the blades of the turbine wheel 15. The media line 11b passes through the plug-in/turn coupling 4 likewise in a Z-shape. The turbine wheel 15 is connected with the holder device 5, here with a receiving sleeve 18, in which the tool 6 can be inserted with its shaft and can be releasably fixed in a manner known per se by means of a fixing device.