fig1 shows an electric motor 1 according to the invention . this is accommodated in a housing , to which a coupling 12 according to din iso 3964 , for the connection of dental instruments , is attached . the electric motor 1 itself comprises a shaft 3 which is connected to a rotor magnet 4 . a stator 5 is concentrically arranged around this , and media conduits 6 and 7 ( for water and air ) and light ( media conduit 8 ) run through the stator , i . e . they no longer need to be led outside the stator . the “ media conduit for light ” may either be a fiber optic ( e . g . glass fiber ), alternatively also an electricity supply , to a light or light diode which is introduced in the region of the coupling to the dental instrument . “ through the stator ” or “ within the stator ” hereby it to be understood in that the media conduits run radially within electrically effective regions of the stator , here radially within the largest dimensions of the stator windings . the media conduits or electrical supply leads for the motor according to the invention run through a flexible tubing which is no longer shown on the right in fig1 , which may either be firmly connected to the electric motor or may be coupled to this via the coupling . the media conduits hereby project preferably radially inwards ( see fig3 ) on the side which is distant to the coupling 12 , in order in this region to provide a flexible tubing with a small diameter as soon as possible after the end of the electric motor . the electric motor 1 is a permanent magnet synchronous motor , here a d . c . motor without collector ( bldc motor ). fig2 shows a detailed , partly freely sectioned construction of the stator 5 . this stator comprises a stator winding 9 which is wound according to gramme , i . e . around the coil body 11 which radially encloses a yoke ring 10 belonging to the coil body . the winding wires hereby run around the outer ring formed by the coil body or around the annular stator core . in the representation shown in fig2 , the winding 9 hereby is subdivided into several sections , which in each case represent annulus segments . these annulus - segment - shaped sections ( for example a first section 9 a or a second section 9 b ) are preferably represented as individual coils . the winding wires of these individual coils are arranged essentially in the running direction of the shaft 3 , ( this runs essentially aligned to the coupling 12 , see fig1 ). the course of the winding wires along the shaft 3 hereby only applies to the radial inner side or radial outer side , and at the end - side the winding wire runs essential radially inwards or radially outwards . in total , six individual coils 9 a , 9 b , etc . are provided , wherein the respective diametrically oppositely lying individual coils are connected to one another in each case into a coil pair and are switched to a phase . the sections 9 a , 9 b , etc . or individual coils are wound in a multi - layered manner and do not overlap , even in their end regions . the corresponding stator winding is cast with an artificial resin or plastic . the stator 5 shows the yoke ring 10 which is surrounded radially inwards and radially outwards by the coil body , and the coil body in turn is surrounded by the corresponding winding . the yoke ring 10 is constructed of several layers of a sheet - metal . the coil body between the individual sections 9 a , 9 b , etc . comprises radial protuberances , which run radially outwards or radially inwards ( thus to the rotor magnet ). in these regions , the passage of the media conduit 8 by light or the media conduit 7 by air or the media conduit 6 by water , is possible without an unnecessary field influence or thermal influence by the electric motor . basically , one may lead through an infinite number of media conduits , possible are also electricity supply leads , in the case that the dental instrument should require additional connections here . the media conduits may thus run within or outside a yoke ring . they do not necessarily need to run between individual sections or the stator windings , but may also run through the stator winding . the ratio of the size extent of the stator radially to the shaft ( largest diameter region of the stator in fig2 , measured as a diagonal of the two points which are radially distanced the most , in a plane of the stator winding which is perpendicular to the shaft ), to the greatest extent of the stator in the direction of the shaft ( thus in the longitudinal direction of the shaft , here therefore aligned to the coupling , again here between the regions of the stator winding which are axially distanced the most from one another ), is 1 . 4 . the ratio of the greatest extent of the stator radially to the shaft ( here again the largest diameter dimension in the region of the stator winding ), to the greatest length of the rotor magnet ( only the length of the actual rotor magnet is considered ), is 1 . 5 . fig3 a to 3 c show different views of a flexible - tubing motor according to the invention . hereby , the electric motor 1 according to the invention , which is arranged in the housing , with which the housing on the left side comprises the coupling 12 according to din iso 3964 , is connected directly to a flexible tubing 13 on the right side , without yet an additional coupling being provided here . such a coupling would entail large construction costs , further sources of errors , as well as a greater weight . the media conduits for air , water or light 6 , 7 , 8 hereby run through the flexible tubing 13 up to a drive and control unit 14 . here , the greatest distance measured from the tip of the coupling 12 , up to the run - out of the flexible tubing 13 into the drive and control unit 14 , is 2 . 5 m it is to be noted that the media conduit 8 for leading through light , which is preferably designed as a glass fiber conduit ( alternatively as an electricity supply lead ), runs directly from the drive and control unit to the coupling 12 without interruption . a light source which feeds the light into this fiber - optic , is provided in the drive and control unit . by way of this , there is no necessity of an additional light source in the region of the electric motor 1 , which would require additional construction space or would entail an increased heat dissipation in the region of the hand of the operator . in particular , by way of making do without a coupling between the electric motor and the flexible tubing , one also ensures that this coupling produces no scatter light loss . fig4 shows an example of a dental instrument 2 with an integrated electric motor according to the invention . “ dental instrument ” in the content of this application is to be understood to include an apparatus , which in a manner driven by motor , permits the machining of objects or teeth , preferably by a dentist , dental technician or corresponding personnel . fig5 shows the construction of a dental system according to the state of the art , with which a dental instrument 2 is coupled via a coupling according to din iso 3964 to a motor 1 ′, which then in turn may be connected to a flexible tubing piece 13 ′ via a further coupling .
the present invention relates to an electric motor for the drive of a dental or medical instrument , with a rotor magnet mounted on a shaft , as well as with a stator and media conduits for leading through media to the dental instrument . a gramme stator winding is provided in the electric motor , wherein at least regionally , media conduits run within the stator winding or between individual sections of the stator winding . the electric motor according to the invention is distinguished by a very compact constructional manner , by which the operator may work without getting tired , even over a long period of time .