Abstract:
The invention comprises a drum motor comprising a drum tube, a spatially fixed shaft in the interior of the drum tube. To provide a drum motor in particular for use in hygiene areas a drum motor ( 10 ) according to the invention comprises: a drum tube ( 11 ), a spatially fixed shaft ( 13 ) in the interior of the drum tube ( 11 ), an inner cover ( 13 ) for accommodating a bearing ( 14 ) to support the drum tube ( 11 ) rotatably about the shaft ( 13 ) and for internally sealing off the interior ( 12 ), and an outer cover ( 30 ) for covering a drum tube end and for externally sealing off the interior ( 12 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a drum motor comprising a drum tube and a spatially fixed shaft in the interior of the drum tube, an outer cover for closing off a drum tube end and a method of assembling a drum motor. 
     A drum motor has a drum tube and a spatially fixed shaft in the interior of the drum tube. Usually arranged in the interior of the drum tube is a drive for driving the drum tube in relation to the spatially fixed shaft so that the drum tube rotates about the axis. Drum motors are also known which have an external gear motor for driving the drum tube with respect to the shaft. 
     Drum motors are preferably used to cause movement of a belt laid around the drum tube. An arrangement of at least one drum motor and a belt guided therearound serves for example as a running belt or conveyor belt. 
     The drum tube is mounted rotatably with respect to the spatially fixed shaft. Oil is usually disposed in the interior of the drum tube, serving to lubricate the bearing and also the drive motor arranged for example in the interior of the drum tube. The ends of the tube are correspondingly closed with a respective cover to keep the oil in the interior of the drum tube. 
     DE 195 27 082 C2 discloses a design configuration of such a cover. In accordance with DE 195 27 082 C2 a cylindrical sleeve is fitted to the inside surface of the drum tube by a connection involving intimate joining of the materials involved, and the cover is introduced into the sleeve in positively locking relationship. Arranging the cover in the drum tube or in the sleeve can thus be implemented as the last assembly step. 
     Drum motors are used for example in industrial sectors in which particular hygiene demands are made on the drum motor. Suitable design configurations for the cover are required, which can be for example a galvanised steel cover, an anodised aluminum cover or a cover of stainless steel. [0007] DE 296 23 889 U1 discloses a cover suitable for use in the foodstuff industry or the pharmaceutical industry. The cover of DE 296 23 889 U1 is provided with a cap of stainless high-quality steel to comply with the hygiene requirements, but to save on that material which would be required for a solid cover of for example stainless high-quality steel. 
     Drum motors are also known in the hygiene field, which have plate covering members of high-quality steel at the ends of the drum tube. 
     The object of the invention is to provide a drum motor which is better adapted to the hygiene demands. 
     BRIEF SUMMARY OF THE INVENTION 
     According to the invention the object is attained by a drum motor comprising a drum tube, a spatially fixed shaft in the interior of the drum tube, an inner cover for accommodating a bearing to support the drum tube rotatably about the shaft and for internally sealing off the interior, and an outer cover for covering a drum tube end and for externally sealing off the interior. 
     The drum motor according to the invention is based on the idea that the drum motor cover is of a two-part structure. In that case the inner cover disposed in the interior of the drum tube performs the function of providing support and preventing oil from escaping from the interior of the drum tube. The outer cover serves for covering over the end of the drum tube and prevents dust, contamination etc. from the space outside the drum motor from being able to pass into the interior. The outer cover preferably serves as a modular outer cover which, depending on the respective hygiene requirement or area of use of the drum motor, is interchangeable without modifications being required in the interior of the drum tube such as for example draining off the oil. 
     An advantage of the drum motor according to the invention is that it is only after the assembly of drum tube, shaft and inner cover, that it can then be decided which outer cover is particularly suitable for the area of use of the drum motor. To replace the outer cover it is only necessary to release the outer cover from the drum motor without for example oil being able to escape from the interior of the drum tube. Therefore the outer cover can be replaced at any time and without major assembly complication and expenditure, for example for cleaning purposes. That is particularly advantageous in regard to hygiene demands on a drum motor. [0013] Advantageously, it is possible to decide after assembly of the motor, which configuration the drum motor is to involve in regard to hygiene, corrosion resistance and material choice for the cover or covers. That provides a particularly maintenance-friendly and/or hygienic drum motor. 
     Preferably the drum motor and/or the inner cover has a fixing means, in particular a thread, for in particular releasable arrangement of the outer cover on the inner cover. Preferably the outer cover is fixed or arranged releasably on the drum motor. Preferably the outer cover is arranged on the inner cover. The arrangement or fixing of the outer cover on the drum motor according to the invention is preferably implemented by a fixing means. Such a fixing means is preferably a thread or screw mechanism, a clamping mechanism, a snap-action or clipping mechanism or the like. The fixing means is preferably adapted to arrange the outer cover releasably on the drum motor according to the invention and/or the inner cover. Particularly preferably the outer cover is screwed on to the inner cover. Preferably the thread for that purpose is arranged at an inwardly disposed location, that is to say between the inner and outer covers, and does not cause any interruptions or unevenness at the outside (for example due to screws) in the smooth external contour, which is particularly advantageous in the hygiene area (for example no contamination or impurities clinging thereto, and simple and reliable cleaning). The cleanability of the motors and thus the aspect of bacterial contamination is considerably improved according to the invention. One or more of those preferred configurations advantageously provides that the outer cover can be particularly easily and/or releasably arranged on the drum motor according to the invention. 
     Preferably the inner cover has at least one oil hole. In particular it is preferable for the inner cover to have at least two oil holes. The oil hole is adapted to introduce oil into the interior of the drum tube and/or to remove oil from the interior of the drum tube. Refilling with oil, an oil change, an oil check, an oil level check and the like can be particularly easily effected by means of the oil hole. 
     Preferably the oil hole has a thread for receiving a sealing screw, it is further preferred if the drum motor according to the invention has a sealing screw which in particular is screwed in sealing relationship in the oil hole. 
     Advantageously the configuration of the oil hole with a thread or fitting the sealing screw in the thread of the oil hole provides that the oil hole can be opened and closed in a particularly simple fashion and reliably prevents oil from flowing out of the interior of the drum tube. If required the sealing screw can advantageously be removed at any time in order for example to remove oil from the interior of the drum tube or to introduce oil thereinto. 
     Preferably the drum motor has a sealing element arranged sealingly in the oil hole. A sealing element can be for example a sealing screw or also a plug, a sealing wedge or another element which prevents the oil from escaping from the interior of the drum tube through the oil hole. 
     Preferably the outer cover has a radial periphery substantially corresponding to the radial periphery of the drum tube. Preferably the radial periphery of the outer cover, in conjunction with the surface of the drum tube, forms a cylindrical surface of the drum motor. The cylindrical surface of the drum motor is in particular smooth so that it is possible substantially to prevent contamination from passing into the interior of the drum motor between the drum tube and the outer cover. The fact that the outer cover, in conjunction with the drum tube, is in the form of a cylindrical surface of the drum motor affords the advantage that the surface of the drum motor can be particularly easily and reliably cleaned. 
     Preferably the outer cover has a smooth surface. Preferably the outer surface of the outer cover, that is to say the surface which is in opposite relationship to the interior of the drum tube, and which closes the interior of the drum tube, is smooth. The smooth configuration of the outer cover permits particularly easy cleaning. In that way, the drum motor is designed in such a fashion that there are no recesses or dirt pockets in the cover region of the drum motor according to the invention, such as for example screw heads on the screws which serve for conventionally fixing the cover, without having to forego the possibility of the oil change and/or a change in the seal. 
     Preferably the drum motor has an outer sealing ring between the outer cover and the drum tube. The outer sealing ring has the advantage that it is possible to prevent contamination from passing from the space outside the motor into the interior of the drum motor according to the invention. The sealing ring also improves the possibility of cleaning the surface of the drum motor as the sealing ring prevents a cleaning agent or a cleaning fluid from being able to penetrate into the interior of the drum motor. Preferably the sealing ring is activated, that is to say pressed, by activation of the fixing means. Preferably the sealing ring is activated by arranging the outer cover on the drum motor according to the invention. Particularly preferably activation of the sealing ring is effected by screwing the outer cover on to the drum motor and/or on to the inner cover. Advantageously that provides that fixing of the outer cover to the drum motor and externally sealing off the interior of the motor are effected at the same time. 
     Preferably the drum motor has a sealing ring between the inner cover and the shaft. Preferably the sealing ring is a Simmerring oil seal. The sealing ring serves for sealing off the drum motor housing on the shaft. The sealing ring in particular prevents the fluid or oil from issuing from the interior of the drum tube, that is to say the sealing ring serves for internal sealing integrity. Preferably the inner cover has an opening in which the sealing ring is arranged. The sealing ring achieves the advantage of particularly good sealing integrity in respect of the interior so that a discharge of oil at the shaft can be substantially prevented. 
     Preferably the drum tube, on its surface in opposite relationship to the interior, has a coating, in particular a rubber coating. The surface of the drum tube, that is in opposite relationship to the interior, is the outer surface of the drum tube or the drum motor. Depending on the respective area of use of the drum motor according to the invention the outer, in particular cylindrical surface of the drum motor is adapted for example to drive a belt. The friction can be set by a suitable choice for the coating. There are for example rubber coatings which are suitable for use with foodstuffs and which are oil- and grease-resistant, and rubber coatings with smooth or structured surfaces or guide grooves. Preferably the radial periphery of the outer cover substantially corresponds to the radial outer periphery of the coating, that is to say the radial periphery of the drum motor according to the invention. Advantageously applying a coating to the surface of the drum motor provides that the drum motor can be adapted for special areas of use. 
     Preferably the outer cover has a projection for engagement into the coating. Preferably the coating has an opening adapted to receive the projection of the outer cover. Preferably the outer cover has an annular projection suitable for engaging into an annular groove in the coating. A particularly advantageous external sealing effect is achieved by the at least partial interengagement of a radial peripheral region of the outer cover into the coating. 
     Preferably the drum motor has a ball bearing between the shaft and the inner cover. Particularly preferably the inner cover has an opening for accommodating the bearing, in particular the ball bearing. Particularly preferably the inner cover has an opening for accommodating the sealing ring and an opening for accommodating the bearing so that the inner cover together with the sealing ring and the bearing can be arranged in the interior of the drum tube in one assembly step. Preferably the inner cover is in the form of a drive output cover which serves for supporting the drum tube with respect to the spatially fixed shaft. Preferably the inner cover is connected to the inner surface of the drum tube by a connection involving intimate joining of the materials concerned. Particularly preferably the inner cover is glued and/or welded to the inside surface of the drum tube. Arranging a ball bearing between the shaft and the inner cover advantageously provides that the inner cover performs the function of supporting the drum tube relative to the spatially fixed shaft. [0026] Preferably the drum motor has a sealing lip between the outer cover and the shaft. Preferably the sealing lip has at least one inner radial region which is rotatable about the outer radial periphery of the shaft. Preferably the sealing lip is adapted to seal off the sealing ring outwardly. Preferably the sealing lip is adapted for sliding around the shaft during rotation of the drum tube about the shaft. The sealing lip has the advantage that external sealing integrity can be further improved to prevent contamination from passing from the space outside the motor into the interior thereof. 
     Preferably the outer cover is sealed off in gap-free relationship both with respect to the inner cover and also with respect to the shaft or axle and also with respect to the drum tube. Sealing integrity as between the outer cover and the inner cover is preferably implemented by the fixing means, in particular the thread, or by screwing the outer cover on to the inner cover. Sealing integrity between the outer cover and the shaft or axle is preferably implemented by the sealing lip. Sealing integrity between the outer cover and the drum tube preferably involves the outer sealing ring and/or the projection of the outer cover into the optional coating. The advantageous gap-free sealing effect is ensured by the defined position of the outer cover by virtue of the screwed construction and thus by a defined pressure on the seals, in particular the sealing lip and the outer seal. According to the invention cleanability of the motors and thus the aspect of bacterial contamination is considerably improved. 
     Preferably the shaft is a hollow shaft. Such a con-figuration is particularly advantageous to pass supply units such as for example cables from outside the drum motor to the motor in the interior of the drum motor. 
     In a further aspect the invention relates to a drum motor comprising a drum tube, a spatially fixed shaft in the interior of the drum tube, an inner cover for accommodating a bearing for supporting the drum tube rotatably about the shaft and for internally sealing off the interior, and means for accommodating an outer cover according to the invention. [0030] In a further aspect the invention relates to an outer cover according to the invention for use in a drum motor according to the invention. 
     In a further aspect the invention concerns a method of assembling a drum motor which has a drum tube and a spatially fixed shaft in the interior of the drum tube, wherein the method comprises the steps: fixing an inner cover between the drum tube and the shaft, wherein the inner cover is adapted to accommodate a bearing to support the drum tube rotatably about the shaft and to internally seal off the interior, wherein the inner cover has an oil hole, filling oil into the interior of the drum tube through the oil hole, sealing off the oil hole, and fixing an outer cover to the drum motor, wherein the outer cover is adapted to cover a drum tube end and to externally seal off the interior of the drum tube. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Embodiments of the invention are described hereinafter with reference to the Figures in which: 
         FIG. 1  shows an external overall view of a drum motor, 
         FIG. 2  shows a cross-section through an end region of a drum motor according to the invention, 
         FIG. 3  shows a cross-section through an end region of a drum motor according to the invention, 
         FIG. 4  shows a cross-section through an end region of a drum motor according to the invention, 
         FIG. 5  shows a cross-section through an end region of a drum motor according to the invention, 
         FIG. 6  shows a detail view of the drum motor of  FIG. 4 , 
         FIG. 7  shows a cross-section through an end region of a drum motor according to the invention, 
         FIG. 8  shows a cross-section through an end region of a drum motor according to the invention, 
         FIG. 9  shows a detail view of the drum motor of  FIG. 7 , and 
         FIG. 10  shows an inside view of the drum motor of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an external view of a drum motor  10 , in the interior of which is arranged a spatially fixed shaft  13 . Outer covers  30  are arranged at the two ends of the drum motor  10 . It is however also possible for the outer cover  30  according to the invention to be arranged only at one end of a drum motor  10 . Arranged in the interior of the drum motor  10  for example is a transmission, the movement of which is converted into a movement of the drum tube  11  with respect to the stationary shaft. 
       FIGS. 2 through 6  show embodiments of non-rubber-coated tubes  11  with a seal. 
       FIGS. 2 and 3  show a first embodiment of a drum motor according to the invention. The drum motor according to the invention has a drum tube  11  which encloses an interior  12  of the drum tube  11  or the drum motor  10 . Arranged in the interior of the drum tube  11  is a spatially fixed shaft  13  which is preferably in the form of a hollow shaft, as shown in  FIGS. 2 and 3 . Arranged between the drum tube  11  and the hollow shaft  13  is the two-part cover according to the invention, comprising an inner cover  20  and an outer cover  30 . The inner cover  20  and the outer cover  30  are arranged against each other. The outer cover  30  in the embodiment of  FIGS. 2 and 3  is screwed on to the inner cover  20  by means of the thread  21 . Alternatively or additionally the outer cover  30  can be screwed on to the drum tube  11 . Instead of screwing the outer cover  30  to the inner cover  20  and/or the drum tube  11  clamping, snap-action mounting, clipping mounting or another fixing mechanism is possible. 
     The inner cover  20  supports the drum tube  11  with respect to the hollow shaft  13  by means of a ball bearing  14 . The drum tube  11  is arranged rotatably about the spatially fixed hollow shaft  13  by means of the ball bearing  14 . In that case the inner cover  20  serves as a drive output cover for transmitting the output of the drive (not shown) to the drum tube  11 . The inner cover  20  is fixedly connected to the drum tube  11  to translate the rotary movement of the inner cover  20  into a rotation of the drum tube  11 . The inner cover  20  is for example glued or welded to the inside surface of the drum tube  11 . 
     The inner cover  20  further has an opening for accommodating a sealing ring  17  in the form of a soft seal. In the embodiment of  FIGS. 2 and 3  the sealing ring is in the form of a Simmerring or oil ring seal  17 . The Simmerring  17  serves for internal sealing integrity, that is to say it prevents a fluid in the interior of the drum tube  11  from issuing. 
     The inner cover  20  of the embodiment of  FIGS. 2 and 3  has two oil holes  15 . The oil holes  15  are provided with a female thread into which sealing screws  16  are sealingly screwed. Upon assembly of the drum motor  10  according to the invention the inner cover  20  is fixed between the drum tube  11  and the hollow shaft  13 , thereafter the fluid, in particular oil, is introduced into the interior  12  through the oil holes  15 , thereafter the oil holes  15  are closed by fixing the sealing screws  16  in place and finally the outer cover  30  is arranged at the drum tube end. 
     Arranged between the outer cover  30  and the hollow shaft  13  in the embodiment of  FIGS. 2 and 3  is a sealing lip  18  which serves for external sealing and prevents contamination and fouling from passing into the interior  12  from the outside. Sealing integrity between the outer cover  30  and the drum tube  11  is achieved by means of a sealing ring  31 , as is further described hereinafter. 
       FIGS. 4 through 6  show a further embodiment of a drum motor  10  according to the invention. In the embodiment of  FIGS. 4 through 6  the shaft is solid and is not in the form of a hollow shaft as in  FIGS. 2 and 3 . Such a design configuration can be advantageous if the drive is arranged for example in the space outside the drum motor  10  and therefore there is no need for supply lines to be passed through the hollow shaft. The cylindrical surface of the shaft  13  also has ring-shaped steps which prevent displacement of the drum tube and components arranged in the interior thereof with respect to the shaft  13 . The embodiment in  FIGS. 4 through 6  has a fixing element  16  which for example is in the form of a plug to close the oil holes  15 . The inner cover  20  and the outer cover  30  can be connected together by means of a thread  21 . The Simmering  17  prevents oil issuing from the interior  12 . The sealing lip  18  prevents contamination from passing into the interior  12 . 
       FIG. 6  shows a detail view of the region Din  FIG. 4 . The embodiment of  FIGS. 2 and 3  is of a similar configuration in the transitional region between the drum tube  11  and the outer cover  30 , as shown in  FIG. 6 .  FIG. 6  shows the inner cover  20  which is fixed to the inside surface of the drum tube  111 , in particular by a connection involving intimate joining of the materials concerned. The outer cover  30  is arranged at the drum tube  11  and the inner cover  20 . An external seal between the outer cover  30  and the drum tube  11  and/or the inner cover  20  is afforded by means of an external sealing ring  31 . The sealing effect of the external sealing ring  31  is activated by the outer cover  30  being arranged on the drum tube  11 , in which case the sealing action of the external sealing ring  31  becomes progressively greater, the correspondingly smaller the spacing between the outer cover  30  and the drum tube  11 . The spacing between the outer cover  30  and the drum tube  11  is preferably adjusted by means of the fixing means  21 ; the tighter the outer cover  30  is screwed for example with the drum tube  11  and the inner cover  20  respectively, the correspondingly greater is the sealing action of the external sealing ring  31 . 
       FIGS. 7 through 10  show a further embodiment of a drum motor  10  according to the invention for a rubber-coated tube  11  with a cut edge. The outer cover  30  for rubber-coated drum tubes  11  provides the sealing integrity in relation to the drum tube  11  by a definedly placed sealing edge as described hereinafter with reference to  FIGS. 7 through 9 . In other respects the features of the embodiment of  FIGS. 7 through 10  are or can be identical to those of the non-rubber-coated drum tube of  FIGS. 1 through 6 . 
     The drum motor  10  in  FIGS. 7 through 10  has a drum tube  11  and a hollow shaft  13  arranged stationarily in space in the interior of the drum tube  11 . A bearing and a sealing ring are arranged around the hollow shaft  13 . The inner cover  20  is arranged between the bearing, the sealing ring and the inside surface of the drum tube  11 . The outer cover  30  is screwed on the surface of the inner cover  20 . The design configuration of oil holes  15  and the sealing element  16  can be in accordance with the above-described embodiments or other design configurations. 
     A coating  19  is arranged on the outside surface of the drum tube  11 . The coating  19  is in particular a rubber coating and serves for adjusting the friction depending on the respective area of use of the drum motor  10 . The external sealing integrity between the outer cover  30  and the drum tube  11  or the rubber coating  19  is afforded in the  FIGS. 7 through 10  embodiment not or not solely by a sealing ring, but by a projection  32  as is illustrated in  FIG. 9  showing a detail view of the region B in  FIG. 7 . 
       FIG. 9  shows a drum tube  11 , to the inside surface of which the inner cover  20  is fixed by a connection involving intimate joining of the materials concerned. A rubber coating  19  is arranged on the outer surface of the drum tube  11 . The outer cover  30  is arranged on the inner cover  20  and the drum tube  11  to cover over the drum tube end and to seal off the interior  12  relative to the exterior. The external sealing integrity is afforded by a projection  32  which engages into the rubber coating  19  or which is received in a recess in the rubber coating  19 . It is possible to dispense with the use of a sealing ring  21  in the embodiment of  FIGS. 7 through 10 . 
       FIG. 10  shows an inside view of the drum motor of  FIGS. 7 through 9 , illustrating the section along A-A in relation to  FIG. 7 .  FIG. 10  illustrates the radial arrangement of shaft  13 , ball bearing  14 , inner cover  20  and drum tube  11 . The coating  19  is arranged outside the drum tube  11 . In the view shown in  FIG. 10  it is possible to see the sealing elements  16  which seal off the oil inlet or passage to the interior  12  of the drum motor. 
     The invention makes it possible to design the drum motor  10  in such a way that the outer cover  30  can be designed in customer-specific and demand-specific fashion in relation to shape and material, and can be subsequently fitted in place. In particular the drum motor  10  according to the invention makes it possible to use the surface of the outer cover  30 , prior to assembly of the drum motor  10  or after assembly of the drum motor  10 , for manufacturer-specific or customer branding. Particular requirements, including on the esthetic aspect, can thus be particularly easily met. As the outer cover  30  serves for covering over the drum tube end and for external sealing thereof it can be made virtually from any material, such as for example high-quality steel, plastic, rubber and so forth. According to the invention therefore there is thus provided a hygienic drum motor cover with central closure and choice of external material after assembly.