Abstract:
A drive for rotating an article such as a roller shaft or plate has a gear which is connected to the rotating article in a rotationally fixed manner. The gear has a number of teeth. A means for driving the gear has a movably mounted lever with a tip that meshes with the gear to have driving contact with the gear and impart driving motion to the gear. The tip forms a tooth and the gear teeth and the tooth of the lever tip are shaped to mesh with a rolling contact between them during the driving motion.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a drive for a rotating article 
     Such a drive has already been disclosed by European Laid-open Specification EP 083 8610 A2. The main item of this drive is at least one pivotably mounted lever, which interacts with a gear, which is connected to the rotating article in a rotationally fixed manner. To this end, there is a device for mounting and guiding the lever for a driving forward motion, meshing with the gear, of the lever. 
     This drive has the advantage that it is essentially insensitive to contaminants which occur due to a liquid in which rollers, shafts or the like rotate in an air-humidifying and cleaning unit, a deodorizer or the like. For even if the gear is wetted in the process by the liquid due to the rotational motion in the liquid, the only point of contact with the further components of the mechanism is in that part of the lever which meshes with the gear. However, this part of the lever is simple to clean as a rule. 
     However, a disadvantage of this mechanism consists in the fact that, in particular due to the occurrence of production tolerances of the drive parts, smooth, quiet running of the rotating article is impaired from time to time, since, in particular, the meshing lever may become stuck with the gear. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a drive which has improved synchronism and is in particular less sensitive to production tolerances. 
     The invention is based on a drive for a rotating article for a roller, shaft, plate or the like, in particular for a deodorizer, an air humidifier or an air-cleaning unit or the like, which has the following features. 
     A movably mounted lever, a gear which is connected to the rotating article in a rotationally fixed manner, and a lever mechanism means for a driving motion, meshing with the gear, of the lever in order to rotate the gear, are provided with the lever having a tip for meshing with the teeth of the gear. The central idea of the invention, then, is to design the tip in the form of a tooth, the shape of this tooth and that of the teeth of the gear as well as the lever mechanism being matched to one another in such a way that the tooth flanks of the tooth on the at least one lever and the respectively meshing tooth on the gear roll on one another during the driving motion. This measure achieves a situation in which the drive, even when production tolerances occur, sets the gear and the rotating article in a smooth motion, in the course of which sticking of lever tip and gear can be avoided. This is because the configuration according to the invention essentially fulfills the mathematical interrelationships of a conventional tooth system between two gears. In addition, the wear of the tooth flanks in contact is thereby markedly improved compared with the solution from the prior art, since the sliding motion, which is otherwise present, between the flanks is greatly reduced and is essentially replaced by a rolling motion. This has a positive effect, in particular, on the service life of the drive and on the operating noise. 
     In order to improve the synchronism of the drive still further, it is also proposed that the shape of the tooth on the lever and that of the teeth of the gear as well as the lever mechanism be matched to one another in such a way that the tooth flanks of the tooth on the at least one lever and the respectively meshing tooth on the gear, during the driving motion, have a point of contact at which the flanks roll on one another without radial sliding (rolling point). 
     The shape of the tooth on the lever and that of the teeth on the gear are preferably designed according to the rules of tooth engagement as an involute, cycloidal or circular arc tooth system or as a lantern tooth system, in which the tooth on the lever has, for example, the shape of a pin. In this way, an essentially constant transmission ratio between lever mechanism and gear can be realized. 
     In an especially advantageous refinement of the invention, the lever mechanism contains guide surfaces for the lever for the sliding guidance of the lever. As a result, the lever, in a guided manner, can perform, for example, a forward motion, a reverse motion and a pivoting motion. In this connection, it is advantageous if the lever mechanism comprises an eccentric drive for the lever. By the articulation points of the lever and the guide surfaces on the housing of the lever mechanism being geometrically arranged in such a way as to be appropriately matched to one another, a desired coupler curve can be realized for the cyclic meshing of the tooth-shaped tip of the at least one lever. Instead of the operating principle, thereby realized, of the slider-crank mechanism, the operating principle of the inverted slider crank, in which the longitudinal guide is located in the lever, and, for example, a pin secured in the housing of the lever mechanism engages in this longitudinal guide, may also be applied in another embodiment. 
     Furthermore, to realize a simple eccentric drive, it is proposed that this eccentric drive have a drive shaft for the lever, and this drive shaft is arranged eccentrically on a gear. The gear may be driven continuously, preferably by means of a worm. As a result, extreme transmission ratios are possible on the one hand, which is necessary in particular during use in a deodorizer or air washer according to the invention, where only one motor is used for the direct drive of the fan and the drive of one or two plate stacks. On the other hand, a worm gear unit constitutes a so-called self-locking gear unit, as a result of which the at least one lever is locked against undesirable motion. 
     In a preferred embodiment, the drive shaft is attached directly and eccentrically to a gear which is driven by a worm. 
     The worm is preferably connected to the drive shaft of a motor via an elastic coupling. In this way, the drive shaft need not be absolutely exactly in alignment with the worm shaft. In this case, larger tolerances during the production of a drive according to the invention are possible, which, inter alia, brings about a cost saving. 
     In an especially advantageous refinement of the invention, there are two, three or more levers, which mesh alternately with the gear. As a result, at least one lever is constantly in mesh with the toothed or pin ring of the rotating article, so that the latter is driven smoothly. Furthermore, in the event of the levers being locked by a worm gear unit against an undesirable motion, it is ensured that the rotating article is also secured against any undesirable further motion, for example against turning back, by at least one meshing lever. The rotation of the rotating article is therefore constantly controlled in a mechanically fixed manner by the lever drive. 
     Furthermore, it is especially preferred if the at least one lever is elastically mounted between the guide surfaces of the lever mechanism. As a result, the lever is prestressed in the lever mechanism and exhibits no play even where there are production tolerances. Excessive play could, in the worst case, lead to the tooth of a meshing lever colliding with a tooth of the gear or to the teeth sticking. 
     In this case, it is especially preferred if, to elastically mount the lever between the guide surfaces, at least part of the outer contour of the lever gripped by the guide surfaces is elastically resilient. In this connection, it is advantageous if, to realize an elastically resilient outer contour of the lever, the outer contour is designed as a narrow frame. In particular, if the lever is made of plastic, this contour region consequently has elastic properties. 
     Furthermore, in order to further improve the elastic properties, it is preferred if the frame is interrupted, a spring element being fitted in place at the point of interruption. 
     Finally, in order to ensure effective force transmission of the at least one lever to the gear, it is proposed that that region of the outer edge of the lever which is supported on a guide surface of the lever mechanism in order to absorb the major force for a further motion of the gear not be elastically resilient. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Several exemplary embodiments of the invention are shown in the drawings and explained in more detail below with indication of further advantages and details. In the drawing: 
     FIG. 1 shows a side view of two plate stacks, arranged next to one another, of an air-humidifying unit with drives according to the invention arranged thereon in each case, in schematic side view, 
     FIGS. 2 a-e  show a schematic cross-sectional detail of a drive according to the invention in accordance with FIG. 1 for different lever positions, 
     FIGS. 3 a-c  show a lever according to the invention in two plan views with and without spring element and in a side view, 
     FIG. 4 shows a worm wheel with eccentrically arranged drive shaft for a lever according to FIGS. 3 a  to  c  in a schematic plan view, 
     FIG. 5 a  shows a detail of a drive according to the invention in accordance with FIGS. 2 a  to  e  but with three drive levers for one position, and 
     FIG. 5 b  shows a drive according to the invention in accordance with FIG. 5 a  in longitudinal section. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Two plate stacks  1 ,  2 , mounted in parallel, of an air-humidifying unit with drives  3  according to the invention arranged thereon are shown in FIG. 1 in a schematic side view. The plate stacks  1 ,  2  consist, for example, of circular disks arranged one behind the other in a lamellar manner. In the air washer, the plate stacks  1 ,  2  are normally mounted on a trough(not shown), in which water, if need be with an additive, is located as a rule, the plate stacks plunging into the water during a rotation about axes  4 ,  5 . Likewise not shown is a housing cover, on which, for example, a fan with drive motor, which is connected to the two drives  3  according to the invention via an elastic coupling  6 , is arranged. 
     In FIGS. 2 a-e , the drive  3  according to the invention is shown as an enlarged detail in sectional view for different lever positions. These figures show a lever mechanism means  7 , which interacts with a toothed ring  8 , which is arranged on the end face of the plate stack  1 . The lever mechanism  7  is an arrangement having two drive levers  9 ,  10 . The drive levers  9 ,  10  in each case have a tip  11 ,  12  of tooth-shaped design as well as a location opening  13 ,  14  (also see FIGS. 3 a  and  b ) for two drive journals  15 ,  16  in each case. The drive journals  15 ,  16  are attached to the two end faces of a worm wheel  17  in such a way as to be eccentrically offset by 180° and thus form an eccentric bearing seat for the drive levers  9 ,  10  slipped into position thereon via the location openings  13 ,  14 . The worm wheel  17  has a rotary spindle  18 , which is mounted in the housing of the lever mechanism  7  and is in engagement with a worm  19 . The worm  19  is connected to, for example, a drive motor M via the elastic coupling  6 . When the worm  19  rotates and when the worm wheel  17  rotates as a result, for example in the direction of the arrow, the drive levers  9 ,  10  are moved or pivoted back and forth in the housing of the lever mechanism  7  via the location openings  13 ,  14 , of the drive levers  9 ,  10  mounted on the drive. In the process, the outer contour of the drive levers  9 ,  10  bears against guide surfaces  20 ,  21  of the housing of the lever mechanism  7 . 
     In FIG. 2 a , the front drive lever  10  (shown in solid lines) is in mesh with the tooth system of the toothed ring  8 , whereas the second drive lever  9  (shown in broken lines) arranged behind it has been completely retracted from the tooth system of the toothed ring  8 . The desired motion of the tooth-shaped tips  11 ,  12  of the drive levers  9 ,  10  results essentially from the geometric distances between the eccentrically arranged drive journals  15 ,  16  as well as from the shape and the distance between the guide surfaces  20 ,  21 . The path curve of the tooth-shaped tips  11 ,  12  appears as a coupler curve of the slider-crank mechanism which is thus realized. 
     The motion of the drive levers  9 ,  10  for obtaining a rotary motion of the toothed ring  8 , arranged on the plate stack  1 , in the direction of the arrow is depicted in different angular positions of the worm wheel  17  in FIGS. 2 a  to  e . Here, each figure corresponds to a state of the lever position for a rotation of the worm wheel  17  through 45°. That is to say, FIG. 2 e  represents a rotation through 180°, provided FIG. 2 a  is established at 0°. 
     The shape of the teeth  22  of the toothed ring  8  and of the tooth-shaped tip  11 ,  12  is designed in such a way that the intermeshing teeth realize, by way of example, a cycloidal tooth system. In addition, the motion of the drive levers  9 ,  10  is coordinated by the eccentric mounting and the guide surfaces on the housing of the lever mechanism in such a way that the tooth flanks roll on one another. 
     The drive lever  10  is again shown in detail by way of example in FIGS. 3 a  to  c . The outer contour of the drive lever  10  is designed as a narrow frame  23  over a large region on one side. The frame  23  is interrupted in front of the location opening  13  and has location pins  24  for a compression spring  25  (only shown in FIG. 3 a ). In this way, the front region of the drive lever  10  is elastically resilient on this side. This enables the drive lever  10  or the drive lever  9  of identical design to be inserted with prestress into the housing of the lever mechanism  7 . This prevents the levers  9 ,  10  from exhibiting play where production tolerances occur, this play possibly leading to the tip  11 ,  12  of a drive lever  9 ,  10  colliding with or becoming stuck to a tooth of the toothed ring  8 . The asymmetrical frame formation enables the lever to be supported on a guide surface without yielding. This is preferably the side which absorbs the major forces for the further motion of the gear. 
     The worm wheel  17  with the drive journals  15 ,  16  arranged on both end faces in such a way as to be eccentrically offset by 180° is again shown as a detail in FIG.  4 . As already mentioned above, the mounting of the worm wheel  17  is effected via bearing spindles  18 , which project from the eccentrically arranged drive shafts  15 ,  16 . 
     As can be seen in particular from FIG. 1, the tips  11 ,  12  of the drive levers  9 ,  10  are directed downward, so that liquid, which is delivered to the lever tips  11 ,  12  by the plunging of the toothed ring  8  into a liquid bath, runs off again down to the toothed ring  8 . The only locations which can therefore connect with the liquid of the bath are merely the tooth-shaped tips  11 ,  12  of the drive levers  9 ,  10 . There is therefore no risk of the remaining components of the drive coming into contact with the bath liquid during any operational phase of the unit. For the layman, dismantling the unit for cleaning work is possible in a simple manner, since, with removal of the cover (not shown), only the plate stacks  1 ,  2  are still located in the trough (not shown). 
     The drive shown for a plate stack  1 ,  2  can be used outside an air-humidifying unit according to the invention. The system shown can be readily used on any rotating article with which a drive system according to the invention offers advantages. This may be the case, in particular, in chemical production plants, where rollers, drums, heat exchangers or the like must likewise frequently rotate inside a liquid bath, and therefore the problem likewise arises that the drive must not come into contact with the, possibly aggressive, liquid or may only come into contact with said liquid at certain points. The drive principle according to the invention may also be advantageously applied if a very high transmission ratio is to be realized between the drive shaft and the rotating article. 
     A variant of a drive according to the invention is shown in FIGS. 5 a  and  b , three drive levers  26 ,  27 ,  28  being used in this drive instead of two. In a corresponding manner, drive journals are eccentrically offset on a worm wheel  29  not by 180° but by 120°. Further improved synchronism can be achieved by this embodiment, which is shown in longitudinal section in FIG. 5 b  to illustrate the position of the drive levers  26 ,  27 ,  28 .