Drive for rotating object such as a roller, shaft, plate or the like

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.

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.

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. 2a-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. 3a 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.degree. 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. 2a, 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. 2a to e. Here, each figure corresponds to a state of the lever
 position for a rotation of the worm wheel 17 through 45.degree.. That is
 to say, FIG. 2e represents a rotation through 180.degree., provided FIG.
 2a is established at 0.degree..
 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. 3a
 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. 3a). 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.degree. 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. 5a 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.degree. but by 120.degree.. Further improved
 synchronism can be achieved by this embodiment, which is shown in
 longitudinal section in FIG. 5b to illustrate the position of the drive
 levers 26, 27, 28.