Abstract:
A transport system for transport of containers has a switch with an entry zone, an exit zone with at least two different transport paths for conveying a container, and a switch mechanism for selectively controlling the transport of the container to the transport paths. During their travel, the containers are supported by a support assembly, and aligned and advanced in a controlled manner in the entry zone by an alignment and propulsion mechanism. A propulsion and guide assembly in the exit zone is rendered operative in response to a transport of the container along the transport paths and includes at least two modules which respectively cooperate with the transport paths and are disposed in the exit zone below the plane of the support assembly. The modules are hereby so controlled that only the one of the modules is raised into a plane above the plane of the support assembly, when the container is transported along the associated transport path.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application claims the priorities of German Patent Applications, Serial Nos. 103 08 657.9, filed Feb. 27, 2003, and 103 15 475.2, filed Apr. 4, 2003, pursuant to 35 U.S.C. 119(a)–(d), the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to a transport system for transport of containers, in particular to an airport baggage handling system. 
   German Patent publication DE 199 21 131 A1 describes a switch for a transport system having in transport direction of the containers an entry zone which leads to a switch zone for directing the containers into a desired direction. Following the switch zone is an exit zone from which the containers move in the selected direction. The transport of the containers takes place in a horizontal support plane which is formed by cylindrical rollers. A change in direction of the containers in the switch zone is realized by a group of cooperating modules. Each of the modules includes a rolling body for support of the containers during their advance. The rolling bodies of the modules are hereby swingably supported about a vertical axis via a control mechanism. 
   It is also known to urge containers to move in a desired direction by means of central guide rails on which guide rollers run that are mounted to the container. As the transport direction of the container does not entirely coincide with the driving direction of the driving rollers, increased wear is encountered. The constraint guidance of the containers takes place spotwise and requires metal insets in the container so that a full screening of the containers in an X-ray machine becomes impossible. 
   It would be desirable and advantageous to provide an improved transport system with at least one switch to obviate prior art shortcomings and to ensure a substantially frictionless horizontal guidance of the containers in nay intended direction while still being simple in structure. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the present invention, a transport system for transport of containers, in particular a baggage handling system, includes at least one switch having an entry zone, an exit zone with at least two different transport paths for conveying a container to conveyors immediately disposed downstream of the exit zone, and a switch mechanism for selectively controlling the transport of the container to the transport paths, a support assembly defining a plane for support of the container between the entry zone and the exit zone, an alignment and propulsion mechanism disposed in the entry zone for aligning and advancing the container in a controlled manner, a propulsion and guide assembly rendered operative in response to a transport of the container along the transport paths, with the propulsion and guide assembly including at least two modules constructed for cooperation with the transport paths in one-to-one correspondence and disposed in the exit zone below the plane of the support assembly, wherein the modules are controlled in such a manner that only the one of the modules is raised into a plane above the plane of the support assembly when the container is transported along the associated transport path. 
   According to another feature of the present invention, the alignment and propulsion mechanism may have a catch member extending transversely to the plane of the support assembly and constructed for engagement against opposite longitudinal sides of a recess formed in an underside of the container and extending in longitudinal direction of the container to thereby apply a contact pressure upon the container and advance the container. 
   According to another feature of the present invention, the catch member may include two driving belts which are routed about rollers and have outer belt sides for abutment against the longitudinal sides of the recess, wherein each of the rollers defines an axis extending transversely to the plane of the support assembly. Thus, slight distances between the propelling driving belts are possible so that differences in speed are minimal. 
   Suitably, the longitudinal sides of the recess extend in parallel relationship. 
   According to another feature of the present invention, the catch members may be configured as rollers, preferably cone-shaped rollers, which roll on the longitudinal sides of the recess. As a result, the containers can travel with little wear and little noise. Advantageously, the longitudinal sides of the recess extend slantingly outwards away from one another. Precision of the guidance may be further enhanced by configuring each of the longitudinal sides of the recess with increasingly outward curvature toward a mid-section thereof. 
   According to another feature of the present invention, the support assembly may have rotatably supported ball rollers or sliding surfaces for support of the container so that the guidance takes place with little transverse forces. 
   According to another feature of the present invention, the switch mechanism may include a passive operating element in the form of a leaf spring, which extends transversely to the plane of the support assembly and has opposite flat sides, and plural guide rollers disposed on the flat sides in parallel relationship, said leaf spring having one end securely fixed in an entry-zone-proximal region and another end outwardly deflectable through bending. The moment transmitted by the leaf spring can be increased when providing a rocker arm for outwardly deflecting the leaf spring, and a four-bar linkage for guiding the leaf spring along a radius of curvature. 
   According to another feature of the present invention, each of the modules of the propulsion and guide assembly may include rollers extending transversely to the plane of the support assembly, and/or at least one driving belt, for engagement against opposite longitudinal sides of a recess of the container to advance the container. 
   According to another feature of the present invention, the propulsion and guide assembly may include a servomotor for operating the modules, with the servomotor having a motor shaft for support of cam plates which actuate lifting elements for selectively lifting and lowering the modules. 
   According to another feature of the present invention, the alignment and propulsion mechanism and/or the propulsion and guide mechanism may be constructed as flat-top chain with prisms or trapezoids disposed transversely to a chain moving direction in parallel relationship, wherein the prisms or trapezoids engage in a longitudinal recess of the container to thereby realize a frictional engagement with slanted longitudinal sides of the recess for guiding and advancing the container, whereby the prisms or trapezoids have outwardly directed sides resting against the longitudinal sides. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which: 
       FIG. 1  is a perspective view of a switch for a transport system in accordance with the present invention; 
       FIG. 2  is a cutaway perspective view, on an enlarged scale, of an entry zone of the switch of  FIG. 1 ; 
       FIG. 3  is a cutaway perspective view, on an enlarged scale, of the switch, showing in detail the area of the switch with the switch mechanism; 
       FIG. 4  is a side view of the switch mechanism; 
       FIG. 5  is a cutaway perspective view of an exit zone of the switch of  FIG. 1 ; 
       FIG. 6  is a front view of the exit zone; 
       FIG. 7  is a schematic perspective view of a modified switch for transport of a container; 
       FIG. 8  is a schematic perspective view of a yet another variation of a switch for transport of a container; 
       FIG. 9  is a perspective illustration of a propulsion and guide assembly in the exit zone of another embodiment of a switch; and 
       FIG. 10  is a perspective illustration of the propulsion and guide assembly of  FIG. 9  with container. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Throughout all the Figures, same or corresponding elements are generally indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. 
   This is one of three applications filed on the same day. These applications deal with related inventions. They are commonly owned and have in part different inventive entities. The applications are unique, but incorporate the other by reference. Accordingly, the following U.S. patent applications are hereby expressly incorporated by reference: “Container Transport System and Container for Transport of an Article” and “Transport System for Advancing Containers, and Curve Section of such a Transport System”. 
   Turning now to the drawing, and in particular to  FIG. 1 , there is shown a perspective view of a switch  1  for a transport system in accordance with the present invention for transport of containers or trays  2  (depicted in  FIGS. 7 ,  8 ,  10 ). This type of transport system is oftentimes installed in a baggage handling system in airports. The containers  2  travel through the switch  1  in direction of the arrow and are first received by an entry zone  3  of the switch  1  and then advanced via a switch zone  4  to an exit zone  5 . Depending on which way the switch  1  is positioned, the containers  2  can travel in a straight transport path without change in direction, or to a left transport path or a right transport path, as shown in  FIG. 1 . The transport system includes a support assembly in the form of plate-shaped support elements  6  with freely rotatable ball rollers  7  for carrying the containers  2 . As an alternative, the support elements  6  may also be configured as sliding surfaces. 
   In the entry zone  3 , the containers  2  are properly lined up and propelled in a controlled manner by an alignment and propulsion mechanism, generally designated by reference numeral  8  and configured as a catch member which includes two driving belts  8   a,    8   b.  For interaction with the containers  2 , the containers  2  have an underside formed with a grooved passageway or recess  8   c  which is bounded by two confronting sidewalls  8   d,  as shown in particular in  FIGS. 7 ,  8  and  10 , and which is engaged by the driving belts  8   a,    8   b  as the containers  2  travel through the entry zone  3 . 
   The containers  2  are then received in the switch zone  4  which includes a switch mechanism in the form of an operating element  9  for regulating the further advance of the containers  2 . The operating element  9  is configured as a leaf spring having one end (the left-hand end in  FIG. 1 ) which is securely fixed in the area adjacent to the entry zone  3  and an opposite end (right-hand end in  FIG. 1 ) which can be bent for deflection to the right or left depending on which of the transport paths is desired. 
   Disposed in the exit zone is a propulsion and guide assembly, generally designated by reference numeral  10  and including modules  10   a,    10   b    10   c  which are respectively associated to the transport paths in the exit zone  5 . In other words, the module  10   a  cooperates with the right transport path, module  10   b  cooperates with the straight transport path, and module  10   c  cooperates with the left transport path. The modules  10   a,    10   b,    10   c  can be moved between an idle lower position and an operative elevated position with respect to the plane of the support assembly  8  and are implemented in the form of a roller and driving belt combination. In the switch position as shown in  FIG. 1 , the containers  2  travel in the straight transport path so that the associated module  10   b  assumes the elevated disposition above the plane of the support elements  6  of the support assembly, while the modules  10   a,    10   c  for the right and left transport paths are lowered to their idle position. 
   Turning now to  FIG. 2 , there is shown a cutaway perspective view, on an enlarged scale, of the entry zone  3  of the switch  1 . Both driving belts  8   a,    8   b  extend perpendicular to the plane of the support elements  6  and project beyond the support elements  6 . The driving belts  8   a,    8   b  are guided by cylindrical rollers  11 ,  12  which turn about rotation axes also extending perpendicular to the plane of the support elements  6 . The rollers  12  are additionally swingably supported about an offset axis in parallel relationship to the rotation axes of the rollers  11 ,  12  so that the rollers  12  are urged outwardly by the belt and the driving torque of a motor, shown here only by way of pinion  13 . The driving belts  8   a,    8   b  engage the recess  8   c  of the containers  2  for their advance and respectively bear upon the parallel sidewalls  8   d.  As a consequence of the swingable support of the rollers  11 ,  12 , the outwardly directed belt sides are pressed against the sidewalls  8   d  of the recess  8   c.  In this way, possible tolerances of the containers  2  can be compensated in a play-free manner. 
     FIG. 3  is a top perspective view, on an enlarged scale, and  FIG. 4  a front view of the switch zone  4 . The leaf spring  9  is arranged perpendicular to the plane of the support elements  6 , whereby freely rotatable guide rollers  14  in the form of a roller path are arranged on the opposite flat sidewalls of the leaf spring  9 . The leaf spring  9  can be deflected into the desired direction by a rocker arm  15  which interacts with a four-bar linkage  16  with two bars  17   a,  whereby the leading part of the leaf spring  9 , as viewed in transport direction of the containers  2 , is deflected by the rocker arm  15 . 
   Turning now to  FIG. 5 , there is shown a top perspective view of the exit zone  5  of the switch  1 , while  FIG. 6  shows the pertaining front view thereof. As can be seen in  FIG. 5 , the module  10   b  of the propulsion and guide assembly  10  that is provided for straight travel of the containers  2  includes two parallel driving belts  26 , in analogy to the alignment and propulsion mechanism  8 . Thus, as the containers  2  are advanced, the outwardly directed belt sides are pressed against the sidewalls  8   d  of the containers  2 . Both revolving driving belts  26  of module  10   b  provide the necessary propulsion of the containers  2 . The difference to the driving belts  8   a,    8   b  resides in the capability to lower the driving belts  26  to the idle disposition. The module  10   c  for the left transport path and the module  10   a  for the right transport path are slightly differently configured and include only a single driving belt  26  which extends in a curved way and is respectively driven and guided by cylindrical rollers  17 . Disposed parallel to the driving belt  26  of each module  10   a,    10   c  are guide rollers  18  which are lined up to form a roller path. When elevated, the driving belt  26  of the modules  10   a,    10   c  also engages the recess  8   c  of the containers  2  to direct them to the desired transport path. Propulsion is realized by a drive motor having a pinion  19 , as shown in  FIG. 5 . Transmission of the driving torque is hereby implemented by a driving belt  20 . As shown in  FIG. 6 , an additional servomotor, shown here only by way of pinion  21 , is provided and has a motor shaft for support of cams  22 . By means of the servomotor in combination with the cams  22 , lifting elements (not shown) are actuated to selectively elevate and lower the modules  10   a,    10   b,    10   c  of the propulsion and guide assembly  10  in a manner that only one of the modules  10   a,    10   b,    10   c  can be elevated at any time while the other two are idle and in the lowered disposition. 
   Turing now to  FIGS. 7 and 8 , there are shown perspective views of modified embodiments of the alignment and propulsion mechanism  8  and the propulsion and guide assembly  10 . Parts corresponding with those in  FIG. 1  are denoted by identical reference numerals and not explained again. The description below will center on the differences between the embodiments. In the embodiments of  FIGS. 7 and 8 , provision is made for slightly beveled rollers  23 , instead of driving belts. The rollers  23  are arranged behind one another in parallel rows and roll on the sidewalls  8   d  of the recess  8   c.  The sidewalls  8   d  are here inclined to the outside away from one another with increasing outward curving toward their mid-section.  FIG. 7  shows the rollers  23  in a curved section, whereas  FIG. 8  shows the arrangement of rollers  23  in a straight section. 
   Further alternative embodiments are shown in  FIGS. 9 and 10 , whereby the alignment and propulsion mechanism  8  and the propulsion and guide assembly  10  can be configured in the form of a flat-top chain  24  with parallel prisms  25  (or trapezoids). The prisms  25  engage the recess  8   c  of the containers  2 , as shown in  FIG. 10 , to guide and advance the containers  2  through frictional engagement, whereby the outwardly directed prism sides  25   a  rest against the sidewalls  8   d.    
   While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. The embodiments were chosen and described in order to best explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. 
   What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: