Abstract:
A storage device for storing trays, the device including a first movable member and a second movable member positioned opposite the first movable member. The first and second movable members are adapted to selectively vertically move and support at least one tray therebetween. A conveyor moves a tray to transfer position, and a transfer mechanism elevates the tray to a storage position between the two movable members. A stack of nested trays may be stored.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to storage devices, and more particularly to storage devices for storing trays. 
   BACKGROUND OF THE INVENTION 
   Typical handling systems (e.g., distribution systems, sorting systems, and the like) often utilize a container or tray for holding the components being handled. At times during the handling process, these trays may be emptied and stored for future use. Oftentimes, a buffer system is integrated into the handling system to accommodate storage of these empty trays. A buffer system usually includes conveyors, like the conveyors in the handling system, for individually and separately storing the empty trays. In this configuration of a buffer system, the empty trays may occupy large amounts of floor space and excess amounts of machinery (i.e., conveyors) for storing the empty trays. In addition, the empty trays must be transferred between the handling system and the buffer system upon storage, and from the buffer system back to the handling system for re-entry into the handling system. As a result of a complicated transfer point between the handling and buffer systems, a complicated transfer mechanism is typically required to transfer the empty trays between the handling and buffer systems. Such a transfer mechanism may also occupy large amounts of floor space. 
   SUMMARY OF THE INVENTION 
   The present invention provides a storage device for storing trays. The storage device includes a first movable member and a second movable member positioned opposite the first movable member. The first and second movable members selectively vertically support at least one tray therebetween. 
   The present invention also provides a method for storing trays. The method includes transporting a first tray to a transfer position, vertically transferring the first tray from the transfer position to a storage position, and supporting the first tray in the storage position by two opposed movable members. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, wherein like reference numerals indicate like parts: 
       FIG. 1  is a perspective view of a storage device of the present invention; 
       FIG. 2  is a front view of the storage device of  FIG. 1 , illustrating a tray being conveyed to a transfer position relative to the storage device; 
       FIG. 3  is a front view of the storage device of  FIG. 1 , illustrating a tray being transferred from the transfer position to a storage position; 
       FIG. 4  is a front view of another construction of the storage device, illustrating a tray being conveyed to the transfer position; 
       FIG. 5  is a front view of the storage device of  FIG. 4 , illustrating a tray being transferred from the transfer position to the storage position; 
       FIG. 6  is a front view of yet another construction of the storage device, illustrating a tray being conveyed to the transfer position; and 
       FIG. 7  is a front view of the storage device of  FIG. 6 , illustrating a tray being transferred from the transfer position to the storage position. 
   

   Before any features of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited. 
   DETAILED DESCRIPTION 
   With reference to  FIG. 1 , a storage device  10  is utilized to vertically support empty trays  14  in a nested configuration. However, the storage device  10  may also be used to store trays  14  containing material. As used herein, a “tray” may be defined to include anything that may hold an object (i.e., the tray may be in the form of a substantially flat sheet, or in the form of a container having a depth). In the exemplary constructions, the storage device  10  takes advantage of the tapered shape of the trays  14  in that an inherent, predictable, and consistent spacing occurs between adjacent trays  14  upon nesting the trays  14 . However, in other constructions of the storage device (not shown), any other tray configuration that provides predictable and consistent spacing between adjacent trays  14  may be used. The trays  14  shown and described herein may be utilized to carry, handle, and/or store mail or other parcels or packages. 
   The storage device  10  includes two opposed movable members in the form of rotatable members, such as wheels  18 , positioned above a conveyor  22 . The conveyor  22  is a portion of a handling system (not shown) for transporting trays  14 . As shown in  FIGS. 2–3 , the spacing between the wheels  18  is selected to receive the trays  14  therebetween from the conveyor  22 . In one construction of the storage device  10 , the wheels  18  include teeth  26  extending from their outer surfaces to engage a lip or rim  30  projecting from each tray  14  to support the trays  14  in a vertical column or stack  31 . However, in other constructions of the storage device, the trays  14  may be supported in a substantially vertical column or stack, such that the stack may be tilted relative to the ground or other supporting surface. The teeth  26  have a pitch corresponding with the inherent spacing of the trays  14  when the trays  14  are nested. The teeth  26  also include tapered surfaces  32 , such that the rim  30  of a particular tray  14  may be smoothly engaged upon sliding contact between the teeth  26  and the rim  30 . However, the teeth  26  may include any of a number of different shapes that provide smooth engagement with the rim  30  of a tray  14 . 
   Another construction of the storage device  210  is shown in  FIGS. 4–5 . The storage device  210  is similar to the storage device  10  of  FIGS. 1–3 , except the movable members are in the form of different rotatable members, such as opposed wheels  218  having respective outer frictional surfaces  222 . As such, like components are labeled with like reference numerals. The storage device  210  may be particularly useful in handling trays  214  that do not include rims or lips therearound. The respective outer frictional surfaces  222  of the opposing wheels  218  frictionally engage opposite sides  212  of the trays  214  to support the trays  214  in a vertical column or stack  231 . The wheels  218  may include resilient coverings  234  (e.g., rubber coverings) that at least partially deform upon supporting a tray  214  therebetween, such that frictional forces are developed between the respective outer frictional surfaces  222  and the sides  212  of the trays  214  to maintain the tray  214  in position between the wheels  218 . Further, the outer frictional surfaces  222  may include some sort of gripping surfaces (e.g., raised or knurled surfaces) to provide additional grip on the sides  212  of the trays  214 . 
   Yet another construction of the storage device  310  is shown in  FIGS. 6–7 . The storage device  310  is similar to the storage device  10  of  FIGS. 1–3 , except the movable members are in the form of opposed belts  318 . As such, like components are labeled with like reference numerals. The belts  318  may be continuous belts arranged in any of a number of different belt runs. However, the belts  318  may also be discontinuous, such that the belts  318  have distinguishable ends that are wound and unwound on respective spools (not shown) depending on the direction of movement of the belts  318 . At least one roller  320  in each belt run may be driven to provide movement to a respective belt  318 . 
   The belts  318  include projections  326  extending therefrom to engage a rim  330  projecting from each tray  314  to support the trays  314  in a vertical column or stack  331 . The projections  326  have a pitch corresponding with the inherent spacing of the trays  314  when the trays  314  are nested. The projections  326  also include tapered surfaces  332 , such that the rim  330  of a particular tray  314  may be smoothly engaged upon sliding contact between the projections  326  and the rim  330 . However, the projections  326  may include any of a number of different shapes that provide smooth engagement with the rim  330  of a tray  314 . 
   As shown in  FIG. 1 , the wheels  18  are powered by a drive mechanism  34 . For proper operation of the storage device  10 , the wheels  18  should be synchronized and driven in opposite directions (as shown in  FIG. 3 ). In one construction of the storage device  10 , the drive mechanism  34  may utilize a mechanical linkage  36  coupling the two wheels  18  to ensure that the two wheels  18  are synchronized. The mechanical linkage  36  is driven by a motor  38 , such as a servo-motor, or a stepper motor providing a stepped torque input to the mechanical linkage  36  rather than a continuous torque input. Such a mechanical linkage  36  may include a gear train  42 , which provides a torque output to each wheel  18 . The mechanical linkage  36  may be any of a number of conventional designs, and should not be limited by the gear train  42  illustrated in  FIG. 1 . A controller  46  may be electrically connected with the motor  38  and the handling system&#39;s control system (not shown) to control operation of the motor  38  and subsequently the wheels  18 . A sensor  48  may also be positioned adjacent the conveyor  22  for detecting a presence or absence of a tray  14 . Further, the sensor  48  may be electrically connected with the controller  46  to provide a signal to the controller  46  upon detecting or not detecting a tray  14  on the conveyor  22 . However, any number of alternate sensing devices may be utilized to detect the presence or absence of a tray  14  on the conveyor  22 . 
   In another construction of the storage device  10 , the drive mechanism  34  may utilize an electronic linkage coupling the two wheels  18  to ensure that the two wheels  18  are synchronized. Such an electronic linkage may include individual motors  50  providing torque inputs to the respective wheels  18 . The motors  50  may be electrically connected to the controller  46 , which operates the two motors  50  in synchronism with one another. Like the motor  38  driving the mechanical linkage  36 , the motors  50  may also be servo-motors, or stepper motors providing stepped torque inputs to the wheels  18  rather than a continuous torque input. Further, the sensor  48  may be electrically connected with the controller  46  to provide a signal to the controller  46  upon detecting or not detecting a tray  14  on the conveyor  22 . Further, similar drive mechanisms may also be used to drive the wheels  218  of the storage device  210  of  FIGS. 4–5 , and the rollers  320  of the storage device  310  of  FIGS. 6–7 . 
   A frame (not shown) may support the wheels  18  and the drive mechanism  34  relative to the conveyor  22 . Further, the frame may be adjustable to accommodate different size trays  14  to be stored. The drive mechanism  34  utilizing the electronic linkage between the individual motors  50  is especially adept to an adjustable frame for accommodating different size trays  14  since the distance between the wheels  18  may be changed. A shroud  54  (see  FIGS. 2–3 ) supported by the frame or other structure may also be placed over the wheels  18  and the trays  14  to provide a barrier between the wheels  18  and their surrounding environment and lateral support to the stack  31  of nested trays  14  supported by the wheels  18 . 
   A transfer mechanism  58  in the form of a lifter  62  transfers selective trays  14  from the conveyor  22  toward the wheels  18  for storage. The lifter  62  includes multiple projections, or tines  66  that are insertable between individual rollers  70  of a portion of the conveyor defining a transfer position  72 . During operation of the lifter  62 , the tines  66  vertically protrude through the conveyor  22  to abut a bottom surface  74  of a select tray  14   a  (see  FIG. 2 ) to lift the tray  14   a  from the conveyor  22  toward the wheels  18  for storage in a storage position  78 . The lifter  62  may be driven by any of a number of mechanisms, such as a pneumatic or hydraulic cylinder  82 , a rack and pinion linkage (not shown), and the like. Further, the transfer mechanism  58  may be electrically connected with the controller  46  to receive an operating signal from the controller  46 . 
     FIGS. 4–5  illustrate multiple suction devices  234  coupled to the ends of the tines  66 . The suction devices  234  are operable to grip the bottom surface  274  of a tray  214  when moving the tray  214  from the transfer position  72  to the storage position  78 , or from the storage position  78  to the transfer position  72 . The suction devices  234  may be in the form of conventional suction cups that cling onto the bottom surface  274  of the tray  214  when pressed against the bottom surface  274  of the tray  214 . However, the suction devices  234  may also be in the form of suction cups that are fluidly connected with a vacuum source  242 . The vacuum source  242  may be electrically connected with the controller  46  to selectively draw a vacuum from the suction cups upon the suction cups abutting against the bottom surface  274  of the tray  214 . As shown in  FIGS. 4–5 , only one of the suction devices  234  is fluidly connected to the vacuum source  242 . However, in other constructions of the storage device  210 , more than one of the suction devices  234  may be fluidly connected with the vacuum source. Also, although the suction devices  234  and the vacuum source  242  are shown being utilized in the storage device  210  of  FIGS. 4–5 , the suction devices  234  and the vacuum source  242  may also be utilized in the storage device  10  of  FIGS. 1–3  or the storage device  310  of  FIGS. 6–7 . 
   During operation of the storage device  10  in combination with the handling system, the conveyor  22  is initially loaded with successive trays  14 . The sensor  48  detects the presence or absence of a tray  14  on the conveyor  22  as the successive trays  14  move toward the transfer position  72 . The sensor  48  interfaces with the controller  46 , and perhaps the handling system&#39;s control system, to determine whether or not any particular tray  14   a  should be stored or allowed to pass by the storage device  10  en route to another portion of the handling system, or whether a stored tray  14   b  should be lowered onto the conveyor  22  for re-entry into the handling system (see  FIG. 2 ). 
   In one manner of operation of the storage device  10 , the sensor  48  may detect a particular tray  14   a  on the conveyor  22  and the handling system&#39;s control system may designate the tray  14   a  as one to be stored. The conveyor  22  then transports the tray  14   a  to the transfer position  72 , whereby the tray  14   a  is positioned directly above the lifter  62 . The lifter  62  is then actuated upwards through the conveyor  22  to abut the bottom surface  74  of the tray  14   a  and lift the tray  14   a  off the conveyor  22  (see  FIG. 3 ). At this time, the suction devices  234  and/or the vacuum source  242  may be employed to cling onto the bottom surface  74  of the tray  14   a  to provide the lifter  62  with a firm grasp of the tray  14   a . The lifter  62  lifts the tray  14   a  up to a point whereby the teeth  26  of the opposed wheels  18  can engage the rim  30  of the tray  14   a . The wheels  18  are then driven incrementally so that the teeth  26  engage the rim  30  of the tray  14   a  and lift the tray  14   a  off the lifter  62 . If the suction devices  234  and/or the vacuum source  242  are being employed, the vacuum source  242  is deactivated at some time before the tray  14   a  is lifted off of the lifter  62  to release the tray  14   a . If an existing tray  14   b  is already being supported by the wheels  18 , then the tray  14   b  becomes nested within the tray  14   a  upon the tray  14   a  being raised by the lifter  62  and engaged by the wheels  18 . Further rotation of the wheels  18  upwardly displaces the tray  14   b . Subsequent trays  14  being stored in this manner are upwardly displaced relative to the handling system and form the vertical column or stack  31  of nested trays  14  in the storage position  78 . 
   In another manner of operation of the storage device  10 , the sensor  48  may detect a particular tray  14  on the conveyor  22  and the handling system&#39;s control system may designate the tray  14  for use in a later portion of the handling system. The particular tray  14  is then allowed to pass by the transfer position  72  without being transferred to the storage position  78 . 
   In yet another manner of operation of the storage device  10 , the sensor  48  may detect the absence of a tray  14 , and the handling system&#39;s control system may determine that a stored tray  14  should re-enter the handling system by filling the vacancy on the conveyor  22 . In this instance, the lifter  62  is actuated upwards to a point whereby the tips of the tines  66  are slightly below the bottom surface  74  of the lowest tray  14   a  (see  FIG. 3 ) that is to re-enter the handling system. The wheels  18  are then incrementally driven so that the tray  14   a  is downwardly displaced and separated from the stack  31  of nested trays  14 , and further allowed to fall onto the tines  66 . 
   The trays  14  may include integrally formed stops  86  extending from the bottom walls of the trays  14  to provide consistent nesting between the trays  14  and to prevent the trays  14  from nesting too close together such that any two nested trays  14  may not be readily separated. As a result, the lowest tray  14   a  (see  FIG. 3 ) in the stack  31  of nested trays  14  should easily separate from the stack  31  of nested trays  14  and fall onto the tines  66 . However, the suction devices  234  and/or the vacuum source  242  may be used to grasp the lowest tray  14   a  to forcibly separate the tray  14   a  from the stack  31 . The lifter  62  then moves downward and places the bottom surface  74  of the tray  14  back onto the conveyor  22  in a location corresponding with the vacancy sensed by the sensor  48 . 
   Operation of the storage device  210  is substantially similar to the previously-described operation of the storage device  10 , with the exception that the outer frictional surfaces  222  engage opposite sides  212  of the tray  214  rather than the rim  30  of the tray  14 . 
   Operation of the storage device  310  is also substantially similar to the previously-described operation of the storage device  10 . However, since opposed projections  326  on the belts  318  may support at least one tray therebetween, the trays  314  are not required to nest within each other. In such a configuration, two opposed projections  326  may only be responsible for supporting the weight of one tray  314 , rather than multiple trays  314 . Further, a shroud or protective guard may be positioned around the belts  318  and/or the stack  331 .