Patent Publication Number: US-2009229488-A1

Title: Pivot Wheel Assembly and Powered Pallet with Pivot Wheel Assembly

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/988,310, filed Nov. 15, 2007, which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The disclosure herein relates generally to a pallet apparatus for moving parts and materials in a manufacturing environment. 
     BACKGROUND 
     Various powered pallet assemblies (“powered pallets”) have different mechanisms for changing direction of the pallet. Powered pallets may be designed for use on trackways or for use on floors. An example of a powered pallet for use on intersecting trackways is the PowerPallet™, available from Ward Systems, Inc. The PowerPallet™ is described in U.S. Pat. No. 5,857,413 and uses multiple cams and gears to effect the change in wheel direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the course of the detailed description to follow, reference will be made to the attached drawings. These drawings show different aspects of the present invention and, where appropriate, reference numerals illustrating like structures, components, materials and/or elements in different figures are labeled similarly. It is understood that various combinations of the structures, components, materials and/or elements, other than those specifically shown, are contemplated and are within the scope of the present inventions. 
         FIG. 1  is a view of a powered pallet assembly, according to an embodiment; 
         FIG. 2  is an exploded view of a powered pallet end, according to an embodiment; 
         FIG. 3  is a top view of a wheel pivot assembly with locking mechanism, according to an embodiment; 
         FIG. 4  is a bottom view of a wheel pivot assembly with a wheel pivot lock, according to an embodiment; 
         FIG. 5  is a view of a wheel pivot mechanism, according to an embodiment; 
         FIG. 6  is an exploded view of a wheel pivot mechanism, according to an embodiment; 
         FIG. 7  is a view of a wheel pivot lock, according to an embodiment; 
         FIG. 8  is an exploded view of a wheel pivot lock, according to an embodiment; 
         FIG. 9  is a view of a manual control enclosure, according to an embodiment; 
         FIG. 10  is an exploded view of a manual control enclosure, according to an embodiment; 
         FIG. 11  is view of an alternative embodiment of a powered pallet assembly, according to an embodiment; and 
         FIG. 12  is a view of two pivot wheels of the assembly of  FIG. 11 , according to an embodiment. 
     
    
    
     DESCRIPTION 
     Embodiments of a powered pallet assembly as shown in the drawings and described herein reduce the parts count of a pallet compared to prior pallet, while allowing versatile movement of the pallet, including rotation of the entire pallet itself. 
     In an embodiment a pallet has one wheel on each of four corners. Each corner wheel is driven by its own motor. The wheel assembly pivots and locks in the two 90 degree positions used for X and Y travel. In some embodiments, each wheel assembly can be positioned in various positions in addition to the 90 degree positions. For example, the four wheel assemblies can be positioned to allow the entire pallet to rotate about its own center. 
     Four pivoting corner wheel/motor assemblies allow direction change and provide drive force for movement. 
     The pivot wheel assembly is suitable for a motorized (“powered”) pallet that drives from location to location within a conveyor environment. For example, the pivot wheel assembly and system can supplement the existing PowerPallet™ with a new method of changing the wheel direction and a new method of providing a drive system. Other applications are also possible. 
     In an embodiment, to change the orientation of a drive wheels, the wheel/motor assembly is unlocked. The motor then drives the wheel. The pivot point for the wheel/motor assembly is off center from the drive wheel. This causes the wheel/motor mechanism to freely rotate about its pivot point while the drive wheel is driving. The lock is released and the pivot assembly locks into the new orientation. This orientation is typically 90 degrees to the original orientation but can be at any angular orientation that facilitates the next directional use of the drive system. 
     The wheel/motor assembly forms an integral mechanism that is a rotating assembly. To change the direction the rotating assembly is unlocked and the wheels being off center with the pivot point become the drive force to pivot the wheels. The drive motors for each wheel assembly are used to drive the pallet in a direction and also to change the wheel orientation. 
     The figures show various elements of versions of a powered pallet including the pivot wheel assembly and system. 
       FIG. 1  is a view of a partially disassembled powered pallet  100  according to an embodiment. The pallet  100  includes a two pallet ends  104  and a cross beam  102  which make up the pallet structure. The pallet end  104  includes two pivot wheel assemblies as further illustrated and described below. Pallet ends  104  will also be referred to as wheel assemblies  104  herein. The pallet  100  is assembled by connecting each of the two pallet ends  104  to the cross beam  102 . The pallet  100  is just one example of a pallet configuration that can use the novel pivot wheel assembly as described herein. The configuration of the pallet  100  is chosen based on the dimensions and weight of the load the pallet is expected to bear. In other embodiments, the pallet may consist of essentially two wheel assemblies  104  connected to each other directly or to a much shorter cross beam in proportion to the dimensions of the wheel assembly  104 . In yet other embodiments (as shown with reference to  FIG. 11  for example), the pallet may include a rectangular frame structure supported by four wheel assemblies. 
       FIG. 2  is an exploded view of the wheel assembly  104 . A top plate structure  1  is a main structural component of each wheel assembly  104  (also referred to as pallet ends  104  or ends  104 ) to which many of the other components attach. Attached to and below the top plate structure  1  are pivot wheel assemblies  8  and  9 , vertical structural members  22  and  23 , and a skirt  33 . Attached to and above the top plate structure  1  are all of the electronic components, pivot lock actuators and covers  7 ,  24 , and  25 . 
     The powered pallet end  104  includes two pivot wheel assemblies, a left pivot wheel assembly  8  and a right pivot wheel assembly  9 , and a pivot latch  30 . Also shown are a mating plate  2 , a gear enclosure  7 , a battery tray  19 , and a battery tray support  21 . The power pallet end  104  further includes a left structure  22 , a right structure  23 , a controls enclosure  24  and  25 , and a front skirt  33 . 
       FIG. 3  is a view of a pivot wheel assembly  300  including a pivot wheel and wheel pivot lock showing the top portion of the assembly.  FIG. 4  is a view of the pivot wheel assembly  300  showing the bottom portion of the assembly. 
       FIG. 5  is a view of a pivot wheel assembly  500  without a wheel pivot lock.  FIG. 6  is an exploded view of the pivot wheel assembly  500 . The pivot wheel assembly  500  is pivotable about an axis defined by the center of a pivot shaft  716 . Shown disassembled from the pivot shaft  716  are a pivot cup  71 , a retaining ring  714 , a bearing  75 , washers  710  and  711 , a jam nut  79 , and a pivot cap  724 . 
     A wheel drive motor  712  is operable to drive a wheel  77  about its axis in one configuration, and also to rotate the assembly  500  about the pivot shaft  716  in another configuration. Screws  722  and  726  connect the motor  712  to a motor mount  72 . A drive shaft coupling  74  and an axle  73  form part of a drive assembly connecting to the pivot shaft  716 . A screw  719  retains the axel  73  in the pivot shaft  716 . The drive assembly further includes a retaining ring  713 , a bearing  75 , a nut  715 , the wheel  77 , and a drive shaft insert  725  retained by screws  721 . 
     A stop plate  718  includes detents as shown that allow the assembly to be fixed in a particular position such that the wheel  77  is oriented in a particular way with respect to the X-Y axis shown. For example, the wheel  77  is currently shown oriented so that it turns along the Y axis. The assembly  500  can also be oriented so that the wheel  77  turns along the X axis. As further described below, a pivot locking mechanism engages with the detents of the stop plate  718  to retain the assembly  50  in a particular position. 
     A stop plate mount  717  is connected to the stop plate  718  by dowels  720  and screw  719 , and also to the pivot shaft  716  by screws  723 . 
       FIG. 7  is a wheel pivot lock  700  in an embodiment.  FIG. 8  is an exploded view of the wheel pivot lock  700 . Wheel pivot lock  700  includes a pivot shaft bearing housing  81 , a cam follower lever  85 , a lock release lever  84 , and a lock release actuator  88 . A cam follower  83  is connected the cam follower lever  85  with a screw  82 . The cam follower  83  engages one of the detents in the stop plate  718  (as can be seen in assembly  300 ,  FIGS. 3 and 4 ) to retain the wheel assembly  500  in a particular orientation. 
     The wheel pivot lock  700  further includes bearings  87  and lock release lever  86 . The actuator  88  is electrically powered and moves lock release lever  84  so as to engage and disengage the cam follower  83  with respect to the detents in the stop plate  718 . In operation, the lock release actuator  88  pulls the lock release lever  84  rotating shaft  86  swinging the lever  85  moving the cam follower  83  out of engagement with the lock plate  718 . 
       FIG. 9  is a view of a manual control enclosure and control panel  900  according to an embodiment.  FIG. 10  is an exploded view of the enclosure  900  a frame  91  receives an On-Off switch  93  and an Emergency Off switch  92 . A battery connector  94  is assembled to the frame  91  by nuts  99 . Light emitting diodes (LEDs)  96 ,  97  and  98  signal various states of the powered pallet during operation. The control panel  900  is attached to the top plate structure  1  and is under the cover  25  (see  FIG. 2 ) 
       FIG. 11  is a view of an alternative embodiment of a powered pallet  1100  with pivot wheel assemblies. The pallet  1100  includes four pivot wheel assemblies  1110 ,  1112 ,  1114 , and  1116  supporting a rectangular pallet structure. The pallet  1100  is suitable for heavier loads than the pallet  100 , but the principles of operation are similar between the two pallets. 
       1106  and  1108  are lock pin mechanisms. Lock pin mechanisms  1108  are used to lock the pallet to the floor or track structure. Lock pin mechanism  1106  is used to lock the pallet for rotation about its center point. 
       FIG. 12  is a view of two pivot wheel assemblies  1110  and  1112 . A wheel pivot wheel and wheel pivot lock assembly  1204  is partially visible and includes a wheel  1202 . The wheel  1202  is shown in a position between the X and Y axes. When all four wheels are rotated to this intermediate position, the pallet  1100  can be rotated in a circle. The wheel  1203  is shown in an orientation that allows the wheel to travel along the X axis. The wheels  1202  and  1203  are grooved so as to ride on a particular track. However, in different embodiments the wheels be designed to travel on a different type of track, or include rubber tires for traveling on a floor. In other embodiments, the pallet may be large enough to require more than pivot four wheel assemblies. For example, the pallet may include one pivot wheel assembly at each of four corners of a rectangular pallet and two or more additional pivot wheel assemblies located along the edges of the rectangular pallet structure. Holes  1211  are detents for locking mechanisms. 
     Embodiments as disclosed and claimed herein include a pivot wheel assembly, comprising: a motor coupled to drive a drive shaft; a wheel coupled to the drive shaft so as to be driven about a first axis of rotation defined by the drive shaft when the assembly is in a locked configuration; and a pivot shaft coupled to the drive shaft, wherein the pivot shaft defines a second axis of rotation that is orthogonal to the first axis of rotation, wherein the motor drives the assembly about the second axis of rotation when the assembly is in a unlocked configuration. 
     Embodiments further comprise a stop plate coupled to the pivot shaft. 
     Embodiments further comprise a wheel pivot lock configured to engage the stop plate for retaining the assembly in the locked configuration. 
     In an embodiment, the locked configuration comprises one of a plurality of positions for the wheel about the second axis of rotation. 
     In an embodiment, the stop plate comprises a plurality of detents, and wherein the wheel pivot lock comprises a cam follower that engages one of the plurality of detents when the assembly is in the locked configuration. 
     In an embodiment, the wheel pivot lock comprises an actuator coupled to a lock release lever and operable to move the lock release lever to configure the assembly in the unlocked configuration. 
     In an embodiment, the wheel pivot lock further comprises a pivot arm stop cam and a cam follower coupled to the lock release lever and configured to engage the stop plate. 
     Embodiments further include a powered pallet comprising: four wheels each coupled to a drive shaft, each drive shaft defining a first axis of rotation about the center of each wheel, wherein the four wheels are positioned with respect to each other to support four corners of a rectangular pallet structure; four pivot shafts each coupled to one of the drive shafts, wherein each pivot shaft defines a second axis of rotation orthogonal to a respective first axis of rotation; four motors, wherein each motor is coupleable to drive one of the drive shafts; and four wheel pivot locks, each configurable to place a motor and respective wheel in a locked or an unlocked configuration, wherein in the locked configuration a motor causes a respective drive shaft to rotate while a respective pivot shaft does not rotate, and wherein the unlocked position, the motor causes the respective drive shaft to rotate while the respective pivot shaft also rotates. 
     In an embodiment, the first axis of rotation for each of the four wheels is rotatable about the second axis of rotation in the unlocked configuration. 
     In an embodiment, the direction of travel of the pallet structure is changeable by rotating the first axis of rotation for each of the four wheels. 
     In an embodiment, the pallet structure is configurable to rotate in place by configuring the location of the first axis of rotation for each of the four wheels. 
     An embodiment further comprises four actuators for manipulating each of the four wheel pivot locks. 
     In an embodiment, the four actuators are electronic. 
     In an embodiment, the wheels travel on one or more tracks that are oriented at angles to one another, each defining a direction of travel. 
     Other embodiments include a powered pallet comprising: a plurality of pivot wheel assemblies, each pivot wheel assembly comprising, a motor coupled to drive a drive shaft; a wheel coupled to the drive shaft so as to be driven about a first axis of rotation defined by the drive shaft when the assembly is in a locked configuration; and a pivot shaft coupled to the drive shaft, wherein the pivot shaft defines a second axis of rotation that is orthogonal to the first axis of rotation, wherein the motor drives the assembly about the second axis of rotation when the assembly is in a unlocked configuration. 
     In an embodiment, each pivot wheel assembly further comprises a stop plate coupled to the pivot shaft. 
     In an embodiment, each pivot wheel assembly further comprises a wheel pivot lock configured to engage the stop plate for retaining the assembly in the locked configuration. 
     In an embodiment, the locked configuration comprises one of a plurality of positions for the wheel about the second axis of rotation. 
     In an embodiment, the stop plate comprises a plurality of detents, and wherein the wheel pivot lock comprises a cam follower that engages one of the plurality of detents when the assembly is in the locked configuration. 
     In an embodiment, the wheel pivot lock comprises an actuator coupled to a lock release lever and operable to move the lock release lever to configure the assembly in the unlocked configuration. 
     In an embodiment, the wheel pivot lock further comprises a pivot arm stop cam and a cam follower coupled to the lock release lever and configured to engage the stop plate.