Patent Publication Number: US-2016244166-A1

Title: Cargo Power Drive Unit With Water Extraction Mechanism

Description:
BACKGROUND 
     Cargo aircraft commonly include cargo floors that have a number of incorporated rollers that facilitate the movement and manipulation of cargo loaded onto pallets. There may also be a number of power drive units (PDUs) mounted within the cargo floors. A conventional PDU includes an actuator-driven drive wheel that is sized to engage a bottom surface of a pallet when positioned on the rollers. When activated, the drive wheels of the PDUs rotate, moving the cargo pallets forward or rearward along the cargo floor over the rollers, which freely rotate. 
     When cargo and the associated pallets are wet due to rain or snow, the water falls onto the cargo floor. Cargo floors include drains for effective water removal, however, the water flowing to the floor drains often falls around the drive wheels into the drive wheel compartments of the PDUs. Water within the PDUs is undesirable since wet drive wheels may slip when engaging pallets, decreasing the efficiency of the pallet loading or unloading operation. To combat this issue, conventional PDUs include a drain that allows the water within the drive wheel compartments to be routed to a system of drain tubes connecting the PDUs to a holding tank from which the water may be removed or disposed of This system of drain tubes adds significant weight and expense to the aircraft. 
     It is with respect to these considerations and others that the disclosure made herein is presented. 
     SUMMARY 
     It should be appreciated that this Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to be used to limit the scope of the claimed subject matter. 
     Apparatus and methods described herein provide for a cargo power drive unit with a water extraction mechanism. According to one aspect, a PDU for moving pallets over a cargo floor in a wet environment is provided. The PDU may include a PDU housing that is configured for installation within the cargo floor. A PDU drive wheel is positioned within a drive wheel compartment of the PDU housing. The PDU drive wheel extends a height H above the cargo floor. A water barrier is positioned around a top portion of the PDU housing, extending a distance less than the height H. A water extraction mechanism is configured to transfer water from a sump portion of the drive wheel compartment to the cargo floor outside of the water barrier. 
     According to another aspect, a method for moving pallets over a cargo floor in a wet environment is provided. According to the method, a PDU drive wheel is activated within a drive wheel compartment of a PDU housing. A bottom surface of a pallet is engaged with the PDU drive wheel to move the pallet. Water is routed around the drive wheel compartment with a water barrier positioned around a top portion of the PDU housing. Water is transferred from a sump portion of the drive wheel compartment to the cargo floor outside of the water barrier via a water extraction mechanism. 
     According to yet another aspect, a PDU for moving pallets over a cargo floor in a wet environment includes a PDU housing configured for removable installation within the cargo floor. A PDU drive wheel is positioned within a drive wheel compartment of the PDU housing. The PDU drive wheel extends a height H above the cargo floor. A motor is positioned within the PDU housing and operates to rotate the PDU drive wheel. A water barrier is positioned around a top portion of the PDU housing and extends a distance less than the height H above the cargo floor. A water conduit is positioned within the PDU housing, providing a conduit from a sump portion of the drive wheel compartment to an exterior side of the water barrier. A pump is positioned within the PDU housing and is operative to pump water from the sump portion of the housing through the water conduit to the cargo floor on the exterior side of the water barrier. 
     The features, functions, and advantages that have been discussed can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view and cross-sectional view of a PDU for moving pallets over a cargo floor in a wet environment, illustrating a water barrier positioned around an outer edge of a PDU housing according to various embodiments described herein; 
         FIG. 2  is a perspective top view of a PDU for moving pallets over a cargo floor in a wet environment, illustrating a water barrier positioned around an outer edge of a PDU housing according to various embodiments described herein; 
         FIG. 3  is a side view and cross-sectional view of a PDU for moving pallets over a cargo floor in a wet environment, illustrating a water barrier positioned around a perimeter of a drive wheel compartment of the PDU housing with a water extraction mechanism positioned within the drive wheel compartment according to various embodiments described herein; 
         FIG. 4  is perspective top view of a PDU for moving pallets over a cargo floor in a wet environment, illustrating a water barrier positioned around a perimeter of a drive wheel compartment of the PDU housing according to various embodiments described herein; 
         FIG. 5  is a side view and cross-sectional view of a PDU for moving pallets over a cargo floor in a wet environment, illustrating a water barrier positioned around a perimeter of a drive wheel compartment of the PDU housing with a water extraction mechanism positioned outside of the drive wheel compartment according to various embodiments described herein; and 
         FIG. 6  is a flow diagram showing a method for moving pallets over a cargo floor in a wet environment according to various embodiments presented herein. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is directed to a cargo power drive unit with a water extraction mechanism and corresponding method that utilizes a water barrier for routing water around a PDU drive wheel, and a water extraction mechanism for transferring water from a drive wheel compartment to the cargo floor external to the water barrier. As discussed above, traditional PDUs include a water drain that is connected to a system of pipes or tubes that carry the water from all PDUs to one or more collection tanks. This plumbing adds a significant amount of weight to the aircraft along with the associated cost of the plumbing and associated hardware. 
     Utilizing the concepts and technologies described herein, water from cargo and pallets is routed around the PDUs using water barriers. Any water that enters the drive wheel compartments is pumped out of the compartment to the cargo floor, where the water is routed to the existing cargo floor drains. In doing so, all of the conventional drains associated with PDUs, as well as the associated holding tanks, may be eliminated, saving the corresponding weight and cost of the drain components. Various embodiments will be described in which a water barrier is used to route water from the cargo floor around a PDU, or around the drive wheel compartment of a PDU. A water extraction mechanism associated with each PDU is used to pump water out and back onto the cargo floor. Various implementations of the water extraction mechanism will be described in which some or all of the components of the water extraction mechanism may be located within the drive wheel compartment, external to the drive wheel compartment but within the PDU housing, and/or on top of the PDU housing. Moreover, according to various embodiments described below, the water extraction mechanism and water barrier may be an integral part of a PDU, or may be attachable to a PDU, which allows for use with existing conventional PDUs. 
     In the following detailed description, references are made to the accompanying drawings that form a part hereof, and which are shown by way of illustration, specific embodiments, or examples. Referring now to the drawings, in which like numerals represent like elements through the several figures, a cargo power drive unit with a water extraction mechanism and method for employing the same according to the various embodiments will be described. 
       FIG. 1  shows a side view and cross-sectional view of a PDU  100  for moving pallets  102  over a cargo floor  108  in a wet environment, illustrating a water barrier  120  positioned around an outer edge of a PDU housing  112  according to various embodiments described herein. Looking at  FIG. 1 , an example environment is shown according to various embodiments in which cargo  104  on a pallet  102  is being moved across a cargo floor  108  on rollers  106 . To assist in moving the cargo  104  over the rollers  106 , a PDU  100  is used. The PDU  100  includes a PDU housing  112  installed within the cargo floor  108 . The PDU housing  112  encompasses a drive wheel compartment  114 , which houses a PDU drive wheel  116 . The PDU drive wheel  116  is rotated using a motor  118 . The motor  118  is operatively coupled to the PDU drive wheel  116 , and configured to rotate the PDU drive wheel  116  in a manner known by those with skill in the art. 
     The PDU drive wheel  116  is positioned within the drive wheel compartment  114  of the PDU housing  112  and extends a height H 1  above the cargo floor  108 . The height H 1  corresponds to the height of the bottom of the pallet  102  as the pallet  102  sits on the rollers  106 . As the pallet  102  slides over the top of the PDU drive wheel  116 , the PDU drive wheel  116  frictionally engages the pallet  102  to drive the pallet  102  and corresponding cargo  104  over the PDU  100  to adjacent rollers  106  and the next PDU  100 . 
     According to various embodiments, the PDU  100  includes a water barrier  120  that prevents water from flowing into the drive wheel compartment  114  by routing the water around the PDU  100 . The water barrier  120  is positioned around a top portion  132  of the PDU housing  112  and extends a height H 2  above the cargo floor  108 . The top portion  132  of the PDU housing  112  may include the outer edge  202  of the PDU housing  112 , as shown in  FIGS. 1 and 2 . Alternatively, the top portion  132  of the PDU housing  112  may include the outer edge  302  of the drive wheel compartment  114 , as shown in  FIGS. 3-5 . 
     The height H 2  of the water barrier  120  is less than the height H 1  of the PDU drive wheel  116 , as well as of the rollers  106 , so that the water barrier  120  does not interfere with the movement of the pallet  102 . The height H 1  of the rollers  106  and the PDU drive wheel  116  is approximately equivalent since both contact the bottom surface of the pallet  102  to assist in moving the pallet  102  along the cargo floor  108 . 
     The water barrier  120  may be manufactured from a metallic or non-metallic material such as aluminum, fiberglass, plastic, rubber, or other suitable material. According to one embodiment, the water barrier  120  may be manufactured from a flexible material so that it may be placed in any desired configuration around the top portion  132  of the PDU housing  112 . For example, it may be desirable to bend or turn the water barrier  120  around a roller  106  or other obstruction on the cargo floor  108  in a specific location, where the bed or turn may not be needed or desirable in another location for another PDU within the cargo floor  108 . The water barrier  120  may be fixedly or removably attached to the top portion  132  of the PDU housing  112 . For example, the water barrier  120  may be welded in place, attached via fasteners or adhesive, or may be press fit into a gap between the PDU  100  and the cargo floor  108 . Alternatively, the water barrier  120  may be attached using magnets, clips, snaps, tape, hook and loop fasteners, or any other suitable fasteners. 
     The PDU  100  includes a water extraction mechanism  122  configured to transfer water from a sump portion  128  of the drive wheel compartment  114  to the cargo floor  108  outside of the water barrier  120  via PDU water outlet  136 A or  136 B (generally referred to as PDU water outlet  136 ). The water extraction mechanism  122  may include a pump  124  and a water conduit  126 . The water conduit  126  fluidly couples the sump portion  128  of the drive wheel compartment  114  to an exterior side of the water barrier  120  so that water from the sump portion  128  may be transferred to the cargo floor  108  outside of the PDU  100 . The pump  124  is fluidly coupled to the water conduit and is operative to pump the water from the sump portion  128  to the cargo floor  108  via the PDU water outlet  136 . According to one embodiment, the water conduit  126  exits the water barrier  120  somewhere between a top edge and a bottom edge of the water barrier  120 . This creates the PDU water outlet  136 A shown in solid black lines within the water barrier  120 . According to an alternative embodiment, the water conduit  126  may extend over a top edge of the water barrier  120  to deposit the water over the barrier to the cargo floor  108 . This embodiment is shown in broken lines with PDU water outlet  136 B. According to a third alternative shown in  FIG. 5 , the water conduit  126  may exit the PDU housing  112  at PDU water outlet  136 C at a position external to the water barrier  120 . 
     Looking at  FIGS. 1 and 2 , the water conduit  126  is positioned to provide a single water outlet  130  for the sump portion  128  of the drive wheel compartment  114 . Water is only transferred from the sump portion  128  via the single water outlet  130 , which is fluidly coupled to the water conduit  126  of the water extraction mechanism  122 . In other words, the single water outlet  130  of the sump portion  128  defines a water inlet to the water conduit  126 . There is no drain from the drive wheel compartment  114  to a pipe or tubing that connects the PDU to an external system of drain pipes, as is done with conventional PDUs. Rather, the water removal components are self-contained within the PDU  100 . 
     According to the example shown in  FIGS. 1 and 2 , the water conduit  126  is positioned within the drive wheel compartment  114 , while the pump  124  is positioned on top of the PDU housing  112 . It should be understood that this configuration of the water extraction mechanism  122  may be altered as desired per known plumbing techniques. For example, as shown in  FIGS. 3 and 4 , the pump  124  may be located within the drive wheel compartment  114 , and as shown in  FIG. 5 , the pump  124  and water conduit  126  may be positioned outside of the drive wheel compartment  114 , while remaining within the PDU housing  112 . These alternate configurations will be described in greater detail below. 
     If the pump  124  is positioned on top of the PDU housing  112 , as shown in  FIGS. 1 and 2 , the dimensions of the pump  124  should provide for a pump height that is less than H 1  so as to not interfere with the pallets  102  passing over the PDU  100 . Having the pump  124  positioned on the top of the PDU housing  112  may be beneficial when the water barrier  120  and the water extraction mechanism  122  are configured for attachment to a conventional PDU for reconfiguring the conventional PDU from utilizing the drain and external plumbing described above to the self-contained water removal system of PDU  100  utilizing the concepts described herein. In attaching the water barrier  120  and the water extraction mechanism  122  to the PDU  100 , the water conduit  126  is secured using conventional methods to the inside of the drive wheel compartment  114 . The water barrier  120  may be positioned around a top portion  132  of the PDU housing  112 . The pump  124  is then secured to the top of the PDU housing  112  and electrically and communicatively coupled to an electrical and activation source. The electrical source may include the aircraft wiring, or may include the PDU electrical circuitry, which ultimately is powered by the aircraft. The activation source is the mechanism for activating the pump  124 . 
     There are various methods for activating the pump  124  to transfer water from the sump portion  128  to the cargo floor  108  outside of the water barrier  120 . According to one embodiment, the pump  124  may be operatively coupled to a water sensor  134 . The pump  124  activates upon detection of water within the sump portion  128  of the drive wheel compartment  114  by the water sensor  134 . Alternatively, the pump  124  may activate upon detection by the water sensor  134  of water at a threshold depth, such as a depth that is close to a position that allows contact with the PDU drive wheel  116 . These types of water sensors are known in the art. The present disclosure is not limited to any particular type of sensor; including float switches and electrical resistance measurement devices. It should be appreciated that the water sensor  134  is shown as a box positioned on the floor of the drive wheel compartment  114  for simplicity purposes. The water sensor  134  may be positioned at any suitable location without departing from the scope of this disclosure. 
     According to another method for activating the pump  124 , the pump  124  is operatively coupled to the motor  118  such that the pump  124  is activated upon activation of the motor  118 . In other words, whenever the PDU drive wheel  116  is rotating, the pump  124  is activated to remove any water from the sump portion  128  of the drive wheel compartment  114 . According to yet other embodiments, the pump  124  may operate independently of the motor  118 , and be activated in response to a user input or a predetermined schedule. A user may press a button that provides the electrical signal to one or more pumps  124  within PDUs  100  of the cargo floor  108 . Alternatively a controller within the PDU  100  may be programmed to activate the pump  124  at a particular time or time interval from a user input or other event. 
     Turning now to  FIGS. 3 and 4 , embodiments are shown that illustrate the water barrier  120  being positioned around an outer edge  302  of the drive wheel compartment  114 . In these embodiments, the water barrier  120  routes water around the top portion  132  of the PDU  100 , just as described above with respect to  FIGS. 1 and 2 , but only around the drive wheel compartment  114  rather than the entire PDU housing  112 . One advantage of this implementation is that less material is needed for the water barrier  120  since it does not extend around the entire perimeter of the PDU  100 , which equates to weight and cost savings. An additional aspect of  FIGS. 3 and 4  that should be noted includes the pump  124  being located within the sump portion  128  of the drive wheel compartment  114  rather than being positioned on top of the PDU  100 . One benefit to this configuration is that by positioning the pump  124  within the drive wheel compartment  114 , the pump  124  is protected from damage from external sources within the cargo bay of the aircraft. 
     While any of the embodiments shown in  FIGS. 1-4  may be configured as a single unit with all water extraction and pallet driving components integrated into PDU  100  for removable installation within the cargo floor, the embodiment of  FIG. 5  illustrates a good example of a single integrated unit. According to this example, the water extraction mechanism  122  is positioned within the PDU housing  112 , but outside of the drive wheel compartment  114 . The drive wheel compartment  114  includes a single water outlet  130  that leads to the water conduit  126  outside of the drive wheel compartment  114 . The water is pumped up to the PDU water outlet  136 C at a position external to the water barrier  120 . One benefit to this configuration is that by positioning the water extraction mechanism  122  within the PDU housing  112  but outside of the drive wheel compartment  114 , the components of the water extraction mechanism  122  are protected from damage from external sources such as cargo personnel, falling cargo or other objects, or contact with the PDU drive wheel  116 . 
     It should be appreciated that the configurations shown throughout the drawings is for illustrative purposes only and should not be construed as limiting. For example, positioning of the water extraction mechanism  122  may be inside or outside of the drive wheel compartment  114  with the water barrier being positioned around the outer edge  202  of the PDU housing  112  or around the outer edge  302  of the drive wheel compartment  114 . The positioning of the water barrier  120  is not dependent on the configuration of the water extraction mechanism  122 . Similarly, the activation mechanism used to activate the pump  124  is independent of any configuration of the water barrier  120  and water extraction mechanism  122 . 
     Turning now to  FIG. 6 , additional details will be provided regarding embodiments presented herein for moving pallets  102  over a cargo floor  108  while preventing water accumulation within the drive wheel compartment  114 . It should be appreciated that more or fewer operations may be performed than shown in the figures and described herein. These operations may also be performed in parallel, or in a different order than those described herein. 
       FIG. 6  shows a routine  600  for moving pallets  102  over a cargo floor  108  in a wet environment. The routine  600  begins at operation  602 , where the PDU drive wheel  116  is activated. When a pallet  102  contacts the PDU drive wheel  116  at operation  604 , the pallet  102  is driven across the PDU  100 . At operation  606 , a water barrier  120  routes water around the drive wheel compartment  114 . According to one embodiment, the water barrier  120  is positioned around the outer edge  202  of the PDU housing  112 , as shown in  FIGS. 1 and 2 . Alternatively, the top portion  132  of the PDU housing  112  may include the outer edge  302  of the drive wheel compartment  114 , as shown in  FIGS. 3-5 . 
     From operation  606 , the routine  600  continues to operation  608 , where water is detected in the drive wheel compartment  114 . As described above, water may be detected in various ways, including via a water sensor  134 . Water may be detected or may be detected at a current level, which may be compared to a threshold level. The detection of water, or water at a threshold level, may trigger the activation of a pump  124  of a water extraction mechanism  122  at operation  610 . Alternatively, the pump  124  may be activated via a user input or a predetermined schedule. At operation  612 , the water is transferred from the sump portion  128  or the drive wheel compartment  114  to the cargo floor  108  via the water conduit  126 , and the routine  600  ends. 
     The subject matter described above is provided by way of illustration only and should not be construed as limiting. Various modifications and changes may be made to the subject matter described herein without following the example embodiments and applications illustrated and described, and without departing from the true spirit and scope of the present disclosure, which is set forth in the following claims.