Abstract:
A module for a payload that utilizes individual grippers in which each fill to a conical shape from an interior wall of the module toward a payload in the module. The shape of the grippers provides a holding strength on and lateral stability for the payload. The angle of the conical shape transfers the axial force of the payload into a tensional load on the gripper where it has comparatively greater strength. The conical shape of each gripper allows for more complete capture of a payload in that the grippers fill voids around the payload. Since there are more contact points with the grippers and the payload, the contact force required for an adequate capture can be spread out.

Description:
STATEMENT OF GOVERNMENT INTEREST 
   The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore. 
   BACKGROUND OF THE INVENTION 
   (1) Field of the Invention 
   The present invention relates to a payload module capable of storing payloads of various shapes. The payload module utilizes a flexible material that can conform to the shape of the payload by being inflated for a gripping action on the payload. 
   (2) Description of the Prior Art 
   As a result of evolving missions and the limitations of space on naval vessels, a need exists to transport special equipment (such as motorcycles, all-terrain vehicles, jet skis, rafts, boats, etc.) using payload modules. 
   Presently, payload modules transport special equipment includes handling gear that is specifically designed for the equipment to be transported. Since the types of equipment or payload items may vary extensively, it is necessary to provide a flexible payload module that could be used for many items as opposed to being designed specifically for just one. 
   In the Ono reference (U.S. Pat. No. 4,155,453), an inflatable grip container is provided. As shown with the example camera in  FIG. 3  of the reference, the container (buoyant case  1 ) is a broad inflatable bag that would be limited to the extending sections of the camera (or alternate payload). Since the contour of the camera is not fully covered, compartments (item  6 ) exist in which the camera (or alternate payload) is not securable. 
   In the Kieselewski reference (U.S. Pat. No. 4,762,231), a pneumatic device for holding articles in containers is provided. The container (item  12 ) has a mat (item  14 ) disposed therein. A plurality of individual inflatable members (item  20 ) are positioned with the mat. The members are inflated until an article placed in the container is in contact with a pressure applying surface (item  22 ). Similar to the inflatable bag of the Ono reference, the pressure applying surface is limited to the extending sections of a payload placed in the container. Since the contour of the payload is not fully covered, compartments would exist in which the payload is not securable. 
   As a result, a need exists for an improved payload system or module that utilizes individual grippers in which the inflatable or fillable grippers provide a holding strength on and lateral stability for the payload. The flexible payload module should be able to hold and provide stability for payload items of varying sizes. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a payload module that utilizes individual grippers in which the grippers provide a holding strength on and lateral stability for the payload. 
   It is therefore a further object of the present invention to provide a flexible payload module that could be used for payload items of varying sizes. 
   In order to attain the objects described, there is provided a payload module that utilizes numerous inflatable fingers or grippers that are preferably conical in shape. The conical shape is unique as it allows for the contact area of the gripper to increase and decrease with the size of the payload. This change in contact area can be accomplished without having to change the pressure inside each gripper. 
   The conical shape of the grippers also provides an axial holding strength of the payload thereby providing a greater securing force to the payload. If a payload moves perpendicular to the longitudinal axis of the gripper, the conical shape provides for lateral stability. Specifically as an individual gripper is displaced to one side, the gripper deflects and places the material of the gripper in tension. The angle of the conical shape transfers the axial payload force into a tensional load on the gripper where it has the greatest strength. 
   The number of grippers along with the conical shape of each gripper allow for more complete capture of a payload in that the grippers can fill voids around the payload item. Since there are more contact points with the grippers and the payload, the contact force required for an adequate capture can be spread out. 
   Each of the grippers is capable of using seawater as the inflation fluid as well as consideration to a mixture of fluids or the use of different fluids in various chambers. The mixing of fluids allows for non-linear loadings such as in a non-exclusive use in which a gripper could utilize a very soft (less dense) fluid like air at its tip and a denser fluid like water at its base, or vice versa. 
   The grippers are made from elastomeric materials such as rubber, or non-elastomeric materials such as Kevlar. The elastomeric material provides for greater flexibility and the non-elastomeric material provides for greater strength. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete understanding of the invention and many of the attendant advantages thereto will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
       FIG. 1  depicts a cross-sectional view of a payload module of the present invention in which the flexible grippers of the payload module are deflated; 
       FIG. 2  depicts a plan view of the payload module of the present invention with the view taken from reference line  2 - 2  of  FIG. 1 ; 
       FIG. 3  depicts a side view of bellows-type gripper; 
       FIG. 4  depicts a cross-sectional view of a payload module of the present invention in which the flexible grippers of the payload module are filled or inflated; 
       FIG. 5  depicts a plan view of the payload module of the present invention with the view taken from reference line  5 - 5  of  FIG. 4  in which some of the flexible grippers are removed for clarity; 
       FIG. 6  depicts a cross-sectional view of a payload module of the present invention in which the flexible grippers of the payload module are filled or inflated in contact with a payload; 
       FIG. 7  depicts a cross-sectional view of a payload module of the present invention in which the flexible grippers are controllably supplied to individual grippers; 
       FIG. 8  depicts a cross-sectional view of a bi-furcated gripper; and 
       FIG. 9  depicts a cross-sectional view of a payload module of the present invention in which the flexible grippers are controllably supplied to individual grippers with the individual grippers passing through an inner skirt. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIG. 1  there is shown a cross-sectional view of a payload module  10  as the present invention. In the figure, the payload module  10  generally comprises a plurality of conical grippers  12  (shown non-filled or deflated), a winch assembly  14  and a pair of submersible pumps  16 ,  18 . 
   As depicted in the figure and the plan view of  FIG. 2 , the payload module  10  includes an interior cylindrical wall  20  with several rows of the grippers  12 . Each gripper  12  is made of a watertight material that can be inflated or filled and deflated with pressurized water. 
   The conical shape of the grippers  12  allows the grippers to collapse within themselves as they are deflated. Because the conical shape gets progressively smaller in diameter from its base to its inner center, the gripper  12  will flatten when deflated. When made of rubber, the grippers  12  are flexible enough to be collapsed from a smooth shape into the flattened shape such that they occupy very little volume when deflated. For tougher materials, such as Kevlar, to collapse into flattened shape, the grippers can have a bellows shape as shown in  FIG. 3 . The flattened profile of each gripper  12  takes up a minimal amount of space, thereby providing a maximum amount of space for a given payload. 
   As shown in  FIGS. 4 and 5 , the grippers  12  are conical in shape so that they can expand towards a longitudinal axis  22  of the payload module  10  and a positioned payload  40  (shown in  FIG. 6 ) without interfering with one another. 
   As shown in the figures, the payload module  10  is contained inside a watertight and high pressure-resistant container  50 . The container  50  protects the payload module  10  and its contents from extreme depth pressures and pressure fluctuations if the container is used with a submarine or as part of other submersibles (not shown). As such, the interior of the payload module  10  remains at a steady pressure. Because the container  50  is watertight, the payload module  10  may be filled with air to keep it contents dry. 
   Each of the pumps  16  and  18  is used to transfer seawater from the interior  52  of the payload module  10  or the ambient ocean environment into the inflatable grippers  12 . For space considerations, the pumps  16  and  18  are located at the closed end of the container  50 . In operation, the pumps  16  and  18  draws seawater from inside or outside the payload module  10  and transfer it behind the grippers  12  by the use of an annular water flow passage  24  formed between the container  50  and the wall  20  of the payload module or the grippers  12  are filled through a network of piping. From the annular passage  24 , the seawater or alternate fluid fills the individual grippers  12 . 
   As shown in  FIG. 7 , individual tubing  26  with associated control valves  28  can be used to control the inflation of specific grippers  12 . Inflation of specific grippers  12  allows access to certain areas in the interior  52  or can protect certain parts of the payload  40  from damage by the grippers  12  or can protect the grippers themselves. The pumps  16 ,  18  can be used to deflate the grippers  12 , if a reversible pump is used; otherwise, the two submersible pumps (or one if cross-connected) are used to inflate and deflate the grippers. 
   The grippers  12  can be inflated within a wet or dry interior of the payload module  10 . If the interior  52  is wet, the grippers  12  can be filled by the pumps  16 ,  18  from a supply of seawater from the interior. If the interior of the payload module  10  is dry, the grippers  12  can be filled by the pumps  16 ,  18  from water within the annular passage  24  and/or outside of the container  50  by use of external connection  29  with control valve  30  (shown in  FIG. 7  but also adaptable for the payload module of  FIG. 1 ). 
   Once the grippers  12  are inflated, the pumps  16  and  18  can then be used to empty remaining seawater from the container  50  by use of the external connection  29 . In this way, the grippers  12  remain filled with seawater while the contents of the container  50  can remain dry. To achieve this, a muzzle hatch  54  (shown partially due to space restrictions) on the container  50  must be closed or the submarine must be surfaced before the process to pump the interior of the payload module  10  can begin. If surfaced, the muzzle hatch  54  would remain open so air could flow in as seawater was being pumped out. If submerged, the muzzle hatch  54  must be closed and air must be pumped in as the seawater is being pumped out. 
   The discharge pressure of the pumps  16  and  18  controls the grip force of the grippers  12 . As the pressure is increased; the grip force increases. The pressure supplied to the grippers  12  should correspond to the weight and strength of the payload  40  being contained in order to prevent accidental damage to the payload. 
   The grippers  12  are made from a flexible material, such as a fabric, that is waterproof, puncture-resistant, tear-resistant and sufficiently strong to withstand the inflation pressure and a small portion of the weight of the payload  40 . The flexible material is preferably Kevlar for more tear resistance or elastomeric rubber for more flexibility. For each gripper  12 , the grippers are preferably fastened to the inner wall  20  (by means known to those skilled in the art) over individual apertures in the inner wall. 
   The winch  14  is used to assist with loading and unloading of the payload  40  of the payload module  10 . The cable of the winch  14  shall be long enough to reach well outside the payload module. Since most payload items are buoyant in nature, the winch  14  is needed to pull the payload  40  down into the payload module  10 . The winch  14  may also be used to control the rate of ascent as a particular payload item is allowed to float out. 
   The main advantage of the payload module  10  is that it provides a flexible means of carrying almost anything inside a submarine or submersible vehicle. The fluid nature of seawater in combination with the flexible material of each gripper  12 , allows the grippers to match the shape of the payload  40  where the grippers make contact. Because all the grippers  12  are interconnected by the fluid action of the seawater, the grippers conform to the shape of the payload  40  as a group. Therefore, individually then cumulatively as a group, the grippers  12  flow around and conform to the shape of the payload  40 . 
   Regardless of the shape or size of the payload  40 , the pumps  16  and  18  can continue pumping until all the grippers  12  are either engaged with the payload or completely inflated. If no payload is present, the pumps  16  and  18  would operate for the longest period because it must fully inflate all of the grippers  12  (unless flow is controlled to individual grippers as depicted in  FIG. 7 ). Once the desired pressure is reached, the grippers  12  will be either fully engaged or fully inflated. The pumps  16  and  18  can then be controlled to shut off automatically. 
   The payload module  10  is depth independent. The hydrostatic depth pressure is balanced across the suction and discharge sides of the submersible pumps  16 ,  18 . Since seawater is incompressible, the hydrostatic depth pressure is constantly sensed across the fabric of the gripper  12 . From there it is transferred to the discharge side of the submersible pumps  16 ,  18 . Therefore, the payload module  10  can operate equally well at any depth. 
   By controlling the shut-off pressure on the submersible pumps  16  and  18 , the grip strength of the grippers  12  can also be controlled. As the shut-off pressure is increased, so is the grip force. If the payload  40  is heavy and strong, a heavy grip force can be applied. If however, the payload  40  is light and fragile, a light grip force can be applied. This is simply controlled by controlling the pressure supplied by the pumps  16  and  18 . 
   Because the grippers  12  are made from a flexible material, a uniform pressure force is applied to the payload  40 . Doing so greatly increases the holding strength of the grippers  12  and greatly reduces the chance of damaging the payload  40 . If the same grip force was concentrated at a point or a small area, the payload  40  could be damaged. The uniform pressure distribution of the system therefore minimizes any risk of damaging the payload  40 . 
   The flexible payload module  10  can be used to store the payload  40  dry or wet. In both cases, the grippers  12  are filled with seawater, but the interior  52  itself can be wet or dry. If a dry bay is desired, after the payload  40  is loaded wet, the seawater is pumped out once the grippers  12  are inflated. 
   If the payload  40  must be loaded dry, the submarine is surfaced and the payload module  10  is emptied of seawater. Seawater is then supplied from external sources to the external connection  29  to inflate the grippers  12 . In this way, the payload  40  only comes in contact with the dry side of the grippers  12 . 
   The flexible payload module  10  provides for shock protection since none of the grippers  12  are rigid; therefore, shock loads are easily absorbed. Each inflatable gripper  12  only opposes another gripper when they are inflated. If the payload  40  shifts and moves from its balanced center position during a shock event, seawater is simply transferred from one gripper  12  to another gripper. Once the shock event ends, the grippers  12  redistribute the seawater within them until the entire system is returned to a balanced condition with the payload  40  centered again in the interior  52 . 
   The gripper  12  are preferably conical when filled; however, they can be any shape. The grippers  12  must merely be watertight such that they can be inflated and deflated with water or other fluids. The grippers  12  can also be used with air instead of water, only requiring compressors to replace the pumps  16  and  18 . 
   In an alternate configuration, shown in  FIG. 8 , the gripper  12  can also be inflated using a mixture of seawater and air or a mixture of any other fluid. For this configuration, the gripper  12  is compartmented to provide for non-linear stiffness. In the non-exclusive configuration of the gripper  12  of the figure, an air compartment  80  is adjacent to a seawater compartment  82  in the gripper. The air compartment  80  is preferably pre-filled prior to the addition of the payload  40  to the module  10  by a connection  84 . 
   During use of the bi-furcated configuration of air and fluid, the tip of the gripper  12  can be soft and the base can be comparatively stiffer. The soft portion would be a benefit when in contact with a delicate payload and the stiffer portion would be a benefit for a large and robust payload. 
   The pumps  16  and  18  do not have to be submersible. The pumps can be located separately inside the submarine pressure hull. The pumps  16  and  18  must merely be able to pump seawater into and out of the individual grippers  12 , and into and out of the interior  52  of the payload module  10 . 
   In yet another configuration shown in  FIG. 9 , an inner cylindrical skirt  90  can be positioned on the inner cylindrical wall  20  to provide a smooth surface for loading and unloading. Without the inner skirt  90 , the payload  40  may get hung up on the protruding grippers  12 . Apertures  92  are placed in the inner skirt  90  that are equal in diameter and in-line with the grippers  12 . When deflated, the grippers  12  are contained within the inner skirt  90 . When inflated, the grippers  12  expand and pass through the inner skirt  90 . The inner skirt  90  provides a cavity or well that is large enough to contain a deflated gripper. This configuration creates a smooth surface for the payload  40  to slide past when the payload is being loaded and unloaded. 
   Obviously many modifications and variations of the present invention may become apparent in light of the above teachings. In light of the above, it is therefore understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.