Abstract:
A forward closure system includes a cylindrical frame. A pair of lune-shaped base sections are mounted to an inside surface of the frame. First and second opposed lune-shaped shell assemblies, each assembly including at least an outer shell section and an inner shell section, are rotatably mounted independently of each other at opposed ends along the rotation axis, the inner section and base sections of each shell assembly nested within the outer section when the forward closure system is in an open position, mating edges of the outer sections abutting one another when the forward closure system is in a closed position. An actuator is coupled to each outer shell section.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/465,702 filed on Mar. 23, 2011, the entirety of which is incorporated by reference herein. 
    
    
     GOVERNMENT LICENSE RIGHTS 
     This invention was made with government support under contract number N00030-08-C-0056/Q108CC/SRT awarded by the Department of the Navy. The government has certain rights in the invention. 
     This invention was made with government support under contract No. N00030-08-C-0056/Q108CCISRT awarded by the United States Navy. The government has certain rights in the invention. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates to systems which can enclose an object that is sensitive to environmental conditions until it is ready to be launched (or leave) from the enclosure. 
     2. The Prior Art 
     Forward closure systems are used as devices to seal enclosures that contain an object, launchable from submerged, underground or surface launchers. Their primary goal is to act as an environmental seal while the launchable object is not in use, and to allow object egress during launch procedures. 
     In the prior art forward closure systems, the device is designed to be removed prior to launch of the object and is not reusable. In U.S. Pat. No. 3,135,163 to Mechlon et al., an explosive cord ruptures a diaphragm prior to an object launch. The detonation has to happen in a pre-determined pattern such that the debris from the diaphragm will not damage the object as well as the surrounding equipment. 
     In U.S. Pat. No. 3,742,814 to Kroh, the closure diaphragm is made up of a thin frangible plastic, which can be ruptured by the launched object. However, the drawback with this system is that, the launched object can be damaged while interacting with the plastic diaphragm. In addition, the thin diaphragm might not be strong enough for enclosures submerged at significant depths in water, and cannot withstand the hydrostatic pressure conditions. 
     U.S. Pat. No. 3,962,951 to Schenk, discloses the use of a hold down locking device to keep the shatterable type closure system in place. The closure may be made of asbestos-reinforced phenolic plastic. However, similarly, this closure system is ruptured by contact with the launched object, which can damage the launched object; moreover, debris generation still remains an issue. 
     A closure comprising of frangible glass ribs that form a dome shaped closure is disclosed in U.S. Pat. No. 4,301,708 to Mussey et al. A linear-shaped explosive charge arranged in a pre-determined pattern fragments the glass section prior to launch. The issue of excessive debris generation remains a problem with this design. 
     Another frangible fly-through diaphragm design is disclosed in U.S. Pat. No. 4,498,368 to Doane. This diaphragm is formed from epoxy and fiberglass plies, which are torn in a pre-determined path, during the fly-through launch of an object. 
     BRIEF DESCRIPTION 
     A Forward Closure System (FCS) according to the present invention includes means to protect the enclosed object from the environment and a method of fast opening to launch the object into the environment. The FCS structure can withstand high-pressure variations in both directions, from above and below, and is particularly suitable for underwater applications. The FCS can also withstand a wide range of temperatures, depending on the materials used for its fabrication. The opening surface of the FCS is sectioned into multiple separate shell components. Each shell is designed to slide under an adjacent shell that is larger in diameter, resulting in a structurally strong FCS that takes minimal space around the object being enclosed. The FCS can be sealed using many different techniques. 
     The FCS of the present invention can overcome all of the aforementioned drawbacks, such as, one-time use, debris generation, direct contact with the launched object, and inability to hold deep-sea pressures. The present invention can protect the enclosed object from environmental conditions prior to being launched, as well as actuate quickly enough, so that the launched object flies without any interference from the closure. The present invention provides a structure that is completely reusable. The only required replacement is the seals, which are torn during object launch. The torn seals produce minimal to no debris, which imposes no hazard to the launched object and surroundings. The fail-safe operation mode of the invention ensures that in the event of actuation malfunction, the launched object interacts with the system and opens it, with minimal force. Similarly, the main structure of the system is completely reusable and generates minimal debris even at its fail-safe operation mode. This invention can be equipped with sensors that communicate with a control system, so that different aspects, such as, opening/closing time can be controlled and changed via a user interface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  is a drawing that shows an isometric view of the FCS in the closed position without the seals. 
         FIG. 2  is a drawing that shows a sectioned isometric view of the FCS in the closed position without the seals. 
         FIG. 3  is a drawing that shows an isometric view of the FCS in the opened position. 
         FIG. 4  is a drawing that shows an isometric view of the FCS in the closed position with the seals. 
         FIG. 5  is a drawing that shows a sectioned isometric view of the FCS in the closed position with the seals. 
         FIG. 6  is a drawing that shows the FCS with sections only on one side in the closed position to demonstrate the opening mechanism. 
         FIG. 7  is a drawing that shows the FCS with sections only on one side in open position to demonstrate how the system opens. 
         FIG. 8  is a drawing that shows a sectioned view of the FCS revealing the fail-safe operation mechanism. 
         FIG. 9  is a block diagram illustrating how an exemplary user interface, control system and FCS can interact. 
         FIG. 10  is a drawing that shows an alternative embodiment of the FCS invention in the closed position. 
         FIG. 11  is a drawing that shows the alternative embodiment of the FCS invention in the open position. 
         FIG. 12  is a drawing that shows a sectioned view of the alternative embodiment of the FCS invention in the open position. 
         FIG. 13  is a drawing that shows a close up side sectioned view of an air port on the alternative embodiment of the FCS invention in the closed position. 
         FIG. 14  is a drawing that shows a side sectioned view of the FCS in the closed position with added tabs for mechanical actuation. 
         FIG. 15  is a drawing that shows a side sectioned view of the FCS in the closed position with an added inner slide attachment for actuation by the enclosed object. 
         FIG. 16  is a drawing that shows an isometric view of the FCS in the closed position being activated by a rotational device such as an electric motor, a rotary pneumatic or hydraulic actuator. 
         FIG. 17  is a flow diagram showing an illustrative operating sequence for FCS of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Persons of ordinary skill in the art will realize that the following description of the present invention is illustrative only and not in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons. 
     The Forward Closure System (FCS) device disclosed herein can be rigidly connected to a frame/chassis/vehicle that can be underwater or on the ground, where an object is to be enclosed by the FCS and protected from the environment. The device can be connected to an electric power supply, a pneumatic or hydraulic supply for actuation. The device can be equipped with position/angular sensors that can be connected to a control system. Based on the feedback from the position/angular sensors, the required electric current/actuation load can be supplied to the device. Upon application of the electric current/actuation load the FCS opens to allow for the enclosed object to pass through. 
     An illustrative embodiment of a Forward Closure System (FCS)  20  shown in  FIG. 1  is composed of multiple shell sections. The example in  FIG. 1  consists of 4 shell sections. Persons of ordinary skill in the art will appreciate that the number of shell sections employed can differ based on the overall size and operation requirements of the FCS. The outer sections  21  are the ones having the largest radii of all the sections. The inner sections  22  have a slightly smaller radius than the outer sections  21  to allow outer sections  21  to slide in a radial direction over inner sections  22 . A cross-sectional isometric view of the FCS  20  is shown in  FIG. 2 . 
     For the specific illustrated FCS design  20  as shown in  FIG. 1  and  FIG. 2 , all rotating shell sections  21 ,  22  are connected to the stationary base section  23  which is a section having a smaller radius than sections  22 . The rotating sections  21 ,  22  can be actuated with an actuator  24  or multiple actuators  24 . The actuator(s)  24  can be AC or DC powered motors, electromagnetic actuators, hydraulic or pneumatic rotary actuators. Alternatively, a gearbox or another torque and speed-varying device  25  can be attached to each actuator to vary the torque applied on the rotating sections  21 ,  22 . The selection of actuator power and gearbox design depends on the opening time, size and shape of the FCS. 
     Once actuated, the FCS design  20  opens as demonstrated in  FIG. 3 . As shown in  FIG. 3 , all rotating sections  21 ,  22  are connected to the base section  23  via the pins  26  that are seated in bearing(s)  27 . The actuator(s)  24  can be connected via actuator attachment plate(s)  28  to the seal attachment structure  29 . The FCS design  20  can be rigidly attached to a frame  30  via the stationary base section  23  and the seal attachment structure  29 . As shown in  FIG. 2 , the rotating sections  21 ,  22  and the stationary base section  23  are covered with a structural skin, and alternatively can include reinforcing rib/truss type elements  31  that can be designed according to the load carrying requirements on the FCS  20 . 
     The FCS design  20  also includes an upper seal compression ring  32  and a lower seal compression ring  33 . Once installed on a frame  30 , the FCS design  20  requires an upper seal  34  and a lower seal  35 , as shown in  FIG. 4  as an assembly, and in  FIG. 5 , as a sectioned view to reveal the location of the lower seal  35 . The seals  34 ,  35  are required if the object to be launched is to be protected from environmental conditions such as high pressure water (for underwater conditions), hazardous contaminants, and foreign objects, etc. The upper seal  34  and lower seal  35  can be made of elastomeric material or any other combination of materials that can be molded into the desired shape. The upper seal  34  and lower seal  35  can be directly attached to the outer sections  21 . The means for connection can be mechanical fasteners. During opening the outer sections  21  tear apart the upper seal  34  and lower seal  35  to allow the launchable object to pass through the closure. 
       FIG. 6  is a view of the rotational joint sections  36  at the pin  26  location of the sections  21 ,  22  when the FCS design  20  is in its closed position. Only one side of the FCS design  20  is shown for better understanding of the mechanism. Each joint  36  contains a sealed bearing  37  for optimal rotation. The rotational joint sections  36  connected at the end of the rotating outer sections  21  contain a dowel pin  38  that can interact with the inner rotational sections  22 . The inner rotational section  22  has a slot  39  that allows for relative movement during the opening of the FCS. Upon actuation of the outer rotational section  21 , the dowel pin  38  moves along the slot  39  and engages with the inner rotational section  22  after a predetermined rotational angle, and opens the inner rotational section  22 .  FIG. 7  presents the FCS design  20  in the open position. 
     The FCS design  20  also includes fail-safe features for emergency operation conditions, in case the actuators  24  fail to open the system. Each outer section  21  includes at least one fail-safe operation tab  40 , as demonstrated in  FIG. 8 , that can be designed based on the launched object  41  nose profile. If the actuators  24  fail to operate, the launched object  41  hits the fail-safe operation tab(s)  40 . The upwards axial movement of the launched object  41  is directed sideways via the fail-safe operation tab(s)  40 . This generates a torque on the pin  26  locations which can tear the upper seal  34 , the lower seal  35  and pry open the FCS sections  21 ,  22 , simultaneously, without damaging the launched object  41 . 
     After normal or fail-safe operation of the FCS design  20 , no structural part except the upper seal  34  and the lower seal  35  is damaged. The embodiment shown in  FIG. 4  produces minimal amount of debris. After opening, only the seals  34 ,  35  need to be replaced, therefore, the FCS design  20  structure is reusable. 
     The operation of the FCS design  20  can be controlled via a control system  50  that includes a user interface  51  and other control system hardware  52 , as illustrated in the block diagram of  FIG. 9 . The user interface  51  can be a computer, where the user can enter operating parameters. The control system hardware  52  also includes a data acquisition chassis  53  that is powered externally  57 , a data acquisition card  54 , a data acquisition controller  55  and an actuator controller  56 . The data acquisition chassis  53  can supply the power  57  to the user interface  51 , actuator controller  56  and the position sensor(s)  58 . The position sensor(s)  58  can be any type of angle or displacement transducer that feedback the position of the outer rotational sections  21  to the control system  50 . Based on the user interface  51  input of the required opening time and feedback from the position sensor(s)  58 , the actuator controller  56 , can adjust the driving force (whether it is an electric current, hydraulic pressure supply valve or pneumatic supply valve), so that the FCS design  20  opens in the required time. The FCS design  20  also employs at least two mechanical emergency stop switches  59  that can send a signal to the control system  50  that the FCS design  20  is open, in the event the position sensor(s)  58  malfunction. Persons of ordinary skill in the art will appreciate that the partitioning of the control system hardware  52  shown in  FIG. 9  into various sub-components is illustrative only and that other partitioning of the functions performed by control system hardware  52  is within the scope of the present invention. 
     In an alternative embodiment of the FCS invention shown in  FIG. 10 , the FCS design  70  is composed of multiple shell sections each including a port  76 . The embodiment in  FIG. 10  consists of 8 shell sections. The main upper section  71  is the one with the largest radius out of all the sections. Section  72  has a slightly smaller radius than section  71  to allow section  71  to slide in a radial direction over section  72 . Likewise, section  73  has a smaller radius than section  72  in order to allow section  71  and  72  to slide over section  73 . Section  74  is a section with a smaller radius than section  73  allowing all other sections  71 ,  72 ,  73  to slide over section  74 . All sections  71 ,  72 ,  73 ,  74  are connected with a pin  75 . Sections  71 ,  72 , and  73  contain ports  76  to allow a fluid to flow in between the shell sections to actuate the sections when the FCS  70  is to be opened. 
       FIG. 11  shows how sections  71 ,  72 , and  73  lie on the base section  74  after the FCS  70  is activated and is fully opened.  FIG. 12  is a sectioned view of  FIG. 11 , which shows the final volume of the gaps  77  once the FCS  70  is fully open. 
       FIG. 13  shows the initial volume of the gaps  77  between sections  73  and  74  before the FCS  70  is opened.  FIG. 13  also shows how the activating fluid/gas pressure flows into the gap  77  through the port  76 . When the FCS  70  is in the closed position, all of the sections interact with each other via flanges at the end of sections  71 ,  72 ,  73 , and  74 . These flanges all contain a sealing surface  78  that can be made up of a linear seal stock of rubber or plastic material, which allows the system to be tightly closed. 
       FIG. 14  shows how another embodiment of the invention. FCS  80  can be opened by pulling on the tabs  81  in the direction  82 . The tabs  81  can be pulled by a number of different devices including hydraulic actuators, electric actuators, mechanical hand crank, and electric motor. Similar to the other embodiments  20 ,  70  this will cause the sections to rotate about the pin  26 , thus causing the system to open. 
       FIG. 15  shows another embodiment of the invention. FCS  90  can be opened by pushing the sliding attachments  91  inside the shell sections in the direction  92  by the object enclosed by the FCS  90 . Similar to the other embodiments  20 ,  70 ,  80  this will cause the sections to rotate about the pin  26 , thus causing the system to open. 
       FIG. 16  shows another embodiment of the present invention. FCS  100  can be opened by rotating the upper sections  101  with a rotary device connected to a shaft  102  such as an electric motor, rotary hydraulic motor, rotary pneumatic motor, or engine. Compared to the FCS design  20  shown in  FIG. 1 , the alternative FCS design  100  might not require the use of a gearbox  25 . The two rotary devices connected to the shaft  102  need to rotate the upper sections  101  in opposite directions  103  causing the sections  101  to move away from each other. When the upper sections  101  begin to rotate, they will pull the other sections  104  and  105  down as well, thus causing the FCS  100  to open. 
     Referring now to  FIG. 17 , a flow chart shows an illustrative operating sequence  110  for FCS design  20 . The sequence begins with two inputs, the speed input  112  and the direction input  114 . The speed input  112  is the desired opening or closing speed of the forward closure system, assuming the speed of the actuator used is adjustable. The direction input  114  determines whether the forward closure system will open or close. 
     Once the sequence is started, the open close block  116  determines which mechanical switches and angles to use in order to move the system. The system first checks the shell angle to determine if it is greater than or equal to θ max  in block  118  or if it is less than or equal to zero in block  120 , if so, then the system is already open or closed as shown at reference numerals  122  and  124  and the motor speed is set to zero at reference numeral  126 . If the angle is either less than θ max  or more than zero, then the system checks the mechanical switches in blocks  128  and  130  to see if they are activated. If either switch is activated then the system is already open or closed and as indicated at reference numerals  122  and  124  and the motor speed is set to zero at reference numeral  126 . If neither switch is activated then the system sets motor/actuator speed at reference numerals  132  or  134  to the desired input speed set at speed input  112 . From reference numerals  132  and  134 , the process loops back to reference numeral  114  until the system reaches its desired position. Once the opening or closing is complete as designated by reference numerals  122  or  124 , the motor/actuator speed to zero at reference numeral  126 . 
     While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications than mentioned above are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.