Abstract:
A hinge apparatus for automated decoupling that includes an actuatable assembly normally coupled, very robust, and suitable for the hanging of a door/canopy and the like. When mounted, the apparatus is normally decoupled where rapid egress is necessary, and complete removal of the door/canopy is desired. The apparatus includes a hinge finger with a finger pin and a reciprocal hinge finger with a hinge gudgeon. The finger pin normally intersects and freely pivots with respect to the gudgeon, such as when the door/canopy is opened or closed. The actuatable assembly employs a SMDC tip device to actuate a piston that decouples the hinge. Decoupling is effected as the piston linearly shifts moving the hinge finger such that the finger pin no longer intersects the gudgeon and the door/canopy falls away.

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. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to frangible hinges, and more particularly to an actuatable assembly and method for decoupling robust aircraft hinges. 
     BACKGROUND OF THE INVENTION 
     The performance and survivability of personnel in an aircraft, such as a helicopter, is a major design consideration. While protection of the pilots and other crew members is of primary importance, consideration must also be given to other personnel (e.g., assault troops and litter patients) and mechanical components (e.g., fuel cells) whose survival contributes to successful mission performance. Personnel are susceptible to all direct and secondary injury mechanisms (e.g., span fragments and other debris) emanating from threat weapon effects, as well as from other causes including explosive removal of doors/canopies and ejection seat rockets. The separation of doors/canopies and ejection seats is particularly dangerous as separation utilizes explosives in very close proximity to the crew and other personnel on the aircraft. The separation explosive can produce explosive decompression, sound pressure and impulse, toxic fumes, and smoke, all of which can have an adverse impact on the survivability of the crew and others. 
     Survivability and effectiveness is of special concern in the case of helicopters such as the AH-1W and AH-1Z USMC helicopters, where a combination of factors aggravates the situation. The crew is located very close to the airframe and the helicopters have been outfitted to have improved ballistic resistance. To effect separation of the doors/canopies and fixed windows requires greater explosive force, and coincident greater trauma to those onboard when these emergency egress systems are actuated. 
     SUMMARY OF THE INVENTION 
     In a variation of the invention, the invention is a hinge apparatus that has automated decoupling. The hinge apparatus is normally coupled, very robust, and suitable for the hanging of a door/canopy and the like. A mounted hinge apparatus is normally only decoupled in the case where rapid egress is necessary, and complete removal of the door/canopy is desired, such as when there is an emergency. The hinge apparatus includes a first hinge member having a first connecting apparatus and an actuatable assembly, and a second hinge member having a second connecting apparatus, where the second connecting apparatus is coupled to the first connecting apparatus. An example of the first connecting apparatus includes a hinge finger and a finger pin. An example of the second connecting apparatus includes a reciprocal hinge finger and a hinge gudgeon, where the pin normally intersects and freely pivots with respect to the gudgeon, such as when the door/canopy is opened or closed. The actuatable assembly is substantially only actuated when rapid egress is necessary. In those circumstances a shielded mild detonating cord (SMDC) tip device or a similar device is ignited producing high pressure gases in a combustion chamber of the actuatable assembly. The high pressure gases actuate a piston that decouples the hinge. Decoupling is effected when the piston shifts linearly. The linear shift causes the first connecting apparatus, which is connected to the piston, to move to a position where the first connecting apparatus is no longer coupled to the second connecting apparatus. The door/canopy at this time falls away, or is furthermore thrust away. 
     There are several aspects of the invention that make it particularly well suited for USMC helicopters such as the AH-1W and AH-1Z. A first aspect is that the high pressure gases are largely confined in the combustion chamber, thereby reducing toxic fumes and smoke. 
     A second aspect is that translational movement of the piston is dampened by a compression chamber locate in the actuatable assembly. The dampening reduces the sound pressure and impulse. 
     A third aspect is that the piston itself does not come into contact with of an elongate slotted barrel-like housing, which houses the piston. The piston is fitted with o-rings, which act as spacers, so that only the edges of the o-rings come into contact with the surface of the barrel-like housing. The edge has a narrow area of contact, and this configuration reduces the frictional resistance, and the spacing provides for greater tolerances, which makes binding improbable. Cumulatively, the o-rings narrow the range of uncertainty as to exactly how much force will be required to actuate the piston, and therefore the amount of charge can be appropriately lowered. The o-rings also act as a gas seal, retaining the high pressure gases, which improves the efficiency and excludes sand, dust, rain, ice, etc. The piston itself acts as a redundant mechanism even if one or more o-rings fail because the piston may still be actuated as it may still move through the barrel-like housing when the shear pin is sheared. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing invention will become readily apparent by referring to the following detailed description and the appended drawings in which: 
         FIG. 1A  is a perspective overview view of an exemplary embodiment of the invention from a right side of a helicopter. 
         FIG. 1B  is a perspective overview view of an exemplary embodiment of the invention from a left side of a helicopter. 
         FIG. 1C  is a perspective top-down/overview view of an exemplary embodiment of the invention of a helicopter. 
         FIG. 2  is a cross-sectional side view of an exemplary embodiment of the invented hinge apparatus having an actuatable assembly, wherein the first hinge member, which includes a hinge finger and a hinge pin, is coupled to the second hinge member, which includes a reciprocal hinge finger and hinge gudgeon; 
         FIG. 3  is a cross-sectional side view of the embodiment illustrated in  FIG. 2 , wherein the actuatable assembly has decoupled the first hinge member from the second hinge member; 
         FIG. 4  is a cross-sectional side view of another exemplary embodiment of the invented hinge apparatus having an actuatable assembly, wherein the first hinge member includes a reciprocal hinge finger and a hinge gudgeon, and is coupled to the second hinge member that includes a hinge finger and a hinge pin; 
         FIG. 5  is a cross-sectional side view of the embodiment illustrated in  FIG. 4 , wherein the actuatable assembly has linearly shifted the reciprocal hinge finger and the hinge gudgeon, therein decoupling the second hinge member from the first hinge member; 
         FIG. 6  is a diagrammatic side view of another exemplary embodiment of the hinge apparatus where the piston has a plurality of hinge fingers and hinge pins which are coupled to a plurality of reciprocal hinge fingers and hinge gudgeons; 
         FIG. 7  is an end-on view of the variation illustrated in  FIG. 6 ; 
         FIG. 8  is a perspective view of an exemplary embodiment of the actuatable assembly with the piston removed, therein permitting a better perspective of the elongate slotted barrel-like housing and the capping housing component; 
         FIG. 9  is a cross-sectional view of the capping housing component illustrated in  FIG. 8 ; and 
         FIG. 10  is a cross-sectional view of the invented hinge apparatus, where the view has an enlarged view that illustrates the use of the o-rings on the piston, where the o-rings serve in-part as spacers, so that only the edges of the o-rings come into contact with the barrel wall of the barrel-like housing, therein reducing the friction resistance, providing for greater tolerances, making binding improbable, and reducing the amount of explosive material required to actuate the piston. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Several exemplary embodiments of the invention are shown and described in the attached drawings, where the invention includes a hinge apparatus  10  having automated decoupling. Referring to  FIG. 1A  and  FIG. 1C , the hinge apparatuses  10 ,  10  may be located on a right side  2  of a helicopter substantially adjacent a rear, right-side window  6 , which is behind a front right-side window  4 . Similarly, and referring to  FIG. 1B , the hinge apparatuses  10 ,  10  may be located on a left side  8  of a helicopter substantially adjacent a front, left-side window  9 . Referring to  FIG. 1C , hinge apparatuses  10 ,  10  may be located substantially adjacent the rear, right-side window  6  as well as located substantially adjacent the front, left-side window  9 . Accordingly, the hinge apparatuses  10 ,  10  on the right side of the helicopter  2  are off-set from the hinge apparatuses  10 ,  10  on the left side of the helicopter  8  to permit efficient and safe exit from the helicopter  2 . 
     Referring to  FIG. 2  the hinge apparatus includes a first hinge member  20  having a first connecting apparatus  22  and an actuatable assembly  40 , and a second hinge member  30  with a second connecting apparatus  32 . The second hinge member  30  is shown with dashed lines because, as will become apparent, the choice of the first and second hinge members is adjustable, and can be selected from a variety of hinge members. The second connecting apparatus  32  is coupled to the first connecting apparatus  22 . In  FIG. 2  the first connecting apparatus  22  includes a hinge finger  24  and a hinge pin  26 . The hinge finger is depending from a piston  42 , which is the actuatable element in the actuatable assembly  40 . The second connecting apparatus  32  includes a reciprocal hinge finger  34  and a hinge gudgeon  36 . A retainer  60   a  serves as a backstop in the illustrated embodiment. 
     The illustrated piston  42  is rod-like, and it has a first end  42   a  with a proximate first groove (see  42   g  in  FIG. 6 ) and a first o-ring  42   b  with a first edge (not shown) that serves as a spacer. The piston  42  has a medial section  42   c , a second groove (see  42   h  in  FIG. 6 ), and a second o-ring  42   d  with a second edge (not shown) that serves as another spacer, an opposing end  42   e , and a first aperture  42   f  that is aligned with a second aperture  50   f  in the elongate slotted barrel-like housing  50 . A shear pin  12  is seated in the first and second aperture  42   f ,  50   f ; and the pin prevents translational movement by the piston  42 . A set screw  14  is used to seat the shear pin  12 . The elongate slotted barrel-like housing  50  has a stop  50   a , which defines a maximum translational distance that the piston of a specified length can move. This distance is selected such that at the stop or proximate to the stop  50   a , the first connecting apparatus  22  is no longer connected to the second connecting apparatus  32 . The elongate slotted barrel-like housing  50  has a slot for linear movement of the first connecting apparatus and a barrel-like space for the linear movement of the piston. The slot has a substantially vertical side wall  50   g , which prevents rotational movement of the first connecting apparatus  22 , as shown in  FIG. 2 ,  FIG. 3 , and  FIG. 10 . The first connecting apparatus  22  has a hinge finger  24  depending perpendicular from the piston  42 . The slot side wall  50   g  is sloped at the distal end of the slot forming a ramp  50   a . The ramp  50   a  facilitates the expulsion of debris when the actuatable assembly is actuated 
     The elongate slotted barrel-like housing  50  also has a compression chamber  50   b , with a coined burst disk  50   c . The coined burst disk  50   c  is selected to keep out debris, rain, sand, dust, ice; and to deform to relieve pressure as the piston moves toward the stop. The compression chamber  50   b  functions to dampen the action of the piston, and the burst disk  50   c  relieves most of the pressure in the compression chamber  50   b , where pressure is created in the compression chamber  50   b  only when the piston is actuated. The elongate slotted barrel-like housing  50  has a first mounting bracket  50   d  for mounting the housing and the piston contained therein to a door/canopy frame. 
     The actuatable assembly  40  also includes a capping housing component  60  that provides access for loading the piston  42  into the elongate slotted barrel-like housing. The capping housing component  60  includes a combustion chamber  60   c  adjacent to the first end  42   a  of the piston  42 . The combustion chamber  60   c  may hold high pressure gases having sufficient force to move the piston  42  through the barrel-like housing  50 , shearing off the shearing pin  12 , and compressing air in the compression chamber  50   b . When the piston  42  is proximate to or upon reaching the stop, the first hinge member  20  decouples from the second hinge member  30 . 
     The capping housing component  60  includes a threaded port  60   d  to accept a shielded mild detonating cord (SMDC) tip device  60   b . The SMDC tip device on ignition produces high pressure gases  60   g  in the combustion chamber  60   c . A safety wire can be connected to the SMDC tip device via a safety wire port  60   c . In one exemplary embodiment, the SMDC tip device utilizes only 65 milligrams of HNS. In another exemplary embodiment, a larger charge device, such as, a type II SMDC tip, may also be employed. The type II SMDC tip uses 144 mgs of HNS. HNS is an abbreviation for hexanitrostilbene, which is listed as a Division 1.1 explosive. A Division 1.1 explosive consists of explosives that have a mass explosion hazard. A mass explosion is one that affects almost the entire load, instantaneously. In the illustrated embodiment, the invention is classified as a safer division 1.4 explosive. Division 1.4 explosives consist of explosives that present a minor explosion hazard. The explosive effects are largely confined to the package and no projection of fragments of appreciable size or range is to be expected. An external fire must not cause virtually instantaneous explosion of almost the entire contents of the package. 
     It is anticipated that a variety of explosive devices and explosive materials are suitable, because the combustion chamber expands when the piston is actuated, therein keeping the explosion largely confined. For HNS, a range of about or more than 220% by weight to weight of explosive material may be used depending on the characteristics of the shear pin. Other explosive materials may work similarly as the actuator assembly may tolerate a wide performance range. The illustrated capping housing component  60  has a mounting bracket  60   f . The retainer  60   a , in the illustrated embodiment is a backstop for the hinge pin  26 . 
     Referring to  FIG. 3 , the invented hinge apparatus  10  having automated decoupling has been actuated. The gases  60   g  have forced the piston to move to the right, as seen in the page. The shear pin  12  has been sheared off into two portions, a first portion  14   a  (in the piston) and a second portion  14   b  (in the housing  50 ). The coined burst disk  50   c  has an etched cross shape available to rupture along the etched portions of the etched crosses similar to the opening of a flower petal. Based on this configuration, pressure is relieved without the coined burst disk  50   c  being blown off. The burst disk  50   c  is selected so that it is not ejected. If the burst disk  50 C is blown off, then it becomes a potentially dangerous fragment. The opposing end  42   e  of the piston  42  is resting against the stop  50   e . There has been no rotational movement of the hinge finger  24 , only translational movement. The high pressure gases  60   g  are temporarily contained in the combustion chamber  60 . When decoupled the door/canopy is free to fall away, and furthermore to be thrust away. Rapid egress though the door/canopy frame is possible. 
     Referring to  FIG. 4 , which is a cross-sectional side view of an alternate embodiment of the invented hinge apparatus having an actuatable assembly  40 . In the alternate embodiment the first connecting apparatus  22  includes the reciprocal hinge finger  34 ′ and hinge gudgeon  36 ′, and the second connecting apparatus  32  includes a hinge finger  24 ′ and a hinge pin  26 ′. The retainer  60   a  is a backstop. The first connecting apparatus  22 , and the second connecting apparatus  32  are coupled similar to the embodiment in  FIG. 1 , except that the reciprocal hinge finger  34 ′ is attached to the piston  42 .  FIG. 3  illustrates that a number of hinged combinations will work with the invented actuatable assembly  40 . 
     Referring to  FIG. 5  the actuatable assembly has linearly shifted the reciprocal hinge finger and the hinge gudgeon, therein decoupling the first hinge member from the second hinge member. 
     Referring to  FIG. 6 , which is a diagrammatic side view of another alternate embodiment of the hinge apparatus, where the piston  42  has a first connecting apparatus  22  with a plurality of hinge fingers  24  and hinge pins  26 , which are coupled to the second connecting apparatus  32  with a plurality of reciprocal hinge fingers  34  and hinge gudgeons  36 . The action of decoupling is the same as previously described. This hinge assembly is much stronger than a single pin and gudgeon, and is self supporting when a door/canopy is connected to the hinge apparatus. Also shown in  FIG. 6  are the first groove  42   g  and the second groove  42   h  for the respective o-rings  42   b , 42   c  which have been previously illustrated. The groove undercuts the surface of the piston, but the o-rings are large enough that only the outer edge of an o-ring comes into contact with the barrel wall  50   i , as shown in  FIG. 10 . 
       FIG. 7  is an end-on view of the embodiment illustrated in  FIG. 6 . 
     Referring to  FIG. 8 , it is a perspective view of the actuatable assembly with the piston removed. The elongate slotted barrel-like housing  50  has an extension  50   h , to facilitate joining the barrel-like housing  50  with the capping housing component  60 . The extension  50   h  is a projected tapered continuation of the barrel wall (see  50   i  in  FIG. 10 ).  FIG. 8  also illustrates the mounting brackets  50   d  and  60   f . A distal end of the slot wall is sloped forming a ramp  50   a.    
       FIG. 9  is another cross-sectional view of the capping housing component  60  illustrated in  FIG. 8 . The exemplary SMDC tip device  60  utilizes milligram quantities of hexanitrostilbene. 
       FIG. 10  is a cross-sectional view of the invented hinge apparatus. The enlarged view illustrates the use of the previously described o-rings  42   b , 42   d . The o-rings serve in-part as spacers, so that only the edges of the o-rings come into contact with the barrel wall  50   i  of the barrel-like housing. Frictional resistance is reduced. The spacing widens machining tolerances, making the actuatable assembly easier to manufacture. The spacing also makes binding between the barrel wall  50   i  and the piston highly improbable. The lowered frictional resistance and narrowed range of frictional resistance taken together enable the amount of explosive material to be reduced, as the invention eliminates most problematic areas. A lower amount of explosive material reduces the noise and impulse pressure, and the invented apparatus is easier on the crew. The illustrated actuator assembly in this view is slightly elliptical, and has an increased resistance to rotational movement. 
     The invention also is a method for rapidly removing a door/canopy of a helicopter. The steps include providing an automated decoupling door hinge apparatus having a first hinge member with a hinge finger, a hinge pin, and an actuatable assembly, where the first hinge member is mounted to a frame for the door/canopy; and a second hinge member with a reciprocal hinge finger, and a hinge gudgeon that is coupled to the hinge pin. The second hinge member is mounted to the door/canopy. The actuatable assembly includes a shear pin, an actuatable rod-like piston connected to the hinge finger. The piston has a first end with a proximate first groove and a first o-ring with first edge, a medial section, a second groove and a second o-ring with a second edge, an opposing end, and a first aperture that receives a first portion of the shear pin. There is an elongate slotted barrel-like housing with a stop. The housing has a slot for the linear movement of the hinge finger and a barrel-like space for the linear movement of the piston. The stop defines a maximum translational distance that the piston may move. There is a second aperture that receives a second portion of the shear pin, and a first mounting bracket that is affixed to the door/canopy frame for mounting the slotted barrel-like housing. There is a capping housing component that provides access for loading the piston into the elongate slotted barrel-like housing, where the capping housing component is comprised of a combustion chamber adjacent to the first end of the piston, a threaded port and a shielded mild detonating cord (SMDC) tip device. The SMDC tip device may produce high pressure gases having sufficient force to move the piston, shearing off the shearing pin, and upon becoming proximate to the stop, decoupling the first hinge member from the second hinge member. The first o-ring and second o-ring limit contact between the piston and the slotted barrel-like housing and the capping housing component, therein establishing a limited frictional resistance, and preventing binding of the piston itself with the slotted barrel-like housing or the capping housing component. The automated decoupling door hinge apparatus is used as a conventional hinge to rotate a door/canopy open and closed; and activating the SMDC tip device actuates the piston, decoupling the hinge apparatus, causing the door/canopy to fall away, and furthermore to be thrust away, and allowing rapid egress though the door/canopy frame. 
     Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding 
     It is to be understood that the foregoing description and specific embodiments are merely illustrative of the best mode of the invention and the principles thereof, and that various modifications and additions may be made to the invention by those skilled in the art, without departing from the spirit and scope of this invention, which is therefore understood to be limited only by the scope of the appended claims.