Abstract:
A coaxial double layer parachute includes an inner inflatable body and an outer canopy which are located along a central axis. Since the inner inflatable body is filled with helium to generate a first buoyance, the inner inflatable body can be obviously lifted to a certain height. When a payload connected to the inner inflatable body and the outer canopy with parachute cords falls, the ambient air flows will enter the inflation space through the annular air inlets to produce a second buoyance, which makes the outer canopy open completely. Hence, a secure descending task from even a very low height can be fulfilled if the coaxial double layer parachute can employed. Apparently, the coaxial double layer parachute can be mainly applied to fire and earthquake rescue actions in the cities when low height deployments, risk-free parachuting, and less complicated manual operation are required.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Field of the Invention 
         [0002]    The present invention relates to a parachute, and more particularly to a coaxial double layer parachute which can be mainly applied to fire and earthquake rescue actions in the cities when low height deployments, risk-free parachuting, and less complicated manual operation are required. 
         [0003]    Description of the Prior Art 
         [0004]    Parachute is an aerodynamic decelerator which is fixed to a payload by a connecting member. Hence, the parachute can be deployed to slow down the falling speed of the payload by creating a drag. 
         [0005]    However, the deployment of most parachutes requires a great height to carry out parachuting. Second, failure of an operational parachute extraction system causing fatalities and injuries leads to less trust in using parachuting decelerator as a fire escape device. Third, relatively complicated manual operation and skills are required. 
         [0006]    The present invention has arisen to practically amend the afore-described disadvantages. 
       SUMMARY OF THE INVENTION 
       [0007]    The primary objective of the present invention is to provide a coaxial double layer parachute which can be applied to fire and earthquake rescue actions. 
         [0008]    To achieve the above objective, a coaxial double layer parachute in accordance with the present invention comprises an inner inflatable body and an outer canopy which are located along a central axis. The inner inflatable body can be obviously lift to a certain height since the inner inflatable body is filled with helium, a less dense gas than air, to generate a first buoyance. When the payload connected to the inner inflatable body and the outer canopy falls, the ambient air flows will enter an inflation space via the annular air inlets at the lower end of the outer canopy to produce a second buoyance, which makes the outer canopy open completely. Hence, the coaxial double layer parachute can be applied to the tall buildings where fire and earthquake rescue actions take place because it can be opened automatically without requiring great height, parachuting failure and complicated manual operation. 
         [0009]    Preferably, a plurality of fabric panels, peripherally partitioning the lower section of an inflation space into several sectors as air flow tunnels, is outwardly connected to the inside surface of the outer canopy and inwardly connected to the outside surface of the inner inflatable body, so as to prevent the inner inflatable body and the outer canopy from mutual deviation with respect to the central axis during the descent of the coaxial double parachute. 
         [0010]    Preferably, the inner inflatable body is provided with an air flow guiding round-nose in the form of an arc-shaped surface to guide air flows to the air inlets effectively. 
         [0011]    Preferably, a formed circular plate is disposed between the inner inflatable body and a lower end of the outer canopy to provide much more tensile strength to the structures at the bottom surface of the outer canopy and amid the inner inflatable body. 
         [0012]    Preferably, the outer canopy takes the form of a downward tapered surface which can stabilize the entire parachute through the air pressure annularly acting on the downward tapered surface and inside the inflation space between the inner and outer sides of the outer canopy, and reduce unexpected swing during the descent of the parachute. 
         [0013]    Preferably, a formed circular plate is provided with a plurality of air inlets, which substitute for the annular air inlets at the bottom surface of the outer canopy, will make the air flow inlets very rigid for withstanding strong air flow and turbulence. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of a coaxial double layer parachute in accordance with a first embodiment of the present invention; 
           [0015]      FIG. 2  is a plan view of the coaxial double layer parachute in accordance with the first embodiment of the present invention; 
           [0016]      FIG. 3  is another plan view of the coaxial double layer parachute in accordance with the first embodiment of the present invention; 
           [0017]      FIG. 4  is a perspective view of a coaxial double layer parachute in accordance with a second embodiment of the present invention; 
           [0018]      FIG. 5  is a plan view of the coaxial double layer parachute in accordance with the second embodiment of the present invention; and 
           [0019]      FIG. 6  is another plan view of the coaxial double layer parachute in accordance with the second embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    The present invention will be clear from the following descriptions when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
         [0021]    Referring to  FIG. 1 , a coaxial double layer parachute  10  in accordance with a first embodiment of the present invention comprises: an inner inflatable body  20  and an outer canopy  30 . The inner inflatable body  20  is used to fill with helium and includes an air flow guiding round-nose)  21  at a lower portion of the inner inflatable body  20 . The air flow guiding round-nose  21  is profiled an arc-shaped surface  210 . A restricting cord  22  has one end connected to a bottom of the air flow guiding round-nose  21 , and the other end connected to a payload T. 
         [0022]    The outer canopy  30  covers the inner inflatable body  20  which is disposed inside the outer canopy  30  while between the outer canopy  30  and the inflatable body  20  is defined an inflation space  31 . The bottom surface  32 , been formed from the lower portion of the outer canopy  30  and provided with a plurality of air inlets  320  which are annularly arranged, is directly connected to the air flow guiding round-nose  21  of the inner inflatable body  20 . At each of four corners of the top surface of the outer canopy  30  is formed an air exhaust port  33 , and to the periphery of the bottom surface  32  are connected plural connecting cords  34  which are annularly arranged. Each of the connecting cords  34  has one end connected to the periphery of the bottom surface  32  and the other end connected to the (payload) T. Around the connecting cords  34  is disposed a fixing ring  340  which is located adjacent to the payload T. 
         [0023]    Referring then to  FIGS. 2 and 3 , the inner inflatable body  20  and the outer canopy  30  are coaxially arranged on an central axis H of the coaxial double layer parachute  10 , and the inner inflatable body  20  is filled with helium to generate a first buoyance F, which will make the inner inflatable body  20  lift to a certain height since helium is much less dense than air. When the payload T connected to the inner inflatable body  20  and the outer canopy  30  falls, the ambient airflow  40  will enter the inflation space  31  via the air inlets  320  to produce a second buoyance F 1 , which makes the outer canopy  30  open completely. Meanwhile, the restricting cord  22  and the connecting cords  34  connected to the inner inflatable body  20  and the outer canopy  30  will be upwardly pulled tight. While the restricting cord  22  is pulled tight, the inner inflatable body  20  will be restricted to the central axis H, so that the first buoyance F of the inner inflatable body  20  can uniformly apply upwards along the central axis H to prevent the inner inflatable body  20  from random deviation. 
         [0024]    After the inner inflatable body  20  is inflated with helium, the first buoyance F makes the inner inflatable body  20  lift. Then, the air flow field  40  especially surrounding the inner inflatable body  20  will be guided by the arc-shaped surface  210  of the air flow guiding round-nose  21  of the inner inflatable body  20  through the air inlets  320  at the bottom surface  32  of the outer canopy  30  to the inflation space  31 , so as to produce the second buoyance F 1 , which makes the parachute open completely. In a word, when the payload T connected by the restricting cord  22  and the connecting cords  34  falls, the coaxial double layer parachute  10  will descend in a pre-inflation manner. 
         [0025]    Therefore, the coaxial double layer parachute  10  of the present invention can be applied to the tall buildings where fire and earthquake rescue actions take place because it can be opened automatically without requiring complicated manual operation and great height. 
         [0026]    In addition, the connecting cords  34  connected to the periphery of the bottom surface  32  of the outer canopy  30  are rimmed and restricted by the fixing ring  340 , so that the connecting cords  34  can be pulled tight and prevented from tangling one another. 
         [0027]    Referring then to  FIG. 4 , a coaxial double layer parachute  10  in accordance with a second embodiment of the present invention comprises: an inner inflatable body  20 , an outer canopy  30  and a formed circular plate  50 . 
         [0028]    The inner inflatable body  20  is used to fill with helium and provided with a plurality of fabric panels  23  around the outer surface of the inner inflatable body  20 , and an air flow guiding round-nose  21  at lower portion of the inner inflatable body  20 . The air flow guiding round-nose  21  is profiled an arc-shaped surface  210 . A restricting cord  22  has one end connected to a bottom of the air flow guiding round-nose  21 , and the other end connected to a payload T. 
         [0029]    The outer canopy  30  covers the inner inflatable body  20  which is disposed inside the outer canopy  30  while the outer canopy  30  and the inflatable body  20  is defined an inflation space  31 . At each of four corners of the top surface of the outer canopy  30  is formed an air exhaust port  33 , and to the periphery of the bottom surface  32  are connected plural connecting cords  34  which are annularly arranged. Each of the connecting cords  34  has one end connected to the periphery of the bottom surface  32  and the other end connected to the payload T. Around the connecting cords  34  is disposed a fixing ring  340  which is located adjacent to the payload T. 
         [0030]    The formed circular plate  50  made of rigid and extra-light material, like carbon glass, is disposed between the inner inflatable body  20  and a lower end of the outer canopy  30 , and provided with a plurality of air inlets  51 , which are annularly arranged. The formed circular plate  50  is design to substitute for the bottom surface  32  at the lower end of the outer canopy  30  while the plural air inlets  51  play the same role as the air inlets  320 . 
         [0031]    Referring then to  FIGS. 5 and 6 , as indicated in the first embodiment of the present invention, the inner inflatable body  20  and the outer canopy  30  are coaxially arranged on the central axis H of the coaxial double layer parachute  10 , the inner inflatable body  20  is disposed inside the outer canopy  30  that has been removed the air inlets  320  and the bottom surface  32 . 
         [0032]    Secondly, the formed circular plate  50  is disposed between the inner inflatable body  20  and a lower end of the outer canopy  30 . With the rigid formed circular plate  50 , the outer canopy  30  and the inner inflatable body  20  can not only be bridged, but also be strengthened to withstand the pressure of the stronger air flows and turbulence around their bottom ends. 
         [0033]    Thirdly, the plural fabric panels  23 , peripherally partitioning the lower section of an inflation space into several sectors as air flow tunnels, is outwardly connected to the inside surface of the outer canopy  30  and inwardly connected to the outside surface of the inner inflatable body  20 , so as to prevent mutual deviation of the inner inflatable body  20  and the outer canopy  30  from the central axis H during the descent of the coaxial double layer parachute  10 . 
         [0034]    Since the inner inflatable body  20  is filled with helium to generate a first buoyance F, which will make the inner inflatable body  20  lift to a certain height since helium is much less dense than air. When the payload T connected to the inner inflatable body  20  and the outer canopy  30  falls, the ambient air flows  40  will be guided to the inflation space  31  via the air inlets  51  to produce a second buoyance F 1 , which makes the outer canopy  30  open completely. 
         [0035]    It is to be noted that the inner inflatable body  20  and the outer canopy  30  can be evenly tightened in axial and radial directions by the fabric panels  23 , so that the outer canopy  30  can be kept equidistantly from the inner inflatable body  20 . As a result, the air flows  40  can be uniformly filled in the inflation space  31  between the inner inflatable body  20  and the outer canopy  30 . 
         [0036]    In summary, the coaxial double layer parachute  10  in accordance with the present invention has the following advantages: 
         [0037]    First of all, before the payload T gets ready to falls even from a low height, the first buoyance F will make the inner inflatable body  20  gradually lift to a position atop the payload T and then pull tight the restricting cord  22 , the connecting cords  34  and the outer canopy  30  since the inner inflatable body  20  is being pre-filled with helium. When the inner inflatable body  20  lifts to a certain height, the ambient air flow  40   s  will enter the inflation space  31  via the air inlets  51  at the state of one atmosphere. After the payload T falls, the ambient air flows  40  especially surrounding the air flow guiding round-nose  21  will be guided by the air flow guiding round-nose  21  to rush into the inflation space  31  via the air inlets  51  to produce the second buoyance F 1  making the outer canopy  30  open completely, so that the coaxial double layer parachute  10  of the present invention can be deployed easily and safely. 
         [0038]    Secondly, the inner inflatable body  20  and the outer canopy  30  are located at the same central axis H, and can therefore be maintained at the coaxial position, no matter how heavy a variety of pressures such as the first buoyance F, the second buoyance F 1 , or/and the air ambient flows  40  inwardly and outwardly exert on them. In other words, the plural fabric panels  23  radially and axially tighten the inner inflatable body  20  and the outer canopy  30 , so as to prevent the inner inflatable body  20  and the outer canopy  30  from entanglement or/and coaxial dislocation during the descent of the coaxial double layer parachute  10 . 
         [0039]    Thirdly, the air exhaust ports  33  are formed at four corners atop the outer canopy  30  to leak a small amount of the air flows  40  from the inflation space  31 , which reduce unexpected swing caused by environmental turbulence during the descent of the coaxial double layer parachute  10 . 
         [0040]    Fourthly, it is highlighted that, according to the aerodynamic theorem as well as the experimental results correlated each other, the outer canopy  30  with a very huge downward tapered surface  300 , steadily holds the outmost air flows  40  downwards in order to balance the air flows  40  of the inflation space  31 , so as to make the coaxial double layer parachute  10  descend much more stably. 
         [0041]    Finally, the formed circular plate  50  made of an extra-light and rigid material like carbon glass is designed to strengthen the structures near the bottom end of the outer canopy  30  and amid the inner inflatable body  20 . Nevertheless, the air inlets  51  of the formed circular plate  50  allow the air flows  40  to enter the inflation space  31  to push up the outer canopy  30  more smoothly and effectively. 
         [0042]    While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. cm What is claimed is: