Abstract:
An intake module includes an outer tube body defining an intake chamber and having an intake end, and an inner tube body disposed in the outer tube body and having an intake hole communicating with the intake chamber. An intake lid covers the intake end and has an inlet hole for allowing the intake chamber to be in fluid communication with the outside so that a compressed gas is fed into the inlet hole. A needle tube defines a jet hole for spraying the compressed gas from the needle tube into the intake hole. When the compressed gas is delivered from the intake lid into the inner tube body, air is drawn into the intake hole to mix with the compressed gas according to Venturi effect.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority of Taiwanese Application No. 101112448, filed on Apr. 9, 2012. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to an intake module, more particularly to an intake module having an entrainment cover by which ambient air is entrained to increase the total flow rate of the intake module. 
         [0004]    2. Description of the Related Art 
         [0005]    A current respiratory device typically includes a respiratory mask coupled to a compressed oxygen cylinder by an intake module for entraining ambient air into the compressed oxygen to dilute the oxygen concentration and increase the total flow rate of the gas flowing into the respiratory mask. However, the diversion mechanisms for entraining ambient air in current intake modules are unable to steadily entrain ambient air into the compressed oxygen stream, making the current mechanisms inefficient for increasing the total flow rate. 
       SUMMARY OF THE INVENTION 
       [0006]    Therefore, an object of the present invention is to provide an intake module for steadily and uniformly entraining ambient air into the compressed oxygen stream to increase the total flow rate of the gas flowing into the respiratory mask. 
         [0007]    According to an aspect of the present invention, there is provided an intake module comprising an air delivery tube, an intake lid, an entrainment cover, and a needle tube. 
         [0008]    The air delivery tube includes an outer tube body and an inner tube body disposed in the outer tube body. The outer tube body includes an intake end, an exhaust end opposite to the intake end, an intake chamber defined by the outer tube body, and an intake port that is formed between the intake end and the exhaust end and that exposes the intake chamber. The inner tube body extends from the exhaust end towards the intake end, and includes an exhaust hole disposed at an end thereof and adjoining the exhaust end, and an intake hole disposed at an opposite end thereof and in fluid communication with the intake chamber. 
         [0009]    The intake lid covers the intake end, seals the intake chamber, and includes an inlet hole that extends through the intake lid and allows the intake chamber to be in fluid communication with the atmosphere. The entrainment cover is sleeved on the end of the inner tube body formed with the intake hole, and has a positioning hole formed therethrough and located between the intake hole and the inlet hole, and an entrainment port for establishing fluid communication between the intake chamber and the intake hole of the inner tube body. The needle tube establishes fluid communication between the inlet hole of the intake lid and the positioning hole of the entrainment cover, and defines a jet hole for spraying a compressed gas from the needle tube into the intake hole. The diameter of the jet hole is less than that of the intake hole of the inner tube body. 
         [0010]    Preferably, the entrainment cover is a hollow and generally conical, and includes a securing ring portion that is sleeved fixedly on the inner tube body, a tapered portion that extends and tapers from the securing ring portion towards the intake end, and an end wall at a tip of the tapered portion. The entrainment port is formed in the tapered portion. The positioning hole is formed in the end wall. The entrainment cover defines a mixing space that is in fluid communication with the intake hole, the entrainment port, and the jet hole. 
         [0011]    Additionally, the air delivery tube defines a central axis (L), about which the inner tube body and the jet hole are centered. 
         [0012]    Preferably, the intake lid further includes a lid body sealably engaging the intake end of the outer tube body, and a rod extending from the lid body towards the inner tube body. The inlet hole extends through the rod and the lid body, is centered about the central axis (L), and has a first hole portion proximal to the lid body for is adapted to be in fluid communication with a compressed gas source, and a second hole portion distal from the lid body and having a diameter smaller than that of the first hole portion. The needle tube extends through the second hole portion. 
         [0013]    According to another aspect of the present invention, there is provided an entrainment cover by which ambient air can be steadily and uniformly entrained into the compressed gas stream to increase the total flow rate of the gas flowing into the respiratory mask. 
         [0014]    The entrainment cover is a hollow and conical, is sleeved fixedly on the inner tube body, and has a positioning hole for establishing fluid communication between the intake hole and the inlet hole via the needle tube. The entrainment cover further has an entrainment port for establishing fluid communication between the intake chamber and the intake hole of the inner tube body, and defines a mixing space that is in fluid communication with the inlet hole, the entrainment port, and the jet hole. 
         [0015]    Preferably, the entrainment cover further includes a securing ring portion sleeved fixedly on the inner tube body, a tapered portion extending and tapering from the securing ring portion towards the intake end, and an end wall at a tip of the tapered portion. The entrainment port is formed in the tapered portion. The positioning hole is formed in the end wall. 
         [0016]    The efficacy of this invention resides in the needle tube and the entrainment cover. Specifically, the needle tube is fixed between the positioning hole of the entrainment cover and the inlet hole, so as to provide a steady stream of compressed gas into the intake module along the central axis. The entrainment cover is sleeved fixedly the inner tube body, and allows for steady and uniform entrainment of ambient air into the compressed gas stream provided by the needle tube to achieve an increased total flow rate of the gas flowing into the respiratory mask. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    Other features and advantages of the present invention will become apparent in the following detailed description of a preferred embodiment with reference to the accompanying drawings, of which: 
           [0018]      FIG. 1  is an exploded perspective view of the preferred embodiment of an intake module of the present invention; 
           [0019]      FIG. 2  is an assembled perspective view of the preferred embodiment; and 
           [0020]      FIG. 3  is a sectional view of the preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0021]    With reference to  FIG. 1 , the preferred embodiment of an intake module of the present invention is coupled to a compressed oxygen cylinder (not shown) via a conduit tube (not shown), and is connected with a respiratory mask (not shown) via a flexible pipe (not shown). The intake module receives compressed oxygen from the compressed oxygen cylinder, and passes it through the flexible pipe and into the respiratory mask for inspiration by a user. 
         [0022]    With additional reference to  FIGS. 2 and 3 , the intake module comprises an air delivery tube  1  having a central axis (L), an intake lid  2  sealably engaging an end of the air delivery tube  1 , a hollow, generally conical entrainment cover  3  disposed within the air delivery tube  1 , and a needle tube  4  for establishing fluid communication between the intake lid  2  and the air delivery tube  1 . 
         [0023]    The air delivery tube  1  includes an outer tube body  11  and an inner tube body  12  disposed in the outer tube body  11 , both of which are centered about the central axis (L). The outer tube body  11  has an intake end  111  that is engageable with the intake lid  2 , an exhaust end  112  opposite to the intake end  111 , an intake chamber  113  defined by the outer tube body  11  and open at the intake end  111 , and an intake port  114  that is formed in the outer tube body  11  between the intake end  111  and the exhaust end  112  and that exposes the intake chamber  113  to the atmosphere. The compressed oxygen flows into the air delivery tube  1  through the intake end  111  of the outer tube body  11 . Ambient air flows into the intake chamber  113  through the intake port  114 . The inner tube body  12  extends from the exhaust end  112  towards the intake end  111 , and includes an exhaust hole  122  that is disposed at an end thereof and that is defined by the exhaust end  112 , and an intake hole  121  that is disposed at an opposite end thereof and that is in fluid communication with the intake chamber  113 . 
         [0024]    The intake lid  2  includes a lid body  21  for sealably engaging the intake end  111  of the outer tube body  11 , a rod  22  extending from the lid body  21  towards the inner tube body  12 , and an inlet hole  221  extending through the rod  22  and the lid body  21  along the central axis (L). The inlet hole  221  has a first hole portion  222  proximate to the lid body  21 , and a second hole portion  223  distal from the lid body  21 . The diameter of the second hole portion  223  is less than that of the first hole portion  222 . 
         [0025]    The entrainment cover  3  includes a securing ring portion  32  securely sleeved on the end of the inner tube body  12  formed with the intake hole  121 , a tapered portion  33  extending and tapering from the securing ring portion  32  towards the intake end  111 , and an end wall  34  at a tip of the tapered portion  33 . A positioning hole  341  is formed in the end wall  34  for receiving one end of the needle tube  4 . An entrainment port  331  is formed in the tapered portion  33  and configured as a rectangular-cross-sectioned slot extending from the middle of the tapered portion  33  to the end wall  34  for establishing fluid communication between the intake chamber  113  and the intake hole  121  of the inner tube body  12 . The size of the entrainment port  331  can be varied during manufacture of the entrainment cover  3  to adjust the amount of ambient air to entrain. In addition, the shape and number of the entrainment port  331  are not limited to those in the preferred embodiment and may be modified as necessary to achieve desired results. 
         [0026]    Further, the entrainment cover  3  defines a mixing space  31  that is in fluid communication with a jet hole  41  of the needle  4 , the entrainment port  331 , and the intake hole  121  and that receives the compressed oxygen flowing from the jet hole  41  and ambient air flowing from the entrainment port  331  to decrease the concentration of oxygen, so as to direct the mixture of the compressed oxygen with ambient air into the intake hole  121 . 
         [0027]    The jet hole  41  has a diameter less than those of the conduit tube and the intake hole  121  of the inner tube body  12  for spraying the compressed oxygen from the needle tube  4  into the mixing space  31 . In this embodiment, one end of the needle tube  4  is inserted through the second hole portion  223  of the inlet hole  221 , while the other end is inserted through the positioning hole  341  and into the fixedly extends along the central axis (L). 
         [0028]    Operation of the intake module of the present invention requires the conduit tube to be disposed between and in fluid communication with the compressed oxygen cylinder and the first hole portion  222  of the inlet hole  221  so that the compressed oxygen flows through the inlet hole  221  out of the jet hole  41  of the needle tube  4 . Because the diameter of the conduit tube is greater than that of the jet hole  41 , the velocity of the compressed oxygen increases and the pressure of the compressed oxygen decreases as it flows through the jet hole  41 . The jet hole  41  directs the flow of compressed oxygen into the mixing space  31  of the entrainment cover  3  towards the intake hole  121  of the inner tube body  12 . Specifically, when the mixing space  31  receives the stream of compressed oxygen from the jet hole  41 , the compressed oxygen stream flows at high velocity and low pressure compared to the ambient air within the mixing space  31 . Via the Venturi effect, the pressure difference causes the stream of compressed oxygen to entrain ambient air in the mixing space  31  as it flows into the intake hole  121 . 
         [0029]    The entrainment of ambient air into the compressed oxygen results in a decrease in the oxygen concentration of the gas flowing through the mixing space  31 , and an increase in the t the gas within the stream. This mixture flows through the inner tube body  12  and out of the intake module from the exhaust hole  122  into the flexible pipe. 
         [0030]    Importantly, the entrainment cover  3  firmly secures the inner tube body  12  and the needle tube  4  along the central axis (L) for optimally introducing ambient air into the intake hole  121  of the inner tube body  12  via the Venturi effect. The compressed oxygen stream steadily and uniformly entrains ambient air, incorporating it therein while flowing to the intake hole  121 , thus increasing the total flow rate of the gas flowing from the intake module into the respiratory mask. 
         [0031]    Further, due to the Venturi effect, when ambient air from the mixing space  31  is entrained by the compressed oxygen into the intake hole  121 , the air pressure within the mixing space  31  decreases. The resulting pressure difference causes the air outside of the outer tube body  11  to enter the intake chamber  113  through the intake port  114 . This ambient air flows from the intake port  114  into the mixing space  31  through the entrainment port  331  to replenish the mixing space  31  with air. 
         [0032]    To sum up, the fixed position of the needle tube  4  between the inlet hole  221  of the intake lid  2  and the positioning hole  341  of the entrainment cover  3  along the central axis (L) allows the compressed oxygen to flow into the mixing space  31  and, via the Venturi effect, steadily and uniformly entrain ambient air as it flows through the mixing space  31 . The addition of ambient air into the compressed oxygen stream increases the total flow rate and thus fulfills the purpose of this invention. 
         [0033]    While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.