Patent Publication Number: US-2006004468-A1

Title: Prosthetic pneumatic unit

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a buffer air-cylinder apparatus, and more particularly to a prosthetic pneumatic unit, wherein up- and down-traveling velocities of a piston rod thereof can be separately controlled according to users&#39;desires.  
      2. The Related Art  
      Buffer air-cylinder apparatuses have been widely applied to control the activities of objects in translation or rotation, for example furniture, lift car-doors, general doors, and prosthetic limbs.  
      Taiwan Patent Publication Number 85200 discloses a prosthetic pneumatic unit for a prosthetic limb, comprising an air-cylinder, a piston rod, one end of which is connected to a piston of the air-cylinder, and the other end thereof extends outward so as to be connected to a knee joint portion that actuates the piston rod; a separation plate interposed in the interior of the air-cylinder and dividing the air-cylinder chamber into two chambers; an air passage connecting the two chambers, a drag of air passing through which can be controlled by adjusting a valve plug. However, the drags of air passing through the air passage for down and up traveling of the piston rod for the prior art cannot be separately controlled by the adjustment of the valve plug. It means that down- and up-traveling velocities of the piston rod cannot be separately controlled. Therefore, the practicability thereof is largely limited.  
      Thus, it is desired to have a prosthetic pneumatic unit, which down-and up-traveling velocities of a piston rod thereof can be separately controlled according to users&#39;desires.  
     SUMMARY OF THE INVENTION  
      Therefore, a primary object of the present invention is to provide a prosthetic pneumatic unit, which down- and up-traveling velocities of a piston rod thereof can be separately controlled according to users&#39;desires.  
      Another object of the present invention is to provide a prosthetic pneumatic unit, which can be applied to other fields.  
      A further object of the present invention is to provide a prosthetic pneumatic unit having a simple structure and easy to assemble.  
      To achieve the above objects, a prosthetic pneumatic unit in accordance with the present invention comprises a cylinder body, one end of which is closed by a head part, the other end thereof is closed by a bottom part, and a piston is interposed within the cylinder body and defines a first chamber between the piston and the head part and a second chamber between the piston and the bottom part; the cylinder body having a first air passage and a second air passage each having a contraction part at the lower portion thereof; a piston rod, one end of which is connected with the piston and the other end thereof extends outward from the head part of the cylinder body so as to be connected with an object; an elastic member received in the second chamber for pushing the piston back to an original position thereof; a first valve mechanism received in the first air passage for controlling a traveling drag and thus an up-traveling velocity of the piston rod; and a second valve mechanism received in the second air passage for controlling a traveling drag and thus a down-traveling velocity of the piston rod. Thus, the up- and down-traveling velocities of the piston rod thereof can be separately controlled by the adjustments of the first and second valve mechanisms according to users&#39;desires.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will be apparent to those skilled in the art by reading the following description of preferred embodiments thereof, with reference to the attached drawings, in which:  
       FIG. 1  is a perspective view of a prosthetic pneumatic unit in accordance with the present invention;  
       FIG. 2  is an exploded view of the prosthetic pneumatic unit of the present invention;  
       FIG. 3  is a locally exploded view of the prosthetic pneumatic unit of the present invention; and  
       FIGS. 4A and 4B  respectively show a motion diagram of a first valve mechanism and a second valve mechanism of the present invention when a piston rod thereof travels downward and upward. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring to  FIGS. 1 and 2 , a prosthetic pneumatic unit in accordance with the present invention comprises a cylinder body  10 , one end of which is closed by a head part  14 , the other end thereof is closed by a bottom part  15 , and a piston  16  is interposed therein and defines a first chamber between the piston  16  and the head part  14  and a second chamber between the piston  16  and the bottom part  15 ; the cylinder body  10  having a first air passage  101  and a second air passage  102  each having a contraction part  1011 ,  1021  at the lower portion thereof and holes  101   a ,  101   b ,  102   a ,  102   b  on side walls of the upper portion and the contraction part of the lower portion thereof interconnecting with the first and second chambers; a piston rod  13 , one end of which is connected with the piston  16  and the other end thereof extends outward from the head part  14  of the cylinder body  10  so as to be connected with an object; an elastic member  17  received in the second chamber for pushing the piston  16  back to an original position thereof when an external force applied on the piston rod  13  is released; a first valve mechanism  11  received in the first air passage  101  for controlling a traveling drag and thus an up-traveling velocity of the piston rod  13 ; and a second valve mechanism  12  received in the second air passage  102  for controlling a traveling drag and thus a down-traveling velocity of the piston rod  13 .  
      Moreover, the present invention further comprises a cylinder bushing  18  received in the cylinder body  10 . The piston  16  and the elastic member  17  can move therein.  
      Referring to  FIG. 3 , the first valve mechanism  11  comprises a first orifice tube  112 , a first valve plug  111 , a first air door  113 , and a first spring  114 . The first orifice tube  112  has a first orifice plate  1121  therein and a hole  1123  on a sidewall thereof above the first orifice plate  1121  (see  FIG. 4A ), which is interconnected with the hole  101   a  of the first air passage  101  and then the first chamber. One end  113   a  of the first air door  113  is attached to a first orifice  1122  of the first orifice plate  1121  for controlling the on/off of air passing through there, and the other end  113   b  thereof is attached to one end of the first spring  114 . The other end of the first spring  114  is biased against a top surface of the contraction part  1011  of the first air passage  101 . The first valve plug  111  is for example in threaded engagement with the first orifice tube  112 . The tip of the first valve plug  111  can be inserted into or removed from the first orifice  1122  of the first orifice plate  1121  by adjusting upward or downward the engagement thereof with the first orifice tube  112  for controlling an flow rate of air passing through the first orifice  1122 , a traveling drag and thus an up-traveling velocity of the piston rod  13 .  
      Similarly, the second valve mechanism  12  comprises a second orifice tube  122 , a second valve plug  121 , a second air door  124 , and a second spring  123 . The second orifice tube  122  has a second orifice plate  1221  therein and a hole  1223  on a sidewall thereof above the second orifice plate  1221  (see  FIG. 4B ), which is interconnected with the hole  102   a  of the second air passage  102  and then the first chamber. One end  124   b  of the second air door  124  is attached to an top of the contraction part  1021  of the second air passage  102  for controlling the on/off of air passing through there, and the other end  124   a  thereof is attached to one end of the second spring  123 . The other end of the second spring  123  is biased against the second orifice plate  1221 . The second valve plug  121  is for example in threaded engagement with the second orifice tube  122 . The tip of second valve plug  121  can be inserted into or removed from a second orifice  1222  of the second orifice plate  1221  by adjusting upward or downward the engagement thereof with the second orifice tube  122  for controlling an flow rate of air passing through the second orifice  1222 , a traveling drag and thus a down-traveling velocity of the piston rod  13 .  
      Owing that installation positions of the first spring  114  and the first air door  113  of the first valve mechanism  11  are reverse to those of the second spring  123  and the second air door  124  of the second valve mechanism  12 , the length of the first orifice tube  112  is preferably shorter than that of the second orifice tube  122  so as to conveniently assemble the springs  114 ,  123  and the air doors  113 ,  124  and save material.  
      In addition, referring to  FIG. 2 , the present invention further comprises a plurality of O-rings OR or metal rings F, for example Teflon rings, for preventing air leakage.  
      In operation, referring to  FIGS. 4A and 4B , when an external compression force is applied on the piston rod  13 , then the piston  16  moves downward. The air inside the second chamber is pressed and passes through in order the hole  102   b , the contraction part  1021  of the second air passage  102 , the second orifice  1222  of the second orifice tube  122  by the pressed air pushing back the second air door  124 , the hole  1223  of the second orifice tube  122  and the hole  102   a  of the second air passage  102 , and finally enters into the first chamber. In contrast to the second air passage  102 , owing that the pressed air flows via the hole  101   b  into the contraction part  1011  of the first air passage  101  and thus pushes the first air door  113  to tightly attach and close the first orifice  1122 , the pressed air cannot pass through the first air passage  101 .  
      In reverse, when the external force applied on the piston rod  13  is released, the elastic member  17  provides with a restoring force that makes the piston  16  move backward. The air inside the first chamber is pressed and passes through in order the hole  101   a  of the first air passage  101 , the first air passage  101 , the hole  1123  of the first orifice tube  112 , the first orifice  1122  of the first orifice tube  112  by the pressed air pushing back the first air door  113 , the contraction part  1011  of the first air passage  101  and the hole  101   b , and finally back to the second chamber. In contrast to the first air passage  101 , owing that the pressed air flows via the hole  102   a  into the second air passage  102  and then into the second orifice tube  122  and thus pushes the second air door  124  to tightly attach and close the contraction part  1021  of the second air passage  102 , the pressed air cannot pass through the second air passage  102 .  
      Also referring to  FIGS. 1-3 , the openings of the first orifice  1122  and the second orifice  1222  can be controlled by adjusting upward or downward the engagement of the valve plugs  111 ,  121  with the corresponding orifice tube  112 ,  122  thereof. Therefore, the drags of air passing through the first and second air passages  101 ,  102  and thus the up- and down-traveling velocities of the piston rod  13  can be suitably controlled according to users&#39;desires.  
      Seen from the aforesaid descriptions, the present invention has the advantages of a structure simple and easy to assemble, a wide applications and being able to separately adjust the up- and down-traveling velocities of the piston rod thereof.  
      Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.