Patent Publication Number: US-2004049160-A1

Title: Safety hypodermic syringe

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a safety hypodermic syringe wherein the plunger is pulled back and broken to allow the needle cannula and the locking tip to be left in the barrel after the injection is completed.  
       BACKGROUND OF THE INVENTION  
       [0002] A conventional hypodermic syringe for injecting medicine into patient&#39;s body generally includes a barrel with a plunger movably inserted therein from a first end thereof and a locking tip with a needle cannula is fixed to a second end of the barrel. Medicine is sucked in the space of the barrel and the plunger has a stopper which seals the inner periphery of the barrel so as to push the medicine out from the needle cannula. A cap is used to re-mount the needle cannula so as to prevent the needle cannula from hurting people. It is dangerous for people being hurt by the needle cannula which is attached with medicine, the patient&#39;s blood or body liquid. Nevertheless, the re-cap action is proceeded in a hospital hundreds of time in one day and the nurses work under a potential risk of being hurt by the discarded needle cannulas.  
       [0003] The present invention intends to provide a safety hypodermic syringe, the needle cannula can be pulled back into the barrel and left in the barrel after the injection action.  
       SUMMARY OF THE INVENTION  
       [0004] In accordance with one aspect of the present invention, there is provided a safety hypodermic syringe which comprises a barrel having an opening defined in a first end thereof through which the plunger is inserted. A base and a connection piece are movably received in the barrel and a passage is defined through the base. A needle cannula unit is fixed connected to the base and extends out from the second end of the barrel.  
       [0005] The plunger has an insertion which is inserted through the connection piece and into the passage in the base. The insertion is securely engaged with the connection piece. A stopper is mounted to a root portion of the insertion. A breaking groove is defined in an outer periphery of the plunger and located close to the second end of the plunger.  
       [0006] The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007]FIG. 1 is a cross sectional view to show the safety hypodermic syringe of the present invention;  
     [0008]FIG. 2 is an exploded view to show the safety hypodermic syringe of the present invention;  
     [0009]FIGS. 3A and 3B show the plunger is inserted into the barrel to be engaged with the base;  
     [0010]FIG. 3C shows that the plunger has engaged with the base and to be pulled back;  
     [0011]FIG. 3D shows the plunger is pulled back after injection and broken at the breaking groove;  
     [0012]FIG. 4 is an enlarged view to show the engagement of the insertion of the plunger and the base; and  
     [0013]FIG. 5 is an enlarged view to show that the flange of the connection piece is deformed and disengaged from the first groove in the barrel. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0014] Referring to FIGS. 1, 2  3 A and  3 B, the safety hypodermic syringe of the present invention comprises a barrel  10  having a space  11  defined therein and an opening is defined in a first end of the barrel  10 . The opening communicates with the space  11 . The barrel  10  has a first groove  111  defined in an inner periphery thereof and is located close to the second end of the barrel  10 . A second groove  112  is defined in the inner periphery of the barrel  10  and located close to the first end of the barrel  10 .  
     [0015] A base  70  is movably received in the barrel  10  and includes a tube  71  located in the base  70 , a passage  711  defined through the tube  71 . An engaging recess  73  is defined in a first end of the base  70  and a threaded inner periphery  72  is defined in a second end of the base  70 . A cylindrical connection piece  60  has a hole  622  defined therethrough and is engaged with the engaging recess  73 . The connection piece  60  has a flange  61  on an outer periphery thereof and a ridge  611  extends from an inner periphery of the hole  622  of the connection piece  60 . The base  70  has a first connection protrusion  731  extending from an inner periphery of the engaging recess  73  and the connection piece  60  has a second connection protrusion  621  on an outer periphery thereof. The first connection protrusion  731  is engaged with the second connection protrusion  621 . The flange  61  of the connection piece  60  is flexible and engaged with the first groove  111  in the barrel  10  as shown in FIG. 4.  
     [0016] A needle cannula unit  30  has a flange  31  which is engaged with the threaded inner periphery  72  of the base  70  and the needle cannula extends out from the second end of the barrel  10 . A cap  40  can be mounted on the needle cannula unit  30 .  
     [0017] A plunger  20  has a thumb rest on a first end thereof and an insertion  21  extends from a second end of the plunger  20 . A groove  211  is defined in the root portion of the insertion  21  and the stopper  50  is engaged with the groove  211  in the root portion of the insertion  21 . An enlarged skirt  213  extends from an outer periphery of the insertion  21  and is securely engaged with the connection piece  60  by being engaged with the ridge  611  of the connection piece  60  when the plunger  20  is inserted into the barrel  10  and the insertion  21  is inserted through the hole  622  in the connection piece  60  and into the passage  711  in the base  70 . By this way, the plunger  20  is connected to the base  70  and the connection piece  60 . A breaking groove  23  is defined in an outer periphery of the plunger  20  and located close to the second end of the plunger  20 .  
     [0018] The plunger  20  can be pulled back to suck medicine into the space  11  in the barrel  10  and then be pushed toward the base  70  to inject the medicine into the patient. Referring to FIG. 5, the flange  61  of the connection piece  60  is flexible and can be easily disengaged from the first groove  111  to allow the pull of the plunger  20 .  
     [0019] Referring to FIGS. 3C and 3D, after the infringe, the plunger  20  together with the base  70  and the needle cannula unit  30  are pulled back and the plunger  20  has a flange  22  extending from the outer periphery thereof and the flange  22  of the plunger  20  is engaged with the second groove  112  so that the user knows that the plunger  20  is positioned and the user breaks the plunger  20  at the breaking groove  23  to leave the needle cannula unit  30  in the barrel  10 .  
     [0020] During the action, the users do not need to touch the needle cannula and the possibility of being hurt by the used needle cannula can be reduced.  
     [0021] While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.