Abstract:
An automatic injection syringe that is pre-loaded with medicament and protected from inadvertent ejection of said medicament or injection of air. A plunger assembly is first positioned with a compressed spring in between a plunger and a retainer element. The compressed spring is held in place by a resilient retainer sleeve and the plunger is inside the syringe tube. When the syringe is pushed back, the resilient retainer sleeve releases the spring which then expands to push the plunger into the reservoir of the syringe tube to eject the medicament out from a syringe needle.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to a hypodermic syringe. More particularly this invention concerns a syringe preloaded with the desired amount of medicament that is ready to be injected into a patient. After the needle of the syringe is forced into the patient, a plunger automatically pushes the medicament into the patient through the needle. 
       DESCRIPTION OF PRIOR ART 
       [0002]    A hypodermic syringe is described as having a generally cylindrical syringe tube centered on a longitudinal axis and having a hollow needle with an open tip attached to the front end. A plunger is slidable inside the tube and define the liquid compartment into which the medicament is placed. When the plunger is moved forward toward the needle, the medicament is pushed though the needle and out the open tip of the needle so that the medicament is injected into the patient. 
         [0003]    Hypodermic syringes are primarily used to effect subcutaneous injections. It is well known in the art that many patients are injected with the same dosage of the same medicament. Thus, in preparation, medical professionals often pre-load multiple syringes with the same dosage of the same medicament. When the syringes are pre-loaded, the plunger is left in the retracted position ready to be pushed toward the needle so as to inject the medicament. However, a common problem encountered is that the plunger can be moved forward or backward inadvertently before it is injected into a patient. As this occurs, some of the medicament is pushed out or air is pulled into the tube of the syringe. Either of these scenarios is highly undesirable because it results in the medicament to be contaminated with air or the dosage of the medicament in the syringe to be reduced. Whether air enters the tube of the syringe or some of the medicament is pushed out of the syringe, such pre-loaded syringe becomes unusable and must often be discarded. This problem is primarily caused by the plunger that is unprotected and susceptible to inadvertent movement forward or backward relative to the tube of the syringe. 
         [0004]    Accordingly, there is a need for a syringe with a plunger that is protected or encased so that it does not move forward or backward inadvertently until the medicament is ready to be injected into the patient. 
       SUMMARY OF THE INVENTION 
       [0005]    Accordingly, the present invention has been made in view of the above-mentioned disadvantages occurring in the prior art. The present invention is an automatic injection syringe that is pre-loaded with the desired dosage of a medicament and can be stored for extended periods of time without fear that the plunger will inadvertently be pushed or pulled rendering the syringe useless. 
         [0006]    It is therefore the primary object of the present invention to provide a syringe with a plunger that is encapsulated or encased so that it may not be inadvertently pushed or pulled. 
         [0007]    Another object of the present invention is to provide a syringe that can be pre-loaded with the desired amount of medicament. 
         [0008]    Yet another object of the present invention is to provide a syringe that automatically injects the medicament into the patient once the needle is forced into the patient. 
         [0009]    A still further object of the present invention is to provide a syringe with components that can be varied so as to control the rate by which the medicament injected into the patient. 
         [0010]    A yet further object of the present invention is to provide a syringe that is cost effective to manufacture. 
         [0011]    The above objects and other features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention described in detail with reference to the accompanying drawings. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying drawings which are incorporated by reference herein and form part of the specification, illustrate various embodiments of the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. In the drawings, like reference lumbers indicate identical or functional similar elements. A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
           [0013]      FIG. 1  is a perspective view of the automatic injection syringe of the present invention in its assembled state as it would be assembled before use on a patient. 
           [0014]      FIG. 2  is an exploded view of the automatic injection syringe of the present invention. 
           [0015]      FIG. 3  is a perspective view of the tube of the present invention. 
           [0016]      FIG. 4  is a perspective view of the shell of the present invention. 
           [0017]      FIG. 5  is a perspective view of the shell cap of the present invention. 
           [0018]      FIG. 6  is a perspective view of the plunger of the present invention. 
           [0019]      FIGS. 7 a  and 7 b    are a perspective views of the retainer of the present invention. 
           [0020]      FIGS. 8 a  and 8 b    are a perspective views of the retainer sleeve of the present invention. 
           [0021]      FIG. 9  is a perspective view of the plunger assembly of the present invention. 
           [0022]      FIG. 10  is an exploded view of the plunger assembly of the present invention. 
           [0023]      FIG. 11  is a cross-sectional view of the automatic injection syringe of the present invention in its assembled state as it would be before use on a patient. 
           [0024]      FIG. 12  is a cross-sectional view of the automatic injection syringe of the present invention in its assembled state as it would be after use on a patient. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    Reference will now be made to the drawings in which various elements of the present invention will be given numerical designations and in which the invention will be discussed so as to enable one skilled in the art and make use the invention. 
         [0026]    The present invention comprises an automatic injection syringe  100  comprising a syringe tube  10 , a shell  20 , a shell cap  30 , a needle  40 , a sleeve  45 , a needle cap  43 , and a plunger assembly  90  which comprises a plunger  50 , a spring  60 , a retainer  70 , and a retainer sleeve  80 . It is well known that in the treatment of patients, medical professionals often inject the same dosage of the same medicament. Thus, as a time saving exercise, it is customary for medical professionals to pre-load multiple syringes with the same dosage of the same medicament ready for use. However, conventional syringes comprise a plunger that is exposed and can be manually displaced inadvertently so as to release some of the medicament and render the pre-loaded syringe useless. The automatic injection syringe  100  of the present invention allows a syringe to be pre-loaded with medicament and encapsulates the plunger so as to eliminate the risk that it will be inadvertently displaced. Then when needed, the medical professional can inject the medicament into a patient without pressing or even touching the plunger. 
         [0027]      FIG. 1  shows a perspective view of the automatic injection syringe  100  of the present invention in its assembled state as it would be used.  FIG. 2  shows an exploded view of the automatic injection syringe  100  of the present invention to depict in greater detail the various components that comprise the automatic injection syringe  100 . The main component of the present invention is the tube  10  having an opening  11  in one end and the needle  40  with the sleeve  45  attached to the opposing end. The needle  40  is hollow with an open tip and in fluid communication with the interior of the tube  10 . Accordingly, any fluid or medicament inside the tube  10  can be forced or pushed to be discharged through the needle  40  out the open tip. An important element of the tube  10  is an annular flange  12  that extends outwardly around the opening  11 , as shown in  FIG. 3 . 
         [0028]      FIG. 4  shows a perspective view of the shell  20  that is tubular in shape and having a front opening  21  and a rear opening  22 . However, the rear opening  22  is larger in diameter than the front opening  21 . The preferred design of the shell  20  includes a taper  23  towards the front to create the smaller front opening  21 , as shown in  FIG. 4 . 
         [0029]      FIG. 5  shows a perspective view of the shell cap  30  that is also tubular in shape and having an opening  31  in one end while the other end is closed. The design configuration of the shell  20  and the shell cap  30  is such that the shell cap  30  can be attached to the rear opening  22  of the shell  20  so as to cover or cap it. Furthermore, the diameter of the rear opening  22  of the shell  20  is large enough for the tube  10  to be inserted therethrough but small enough for the annular flange  12  not to pass through. Thus, the tube  10  can be inserted into the shell  20  until the annular flange  12  rests against the rear opening  22 . Additionally, the length of the shell  20  is smaller than the length of the tube  10  such that when the tube  10  is inserted into the shell  20  until the annular flange  12  rests against the rear opening  22 , a portion of the sleeve  45  is exposed and protrudes past the front opening  21  of the shell  20 , as shown in  FIG. 1 . 
         [0030]      FIG. 6  shows a perspective view of the plunger  50  that is tubular in shape having a closed, end  51  and an opening  52  in the opposing end. In addition, an o-ring  54  is used around the plunger  50  to provide a radial seal. Finally, the plunger  50  has an annular groove  55  as shown in  FIG. 6 . The spring  60  is inserted into the plunger  50  through the opening  52 . 
         [0031]      FIGS. 7 a  and 7 b    shows a perspective view of the retainer  70  that is tubular in shape having a closed end  71  and an opening  72  in the opposing end. Additionally, the retainer  70  has two flexing elements  73  which extend along the sidewall of the retainer  70  and can flex radially inward and outward. Each flexing element  73  has an inner peg  74  that protrudes radially inward and an outer peg  75  that protrudes radially outward, as shown in  FIGS. 7 a    and  7   b.    
         [0032]      FIGS. 8 a  and 8 b    shows a perspective view of the retainer sleeve  80  that is tubular in shape with a base  81  and a base opening  82  in one end and a top opening  83  in the opposing end. The base  81  has a large section  81   a  and a small section  81   b  such that the inner diameter of the large section  81   a  of the base  81  is larger than the inner diameter of the small section  81   b  of the base, as shown in  FIG. 8 a   . Above the base  81 , the retainer sleeve  80  has various groves  84  that are configured to allow the retainer sleeve  80  to be compressed longitudinally. 
         [0033]      FIGS. 9 and 10  show a perspective and an exploded view, respectively, of the plunger assembly  90 . The plunger assembly  90  is the assembly of the plunger  50 , the spring  60 , the retainer  70 , and the retainer sleeve  80 . The plunger assembly  90  is assembled by first inserting the spring  60  into the plunger  50  through the opening  52  until it rests against the closed end  51 . Then the retainer  70  is placed over the spring  60  such that the spring  60  is inserted through the opening  72 . Then the retainer  70  is pushed toward the plunger  50  so as to compress the spring  60  until the inner pegs  74  on the retainer  70  are aligned with the annular groove  55  on the plunger  50 . Then the retainer sleeve  80  is placed over the retainer  70  such that the closed end  71  of the retainer  70  is passed through the base opening  82  until the outer pegs  75  are within the large section  81   a  of the base  81  of the retainer sleeve  80 . Then, the flexing elements  73  of the retainer  70  are flexed inward so that the inner pegs  74  are inserted into the annular groove  55 . Finally, the retainer sleeve  80  is pushed further toward the plunger  50  until the outer pegs  75  are pushed into the small section  81   h  of the base  81  of the retainer sleeve  80  so that the inner pegs  74  are held within the groove  55 . Accordingly, the plunger assembly  90  is maintained assembled by the inward flexing of the flexing elements  73  such that the inner pegs  74  are retained within the groove  55 , thus, mechanically locking the plunger assembly  90 , as shown in  FIG. 9 . 
         [0034]    Once the plunger assembly  90  is assembled, it is coupled with the tube  10  through the opening  11  so that the plunger  50  is inside the tube  10  and the base  81  of the retainer sleeve  80  rests on the annular flange  12  of the tube  10 . With the plunger assembly  90  in place, the tube  10  is inserted into the shell  20  through the rear opening  22  until the annular flange  12  rests against the rear opening  22  and a portion of the sleeve  45  is exposed and protrudes past the front opening  21  of the shell  20 . Finally, the shell cap  30  is attached to the rear opening  22  of the shell  20  so as to cover or encapsulate the entire tube  10  and plunger assembly  90  within the shell  20  and the shell cap  30 . Once the shell cap  30  is attached to the shell  20 , the automatic injection syringe  100  of the present invention is ready for use, as shown in  FIG. 11 . However, when immediate use is not necessary or when storage of the automatic injection syringe  100  is required, the needle cap  43  is used to cover the needle  40  so that it does not inadvertently poke or puncture somebody. 
         [0035]    When the automatic injection syringe  100  of the present invention is ready for use to inject medicament into a patient, the needle cap  43  is removed and the needle  40  is forced into the patient in such a manner and to such extent as to press against, the portion of the sleeve  45  that is exposed and protrudes past the front opening  21  of the shell  20 . In doing this, the tube  10  is pushed back so as to longitudinally compress the retainer sleeve  80 . As the retainer sleeve  80  is pushed back longitudinally, the large section  81   a  of the base  81  is aligned with the outer pegs  75  so as to allow the flexing elements  73  to displace to its natural position, thus, releasing, the inner pegs  74  that are held within the groove  55 . This allows the spring  60  to extend to its natural uncompressed length, thus, pushing the plunger  50  toward the needle  40 , as shown in  FIG. 12 . As the force of the spring  60  pushes the plunger  50 , the medicament is forced to discharge through the needle  40  and into the patient. 
         [0036]    It is well known in the field of art that different medicaments have to be injected with different injection rates. Thus, the automatic injection syringe  100  of the present invention can be configured with a spring  60  having a compressibility ration that corresponds the desired injection rate. This way, when the spring  60  is released, the stiffness of the spring  60  will allow the plunger  50  to be pushed forward at the desired injection rate. For example, the stiffer the spring  60 , the greater the force with which the plunger  50  will be pushed, thus, resulting in a greater injection rate. Similarly, the less stiff the spring  60 , the lower the force with which the plunger  50  will be pushed, thus, resulting in a lower injection rate. 
         [0037]    Therefore, the automatic injection syringe  100  of the present invention is superior in design and functionality than any existing prior art. It is understood that the described embodiments of the present invention are illustrative only, and that the modifications thereof may occur to those skilled in the art. Accordingly, this invention is not to be regarded as limited to the embodiments disclosed, but to be limited only as defined, by the appended claims herein.