Disposable syringe with retracting needle
FIELD OF INVENTION 
     The present invention generally relates to hypodermic syringes and more particularly relates to a disposable hypodermic syringe which is readily disabled after its intended use against re-use and also against the dangers of needle sticking during subsequent handling and disposal. 
     BACKGROUND OF THE INVENTION 
     The medical workers who use hypodermic syringes incur considerable possibility of receiving sticks or pricks from the hypodermic needles used in the course of their daily work. Workers who clean up the medical facilities also incur the possibility of such needle pricks. Communicable diseases such as hepatitis and AIDS can be transmitted by these needle pricks. The need is evident for a hypodermic syringe which is disposable and which is readily disabled against the possibility of needle pricks and also against re-use. 
     The hypodermic syringe of the present invention requires few component parts, including a removable protective cap, and each of the parts may be mass produced at relatively little expense. 
     The syringe of the present invention may be filled with liquid for injection into a subject in the same manner as the prior art syringes. After use, the syringe plunger may be retracted and the hypodermic needle released for retraction into the syringe chamber by holding the syringe barrel with one hand and the syringe holding flange with the other hand, then twisting or rotating the syringe flange with respect to the barrel member. The needle is released into the syringe reservoir by the torsion and is permanently contained within the reservoir. The syringe needle is disabled against accidental sticking. 
     The presently known prior art are U. S. Pat. Nos. 3,584,626; 4,542,749; 4,710,170; 4,747,830; 4,747,831; 4,767,413; 4,770,655; 4,790,822; and 4,795,432. 
     OBJECTS OF THE INVENTION 
     One object of the present invention is to provide a hypodermic syringe which can be permanently disabled against a needle stick or prick after its intended use. 
     Another object of the present invention is to provide a hypodermic syringe which is disposable after use. 
     A further object of the present invention is to provide a hypodermic syringe having component parts which are easily and economically molded by injection molding. 
     SUMMARY OF THE INVENTION 
     The foregoing and other objects and advantages of the present invention are provided in hypodermic syringe apparatus having a completely retractable needle. The syringe includes a hollow barrel member formed with a needle support opening at a first end and a reservoir body formed with a needle support carrier means at a first end. The reservoir body is retained against longitudinal movement while permitting rotational movement of the reservoir body within the barrel member. The needle support carrier means is retained against rotational movement while permitting longitudinal movement of the needle support carrier means within the needle support opening. 
     An elastic member is mounted in stressed relation between the needle support opening and the needle support carrier means for urging the needle support member to move into the reservoir body. A disconnectable connection means connects the needle support carrier means to the reservoir body and is adapted to be disconnected by rotational force applied between the barrel member and the reservoir body means. The elastic member is adapted to force the needle carrier means and the needle into the reservoir body when the connection means is disconnected. A liquid plunger means is mounted within the reservoir body for sucking liquid through the needle into the reservoir body and discharging liquid through the needle out of the reservoir body. The plunger member is retained within the reservoir body by at least one barb retainer means formed on the plunger member. 
     The reservoir body is retained within the barrel member by a keeper flange which keeps a flange on the reservoir body in contact with the other end of the barrel member. The needle carrier comprises a needle support post fitted in sliding and non-rotating relation within the needle support opening. 
    
    
     DESCRIPTION OF THE DRAWING 
     FIG. 1 is a partly schematic longitudinal cross-sectional view showing a hypodermic syringe including a protective cap as being ready for intended use; 
     FIG. 2 is the same sectional view as FIG. 1 and showing the syringe plunger in a retracted position as when the reservoir body chamber has been filled with a liquid and/or when the plunger has been retracted to disconnect the reservoir body from the needle carrier member; 
     FIG. 2A is an enlarged view taken from FIG. 2 and showing in more detail the partable web link which connects the reservoir body with the needle carrier member; 
     FIG. 3 is similar to FIGS. 1 and 2 and shows the needle carrier member and needle permanently moved into and retained within the reservoir body chamber; 
     FIG. 4 is a partly sectional and partly elevational view taken at line 4--4 of FIG. 2; 
     FIG. 5 is a longitudinal cross-sectional view of the syringe barrel member as utilized in FIGS. 1-3; 
     FIG. 6 is a longitudinal cross-sectional view of the reservoir body and the needle carrier member as utilized in FIGS. 1-3; 
     FIG. 7 is a longitudinal elevational view of the syringe plunger including its plunger piston and actuation flange; 
     FIG. 8 is a partly sectional and partly elevational view of the syringe barrel as shown at line 8--8 in FIG. 5; 
     FIG. 9 is a partly sectional and partly elevational view of the reservoir body as taken along the line 9--9 of FIG. 6; 
     FIG. 10 is a partly sectional and partly elevational view of the assembled hypodermic syringe as shown at from line 10--10 of FIG. 1; 
     FIG. 11 is a partly sectional and partly elevational view of the syringe plunger as taken along the line 11--11 of FIG. 7. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1, 2, 2A, and 3 show the hypodermic syringe 10 as provided by the present invention. In FIG. 1, the syringe 10 is seen to include a removable protective cap 12. 
     As seen in FIG. 1, the outer barrel member 14 is formed with a barrel retainer flange 42 and a needle support opening 38 which is formed by a needle support collar 40. The support collar 40 forms a support shoulder 58 and two counterbores; the smaller counterbore houses a spring 24. Part of the opening 38 is square in configuration as shown in FIG. 8. Fitted within the barrel member 14 is an inner reservoir body 16 which is attached to a needle support member 20. Support member 20 carries a needle support post 22 and a radially disposed support flange 56. The support flange 56 is connected to the end of the reservoir member 16 by means of a plurality of webs or links 26 as best shown in FIG. 2A and FIG. 9. 
     The reservoir body 16 is formed with a reservoir flange 44 at the other end. The inner bore of the flange 44 is formed with a ramp 36 for use as later described. 
     In view of FIG. 1 and FIG. 10, the reservoir flange 44 and the barrel retainer flange 42 are seen to be retained in contiguous position by means of a keeper flange 48. As shown, the keeper flange 48 has a keeper retainer recess 52 which contains the barrel retainer flange 42. The recess 52 may be formed in connection with a boss 50 in an injection molding operation. The keeper flange 48 is connected to the reservoir flange 44 by means of ultrasonic welding, as a preferred fastening means. As shown in FIG. 1, the flanges 44 and 48 are free to rotate about the barrel retainer flange 42 while at the same time restraining the longitudinal movement of the reservoir body 16 within the barrel member 14. 
     FIG. 10 shows a plunger shaft 32, the body member 16, and the barrel 14 in cross-section. The ramp 36, the keeper retainer recess 52, and the barrel retainer flange 42 are indicated by a dashed line. The boss 50 is shown with respect to the keeper flange 48. 
     Referring now to FIG. 2, the syringe 10 is shown with the plunger member 28 in position withdrawn out of the reservoir body 16 indicating that the reservoir formed by the reservoir 16 has been filled with a liquid medication of some designation. Also, the plunger member 28 is placed in this position in order to provide space for the needle support member 20 and its hypodermic needle 18 to be stored within the reservoir body 16 after being separated from the body member 16. 
     FIG. 4, taken at 4--4 of FIG. 2, shows the reservoir flange 44, the ramp 36, and the plunger shaft 32. 
     FIG. 2A is an enlarged detail showing the barrel member 14, the reservoir body 16, the web support flange 56, and the web link 26 connecting the flange 56 to the reservoir body 16. In FIG. 2, the spring 24 is shown as being in compression between the needle support member 20 and the counterbore in collar 40, and the spring is held in compression by a plurality of the web links 26 as shown in FIG. 2A and FIG. 9. 
     FIG. 3 shows the syringe 10 with the needle support member 20 separated from the reservoir body 16 wherein the spring 24 has forced the needle support member 20 and its hypodermic needle 18 into the chamber within reservoir body 16. It is to be noted that spring 24 could be provided of a tubular elastomer such as rubber. 
     Referring now to FIG. 5, the outer barrel member 14 is shown in greater detail. Shown are the retainer flange 42, the collar 40, the opening 38, the support shoulder 58, the first counterbore, and the smaller counterbore which houses the spring 24. 
     FIG. 8 shows the barrel 14 in section, the shoulder 56, the counterbores, and the opening 38 in elevation. The opening 38 is shown as being square, but other spline arrangements such as spline teeth or other non-circular cross-sections could be utilized. In such event, the needle support post 22, as shown in FIGS. 1 and 2, would be of corresponding outside circumference so that the post 22 could reciprocate within the opening 38 but could not rotate within opening 38. 
     FIG. 6 and FIG. 9 show the reservoir body 16 to have the reservoir flange 44 and the ramp 36 at one end and the needle support member with the flange 56 and the web links 26 being shown in elevation. As shown, the web links 26 are symmetrically arranged around the circumference of the bulkhead 66 and within the inner wall of the reservoir member 16. The rotation, or torque urging rotation, of the reservoir body 16 within the barrel member 14 places stress on the web links 26 until, at some designated torque, the web links 26 are sheared or parted, leaving the flange 56 free to move longitudinally with respect to the reservoir body 16. As shown with respect to FIGS. 2 and 3, the support member 20 is urged into the chamber of reservoir body 16 by the forceful expansion of the spring 24. This movement is rather rapid, and the support member 20 attains some inertia which carries it up against the plunger piston 30 before it comes to rest as shown in FIG. 3. The needle 18 is free of the spring 24. 
     FIG. 7 and FIG. 11 show the plunger member 28 in detail. As shown, the plunger member 28 is formed with a flange 46 at one end and a plunger piston 30 is attached at the other end. The plunger member 28 is equipped with barbed retainer means 34 which have been formed to retain the plunger 28 within the reservoir body 16. When the plunger 28 is brought into the reservoir body 16, the piston 30 and the barbs 34 are forced past the ramp 36 responsive to some distortion between the plastic members. After the plunger 28 has been pushed into the reservoir body 16, the barbs 34 prevent removal of the plunger 28 because the ramp 36 forms a buttress beyond which the barbs 34 may not pass. 
     In operation, the syringe 10 is assembled as shown in FIG. 1 in readiness for its intended use. When used, the protective cap 12 is first removed, and the plunger piston 30 is withdrawn as shown in FIG. 2, usually to suck some liquid medication through needle 18 into the reservoir or chamber formed within the barrel member 16. The syringe 10 is used as any other syringe is used, and after its use has been completed, the plunger is withdrawn to a position as shown in FIG. 2. To disable the syringe against further use and to pull the needle out of any anti-stick position, the barrel member 14 is held with one hand and the composite flange 44-48 is gripped by the other hand. With this grip as described, torque is applied to the reservoir body 26 with respect to the needle support member 20. A shearing force is applied by such torque to the web links 26. At some designated torque force, which is within the capability of a very small person, the web links 26 are parted or broken due to the shearing action between the body 16 and the support member 20. 
     When the web links 26 are parted, the spring 24 then forcefully urges the support member 20 away from the shoulder 58 until the entire support member 20 and needle 18 are completely confined within the reservoir body 16. 
     It is to be noted that the relative dimensions of the spring 24, when fully expanded, are sufficiently long in order to push the entire support member 20 and hypodermic needle 18 positively to within the reservoir body 16. 
     If desired, a portion of the plunger 32 of the plunger member 38 can be serrated to facilitate being broken and removed as shown in some of the prior art. This would be an optional feature not shown in the present drawings. 
     It will be apparent to those skilled in the art that modifications and changes may be made to the embodiment as shown and described without departing from the spirit or scope of the invention which is set forth in the appended claims.