Safety hypodermic syringe

Abstract

A safety hypodermic syringe is disclosed to include a barrel, which has a front connector with a breakable connection portion connected to the peripheral wall of the barrel, a needle assembly connected to the front connector, a flexible stopper fitting the inner diameter of the barrel, a plunger, which has a stopper holder that holds the flexible stopper and a barbed retaining flange disposed at the front side for engaging two hollow retaining wings of the front connector when the plunger is pushed further forward after the service of the safety hypodermic syringe such that the front connector is separated from the barrel and received with the needle assembly to the inside of the barrel upon a return stroke of the plunger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is an exploded view of a safety hypodermic syringe according the present invention.

FIG. 1 b corresponds to FIG. 1a when viewed from another angle.

FIG. 2 is a perspective assembly view of the safety hypodermic syringe according to the present invention.

FIG. 3 a is a top view in an enlarged scale of the safety hypodermic syringe according to the present invention.

FIG. 3 b is a sectional view in an enlarged scale of the front part of the barrel of the safety hypodermic syringe according to the present invention.

FIG. 4 is a sectional view of the present invention, showing a standby status of the safety hypodermic syringe.

FIG. 5 is a schematic sectional view of the present invention, showing the barrel of the safety hypodermic syringe filled with a liquid medicine for injection.

FIG. 6 is a schematic sectional view of the present invention, showing the status of the hypodermic syringe after injection.

FIG. 7 is a schematic sectional enlarged view of a part of the present invention, showing the barbed retaining flange of the plunger engaged with the retaining wings of the conical front connector of the barrel.

FIG. 8 is a schematic sectional enlarged view of a part of the present invention, showing the conical front connector disconnected from the peripheral wall of the barrel.

FIG. 9 is a schematic sectional enlarged view of the present invention, showing the needle assembly received inside the barrel after a return stroke of the plunger.

FIG. 10 is a schematic sectional enlarged view of the present invention, showing the neck of the plunger broken, the needle assembly with the front part of the plunger left inside the barrel.

Claims

1. A safety hypodermic syringe comprising: a barrel, said barrel comprising a fluid chamber, and a front connector suspending in a front end thereof, said front connector defining an axially extending fluid passage in communication between said fluid chamber and the atmosphere, said front connector having two retaining portions protruded from the periphery thereof at two sides, a connection portion extending around the periphery of a rear end thereof and connected to the periphery of said barrel, and a tearing groove formed on said connection portion;a needle assembly, said needle assembly comprising a hub and a needle cannula forwardly extending from said hub, said hub having an axial hole disposed in fluid communication with said needle cannula and a rear coupling portion capped on said front connector of said barrel and engaged into said tearing groove;a plunger, said plunger comprising a shank, a front extension rod forwardly axially extending from a front end of said shank, and a retaining portion at said front extension rod; anda flexible stopper fitting the diameter of said fluid chamber of said barrel, said stopper having a longitudinal chamber through which said front extension rod of said plunger passes, and a front center through hole forwardly extending from said longitudinal chamber to a front side thereof and stopped in front of the retaining portion of said plunger;wherein when pushed said plunger forwards after the service of the safety hypodermic syringe, the retaining portion of said plunger is forced into engagement with the retaining portions of said front connector and said tearing groove is broken to separate said front connector from said barrel for enabling the broken front connector and said needle assembly to be pulled with said plunger backwards to the inside of said barrel upon a return stroke of said plunger at this time.

2. The safety hypodermic syringe as claimed in claim 1, wherein the retaining portions of said front connector are hollow retaining wings; the retaining portion of said plunger is a barbed retaining flange for engaging the hollow retaining wings of said front connector.

3. The safety hypodermic syringe as claimed in claim 1, wherein said barrel has an inside annular stop flange extending around an inside wall near a rear end thereof; said plunger has a head connected between said shank and said front extension rod, said head having a front flange and a rear flange for engagement with the inside annular stop flange of said barrel after a return stroke of said plunger after the service of the safety hypodermic syringe.

4. The safety hypodermic syringe as claimed in claim 3, wherein said plunger further has a neck connected between said shank and said head for breaking to separate said shank from said head after engagement of the front flange and rear flange of said head with the inside annular stop flange of said barrel.

5. The safety hypodermic syringe as claimed in claim 1, wherein the coupling portion of said hub of said needle assembly has a beveled outer surface disposed in contact with said connection portion of said front connector of said barrel.

6. The safety hypodermic syringe as claimed in claim 1, wherein said plunger further comprises a stopper holder formed integral with said front extension rod for holding said stopper, said stopper holder having a front retaining skirt and a rear retaining skirt respectively extending around the periphery thereof; said flexible stopper having an inside annular flange formed in a rear side of said longitudinal chamber and disposed in contact with the periphery of said stopper holder between said front skirt and said rear skirt.

7. A safety hypodermic syringe comprising: a barrel, said barrel comprising a fluid chamber, and a front connector suspending in a front end thereof, said front connector defining an axially extending fluid passage in communication between said fluid chamber and the atmosphere, said front connector having two hollow retaining wings protruded from the periphery thereof at two sides, a connection portion extending around the periphery of a rear end thereof and connected to the periphery of said barrel, and a tearing groove formed on said connection portion;a needle assembly, said needle assembly comprising a hub and a needle cannula forwardly extending from said hub, said hub having an axial hole disposed in fluid communication with said needle cannula and connected to said front connector of said barrel;a plunger, said plunger comprising a shank, a front extension rod forwardly axially extending from a front end of said shank, and a barbed retaining flange around the periphery of a front end of said front extension rod; anda flexible stopper fitting the diameter of said fluid chamber of said barrel, said stopper having a longitudinal chamber through which said front extension rod of said plunger passes, and a front center through hole forwardly extending from said longitudinal chamber to a front side thereof and stopped in front of the barbed retaining flange of said plunger;wherein when pushed said plunger forwards after the service of the safety hypodermic syringe, the barbed retaining flange of said plunger is forced into engagement with the hollow retaining wings of said front connector and said tearing groove is broken to separate said front connector from said barrel for enabling the broken front connector and said needle assembly to be pulled with said plunger backwards to the inside of said barrel upon a return stroke of said plunger at this time.

8. The safety hypodermic syringe as claimed in claim 7, wherein said barrel has an inside annular stop flange extending around an inside wall near a rear end thereof; said plunger has a head connected between said shank and said front extension rod, said head having a front flange and a rear flange for engagement with the inside annular stop flange of said barrel after a return stroke of said plunger after the service of the safety hypodermic syringe.

9. The safety hypodermic syringe as claimed in claim 8, wherein said plunger further has a neck connected between said shank and said head for breaking to separate said shank from said head after engagement of the front flange and rear flange of said head with the inside annular stop flange of said barrel.

10. The safety hypodermic syringe as claimed in claim 7, wherein said plunger further comprises a stopper holder formed integral with said front extension rod for holding said stopper, said stopper holder having a front retaining skirt and a rear retaining skirt respectively extending around the periphery thereof; said flexible stopper having an inside annular flange formed in a rear side of said longitudinal chamber and disposed in contact with the periphery of said stopper holder between said front skirt and said rear skirt.