Hypodermic Syringe

Abstract

A syringe of the hypodermic type including a unitary barrel member having a large upper bore and a small lumen at the lower end thereof communicating with the bore, the lower end of the barrel member being adapted to receive a needle, with a piston assembly slidable in the barrel member and having a sealing portion sealingly engaged the large bore and shaped to discharge all of the medicant from the large bore, there being provided a plunger fixed to the piston assembly and complementary to as well as coextensive in length with the barrel member lumen for the purpose of discharging all of the medicant from the lumen minimizing medicant loss in the syringe.

Description

BACKGROUND OF THE PRESENT INVENTION

Prior hypodermic syringes, particularly of the luer type have a disadvantage that they do not deliver or discharge all of the medicant from the syringe barrel.

These hypodermic syringe constructions normally include a transparent barrel member having a large upper bore communicating with a small lumen at the lower end of the barrel which receives a needle assembly. A plunger assembly is provided reciprocable in the large bore and having a seal thereon engaging the sides of the bore for the purpose of providing the necessary seal to both draw and discharge fluid relative to the barrel member. The seals in these prior constructions have in many instances been incapable of discharging all of the medicant from the large bore so that not only is there residual medicant in the barrel lumen after discharge, but medicant is also not completely dispelled from the large barrel bore.

It is the object of the present invention to obviate the problems in prior art syringe devices as noted above.

SUMMARY OF THE PRESENT INVENTION

In accordance with the present invention a hypodermic syringe is provided having a barrel member and plunger assembly constructed so that upon discharge, all of the medicant is delivered from the barrel member.

In today's mass medicant injection procedures there is a significant trend toward the use of entirely disposable syringe devices. These syringe devices are filled with medicant which is discharged into the patient and thereafter the entire syringe disposed of. It is apparent that with the present high rate of medicant injections per patient that the loss of even a small quantity of medicant in each injection can result over a large number of injections in a significant wasted medicant cost expenditure.

The present invention obviates this problem through the discharge of all of the medicant from the syringe barrel by providing a seal which slides in the larger portion of the barrel member that is configured to discharge all medicant from this large bore, and the seal is provided with a plunger projection extending directly therefrom for discharging all of the medicant from the lumen in the barrel communicating with the large bore in the lower end of the barrel.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the present hypodermic syringe;

FIG. 2 is a fragmentary section of the present syringe with the plunger assembly withdrawn; and

FIG. 3 is a fragmentary section of the present syringe with the plunger assembly in its retracted or discharged position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings a hypodermic syringe 10 is illustrated of the luer type having a transparent barrel 12 slidably receiving a plunger assembly 14. The lower end of the barrel 12 receives a needle hub assembly 16.

The barrel includes an enlarged upper cylindrical portion 18 having a large cylindrical bore 19 therein which is adapted to receive a major portion of the medicant. Communicating with the bore 19 and also formed within barrel member 12 is a tapered lumen 21 that serves to communicate the medicant receiving bore 19 with the needle hub assembly 16. Lumen 21 is of smaller diameter than bore 19 and has at its upper end an arcuate annular juncture 23 with the large bore 19.

The piston assembly 14 is constructed to deliver all of the medicant from the bore 19 as well as from the smaller lumen 21.

Toward this end the piston assembly 14 includes a cylindrical operator 24 having a head portion 25 at the end thereof for facilitating the operator's hand movement of the plunger assembly. Operator 24 has at its lower end a stepped annular boss portion 26 that receives a one piece rubber seal 30.

Seal 30 has an elongated generally cylindrical rubber body having an upper annular seal received securely on the stepped portion 26 and having an annular upper seal 32 and an annular lower seal 33. The annular seals 32 and 33 are semi-circular in cross section with the lower seal 33 being congruent with the juncture 23 so that they define complementary sealing surfaces as shown in FIG. 3 to discharge all of the medicant from the large bore 19 upon movement of the plunger assembly 14 to the position shown in Fig. 3.

For the purposes of assuring that all of the medicant is discharged from the lumen upon discharging the syringe 10, an integral projection 35 is provided on rubber seal 30. Projection 35 is frusto-conical in configuration, congruent and coextensive in length with lumen 21 (as shown in FIG. 3) so that the projection completely discharges the lumen as the plunger assembly 14 is moved to its discharged position shown in FIG. 3 during patient injection.

Claims

I claim:

1. A hypodermic syringe assembly of the luer type, comprising: a unitary transparent barrel member having an upper receptacle portion with a large diameter bore, and a lower portion integral with said receptacle portion and having a lumen communicating with said bore and of a smaller diameter than said bore, said lumen extending entirely through said lower portion to the lower end of said barrel member, a removable needle and hub member with the needle hub surrounding and fixed to said lower portion and slidable thereon, said hub being engaged with the exterior surface of said lower portion and surrounding a substantial lower end portion of said lumen, a plunger slidable in said barrel member for discharging medicament therefrom, said plunger having a seal portion conforming in configuration to and engageable with the juncture between said receptacle and said lumen, said plunger having a small diameter projection fixed thereto and conforming in shape to said lumen, said projection being of sufficient size to completely fill said lumen and of sufficient length to extend in the discharged position of said plunger substantially to the lower end of said lumen and within said hub to assure discharge of substantially all of the medicament from said barrel member said plunger including a rubber seal member having said seal portion thereon and said projection extending axially from said seal portion and having an axial length greater than the diameter of said bore.

2. A syringe assembly as defined in claim 1, wherein said lumen is tapered downwardly and said projection is a part of said seal member and is tapered downwardly complementary with said lumen.

3. A hypodermic syringe assembly of the luer type, comprising: a generally cylindrical barrel member, a needle and hub member connected to the lower end of said barrel member, said barrel member having an upper portion with an upper bore, and a lower portion integral with said upper portion and having a bore communicating with and of smaller diameter than said upper bore, a plunger assembly slidable in said barrel member, seal means on said plunger assembly for discharging all of the medicament from said upper bore, and a projection on said plunger assembly fixed with respect thereto and having an axial length greater than the diameter of said upper bore for discharging substantially all of the medicament from said smaller diameter bore, the hub of said needle and hub member slidably engaging the exterior surface of said lower portion and surrounding a substantial lower end portion of said projection when said plunger assembly is in the discharged position.