Compact Syringe

Abstract

A syringe having a liquid holding barrel closed at one end and open at the other. A piston sealingly and slidably disposed within the barrel and a rod connected to the piston and extending through and substantially beyond the open end of the barrel. A cannula is connected to the outer end of the rod, the piston and rod having a passageway extending therethrough and communicating between the interior of the barrel and the cannula. A closure yieldably obstructs the movement of fluid from the barrel through the cannula.

Description

This invention relates in general to a syringe for injecting fluids into a patient and, more particularly, to a type thereof which is compact in size and relatively inexpensive to manufacture.

It has become increasingly advantageous, if not economically essential, to provide single service packaging for injectable medicaments, whether they be used for direct injection into a patient or as additives for intravenous feeding. That is, the cost of the materials used in fabricating a syringe has been reduced by technological advancement, particularly relative to other costs, to the point where it is not economically sound, in most instances, to furnish a syringe of the type which is sterilized after each use so that it can be refilled for another use. Moreover, the single service syringe eliminates the risk of contamination carried from one use to the next and, in fact, avoids the possibility of contamination in general.

Incident to the increasing interest in the single service syringe has been the desire for a reduction in cost, hence, in size of the syringe. In pursuing the problem of size reduction, it occurred to me that the piston in the syringe barrel could advantageously be connected to the cannula and thereby reduce the overall length of the syringe, while retaining the same liquid capacity. Moreover, this would simplify the provision of closure means or valve means for preventing a leak of the liquid from the syringe barrel during a storage period. Furthermore, this arrangement would provide for a far greater flexibility in syringe capacities with a minimum of component parts.

Accordingly, the primary object of this invention is the provision of a compact, single service syringe capable of relatively inexpensive fabrication and including a totally enclosed compartment in which the liquid to be injected is stored until time for the injection.

A further object of this invention is the provision of a syringe, as aforesaid, which is leak-proof, under normal storage conditions, which is virtually contamination-proof, and which is comprised of components which provide for a maximum of capacity variation with a minimum number of components.

Other objects and purposes of the invention will become apparent to persons familiar with this type of device upon reading the following specification and examining the accompanying drawings, in which:

FIG. 1 is a side elevational view of a syringe embodying the invention;

FIG. 2 is a partially exploded sectional view substantially as taken along the line II-II in FIG. 1;

FIG. 3 is a sectional view substantially as taken along the line III--III in FIG. 2;

FIG. 4 is a sectional view taken along the line IV--IV in FIG. 1;

FIG. 5 is a sectional view taken along the line V--V in FIG. 2;

FIG. 6 is a fragment of FIG. 3 illustrating a modified construction; and

FIG. 7 is a fragment of FIG. 3 showing a further modification.

For convenience in description, the terms "upper," "lower" and words of similar import will have reference to FIGS. 1, 2 and 3 and parts thereof. The terms "inner," "outer" and derivatives thereof will have reference to the geometric center of said syringe or any major components thereof.

SUMMARY OF THE INVENTION

The objects and purposes of the invention, including those set forth above, have been met by providing a syringe having an axially elongated cylindrical and cup-shaped barrel in which a resiliently flexible piston is slidably and sealingly disposed. Rod means is connected at one end to the piston and at the other end to a cannula. An axial opening through the piston, which connects with a passageway through the rod, serve as a communication between the interior of the barrel and the cannula. A yieldable closure means, such as a slit membrane in the piston, yieldably obstructs movement of the liquid from within the barrel through the passageway and out the cannula.

DETAILED DESCRIPTION

The syringe assembly 10, a preferred embodiment of which is illustrated in FIGS. 1 and 2, is comprised of a barrel 11, a piston 12 disposed within said barrel 11, a rod 13 connected at one end to said piston, and a cannula 14 connected to the other end of the rod 13. A sheath 16 is provided to cover the cannula prior to use thereof.

The barrel 11 is cup-shaped, preferably cylindrical, axially elongated and it may be fabricated from glass, plastic or some other substantially rigid material.

The piston 12, which is fabricated from an elastomeric material, such as synthetic rubber, is substantially cylindrical in shape and slightly larger in outside diameter than the inside diameter of said barrel 11, which with said piston defines a chamber 17. The piston 12 preferably has a plurality, here three, of radially extending, spaced ridges 18 which improve the sealing engagement between it and the inner wall of the barrel 11.

In a preferred embodiment of the invention, the piston has two coaxial recesses 21 and 22 in the opposite axial ends thereof, which recesses are spaced from each other to form a relatively thin membrane 23 integral with the piston 12. The membrane 23 has a slit 24 substantially diametrically thereof and therethrough whereby said membrane acts as a valve obstructing the flow of fluids through the piston under circumstances where the pressure on opposite sides of the membrane is substantially equalized.

The rod 13 (FIG. 2) is elongated and, throughout most of its length, is X-shaped in cross-section (FIG. 4) in order to minimize the amount of material utilized while maintaining adequate strength and rigidity in said rod. There are three annular and radially disposed flanges 27, 28 and 29 (FIG. 2) integral with said rod and located near the upper end thereof, near the middle thereof, and near the lower end thereof, respectively. The lower flanges 28 and 29, as shown in FIG. 1, are elongated transversely of said rod 13 in one diametrical direction, and they are so spaced with respect to each other that the first and second fingers of a normal adult hand can be inserted between these two flanges for controlling the movement of the rod 13 relative to the barrel 11.

The rod 13 has an integral, upwardly extending and substantially cylindrical stem 32 which is of approximately the same diameter as the inside diameter of the cylindrical recess 22 in the piston 12. The stem 32 has an upper, annular flange 33, the peripheral surface of which is beveled so that it slopes downwardly and outwardly away from the stem and thereby resists disengagement of the stem from within the piston 12 after it is inserted into the recess 22.

The stem 32 also has a second, lower flange means 34 which, in this embodiment, is comprised of four segments 36 (FIG. 5), the radial edges of which define involute curves 37A terminating at their outermost points in radial surfaces 37 extending back to the stem. The radial surfaces 37 of the segments 36 positively oppose rotation of the stem 32 relative to the piston 12 in one rotational direction, thereby permitting rotation of the rod 13 and piston 12 relative to the barrel 11 in order to break loose any seizing that may occur between the piston and the barrel during a period of prolonged storage. The flange means 34 also has a downwardly and outwardly sloping peripheral surface to facilitate insertion of the stem into the piston and resist removal thereof.

The lower end of the rod 13 is provided with an integral nozzle 38 which is coaxial and substantially cylindrical, but preferably has an outer surface which converges slightly downwardly. A passageway 39 extends substantially coaxially completely through the rod 13 including the stem 32 and nozzle 38. The rod 13 may be fabricated from plastic, glass or any other convenient material. When the stem 32 is properly disposed within the recess 22, the upper flange 27 is snugly against the lower end of the piston 12 and the upper end of the stem 32 is preferably spaced a short distance from the membrane 23. The upper end of the stem 32 has a slight concavity 42 which coaxially encircles the upper end of the passageway 39. Thus, as shown in FIG. 3, the edges of the membrane 23 defining the slit 24 therein can move downwardly into the concavity 42 when fluid in the chamber 17 is exposed to a compressive force, whereby the fluid can enter the passageway 39.

The cannula 14 may be substantially conventional with a sharpened tip 43 at the lower end thereof. The upper end of the cannula 14 is firmly embraced by the lower, reduced end portion 44 of the coupling sleeve 46 which is substantially cylindrical and has an internal surface which diverges upwardly slightly so that it can firmly and frictionally engage and be sleeved upon the nozzle 38. The cannula will normally be fabricated from metal but the sleeve 46 can be fabricated from plastic, glass, metal or the like. The lower end 44 is permanently connected to the cannula 14, as by being molded thereto or affixed thereto by an adhesive.

The sheath 16 is substantially cylindrical, relatively narrow in cross section and closed at the lower end thereof. Said sheath has, at least at its upper end, an upwardly diverging inner surface designed to sleeve snugly upon and frictionally engage the outer surface of the sleeve 46. Said sleeve 46 is preferably provided at its upper edge with a radially outwardly extending flange 47 against which the upper end of the sheath 16 abuts in order to prevent an excessive gripping between the sheath and the sleeve. Thus, when the sheath 16 is pulled downwardly, relative to the sleeve 46, it will release from the sleeve, rather than causing the sleeve to release from the nozzle 38.

ASSEMBLY AND OPERATION

Persons skilled in the field of making and using syringes will perceive the operation of said syringe assembly 10 from the foregoing description. However, the assembly of the syringe and its functioning will be summarized briefly hereinafter for convenience.

Normally, the barrel 11 will be placed in an upwardly opening position and filled with a fluid, such as a liquid medicament, prior to the assembly of the syringe. The piston 12, having been connected to the stem 32 of the rod 13, will then be inserted into the chamber 17 of the barrel 11. Usually, piston 12 will be moved downwardly into the barrel 11 so that any air on top of the liquid can escape up through the slit in the membrane 23 and be expelled from the syringe. At the same time, the air leaving the barrel, which will normally be sterile, will purge non-sterile air from within the passageway 39 in the rod 13. The sleeve 46 on the cannula 14 is then telescopically mounted upon the nozzle 38 so that accidental disengagement therebetween is not likely to occur. The sheath 16 is then mounted upon the sleeve 46 and the syringe 10 is ready for use, storage or shipment, as desired.

When it becomes desirable to use the syringe 10, the sheath 16 is disengaged and removed from the sleeve 46 so that the cannula 14 is exposed. The syringe 10 is then placed in the hand of the operator so that the first and second fingers of such hand are disposed between the flanges 28 and 29 on opposite sides of the rod 13. The upper closed end of the barrel 11 is pressed against the palm of the same hand, roughly adjacent the thumb. Thus, by moving the first and second fingers, toward the thumb, the piston 12 is moved into the barrel 11 whereupon the liquid in the chamber 17 is expelled through the slit in the membrane 23, through the passageway 39 and into the cannula 14 from which it is discharged.

While this type of syringe is normally designed for a single use and subsequent disposal, it would be possible to sterilize and reuse at least some parts of the syringe, such as the barrel 11, the rod 13 and the cannula 14.

It will also be recognized that, under some circumstances, it may be desirable to furnish the syringe 10 without the cannula 14 and its sleeve 46 mounted on the rod 13. In such case, the nozzle may be covered with a small cap and the cannula will be mounted on the rod at the time of use. This will reduce the size of the package for shipment.

ALTERNATE STRUCTURE

FIG. 6 illustrates an alternate structure for the nozzle 38 at the lower end of the rod 13 of FIG. 2. Specifically, the rod 13A (FIG 6) has a nozzle 38A which is encircled by a substantially concentric cylinder 51 spaced radially from the nozzle 38A and having a spiral groove 52 in the inner surface thereof. Thus, the diametrically elongated flange 47 on the upper end on the sleeve 46 can be moved upwardly within the cylinder 51 by rotating the cannula relative to the rod 13A until the sleeve 46 firmly and snugly engages the nozzle 38A.

In the alternate structure illustrated in FIG. 7, the cylinder 53 has coaxial adjacent grooves 54 in its internal surface. The flange 56 on the sleeve 46B, which is also diametrically elongated in one direction, simply snaps along said grooves as it is inserted into the cylinder until the sleeve 46B snugly engages the nozzle 38B.

It will be seen that the capacity of the syringe assembly 10 can be varied as desired over a wide range by merely using a barrel 11 and cooperating piston 12 of various diameters. All other components of the syringe may remain the same. Also, for small variations, such as several cubic centimeters, of capacity, a slightly longer or shorter barrel 11 can be furnished without any other changes in the syringe. Both the diameter and length of the barrel can be changed for maximum variations.

Although a particular preferred embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A syringe for dispensing a liquid medicament, comprising:

hollow cylindrical barrel means having a closed axial end and an open axial end;

elastomeric piston means sealingly and slidably disposed within said barrel means for movement lengthwise thereof, said piston means having a central opening therethrough in a direction substantially parallel with the direction of movement of said piston means;

closure means yieldably obstructing the flow of liquid from said barrel means, said closure means comprising a membrane integral with said piston means and extending across said opening, said membrane having a slit therethrough;

elongated rod means having an end portion adjacent one end thereof extending into and firmly held within said opening in said piston means, said rod means having a central passageway therethrough and being longer than said barrel means, whereby said rod means projects outwardly through the open axial end of said barrel means;

one-way gripping means coacting between said end portion and said piston means

1. for preventing relative rotation between said end portion and said piston means in one rotational direction to thereby permit rotation of the rod means and the piston means relative to the barrel means to break loose any seizing that may occur between the piston means and the barrel means and

2. for permitting axial insertion of said end portion into said opening of said piston means while preventing said end portion from being axially separated from said piston means; said one-way gripping means including projection means fixed to said end portion and projecting radially outwardly therefrom for distorting the portion of said piston means defining the opening therethrough, the axial end face of said projection means which faces away from the other end of said rod means being formed with an inclined surface thereon which slopes downwardly and outwardly toward said other end of said rod means to facilitate axial insertion of said rod means into the opening formed in said piston means, the other axial end face of said projection means extending outwardly substantially radially relative to the longitudinal axis of said rod means for preventing said rod means from being axially separated from said piston means; and laterally projecting grip means on said rod means near the other end thereof.

2. A syringe according to claim 1, including elongated cannula means having one end thereof connected to the other end of said rod means and communicating with the passageway therethrough, said cannula means including a sleeve portion of enlarged inside and outside diameter adjacent said rod means, said inside diameter diverging toward said rod means, and said sleeve portion including a flange fixed adjacent the free end thereof and projecting outwardly therefrom;

wherein said rod means has a substantially cylindrical portion at the other end thereof, said cylindrical portion converging toward said cannula means for snug frictional engagement within the inside diameter of said sleeve portion;

wherein said rod means has a sleeve part at said other end thereof disposed outwardly from and positioned in surrounding relationship to said cylindrical portion for defining an annular space therebetween, said sleeve part having the inside surface thereof formed with groove means thereon, said sleeve portion of said cannula means projecting into said annular space with said flange being engaged within the groove means for fixedly securing said cannula means to said rod means;

wherein said sleeve portion of said cannula means is axially longer than said sleeve part so that a portion of said sleeve portion projects outwardly beyond the free end of said sleeve part when said cannula means is mounted on said rod means; and

elongated sheath means closed at one end and open at the other end for sealingly enclosing and surrounding said cannula means, the inside surface of said sheath means adjacent said other end being snugly and slidably engagable with the external surface of said sleeve portion where same projects outwardly beyond said sleeve part.

3. A syringe according to claim 1, wherein said projection means includes an annular flange fixed to and surrounding said end portion and projecting radially outwardly therefrom, and wherein said one-way gripping means also includes a plurality of circumferentially spaced projections fixed to said end portion and projecting radially outwardly therefrom for distorting the portion of said piston means defining the opening therethrough, said projections being axially spaced from said annular flange and including a substantially radially directed face on one side thereof and a sloped face extending inwardly from the outer end of said radial face to the outer periphery of said end portion, whereby said projections effectively prevent rotation between said piston means and said rod means only in said one rotational direction.

4. A syringe for dispensing a liquid medicament, comprising;

hollow cylindrical barrel means having a closed axial end and an open axial end;

elastomeric piston means sealingly and slidably disposed within said barrel means for movement lengthwise thereof, said piston means having a central opening therethrough in a direction substantially parallel with the direction of movement of said piston means;

closure means yieldably obstructing the flow of liquid from said barrel means, said closure means comprising a membrane integral with said piston means and extending across said opening, said membrane having a slit therethrough;

elongated rod means having an end portion adjacent one end thereof extending into and firmly held within said opening in said piston means, said rod means having a central passageway therethrough and being longer than said barrel means, whereby said rod means projects outwardly through the open axial end of said barrel means;

one-way gripping means coacting between said end portion and said piston means for preventing relative rotation therebetween in one rotational direction, thereby permitting rotation of the rod means and the piston means relative to the barrel means to break loose any seizing that may occur between the piston means and the barrel means; and

said one-way gripping means includes a plurality of circumferentially spaced projections fixed to said end portion and projecting radially outwardly therefrom for distorting the portion of said piston means defining the opening therethrough, said projections including a substantially radially directed face on one side thereof and a sloped face extending inwardly from the outer end of said radial face to the outer periphery of said end portion, whereby said projections effectively prevent relative rotation between said piston means and said rod means only in said one rotational direction;

the axial end face of each said projection which faces away from the other end of said rod means being formed with an inclined surface thereon which slopes downwardly and outwardly toward said other end of said rod means to facilitate insertion of said rod means into the opening formed in said piston means, the other axial end face of each said projection extending outwardly in a substantially radial plane relative to the longitudinal axis of said rod means for preventing said rod means from being axially separated from said piston means; and

laterally projecting grip means on said rod means near the other end thereof.