Filter Syringe

Abstract

A syringe for the injection of liquid having a diaphragm sealing the open end thereof and a filter member between the diaphragm and the open end of the vial with a hollow needle mounted for reciprocal movement between retracted position beyond the diaphragm and operated position piercing the diaphragm but not piercing the filter member.

Description

This invention relates to syringes for the injection of solutions and it relates more particularly to a syringe in which the solutions are effected therein immediately prior to injection by bringing the liquid solvent into contact with the solute in liquid, solid or powdered form.

In the recently issued Cohen U.S. Pat. No. 3,557,787, description is made of a disposable syringe formed by telescoping tubular members in which the inner tubular member of smaller dimension is adapted to contain a liquid solvent and the outer tubular member of larger dimension is adapted to contain the liquid, powdered or solid material in measured amounts for solution to provide a desired dosage.

The inner tubular member is provided with a flexible seal to separate the two chambers and which is adapted to open in response to pressure generated by a piston member displaceable in the inner tubular member to effect transmission of the liquid from the inner tubular member to the outer tubular member. The end of the inner tubular member sealably engages the inner wall of the outer tubular member and functions as a piston to force displacement of the solution from the outer tubular member into the needle in communication therewith for injection.

It has been found that often times complete solution of the powdered or solid material is not effected with the result that solids remain suspended thereby to represent a foreign material in the solution which it is undesirable to include with the liquid injected.

Similarly, in syringes that have been pre-packaged and sterilized with a solution or liquid to be injected from a single container, often times solids form by reason of decomposition, reaction or otherwise upon standing thereby to represent a foreign material which it is undesirable to include with the solution or liquid that is being injected.

Thus it is an object of this invention to provide a syringe for the injection of liquid or other solution and which embodies means for the removal of solids contained or otherwise suspended therein as the liquid is being ejected from the syringe.

These and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of limitation, an embodiment of the invention is shown in the accompanying drawing in which:

FIG. 1 is a schematic sectional elevational view of a sryinge embodying the features of this invention in normal position of use; and

FIG. 2 is a sectional elevational view showing the arrangement of elements during ejection of fluid from the needle end portion of the syringe.

Referring now to the drawing, the fluid 10 to be injected is illustrated as being contained in a vial 12 having an open end 14 formed with a neck portion 16 which terminates in an outwardly extending angular flange portion 18. The fluid 10 is maintained in sealing relation within the vial by means of a diaphragm 20 of rubber or plastic material which is dimensioned to span the opening and extend therebeyond for a distance corresponding to the neck flange 18 of the vial. The diaphragm 20 is clamped in sealing relation on the end of the vial by means of a metal cup 22 which is crimped about the outer flange portion of the neck and the corresponding outer edge portions of the diaphragm 20 to effect a sealing engagement between the adjacent flattened outer end portion of the neck flange 18 and the diaphragm 20, when in the assembled relation. The cup member 22 is formed at its outer end with an inwardly extending annular flange 25 and compressed within said cup resiliently to engage the annular flange is a compression spring 26 which is wound about a needle hub 27 having a disc member 31 of larger dimension which functions as an abutment for the opposite end of the spring. The main outward portion of the hub is formed with threads 29 for threaded engagement with internal threads of a needle cover 32.

The hub member supports a hollow needle 28 which is mounted for endwise movement between a retracted position in which the inner sharpened end portion 30 terminates just short of the diaphragm 20 and an operated position in which the needle is displaced inwardly to a position wherein the inner sharpened end portion 30 of the needle penetrates the diaphragm for direct communication with the interior of the vial to enable ejection of fluid from the vial through the needle. Reference may be made to U. S. Pat. Nos. 3,557,787 and No. 3,401,693 for means for mounting the needle releasably to retain the needle in retracted position for releasing for movement to operated position in response to removal of the needle cover 32. In the modification illustrated in FIG. 1, the coil springs 26 operate immediately to effect displacement of the needle from retracted to operated position in response to removal of the needle cover which releases the hub.

In accordance with the practice of this invention, direct communication between the needle and the interior of the vial containing the liquid to be ejected is obstructed by a filter member 34 in the form of a filter disc which extends crosswise between the flanged open end portion of the vial and the diaphragm to span the open end of the vial and for sealing engagement between the clamped flanged neck end portion 18 of the vial and the diaphragm 20, as by heat sealing to the upper surface of the diaphragm. The filter disc can be formed of ceramic, paper, plastic, rubber, glass or the like material having communicating fine pores for the removal of solids from the liquid passing therethrough but without obstructing fluid flow, such as filter pores of 0.1 to 1 micron and preferably about 0.2 to 0.4 micron.

In order to permit needle penetration of the diaphragm 20 without piercing the filter disc 34, the diaphragm is dimensioned to have a thickness whereby the inner wall 36 is spaced inwardly from the end 30 of the needle when the latter is in operated position. A well 38 is provided to extend through the central portion of the diaphragm from the inner wall in endwise alignment with the needle to a depth sufficient to provide for entrance of the needle end 30 when displaced to operated position. Thus, the diaphragm 20 is effective to maintain the sealed relationship to seal the liquid in the vial while enabling penetration of the needle into the well for communication with the interior of the vial when in operated position. The filter element 34 is in position beyond the end of the needle to separate the well from the interior of the vial whereby all liquid entering the well for ejection through the needle is required to pass through the filter element.

Operation of the invention will be described with reference to a syringe of the type illustrated in U. S. Pat. No. 3,557,787, although it will be understood that the inventive concepts may be adapted to a syringe in which the liquid to be injected is housed within a single vial having a piston member adapted to force the liquid from the vial.

In the modification which is shown in FIG. 1, when it is desired to effect injection of a measured amount of liquid from the syringe, the piston 44 in the inner vial 42 is displaced endwise to force the liquid 40 for displacement through the flexible sealing diaphragm 46 from the inner vial to the outer vial 12 containing the powder 48. The vials are then shaken to dissolve the powder or other solid material or to mix the two different liquids in the event that one vial contains one and the another the other. When the solution has been effected and the injection is to be made, the needle cover 32 is removed. This releases the needle 28 which is actuated by the tension springs 50 for displacement from retracted to operated position during which the end 30 of the needle pierces the thin wall of the diaphragm 20 for entrance of the needle into the well 38.

Thereafter, the inner vial 42 is displaced in the illustrated modification to eject the liquid from the outer vial 12. This forces the liquid to flow through the filter element 34 to fill the well 38 and from the well to the needle 28 for injection as pressure continues to be placed on the liquid in the vial. Solids 52, which remain suspended in the liquid, are separated out on the ingoing side of the filter surface as the liquid flows therethrough thereby to deliver a filtered fluid to the needle 28.

It will be understood that the concepts of this invention will have application to syringe devices formed of but a single vial in which a liquid material is contained for injection with the filter element and diaphragm arranged in the manner heretofore described.

It will be understood that changes may be made in the details of construction and operation without departing from the spirit of the invention, especially as defined in the following claims.

Claims

I claim:

1. In a syringe for the injection of a liquid including a vial having an open end through which the liquid is to be ejected from the vial and a plunger axially displaceable in said vial for displacement of liquid through the open end, a rupturable diaphragm extending across the open end of the vial in sealing relation therewith, a hollow injection needle having inner and outer pointed ends endwise aligned with the open end of the vial and mounted for endwise movement between retracted position with the inner end of the needle spaced a short distance beyond the diaphragm and operated position with the inner end of the needle piercing the diaphragm, the improvement which comprises a filter member spanning the open end of the vial between the end of the vial and the diaphragm, said diaphragm constituting a member separate and apart from the filter, a well in the diaphragm extending from the side adjacent the filter member partially through the diaphragm in endwise alignment with the needle and into which the inner end of the needle extends when in operated position and stop means mounted intermediate the needle ends, whereby in the operated position the inner needle end will extend through the diaphragm but not pierce the filter.