US2374368A - Syringe - Google Patents

Description

April 24, 1945. c. v.- R. MEJIA SYRINGE.

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Patented Apr. 24, 1945 2,374,368 SYRINGE Carlos Victor Ramos Mejia, Buenos Aires,

Argentina Application January 19, 1944, Serial No. 518,894 In Argentina February 22, 1943 4 Claims.

The present invention relates to syringesand more particularly to a self-charging syringe intended for making a series of injections of predetermined doses, as for example, in treating cattle and other animals. The novel syringe may also be used upon human patients when a large number of subjects have to receive injection of a given product, .as in hospitals, barracks and the like, and in times of epidemics.

My novel syringe consists essentially of a cylinder, preferably of glass or of some similar transparent material which has secured-to it at one end an inlet valve assembly operated by suction and into the other end of which there extends the shank of a piston member, said shank being a sliding fit in said cylinder and projecting therebeyond and having integrally formed on the end thereof lying outside the cylinder 2. head portion to which is ecured an outlet valve assembly comprising a. needle and needle-holding member. Preferably the cylinder is enclosed in a protective housing or sheath of metal or the like which in the neighborhood of its end remote from the inlet valve may bear graduations with which cooperates a stop projecting from a strokedetermining member secured to one of the elements of the outlet valve assembly. Communication between the inlet valve and the outlet valve is established through a longitudinal bore extending through the piston shank and head. Externally, the inlet valve assembly comprises a nipple adapted to receive one end of a flexible tube, the other end of which may be connected to a nipple on an auxiliary reservoir into which a quantity of the liquid to be injected may be introduced, said liquid being withdrawn in measured doses each time an injection is made. The practical advantages and constructional features of my novel syringe will best be understood from the following description of certain preferred embodiments thereof, illustrated in the accompanying drawings in which,

Fig. l is a longitudinal section of one form of syringe in accordance with the present invention.

Fig. 2 is an elevation of an auxiliary reservoir.

Fig. 3 is a longitudinal section of a slightly modified embodiment of the syringe, and.

Figs. 4-7 inclusive are detailed sectional views of the constituent parts of the outlet valve assembly of the embodiment of Fig. 3.

Referring first to Figs. 1 and 2, my novel syringe comprises a cylinder Ii] preferably of glass or ome other suitable transparent material which at one end has secured to it an inlet valve and connection assembly indicated by the general reference numeral [2. Into the other end of said cylinder I0 and into a longitudinal bore 14 thereof there extends a shank portion N5 of a piston member [8 having ahead 20 to which is secured an outlet valve arrangement indicated by the general reference numeral 22. In order to establish communication between the inlet valve assembly l2 and the outlet valve assembly 22,, said piston member I8 has a longitudinal perforation. 24 throughout its length.

Preferably the cylinder to is enclosed in a protective tubular sheath 26 of metal or the like which'may if desired be provided with openings 28 to permit of the inspection of the interior of the cylinder. When such sheath is used, the

inlet valve assembly may conveniently be screwed thereto.

The inlet valve assembly consists of a housing 30 from which projects a nipple 32 having a longitudinal bore 34 communicating with a small inlet chamber 36, which in turn communicates with a valve chamber '38. In said valve chamber is positioned a valve supporting and seating block 40 having a valve seat 42 formed on the end thereof adjacent the cylinder [0, and a passage 44 extending from the valve seat to the opposite face of said block, thereby establishing, in the assembled condition of the arrangement, a communication between the inlet chamber 34 and the valve seating 42. Between the valve block 40 and the bottom of the inlet chamber 34, I provide a washer 46 preferably of compressible material such as rubber. A valve member 48, shown as a mushroom type of valve, has its head seated on the valve seat 42 and its stem extending through the passage 44. The valve is normally urged against its seat by means of a spring 50. As shown in the drawings the housing 30 of the inlet valve assembly is secured by screwing to the protective sheath 26, but it is of course to be understood that if the sheath is omitted the housing 30 may be secured directly to the cylinder l0.

At the other end of the cylinder I provide a closure member 52 secured as by screwing to the sheath 26 so as to retain the cylinder 10 within said sheath. Preferably a cushioning washer 54 is inserted between the base 56 of said closure member 52 and the end of cylinder in.

The outlet valve assembly comprises a tubular housing 58 in which the head 20 of the piston member is a tight fit and which contains abutting the free face of said head 20, an outlet valve block 60 having on the side thereof adjacent said head a central recess 62 which communicates by means of a passage 64 with a valve seat 66 formed on the opposite side of said outlet valve block. A valve 68 is provided and is normally urged against the seat 66 by means of a spring H1.

The tubular housing 58 is secured to the piston head 20 by means of a screw collar 12, and preferably a resilient washer 14 is interposed between the base 16 of said screw collar and the corresponding end of the housing 58. The other end of the housing is closed by a screw cap 1.8 having a central perforation 80 adapted to receive the root portion 82 of a needle 84, said root portion having a flange 86 which is pressed by said cap 18 against a resilient washer 88 interposed between said flange and the outlet valve block.

The nipple 32 is adapted to be connected as by flexible tubing 90 to a nipple 92of an auxiliary reservoir 94. Said nipple 92 communicates with the bore of a delivery tube 96 extending to the bottom of said reservoir, which preferably is provided'with a charging nipple 98 projecting therefrom at some convenient point.

In order to enable the charge sucked into the cylinder I during operation of the syringe, as

' will hereinafter be described, to be predetermined,

I provide a stroke-determining member comprising a stem I00'extending from the screw collar 12 towards the inlet end of the cylinder and alongside the wall of the cylinder or sheath as the case may be, and a projection or enlargement I00 at the free end of the stem I00.

As shown in Fig. 1, the stem passes through a hole I00" in the closure member 52, and said projection I00 is larger than the hole I00" so that abutment of the projection against the edge of the closure member remote from the outlet valve assembly will determine the maximum retraction of the piston member I6.

In Figs. 3 to 7, I have shown a slightly modified form of syringe according to the present invention. The modifications affect principally the valves and the design of the valve assemblies. The mushroom type valve is satisfactory from the general point of view of operation, but it entails the provision of springs and special metal parts which may not be readily to hand when operating in thefield, should a replacement or repair be needed. The valve arrangements of the alternative embodiment are much cheaper to construct, and dispense with springs, the elasticity being provided by the use of rubber or the like valve members. Thus the carrying of spare parts or the temporary replacement or repair of the valves in the field is greatly facilitated; in addition to which the first cost of the syringe and the cost of the spare parts is considerably reduced.

As shown in Fig. 3, the housing 30a of the inlet valve assembly is simplified by being merged with the valve seating block. It'comprises an internal valve chamber 38a in which an imperforate disc valve 48a is provided, said valve being made of rubber or some equally elastic material. The passage 34a extending through the nipple 32a communicates directly with the valve chamber 38a and on the side thereof remote from said passage I provide an outlet chamber or recess I02,

Similarly, the construction of the outlet valve assembly of the embodiment of Fig. 3 has been simplified. The tubular housing 58a is shown integral with the cap member 1811, said cap member having a central bore 80a designed to take the shaft of the needle 84a and terminating inside the tubular portion 58a in a conical needle seat I04 located between said bore 80a and an annular abutment surface I06 formed at the bottom of said housing 58a. As best seen in Fig. 7, the flanged portion 86a of the needle is externally cylindrical or substantially so, so as to fit snugly within the tubular housing 58a. On the free end of said flange portion 86a, I provide a frustaconical recess I08 forming between its outer, major circumference and the circumference of the flange portion an annular surface IIO between which and the free end of the piston head 20 an outlet valve disc 64a is clamped. Said outlet valve disc is made of rubber or some similar material and has a, preferably diametral, slit IIZ which is normally closed by the natural action of the material but will open to permit passage of liquid if pressure is exerted against said valve disc.

In the embodiment shown in Fig. 3, I have likewise provided a somewhat modified form of screw collar He, the modification consisting principally in the stroke determining device which comprises, as shown, a rod I 00a adapted to be screwed at one end into said screw collar 12a, and having secured to its other end a head II4 having a projection I00'a extending into an opening 28a in the'protective sheath 26a. This stroke determining member limits the retraction of the piston shank with respect to the inlet valve assembly by abutment of the projection I00'a against the blind end of the opening 28a nearest the outlet valve assembly. It will be clear to those skilled in the art that the amount of permitted retraction depends upon the length of the rod I00a. Since said rod is removably secured to the screw collar 1811, the injection dosage may readily be adjusted to a predetermined amount for any particular series of injections by suitably selecting the length of rod utilized. In practice a plurality of dosage members having rods I00a of different lengths would be supplied as accessories of this model of the syringe.

Similarly, the stem I00 of the device shown in Fig. 1 may be removably secured to the member 12. In either case, a scale of graduations may be provided on the cylinder and/or sheath to enable the amount of the dose to be read in the fully inserted position of the piston member by alinement of some indicating mark as the strokedetermining member with one of said graduations.

With the syringe of the present invention in either of the illustrated embodiments connected as hereinbefore described to a suitable source of injection fluid, such as for example the reserve reservoir 94, and with the shank 24 of the piston abutting the resilient washer I I6 interposed between the housing 30 and the cylinder I0 (fully inserted position of the piston member), the apparatus is in a condition for filling or charging. On retracting the piston shank by pulling on the screw collar I2 or 12a, suction will be exerted on the inlet valve 30 or 30a and fluid will be drawn from the reservoir 94 into the space within the cylinder I0 between the washer IIS and the end of the piston shank remote from the head 20. The fluid will also tend to run into the longitudinal bore 24 of the piston member. Retraction of the piston member and hence the volume to be filled with liquid is limited by the projection of the stroke-determining member as hereinabove explained. In order to ensure that all the air has been expelled from the several passages concerned and the whole syringe insary.' These preliminary charging or loading operations should be performed with theneedle pointing upwards'to facilitate the escape of the air and avoid needless spillage.

After being charged in the manner just described, the syringe is taken in the hand with a finger and thumb pressing against'the surface of the screw collar remote from the needle and, while continuing this pressure, the needle is plunged into the body of the patient, whereupon said finger and thumb are removed from the screw collar and the body of the syringe is pushed forward by the hand. In thus pushing forward the body of the syringe its liquid contents are ejected through the needle by reason of the fact that the inlet valve now receives the hydraulic pressure in a sense to force it against its seat Whereas the outlet valve receives the pressure in a sense to move it towards the needle. Thus the exit path for the liquid is established either by the lifting of the mushroom valve from its seat or by the temporary dishing of the disc valve. When the charge has been driven into the patients body the body of the syringe is retracted by the hand in order to withdraw the needle from the patient. Owing to the resistance of the tissues to the withdrawal of the needle the latter will still remain in the patients body until the cylinder and its housin have been retracted sufficiently for the blind end of the slot in the sheath or the surface of the closure member to contact the stop of the stroke-determining member. During this retraction of the cylinder a fresh charge will automatically be sucked into the cylinder so that immediately on withdrawal of the needle which occurs when the full pull can be exerted upon it by reason of the abutment of said stop as aforesaid, the instrument is ready for immediately making a further injection. It will be noted that the operator need not concern himself with the measurement of the dose as this is automatically achieved by the operation of the device.

I claim:

1. In a self-charging syringe for making a series of injections of predetermined doses, a cylinder, a sheath surrounding said cylinder and havin a plurality of longitudinal slots of different lengths therein, a suction operated inlet valve assembly including connection means for connecting said assembly to a reservoir of solution to be injected, and secured at one end to said' sheath, a piston member having a head and a cylindrical shank, said shank projecting reciprocally into said cylinder and projecting therebeyond, and said head being outside said cylinder and having secured to it an outlet valve assembly including a needle holding member having a relatively large recess therein, and a needle receiving bore communicating with said recess, a needle having an enlarged head at one end, said head'being seated within said needle holding member in said recess and said needle projecting through said bore, said piston member having a longitudinal bore whereby communication is established between said inlet and outlet valve assemblies, and stroke determining means mounted on the outlet valve assembly for selectivel predeterminingthe dose sucked into the cylinder and expelled through said needle upon reciprocation of said piston member, said stroke determining means comprising a stem extending longitudinally alongside the piston shank and a lateral projection on, said stem selectively engageable with one of said slots.

.2. A self-charging syringe accordingto claim 1, wherein the inlet valve assembly comprises an imperforate disc valve of flexible material such as rubber, and the outlet'valve assembly consists of an annular nut-like member surrounding said shank and a housing member having a cylindrical externally threaded valve chamber portion screw connected to said annular member and containing said piston head, and an integral needle holder portion having a needle receiving bore, a needle projecting through said needle receiving bore and having an enlarged end fitting in said valve chamber portion and including a frusta-conical recess on the face of the enlarged end remote from the needle, a disc-like outlet valve member of elastic material such asrubber, having a transverse out therein lying within the circumference thereof and extending therethrough, said out being normally held closed by the elasticity of the material, said outlet valve member being held with one face resting against the free end of the piston head and having its edge portion clamped between said cylinder head and the portion of the I needle head surrounding said frusta-conical recess, whereby said outlet valve member may under pressure yield towards said recess to open said slit for the passage of liquid and is prevented from yielding in the opposite direction by abutment against said piston head.

3. A self-charging syringe for making series of injections of predetermined doses, comprising a cylinder of transparent material, a protective sheath surrounding said cylinder, a suction oper ated inlet-valve assembly including connection means for connecting said assembly to a reservoir of solution to be injected, secured to one end of said sheath, a piston member having a cylindrical shank, an enlarged head at one end of said shank, the other end of the shank projecting reciprocally into the end of the cylinder remote from the inlet valve assembly and being a sliding fit in said cylinder, an outlet valve assembly secured to said piston head and including a needle holding member having a relatively large recess therein, and a needle receiving bore communicating with said recess, a needle having an enlarged head at one end, said head being seated within said needle holding member in said recess and said needle projecting through said bore, a longitudinal bore extending through said piston member and establishing communication between said inlet and outlet valve assemblies, a plurality of slots in said sheath extending lengthwise thereof and having a blind end at the extremity thereof nearest the outlet valve assembly, said blind ends being at relatively different distances from the outlet valve assembly, stroke determining means mounted on said outlet valve assembly and including a stem extending towards the inlet valve assembly and havin a projection 'for selectively extending into one of said slots whereby the stroke of the piston member is limited by engagement of the projection with the respective blind end and the dose sucked into the cylinder and expelled through said needle upon reciprocation of said piston member is selectively determined.

4. A self-charging syringe as defined in claim 3, wherein the inlet valve assembly comprises an imperiorate disc valve of flexible material such as rubber, and the outlet valve assembly consists of an annular nut-like member surrounding said shank and a housing member having a cylindrical externally threaded valve chamber portion of the material, said outlet valve member being held with one face resting against the free end of the piston head and having its edge portion clamped between said cylinder head and the portion of the needle head surrounding said frustaconical recess, whereby said outlet valve member may under pressure yield towards said recess to open said slit for the passage of fluid and is prevented from yielding in the opposite direction by 10 abutment against said piston head.

CARLOS VICTOR RAMOS MEJIA.

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