US2526365A - Hypodermic syringe - Google Patents

Description

Oct. 17, 1950 N. B. .JoRGENsEN HYPODERMIC SYRINGE Filed March 7, 1949 Patented Oct. 17, 17950 UNITED STATES PATENT OFFICE HYPODERMIC SYRINGE Niels Bjorn Jorgensen, Los Angeles, Calif.

Application YMarch 7, 1949, Serial No. 80,044

' of which the piston could be withdrawn by the plunger. Accordingly, such a syringe can be operated only to inject fluid from the syringe into a patient, and is not reversely operable to withdraw fluid from the patient into the syringe. Such Withdrawal operation is a desirable characteristic, since, in the injection ofv some medicaments, it is desirable to avoid injection into a blood vessel. The common method of testing `to determine whether the needle of the syringe has entered a blood vessel is to advance the piston only a slightdistance and then to withdraw it tov the beginning of its stroke. In the event that the needle has entered a blood vessel, blood will be drawn back into the syringe and will, by its characteristic red color, warn the operator of that fact. Since'many of the medicaments that are injected directly from the ampule are of a type which would be injurious if injected directly into a blood vessel or which, for some other reason, should not be injected into a blood vessel, there has for many years been a need for a reversely operable syringe of a type embodying a medicinev The primary object of my invention is ampule. to provide such a syringe.

While there have been a number of Vprior' proi posals attempting to answer this need, they have all, so far as I am aware, proposed to utilizea retrograde movement transmitting connectionl between the syringe plunger and the stopper of the ampule. Such an expedient necessarily involves some means on the end of the plunger foriv piercing or clasping the ampule stopper, and so far as I am aware, none of them has proved to be practicable. Y

In contrast to these prior proposals, myinvention embodies the concept of providing a piston assembly including a main piston and an auX- iliary piston (or its equivalent, such as a diaphragm) carried by the main piston and adapted to co-act with a plunger which isadapted'to initially transmit to the auxiliary piston a limited movement while the mainpiston remains" stationary and, when the limit of such movement V12 claims 01. 12s- 218) has been reached, to transmit movement to the main piston. The invention also provides means acting yieldingly between the auxiliary piston and the main piston to retract the auxiliary piston and plunger to their initial positions when the lpressure on the plunger is released. It is this retracting movement of the auxiliary piston which functions toapply suction which results in the withdrawal of fluid from the patients body into the syringe, and the range of limited movement of the auxiliary piston is just sufcient to provide an adequate withdrawal capacity to assure the passage of a body fluid through the hollow needle of the syringe back into the transparent barrel thereof. A further characteristic of the invention isthe balancing of the force of the yielding retracting means against the frictional grip of the cylinder upon the main piston so that the former cannot overcome the latterv and transmit movement to the main piston prior to the movement of the auxiliary piston to its "2 the cost of the ampule and the Stoppers be heldv at a minimum. Accordingly, a further object of. the invention is to provide a syringe embodying the features pointed out above in a construction that is relatively simple and inexpensive, suinciently so that the cylinder and piston portion of the syringe (the ampule) may be discarded after one full stroke of the piston.

A further object is to provide, as a renewable part of a syringe having the features discussed above, a medicament ampule having a novel stopper functioning' as a reversely operable piston. f

Other objects will become apparent in the ensuing specications and appended drawings in which: Fig. l is a longitudinal sectional view'through a syringe embodying the invention;

Fig. 2 is a sectional view through a portion of the same showing a different position of operation;

Fig. 3 is a sectional view through a portion of the syringe embodying a modified form of= theY invention;

Fig. 4 is a sectional view of the syringe of Fig. 3, showing a diierent position of operation, vand Fig. 5 is a szctional view of a piston embodying another modified form of the invention.

As an example o a preferred form in which the invention may be embodied, I have shown in Figs. l and 2 a syringe embodying a holder, indicated generally at and a medicament ampule, indicated generally at 1. rIhe holder 6 includes a barrel 8 having one end closed by an end wall 9 having a needle receiving neck I@ and having its opposite end open to receive the ampule 'I. To the open end of the barrel 3 is hinged, upon trunnions il, a yoke I2 having projecting nger grips I3 and a bearing Il in which is slidably mounted a plunger I5. The conventional hypodermic needle I6 is mounted in a cap E51 which is threaded onto the neck IE). The needle I6 is adapted to pierce the stopper il' (of soft rubber or equivalent material) which seals one endof the ampule ll. The foregoing features are conventional features of the type of syringe which L incorporates the ampule as an operating part thereof.

In such a conventional syringe, there is ordinarily a plain solid rubber stopper normally closing the end of the ampule opposite the stopper II. Instead of this plain rubber stopper, my invention provides an ampule having a stopper I8 which is cup shaped, including a cylindrical wall I9 that is slidable within the cylindrical barrel of the ampulei, and an end wall 2i which closes its outer extremity.

Since the stopper Ifunctions as a piston, and the barrel 2@ as a cylinder, in the a enabled syringe, they will hereinafter be referi d tc piston and cylinder respectively. The p1. is of a fairly soft, compressible material, suc as soft rubber, either natural orV synthetic, rubber substitute or other composition material having equivalent qualities of compressibilitx7 and tensile strength. The piston I8 is installed in the cylinder under some compression. setlicient to establish a tight hermetic seal adequate to prevent any escape o-f liquid and to protect the body of medicament 22 within the amp-ula against contamination; and suiiicient to establish a substantial frictional grip o-f the cylinder wall 20 upon the piston wall I9, to the extent hereinafter more fully pointed out.

, The end wall 2l of piston I8 is of suincient thinness to function as a diaphragm, movable axially with reference to piston wall I9 so to place the body of medicament 22 under pressure or suction when moved axially inwardly or outwardly as the case may be.

The invention provides means whereby the plunger I5 may first move the diaphragm 2i a limited distance inwardly while the wall is of piston I8 remains xed with relation to the cylinder 20.

In the form of the invention shown in Figs. 1 and 2, such means comprises a button 23 formed integrally with and projecting outwardly yfrom the diaphragm 2l, for engagement by the head 24 of plunger I5. A characteristic of the invention is a ratio between the diameters of piston I8 and head `2li such that the head 2li upon engaging the body of piston I8, directly transmit pressure to the piston I8. To this end, the diameter of head 2A is preferably substantially larger than the diameter of the cylindrical cavity 25 of piston I8, so that the peripheral porticn of head 24 may make direct contact with the outer end of cylindrical wall IS of the piston i3.

The height of button 23 determines the extent of limited movement which will be transmitted from head 24 to diaphragm 2l prior tc direct engagement of head 24 against piston i3. Fig. l shows the parts prior to the beginning of si. 1^ movement. Fig. 2 shows the parts at the end such movement. During this movment ci dia-- phragm 2l, the annular web of thin materiel oi" diaphragm ZI bridging between button .23 and wall I9, will bend and stretch inwardly until the outer face of button 23 is flush with the outer end of wall I9, wall it remaining staticnary throughout th-e movement. In order that this may be effected, the frictional grip of cylinder 2Q upon wall I9 is considerably greater than the yielding resistance of diaphragm 2i to being .i stretched to the position shown in Fig. 2.

When the pressure on plunger I5 is relaxed, the stretched diaphragm 2 i, attempting to relieve the tension therein, will return to its normally flat condition shown in Fig. l, pushing the plunger I5 back to the position of Fig. l. During the advancing movement ofthe diaphragm, a small quantity of the medicament is expelled through the needle i5. into the body of the patient. As the diaphragm recedes to its normal position, it will exert suction upon the of medicament 22, withdrawing from the body of the patient a corresponding quantity of fluid. If the needle has entered a blood vessel, there will be sufcient blood mingled with the rluid drawn back into the cylinder 26 to indicate that fact to the operator. In this ccnnection, it may be pointed out that the syringe holder is provided with window opening 26 through which the transparent cylinder EIS, and the contents therein, are visible.

To improve the hermetic seal between piston I8 and cylinder 25, the wall IS may be provided with an annular groove 2 defining at the inner end of the piston, an annular sealing flange 2Q.

In the form ci the invention shown in Figs. 3v and 4, the piston Ita has a diaphragm 2in that is relatively thin and flexible through-ont its entire area from wall Ilia to the center thereof, and instead of the button 23 integral with the diaphragm, I provide a button which is formed integrally with plunger head 2de. rShe diameter of button-23a is sufficiently smaller than that of piston cavity 25 so that the annular portion of diaphragm 2Ia extending between the periphery cf button 23a and wall lil may bend and stretch into cavity 25 until the shoulder 23 of head 24a makes contact with the body of piston I8a, as shown in Fig. 4. Aside from the fact that the button 23a is a part of piston Zlla instead of a part of diaphragm Zia, the operation is substantially the same as in the form of the invention shawn in Figs. l and 2'.

In the form of the invention shown in Fig. 5, the piston Ib, of soft rubber or equivalent material, has an internal cavity 25h communicating with medicament body 22 by a reduced neck opening 3G defined within a ange 3! that projects inwardly from the inner extremity of wall |919. Cavity 25h also communicates with a reduced opening 32 dened by a nange projectu ing inwardly from the outer extremity of wall |91). In the opening 32 is slidably mounted the auxiliary piston 2lb which has at its inner extremity an outwardly extending ange which substantially iits the VWall of cavity 25o. A coil spring 35, under compression between flange 3l. and flange 3I, urges piston 2lb outwardly, normally seating ilange 3d against harige 33 to establish a seal. Head Y24 (having a relation to wall 7,11 I9b similar to that of head 2li and wall I9v of Fig. 1) is adapted to engage piston 2 Ib` and move it inwardly until head v2li makes' direct contact with Wall |917. Normally, piston 2lb 'projects` innerwallof said cylinder to close one end thereof, and a yieldable auxiliary member positioned to be engaged by saidplunger and to be moved inwardly `with reference to said main bodymem-Y ber so as to functionas an auxiliary"piston. Vforj applying first pressure and then suction to the contents of said cylinder as the plunger is first pushed inwardly and tiien released, said main body member engaging' said cylinder wall with a grip suflicient to hold it stationary while said auxiliary member is moved by said plunger, said piston including means yieldingly opposing inf Ward movement of said auxiliary member and moving said auxiliary member back to its starting position when pressure on said plunger is'released. l

2. A syringe as defined in -claim l, Y wherein said plunger is so related to said main body member and auxiliary member as to transmit movement to said main body member after said auxiliary member has been moved a limited distance relative to said main body member.

3. A syringe as deiined in claim 1, wherein said pistonis cup shaped and of a material having the general characteristics of soft rubber, and has an annular wall of sulilcient thickness to engage the wall of said cylinder under compression sufficient to establish a grip upon said annular wall by said cylinder adequate to hold saidl has an annular wall of sufcient thickness to engage the wall of said cylinder under compression sufcient to establish a grip upon said annular wall by said cylinder adequate to hold said annular wall stationary while said resilient member is moved by said plunger; wherein said yieldable auxiliary member comprises a button projecting rearwardly from the rear end of said annular wall and a relatively thin annular web joining said button to the rear end of said annular wall with the button disposed at the axis of the Vin and engages the inner wall of said cylinder` piston, said annular web being adapted to bend Y gage the wall of said cylinder under compression suiiicient to establish a grip upon said annular `wall by said cylinder adequate to hold said vannular wall stationary while said resilient member is moved by said plunger; wherein said yieldable auxiliary member comprises a relatively thin end wall at theouter end of said piston, adapted to function"v as a diaphragm; and wherein said plunger has a-head provided with a reduced projecting end portion engageable with said diaphragm and a body portion of a diameter sufricient to directly engage the outer end of said annular wall, said body portion being set back from the end of said reduced end portion; whereby s'aid reduced end portion may distend said diaph-ragmr into the hollow interior of said piston while said annular wall remains stationary, whereby said diaphragm may return to a normal position upon release of pressure against said plunger, and :thereby exert suction against the contentsof said cylinder, and whereby said main body portionnof said plunger head may directly vengage said annular wall to advance said piston in said cylinder.

g 6. A syringe as defined in claim 1, wherein said piston is cup shaped and of a material having the general characteristics of soft rubber, and has an annular wall of sufficient thickness to engage thewall of said cylinder under compression sufiicient to establish a grip upon said annular wall by said cylinder adequate to hold said annular wall stationary while said auxiliary member is moved bysaid plunger, said annular wall having adjacent its inner end an annular outwardly opening groove defining at the inner end of said Apiston an annular ange engaging the wall of said cylinder and functioning as a sealing ring. 7.',A, syringe as defined in claim 1, wherein said main body member is annular and is received with a sealing engagement, and wherein said auxiliary member comprises a separate piston slidably mounted within said main body member andv projecting therefrom; andspring means'acting under compression between the inner end of said auxiliary piston and said main body member to normally urge said auxiliary piston outwardly, said main body member engaging the wall of said cylinder with suiiicient grip to hold it stationary 1 v:While said auxiliary piston is moved against the resistance of said spring means, said plunger having a head adapted to lirst engage the projecting end of said auxiliary piston, to move said auxiliary piston through a restricted range of movement and to then engage directly the outer end of said main body member to move said annular main body member within said cylinder.

8. A disposable component of a hypodermic syringe, consisting in a medicament ampule including a transparent barrel and a stopper closing one end thereof said barrel and stopper functioning respectively as piston and cylinder in the `assembled syringe, said stopper being of cup shape, including an annular main body member received in and having sealing engagement with the wall of said barrel and an auxiliary member mounted in the outer end of said main body member and movable relative thereto to function as an auxiliary piston, such plunger having means to engage said vauxiliary member to move the same inwardly with' reference to said main body Y member and having means to engage the latter after a limited amount of such inward movement lof said auxiliary member, said mainbodymember engaging the wall of said cylinder with suicient grip to hold the same stationary while said auxiliary member is moved inwardlyV by said plunger as aforesaid, said piston including means yieldingly resisting such inward movement of said Aauxiliary member and-returning said auxiliary member to its initial position when the pressure atea-365 on said plunger is released, whereby to establish suction upon the contents of said cylinder.

9. A component for a hypodermic syringe having a plunger, a piston and a cylinder in which said piston is operable, said component consisting in a medicament ampule including a barrel adapted to function as said cylinder and a stopper in one end of said barrel adapted to function as said piston, said stopper including an annular main body member received in and in sealing engagement with the wall of said barrel and an auxiliary member mounted in the outer end of said main body member and adapted to function as an auxiliary piston that is movable relative to said main body member while the latter remains fixed in said cylinder, and means yieldingly opposing such movement of said auxiliary member relative to said main body member andadapted to return said auxiliary member to its initial position when pressure thereagainst is released, said auxiliary member including a part adapted to be engaged yby said syringe plunger for limited inward movement thereof relative to said main body member, said main body member being related to said plunger and auxiliary member so as to receive movement from said plunger after said initial movement of said auxiliary member has been completed.

l0. A syringe component as dened in claim 9,

wherein said stopper is of cup shape and of material having characteristics of yieldability and elasticity comparable to those of soft rubber, including a relatively thick annular main body portion received in and engaging the wall of said cylinder and a relatively thin outer end wall having a thickened central portion in the form of a button projecting rearwardly from the rear end of said annular portion, so as to be engaged by the head of said plunger prior to engagement of said head against said annular portion, said relatively thin end wall functioning as a diaphram and being adapted to .bend and stretch inwardly to permit said button to be pressed into the space within said annular portion until its outer end is flush with the outer end of said annular portion, whereby said plunger head may directly engage said annular portion.

11. A syringe component as dened in claim 9, wherein said piston comprises a cup shaped one piece body of material having characteristics of yieldability and elasticity comparable to those of soft rubber, including a relatively thick annular portion received in and engaging under compression the wall of said barrel and a relatively thin outer end wall functioning as a diaphragm, and wherein the inner diameter of said annular p0rtion is so related to the end of said plunger .that the latter may rst distend said diaphragm inwardly into the space within said annular portion and then transmit movement to the outer end of said annular wall to move the latter in said cylinder.

12. A syringe component as dened in claim 9, wherein said piston includes an annular body portion received in and in sealing engagement with the wall ofsaid barrel, and an auxiliary piston slidably mounted in said annular body portion, having an outer end projecting rearwardly from the outer end of said annular body portion for engagement by the plunger of said syringe, and including yielding means opposing the inward movement of said auxiliary piston and adapted to return the same to its starting position when the pressure of said plunger thereagainst is relaxed, said'annular body portion and auxiliary piston being so related to said plunger that said auxiliary piston `will vbe rst moved a limited distance inwardly with relation to said annular body portion and said plunger will then transmit movement to said annular body portion for moving the same in said barrel.

NIELS BJ ORN JORGENSEN.

REFERENCES CHED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,704,924 Rehm Mar. 12, 1929 1,704,936 Cook Mar. 12, 1929 2,268,994 Smith Jan. 6, 1942

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