US3461867A - Needleless injector - Google Patents

Description

Aug. 19, 1969 A, zlMMET ETAL NEEDLELESS INJEcToR Filed March 14, 1966 ARTHUR 1.. zlMMET By R|cHARD H. HUBBARD ATTORNEY United States Patent O 3,461,867 NEEDLELIESS INJECTOR Arthur L. Zimmet, New York, N.Y., and Richard H. Hubbard, Clifton Forge, Va., assignors to Mizzy, inc., Clifton Forge, Va.. a corporation of New York Filed Mar. 14, 1966, Ser. No. 534,187 lint. Cl. Alm 3.7/

US. Cl. 128--173 3 Claims ABSTRACT 0F THE DISCLGSURE A needleless injector, and more particularly an improved device of the type described, which includes an elongated body having a front and rear portion with the front portion having an elongated recess within the confines thereof to receive an ampule that defines a liquid reservoir. The reservoir is in communication with a pressure chamber which is charged by the retraction of a piston associated therewith and which is discharged upon rapid advance of such piston, through a discharge passageway at the end of the front portion which forms an obtuse angle with respect to said body.

More particularly, this invention relates to an improved injector of the type wherein an innoculant is discharged at high velocity through a jet orifice, to penetrate the tissues of the patient.

The invention, in its more particular phases, relates to an improved injector wherein an innoculant is stored in a readily replaceable ampule or container, which may be applied to the device, forming a reservoir therefor, the device including means for withdrawing from the reservoir selected quantities of innoculant, the same being stored at an intermediate chamber directly before it is dispensed.

The invention further relates to an improved injector apparatus incorporating a novel valving arrangement interposed between the discharge orifice and the reservoir, whereby contamination of the contents is avoided.

The invention further relates to an improved apparatus of the type described wherein the quantity and velocity of innoculant dispensed may be readily controlled, and wherein it is assured that the entire quantity of innoculant is expressed under sufficient pressure to enter the tissues to be treated.

Accordingly, it is an object of the invention to provide an improved needleless injector.

To attain these objects and such further objects as may appear herein or be hereinafter pointed out, reference is made to the accompanying drawings, forming a part hereof, in which:

FIG. l is a plan view of an injector device in accordance with the invention;

FIG. 2 is a section taken on line 2-2 of FIG. l;

FIG. 3 is a magnilied, fragmentary section showing the position of the parts when the same are partially cocked; and

FIG. 4 is a further magnified section of the discharge assembly, showing the position of the parts during the fluid expressing stroke.

In accordance with the invention, 1t) is an injector mechanism comprising a body 11 having a first axially extending bore '12. The bore includes a wide diameter portion 13 and an axially extended narrow diameter portion or discharge chamber 14. The body includes a separable reservoir which, in the illustrated embodiment, comprises a disposable ampule 1S, removably insertible into a holder defined by the body portion. The ampule is formed of a glass cylinder 16 provided witha fixed, penetrable seal 17 at one end, the seal preferably being of ice elastomeric composition. A movable seal 18 is disposed in the other end of the cylinder, it being understood that the seal 1S is shiftable axially within the ampule. The ampule is mountable within a recess 19 defined in the body portion, a hollow needle 20, extending axially from the body portion and providing an exit means for the ampule contents, being insertble through 'the seal 17.

The inner terminal end 21 of the needle 2@ defines a frusto-conical seat, a ball 22 being normally pressed by spring 23 into contact with the seat. A duct 24 extends from the check valve dened by the ball 22 and seat 21, the duct leading into the discharge chamber 14. A passage 25 leads from the discharge chamber v14 to the ejector head, referred to generally as 26.

The liuid within the ampule 15 is maintained under pressure by a spring pressed ram 27, having a ram head 28 of a size which will permit said head to enter into the cylinder 16 and follow the movable seal 1S as fluid is progressively discharged from the ampule.

The ram 27 includes a mounting knob 29, having an offset locking pin 30 and an inwardly extending spring guide 31. The ram spring 32 is sleeved over the guide 31, the forward end of the spring pressing against an internal plug 33 extending rearwardly from the head 28 of the ram.

The body 11 of the injector device is provided with a bayonet slot 34 adjacent the rear end 35 thereof to receive the pin 3() to retain the ram 27 in position.

From the foregoing it will be understood that an ampule may be loaded into the recess 19 by pressing the same axially over the needle 2t? so that the needle penetrates the seal 17, seating the ampule within the recess. Thereafter, the ram 27 is inserted endwise behind the ampule, the retainer knob 29 being pressed inwardly to permit the locking pin 3i) to enter bayonet slot 34 in the body p0rtion, the knob 29 being thereafter twisted to cause the pin 30 to enter the bayonet slot 34 and prevent outward movement of the knob. The ram spring 32 will be compressed by the aforesaid loading action, causing the ram head 28 to be urged tightly against the rear seal 18 of the ampule.

A piston assembly is disposed in the axially extending bore 12, the assembly including a piston head 40 and a plunger assembly 41. The piston head 40 extends slidably and sealingly within the narrow bore portion 14, the head 40 defining a rearwardmost movable boundary of the discharge chamber 14.

The piston head 40 is formed on the forward end of a piston rod Imember 42, the rear end of which comprises a threaded shank 43. A release collar 44 is threaded over the shank 43 and includes a forwardly directed annular shoulder 4S. The collar, in addition, in the portion surrounding the shank 43, defines a rearwardly directed spring support shoulder 46. The large diameter bore portion 13 adjacent the outer end 35 of the body portion incorporates an internally threaded portion *47, an annular spring compression collar 48 being threaded into the portion 47 of the bore 13.

A piston actuator spring 49 is compressed between the shoulder 46 of collar 44 and a forwardly directed shoulder 50 of compression collar 48. It will be understood that by forwardly or rearwardly Amoving the compression collar `48 within the body portion, the degree of compression applied to the spring 49 may be varied.

A spring adjustment member 51 is seated in the end of the bore 13, the adjustment member incorporating spaced drive teeth 52 which mesh with recesses 53 formed in the adjustment collar 48. Thus, it will be seen that rotation of the adjustment member 51 will communicate rotary movement to the collar 48, while still permitting relative axial movement between these parts.

A stroke adjuster nut 54 is threaded over the outer portion 55 of the piston shank 43, the nut 54 including a forwardly directed stop shoulder portion S6. The spring adjustment member 51 includes a rearwardly directed complemental stop shoulder 57.

From the foregoing, it will be seen that the forwardmost position which may be reached by the piston is limited by the engagement of the complemental stop shoulders 56, 57 of the nut 54 and adjustment member 51 respectively. Optionally, the outermost surface of the nut 54 may be marked with indexing numerals or the like, to provide a ready means of identifying the quantity of fiuid which will be expressed in any stroke of the piston.

A cooking lever 60 is pivotally mounted on a pin 61 carried by the body portion. The cocking lever includes spaced claw members 62, 62 which are pivoted into the interior of the body portion through access slots 63 formed in said body portion, when the lever is lifted to the position shown in FIG. 3. As best shown in FIG. 3, lifting of the lever causes the claws 62 to bear against shoulder 45, causing the piston shank, rod and head to be shifted rearwardly or to the right, as shown in the drawings.

A detent trigger 64 is pivotally mounted on the body portion, the forward end 65 of the trigger being normally pressed away from the body portion by a leaf spring 66. A detent shoulder 67 engages the shoulder 45 of the release collar 44 when the collar has been shifted sufficiently rearwardly, it being understood that the trigger will maintain the collar and associated piston mechanism in the rearward position until the trigger is tripped by pressing the end 65 toward the body portion of the injector against the force of spring 66.

As best seen in FIG. 4, the ejector head 26 includes a jet orifice 70. The orifice 70 is formed in an insert member 71 threaded into the head 26, the portions 72 of the insert member immediately rearward of the orifice 70 defining a discharge valve seat. A valve stem 73 of generally cylindrical conformation is movably mounted within a bore '74 in the discharge head 26. The stem 73 includes a reduced cylindrical tail portion 75, about which is concentrically mounted a compression spring 76. A spring seat 77, threaded into the end of the head 26 remote from the orifice 70, bears against one end of the compression spring 76, causing the opposite end of said spring to urge the tapered end 78 tightly and sealingly against the valve seat 72, `as shown in FIG. 2.

The passage 25 leading from the discharge chamber to the head 26 communicates with an oversize cylindrical recess 79 formed in the insert 71, thus permitting the flow of fiuid into contact with those portions of the valve stem which lie outwardly of the points of engagement between the valve stem and the valve seat. It will thus be seen that sufficient pressure in the area 79 will tend tourge the valve stem 73 rearwardly to clear the valve stem 73 from the valve seat 72.

OPERATION An ampule 16 is loaded into the device in the manner previously set forth. The cocking lever is withdrawn as shown in FIG. 3, shifting piston rod 42 and piston head 40 rearwardly within the bore 14. The rearward movement of the piston creates a vacuum in the discharge chamber 14, and the cumulative result of this sub-atmospheric pressure, plus the pressure applied to the ampule by the ram 27 causes a fiuid flow through the needle 2G and the duct 24 into the discharge chamber 14. The pressure required to unseat the valve stem 73 is greater than that required to unseat the ball valve 22 and, thus, the stem remains in head-sealing position throughout the cocking operation.

With the plunger in cocked position, the trigger 54 may be depressed, causing the piston assembly to snap forwardly and creating an extremely high pressure head within the discharge chamber 14. Such pressure can be relieved only by unseating the valve stem 73 from the valve seat 72 since pressure in such chamber tends more firmly to seat the ball 22 in the seat 21. When the pressure in the chamber 14 reaches a sufficiently high value, the stem 73 will be shifted rearwardly against the pressure of spring 76, causing iiuid in the chamber 14 to be violently expressed through the jet orifice 70. When the pressure is relieved at the end of the forward movement of piston head 40, the spring 76 will immediately cause the stem 73 to be shifted against its seat, preventing any back fiow or contamination of the contents of the injector.

As previously noted, the forward movement of piston head 40 and hence the quantity of fiuid expelled may be controlled by rotation of nut 54. In addition, the ejection pressure may be varied by modifying the compression of spring 49. This is readily accomplished by rotation of spring adjustment member 51 which in turn controls the position of spring compression collar 48.

A highly desirable feature of the device lies in the employment of the relief valve (72, 73) in the head 26. 'Ihe value of such valve will be readily appreciated when the device is contrasted with units heretofore known wherein the reduced size of the discharge orifice provides the sole limitation to the flow of liquid `after release of the piston. In such devices, it is possible for the initially discharged portions of the liquid to be expelled at an undesirably low pressure, and for the desired tissue penetrating pressure to be attained only at an intermediate portion of the stroke of the piston. Under such circumstances, it will be readily recognized that the initially emerging portions of the fluid may not penetrate the tissue. Thus, in such known devices, the effective dosage, namely, the dosage expressed at a force sufficient to penetrate, will bear no necessary relation to the total quantity of fluid expressed.

In contrast, the device of the present invention, by providing an exit valve directly adjacent the jet orifice, assures that only fluid sufiiciently compressed to cause unseating of the valve stem will emerge from the orifice so that there will be a high velocity at the end of the injection as well as at the beginning. Therefore, all emerging fluids are assured to have attained a predictably high tissue penetrating velocity. Furthermore, by reason of the exit valve, the injector will have a dripless cut-off and in addition, the instrument will be sealed from the atmosphere insuring against any back flow or contamination reaching the remaining injectable material.

It has been further found that by providing a valve stern which, in moving to the opening position shifts in a direction opposite to the direction of fluid movement, a sudden initial surge of high velocity is obtained, which assures particularly effective application of the uid.

From the foregoing, it will be recognized that the injector apparatus is simple to use, efficient in operation and may be readily disassembled for sterilization. Furthermore, the quantity of uid which is expressed in each stroke of the piston may be accurately determined and, by reason of the novel construction of the device, the expelled fluids are effectively and predictably administered, as contrasted with injectors heretofore known.

As many changes could be made in the above construction, and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown yin the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. A needleless injector of the piston actuated type comprising `a body having a front portion and a rear portion, the front portion being elongated and of smaller cross section than said rear portion, the front portion of said body having an elongated cavity within the confines thereof releasably to receive a variable volume ampule defining L.. J a liquid reservoir for storing iiuid, holding means for removably grip-ping said ampule, spring means shiftable into said ampule for pressurizing the contents thereof, said ampule and said spring means being within the confines of said body, a duct leading from said reservoir, oneway valve means in said duct for blocking luid flow through said duct toward said reservoir and permitting tlow out of said reservoir, an axial passageway dening a discharge chamber, said duct communicating with said passageway, an axially movable plunger shiftable in said passageway and defining a movable boundary of said chamber for selectively increasing and decreasing the volurne of said chamber, said plunger being in parallel longitudinal relationship with respect to said ampule, spring means biased between a spring seat on said body and said plunger urging said plunger toward said chamber, a stop shoulder on said body portion, an adjustment member axially movably mounted on said plunger, said last named member being disposed in the path of movement of said shoulder as said plunger moves axially toward said chamber, said shoulder and adjustment member, in the engaging position thereof, blocking further movement of said plunger into said chamber, whereby the axially adjusted position of said member with respect to said plunger determines the stroke of said plunger, a discharge head mounted at the free end of said front portion, said discharge head having a discharge passageway with a jet orifice at its outer end, said passageway forming an obtuse angle with respect to said body portion and pressure sensitive valve means interposed between and normally isolating said orifice from said chamber, said valve means being effective to provide communication between said orifice and chamber responsive to pressures in said charnber of a predetermined magnitude.

2. A device in accordance with claim 1 wherein the terminal end of said duct remote from said passageway comprises a hollow needle insertible into the interior of said ampule.

3. A device in accordance Iwith claim 1 wherein said spring seat is axially movably mounted relative to said body, thereby to vary the compressive force exerted by said spring means against said plunger in accordance with the axially adjusted position of said spring seat with respect to said body.

References Cited UNITED STATES PATENTS 9/1963 Morrow et al. 128-218 7/1964 lsmach 12S-173

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