Title:
Hypodermic injector
United States Patent 2380534


Abstract:
My present invention relates to a hypodermic injector which does not require the use of a hollow needle to accomplish injection, this application being a division of my copending application, Serial No. 390,598, filed April 26, 1941, now Patent No. 2,322,245, issued on June 22, 1943. One object...



Inventors:
Lockhart, Marshall L.
Application Number:
US47918343A
Publication Date:
07/31/1945
Filing Date:
03/15/1943
Assignee:
Lockhart, Marshall L.
Primary Class:
Other Classes:
222/340
International Classes:
A61M5/30
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Description:

My present invention relates to a hypodermic injector which does not require the use of a hollow needle to accomplish injection, this application being a division of my copending application, Serial No. 390,598, filed April 26, 1941, now Patent No. 2,322,245, issued on June 22, 1943.

One object of the present, invention is to provide hypodermic injector mechanism of simple, durable and inexpensive construction.

Another object is to provide a hypodermic injector which eliminates the necessity of using a hollow needle and the usual type of syringe in conjunction therewith, yet which effectively injects liquid or medicants, such as novocain, antiseptic and the like into animal tissue, leaving only a microscopic scratch on the surface of the tissue.

More particularly, it is my object to provide a hypodermic injector containing an ampule in which the liquid to be injected is enclosed, and means capable of exerting a predetermined high pressure within the ampule '(which exceeds approximately 30 atmospheres, or 400 pounds per square inch) by suitable means, such as a spring or compressed air biased plunger to displace the liquid from the ampule through a discharge orifice, such orifice being so minute that the liquid is vaporized or atomized so finely that it can pass through animal tissue, leaving a hole therethrough large enough to be seen only through a microscope, thus eliminating the risk of infection, fright, pain, etc., of the usual hypodermic needle, the only feeling of the patient being the sensation of a slight breeze blowing against the skin as the injection takes place.

Another object is to provide a hypodermic injector wherein a predetermined and substantially instantaneous build-up of pressure may be secured for the purpose of predetermining the force of ejection of the liquid, thus securing precision control of dosage and administration of the liquid to the hypodermic location desired.

Still a further object is to provide a hypodermic injector using a compressed spring, compressed air or the like as motive power for driving a plunger against a follower with an impact blow, whereby the follower displaces the liquid from the ampule of the injector, and to further provide such a device which is suitable from a commercial standpoint, and makes it possible to provide a physician with different quantities of liquid to be injected, and a readily selectable supply of injections to suit his particular needs.

Finally, it is an object of my present invention to make an injector mechanism which is spring or compressed air operated, which has but few parts, and these parts so arranged as to facilitate their assembly with relation to each other to form the completed injector mechanism.

With these and other objects in view, my invention consists in the combination, construction and arrangement of the various parts of my device whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed r out in my claims and illustrated in the accompanying drawing, in which: Figure 1 is a longitudinal sectional view through one form of my invention, showing a spring to effect the build-up of pressure necessary to force the hypodermic liquid from the injector with injection force, the spring being shown in contracted position, as when the device is "cocked"; Figure 2 is a similar sectional view of Figure 1, showing the spring released and having effected discharge of the hypodermic liquid; and Figure 3 is a similar sectional view of a modified form wherein compressed air is used as the propelling force.

On the accompanying drawing, I have used the reference numeral 91 to indicate a cylindrical ampule containing hypodermic liquid 92 to be injected. One end of the ampule 91 is provided with a discharge orifice 93 which is of very minute size. I have found that between .001 and .006 inch are suitable sizes for the purpose, although other sizes, of course, can be used to suit the particular requirements of the -injection to be made. The size of the discharge orifice 93 is much smaller than the area within the cylinder 91, which area is illustrated about full size in Figure 1, whereas the orifice 93 is necessarily enlarged in order to show up on the drawing.

In Figures 1 and 2. I illustrate an impact -type of mechanism for accomplishing injection. A holder 90 may be provided for the ampule 91 in which the hypodermic liquid 92 is enclosed. The holder 90 is removably positioned with relation to a cylinder 95, in which a plunger 96 is slidably mounted. The plunger has a reduced portion 91 and a head 98. A stem 99 extends from the head 98 through a cap nut 100 in the outer end of the cylinder 95. An actuating knob 101 is mounted on the stem 99, and a spring 102 is interposed between the plunger head 98 and the cap nut 100.

A latch pin 103 is slidably mounted transversely in the cylinder 95, and is biased to the latching position shown in Figure 1 by a spring 104.

The plunger 96 and its reduced end 91 are adapted to move through a bore 105 in the latch pin 103.

In the operation of the injector shown in Figures 1 and 2, the knob 101 may be grasped and pulled outwardly from the position of Figure 2 to the position of Figure 1. The spring 104 will cause the latch pin 103 to assume the position illustrated in Figure 1, serving as a stop for the shoulder of the plunger 96, where it is cut down to form the reduced part 91.

Whenever the latch pin 103 is pushed inwardly, as to the position of Figure 2, the plunger 91 will be released as soon as the opening 105 reg. isters with it, and the spring 102 will expand thereby causing the reduced end 97 to strike thi follower 94 and then force it forwardly in th< bore of the container of the ampule 91. This wil cause the hypodermic liquid 92 to be displacec through the orifice 93 with sufficient force to accomplish hypodermic injection. Such force, as already mentioned, must be in excess of 40( pounds per square inch, produced on the plunger 94, and. consequently, on the liquid 93, before injection to a hypodermic position can be successfully accomplished.

In Figure 3 there are many parts similar tc those described in Figures 1 and 2, and they bear the same reference numerals. Other parts involved will now be described.

The plunger 98 carries a piston 106 slidable in a cylinder 952 which is larger than the one shown in Figure 1. Means is provided for building up a charge of highly compressed air in the cylinder 953, and may consist of a second piston 107, a piston rod 108 therefor, and a rod 109 for operating the piston 107. The knob 109 has a threaded part 118 adapted to coact with threads 1i! of the cylinder 95a.

In the operation of the device shown in Figure 3, the knob 109 is unscrewed at 10-- 92, and the piston 107 pulled outwardly, which also pulls the piston 106 outwardly, causing it to be locked, as illustrated. The piston 101 is then pushed inwardly and locked in its inward position by engaging the threads 110 with the threads 112. This confines a charge of highly compressed air between the pistons 106 and 107, whereby, upon depression of the latch pin 103, the plunger 96 is released so that the air acting on the piston 106 will force the plunger forwardly and result in the reduced portion 97 of the plunger striking the follower and propelling it forwardly.

With either type of injection mechanism, the operation occurring after the latch piit 103 is released is the creation of a pressure of thou-sands of pounds per square inch for displacing the liquid 92 along the cylindrical bore of the ampule 91, the time of displacement varying over a period, such as a fraction of a second, because Of the small size of the orifice I I-preventing any possibility of instantaneous discharge of the liquid. The higher the pressure, of course, the shorter will be the displacement time.

In my mention of thousands of pounds per square inch pressure being created, I do not wish to infer that pressures below a thousand pounds per square inch are unsuitable. ,I have found that for certain types of hypodermic injection, pressures in excess of 30 atmospheres, or about 400 pounds per square inch, are sufficient. Pressures below this level, however, are below the level of utility, as they do not produce the desired penetration of the liquid through the skin, with any assura-nce of accurate control of dosage and of administration.

With a pressure of 10,000 pounds per square inch. liquid displacement through an orifice of .004 inch can penetrate most any animal tissue to a depth of 4 inches. Accordingly, if it is desirable to penetrate to a less depth, less pressure is reauired.

I am able to secure a relatively great pressure in pounds per square inch with a relatively light spring 102, because the plunger end 97 is relatively small in area. The one shown on the drawing is approximately s/," in diameter, which I makes the area about 1/o of a square inch. It is therefore obvious that a pressure of 25 pounds against the plunger 96 will produce a pressure of S 1,000 pounds per square inch for acting upon the S5 follower 94. The spring 102, however, may be l even lighter than this to produce a pressure of 1 1,000 pounds per square inch, because, in addition to the spring, the plunger strikes the folS lower with impact, and, at the moment of imS10 pact, the pressure is greater than that produced by the spring alone.

Likewise, in the form shown in Figure 3, the pressure is greater, because of impact, than that produced by the compressed air alone, and this I 15 initial build-up (almost instantaneously) of the pressure is sufficient to cause the liquid to be expelled in a very fine stream and with sufficient force to cause it to penetrate through the skin of the patient being treated. The penetration produces a minute opening through which the remaining liquid can follow without as much pressure as is necessary for the initial penetration by the liquid.

S My hypodermic injector eliminates the necessity of mechanically puncturing the tissue in order to inject a medicant into it. It also eliminates the pain and fright attendant on an injection of the needle type.

The method involved comprises the steps of enclosing the fluid to be hypodermically injected in such manner that a movable wall of the container for the liquid may be relatively quickly forced into the container by the force of a spring or other biasing means assisted by impact, so that the result is expulsion of the liquid in a streamcontrolled form. Claims covering the method will be found in my Patent No. 2,322,245, hereinbefore mentioned.

The size of the orifice and the time of liquid discharge can be so regulated that the injector can be used for various purposes. For ordinary hypodermic injections, a minimum period of time for Injection is desirable, provided the injector meets other necessary requirements. In other cases, such as when it is desirable for-a dentist to spray the entire gums of a patient with a local anaesthetic, the time of discharge can be extended over a time period of three or four seconds, which would give the dentist sufficient time to spray the injecting liquid over the entire surface of the gums by moving the injector relative to the gums while injection is taking place.

One of the most important results of the use of o" my hypodermic Injector Is the elimination of the possibility of infection from unsterile needles, and from openings formed in the tissue which provide an entrance for bacteria.

It is thus obvious that a predetermined high .* pressure may be secured to effect a predetermined force of ejection of the liquid and a resultant control of dosage and administration.

Unsuccessful attempts have heretofore been made to accomplish hypodermic injection. I ;.' have found it necessary to provide an injector capable of exerting at least 400 pounds per square inch on the liquid in order to force it from the discharge orifice 93 with sufficient force to remain in the form of a stream of liquid which passes through the epidermis without merely striking it and being deflected by it.

When a force of this magnitude, or greater, is produced by impact and/or by spring or compressed air or the like, or by any other means, 7' then injection to a hypodermic position is possible with assured precision in dosage. By the use of a fine orifice of a few thousandths of an inch, such high pressure exerted on the liquid confines it to a fine, stream-like form, so that it all passes through the skin to the tissue therebeneath without stray droplets at the edges of the stream being deflected by the skin and thereby failing to enter to the desired subcutaneous position. The force of ejection may be predetermined by the proper selection of springs and de- 1 sign of the structural elements of the injector, as well as many other variable factors.

Various modifications, such as those illustrated, and others, can be made in my' hypodermic injector without departing from the real spirit 1 and purpose of my invention. It is my intention, therefore, to cover by my claims any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope. 2 I claim as my invention: 1. A hypodermic injector for use with an ampule having a blunt end with a minute discharge orifice therein, a holder having provision at one end thereof for removably and fixedly 2 holding said ampule in such a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be filled with liquid to be injected into said tissue and a follower in said bore, said holder having a plunger arrangedto strike said follower and impart thereto a sharp blow, energy-storing means for propelling said plunger to strike said follower, manually operated provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storing means in cocked position, said latch including a manually operable member extending transversely of said holder and projecting laterally therefrom, said latch upon actuation of said manually operable member being adapted to suddenly release said plunger so as to transmit energy stored in said energy-storing means to said follower for ejecting said liquid under high pressure from said orifice.

2. A hypodermic injector for use with an ampule having a blunt end with a minute discharge orifice therein, a holder having provision at one end thereof for removably and fixedly holding said ampule in such a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be filled with liquid to be injected into said tissue and a follower in said bore, said holder having a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storing means for propelling said plunger to strike said follower, manually operated provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storing means in cocked position, said latch including a manually operable member extending transversely of said holder and projecting laterally therefrom, said latch upon actuation of said manually operable member being adapted to suddenly release said plunger so as to transmit energy stored in said energy-storing means to said follower for ejecting said liquid under high pressure from said orifice, the mass of said plunger being many times greaterlthan that of said liquid and follower.

3. A hypodermic Injector for use with an ampule having a blunt end with a minute discharge orifice therein, said holder having provision at one end thereof for removably and fixedly holding - said ampule in such a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection is to be made, said ampule having a bore adapted to be filled with liquid to be injected into said 0 tissue and a follower in said bore, said holder having a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storing means for propelling said plunger to strike said follower, manually operated provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storink means in cocked position, said latch including a manually operable member to release said plunger so as to transmit energy .o stored in said energy-storing means to said follower for ejecting said liquid under high pressure from said orifice.

4. A hypodermic injector for use with an ampule having a blunt end with a minute discharge !5 orifice therein, said holder having provision at one end thereof for removably and fixedly holding said ampule in such a way that the blunt end thereof may be operatively positioned adjacent to and externally of tissue into which an injection O0 is to be made, said ampule having a bore adapted to be filled with liquid to be injected into said tissue and a follower in said bore, said holder having a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storing 35 means for propelling said plunger to strike said follower, manually operated provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storing means in cocked position, said t0 latch including a manually operable member to release said plunger so as to transmit energy stored in said energy-storing means to said follower for ejecting said liquid under high pressure from said orifice, the mass of said plunger being 15 many times greater than that of said liquid and follower.

5. A hypodermic injector comprising an ampule having a blunt end with a minute discharge orifice therein of the order of .001 inches, a holder 50 having provision at one end thereof for removably and fixedly holding said ampule in such a way that the blunt end thereof may be operatively positioned against and externally of tissue into which an injection is to be made, said ampule 55 having a bore adapted to be filled with liquid to be injected into said tissue and a follower in said bore, said holder haviplng a plunger arranged to strike said follower and impart thereto a sharp blow, energy-storing means fori propelling said 60 plunger to strike said follower, provisions by means of which said energy-storing means may be charged, a latch for holding said plunger and energy-storing means in cocked position, a manually operable member adapted suddenly to release (5 said plunger so as to transmit energy stored in said energy-storing means to said follower for ejecting a stream of said liquid from said orfice under a pressure sufficiently high to penetrate 70 said tissue, the mass of said plunger being many times greater than that of said liquid and follower.

MIARSHALL L. LOCKHART.