US2687725A - Hypodermic injector - Google Patents

Description

fl- 1954 s. N. HEIN, JR

HYFODERMIC INJECTOR 2 Sheets-Sheet 1 Filed Aug. 23, 1951 a av w M Q a Q Q m g amv Q mum's INVENTOR. freq/Zia AZ #0111, 1/9. BY

Patented Aug. 31, 1954 UNITED STATES PATENT OFFICE 2,687,725 HYPODERMIC INJECTOR George N. Hein, Jr., San Carlos, Calif. Application August 23, 1951, Serial No. 243,241

8 Claims.

This invention relates to a structurally and functionally improved hypodermic injector and in its more specific aspects aims to provide an apparatus by means of which medicament may be injected without the use of a skin-piercing needle.

It is a primary object of the invention to furnish a mechanism which will be compact and readily operated; the apparatus being capable of being controlled in a manner such that the medicament will be ejected at pre-determined and desired pressures.

A further object is that of providing a mechanism of this character which will include relatively few parts each individually simple and rugged in construction such parts being susceptible of ready assemblage to furnish a unitary mechanism operating over long periods of time with freedom from all difficulties.

With these and other objects in mind reference is had to the attached sheets of drawings illustrating practical embodiments of the invention and in which:

Fig. l is a sectional side view of an injector;

Fig. 2 is a similar view thereof but showing the parts of the apparatus in positions different from that illustrated in Fig. 1;

Fig. 3 is an end view of the unit;

Fig. 4 is a transverse view along the line 4-4 in the direction of the arrows as indicated in Fig; 2;

Fig. 5 is a transverse view generally along the line 5-5 in the direction of the arrows as indicated in Fig. 1 and with certain of the parts eliminated;

Fig. 6 is a sectional View similar to Figs. 1 and 2 but showing an alternative form of apparatus; such view being taken along the line 6-6 in the direction of the arrows as indicated in Fig. 7;

Fig. 7 is a side elevation of the apparatus as shown in Fig. 6;

Fig. 8 is a transverse sectional view taken along the line 8-8 and in the direction of the arrows as indicated in Fig. 6; and

Fig. 9 is a fragmentary enlarged sectional side view showing an alternative form of regulator assembly.

As previously brought out the present invention relates primarily to a mechanism for the hypodermic injection of medicaments without it being necessary to employ a skin-piercing needle. Mechanisms of this type are generally identified as velocity injection devices. They include medicament chambers which ordinarily receive the solution to be injected enclosed in an ampule structure rather than receiving the medicament directly into the chamber of the injector. With this in mind, such preferred arrangement has been illustrated in the present drawings.

Thus in these views the numeral I0 indicates the casing of the device in the form of a tube. Secured to the forward end of the latter by, for example, screw threads is a nose piece H. In turn attached to this unit by means of a quickreleasable coupling is a loading cap l2. The latter defines one end of the medicament chamber proper. The outer end of cap I2 is formed with a preferably central orifice through which the tip H! of a nozzle extends. The bore of this nozzle adjacent at least its outer end is restricted so as to define a minute orifice. That orifice may have a diameter of from .004" to .015. In any event it will define a jet of liquid of such fineness that if the jet is projected with sufiicient velocity it will penetrate the epidermis without it being necessary to employ a skin-piercing needle.

The medicament-containing chamber is, as shown, defined by an ampule provided by a section of glass tubing I4. Adjacent its rear end that ampule mounts a piston type stopper l 5. At its forward end it mounts a stopper l6 which is formed with a bore initially closed by a displaceable sealing unit l1 conveniently in the form of a sphere. The end of nozzle [3 is extended in a rearward direction as indicated at l8. Accordingly this end may pass into the bore of stopper I6 and contact the seal I! which it will serve to displace. With such displacement communication will be established between the interior of the ampule and the bore of the nozzle. A flange H! extends outwardly from the latter and intervenes the stopper l6 and the adjacent inner face of cap l2. So disposed all parts will be properly maintained against undesired movements with respect to each other when the loading cap is once seated.

Within tube [0 a cup-shaped member 20 is mounted for sliding movement. The base of this member is furnished with a stem 2| which is bored and provided with a seal of any desired type such as a plug 22. With this seal removed the interior of cup 20 may be charged with fluid under pressure. Conveniently the fluid will be nitrogen and the pressure may have any desired value above that necessary to penetrate the epidermis. Such a pressure may, for example, be somewhere between 1,000 and 2,000 pounds to the square inch. In any event when cup 20 is projected stem 23 will be similarly projected and therefore pass into the bore of which forms a part of nose piece ll. Seal 22 will normally prevent any escape of the fluid under pressure.

In the embodiment illustrated the ampule is provided with which might be termed a tail piece in the form of a stem 23. Conveniently that stem is formed of parafiin or other fluid material in the sense that under pressure it will deform. Loading cap i2 receives a liner 24 which has an internalbore slightly in excess of that of ampule M. In common with the stoppers at the ends of the ampule this liner is formed of rubber or cause a projection of stopper l5, but will also displace in a manner such that it exerts pressure against the rear edge of liner 24. This thrust will result in an axial compression of the liner and a consequent constriction of its bore. Therefore, the face of that bore will move into supporting relationship with the outer face of tube l5. Accordingly that tube will be supported against bursting even although its interior is subjected to high pressure. As will finally be noted with reference to this portion of the structure the liner is provided with an outstanding flange portion 25 which bears within a groove formed in loading cap IE to prevent a displacement of the liner from that cap.

With a view to providing a structure suitable for cooking the apparatus that end of the unit which is opposite the medicament chamber supports a disk or hub 25. Such support is achieved by securing this unit against movement with respect to a threaded shaft 26. In accordance with the present teachings it is preferred to rotate the 'disk or hub and its shaft by means of a handle structure. That structure includes a pair of substantially semi-circular links 21 pivotally connected to each other as at 28. The end of what might be termed the innermost link is pivotally connected as at 29 to the outer portion of the hub or disk assembly 25'. The outer end of the second link presents a handle 3|). When rotated in a clockwise direction as viewed in Fig. 2, abutting surfaces between the links 2! and the innermost link and the hub cooperate so that the links in effect form a crank handle to the outer end of which the knob 30 is secured. Under these circumstances by grasping this handle and rotating it in the direction stated the hub assembly or disk will turn carrying with it the shaft 26. When knob at is moved in a counterclockwise direction as viewed in Fig. 2, then the links will pivot around points 29 and 28 so that a compact structure is presented.

As shown in Figs. 1 and 3 tube Ml extends rearwardly and is provided with a shoulder portion 3| the forward face of which is preferably inclined. To the rear of this point the sleeve is secured by screw threads or in any other desirable manner to a head portion 32. That head portion is continued rearwardly and provided with a central opening within which there is fixed against movement a nut 33. The threads of. the latter engage the threads of shaft 26. The rear end of head 32 is encircled by a collar 34. A flange portion 35 forming a part of the hub or disk 25 has telescopic relationship with respect to the collar. The face of the collar 3d bears indicia in the form of a series of graduations with which the forward edge of flange Eli registers in order to indicate the degree of overlapping of that flange with respect to the collar. Based upon the amount of such overlap the shaft 26 will be projected or retracted to a greater or lesser extent.

As shown, shaft 25 is formed with a normally sealed bore 36 through which lubricant passes. The forward end of this shaft conveniently terminates in a headed portion 31. This end of the shaft extends into a cup-shaped cylinder 38. A piston 39 conveniently provided with an O ring packing 40 is slidably mounted within the bore of this cylinder and coupled to the headed end 3'? of rod 26 by mounting a shell 4| into which that headed end extends. A snap ring 42 is conveniently carried by the shell 4| and prevents an accidental withdrawal of the headed portion 31 of the rod. A similar snap ring 43 is carried by the cylinder adjacent its rear end and limits outward movement of the rod therefrom.

Within the cup-shaped member 26 there extends a collapsible structure. As illustrated in Figs. 1 and 2 this structure conveniently takes the form of a diaphragm 44 which may be formed of rubber or similar material. The outer edges of this diaphragm are defined by a flange which is clamped between adjacent similar portions forming a part of the cup-shaped member and the base of cylinder 38. In this manner a fluid type seal is provided at this point so. that the structure may be extended into and retracted from a position toward the base of member 20. A passage 45 extends from the space defined between diaphragm M1 and the base of cylinder 38. This passage communicates with a chamber 48 which defines a valve seat with which a valve 4'? cooperates. The latter is provided with a stem 48. A pasage 49 extends from a point beyond the valve seat to the interior of the bore of cylinder 38. These several spaces are filled with a suitable fluid which may take the form of grease, oil.

That end of stem 43 which is opposite valve body 41 extends into a tubular casing 5|] defining a bore in the base of cylinder 38 and which extends perpendicular to the axis of that cylinder. A spring 5| has one of its ends thrusting against the end of stem 58. Its opposite end bears against the head 52 of an actuator which, for purposes of stability, is formed with a stem portion as shown. The actuator is engaged by the inner face of a sleeve 53 the thickness of which varies to provide an eccentric. This sleeve should be capable of rotation through approximately When disposed in the position shown in Fig. 1, actuator 52 will extend beyond tube 50. When sleeve 53 is rotated to the position shown in Fig. 3, then the actuator head 52 will be substantially completely housed within the tube and spring 5| will be under maximum. compression.

Now with a view to providing a controlling or latch structure it is preferred that a friction member be employed. As shown especially in Figs. 1, 2, and 5, a ring 54 encircles the assembly in the zone of the piston and cylinders 4| and 38. An actuating portion 55 extends outwardly from this ring. A safety catch 56 is conveniently mounted by the ring and, under spring pressure, extends into one of a pair of notches disposed at diametrically opposed points in the adjacent portion 32 of the apparatus. In this manner the ring is prevented from rotating except when element 58 is retracted to permit of such turning. Body 32 is provided with a recess presenting a tapered wall. A ring 51 of rubber or other suitable displaceable material has surfaces generally conforming to this recess and is disposed therein. Interposed between ring 54 and the outer face of cylinder member 38 is a band 59 preferably formed of metal. Displacement pins 58 extend into the recess occupied by ring 5'1 and also into channels 60 formed in the face of ring 54. The base portions of these channels 50 are inclined to present cam surfaces as shown in Fig. 5. Accordingly when the ring is shifted to one position, (safety) element 56 will be projected into a notch Y chamber.

to prevent'thering from turning and pins 58 will be projected in the directionof ring 51 to a maximum extent. This willcause the material of ring BIto be displaced exerting pressure against band 59. The latter will grip the exterior surface of cylinder member 38andthus prevent movementof the parts. 1 Howeverif ring 54 is rotated, for example, through approximately then pins 58 may instantly retract to a maximum extent into channel 60. Thiswill relieve the pressure on band 59 and cylinder 38 will be free to move with respect to the adjacent portions of the apparatus. As ring 54 will project and release pins 58 twice in one full turn, two safety notches (spaced 180) are preferably provided in portion 32. It is apparent that any suitable adjusting structure may be employed to exert initial and adjustment pressure on ring 5! of a nature such that the mere shifting of. the pins 58 will achieve the desired results. i

In employing an apparatus of this nature it will be assumed that the medicament chamber involves an ampule structure of the type as heretofore described and illustrated. The band or sleeve 53 should be rotated so that actuator 52 is depressed to a maximum extent. It being assumed that the device-has been fired, the parts of the assembly providing piston 39 will be adjacent the stop member or ring 43. Under these circumstances crank 30 will be rotated ina counter-clockwise direction as viewed in Fig. 3. This will resultin the piston assembly bearing against the stop 43 and retracting member. 28 and the parts associated therewith. At the limit ofretraction the parts will have assumed the positions shown in Fig. 2. With plunger 2| fully retracted, loading cap 12 may be dismounted and a fresh ampule inserted within the medicament In applying the loading cap the rear end It of the nozzle will displace the seal I! thereby establishing communication between the interior of the ampule and the bore of the nozzle. It is apparent that in mounting the ampule the latter may be initially disposed withinthe loading cap or else have its stem disposed within the bore of nose piece II. If the stem 23 of paramn or other suitable material is not associated with the ampule but rather is formed of, for example, rubber and secured to plunger 2| then; of course, the ampule should be initially disposedwithin the loading cap l2. In any event with the loading cap again mounted the parts will be ready for further manipulation.

If the capacity of the severalparts is slightly different from that shown in Figs. 1 and 3 then the collapsible member of diaphragm 44 may contact the base of the cylinder member 38. To prevent a freezing of the diaphragm against the face of that base a channel 45 is provided atthis point. With the parts in the position shown in Fig. 2 ring 54 is rotated to project the displacement pins 58. Therefore cylinder 38 will be restrained from movement as shown in Fig. 1. Under these circumstances the catch or detent element 55 will rest within one of the notches forming a part of portion 32. Sleeve 53 should be shifted to correspondingly shift actuator 52 and compress spring 5| to a maximum extent. It will be understood that the value of this spring is such that it will hold valve 41 open even under conditions of maximum retraction and consequent operating stroke of the parts. Otherwise valve bod 4'! would be pulled into a sealing relationship with. its seat when the oil pressure within cylinder 38 is raised; such result following because of the different relative areas of the valve body and stem 48. Crank 30 may now be grasped with one hand andthe body ID of the unit with the other. If the crank is rotated in a clockwise direction as viewed in Fig. 3 then piston 49 will be projected within the bore of cylinder member 38.

It will be assumed that a complete full stroke of the parts is desired rather than a partial stroke. This may be measured by registering the forward edge of flange 35 with the adjacent surface of member 34 to determine the amount of projection of that flange. To' this end registering marks (not shown) may be provided upon the outer surface of member 34. Projection of the piston 39 within the bore of the cylinder member 38 will cause displacement of the fluid through the channel 49, chamber 46 and channel 45 into the space defined by the collapsible member or diaphragm 44. This will cause the latter to distend thereby increasing the pressure of the fluid within cup member 2!]. The pressure regulator may now be adjusted. This is achieved byrotating sleeve. 53 to an extent such that actuator head 52 is depressed or projected to the desired amount. Such projection will tension spring 5| to a corresponding degree thus effecting the seating of valve 41. The parts are now in the position shown in Fig. 1.

The site of the injectionhaving been selected the end of nozzle I3 is disposed in contact with the skin at a point overlying this area. If the latch 56 is shifted from within its recess then, by means of the actuating portion 55, ring 54 may be rotated through a limited are (for example, ten degrees). Under these circumstances no operation of the parts will occur because theinner ends of pins 58 are still in engagement with the most raised portions of camming surfaces 6!). Continued rotation of ring 54 will result in these pins being abruptly permitted to retract. This retraction will relieve thepressure on the body of displace-able material thereby releasing cylinder 38 from restraint. Accordingly the power stroke of the apparatus will be initiated. This movement will occur incident to the pressure within cup member 243' which will tend to force a collapse of diaphragm 44 and accordingly a displacement of the fluid therein into the bore of the cylinder member 33. The piston 39 presenting a fixed reaction point during this stroke, it follows that the cup member 20 and all parts associated therewith will be projected.

Assuming that the ampule structure follows the illustrated embodiment then with such projection plunger 2| will act against stem 23. The latter will thrust against stopper i5 and through the bore of ampule 14. Also it will thrust against the rear edge of sleeve [5 to axially compress the same and constrict its bore into supporting relationship with the outer wall of the ampule. At the end of the stroke substantially all medicament will be expelled from the ampule; the flow having occurred outwardly through the bore of nozzle l3. The pressure regulator provided by the valve 49 and its assembly will maintain the value or effective pressure of the stroke throughout its entire range according to the setting which has been imparted to that valve by sleeve 53 or any equivalent controlling structure.

In the unit as illustrated in Figs. 6, 7 and 3 a structure in many respects similar to that heretofore described is employed. Therefore the same reference numerals have largely been used in the latter figuresto designate parts having functions substantially identical with those embodied in Figs. 1 to 5 inclusive. Thus, again we have present a unit embodying a tubular main body I0 with a medicament chamber of the type heretofore described. A cup-shaped member provided with a forward plunger or stem and charged with gas under suitable pressure is also present.

Ihe adjustable pressure regulating valve for controlling the flow of oil or other fluid is also present and the position of the valve is adjusted by movement of the encircling sleeve 53. The shaft 26 is moreover turned preferably by a leverage apparatus involving a multiple link crank as heretofore illustrated.

However the nut 6| which engages the threads of shaft 26 may be directly secured to the casing l0 adjacent the rear end of the latter. Also the piston 62 which is projected and retracted by means of this shaft may be coupled thereto by a head portion 63 of the shaft which is formed of at least two sections and is provided with an antifriction bearing 64 so that relative rotation of the parts may occur and thrust will be properly supported. This piston s2 reciprocates within the bore of a cylinder member 65 to which cup member 20 is secured.

An expansible structure corresponding to the diaphragm 44 is provided in this instance by securing to the base of member 65 a cylinder 66 which has its end open to the interior of cup member 20. Slidably mounted within this cylinder is a piston 61 provided with a groove within which a suitable packing such as an O ring 68 is mounted. This will substantially prevent any escape of gas under pressure from within cup member 20 to the space to the rear of piston 61 'or a seepage of oil or other liquid from the rear of that piston into the cup member 20.

As especially shown in Figs. 6 and 8 casing I0 may be encircled by a yoke 69 which is provided with a recess within which a saddle member in may be disposed. The latter contacts on its inner face the outer surface of cylinder member 65. Its outer surface is engaged by a block H of rubber or similar material which is in turn retained in position by a plate 12. The latter is formed with an opening through which a displacement pin 13 may project. The outer end of this pin is engaged by a rotatably mounted cap I4 having a recess 15 for the accommodation of pin 13. The base of this recess extends tangentially so as to furnish a cam surface. Conveniently a crank 16 may be applied to the cap 14 so as to rotate the latter around its pivot. As heretofore mentioned the outer surface of sleeve 53 may be provided with an indicating mark 11 which registers with one of the several marks 18 applied to the forward inclined face of shoulder 3|. Thus the operator will be aware of the adjustment or position of actuator 52.

With the parts in the position shown in Fig. 6 the medicament within the ampule or other chamber has been discharged. By turning crank 30, piston 62 being engaged by the stop provided by ring 43 will retract cup member 20. This retraction will continue until plunger 2! has been withdrawn to a maximum extent to the left as viewed in Fig. 6. Thereupon loading cap I2 may be dismounted, the spent ampule may be discarded and a fresh ampule inserted. After this the loading cap may again be mounted upon the nose piece.

During the retracting operating cap 14 will have been turned so that pin I3 may shift in an outward direction. This will relieve pressure upon the saddle member 10 so that substantially no frictional engagement occurs between the inner face of the latter and cylinder 65. With the parts adjusted to the position stated then crank 16 is turned to project pin 13 and thus lock cylinder member 65 from movements in an axial direction. A turning of crank 30 in a proper direction will now cause shaft 26 toproject piston 62 to the right as viewed in Fig. 6. This will cause a displacement of liquid through passages 49 and 45 into the space to the rear of piston 61. Accordingly the gas within cup member 20 will be compressed to a maximum extent. As in the case of the structures of Figs. 1 to 5, flange portion 35 may be used as a guide to indicate the range of the stroke which will result when the partsare released. Likewise sleeve 53 may be adjusted to furnish the desired regulation of pressure. Upon cap 14 being turned, displacement pin 73 will shift outwardly and. the restraint on cylinder member 65 will become inoperative. Under these circumstances this member as well as member 20 will shift to the right. With such shifting the medicament will be expelled.

As will be understood structures of this type may readily be modified so that a changeable pressure of pre-determined pattern is established. An arrangement for effecting this result has been shown in Fig. 9. In that view the actuator for varyingthe pressure on the spring of valve stem. 48 has been shown at 19. A unit is provided with undercut portions at its ends. The unit 80 is faced as at 82 to 85 inclusive to be engaged by the actuator '19 as it shifts. These several faces extend to a greater or lesser distance from the axis of the mechanism. A set screw 86 is provided to secure unit 86 in position. With a device such as this in position surface 85 might, for example, provide an initial penetrating pressure on. the order of 4,000 pounds to the square inch. Then if desired face 84 might provide for a pressure of 3,000 pounds while face 83 would provide for 3,500 pounds. Face 82 might provide a terminal pressure of 2,000 pounds to the square inch. This is merely a suggested pattern of discharge for a 1 cubic centimeter medicament chamber. Various other patterns could, of course, be set up.

Thus, among others, the several objects of the invention as specifically aforenoted are achieved. Obviously numerous changes in construction and rearrangement of the parts might be resorted to without departing from the spirit of the invention as defined by the claims.

I claim:

1. A hypodermic injection apparatus including in combination a hollow body, means providing a support for a medicament chamber adjacent one end of said body, means projectible within said body to expel medicament from said chamber, means providing a pressure accumula- I by said expulsion means to control the flow of liquidthrough said passage, a valve movably associated with said mounting, spring means acting upon said valve to cause the latter to regulate the pressure of liquid flowing through said passage and cam means movably carried by said body for varying the compressive force upon said spring.

2. A hypodermic injection apparatus including in combination a hollow body, means providing a support for a medicament chamber adjacent one end of said body, means projectible within said body to expel medicament from said chamber, means providing a pressure accumulator within said body, an expansible structure carried by said expulsion means and acted upon by the pressure of said accumulator, means providing a passage for the flow of liquid to said structure to expand the same whereby said accumulator may act upon and cause projection of said expulsion means, a mounting for a valve also carried by said expulsion means to control the flow of liquid through said passage, a valve movably associated with said mounting, spring means acting upon said valve to cause the latter to regulate the pressure of liquid flowing through said passage, a sleeve rotatably mounted upon said body and a cam carried by said sleeve and acting upon said spring to vary the compressive force on the latter.

3. A hypodermic injection apparatus including in combination a hollow body, means providing a support for a medicament chamber adjacent one end of said body, means projectible within said body toexpel medicament from said chamber, means providing a pressure accumulator Within said body, an expansible structure carried by said expulsion means and acted upon by the pressure of said accumulator, means providing a passage for the flow of liquid to said structure to expand the same whereby said accumulator may act upon and cause projection of said expulsion means, a mounting for a valve also carried by said expulsion means to control the flow of liquid through said passage, a valve movably associated with said mounting, spring means acting upon said valve to cause the latter to regulate the pressure of liquid flowing through said passage and means carried by said body to vary the compressive force on said spring as said expulsion means is projected within said body.

4. A hypodermic injection apparatus including in combination a hollow bod means providing a support for a medicament chamber adjacent one end of said body, means projectible within said body to expel medicament from said chamber, means providing a pressure accumulator within said body, an expansible structure carried by said expulsion means and acted upon by the pressure of said accumulator, means providing a passage for the flow of liquid to said structure to expand the same whereby said accumulator may act upon and cause projection of said expulsion means, a mounting for a valve also carried by said expulsion means to control the flow of liquid through said passage, a valve movably associated with said mounting, spring means acting upon said valve to cause the latter to regulate the pressure of liquid flowing through said passage and means functioning during the projection of said expulsion means for varying the compressive force on said spring.

5. A hypodermic injection apparatus including in combination a hollow body, means providing a support for a medicament chamber adjacent one end of said body, means projectible within said body to expel medicament within said chamber, means providing a pressure accumulator within said body to act upon and cause projection of said expulsion means, rotatable means extending from the opposite end of and axially with respect to said body to potentialize said accumulator to act upon said expulsion means and a plurality of pivotally connected links coupled to said rotatable means to provide a crank structure for said apparatus, said links being swingable with respect to each other to occupy a space substantially within the area extensive from the axial walls of said body.

6. A hypodermic injection apparatus including in combination a hollow body, means providing a support for a medicament chamber adjacent one end of said body, means projectible within said body to expel medicament within said chamber, means providing a pressure accumulator within said body to act upon and cause projection of said expulsion means, a latch means for preventing a projection of said expulsion means, said latch means comprising a ring-shaped displaceable body encircling and acting upon said expulsion means to restrain movement of the latter, displacement means cooperating with said displaceable body, a ring encircling and rotatable with respect to said body and means forming a part of said ring and acting upon said displacement means to control the movement by said projectible means.

'7. A hypodermic injector including in combination a hollow body, a piston assembly projectible therein to expel medicament from a chamber forming a part of said body, said assembly including a pair of spaces connected by a passage, one of said spaces being charged with gas under pressure, an expansible unit mounted by the said assembly and extending into said one space, the interior of said unit and the other of said spaces receiving fluid displaceable from one to the other through said passage, means mounted by said body and acting against the fluid in the other space to displace the same into said unit to expand the latter against the gas within said one space, valve means interposed in said passage and movable towards surfaces of the latter for governing the flow of fluid through said passage, a spring acting upon said valve means to urge the latter away from said surfaces and manually controlled cam means rotatably encircling said body and connected to vary the compressive force of said spring.

8. A hypodermic injection including in combination a hollow body, a piston assembly projectible therein to expel medicament from a chamber forming a part of said body, said assembly having a passage through which fluid fiows to cause projection of said assembly, a valve mounted for floating movement within said passage to automatically govern the flow of fluid therethrough and control the movement of said assembly, a spring acting upon said valve to normally urge the same in one position and manually controlled cam means rotatably encircling said body and connected to vary the compressive force upon said spring.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,380,534 Lockhart July 31, 1945 2,547,099 Smoot Apr. 3, 1951 OTHER REFERENCES A manuscript doctors thesis: Local Infiltra tion of Tissues From a Machine Designed to De- 0 liver High Pressure, High Velocity Jets of Fluid,

by John F. Roberts. The manuscript is in the Medical Library of Columbia University, College of Physicians and Surgeons, 630 W. 168th St., New York, N. Y.; Catalog #R747.C7,/C73/1935. (A copy is in Division 55 of the Patent Oflice.)

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