US 2627270 A
Abstract available in
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Description (OCR text may contain errors)
Feb. 3, 1953 G. B. GLASS PROPELLED AUTOMATIC SYRINGE SELF- Filed Feb. 9, 194
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Feb. 3, 1953 G, B, GLASS SELF-PROPELLED AUTOMATIC SYRINGE Filed Feb. 9, 1946 E@ www mvx m v f m5! ,O N s. www mb P QN n QQ R ww A., a 1 1| w N www. v 9 f ...n QQ Rw@ vm, www www www S S INVENTOR eafye. 67035 Feb. 3, `1953 G. B. GLASS l SELF-PROPELLED AUTOMATIC SYRINGE 5 Sheets-Sheet 5 Filed Feb. 9. 1946 IN V EN TOR.
Patented Feb. 3,
UNITED STATES PATENT OFFICE SELF-PROPELLED AUTOMATIC SYRINGE George Bronislaw Glass, New York, N. Y., assignor to Antonina S. Glass, New York, N. Y.
Application February 9, 1946, Serial No. 646,611
(Cl. 12S-218) 9 Claims. 1
This invention relates to medical syringes.
The general object of the invention is to provide an automatic medical syringe propelled by a motor, preferably electric, which enables drug solutions contained in a disposable ampule-cartridge to be automatically injected at a predetermined rate.
In the medical profession there is an urgent need for such an instrument. Itis needed for the administration of drugs which owing to their side reactions should be injected very slowly, such as the arsphenamides, strophantin, X-ray dyes and many other drugs.
It is also needed in the administration of those drugs which are rapidly destroyed in the body or quickly eliminated therefrom and yet Which require their concentration to be maintained in the blood as by means of repeated injections or constant infusion. Penicillin, sulfonamides, many hormone drugs (such as adrenalin or insulin) some anesthetics and sedatives given intravenously, heparin, and others may require such method of administration. I
A third important use of such an instrument is in the administration of large amounts of fluids parenterally (saline, plasma, glucose solutions) as Well as the transfusion of preserved blood at a precisely controlled and predetermined rate. An automatic syringe can also be used like a perfusion or infusion pistonpump for laboratory experimental purposes.
An additional object of the invention is to provide an automatic self-propelled (preferably electric) syringe to be used with interchangeable and disposable cartridges of a novel type.
A further object of the invention is to provide an automatic self-propelled syringe which can be mounted together with other syringes of the same type but of a different size ii' necessary and set up like a syringe battery on a mobile chassis, all the syringes in such battery being connected with the same inserted needle and each of them injecting simultaneously a different drug solution in a predetermined amount and rate.
Another object of the invention is to provide a small automatic syringe driven by a portable motor (preferably electric) and mounted in a portable box, all of which can be attached to one of the extremities of the body for an unlimited period of time. In this Way the freedom of movement of the person subjected to such a prolonged Vinjection is not hampered.
Other objects, advantages and applications of the invention Will be apparent from the following description and drawings, wherein:
Fig. 1 is a perspective View of a 1Go cc. electrically driven automatic syringe according to this invention, loaded with a cartridge and in action;
Fig. 2 is a side View of the same automatic syringe in an unloaded position;
Fig. 3 is a perspective View of another modication of this invention showing a 2O cc. electrically driven automatic syringe of a portable type loaded and in action, provided with a portable electric motor, said syringe being mounted in a box attached to one of the extremities of the body;
Fig. 4 is a partially diagrammatic view in longitudinal cross-section of the syringe shown in Fig. 3;
Fig. 5 is a sectional View `of the discharge portion of a closed self-propelled automatic syringe along line 5 5 of Fig. 4;
Fig. 6 is a sectional View of the rear portion of the same syringe along line 6--6 of Fig. 4;
Fig. 7 is a rear end vieW of a connecting member in an open position;
Fig. 8 is a rear end View of the connecting member in a closed position;
Fig. 9 is a front end view of the connecting member in a closed position;
Fig. 10 is a fragmentary horizontal transverse cross-sectional View through said connecting member along line lll-I il of Fig. 2;
Fig. 11 is a fragmentary View in longitudinal cross-section of a modified cartridge for use with the syringe in accordance with the invention.
Referring now particularly to the drawings it will be seen that the automatic self-propelled syringe of this invention can be applied in two main types:
1. The stationary type, as shown in Figs. 1 2; it is mounted together with itsmotor I(preferably electric) on a movable support.
2. The portable type, as shown in Figs. 3 and 4; it is of a small size (5-20 cc.) and is mounted in a portable box attachable to one of the extremities of the body. It is driven by a portable motor, preferable electric, With which it is connected by a flexible drive shaft.
The electrically driven automatic syringe consists of (a) a syringe, (b) an interchangeable disposable cartridge containing the drug solution, (c) a perforator mounted on the discharge end of the syringe and connected with a iiexible tubing, to the other end of which a needle is attached, and (d) an electric motor.
' The syringe (in a strict sense) takes the form of a horizontal barrel, the lower part of which is stationary. I'he latter consists of a central portion l provided with front and rear reinforcements 2a and 2b. The rear reinforcement 2b continues into the end portion 3 of the syringe which terminates at the rear in vertical semicircular plate 5. A cylindric bearing for the plunger rod 3| is secured to said plate 5. The central portion of the lower stationary part of the syringe has an aperture 6 (Fig. 2) and terminates at its front end in semicircular plate l'. A forward extension 8 carries a threaded portion ii adapted to engage the rear end et of the barrel of a perforator The upper half part of the forward end of the syringe is formed by another semi-circular plate lil to which the upper half of the forward extension ll is attached. Tit is provided on its upper surface with a small aperture i2. The plate I as well as the upper part of the extension l! are hinged at i3 and secured by a latch It. The lower part of the syringe is attached to the support l? by means of two front and rear supports lEa and lb secured to blocks Ea and leb. On the lateral sides of the syringe two guideways I8 are attached, which are open to the rear 2f; and closed in front Iii (see Figs. 5 and 6).
The upper sliding part of the syringe has a central portion 2l, front and rear reinforcements 22a and 22D, and aperture 2d. The rear reinforcement 22h continues into the upper portion of the syringe .barrel 23 on which a handle 25 is mounted for backward and forward sliding of the upper part of the Syringe so as to open or close the latter. The portion 23 of the sliding part is closed from the rear by a vertical semicircular -plate 26 which contacts with the cylindric bear 4 and borders with the lower semicircular plate 5. The slides 21 of the sliding part of the syringe move in their guidewaysI i8. Small plug-s (not shown) are adapted to each of them to prevent the sliders 2l from dropping out of guideways.V
The front portion of the hollow chamber of the syringe forms the receptacle for the reduced front part of the cartridge and is formed by lower and upper extensions 8 and il. This receptacle communicates to the rear with the middle portion of the hollow chamber of the syringe into which the barrel of the cartridge 13B containing the 4drug solution 56 is inserted. The rear )portion of the hollow chamber of the syringe is con-- tained Vwithin the upper and lower portions 23 and 3 of the syringe and harbors the head of the plunger 2S and Sil when the `syringe is unloaded. The head of the plunger is formed of a narrow 29 and wide tt portions which are integral or welded together, and it is attached to the plunger rod 3l which is internally `bored 32 through its whole length. To the lower surface of the plunger rod a thin bar 33 is attached, which engages a groove in the lowest part of the plunger rod bearing i and in such way prevents the plunger and the plunger rod from deviating and rotating during the thrust (see Fig. 6). To the rear of the plunger rod 3l a connecting member is attached (Figs. 7 and 8) for coupling the plunger rod ti to the threaded drive shaft 8l of the motor.
The connecting member Bt-tl comprises an oval shaped portion 3d. To its upper part a bolt 35 is attached terminating in a handle 35 which Amay be rotated. The bolt 35 accommodates a vertical shaft 3l (Fig. 10) which is attached at its upper end to the handle 36 and at its lower portion to a gear 43.23. The latter engages a horizontal rack bar 39, the rear and front yportions of which 4D are smooth and form a bolt running through the bore di in the Lipper part of the connecting member. The middle portion of the connecting member d2 (Figs. 2, 7 and 8) has a circular vertical cross-section. it is provided with three bores: (a) the upper bore which is a continuation of the bore di and through which the bolt it is running; (b) the middle bore which is a continuation of the large central longitudinal bore of the plunger rod 32 and through which the drive shaft of the motor 8l is running; and (c) the lower bore, through which a short thin shaft d3 extends. The latter terminates in latch de which is adapted to engage a small hole 82 in the front wall of the motor box. The connecting member further comprises two semicircular members 45a and 5b hinged on the shaft 43. Each member d5 is provided internally with a horizontal groove @da and @6b threaded correspondingly to engage and mesh the screw threaded shaft 3l. To the part of each of the inembers :35a and 6551 a collar ila and lill] is attached, having a small circular .bore (Figs. 1 and 7). When both semicircular halves of the rear portion of the connecting member are closed, there two collars stand one behind another forming a channel. By an appropriate turn of the handle Se the rear portion of the bolt d@ is pushed into this. channel and locks both members 45a and 5b tightly around the drive shaft El of the motor. In this position a tight fit is produced between the threaded part of the drive shaft of the motor Si and the threaded grooves a and del) of the connecting member. If the handle 35 is turned to the other side,.the bar Lid will be pushed forward out of the channel, so that both semicircular' halves of the rear portion of the connecting member' itc and 45h get disconnected and the tight fit between the connecting member and the threaded portion of the drive shaft 8l is severed. This enables the 'plunger rod to move forward or backward in response to the manual pressure exerted upon the handle 35 and the bolt 35.
The ampule-cartridge containing the drug solution consists of a cylinder 48 made preferably of glass. It comprises a reduced front portion, called the head of the cartridge dit which is closed by a cap member E@ preferably made of rubber. After the ampule-cartridge has been manufactured, sterilized and sealed with the cap member 5t a protective cover (not shown) made of aluminium, paper, cellophane or other appropriate material is placed lupon the latter. This is removed before use. The rear portion of the glass cylinder has a closure in the form of a combined stopper and piston member 52 which is made preferably of plastic or cork. It has on its periphery a circular fluid-tight band 53 made preferably of rubber, and centrally a hollow 54 which is adapted to engage the reduced front portion of the plunger head y29. The utmost rear portion of the cartridge i8 which is situated to the rear of the combined stopper and piston member 52 is adapted to accommodate the wider portion of the plunger head 3@ before the start of the injection. When the injection is started this wide portion of the plunger head 33 exerts the pressure only upon the peripheral part Iof the combined stopper' and piston member 52 which prevents the breakdown of the latter during operation.
The external part of cartridge cylinder `bears painted or etched inscrpitions denoting the contents of the cartridge and the concentration of the drug solution 56 in it as well as graduations in cc. 55 readable through the upper aperture of the syringe barrel 24 after the cartridge has been loaded into the syringe. The -position of the combined stopper and piston member in respect to the graduation indicates the actual amount of drug solution which has been discharged from the cartridge.
The usual content of the cartridge is a fluid drug solution 56. The ampule-cartridge with its content is prefabricated. It may also contain a powder which is dissolved before the use of the cartridge. This can be done through the stopper member by means of a double barrelled needle through which the solvent is introduced while the air escapes.
A modication of the above cartridge is discussed below.
The perforator with a exible tubing attached to it connects the contents of the ampule-cartridge, which is charged into the syringe with the needle inserted in the body of the patient. The perforator consists of a metal barrel 51 having thick walls and bearing in its upper part a C shaped aperture 58 having a front and rear recess 58a and 58h (Fig. 2). The barrel of the perforator has a reduced front portion 59 and comprises in its rear part a mobile nut 60 which is adapted to engage the threaded front portion of the syringe 9. The barrel of the perforator is bored throughout its length forming a channel 6|. The front part of the latter forms the front chamber of the perforator 62. This is formed only when the glider of the perforator 63' is pushed backward.
The glider 63 to the upper surface of which a bolt 64 is fastened engages the adjacent internal surface of the barrel of perforator and in any position obturates the upper aperture of the latter. The glider is bored throughout its length. Its central internal channel 65 continues backward into the channel of the needle 66 and forward into the front chamber 61 of the glider 63. The latter communicates with the front chamber of the perforator 62 by means of small openings 68 situated on the periphery of the front wall of the` glider 63 which tapers to form plug 69 to which a rubber or cork cap 1U is attached. The reduced front part of the perforator 59 continues into a flexible tubing 1| made preferably of rubber or other iiexible material. The tip of the tubing is connected with the inserted needle.
After the perforator has been mounted on the syringe by means of its mobile nut 69 and the bolt 64 of the perforator has been pushed backward and locked in the rear recess of the Caper ture 58h the needle 66 will be forced to perforate the cap member 50 of the cartridge and enter the head 49 of the latter. This can be observed through the aperture I2 provided in the upper part of the extension ll of the syringe. At the same time the plug 69 pushed backward will open the reduced front portion of the perforator 59 so that a communication is established between the flexible tubing 'H and the fluid content of the cartridge 56. When, however the bolt 64 is pushed forward and locked in the front recess of the aperture 58a the needle S6 of the glider will leave the cartridge and the plug 69 covered with the rubber cap 1D will enter and close the reduced front portion of the perforator 59, so that the connection is severed between the flexible tubing and channel 6| of the perforator. The nexible tubing 1l terminates distally in a rigid tip portion 12 which has engaging means I3 to engage the rear portion of the needle.
A modification of the cartrldge-ampule is shown in Fig. 11. Here the flexible conduit Ha is mounted directly on the reduced front part (head) of the cartridge cylinder 49a forming a tubular integral portion of the latter. Both cylinder 48d and tubing 'Ila are lled with the drug solution 56a and the rear portion of the cartridge is closed by a combined stopper and piston member `52a comprising a fluid-tight circular band 53a. The tubular portion of the modified cartrdge has on its distal end a rigid tip portion 12a comprising means for engaging a needle 13a and closed by a membrane 50a, preferably made of rubber. The rigid tip portion of the tubing of the modilied cartridge is covered during storage by a removable cover 5Ia made of aluminium, cellophane, paper or other material. No perforator of a kind described above is needed for the modified cartridge.
The driving element of the automatic syringe is the screw threaded drive shaft 8|, having a, reduced portion Blb which is connected to the gear |93 and which by means of the connecting member 34-41 may be coupled to the plunger rod 3l of the syringe. With the rear portion of the connecting member 45a and 45h locked around the threaded central portion of the drive shaft 8| the rotation of the motorcauses the connecting member and the plunger 29-3l to move forward. This exerts a pressure on combined stopper and piston member of the cartridge 52 and results in expelling the fluid contents 56 of the cartridge through the flexible tubing Ha or 'H into the needle. The forward movement of the plunger continues until the threaded part of the connecting member ceases to contact the screw-threaded portion of the drive shaft and gets in contact with the smooth reduced portion of the latter.
The electric motor driving the automatic syringe preferably should have a low rate of revolutions. If the pitch of the screw threaded shaft of the syringe is such that the discharge of the fluid from the cartridge requires twenty revolutions of the drive shaft, and the rate of revolutions of the motor is between 1 and 200 per hour. at the slowest rate the syringe will empty in 20 hours and at its quickest rate--in 6 minutes.
The electric motor, as described in this embodiment is contained in a box 95 and is attached to a stand 96 (see Figs. 1 and 2). The power is provided by a regular electromotor of small dimensions adjusted to alternate or direct current, and which has a relatively low rate of revolutions per minute. In the embodiment which is here described the motor having 500 revolutions per minute is used and the speed is reduced to the required range of 1 200 revolutions per hour by aid of an appropriate gear box and a rheostat (not shown in the drawings). The current enters the motor through the plug 91. On the 'top of the motor a switch 98 is mounted, which switches the motor on or off and a speed control switch 90 for adjustment of the rate of delivery is also provided. The construction of the motor, gear box, the rheostat, switch and the plug are as acapara sists of a small gear box (Figs. 3 and 4,) which is reduced in its front portion l0! and which comprises bearing |02 for the rear portion of the drive shaft Blb which ends by a .small gear |03. In the rear portion of the gear box another gear |08 is contained which meshes the gear .of .the drive shaft |03 and by means of a connector |09 engages the exible wire |||l rotating in an insulating cord. The latter is connected with the drive shaft of the motor so that the revolutions of the latter are -transmitted to the drive shaft of the syringe 3|. The transmitter also comprises a notch |04 for the latch .lie of the connecting member of the plunger rod, and by means .of shoulders .|05 and a central column |06 is attached to the stand |01.
The container for the `portable syringe consists of a fiat base to which the support .of the syringe Il and the stand of the motor transmitter |01 are attached. To this base a cover |2 is fastened, preferably made of plastic. The upper part of the cover is transparent and vit opens laterally by aid of a hinge H. The cover is closed by means of a lock H3 and it has in its front wall a long and narrow aperture ||5a through which the iiexible tubing 'iI or the tubular portion of the modified cartridge 'Ha passes. A similar aperture ||5b is provided in the rear wall of the cover for the exible drive wire lm. The flat base of the container can be attached to one of the extremities by aid of two belts Htc and ||6b and two intermediary inlays: the upper of them il is fiat above and concave below,.and the lower one ||3 has a concave upper surface and a convex lower one. The motor of the portable type of automatic syringe is contained in a portable box H9. The current enters the motor with the wire |20. The dial of the speed control is the same in both types of syringes. The external switch of the speed control .Se has a pointer 12| the tip of which |23 is set by means of the handle |22 on the respective figure of the dial. The rate of delivery is indicated on the dial in terms of (a) revolutions per hour of the drive shaft of the syringe |24, (b) time in which the syringe will empty (25), and (c) rate of delivery in cc. per lhour (i 25). Since the portable motor can be coupled to syringes of various sizes (5-20 cc.) the dial of the motor comprises an additional switch |27 which shifts the figures of I the rate of delivery depending upon thesize of the syringe used. The latter automatically shows in the aperture |25. The turn of the switch |27 by means of a gear train (not shown) causes the shift of a disc on which the respective figures are drawn.
The automatic syringe is loaded and set in motion as follows: The sterile wrapper is removed from the head of the ampule-cartridge. Then the cartridge is charged into syringe, so that its main body is set in the middle portion vof the hollow chamber of the syringe, andr its head is placed in-itsreduced front portion. The upper front plate In with its extension is .closed-on its latch I4 and the sliding part of the syringe by means of the handle 25 is pushed forward to lock the ampule-cartridge within the hole chamber of cation of the uid between the cartridge Vand the tubing. This .can be observed through the aperture I2. Now the bolt 35 is pushed forward by hand, so that the plunger head 29.-30 enters the cartridge and engages the combined stopper and piston member .52. The push on the Vbolt 35 is continued until the air is completely driven .out of the perforator, fiexible tubing and the needle, and until the iiuid flows out. Then the .connecting member is locked around the .drive shaft 8| by turn of the handle 3B. The switch of the speed control is set on the required rate of Ydelivery and the motor is switched on.
The use of the modified ampule-cartridge .(Fig. 11') simplifies the operation still more. After the cartridge has been charged in the syringe, the sterile wrapper from the tip of the tubular portion is removed and a sterile needle is .attached to its end after removal for penetrating the membrane. The Vair is removed from the system, as described above, and the connecting member is locked around the drive shaft of the syringe. The needle is inserted and the motor is switched on, after its speedV has been adjusted by an .appropriate turn of the switch of the speed control.
The .advantages of this invention are apparent from the above given description. The .electrically driven automatic syringe enables automatic parenteral administration of any .drug solution @Ontaned in the prefabricated ampule-cartridge at any rate varying from a few minutes to many hours depending upon the requirements of the injection. The use of cartridges of a modilied type containing drug solutions enables the administration of the drug without sterilizationin the office or hospital of any part of the instrument except the needle. The rate of the administration of the drug can be adjusted .during the injection and is controlled precisely by the mechanism of the driving motor. The drugsolution can be also easily changed during the injection by exchange of the cartridge, The use of a battery of self-propelled syringes renders possible the administration of many different solutions in various amounts and at different rates through only one inserted needle. .The use of the portable type of a self-propelled syringe makes possible a continuous administration of small amounts of drugs during 24 hours without hampering the freedom of movements of the subject. Other practical advantages of the instrument will also be readily apparent.
As many possible embodiments may 4be made of the features of the above invention and as the art herein described might be varied in various parts all vwithout departure from the scope `of the invention, it isY to be understood that all matter shown in the accompanying drawings herein before set forth is to be interpreted as illustrative and not in a limited sense. For instance the coupling of the plunger rod with the drive shaft may be varied, the graduations may be setnot on the wall of the glass cylinder of the cartridge but on the plunger rod, the general aspect of the syringe may be changed, lmany variants of the construction of the motor and of the ampule-cartridge are possible. I intend therefore by the appended claims to cover all such modifications as fall within the true spirit and the scope of the invention of the self-propelled automatic syringe with motor drive.
What I claim is:
1. In a motor driven medical injection apparatus for the controlled automatic injection of fluid medicaments, comprising a stationary support, a
motor secured to said support, and a plunger mounted on said support and operatively associated with the drive shaft of said motor, a receptacle rigidly secured on a stationary part of said apparatus, a, disposable cartridge in said receptacle for containing injectable fluid medicament in operative alignment with said plunger, whereby the contents of said cartridge are automatically discharged on operation of said motor, said receptacle comprising a hollow chamber, a cover member movable to disclose an opening for loading said cartridge in said receptacle, a front Wall portion for preventing forward movement of said cartridge, said front wall portion having an outlet port for discharge therethrough of said injectable medicament, and an opening in the rear portion for reception therein of said plunger.
2. In a motor driven medical injection apparatus as claimed in claim l, the provision of means for manually operating said plunger independently of said motor.
3. In a motor driven medical injection apparatus as claimed in claim 2, the provision of means for changing the rate of travel of said plunger.
4. In a motor driven medical injection apparatus as claimed in claim 3, the provision of a screw-threaded drive-shaft connected with said motor, a travelling nut mounted on said drive shaft and connected with said plunger, and means for preventing rotation of said nut during the axial travel thereof.
5. In a motor driven medical injection apparatus as claimed in claim 3, a screw-threaded drive shaft connected With said motor, a travelling split nut mounted on said drive shaft, means for preventing rotation of said split nut during axial travel thereof, a connecting member for connecting said split nut and said plunger, and manual means for disconnecting said spilit nut and said drive shaft.
6. In a motor driven injection apparatus, a stationary support, a motor having a drive shaft secured to said support, a plunger operatively associated with the drive shaft of said motor, a holder on said support, and a container for injectable fluid rigidly secured in said holder in operative alignment with said plunger, said container comprising in combination a sealed ampule containing injectable sterile fluid, a discharge opening at one end of said ampule, a ilexible conduit having one end secured to said discharge opening and an opposite end being adapted for securing to a needle, and displaceable combined stopper and piston means at the other end of said -ampule for sealing said other end of said ampule and for discharging said injectable uid from said ampule through said tubing in response to pressure applied on said displaceable means by the plunger of the injection apparatus.
7. In combination, a dischargeable container for injectable fluid, comprising an ampule, an injectable iluid sealed within said ampule, an opening at the front end of said ampule, penetrable closure means association with said opening for sealing the front end of -said ampule, and displaceable combined stopper and piston means slidably mounted at the rear end of said ampule for sealing said ampule `from the rear and for discharging said injectable fluid from the ampule in response to external pressure applied upon said displaceable means, a flexible conduit, means associated with one end of said conduit for establishing communication of injectable fluid between said ampule and said conduit through said penetrable closure means, means at the other end of said con-duit for attaching a needle, motor driven means operatively associated with said displaceable stopper and piston means for discharging said container at a predetermined and controlled rate, and securing means `associated with said motor driven means for rigidly holding said container in operative alignment with said mot-or driven means.
8. A disposable container for injectable fluid, comprising a sealed from the rear ampule, a restricted discharge opening :at the front end of said ampule, a exible conduit having one end connected to said opening, closure means .at the other end of s-aid conduit for sealing the latter, means for attaching a hypodermic needle at said other end of the conduit, an injectable fluid sealed Within said ampule and sai-d conduit, and displaceable combined stopper and piston means slidably mounted at the rear end of said ampule for sealing the injectable fluid in .the ampule and for -discharging said fluid from the ampule and conduit in response to externally applied pressure upon said -displaceable means.
9. In combination, a disposable container for injectable fluid, as claimed in claim 3, mot-or driven means operatively associated with said container for discharging said container at a predetermined and controlled rate, and securing means associated with said motor driven means for rigidly holding said `container in operative alignment with said motor driven means.
GEORGE BRONISLAW GLASS.
REFERENCES CITED The following references are of record in the le of this patent:
UNITED STATES PATENTS Number Name Date 1,416,614 Cournand May 16, 1922 1,556,085 De Pew Oct. 6, 1925 1,725,318 Thayer Aug. 20, 1929 1,751,139 Feinstein Mar. 18, 1930 1,755,684 Clark Apr. 22, 1930 1,966,498 Gross July 17, 1934 2,057,726 Landis Oct. 20, 1936 2,137,132 Cooley Nov. 15, 1938 2,449,968 Smith Slept. 21, 1948 FOREIGN PATENTS Number Country Date 28,796 Great Britain Dec. 13, 1913