US2608373A - Filling apparatus for containers - Google Patents

Description

Allg 26, 1.952 W. TUTTLE ET AL 2,608,373

FILLING APPARATUS FOR CONTAINERS 'WLW Al1g- 26, 1952 w. TUTTL'E ET AL 2,608,373

FILLING APPARATUS FOR CONTAINERS 5 Sheets-Sheet 2 Filed Aug. 6, 1946 Illz..

Aug 25, 1952 w. TUTTLE ET AL FILLING APPARATUS FOR CONTAINERS 5 SheeIs-Sheet 3 ///5 Q 4 sf /2 6 muy o, .\\A lA ,A A ,NL/a 2 I M m Mw A y i f M2 A Wis \w IIIIIIII I IIIA Filed Aug. 6, 1946 Patented Aug. 26, 1952 FILLING APPARATUS FOR CONTAINERS Wainwright Tuttle, Devon, and Nils Otto Loven, Monroe, Conn., assignors to Bridgeport Brass Company, Bridgeport, Conn., a corporation of Connecticut Application August 6, 1346, Serial No. 688,782

y 11 Claims. 1

This invention relates to apparatus for relling dispensing units'for use in connection with the distribution or dispersion of insecticides, fumigants, hormones and the like.

The patent to Goodhu-e et al., No. 2,321,023, discloses a method of `producing insecticidal aerosol which involves confining in a receptacle under super-atmospheric pressure a liquid gas containing in solution a suitable insecticide and releasing the receptacle contents, as desired, through a discharge orifice into the atmosphere. The receptacle contents are forced into the atmosphere by the high vapor pressure of the liquid gas, and the liquidsolvent instantly evaporates into the atmosphere, separating the solute into particles of colloidal dimensions and leaving them suspendedinthe air, in the form of an aerocolloid, which is known as an aerosol. The receptacles generally are fitted with a discharge nozzle provided with a removable cap which, when screwed tightly onto the discharge nipple of the receptacle servesto open an internal valve and to release the contents of the receptacle in the form of `a spray through a discharge orifce in the cap. When the cap is removed, the internal valve closes automatically to prevent loss of the receptacles contents. ySince these recep tacles are comparativelyexpensive and reiillable, they may be sentA back to the manufacturer for refilling purposes. "However, this is time-consuming and fairly costly.

An object of thepresent invention is to provide a field filling unit for distribution at convenient points or localities to which the users may bring such receptacles for refilling, thereby obviating the'necessity of returning these receptacles to the manufacturerfor such purposes.

Another and principal object of the invention is to provide a refilling apparatus in which no electrical connections or devices are necessary.

A further important object of the invention is to provide an apparatus that will refill such receptacles to a uniform over-all weight, including the weight of the receptacle and the filler.

Another object of the invention is to provide novel means for pumping and forcing the liquid filler from the supply tank to the receptacle being fined.

Other objects and advantages will appear hereinafter.

To the accomplishment of the foregoing and such other objects as may hereinafter appear, this invention consists in the novel construction and arrangement of parts hereinafter to be described and then soughtto be defined in the appended claims, Vreference being had to the accompanying drawing forming a part hereof which shows, merely for the purpose of illustrative disclosure, a preferred embodiment of the invention, it being expressly understood, however, that changes may be made in practice within the scope of the claims without digressing from the inventive idea.

In the drawing, in which similar reference characters denote corresponding parts- Fig. 1 is a plan View of the apparatus of this invention;

Fig. la is asectional, elevational view on a reduced scale of the supply tank; K

Fig. 2 is a side elevation partially in section of the device of Fig. 1; *A

Fig. 3 is a fragmentary section taken along the line 3-,3 of Fig. 2 and viewed in the direction of the arrows;

Fig. 4 is a fragmentary sectional view of a detail taken along line 4-4 of Fig. 1;

Fig. 5 is a similar enlarged fractional sectional view of another detail taken along line 5--5 of Fig. 1; and I Fig. 6 is an enlarged vertical section taken along the line 6 6 of Fig. 2 illustrating details of the mechanism for connecting the receptacle to be filled with the filling apparatus.

Referring now more specifically to Figs. 2 and 6, il) is a generally cylindrical metal receptacle with dome-like ends, which is designed to receive under pressure a liquefied kgas containing in solution an insecticide, fumigant, hormone or the like.' This receptacle l''may be approximately 6 long and approximately 3 in diameter, so that it may be readily held in a persons hand and directed as desired. At one end, the casing is provided with suitable means for discharging the receptacle contents into the atmosphere. This discharge means includes a tubular member II'(Fig. 6)V projecting through an aperture in one end of the receptacle I0 and preferably formed with a shoulder I2Y which engages the outer surface of the receptacle end. A gastight seal is established' between the receptacle II) and the member II by any suitable means.

The inner 'end ofthe tubular member Il is formed with a reduced diameter portion I3 around which'tightly iits one end of a tube I3a extending substantially to the opposite end of the receptacle, The passageway through the member II is composed of three sections I4, I5 and I6 of progressively increasing diameter from the inner end of the member outwardly. In the passageway I is provided an elastic ring I'I,

rod, presently to be described, engages.

preferably composed of synthetic rubber, such, for example, as neoprene, said ring being held in gas-tight sealing relationship and in place by an inwardly projecting lip I8. The member i i is threaded exterorly at I9 to form a nipple to receive a removable cap (not shown) having a discharge orice through which the contents of the receptacle are discharged under p-ressure.

In the passageway l5, there is provided a helical expansion spring 29, one end of which sup ports a cup-shaped element 2l facing the ring l1. The cup-shaped element 2l has a bottom cylindrical recess 2id in which a valve operating The rim 2lb of the cup-shaped element 2| `is -normalh7 biased into sealing engagement with the ring l1 by the spring 23 so that its cup-shaped element. together with the ring l1, serves as a one-way valve normally sealing the contents of the rcceptacle therein. The removable cap (not shown) which screws onto the threaded portion i9 contains parts that operate to raise the cap rim '2l from its seat on the ring l1 to release the contents of the receptacle when desired. These parts are removed, together with the cap, when it is desired to rell the receptacle I and, therefore, are not shown. The receptacle lli, with its cap removed, is adapted when empty to be applied to the field filling apparatus now to be described for refilling. A

` Referring now more particularly to Figs'. l, 2 and 6, this filling apparatus comprises a guide shell 25 which is admeasured in dimensions to receive the receptacle IB and to assist in supporting it vertically during the filling operation. This guide shell 25 has a drain outlet 25a and an opening in its bottom in which a tubular member 26 is permanently fixed as at 21. This tubular member 26 has a passageway 28 which is internally threaded at 29 land admeasured in diameter and depth to receive thethreaded portion i9 of the tubular member Il. Y The member 25 also has a passageway section 39 of larger diameter than the section 28 and these two sections are joined by a passageway section 3l of comparatively smaller diameter than either of the sections 28 or 35.

The tubular member 25 has an exteriorly threaded portion 32 and an Unthreaded portion 33 of smaller diameter than the threaded portion 32 dening a shoulder 34. A tubular member 35, admeasured in diameter and in length to t fairly loosely and slidably within the passageway 35, is provided. This tubular member 35 has a pointed lower end 35a and an annular flange 3S. A latch expansion spring 31 is carried about the portion 33 of the tubular member 25 between the annular shoulder 34 and the upper surface of the flange 36 and functions as will be presently described. The tubular member 35 is held in place by a tubular member 38 which is internally threaded at 33aI for threaded engagement with the threaded portion 32 of the tubular member 25. An annular shoulder 39 at the opposite end of the member 33 cooperates with the annular flange 55 to limit outward movement of the tubular member 35 relative to the passageway 39 induced by spring 31. The tubular member 35 has passageways 4G, 4l 42 and 43 of progressively increasing diameter. An internally threaded passageway 44, in which `a threaded nipple having an internal passageway 46 may be screwed, provides access to the passageways 49, 4|, 42 and 43 for purposes presently to be Adescribed.

As shown in Fig. 6, a helical biasing spring 41 is supported in the passageway section 4l. An elastic ring 68 of rubber, such as neoprene or the like, and having a substantially T-shaped section, is supported in the passageway sections 42 and 43 above the helical spring 41. This ring is secured in sealing relationship upon the shoulder 39 by awasher 50 and ring nut 5l which is threadedly engaged in the threaded portion 52 of the passageway section 43.

A cup-shaped element 53facing the ring t3, is supported on the helical spring 41. This cupshaped element 53 has a bottom cylindrical recess 53@ which is adapted to support one end of an upwardly .projecting rod 54. The rod 54 projects upwardly of the cup-shaped element through ring 58, washer 59, ring nut 5|, passageway 3l and into the passageway 23. This rod 55 has a central passageway 55, communicating passageways 56 at its lower end, as well as communicating passageway/s 51 near its upper end. The upper end of the rod 54 is reduced in diameter and admeasured to t loosely within the reduced portion 2id of the cup 2l when the nipple portion i9 of the receptacle Ill is screwed into the threaded portion 29 of the tubular member 23. The lower end of the vrod 55 ts fairly loosely within the reduced .portion 53a of the cup-shaped element 53 to permit the rim 53h of the cupshaped element `53, to accommodate itself to the lower surface of the neoprene ring 48. Y

The cup-shaped element 25, and the assem bled parts just described, a-re supported suitably as shown in Figs. l and 2 by the arms 69 and 6l of a forked balance lever 62. These arms B0 and 5l are supported on a shaft 63 and the latter, in turn, is carried between the ball bearing supports 55, 55, provided in the oppositely located uio-standing brackets S6, 61, these brackets being suitably supported from a table member 58. The portions 69a, Gla of the arms 65, 6l extend beyond the ball-bearing supported shaft 63.

A counterweight 69 is adjustably crarriedron these arm portions 69a, Sla for purposes presently to be described. The portions 59h, Sib of the arms 63, 6l extend forwardly of the tubular member 26, being bent closer to each other there, and are joined by a cross rod 10. The arms 55, Si constitute a balance lever 52 whose fulcrum is the ball-bearing supported axle 63.

A yoke member 1l supported fxedly at 12 from the arms 69, 6l in turn pivotally supports at 13 a forked lever 14, this lever 14 in turn at 15 pivotally supporting a latch member 16. This latch member 16 is substantially L-shaped and one of its legs has a pawl member 11 at its end which extends between the arm portions 59h, lb, and is engageable with the cross rod 19. A forked member 15 bearing a cross rod 19 between its tines is supported xedly from the base 63 and is positioned to underlie the end 15a of the L-shaped latch member 1B. 'The -height of the cross rod 19 is so admeasured that when the balance arm 92 consisting of the levers 60, GI is tilted in the clockwise direction of Fig. 2, to a predetermined extent, the latch or pawl member 11 will become disengaged from the cross rod 1D. The lever` 1d has a portion adapted to underlie the pointed end 35a of the tubular member 35 so that if the lever 14 is rotated in the counterclockwise direction of Fig. 2, sufficiently for the pawl 11 to engage the cross rod 10, the member 35 will be moved upwardly within the passageway 30 of the tubular member 26 against the action of latch spring 31 to substantially the position shown in Fig. 6. As a vresult of this uplift, the rod 54 .will be raised to the limit permitted by its annular flange 58 so that both the cup member 2| and the cup member 53 will have their respective rims 2lb and 53o moved out of sealing engagement with respective rubber rings |1 and 48. i. On the other hand, when the balanced lever 62 tilts in the clockwise direction sufficiently for the end 16a to engage the cross rod 19, it will disengage the pawl 11 from the cross rod 1U. The latch spring 31 will then move member 35 outwardly to the limit permitted by flange 39, and rotate the lever 14 in clockwise direction. The helical springs and 41 will then be free and, through their biasing action, will restore the cup members 2| and 53 to their normally closed positions. The latter described position is the normal position of the parts within the tubular member 26.

The .nipple 45 which extends laterally of the tubular member 35 near its lower end is joined by a suitable coupling nut 80 to an extension 8| of a tubular helical coil 82. The other end of this coil 82 is secured suitably to a coupling 83 carried fixedly, forV example, by one of the brackets 66. A conduit 84 connects the coupling 83 with a conventional filter 85 (Fig, l). This illter 85, in turn, is connected by conduits 86, 81 and 88 to the outlet nozzle 89, tted with a one-way valve (not shown), opening outwardly, of aconventional hand pump 90. The inlet nozzle 9| of this pump 90, fitted with a one-way valve (not shown), opening inwardly, is connected by a conduit 92 to the outlet 93 of a supply tank 94 which contains the filling compound. A tubular extension or standpipe 93a extends from outlet 93 inwardly of tank 94 nearly to its bottom i. e. within lifto 1/8". The standpipe 93a is, of course, connected in leak-proof manner to the outlet 93. The reciprocating piston 95 of thehand pump 96 is connected pivotally at 96 to a yoke 91 which, in turn, is pivotally supported at 98'and operated by a removable lever arm 69; When out of operation, the lever arm 99 may be removed from the socket of the yoke 91 and carried in the spring brackets |06 ilxed to the table member 68.

Operation of the device is as follows: Assuming that the illling tank has been suitably connected to the conduit 92 and that the operating lever 99 has been inserted into the socket of the yoke 91, the removable cap of the receptacle |0 to be filled is removed from the nipple of that unit. The receptacle I9 is inverted and its threaded portion I9` is screwed into the receiving thread 29 of the member 26. The lever member 14 is then rotated counterclockwise about its fulcrum 13 until the pawl 11 engages the cross arm 1D, to maintain the said position of said lever 14. This serves to raise member 35 in opposition to latch spring 31 and to move the cup members 2| and 53 away from their seats on the rubber rings |1 and 48. Operation of the pump in one direction by lever 99 draws the filling fluid from the tank 94 through the one-way valve in nozzle 9| into the pump chamber. Then operation of the lever 99, in opposite direction, forces this fluid in the pump cylinder through the one-way valve in nozzle 89 and the conduits 88, 81 and 86, through the filter 85, and then through the conduit 84 and through the coiled tube 82 and its extension 8|, through the passageways 46, 40, 4|, 42, around the rim of cup 53, through the passageways 56, 55, 51, around the rim 2lb of the cup 2| and through passageways I5 and |4 to the interior of the receptacle l0. As long as the pump is operated, fluid is transferred from the convenience only.

'6 tank 941to7 the receptacle: if),A asv justdescribed. The counterweight 69 is of such Vsize that when thekreceptacle is filled to a predetermined weight, thebalancebeamiBZ is in equilibrium. The center of gravity at this time'of thewhole moving system isabove the center of rotation 63. As soon as the combined Weight of the unit |0 and its filling is slightly heavier than the counterweight 69 or other counterbalancing means, such as a spring, it starts to rotate the balance beam 62 in clockwise direction, forcing the portion 60h, 6|b of this beam downwardly. As soon as the beam 62 is rotated through any appropriate angle, there is an increasing torque tending to rotate it further in the same direction. When this beam 62 is rotated f ar enough to produce a substantial turning moment, the extension 16a of the latchingv arm 16 strikes the fixed stop 19, causing the ratchet arm 16 to rotate about its fulcrum 15 and releasevthev pawl 11 from the cross rod 10. The latching spring 31 Vis then free to move a tubular member 3'5 outwardly until the flange 36 strikes the shoulder 39, at which time the biasing springs 41 and 20 operate respectively to move the cup members 53 and 2l into sealing engagement with their respective rubber rings l1 and 48. The filled receptacle I6 may then be unscrewed from the threaded socket 29 and replaced by a newunit to be filled. The procedure is then repeatedwth this new unit.

The function of the coil lspring tube 82 in the feed line is to make *they resisting torque negligible so that operation of the balance beam 62 will not be restricted. This'coil 82 is located near the center of rotation of the beam 62. As shown in Fig. 2,.the coil 82 is located'substam tially below the ball-bearing mounted axle 63.

The pump 99, while described as a hand pump, may be replaced by a power pump or, in the alternative, it may be eliminated and the sup- 'ply tank 94 may be vheated to increase the pressure of its contents and Ythereby to force the ow of fluid through the conduit to the unit being iilled. If desired, an accumulator (not shown) may be incorporated in the luid line between the pump and the coil 82 so that a more uniform flow will result and thereby reduce the variable errors lintroduced by the pulsations of ilow while the balanced beam 62 is moving from its latched position to its unlatched position, as described. The filter 85 functions to prevent the entry of dirt into the filtering head or the receptacle I0. Suitable check valves |ll| are provided in the conduits from the pump 99 to the filling unit, for example, between the conduits 88 and 81. It is to be understood, too, that the pump 96 itself contains built-in check valves (not shown).

The valves V of Freon containing tanks 94 normally have a comparatively small opening, so that to obtain any substantial flow the pump 96 must exert considerable suction. Normally, a volatile fluid under such suction tends to vaporize and to vapor lock the pump. However, it has been found that while the pump 96 will illl with gas for afew strokes of lever 99, the cooling effect of the vaporization of the Freon tends to reduce the vapor pressure of the liquid and to offset the lower suction pressure. The insecticide is normally mixed with Freon in the supply tank 94.. This, however, is for VIt could, ifddesired, be injected separately.y Control valvesV1, V2, of conventional type, may be provided in the conduits 92 and 88.

While a specicembodiment of the invention has been-described, it is to be understood that variations in structural detail within the scope of the claims is possible and is contemplated. rll-here -is no intention, therefore, of -limitation to the exact details shown and described.

What is claimed is:

l-. In a device of the character described, a `balance beam rotatable about a -fulcrum, means for mounting a receptacle to be filled on said beam to one side of said -fulcrum, counterbalancing means `for fsaid beam, one way valve means in said mounting means and said receptacle also having one way valve means, latchcontrolled means vto move said valve means linto open condition and to maintain said open condition during filling of said receptacle, means for delivering -lling fluid from a source into said receptacle through said valve means, and means responsive to the position of said beam for releasing said latch-controlled means when said receptacle has been filled with a prescribed weight of filling fluidi 2. In a device of the character described, a balance beam rotatable about a fulcrurn, means for mounting a receptacle to; beV iilled on said beam to one side of said iulcrum, counterbalancing means for said beam, one way valve means in said mounting means and said receptacle also having one way Valve means, latchcontrolled means to move said valve means into open condition and to maintain said open condition during -lling of said receptacle, means for delivering filling fluid from a source into said receptaclethrough said Valve means, means responsive tothe position of said beam for releasing said latoh-controlled means when said receptacle has been lled with a prescribed weight of filling uid, and means to restore said valve means to closed condition.

3. In a device of the character described, a balance beam, means for mounting a receptacle to be lled on -said beam, valve means in said means, a pump for forcing lling liquid from a source into said receptacle to be filled through said valve means, a coiled conduit connecting said pump and said valve means to eliminate sub- Stantially all torque resisting free motion of said balance beam, counterbalancing means for said beam, and means responsive to the position of said balance beam to effect closure of said valve means when said receptacle has been filled with a prescribed weight of the lling iiuid.

Il. In a device of the character described, a balance beam rotatable about a ulcrum, means for mounting a receptacle to be lled on said beam to one side of said iulcrum, counterbalancing means for said beam, one way valve means in said mounting means and said receptacle having a similar valve, a lever pivotally carried by said beam, a latch member pivotally carried by said leverand engageable with a part of said beam, a fixed stop in the path of travel oi another part of said latch member, means engageable with a portion of said lever for moving said valver'neans to open condition in one position of said lever, said latch means then engaging said part ofsaid beam and maintaining said position of said lever and the open condition oi said valve means during filling of said receptacle, and means for delivering iilling duid from a source into `said receptacle through said valve means, said fixed stop serving to release vsaid latch member when said receptacle has been filled with a prescribed weight of duid-and has moved said balance beam about said ful- 8 Crum a deter-mined distance in opposition to said counterbalancing means.

5. In a device ofthe character described, a bal'- ance beam rotatable about a iulcrum, means for mounting a receptacle to be filled on said beam to one side of said fulcrum, counterbalancing means for said beam, one way valve means in said mounting means and said receptacle having a similar valve, a lever pivotally carried by said beam, a latch member pivotally carried by said lever and engageable with a part of said beam, a iixed stop in the path of travel of another part of said latch member, means engageable with a portion of said lever for moving said valve means to open condition in one position of said lever, said latch means then `engaging said part of said beam and maintaining said position of said lever and the open condition of said valve means during lling of said receptacle, a pump for delivering iilling iiuid from a source into said receptacle through said valve means, and conduit means connecting -said pump and the valve means in said mounting means and which means is free from reaction resisting -free motion of said balance beam on its fulcrum, said fixed stop serving to release said latch member when said receptacle has been filled with a prescribed weight of fluid and has moved said bal'- -ance beam about said ulcrum a determined distance in opposition to said counterbalancing means.

6. In a device of the character described, a balance beam, means for mounting a receptacle to be illed on said beam, valve means in said means, means for forcing lling fluid from a source into said receptacle to be lled through said valve means, ltering means for 'said-fluid, counterbalancing means for said beam, and means responsive to the position of said balance beam to effect closure of said valve means when said receptacle has been lled with a prescribed weight of the filling fluid.

7. Ina device of the character described, the subcombination including, a guide shell for receiving a receptacle to be filled and having a nipple containing a valve, a hollow member carried by said shell and having a threaded opening to receive said nipple, a tubular member mov-- able longitudinally of said hollow member, one way valve means in said tubular member, spring means biasing said valve means normally to a closed position, spring means biasing said tubular member normally outwardly of said hollow member, means limiting the biasing action of said last-named spring means, and a hollow rod extending outwardly of said hollow member and engageable with the valve within said nipple to open the latter and said first-named one way valve means when said tubular member is moved in opposition to said second-named spring biasing means.

8. In a device of the character described, the combination including, a guide shell for receiving av receptacle to be filled and having a nipple containing a valve, a hollow member carried by said shell and having a threaded opening to receive said nipple, a tubular member movable longitudinally of said hollow member, one way valve means in said tubular member, spring means biasing said Valve means normally to a closed position, spring means biasing said tubular member normally outwardly of said hollow member, means limiting the biasing action of said lastnamed spring means, a hollow rod extending outwardly of said hollow member and engageable aeoasve with the valve contained by said nipple to open the latter and said first-named one way valve means when said tubular member is moved in opposition to said second-named spring biasing means, means for so moving said tubular inember, latch means for retaining said tubular member in such moved position, means for forcing filling iiuid from a source through said valve means and said receptacle, and means responsive to the weight of said receptacle increasing to a predetermined weight for releasing said latch means.

9. In a device of the character described, means for mounting a receptacle to be lled, a balance beam Supporting said means, valve means within said mounting means, latch-operated means for opening said valve means, means including a pump for transferring lling fluid from a source to said receptacle to be lled, and means responsive to the position of said balance lever for releasing said latch-operated means to permit closing of said valve means when said receptacle has been lled with a prescribed weight of the filling fluid.

10. In a device of the character described, l,

means for mounting a receptacle to be filled, a balance beam supporting said means, a counterweight carried by said beam, valve means within said mounting means, latch-operated means for opening said valve means, means including a .Y

pump for transferring filling fluid from a source to said receptacle to be lled, and means responsive to the position of said balance lever for releasing said latch-operated means to permit closing of said valve means when said receptacle has been filled with a prescribed weight of the lling fluid and has overbalanced said counterweight.

11, Apparatus for filling a fluid receptacle having a dispensing outlet projecting therefrom and providing a passage in which there is an inwardly facing valve seat and a valve biased outwardly thereagainst for opening by a removable operator pushed thereagainst through said passage with the latter having a gasket for sealing around this operator, said apparatus including a downwardly movable vertical outer tubular member having in its top an upwardly pointing recess adapted for receiving and releasably engaging said outlet to thereby support said receptacle, a vertical inner tubular member vertically reciprocatively arranged in said outer member with a spring urging the former downwardly relative the latter and a retainer for preventing the former from separating from said outer member while permitting thus limited relative downward motion, a downwardly facing feeder valve seat in the upper portion of said inner tubular member and a feeder valve biased upwardly thereagainst, a tubular rod extending from said feeder valve up through said feeder valve seat in a iiuid tight reciprocative manner and up into said recess with at least its upper portion sized and shaped to pass through said reoeptacles valve operator gasket in a fluid tight manner when said receptacles valve operator is removed and said rod being adapted to communicate with the relatively opposite sides of both said valve seats when both said valves are forced therefrom, said inner tuhula-r member being adapted to be fed with fluid beneath its said valve seat, a snap acting retainer for holding said inner tubular member upwardly when said outer tubular member is at an up position and which is movable with said outer member, means engaging and releasing said retainer when the latter moves with said outer member and means for biasing said outer tubular member at said up position with a predetermined force.

WAINWRIGHT TUTTLE. NILS OTTO LOVEN.

REFERENCES CITED The following references are oi" record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,511,604 Ganucheau Oct. 14, 1924 1,631,957 Fortier June 14, 1927 1,804,445 Stevens May 12, 1931 1,871,075 Mott et al Aug. 9, 1932 1,875,053 Locke Aug. 30, 1932 2,157,197 Van Duyn May 9, 1939 2,212,379 Smith Aug. 20, 1940 2,331,153 Ackley Oct. 5, 1943 2,408,842 Garretson et al. Oct. 8, 1946

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