US2575506A

US2575506A - Self-washing centrifuge

Info

Publication number: US2575506A
Application number: US678911A
Authority: US
Inventors: Russel D Acton
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-06-24
Filing date: 1946-06-24
Publication date: 1951-11-20
Anticipated expiration: 1968-11-20

Description

1951 R. D. ACTON SELF-WASHING CENTRIFUGE 2 SHEETS SHEET 2 Filed June 24, 1946 7206723 525 fiezsseZZ afczoza.

@; Paula/ A Patented Nov. 20, 1951 UNITED STATES" PATENT OFFICE sELF-WAsHmc CENTRIFUGE Russel 1). man, Chicago, 111.

Application June 24, 1946, Serial No. 678,911

21 Claims. (01. 233-4) 1 individually washing the components thereof,

particularly the disks used in most cream separators at the present time. Attempts have been made to rinse the devices with washing liquid without providing any auxiliary valve structures. These attempts have not been satisfactory due to the low velocity with which the washing liquid passes over the surfaces which accumulate slime and other deposits. ther attempts have been made to provide self-washing cream separators by providing auxiliary valves in the periphery of the bowl structure with all surfaces slanting toward the valve openings whereby, upon opening the valves, washing liquid will be delivered at high velocity over all surfaces of the separating structure.

The principal object of the present invention is to provide improved self-washing cream separator devices of a type in which valve means are provided for opening the bowl structure at its periphery during areduced speed of operation.

Another principal object is to provide diverting means for supplying milk through one path for a separating operation and to supply washing liquid through another path during a cleaning operation.

Another object is to provide washing liquid directin means whereby a minimum amount of washing liquid may be added directly through the supply means for liquid to be treated and distributed uniformly to the edges of separating disks.

A more specific object is to provide a manually movable valve means for diverting washing liquid to the edges of a disk pack.

Another more specific object is to provide a. diverting valve structure automatically operable by centrifugal means to divert washing liq-- uid to the disk edges simultaneous with the opening of valves in the periphery of the bowl structure for the discharge of washing liquid.

Another specific object is the provision of valve structure operable by a speed change in the bowl structure to overrun the bowl structure as the construction with a portion broken away in section to show theinterior of the bowl structure;

Figure 2 is a plan view taken on the line 22 of Figure 1;

Figure 3 is a combined elevation and sectional view showing another modification;

Figure 4 is a view taken on the line 44 of Figure 3;

. Figure 5 is a view similar to Figure 4 with the valve member in a different positon.

Centrifugal devices have been long used for many purposes particularly for separating cream from whole milk. Such devices have become rather standardized, most types now utilizing a plurality of closely spaced, nested, conical disks. The disk pack is mounted in a bowl structure which is rotated at a high speed by suitable driving mechanism, usually around 9000 R. P. M. Because of the well known use of such structures, the drawings are somewhat diagrammatic except for the illustration of the specific parts of the bowl structure in which the invention is involved. In Figure l certain of the exterior parts of a separator construction are shown, these parts usually being referred to as the sheet metal ware. -A dome-shaped sheet metal housing ID has a bead ll adjacent its lower extremity providing a flange l2 beyond the bead which slidably fits into a cylindrical wall l3, said wall, together with an annular interior deflector member 14 and a spout I5, comprise means for receiving and delivering skimmed milk with is delivered against the housing in and downwardly therefrom. The wall I3 is provided near its lower edge with a bead l6 and a flange portion H extending beyond the bead. Said flange portion fits in a cylindrical wall l8 which, together with an annular deflector l9 and a spout 20, comprise means for receiving separated cream. The supporting structure for the sheet metal ware has not been illustrated as it may be of any conventional construction many forms of which are well known in the prior art.

A spindle 20, which is to be driven by any conventional means as used in high speed centrifugal devices is provided with a shoulder 20" to provide for mounting the bowl structure of the device for rotation. Said bowl structure, which will be referred to in its entirety by the reference character B, consists essentially of a conical outer shell 2|, a base structure 22, and a plurality of nested conical disks 23. The base structure 22 is fitted on the spindle 20' against the flange 20" for rotation at high speed with the spindle. Said base structure has an outer portion 24 which extends upwardly at an angle beyond the outside terminal edges of the disks 23. Said portion is generally conical and meets the shell portion 2| abutting thereagainst. A plurality of spaced openings, one of which, 25, is visible, are provided around the abutting portions of said members to provide outlet means from the interior or inner compartment formed within the bowl structure.

An annular member 26 has a flange portion 21 overlapping :theperipheral edge of the shell 21 for clamping-said shell in position against the base structure. The annular member 23 is threaded onto the peripheral edge of the upturned portion 24 of the base structure. vAplurality of openings 28 are provided inthe annular member 2? for the escape of liquid passing-outwardly through the passages 25.

An annular rubber ring 29 is illustrated for providing valve means. Said member has aaplurality of spaced projections 30 which engage the .inneresurfacesof the shell 2| and the upturned ;portion24 of the basestructure spaced from their inner section. The ring 29 is of such resilience and the projections 36 are so positioned and spaced, that upon the exertion of centrifugal force on the ring 29 by high speed rotation of the bowl, said ring extends and fits against the inner surface of the shell 2i and the inner surface of the portion 24 to effect a seal against the escape of liquid during the separating operation. Upon (a reduced-speed of operation for washing, said ring releases to permit the escape of washing liquid through the passages 25 and the openings 28. This peripheral outlet valve construction is a part of this invention onlygenerally as to the provision of means for permitting the escape of washing liquid at the peripheral portion of the bowl structure. The disk 23 may be supported in position by any conventional means. One web. 3|, is shown in Figure l for engaging the edges of the disks. Said web is also provided with circular notches 32 for maintaining the ring 29 in position.

. An upper cream separating disk 32' is illustrated which overlaps the other disks which are of uniform size to provide an internal .annular channel for the collection of cream. ,As said creamcollectsatthe inner edges of the disks and builds up a layer therein, it passes downwardly and out of the bowlthrough a channel 33 .formed at anangle in the base structure 22 of .the bowl. Themilk which passes upwardly .along the inside of .the shell 2i and outside of the dividing disk .32 discharges through an adjustable .milk outlet channel .33 providedat .the top .of .the shell 2 l.

The inner edges of the disks 23 provide a generally unobstructed cylindrical space 34. Said space is limited at the top bythe dividingdiskfiz and at the .bottom .by an annular member 35 which has a central opening .36 .and a .downturned flange 31 fitting into a recess formed .in the .base structure .22. The opening 33 registers with a distributer chamber 38 .formed inthe base structure 22. Said distributer chamber has a plurality ofoutlets, one of which,.39, is .visiblein Figure 1; said .outlets extending radially and registering with a distributer channel i l provided by a plurality of aligned openingsllfi in thedisks 23 eccentric with respect to their centeropenings. This is a conventional construction for cream separators.

Thedistributer chamber 38 has a raisedcenter portion 4| formed integrally with the base structure, which has a flat top portion 42. The top portion 42 lies a substantial distance below :the annular member 35-and the distributer chamber shape is further altered by undercutting in an outwardly direction to form a curved wall A3 wherebyany liquid discharged from thesurface .42 will be deflecteddownwardlyand retained .in

offof the rotating surface 42.

the distributer chamber until it is discharged through one of the outlets 39. A liquid supply receptacle 45 is provided with a tubular extension 46 which slidably fits into a cylindrical neck 47 formed 'on-thehousinglfl. ZIn-the position shown in the drawings the bottom of the receptacle 45 fits into a flange 48 formed on the neck 4?. A

manually operable member 43 slidable through a 34 and is provided at its lower end with an in- Wardly tapered or restricted-delivery end portion Said end portion, as shown in full lines in Figure 1,.overlapsthe top surface 42 of .the upwardly extending portion 4| in the distributer chamber 38 whereby liquid delivered from-said surface during rotation will engage the inner conical wall of said end and will be delivered upwardly thereby.

Within the space 34 and for the entire axial extent of the inner edges of the disks 23, the

supply tube 5| is of a foraminous construction being provided with radial outlets illustrated as a plurality of narrow axially extending opening means in the form of slits 53. Above the dividing disk 32, a plurality of openings 54 are provided in the supply tube 5!. The tube 5! formed with the slits-.53 and the openings 54 provides foramin- -ous means extending throughout the center of .the bowl to deliver washing liquid radially out- Wardly when the fiow is cutgoff through the distributing chamber 38. A restriction 55 is formed in-the supply tube above said openings to deliver .fluid-in a stream of substantially less diameter than the slitted lower-portion of thesupply tube wherebyisaid stream of liquid will initially badelivered to the restricted lower end of said supply .tube.

In;normal operation of a cream separator as above described andas shown inlFigure 1, milk to be separated will be delivered through.the.sup

.plytube'5l and due to the restriction 55 will be delivered as a stream at the restricted lower end .52 of the supply tube which will be in the dottedlinepositionas shown in Figure 1. The milk;will be discharged from said end into the distributer chamber and will be discharged therefrom through the outlets 39 and tothe channels Allfor separation in the conventional manner.

When the separatoris to be washed after completionof a separating operation, the supply tube being axially shiftable is dropped to .the position shown in;Figure 1 by withdrawal of the member .49. Wash liquid is then delivered through the supply tube 5!. Asthe restricted end ;52 of the milk tube in cooperation with the upstanding portion '4! within the .distributer chamber forms a valve means to cut off and toblock the flow of liquid through .the distributer chamber, the liquid will build up in the tube 5! assisted by the centrifugal force of impinging liquid delivered Liquid will then build up in the tube 5| and will flow outwardly through theslits 53 and the openings 54. These streams of liquid will impinge against the inner its operation as explained, a relatively small quantity of wash liquid is effectively delivered to the inner edges of all of the disks to obtain a satisfactory washing action. Liquid is also discharged through openings 54 to other parts of the separator for cleaning other passages. A certain amount of liquid will also escape through the distributer chamber, cleaning these parts of milk and accumulated slime.

Figure 3 represents a modification in which a different type of flow control means, or valve means, is utilized for altering the fiow path of liquid through the bowl structure for a washing operation. In Figure 3 a spindle 56 carries a bowl structure including a base 51 and a shell 58 secured together by a clamping member 59 identical in structure with the clamping member 26. It is to be understood also that the same annular ring valve and outlet means would be provided in the modification of Figure 3, such structure not being shown as said figure shows in elevation the outer portions of the bowl structure.

The base structure 51 is formed centrally with a distributer chamber 59 having a plurality of discharge outlets 60. Said outlets are adapted to register, as shown in Figure 3, with radially disposed openings or passages 61 formed in an annular valve member 62 mounted for limited angular movement or rotation in an annular chamber 63 formed concentric with the distributer chamber around the upper portion of the base structure 51 An annular member 64 has an upturned flange 65 extending above the distributer chamber 59' and a conical, downwardly extending portion 66 overlapping the recess 63 and forming therewith a closed compartment for the member 62. The conical portion 66 of the member 64 is provided with openings 61 registering with channels 68 formed by a plurality of aligned openings 68' in nested disks 69 which constitute a disk pack for carrying on a separating operation. At the top of said disk pack, a dividing disk I is provided, said disk having a flange ll extending inwardly and overlapping a cylindrical space H formed by the aligned inner edges of the disks 69.

The valve member 62 is provided with a slot or recess 12 into which a pin 13 extends. Said pin permits relative or overrunning angular movement of the member 62 with respect to the base structure 51 in the recess 63 a sufficient angular distance to substantially block the outlets 60 as shown in dotted lines in Figure 5. In this position only a small portion of liquid flows through the distributing chamber 59.

A supply tube 14 coaxial with the bowl structure and adapted to be supported and held stationary by any conventional means such as the means shown in Figure 1, extends inwardly within the bowl structure as far as the dividing disk 10. A concentric tube I of substantially greater diameter than the tube 14 is secured thereto and extends downwardly pinto overlapping relation with respect to the flange 65 in closely adjacent relation thereto to restrain the flow of liquid between the end of said tubular structure and the adjoining portion of the bowl structure which in the structure shown in Figs. 3 and 6 is the flange 65. Discharge openings are provided in the tube 15 throughout its length by means of a plurality of narrow slits 16. Said slits extend substantially the entire height of the disk pack whereby liquid discharged through said slits reaches the edges of all of the disks.

A cream discharge passage 14' is provided in the base structure 51. A milk discharge outlet 1551s provided at the top of the shell 58.

The operation of the modification shown in Figure 3 will be readily understood from the description of the component parts. Milk delivered through the supply tube 14 is discharged as a stream directly through the distributer chamber 59 from whence it flows outwardly through the outlets 60 and the passages 6| which register with the outlets 6|! to the channels 68 for separating in the conventional operating manner of a conical disk type of separator. This action takes place when the separator is operated at uniform speed. When it is desired to wash the separator the poweris cut off whereupon the bearing friction and air friction of the bowl structure starts de celerating the speed of the bowl structure, the valve member 62 being freely mounted and not being subjected to the same degree of resistance, upon a predetermined change in speed of the bowl structure overruns from the position shown in Figure 7 to the position shown in Figure 8, thereby closing the outlets 60 and stopping the flow of liquid from the distributer chamber. When the bowl structure is being brought up to separating speed, the valve member lags behind and moves back to the position of Fig. '7 to open the outlets 60 for the. flow of liquid from the distributer chamber. The wash liquid then being supplied builds up within the concentric tube 15 and discharges therefrom radially against the disks. The washing operation then takes place in the same manner as in the modification of Figure 1 with the peripheral outlet valves opening as the speed of the bowl structure decreases.

The diiferent modifications of applicants selfwashing bowl construction for centrifugal devices are preferred embodiments of his novel valve means for altering the path of liquid flow during a separating operation and during a washing operation, all modifications, however, falling within the appended claims are contemplated as a part of the invention.

What is claimed is:

1. A bowl construction for a self-washin centrifugal separator comprising a bowl structure formed with a compartment therein, a stack of spaced conical disks mounted in said compartment, said disks having aligned center openings to provide a generally cylindrical space extending axially of the bowl structure, a distributer chamber formed in said structure at the bottom of said cylindrical space, said distributer chamber being provided with radially delivering outlet means, said disks being formed with aligned openings eccentric to the center openings and communicating with said outlet openings means, foraminous means extending through the cylindrical space and to the distributer chamber for supplying liquid thereto, and means for blocking flow of liquid through said distributor chamber thereby diverting the liquid flow from the distributer chamber through the foraminous means.

2. A device as set forth in claim 1 in which means are provided for holding the liquid supplying means against rotation.

3. A device as set forth in claim 1 in which outlet means are provided at the periphery of managers #7 the bowl structure operable 'to discharge liquid therefrom at one speed of oper'ation.

4, A device as set forth in' claim -1 inwhich the foraminousmeans is a tube having a slit extending axially thereof.

5. :A- deviceas setlforth in claim -1:.in which the liquid supply meansiincludes anon-rotatable tube extending:downwardly to' th'e'top of the disklpack and:a:concentric tube of larger diameter-extending from the first tube to thedistributer chamber, said second tube being provided with discharge openings ior-radial delivery Of-liquidupon operation of the 'means for blocking the flow f liquid through the distributor chamber.

6. 'A bowl constructioni'for aself washing cen- Ztrifugal :separator comprising a bowl Estructure iorm'ed' witha compartment therein, a stack of spaced conical disks mounted in said icompartment, saiddislrs having aligned center openings to provide an unobstructed cylindrical-space extending axially of the bowl structure, a idistributer chamber formed in-said structure'at the bottom of said cylindrical space, said distributor chamber being provided with radially delivering outlet means, valve means operable to close said outlet :means, said disks being forme'dwith aligned openings eccentric with respect tolth'e center openings -and communicating with said outlet means, means for supplying liquid to the distributer chamber, said'm'eans being operable upon closing 'of 'the valve means to thereafter supplyliqui'd to the interior of the cylindrical space and to the inner edges of the'disks.

7. Adevic'e as set forthiin claim 6 in which the liquid supply 'means is a tube extending downwardly through the cylindrical space and to the distributor chamber, said tube being provided with openings for discharging liquid therefrom opera'ble w'henthe valve means close the distribiut'er chamber outlet'means.

8. A device as set-forth in claim din which the liquid supply means includes a non-rotatable tube extending downwardly to th'e'top of the disk pack and aconcentric tube of larger'diameter extending from the first tube to the "distributer chamber, said second tube being provided with discharge openings 'forra'dial delivery of liquid upon closing inf .th'e valveimeans.

9. A device as set forthiin claim 6 in which the valve means for the outlet zmeans of "the distrib- -uter chamber is'a member mounted for limited angular movement with respect to 'thebowl structure about-the same axis, said member being constructed to regulate fiowthrough the outlet. means "by over-running movement withrespect to theremaining bowl structure. 7 a

10. A device as set forth .in claim-6 'in'which the valve means includes anannular valve member carried for limited relative rotation with'respect to the bowl structure on the same'axis, said valve means being operative to control liquid flow throughthe distributor chamber by over-running movement of said member .upon predetermined changes in thespeed of the bowlstructure.

11. A device as set forth in claimo in which the valve means is an annular valve member mounted for limited relative angular movement with respect to the bowl structure and around the distributer chamber, said member having radially disposed openings adapted to register with the outlet means in the distributor chamber in one angular positioh and to close saidoutlet means in another angular position. 1 12. A bowl construction for aself-washingcen- -=tri'fugal separator comprising a bowl structure formed withiaicompartment therein,='alstack of spaced conical disks amounted in :said -.compar.tmerit, said disks having aligned center openings providing-agenerallylcylindrical space extending axially .of thelbowl structureaa distributerchamber formed in said structure at the bottom ofzsaid cylindricalispace, said distributor chamber being provided withloutletiopenings extending radially fromatheicentrakportion thereof, said disks being 19 formed'with aligned openings eccentric with-mespect to :the center" openings and communicating withsaidaoutletmeansfrom-the distributer chamber, a liquid supplytube adapted to extend downwardly into saiddistr'ibute'r chamber, said tube 5 being provided with Laxially arranged 1 openings,

and said tube having-an annular:imperforateibottom portion and being adjustable from a "lower position with :the bottom portion extending :into the liquid distributing chamber withsaid bottom 20 portion arranged in-a liquid flow :blockingposition with respect'to the distributing chamberto an upper position with said tube terminating above said'distributer chamber, whereby in the raised position liquid to-be separated may be dis- 5 charged into the distributing chamber andradially outwardly {therefrom and whereby when the tube is in the lower position liquid will be restrained from movement'out-of the distributer chamber whereby the tube fills'with liquid which discharges radially therefrom through the openings, whereby the'liquid engages :the inner edges of the'diskpack, and -means in said bowl structure at the periphery thereof for releasing the liquid therein upona lower speed of the bowLwhere- 3 5 by the disks may-be washed by the liquid delivered through the openings in the supply tube.

13. A device-as set forth in-claim l2=in which the liquid supply tube is stationary with-respect to the bowl structureduring washing operation.

:14. A device as set forth in claim 12 in which the opening means in-the tube includes a-continuous .narrow slit extending longitudinally of the tube coextensive with the disk pack.

15. A device as set forth in claim 12in which the supply tube is provided with a restriction above the top of the disk pack whereby liquid passing 'therethrough dropszdownwardly intact as a streamof smaller diameter than theinteriorof the-tube below the restriction.

5O 16. Abowlconstructionfor a self-washing centrifugal separator comprising a bowl structure formed with :a compartment therein, a stack-of spaced conical; disks mounted in said compartunent, saiddisks having aligned center openings whereby the innerdisk edgesprovidea generally cylindrical space extending axially of the bowl structure, a distributor chamber formed in said structure at the bottom of said cylindrical space, said=distributer chamber being provided with out- :let 'openings extending radially from the central portion thereof, said disks being formed with aligned openings eccentric with respect to the center openings and communicating with said outlet means from the distributer chamber, a G5 .raised center portion ;in the distributor chamber :providing an annular surrounding bottom channel "in the distributer chamber, a liquid supply tube Padapted to extend'dowriwardly into said annular channel, said tube having'an inwardly tapering 7 b'otto'm portion of reduced diameter, said portion being adapted ito extend below and around the raised center portion in the "distributor chamber, whereby 'liqui'd thrown therefrom encounters said tapering portionpwhereby the liquidis forced upwar'dly into "-thetube, said 'tube being provided with axially extending opening means and said tube being adjustable from a lower position with the bottom portion extending into the liquid distributing chamber to an upper position with said tube terminating above said distributer chamber, whereby in the raised position liquid to be separated may be discharged into the distributing chamber and radially outwardly therefrom and whereby when the tube is in the lower position liquid will be restrained from movement out of the distributer chamber and will be forced upwardly into said tube whereby the tube fills with liquid which discharges radially therefrom through the opening means whereby the liquid engages the inner edges of the disk pack, and means in said bowl structure at the periphery thereof for releasing the liquid therein upon a lower speed of the bowl, whereby the disks may be washed by the liquid delivered through the openings in the supply tube.

17. A device as set forth in claim 16 in which the liquid supply tube is stationary with respect to the bowl structure during washing operation.

18. A device as set forth in claim 16 in which the opening means in the tube includes a continuous narrow slit extending axially of the tube coextensive with the disk pack.

19. A bowl construction for a self-washing centrifugal separator comprising a bowl structure formed with a compartment therein, a stack of spaced conical disks mounted in said compartment, said disks having aligned center openings whereby the inner disk edges provide a generally cylindrical space extending axially of the bowl structure, a distributer chamber formed in said structure at the bottom of said cylindrical space, said distributer chamber being provided with outlet openings extending radially from the central portion thereof, said disks being formed with aligned openings eccentric with respect to the center openings and communicating with said outlet means from the distributer chamber, a raised center portion in the distributer chamber providing an annular surrounding bottom in the distributer chamber, liquid supply means including a stationary tubular structure having a circular downwardly opening discharge conduit terminating at the top of the cylindrical space and a surrounding tube having an inside diameter larger than the inside diameter of said discharge conduit tube and extending to the distributor chamber, said tube having an inwardly tapering annular and imperforate bottom portion of reduced diameter, said portion being adapted to extend below and around the raised center portion in the distributer chamber, whereby liquid thrown therefrom encounters said inclined wall portion whereby the liquid is forced upwardly into the tube, said tube being provided with an axially arranged opening means coextensive with the edges of the disk structure, and said tube being adjustable from a lower position with the bottom portion extending into the liquid distributing chamber to an upper position with said tube terminating above said distributer chamber, whereby in the raised position liquid to be separated may be discharged into the distributing chamber and radially outwardly therefrom and whereby when the tube is in the lower position liquid will be restrained from movement out of the distributer chamber and will be forced upwardly into said tube, whereby the tube fills with liquid which discharges radially therefrom through the openings, whereby the liquid engages all interior surfaces of the inner edges of the disk pack, and means in said bowl structure at the periphery thereof for releasing the liquid therein upon a lower speed of the bowl, whereby the disks may be washed by the liquid delivered through the openings in the supply tube.

20. A bowl construction for a self-washing centrifugal separator comprising a bowl structure formed with a compartment therein, a stack of spaced conical disks mounted in said compartment, said disks having aligned center openings, the edges of the disks around said openings providing a generally cylindrical space extending axially of the bowl structure, a distributer chamber formed in said structure at the bottom of said cylindrical space, said distributer chamber being provided with radially delivering outlet means, said disks being formed with aligned openings eccentric to the center openings and communicating with said outlet opening means, tubular fluid supply means extending through the cylindrical space and to the distributer chamber arranged and constructed to supply liquid to be separated therethrough to the distributer chamber, said supply means having openings over an area axially coextensive with the cylindrical space, and valve means operable for a washing operation to block flow of washing liquid to the distributer chamber thereby diverting the liquid flow from the distributer chamber through the openings in the supply means to the edges around the center opening of the disks.

21. A bowl construction for a self-washing centrifugal separator comprising a bowl structure formed with a compartment therein, a stack of spaced conical disks mounted in said compartment, said disks having aligned center openings, the edges of the disks around said openings providing an unobstructed cylindrical space extending axially of the bowl structure, a distributer chamber formed in said structure at the bottom of said cylindrical space, said distributer chamber being provided with radially delivering outlet means, a valve means for said distributer chamber for regulating the flow of fluid through said outlet means, said disks being formed with aligned openings eccentric with respect to the center openings and communicating with said distributer outlet means, means for supplying liquid to the distributer chamber, said means being operable upon closing of the valve means to thereafter supply liquid to the interior of the cylindrical space and to the inner edges of the disks.

RUSSEL D. ACTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 509,185 Salenius Nov. 21, 1893 802,724 Adams Oct. 24, 1905 2,091,329 Nyrop Aug. 31, 1937 2,173,579 Fawcett Sept. 19, 1939 2,173,580 Fawcett Sept. 19, 1939 2,256,316 Eddy Sept. 16, 1941 FOREIGN PATENTS Number Country Date 23,115 Great Britain May 9, 1912 3,957 Germany May 23, 192i