US2651368A

US2651368A - Plug and valve device for casing apparatus

Info

Publication number: US2651368A
Authority: US
Inventors: Reuben C Baker; Austin Benjamin Lewis
Original assignee: Baker Oil Tools Inc
Current assignee: Baker Hughes Oilfield Operations LLC
Priority date: 1948-04-23
Filing date: 1949-11-14
Publication date: 1953-09-08
Anticipated expiration: 1970-09-08

Description

R. C. BAKER ETAL PLUG AND VALVE DEVICE FOR CASING APPARATUS Sept. s, 1953 2 Sheets-Sheet 1 Original Filed April 23, 1948 5 P a a i? e s y M2M if M. if i c f -l REL/@EN Ci BA .JA

y c n Y BY rraeA/EYS Sept. 8, 1953 R. c. BAKER ETAL 2,551,363

PLUG AND VALVE DEVICE PoR cAsING APPARATUS original Filed Aprii 23,V 1948 2 sheets-sheet 2 19e-usan CI BAKER,

BENJAM/N. Ew/.sasr/M IN VEN TORS.

mM/zwwmw @Trae/Veys Patented Sept. 8, 1953 PLUG AND VALVE DEvioE Fon, OASING APPARATUS Reuben CLBaker, Coalinga, and Benjamin Austin,- Long Beach, Calif., assgnors to Baker Oil Tools, Inc.,` Vernon, Calif., a corporation of California Original application Ap ril 23", 1948, Serial No.

22,886. Divided -and this application November 14, 1949, Serial No.- 127,190

The present invention relates to subsurface well devices, and more particularly to plug and valve members adapted to be lowered through the well bore into engagement with a cooperable valve seat therewithin.

This application is a division of our application for Positive Shut-01T Ported Casing Apparatus, Serial No. 22,886, led April 23, 1.948.

An object of the present invention is to DIJO'- vide plug or valve devices particularly useful in closing the central passages through members disposed in a well casing or the like, which enables fluid to be relieved or dissipated that would otherwise be entrapped at one side of' the members.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied.

Such forms are shown in the drawings accompanying and forming part of the present sleoication. These forms will new be described in detail, illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken ina limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a longitudinal section through a ported well apparatus, with the ports closed and 'the parts arranged for running the 'apparatus in a well bore;

Fig. 2 is a View similar to Fig. 1', with` the ports open;

Fig. 3 is a View similar to Fig. 1', with the ports reclosed;

Fig. 4 is an enlarged section through a plus' or valve device used in connection with the lower inner sleeve valve member Fig. 5 is a view similar to Fig'. 4 of another embodiment of plug or valve device.

As disclosed in the drawings, a casing collar A has its upper and lower ends threaded-ly conmaterial i3, to serve a purpose described below.

Thev tubular member l-D has a plurality of eircularly spaced side ports l 4` through which fluids are adapted to pass between. the interior and exterior of the collar apparatus. These ports are closed. initially by a lower inner sleeve valve member' I`5v having seal rings I6, Il disposed in suitable ring grooves I8 on opposite sides of the ports. These rings' maybe of rubber and of round cross-section to prevent leakage thereby in bothlongitudinal directions.

The lower inner sleeve valve member I5 is retained in position. to locate its seal rings I6, Il on. opposite sides of. the ports I4 by one or more irangible devices in the form of shear screws t9` threaded through the tubular member in' and1 extend-ine into the valve member.

It is t'o be noted that the. inside diameter of the'V tubular member I0, at the region Where it is engaged by the lower seal ring il, is lessy than the internal. diameter of a groove 23 in thel member I0 immediately below this' region. Also, the sleeve valve member I5 is reduced .in external diameter to form a peripheral. groove 24 below the lower seal ring t1, in which a split, inherently expansi'ble stop ring. 25 is located. 'Ihe stop ring has an upper inner inclined surface 2.6 tapering downwardly and inwardly for cooperation with a corresponding tapered surface 21 on thebase of the peripheral groove 2.4. The length of the groove 24 is much greater than the. length of the stop ring' to permit downward movement of the sleeve valve member I5: relative to the stop ring'.-

The stop ring 2,5 is received within the enlarged diameter portion 2'3- of the tubular member. This enlarged portion isv much longer than. the height of' the stop ring.A The stopring may rest upon ashoulder 28 provided by the lower end of the' peripheralgroo-ve 24, the upper end of the stop ring being engageable with an upper shoulder 29 of the peripheral groove 24. Downward movement of the stop ring is limited by its engagement with a shoulder 3U form-ed by the lower end of' the tubular member groove 23.

The shear screws i9 are adapted to be' disruptedv and the lower inner sleeve valve member I5` moved downwardly to` a position ini Wh-ioll the uppervse'al ring r6 is disposed below the portsl i4.

The ports arel thenopen tothe passage of fluids between thel interior and exterior' of the apparati-1s.

After the ports have been opened, it is desired to reclosethem. To accomplishthis purpose,- an

'extern-al sleeve valve member 3i is provided on the tubular member n Y I-'ii". This external member has a plurality of' longitudinally spaced seal rings 32, 313 disposed in internal grooves 3tland slid- 3 ably engageable with the outer surface of the tubular member I0. The outer member 3| has an upwardly extending cylinder 35 integral therewith, or otherwise suitably secured thereto, which is slidable along an enlarged portion Illa of the tubular member.

The outer member 3I is retained initially in an upward position, in which it does not close the ports I4, by one or more shear screws 36 threaded through the cylinder 35 into the enlarged portion a of the tubular member. These screws are disruptable hydraulically by iiuid pressure, including fluid one or more elongate ports, slots or openings 31 in the tubular member into a cylinder space 38. This space is formed between the enlarged portion Illa of the tubular member, the cylinder skirt 35 and the part 31a of the sleeve valve member carrying the

seal rings

32, 33. a downward direction between the sleeve valve member 3l and tubular member I0 is prevented by the seal ring 32. Leakage in an upward direction therebetween is prevented by a seal ring 39 disposed in a peripheral groove 40 in the enlarged portion 10a of the tubular member, which sealingly engages the inner surface of the cylinder 35.

When sulcient hydraulic force is exerted on the outer sleeve valve member 3|, the shear screws 36 will be disrupted and the outer sleeve valve member 3I shifted downwardly to a position in which its

seal rings

32, 33 are located on opposite sides of the ports I4, closing such ports against passage of nuids therethrough in both directions between the interior and exterior of the apparatus. This position of the sleeve valve member 3I is determined by engagement of its depending skirt 4I with the upper end of the stop member I2. It is to be noted that the upper portion of the skirt 4l is spaced outwardly from the tubular member I0 so as to avoid interfering with passage of fluids through the ports I4 after they have been opened. This fluid flows through the ports I4 and through slots 41a in the lower end of the skirt. The end is slidable upon the member I0 and has a lower, knife-like edge 4Ib capable of cutting through any materials that might coat the member I0, or tend to prevent downward movement of the outer sleeve valve member 3I.

After the outer sleeve valvemember 3I has been shifted downwardly to port closing position, it is prevented from moving upwardly again by a latch or lock ring 42 disposed within a peripheral groove 43 in the tubular member I0 above its seal ring 33. This lock ring consists of a split, inherently eX- pansible member having a reduced diameter lower portion 42a forming a shoulder 44 with the upper `portion 42h. The shoulder is inclined outwardly in a downward direction to a slight extent.

When the outer sleeve valve member 3l has been forced downwardly to essentially its fullest extent, the upper end 35a of the cylinder is disposed below the shoulder 44 of the split lock ring, `but not below the larneter portion 42a. As a matter of fact, the 4upper part of the -ment with the outer surface of the reduced dilower end of its reduced dioylinder 35 will be in engageameter portion 42a, the lock ring 42 inherently expanding outwardly to a certain extent upon riding of the cylinder o its upper portion 42h, Any tendency for the outer sleeve valve member 3l to move upwardly will be limited by engagement of the upper cylinder end 35a with the lock ring shoulder 44, the lock ring being forced against the upper end of the peripheral groove Leakage under pressure entering through -,3l are open, fluid under 4 43. To insure against inward forcing of the lock ring 42 from engagement with the end 35a of the cylinder, the latter is tapered in the same direction as the shoulder 44, so that the two will remain in snug contact with one another.

The force of iluid under pressure is prevented from acting upon the external sleeve valve me ber 3l by an upper inner sleeve valve member 45 having longitudinally spaced seal rings 4B disposed in ring grooves 41 on opposite sides of the elongate ports or slots 31. |This valve member is held in position by one or more shear screws 48 threaded through the tubular member l0 into the upper valve member 45. Disruption of the shear screws 43 and downward shifting of the upper sleeve valve member 45 will expose the ports 31 and permit fluid under pressure to pass through the latter into the cylinder space 3B, in order to assist in shearing the cylinder screws 36 and moving the outer sleeve valve member 3I downwardly to port closing position.

The upper inner sleeve valve member 45 is not only used for the purpose of controlling the passage of fluid through the elongate ports 31, but is also used in assisting downward movement of the external sleeve valve member 3l to port closing position.

To accomplish this latter purpose, the upper inner sleeve valve member 45 and external sleeve valve 3l have an intervening lost motion connection. As specifically disclosed in the drawings, the outer sleeve valve 3| is formed with a plurality of inner keyways 80, in which are received the lug or arm portions 8I of keys 32 secured to the upper inner sleeve member 45 and extending outwardly through the elongate ports or slots 31. Each key includes a leg portion 83 depending from the arm portion GI and adapted for movement within the tubular member It with the upper inner valve member 45.

It is to be noted that the arm BI of each key is disposed originally abovevthe lower end or shoulder 84 of the keyway 83. This arrangement is provided for the purpose of permitting the inner valve member 45 to move downwardly to an ex- .tent sufficient to shift the upper seal ring 46 below the upper ends of the ports 31, and thereby allow fluid to pass into the annular cylinder space 38 for action upon the sleeve 3l to effect shifting, or at least assisting in shifting, the sleeve valve 3l downwardly to port closing position. As described in detail below, once the elongate ports pressure may enter the cylinder space 38 through these ports, disrupt the shear screws 36 and shift the outer valve member 3l downwardly to port closing position. If this hydraulic force is insuicient, then pressure may -be imposed upon the entire cross-sectional area of the upper inner sleeve valve 45, which will be transmitted to the external sleeve valve 3I through the keys 82 and abutting shoulders 84.

As stated above, the lower sleeve valve member I5 is held initially in closed position by its shear I9. Similarly, the upper sleeve valve in closed position over the elongate ports 31 by shear screws 48, preferably closely adjacent or in abutting relation with the upper end of the lower valve member I5. The

has a central bore 49 whose wall and inwardly. Similarly, the I5 has a downwardly and inupper valve 45 tapers downwardly lower valve member -wardly tapering central bore 50, which, in effect, Vforms a continuation of the upper member bore 45. The cylinder screws 3E hold the outer valve #member 3I in its upper position. The parts are all arranged as illustrated in Fig. il, occupying their relative positions for lowering the apparatus into Aa well bore.

With both sets of ports I4, 531 closed, a liuent material, vsuch as cement slurry, may be pumped directly into the casing string and through the central bores or passages `45, 50 in both sleeve valve members 45, l5, for discharge from the well casing at some point below the collar, as, .for example, 'from a casing shoe "(n'ot shown. 'This charge oi cement slurry will pass upwardly through the annulus around the casing string and may extend approximately 'to the location for the collar A, or slightly th'ereabove.

When it is desired to eject a :second or 'upper charge -of 4cement slurry through 'the collar ports H, a trip rdevice or plu-'g member 5I is dropped into the well casing and is allowed to gravitate through the fluid therein into engagement 'with the wall of the central .bore 50 in the lower lsleeve valve member I5. As disclosed 1in the drawings, this trip device may consist of a substantially spherical head v52 having a rubber, lor equivalent,

spherical seal member 53 clamped thereon by 'a suitable depending extension 554 threaded-on a neck 55 projecting downwardly from the head 52. The interior of the extension may be filled with lead 56, -or similar weighting material, to insure rapid gravitation or descent or 'the trip device 5l through the 'fluid the well casing.

'The seal 53 on the trip device has a lesser external diameter than the minimum diameter of the tapered bore in the upper sleeve valve member /4-5, to insure its complete 'passage through the latter. The spherical seal, however, has a diameter greater than 'the minimum diameter of the bore 50 through the lower valve member l5. As a result', the trip member comes to rest within the lower valve member with its 'head 532 and seal 53 closing its central bore or passage v5I). Pressure may now be applied to the fluid the casing above the trip member 5l and sleeve I5 1in 'an amount sulilicient to shear lthe screws I9 and shift the lower sleeve valve member l5 dow-n- 'wa-rdly to port opening position, as shown Fig. 2.

Downward movement Ior the lower valve member is limited by engagement of the stop zring v"25 -with the shoulder 3U of the tubular member I0,

and oi the shoulder 29 on the lower sleeve `mem- Y"ber i5 with the stop ring. Washing-fluid, Lfollowed 'by cement slurry or 4other cementitious maf- 'teriaL may -now be discharged outwardly 'through the open ports -I-Il, passing through 'the annular `space between the tubular 'member -ll land the depending skirt -IIAI of the outer valve `member '-3I, and through the 'slots lHa in the lower end'of this skirt, 'ffor upward movement through the annulus around the collar A and "casing string.

Upon discharging the required quantity of v'cement slurry, the outer sleeve valve 3l is forced 'downwardly to port closing position. This act may -be accomplished by placing a top (sementi-ng l'plug 5B at the upper v'end-of the charge of cement slurry pumped outwardly through the port-s H. This plug will come to rest within the bore E9 of vthe upper sleeve valve member '4"5, allowing the fluid in the casing string Aabove vthe collar to be pressurized to an extent suiii-cient for 'shear- -ing 'the screws f48, to shift the upper inner valve member lt5 downwardly to -a position in which the upper ends Yof the elongate ports 37"are open, u

The top cementing plug 58 disclosed jt'he drawings "is of a composite character. It Aincludes neslnm, aluminum or other-suitable, readily drillable material, lhaving a tapered periphery .650 adapted to `conform to the taper of the passage de in the upper sleeve 45. `This nose Vis so 'proportioned as 'to seat within the passage and vcause the top cementing plug 58 'to come vto :res-t therewithin. From its tapered nose, the lower and of the plug is :integral with a central shank 61 ter- .minating in a ilange 62, received within a companion bore and recess 153 :of a .flexible portion B5 or the cement-,ing plug. These two parts are 'suitably vulcanized together.

The Illegible plug o5 .is iformed essentially of rubber or .similar material. It Chas an imwardly compressible body portion :'10 donned by 'tapered iorward and rearward surfaces fII, "I2 .merguig into an yannular peripheral :sealing surface 13 slidably engageable 'with the wall of 'the well casing. The plug B5 also has a tail portion WI iterminatin'g in a fluted guide 1:5. Its annular .sealing portion includes an upwardly extending lip IS adapted 'to be forced outwardly .by nui-d pressure Aagainst the wall fof the casing.

The tapered nose :59 'on the lower plug :portion has la greater @dia-meter than the minimum diameter `through the upper .sleeve valve "45. As 'a result, it comes to rest 'within 'the tapered bore '4'9 of the latter, closing .it against :passage ofiiuid and allowing pressure .to be :built up in the y'casing iiuid above the cementing lplug 5a, suincient in extent to shear the `screws 48 and .shift the upper member '135 downwardly to a position .limited Aby engagement of the Akey lugs '81 with the shoulders 8f4 form-ing the flower `end of the keyways T80 in the outer sleeve 3ft. When in this position, "the iupper ends of the elongate ports 31 are exposed, allowing fluid to pass into the cylinder space 3'8 for the purpose of shearing the cylinder .screws 3'6 and moving the outer .sleeve 35'! downwardly to port 'closing position.

A standard top comen-ting plug would Inot permit ifi-uid to pass by it and :enter the ports j3*'I. 'The V.flexible plug 65 described above, however, will have its body I0 .and annular sealing portion 'I5 deformed inwardly to a suflicient extent to Acom- .'press the rubber material into the tapered passage 419 through the upper inner valve member 45, sealing off this vpassage completely, while removing the annular sealing portion 'II-3 of the plug lfrom engagement with 'the :casing wall or Sinner wall of the tubular member '-H). The plug, therefore, offers no restriction or barrier to 'passage vof lluid through the 'ports 31, for action upon the outer sleeve 'valve member 3 I..

In connection with the shifting of the 'outer sleeve valve .3l downwardly to vport closing position, several conditions might be encountered ,in the well bore, tending to resist this action. The upper inner sleeve valve d5 may be lshifted :downwardly Sto va position in which the ykey lugs '81| engage the lower shoulders 811 in `the outer sleeve valve member, which, as described above, opens the ports 31. The application -of 'pressure .to the lcasing fluid above the top cementing plug :58 not only acts upon the .annular cross-sectional area of fthe cylinder 35 'in the 4space 3-8, but also upon the entire cross-sectional area of the liexible'plug (i5-and inner sleeve memberd. This pressure disrupts the shear .screws i515 and fs'loifts the upper inner valve member d'5 land the outer valve member `3I downwardly as a unit, until the Vlower seal ring 3'3 on the outer member 'is disposed below the ports I4, thereby closing them. 'During movement or the outer lvalve .member v.il `and inner valve `member 215 to the position justV referred to, the fluid in the collar between the upper and lower valve members 45, I5 can pass outwardly through the open ports I4. However, since the lower seal ring 33 is now disposed below the ports I4, this fluid is trapped between the upper and lower sleeves 45, I5 and prevents further downward movement of the upper inner sleeve 45. Thereafter, the fluid pressure can act effectively on the annular cylinder 35 alone, to force the outer valve member 3l downwardly to port closing position, such as disclosed in Fig. 3. The lost motion connection 80, 8l between the inner and outer sleeves 45, 3| permits such occurrence without further downward shifting of the inner member 45. Under some circumstances, however, insufficient pressure can be built up for shifting the outer valve member 3l completely to its port closing position.

Well conditions, such as a high hydrostatic head of cement slurry around the exterior of the casing string above the ports I4, or hardened cement from the lower cementing operation around the tubular member I below the outer sleeve valve 3 I, and the like, may offer resistance to downward movement of the outer sleeve valve upon application of hydraulic pressure in the annular cylinder 35 alone. To insure an adequate hydraulic force to shift the outer sleeve valve member 3I downwardly to full port closing position, it is desired to transmit the force of the fluid pressure acting across the entire area of the plug 58 and sleeve 45 to the outer sleeve valve. This can be done upon eliminating the entrapped iluid from the region between the upper and lower inner sleeve valve members 45, I5.

This fluid can be removed in several manners, after the ports I4 have been closed by the outer sleeve valve 3|. The lower plug or trip device 5I includes an upper central passage 90 communicating with side ports 9I below the spherical seal 53. This central passage is originally closed by a plug or valve head 52 held in position by frangible means, such as a shear pin 93 extending between the spherical head 52 and the plug 92. Leakage around the plug can be prevented by a suitable side seal 94 engaging the wall of the central passage 90.

When suiicient pressure is imposed on the fluid entrapped between the upper and lower sleeve valve members 45, l5, the frangible pin 93 is disrupted, and the plug 92 in the trip device moved downwardly into an enlarged bore 94 formed in the extension 54 (Fig. 3). The fluid between the sleeve valve members 45, I5 can then pass through the open passage 90, through the enlarged bore 95, and through the ports 9i into the casing below the collar A. The release of such uid permits the upper inner sleeve valve member 45 and top cementing plug 5B to move downwardly under the action of the hydraulic pressure thereabove, the hydraulic force being transmitted from the upper valve member through the keys 82 to the outer valve member 3l, the inner and outer valve members being moved downwardly to the fullest extent, in which the upper end of the cylinder 35 is disposed below the latch shoulder 44 (see Fig. 3).

The fluid in the casing string below the collar A may also be a trapped body of fluid, but it is of such length (several hundred or several thousand feet) that the small quantity of fluid trapped vbetween the upper and lower sleeves 45, I5 can still be forced through the trip device passages 7 5 8 90, 9 5, 9| downwardly into it. The iluid below the collar A is ordinarily of such character as to be partially compressible, even if only to a relatively minute extent.

The entrapped fluid may also be released by forming the lower trip device 5I with a chamber 96 that can have the required volume, and which is normally at atmospheric pressure. This chamber is closed by the plug 92 held in place by the shear pin 93, in the same marmer as described in connection with the other trip device (see Fig.5).

Upon application of suicient pressure to the top cementing plug 58 and upper inner valve member 45, the shear pin 93 is disrupted and the plug 92 moves downwardly into the air chamber 9B, followed by the entrapped fluid between the members 45, I5. As a matter of fact, the disrupting of the frangible pin 93 will cause the air chamber 96 to effectively suck the entrapped fluid downwardly into it.

Following release of the plug 92, the upper inner valve member 45 cooperates with the outer valve member 3I to shift the latter to port closing position, in the manner described above in connection with the other trip device.

The inventors claim:

1. A plug adapted for downward movement in a well conduit, said plug including an upper valve head having a chamber which opens upwardly through said head, said head having a downwardly facing sealing surface adapted to engage a companion seat in the well conduit, an extension extending downwardly from said head, and means releasable by hydraulic pressure releasably attached to said head and disposed across said chamber to close the same.

2, A plug adapted for downward movement in a well conduit, said plug including an upper valve head having a chamber which opens upwardly through said head, said head having a downwardly facing sealing surface adapted to engage a companion seat in the well conduit, an extension extending downwardly from said head, a closure member in the upper end of said chamber to close the same, and hydraulically releasable means attaching said closure member to said head.

3. A plug adapted for downward movement in a well conduit, said plug including an upper valve yhead having a chamber which opens upwardly through said head, said head having adownwardly facing sealing surface adapted to engage a companion seat in the well conduit, a hollow exa tension extending downwardly from said head and` communicating with said chamber, a closure member in said chamber to close the same, and hydraulically releasable means attaching said closure member to said head.

4. A plug adapted for downward movement in a well conduit, said plug including an upper valve head having a chamber which opens upwardly through said head,said head havinga downwardly facing sealing surface adapted to engage a companion seat in the well conduit, an extension extending downwardly from said head and having a chamber communicating with said head chamber, said extension having a sideport leading outwardly from the extension chamber below said sealing surface, a closure member in one of said chambers above said port, and means releasably attaching said closure member in said vone chamber.

5. A plug adapted for downward movement in Va. well conduit, said plug including an upper valve head having a chamber which opens upwardly through said head, said head having a downwardly facing sealing surface adapted to engage a companion seat in the well conduit, an extension extending downwardly from said head and having a closed chamber therein communicating with said head chamber, and means releasably attached to said head and closing said head chamber.

6. A plug adapted for downward movement in a well conduit, said plug including an upper valve head member having a chamber which opens upwardly through said head member, said head member having a downwardly facing sealing survface adapted to engage a companion seat in the well conduit, an extension member extending downwardly from said head member and having a chamber communicating with said head member chamber, said extension member having a side port leading outwardly from the extension member chamber below said sealing surface, a closure in one of said chambers above said port, means releasably attaching said closure to one of said members and within said one chamber, and a weighting material in said extension member below said port having a substantially greater specic gravity than that of the material of the extension member.

7. A plug adapted for downward movement in a well conduit, said plug including an upper valve head having a chamber which opens outwardly through said head, said head having a lower generally spherically curved sealing surface adapted to engage a companion seat in the well conduit, an extension extending downwardly from said head and having a chamber communicating with said head chamber, said extension having a side port leading outwardly from the extension chamber below said sealing surface,

and frangible means in said head chamber attached to said head to close said head chamber.

8. A plug adapted for downward movement in a well conduit, said plug including an upper valve head having a chamber which opens upwardly through said head, said head having a lower generally spherically curved sealing surface adapted to engage a companion seat in the well conduit, an extension extending downwardly from said head and having a chamber communicating with said head chamber, and frangible means in said head chamber attached to said head to close said head chamber.

9. A plug adapted for downward movement in a well conduit, said plug including an upper valve head having a chamber which opens upwardly through said head, said head having a downwardly facing surface, an elastic seal on said surface adapted to engage a companion seat in the well conduit, an extension extending downwardly from said head, and means releasable by hydraulic pressure releasably attached to said head and disposed across said chamber to close the same.

REUBEN C. BAKER.

BENJAMIN LEWIS AUSTIN.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,312,695 Kessler Aug. 12, 1919 1,509,386 Wilson Sept. 23, 1924 1,812,888 Maynard July 7, 1931 1,822,925 Granger Sept. 15, 1931 2,295,418 Mims Sept. 8, 1942 V2,343,901 Groves Mar. 14, 1944 2,382,578 Penick Aug. 14, 1945 2,493,650 Baker et al. y. Jan. 3, 19,50