US2925252A

US2925252A - Turbine driven drill bit

Info

Publication number: US2925252A
Application number: US640475A
Authority: US
Inventors: Sid H Minor
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-02-15
Filing date: 1957-02-15
Publication date: 1960-02-16
Anticipated expiration: 1977-02-16

Description

S. H. MINOR TURBINE DRIVEN DRILL BIT Feb. '16, 1960 3 Sheets-Sheet 1 Filed Feb. 15, 1957 INVENTOR. BY 5m 1.7. Mitwr )f Z v ATTORNEYS Feb. 16, 1960 s. H. MINOR TURBINE DRIVEN DRILL BIT 3 Sheets-Sheet 2 Filed Feb. 15, 1957 IIII,I,

mmvma Sid 1!. Minor ATTORNEYS Feb. 16, 1960 s. H. MINOR 2,925,252

TURBINE DRIVEN DRILL BIT.

Filed Feb. 15, 1957 5 Sheets-Sheet 5 m 4 WM 7 .H T. .m m 4 4 la a; 7/ W m M M 8m m W. y M w 2 4 l J 3 W W 4 v w M H w flw J m w w -3 36 M M L2 m if. j j W United States Patent 2,925,252 TURBINE DRIVEN DRILL arr Sid H. Minor, Barnwell, S.C.

Application February 15, 1957, Serial No. 640,475

15 Claims. (Cl. 255-4) This invention relates to a power-driven drill or hit, and more specifically, the present invention pertains to a turbine-driven drill or bit for drilling Wells.

One of the primary objects of this invention is to provide a well-drilling, turbine-actuated, substantially hollow cylindrical bit which may be operated by any fluid medium source under pressure such as, for example, water, steam, compressed air, or other gases and fluids.

A further object of this invention is to provide a turbine-actuated bit of the type described wherein the fluid medium employed serves the additional functions of preventing the bit teeth from overheating and of flushing away drillings which may accumulate within the hollow bit.

Another object of this invention is to provide, in a device of the type referred to above, means for closing the fluid discharge side of the turbine housing to prevent damage to the impeller in the event the drillings are not flushed from the bit and accumulate therein.

A still further object of this invention is to provide a rotary turbine-driven drill bit wherein one or more sets of turbine impeller blades are mounted within the bit for rotation about a horizontal axis.

Other and further objects and advantages of the present invention will become more evident from a consideration of the following specification when read in conjunction with the annexed drawings, in which:

Fig. 1 is a side elevational view of a power-driven bit constructed in accordance with this invention and illustrating the same in a well digging operation;

Fig. 2 is an enlarged detail cross-sectional view of the bit shown in Fig. 1, this view being taken on the vertical plane of line 2--2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a fragmentary detail cross-sectional view of the bit taken substantially on the vertical plane of line 3-3 of Fig. 2, looking in the direction ofthe arrows;

Fig. 4 is a top plane view of the power bit, partly in section, and taken on the horizontal plane of line 4-4 of Fig. 2, looking in the direction of the arrows;

Fig. 5 is a detailcross-sectional view of thebit taken on the horizontal plane of line 5-5 of Fig. 2,-looking in the direction of the arrows; i

Fig. 6 is a bottom plan view of the power bit taken on the horizontal plane of line6'-6 of Fig. 2, looking in the direction of the arrows;

Fig. 7 is a medial, longitudinal, cross-sectional view of a power driven bit constructed in accordance with a second embodiment of this invention;

Fig. 8 is a detail cross-sectional view taken on the horizontal plane of line 83 of Fig. 7, looking in the direction of the arrows;

Fig. 9 is a fragmentary cross-sectional view taken on the vertical plane of line 99 of Fig. 7, looking in the direction of the arrows; Vi

Fig. 10 is a fragmentary cross-sectional view taken on the vertical plane of line 10--10 of Fig. 7;

'walls 46, 4.8, 50, 52 as'described above.

Ice Patented Feb; 16, 1960 Fig. 11 is .a vertical, medial, cross-sectional view of another embodiment of this invention;

Fig. 12" a detail cross-sectionalview of the bit taken on the horizontal plane of line 12-12of Fig. 11, looking in the direction of the arrows;

Fig. 13 is a detail cross-sectional view taken on the ver-. tical plane of line 13-13 of Fig. 11, looking in the direction of the arrows;

Fig. 14 is a detail cross-sectional view taken on the vertical plane of line 14-14 of Fig. 11, looking in the direction of the arrows;

Fig. 15 is a fragmentary cross-sectional view of the modification illustrated in Fig. 11, Fig. 15 disclosing a still further embodiment of this invention; and

Fig.16 is a bottom view of the structure shown in Fig. 15, certain parts thereof being shown in a different position.

Referring now more specifically to Figs. 1 to 5, inclusive, reference numeral 20 designates, in general, a powerdriven drill bit assembly constructed in accordance with the teachings of a first embodiment of this invention, and especially designed for the drilling of wells, as is indicated at 22 in Fig. 1.

The assembly 20 is seen to comprise a vertically-elongated, substantially-hollow cylindrical casing 24, reduced in diameter at its upper end to form a neck portion 26 which is externally threaded at 28. A coupling element 30 internally threaded at 32 at its lower end is threadedly connected with the neck portion 26. The upper end of the coupling element 30 is internally threaded at 34 to provide a threaded connection with the lower end of an elongated, hollow and substantially cylindrical conduit 36 externally threaded at 38.

Disposed within the casing 24 is a substantially hollow rectangular turbine housing, designated generally by, the numeral 44, with opposed open upper and'lower ends.

The housing 44 comprises four vertically extending side.

walls

46, 48, 56, 52. The upper ends of the

side walls

46, 48, 50, 52 are welded, or otherwise secured, by conventional means, to the lower ends of a plurality of fiat plates 54. The plates 54 are of identical configuration and are inclined upwardly and outwardly from the

side walls

46, 48, 50 and 52. Plates 54 are constructedwith straight lower ends 56, oppositely disposed and inwardly converging sides 58, 6t), and an arcuate upper end 62 which conforms with the inner surface of casing 24. The plates 54 are assembled with their respective adjacent pairs of sides fixedly secured to each other and the lower ends thereof are connected'with the upper ends of the side The resulting structure comprises a fluid inlet for the turbine housing having a hollow, truncated, inverted substantially pyramiclate configuration with a continuous circular upper end 62 engaging the inner surface of the casing 24 adjacent the upper end thereof.

A second set of plates 54', identical with respect to the plates 54 are arranged and secured together in the manner described above and are secured to the lower ends of the

side walls

46, 48, 50, 52 with the lower arcuate ends 62 thereof forming a continuous circular end engaging the inner side of the'casing 24 adjacent its lower end. This set of plates forms afluid discharge structure having a hollow, truncated, substantially pyramidate configuration. Welding 64 secures the ends 62' to the adjacent side of the casing 24 to rigidly secure the turbine housing 44 in place.

The side walls 46, 50 of the turbine housing 44 are formed with oppositely disposed coaxially aligned aper tures 66, 68, respectively, which are spaced from and are coaxially aligned with a pair of diametrically opposed apertures 70, 72 formed in the casing 24. A turbine shaft 74 extendstransversely across the housing 44 and the casing 24 and is journalled for rotation in the

apertures

66, 68,70, 72. Bearings 16, 78 are mounted in the apertures 10, 72 and support the shaft 74 adjacent theouter ends thereof; Bearing keepers'80; 82': surround the; shaft 74 andare fixedly" secured to: t the inner: side ofithe casingi24-as by welding 84a 1E7 '7 A turbine impeller hub 86:is telescoped oventheshaft 74* and is keyedthereto: by a spline 88 forrotation .therewith. 'A- plurality of impeller blades 90' extend axially of the hub 86 and are fixedly mounted; thereon by welding 92'. The'turbinebladeswork between a-pair of spaced and oppositely disposed arcuateplates 1 94, 96 having their opposed ends affixed to the side walls 46, 50, and the convex surface of: the former welded at 98 to the side wall 48; The convex surface of the latter plate 96, is secured to the sidewall 52 by welding as at 100.

A substantially: rectangular fluid guide plate 102 is welded at: 104m the

side walls

46, 48, 50. This. plate (see Figs. 2 and 3) is downwardly inclined from the upper end of the side wall 48 and terminates at a point slightly beyond one-half the distance between the side Walls 48 and" 52, and its lower terminal end is welded orotherwise rigidly connected to. the upper terminal end of the arcuate plate 94. This structure results in the formation of a substantially rectangular water inlet slot for the turbine housing 44 which is defined. by the lower end-of the guide plate 102, the side walls 46, 50

v and the sidewall 52; The discharge port from the turbine is defined by the lower confronting ends of the plates-'94, 96 and' the'side walls 46, 50;

An inverted, hollow frusto-conical member 106 is mounted below casing 24 with its upper end rigidly con.- nect'ed'to'the lower end'of said casing.

The-rotary bit member is designated, in general, by the reference numeral 108 and comprises an axially elongated, substantiallyyhollow cylindrical member 110, openi'at either-end, surrounding the casing 24 in spaced relation relative thereto. a 1 1 The cylindrical member 110 has an inwardly project- 'ing annular gear ring112 rigidly connected thereto adjaeentthe upper end -theref,' and a second gear ring 114 also-fixedlysecured to the cylindrical member 110 in downwardlyspaced relation relative to the first gearring. Bothof the gear rings surround the casing 24 in" spaced relation with respect thereto.

Intermediate-the ends of the cylindrical member 110 isrigidly secured an annular'flange 116, the functiontof which will become more'apparent below.

In assembling'the device, the flange 116 is first aifixed to the cylindrical member 110 by conventional means such as, for example, by weldingtnot shown). The ring gear 114 is also fixedly securedto the cylindrical member- 110 in5a similar manner. This assembly is slidably mounted over thecasing 24 after which aplurality of ball bearings 118 are disposed on the ring gear 112 and annular flange, 120 is then welded to the casing 24; The ring gear 112 and the flange 120serve as races for the bearings 118.

An annular flange 122 is rigidly secured, as by welding; to the lower. end; of thecasing 24 and this flange taken together with. the, flange 116 serve as races for the ball bearings 124 which are interposed therebetween.

'A: frusto-conical member 126'has the base thereof rigidly securedtoi the cylindrical member 110 adjacent the lowerendithereof. As isseen in Fig. 2 of the drawings;-

the open upper end of the frusto-conical member 126 surrounds .thelower end; of the inverted fl'USlZO-COIllC31 element 106 in spaced relation relative thereto;

Atplurality, of;t(=.eth':1"3l6 is: secured to the-outer side ofi-thex cylindrical member. 110 extending downwardly from the/lower'end thereof; As isseen in Figs. Land-6, the teeth -136' are: arranged in: a plurality of sets= circumferentially.v spacedgifizom :each: other; for; a reason which will appear hereinafter.

' Arcuately shaped ribs 128 are rigidly secured at their outer ends to the innersurface of cylindrical member 110 and extend inwardly therefrom, the inner. ends of said ribs being secured to a circular hub 130 as by welding 132. As seen in Figs. 2 and 6, each of the ribs 128 carries a plurality of depending teeth 134.

Each of the ribs 128r has fixedly secured thereto an upstanding hollow cylindrical boss 188 internally threaded to receive a bolt 1 The bolts 140 serve as vertical guides for a substantially hollow conical member 142 which is mounted thereon. As is seen in Fig. 2 of the drawings, the conical member 142 has secured-1m the upper side thereof a plurality of lugs 144 which surround the bolts 140. Interposed between the bolts 140 and the lugs 144 are a plurality of helical springs 146 which tend to constantly bias the conical member 142 in a downwardly direction. A

An annular flange 148 has-it's outer edge fixedly secured to the cylindrical member 1 10 adjacent the base of the frusto-coni'cal element 126; From Fig. 2 it willb'e seen thattheannular flange 148is downwardly inclined and the nature of the flange 14% will be set forth rnoife' specifieally below.

The shaft'74'projects' diametrically across and beyond the casing 24. A bevel gear 150 is fixedly secured to one end of the shaft 74' by means of a set screw .152 and the otherprojecting endof the shaft 74'rec'eivesa bevel gear 1'54'wh-ich-isfixedly secured thereto'by means ofa set screW-'156'.=- The bevel. gear 150 is displaced outwardly away froni the casing 24 atagreaterdistwee then is the bevel gear 154, whereby the bevel gear 150 ismes' hedwith the ring-gear 112 while the bevel gear 7 154 meshes" with the ring gear- 114.

The operation of the device'- is now deemed to be? as;

the shaft 74-is ro'tated', the bevelgear s' 150, 154 being in mesh with the ring gears 1-12, 114 efiect the rotation of the cylindrical member 110. As the cylindrical mem her 110 is rotatedg-the teeth 134,136drill into the ground 160to produce the'cylindrical well here 22; v

The fluid after impinging upon the impeller blades passes downwardly through the inverted frusto-conical element 106 from whence iti-s dischargedto pass between the lower edge of the'frusto-conical member 106 and the conical member 142} The discharge force of the fluid passingfrom th'e'invertedifrusto conic-al member 106 normally tends towassistethe'helical springs 146 tosmaintain the conicalmember 142'in its downward open position relative to the outlet end' of therinverted' frusto-conical member 106. Under normal operating-conditions; the fluid discharged frombetween the frusto-conical'member 106and the conica'l member 142 impinges against-the annular plate orjflange1148 which reverses-the direction of the flow of the fluid in such a manner thattheifluidisdirected inwardly" toward theccnter of the cylindrical memben; i V H c The fluid discharging from the plate-148 is directed toward the ribs 128- and their respective drill teeth 134. As the-

drill'teeth

134 and 136 bore through the: ground, there is a natural tendency for drillings to -accumulate Within the cylindrical member 110at the lower end thereof. However, any tendencyyfor this matter to accumulate within the cylindrical 110 is normally. obviatcd since the fluid mediumemployedmixes withthe drilli'n'g's and ferees the same outwardlwb elow the'lo w'ere'rid of'fthe casing 24, upwardly throligh the spaces between e'ac liofth at! jacent sets of drill teeth 136. Thereafter, the drillings entrained in the fluid pass upwardly between the; wall of the well bore 22 and the adjacent side of "the cylin drical member 110 and eventually rise to the surface of the ground 23. This fluid backwash may be led by means (not shown) to storage means for reuse. In the event water is employed as the power medium, conduits may lead the backwash to a settling pit.

In addition to the flushing operation, the fluid medium is also suitably adapted to maintain the

drill teeth

134, 136 at a low temperature despite the heat generated by fric tional contact thereof with the ground during the drilling operation.

In the event the fluid medium employed is not supplied to the cylindrical member 110 in sufficient volume or without sumcient force to effectively flush the drilled material from within the cylindrical member 110, the

rillings will tend to accumulate within cylindrical member 110 at the lower end thereof. As this massincreases, it will engage against the underside of the hollow conical member 142 and will tend to force the same upwardly against the tension of the helical springs 146 and the added force generated by the fluid medium. The upward movement of the conical member 142 causes it to seat against and to close the lowermost opening of the inverted frusto-conical member 106. In closing this opening, the frusto-conical member 142 prevents the entry of the drillings within the casing 24 and the housing 44 so that the drillings cannot reach the turbine blades 90 and damage the same. Suitable gauges (not shown) connected with the source of fluid under pressure may be employed to detect malfunctioning of the drill 20. Also, suitable gauges (not shown) can be employed to detect this condition by "cohnection with the return means for the backwashing fluid. 1 L

A second embodiment of this invention is illustrated in Figs. 7 to 10, inclusive. In' these figures, the power driven drill bit assembly is designated, in general, by the reference numeral 200 and is seento comprise an axially elongated hollow cylindrical casing .204having an upper reduced neck portion 206 jexternallythreaded at 208 to receive the lower end of a coupling 210. The upper end of thecoupling 210 is threadedly connected with the lower end of an elongated hollow conduit 211, as described in the first embodiment of this invention, the upper end of the conduit 211 being connected with a source of fluid under pressure.

The casing 204 surrounds a turbine housing 212 having a substantially rectangular configuration and comprises the

rectangular side walls

214, 216, 218, 220.

As in the original embodiment of this invention, the

side walls

214, 216, 218, 220 are welded or otherwise secured by conventional means to the lower ends of a plurality of flat plates 222. These plates have identical configurations and are inclined upwardly and outwardly from side walls, .214, 2.16, 218, 220. Plates 222 are constructed with straight lower ends 224, oppositely disposed and inwardly converging

sides

226, 228 and an arcuate upperend 230 which conforms with the inner surface of casing 2134. Assembly of these plates. with their. respective adjacent pairs of sides fixedly secured to, each other and withtheir respective lower ends connected with the upper ends of the side walls-214, 216 21 8, 220 gives rise to, a fluid inlet structure having a hollow, truncated, substantially pyramidate configuration with a continuous upper end engaging the inner surface of the casing 204 adjacent the upper end thereof} 1 A second set of plates 222' having identical configurations. with respect to the plates. 222 are arranged and secured together in the manner described aboveand are amxed to the lower ends of the side walls 214, 21-6, 218, 220 withthe lower arcuate ends thereof 224 forming a continuous circular end engaging the inner side of the casing204. This set of plates form a fluid discharge structure having a hollow, truncated, substantially pyramidate configuration. Welding 231 secures the arcuate cases 6 ends 224 of the plates to adjacent sides of the casing 204 to rigidly secure the turbine housing 212 in place.

A substantially vertically extending divider plate 232 is disposed within the turbine housing 212 and has a pair of opposed edges thereof rigidly secured to the

side walls

216, 220. As is seen in Figs. 7 and 8, the divider plate is positioned substantially centrally between the

side walls

214 and 218. The divider plate 232 has a circular recess 234 formed in one side thereof which is eoaxially aligned with an opening 236 formed in the side wall 214 and with an opening 238 formed in the casing 204. A similar recess 239 is formed in the opposite side of the divider plate 232 and is coaxially aligned with the opening 240 formed in the side plate 218 and with the opening 242 formed in the casing 204. The openings 236, 238, 240, 242 and the recesses 234 and 238 are all coaxially aligned, one with respect to the others.

A shaft 244 has one of its ends rotatably journalled Within the recess 234 and the other end thereof is rotatably received within the openings 236, 238, the shaft 234 projecting laterally beyond the casing 204. In a similar manner, a shaft 246 has one of its ends rotatably journalled within the recess 239 and the other end thereof is rotatably received within the openings 240, 242. As is seen in Fig. 7, the other end of the shaft 246 also projects beyond the casing 204.

The rotary bit member is designated, in general, by the reference numeral 248 and is seen to comprise an axially elongated hollow, cylindrical member 250. Adjacent the lower end of the cylindrical member is fixedly secured a flange 252 which cooperates with a flange 254 fixedly secured to the casing 204, the flanges 252, 2154 serving as races for the ball bearing 256 interposed therebetween. The drill bit 248 has an annular ring gear 258 fixedly secured to the inner side thereof, the ring gear being adapted to mesh with the bevel gears 260, 262 which are mounted on said other ends of the shafts 244-, 246. Screws 2'64, 266 fixedly secure the

gears

260, 262, respectively, to the shafts" 244, 246 for rotation therewith.

An annular flange 268 is rigidly secured to the casing 204 adjacent the upper end thereof and cooperates with an annular flange 270 fixedly secured to the rotary bit member 248 to form a bearing race for the ball bearings 272.

As is seen in the drawings, the divider plate 232 divides the turbine housing 212 into a pair of compartments disposed in side-by-side relationship. For convenience, the two compartments have been indicated by reference letters A, B. In compartment A and mounted on the shaft 244 is a hub 274 secured to the shaft by a spline 276 for rotation therewith. The hub 274 has fixedly secured thereto one end of a plurality of impeller blades 278.

Upper and

lower ribs

280, 282 are fixedly secured to the side wall 216 and are adapted to support a pair of arcuately shaped plates 284, 286, respectively, which confront the outer edges of the impeller blades 278. In a similar manner a rib 288, secured to the side wall 220, supports an arcuately shaped plate 290 which also confronts the impeller blades 278. As is seen in Fig. 7 of the drawings, the

plates

284, 286 and 288 extend transversely across the chamber A between the adjacent sides of the side wall 214 and the divider plate 232. The chamber B hasdisposed therein a plurality of impeller blades 292 having their inner ends fixedly secured to a hub 294 which is, in turn, splined at 2% to the shaft 246 for rotation therewith. It is important to note at this point that while the

impeller blades

278 and 292 are of identical construction, the working face of the impeller blades 292 is reversely directed with respect to the Working face of the impeller blades 278.

The impeller blades 292 work between the

plates

298 and 300 which are rigidly secured to the side wall 220 by means of a pair of upper and lower ribs 302, and 304, respectively, and a third plate 306, rigidly supported from, the side Wall 216 by means of a rib 308.

lower end of an elongated conduit'434. The otherend' of the conduit 434 is connected with a source of fluid under pressure and theoperation of the turbine driven drill-bit is the same as has been set forth above.

, Figs. 15 and 16 illustrate a further embodiment of this invention. As shown therein, the turbine-driven drill assembly500 is identical in construction to the drill 320 with the exception of added means for protecting the

impellers

376, 376 from damage by preventing drillings from accumulating in the lower ends of the assembly. To this end a bottom plate 502 is welded to the lower end of the casing 322 atone side of the passage 326 and a substantially rectangular closure plate 508 disposed across passage326 is pivotally secured thereto by means of a hinge 504.

An arcuately shaped stop member 512 is provided for each end of the plate 508. As illustrated, one end of the stop members 512 is welded to the plate 508 while the other end thereof normally engages the lower end of the casing 322 keeping the closure plate 508 from opening to any position more than about 60 from the horizontal.

A" similar closure plate 508 provided with a stop member 512' is pivotally secured by means of a hinge 504' to a bottom plate 502' which is secured to the bottom of casing 322 on the opposite side of passage 326.

As the drillings build up below the plates 508, 508' within the casing, the plates 508, 508' are pushed upwardly and will pivot towards each other until they are in closed position and the discharge end of the passage 326 is eflectively sealed. With the discharge end of the passage 326 closed, fluid flow no longer rotates

impellers

376, 376 and the drilling operation is halted. The operator now raises the drill 320 and removes the accumulated drillings and thereafter returns it to the Well hole.

Having described and illustrated several embodiments of this invention, it is to be understood that the same are offered merely by way of example, and that this invention is to be limited only by the scope of the appended claims.

I claim:

1. Drilling apparatus comprising: a casing having a fluid inlet and a fluid outlet and being adapted for the passage of fluid therethrough from said inlet to said outlet; a fluid driven impeller device mounted in said casing for rotary movement with respect to said casing upon actuation by fluid flow from said inlet to said outlet, a substantially cylindrical bit member surrounding said casing and rotatably mounted with respect thereto; and a shaft having one end thereof drivingly connected with said impeller device and having the other end thereof extending generally horizontally through an opening in said casing and being connected with said bit member to effect rotation thereof upon actuation of said impeller device.

2. Drilling apparatus as defined in claim 1, wherein said impeller device rotates about a normally horizontal axis.

3. Drilling apparatus as defined in claim 1, including means for closing said outlet to prevent an accumulation of drillings from entering said impeller device.

4. Drilling apparatus as defined in claim 1, wherein said bit member includes a plurality of ribs extending transversely of said casing adjacent the lower end thereof, said ribs having aplurality of longitudinally spaced drill teeth depending therefrom, and wherein said bit member is also provided with a plurality of circumferentially spaced sets of drill teeth outwardly offset with respect thereto.

5. A turbine-driven drill bit comprising: an elongated casing having a fluid inlet opening and an oppositely disposed fluid outlet opening; an elongated turbine housing fixedly secured within said casing, said turbine housing having a fluid inlet opening and an oppositely disposed outlet opening; a shaft extending across said turbine housing and said casing. and having its opposed ends proje'ctinglaterally beyond said casing, sai-dshaft being rotation of said shaftyan elongated bit member sur-- rounding and being mounted for rotation on said casing; and means connecting said ends of said shaft with said bit member in driving relation.

6. A turbine driven drill bit as defined in claim 5,-

wherein said connecting means includes a gear fixedly mounted on one end of said shaft for rotation therewith,

and a gear ring fixedly secured to said bit member in spaced relation relative to said casing, said gear and gear ring being meshed with each other.

7. A turbine device as defined in claim 5, wherein said connecting means includes a pair of axially spaced gear rings fixedly secured to said drill bit in elf-set relation relative to each other, and gears fixedly secured to the opposite ends of said shaft, each of said gears meshing, respectively, with one of said gear rings.

8. A turbine-driven drill bit comprising an elongated casing; an elongated turbine housing mounted in said casing and having oppositely disposed inlet and outlet openings; means dividing said housing into a pair of compartments, an impeller device rotatably mounted in each of said compartments, means for directing fluid flow against said impellers to effect rotation thereof in opposite directions; a bit member surrounding said casing and being rotatably supported thereon in spaced relation relative thereto, and means connecting said impeller devices in driving relation with said bit member to efiect rotation thereof.

9. A turbine-driven drill bit as defined in claim 8, wheren said impeller devices are each provided with a shaft having one end thereof extending exteriorly of said casing, a gear being mounted, respectively, on each of said shaft ends and both of said gears meshing with a gear ring fixedly secured to said bit member.

10. A turbine-driven drill bit as defined. in claim 9 wherein said impeller devices are mounted for rotation about substantially horizontal axes.

11. A turbine-driven drill bit as defined in claim 8,

including means for preventing an accumulation of drillings within said casing from entering said turbine housing.

12. A turbine-driven drill bit as defined in claim 8, wherein said bit member includes a plurality of ribs extending transversely of said casing adjacent its lower end, said ribs having a plurality of longitudinally spaced drill teeth depending therefrom, and wherein said bit member is also provided with a plurality of circumferentially spaced sets of drill teeth outwardly offset with respect thereto.

13. A turbine-driven drill bit comprising: an elongated substantially cylindrical casing having a substantially rectangular passage extending axially therethrough; means dividing said passage into a pair of sideby-side compartments; an impeller device rotatably mounted in each of said compartments for rotation in opposite directions relative to each other; a substantially cylindrical bit member surrounding said casing and being rotatably supported thereon in spaced relation relative thereto; means connecting said impeller devices in driving relation with said bit member to effect rotation thereof around the axis ofsaid cylindrical casing; and means for connecting one end of said casing with a source of fluid under pressure.

14. A turbine-driven drill bit comprising: an elongated substantially cylindrical casing having an axially extending substantially rectangular passage formed therein and having opposed open ends, said casing having a plurality of longitudinally extending recessesformed in a pair of opposed side walls of said passage: a turbine unit coma side, of said. divider: plate; a; second; pair; of arcuatelv shaped; turbine housing sections, said: second; pair of;-

housing; sections having one; of. their-respective; endsse cured tothe other side of: said divider; plate, said divider plate having an opening extending transversely there through; a turbine, having ahollow huh-disposed between each; of saidfirst. and, ,-sec,ond; turbine-housing. sections;

said; unit ,being, disposed within said passage: with, the; outer endsofcsaid-ribszand said divider pl wdi pmed in, said ,recesses; said casing having a -pair oft'diarnetricaln ly opposed openings formed therein; said; openings beingaligned F with said: opening; formed; in v said divider pl-ate and with said hubs; a shaft rotatably; mo nted in; one of;

said openings formedzin said-easing andhavingan end,

thereof projecting through; one of; said turbine huhsand, journalled within; said opening=,formed in said divider, plate; a second shaft-having;oneofits ends extending throngh'theother ofrsaid'openings formed insaid casing and; projecting: through; said hub; of saidzsecond 5 turbine ndiiopmelled h n dmashin ormed ints dltdiv der plateeansefi dln ec r n id-hubs o s d-shafts i ee mitt n he h nt r wash Qfi saidfiheflse ar eylindrieal bit member; means supgorting said seemed mime-inner side of said bitmembereand meshing w-ith. Said; gears, andmeans for connectin o lQ: 6nd,;

of said casing with a source, of fluid under pressure. 1

15. A turbineadriven; drill,,bit;as defined in,cl aim 14,

andimeans mounted on the, other end ofisaideasingztg automatically close said otherrend; thereof upon 'aceumu-n lationof drilling s within said bit;

RferencesCitgd-inthe file-of this atent.

I UNITED "STATES' PATENTS,

ut member for rotation on sald casing g a gearr-ring fixedly;