US1245392A - Turbine-engine. - Google Patents

Description

C. J. SHELDON.

TURBINE ENGINE.

APPLICATION FILED AUG-25.1916.

1,245,392. Patented Nov. 6, 1917.

6 SHEETSSHEET llNVENTOR al/w ATTORNEY 0.1. SHELDON. TURBINE ENGINE.

APPLICATION FILED AUG-25- I916.

Patented Nov. 6, 1917.

6 SHEETS-$HEET 2 ENVENTQR TTORNEY C. 1. SHELDON.

TURBINE ENGINE.

APPLIcATmN FILED AUG.25. 191s.

Patented NOV. 6, 1917.

6 S HEETSSHEET 3.

A'ITORNE INVENTCR C. J. SHELDON.

TURBINE ENGINE.

APPLICATION FILED AUGIZS. 19l6.

1,245,392. Patented Nov. 6, 1917.

6 SHEETS-SHEET 4- I NVEN TO R (1.1. SHELDON.

TURBINE ENGINE.

APPLICATION FILED AUG.25. I916.-

1 45,392. Patented Nov. 6, 1917.

. 6 SHEETS-SHEET 5.

GI-II ENVENTOR c.1. SHELDON.

TURBINE ENGINE. APPLICATION FILED A'u .25. mus.

$455392, Patented Nov. 6, 1917.

e shins-sum 6.

INVENTOR UNITED srarns PATENT ourrcn CARSON J. SHELDON, OF YOUNGSTOWN, OHIO, ASSIGNOR 0F ONE-SEVENTH TO JOHN L. HGFFACKER, OF SHARON, PENNSYLVANIA, AND ONE-SEVENTH TO GEORGE L.

SCI-IVIARTZ, OF YOUNGSTOWN, OEIO.

TURBINE-ENGIN E.

Application filed August 25, 1916.

To all whom. it may concern:

Be it known that I, Cnnsom J. SHELDON, a citizen of the United States of America, and resident of Youngstown, county of Mahoning, and State of Ohio, have invented certain new and useful Improvements in Turbine-Engines, of which the following is a specification.

This invention relates broadly to turbine engines, and more particularly to a reversible steam turbine.

The primary object of the invention is to provide a steam turbine motor or engine of simple and improved form which may be operated with equal facility in either forward or reverse direction.

A further object of the invention is to provide a motor of the character mentioned having an improved type of rotor embodying spirals having a form and arrangement which render them particularly eiiicient, adapting them for utilizing practically all of the expansive force of the steam.

A further object is to provide a rotor in which the spirals are composed of segments or blades which are readily inscrtible and removable without disassembling the rotor.

A still further object within the contem plation of the invention is to provide a device of the character mentioned which is so constructed that the pressure of the entering steam is counterbalanced, preventing end thrust on the rotor.

lVith these and other important objects in view, the invention resides in the features of construction, arrangement of parts and coinbinations of elements which will hereinafter be fully explained, reference being had to the accompanying drawings, in which Figure 1 is a partial horizontal section of the invention;

Fig. is an enlarged transverse section taken substantially on line 2-2, Fig. 1;

Fig. 3 is an enlarged vertical longitudinal section on the line 33, :Fig. 1;

Fig. 4 is an outer edge view of the spiral of the rotor, the rotor casing being shown in section;

Fig. 5 is a section on line 55, Fig. 4:;

Fig. 6 is a top plan view of the invention, complete;

F ig. 7 is a detail section of the packing ring between the outside casing and the ro- Specification of Letters Patent.

.tions are connected by bolts 8 and are ri Patented Nov. 5, 1917.

Serial No. 116,825.

tor casing, showing an adjustment for said ring;

Fig. 8 is a detail perspective view of segment or blade;

Fig. 9 is a detail section on line 9-9, Fig. 6, showing the piston valve in steam admitting position; V i

Fig. 10 is an enlarged front elevation of the reversing gear;

Figs. 11 and 12 are sections taken, respectively, on lines 1111 and 1:212, Fig. 10, the former showing the rotary valve in one of its operative positions and the latter showing said valve in neutral or inoperative position; and V Fig. 13 is a section on line 13-13, Fig. 10.

Referring to said drawings, in which like designating characters distin uish like parts throughout the several views 1 indicates a main casing, hereinafter termed the outer casing, the body of which is composed of top and bottom sections sccured together by means of bolts 2. Said casing incloses a rotor which comprises a hollow cylinder 3 having heads 4-. mounted in fixed relation to its opposite ends. EX- tending centrally through the rotor casing 3 is a drive shaft 5 which is journaled in suitable bearings, as 6, provided in the companion top and bottom sections 7 composing the end walls of the outer casing 1, which sec O t) idly attached to the body of said casing, as by bolts 9. Keyed upon the shaft 5 is a hub 67 which has a length substantially the same as that of the cylinder 8. The periphery of said hub is provided with a series of spaced longitudinal ribs 10 between which are longitudinal grooves or mortises 11, the purpose of which will presently be explained. Provided on the shaft 5 at each end of the hub 67 are threaded portions 12. Said threaded portions are designed to receive thereon the cylinder heads 4 which are adjusted to closely engage the ends of the cylinder 3 and also the ends of the hub 67.

As is obvious, the shaft might be made with a portion corresponding to the hub 67 formed inte ral with said shaft and having a diameter snfliciently greater than that of the shaft that the alternate ribs and grooves might be formed therein, thereby dispensing with the hub. However, I prefer to'e-mploy the hub 67 for reasons which will be hereinafter explained.

Fixed to, or formed integral with, each of the cylinder heads a is an outwardly tending shaft-inclosing sleeve 13 preferably of the tapered or conical form shown most clearly in Fig. 3; and fixed to or formed integral 'ith said sleeve is a circular plate 14: which is disposed parallel to said cylinder head. The peripheral edge of said plate is rotatably received in an internal annular channel provided in the end of casing 1 and said plate is abutted by the adjacent end wall '7 of said casing. Inclosed chambers 15 and 16 are thus formed at opposite ends of the interior of the casing 1 between the cylinder heads and the adjacent plates ll, which latter constitute pressurebalance plates which are rotatable with the rotor.

Opening into the chambers 15 and 16, respectively, are ports 17 and 18 for the admission and exhaust of steam which is controlled in a manner which will presently be explained.

Located within the otor casing or cylinder is a plurality of parallel spirals, each composed of a plurality of abutting segments or blades 19, the adjacent helices of said spirals being relatively disposed to form a plurality of parallel spiral passages 20 through which courses the steam introduced in the rotor through openings 21 provided in the rotor heads 4:. Each of said blades has its opposite faces fluted or ribbed, as is most clearly shown in Fig. 8, and the opposite flutes are located in staggered relation, as shown in dotted lines in Fig. 4. The ad jacent helices composed of the blade-like segments 19 have the flutes of their opposing faces in staggered relation, thus forming therebetween passages 20 of tortuous form. As is obvious, due to the said arrangement, the ribs or fins of the blades are presented in the path and receive the impact of the expanding steam. The blades are removably mounted in fixed position within the rotor casing 3 each thereof having at its inner or pointed end an integral head or flange which is terminated by tenons 23 which snugly fit in moitises or grooves 11 of the hub 67, saic mortises being of a width which snugly accommodates in abutting relation the two adjacent tenons of abutting blades, as shown in Figs. 4 and 5. The outer edge of each blade is curved to conform to tie cuiwat-ure of the interior walls of the rotor casing and has formed thereon adjacent to the angles which it forms which the lateral edges of the blade projecting tenons 241- which it within longitudinally disposed grooves or mortises 25 provided in said interior walls of the rotor casing in a manner analogous with that of the tenons 28. Formed on the lateral edge of said segment between said tenons 2 1 is a flange 68 having a thickness corresponding to said tenons 24:. The heads or flanges 22 and 68 and tenons and 2st have substantially the same thickness, said thickness being greater than that of the body of the blade so that when said segments are placed in the cylinder in abutting relation adjacent helices composed of such blades are properly spaced apart, as shown in Fig. &. In introducing the blades, the same are entered from one end of the rotor casing, the tenons thereof being inserted one after another in their respective mortises and forced to the limit of their movement. As is obvious, the blades 19" erminating the various spirals necessarily differ slightly in form from the other blades 19, a blank face portion 19 being provided for seating closely against the adjacent rotor head 4 to form a tight oint with the latter.

Due to the large diameter of the hub 67 the passage between the spirals is such a distance from the shaft that a greater leverage is obtained than would be the case if the segments were fitted directly onto the shaft Communicating with the steam chambers 15 and 16 through the ports 17 and 18, respectively, are passages 26 and 27 provided in opposite sides of the bottom section of the enter casing 1. Leading to said passages 26 and 27, respectively, and coupled to said casing section are hollow arms 28 and 28 formed, respectively, on two valve casings 29 and 29 located at opposite sides of the motor constituted by the parts hereinbefore described. Said valve casings constitute parts of a reversible mechanism whereby the direction of the steam through the motor, and, consequently, the direction of rotation of the rotor, may be controlled. Each of said valve casings has mounted therein a piston valve 30 which is movable to and from chasing relation to a steam inlet port 31 which is located in the top of the valve casing in a vertical plane passed through the hollow arm thereof hereinbefore mentioned. A. steam. pipe 32 leads to each of said inlet ports, and, when the piston valve 30 occupies the position shown at the top of Fig. 1, steam passes to the adjacent steam chamber of the motor, being conducted from said port 31 to the passage in the adjacent arm 28 through an L-shapcd passage provided in said piston valve, as is clearly shown in Fig. 9.

The piston valves of the two valve casings 29 and 29 at all times occupy reverse positions so that when one occupies aposition admitting steam to the rotor, as aforesaid, the other occupies a position permitting steam to exhaust, as shown at the bottom of Fig. 1. In the last-mentioned position of the piston valve a transverse passage 3t ex tending therethrough is in open communication at one end with the passage through the arm, as 28, and at the other end with an exhaust port 35 provided in the valve casing, free passage forthe exhaust steam being thus afforded.

The valve 30 has seated against its opposite ends suitable bulfer springs, as the coil springs 36 and 37, and opening into the opposite ends of the valve casing 29 are pipes 38 and 39 for conducting a pressure fluid, as steam, water, or air, preferably the latter, whereby said valve 30 may be shifted from one limit of movement to the other and held in shifted position; and opening into the opposite ends of the valve casing 29 are pipes 38 and 39 for conducting such pressure fluid whereby the valve 30 thereof may be shifted and held. The pipes 38 and 38 communicate with a single pipe 40 leading from a suitably located control valve casing 41, while the pipes 39 and 39 communicats with a single pipe 42 leading from said control valve casing, as shown in Figs. 6, 10. and 11. Located within said casing 41 is a circular rotary valve 43 having a main passage 44 thcrethrough. One end of said passage is centrally located so as to remain permanently in open communication with a pipe 45 leading from a source of supply of the pressure fluid, while the other end of said passage is eccentrically located so that it may, with rotary movement of the valve 43, be shifted into communication with either of the pipes 40 or 42, according as it is desired to furnish the pressure fluid to the right or left hand ends of the valve casings 29 and 29. Also provided in the rotary valve 43 is a passage 46 of curved, or substantially U-shaped, form, one end of which is centrally located so as to remain permanently in open communication with an exhaust port 47 provided in the casing 41 at the side opposite that to which leads the supply pipe 45. The other end of said passage 46 is eccentrically located so that it will, when the rotary valve is shifted from one pressure supply position to the other, be carried from registering relation with the pipe 42 as shown in Fig. 11 to a neutral position over a blank wall. Provided in the face of said valve 43 is an arc-shaped groove 46 which maintains connection between the pipe 42 and exhaust port 47 when the main passage 44 occupies a position intermediate pipes 40 and 42. A second U- shaped passage 69, connected with an arcshaped groove 69, similar to passage 46 and groove 46 is formed in said valve 43 so that when the main passage 44 occupies a position intermediate the pipes 40 and 42, or in direct communication with pipe 42, said groove 69 and passage 69 will allow the fluid in pipe 40 to exhaust. It will therefore be seen that when said main passage 44 occupies a position intermediate said pipes 40 and 42, both of said pipes will be connected with the exhaust port 47, pipe 40 through groove 69 and passage 69, and pipe 42 through groove 46 and passage 46. As is apparent, when the valve 43 is so shifted that the main passage 44 is in direct combe engaged by a toothed dog 51 which is carried by said lever. Said dog is mounted upon a pin 52 which is longitudinally movable in a slot 53- provided in the lever 48. A retractile coil spring 54 has one end attached to said pin and the other end to said lever at a point inward with respect to said pin whereby said dog is normally held in engagement with the ratchet teeth 50. Pivoted links 55 are interposed between the pin 52 and a pivoted trip-arm 66 provided on the outer end of said lever, as shown in Fig. 10. As is obvious, hand pressure applied to the trip-arm acts to withdraw the dog 51 from engagement with the ratchet teeth, whereupon the operating lever may be moved as desired for shifting the position of the rotary valve 43.

hen the operating lever is shifted to a midway position, the rotary valve 43 is carried to a neutral position, whereupon both pipes 40 and 42 are connected to exhaust port 47, as hereinbefore explained.

WVith the pressure control valve set to admit the pressure fluid to the left hand end of the piston valve casing 29 and 29, as shown in Fig. 1, the piston valves 30 are forced against the tension of springs 37 to the positions shown in said figure. With the piston valves in said positions, steam supplied by the steam pipe 32 leading to the valve casing 29 passes through the port 31 of said casing, thence through the registering L-shaped passage 33 of the piston valve 30, thence through-hollow arm 28 to passage 26, whence it passes through port 17 to steam chamber 15, which then serves as an expansion chamber for the admitted steam. The pressure of steam so admitted to the chamber 15 acts equally upon the adjacent cylinder head 4 and the attached circular plate 14, and consequently, the objectionable, end thrust on the rotor, which, except for the presence of said plate, would be evident, is prevented. From the chamber-l5 the ex- Said flanges 49 are preferably provided with ratchet teeth 50 adapted to fixed relation to the hub panded steam passes to the interior of the rotor casing 3 through the openings 21 in the head f, entering the spiral passages 20 between the helices of the spirals composer of the blades or segments 19 and disposed in After traversing said passages, in which it acts to exert a driving force upon the ribbed faces of said spirals, the steam exhausts outward to chamber 16 through the openings 21 of the adj acent head From said chamber the exhaust steam passes through port 18, passsage 27, the hollow arm 28 of casing 29, the registering passage 3st of the piston valve 30 of said casing, and thence outward to the atmosphere through exhaust port As is obvious, reversal of the direction of travel of steam and a consequent reversal of the direction of rotation of the rotor is ac complished by shifting the piston valves 80 to reverse positions, as hereinbefore described.

Suitable packing is provided between the balance plates 1's of the rotor and the end walls 7 of the outer casing 1. While said packing may be of any appropriate type, I prefer to employ the form shown in the drawings, the same including a ring 56 disposed within a circular groove or channel 57 provided in the inner face of each end wall 7. The projecting edge of said ring is preferably beveled as shown, and said edge is received within a V-shaped groove 58 provided in the adjacent face of the balance plate 1%. Said ring seats against said balance plate with an adjustable yielding ten sion afforded by plurality of springs 59 disposed in encircling relation to pins 60 which are mounted in the outer face of said ring at suitably spaced intervals. Said pins are freely movable in holes 61 provided therefor in the walls 7 and have adjusting nuts 62 threaded upon their outer ends, shown in Fig. T. The springs 59 are di posed within sockets 63 provided therefor in the walls 7 and exert a yielding force for maintaining the beveled edge of the ring 56 seated against the balance platele. By adjustment of the adjusting nuts 62 the ertent of inward movement of said rings un-- der the pressure of said springs may be regulated.

The ring 56 is preferably provided with an outer annular groove 64 in which is disposed a ring 65 of piston ring type, as shown.

lVhile I have herein shown and described a practical embodiment of my invention it will be understood that the invention is not confined to a strict conformity with the showing of the drawings, but the details of construction may be changed and modified to the extent that such changes and modifications mark no material departure from the salient features of the invention.

lVhat is claimed isr l. A turbine engine comprising an outer casing, a cylindrical rotor casing rotatable within said outer casing, a centrally disposed drive-shaft extending through said rotor casing, spirals interposed between and disposed in interlockin relation to said rotor casing and said shaft, said spirals being disposed'to form passages for the actuating fiuid, and means controlling the admission and exhaust of said fluid.

A turbine engine comprising an outer casing, a cylindrical rotor casing rotatable within said outer casing, a centrally disposed drive-shaft extending through said rotor casing, spirals interposed between said rotor casing and said shaft and interlocked with both, said spirals being composed of removable segments disposed to form spiral passages for the actuating fluid, and means controlling the admission and exhaust of said fluid.

3. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, apertured heads closing the ends of said cylinder and carried in fixed relation to said shaft and to said cylinder, spirals disposed in encircling relation to said shaft and interlocked both with said cylinder and with said shaft, said spirals being disposed to form spiral passages for the actuating fluid, and means controlling the admission and exhaust of said fluid.

l. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, a hub fixed on said shaft, apertured heads closing the ends of said cylinder and carried in fixed relation to said shaft and to said cylinder, spirals encircling said hub and interlocked both with said cylinder and with said hub, said spirals being disposed to form spiral pasfor the actuating fluid, a circular plate disposed parallel and in fixed relation to each of said cylinder heads at a distance from the latter whereby is formed an intermediate pressure-balance chamber for receiving the actuating fluid, means for conducting said fluid to one of said chambers, and means for conducting said fluid from the other chamber.

5. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, a hub in fixed relation to said shaft, apertured heads closing the ends of said cylinder and carried in fixed relation to said hub and to said cylinder, spirals encircling said hub and interlocked both with said cylinder and with said hub, said spirals being disposed to form spiral passages for the actuating fluid, fluid-receiving chambers adjacent'to said cylinder heads, means carried in fixed relation to'said heads for relieving the cylinder of end thrust under the force exerted by said fluid, and means controlling the admission and exhaust of said fluid with respect to said chambers.

6. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, a hub in fixed relation to said shaft, apertured heads closing the ends of said cylinder and carried in fixed relation to said hub and to said cylin der, spirals encircling said hub and connected both to said cylinder and to said hub, said spirals being disposed to form spiral passages for the actuating fluid, said spirals being composed of removable segments, means disposed in fixed relation to said cylinder heads for relieving the cylinder from end-thrust under the force of the incoming actuating fluid, and means for controlling the admission and exhaust of said fluid.

7. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drivcshaft extended centrally through said cylinder, a hub carried by said shaft, apertured heads closing the ends ofv said cylinder and carried in fixed relation to said hub and to said cylinder, spirals encircling said hub and connected both to said cylinder and to said hub, said spirals being disposed to form spiral passages for the actuating fluid, said spirals being composed of removable segments, means disposed in fixed relation to said cylinder heads for relieving the cylinder from end thrust under the force of the incoming actuating fluid, means for controlling the admission and exhaust of said fluid, and means for reversing the direction of travel of said fluid.

8. A turbine engine comprising an outer casing, a cylindrical rotor casing rotatable within said outer casing, a member extended centrally through said rot-or casing and having spirals interposed between it and said rotor casing, said spirals forming passages for the actuating fluid, apertured heads closing the ends of said rotor casing, means associated with said heads and rotatable with said rotor casing whereby pressure balance chambers are formed outside said rotor casing for preventing end thrust underthe force of the incoming actuating fluid, and means controlling the admission and exhaust of said fluid with respect to said chambers.

9. A turbine engine comprising an outer" casing, a hollow cylinder rotatable within encircling said hub and connected both to said cylinder and to said hub, said spirals being arranged to form unconnected spiral passages for the actuating fluid, and shiftable valves whereby the direction of travel.

ofsaid fluid is controlled.

10. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, a hub carried by said sha 't, apertured heads closing the ends of said cylinder and carried in fixed relation to said hub and to said cylinder, spirals en-' 1 circling said hub and'connected both to said cylinder and to said hub, said spirals being disposed to form spiral passages for the actuating-fluid, and a pair of piston valves controlling the exhaust of said fluid.

12. A turbine engine comprising an outer casing, a-hollow cylinder rotatable within said casing, aidrive-shaft extended centrally through said cylinder, a hub carried by said shaft, apertured heads closing the ends of said cylinder and carried in fixed relation to said hub and to said cylinder, spirals encircling said hub and connected both tov said cylinder and to said hub, said spirals being disposed to form spiral passages for the actuating fluid, a pair of piston valves controlling the admission and exhaust of said fluid, and meansfor simultaneously shifting said va ves for reversing the direction of travel of said fluid.

13. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, a hub carried by said shaft, apertured heads closing the ends of said cylinder and carried in fixed relation to said hub and to said cylinder, spirals encircling said hub and connected both to said cylinder and to said hub, said spirals being disposed to form spiral passages for the actuating fluid, a shiftable valve controlling the admission of said fluid, ashiftablevalve controlling the exhaust of said fluid, said valves being reversely disposed, and means for simultaneously shifting said valves for reversing the direction of travel of said fluid.

14. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, a hub in fixed rela tion to said shaft, apertured headsclosing the ends of said cylinder and carried in fixed relation to said hub and to said cylinder, spirals encircling said hub and con-' nccted both to said cylinder and to said hub, said spirals being disposed to form spiral passages for the actuating fluid, a shiftable valve controlling the admission of said fluid, a shiftable valve controlling the exhaust of said fluid, said valves being reversely disposed, cylinders in which said valves are located, and means for admitting a pressure fluid to said cylinders for accomplishing the shifting of said valves.

15. A turbine engine comprising an outer casing, a hollow cylinder rotatable within said casing, a drive-shaft extended centrally through said cylinder, a hub carried by said shaft, apertured heads closing the ends of said cylinder and carried in fixed relation to said hub and to said cylinder, spirals encircling said hub and connected both to said cylinder and to said hub, said spirals being disposed to form spiral passages for the actuating fluid, a shiftable valve controlling the admission of said fluid, a shiftable valve controlling the exhaust of said fluid, said valves being reversely disposed, cylinders in which said valves are located, means connected to the opposite ends of said cylinders for admitting a pressure fluid, means maintaining one end of each cylinder closed when the other is open, and means for shifting the pressure fluid with respect to said ends to reverse the position of said valves for reversing the direction of travel of the actuating fluid.

16. A turbine engine comprising an outer casing, a cylindrical rotor casing rotatable within said outer casing, a centrally disposed drive-shaft extending through said rotor casing, a hub fixed on said shaft, said hub having thereon a plurality of alternate longitudinal ribs and grooves, a plurality of spirals encircling said hub, said spirals being composed of a plurality of segments each of which has a portion seated in one of said grooves and has a portion interlocked with said rotor casing.

17. In a turbine engine, a rotor comprising a cylindrical casing having a plurality of internal spaced longitudinal grooves therein, a shaft extended centrally through said casing, a hub carried in fixed relation of said hub and has tenons seated in thegrooves of said cylinder.

18. In a turbine engine, a rotor comprising a cylindrical casing having a plurality of internal spaced longitudinal grooves therein, a shaft extended centrally through said casing, a hub carried in fixed relation to said shaft and having thereon a plurality of alternate longitudinal ribs and grooves. a plurality of spirals encircling said hub, said spirals being composed of segments each of which has tenons seated in the groove of said hubs and has tenons seated in the grooves of saidcylinder, each tenon being of greater thickness than that of the body of the segment, the tenons of alined segments serving to space the latter to provide an intervening passage of predetermin ed width.

19. In a turbine engine, a rotor embodying spirals composed of abutting segments whereby unconnected spiral passages are formed, each segment having its opposite faces fluted to form axially projecting in1- pact-receiving fins.

20. In a turbine engine, a rotor embodying spirals composed of abutting segments whereby intermediate unconnected spiral passages are formed, each segment having its opposite faces fluted to form axially pro;

jecting impact-receiving fins, the flutes of one face being staggered with respect to those of the other.

21. In a turbine engine, a rotor embodying spirals composed of-a plurality of segments disposed in closely abutting relation whereby unconnected spiral. passages are formed, each segment having its opposite faces fluted to form radially disposed projecting impact-receiving fins, the flutes of one face being staggered with respect to those of the other, and the arrangement of the horizontally alined segments being such that the fiutesof opposing faces in adjacent helices are-in staggered relation for rendering said passages tortuous.

In testimony whereof, I affix my signature in presence of two subscribing witnesses.

CARSON J. SHELDON.

l/Vitnesses THOS. J. HERBERT, GUSTAV C. GAST.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D, G

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