US2405190A - Fluid turbine - Google Patents

Description

Aug 6, 1945 l.. A. DARLING 2,405,190

FLUID TURBINE Filed March 5, 1943 6 Sheets-Sheet 1 iml Aug. 6, 1946. 1 A. DARLING 405,390

FLUID TURVBINE Filed March 5, 1 943 vsheets-Sheet 2 .Hizo/v@ ,W mm UL nm ID A. m w E L l1g- 6, 1945 L. A. DARLING 2,405,190

FLUID TURBINE Filed March 5, 1945 6 Sheets-Sheet 5 1m/611,50; LE\N\S A. DARLJNG Aug. 6, 1946. l.. A. DARLING FLUID TURBINE Filed March 5. 1945 e sheets-sheet 4 ug- 6, 19465 L. A` DARLING 2,405,199

FLUID TURBINE Filed March 5, 1943 e sheets-sheet 5 Aug- 6, 1945- L. A. DARLING 2,405,190

FLUID TURBINE Filed March 5, 1945 6 Sheets-Sheet 6 Patented Aulg. 6, 1946 Lewis A. Darling, Elkins Park, Pa., assignor of eighty per cent to Peerless Turbine Corporation, Wilmington,`Dei a corporation of Dela- Wavre Applicationy Maren 5, 194s, serial Nn. 478,140

(ci. lso-41) 26 Claims.

This invention relates generally to power generators and more particularly to generators of the turbine type that are adapted to be actuated through the medium of an elastic uid, such as steam, air, gas-water, or the like, it being among the principal objects of the present invention to provide improvements in the form and construction of the wheel buckets, the generator wheel, so as to increase the operating efficiency of the generator as a whole and to provide for its economical and more rapid manufacture. In addition, the present invention has as one of its principal and general objects to so design and construct the turbine rotor, consisting of the wheel body and its associated wheel buckets, as to be of comparatively great stability and permanence of structure, the weight of the rotor being maintained at what may well be termed the irreducible minimum, all parts of the rotor being of exceedingly simple design and adapted for easy assembly to thereby eliminate the necessity of employing expensive tools and highly skilled labor in the construction and assembly of the rotor parts and to thereby elect a material saving of time in the manufacture of the power generator of the present invention.

As will appear more fully hereinafter, the present invention makes it possible to employ to the best advantage any or all of the modern materials that are inherently strong and durable, resistant to corrosion, heat and abrasion, such as stainless and chrome nickel steel, etc., and the improved methods of manufacturing that have been developed to date.

In order to provide a construction of turbine having the least possible Weight with comparatively great strength and stability, the present invention has as its object the construction of the rotor wheel body formed largely of sheet metal stock and wheel buckets formed of relatively thin sheet metal stock, the sheet metal parts being designed and formed of such shape and having such capability of interlocking assembly as to produce a more or less skeleton or hollow wheel body structure and associated wheel buckets having the greatest possible strength, the several sheet metal parts of which the rotor unit is fabricated being manufactured and adapted for assembly Without the necessity of resorting to the use of the extra line machining operations with their attending close tolerance requirements, such as are usual in the case of high speed turbine wheel structures of ordinary commercial design that are constructed of more or less solid elements rigidly assembled.

'I'he principles of the present invention may be utilized in the construction of various types of turbine wheels as, for example. one type having wheel buckets designed to receive the propelling uid that is directed toward the peripheral margin of the wheel, and another type wherein the velastic fluid which propels the wheel is directed toward the side thereof at a point adjacent and just within the peripheral margin of the wheel and is exhausted from the periphery of the wheel. With respect to that form of turbine wheel wherein the propelling elastic uid is directed toward the peripheral margin of the wheel, it is a special purpose of the present invention to so construct the wheel buckets as to provide for a divided and re-directed iiow within thebucket of the propelling uid which latter, as it is directed into a given bucket, is separated into two distinct streams that respectively exhaust from opposite sides of theturbine wheel. By dividing this stream ow of elastic iiuid into two parts of equal volume, the axial thrust may, by proper bucket design, be neutralized so that the wheel will be in balance insofar as end thrust is concerned.

To this end, in one form of the present invention, the wheel bucket is provided with a central partition wall which serves to smoothly divide and change the directional ow of the elastic iluid that is discharged from the delivery noz.. zles and passes into and through the bucket channel-ways. The construction and form of the divided bucket is such as to provide a pair of substantially U-shaped channels, each of which insures acceptance and discharge of the propelling iiuid along lines which extend approximately tangential to the circle of the wheel buckets, the flow of the iiuid as it traverses each U-shaped bucket being reversed in direction through almost degrees.

Another form of bucket within the scope of the present invention is one that receives the propelling uid at the wheel periphery and exhausts this fluid from one side only,the wheel bucket channel-way being of U-like shape similar to those hereinbefore described.

Also included within the purview of the present invention is the design and construction of a large capacity wheel bucket of U-shape as hereinbefore generally described, the channel-way of each bucket embodying therewithin one or more U-shaped partition walls that separate the elastic driving iiuid into more or less parallel-owing approximately band-like streams as it passes through the wheel, thereby insuring increased ef- 3 flciency of operation, especially where the volume of elastic fluid handled is large.

Still another and important object of the present invention is to provide in a turbine of the character hereinbefore described means for making possible the use of a cooling medium,- the function of which is to hold down the temperature of the wheel and create other beneficial effects, especially in turbines designed for use in superchargers and which are driven by exhaust or other gases of extremely high temperatures. To this end, the wheel buckets of the present invention may be described generally as being provided with hollow interiors which are in communication with the interior of the wheel proper and which buckets are provided with discharge openings in the sides thereof through which the coolant may be discharged. Preferably, these coolant outlets are so designed as to discharge the coolant in directions substantially parallelng the direction of discharge of the propelling fluid from the exit ends of the wheel buckets so as to thereby establish a reaction force similar to that of a reaction type turbine. Thus, the coolant. that may be water which is converted within the hot wheel into steam, can be employed to produce some additional driving power for the turbine without any appreciable expenditure of extra energy, and, in fact, even in the case where the coolant need not be employed for the express purpose of holding down the temperature of the wheel, it may, nevertheless, beutilized, i! desired, as a means for increasing the power output o! the turbine at a negligible expense.

Turbine power generators that combine the use of nozzles, wheel buckets and wheel bodies which fall within the scope of the invention can be built to designs of practically any or all types of impulse turbines that have been developed. Such turbines range from single pressure stage to multi-pressure stage turbines with single velocity or multi-velocity type of wheel bucket within each pressure stage.

Another type of turbine to which this invention inherently applies is the gas driven turbine which can be operated by gas especially generated and applied as an elastic fluid or by exhaust gas from a gas engine. V

Other objects and advantages of the present invention will appear more fully hereinafter, it being understood that the present invention consists substantially in the combination, construction, location and relative arrangement of parts, all as described morefully hereinafter, as shown in the accompanying drawings and as finally pointed out in the appended claims.

In the accompanying drawings, which are intended to be illustrative of the principles of the present invention and which show certain preferred constructions embodying these principles,

Figure 1 is a partial vertical section taken in the central median plane of a turbine constructed in accordance with and embodying the principles of the present invention;

Figure 2 is an end elevational view of said turbine, the upper half of which is shown in section;

Figure 5 is a view showing the iiat blank of one element o! which the wheel bucket is formed;

Figures 5a and 5b are side elevational and top plan views respectively of that element of the wheel bucket which is formed of the blank shown in Figure 5:

Figure 6 is a view showing the sheet metal blank of which the second element of the wheel bucket is formed;

Figures 6a and 6b are top plan and side elevational vlews respectively of the second element of the wheel bucket which is formed of the blank shown in Figure 6;

Figure 'I is a perspective view of the bucket element formed of the blank shown in Figure 5:

Figure 8 is a perspective view of the same element rotated through approximately degrees;

Figure 9 is a perspective view of the bucket element formed ci.' the blank or Figure 6;

Figure 10 is a view illustrating the manner of nesting together the several bucket elements oi Figures 'l and 9 to produce a plurality of wheel buckets; i

Figure 11 is a perspective view showing a plurality of the bucket elements assembled to produce one full bucket and front and back portions of a second and third bucket;

Figure 12 is a top plan view of the assembly shown in Figure l1;

Figure 13 is a vertical sectional view taken on the line I3-l3 of Figure 12;

Figure 14 is a vertical sectional view taken the line lI-l l of Figure 12;

Figure 15 is a horizontal sectional view taken on the line l5-I 5 of Figure 14;

Figure 16 is a perspective view of a wheel bucket assembly similar to that of Figure l1, but illustrating a modified form thereof;

Figure 17 is a vertical sectional view o1' a plurality of buckets assembled as in Figure 16;

Figure 18 is a horizontal sectional view taken on the line IS-l of Figure 17;

Figure 19 is a partial sectional view of a turbine wheel or rotor employing the wheel bucket of the form shown in Figure 16;

Figure 20 is a vertical sectional view of the turbine wheel or rotor of Figure 19;

Figures 21 and 22 are views similar to Figures 19 and 20, respectively, but showing variations in the construction of turbine wheel;

Figure 23 is a partial sectional view of a turbine wheel or rotor of the type wherein the pro- 4 peiling uid laterally impinges the wheel buckets through one side thereof and is directed therethrough for discharge in the peripheral surface of the wheel, this figure being taken substantially on the line 23-23 of Figure 24;

Figure 24 is a sectional view taken substantially on the line 24-24 of Figure 23;

Figure 25 is a view of a sheet metal blank of which one element of the bucket of Figures 23 and 24 is formed;

Figure 26 is a view of the sheet metal blank of which the second element of said bucket is formed:

Figure 27 is a horizontal sectional view tf'en on the line 21-21 of Figure 23; and

Figure 28 is a perspective view of a single ow bucket assembly formed of the blanks of Figures 25 and 26.

An important feature ol' the present invention is that it permits the use of a novel method of design and layout in order to obtain a wheel bucket that will etliciently meet requirements. By means of this method, which involves the use of iiat sheet stock, a turbine bucket can be "laid out and formed from :dat blanks as hereinafter described, which blanks can then be shaped and fabricated into the desired wheel bucket Without the great expense of tooling up as is required in the conventional production of turbines. 'I'his method is especially valuable in experimental work or in making one or only a few turbine wheels to meet a given set of conditions.

Having determined on the exact design of a desired wheel bucket, the element portions thereof are initially blanked and formed, it being possible, in accordance with the present invention, to make a bucket from'only two such element portions shaped to nest in assembly around the wheel body periphery and form channelways or passages to eflciently handle the elastic fluid passing through the wheel. However, before describing in detail the construction of such bucket, it is deemed advisable to describe generally a form of power generator of the turbine type in which may be incorporated the buckets as constructed in accordance with the present invention and, accordingly, reference is now made to Figures 1 to 3 of the drawings.

Referring now more particularly to these Figures 1 to 3, it will be observed that they show a turbine having a split external housing consisting of a pair of axially spaced upper members lIl-IIIa and a pair of axially spaced lower members IIlb-Illb, which members are secured together in any suitable manner to provide an internal chamber for the elastic propelling iiuid, such as steam, the axially spaced outer walls of the turbine housing being provided with suitable bearing and packing units II-I I for the rotor shaft I2 of the turbine. The turbine housing is suitably provided with an elastic iluid chest I3 having an inlet passage' I4 by which the elastic fluid under high pressure is delivered into the internal chamber of the turbine.

Immediately associated with and secured to the fluid inlet chest I3 is a nozzle block I5, this nozzle block being provided with a plurality of nozzle elements I6 (see Figure 1) which are arranged in spaced relation across the opening in the nozzle block and are each of such shape and relatively so inclined as to provide a"plurality of gradually expanding nozzle openings I1 through which the elastic propelling fluid is delivered to the buckets of the turbine rotor. These nozzle elements I6 may be formed as solid elements, or they may be formed of sheet material.

In the particular form of power generator illustrated in Figures l to 3 inclusive, the internal chamber is constructed to provide for two pressure stages, the chambers for these stages being respectively denoted by the reference characters P1 and P2. It will`also be noted that in the type of turbine illustrated, the chamber for the first pressure stage P1 is flanked on each side by a `chamber for the second pressure stage P2, the

central chamber P1 being separated from-the outer chambers P22-P2, by annular diaphragms III-I8, each of which has its outer peripheral edge immovably secured, as at I9, to the annular rim of the external housing of the turbine. The central portions of these diaphragms |8|8 are closelyfitted about thel turbine rotor shaft I2, preferably by the use of suitably packing rings 2li- 20, which' latter prevent escape of the elastic fluid from the central pressure stage chamber P1 to either of the outer pressure stage cham bers Pl along the shaft I2.

Secured to the shaft I2 for rotation therewith is a central rotor unit designated generally by the reference numeral 2|, and a pair of outer rotor units respectively designated generally by the reference numerals 22 and 23. The central rotor unit 2| is, of course, confined between the stationary diaphragms |8|8, while the outer rotor units 23--23 are respectively disposed outside of the stationary diaphragm members |8I8.

The central rotor unit 2| essentially consists of a main hub 24 which carries a radially extending rotor wheel 25 formed of a pair of sheet metal plates 26-21 suitably secured together, the inner portions of which embrace an annular spacer member 25e. The central wheel formed of these plates 26-21 is fitted upon its peripheral edge 23 with a series of circumferentially spaced wheel buckets 29, these buckets being of a. form and construction, as will be described more specilically hereinafter, to provide .for a divided and redirected iiow of the elastic propelling uid so as to separate the latter into two distinct streams that respectively exhaust from opposite sides of the central turbine wheel.

Also carried by the hub 24 of the central rotor unit for rotation with the central wheel 25 are a. pair of outer discs or platemembers 3IJ-3I which are secured and held together, in the as.. sembled relation shown (see Figure 2), by transversely extendingrivets 32 and by welding the parts together. The discs SI1-3| are suitably provided at their peripheral edges with inturned portions 33 which respectively provide seats for two sets of additional buckets 34 and 35, the set of buckets 34 and thel set of buckets 35 being disposed to either side of and in axially spaced relation with respect to the central set of doubleflow buckets 29. AIt will be understood, of course, that the central rotor unit consisting of the central wheel 25 with its peripheral buckets 29, the outer disc 3|) with its peripheral buckets 34, and the outer disc 3| with its peripheral buckets 36, all rotate as a unit with the turbine rotor shaft I2.

In addition to the several sets of buckets just described, the turbine illustrated in Figures 1 to 3 is provided with two additional sets of lbuckets respectively designated 36 and 31, the set of buckets 36 being secured about the peripheral edge of the wheel 22 in the left-hand pressure chamber P2 and the set of buckets 31 being secured to the peripheral edge of the wheel 23 in the right-hand pressure chamber P2. These additional sets of buckets 36 and 37. of course, rotate in unison with the several sets of buckets disposed within the central pressure chamber.

Provided internally of the annular nozzle block I5 and arranged to either side of the circular row of wheel buckets 29 are a pair of stationary reguide buckets 38-39 (see Figure 2). The set of stationary reguide buckets 38 is disposed between the set of double-dow rotating buckets 23 and the set of buckets 34, while the reguide buckets 33 are disposed between the double-flow buckets 23 and the buckets 35. Extending circumferentially about the stationary partition plates or discs III-I8, adjacent the marginal edges of each, are a series of nozzles Ill-4I, the nozzles 40 being disposed between the rotating buckets 34 in the Afirst pressure stage chamber P1 and the buckets 36 in the left-hand second stage pressure chamber P2, while the nozzles 4| are similarly disposed between the buckets 35 of pressure chamber P1 and the buckets 31 of the right-hand bucket chamber P2.

The elastic propelling fluid employed to drive 7 the turbine, which may be steam, is supplied to the fluid chest i3 by way o! a suitable valve or valves which are regulated by a governor to insure maintenance of an approximately constant pressure of uid as it enters the uid chest I3. Inasmuch as the valves and pressure regulating governor are more or less conventional in turbine constructions, they are not shown in the drawings and are not speciiically described herein. The constant pressureiiuid in the chest I3 is delivered by way of the nome II-I1 into the first pressure stage chamber Pl of the turbine. By properly designing this nozzle, the fluid, as it passes therethrough, increases in velocity at the same time that the pressure drops from its initial high value existing in the chest I3 to the lower pressure existing in the first pressure stage P1 of the turbine. The iluid, as it issues from the nozzle IE-IL merges into the form of a definitely directed, smooth-ilowmg and continuous band or stream which iiows without shock into the entrances of the wheel buckets 23 of the central turbine wheel 25. The ilow oi iluid into these buckets 23 is directed toward the periphery of the wheel 25 and along lines approximately tangential to the outer circle of the buckets, and since the fluid at this point is at its highest velocity and'in its most perfect stream-like condition, and further, since its greatest 4force is made use of at its greatest distance from the center of the wheel, the maximum amounto! rotative force is obtained.

In view of the unique construction oi the buckets 29 of the central wheel 25, which construction will be described in detail hereinafter, the fluid which is delivered into these buckets. is divided into two streams and is then further redirected for discharge from opposite sides of the buckets after having been directed through an arcuate path of almost 180 degrees, the separate streams of iluid discharging from the opposite sides of the central wheel buckets being directed along lines which are approximately tangential with the circle of the discharge outlets on either side of the buckets.

The dual streams of uid which thus issue from 'the discharge outlets provided at opposite sides of the central-wheel buckets 29 are employed to impart further rotative effort to the turbine rotor by directing them to and through the axially spaced outer sets of wheel buckets 3I-33 and 3G-31. Thus, as will appear most clearly from Figures 2 and 3, the fluid, as it emerges from the left-hand side of the central wheel buckets 29, is directed through the reguide buckets or passages 38 and thence to the rotor wheel buckets 34, while the iluid which emerges from the right-hand side of the central wheel buckets 29 is directed through the reguide passages 39 and thence to the rotor wheel buckets 35.

The rotor wheel buckets 29 and 34, as do the rotor wheel buckets 29 and 35, provide a two velocity stage wheel within the pressure stage chamber P1, the buckets 34 constituting the second velocity stage of the left-hand half of the central rotor unit and the buckets constituting the second velocity stage of the right-hand half of said rotor unit. The buckets 29, of course, constitute the iirst velocity stage and it will be understood that all oi these rst and second velocity stage buckets operate under the constant pressure maintained in the rst pressure stage chamber P1 of the turbine.

Where sumcient pressure drop is available, as

in the form of turbine illustrated in Figures l to 3 to provide for a second pressure stage P2, the iluid discharged from the second velocity stage buckets 3l is directed through the stationary nozzles 40 and thence into the axial flow buckets 36 carried upon the outermost left-hand rotor wheel 22.`

Similarly. the iiuid discharged from the second stage velocity buckets 35 is directed through the stationary nozzles Il to and through the outermost right-hand axial ilow buckets 31. By so directing the iluid into the outer sets of buckets 36 and 31, additional energy is provided in the second pressure stage chamber P2 for increasing the power output of the turbine. The fluid which issues from these second pressure stage buckets 3B and 31 ilnally discharges from the turbine b`y way of the discharge openings 42 and 43. It will be observed at this point that in the form of turbine illustrated in Figures 1 to 3, end thrust is practically eliminated by reason of the fact that provision is made for directing the iiuid into the turbine at the center thereof and then dividing and redirecting it in opposite directions to impart energy to the axially spaced sets of wheel buckets arranged to either side of the central set of wheel buckets.

The direction of flow of the elastic uid as it enters and passes through the turbine of the form shown in Figures 1 and 2 is more or less diagrammatically shown in Figure 3. The central wheel buckets 29, which initially receive the fluid from the nozzle lE-I1, is designed to receive, divide and reguide the fluid in such manner as to insure smooth continuous smooth-ilowing separate streams, the divided channels of the buckets 29 being -at all times substantially iilled with the moving fluid, the fluid being maintained in as perfect formation as possible until it is finally discharged from the buckets 36 and 31 of the single velocity stage wheels 22 and 23 respectively disposed in the second pressure stage chambers PLP.

The double-flow power generator as just described, is really two turbines in one, and when properly designed effects a considerable reduction of surfaces and a saving in material and production costs as compared with two single turbines or a single larger turbine necessary for a given power development. Generally speaking, the quantity ow of elastic fluid is approximately equal in each of the two divisions of the turbine that are located on each side of the central or median plane of the turbine. mately one-half of the turbine may be employed to maintain the full load demanded of it, while the other half may be employed to take care of any overload on the turbine and also to provide for the extraction of steam for auxiliary commercial uses in such quantities and at such pressures as may be eiiiciently permissible. It can readily be understood that that half portion of the turbine which carries the full normal turbine load can, under such constant working conditions, be designed to give high eiiiciency, while the other half portion of the turbine can be designed to give the best eiliciency possible to carry the varying overload and the varying steam extraction load. In this way, a greater overall eiliciency is obtained than is possible with the ordinary turbine Whose eiiciency is adversely affected by variations in the power loads that must be delivered and in the quantities of steam that must be extracted.

'Ihe construction of the central wheel dual- Aflow bucket 2l,- as employed in the form of tur- Thus, approxibine illustrated in Figures 1 and 2, will now be described in detail, and in connection therewith, reference is more particularly made to Figures 4 to 14 inclusive. As will appear from these latter figures, the dual-flow buckets 29'of the central wheel of the turbine hereinbefore described are formed of a plurality of pairs of elements which are individually shaped and nested together and then assembled upon the rim of the central wheel of the turbine to thereby constitute a plurality of circumferentially spaced buckets, each having a pair of laterally spaced passages or guideways for the separated streams of elastic uid. Each pair of these elements consists of a uid thrust element such as is shown in perspective in Figures '1 and 8 single blank 48 of sheet metal stock, of the gene eral configuration shown in Figure 6. While as has been indicated, the blanks 41 and 48 are each single units, as respectively shown in Figures 5 and 6. manufacturing exigencies may make it advsable to divide on or the other or both of these blanks into two or more pieces, which pieces may then be formed and assembled together to constitute the'completed bucket body.

With reference first to the blank 41 of Figure 5, it will be observed that it is symmetrical about the longitudinal center line a-a and that it is formed to provide several portions which are respectively delineated as follows: the portion v49 delineated by the lines extending between the points b-0-d-e--g-h-, which forms the .front surface of the bucket for receiving the thrust of the elastic fluid that issues from the nozzle and is directed toward the periphery of the bucket wheel; the portion 58 delineated by the lines extending between the points e-i-kd-lm-n-o-p-f, which forms the bucket back or guiding surface for the fluid; the lateral wing portions 5l`-5 provided upon either side of the portion 49; the lateral Wing portions 52-52 provided to either side of the portion 68 and the flange portions 53-53. I

As most clearly appears in Figures 5A, 5B, 7 and 8, the front or thrust surface portion 49 of the bucket forming blank 41 is smoothly bent into substantially the arc of a circle to provide a curved thrust surface 54 (see Figures 5A and 8) which rises upwardly from the substantially flat forward portion to the point 56, this latter point being coincident with the line e-f of the blank 41.

The portion 50 of the blank 41 is rearwardly and downwardly bent about the transverse line et0 prOvide a curved back or iluid guiding surface 51 for the bucket element 45, this curved surface 51 being relatively so disposed as to be in spaced relation with respect to the front or thrust surface 54 of said bucket element. As will appear from Figure 5, the portion 50 of the blank 41 is notched as at 58 to provide a pair of generally diverging portions Sil- 59, and as appears most clearly in Figures 5B, '1 and 8, these divergent portions 59-59 respectively constitute the laterally spaced portions -60 of the curved back or guiding surface of the bucket element.

these portions 60-60 being separated from each other by the V-shaped notch 58 of gradually increasing width in'a direction extending rearwardly from its front or apex point 6 l The lateral wing elements 52-52 are upturned into substantially parallel relation, while the flange elements 53 are also upturned,` all as appears most clearly in Figure 8. At the same time, the lateral wing elements 5| of the portion 49 of the blank are downwardly turned into substantially parallel relation.

By so shaping and forming the bucket blank 41 as just described, the bucket element 45 is obtained, this element being provided with the curved front thrust surface 54 and the curved back guiding surface 61, which latter consists of the laterally spaced curved surfaces 60-68. Front and rear curved surfaces of the bucket element 45 merge along the line e-J of the blank 41 to form the relatively sharp bucket lip 56. While the bucket element 45 has been shown in the drawings as being formed of a single blank 41, it will be understood that the said blank 41 may be separated, if desired, into convenient parts, each of which may be independently shaped and formed preliminarily to assembling them together. Thus, for example, manufacturing exigencies may make it advisable to separate the blank 41 along the line e--f so as to enable the portions 49 and 50 to be separately formed and then joined together, by welding or otherwise, along the line which forms the lip 56 of the bucket element.

The second bucket element, which has been designated generally by the reference numeral 46 and which is shown most clearly in perspective in Figure 9, is formed of the blank 48 shown in Figure 6. As in thecase of the blank 41, the blank 48 is also symmetrical about its longitudinal center line a'-a'. This -blank 48, which is also formed of thin sheet metal stock, may be described as consisting of a plurality of different portions as follows: the central bridge portion 62; the laterally spaced similar portions 63-63, which are respectively contiguous with the opposite ends of the portion 62 along the lines b-b'; the laterally spaced similar portions 64-64, which are respectively contiguous with the portions 63-63 along the lines c-c; the portions 65-65, which are respectively contiguous with the portions 64-64 along the lines d-d'; the laterally spaced triangular portions 66-66, which are respectively contiguous with the portions 63-63 along the lines ee; the laterally spaced wing portions 61-61, which are respectively contiguous with the portions 66-66 along the lines f'f'; and the laterally spaced flange portions 68-68, which are respectively contiguous with the portions 65-65 along the lines g-g'.

This blank 48 is shaped and formed to provide the second element 46 of the bucket body, which latter is shown most clearly in Figures 6A, 6B and 9. By reference to these figures, it will be observed that upon properly shaping the blank 48, the central bridge portion 62 thereof is bent along the longitudinal center line aa' to provide a wedge-shapedsection having a horizontally inclined, relatively sharp upper edge 69 and a pair of downwardly divergent side members 1li- 10. The portions 63, 64 and 65 extend generally upwardly in laterally spaced relation to provide the side guide walls of the bucket body, it being observed that the portions 65-65 are slightly inclined out of the plane of their con'- ure 6, it will be noted that the central bridge portion 82 of the blank is provided adjacent its opposite ends with the more or less pointed projections 1l-1I, which projections are respectively bent inwardly out of the divergent planes of the members 10-10 forming the wedge-shaped portion of the bucket element 46, as appears most clearly in Figure 9. These elements 1l1lvserve as spacers for assisting in maintaining the bucket elements 45 and 48 in properly assembled relation and also to assist in closing the sides of the bucket.

'I'he shaped bucket elements 45 (Figure 8) and 48 (Figure 9) are adapted to be nested together and assembled in the manner illustrated in Figures 1o to 15 inclusive to produce the dualiiow buckets 28 hereinbei'ore described as being mounted upon the central rotary wheel of the turbine shown in Figures 1 and 2. 'I'hese bucket parts 45 and 48, it will be understood, are assembled in alternating relation about the periphery of the rotor wheel, as many pairs of these parts 45 and 48 being employed as is necessary to produce the required number of circumferentially spaced buckets upon a rotor wheel of predetermined diameter. In assembling each pair of these bucket parts 45 and 48, it will be observed that the bucket side wall enclosing part 48 is so assembled with respect to the thrust receiving part 45 of the bucket as to dispose the wedge-shaped portion of the former in close engagement with the rear of the bucket part 45. When so nested together, the relatively sharp upper edge 89 cf the wedge-shaped portion of the part 48 is snugly fitted within the apex end of the rearwardly diverging notch 58 of the part 45, while the downwardly divergent members 18-18 of the part 48 extend partially within and respectively engage the opposite edges of said notch 58. In other words, the wedge-shaped portion of the part 48 fits within the notch 58 of the bucket part 45. At the same time, the laterally spaced frontal sections of the part 48, each of which is composed of the portions 83, 84 and 85. respectively extend forwardly of and embrace the side edges of the curved thrust portion 54 of the part 45,' to thereby provide side enclosing walls for the front or thrust receiving surface of the bucket. The parts 45 and 48 thus nested together are held in their assembled relation by means of the flanges 88-88, which are crimped over the upper edges of the wing portions 52-52, thus securing the said wings 52-52 of the part 45 in overlapping relation with respect to the forward portions 55-85 of the immediately adjoining part 48, at the same time that the wings 81-81 of said part 48 lap over the wings 5I--5I of the part 45.

It will be understood, of course, that in order l2 spaced complete buckets are formed, these buckets being secured to the rim of the central rotor wheel by means of the downwardly extending mounting flanges.

It will be observed that when the bucket parts are assembled as just described, the portions of the divergent members 18-18, which project above the curved back surfaces -60 of the part 45, serve to divide each bucket channel into a pair of laterally spaced passageways for said fluid. In this connection, it will be noted that the rear edges of the members 1li-18 are smoothly curved, as at 12, to follow the contour of the curved thrust surface 54. The bucket channel which receives the elastic fluid from the turbine nozzles as hereinbefore described, is designated by the reference numeral 18, and it is this channel 13 which is divided into a pair of laterally spaced passageways respectively designated 13a-131 i see Figure 1l).

The divergent members 1li-10 of one of the parts 48 of the bucket respectively form with the corresponding members 18--10 of the next succeeding similar part 48 of the bucket, a pair cf paths or guidewaysv 14 having discharge outlets 15 disposed to either side of the bucket (see Figures l1 and 15). These passageways 14-14 constitute reversely directed continuations of the fluid entrance passageways 13e-13, it being apparent that each bucket is thus provided with a pair of laterally spaced substantially U-shaped passages for the elastic fluid stream, each of which accepts an equal portion of the elastic fluid which is directed into the bucket opening 13 from the turbine nozzle I8--I1 (Figures 1 and 2)k and guides it through the curved path formed between the curved thrust surface 54 and the guiding surface 80 for final discharge from the bucket by way of the discharge outlet 15. By properly designing and shaping the curved surfaces 54 and 88, which respectively constitute the thrust and guiding surfaces for the fluid stream passing through the fluid passage in a bucket, and by properly designing and shaping the members 10-10 in relation to said curved surfaces 54 and 88, a pair of laterally spaced fluid guiding passages are provided which increase in volume and area from the bucket entrance to the bucket exit. Inasmuch as these passages are each of substantially U form and of progressively increasing volumetric capacity from entranceto exit ends thereof, the elastic fluid accepted by each passage is smoothly guidedtherethrough and reversed in its direction of ow through approximately degrees so that although its velocity decreases, its volume increases to insure that the same amount of elastic uid that it delivered to the mouth of the bucket is exhausted from the discharge openings thereof. Consequently, the bucket passageways are at all times filled with fluid as the result of which vacuum cavity formations, eddy currents and the like, which tend to disturb the smooth flow of the elastic duid through the bucket, are practically eliminated.

Figure 4 shows a suitable construction of rotor wheel, the peripheral rim of which' is fitted with a plurality of the dual iiow buckets of the construction just described, the bucket wheel of Figure 4 being that which is generally designated in Figure 2 by the reference numeral 25. In this form of bucket wheel, a pair of oppositely dished circular plates 26-21 are secured together in the relation shown in Figure 4 by means of an annular spacer member 18 and a pair of annular hub elements 11-18. These hub elements which are I 13 suitably non-rotatively secured upon the turbine shaft I2 are pressed together to securely clamp therebetween the wheel discs 26--21 and their intervening spacer element 16. If desired, in order to provide for a, rigid unitary structure, the parts may be welded together as at th'e points marked at. The outer edges of the discs 26-21 are respectively provided with oppositely turned anges 18M-18a, which are disposed in a common plane to provide a circular rim (designated labout the undersurface of the wheel rim flanges 18a-19a, as indicated by the reference numeral 83 in Figure 4. Preferably, the retaining wings 80-8I are secured in place by welding the same to th'e discs as indicated at at.

While it will be understood that any suitable construction of rotor wheel may be employed for carrying the peripheral buckets 29, I prefer to construct such wheels of pressed sheet metal as shown because the circular plates 26-21 thereof may be readily shaped as desired to insure snug and secure mounting of the bucket forming parts thereon. Also, the wheel construction shown, being hollow, inherently provides for a comparatively stronger wheel per unit of material weight than other forms of construction commonly used,

at the same time that the stresses resulting from strains which are normally induced in the tur. bine by vibrations, impulses, expansions and contractions.

A particular advantage of the hollow form of wheel body construction is that it can be employed to deliver a coolant fluid to and through the wheel buckets to hold down the temperature of the 'Wheel and the buckets, especially in those turbines which are driven by exhaust gas from a gas or gasoline engine or by a high' temperature gas prepared for use as the power imparting iluid. Such a, turbine wheel is especially adapted for use in a, supercharger in connection with gas engine operation, in'which case water may be used as the coolant median, or in a supercharger operatively associated with an airplane engine operating in the stratosphere or high altitude, in which case the coolant median would be air.

Where water is employed as the coolant and is delivered into the hollow interior of the rotor wheel, the high temperature of the latter immediately converts the water as it enters into the e wheel into steam, thereby filling the whole interior of the wheel with steam under pressure. 'I'he interior of the wheel thus functions somewhat as a flash boiler, the pressure of the steam so generated within th'e wheel being dependent upon-the quantity of the water which is delivered into the wheel and the size of the discharge outlet which is provided for discharge oi' the steam from the wheel. The temperature of the steam is, of course, less than would be the temperature of the uncooled wheel, in consequence of which the operating temperature of the turbine wheel and the buckets is held down.

- In order to provide for this advantageous use of a coolant medianl the buckets carried by the wh'eel are so designed as to provide for discharge of the coolant median from the wheel by way of the buckets. Figures 16 to 20 inclusive show an arrangement of hollow wheel and associated wheel buckets for permitting such use of a coolant median, which may be water or air. As more particularly appears in Figures 16 to 18, the wheel buckets are essentially of the same form and construction as those hereinbefore described and designated generally by thereference numeral 28. They are of the dual-flow type which'accept the elastic driving Huid at the periphery of the wheel and separate it into two equal streams which are respectively discharged from opposite sides of the bucket by way of the discharge openings 15. They differ only from the previously described buckets in that they include provision for circulating therethrough and discharging therefrom the coolant median which is delivered into the hollow interior wheel'for cooling the latter and the buckets associated therewith. y This means will now be described.

It will be observed that a general characteristic of the dual-flow bucket 29 constructed and assembled as hereinbefore described, is that it includes a hollow space 84 (see Figures 13 and 14) between the front thrust surface 54 and the back guiding surface of the part 45. This recess or space 84 extends across the full width of the bucket with its opposite ends partially closed by the upstanding wings 52-52, complete enclosure of the opposite ends of each such transverse passage 84 being eiected by the wing members 52 of the next succeeding bucket part 45. It will also be observed that the frontal portions 64-64 upon opposite sides of the bucket part 46 are respectively received within the opposite wing members 52-52 of the bucket part 45, the

rear edges of the part 64-64 extending only Islightly beyond the opposite edges'of the front surface 54 in the immediate zone of the transverse passage 84. These portions 64--64 of the part 46 respectively diverge inwardly and away from the Wing members 52--52 of the part 45, this relationship of these parts being maintained by the triangular spacer portions formed between each wing 52 and the flange 53 of the part 45. These triangular spacer parts are designated in Figure 5B by the reference numeral 85. There is thus provided upon opposite sides of each bucket a space 86 which is in communication with the transverse space or passageway 84. In the form of bucket hereinbefore described in which no provision is made for the use of a coolant medium, these lateral spaces 86 are closed off to atmosphere and the transverse recess 84 is accordingly sealed by securing together adjoining wing elements 52 on either side of the buckets in the abutting relation shown by the dotted lines in Figure 18. l

However, in the case where the buckets are designed to receive a coolant medium, these wing members 52 on opposite sides of the circular row of buckets are each opened up as at 81 (Figures 16 and 18) to provide 'openings 88 which discharge to atmosphere, or, in the case of the turbine illustrated in Figure 2, into pressure chaml5 ber P. The buckets of Figures 16 to 18 are further provided with openings 89 formed centrally in the ilat base portion 55 of each bucket part 15. inasmuch as the transverse recesses 84 are mchin free communication with the space 90 formed between the downwardly divergent members 'l0-'I0 oi the Wedge-shaped portion of the part 46, and inasmuch as the openings 89 are nach so located as to be in free communication with each of the spaces 90 (see Figure 17), it will be apparent that a fluid delivered into the opening 89 may pass freely through the space 90, thence through the transverse space 84 and its lateral continuations 86 for final discharge from the bucket by way of the discharge outlets 8888 provided at opposite sides of the buckets.

Referring now to Figures 19 and 20, which illustrate a form of turbine wheel designed for use in connection with a coolant iluid, it will be observed that this wheel is of hollow construction and consists essentially of a pair of oppositely dished circular plates 9l-9|, which are suitably mounted in the spaced relation shown upon a hub 92, whichlatter in turn is non-rotatively fitted upon the shaft 93. The hub is provided with a plurality of circumferentially spaced passages 94 for delivering into the hollow interior of the wheel a suitable coolantl such as air.

Provided interiorly of the rotor wheel are a plurality of circumferentially spaced blades or vanes 95, which are suitably secured in any suitable manner so as to constitute rigid elements of the rotor wheel. Each of these blades extends the full distance between the opposite wheel plates 9I-9I and preferably have their opposite edges welded or otherwise joined to these plates. The outer extremities of the blades 95 are each similarly curved as at 96 so that upon rotation of the wheel, these members 95 act as fan blades to draw in and propel air through the wheel and force it out of the Wheel interior by way of the openings 89 of the dual buckets which are mounted upon the peripheral rim of the wheel. It will be observed in this connection that the outer prtions of the wheel plates 9|-9I are in spaced relation to provide an outer annular chamber 91 with which the openings 89 are in free communication. Any suitable means may be employed to secure the bucket parts in assembled relation about the wheel periphery, this being eected the particular form of construction shown 1n Figure 20 by wrapping the mounting flanges 98-98 of the bucket about the peripheral flanges 99--99 of the wheel plates and then securing them permanently in place by welding or by the use of retaining rings |00. In order to maintain the wheel plates 9l--9I in the spaced relation shown, a spacer band I0| may be employed which extends circumferentially about the wheel and is tted into annular shoulders respectively provided in these plates. The annular band |0I is, of course, provided with circumferentially spaced apertures |02, which are adapted for registry with the openings 89 of the buckets.

The turbine wheel shown in Figures 19 and 20 and just described, is especially adapted for use in a turbine which is driven by exhaust gas from a gas engine and in superchargers that operate in conjunction with gas engines for propelling airplanes through the stratosphere, where a supercharger of low weight having the greatest factor of safety is essential. In this last described form of turbine wheel, the coolant fluid passes through the interior of the wheel and through the peripheral wheel buckets for final discharge through the coolant discharge outlets 88-88 of the buckets. This cooling function is accomplished without any of the coolant medium coming into contact with or otherwise disturbing the elastic fluid which is used to drive the `turbine, the paths of ilow of the coolant medium and of the propelling medium through the buckets being quite independent of each other, the former exhausting from the buckets by way of the outlets 08 and the latter by way of the outlets 15. However, after these iiuids have performed their respective functions and are exhausted from the buckets, they merge with one another in the regions of such exhaust. This mingling of the driving and coolant fluids exhausted from the buckets provides a beneficial eil'ect in that the coolant tempers somewhat thehot exhaust gas and renders the latter less destructive to any surfaces with which it may come in contact. Also the coolant, if under pressure, has the effect of producing additional driving power for the turbine without any appreciable expenditure of extra energy, and even where the coolant fluid isnot employed for the express purpose of holding down the temperature of the Wheel, it may, nevertheless, be utilized as a. means for increasing the power output of the turbine at a negligible expense.

Figures 21 and 22 show still another form of turbine wheel designed for use in conjunction with the dual iluid construction of bucket shown in Figures 16 to 18. While this modified form of turbine wheel may also be employed for utilizing air or as the coolant medium; it is particularly designed for the use of water as the coolant medium.

As in the previouslydescribed form of turbine wheel, that of Figure 22 essentially consists of a pair of dished circular platesA ID3-|03 which are suitably mounted upon a central hub |04, which in turn is non-rotatively tted upon the shaft |05. The plates |03-l03 are maintained in the spaced relation shown by means oi an inner spacer ring |05a and an outer spacer band |06. The shaft |05 is axially bored as at |01 to provide a water inlet passage which is in communication with the hollow interior of the mleel by way of a plurality of radial passages The outer spacer band |06 is provided with a plurality of circumferentially spaced struckout tongues |09, these tongues projecting inwardly of the band |06 for disposition between the wheel plates |03|03. Preferably, these tongues |09 extend across the full distance between the plates IUS-|03 and are similarly curved so that they function as scoops to force the coolant medium outwardly of the wheel interior by way of the openings I I0 provided in the band |06. It will be observed that the elements |09 are generally of T-shape (see Figure 22) to provide oppositely extending portions each of which forms with the band |06 a notch H2. These notches H2 are, of course, spacedcircumferentially about the inner surface of the band |00 along each side edge thereof, and each circular set of these notches is adapted to receive therein the inwardly turned outer ange H3 of each wheel plate |03, thereby affecting an interlocking engagement between the band |06 and the outer edges of the plates I03-|03. By rst wrapping the mounting flanges H4 of the buckets about the opposite side edges of the band |06 and then assembling the bucket-tted band and the plates I03|03 17 together, these parts are al1 effectively and securely locked together.

Ii' the coolant medium employed in connection with the fluid turbine whee1 in Figure 22 is water, instantly upon its delivery by way of the passages |01 and |08 into the interior of the Wheel, it is converted into steam under pressure; This steam, which, of course, is of a temperature less than the uncooled temperature of the wheel and buckets, is forced by its own pressure through the outer portion of the wheel where it is scooped up by the tongues |09 and forced into and through the buckets for ilnal discharge therefrom by way of the coolant discharge outlets 88. It will be understood, of course, that these buckets are of a form and construction quite similar to those shown in Figures 16 to 18.

As in the previously described form of turbine wheel, the passages for the coolant, be it air, gas or water converted into steam, are wholly independent and apart from the passages through the bucket for the elastic driving fluid.

By way of example, it may be mentioned that the turbine wheels of Figures 20 and 22 might be employed as the rotor of a stratosphere superchanger turbine for gas engines. In such case, the turbine wheel would be impelled by a jet or Jets of gas exhausted by the engine, the gas being directed by suitable nozzle or nozzles into the turbine wheel buckets to impart rotation to the wheel. At the same time, the internal vanes of the turbine wheel act as a compressor of the coolant air delivered into the turbine and inasmuch as the temperature of the air in the stratosphere is very low, such cold air could be very effectively employed in cooling the turbine wheel of the supercharger.

The principles of the present invention employed in the construction f the divided flow bucket hereinbefore described are applicable as well to the construction of a single flow bucket, that is, abucket having a single passage for the elastic impelling fluid. Such a single flow bucket may be designed to accept the elastic driving fluid at the periphery of the wheel bucket circle, the iluid being delivered through the bucket through a. U-shaped passage of approximately 180 degrees,

for discharge through the side of the bucket exactly as in the case of the divided flow bucket hereinbefore described. In order to provide for such a construction, it would be merely necessary to divide the. blank 41 of Figure 5 along its longitudinal center line a-a, and the blank 48 of Figure 6 along its longitudinal center line a'-a'. Thereupon, a plurality of these half blanks would be formed and nested together in assembled relation upon a suitable mounting plate forming part of the rotor wheel of a turbine.

This single flow bucket may also be designed to receive the driving fluid at the side of the wheel and exhausted at the periphery, in which case the cross-sectional area of the U-shaped channel through the bucket progressively increases from the side entrance toward the peripheral discharge exit to thereby handle the driving fluid smoothly and `exhausted with the least frictional loss. A single flow bucket of this latter type is employed as the second velocity stage bucket in the righthand portion of the chamber P1 of the turbine shown in Figure 2, this bucket being therein designated by the reference numeral 35. The construction and form of this single flow second velocity stage bucket 35 is more particularly shown in Figures 23 to 27 inclusive.

Referring to these latter figures, it will be observed that the bucket is formed oi' two main body parts |I5 and ||8. It will be observed that the blank ||5 is substantially of the same shape as the left-hand half of the blank 41 of Figure 5, while the blank ||8 is substantially similar in shape to the left-hand half of the blank 48 of Figure 6. Thus, the blank ||5 includes a sideenclosing wing portion I I1, a flange I I8, a bucket back or fluid guiding portion I|9, a bucket front or iluid thrust portion |20 and a mounting flange portion |2I,l all of which portions find their respective equivalents in the left-hand half of the blank 41 of Figure 5. Also, the blank ||6 includes the several portions |22, |23, |24, |24, |25, |26 and |21, whose corresponding portions are to be found in the left-hand half of the blank 48 of Figure 6. The blank I|8 further includes a mounting flange portion |28.

The blank I 5 is bent sharply upon itself along the line e"f" at the same time that the portion |20 is curved to provide the frontal thrust surface of the bucket to correspond with the frontal thrust surface lit of the bucket part shown in Figure 8.

The portion ||9 is also curved rearwardly and downwardly to form the back guiding surface of the back corresponding to the surface 51 of the part shown in Figure 8. The wing element ||1 is turned upwardly as is the flange I I8, in the same manner as were the corresponding elements 52 and 53 of the part 45 in Figure 8. The mounting flange |2| is downwardly turned substantially at right angles to the forwardly extending portion |29 (Figure 25) of the curved thrust surface |20.

The blank ||6 is shaped to provide a formed part which corresponds substantially to one of the symmetrical halves of the formed part 46 of Figure 9, the mounting flange |28 of this formed part constituting a lateral extension of that edge of the shaped blank which corresponds to the ridge 89 of the part shown in Figure 9.

When the blanks ||5 and ||`6 are shaped into the forms just described, they may be assembled in nested relation, as shown in Figure 428, and mounted upon the peripheral rim of a turbine wheel to provide a series of circumferentially spaced single ilow buckets which are designated generally by the reference numeral 35 in Figure 2.

Figures 23, 24 and 27 show a particular construction of hollow turbine wheel which is fitted with this type of single flow turbine and which is designed to provide for the use of a coolant fluid to hold down the temperature of the wheel in accordance with the principles hereinbefore described. This turbine Wheel consists of a pair of sheet metal plates |30|3 I, which are secured in the spaced relation shown, upon a hub |32, which is in turn keyed or otherwise non-rotatively secured to a shaft |33. The plate |3| is of somewhat greater diameter than the plate |30, both of these plates |30 and |3| being provided respectively with oppositely turned peripheral flanges |34 and |35.

In assembling the bucket parts upon the hollow wheel, the bucket part formed out of the blank ||5 is fitted upon thewheel so that its edge |38 (see Figure 25) abuts against theinner surface of the wheel plate |3I, as at |31, the mounting ilange |2| being pressed around the flange |34 of the opposite wheel plate |30. The bucket part, when so mounted upon the wheel, provides a curved thrust surface |38 which extends upwardly from the portion |29 through approximately the arc of a circle to the lip |39 of the bucket.

The second part of the bucket formed out of the blank i6 nests with the first bucket part to provide the side-enclosing walls for the arcuate fluid channel, the inner wail being formed by the portion |22 of the part 6, the flange portion |28 of which is extended upwardly and about the peripheral ilange |35 of the wheel I3|. The portions |24, IMHA and |25 constitute the forward extension of the ychannel side wall |22, the mounting iiange |21 of the part |26 being lapped over the mounting flange |2I of the part ||5.

By assembling a number of the parts ||5 and IIE in'alternating relation, a series of circumferentially spaced'buckets are provided about the periphery of the wheel, each of which is provided with a side entrance opening for the bucket which corresponds with the opening 15 of Figure 11, the latter, however, being employed as a discharge outlet, whereas in the arrangement of Figures 23 to 27, such opening serves as the inlet for the elastic driving fluid. This uid is discharged through'the discharge outlets formed between the lips |39 of successive buckets, it being observed that the arcuate channel extending between the entrance and exit ends of the buckets are of progressively increasing cross-sectional area from entrance to exit end. This is the reverse of the fluid channel in the construction of Figure 11 wherein the cross-sectional area progressively increases irom the peripheral opening toward the side opening of each bucket.

In order to provide for the use of a coolant medium, the bucket part ||5 is apertured as at |40 to provide communication between the hollow interior of the turbine wheel and the chamber |4| formed between the portion |22 and the wheel plate |4i. This chamber i4| is in communication with side discharge outlets formed by opening up the wing elements I1, these side openings thus corresponding in every respect with those designated by the reference numeral 88 in the form of construction shown in Figure 16. The coolant medium is delivered to and through the interior of the wheel by any of the means hereinbefore described or by other suitable means, and is discharged from the buckets in directions' substantially paralleling the direction of discharge of the elastic driving uid from the buckets.

Where the wheel bucket last described is small and the elastic driving fluid passes freely and smoothly through its channel with substantially no self-interference, the channel may be in the 'form of a single passageway. However, Where the bucket is comparatively large, thus substantially increasing the cross-sectional aresl of the bucket channel, it may be advantageous to provide the channel way with a curved partition member |42, which is suitably iltted and secured in place between successive bucket parts for the purpose of dividing the stream of elastic driving fluid into a pair of comparatively narrow bands. These partition members function to divide the stream into these narrow bands while it is being reversed in direction of flow and thereby insures that each of the channel ways so formed is substantially filled with iluid and so avoid self-interference and the setting up of vacuum cavity formations and other such disturbances which might deleteriously affect the smooth flowing y character of the stream. These parallel flowing streams are indicated by the arrows in Figures 23 and 27, from which it will be observed that they merge at the bucket exit. In a comparatively large bucket designed to handle a large volume of steam, several such partition members may be employed within each bucket channel.

In the case where the buckets of the present invention are employed for receiving the elastic driving fluid at the peripheral edge of the turbine wheel, it will be n oted that the curved surfaces of the fluid channel through the bucket, these being the front or thrust surface 54 and the back or guiding surface 51 (see Figures 8 and l1), are relatively so formed that none of the fluid which is directed into the bucket directly impinges or strikes against the said back or guiding surface of the bucket. Instead, the fluid stream, which is directed into the bucket along a line which is practically tangential with the outer circle of the wheel buckets, flows smoothly over said back or guiding surface to substantially fill `the space between this surface and the succeeding front or thrust surface of the next bucket and is then smoothly guided and reversed in direction through an arc substantially degrees for final discharge from the bucket channel by way of its discharge outlet. In order to prevent any tendency for the elastic fluid to be splashed by the front lip or edge 56 of the bucket (see Figure 11), this edge is swaged or rolled or even ground or machined to form a comparatively sharp edge.

As in the case of the wheel buckets, the bodies oi the wheels, being formed of sheet metal in accordance with the principles of the present invention, also have important inherent advantages over Wheels constructed in the conventional manner. As has been indicated hereinbefore, the side plates of which the wheel bodies are formed can be readily shaped as desired to provide for increased strength with a minimum of weight to better allow for expansions and contractions and to practically prevent wheel distortion due to any cause. It is preferable to have the wheel plates formed with sides that slope outwardly of each other from the rim toward the hub of the wheel. This hollow wheel construction provides a comparatively stronger wheel unit of material weight than other forms of construction commonly used and more eiliciently offsets strains and stresses which may tend to be established in the turbine wheel when in operation due to centrifugal force. While the accompanying drawings show the fabricated wheel buckets mounted upon the rims of hollow sheet metal wheels, it will be understood, of course, that these buckets may be mounted upon any conventionally constructed wheel and, conversely, that the hollow sheet metal wheel of the ypresent invention may be employed in association with conventionally produced wheel `buckets.

It will be understood, of course, that the present invention is susceptible of various changes and modications which may be made from time to time without departing from the general principles or real spirit thereof, and 1t is accordingly intended to claim the same broadly as well as specifically as indicated by the appended claims. For example, in constructing the bucket forming parts out of sheet metal stampings, the latter may be changed somewhat from the form of stampings hereinbefore described so as to provide one of such stampings with elements which were hereinbefore described as forming integral parts of the other of such stampings and vice versa. Thus, one of such stampings may b'e of such shape and form that when pressed into shape, it forms as an integral unit the concave front or thrust surface equivalent to the portion 5| of the structure shown in Figure 8, which terminates at its upper end in a bucket forming lip, and the forwardly extending portion 55 and the mounting wings I, of Figure 8, together with apair of wing portions extending forwardly of the opposite side edges of the curved thrust portion to provide opposed side enclosing walls forthe fluid passage. On the other hand, the

" other complementally formed part of the bucket may include as integral parts thereof the back or uid guiding surface equivalent to the porvtion 5l of Figure 8, together with the,inverted V-shape part of the structure shown in Figure 9, which latter part includes the ridge 69 and the oppositely divergent member Ill- (see Figure 9), together with the mounting wings 61-61 thereof. When a plurality of these parts so modied are assembled and nested together they will form a series of buckets which in all essential respects are similar to the buckets formed of the parts 45 and 46 hereinbefore described.

What is claimed as new and useful is:

l. A turbine wheel bucket construction consisting of pre-formed sheet metal elements assembled together in nested relation to provide a series of bucket members each having enclosingside walls and arcuately shaped front thrust and back guide surfaces which merge along a line extending transversely of the plane of rotation of the turbine wheel to form the outer edge or lip of a bucket, each successive pair of said bucket members providing therebetween an eX- ternal arcuate passage for receiving and directing therethrough an elastic driving iiuid and said front thrust and back guide surfaces of each bucket member forming therewithin an internal passage for receiving and directing therethrough an elastic coolant fluid, the external and internal passages immediately associated with each 'bucket being whollyindependent of each other and being provided with discharge outlets arranged in such close proximity to each other as to cause the fluids exhausted therefrom to mingle together in the region of said outlets.

2. In a turbine wheel of the type including a central hub, circular side plates having annular rim forming iianges mounted on the hub and spaced apart to form a cavity therebetween and an inlet opening into said cavity, interlocking wheel bucket elements mounted on the wheel rim in-alternating relation to provide circumferentially spaced bucket members each having enclos--v ing side walls and arcuately shaped front thrust and back guide surfaces which merge along a line extending transversely of the plane of rotation of the turbine wheel to form the outer edge or lip of a bucket, the bucket elements being arranged to provide for each bucket an external channel for an elastic driving uid and an internal cavity for an elastic coolant fluid, said internal cavities being in communication with the wheel cavity to permit a coolant to be forced through said wheel cavity and into said internal cavities formed by said wheel bucket elements, and means for effecting independent discharge of the driving and coolant uids from the outer marginal side of the turbine wheel.

3. In a turbine wheel of the type including a central hub, circular side plates having annular rim forming iianges mounted on the hub and spaced, apart to form a cavity therebetween and an inlet opening into said cavity, interlocking Wheel bucket elements mounted on the wheel rim in alternating relation to provide circumferentially spaced bucket members each having enclosing side walls and arcuately shaped iront thrust and back guide surfaces which merge along a line substantially paralleling the turbine wheel axis to form the outer edge or lip of a bucket, the bucket elements being arranged to provide for each bucket an external channel for anelastic driving fluid and an internal cavity for an elastic coolant iluid, said internal cavities being in communication with the wheel cavity to permit a coolant to be forced through said wheel cavity and into said internal cavities formed by said wheel bucket elements, and means for effecting independent discharge of the driving and coolant fluids from the outer marginal side of the turbine wheel, said last-mentioned means being so located as to direct the discharged iiuids outwardly from the sides of each bucket in a direction substantially tangential of the turbine wheel and to provide for intermingling of the uids exhausting from a given single bucket assembly.

4. A turbine wheel bucket construction consisting of pre-formed sheet metal stampings assembled together in circumferentially spaced relation to form a plurality of circumferentially spaced passages for an elastic driving fluid each having a single peripheral entrance and a pair of laterally spaced separate side exits, certain of said stampings providing arcuately shaped thrust and guide surfaces which merge along a line extendingr transversely of the plane of rotation of the turbine wheel to form the outer edge or lip of a bucket, the said thrust and guide surfaces constituting, respectively, the front and rear walls of said bucket.

5. A turbine wheel bucket construction consisting of pre-formed sheet metal stampings assembled together in circumferentially spaced relation to form a plurality of circumferentially spaced substantially U-shaped passages for an elastic driving fluid each having a single peripheral entrance and a pair of laterally spaced separate side exits, certain of said stampings providing arcuately shaped front thrust and back guide surfaces which merge along a line extending transversely of the planeof rotation of the turbine wheel to form the outer edge or lip of a bucket and other of whichl stampings, arranged alternately with respect to and interlocked with said n last-mentioned stampings, constituting means for dividing each passage into a pair o f separate channel ways for the elastic driving fluid.

6. A turbine wheel bucket construction consisting of pre-formed sheet metal stampings assembled and secured together to provide a plurality of circumferentially spaced passages for an elastic driving fluid, each passage having a pair of arcuately shaped thrust and guidesurfaces which are spaced circumferentially about the turbine wheel axis with the thrust surface of any one passage and the guide surface of the next preceding passage merging along a line extending transversely of the plane of rotation of the turbine wheel to form the outer edge or lip of a bucket, certain of said stampings being arranged.

locking relation to provide a plurality of circumferentially spaced passages for an elastic driving uid, each passage having a pair of arcuately shaped thrust and guide surfaces spaced circumferentially about the turbine wheel axis with the thrust surface of any one passage and the guide surface of the next preceding passage merging along a line substantially paralleling said axis to form the outer edge or lip of a bucket, certain of said interlocking stampings being arranged to divide each of said passages into a pair of laterally spaced channel-ways having side discharge exits for the fluid and all of said stampings having cooperating means for enclosing the opposite sides of said passages and directing the fluid to and through said side exits in a direction substantially tangential to the wheel.

8. A turbine wheel bucket construction consisting of pre-formed sheet metal stampings assembled and secured together in nested, interlocking relation to provide a plurality of circumferentially spaced passages for an elastic driving fluid, each passage having a, pair of arcuately shaped thrust and guide surfaces spaced circumferentially about the turbine wheel axis with the thrust surface of any one passage and the guide surface of the next preceding passage merging along a line substantially paralleling said axis to form the outer edge or lip of a, bucket, certain of said interlocking stampings being arranged to divide each of said passages into a pair of laterally spaced channel-ways having side discharge exits for the fluid and all of said stampings having cooperating means for enclosing the opposite sides of said passages and directing the fluid to and through said side exits in a direction substantially tangential to the wheel, each of the passage-dividing stampings having a portion of substantially inverted V-shape to provide a pair of elements which diverge from the central median plane of the turbine wheel toward the opposite outer side planes thereof.

9. A wheel bucket assembly comprising a number of sets of pre-formed sheet metal parts, the parts comprising any one set being f a, shape identical with each other but different from the parts of another set and all of the parts being assembled with a part of one set alternating with a. complemental part of another set to provide a series of successive buckets circumferentially spaced apart to provide passages for receiving and directing therethrough an elastic driving fluid, said assembled parts providing for each bucket arcuately Ishaped front thrust and back guide surfaces which' merge along a line substantially paralleling the axis of rotation of the wheel bucket assembly.

10. A wheel bucket assembly comprising a number of sets of pre-formed sheet metal parts, the parts comprising any one set being of a shape identical with each other but diiferent from the parts of another set and all of the parts being assembled with a part of one set alternating with a complemental part of another set to provide a series of successive side-enclosed channels for receiving and directing therethrough an elastic driving fluid, the parts of one of said sets constituting the side Walls of said channels and the parts of another of said sets constituting a front thrust surface for a, given channel and a back guiding surface for the next preceding channel, both' surfaces being of arcuate form and spaced from each other forwardly of the line of juncture thereof, said line forming the lip or outer edge of abucket.

11. A wheell bucket assembly comprising a number of sets of pre-formed sheet metal parts, the parts comprising one set being of a, shape identical with each other but different from the parts of another set and all of the parts being assembled with a part of one set alternating with a part of another set to provide a series of successive side-enclosed channels for receiving and directing therethrough an elastic driving fiuid, the parts of one of said sets being each of generally inverted V-shape having downwardly divergent branches terminating in forwardly extending portions, the latter constituting opposite side enclosing elements for a given bucket and the ridge of the divergent branches constituting a fluid stream separator which extends from rear to front of a uid passage for a given bucket, and the parts of another of said sets* each constituting a front thrust surface for a given channel and a back guide surface for the next preceding channel, each pair of said latter surfaces being of arcuate form and spaced from each other forwardly of a line of juncture thereof which substantially parallels the central axis oi the bucket assembly.

12. A wheel bucket assembly consisting of a number of sets of pre-formed sheet metal parts, the parts comprising one set being of a shape identical with each other but different from the parts of another set and all of the parts being assembled with a part ofone set alternating with a part of another set to provide a series of .successive buckets circumferentially spaced apart to provide passages for receiving and direc-ting therethrough an elastic driving fluid, the parts of one of said sets each providing a front thrust surface for a given passage and a back guiding surface for the next preceding passage, both surfaces being of arcuate form and spaced from each other forwardly of the line of juncture thereof. said line forming the lip or outer edge of a bucket, and the parts of another of said sets being each of generally inverted V-shape to provide downwardly divergent .branches terminating in forwardly extending portions, the latter constituting opposite outer side enclosures for thearcuate thrust surface portion of a given one of the first-mentioned parts and the ridge of said divergent branches constituting a iiuid streamI separator which extends between the back guiding surface of said given first-mentioned part and. the front thrust surface of the next preceding one of said first-mentioned parts.

13. A wheel bucket assembly as defined in claim 9 wherein the downwardly divergent branches of each of said second-mentioned parts respectively form the inner walls of a pair of laterally spaced fluid channels which respectively receive and guide therethrough the separated Portions ofthe fluid stream, each of said channels having a discharge opening which is separated from said front thrust surface by one of the forwardly extending portions forming the side enclosures for said surface.

14. In a wheel bucket construction for an elastic huid turbine, a plurality of elements nested together to form said bucket, one of said elements providing a concave thrust surface and a convex guiding surface for an elastic uid, said surfaces being spaced from each other ,forwardly of a. line of juncture substantially paralleling the axis of the turbine wheel and constituting the outer edge of a bucket, and another of said elements providing inside and outside side-wall surfaces, all said surfaces cooper ating to create a series of circumferentially spaced U-shaped passages each having laterally spaced channel-ways through which elastic fluid flows to actuate the turbine.

15. In a wheel bucket construction for an elastic fluid turbine, a plurality of elements nested together to form said bucket, one of said elements providing a concave thrust surface and a convex guiding surface for an elastic fluid, said surfaces being spaced from each other forwardly of a line of juncture substantially paralleling the axis of the turbine wheel and constituting the outer edge of a bucket, and another of said elements providing inside and outside side-wall surfaces, all said surfaces cooperating to create a series of circumferentially spaced U-shaped passages each having laterally spaced channel-ways through which elastic fluid ows to actuate the turbine, theV wheel bucket construction being further characterized in that the said concave surface of one of the elements of which it forms a part cooperates with the convex surface of an adjoining similar element to form said U -shaped passage.

16. In a power turbine of the type including a pressure chest in which an elastic driving fluid is maintained under pressure and having a nozzle associated with the pressure chest for directing said elastic fluid impulsively toward a turbine wheel rotatively mounted Within the turbine, a bucket construction for said wheel in which the latter is peripherally fitted with buckets for providing the same with a series of U-shaped channel-ways, each channel-way having a pair of laterally spaced uid passages, the intake of which is common and the exits separate, said Ibucket construction including several sets of sheet metal stampings assembled in nested relation upon the peripheral rim of the turbine wheel to provide the fluid passages aforesaid, the stampings of each separate set thereof lbeing of identical shape with those of one set arranged in alternating relation with respect to those of another set, to provide the channel-ways aforesaid for peripheral admission of the fluid and the laterally spaced uid discharge passages for each channel-way.

17. A turbine wheel bucket assembly consisting of pre-formed sheet metal stampings assembled together in circumferentially spaced relation to form a plurality of circumferentially spaced divided-flow passages each having a single peripheral entrance and a pair of laterally spaced separate side exits for an elastic driving fluid, certain of said assembled stampings providing a front thrust surface for a given passage and a back guiding surface for the next preceding passage, said surfaces being spaced from each other forwardly of a line of juncture substantially parallellng the central axis of the turbine wheel to -provide a recess therebetween, certain of said stampings each having portions of generally inverted V-shape to provide a pair of downwardly divergent brances, each pair of said divergent branches laterally embracing arecess aforesaid t form an internal chamber for reception of a coolant huid. the downwardly divergent branches of said V-shaped stamping serving conjolntly as the outer walls of said internal chamber lfor the coolant fluid and as the inner walls of each divided-flow passage for the driving fluid.

18. In a. turbine wheel bucket assembly as defined in claim 17 wherein the opposite side exits for each divided-flow passage are disposed at points located radially inwardly of the peripheral surface of the wheel.

19. In a turbine wheel bucket assembly as defined in claim 17 wherein the opposite side exits for each divided-flow passage are disposed at points located radially inwardly of the peripheral surface of the wheel and wherein discharge exits for the internal chamber immediately associated with a given divided-flow passage are disposed in close proximity to the discharge exits for the driving fluid.

20. A wheel bucket assembly comprising a number of sets of pre-formed sheet metal parts assembled together in substantially circumferentially spaced nested relation, the parts comprising one set being of a shape identical with each other, but different from the parts of another set and all of the parts being assembled with a part i of one set alternating with a complemental part of another set to provide a series of successive passages for receiving and directing therethrough an elastic driving fluid, the immediately associated parts of the several sets thereof being complementally shaped to provide for a given passage an arcuately shaped front thrust surface and for the next preceding passage an arcuately shaped back guide surface, said surfaces being joined along a line extending transversely of the plane of rotation of the bucket assembly to constitute the outer edge of a bucket element separating the two passages aforementioned.

21. In a wheel bucket assembly of the character defined in claim 20 wherein the said arcuately shaped back guide surface for a given passage is of a curvature so related to the curvature of the arcuately shaped front thrust surface for said passage as to provide said passage with a gradually increasing cross-sectional area from the entrance toward the exit ends thereof.

22. In a wheel bucket assembly of the character defined in claim 20 wherein the said nested parts forming a given4 passage are provided with interiltting complemental parts constituting side enclosures for said passage.

23. In a wheel bucket assembly of the character defined in claim 20 wherein the nested parts forming a given passage for the elastic driving fluid are provided with interitting complementally shaped elements which divide said passage into a pair oi' laterally spaced channel-ways which have a common perpiheral inlet and separate exits respectively located at opposite sides of the bucket assembly and at points spaced radially inwardly from said common peripheral entrance.

24. In a wheel bucket assembly of the character defined in claim 20 wherein the immediately associated parts which form therebetween a given passage for an elastic driving fluid are provided with interfitting, complementally shaped elements which divide said passages into a pair of laterally spaced channel-ways each of arcuate form, said channel-ways being relatively so arranged that their median planes diverge downwardly from the peripheral surface of the assembly.

25. In a wheel bucket assembly of the character dened in claim 20 wherein means is provided for dividing the fluid stream, as it passes through each passage, in'to a plurality of substantially parallel band-like streams.

26. In a turbine wheel as dened in claim 2, means within the wheel cavity operative to draw into and expel therefrom an elastic coolant uid while the wheel in rotation.

Lewis A. marmo.

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