US2482217A - Blade mounting for propellers - Google Patents

Description

Sept. 20, 1949. c. R. SACCHINI ,4

BLADE MOUNTING FOR PROPELLERS Filed Dec. 21, 1945 2 Sheets-Sheet l 44 //v van/r02 (040/2150)??? finru/iw ATTOR Sept. 20, 1949.

c. R. SACCHINI BLADE MOUNTING FOR PROPELLERS 2 Sheets-Sheet 2 Filed Dec. 21, 1945 ATro RA/E V Patented Sept. 20, 1 949 UNITED STATES PATENT OFFICE or to The Marquette Metal Products Company,

Cleveland, Ohio, a corporation of Ohio Application December 21, 1945, Serial No. 636,363

9 Claims.

This invention relates to controllable pitch propellers and particularly to the mounting of the propeller blade thereof in a hub, and is an improvement on the propeller blade mounting disclosed in the copending application of Gordon W. Hardy, Serial No. 528,412, filed March 28, 1944.

One of the principal objects of the present in- I vention is to provide, in a controllable pitch pro- 7 retaining sleeve and blade adjusting gear for mounting the blade in the hub and for connecting it to the pitch control mechanism, and which is simple in construction, easily installed, maintains the blade shank in proper position axially while permitting proper rotation thereof about its axis for adjustment, permits initial pos-itioning and securing of the blade and blade gear accurately in relatively rotated positions of adjustment with respect to each other, after installation, and maintains the blade and gear accurately in all controlled positions of the blade.

A more specific object is to provide a pair of complementary hemi-cylindrical sleeve sections which cooperate to form a cylindrical retaining sleeve for a propeller blade shank and one of which has a blade driving gear integral therewith and positioned to be coaxial with the assembled sections and to cooperate accurately with the main driving gear of the propeller hub when the blade is installed.

Other objects and advantages will become apparent from the following description wherein reference is made to the drawings in which: Fig. 1 is a side elevation of a hub and blade assembly embodying the blade mounting of the present invention, part thereof being shown in section for clearness in illustration;

Fig. 2 is a top plan view of one of the blade mountings illustrated in Fig. 1;

Fig. 3 is a front elevation of the blade mounting illustrated in Fig. 2, part thereof being shown in section for clearness in illustration; and

Fig. 4 is a cross sectional view of the blade supporting barrel of the hub with a blade mounted therein, and is taken on the line 4--4 of Fig. 1,

the roller bearings being shown in elevation for clearness in illustration.

more fully set forth in the copending application above identified, considerable difllculty has been encountered in providing an easily installed blade mounting which permits adjustment of the blade for pitch after installation of the blade in the hub and which supports the blade shank in proper relation to the blade gear and the latter in proper relation to the main driving gear. One mounting for this purpose is illustrated in the above identified copending application and, in the form there shown. while the mounting assembly is relatively simple and easily constructed, its installation and removal for purposes of servicing of the parts thereof or of the operating mechanism within the hub is difficult and time consuming. Furthermore, the pitch of the blade associated therewith cannot be adjusted after installation of the blade and retainer subassembly in the hub.

In accordance with the present invention, a simplified and more easily installed mounting for a propeller is provided and is arranged to cooperate with the control mechanism such as fully disclosed in said copending application.

As therein more fully described, the propeller comprises generally an annular hub l which is generally in the form of a central segment of a sphere with inturned radial flanges at its ends and which has a plurality of blade supporting barrels or arms 2 spaced apart from each other about its periphery and preferably integrally secured thereto or formed integral therewith. In the form illustrated herein, two such barrels are provided, although three or four barrels angularly spaced equidistantly about the axis of the hub may be provided.

The hub l is mounted on, and in coaxial relation with, a hub carrier 3 which has a peripheral flange 4 near its rear end and an annular shoulder 5 near the periphery of the flange for receiving the inner edge of one of the end flanges of the hub I so as to center the hub in proper coaxial relation to the carrier 3. The hub is secured rigidly in position on the shoulder 5 by means of a plurality of circumferentially spaced bolts 6.

The carrier 3 has a tapered internal bore 1 in which is fitted the crank shaft 8 of an engine (not shown), a suitable key 9 being provided for interlocking the carrier 3 and shaft 8 against rotation relative to each other. The shaft 8 extends axially entirely through the carrier 3 from the rear end of the carrier and beyond its forward end and is threaded, as indicated at l0, adjacent to the forward end of the carrier 3. A tubular nut l2 having an internally threaded inner end portion 13. is in threaded engagement with the threaded portion. ll] of the shaft 8 for holding the carrier 3 in fixed axial position on the shaft 8.

Mounted in surrounding and coaxial relation to, and rotatable relative to, the nut l z'is a gear hub or sleeve l4 on one end of which is a bevel gear I5 which is the master power gear forop erating thebl'adesv of the propeller to vary; or 0011:. trol their pitch. The sleeve I4 is also provided with an external spur gear 7 l6 positioned for-1 wardly from the bevel gear IS, The gear; 6 in turn, is drivingly connected to a plurality of racks ll which are preferably tor-med on and; integral with pistons l8 of suitable servomotors, the cylinders of which are indicated at l9. As illustrated, the cylinders [9 are sop i iq lfidsthat the pistons l8 and racks H can reciprocate tangentially of the pitch diameter of the gear it as to oscillate the master gear l5 about the axis of the. sha t 8- Thev servomotors. are carried in a suitable housing 26- whieh hasa peripheral flange 21' on which is an annular shoulder 22. The'shoulder; 2 2; en ages the inner edge of the forward flange surface 30, the latter being at the innermost end of the shank. Since each blade is mounted in eorrugations,,indicated generally at 34, which are of; the. hub l and centers the housing 20 in co axial; relation with respect thereto. The servo motor hous n 2a is se ured to th h b l by ean oisa circumferential; series of bolts 23 and, inaddition to being the housing for the servomotor, provides an external, radial thrust bearing and an adjacent axial; thrust. bearing forthe sleeve t4; as indicated at 24. Qperatin fluid is supplied to the servomotors as fully set forth in the above identified copending application. The discharge of fluid from the motors is. into; a sump. 2.5 which. is defined: by the annular flange 4 of the carrier; 3 and a suitable cover plate 26-, and, in turn,v is connected: the hydraulic system, all: as. fully set forth. in the. above identified copending application. Tfhepropeller'blades areimounted in theblade supporting barre-ls or arms. 2; and must. be mounted therein in coaxial relation thereto and fior'correlated rotation or oscillation about their respective: axes, At. the same time. adequate. thrust-.toresist the centrifugal force of'the-bladesmust. be provided in a. manner such that the blades donot bind and; resist. rotation. about: their axes to diflerent. controlled positions. Likewise the blades must be interlocked with each other through thecontrol mechanism so that once they. are: set in tha properly adjusted: position initially. with respectto each other, subsequent rotation of one blade for varying its. pitch is; impossible without a. complementary and equal: rotation of thesother; They must be arranged so: as tapermit. the proper initial: setting ofi each blade with: respect to the control means ,itself'so that thereafter they are operated in the proper balance and relation by the control means. They should be mounted so that they can be installed and: removed easily and quickly and initially ads. jilsted for pitch after!installation in. the hub; Finally, since the blades are made of aluminum or. relatively soft metal}. they: must be provided with; large anchorage corrugations to" resist: cen-. tritugalforce.

Irrorder to accomplish all of these resultsin a simple and rugged structure, the mountingof: the present invention. is provided; In the-musetrative. embodiment, the mounting: is. shown as adaptedfor-use with the usual: blades 21, eachlof' which has an integral shank portion. wprovid'ect with external annular corrugations 29 and a pilot eomplementary to and lit the corrugations 29 ofthe: shank. The hemi-cylindrical sleeve section 32 is provided at one end with anintegral hub extension 35" which is coaxial with the assembledsleeve sections and which carries, near its innermost end, a bevel gear 36 which consti ut s e. blade. gear for. osci latine the; bla a scciatedwiththe. reta ner 31-- e eta n r: 3L isprqvided between; its ends with, an eXternalani l ar shoulder 3.1 and, the, extensio 3.5;ispros vided. with an. axial bore 38., the innermost end of which is. in the. form of; an. internal. annular bearing surface 39. The carrier 3. provided with. radia ly ext ndi al ndr salv bosses 46% whi h. are mounted: suit ble bush nesor xterna an ular bearin s 42!. which e age nd are ommementaryto he e rin suria fifi c he; x. tension 35 and proyidethepilot and radial thrust, bearing iorthe. t i-uerra m unt ng; 3:! wh n. the retainer 3 s ns alled; in; eibar el; 2. w th t e gear 36 in proper mesh with the main; driving gear 3..

A ts. pposit en he. retainer 31. asw liu i al ampina pe tion. 4.2: wh ch adapted e b ace t e s ank 2.8. of th 1ade=Qu W d anally-b ond. the barre Th h rm n has ims. 3. which. xten from. its: outer end; 1on.-- aitlldin yo e hQrtiOn 4.23 for; a. sufiicient: dis fiance o nrcvidel x b ity of; they po ion The! po t on 42 has: wn-external: annuial. growe- 4 whi h l es.-

he lotted portion. and aCQOmrmqda e a clamp ng nd 45: which, by means of? a gut .ble: bolt; 4&1 and; its cooperating nut, operated;- to draw: the. portion 424 intofirm clamp. 21% engagement. withi-itheshank 28 when: the b ade the desired relatively rotated initial; idl'ilstedt nosition. with respect to-the retainer" 31!; and secures; the; blade. shank;v 28 and". the sec tions. 32 and: 3&forrotation together. The hemi-- cylinsihigcalz sections 32 and 335 are alsoheld inernlaracingrelation to. the hub 28 of the blade hyemeans; ot-an endlessannulan band 41- Which is: fitted onto the assembled sectinnszaiter the bladeshank: has been embraced; therein, preferably with a slipzfitto facilitate disassembly. Th band: 41 mayrbea bronzebearing or; as ii lustrated may be. a. hard; metals race-suitable for thrust roller bearings. l8; the innerwall' of thebarrel 2 forming the outer race: of the bearings 4%; The bearings:

48 are preferablyofi such. length as to-ht freely:

between. theinward: face of the flange 37 oft-he retainer 3| and an outwardly facing shoulder 49ioffthe blade supportinglbarreli v At; the; outermost face of the flange- 31, a suitable combined axiali and: radia-l thrust bearing isprovidedt In the form; illustrated; a-suitable bearing race 56 is slip fitted onto the assembled sleeve sections: 32 andf firmly against the outward: faced-the flange 31*: A complementary" race 5| is screw threaded into-the open end-of the barrel 2* so as-to-retaim theb'a1i bearingssz,

accurately with a protractor.

and through them, the retainer 3!, in proper axial and radial position in the barrel 2. The outermost end of the barrel 2 has a plurality of notches 63 and the outer end ofthe race 5| has a plurality of notches 54, so that, when the race is in proper position in the barrel, a suitable key 55 may be inserted in aligned notches of the barrel and outer race for anchoring the race 52 against rotation. The key 55 may be secured in place by suitable screws, not shown, extending through the key 54 and in threaded engagement with the end of the barrel 2.

As more fully described in the above ldentifled copending application, a different number of notches 53 is provided in the outer end of the barrel and in the race 52 So as to provide a Vernier effect between the notches of one and the other to permit closer setting of the race 52, while providing for insertion of the key 55 in the adjusted position. As disclosed in the above copending application, the practice has been to make the retaining sleeve in two sections, the two sections being threaded at their inner end so as to receive, in threaded engagement, the outer end of a shank of a blade gear comparable to the gear 36. This gear shank is hollow and receives axially a retaining bolt which isin threaded engagement with an axial bore in the inner end of the shank of the installed propeller blade. A sleeve that is split longitudinally after threading is difficult to assemble into or on to a complementarily threaded part. Moreover, because of the larger number of parts required and precise relationship between them, the construction according to said copending application is much more expensive than the present one.

With the present structure the blade can be readily installed in the retainer or mounting 3| and the assembled blade and mounting installed readily in the barrel 2 of the hub.

In order to install a blade, the servo-motors are operated to set them and the master gear [5 at low pitch position of the blades. The retaining sleeve sections 32 and 33 then are placed in embracing relation to the blade shank and the bearing or race 41 and the race 50 are then installed by slip fitting them into place on the sleeve sections. The clamping band 45 is installed and holds the blade approximately atthe pitch .de-

sired. This subassembly is then inserted into its associated barrel with the roller bearings 48 in place thereon and while held in a rotated posi tion to mesh the segmental blade gear 36 at its circumferential midpoint with the master gear l5. The axial thrust bearing 52 and the race 5| are then installed, adjusted for balance of the blades about the hub axis and secured in adjusted position by the key 55.

The clamping band 45 is then loosened and, with the servo-motor remaining at low pitch and the segmental gear centered and meshed with the master gear IS, the blade is rotated in the sleeve sections 32 and 33 about its axis to low pitch position, the final position being determined Thereupon the clamping band 45 is again tightened. Thus the blade can be adjusted after assembly in the barrel 2. Since the pitch of the blades is seldom varied more than a few degrees, the blade gear 36 may be segmental, as illustrated. If desired, the blade gear, with only a slight addition in weight, can bea complete gear, in which case any of its teeth can be engaged initially with the master gear when the blade and retainer subv assembly is inserted in the barrel, andthe blade then rotated in the sleeve sections to the adjustdrivingly connected ed position. The use of a complete gear 36 is advantageous for purposes of assembly.

Once this installation of the blades is made, all of them maintain a fixed degree of pitch relative to each other as the gears l5 and 36 are extremely accurate and free from backlash.

The assembly and disassembly of the other parts of the hub are fully disclosed in said copending application. If the complementary tapered surfaces of the hub carrier and shaft 8 are lubricated before mounting of the hub carrier on the shaft, then by rotating the nut l2, as by a wrench engaging a cross hole in the nut, the entire propeller hub can be moved endwise in the direction of taper of the shaft 8 and thus loosened for removal as a unit. This is due to engagement of the nut l2 with the inner radial wall of the gear hub I 4 and engagement of the hub M with the thrust bearing surface on the inner wall 2| of the servo-motor housing 20. Again, the servo-motor housing and the servo-motors carried thereby can be removed as a unit for service and repair by removing the bolts 23, and the gears l5 and i6 can be removed readily after removal of the housing 20.

Iclaim:

1. In a variable pitch propeller, a hub, a blade supporting barrel extending radially of the hub, a propeller blade, a blade shank thereon and having external annular corrugations, a pair of complementary hemi-cylindrical shank retaining sleeve sections embracing the shank and having internal corrugations fitting the corrugations of the shank, means for securing the hemicylindrical sleeve sections in embracing relation to and in coaxial relation with the blade shank, means supporting the assembled retaining sleeve sections in fixed axial position in the barrel and for rotation about their common axis, means securing the blade shank and retaining sleeve sections for rotation together about said common axis, one of said hemi-cylindrical sleeve sections having at its inner end an integral extension ifset from the associated sleeve section, coaxial with the shank and projecting into the hub, a blade gear on and rigid with and coaxial with the extension, and driving means in the hub to said gear for varying the pitch of said blade.

2. In a variable pitch propeller, a hub, a Plurality of blade supporting barrels extending radially of the hub, the axes of said barrels lying in the same plane and intersecting and spaced uniformly circumferentially of the hub, at a common point in the hub, blades respective to the barrels, a blade shank on each blade and having external annular corrugations, a plurality of pairs of complementary hemi-cylindrical shank retaining sleeve sections, each pair embracing a shank, means for securing each pair of the hemi-cylindrical sleeve sections in embracing relation about and in coaxial relation with its associated shank, means supporting each pair of the assembled retaining sleeve sections in fixed axial position in its associated barrel and for rotation about the common axis of its sections, means securing each blade and its associated retaining sleeve sections for rotation together about their common axis, one hemi-cylindrical sleeve section of each pair having an integral extension at its inner end offset therefrom into coaxial relation to the shank and projecting into the hub, blade gears on and rigid drive shaft coaxial with the hub and having its with, an annular radial flange on the assembled sections between the collars, spaced retainers for the bearing means in the barrel, one adjustable axially thereof to fix the position of the sleeves and blade shank for rotation in the barrel, one of said hemi-cylindrical sleeve sections having an integral ofiset extension at its inner end coaxial with the shank and projecting into the hub, and blade driving means rigid with the extension adapted to cooperate with complementary driving means in the hub for varying the pitch of said blade.

. 9. In a variable pitch propeller, a hub structure having a tubular blade-supporting barrel, a. circular blade shank having an annular neck and adjacent annular rib, a mounting shell formed complementary to the neck and rib and comprising complementary relatively large diameter hemi-cylindrical parts, metal bearing collars closely embracing said parts to hold them snugly on the shank, cooperating bearing means in the barrel engaging the collars, one of the hemicylindrical shell parts having a reduced diameter inwardly offset, non-split tubular portion integral therewith and connected thereto for half REFERENCES CITED The following references are of record in the flc of this patent:

UNITED STATES PATENTS Name Date Rupp Aug. 7, 1934 FOREIGN PATENTS Country Date Great Britain J Jan. 1, 1907 Great Britain Mar. 5. 1936 Number Number

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