US2378958A - Propeller construction - Google Patents

Description

June 26, 1945. TROLLER I 2,378,958

PROPELLER CONSTRUCTION Filed Dec. 11, 1942 2 Sheets-Sheet 1 IN V EN TOR.

BY Mir June 26, 1945. T. H. TR OLLER 2,378,958

PROPELLER CONSTRUCTION Filed Dec. 11, 1942 2 Sheets-Sheet 2 INVENTOR. 7mm ,4, 41m

. 9 1 k104i m Patented June 26, 1945 PROPELLER CONSTRUCTION i Theodor H. Troller, New Philadelphia, Ohio, as: signor to La-Del Conveyor & Manufacturing Company, a corporation of Ohio Application December 11, 1942, Serial No. 468,651

11 Claims. (01. 230 114) Myinvention relates in general to variable pitch propellers and more particularly to the improvementof a rim and a fitted blade construction adapted to give improved operating characteristics.

An object of my invention is the provision of a variable pitch propeller havinga rim with a cylindrical outer surface to which is rotatively mounted a fitted blade, wherein the outer cylindrical surface is provided with a recess to receive the base portion of the blade, the construction and shape of the recess and of the lower base portion of the blade being such to provide a close clearancetherebetween to give improved operating characteristics.

Another object of my invention is the provision of a rim having a substantially circular outer surface upon which one or more fitted blades drical outer surface instead of a non-circularconstruction which would tend to create turbulences I in the air stream.

Another object of my invention is the provision of a rim to which variable pitch propeller blades may be rotatively mounted wherein the rim has a smooth cylindrical outer surface to minimize the turbulences and the friction losses in the air stream. i

Another object of my invention is the provision of providing a'close clearance between the base portion of the blades of a variable pitch propeller and the rim to which the blades are rotatively mounted in order to minimize noises and other air disturbances. a

Other objects and: a fuller understanding of my invention may be'had -by referring .to' the following description and claims taken in conjunction with the accompanying drawings, in which:

. Figure 1 illustrates a front elevational view of Figure 2 is an,enlarged view taken along the line 2 2 of Figure 1 and showing principally the recess in the outer cylindrical surface of the rim 1 and a cross-section of the base portion of a blade which is arranged to fitin the. recess; I

Figure .3 is a cross-sectionalview taken along angle with respect to a plane the line 33 of Figure 2 and shows the close clearance which exists between =thebottom or base portion of the blade and the bottom of the recess; i

Figures l, 5 and 6 are viewssimilar to Figure 3, the figures being taken respectively along the lines 4- 4, 55,and 66 of Figure 2;

Figures 7 and 8 are cross-sectional views taken respectively along the lines and 8-8 of Figure 2, the figures being shown in a matched relationship in order to showthe depth of the recess on the side edge which has the greater pitch passing through the zero pitch angleyand Figures 9 and 10 are'views taken, respectively, along the lines 99 and [0-H] of Figure 2, and

showing respectively the depth of the recessalong a the side edge which has the smaller pitch angle with respect to a planepassing through the zero pitch angle. r i i 1 i With reference to Figure 1, mylinvention may be embodied in a variable pitch propeller comprising a plurality of blades I5 rotatively mounted at spaced intervals to a rim I! which may be driven by any suitable type of motive'power. The blades may. be rotatively mounted to the rim by means of shanks l 8 which rotatively lit in sockets in the rim l1. The inner end of the shank l8 maybe'actuated by a crank arm l9 to vary' the pitch angle of the blades. As illustrated, the crank arm l9:may be jointly operated by an axially movable control member or spider 20 actuated by a control lever 21 which extends transversely of an air flow passage IS in which the propeller revolves. The lower end of the control lever 2| mayrbe anchored to the bottom of the air flow passage l6 by means of a hinged connection 23 and theupper end of the control lever 2| is arranged toextend externally of the air flow passage [6 so that as the control lever 2| isactuated back and forth the pitch of the propeller blades is accordingly varied. The forward end of the rim I1 is provided with a nose-like cover 24 and an axially movable control rod extends through the forward portion of the nose-like cover and inter-connects the control member 20 to the intermediate portion of the control lever 2! at the hinged connection 22. The control mechanism for rotating the blades to vary the pitch thereof may be the same as that shown and described in an application executed concurrently herewith in the name of Thomas .0. Adams Jr. and Theodor H. Troller for an application entitled improvementin Adjusta'ble pitch propeller mechanismand assignedto the assignee of this application, While. I have illustrated a .fan .and the :bottom .of :the recesses. .icesses may the :cast or otherwise suitably proadjusted to vary the pitch thereof within predetermined limits.

The leading base portion 25 is arranged to-fit into a leading recess 21 provided in the outer cylindrical surface of the rim -I"Iand the-trailing base portion 26 of the bladeis arranged to fit in a trailing recess 28 mounted in the outer cylindrical surface of the rim ;-H. The leading and trailing recesses 21 and 28 are Wide enough to allow the blade to be rotated to its predeterminedilimit of variable pitchangle. The leading recess 2'! is provided with atWO. side'edges 2?!) and @Uandanend-edge -3l. The-bottom of the i leading recess 21 is indicated by the reference character '32.

leadingrecess -21 isdefined by the rotation of a The bottom surface .32 of the generatrix aboutttheaxisof the hub. The-line 32in FiguresHTZ-and Q vwhicltiqdefines the bottom 'of .the leading .recess .at the plane vof the particular -,cr.oss-sec.tion .is the generatrix. Similarly, the trailing recess .28 is provided with side edges 33 and 34 and Ian endedge :35. The bottom of thetrailing recess ..-28.is indicated :by the reference character 36. The bcttomsurface 13.6 of the,trailing recess 28 isldefined by .the rotation of ageneratrix about-the axis of .the .hub. The line 36. in-FiguresB; and which defines the bottorn of the .trailingrecessat the plane of theparticular 1c-rcssesection is :the .generatrix. As 'illustrated in Figures 3 to 10, inclusive, the side edgesltlgand :33 are deeper than-the side edges SO-and :34. .In other words-the sideeedge'of'zthe leading and .trailing recesses 21 and 28 which has the greater :pitch angle withrrespect 'to a plane :passing through :,the. .EZGIO pitch .angle :is deeper than-the :side v edges .whichzhaveithe smaller -zpitchangle. vThedeeper-side edges 1219 r and 3 and the endedgesfll and3;5;are gradually sloped in order :to prevent .any abrupt change in the ,air flowuasthe air passes-along the outer cylindrical surface of .the I1 and into they leading andtrailing'recesses =2Land 2-8.

, The :bottom edge dfl of ztheleading base sporctionlziandxthe bottom edge 4|;of the trailing base portion :26 ."of the blades are shaped to substantially match the gradually sloped deeper side edges -29zand :33 of the leading and .trailing recesses 1521 and :23, .see Figures '3 to 6, inclusive.

As illustrated iniEigures 2 and :6,.the bottom edge 4110fthe trailingbase portion .26 is provided with can angularly disposed flange 242- which is arranged :to :match the .deeper side edge .33 .of the trailing recess 2-8. The bottomusurfaces 32 and 13B of the leading and trailing .recessesJZl and 228 are varcuaterin a. longitudinal direction, and the botithezblade I 5, are correspondinglyarcuate to pro- .videa close clearanceabetweenthebottom of the The revided in'the:rim-"|-:l. "In the event the recesses .aretcast in the rimzli'Lithe patterns used'for making the casting .may have 1 the recesses provided therein. In 1 cutting the recesses in 1 the patterns, the, bottom -:surfaces .thereof may 7 be; determined gby .placingia given bladehaving a :given under ,the smaller pitch angle being shown by the dashdot line in Figure 2. In this invention, it is to be understood that the leading and trailing recesses 21 and 28 may have anyangular position with ;respect to the zero pitch line depending upon'the range through which the blade is to be adjustably moved to obtain the most desirable operating characteristics. In other words, the leading and trailing recesses 21 and 28 may be shifted in a clockwise direction to have a smaller angle withrespect to the zero;pitch line, or :they maybe shifted in a countersclockwiseudirection to have a .larger angle withrespeot toithevze o pitch line.

In my invention, I have no hole or-aperture extending through the :rim in theregionnof the base portion of the fan. blade. By eliminating the hole or aperture around the base portion .ofithe blade, I am able to produce avariablezpitchdan construction which has aminimumzofan'oises-and air disturbances. Also, in my invention .1 am able to employ a rim having an outer cylindrical smooth surface as distinguished from =a runncircular rim: or a rimzutilizin-gregulansurface. such for example, having flatsurfacesradjacent the-lower edges of the-blades.

The leading and the trailingrecesses:2:l and 28 .may be cast in the outer cylindrical surface of the .rim and inasmuchzas -.there-.mays.b.e zirregularitiesin l the casting of the recesses, I :provide the shallow edges ;3-fl.and.-34. :In-ptherwords, in a theoretical sense, assuming thatzthe: bottom of the recesses and the DOttOmBdgQOIf thethlades wereperfectly smooth .and free. of mechanicalirregularities, then there "would Lbe :norneed :for

theshallowedges 30 .andM. Accordingly, the shallow edges :30 and 34 .are .made 'just mieep enough to take care of mechanicalzirregularities in the casting-or.otherwise.manufacturingzof the recesses.

lnzoperation of myinvention, the-airfflows substantially uninterruptedly over the .outer cylindrical surface of the rimll and produces aniimproved fan operation. The noise is reduced ito a low minimum and in addition there is no mechanical concentration of stresses as is 28X- perienced in certain prior: art devices which employ a fairing or :other shell about the rim' through which the fan blades extend such, -*'for the rim .or mounting to which it is rotatively connected. While I'have shown the recesses 21 and 28 in a rim having an outer cyl'indrical surface, it is to beunderstoodthatmy reoesses may :be utilized ina rim or mounting having a spherical, convex, or other curved surface and in-the claims the term -cylindrical-outer surface shall be interpreted to include spherical,

convex and all types of curved surfaces as well as-cylindrical surfaces.

Although I have described mybinvention with a certain degree of particularity, itis understood that the present disclosurehas been made ;only by way of example and that numerous changes inthe details of construction and the combination and arrangement of parts may be resorted to without departing fromthe spirit andgthe scope of the invention as hereinafter claimed.

I claim as my invention:

1. In a variable pitch propeller mechanism, the improvement of a rim and a fitted blade construction, said rim having substantially a cylindrical outer surface, said blade being rotatively mounted about anoutwardly extending axis in the-rim for adjusting the blade pitch within predetermined limits and having a leading base portion and a trailing base portion extending in substantially opposite directions from said axis, said outer surface of the rim having a leading recess extending forwardly from said axis to receive the leading base portion of the blade and having a trailing recess extending rearwardly from said axis to receive the trailing base portion of the blade, the bottom surfaces of said recesses being portions of surfaces of revolution, the axes thereof being the first mentioned axis, each surface of revolution having a generatrix defining a line with a curvature close to the curvature of the rim, the under surface of said leading base portion and of said trailing base portion being substantially congruent and coaxial with the bottom surfaces of the leading and trailing recesses respectively.

2. In a variable pitch propeller mechanism, the improvement of a rim and a fitted blade construction, said rim having substantially a cylindrical outer surfacasaid blade being mounted on therim and extending therefrom and being rotatable about an axis for adjusting the blade pitch Within predeterminedlimits and having a leading base portion and a trailing base portion extending in substantially opposite directions from said axis, said outer surface of the rim having a leading recess extending forwardly from said axis to receive the leading base portion of the blade and having a trailing recess extending rearwardly from said axis to receive the trailing base portion of the blade, the bottom surfaces of said recesses being portions of surfaces of revolution, the axes thereof being the first mentioned axis, each surface of revolution having a generatrix defining a line with a curvature close to the curvature of the rim, the under surface of said leading base portion and of said trailing base portion being substantially congruent and coaxial with the bottom surfaces of the leading and trailing recesses respectively.

lution having a generatrix defining a line with a curvature close to the curvature of the rim, the under surface of said leading base portion and of said trailing base portion being substantially congruent and coaxial with the bottom surfaces of the leading and trailing recesses respectively, each said recess having two side edges between which said blade is adjustably moved to vary the pitch thereof, the side. edge which has the greater pitch angle with respect to a plane passing through the zero pitch angle beingdeeper than the other side edge.

4. In a variable pitch propeller mechanism, the improvement of a rim and a fitted blade construction, said rimv having substantially a cylindrical outer surface, said blade being mounted on the rim and extending therefrom and being rotatable about an axis for adjusting the blade pitch within predetermined limits and having a leading base portion and a trailing base portion extending in substantially opposite directions from said axis, said outer surface of the rim having a leading recess extending forwardly from said axis to receive the leading base portion of the blade and having a trailing recess extending rearwardly from said axis to receive the trailing base portion of the blade, the bottom surfaces of said recesses being portions of surfaces of revolution, the axes thereof being the first mentioned axis, each surface of revolution having a generatrix defining a line with a curvature close to'the curvature of the rim, the under surface of said leading base portion and of said trailing base portion being substantially congruent and coaxial with the bottom surfaces of the leading and trailing recesses respectively, each said recess having two side 3. In a variable pitch propeller mechanism,

the improvement of a rim and a fitted blade construction, said rim having substantially a cylindrical outer surface, said blade being mounted on the rim and extending therefrom and being rotatable about an axis for adjusting the blade pitch within predetermined limits and having. a leading base portion and a trailing base portion extending in substantially opposite directions from said axis, said outer surface of the rim having a leading recess extending forwardly from said axis to receive; the leading base portion of the blade and having a trailing recess extending rearwardly from said axis to receive the trailing base portion of the blade, the bottom surfacesof said recesses being portions of surfaces ofrevolution, the axes thereof being the first mentioned axis, each surface of revosurfaces of the leading and passing through the zero edges between which said blade is adiustably moved to vary the pitch thereof, the side edge which has the greater pitch angle with respect to a plane passing through the zero pitch angle being deeper than the other side edge, said deeper side edges of the recesses being gradually sloped to minimize air disturbances. l

5. In a Variable pitch propeller mechanism, the improvement of a rim and a fitted blade construction, said rim having substantially a cylindricalouter surface, said blade being mounted on the rim and extending therefrom and being rotatable about an axis for adjusting the blade pitch within predetermined limits and having a leading base portion and a trailing base portion extending in substantially opposite directionsfrom said axis, said outer surface of the rim having a leading recess extending forwardly from said axis to receive the leading base portion of the blade and having a trailing recess extending rearwardly from said axis to receive the trailing base portion of the blade, the bottom surfaces of saidrecesses being portions of surfaces of revolution, the axes thereof being the first mentioned axis, each surface of revolution having a generatrix defining a line with a curvature close to the curvature of the rim, the under surface of the said leading base portion and of said trailing base portion being substane tially congruent and. coaxial with the bottom trailing recesses respectively, each said recess having two side edges between which said blade is adjustably moved to vary the pitch thereof, the side edge which has the greater pitch angle with respect to a plane pitch angle being deeper than the other side edge, each said recess also havingan end edge, said end edges and said deeper side edges of the recesses being gradually sloped to minimizeair disturbances.

6. In a variable pitch propeller mechanism, the improvement .of a .rim and 1a fitted blade construction, said rim having substantially .a cylindrical outer surface, said blade being mounted on the rimrand extending therefrom and being. rotatable about an axis for adjusting the blade pitch Within predeterminedlimitsand having a :base portion extending from .said axis, said rim having .a recessin the outersurface thereof, the bottom of the .base portion of the blade fitting in the saidsrecess, thebottom surface of said recess being a portion of a spherical surface of revolution, .the axis thereof coinciding with the first mentioned axis, said :spherical surface of revolutionlhaving a generatrix clefining a line, said line intersecting isaidraxis at apoint spaced at a'distancefrom the center of rotation of :the rim substantially equal to the radius of the rim, the bottom surface of said base portion being substantially congruent with the bottom surface of the recess, said recess having two side edges between which said blade is adjustably moved to vary the pitchithereof.

7. In a variable pitch propeller mechanism,;the improvement of a rim and ,a fitted blade :construction, said rim having substantiallya cylindrical .outer surface, saidblade'being mounted on the rim and extending therefrom and being rotatable about an axis for 'adiusting the blade pitch within predetermined rmas and having aleading base portion and a trailing base portion extending in substantially opposite directions from said axis, said outer surface of the rim having a leading recess extending forwardly from said axis to receive the leading base portionof the blade and having a trailing recess extending rearwardly fromsaid axis to receive the trailing base portion of the blade, the :bottom surfaces of said recesses being portions of surfaces of revolution, the axes thereof being thefirst mentioned axis, each surface of revolution having a, generatrix defining a line with a curvature close'to the curvature of the rim, the'under surface of said leading base portion and of said trailing-base portion being substantially congruent and coaxial with'the bottom surfaces of r the leading andtrailing recesses respectively, each said recess having two side edges between which said blade-is .adjustably'moved to vary the pitch thereof, the sideed'ge which has thegreater pitch angle with-respect to .a .plane,passing through the 'zero pitchangle being deeper than thevother side edge, said trailing base portion having an angularly disposed flange which substantially matches the side edge in the trailing recess which, has the greater pitch angle.

8. In a variable pitch propeller 'mechanism, the improvement of a rim and a fitted blade construction, said rim having substantially ..a cylindrical outer surface, and a socket therein, said blade having a shankv portion fitting 'lIllSELld socket and a base portion extending-outwardly from the rim, said blade being rotatable about an axis for adjusting the blade pitch 'w-ithin predetermined -limits,,sai-d rim having a-recess in the outer surface thereof and extending from the edges .of the socket, the bottom-of the base portion fitting in the said recess,zthe. bottom surface of said recess beinga portion .of a spherical surface of revolutiomtheaxis thereof coinciding with the first mentioned axis, said spherical surface of revolution havinga generatrix defining .a line, said line xintersecting-saidraxis at apoint spaced ata distance fromthe center of rotation of the rim substantially equal tocthe radius of the rim,the bottom surface of said base .p.ortion being substantially congruent with thebottom surface of the recess, said recess having twoside edges betweenwh-ich :said blade is adjustably moved to vary the pitch thereof.

9, In a variable pitch propeller :mechanism, the improvement of a rim and a fitted blade construction, said rim having substantially a cylindrical outer surface, said blade being mounted on therim and extending therefrom and being rotatable about an axis for adjusting the blade pitch within predetermined limits and having a base portion extending from said said rimr having a recess in the outer surface thereof,,the bottom of the base portion of the blade fitting, in the said recess, the bottom surface of said recess being a port-ion of a surface of revolution, the axes thereof being the first mentioned axis, the surface of revolution having ageneratrix defining .a line with a curvature close to the curvature of the rim, the under surface of said base portion being substantially congruent and o coaxial with the bottom surface of the saidrecess. 10. In a variable pitch propeller mechanism,

the improvement of a rim and a fitted blade construction, said rim having substantially a cylindrical outer surface, said blade being mounted on therim and extending therefrom and being rotatable about an axis for adjusting the blade pitch within predetermined limits and having a base portion extending from said ,axis, said rim having an auxiliary surface, said' auxiliary surface being aportion ofa surface of revolution, the axes thereof being the first mentioned axis, the surface of revolution having-ta generatrix defining a line with the curvature close to the curvature of the rim, the undersurface of saidbase portion of the blade being dis posed close to and substantially congruent and coaxial with said auxiliary surface.

11. In a variable pitchpropeller mechanism, the improvement of a cylindrical rim. and; a fit-. ted blade construction, said blade being mounted on the rim and extending-therefrom and being rotatable about an axis for adjustingthe blade pitch withinpredeter-m-ined limits and having a leading base portion'and a trailing base portion extending in substantially opposite directions from said axis, said rim having a recess on its outer surface to receive the base portions of the blade, said recess comprising a leading recess extending forwardly from saidaxisto receive the leading base portion of the blade and having a trailing recess extending rearwardly from said axis to receive the trailing base portion of the blade, the bottom surfaces of saidrecesses being portions .of spherical surfaces of revolution, the axes thereof coincidingwith the first mentioned axis, each spherical surface of revolution having a generatrixdefining a line,;eaoh said line respectively intersecting said first mentioned axis at a point spaced at a distance from the center of rotation ofthe rim substantially equalto the radius of the rim, the .bottom,- surfaceof said leading base portion and of ;-said trailing base portion being substantially congruent with the bottom surfaces of the leading and trailing recess respectively, each saidrecess having two side edges betweenwhich said bladeis adjustably moved to vary the pitch thereof,

, ,THEODOR ,I-I. TROLLERQ,

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