US2324569A - Propeller - Google Patents

Description

V y w.'w. mm j 2,324,569

PROPELLER Filed-July 3. i940 2 Sheets-Sheet 1 r I WA LTERW. EVERTS July 20,1943. .w. w. EQE TQ 2,324,569

PROPELLER Filed July 3, 1940 2 Sheets-Shet 2 W s /W counter weights may be employed to effect equi-v I Patented July 20,

' -z ,sz4 ,5sa u 4 ,raornrlnna Walter WpEverts; Baltimore, MIL, as aignor'to erel Propeller'Corporation, Baltimore, Md.. Hanoi-notation cr nial-flu d f l spirates ,la fa ioio, stadiums 4338a sci'aum.

referenceto an automatic variable ,pitch propeller. a x H a In general, automatic. variable pitch propellers operate upon the theoryof so constructing the propeller that the blade is capable-of movement to alter the pitch as" a result of some or all of the forces acting upon the blade when rotating. The present invention isdirected to a propeller in which the blade'vis pivoted to" the hub in such-a way that it is capable of limited rota-- tion and, in such movement; describes an arc of. a cone.

An object of this invention is to, provide a novel hub construction which is'adapted for use in a propeller of the type above mentioned.

Yet another object of this invention is to provide means for mounting the'propeller blade on such a hub;

A still hirther object of this invention is to g provide a novel pivoting arrangement it! such construction, a

' To accomplish the above and other important objects my invention in general embraces the concept of mounting a propeller blade upon a.

hub to permit limitedrotation of the io'rmerfto describe the arc of afsurfaceof a'cone.

principal 'forces" in-' effecting such movement within the arc, during operation of the propeller, are centrifugal .forces acting on the blade and the drag of the blade. Auxiliary means such as librium between .these forces, and any .other' forces, encountered duringrotation of a propeller. More specifically, the blade is pivoted uparcuo-conical path desired for. the particular propeller. While the position ofthe pivotal axis may be varied within certain limits to-meet the on the hub in' such a mannerias to insure the.

170-164 j x structed in accordance with my invention; 'the propeller being in inoperative position. Figure 2 is a view-similar. to Figure l; butin-u didating' the relative movement between the blade and 'hub which is possible during rotation of the propeller.

Figure 3 is a side ,view of the propeller, in

which thesolid nd dottedlines' of the blade represent two different positions that -'the blade may assume during flight. I

Figure 4 is .a' sectional'view-alon'g the line 4- 4 of Eigure-2 lookingin-the directionof the arrows, and showing in detall by the dotted line the variation in pitch of the propeller resulting from'movement of the propeller along the arc of the cone as above mentioned.

Figure '5 is a detailed view along the line 5-5 of Figure 1 looking in the direction of the arrows. l Figure 6 is a' View along the line 6-6 of Figure 5 looking in the direction of the arrows.

Figure 7 is a view taken along .the line '|.'|of

Figure 5, but showing the sides of the hub open and the blade in a radial position and at its point of maximum pitch; v

Figure 8 is a view generally similar to Figured,

.'Figure 8 looking in thedirection of the arrows.

It will be observed that the assembled propeller 1 comprises a hub generally designated I and blades designated generally 2 carried by the hub. The

hubis adapted to be splined, or rigidly mounted 3 'shaft3.-

exigencies of any particularsituation, in gen.- eral the pivotal axisis .angularly disposed ,with' respect to the plane of rotation'of the propeller,

and preferably lies ih'a plane which is perpendicularto such plane and also intersects the axis of rotation. A specific embodiment of my in-. vention, showing-certain detailed constructional advantages, isdisclosed in the accompanying drawings and described. hereafter, it being understood however that various departures may be made therefrom without exceeding the scope oi my'invention. T l

In the accompanying drawingsin which similar numerals refer tolthe same part: Figure 1 is a front view/oi a propeller coril or the huband are pivoted upon the arm Eatthe front of. the hub, -The'forward end of each Referring more particularly'to Figure -5, the

hub consists of a sleeve .4 which receives the drive shaft 3, and thlssleeve is provided with {a pair of radially disposed arms 5 and 6 whichiorm .in effect a recess for each blade, or more" specifically for a blade socket. It will be noted that thearm 8 is of greater length than the arm 5,which is a for the purpose oi permitting the drilling of diagxonally aligned apertures I and through the two arms.

Extending the min length or. the hub are side memberst which are similar in construction.

The.slde members are provided with ears II at each end which bend over the top and bottom side member a is provided with an inturned lip 8 respectively,

v to centrifugal force to a C ment with respect to the arms shown inF'igure 8. This is possible in view of pitch when the blade is radial with; respect to :the axis of rotation, as showninFigure 1, and

and 26 of the socket 18. The propeller isdel2' which, upon opening the side members as shown in Figure 2, abuts against a cap 13 which closes the front of the sleeve 4.

.The rear of each side'member 9 is provided withan outwardly extending flange H which 5- carries one or more pins l5, oppositely disposed with respect to corresponding pins on the other side member. Theside members'are apertured as atit, as best shown in Figure '7, and a springl'l passes through each aperture and is secured to the oppositely disposed pins I5. The springs. resiliently urge the side members to a closed position to lie against a socket forthe blade as will be later described, but upon rotation of the propeller the side members 9 are forced open due- 'l d 7 position where the lips" I2 abut against the cap i3. r v

The blades 2 are provided with the usual" shanks which are held in a socket l8 by means'of a pm I 9. The s'ocket- I8 is drilled for a hole '2i which, when the socket is in assembled position in the hub, is aligned with holes 1 and 8 in the arms and'B.

A pin is adapted to pass through the holes 8, 2! and 1 to form a pivot with which the socket l8 may swing to a predetermined degree, and, while any conventional'type of pivot pin m y be employed, I find that, if a counter-balance weight is necessary foroppo'sing the centrifugal action on the propeller blades, the arm of such weight may be bent to serve as the pin. As shown in the drawings, a counterweight 22 is mounted upon an arm 23. This arm is bent to serve as the pivot pin 28a. .14. set screw 24 maybe screwed into a threaded hole in the socket .i8

' -to engage the pin 23a and hold it fixed both longitudinally and rotatively" with respect to the socket I8. 7 I J It will be appreciated that the socket iii in pivoting with the pin 23;: incurs twisting move.- andfi, as best the fact that the diagonally oppos'dcorners of the socket l8 are beveled as at 25- and 26 (see Figure 9), which permits ofxlim'lted twisting movement, and the extent of this bevel of course determines the amount of twisting movement'possible. It will be appreciated that in such pivoting and twisting of the socket I 8, the bladed... moves between the positions indicated by the solid and dotted lines of Figures zi, with a consequent chan e in the pitch of the blade. '3

In actual operation, the blade has a maximum by the solid lines in' Figures 2', 3 and 4. The blade is in this position when the hub is stationary inasmuch 'as the side members 9 maintain ,it in this position as shown in Figure 6. Upon,..

rotation of the propeller, the side members open to a position shown in Figures 2, '7 and 8. and the blade is then free to assume the 0ptimum pitch for the operating condition encountered,

within the limits determined by the bevels 25 signed so that the blades will be ln a condition 5 of substantial equilibrium for any given opera-' tion. In'other words, theangleat which the socket l8 is disposed 'with respect to the. arms 5 and- 6, the use (number, weight ;and disposition) of the counterweights, and the, degree of bevels .25, will allbe designed upon the determination j of various factors involvedln the particular air- .plane under consideration, all in accordance withez-r. \tion-an angle. of :less than 96. L

recognized aeronautics practice In general,,-the 3 3 n propeller assembly comprising g 1 peller speed, and the design 0 specific position of the blade with respect to the hub for any given condition of flight, will be principally the function of centrifugal force upon the drag of the 'blade during rotation (althoughother factors may be encountered to a less degree). As indicated above, suitable, counterweights may be used. to modify these. forces.

- In actual operation the' drag upon the propeller is determined by the engine torque characteristics. The tendency oi the propeller drag is to urge the blade out 'of a radial position and hence into a lower pitch. This tendency is opposed by the centrifugal forces acting upon the b de tending to urge the blade'into higher pitch.

e centrifugal force efl'ects are a function of the propeller revolution speed and of the angular position of the blade with respect to the hub. The blade will thus find an equilibrium position or pitch dependent upon the .engine torque, pro'- fthe blade for the particular propeller.

It will be seen from the foregoing that I have provided 'a propeller in which the blades, are adapted to automatically assume positions of varying degrees of pitch, and which, for any given condition of fiight, is in a position of substantial equilibrium. I It will be appreciated that the mechanical structure of this propeller is economical and efficient and provides novel means for securing the automatic variations in pitch.

While I have described the invention with particular respect to a two-blade propeller for an airplane, the precise number of blades is. immaterialhand furthermore; my inventive concept may be applied to other devices than airplane propellers. Consequently, the use of the expression propeller in the claims is not to be strictly construed, 'but is designed to include all devices of this general character, such as fans, etc.

I claim: I 1. A propeller assembly adapted to be mounted on a drive shaft of an airplane comprising a sleeve adapted to be secured to the drive shaft..

spaced arms extending radially from the sleeve, a propeller blade pivotally mounted between the said arms,-a counterweight for said assembly. a

section of said counterweight extending through the said arms and forming he"pivot upon which the blade is mounted, said s tion lying in a plane spaced arms extending radially from the sleeve;

9. pair of propeller blades the roots of which are mounted between said arms in opposed relation, side members hinged on opposite sides of one of said radial, arm's..each of said side members being designed to engage one ofthe aligned sides ofthe said propeller rootspresilient spring means tohold the said side members against the propeller bladeroots until separatedby centrifugal forces caused,jby the revolution of the propeller, apair of pivot pinsext'ending' through the said arms, each pin forming aflpivot upon which one of the roots of the said. propeller blades is mounted, v said pinsglying in. aplane perpendicular't'o the plane of rotation of. the propeller, and. th axis of'each pinforming with the er assemblyadapted tobe mounted axis of rotdfor v mounting on a drive shaft of an airplane engine, arms extending radially from the sleeve and. fixed relatively thereto, said arms being -spaced axially of the sleeve, a propeller blade having its shank mounted between said arms, a

.pivot pinextending through said arms and the shank of theipropeller blade and forming a pivot upon which the propeller blade is mounted for pivotal movement, said pivot pin lying in a plane containing the axis of said sleeve and the axis of said pin forming an angle of less than 90 with the axis of saidsleeve plate means posi- 'tioned on opposite sides of the blade shank, and

resilient means urging said plates into engagement with theshank to urge said blade to a predetermined position.

4. A propeller assembly comprising a sleeve 7' for mounting on a drive shaft of an airplane engine, arms extending radially from the sleeve and fixed relatively thereto, said arms being spaced axially of the sleeves. propeller blade having its shank mounted between said arms, a

pivot pin extending throughsaid arms and the shank of the propeller blade and forming a pivot upon whichthe propeller blade is mounted for pivotalmovementpsaid pivot pin lying in a plane containing the axis of said sleeve, the axis of said pin forming an angle of less than 90 with the axis of said sleeve, said pivot pin being'rotatably mounted in said arms and fixed to the shank of the propeller blade, a crankarm extending from one end of said pivot pin and a weight responsive to centrifugal action mounted on the free end of said arm. V i 5. 'A propeller assembly comprising a sleeve I for mounting on a drive shaft ot an-airplane containing the axis of said sleeve, the axis of engine, arms extending radially from the sleeve with the axis of said sleeve, flap means hingedly mounted on oneof said arms, and resilient means urging said flap means into engagement with theshank oi the propeller blade to maintain said blade in a predetermined position;

6. Apropeller. assembly comprising a sleeve for mounting on a drive shaft of an airplane engine, arms extending radially from the sleeve and fixed relatively thereto, said arms being spaced axially of the sleeve, a propeller blade having its shank mounted between said arms, a

pivot pin extending through said arms and theshank of the propeller blade and forming a pivot upon which the propeller blade is mounted for pivotal movement, said pivot pin lying in a plane said pin forming an angle of less than 90. with the axis of said sleeve, flap means hingedly mounted on one of said-arms, resilient means urging said flap means into' engagement with the shankof the propeller blade to maintain said [blade in a predetermined position,. and'weights on said flap means operable by centrifugal action during rotation of the propeller to oppose the action of said resilient means. i

WALTER W.

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