US2155311A - Variable pitch propeller - Google Patents

Description

Filed June 26, 1936 2 Sheets-Sheet l mvzufon ATTORNEYS April 13, 1939. P. HORROCKS VARIABLE PITCH PROPELLER I Filed June 26,-1936 2 Sheets- Sheet 2 uronnevs Patented Apr. 18, 1939 UNITED STATES PATENT OFFICE.

vsnmnm Prrcn PROPEILEB r Percy Hot-rocks, Hyde Park, 1v. Y. Application June at, 1936, Serial No. 81,500

3 Claims. (01. 170-163) The present invention relates to aircraft propellers and more particularly to mechanisms associated with a propeller bywhich the pitch of the blades thereof may be varied.

The primary object of the inventionis to pro- -vide a simple and rugged mechanism of a minimum number of parts adapted for construction within the hub of a propeller whereby the blade pitch may be adjusted to any desired angle at the will of the pilot.

Another object resides in the novel arrangement of certain elements of the mechanism comprising the invention which, in addition to providing blade pitch varying means, affords reinforcing members for the propeller blades so as, during rotation of the propeller, to counteract the centrifugal force and bending stresses imparted to the blades.

A further object of the invention is to provide a propeller pitch change actuating mechanism,

the same being particularly adapted for symmetrical arrangement about the axis of rotation of the propeller thereby obviating'the occurrence of vibration and other such detrimental reactions re- 35 sulilzing from high speed operation of the prope er.

The invention will be fully and comprehensively understood from a consideration of the following detailed description when read in connection 30 with the accompanying drawings which form part of the application.

In the drawings:

Figs. 1 and 2 are side and rear elevational views, respectively, of the variable pitch propeller di- 35 rected to illustrate the general arrangement of same.

Fig. 3 is a fragmentary sectional view of the propeller hub portion taken on the Planes indicated by the staggered line 32 of Fig. 1 and 40 illustrating the actuating mechanism for effecting the blade pitch change; and

,Fig. 4 is a transverse sectional view taken on line 4-4 of Fig. 3.

Referring now to the drawings for a more de- 45 tailed description thereof, the numeral 5 indicates the drive shaft by which the propeller is rotated, the same being secured to the propeller hub 6 by suitable means such as that illustrated in Fig. 4. Onto the hub 6 is formed a cylindrical 60 casing I, the same. including at its forward en a removable cover 8.

In the cylindrical wall of the casing I are journaled' a plurality of propeller blades 9 preferablysecured for axial rotation in bearing sleeves I! ll integral with the casing 1. The blades I are retained for rotation within the bearings Ill, preferably in the manner shown in Fig. 3 in which the blade spindle includes a thrust collar l2 adjustably secured within the hearing In by a threaded sleeve l3. 5.

The means for rotating each of the propeller blades 9 to effect the pitch change thereof comprises a pull rod l4 extending from within the casing I and substantially longitudinal to the blade 9, being anchored at the tip |5 thereof. 10 The pull rod I4 is slidably retained in a slide bearing It, the latter being secured to the blade 9 preferably'at the widest portion of the-blade and adjacent the trailing edge of same. Each of the pull rods l4 extending to within the casing 15 I thru suitable apertures H in the wall thereof are pivotally anchored, as indicated at 8, to the end wall of the casing I.-

As hereinafter described, the variation of the blade pitch is effected by exerting a pull on each 20 of the rods M, which pull is effected by means comprising apinion gear l9 disposed centrally in the casing I. 'I'he pinion gear I9 is carried on and rotated by a shaft 20, which shaft extends anally from the drive shaft 5 and is mounted for rotation independently of same in a central bore of the drive shaft 5. It is, of course, to be expressly understood that the shaft 20 positioned concentrically within the drive shaft 5 can be moved relatively thereof during operation of the propeller. That is to say, the shafts 5 and 20 during use can be rotated at the same speed or at slightly different speeds whereby relative rotation takes place. The actuating means for the I pull rods I 4 also includes a series of sector gears 2|, each of which is mounted for rotation about a stud 22 secured to the casing 1. Each of the sector gears 2| is formed in an arcuate flange 23 on which is carried an'internal gear 24. The

. web of each of the sector gears 2| has a cut-out 40 portion 25 to permit the shaft 20 to extend therethru.

It will be observed that the rotation of the pinion gear I9 actuated by means of the shaft 20 will impart to each of the sector gears 2| an angular movement. This movement is transmitted to the pull rod H by having the mentioned rod secured to the sector gear 2| by means of a lug 26 projecting from a corner of the sector gear 2|. The rod I4 is fixed to the lug 26 by a series of clamping elements 21 extending thru the latter. 1

In considering the operation of the mechanism to effect a pitch change it will be noted that in view of the eccentricity of the slide bearing l6 l8 on the blade. 8 that the exertion of a substanbetween the point I8 and the bearing l6 will be l0 which'the pull rod l4 functions to change the foreshortenedand in consequence the bearing it will be moved in the manner to cause the rotation of the propeller blade 8.

To return the propeller blade to its normal pitch the pinion gear l9, being reversed, will cause the rod H to be brought to a straight line. form during which the rod' II by a thrust action pushes the hearing I to its normal position. In accordance with the theory of operation by pitch of the propeller. blade 8 the action occur-- ring takes place substantially between the hearing l8 and the pivotal anchor ll! of the pull rod I 4. Accordingly, the bearing Ii may be considered as forming a fixed connection of the rod be omitted. However, the arrangement illus-- ll to an eccentric portion of the blade 9. However, in order that the rod ll serve as a reinforcing element to the blade 9, same is arranged to slide within the bearing I 6 and is extended longitudinally or the blade 9 to be ancho ed at the tip I! thereof. This arrangement is p ovided so that the rod Il may serve as a strengthening element to the blade 9 by counteracting a centrifugal'force imparted to same during the high speed rotation of the propeller.

Referring to Fig. 3, it will be observed that the pivotal anchor ll of the rod I4 is substantially adjacent the point of rotation 22 of the sector gear 2| and since the rod llis fixedly secured to a corner of the. sector gear 2| by the lug 26, that section of the rod ll between the lug 26 and anchor ll will move in unison with the adjacent edge of'the sector gear 2| and may accordingly trated is preferred so that in the event of failure of any of the actuating members preceding the rod M, the latter will merely move to its normal straight line position and thus permit the blade I to return to its normal pitch.

It is to be understood that this improvement is capable of extended application and is not confined. to the exact showing of the drawings nor to theprecise construction described and,

therefore, such changes and modifications may be made therein as do not affect .the spirit of the invention nor exceed the scope thereof as, e;-

pressed in the appended claims.

What is claimed as new is:

1. A -.variable pitch propeller comprising in combination, a propeller hub, a series of blades extending from said hub and rotatably mounted therein, a pull rod for. each of said blades.connected to an eccentric point thereof, said pull rods converging to said hub and actuating means associated with said hub for tensioning said pull rods so as to rotate said blades, said actuating means comprising a rotary pinion-gear and a series of sector gears in mesh with said pinion gears, each of said sector gears being operatively connected to one of said pull rods for tensioning the same so as to rotate said blades.

2. A variable pitch propeller comprising in combination, a propeller hub, a drive shaft secured to said hub, a series of blades extending from said hub and rotatably mounted therein, a

pull rod for each of said blades connected to an eccentric point thereof, said pull rods converging to said hub and actuating means associated with said hub for tensioning said pull rods so as. Y

to rotate said blades, said actuating means comprising a' rotary pinion gear and a series of secon said hub casing, a pull rod for each ofsaid blades connected to an eccentric point thereof, said 'pull rods converging to said hub casing and terminating within same,'and actuating means associated with said hub casingfor tensioning said pull rods so as to rotate said blades, said actuating means comprising a rotary pinion gear and a series of sector gears pivotally mounted within said casing and in mesh with said pinion gears, each of said sector gears being operatively connected to one of said pull rods for tensioning the same so as torotate said blades.

PERCY HORROCKS.

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