US2939536A - Hub structure for an aeronautical propeller - Google Patents

Description

June 7, 1960 c. M. KEARNS, JR 2,939,536

HUB STRUCTURE FOR AN AERONAUTICAL PROPELLER Filed May 5, 1958 H INVENTOR. i I W CHARLES M. KEARNSJR.

ATTORNEYS FIG. I

United States Patent 071cc 2,939,536 HUB STRUCTURE FOR AN AERONAUTICAL 1 'YPROPELLER. p l

Charles M. Kearns, Jr., Wethersfield, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Filed May s, 1958, so. No. 132,979 2 Claims. Ca ro-160.58

This invention relates to an improved hub structure for an aeronautical propeller and, more specifically, to an improved spider and barrel construction for a hub;

It is the general object of the invention to provide an. aeronautical propeller hub wherein the spider and barrel members thereof are characterized by their lightweight, metal-saving form, one-half of the barrel being-formed integrally with "the spider in a constructionwhich in-.

the scope of the invention, the claims forming a part of' Of the drawing:

Fig. 1 is a view partially in section through the hub of an aeronautical propeller incorporating the features of the present invention; and

Fig. 2'is an exploded perspective view of the spider and barrel which feature the. hub structure of this invention.

Referring to the drawing in detail, the referencenuthis specification beingrelied upon for that purpose.

meral indicatesgenerally the propeller shaft definingthe axis of an aeronautical propeller assembly which-includes, radial propeller blades, such as the blade 12. It has long been the practice to transmit torque from the propeller shaft to the propeller blades in a hub which ne lldes can".elementormember. commonly called a spider which embraces and is connected .to' the shaft and which has arms extending into the hollow interior of the root section of the blades. It has also been an established practice to provide as apart of the hub structure an element or member commonly referred to as a barrel which is formed'in two halves for connection around the inboard or'root end portions of the propeller blades to retain them in engagement with the spider so that they are rotated with the propeller shaft. In these prior constructions, the barrel elements transmitted little, if any, torque from the shaft to the blades, the barrel elements being used solely for the purpose of retaining the blades. In accordance with the present invention, one-half of the barrel construction is formed integrally with the spider so that the barrel transmits part of the torque or load from the propeller shaft to the blades, permitting a weightsaving and economical change in the spider construction while at the same time providing for greater over-all strength in the hub structure.

As shown in the drawing, the spider is indicated generally by the reference numeral 14 and the barrel is designated generally by the numeral 16, the said barrel comprising two halves 18 and 20, the rear or inboard half 20 being formed integrally with the spider 14. As was the 2 case with the prior structures, the hub provided in accordance with the present invention is designed to accommodate the pitch changing mechanism and other devices associated with a controlled pitch propeller capable of being feathered and placed in reverse pitch. The pitch chang-v j ing mechanism which is suported by the hub structure is located forwardly thereof 'within a propeller dome 22. The details of'the pitch changing mechanism form no part of the present invention and such mechanism may vary considerably as to detail. A preferred pitch changing mechanism is hydraulically operated and of the general type shown in the Caldwell, Martin and Anderson Patent- 2,l74,7l7 to which reference maybe had for a detailed disclosure of the mechanism. v

Included in the pitch changing mechanism as shown in the aforementioned patent and as shown by way of example in the accompanying drawing is a rotatable cam 24 which is rotated on the propelleraxis in one direction and the other'when the pitchchanging mechanism calls for a change in the propeller blades toward high and low pitch, respectively. Bevel gear teeth 26 are provided on the inboard end of the cam 24 and are in continuous en gagement with the teeth on a gear ring or segment 28 connected to the inner end of each propeller blade 12.

Thus, in operation of the pitch changing mechanism' within the dome 22, the cam 24 is rotated on the propeller axis to efiect rotation'of the propeller blades, all in the same direction and to the same degree on their respective pitch change axes-which are in a common plane at substantially a right angle-to the-propeller shaft axis.

The spider 14 has a susbtantially cylindrical rear end portion 30 surrounding the propeller shaft 10 and con; nected thereto as by a splined connection indicated at 32.

The front end portion 34 of the spider is'also generally cylindrical, but it has formed thereon a'plurality of radially extending arms 36, 36 which are equally circumaxially spaced and which correspond in number to the propeller blades, a four-blade installation being shown. Each radial arm 36 is preferably cylindrical in form,-and' in the assembled propeller, each arm extends-into a bushing 38 disposed in the hollow inner end of a propeller blade 12.- It is important to observe that the arms 36, 36{ are short by comparison with the conventional spider arms as shown, for example, in theaforementioned Caldwell et a1. Patent No. 2,174,717. The short spider arm: structure made possible by the present invention providesfor economy and ease in manufacture, and, more irn'portantly, there is a substantial saving in weight in thefin ished structure without sacrifice of strength.

The'weight-saving short spider arm construction is accommodated in accordance with'the present invention by providing the rear or inboard barrel half .20 as an integral part ofthe spider 14.- Thatqis inlthe preferred form,- the;

rear barrel half 20 is formed as a radially outwardly extending skirt-like'wall 40 on the generally cylindrical rear portion 30 of the spider. The rear barrel half 20 has a forwardly projecting flange 42 wherein there is provided a plurality of forwardly facing semi-circular openings 44, 44 which are equal in number to the spider arms 36, 36 and similarly circumaxially spaced. In the example shown, there are four semi-circular openings 44, 44 to accommodate four propeller blades. In addition, there are four radial connecting flanges and bosses 46, 46 defined on the front face of the forwardly extending flange 42, one such-flange and boss being provided between adjacent semi-circular blade-receiving openings 44, 44.

The front barrel half or section 18 is generally similar and complementary to the aforedescribed rear barrel half 20. The said front barrel half has a forwardly projecting generally cylindrical portion 48 which receives the rear end of the propeller dome'22. It also has a radial Patented June 7,1960

and rearwardly facing skirt or flange provided with a plurality of substantially semi-circular openings 50, 50 similar to the blade-receiving openings 44, 44 on the rear half of the barrel as described above. In the example shown, thereare fouropenings 50, 50-equally c ircumaxially spaced around the front'barrel half 18 and opposed to the openings 44, 44 in the-rear barrel half 20. A radial Connecting flangeand boss 52 is provided between each pair of adjacent openings 50, 50 for engagement with the corresponding flange and boss 46 on the rear barrel half 20. Thus, when the front and rear barrelhalves are engaged substantially in the plane of the propeller blades and they are connected as shownin Fig. l, the openings 44, 44 and 50, 50 on the respective barrel halves define circular openings within which the inner end portions of the propeller blades 12, 12 are received and retained. The barrel halves are secured in engagement by through bolts and nuts as indicated at 54, the said bolts passing through the connecting flanges and bosses 46 and 52. y

Now, it will be observed that in addition to being hollow to receive the spider arms, the inner end portions of the propeller blades are provided with radial flanges. The blade flanges may properly be referred to as retaining flanges in that said flanges cannot be withdrawn through the blade-embracing circular openings defined by the connected barrel halves. That is, the forwardly projecting flange 42 on the rear barrel half wherein thesemicircular openings 44, 44 are defined and the rearwardly projecting flange on the front barrel half wherein the semicircular openings 50, 50 are defined overlie the blade flanges.

Therefore, in order to accommodate assembly of the blades with the rear barrel half and spider, it is necessary to have the forwardly projecting flange 42 on said rear barrel half spaced radially outwardly from the ends of the spider arms 36, 36. In actual assembly, a blade 12 is placed over a spider arm 36 and then the two'halves inner end, and for transmitting torque from a shaft on the propeller axis to the blades and comprising, a spider having a generally cylindrical portion embracing and connected to the shaft and having a plurality of radial arms corresponding in number to and which are received within the inner ends of the blades, and a barrel comprising front and rear halves whiclrengage substantially in the plane of the blades, the front half having ,a rearwardly projecting flange provided with substantiallysemi-circular openings facing rearwardly and with radial connecting flanges disposed therebetween and the rear half having a forwardly projecting flange provided with complementary substantially semi-circular openings facing forwardly and with complementary,-radial connecting flanges disposed therebetween, whereby by engaging and connecting the radial flanges of the respective barrel halves the blades are surrounded and retained within the circular openings of the connected barrel with the forwardly and rearwardly projecting flanges on the barrel halves overlying the flanges of the respective blades, and the rear half of the barrel being formed integrally with the cylindrical portion of the spider and with its forwardly projecting flange spaced radially outwardly from the spider arms to accommodate blade assembly.

2. A hub for retaining a plurality of radial aeronautical propeller blades, each of which has a radial flange on its inner end, and for transmitting torque from a shaft on the propeller axis to the blades and comprising, a

spider having a generally cylindrical portion embracing of a thrust bearing ring 58 are placed around the blade between the blade flange and barrel flange 42. Then, a plurality of bearings 60, 60 are located between the thrust bearing 58 and the barrel flange 42. And, finally, the front barrel half 18 is placed in position and connected to the rear half 20 by the through bolts and nuts 54, 54. A sealing gasket or packing 62 is preferably provided in a suitable groove in the assembled barrel around each blade. 7

Obviously, assembly ofthe blades to the hub and shaft is made more simple by this invention. Less obviously, the hub is of less weight than prior constructions due to the reduction in size of the spider arms, this being possible by forming one-half of the barrel as an integral part of the spider whereby the said one-half of the barrel shares the torque transmitting function of the spider arms.

- The invention claimed is:

1. A hub for retaining a plurality of radial aeronautical propeller blades, each of which has a radial flange on its and connected to the shaft and having a plurality of radial arms corresponding in number to and which are received within the inner ends of the blades, and a barrel comprising front and rear halves which engage substantially inthe plane of the blades, the front half having a rear-' wardly projecting flange provided with substantially semicircular'openings facing rearwardly and with radial connecting flanges disposed therebetween and the rear half having a forwardly projecting flange provided with complementary substantially semi-circular openings facing forwardly and with complementary radial connecting flanges disposed therebetween, whereby by engaging and connecting the radial flanges of the respective barrel halves the blades are surrounded and retained within the References Cited in the file of this patent UNITED 'STATES PATENTS 7 Martin Dec. 7, 1937 Cushman July 11, 1950

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