US2237030A - Aeronautical propeller - Google Patents

Description

Ap 1, 1941. P. J. GATHMANN AERONA UTICAL PROPELLER Filed June 14, 1938 5 Sheets-Sheet l IN VENTOR Zmazzrz.

ATTORNEY P. v.1. GATHMANN 2,237,030

April 1941.

April 1, 1941. v P. J. GATHMANN AERONAUTIOAL PROPELLER Filed June 14, 1938 5 Sheets-Sheet 3 APril 1941- P. J. GATHMANN 2,237,030

AERONAUTICAL PROPELLER Filed June 14, 1938 5 Sheets-Sheet 5 Patented Apr. 1 1941 UNITED STATES PATENT OFFICE azsipso A ,AERQNAUTICAL PROPELLER Paul J. Gathmann, Lombard, 111. Application June 14, 1938, Serial No. 213,646 7 Claims. (01. 170-162) This invention relates to certain improvements n aeronautical propellers. One object of the invention is the provision of relatively simple and automatically operative means for changing the angular pitch of the propeller blades in response to changes of engine speed. Another object is to arrange such automatic mechanism for actuation by centrifugal force during rotation of the propeller. Further objects and the specific n-a e of the invention will be readily recognized oy those skilled description and explanation, panying drawmgs illustrating certain embodiments thereof; that various modifications and re-arrangements of the features and elements may be made without departing from the spirit and scope of the invention, and that I do not limit myself to the ticular forms and combinations herein shown, except as indicated by the accompanying claims.

the drawings:

Figure l is a front elevation of an aeronautical propeller with the hub cover plate removed, and with parts shown in section to reveal certain details of construction.

Figure 2 is a transverse section of the propelle'r taken substantially at the plane of the axis of the drive shaft and through the intersecting axis of one propeller blade.

Figure 3 is a section taken transversely through a propeller blade, and indicating its range of adjustment with respect to the plane of rotation for and from the accompreferred relatively low engine speeds.

Figure 4 is a similar section through a propeller blade indicating the range of angular adjustment employed at normal engine speeds in flying. I

Figure 5 is also a section through a propeller blade showing its adjustment transversely of the plane of rotation .to serve as a paddle wheel resistance or brake to prevent racing of the engine.

Figure 6 is a transverse detail section taken as indicated at line '6-6 on Figure 2.

in in the art, froni the following Figure 12 is a. detail section taken transversely of the drive shaft and looking into the front cover plate. v

Figure 13 is a front elevation of the central portion of the propeller showing the cover plate in position.

Figure 14 is a transaxi-al view of the hub portion.

of a propeller embodying the modification of the invention.

Figure 15 is a section taken as indicated at line 15-45 on Figure 14.

Y the weights of Figure 14.

but it should be understood Figure '7 is a transverse section taken as indicated at line 1-4 .on Figure 2.

Figure 8 is a detail section showing the centrifugally operated weights and their inter-connection through a crank plate.

Figure 9 is an edge view of the crank plate.

Figure 10 is a detail section on a. larger scale showing one of the weights and being taken substantially as indicated at line lO-Hl on Figure 8.

Figure 11 is a detail section on an enlarged scale showing one of the synchronizing pinions and its control spring.

Referring first to Figures 1 and 2, it will be seen that the structure therein illustrated includes a chambered hub housing l0, supporting a plurality of radially disposed propeller blades, preferably of metallic material, and'each mounted for easy rotative adjustment about'its own axis in bearings formed in the radial branches of the housing H), with shoulders l2 and I3 arranged to receive the radial thrust of the blades due to centrifugal force. The hubhousing I0 is fixedly keyed to the propeller drive shaft 14, as by splines HI, and M and is held in place on the shaft by a retaining nut l5 screwed onto the outer end of the shaft, as seen in Figure 2. V

Each of the propeller blades H terminates at its root end in a hollow shank I l having on its inner surface a plurality of helical grooves I6.

As illustrated, the propeller is provided with three blades, and the hollow shanks of these blades contain automatic controlling weights t8, I9 and 20 respectively, each formed with helical ribs or splines of suitable pitch and dimensions to intermember with the helical grooves in the hollow propeller shanks. Thus, in response to centrifugal "force generated by rotation of the propeller about the axis of its drive shaft I4, the weights t8, l9

and 20 tend to move radially outward in. the

shanks of the respective propeller blades, and if the weights be restrain-ed against rotation, their movement will tend to produce rotative adjust.- ment of the propeller blades by virtue of the interengagement of the helical grooves and splines.

As seen in Figure 8, the weights l8, l9 and 2D constitute a unitary assembly by virtue of their connection to a crank plate 2| which is mounted for free oscillatory movement upon the propeller shaft l4 and is formed withrecesses 22, 23 and 24 in its periphery. These recesses respectively accommodate the connecting torque rods 25, l6v and 21, each having one end attached to the crank plate 2| by means of a pivot pin 21 At their opposite ends the rods are connected to the respective weights by pivots I 3 I9 and 2|] which extend through recesses I 8 I!! and 20 in which the ends of the rods are accommodated similar and equal movement of the other weights, I and any tendency to inequality in such movements as might result from difierences of friction' or otherwise, will be integrated and equalized by this inter-connection of the weights to the crank plate 2|. At the same time, the connect ing rods 25, 26 and 21, being of rectangular crosssection and fitting snugly between the parallel cheeks 9f the recesses 22, 23 and 24, and the cheeks of the recesses l8 N and 20 operate as torque members to prevent twisting or rotatlve movement of the weights, thus insuring that their radial travel will cause rotative adjustment of the propeller blades.

Each of the propeller blade shanks II- is provided at its root end with a mitre gear 28 extending well into the hub housing It), and these gears, in turn,..mesh with synchronizing pinions 29 journaled in the wall of the housing, as seen in Figure 1. a

The front side ofthe hub housing In is provided with a removable cover plate 3| within lar 43 on the stub shaft. Thus any rotativ'e adjustment of the propeller blades, causing corresponding rotation of the pinions 29, inter-meshing with the mitre gears 28, takes place in thepresence of some tension in the springs 46, which serve to take up any possible back-lash in the connections, insuring smooth, even movement throughout the range of adjustment, and avoiding vibration of the parts with respect to each other. Maintaining this' spring tension and operating in opposition to it at all times is the centrifugal force created in the weights l8, I9 and 20 by the rotation'of the propeller assembly.

The retractor spring 35 operates in the-. ,same

direction as the springs 46, so that all the springs work together to prevent looseness or vibration in theoperationpf the automatic adjusting features. And in order to effect a still more perfect synchronization of the parts I may provide aring gear 50, which is formed as a mitre gear and is shown in Figure 2 as rotatively mounted on the internal hub portion l0 of the rear bearing of the hub housing so as to mesh with the three mitre gears 28, but not with pinions, 29.

which there is enclosed a worm 32 and a worm wheel 33 meshing therewith, as best seen in' Figures 2 and 12. The worm wheel 33 has a central hub sleeve 34 suitably bored to fit loosely upon the propeller shaft I4,- to permit of easy rotative adjustment by operation of the worm 32. Such adjustment may be eifected by means of a" suitable tool, such as a socket wrench, engaging the squared end 32 of the shaft of the worm 32, which is accessible through an opening 3 I in the cover plate 3| ,as seen in Figure-13.

To provide a balancing eifect and prevent back-lash or vibration during rotative adjust '35 is thus adjustable by means of the worm 32.

The transverse surface 33 of a recess 33 in the cover plate 3| serves as a thrust bearing to accurately position the worm wheel 33 in alignment with its worm 32, while the hub sleeve 34 extends into abutment with one hub of the crank plate v 2|, the other hub of the crank plate being fitted against the inner end surface 2| of the rear hub bearing so that the crank plate 2| is maintained in proper relation to the common plane of the propeller blade axes.

Referring again to the synchronizing pinions 29, it may be noted that they'are mounted for easy turning in the bearing blocks 40, which are suitably threaded to be screwed into position in threaded openings of the hub housing l0, Each of the pinions 29 has a stub shaft 4| protruding through the bearing block and terminating out.- wardly ina short, square'shank 42, upon which. there is'mounted a collar, 43, having asquare hole 43 by which' it engages the shank 42 for; turning therewith. A retaining nut 45 holds the collar in place.- A retracting spring 46 is shown coiled around a protruding portion of the bearing block 40 and the outer end of the stub shaft,

- with one end of the spring anchored to the bear- -ing block and the other end secured to the col- It should be understood that. in the drawings the parts of the invention are shown in the positions which they occupy when the propeller is not in operation, the'weights l8, l9 and 20 being shown at their innermost limiting positions nearest the axis of the shaft l4, from which positions they wi11 gradually move outwardly under the influence of the centrifugal force generated by rotation of the propeller. -With the parts in the positions indicated, the retracting springs and their bearings and in opposition to the tension 46 are at minimum tension, but as the propeller revolves, the weights, being held against rotation by ,virtue ofwtheir engagement with the torque rods 25, 26 and 21 and the crank plate 2|, will travel radially outward, causing the hollow shanks ll of the/propeller blades, to-turn in of the springs 46, acting through the mitre pinions 29, and to the tension of the spring 35 tending to resist rotation of the crank plate 2|. Thusthe centrifugal force is balanced againstthese variable spring tensions to insure smooth action and a definite position of each part throughout the range of adjustment.

The parts are all substantially symmetrical in their arrangc'ment about the axis of revolution, so that the perfect balance of the propeller is main-' tained for all speeds,

Figures 14 and-l5 illustrate a modification of the'structure, and although, in these views, the propeller is shown as having only two blades, it should be understood that this form of the invention is equally applicable to a propeller. of three blades, such, for example, as that shown in Figures 1 to 13. In this form the hub housing A is secured by means of splines B to the drive shaft C for rotating the propeller as an entirety. Securely fastened to the shaft C within the hub. hou,sing'A is a block-like sleeve D; if desired, the splines B may extend into the block to secure it firmly to the shaft 0 for-rotation therewith. The block D carries radially extending torque rods E, E, each of which is of square cross-section, and which may be made integral, with the block D. v

The hub housing A includes suitable bearings ,A in which the hollow shanks of the propeller blades A are mounted for easy rotative adjustment. The inner wall of thehollow shank of each propeller blade is formed with a plurality of helical grooves E which register with and engage shanks to synchronize and equalize the helical splines G extending-from the pitchchange governorweights' H. These weights are preferably cup-shaped, as indicated in dotted outline on Figure 14, and as more clearly seen in Figure 15, each having a centrally upstanding hub portion J formed with a square bore K by which the weight is slidably' guided on the square torque rod E for radial movement thereon. At the outer extremity of each torque rod there is secured a shouldered nut L, the extreme end of the rod being threaded to receivethe nut. And

interposed between the nut L and the transverse end wall of the cup-shaped weight H there is provided' a coil spring M which normally holds the weight seated against the block D, "as shown in Figure 14, and tends to yieldingly oppose its radial movement outward in response to centrifugal force when the propeller revolves.

In order that the propeller blades shall be equally adjusted at all times, they are shown inter-connected by bevel gears P secured to the root end of each propeller blade inside the hub housing A and meshing with bevel pinions Q and R, which are loosely mounted upon the drive shaft 0.

Referring to Figures 3, 4 and 5, it should be understood that the arrow X in each instance'indicates the direction of rotation of the propeller. In Figure 3 the angle a at which the propeller blade II is shown adjusted, represents the initial position of the blade when at rest. On Figure 4 the angle b indicates the range of adjustment through which the blade may be shifted as the speed increases, the limiting angle shown as approximately 45 degrees corresponding to optimum pitch for full efiiciency. Any further movement of the governor weights caused by an increase in the centrifugal force acting upon them, such increase being, in turn, caused by added velocity of rotation of the propeller, will i into the angular range 5, which is to be considered as the maximum or over-revving setting of the propeller blades at which they offer paddle-wheel resistance, so that the propeller becomes a governor for holding the engine to its maximum intended speed.

In both forms of the invention illustrated herein the pitch of the helical features which intend to shift the blades l indicated at c in Figure terconnect the weights and the hollow shanks of the propeller blades is such that the wind resistance against the blades cannot turn them; in other words, the helical drive between the weights and the blades is irreversible. Thus the blades are held firmly at all positions of adjustment.

I claim:

1. In a variable pitch propeller, a hub and a plurality of blades carried thereby, each blade having a closed hollow shank mounted in the hub for rotation about its own axis, weights guided for movement respectively within said hollow shanks in response to centrifugal force when the propeller revolves, said weights and the inner surfaces of the hollow shanks having inter-engaging helical features, the weights being restrained against rotation whereby the movement of the weights along the shank axes tends to cause'rotative adjustment of the propeller blades, a crank plate journaled within the hub, and substantially straight links connecting said crank plate with said weights respectively to insure equal and simultaneous movements of the weights along the respectiveaxes of the blade propeller revolves, each of ment of the blades, and a torsion spring yieldingly connecting the plate to the hub and opposing rotation of the plate in response to the action of centrifugal force on said weights.

2. In the combination defined in claim 1, pivotal meansv connecting one end of each of said links to the crank plate and pivotal means connecting the other endof each link to one of the weights, the link and said connections serving as the means for restraining the weight against rotation "about the axis of the propeller blade shank.

3. In a .variable pitch propeller, a. hub and a plurality of blades carried thereby, each blade having a hollow shank mounted in the hub for rotation about its own axis, a weight guided for movement within said hollow shank and along its axis in response to centrifugal force when the said hollow shanks having a gear rigidly secured to its inner end within the hub, pinions inter-meshing with said gears and connecting them for simultaneous and equal rotation, each of the weights and the inner surface of the shank in which it moves having inter-engaging helical features, and means extending from the hub and restraining the weight against rotation whereby its movement along the axis of the shank serves-to cause rotative adjustment of the propeller blade, together with separate spring means associated with each of said pinions and yieldingly resisting rotation thereof to prevent back-lash in the gear connections when the blade shanks are rotated.

4; In a variable pitch propeller, a shaft, a hub mounted on said shaft and a plurality of blades carried by the hub, each blade having a hollow shank mounted in the hub for rotation about its own axis, a weight guided for movement within said hollow shank and along .its axis in response to centrifugal force when the propeller revolves, means whereby such centrifugally induced movement of the weight produces rotative adjustment of the shank of the blade in which it travels, a plate rotatably mounted within the hub connected to,the several weights in the blade shanks for rotation in response to their movements within said shanks, and a spring coiled about the the adjust- 75 tively to said plate and said hub to resist rotation of the plate and movement of-the weights outwardly within the shanks of theblades and serving to retract the weights inwardly as the speed of revolution of the propeller is reduced.

5; In the combination defined in claim 4, means for adjusting the initial tension of said spring at will and accessible from the outside of the hub.

6. In a variable pitch propeller, a hub and a plurality of blades carried thereby, each blade having a hollow shank mounted in the hub for rotation about its own axis, and a weight guided for movement within said hollow shank and along its axis in response to centrifugal force when the propeller revolves, said weight and the extenda simultaneous rotative adjustments of the'propeller blades, spring means opposing the move-.

hub, a shaft to which said hub is secured, said hub including a plurality of blade bearings, blades having hollow shanks rotatably mounted in said bearings respectively, a weight guided in each shank for radial movement therein in response to centrifugal force duringrevolution of the propeller, said weights and the inner surfaces of said shanks having inter-engaging helical featuresa rotatably mounted crank plate coaxial with the shaft, links connecting said crank plate to the weights respectively, said weights being restrained against rotation about the axes of the i respective blade shanks whereby their radialmovement causes rotation of the shanks and their associated blades, and a spring coiled about the axis of said shaft having one end connected to said crank plate and the other end connected with said hub for yieldingly restricting rotation of the crank plate and corresponding movement of the weights upwardlywithin the shanks of the blades and serving to retract said weights in-' wardly as the speed of revolution of the propeller is reduced.

PAUL J. GATHMIANN.

CERTIFICATE OF coRREcTIo1 7 Patent No. 2,257,050. April 1,

PAUL J. 'GATHMANN.

It is, hereby certified that error appears in the above numbered patent requiring correction as follows: In the drawing, strike out sheets 1, '2, and L and insert instead the following and that the said Letters Patent should be read with this correction therein that the same may .conform to the-record of the case in the Patent Office- Signed and sealed this 11th day of November, A. D. 19141.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

P 1 P. J. GATHMANN AERQNAUTICAL PROPELLER Filegi'J'une 14, 1938 5 Sheets -Shpet l INVENTORI.

-- ai/zmalzn,

ATTORNEY.

April 1, 1941. P. J. GATHMANN AEBOHA-UTICAL PRO PELLER Filed June 14, 1938 5 Sheets-Sheet 2 ORNEY April 1941- P. J. GATHMANN 2. 37.030

AERONAUTICAL menu. 7

5 Sheets-Sheet 4 mvsmm. BY P Z J 6575722017? v S a:

' ATTORNEY.

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