US2241008A - Variable pitch propeller - Google Patents

Description

y 1941- R. TURNA I 2,241,008

VARIABLE PITCH PROPELLER Filed Jan. 24, 1939 2 Sheets-Sheet l INVENTOR Ru '0 w A N R U T R VARIABLE PITCH PROPELLER Filed Jan. 24, 1939 2 Sheets-Sheet 2 lNVENTOR Rudo/ rna Patented May 6, 1941 2,241,008 VARIABLE rrron PROPELLER couver, British Columbia,

Rudolph Turna, Van Ca nada Application January 24, 1939, Serial No. 252,662

3 Claims.

This invention relates to an improved variable pitch propeller for aeroplanes.

An object of the present invention is the provision of a propeller including means operable from within the aeroplane for altering the pitch of the blades thereof.

Another object is the provision of means for retaining the blades of a propeller at any desired pitch as it is rotated.

Another object is the provision of very simple and yet effective means for altering the pitch of propeller blades.

A further object is the provision of a variable pitch propeller including means for preventing the pitch altering means from being twisted out of shape as the propeller is rotated.

It is desirable to be able to alter the pitch of the blades of a propeller when an aeroplane is taking off or landing. There are numerousvariable pitch propellers known but these are not very practical since they are extremely complicated and, therefore, expensive. The expense, however, is not the chief drawback but the fact that the numerous parts of these complicated devices will not stand up under the great strain to which they are subjected is the main reason for their failure.

This invention overcomes these objections by providing extremely simple means for varying the pitch of propeller blades. This means consists of very few parts and there are no gears to jam or worm gears or other threaded parts to strip or jam. This means for varying the pitch also includes means for preventing the various working parts from twisting in relation to each other.

due to the constant rotary motion of the propeller and particularly to sudden changes in the speed of rotation.

of the propeller illustrated in Figure 1, showing the pitch varying means and an aeroplane en- .gine, with one cylinder removed for the sake of clarity,

Figure 3 is a section taken on the line 3-3 of Figure 2, omitting the propeller blades,

Figure 4 is a side-elevation, partly in section, of an alternative form of the invention and illustrating a two bladed propeller,

Figure 5 is a vertical section taken on the line 5-5 of Figure 4 with the propeller blades shown in elevation,

Figure 6 is a plan view of the hub illustrated in Figure 4, the upper blade of which is shown in section,

Figure 7 is a vertical section taken on the line 1-1 of Figure 4,

Figure 8 is a side elevation, partly in section,

I of a two bladed propeller with the variable pitch means illustrated in Figures 1 and 2, and

Figure 9 is a plan view of the hub illustrated in Figure 8, the upper blade of which is shown in section.

Referring more particularly to the drawings.

. A is a variable pitch propeller adapted to be mounted on the crank shaft of an engine B of any type, the engine illustrated being of the radial type.

In Figures 1, 2 and 3 the propeller A consists of a hollow hub l0 which is open'at its forward end, as at H, and over which a hub cap I2 is removably held by bolts l3. The hub II] has formed therewith or secured thereto in any suitable manner a hollow extension M, which extension extends rearwardly of the hub and is adapted to be mounted on the crank shaft (not shown) of the engine B in any desired manner,

The present invention consists essentially of a propeller mounted on the crank shaft of an aeroplane comprising a hub, a plurality of blades pivotally mounted on the hub, a crank mounted adjacent the inner'end of each blade, a collar slidably mounted adjacent the hub, means connecting the collar to the cranks, means for causing the collar to .rotate with the hub, and means for moving the collar towards and away from the hub to turn the cranks and rotate the blades in relation the following specification and illustrated in the to-the hub, as more fully described in any suitable manner.

such as by being'screwed thereon and held in place by a pin 15 extending through the extension and the crank shaft.

A plurality of propeller blades are pivotally mounted on the hub In. Each propeller blade preferably consists v of a blade l6 removably' mounted on a stub shaft ll which is l'ournalled in the hub and has a crank or crank disc l8 formed on its inner end within the hub. The blades l6 are mounted on the stub shafts II in One way of doing this is to form a socket 20 on the inner end of each blade into which the outer end of the stub shaft fits and having a bolt or pin 2| extending through the socket and the shaft;

A collar 22 slidably mounted on the extension I4, is provided with a plurality oftongues or keys 23 (see Fig. 7) adapted to fit into splines 40 and M secured together by'bolts 42.

or grooves 24 formed in the extension. The collar 22 is provided with a peripheral groove 25 into which a yoke 26 extends. This yoke is formed with an internally threaded boss 2? and is carried by a threaded actuating rod 23, said. rod extending back into the aeroplane (not shown) and having on its inner end a hand wheel 30. The rod is supported in any suitable manner, such as by bearings 3| mounted on the engine B. Each propeller blade is connected to the collar 22 by a. connecting rod 32, one end of which is pivotally secured to the crank disc l8 adjacent the periphery thereof, as at 33, while the other end is pivotally connected to the collar by a pin 3%. Each connecting rod extends freely through an orifice 35 in the rear of .the hub Hi. There are four. propeller blades illustrated in Figure 1 and two in Figure 8 but it is to be understood that there may be any desired number of such blades.

Figures 4., 5 and 6 illustrate an alternative form. of the invention. These figures show a two bladed propeller but there may be as many blades as desired. In this alternative, the hub of the propeller consists of two identical sections Each of these sections is formed with two or more recesses 43, the number depending upon the number of blades, having at their inner ends enlarged portions 46. When the sections Ml and H are bolted together their recesses 43 combine to make circular recesses adapted to receive the stub shafts ll of the propeller blades while the enlarged portions 44 accommodate the discs l8. In this case, the extension [4 is preferably formed with the section 40, as shown, or it may, if desired, be bolted to said section. In either case, the extension extends rearwardly through the section 4!. Cranks 41 are formed with or mounted upon the propeller blades adjacent their inner ends but outside the hub. The outer ends of the connecting rods 32 are pivotally connected to the cranks 41 at 48.

When it is desired to alter the pitch of the propeller blades, the hand wheel 30 is rotated in one direction or the other according to whether the pitch is to be increased or decreased. This turns the rod 28 which causes the yoke 26 and, consequently, the collar to move toward or away from the hub of the propeller. This collar, owing to its connection through the connecting rods 32 to the cranks mounted adjacent the inner ends of the propeller blades,'causes said blades to pivot about the stub shafts I! to alter the pitch thereof.

The tongues 23 and the splines 24 ensure the collar. 22 rotating with the propeller, thus eliminating any possibility of the connecting rods being twisted out of shape owing to the rotation of the propeller or to sudden changes of speed of said rotation. Access may be gained to the interior of the hub merely by removing the hub cap l2. Each blade lfi may be removed by withdrawing the pin or bolt 2|.

From the above, it will readily be seen that very simple and effective means have been provided for varying the pitch of a propeller as it rotates, which will retain the blades'in the desired setting and which will not be likely to go out of working order.

Various modifications may 1 2. in this invention without departing iron: the spirit thereof or the scope of the claims, and therefore the exact forms shown are to be taken as illustrative only and not in a limiting sense, and it is desired that only such limitations shall be placed thereon as are disclosed in the prior art or are set forth in the accompanying claims.

What I claim as my invention is:

1. A variable pitch propeller adapted to be mounted on the crank shaft of an aeroplane engine, comprising a hub, a plurality of blades pivotally mounted on the hub, a crank disc mounted at the inner end of each blade, a pin eccentrically mounted on the outer face of each disc, an extension extending rearwardly from the hub, said extension being splined, a collar slidably mounted on the extension having ton es fitting into the splines, a connecting rod pivotally connected to each crank disc pin at one end and to the collar at the other end, and means for moving the collar toward and away y from the hub to turn the cranks and the blades pivotally connected to each crank disc pin at one end and to the collar at the other end, said rods extending freely through orifices in the rearward wall of the hub, and means for moving the collar toward and away from the hub to turn the cranks and the blades in relation to the hub.

3. A variable pitch propeller adapted to be mounted on the crank shaft of an aeroplane engine, comprising a hub, a plurality of stub shafts journalled in the hub, a blade'removably mounted on each shaft, a crank disc mounted at the inner end of each shaft, a pin eccentrically mounted on the outer face of each disc, an extension extending rearwardly from the hub, said extension being splined, a collar slidalbly mounted on the extension having tongues fitting into the splines, a connecting rod pivotally connected to each crank disc pin at one end and to the collar at the other end, and means for moving the collar toward and away from the hub to flurgi the cranks and the blades in relation to the RUDOLPH TURNA.

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