US2367230A - Controllable pitch-change mechanism for dual rotation propellers - Google Patents

Description

Jan. 16', 1945. 'H M MCCOY 2,367,230

CONTROLLABLE PITCH-CHANGE MECHANISM FOR DUAL ROTATION PROPELLERS- Filed Dec. 9. 1943 INVENTOR Hon/Ago /7. MC 601 Patented Jan. 16, 1945 CONTROLLABLE LERS aasy zao PITCH-CHANGE MECHA- .NISM FOR DUAL. ROTATION PROPEL- 7 "Howard M. McCoy, Fairfield, Ohio Application December 9,1943, Serial No. 513,611

9 Claims. (c1. 170135.6)

(Granted under the act of March 3,1883, as amended April 30, 192 38; 370 O. G. 757) The invention described herein may be manufacturedv and used by or for the Government for governmental purposes,. without the payment to me of any royalty thereon. v

This invention relates to dual rotation pro pellers and more particularly to mechanism for controlling the pitch of the blades of both of the propellers simultaneously.

' By dual rotation is commonly meant a pair of I oppositely rotating propellers operating in close tandem, mounted on'concentric shafts and rotating at equal speeds. r

Mechanism for accomplishing this purpose as heretofore proposed is complicated and costly, and D it is. therefore an objectof this invention to provide a device which will have less parts and therefore be of lighter weight and greater simplicity.

- the worm 24 is rotated to' turn the blades 22 in a Ithas been found that, in a device of this char- I acter, itis advantageous, in order to cancel propeller. torque effects, to have an arbitrary and variable difierential pitch setting between the front and rear propeller blades. For pitch, settings used at take-off and low forward velocities there should be but very little if any-difference.

At high forward velocities there'should be sev-.

eral degrees difference with the setting ,of the rear propeller lower than that of the front. It is desirable to' have the pitch differential vary directly between the small differential at low velocities to the large differential at high velocities.

Fig. l is a longitudinal axial section through a dual rotation. propeller constructed according to subject invention, the view being more or less schematic.

Figs. 2 and 3 are transverse sections taken at 2-2 and 3 --3, showing the arrangement of the" gearing.

Like reference characters refer to like parts throughout the drawing.

The dual rotation propeller, which is selected as an illustrative embodiment of this invention-,-

comprises an outboard or front propeller hub l0, whichis fast on a shaft II and is rotatable clockwise, as indicated by the arrow l2, andan inboard, or rear propeller hub I4, rotatable on the sleeve portion of the hub l4 anticlockwise, as indicated by the arrow l6. I Y When the terms clockwise or "anticlockwise" are hereinafter employed they shall be intended to mean clockwise or anticlockwise when viewed from right to left in the drawing. The relatively heavy gearing required for connecting the front and rear hubs to each other and tothe engine,

- for opposite rotation, isvnot shown.

ID, the blades l8 are rotatable about their axes by the worm 26,

while similar blades 22 are carried on the rear hub Supported onthe front hub l4 and are rotatable about their axes .by the worm 24. Worms 20 and 24, in the instant embodiment, are both right hand.

A relatively light weight gear-set 26, which, for convenience in description, maybe referred-to as the dual rotation gear set,'is provided for drivably connecting the worms 2!] and 24 to each other, this gearing being so arranged that when pitch increasing direction, as indicated by the arrow v28 or 30, the worm 20 will be rotated to turn the blades It in a-pitch increasing direction, as indicated by the arrow 32 or 34, the same result being achieved whether the hubs l0 and I4 are stationaryor are in a state of opposite rotation about the axis of the 'hubs l0 and I4.

The gear-set 26 includes a cylindrical member 36 which is freely rotatable on a sleeve portion 38 of the rear hub l4, and. comprises integrally an external gear 46 and an internal gear 42, a second internal gear 44 integral with the rear .hub l4, a pair of drivably joined sun gears 46 and 41 freely rotatable on a portion of the front. hub In, two

planet pinions 48 and 50 meshing respectively I with the internal gears 42 and 44 and the drivably connected sunfgears 46- and 41, and two planet pinion carriers 52 and 54 for respectively rotating the planet pinions 48 and '50 on their axes while revolving them around the sun gears 46 and 41 and within the ring gears 42 and 44. 7 Carrier 52 is fast on-a portion of the hub III while carrier 54 is freely rotatable thereon. Carrier 64 has an external gear 56 integral. Pinions 58 and 60 drivably connect the gear-set 26 to the worms 2!) and 24, respectively, whereby rotation of the worm 24 rotates the worm 2D equally but oppositely whether the hubs l0 and I4 are stationary or are rotating oppositely. Where it is desirable 1 that pitch change of the rear propeller blades 22, through a given angle, cause. pitch change of the front propeller blades l8 through a slightly greater angle, this may be accomplished by changing the ratios between certain of the gears,

for instance, by adding one or more teeth to the gear 56 and subtracting one or more from the pinv ion 58. In'such case the gears should be set so that both propellers come to zero pitch at the same time, whereby the higher the pitch the more pitch difference will be had between the two propellers.

Gears 5 and 55 are part of a gear mechanism for rotating the worm 24 of the rear propeller for initiating pitch change, but since this mechanism forms no part of subject invention, it is not herein further shown or described. The system herein shown for connecting the two parts of a dual rotation propeller for unitary blade adjustment is shown and described, but not claimed, in my copending application Serial No. 511,935, filed November 27, 1943.

The operation of the mechanism shown and described is substantially as follows:

Let it be assumed that the front hub I0 is rotating clockwise and the rear hub l4 anticlockwise, both at'the same speed, and that, for the time being, no pitch change is taking place.

Since there is no pitch change taking place, the internal gears 42 and 44 both rotate anticlockwise at the same speed, and both carriers 52 and 54 rotate clockwise at the same speed, whereby the pinions 48 and 50 merely rotate anticlockwise on their axes at the same speed and rotate the sun gears 46 and 41 clockwise faster than the hub ID.

If the worm 24 is now rotated one turn clockwise to increase the pitch of the blade 22, the internal gear 42 will gain part of an anti-clockwise turn on the internal gear 44. This part turn gain of gear 42 causes the pinion 48 to gain approximately one anticlockwise turn on the turns it would normally have made when no pitch change was taking place.

Since the carrier 52 has a fixed one to one opposite rotation with respect to gear 44,the one turn anticlockwise gain of the pinion 48 causes a gain over the normal number of clockwise turns of the sun gear 46, which in turn causes the carrier 54 to gain part of a. turn over its normal clockwise turns, whereby the pinion 58 is rotated anticlockwise approximately one turn with respect to the hub [0, which increases the pitch of the propeller l8.

A similar analysis of the directions of rotation will show that rotation of the worm 24 anticlockwise to decrease the pitch of the blade 22 will rotate theworm 20 clockwise to decrease the pitch of the blades [8, whether the propellers are then rotating or are stationary.

I claim:

1. In an aircraft propeller mechanism having two close-coupled, coaxial, tandem, contrarotating propeller hubs, one front hub and one rear hub, with a plurality of propeller blades in each hub having their roots rotatable in bearings in said hubs, mechanism for drivably connecting said roots, whereby rotation of the roots of one propeller in one direction rotates the roots of the other propeller in the other direction, said mechanism comprising, in combination, a front worm wheel on a front propeller-blade shank, a rear worm wheel on a rear propeller-blade shank. a front worm in mesh with said front worm wheel, a rear worm in mesh with said rear worm wheel. a front-worm shaft, a rear-worm shaft, front and rear worm shaft pinions on the front and rear worm shafts respectively, a planet pinion carrier freely rotatable on the front hub, an external gear fast on said carrier and in mesh with the front worm shaft pinion, a second planet pinion carrier fast on the front hub, front and rear planet pinions on the first and second said planet pin ion carriers, respectively, a sun gear freely r0- tatable on said front hub and having a face width sufficient to mesh with both said planet pinions, an internally toothed gear fast on said rear hub and in mesh with the front planet pinion, a second internally toothed gear freely rotatable on said rear hub and in mesh with the said second planet pinion, a second external gear fast on said second internal gear and in mesh with said rear worm shaft pinion, and means to rotate said rear worm shaft.

2. In an aircraft propeller mechanism having two close-coupled, coaxial, contrarotating propeller hubs, one front hub and one rear hub, With a plurality of propeller blades in each hub, said blades having blade shanks rotatable in bearings in said hubs, an improved mechanism for drivably connecting said blade shanks, whereby rotation of the :blade shanks of one propeller in one direction is coincident with rotation of the blade shanks of the other propeller in the other direction, said mechanism comprising, in combination, a planet pinion carrier freely rotatable on the front hub, an external gear fast on said carrier, a second planet pinion carrier fast on the front hub, front and rear planet pinions on the first and second said planet pinion carriers respectively, a sun gear freely rotatable on said front hub and having a face width sufficient to mesh with both said planet pinions, an internally toothed gear fast on said rear hub'and in mesh with the front planet pinion, a second internally toothed gear freely rotatable on said rear hub and in mesh with the said rear planet pinion, a second external gear fast on said second internal gear,,front speed reducing gearing connecting the first said external gear to the blade shanks of the front hub, rear speed reducing gearing connecting the second said external gear to the blade shanks of the rear hub, and means to impart rotation to the rear speed reducing gearing.

3. In an aircraft propeller mechanism having two coaxial, tandem, contrarctatlng propeller hubs, one front hub and one rear hub, with a plurality of propeller blades in each hub said blades having their blade shanks rotatable in hearings in said hubs, an improved mechanism for drivably connecting said blade shanks, whereby rotation of the blade shanks of one propeller in one direction is coincident with rotation of the blade shanks of the other propeller in the other direction, said mechanism comprising, in com bination, a planet pinion carrier freely rotatable on the front hub, an external gear fast on said carrier, a second planet pinion carrier fast on the fronthub, front and rear planet pinions on the first and second said planet pinion carriers, respectively, a sun gear freely rotatable on said front hub and having teeth adapted to mesh with both said planet pinions. an internally toothed gear fast on said rear hub and in mesh with the front planet pinion, a second internally toothed gear freely rotatable on said rear hub and in mesh with the said rear planet pinion, a second external gear fast on said second internal gear, front gearing connecting the first said external gear to the blade shanks of the front hub, rear gearing connecting the second said external gear to the bladeshanks of the rear hub, and means including a portion of said rear gearing to impart rotation to the second said external gear.

4. In an aircraft mechanism having two close: coupled, contra-rotating propeller hubs, one front hub and on rear hub, with a plurality of propeller blades in each hub having blade shanks,

rotatable in bearings in said hubs, an improved mechanism for drivably connecting said blade shanks whereby causing rotation of the blade shanks of one propeller in one direction causes rotation of the blade shanks of the other propeller in the other direction, said mechanism comprising, in combination, a planet pinion carrier freely rotatable on the front hub, a second planet pinion carrier fast on the front hub,

front and rear planet pinions on the first and toothed gear freely rotatable with respect to said rear hub and in mesh with the said rear planet pinion, gearing connecting'the first said planet pinion carrier to the blade shanks of the front hub, a power receiving shaft, and gearing connecting the said second internally toothed gear to the blade shanks of the rear hub and to the power receiving shaft.

5. In an aircraft propeller mechanism having two close-coupled contrarotating propeller hubs,

, one front hub and one rear. hub, with a plurality of propeller blades in each hub having blade shanks rotatably supported by said hubs, an improved mechanism for drivably connecting said blade shanks, whereby rotation of the blade shanks of one propeller in one direction may not take place except upon rotation of the blade shanks of the other'propeller in the other direction, said mechanism comprising, in combination, a planet pinion carrier rotatable freely about the axis of said hubs, a coaxial planet pinion-carrier fast on said front hub, front and rear planet pinions on the firstand second said planet pinion carriers respectively, a sun gear element coaxial with said hubs and freely rotatable with respect thereto and having. teeth in mesh with both said planet pinions, an internal gear coaxial with and fast on said rear hub and in mesh with said front planet pinion, a second.

internal gear coaxial with and freely rotatable with respect to said hubs and in mesh with said rear planet pinion, rotation transmitting means connecting the first mentioned planet pinion car.- rier to the blade shanks of the front hub, a rotatable power input means and rotation transmitrespect thereto and having teeth in mesh with both said planet pinions, an internal gear coaxial with and fast on said rear hub and in mesh with said front planet pinion, a second internal gear coaxial with and freely rotatable with respect to said hubs and in mesh with said rear ting means connecting the said second internal gear to the blade shanks of the rear hub and to the rotatable power input means.

6. In a dual rotation propeller mechanism having close-coupled, coaxial, propeller hubs,

the axis of said hubs, a coaxial rear planet pinion carrier fast on said front hub, front and rear planet pinions on the front and rear. planet pinion carriers respectively, a sun gear element coaxialwith said hubs and freely rotatable with planet pinion, rotation transmitting means connecting the said front planet pinion carrier to the blade shanks of the front hub, rotation transmitting means connecting the said second internal gear to the blade shanks of the rear hub, and means to impart rotation to one of said rotation transmitting means.

7. In a dual rotation propeller mechanism having one front hub and one rear hub with a plurality of propeller blades in each hub having blade shanks rotatably supported by said hubs, an improved mechanism for so connecting said blade shanks to the same source of rotation that rotation of the blade shanks of one propeller in one direction is coincident with rotation of the blade shanks of the other propeller in the other direction, said mechanism comprising, in combination, a front planet pinion carrier rotatable freely about the axis of said hubs, a coaxial rear planet pinion carrier fast on said front hub, front and rear planet pinions on the front and rear planet pinion carriers respectively, a sun gear unit coaxial with said hubs and freely rotatable with respect thereto and having teeth in mesh with both said planet pinions, an internal gear fast on said rear hub and in mesh with said front planet pinion, a second internal gear freely rotatable relative to said hubs and in mesh with said rear planet pinion, means drivably connecting the said front planet pinion carrier tothe blade shanks of the front hub, and means drivably connecting the said second internal gear tothe blade shanks of the rear hub. 8. For a dual rotation propeller having one front and one rear hub with a plurality of propeller blades in each hub having blade shanks rotatably supported by said hubs, an improved gear mechanism for drivably connecting said blade shanks for coincident rotation, said, gear mechanism comprising, in combination, a first planet pinion carrierv rotatable freely about the axis of said hubs, a coaxial second planet pinion carrier fast on one of said hubs, first and second planet pinions on the first and second planet pinions carriers respectively, a sun gear coaxial with said hubs and freely rotatable relative thereto and having teeth in mesh with both said planet pinions, an internal gear coaxial with and fast on one of said hubs and in mesh with said first planet pinion, a second internal gear coaxial with and freely rotatable relative to said hubs and in mesh with said second planet pinion,

means drivably connecting the said first planet ment, the front hub will rotate through a slightly greater angular movement.

HOWARD M. McCOY.

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