US1982170A - Variable pitch propeller - Google Patents

Description

1934- R. P. LANSING VARIABLE PITCH PROPELLER Filed Jan. 22, 1932 2 Sheets-Sheet l INVENTOR Payman Lansing ATTQRN EY.

Nov. 27, 1934. R. P. LANSING 1,982,170

VARIABLE PITCH PROPELLER Filed Jan. 22,1952 '2 Sheets-Sheet 2 VIII/II/I/I/II/II/IIIIIIIII/JII/IA u z; "s wig I I Q3525 [am 75mg 6 BY ATTORNEY.

Patented Nov. 27, 1934 UNITED STATES PAT 1.982.110 VARIABLE rrron momma NewJersey Application January 22, 1932, Serial No. 588,193

' 17 Claims.

This invention relates to propellers and more particularly to a propeller-of the type wherein the pitch of the blades is'variable during rotation thereof. A

It has been proposed, heretofore, to provide. variable pitch propellers which are so constituted that the propeller hub is caused to move axially of the engine shaft in response to the thrust of the blades during the rotation thereof in order to vary the pitch of theJatter. In certain instances,

the reduction of the extent of this axial movement might be desirable in effecting a reduction of the low amplitude, high frequency pitch variations which might be present in this type of propeller. Minimizing such hub travel would also effect a reduction in overhang, consequently permitting a material decrease in the weight of the driving shaft accompanied by an increase in the strength of same, each of these factors being a primary objective in aircraft design.

Accordingly, one of the objects of the present invention is to provide a novel variable pitch propeller which is so constructed as to secure the advantages mentioned above. Y

Another object of this invention is to provide in a variable pitch propeller of the above character, novel means for minimizing the axial movement of the hub with respect to the driving shaft without impairing any of the advantages and novel results secured by such a propeller.

Still another object is to provide a variable pitch propeller embodying means for automatic'ally varying the pitch of the propeller blades during operation, such means comprising a novel motion multiplying device interposed between the hub and the blades whereby a very slight motion of the hub is translated into a relatively large angular motion of the blades.

A further object is to provide in a propeller of the variable pitch type a novel, positive-acting hydraulic or fluid pressure actuating means for changing the pitch of the blades during operation.

A still further object is to provide a novel propeller assembly in which the pitch of the propeller blades is automatically altered with variation in flight conditionsto such an extent as to cause the propeller to operate at'its maximum emciency at alltimes.

,The above and further objects and novel features of this invention will more fully appear from the following description when taken in connection with the accompanying drawings. It 'is to be expressly understood, however, that the drawings are for purposes of illustration only/ and are not designed as a definition of the limits of the inven- 'peller embo ENT' oF iic tion, reference being had for this purpose to the 1 I appended claims.

In the drawings, wherein like reference charac f ters refer to like parts throughout the several views:

Fig. 1 is a side view, partly in section, of a progthe present invention Fig. 2 is an axial view partly in sect-ion, takeri along line 2-2 of Fig. l and Fig. 3;

Fig. 3 is a transverse sectional viewpn line 33 of Fig. 1;

Fig. 4 is-a view similar to Fig. 1, partly in sec-,' tion, showing the hub at full thrust; and I Fig. 5 is a fragmental view similar to Fig. 2

disclosing a modification of the present invention.

A propeller embodying the present invention comprises a plurality of propeller blades 6 adapted to be driven by a driving shaft 7, which in the. illustrated installation'is an engine crankshaft or extension thereof, and the pitch of the blades is automatically a' ustable during operation in response to the thrust thereof by means which will be described hereafter in detail.

For the purpose of drivably connecting the propeller blades 6 to the driving shaft 7, a main hub forging-8 is provided, said hub, forging having a plurality of axially aligned sleeves or sockets 9, adapted to rotatably receive the root end of the blades. Interposed between the hub and driving shaft is a driving member or block 10 which is drivably connected in any suitable manner as by splines with the shaft '7, and maintained in proper relatio'n with respect to said shaft by means of split front and rear cones 11 and 12, respectively, Fig. 2, which are adapted to be brought into firm engagement with said block by the provision of a threaded member or nut 13, threadedly received by the outer end of the driving shaft.

As shown, the hub 8 is drivably connected to the driving block and shaft so as to be axially movable in response to the thrust exerted by the blades during operation. Preferably, this drivingconnection is constituted in such a manner as to provide increased bearing surface without materially increasing the weight of the propeller. the formf'of the invention illustrated. such co ection comprises a plurality of rows of roller bearings 14 and 14a which are seated in longitudinally extending recesses 15 provided in the driving block 10, each of the rows'of bearings 14 and 140 being disposed on'either side of a key member or metal insert 15a extending longitudinally of the hub 8 and rigidly carried thereby; such construction effecting an efllcient driving connection between the hub and the driving block.

Positive means'are provided for varying the pitch of the blades during such thrust responsive movement of the 1311b, and preferably such means include hydraulically operated differen-- tial pistons and suitable linkages interposed between the hub and the blades. As shown, Figs. 1 and 2, such means comprise an annular cylin'-,

'der 16, formed by the annular space between an inwardly extending annular projection 16a integral with an axial projection on the hub, and a piston 17 adapted to be threadedly received by theouterportion of driving block 10, said piston being fitted with peripheral packing and 2 having a radius substantially equal to the inner diameter of cylinder 16. Said cylinder is in direct communication through passages 18 with cylinders 19, which are preferably formed integral with, but which may be otherwise rigidly attached to the hub, the last named cylinders carrying pistons 20. Piston rods 21 secured to the pistons 20 in any suitable manner are suitably connected as through links 22 to a lever 23, one end of which is formed as a toothed segment 23a, in continuous engagement with a ring gear 24 secured in any suitable manner to the root end of each blade. Levers 23 are fulcrumedon pins 25 held by brackets26 which in turn are rigidly fixed to the hub sockets. Each hub socket is preferably provided with a suitable slot in order, to permit engagement between the segment 23a and the ring gear 24'. Cylinders 16 and 19 and passages 18 are completely filled with asuitable liquid, such as oil for example, so that during slight relative movement between the hub and the driving shaft there will be a considerably greater linear movement of the small pistons 20 which in turn results in-the movement of levers 23 effecting a change in the pitch of each propeller blade. There is thus provided a motion multiplying means .for converting slight axial movements of the hub into relatively large angular movements of the blades.

In order to rotatably secure each blade in its respective socket, a split sleeve 27 encircles the blade root end and is secured thereon by means of the ring gearl24 and a bearing race to be further described; these parts being firmly maintained in proper position within the hub socket- 9 by a member 28 threadedly received by the outer portion of the socket and suitably locked thereto. Interposed between the sleeve 2'7 and member 28 is a ball thrust bearing 29, while a suitable ball bearing 30 is confined between the inner-portion of the hubsocket and the skirted portion of the ring gear 24 in order to permit efficient and substantially frictionless rotation of the latter with respect to the former.

Preferably, means are provided for yieldably resisting axial movement of the hub with respect to the shaft, and in the form shown, Figs. 1 and 4, such means are'constituted by a plurality of resilient members such as springs 31 which may be housed within the cylinders 19. It will be apparent that the expansion of springs 31 is normally effective to maintain the hub in such position relative to the driving shaft, that the pitch of the blades will be at a minimum, as indicated by the blade sectionfia, Fig. l, but that during operation, the hub will be moved toward the right, as viewed in said figure, in response to thethrust of the'propellerblades, to compress the springs 31 through the medium, of the hydraulic motion multiplying device heretofore de-.

scribed, the cooperation between ring gear 24 and segment 23a being operable during such movement to increase the' pitch of the blades. Preferably, the springs 31 are adjusted in such a manner as to be effective, during operation of the propeller, to arrest the movement of the hub in such a position that the resultant pitch will be substantially proportional to the thrust exerted by blades 6. r v

Means are provided to insure that the pro-'- peller blades are' at all times operating at an equal angle of incidence, such means including,

as shown, a cylindrical sleeve 32, Fig. 2, adapted for axial movement relative to shaft '7 through mechanisms hereinafter described. Preferably, such axial movement is frictionless upon cone 12 by virtue of ball bearings 33 interposed betweengrooved rings 34 and 35 pressed on cone 12 and sleeve 32 respectively. The said ball bearings are contained in grooved ring 34 while the outerring 35 overlaps to the extent of the required amount of axial movement of sleeve 32 over cone 12. Rigidly secured to laterally extending ears 36 formed integrally with said sleeve and positioned diametrically opposite, is a pair of rack members 37 and 38 which are adapted to cooperate with ring gears 24, the said rack members extending through suitable slots in the hub sockets andbeing guided during movement relative to the hub as by means of brackets 39 fixedly securely to the hub. It is apparent from the foregoing that by virtue of such interlocking device interposed between the root ends of the blades, any change of pitch angle on the part of one blade will effect an equal angular change in the other blade. i

In large high speed propellers the blade thrust reaches a relatively high value and it may become desirable in such propellers to provide additional resilient means for yieldingly resisting the thrust 115 action of the blades. Such means may be provided by either or bothof the two methods shown in Fig. 5. Such means includes helical spring 40, within the cylinder 16 tending to hold the hub tothe left against the thrust action of the blades. If it is desired to reduce the length of cylinder 16 to a minimum, means for yieldingly resisting the forward movement of the hub may be/ constituted by a plurality 'of resilient members, such as for example, coil springs 41, concentrically arranged about the shaft, and interposed between an annular plate 42 rigidly attached to the hub, and an annular member 43 secured in any suitableman nerto the forwardly extending portion of the driving block 10.

For the purpose of substantially neutralizing the net effect of torsion on the propeller blades, which tends to reduce'the pitch of the blades, the ring gears 24 are only partially complete with teeth for cooperation with segments 23a and racks 3'1 and 38 through the desired arc of pitch variation, and are partially cut away, the completedportions in effect constituting counter-weights or enlargements on diametrically opposite sides as indicated in Figs. 1 and 4, the operation of which is to impart a twisting or turning movement to the blades, in accordance with the centrifugal force developed during rotation, to materially offset the effect of torsion'on the blades. It 'is seen that a'centrifugally responsive means is thus provided, tending during operation to increase the I pitch of the blades and thus opposing the effects of torsion which tends to turn the blades into a. zero-pitch condition.

There is thus provided a novel propeller of the ner.

By employing means responsive to the thrust variable pitch type wherein the pitch of the blades is altered in a simple, emcient and positive manof the propeller for varying the pitch of the blades, substantially all of the variable forces acting on the blades during rotation thereof are included, whichresults in a propeller, the blades of which-automatically assume such positions as to yield a maximum thrust for every variable condition encountered during flight, the efficiency of such propeller for a given energy input being thus automatically maintained at a maximum at all times. The hydraulically operated pistons employed, not only provide for sufilcient vari-" ation' in the pitch of e the blades during relative slight axial movement of the hub relative to the-shaft, but also obviate the necessity of dash pots by acting in the capacity, as a secondary function, of preventing slight and rapid fluctuations of the pitch angle and hence noisy and inefiicient operationof the propeller.

While there has been shown and described only one form of the invention, it is to be expressly understood that the same is not limited thereto but may be embodied in various mechanical forms. For example, it is to be understood that the driving connection between the propeller hub and the driving member, and between the interlocking sleeve and the driving member may be constituted by other means than that illustrated. Various changes other than those mentioned above may also be made in the relative sizes, shapes and arrangement of the various compo- -nent parts of the invention without departing from the spirit thereof, as will be apparent to those skilled in the art. Reference will therefore be had to the appended claims for a definition of the limits of the-invention.

What is claimed is:

1. In combination. with a variable pitch pro peller, means for changing the pitch of the propeller blades including cylinders rigidly connected to the hub of said propeller, pistons operable therein, and a movable cylinder carried by said hub with a fixed piston therein, said last-named cylinder having communicating means with said first named cylinders.

2. A propeller comprising a blade, means for revolving said blade, and means responsive to the thrust exerted by said revolving blade and including hydraulically operated mechanism for changing the pitch of said blade.

3. A propeller comprising a plurality of blades, means for revolving said blades, and means responsive to the thrust of said blades for changing to pitch of said blades, said means including a motion multiplying hydraulically-operated linkage inter-connecting said first named means and said blades. v

4. Ina variable pitch propeller of the thrust actuated type wherein thepropeller hub is adaptactuated type wherein the propeller hub is;

adapted for movement longitudinally of a power shaft and wherein the blades are mounted for rotary movement within the hub, the combination with said blades of motion multiplying hydraulically-operated means operatively connected to said hub and 'blades for converting longitudinal movementof the hub into angular movement of said blades.

6. In a variable pitch propeller of the thrust actuated type wherein the hub is movable longitudinally of a power shaft, the combination with said hub of intercommunicating cylinders carried by id hub, a piston in each of saicl cylinders, and resilient means operatively cooperating with certain of said pistons and adapted to hold said hub in a predetermined position on the shaft when at rest.

7. In a variable pitch propeller of the thrust actuated type wherein the propeller hub is adapted for movement axially of a power shaft and wherein the blades are mounted for rotary movement within the hub. the combination with said huband blades of cylinders carried by said hub, a piston in each of said cylinder-sand transmission means for converting linear motion of said pistons to'angular motion of said blades.

8. In a variable pitch propeller of the thrust actuated type wherein the propeller hub is adapted for movement axially of a power shaft to which said hub is drlvably connected and wherein the blades are mounted for rotary movement within the hub, the combination with said hub and blades of motion multiplying hydraulically-operated means adapted to automatically vary the pitch of said blades, and resilient means, independent of said first named means, for holding saidhub in a predetermined position on the shaft when at rest. I

9-. In a variable pitch propeller of the thrust actuated type wherein the propeller hub is movable axially of a driving shaft, and wherein the blades are mounted for rotary movement within said hub, the combination with said propeller oi intercommuni-cating cylinders carried by said hub, a piston in each of said cylinders, said cylinders adapted to contain fluid transmission means between said pistons and interposed between certain of said pistons and the blades for effecting a change in the pitch of the latter during axial movement of said hub. 1

10. In a variable pitch propeller of the thrust actuatedtype wherein the hub is adapted for movement axially of a driving shaft, and wherein the blades are mounted for rotary movement within the hub, in combination with said blades of motion multiplying means operatively connected to said hub and blades 1 or converting axial movement of the hub into angular movement of said blades, and means independent of said first named means for interlocking said blades including cooperating rack members.

11. In combinaition, a variable pitch propeller, motion multiplying means for varying the pitch of the propeller blades, and means, independent of said first named means, for positively interlocking said blades.

12. In a variable pitch propeller of the thrust actuated type wherein the propeller hub is adapted for movement axially of apower shaft and wherein the blades are mounted for rotary movement within the hub, in combination with said blades of motion multiplying means for effecting a change in'the pitch angle of said blades, and means for interlocking said blades including rack members cooperating with said blades and rigidly connected bya sleeve member rotatable with the shaft and axially movable relative thereto.

13. In'a variable pitch propeller wherein the propeller hub is adapted for axial movement relative to a power shaft and wherein the blades are rotatably mounted, in combination with said blades of motion multiplying hydraulically operated means for varying the pitchv of said blades, and centriiugally responsive means for neutralizing the torsion on said blades.

14. A propeller comprising a blade, means for rotating said blade, 'means responsive to the thrust exerted -by said rotating blade and include ing hydraulically operated mechanism for chang- 'ing the pitch of said blade, and centrifug'ally-responsive means for neutralizing the torsion effect on said blade-.- v

' 15. In a variable pitch propeller having a shaft, a hub, a plurality of blades rotatably mounted'in said hub, said-hub and blades being longitudinally movable as --a unit with respect to theshat-tinresponsetothethmstoftheblad means for yielding'ly opposing said longitudinal movement, and fluid transmission means operable during such movement for simultaneously rotating the blades in the hub to vary their pitch.

16. In a variable pitch propeller having a shaft, a hub, a plxnali-ty of blades rotatably mounted in said hub, said hub and blades being longitudinally movable as a unit with respect to the shaft, resilient means yieldingly opposing such longitudinal movement, and fluid operated

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