USRE22034E - Variable pitch propeller mechanism - Google Patents

Description

Feb. 24, 1942. w s. HOOVER VARIABLE PIT CH PBOPELLER MECHANISM a sheets-sheet 1 Original Filed Nov. 2'7, 1934 Feb. 24, 1942. w. s. HOOVER 22,034

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w. s. HOOVER Re. 22,034 VARIABLE PITCH PROPELLER MECHANISM Original Filed Nov. 27, 19:54

8 Sheets-Sheet 8 6/ l a? 4Z1 [nae/1731", WEI/fer 6. Hoover? r Him/mg Rei'a'ued Eeb. 24, 1942 UNITED STATES] PATENTF'QFFICE VARIABLE PITCH PROPELLER. MECHANISM Walter's. Hoover, West Hartford, Conn. Original No. 2,184,143, dated December 19, 1939,

Serial No. 755,031, November 27, 1934.

newed September 15, 1936..

Re- Application for reissue July 27, 1940, Serial No. 348,011

13 Claims.

This invention relates to improvements in variable pitch propeller mechanism, of the general type disclosed in my Patent 1,972,486, issued September 4, 1934.

In the aforementioned patent there is disclosed anhydraulic mechanism for manually and/or automatically effecting the pitch setting of the propeller blades in accordance with the motor load conditions incident to the maneuverability of air-craft.

In accordance with the present invention,"

novel means are provided for transmitting the force developed by the hydraulic unit to' the propeller blades in a manner to prevent hunting of the motor which is characteristic of the automatically controlled variable pitch propeller mechanisms heretofore proposed.

In accordance with the present invention, the medium through which'the hydraulic force is transmitted is self-locking and yet eliminates friction loss, thus rendering it'highly emcient and in addition provides a high reduction ratio between the source of power and the blades.

It is another object of the invention to provide mechanism which shall be adapted to effect a change in the setting of the propeller pitch angle in a smooth and steady manner thereby preventing abrupt changes in motor operation and consequent severestress on the operating parts.

Still another object ofthe invention is the provision of semi-automatic means for manually controlling the adjustment for pitch setting through the medium of electrical control of, the hydraulic unit which, when released, restores automatic control. T

Still a further object of the invention is the provision of manual control means for the hyportion of the propeller hub unit illustrating a modified form of hydraulic rotor;

- Fig. 6a rear view with the housing shown in Fig. 5 partly cut away;

Fig. 7 a plan view of the blade operating an'-' nulus diagrammatically illustrating the mounting of the internal counterweights on the blades;

Fig. 8 a cross-sectional view partially in elevation of an electro-magnetically actuated control valve;

Fig. 9a plan view of the pressure and relief tubes with control valve and governor arms;

Fig. 10 a cross-section of the tube of Fig. 9

taken on line l0lll, Fig. 9;

routing of, the pressure fluid through the con- 'the propeller blade anchorages.

purpose of illustration a hub design for twov Fig. 11 a plan view of the roller bearing for the blade anchorage shown in Fig. 3;

Fig. 12 a diagrammatic showing of the oil pres-'- sure system and its connection to the engine and pitch adjusting unit; and

Fig. 13 a diagrammatic view illustrating the trol valve to the hydraulic actuating unit.

With reference to Figs. 1 to 4 inclusive of the drawings, the numeral I generally designates a propeller hub casting or forging having oppositely disposed hollow extensions 2 for mounting While for the blades is shown, it is obvious that the invention is applicable to propeller mountings employing any number of adjustable blades.

draulic operating mechanism which may be readily substituted for the fully automatic or semi-automatic control mechanism..- These and other objects of the invention will become more apparent from a-consideration of the accompanying drawings constituting a part hereof in which like reference characters desig- ,nate like parts and in which: Fig. l is a front elevational view of' a variable pitch prop'ellen unit embodying the principles of this invention, having its front cover removed;

Fig. 2 a cross-sectional view thereof taken along the line 2-1, Fig. l; Fig. 3 a side elevaticnal view partially in sec-.

tion of the structure shown in Figs. 1 and 2;

, Fig. 4 a sectional elevational view taken on the line 4-4, 'Fig. 3; I

Fig. 5 a side elevation partially in section of a In Fig. 3 the blade root 3 is shown provided with a buttress thread 4 to receive an annulus 5 on which is mounted oppositely disposed counterweights 6, the counterweightsbeing at right angles to the face of the blades as is diagram-.

matically shown in Fig. '7 of the drawings. The function of the counterweights- 6 is to partly counter-balance the magnitudes of centrifugal torsion moments which act on the geometrical mass of the blade to assume lines of exact radii from the nearest centerline tending to flattenout th pitch in the plane of rotation. For

example, in a propeller operating at 2,100" R. P.

M. with the centrifugal torsion at about 4,000 inch pounds for each blade, the employment of internal counterweights 6, while ineffective to entirely balance-out the centrifugal torsion because of space limitations, will reduce the magnitude of centrifugal torsion moments about 1,500 inch pounds for each blade. 7 The weights are positioned at approximately from the crank shaft centerline when the blades areadjusted for normaloperation'.

A sleeve 1, Fig. 3, having a flange 8 houses a series of roller bearings 9 and Ill, the'bearings .9 having their axes parallel to the axis of the -blade to take up the angular thrust of the blade, and the remaining bearings III are radially dis-' posed to take up the centrifugal thrust of the blade. Roller bearings II are provided at the extreme lower end of the blade root with theirwith an annular lead 39 having ported openings 39. The pressure is released through a duplicate annular lead 38a communicating with the ported'opening 40, the annular leads being more axes in parallel;.alinement with the bearings 9 to take up the angular thrust and to provide a maximum spacing of the thrust bearings to provide strength and rigidity invariable propeller blade mounting. The bearings II by their manner of assembly are preloaded to take up internal slackness of the bearing set up. The bearings Ill are interchangeable and are necessarily designed to effect uniform distribution of the load on all of the thrust members, the roller races requiring precision in their tolerances. The short leg of the L-shaped races is adapted to flex slightly under load to make up any discrepancies in the tolerances of successive bearings, thus equalizing the load over a series of stack bearings.

, The propeller blade anchorages as above de scribed are actuated to vary the pitch setting by subjecting the annulus 5 in which they are l5, one of which fits into a hemisphericalseat in the projecting portion l4, and the other ball is held in place by an adjustable cavity in a screw it.

The worm I2 is mounted on a shaft I! having a pinion l3 that interacts with the teeth of a ring gear l9 which is actuated by a fluidmotor generally designated by the numeral 20.

The worm shaft l l isanti-frictionally mounted by bearings 2| and 22, and a U-shape packing 23 prevents leakage of fluid from the hydraulic unit through the gear teeth.

The hydraulic unit 20 comprises a rotor 24 having flanges '25 and 26 which in cooperation with housing walls 21 and 28 form leak pressure cavities 29 and 30, the flange-walls and 26 being of rigid mechanical construction to prevent distortion and to permit of proper sealing of the housing and rotor by gaskets 2|. The, leak pressure cavities 29 and. 30 are adapted to counteract the internal pressure of the rotor by building clearly shown in'Fig. 2.

The flow. of fluid is controlled through valve mechanism generally designated by the numeral 4| which regulates the flow from a port 42 in the side of the propeller hub shaft, Fig. 2, to a flow cavity 43 which surrounds arelief pipe 44 by which the fluid is returned to the pressure source. The flow cavity 43 communicates with a tube 45 that extends to 'a .valve chamber 45, Fig. 3, from which it flows through a ported passage 48 to thepressure lead 31 of the rotor, Figs. 2 and 4.

Ported passages 48 and 48a are controlled by a slide valve 49, Figs. 3, 8 and 10, the valve being of spool shape and hollow in the center to balance the pressure on its outer flange. Valve 49 is actuated by a governor to control the flow of pressure to one side of the vanes 33 and simultaneously relieve the pressure on the opposite side. The governor comprises shafts 50 having governor arms 5I,,Figs. 1 and 3, which are responsive to centrifugal force producedby rotation of the hub to actuate their respective shafts 5!! which bring about the movement of the slide or spool valve 49 throughzconnecting levers 50c, Figs.3, 8 and 10. It will be apparent from Fig. 3

. that when'valve 49 is moved in the direction where it uncovers the port 43 on the outside of its end flange, it will simultaneously uncover the other port 43a on the inside of the opposite flange (Fig. 3) thus'relieving the pressure on one side of vane 33 through the passage 41 of the inner tube or pipe 44. Q

Valve 49 is controllable manually for synchronizing the pitch setting of a plurality of propeller units by actuating'governor arms 5| independently of the centrifugal force that tends'to spread them, such" control being effected through a pair of electrical solenoids 52, Fig. 1, and solenoids 57 and 58, Fig 8, that are electrically connected through lead wires 53 with collector rings 54 mounted on the rear of the hydraulic rotor, current being supplied to the collector ring through brushes 55 connected 'to a source of electrical energy such as a battery. The control is effected by means. of a push button switch- (not shown) which, when held depressed by the operator, will energize solenoids 52 thereby drawing out the governor arms 5| to produce the desirable adjustment of the valve 49 thatcauses up pressure due to the slippage of fluid by the- I pressure differential between the inner and outer faces of the flanged wall. The pressure on both sides of the flanged walls 25 and 28 is substantially balanced by the leak pressure balancing leaks 32 extending through movable vanes 33 and through flange walls 25 and 26, this lead being shown in dotted lines in Fig. 2 and is more clearly shown in Fig. 4 of the drawings.

With reference to Fig. 4, the hydraulic unit embodies a pair of stationary abutments 34 which are secured to the housing 21 by cap bolts 35 or in any other suitable manner, these stationary abutments cooperating with the movable vanes 33 that are attached by dowel pins 35..to the flange walls 25 and 25 of the rotor, the vanes 33 cooperating with the fixed abutments to be relatively movable by fluid presure which is supplied through a pressure lead 31 communicating actuation ofthe movable vanes of the hydraulic unit to produce a desirable pitch setting. When the button switch is released, solenoids 52 will be deenergized and governor arms II will assume the position they would have for the particular revolutions of the propeller shaft at the time of such release.

The mechanism may also be entirely manually I controlled bymeans of the structure shown in- Fig. 8 wherein the governor arms 5! are removed from their shafts 53 and a movable armature 5G is mounted on one-of said shafts. The armature' is actuated by solenoids 51 and 59 which are wired to collector rings 54, Fig. 3, and controlled by separate switches. The valve 49 shown I in Fig. 8 is biased by cofl springs 59 to a normal position o1 pitch setting. Valve 49 is provided with an axially extending finger 5la having a notch 49b which is engaged by a lever 50a mounted to be movable with shaft 53 in response to angular movement of the armature 56. It will be noted as viewed in Fig. 8 of the drawings that the valve 49 has flanged ends which control the ported ducts and 49a for directing the fluid pressure to the hydraulic actuator for effecting a forward or reverse pitch setting, the

with one of the switches the valve 49 will route the actuating fluid to set the pitch of the blades to forward position, and by energizing the other of the solenoids the fluid will be routed to reverse the pitch setting 01 the blade thus affording an all-manual control without any change of the blade actuating mechanism.

A modified form of hydraulic unit or motor is shownin Figs 5 and 6 of the drawings, and consists of a movable housing member which carries the movable vanes 8 I that cooperate with 's't'a'tionary abutments 62 secured to a sleeve 63 by bolts 63a. Sleeve 63 is keyed to a stationary hub portion 63 by a key 64, Fig. 5. The numeral 64a designates an annular pressure lead having ported openings therein. The operation of this type in which the outer housing is movable instead of the inner part as in Fig. 4, is thesame as that of the operation of the structure of Fig. 4, the fluid pressure and relief passages being the same as is readily apparent from comparison of the two figures, the primary aim'of the cylinder housing being to prevent distortion due to the oil pressures used. v L

Fig. 9 shows in detail the relief tube 44 and the pressure tube 45, one end of the relief tube a 44 being provided with'a plug that fits in the counterbored portion of the propeller hub shaft 66, a screw plug 61 interacting with threads provided in the end of shaft 66 to hold the supply tubes 44 and 45 in position.

The pressure tube 45 has a threaded portion 68 that cooperateswith U-shaped leather packing for longitudinal adiustmentwi h the tapered ,face of crank shaft 58 with which it seals, and

a screw plug 69 is provided to render valve 49 accessible. jGovemor arms 5| are shown .at-- tached to theendof the tube-like structure and are operatively connected to valve 49 to adjust the latter in response to variation in the motor *speeds. I T

Fig. l2 diagrammatically illustrates a system for the development of oil pressure in a-,con v entional motor bythe' .use of'auxiliary equipment which functions to'de-velop pressure in excess of the engine pressures while maintaining lower pressure on the oil used for lubricating the em I gine parts,. In Fig. 12'the numeral 69 designates. a gear pump having a conduit Ill. leading :to a

' maintank I l.. and aconduit 12 thatde'livers flu id is j, distributedathigh pressure'througih'c d "to the hydraulic propeller 'unit genera hated by fthenumeral l5 Pump-1B9, 'de 'oil to chamber,13 at a pressure-in eircess [maximum pressure required for "scent I hydraulic propeller unit, and chamber-1i v vided with a relief :'valve 13a having adjustable means for setting the valve to maintain ,pre-

determined oil pressure in chamber 13 is; for

-- example, 209 pounds. so thatthe pressure ole-'- livered througli""'conduits 14 to the hydraulic pitch setting unitwill always, be at 200 pounds,

or whatever pressure is desired. Thebalance of the fluid delivered by pump 69 passes from chamber 19 through conduit 13b to a chamber 130 which is provided with a relief or blow-oil valve 5 13d to maintain a predetermined pressure, such as 75 pounds, in the tank 130. The lubricating fluid is delivered to the engine by conduit 136 from chamber 13c and the fluid, after passing through the parts of the engine to be lubricated, m is returned to the engine sump 18, the blow-off and leak from chamber 130 and the engine being shown by dot-and-dash lines. The drain or return flow from the hydraulic propeller unit is shown as passing out the off-set of the crank 15 shaft at the portion designated by the numeral 11. The oil from the engine sump is returned to the scavenging side 89 of pump 69 which returns it to the main tank H.

The operation of the above described variable go pitch propeller mechanism is briefly as follows:

Assuming the blade roots to be'mounted for rotary movement as hereinabove described, that is, in the bearing set up shown in Fig. 3 with the counterweighted annuli 5 in cooperative engage- 'ment with the worms I! through rollers i3, the pitch of the propeller blades in the absence of manual control will be entirely determined by the operation of the governor arms 5| which respond to the centrifugal force produced by the :m speeds of the motor. As the governor arms 5| I move angularly on their shafts 50, the valve 49 controlling theflow of fluid under pressure to the rotary abutments of the hydraulic unit will beactuated by levers 50a, Fig. 13, to open and :15 close the ported passages 48 and 48a, respectively, thereby routing .the pressure fluid from passages 41 and 41a through port 48 to the pressure lead 31 of the rotor thereby subjecting the movable vanes 'or abutments of the hydraulic unit in to pressureon one side and relieving the'pre'ssure on the opposite side through port 49a to the '!'sump passage 4|, causing the rotor po tion 33 I to rotate which, through ring gear I9, actuates pinion l8 and connected worm shaft l2 causing the annuli 5-to move angularly to effect the change in pitch setting; i

As previously stated, the worm drive is a selflocking device which :prevents hunting of the motor due to leakage-of pressure or slippage of :m the mechanical linkage, and yetthrough the roll-- er engagement urine worm with the annuli substantially all frictiomis eliminated. Further, by

' means of the worm drive, a high reduction ratio between-the fanv blade and hydraulic rotor is 5 attainable so that excessive fluid pressures are not required to operate the-pitch setting mechaisms. I

In the modification 'of hydrau ic unit shown 7 Figs. 5 and 6, the same principle of operation no is present, the l only difference in the construcmen being the rotary movement of the housing instead of the inner member. If it is desirable to use the "manual control as in starting. the cperator e'nergiies the circuit of solenoids 52' which f -actuate the governor arms 51 to effect a change of setting of valve '49 and a. consequent movement of the rotary abutments to change the pitch angle. r 7 When the .fnanua-l control switch 'is released, the solenoids-filwill be 'deenergized and governor 1 arms 51 willjf be released to the position which i'they would normallygassume for the particular 4 engine speed at such time. If the all-manual control is employed as in the tion of pressure to the face of the movable vanes.

One of the solenoids will move the valve actuat-.

'ing armature 56 to forward position of pitch setting and the other to reverse pitch setting, and

. when both electrical circuits are deenergized, the

valve will assume the position in which the blades will be disposed for a given operating condition.

speed responsive device to actuate the rotor in accordance with desired changes in the pitch setting of the blade anchorage members.

3. A hydraulic unit for changing the pitch setting of variable pitch propeller blades comprising a hub structure, a plurality ofv blade anchor- In the exercise of the manual control the solenoid circuits will remain energized only so long as the operator makes contact with push button or other control switch.

It is apparent from the foregoing description of this invention that variable pitch propeller mechanism operating on the hydraulic principle and embodying the principles herein disclosed provide eflicient means for propeller blade adjustment within a compact space with-mechanical devices that are compact and not of excessive weight.

By mounting the hydraulic unit or rotor at the rear of the hub more compactness and a shorter design is obtainable.

Although one embodiment of the invention has been herein illustrated and described, it will be obvious to those skilled in the art that various modifications may be made in the details of construction and in the arrangement of the coop-.

crating parts without departing from the principles herein set forth.

I claim:

l. A hydraulic unit controlling the pitch setting of variable pitch propeller blades comprising a hub structure, blade anchorages mounted therein, a double acting vane type hydraulic actuator operatively connected to the blade anchorages to render them simultaneously movable, said actuator communicating with a source of fluid pres-. sure, valve means controlling the application of fluid pressure to said actuator, said means being normally biased to maintain the valve in one position of its operation, electro-magnetic means age members rotatably mounted therein, a double acting vane type hydraulic actuator geared to the blade anchorages to render them simultaneousl'y movable, a conduit for supplying fluid pressure to said hydraulic actuator from a source remote from said propeller, valve means for controlling the application of fluid pressure to said actuator, means foroperating the control valve comprising a movable armature normally biased to maintain the valve in oneposition of its operation, electromagnetic actuating means for said armature, said valve, armature and electromagnetic means being carried bysaid' hub structure, and meansfor selectively energizing said electromagnetic means to increase or decrease the pitch settingof the blades comprising, electrical contacts movable with said hub and electrically-connected to said electromagnetic'means, and means for supplying a source of electrical energy to said movable contacts.

4. A variable pitch propeller mechanism comprising a hub structure and blades movably mounted therein, a double-acting vaned type of netic means for actuating said valve, said means comprising electrical contacts movable with said for moving said valve means in the other Positions of its operation, said valve and electromagnetic means being carried by said hub structure and means for energizing said electromagnetic means to render said valve means operative'to increase or decrease the pitch setting of the propeller blades. comprising, electrical contacts movable with said hub and electrically connected to said electromagnetic means, and means for supplying a source of electrical energy to said movable contacts.

2. A variable pitch propeller mechanism comprising a hub structure, blade anchorages mounted ior rotary movement therein, screw shafts having gear tooth engagement with said anchorages, fluid pressure mechanism for simultaneously actuating the screw shafts and control means for said fluid pressure mechanism mounted in said hub and rotatable therewith to adjust the pitch setting of the blade anchorages in response to the speed of the hub, said fluid pressure mechanism comprising a housing having a plurality o1 sta-.

tionary abutments, and a rotor having movable abutments, said rotor being gearedto the screw shafts and said control means consisting of a speed responsive device and a slide valve connected to a source of fluid pressure andto'the space between the stationary and movable abutments, said slide valve being actuated bythe hub and electrically connected to said electro-' magnetic means, and means for supplying a source of electrical energy to said movable con tacts. i

5. A variable pitch propeller mechanism comprising a hub structure and blades movably mounted therein, a double-acting vaned type of fluid motor, mounted on the propeller hub, connected with the blades for changing the pitch of the blades, a conduit for supplying fluid under pressure to said motor from a source remote from said hub, a valve in said hub'contro'lling the application of said fluid to actuate saidmotor, electromagnetic means for actuating-said valve, contact rings on said hub, stationary brushes in constant engagement with-said rings and connected to a, source of electrical energy, and electrical conduits. connecting said rings and electro-magnetic valve actuating means.

6. A variable pitch propeller mechanism comprising a hub structure and blades movably mounted therein,- a fluid motor mounted on the propeller hub connected with the blades for changing the pitch of theblades, a conduit for supplying fluid under pressure to said motor from a. source remote from said hub, a valve in said hub controlling the application of said fluid to actuate said motor, a. governor having movable weights mounted in and rotatable with said hub structure, said weights 'being responsive to the speed of the propeller hub to actuate saidfluid controlling valve,- electromagnetic means for actuating the governor-weights to actuate the fluid control valveat the will of the operator, said electromagnetic means having electrical connection with a current collecting means mounted on.

the hubstructure and rotatable therewith, and

means for supplying a source or electrical energy to said current collecting means.

7. In combination with a controllable pitch propeller having a range of pitch adjustment between fixed limit stops, hydraulic means for changing the pitch of said propeller, a valve rotatable with the propeller controlling said hydraulic means, a governor responsive to the speed of the propeller for actuating said valve in one direction, a spring for actuating said valve in up position to said governor, and manually controlled means rotatable with said propeller, said valve having a neutral position in which said valve is under the control of said governor and said spring, said manually controlled means acting upon said value to positively move said valve to a fixed pitch setting position against the action of said govemor and said spring;

a. In combination with a controllable pitch propeller having a range of pitch adjustment between fixed limit stops, hydraulic means for changing the pitch of said propeller, a valve ro-, -tatable with the propeller controlling said hydraulic means, a governor responsive to the speed of the propeller for actuating said valve in one direction, a spring for actuating said valve in opposition to said governor, and electromagnetic means rotatable with the propeller operable to hold said valve in a fixed position of its pitch setting movement independently of the action of said governor and said spring.

9. In combination with a controllable pitch propeller having a range of pitch adjustment between flxed limit stops, hydraulic means for changing the pitchot said propeller, a valve rotatable with the propeller controlling said hy draulic means, a governor responsive to the speed of the propeller for actuating said valve in one direction, a spring for actuating said valve in opposition to said governor, and electromagnetic means rotatable with the propeller operable to actuate the governor arms and control valve independently of the speed of the motor.

said high and low pitch setting, a control valve rotatable with said propeller for said actuating means, governor means responsive to the propeller speed for controlling said valve, spring means biasing the speed responsive elements of the governor means, and electromagnetic means rotata'ble with said propeller for operating said governor speed responsive elements independently of the propeller speed.

11. In a variable pitch propeller, propeller-blade pitch-changing mechanism comprising a rotary hydraulically-actuated angularly-movable displacement means geared to the blades of said' propeller, a spool valve hollow throughout its length and subject to equal fiuid pressure at each end located in said propeller with the axis of said valve disposed transversely to the axis of the-propeller, said valve controlling the flow of engine lubricating .fiuid to and from said mechanism for operating the same, and speed responsive means in said propeller operatively conan electromagnetic force acting upon the metal of the'governor fly-weights for operating said governor independently of the propeller speed.

13. In combination with a controllable pitch propeller having a hub structure, a plurality of pressure communicating with said valve, a gov-- ernor ior said valve rotatable with the propeller, electromagnetic means for controlling said valve at the will of the operator, and an internal mass rotatable with the propeller developing a force counterbalancing the centrifugal moment of the blades.

\ WALTER S. HOOVER.

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