US2451059A - Propeller mechanism - Google Patents

Description

Patented Oct. 12, 1948 PROPELLER MECHANISM Werner J. Blanchard and Charles S. J. MacNeil, Dayton, Ohio, assignors, by mesne assignments, to General Motors Corporation, Detroit, Mich a corporation of Delaware Application August 5, 1942, Serial No. 453,654

1 Claim.

This invention relates to adjustable blade propellers and more particularl to regulating devices therefor such as described in our copendlng application Ser. No. 279,531 flied June 16, 1939, and now patent 2,307,102 and of which this application is a continuation in part.

It is a principal object of the invention to provide a self-contained regulator unit for controlling the setting of an adjustable propeller blade which is simple in construction and opera- 'tion and which provides for accurate regulation and control of the pitch angle of the blade and over its speed of rotation.

It is a further object to provide a regulator assembly of this character having its own fluid pressure medium of proper predetermined characteristics as best suited for the purpose and which may be recirculated entirely apart from the engine lubricating system.

It is also an object to provide a regulator for a hydraulically adjustable propeller in which the fluid pressure system is entirely contained within mechanism which rotates with the propeller, requiring no fluid pressure connection to the engine or other stationary part. 1

It is also an object to provide a regulator device of this character in which a member rotatable with the blades and arranged tobe acted upon by substantial centrifugal force is made to control directly the application of hydraulic pressure to secure accurate setting of the blades and regulation of the engine speeds to accurate values.

It is a further object to provide a fluid circulating system for developing the hydraulic pressure for controlling the setting of the blades which is operative to establish and thereafter only as required to maintain the desired fluid pressure conditions, thereby avoiding unnecessary working and generation of heat.

It is a still further object to provide a single regulator assembly of the character described having a predetermined quantity of fluid pressure medium, and means for indicating substantial depletion in quantity of medium.

A still further object of the invention is to provide means for indicating the sufllciency of In the drawing Fig. 1 is a vertical sectional view along the axis of the regulator device constructed in accordance with the present invention;

Fig. 2 is a transverse sectional view through the axis of the regulator at right angles to the view of Fig. 1,'and substantially as indicated by the line and arrows 22 of Fig. 1.

Fig. 3 is a diagrammatic view showing the parts contributing to the present invention in their functional relation.

In order to provide for adjustment of the setting of the blades in a hydraulically adjustable propeller, suitable means are provided for effecting change in the pitch angle of the blades under the action of selectively applied and controlled hydraulic pressure, application Ser. No. 279,530 flled by us on June 16,1939, now patent 2,307,101, an adjustable blade propeller is shown in which selectively and positively applied hydraulic pressure is utilized to effect both pitch-increasing and pitch-decreasing change in the blade setting, the blades being adjustable over the usual flight range, into a feathered position, and also into a negative pitch position to provide a negative thrust for purposes of landing, maneuvering, and the like. The present invention provides a regulator assembly arranged to develop and supply to the hub and blade structure separately controlled sources of hydraulic pressure for positively actuating the blade in each direction, throughout its range of adjustment to secure predetermined desired setting of the blades. This fluid pressure application is so regulated over the normal flight range as to provide for maintaining substantially constant speed of the propeller within such range as selected either manually or in accordance with instrument control, that speed being subject to change as required. And by reason of the particular construction and arrangement of the invention as hereinafter described, a highly accurate and definite speed condition is provided so that'for example Where a plurality of aircraft propellers are driven by separate engines, the regulating means provides for maintaining accurate conditions of setting of the blades such as to establish accurate speed control and to avoid objectionable noise and vibration from beats produced by the engines.

The invention is likewise applicable for similarly controlling a propeller which utilizes positively applied hydraulic pressure for actuating the blades only in one direction, either for pitch-increasing or pitch-decreasing purposes, the blades being returned in the opposite direction oi. movement, under theaction of centrifugal i'orce, resilient means or the like. c

The separately controlled source 01' hydraulic pressure for the hub and blade structure is emanism for the most part is substantially immersed in the fluid pressure medium, which medium when the regulator is in a state of rotation, is in eifect thrown against the circumferential wall of the regulator. Those parts oLthe control mechanism that are radially movable'will then tend to float in the fluid pressure medium, or their outward movement be opposed by a force substantially equal to the mass of medium displaced by them. It is a well known fact that when any object is wholly or partially immersed in a liquid it is buoyed up by a force equal to the weight of the displaced liquid. and that the center of pressure is where the center of gravity of the submerged portion would be if it were homogeneous. As a result, the submerged and movable parts of the control mechanism are subjected to an inwardly acting buoyant force equal to the weigh-tot the liquid displaced. Considering the control mechanism described. centrifugal force acting on the moving elements of the mechanism is resisted by the spring force plus the above described buoyant force. If the level of the fluid pressure medium falls so low that parts of the movable elements of the control mechanism become only partially immersed this buoyant force is reduced. Since centrliug'al force is-equal to the product of the mass 4 the constant speed attained by the control mechanism. O! the two results, underspeed may be more hazardous than overspeed, since the aircraft may be less responsive to the pilot's control. It

therefore is desirable to know whether or not and when the fluid pressure medium becomes materially depleted. because a low level of fluid medium results in a low top speed.

Referring to the drawing which discloses a pre-.

ferred embodiment of the invention the propeller blades iii are shown as adiustably and rotatably mounted within hub II the hub being provided with blade sockets corresponding to the number of blades, three being shown herein. The hub is driven from drive shaft 12 projecting outwardly from the engine casing l3, the axis of rotation of the drive shaft being shown at ll. The

*regulator of the present invention is indicated moment times the square of the angular velocity.

and since the force to be overcome by centrifugal force is diminished by the reduction in buoyant forc a lower speed of rotation is required to "cause the eontrolmechanism to assume its neucontrol mechanism is immersed.

In the instant disclosure regulation or the fluid pressure application is eflected by means of a radially movable valve member that responds to centrifugal force in opposition to a constantly applied spring force, thus becoming itself the governor mechanism. Designedly, the valve member along with its movable linkage, is immersed in the fluid pressure medium and is responsive to dominance of either centrifugal or spring force to effect sufllcient regulation for constant speed within the range selected, regardless of the level of fluid pressure medium. However, the change of level of the medium, whether it be above or below the prescribed level, will. aflect the range that may be selected for control since the change in buoyancy of the immersed valve member will change the speed of rotation required to move the valve member for its control function. In substance, if the level of fluid pressure medium is above the prescribed level, then the buoyancy or flotation of the valve member is increased and a greater centrifugal force is required to press it to the equilibrium position. Conversely, if the level of the fluid pressure medium is below the prescribed level, then the buoyancy or flotation of the valve member is decreased and a lesser centrifugal force is required to press the valve member to the equilibrium position. That means that the speed setting for which regulation is to be accomplished, though selected by hand or instrument, may be lower or higher respectively than tor assembly is located immediately in front of the motor casing and adjacent to and rearwardly oi propeller hub i I.

The hub H has a-sleeve portion i6 formed integrally therewith which is provided with spline teeth i! for engaging a similar spline upon the drive shaft l2, to provide for rotation of the hub therewith. A wedging ring i8 and locking ring l9 retain the hub in proper driving relation upon the shaft I2.

Bolted to the motor casing l3 by means of .bolts 22 is a stationary plate 23 extending radially inwardly and provided with-a series of bolts 28 for supporting an annular ring member 25 thereupon in stationary relation with respect to the motor casing. The ring 25 is formed integrally with a flange 26 which extends'radially outwardly therev of and has a tumed-over end portion 21 which is provided with a succession of lobes around its peripheryto' function as a cam. Preferably thecam 21 has two high points alternating with two low points uniformly arranged around its periphery.

Seated within a recess in the sleeve portion i6' of the hub and extending radially outward thereciated operating-mechanism. Member. 30 isheld in place upon the sleeve i8 by means of 'a locking ring 3i spaced inwardly from'ring 25 with sufllcient clearance to permit of rotation of ring 3| and member 30 along with hub ll, out of contact with stationary ring 25. g

Member 30 extends radially outward and receives a cover plate 33 in fluid sealed relation upon its outer periphery, the cover plate having an inwardly extending web portion 34 supported upon and sealed with respect to the ring 25. The cover 33 is bolted to member 30 by means of a series of bolts 35 such that it can be removed to provide access to the interior'of the regulator housing.

When in position the cover thus forms a com- 4 pletely enclosed chamber or reservoir for the reception of the hydraulic actuating fluid, and provides a fluid-tight connection preventing escape of fluid from within the chamber for this purpose a sealing member 31 is adaptedto engage the. flange 34 and ring 25, being retained in sealing position by means of contractile spring 38 and cover plate 39. Likewise to prevent escape of fluid from within the housing, a sealing member 40 is aasrosc provided between the inner end portion of member 40 and ring 2!, being similarly retained in place by means of spring 4i and cover plate 42 held in place by bolts 43.

The pump structure and control mechanism is located within the space enclosed between the cover 33 and member 30 so that it is sealed against passage of fluid therefrom and continuously sub- Jected to and operative in the reservoir of fluid pressure medium received therein which serves to lubricate and transfer heat therefrom. Upon rotation of the housing, fluid contained therein will move radially outwardly toward the inner wall of cover I3, which thus forms a reservoir for the fluid, the quantity thereof preferably being such that it practically fllls the reservoir with only a relatively small clearance volume.

Satisfactory results are obtained with the reslator slightly more than half full of fluid, yet satisfactory operation has been obtained with as little as one pint of oil. Normal oil level requires two and one half quarts or more of fluid in the regulator. In main, calibration and ground adiustment will establish fidelity of responsefrom the control mechanism for any predetermined level of fluid pressure medium that may be decided upon. It is therefore only necessary to have sufficient fluid pressure medium in the reservoir to serve the apparatus effecting th control.

'The surface of the fluid while the apparatus is under a state of rotation with normal level is indicated at 44. It is deviation from that level, and particularly a loss of level that is of primary concern here, because. operation at low oil level decreases the maximum speed at which the propeller will control, due to the loss of flotation forces on the moving governor parts. This decrease in speed may amount to about 8 to 10 percent before the oil level becomes critical, so the pilot has a regular check on oil level during each take-off or at any time in flight by moving the propeller control to a selected speed position. Noting the R. P. M. that the engine settles to for the selected propeller control will give an indication of the level of fluid pressure medium as respects the predetermined level for which the control mechanism has been adjusted and calibrated. If the engine speed obtained is coincident with the propeller setting, the indication is that the level of the medium is satisfactory, but if coincidence is not obtained and the engine speed indication is less than the propeller control setting then there is an indication that the level of the fluid pressure operating medium is low, and that it should be replenished for most eflicient operation.

The inlet/for picking up fluid from the reservoir comprises a funnel-shaped member 45 having a screening device 48 over the opening and extending radially outwardly toward the inner wall of the reservoir. It approaches but is spaced some-' what therefrom to avoid picking up any sludge or other deposit from the fluid, but is relatively close so that it will be assured of receiving a supply of fluid. Passing through the funnel, the fluid enters through port 41 the valve chamber of a cut-off valve 48. Valve 49 stands radially of the housing so that the body thereof is subjected to outward centrifugal force in the direction to open the valve, variable with the speed of rotation. A compression spring 50 acts in the same direction as centrifugal force, to urge the valve toward open position with a constant force. The valve has a stem ii the end of which is acted upon by fluid pressure from a pressure chamber 52 in communication with the pressure side of the pump. Pressure so applied acts to urge the valve toward closed position so that upon the development of a pressure on the delivery side of the pump of the proper value, that pressure will be made effective upon the valve stem, to cause the closing of the shut-off valve and the consequent termination of the supply of fluid into the pump chamber. A safety by-pass 58 is likewise provided through the valve chamber, which is uncovered by the valve stem only after the inlet port has been substantially closed off, this by-pass providing for relief in the event of the operation. of either of the pumps for the period immediately following the closing-off of the inlet ports.

The passage I1 leads from the control side of the shut-oil valve directly into the pumpvalve chamber 40. Preferably the pumps and valve means therefor are duplicated, to provide more uniform conditions of operation and of developed pressure, and for this purpose a double passage Il leads from the inlet valve chamber 40 to two pump valve chambers 80 arranged in spaced relation to each other around the periphery. The chambers 60 and pump chambers 8| are preferably formed upon the inner wall portion of member 30, and may be cast integral therewith.

Inasmuch as the structure of each of the pumps and associated valve means is similar to the other, only one such structure will be described in detail. Each pump comprises a cylindrical sleeve member 84 mounted fixedly in the pump chamber BI and slidably receiving the pump piston therein. The piston and cyiin der are relatively elongated axially to provide a substantial bearing area and to maintain a fluidtight seal in the absence of any packing material under the pressure conditions which are developed within the pump. It will be noted that the pump piston is mounted so that its movement is not responsive to centrifugal action, the centrifugal action merely resulting in a side thrust upon the cylinder which is adequately provided for by the large bearing area. A compression spring 86 serves to move the piston outwardly of the cylinder, and the piston is guidedfor longitudinal reciprocating movement by means of a cross guide arm 61 of rectangular cross section which travels in a correspondingly-shaped guideway 88 formed in the chamber 8|. Piston 85 is provided with a recess at its outer end and roller 10 is supported therein on a bearing member H carried by cross arm 81. The roller 10 serves as a'cam follower and has rolling bearing engagement with the face of cam 21 to cause corresponding movement of the pump piston 85.

As previously described, cam 21 preferably has a plurality of lobes. which are followed by the piston and the roller as the assembly rotates about the fixed cam to cause reciprocating movement of the pump piston, to a closed position under the action of the cam and then outwardly under the action of spring 66. In the arrangement shown the two pump cylinders are preferably located 90 apart so that with the doublelobed cam two complete cycles of operation of each pump in alternation are secured with each revolution of the device.

The pump cylinder is ported as shown at I! and this passage leads directly into the pump valve chamber 60. The valve structure within ,the chamber 80 comprises an annular member 16 positioned within the chamber and forming a suction chamber l'l at the radially outer end of chamber 40 communicating directly with the suction inlet passage 51. Member 14 is provided with a series of apertures I8 therein providing for the passage of the fluid from chamber 'I'I into the centrally located pump chamber 18, when the suction valve 80 is raised from its seat. Valve 80 is normally urged toward sealing position by means of compression springjl, and is likewise mounted-in such position that it is afl'ected by centrifugal force so that it is continuously urged toward seating position with a force corresponding to the speed plus .the force exerted by spring 8i.

Annular member 82 deflnes the chamber I9, and. is also provided at its end with a series of apertures 83 leading into the discharge chamber 84 formed in valve chamber to toward the radially lnner end thereof and defined by annular member 85. A discharge valve 06 provides for the closing off of the ports 88 andis urged toward closing position by means of spring 81 and is likewise acted upon in the same direction by centrifugal force.

The operation of the pump and valve mechanism is as follows. Upon movement of the piston 65 to expand the pump chamber under the inlet 05, past the shut-off valve 59, through'pasj sage 51, into the suction chamber I'l through the it flows directly into the pump cylinden; Upon the return stroke of the pump, the piston is cammed positively in the opposite direction,

thereby. subjecting the fluid within its cylinder to pressure, which causes it to flow back into chamber I9 under pressure. This causes the closing of suction valve 80, and the opening of discharge valve 86 to supply the fluid under pressure to the discharge chamber 84. V

The discharge chamber 84 leads directly into a pressure conduit 90 which is preferably formed as an integral unit comprising a tube ill of copper, steel or the like cast integrally in a housing comprising the annular member 30. As shown this conduit arranged in circular form, providing the pressure conduit 90 extending in continuous arcuate manner around the member 30 and valve assemblies, so that pump discharges directly thereinto.

The intake chamber and shut-off valve device is provided with a passage 95 having direct communication with conduit 90, to provide for making the fluid pressure developed by the pumps effective within the chamber 52 and upon the valve stem 5i of the shut-off valve as previously described. Thus upon operation the pumps will jointly produce a pressure within conduit 90 which is returned through passage 95 to effect actuation of the shut-off valve 49 upon the pressure reaching the value which it is desired to maintain for purposes ofoperation. Alt that point valve stem SI moves radially inwardly against the action of spring 50 and of centrifugal force to a closed position to substantially close off the suction inlet opening 41. Thereafter, although the pump piston 65 continues to be actuated in response to rotation, it merely proand having communication with both the pump duces cavitation in the suction passage without drawing in fluid, and does not continue to do work and to build up an excessive and unnecessary pressure. As a result therefore unnecessary working and heating of the body of fluid with jcct to centrifugal force.

increase with greater speeds of rotation, it will usually be found that greater operating forces are required with higher rotative speeds; and by the construction described such greater operating v pressures are automatically provided for in accordance with this invention.

In' order to secure control over the position of the blades of the propeller and hence to maintain a predetermined selected speed condition of the propeller, means are provided for regulating the blade setting automatically in accordance with the speed of operation. For this purpose the member'30 is-provided .with an enlarged portion v -I00 which serves to house the regulator valve assembly. Mounted in the sleeve. III! is the regulator valve body I02 which as shown stands substantially radially so that it is itself directly suba cylindrical body portion having two spaced valve faces, I03 and I06. A passage I05 leads through sleeve IOI and into the part I00 where it communicates upon opposite sides with the two pressure conduits so that thezmaintained fluid pressure is supplied directly to the central portion of the valve I'M, between the two valve faces thereof. Being of equal projected area, thepressure between the two faces is balanced and the valve body moves freely irrespective thereof.

A passage I06 is formed through sleeve IOI in v line with valve face I03, the width of the valve face being slightly greater than the width of the pas-sage so that when properly centered the valve face will entirely close off the passage. Similarly passage I01. is related to and controlled by valve' face I04. Passage I06 communicates directly with intermediate conduits H0 and passage I0'I similarly communicates with inner conduits III which are arranged in suitable manner, preferably concentrically with conduit 90, so that the entire assembly comprising the three conduits can be constructed and cast as an integral unit.

Conduits I I0 and I H are arranged for selective communication with the blade actuating mechanism so that upon application of fluid pressure to one of said conduits, that fluid pressure is communicated to and made effective to actuate the blade adjusting mechanism of each of the blade socket-s of a multi-blade propeller in such manner as to increase the blade pitch; and similarly application of fluid pressure to the other of said conduits is made effective to control the pitch of each of the blades in the opposite direction. This communication is established by means of conduits I I3 and I I 4 extending through the rear face of each blade socket II and communicating respectively with outlets H3 and Ill formed in conduits H0 and III. The corresponding outlets of each group are located at the same radial distance from axis I4, the radial distance of the two groups being different. These conduits H3 and H4 thus are in direct communication with conduits H0 and III, respectively, and lead directly into the interior of each blade socket where suitable means are provided for effecting an increase in the pitch angle of the blade upon fluid pressure being supplied to conduits I I0, I H and for effect- As shown it comprises i ing decrease of the pitch angle upon pressure being supplied to conduits I II, I I3. In the event that it is desired to supply pressure fluid to eflect actuation of the blade in only one direction and to utilize other means such as centrifugal force. or springs to cause the opposite blade movement, only a single such pressure conduit need be utilized.

Means are likewise provided for venting the,

fluid from one conduit during the supplying oi fluid to the other and for this purpose the sleeve IN is open at its radially inner end as shown in Figs. 1 and 3 so that fluid returning through passage I II and entering through ports I'I- can pass directly into the reservoir. At its radially outer end, the sleeve IIII is provided with a number of discharge ports II 2 so that fluid returning through trifugal force effective upon the valve body I 02 so that with the constantly acting force of the regulator springs I28, the valve body will be caused to move radially inwardly. As a result thereof, valve face I 04 will uncover passage I01 and the source of pressure fluid supplied through passage I05 will be communicated through port I07 into pressure conduit III.

- pressure fluid is delivered through the passages conduit I I0 and passage I06 can likewise be freely discharged into the reservoir.

For purposes of adjustment and operating control valve body I02 is provided with a cylindrical portion I I5 to which is connected a yoke member IIB upon opposite sides thereof and having a threaded socket I I1 formed therein. A lever arm H8 is threadedly and adjustably' engaged in the socket. Likewise extending outwardly from and fixedly attached to the sleeve ml is a pair of guideways I20. Slidably mounted upon guideways I20 is a friction clamp I2I having an adjustable bolt I 22 therein for varying the frictional engagement therewith, and formed at its outer side with a concave roller I23 adapted to engage the arm I I8.

Formed integrally with arm H0 is a yoke arm I24 having hooks I25 at either end thereof for engagement with tension springs I28. These springs are relatively elongated and such as to develop substantial force, having their opposite ends fastened to a convenient point within the casing, such as the hooks I27 formed integrally upon pump chamber 6|. centrifugal force, these two springs assume a somewhat arcuate position, but because of the consequent less direct line of action of the spring force, continue to urge the yoke-shaped arm I24 and arm I I8 radially inwardly and with a maintained force which is substantially constant at varying speeds or in which the variations are insignificant practically so far as the regulating action is concerned.

Roller I23 thus forms a fulcrum, lever IIB pivoting about its center, and through connection of the lever with the regulator valve body I 02 acts to urge the valve body radially inward against the action of centrifugal force which acts oppositely thereon. The force with which the Under the action of valve body is urged inwardly remains practically the same for any fixed setting of the roller I23 regardless of the speed of rotation as above described. However upon the shifting of roller I23 axially along arm II8, the effective lever arm of the spring force on yoke I24 is altered, a movement for example of roller I23 to the right as shown in Figs. 1 and 3-providing for the spring force being exerted with a greater lever arm. The lever arm through which this force is applied to the valve body is also increased by the same length but because it is already longer than the arm through which the spring force is applied. its length increases less in proportion and consequently there is a net increase in the inward force applied to the valve body, hence :balancing a greater centrifugal force effective upon the valve body. The opposite condition occurs upon movement of the roller to the left.

I it which lead into the several blade sockets andto the blade adjusting mechanism contained therein, being applied in such direction as to effect a change in the setting of the blades to decrease the pitch thereof so that with a lesser angle of pitch, the speed will tend to increase and be restored to its predetermined desired condition. Simultaneously with the supply of pressure fluid into conduit III, valve face I03 has moved inwardly to uncover the passage I06, thereby rpermitting fluid to exhaust from conduit H0 and from. the opposite side of the actuating piston, back into the reservoir through port II2. I

As the propeller increases its speed by reason of the reduced pitch angle of the blades, the added centrifugal force is effective immediately and directly upon the valve body I02 so as to cause the same to move radially outwardly to such position as to cut of! further communication from the pressure passage through the passage I01, the valve moving outwardly to such point that its outward centrifugal force reaches a condition of balance with the inwardly applied spring force. If this condition corresponds with the predetermined desired speed'condition as determined by the position of roller I28, the'valve body occupies such position that communication with both conduits II 0 and III is prevented. The valve body thus constitutes its own follow-up device, and because it is directly affected by'cen-' trifugal force itself, without the interposition of additional moving parts involving frictional losses, it is highly sensitive and quickly responsive to even quite small changes in speeds of operation. It will be further noted that the valve is rotated at the same speed as the propeller itself, and furthermore is positioned at a substantial radial distance from the axis of rotation so that centrifugal force effective thereon is quite substantial, and differences occurring from even small changes in speeds of rotation are highly effective to bring about the regulating action asdescribed above. This is highly desirable in connection with m-ulti-motored planes, in order to provide for operation of each of the propellers at such speeds as to avoid setting up objectionable vibrations, and to avoid the objectionable effects of beats from the operation of the two motors at speeds only a few R. P. M. apart. With the arrangement of the present invention a highly critical condition of regulation is provided, such that these operating characteristics in multiand results in outward movement of the valve body I 02 against the regulator spring action, caus- This supply of 11, ing the supply of pressure fluid into conduits I I and H3 to effect change in the position of the blade by increasing the pitch angle thereof, with simultaneous ventingof the fluid from conduit III. This produces a reduction in the speed of operation, which is similarly responded to by'the valve body to terminate the correcting application of fluid pressure, and to restore the system to its condition of stable equilibrium.

The construction of the regulator valve body as thus described likewise provides a control which is responsive to the rate of change of speed. inasmuch as a rapidly falling speed condition for instance will result in a greater degree of movement of the valve body I02 inwardly, to thereby open the port I01 more widely, to thereby supply pressure fluid ata greater rate from the source of pressure supply. The same is true of the reverse condition, the sensitive regulator body thus providing an accurate and sensitive control for such operating conditions as en:-

countered. v

The present construction provides a regulator construction which combines the features of stability through the normal working range. and at a sufliciently low idling speed, and a high degree of sensitivity particularly in the normal working range of speeds and blade angles. As will be evident, the movement of regulator valve body I02 results in a change in its radial position and hence in the centrifugal force effective thereon. To counterbalance this condition, the center of roller I23 is offset inwardly a slight distance from the line joining the point of connection to the valve body and the effective point of application of the spring force to lever I I8. Hence as the valve body moves outwardly, lever arm I I8 pivots about roller I23 and thereby its eflective length is-slightly increased, the arm in effect rolling about the center of the roller. Although actually a small valve, it produces a counterbalancing action and provides for securing the desired stability and sensitivity, the sensitivity with the construction disclosed actually increasingwith increase in speed in the operating range so that a very satisfactory condition in this respect is provided.

' for the operation of the regulating device, means are provided for shfting the position of roller I23 and predetermining or adjusting its position at any time during operation. As shown this means comprises a manual control member I30, pivotally mounted on a bearing member I3I carried by one of the engine bolts 22, and having suitable connection at I32 for a control wire, lever, or the like. The end of lever I30 within the cover plate 23 is formed with segmental gear teeth I33 which mesh with teeth I34 of a segmental pinion I35 carried by a rotatable shaft I36. Shaft I36 is rotatably mounted within the ring 25, and extends axially beyond the flange 26 thereof, being provided with an outwardly projecting arm I31 adjacent the inner surface of the flange 23. Arm I31 projects through a. bracket I33 formedintegrally with a ring I 33 rotatably received upon the outer face of ring 23.

.A snap ring 0 fitting within ring 20 serves to prevent axial movement of the ring I39 with revelop a balanced driving force and to avoid bindcircular movement taking place therebetween. Tongue I33 Isprovided with a slot I4I therein through'which arm I3'I projects, the slot being either straight or curved to provide for securing the proper increments of rotation of ring I39 in responseto the actuation of lever I and the movement of the arm I31.

A cam ring I having a central peripheral.

groove I40 therein is mounted upon the outer face of ring I30, and carries a flxed pin I46 which extends radially inwardly thereof through a spirally arranged slot I41 formed in the ring. I39, and into an axially arranged slot I48 formed in ring ,25. As a result of this construction, and upon rotation of ring I33 about its axis, spiral slot I41 travels with respect to pin I 43 and because the cam ring I is held against rotational movement by the engagement of pm I 46 in axial slot I48, the entire pin and cam ring is caused to move axially under the guidance of pin I46 in slot I48. rallty oi such pin and slot means are provided around the periphery of the ring in order to deing of the ring. any tendency toward binding being further reduced as a result of the full lubrication of the parts exposed within the reservoir,

and by reason of the relative rotational movement simultaneously taking place between the cam ring and ring I33. Accordingly movement oi lever I30 is made effective to produce a predetermined axial shifting in the position of cam ring I. the particular relationship depending upon the contour of the cooperating arm and slot MI as previously described.

, In order to transmit this movement of the cam block into a corresponding movement of the roller I23, diametrically opposite cam followers I00 carried by levers I5I are engaged within the groove I45. Levers IliI are pivotally mounted upon fulcrum arms I02 carried by the brackets I20, and are adapted to be rocked thereon in response to movement of cam ring I. 'The levers at their opposite ends are preferably connected together by a cross strut I53 and have outwardly extending parts I54 each formed with a clevis ,engaging lugs I55 formed upon the bracket I56 to which the friction clamp I 2I is attached. As shown. movement of the cam ring I axially results in pivoting of lever arms 'I5I and the consequent movement of the friction block I2I axially over the supporting rod I20. Thus in response to adjustment of the lever I30 either manually or by instrument control, the fulcrum roller I23 is made to change its position, causing a change in the force with which the regulator spring acts upon the regulator valve body, to in'turn result in regulating the speed of operation of the proated to such position as to cause the fulcrum roller I23 to approach the point of application of the regulator springs. the moment of application of that spring force is reduced. thus causingthe valve body to move outwardly and to effect the trifugal force effective upon the valve body to' balance the regulator spring force is likewise re- A pluduced. This is provided for automatically by the regulator action as above described, the blade angle being progressively increased with a corregreater force is applied from the regulator spring to the valve body causing it to move inwardly to r predetermined level be that at which the reservoir is nearly full, about half full or but partially filled,

the control mechanism when correspondingly calibrated and adjusted will function quickly and within close limits of the designed setting. That fldelity of control is due to the fact that the valve body stands within and displaces fluid contained in the reservoir, with the fluid exerting a pressure effect upon the valve body that tends to oppose the action of centrifugal force thereupon. As the level of the fluid is reduced by depletion, that opposing force is lessened with the result that the valve body will move outwardly and reach equilibrium at a slower actual speed of rotation than that for which the control I is set, thereby indicating to the pilot the loss of or reduction in the quantity of fluid in the reservoir.

. To facilitate determination of fluid deficiency the manual for actuating the lever I30 of the propeller control is closely associated with the engine speed indicating device, such as a tachometer, all of which is schematically shown in Fig. '3 of the drawings, where an articulated motiontranslating means, such as the links I60, I8I and'rocker I02 Joins the lever I30 at I32 and ends at a lug I08 of a rotatable or oscillatable ring I04. The ring I64 is disposed for oscillation about the housing of a tachometer I85 through the agency of a handle I68. As is customary, the tachometer I05 is geared to the drive shaft I2 by the gear, elements I61 and I68 and a shaft element I60 which operates to move an arrow or pointer I10 over a scale I1I in accordance with the speed of the shaft I2. The graduations I12 of the scale operate as an index of the engine R. P. M. and also function as an indication for the setting of the propeller control.

As one example, for take-oil the propeller control is moved to the corresponding indication, under which conditions the propeller should be at the full forward position or high speed setting, which for purposes of illustration may be assumed to be 2800 R. P. M. as indicated in Fig. 3. The engine will accordingly have been adjusted as respects throttle and the like, thereby making use of full military power which should result in the engine settling to a top speed of 2800 R. P. M. While take-off" has been mentioned as a specific example under which notation or test of fluid level may be made, it is a fact that the test may be made at any time while the aircraft engine is self-operative. Thus, if the engine settling speed is the same, as that indicated by .the propeller control setting.- that is, if the tachometer arrow I10 becomes coincident with the arrow I14 of the propeller control, then'the indication is that the liquid level of thereservoir is. as designed. Howeverithe tachometer arrow I10 may assume a position atengine settle speed that is out of coincidence with the propeller control arrow I14,

reservoir is other than that intended. If the tachometer arrow fails to reach the position of coincidence as indicated by full lines in Fig. 3, and stops short of that position, such as at the dotted line position indicated by I10a, then there is an indication that the liquid level of the reservoir is low and that replenishment thereof should be made reasonably soon or at the earliest conven ience. A further check on the foregoing can be made at any time while in level flight. An opportune time to do so is while flyin under military l wer.

The invention thus provides a highly accurate and stable though sensitive regulator device for maintaining control over the blade positionings and over the speed of operation. In use, a desired speed condition is maintained with such accuracy that objectionable beats from multi engines are avoided. Being self-contained the system is less subject to failure and the fluid itself is that best adapted for the purpose. The adjustable control provides for securing regulation of the operative condition at a selected range, and serves in the normal operative range, as a proving device for testing the condition or sufliciency of the fluid medium.

While the form of apparatus herein described constitutes a preferred embodiment of the mvention, it is to be understood that the invention is not limited to this precise. form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claim.

What is claimed is:

In a hydraulically controlled constant speed variable pitch propeller having a reservoir rotatable therewith and enclosing a quantity of fluid pressure medium, with pitch control apparatus including a governor valve immersed in the medium and responding to the combined effects of centrifugal force and flotation of the valve in the medium for controlling the blade pitch to effect propeller operation consistent with a predetermined selected speed, the combination of means for detecting a variation in flotation of the valve in the fluid pressure medium, and compensating for the influence of the varied flotation upon the response of the valve to effect selected speed operation, said means including a tachof both the needle and index with a selected point on the scale of the tachometer indicating other than a, prescribed quantity of fluid medium in the reservoir and hence a variation from the prescribed flotation force applied to the valve and which indicates that the level of the liquid in the I WERNER J. BLANCHARD. CHARLES 3. J. MacNElL.

REFERENCES crran The following references are of record in the tile of this patent:

Number Number 1e UNITED STATES PATENTB-- Name 1 Date .Sperry May 2, 1933 Wiegand Jan. 15, 1935 Gausmann June 4, 1940 Olsson May 13. 1941 Adler Nov/ .418, 1941 Blanchard, etal. Jan. 5, 1943 Codebecq 1.51.... Mar. 17, 1942 Hammond Jan. 5, 1943 FQREIGN PATENTS Country Date Australia July 3, 1941 Great Britain Aug. '7, 1936 Germany Aug. 30, 1984

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