US2417870A - Propeller control - Google Patents

Description

March 25, 1947. v 1.4:. HMNES v 2,417,870

PROPELLER CONTROL Filed May 10, 1945 2 Sheets-Sheet 1 INVENTOIR Y Z 'J'afinff/aznas Y BY v o I f 1.14.00, Mo -4 7! 7797 I ATTORNEYS March 25, 194:7. J. F. HAINES 2,417,870

PROPELLER CONTROL Filed May 10, 1943 2 Sheets-Sheet 2 INENTOR 4067? ff/ z'ns W, M fwfif ATTORNEYS Patented Mar. 25, 1947 UNITED STATES PATENT FFICE PROPELLER CONTROL John F. Haines, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application May 10, 1943, Serial No. 486,377

4 Claims. 1

This invention relates to controllable pitch propellers in which a fluid medium under pressure is lead to control apparatus that respond to predetermined conditions for eiiecting a prescribed control of the propeller apparatus.

One object of the invention is to provide a control valve unit operable to effect charging of an accumulator, to prevent dissipation of the energy stored'in the accumulator, and to unload the pump and delivery system if its output reaches too high a value.

Another object is to provide a control valve for a fluid actuating circuit that is characterized by means permitting a build up of pressure in a chamber to a preselected value, and then operates upon continued working of the pressure creating means to unload that means or the delivery line leading to the control valve, yet retaining the charge of pressure in the chamber for subsequent and selected application.

Yet another object of the invention is to provide a control valve for control of a fluid circuit in response to the domination of accumulator pressure opposed by a resultant of spring force, centrifugal force and pump pressure.

Still another object is to provide a pressure limiting means responsive to the dominance of accumulator pressure over the combined effect of pump pressure, centrifugal and spring force to control the load superimposed upon the pump.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a view of a propeller mechanism, substantially as indicated by the line and arrows ll of Fig. 2.

Fig. 2 is a view indicated by the line and arrows 22 of Fig. 1.

.Fig. 3 is a sectional view radially of the propeller hub and through a control valve substantially as indicated by the line and arrows 3--3 of Fig. 2 and Fig. 4.

Fig. 4 is an elevational view of the valve unit looking at its mounting face substantially as indicated by the line and arrows l l of Fig. 3.

Fig. .5 is a top plan view of the valve unit with part of the cover plate removed, substantially as indicated by the line and arrows 5-5 of Fig. '3.

Fig. 6 is a transverse sectional view through the valve unit substantially as indicated by the line and arrows 6-6 of Figs. 3 and 5.

Fig. 7 is a schematic illustration of the fluid circuit embodying a modified form of control valve.

Fig. 8 is a detail view in section of sealing means for the junctures of fluid passages.

With particular reference to the drawings, i0 indicates an engine nose or gear casing from Which projects in rotatable relation a propeller shaft l2 provided with splines It for reception of cooperating splines l6 distributed around the bore of a propeller hub l8, providing a plurality of sockets 2D for mounting each a propeller blade 22. The hub I8 is retained upon the shaft l2 by the conventional mounting nut which forces a rearward extension 24 of the hub onto a rear cone 26 carried by the shaft l2, and a spinner 28 is mounted thereon in any convenient manner and which takes into consideration a nose ring 36 providing clearance through the bore of the shaft l2 for cannon fire. Ineach of the blades 22 a chamber 32 provides, for reception of a torque applying unit consisting of a chamber 34 and radially movable piston 36 adapted through cooperating splines 38 to rotate the blade 22 about its longitudinal axis upon lineal movement of the piston 36 into and out of the chamber 36. Fluid pressure is admitted to the outer end of piston 36 through a tubular connection 46 leading from a chamber 42 which is fed by a transfer tube 44, while the inside end of the p ston 36 responds to fluid pressure admitted through the transfer tube 66.

The transfer tubes i l and 46 each communicate with control passages 48 and 56 embodied in a regulator plate 52 mounted on the hub extension 24 and forming one wall of a reservoir 56. A cover plate 56 closes off the reservoir and is maintained in position by screw devices and the like 58, while its inner periphery carries a fluid seal 59 engaging a cylindrical sleeve 66 of an adapter sleeve 62, projecting across the reservoir to engage a similar seal 66 carried by the regulator plate 52. Thus the reservoir 56 is formed by the regulator plate 52, cover 56 and the adapter sleeve 62, defining an annular chamber surrounding the hub extension 25, it being adapted to contain a quantity of pressure operating fluid and enclose control elements for the propeller mechanism. The regulator plate 52 is mounted on the hub extension 24 so as to be substantially concentric with the propeller shaft l2, and it is there maintained by means of a sleeve nut .66 threaded on to the hub extension 2t and thrusting against the plate 52, the sleeve nut being concentric with but radially inward of the adapter sleeve 82.

The adapter sleeve 62 is retained against rotation by means of a plate 68 mounted on the easing I by means of a screw device i0 and through which plate 68 screw devices enter into the cylindrical portion 60 to retain the two parts in clamping relation. The plate 68 is appropriately grooved at the juncture with the sleeve 60 to oscillatably guide a control ring I2 having an arm 14 and a tooth portion I6 engageable with a plurality of pinions I6 carried by shafts-'80 journalled in the cylindrical portion 60 of the adapter sleeve. The shafts 80 have a high lead portion 82 threadable into and out of a grooved ring 84 within which follows a shoe 86 of a carriage 88 adapted to operate upon a governor valve unit. In doing that, the carriage 8-8 moves a fulcrum roller 90 fore and aft of a lever 92 pivoted to a valve plunger 94 guided in a porting sleeve 86 mounted in a block 98. The block 98 comprises a housing of' the governor valve I00 securely mounted on the regulator plate 52 and designed to distribute a. source of fluid under pressure from a pump delivery passage I02 to either one of two control passages I04 and I06. In doing this, the valve plunger '94 is arranged to be radially disposed with respect to the axis of rotation such as to respond to centrifugal force in moving radially outward in compressing a spring I06 supported by an arm of the block 98 and engaging a lever '92, which it.constantly thrusts radially inward about fulcrum roller 96. Thus, movement of the carriage B8 fore and aft of the lever 92, which may be done by sliding it along the ways I10, alters the balance of forces acting upon the valve plunger and thus operates to define the speed level at which the valve plunger 94 will effect its regulation or governing function. The adjustment of the fulcrum roller 90 is accomplished through manipulation of the lever I4 that rotates the screw shafts, all as has been described hereinabove and specifically set out and claimed in the patent to Blanchard et al. 2,307,102.

Distinguishing over the aforementioned patent, the structure now under consideration also includes a toothed portion I I2 adapted to engage a spur. Wheel carried by a rotary shaft I I4 of a continuous flow typepump or pressure developing means I-IG. The pump has an intake II 8 near the periphery of the reservoir 54 and discharges into a passage I26 which leads to a control valve assembly I2I and thence by passage I22, I24 to an accumulator, and by the aforementioned passage I02 to the governor valve assembly I00. Herein, the accumulator comprises a semi-circular groove I26 formed in the peripheral flange I28 of the plate 52 whichis covered by an impervious flexible partition I30 anchored in place by a ring member I32 providing a similar semicircular groove I34. The partition I30 therefore divides what would be an annular chamber of circular cross section into two compartments in which that formed by the groove I26 and flexible wall comprisea preloading chamber having air under pressure, and in which the chamber formed by the groove I34 and flexible wall provide an expansion chamber adapted to be charged by fluid under pressure from a pump, finding its way there by means of the passages I22 and I 24. The passage I24 comprises a tube as an insert in a thickened portion of the ring I32 and opens into the groove I34 by means of a large number of bores I36.- Thus fluid under pressure from the control valve I2| regularly flows through the passages I22 and I24 on its Way to the governor valve I00, but on stoppage of flow at the governor valve, an increase of fluid delivery into the passage I22, the fluid flows under pressure through I36 into the expansion chamber tending to collapse the flexible wall I30 into the preloading chamber.

Specifically with respect to the control valve IZE, it is interposed in the delivery line of the pump, between these control devices such as the accumulator and the governor valve, substantially as shown in Figs. 2 and '7. As for specific structure, the control valve unit is characterized by a block or housing I40 mountable on a pad of the plate 52 by means of screw devices I42 so as to be in fluid tight relation therewith, and has two ports I44 and I46 in its mounting face I48 for alignment with the orifices I50 and IE2 respectively opening into the passages I26 and I22. The block I40 provides a well I54 into which both ports I 44 and I46 open, the well being divided by the bottom wall of a cup I55 lining the well for a part of its length and dividing the well into a receiving chamber I58 and a pressure chamber I60. The side wall of the cup or liner IE6 is apertured at I62 in alignment with the port I44, and the bottom wall provides a plurality of openings I64 which are covered by a valve disc I55 under the urge of a spring I66 guided by a pin I68. Thus, fluid under pressure flows from the pump through passage I20, orifice I50, port I44 and the aperture I62 into the receiving chambar, and when the pressure becomes great enough it flows through the openings I64 past the valve disc I into the pressure chamber of the control valve. From the pressure chamber the fluid under pressure may flow through the port I46 into the passage I22 and on to the accumulator and governor valve as has been explained.

Both the pump pressure and the accumulator pressure are functions, or elements, of the control for the hydraulic system, and. is made use of by taps or leads therefrom to a piston of differential or fractional area, and a spool valve. The tap into the pump pressure involves a triangular or other recess I76 in the mounting face Mt into which the pump pressure port I44 opens, and from which a drill passage I72 leads to communicate with a cross bore I13 and a chamber I14 surrounding a piston of smallarea I I6, joined to a larger area I18, and so situated that the difference in area of the two piston portions is always exposed to the pressure in the chamber I14, and consequently the pressure of fluid from the pump delivery. The end face of the larger piston portion H8 is covered by a plate I80 held onto the block I40 by screw devices -I82, the plate also covering the receiving chamber I58 and retaining the well liner I56 in place. A chamber I84 is thereby provided at the end of the piston portion II B, which chamber is always under the potential of the accumulator pressure through drill-ways I86 and I88 leading from the chamber I84 to a recess I90 cut in the face I48 of the block and opening into the port I46 leading to the accumulator.

In axial alignment with the bores containing the differential piston there is a valve chamber I 92 along which there is movable a spool valve I 94 under the thrust of the differential piston in response to accumulator pressure, opposed by the force of a spring I96 bottoming in a socket I98 of a; plate 200 closing the valve chamber, I92 where it is retained by screw devices 202. The spool valve I94 is provided with an annular groove 2B4, which when the valve is depressed a predetermined amount against the spring I96, operates to connect a drain port 266 with a passage 2G8 opening into a large drill hole 2 I leading to the aforementioned triangular recess lit]. The spool valve and passages just mentioned provide a quick relief passage for the pump delivery line whenever the accumulator pressure through the port its becomes strong enough to overcome the combined effect of the spring force from Hit, the pump pressure on the difierential area of the piston, and the centrifugal force due to. rotation of the supporting plate 52. To take advantage of the centrifugal force, the valve unit so mounted on the plate 52 that the spool valve 594 will be capable of movement radially with respect to the axis of rotation and be in aiding relation to the spring and pump forces.

The control valve structure of Fig. 7 is functionally the same as that just described, the structural difierences being as hereafter described. The control unit itself is embodied in a capsule like member 2 l2 insertable within a chamber 2 M of the block i450 and provides a valve chamber 296 housing the spool valve I94 and its spring ISt. In axial alignment with the spool valve and arranged to bear against the same is the differential piston exposed to the chamber lit and I84. Communication bet-ween the large end I18 of the piston and the pressure chamber IE0 is effected through a groove 2 i8 and drilled passages 22d and 222 that open into a groove 22 6 of the member 2I2 that is aligned with a bore 226 extending between the chamber 214 and the pressure chamber N50. The differential area of the piston is exposed to pump pressure through cross bores 2% extending from the chamber El i to a wide peripheral groove 23!! in the member 2!2 which in turn is aligned with a passage 232 through the block Illa and port 234 of the liner I55 into the receiving chamber I58. The pump pressure is also conducted from the receiving chamber 58 to the groove 294 of the spool valve by means of a passage 236 extending from the groove 235 to an annular undercut 23% opening into the valve chamber 2 it in substantial registry with the groove 264 of the spool valve. The groove 264 of the spool valve, here as in the form first described, extends sufficient along the length of the valve member to span at least a part of the opening to the pump pressure and also a drain port or ports 25!] leading to an annular groove 2G2 of the member 2I2 aligned with the ports 266, so that depression of the spool valve I54 against the spring 196 will unload the pump The fluid circuit of the system is clearly illustrated in Fig. 7, and demonstrates that under normal conditions, when the regulator is rotating, the pump will be driven to deliver fluid under 5 pressure to the chamber 158 and passages and chambers connected. therewith including the chamber its, the groove 2% and the pressure chamber 160. From the chamber I the fluid under pressure is communicated to the chamber I84, the governor valve, and the expansion chamber of the accumulator whose loading chamber I26 determines the potential of the chambers HM, I613 and I84. When the pressure in those chambers reaches a certain predetermined value the differential piston will overcome the opposing force exerted on the piston by the pump pressure in the chamber I'M, the force of the spring Iifi and the centrifugal force on the spool valve, and will move the valve ifit radially inward to connect 6. the pump line with the drain port 205 by which th pump output is returned directly to the reservoir until there occurs a drop in pressure in the accumulator side of the check valve I65. Movement of the spool valve Ids is facilitated by relief passages I in the head thereof and a passage l9? opening from the valve chamber to the reservoir. Once the valve i94- starts to move, it continues until arrested by engaging the end of the casing, since the pump pressure applicable upon the fractional area is immediately and suddenly relieved with no dimunition of pressure on the end of the piston I78 in chamber I84. The piston H8 will follow the spool valve to the bottom of the chamber 2H3 where those elements are retained until the pressure in the accumulator chamber I3l falls so low as to be dominated by the combined effect of centrifugal force and spring force upon the elements H8 and I94. When that occurs, the spool valve E94 moves radially outward to close the pump relief port 296, in response to which the pump pressur is thus applied to the difi'erential area of the piston in aid of the outward movement of the members, and adding to the force opposing the reduced accumulator pres sure in chamber #841. The valve 194 is therefore instable insofar as it snaps or moves rapidly from one position to the other due to the position cut off and application of definite pressure forces controlling its position. That provides a positive and reliable control for a fluid circuit without attendant hunting or fluttering of the control valve.

The pressure is subject to dimum'tion-whenever the governor valve 94 is moved from its equilibrium position to open communication from the pressure line N32 to either of the control passages I94 or I66. Movement of the valve is the result of domination of either centrifugal force of rotation casting the valve plunger 94 radially outward, or the opposing force of the spring I08, both of which tend to rock the lever 92 about the fulcrum roller 98. When the spring force and the sentrifugal force are balanced the valve 95 will be in the equilibrium position in which neither control passages I04, I86 will be open to the pressure line at 12. Aside from propeller operating con ditions that may call for a shift of blade pitch, the equilibrium position of the valve 94 may be upset by movement of the fulcrum roller 95), which is operative for the most part in selecting the speed level at which the governor valve will control for operation of the propeller. Such fulcrum movement is of small amount and results in changing the relation of, and the length of the moment arms through which centrifugal force and spring force act. However, the fulcrum is capable of movement to extreme positions along the lever 92 so as to negative any automatic operation of the governor valve, and subject the mechanism to full manual control. If the fulcrum is moved to an extreme forward position, or to a point on the opposite side of the line of spring pressure, say'to the dotted line position shown in Fig. '7, then the balance of force on the lever will be so disturbed that the spring force and centrifugal force will be in aiding relation, which will cause the valve member 9 to be cast radially outward connecting the pressure of line I92 with the control passage IE6, calling for an increase in blade pitch. Due to the selected position of the fulcrum roller the governor valve is without corrective or recovery properties and the shift of blade pitch continues until the feather position is reached, as shownin dotted line posi tion of Fig. 2. Movement of the fulcrum roller to the other extreme, or to the extreme end ofthe lever 92, so shifts the relation of spring force and centrifugal force on the valve that a shift to decreasing blade pitch passes through zero to a negative value, suitable for braking.

The control valve unit, along with the accumulator provide a continuing source of fluid pressure for eifecting a shift to the feathering position or braking position and back again to the working range of pitch settings, even though the propeller mechanism may be at rest. The unloading valve assures that the continued flow from the pump will be returned to the reservoir whenever the accumulator is charged to the predetermined potential, and thereby guards against disruption of the fluid circuit. Thus,'the fluid circuit is always charged with fluid under suflicient pressure to effect the contemplated change in blade shift. It is understood, of course, that the fluid under pressure in the control passages 48 and 50 is led to and from opposite sides of the piston 38 of the torque applying unit. When pressure is applied through one of the passages the other is opened to drain back into the reservoir. Since the regulator plate 52 is set against the hub 18 in abutting'relation, the fluid connection is made in the manner shown in Fig. 3, where aligned passages 244 and 246 are counterbored to receive a tubular dowel 248 circumscribed by a compressible rubber sealing ring 250. Clamping of the plate 52 to the hub, which is accomplished by the sleeve nut 66 threading on the hub extension 24, compresses the ring 250 sufliciently to establish a fluid tight seal. In Fig. 8, a similar method is shown for sealing the fluid connection between the pump passage H2 and the passage I24 leading to the governor valve. There, aligned bores 252 and 254 are formed in the members 52 and I32 opening into the passages I22 and I24 respectively. In the face of one of the members, an annular groove is provided that is adapted to receive a flexible sealing ring 256 which when the members 52 and I32 are clamped together by the screw devices 258 is sufficiently compressed to afford the desired fluid seal. The fluid connection between the passage l24 and I02 may be similarly treated.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a system for controlling a hydraulically operated device, the combination of an accumulator for liquid under pressure, resilient means associated with the accumulator for varying the pressure therein in accordance with the amount of liquid present in the accumulator, a reservoir, a pump system connected with the reservoir and including a delivery chamber, means for limiting the pressure in the chamber to a predetermined value, a communication between the delivery chamber and the accumulator, a check valve mounted in the communication and adapted to open only in the direction of the accumulator, said pressure limiting means comprising a centrifugally actuated valve adapted to move radially outwardly of the reservoir to close a relief port from the delivery chamber to the reservoir, a piston having a fractional portion of its area exposed to pump pressure, said centrifugally actuated valve and said pump pressure acting in aidmg relation, and yielding means assisting the centrlfug'ally operated valve to move outwardly against the piston, and means exposing the full area of the piston to accumulator pressure for opposing the outward movement of said centrifugally actuated valve, whereby the domination of accumulator pressure moves the piston radially inward to open the pump delivery to the reservoir.

2. In a system for controlling a hydraulically operated device, a centrifugally operated valve unit for limiting the pressure of the system, comprising, in combination, a block adapted to be mounted on a rotatable support, said block having a bore in which is disposed a valve partition providing a delivery chamber and a pressure chamber, and a stepped bore all arranged to rotatewith a support, means providing fluid connection between the delivery chamber and the juncture of two of the stepped bores, and between the pressure chamber and the larger of the two adjacent bores, a piston disposed for movement in the adjacent bores having its larger area exposed to pressure of the pressure chamber and a fractional area exposed to the pressure at the juncture of the stepped bore, a spool valve engageable with the smaller end of the piston and adapted under spring force and centrifugal force to assist pressure in the receiving chamber for opposing pressure from the pressure chamber, and means whereby domination of the pressure in the pressure chamber will open communication between the juncture of the stepped bore and the outside of the unit, whereby development of system pressure to a predetermined degree will operate to shunt the pump delivery to the reservoir and by-pass the check valve.

3. In a system for controlling a hydraulically operated device, a centrifugally operated valve unit for limiting the pressure of the system comprising in combination, a block adapted to be mounted on a rotatable support, and having fluid connections with pressure developing means and accumulated pressure, a piston and spool valve loosely coupled but adapted for movement radially of a center of rotation, means including pump pressure admitted to a fractional area of the piston for urging the piston and valve, and fluid circuit means exposing an end area of the piston to the accumulated pressure whereby dom nation of the motive force of the accumulated pressure over the assisting forces of pump pressure, centrifugal force and spring pressure operate to connect the delivery chamber with the intake of the pressure developing means.

4. In a system for controlling a hydraulically operated device, a centrifugally operated valve unit for limiting the pressure of the system comprising in combination, a block adapted to be mounted on a rotatable support, and having fluid connections with pressure developing means and accumulated pressure, a. piston and valve for controlling fluid movement through the block upon radial movement of the valve relative to a center of rotation, said piston having a fractional area exposed to the output of the pressure developing means, and an end face exposed to the accumulated pressure, means exerting a variable force upon the valve for maintainin fluid connection between the pressure developing means and accumulated pressure, but subject to being completely overcome by the domination of accumulated pressure for by-passing the output of the pressure developing means, said valve being so instable under the application of opposing forces as to efiect quick and complete opening and closing of the communication from the pressure de-" 9 veloping means upon material domination of either of the said opposing forces.

JOHN F. HAINES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,210,295 Johnson Aug, 6, 1940 2,280,937 Thornhill et a1 Apr. 28, 1942 Number Number

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