US2557127A - Variable pitch propeller - Google Patents

Description

June 19, 1951 H. MAGILL VARIABLE FITCH PROPELLER Filed Dec. 50, 1943 NNN NNN .BY Wlan-ry' A11-tjrs Patented June 19, 1951 f- UNITED STATES PATENT OFFICE VARIABLE FITCH PROPELLER Herbert L. Magill, Chicago, Ill. Application December 30, 1943, Serial No. 516,258

Fig. 1 is a vertical sectional view, shown more or less diagrammatically, showing a preferred embodiment of my invention, with parts of the View being broken away for clarification.

Fig. 2 is a section of a detail construction of the friction device shown in Fig. 1.

The propeller I5 is shown as an aircraft propeller, but could be a propeller for use in any Vfluid medium. It is propelled in any suitable manner, as for example, by reaction jets, located at or near the tips of the propeller blades on the trailing edges thereof, and through which the exhaust from a gas pressure generator I9 is discharged. The propeller blades are so mounted that their pitch is automatically or manually changed as desired, as the plane varies in altitudes. At low altitudes the plane is propelled principally by the forced rotation of the blades I5 by the reaction jets, but at high altitudes the plane is propelled by the reaction jets on the propeller blades, augmented, if necessary, by additional reaction fjets.

Mechanism for varying the pitch of propeller Y blades Attached to and extending forwardly from the pressure generator is a mounting or housing 2 I2, within which is rotatably mounted the propeller shaft 2I3. Suitable anti-friction bearings 2I4,

ing 2I2. The propeller I5 is attached to the hub 221i in such a manner that the propeller 7 Claims. (Cl. T10-135.4)

v4:0 2 I5, are provided for this shaft within the housblades may be varied in pitch, as will now be described.

Attached to the forward end of the propeller shaft 2I3 is a hub 224, within which the inner blades 22D will be rotated about their longitudinal axes, due to the meshing of the gear 221 with the gears 22d on the inner ends of the propeller blades.

Each of the propeller blades is provided with a conduit 222, which extends longitudinally of the blades and have their inner ends enlarged, as at 222e, and through which the exploded gases from the pressure generator I9 are conducted to the reaction jet nozzles located on the rear or trailing edges of the propeller blades, as previously dsecribed.

The propeller shaft 2 I3 is hollow, and the tubular conduit Il8 extends axially therethrough. At its rear end the tubular conduit |18 is rigidly connected to the propeller shaft by a bracket or supporting member 2 I6. i

The forward end of the tubular conduit I'I8 is provided with branch conduits, one for each propeller blade. Where the propeller has but two blades, as shown in Fig. 1, the conduit Il is bifurcated, or terminates in a T-shaped hollow member 2I3, the arms 2I9 of which extend laterally into the enlarged ends of conduits 22| and 222, extending lengthwise of the propeller blades 220, and through which the exploded gases from'the pressure generator I9 are conducted to the reaction jet nozzles located on the outer trailing edges of the propeller blades.

In an airplane having means for propelling the same either by employing reaction jets or by rotating propellers, it is desirable that the construction be such that the change from one means of propulsion to the other may be accomplished by either, and the pitch of the propeller blades be controllable when being propelled by rotating Propellers to maintain the rotation of the propellers at a constant speed by changing the pitch of the propeller blades as the density of the atmosphere may vary by reason of a change in altitude of the aircraft in ight to provide the most efficient pitch for the propeller blades consistent Vwith the power being applied and the atmospheric density.

For instance, in ascending or descending under normal conditions, the change from propulsion by reaction jets to propulsion by rotating propel- 1ers, or vice versa, and the change of pitch of the blades of the propeller during such time that they supply the propelling means is desirable to be accomplished at the will of the pilot, and preferably by automatically operated mechanism.

In the present invention the change is made by merely changing the pitch of the blades. Means are provided for. changing and for also reversing 3 the pitch of the blades, and there are times when it is highly desirable that this change pitch mechanism be manually controlled, as, for instance, in dive bombing. When nearing the limit of a dive under bombing conditions the pitch of the blades may be manually controlled to cause them to function as brakes for a brief period of time in order to relieve strains on the dirigible mechanism of the plane. In reversing the pitch of the.-

blades for braking action to retard forward movement of the aircraft, there is a reversal in the direction of the air-screw effect but the propeller continues to rotate in the same direction.

The mechanism for varying the pitch of the propeller blades comprises a hollow cylindrical shaft 22 3, concentrically mounted within the propeller shaft 2l3, and is relatively rotatable therein, as by means of the anti-friction bearings 225a and 225. Mounted on the outer end of the shaft 223 is the bevel gear 227 that engages bevel gears 22S and 226a on the inner ends of the propeller blades for rotating the blades, as described above. lThe hollow shaft 223 has a spiral thread or gear 2239- thereon, which is engaged by an internal spiral groove in a sleeve 223i. The sleeve 223b is slidably mounted within the propeller shaft 2l3. An outer sleeve 22%a is slidably mounted on the drive shaft 213. These two sleeves are connected to slide together along the drive shaft, but are prevented from turning on said shaft by a plurality of blocks 22ilb, which are slidably mounted in slots 22Bc in the wall of the propeller shaft 2I3. Screws 22T!d hold the sleeves and blocks together so that they may slide as a unit longitudinally of the shaft 223.

The means for moving the threaded sleeve and associated parts along the shaft 223 comprises a yoke or depending arms 220e, pivotally mounted, as at 22if, and having their lower ends at opposite sides of the hollow shaft bifurcated, as at 225g, engaging blocks 22Eih pivoted to an outer ring member 22]i at opposite sides thereof, and which in turn surrounds the sleeve 220a. Antifriction bearings 2205 are provided between the ring 226i and the sleeve 226e, and thus the sleeve 22a, propeller shaft 2|3, and hollow shaft 223 normally turn together, while the ring 220i remains stationary so long as the arms 22]e remain stationary.

It will thus be seen that when the arms 226e are turned about the pivot 220f the ring 22Eii is moved along the propeller` shaft, and. due to the ball bearing connection and construction the sleeve 226e, and with it the sleeve 223', are moved along the hollow shaft 223, thus rotating the latter for rotating the gear 221, which in turn rotates the gears 226 and 2253a for varying the pitch of the propeller blades.

The means for automatically and for manually rotating the arm 22]e will now be described.

The arm 220e is extended beyond its pivot 22Df, and is provided with a toothed quadrant 220k, which is adapted to be engaged by a self-locking worm 2201 on the shaft of a reversible motor 22cm, adapted to oscillate the arm 22%e in either direction. The operation of the motor is controlled by an automatic switch mechanism I, or by a manually operated switch mechanism 2 (Fig. l). The automatic switch mechanism l comprises a housing 2X, which is rigidly connected to the housing 2| 2 and has rotatably mounted therein a gear 3 which meshes with a gear 4` rigidly mounted on the propeller shaft 2 I3. The gear 3 is rigidly mounted on a shaft 5, and a governor E is also mounted on this shaft 5.

Automatic governor for pitch control The governor B, which is of the usual centrifugal type, comprises a collar 7, rigidly connected to the shaft 5 and rotatable therewith. This collar has connected thereto the usual centrifugal ball and link connection 8, which is connected to a sleeve 9 slidable along the shaft 5. A spring le is mounted on the shaft 5 between the collar l and sleeve S for normally holding the latter in its outermost position. Connected to the sleeve 9, as by means of a ball bearing 2a, is a switch operating shaft 3a, having rack teeth 48L thereon. The shaft 3a is free to move horizontally through a cylindrical casing 2y, which is slidably supported at its inner end 2m in a bearing support 2k rigidly attached to the open end of the housing 2X. The bearing support 2k has an extension 2S, to which are attached the two fixed elements 4m and lb of a multiple switch 6a.

The casing 2y has extensions. 23, to which is attached the movable element 5a ofv a multiple switch 6a extending outwardly through the slot 2n in the extension 2s of the bearing support 2k, and is yieldingly held in adjusted position by a spiral toothed gear 2P, rotatably mounted in a spring-pressed block 2q slidably mounted in a bore 2f in the lateral extension 2t of the casing 2y. The spring compression is controlled by the threaded bolt 2W. The gear 2D, meshing with the rack teeth 4, holds the casing 2y in adjusted position without offering too much frictional resistance to the endwise movement of the shaft 3a.

The switch operating shaft 3.a doesnot rotate but is adapted to be moved longitudinally of the shaft 5 by the centrifugal governor mechanism 6. Likewise the casing 2y, which is slidably mounted on the shaft 3a, does not rotate but is adapted to be moved in either direction by the frictional contact between the spiral toothed gear 2p and the rack teeth lia by a corresponding movement of the shaft 3g until the movable element 5a contacts either of the Xed elements 4m or 4b o-f the multiple switch 5a. After such contact the Sleeve 2y is prevented from moving further in that direction, but the shaft 3a may continue to move in the same direction if the speed of the governor continues to increase or decrease, as the'case may be.

The movable element 5a of the switch (ia is provided with a pair of contact members 'la and 821. The contact member 3a, when at one extreme position, is adapted to engage a pair of contact members ib, 2b, and the Contact member la is adapted to engage the contact member 31U on the fixed portion lib of the switch 5a, When moved in the opposite direction the terminal 8a is adapted to engage the two terminals 5b, 6b, of the fixed portion of the switch, and the terminal 'in will Contact the terminal 'lb of the fixed portion of the switch and make electrical connections therewith.

Elcctric circuits for change pitch mechanism When the plane passes from one density of the atmosphere to another, as when ascending, it passes into rare atmosphere, the propeller, having less resistance due 'to the rarity of the atmosphere, will tend to move faster, and this will cause the balls of the governor 2 to move out by centrifugal force, causing the sleeve 9 to move to the left in Fig. l, and this in turn will move the sleeve 3R, and with it the movable element 5a of the switch, thereby bringing the terminals la, 821, in contact with the terminals lb, and 5b, 6b, respectively.

Y y `When these connections are made the electric current from a suitable source of electrical energy, as the battery 8b, will cause the motor 220m to rotate in one direction for increasing the pitch of the blades, as will presently be described.

In passing into a denser atmosphere the reverse will be true, and the electrical connections will be changed so that the motor will be rotated in the opposite direction for decreasing the pitch of the propeller blades. The motor employed is shunt wound, and the reversal of the motor is effected by reversing the field which is secured by reversing the flow of current through the shunt winding from the battery.

Assuming that the movable element 5EL of the switch 6a has been moved to the left in Fig. l and made electrical connections with the terminals on the fixed portion of the switch, and assuming that the blade switch 9kb/which is connected to the terminals i0, 2 and 3, is now in contact with the `terminals 4c, 5C and 6G, the current may be traced as follows:

From the battery 8b through the switch 350 to the `main line B, terminal 8a, where it divides, one portion passes to terminal 6b, through a conductor 3e to the terminal ic across the switch to the terminal IC, and from the terminal i@ through the conductor ic to the terminal 50 of one of the brushes of the motor, and thence returning through the other brush and terminal 9c of the motor, thence through the conductor Id, back through the main line A to the ground, as at 2d.

The other portion of the current passes from the terminal 8a to the terminal 5b through a conductor to the terminals 6c and 3c of the switch 9b through the conductor 3d to the ter. minal 3d of the field winding, thence through the eld to the other eld terminal 5d, through conductor Sd, terminal 2c, switch 9b, terminal 5c, thence through terminals lb, la, and nally through conductor 6g and conduit A to the ground 2d. The rotation of the motor causes the arms 22|)e to rotate in one direction, which in turn moves the sleeve 223b along the cylindrical shaft 223, thus rotating the cylindrical shaft 223 independently of the propeller shaft 2 I3 for causing a change in the pitch of the propeller blades.

The motor 22E!m continues to operate and move the sleeve 223b, causing the pitch of the propeller blades to continuously increase until the added resistance to the rotation of the propeller causes it to decrease its speed. As the speed decreases the governor 6 acts to move the shaft ila to the right, carrying with it the casing 2y and the attached movable element 5a, breaking the electrical contact between its terminals 8a and ia and the terminals 6b, 5b and lb, respectively, and stopping the motor 220m and leaving the blades of the propeller locked in a fixed position, by the self -locking worm 2261, with the toothed quadrant 223k of the arms 220e.

When the switch member 5a is moved to the right in Fig. l, as when the plane moves into denser air, and the speed of the propeller decreases due to this denser air, the contacts are made at the opposite side of the switch, thus reversing the current through the field and reversing the motor, Which in turn lowers the pitch of the blades through the gears 226, 221 and 226e. The circuit may now be traced as follows:

From the battery 8b through the main line B to the switch terminal 8a, terminal lb, conductor le, terminal 5, through the blade of the switch 9b to terminal 2C, conductor 6d to the terminal 5d of the field-1K1, back throughthe terminal 4d of 6. the field,'conductor 3d, terminal 3c, blade of the switch 9b to the terminal 60, thence through the conductor 2e, terminal 3b, terminal 1a, conductor 6g, through the main line A to the ground, thus reversing the motor.

The current through the brushes of the motor may be traced as follows:

From the battery 8b through the switch 350 to main line B, to the terminal 8a, through the ter-- minal 2b, conductor 3e to the terminal 4C, through the blad-e of the switch 9b to the terminal ic, con-v ductor lc, terminal 8c of the motor to the terminal 9C of the motor, conductor ld, and through theA main line A to the ground.

Thus it will be seen that when the propellers are controlled to be operated at any rotational` speed within its speed range by suitable manipu lation of a control valve or element, the mech-y anism just described will act to automatically cause the pitch of the propeller blades to increaseuntil the amount of power applied to the pro-r peller is no longer able to increase its rotational. speed against the increasing pitch of its blades, and will then act to lock the blades in a position of pitch most efficient for the maximum rota-- tional speed of the propeller with the amount of power being applied.

Likewise, with the propellers operating as above described, the motor 22@m will be caused to rotate in such direction as to automatically increase the pitch of the blades should the aircraft ascend, or decrease the pitch of the blades as the aircraft descends, to maintain the rotational speed of the propeller at a constant through variation of the atmospheric density.

The main line B is in series with the switch 350 (Fig. 1), so that when the ignition circuit for the pressure generator I9 is open the circuit for the motor 22Bm will likewise open, and the motor will not function.

It is significant that the automatic governor for propeller pitch control does not provide some specified pitch angle for a given number of R. P. M s of the propeller, but rather introduces another variable so that the governing means responds not only to changes in the power input to the propeller, but also thc fluid resistance to rotation of the propeller to provide a pitch for 'the propeller which effectively absorbs the power being applied by said power means to rotate the propeller.

Manual control for changing pitch of propeller blades When it is desired to vary the pitch of the propeller blades manually, the switch 9b is moved over to the opposite side in contact with the terminals 4e, 5e and 6e, so that the automatic operation of the switch mechanism for the motor 226m is ineffective. The switch mechanism 2 can then be operated manually so as to vary the pitch of the propeller blades. 'The switch mechanism 2 comprises a casing le, having a shaft Se extending therethrough, on which is slidably mounted a sleeve 9E having gear teeth lf on one side thereof. A lever 2f, pivoted in the casing, as at 3f, and having gear teeth df, is provided for shifting the sleeve. The sleeve is normally held in neutral orl rcentral position by springs 5f and 5f, which en gage on opposite sides of the sleeve se, as clearly shown in Fig. 5 of the drawing. Rigidly attached to the sleeve Se is the movable element if of a. switch, which is adapted to contact the stationtry members 8f' Sf, at opposite sides of the mov-- able element'if of the switch.

Since the switch 2 is constructed like the switch l, it is not thought necessary to repeat the description. It is believed to be obvious how the circuits may be traced, since they are similar to those involving the switch 5a, and consequently the tracing of the currents is not repeated.

It is though from the foregoing, taken in connection with the accompanying drawings, that the construction and operation of my device will be apparent to those skilled in the art, and that i changes in size, shape, proportion or detail may be made without departing from the spirit and scope of the appended claims.

i claim as my invention:

l. In an aircraft, a propeller having blades, reaction jets mounted on the propeller blades for normally rotating the propeller as a primary propulsion means for the aircraft, means to automatically vary the pitch of said blades to compensate for changes in air speed and barometric pressure, and means to reverse the pitch of the blades independently of said automatic means thereby to reverse the thrust of the propeller.

2. A propulsion device for use in fluid mediums, said device comprising a bladed variable pitch propeller, power means to rotate said propeller, a mechanism for altering the pitch of the propeller, and automatic means responsive to changes in the power input to said propeller and to the iiuid resistance to rotation of said propeller 5 for operating said mechanism to provide a pitch for the propeller which effectively absorbs and balances the power being applied by said power means to rotate said propeller, said automatic means comprising a first means that varies in accordance with the speed of the propeller, a second means operatively associated with said pitch altering mechanism and responsive to an initial variation in said iirst means for eiiecting a progressive change in pitch in said propeller in a direction that will oppose the change of speed causing variation in said first means, said second means including a third means providing a variable coupling between the first and second means for continuing said progressive change in pitch until final stabilization of the pitch and speed of the propeller has been established for the changed conditions under which the propeller is being rotated.

3. A propulsion device according to claim 2, in combination with means for selectively varying the pitch of the propeller1 by manual control.

4. A propulsion device according to claim 2, in combination with manual means for selectively varying the pitch of the propeller, means for reversing the pitch of said propeller whereby the propeller acts as a brake, and means to control the pitch of said propeller blades when in reverse pitch by said manual means.

5. A propulsion device for use in aircraft, said device comprising a bladed variable pitch propeller, power means to rotate said propeller, a self-adjusting governor mechanism responsive to the speed of rotation of said propeller as it may be affected by variations of power input', air speed, and barometric pressure to control and select the rotating speed and pitch of said propeller, said mechanism comprising a governor responsive to the rotation speed of the propeller, an arm operatively connected to said governor and having longitudinal movement in response to changes in the speed or rotation of the propeller, a contact member projecting from one side of said arm and movable with respect to said arm longitudinally, means associated with the arm dll and contact member to present a resistance to movement of said member with respect to said arm, a pair of contacts positioned to either side of said member and spaced therefrom, electrically controlled means adapted to vary the pitch of the blades of said propeller, electric circuits connecting said last-mentioned means, said Contact member, and said contacts whereby an increase in speed of rotation of said propeller will move said member against one of said contacts to complete a circuit through said last-mentioned means to increase the pitch of said propeller until the speed of rotation of the propeller becomes stabilized by the said increase in pitch, while a decrease in the speed of rotation of said propeller will move said member against the other of said contacts to complete a circuit through the said last-mentioned means to decrease the pitch of the propeller blades until the speed of rotation of the propeller becomes stabilized by the said decrease in pitch, whereby a proper rotating speed and blade pitch is automatically selected to absorb and balance any given power input applied to rotate the propeller and compensate for changes of air speed and barometric pressure.

6. A propulsion device for use in iiuid mediums, said device comprising a bladed variable-pitch propeller, power means to rotate the propeller, pitch adjusting means for varying the pitch of the propeller,v and a governing device automati' cally responsive to changes in speed of rotation of said propeller for operating said pitch adjusting means to effect a combination of pitch setting and speed of propeller rotation to effectively absorb and balance the power being applied by the power means to rotate the propeller, said governing device including a first part movable a'long a given path with its position on said path determined bj the speed of rotation of the propeller, a second part slidably mounted with resp-ect to said first part and movable therewith unless restrained from such movement, a third part adjacent said path and relatively xed against movement, and a centering device including two spaced arms carried by one of said two last-named parts, and a third arm extendingl between said two spaced arms and carried by the other of said two last-named parts, and means operative to change the pitch of the propeller in one direction when said third arm makes contact with one or the two spaced arms, and to change the pitch of the propeller in the other direction when the third arm makes contact with the other of said two spaced arms, said second part being movable relative to the i'lrst part to av new position with respect thereto whenever the cooperating arms of the centering device make contact with a predetermined minimum pressure.

7. A propulsion device for use in fluid mediums, said device comprising a bladed variable-pitch propeller, power means to rotate the propeller, pitch adjusting means for varying the pitch of the propeller, and a governing device automatically responsive to changes in speed of rotation of said propeller for operating said pitch adjusting meansfto eiiect a combination of pitch setting and speed of propeller rotation to effectively absorb and balance the power being applied by the power means to rotate the propeller, said governing device including a first part movable along a given path with its position on said path determined.- by theA speed of rotation of the propeller, ay second part slidably mountedl with 9 respect to said rst part and normally movable therewith but capable of relative movement with respect to the rst part, stabilizing meansfor shifting said second part with respect to said first part in response to excessive movement of said first part, said stabilizing means being operatively connected to said pitch-adjusting mechanism to eiect a change in pitch in a direction that tends to resist the change in speed of rotation that caused the movement of the rst part, whereby said second part establishes a new position with respect to the rst part and the pitch and speed of the propeller are automatically adjusted to values that effectively absorb and balance the power input applied to the power means for rotating the propeller.

HERBERT L. MAGILL.

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

UNITED STATES PATENTS Number Name Date 1,088,761 Anderson Mar. 3, 1914 1,099,083 Duc June 2, 1914 1,290,669 Schmidt Jan. 7, 1919 1,374,786 Walker Apr. 12, 1921 1,374,787 Walker Apr. 12, 1921 1,385,257 McLean July 19, 1921 1,387,166 Pazos-Martinez Aug. 9, 1921 1,457,871 Bonsiakos June 5, 1923 Number 10 Name Date Fales Dec. 16, 1924 Landon Sept. 20, 1927 Goddard Sept. 27, 1932 De Lavaud Jan. 9, 1934 Goddard Nov. 13, 1934 Dornier May 14, 1935 Goddard Jan. 7, 1936 Myers May 25, 1937 Lysholm July 6, 1937 Fator July 13, 1937 Aikman Nov. 22, 1938 Bleecker Jan. 3, 1939 Dicks Jan. 21, 1941 Rindfleisch Sept. 30, 1941 Gregory et al Dec. 7, 1943 Thompson Feb. 26, 1946 Kundig Mar. 26, 1946 Briner Aug. 6, 1946 FOREIGN PATENTS Country Date Great Britain Jan. 12, 1925 Great Britain of 1929 Great Britain July 30, 1930 France Aug. 7, 1928 France May 29, 1931 France Jan. 8, 1936 France June 10, 1940 OTHER REFERENCES Astronautics No. 34, pp. 12-13, June 1936.

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