US2327274A - Variable pitch aerial propeller - Google Patents

Description

Aug. 17, 1943. M. LEVINE VARIABLE PITCH AERIAL PROPELLER Filed Feb. 27, 1942 2 Sheets-Sheet l IN V EN TOR.

8 Morris Levine Morris Levine,

PITCH IPRQPWEE New York, N. if assignor oi one= to Sigmund Einstoss, Brooixllyn, Appiication February 27. W42, Seria'i No. ceases.

2 Ciaims.

invention relates to aerial propulsion means and broadly comprehends an improved propeller in which the blades are so constructed and arranged as to exert a greater force than heretofore in proportion to the size of the propeiler.

The invention is further directed to an improved aerial propeller of the indicated character wherein the blades are mounted and actuated in a novel manner to vary the pitch thereoi, either while the propeller is in operation or at rest.

More particularly the invention is directed to improved aeriai propeller in which the area oi the effective surfaces of the blades is materially increased in proportion to the size of the propeller by extending the inner ends of the blades tangentially of the axis of rotation of the propeller rather than radially thereof and inwardly beyond a line tangential to the periphery of the hub.

As a further feature the invention embodies a propeller structure in which the blades thereof are associated with the hub structure for turning movement of the blades on their longitudinal axis with reference to the hub so as to vary the pitch of the blades and wherein means is provided under the control of the pilot for cheating predetermined variations in the pitch of the blades.

With the above enumerated and other objectsin view, the invention is set forth in greater detail in the following specification and illustrated in the accompanying drawings in which:

Fig. l is a front elevation of an aerial propeller constructed in accordance with the invention.

Fig. 2 is a side view thereof.

Fig. 3 is an enlarged cross sectional view taken approximately on the line 33 of Fig. 1.

Fig. 4 is a, transverse sectional view taken approximately on the line 4-4 of Fig. 3.

Fig. 5 is a transverse sectional view taken approximately on the line 5-5 of Fig. 3.

Fig. 6 is a perspective of the actuator block as viewed from the top.

Fig. 7 is a perspective view of the actuator block as viewed from the underside.

Referring to the drawings by characters of reference, A designates generally the hub of the propeller which is keyed or otherwise secured to the propeller shaft B for rotation therewith. The hub A is of hollow construction and is provided intermediate its length with a. plurality of tangentially disposed bearing bosses l0, two of which are shown in the present embodiment, although the number may be increased to coincide with the number of blades which are to be used so that (illn Mil- 1163) the invention. is applicable to a two, three or tour bladed propeller or even to a greater number oi blades or to a single bladed propeller where desired.

The propeller blades, which are designated generally by the reference character C, each includes the mam body portion i i and a shank extending inwardly from the body and of reduced diameter with reference thereto so as to define a shoulder it at the juncture of the shank with the body. the bearing bosses to are of substantially semicircular configLn-ation throughout the major por-- tion oi their length. and are provided at their innermost ends a cylindrical step bearing i i which surrounds th terminal of the shank it.

The hub A adjacent the outer and of the boss is aiso formed with a concave bearing it which abuts with the side of the inner extremity of the body to brace the same at the hub. The shank: it of each blade formed with a reduced threaded stud it which (extend through an aperture at the inner end of each huh bearing boss it and is equipped with a lock nut it to retain the blade against axial displacement by centrifugai force, while permitting of turning of the blade on its own axis to vary, the pitch of the same. Each oi the blade shanks i2 is further provided with helical worm teeth is extending generally in the direction of the axis of the blade and disposed inwardly towards the longitudinal axis of the hub A. Under this construction it will be observed that the area of the effective surfaces of the blades is increased in proportion to the size of the propeller as said surfaces extend inwardly beyond the periphery of the hub.

In order to provide means under the control of the pilot for Varying the pitch of the blades, a worm gear 25 is secured to a shaft 26 extending longitudinally of the hub and having its longitudinalaxis coinciding with the axis of the hub and mounted in a bearing web 21 with one terminal 28 of the shaft 26 journaled in a. step bearing 29 in the forward end of the propeller shaft B. The worm gear is provided with helical Worm teeth 3| which mesh with the worm teeth 19 on the shanks l2 of the blades for simultaneously turning the blades on their own axes to vary the pitch thereof.

In order to impart turning movement to the worm gear 25, the worm shaft 26 has secured to the forward end thereof a cylindrical head 35 which is formed with a helical cam groove 36, within which the cam lug 31 of an actuator block 38 is engaged for effecting turning movement of said head 35. The actuator block 88 is mounted for guided longitudinal movement in opposite directions in a path parallel to and at one side of the cylindrical head 35 in a guideway 39 fixed to and supported within the hub A, and longitudinal movement there of is imparted thereto by means of a threaded rotary shaft 40 engaging the threaded bore 4| of the block. The threaded shaft 46 is iournaled for rotation and held against axial movement at its opposite ends in the bearing web 21 and a bearing bar 42. The threaded shaft 40 has secured thereto a gear 43 which meshes with the pinion 44 secured to the shaft 46 of a reversible electric motor 46 which is supported in fixed relation to and within the forward part of the hub A. The motor 46 is of the type in which reversing of the polarity efl'ects rotation of the same in opposite directions thereby through the pinion 44 and gear 43 the threaded shaft 40 will be turned in opposite directions to thereby cause the worm gear 25 to turn the propeller blades C in opposite directions of their axes to vary the pitch of the same.

In order to insure the variation of the pitch so as to dispose the same at a plurality of relatively different angles and to place the same under the control of the pilot, manual means is provided for closing the circuit to insure the movement of the actuator block, and automatic circuit breaker means is provided for discontinuing the movement thereof after the predetermined variation in the pitch of the propeller blades has been attained. This is accomplished by arranging the circuit in the following manner:

Conductors 50 and lead from opposite terminals of the motor 46 to a reversing switch 52 L and conductors 53 and 54 lead respectively from the reversing switch. The conductor 53 extends to one pole of the source of supply 55, while branch conductors'56 and 51 lead from the conductor 54. The branch conductor 56 extends to one contact 58 of a push button switch S, while the branch conductor 51 is connected in parallel with contact elements 59 and 60. A circuit wire 6| leads from the opposite pole of the source of supply to the contact element 62 of the push button switch S. A circuit wire 63 is connected with the conductor BI and leads therefrom and is connected in parallel with contact elements 64 and 65. The conductors 53, 56 and 63 which, covered .with insulation, extend through the propeller shaft B and are connected-to contact rings 66 insulated from each other and from the shaft and which rings are engaged by contact shoes 61 to convey the current to and from the rings to the source of supply and the push button switch S. The reversing switch 52 will be preferably located adjacent the push button switch S within convenient reach of the pilot and this may be accomplished in any desired manner such as leading the .wires 50 and 5|, 53 and 54, which are covered with insulation, through the propeller shaft and providing rings and contact shoes for controlling the same by remote control.

The contact elements 59 and 64 are arranged in closely spaced relation, as illustrated, while the contact elements 68 and 65 are arranged in closely spaced relation and spaced from the contact elements 59 and 64 with said pairs of contact elements arranged longitudinally of the guideway 39. A bridge piece is mounted adjacent the contact elements 59 and 64 and is carried by a button ll of insulation material which is normally urged inwardly through an opening in the guideway 39 and into the path of movement of the actuator block 38. A second bridge piece 12 is mounted adjacent the contact elements 60 and 65 and is carried by a button 13 of insulation material which button is normally urged inwardly through an opening in the guideway 39 and into the path of movement of the actuator block. The buttons 1| and 13 are so spaced longitudinally of the guideway and with reference to each other so that when oneis engaged by the actuator element, the other is out of engagement therewith.

In use and operation, with the propeller blades set at the angles as shown by the broken line X, the pitch may be varied by the pilot depressing the push button switch S to bridge the contacts 58 and 62. This closes the circuit to the motor 46 as the current will then flow from the right hand pole of the source of supply 55 through the wires 6|, contact 62, bridge of the switch 8, contact 58, wire 56 to wire 54, thence through the reversing switch 52, wire 5|, motor 46, the wire 50 back through the reversing switch to the wire 53 and through wire 53 to the opposite pole of the source of supply. It will, of course, be assumed that the reversing switch 52 has been set to cause the motor 46 to turn in a. direction to move the actuator block 38 to the eft. The initial movement of the actuator block 38 will cam the button 1| outwardly so that the bridge piece 10 engages contact elements 58 and 64 whereby when the push button is released, the circuit to the motor is then completed from the contact element 59 through the branch wire 51, wire 54, the reversing switch 52, the conductor 5| to the motor, thence from the motor to the wire 50, the reversing switch 52, the wire 53 to one pole of the source 55, thence through the wire 6|, the wire 63, to contact element 64, the bridge piece 10 to contact element 59, it being understood that the push button switch is only momentarily depressed to start the motor and move the actuator element until it eflects closing of the circuit by the bridge piece 10. The release of the push button switch S breaks the manually controlled circuit and the circuit is then maintained closed as theactuator block is moving to the left. The circuit is then broken automatically as the actuator block moves past the button 1|, which is urged inwardly to dispose the bridge piece 10 out of engagement with the contact elements 59 and 64. This movement of the actuator block 38 turns the cylindrical head 35 a partial turn so' that the worm gear 25 effects simultaneous turning of the shanks |2 of the propellers to dispose the blades thereof at the angle illustrated by the broken line Y. When the actuator block 38 has moved to the left a sufficient distance to release the button ll of the bridge piece 10, the block will have been advanced to a point closely adjacent the button 13 of the bridge piece 12. If the pilot desires to further vary the angle or pitch of the propeller to that shown-by the broken line Z, he again depresses the push button switch S causing the actuator block 38 in moving further to the left to engage with and force the button 13 of the bridge piece 12 outwardly into engagement with the contact elements 68 and 65 thereby closing the circuit through bridge piece 12 and causing the motor to continue to turn after the push button switch is released until the actuator block 38 releases the button 13 of bridge piece 12 thus automatically breaking. the circuit when the pitch or angle of the blades is in the broken line position illustrated at Z.

With the propeller blades set at the angle Z, the operator may change the pitch to that of either of the angles Y or X by first manipulating the reversing switch 52 and then pressing the push button switch S so as to close the circuit to the motor and causing the same to turn in the reverse direction for moving the actuator element 38 to the right. It will be understood that the initial movement of the actuator element 38 to the right will close the circuit by bridging the contact elements 60 and 65 until the element 38 has passed beyond the button 13 when the circuit will be automatically broken and the pro peller blades assume the pitch designated by the broken line angles Y. A second actuation of the push button switch S will cause the actuator element 38 to move further to the right for closing the circuit due to the bridge of the contact elements 59 and 64 with the bridge piece 10.

What is claimed is:

1. In an aerial propeller, a hollow hub, a plurality of blades each having a shank at the inner end thereof provided with worm teeth, means mounting the blade shanks within the hub for turning movement of the blades on thier axes to vary the pitch of the same, a worm wheel mounted within the hub to turn with reference thereto on an axis extending longitudinally of the hub with the teeth of the Worm wheel engaging the worm teeth of the blade shanks, a rotary head secured to the worm wheel and having a helical cam groove, an actuator block having a cam lug engaging said cam groove, said block being mounted mr guided movementin the path parallel to the axis of the rotary head, feed screw threadedly engaging the actuator block for moving the same in said path of movement, a reversible electric motor connected with the feed screw for turning the same, a circuit including said motor, and a manually operable reversing switch, a normally opened, manually closable switch for starting the motor, and a switch controlled by the actuator block for maintaining the motor circuit closed for a predetermined period and for automatically breaking the circuit after the actuator block has traveled a predetermined distance so as to effect a predetermined variation in the pitch of the blades.

2. In an aerial propeller, a hollow hub, a plurality of blades each having a shank at the inner end thereof provided with Worm teeth, means mounting the blade shanks within the hub for turning movement of the blades on their axes to vary the pitch of the same, a worm wheel mounted within the hub to turn with reference thereto on an axis extending longitudinally of the hub with the teeth of the worm wheel engaging the worm teeth of the blade shanks, a rotary head secured to the worm wheel and having a helical cam groove, an actuator block having a cam lug engaging said cam groove, said block being' mounted for guided movement in the path parallel to the axis of the rotary head, a feed screw threadedly engaging the actuator block for moving the same in said path of movement, a reversible electric motor connected with the feed screw for turning the same, a circuit including said motor and a manually operable reversing switch, a normally opened, manually closable switch for starting the motor, and a plurality of switches spaced longitudinally of and in the path of movement of the actuator block and successively engaged thereby upon the initial starting of the motor for maintaining the motor circuit closed for predetermined periods and for automatically breaking the circuit after the actuator block has traveled predetermined distances so as to efiect predetermined variations inthe setting of the pitch of the blades.

. MORRIS LEVINE.

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