US2447023A - Selective control mechanism for governor-controlled aircraft propellers - Google Patents

Description

Aug, N, i948. H. M. MccoY 2,447,023

SELECTIVE CONTROL MECHANISM FOR GOVERNOR-CONTROLLED I AIRCRAFT PROPELLERS Filed Feb. 3, 1944 Hom/Abo M M0 Cor Patented ug. i7, 1948 ETE!) STATES SELECTEVE CNTRL MCHANISIVI` FR severance-commises insonnia PROPEIJLERS (Granted under the act off: March 3, 15883, as.`

amended April 30, 1928;, 370 @e G. 757) 2 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to ine of any royalty thereon.

This invention relates to selective control mechanism for governor-controlled airplane pr'opeller's and the like, and' in general aims' to providek a control whereby the pilot or engineer mayieiect almost instantaneous changes in the propeller R. P. M. by merely pushing a button or similar switch element. Another object is to provide means which may be so adjusted that operation inresonant engine-propeller ranges is made irnpossible. Further objects are to provide a control mechanism which is simple, dependable, easy to adjust and maintain, and whichis adapted to cooperate with known types of mechanisms for changing propeller R. P. M., without material modiiication of said mechanisms. It is now conventional to control the R. P. M. of a propeller by means of an engine driven governorhaving alcoil spring and having a mechanical'conn'ectionuwith the valve controlling the supply of hydraulic .fluid to the pitchchang-ing mechanism. (See in this connection the Martin Patent No. 2,144,429, dated Januaryv 17, 1939; MacNeil et al. latents` No. 2,218,766, dated October 22, 1940, and No. 2,299,635, dated October 20, 1942.) in one embodiment of the invention, I may add tothe governor of the Martin patent a control mechanism including a source. of power which makes possible as many as seven or more automatic adjustments of the propeller R. l?. M. setting while the airplane is in flight by merely pushing the appropriate switch button for. each desired adjustment. The invention will beV readily understood by referringto the accompanying schematic drawings showing the preferred embodiment, wherein:

Figure l a diagrammatic sectionalelevation;

Figure 2 is a wiring diagram showing the motor control circuit of one push button switch element; and

Figure 3 is a detail in elevation showing the bank of push buttons and their legends.

Referring particularly to the drawings, Sis an R. P. M. governor of the same type as is disclosed in Figs. l and 2 of said Martin patent, having yweights 6 and a governor or Speeder spring 'l whose compression is under the direct control of a slidab-le, but nonrotatable, abutment or piston B to which a valve stem 9 is fixed by means of a nut i3 and lock washer Il. The abutment or piston 8 is cup-shaped and slides -in a cylindrical sleeve l2' press-htted-or otherwise secured-in'ithe governor casing i3.V A cup-shaped abutment- 2. adjusting' member. lli, provided with external screwthreads,y is threadedinto piston 8, which has internal screw threads, asshown.. At the outer end, theabutment-adjusting member is providedv with reversible worm gear i5 which meshes with-a worm= lr6-on a' shaft l?! journaled in the governor casing?. Shaftv Vl is'an extension of a flexibleshafti8V housedfinaiiexible cable i9,V permitting adjustment-of the governor spring, hence of the propeller pitch1and-.R. P. M. of the motor, frcm'any remote point. Valve stem may operate the needle lvalve (not shown) which controis the. flow ofy hydraulic fluid to the. pitchehangingmechanism.A

Toprovide power to drive shaft Il, thereby to vary the propeller R.. P. M., I prefer to employ a reversible electricservomotor 22 with split -iield windingsv 2l, and energized by a source of electricity` 22-throughlead 23 and-conductors 5S, when=the circuitY i-s closed. The shaft, 2d ofthe motor drivesa pinion ziwhichmeshes with a gear 26 on the endofashaft 2l which is coupled (not shown) to the end of flexible shaft `l 3,'andis jour-- naled-in bearingsprovided on lthearms-.253, 29 of frame 35. The gear train .2 5, 25 is obviously illustrativefof any reduction gearV tra-in, 1preferably of high-ratio.v Shaft LA? carries a reversible worm 3i which meshes withvaworm gear 32. on` a cam shaft 33 also journaled-inf'rame 3E, sothat the camshaftis driven-very slowly whenever motor 2G is energized. Secured to the cam are a plurality ofdisk cams-311, 35, 3B, 3l, 38, and 4S, preferably arranged parallelI tceach other. A plurality. of push buttonshii, 42, id, tlc, andd close contacts (not. shown) in a switch .box G8 mountedonfiame 30 (or anywhere in the airplane), anda calle fi9'incloses and insulates the-necessary conductors which electrically conn nect each ofthe. contacts in the switch box with a plurality of lfixedcontacts Eil-secured upon and insulated by. the frame member 55. Switch box with itsvarious push buttons and contacts may be termeda-Selector"switch since itpermits the pilot to select the particular propeller adjustment which he desires for the fiightconditions immediately" ahead, Obviously other types of selector switches may lie used.` Another cable 5i inclusesV co'n'duc'rtors5'8",l 5"!!A connecting motor '2li 1withcorita'ctslill an'dwith lanother setV of contacts `tif secured upon -an'd insulated `liy member 55,'. which isspaced from frame member 56?. There are' asinahy contacts in eac-h set of contactsi, Sii-as there-are push" Bettens on the selector switch; and eachlpair' offcfoiitacts. 513,-' SL53 control the motor circuiti as wll now bej described.

3 Normally there is no current flowing through any of the frame-supported contacts, and the motor is normally at rest.

Let us suppose that the button 43 is depressed, as shown, to effect the proper propeller adjustment for climb or high speed. This closes the motor circuit to start the motor, which moves the piston 8 in one direction or the other and also slowly rotates the cam shaft 33 to turn cam 36. In contact with cam 36 is a cam follower 13 fixed on but insulated from a movable contact member 68, and held against the edge of the cam by compression spring 14, which is interposed between the frame and the contact member. Contact member 68 is one of a. set of movable contact members (G6-'l2 inclusive) each of which is movable between a pair of fixed contacts 5060 to Y close the circuit of motor field 2| to cause rotation of the motor in one direction or the other. Contact members 66-12 are normally in a circuit closing position against one of the fixed contacts so that depressing one of the push buttons 4l to 4l will complete the motor circuit, causing rotation of the cam shaft until the proper adjustment of piston 8 has been effected, whereupon the cam which has been active moves the corresponding contact member to neutral position, and power to the motor is immediately cut off. Each contact member 66--12 is moved by a corresponding cam of the set of cams 34-40 in the direction required by the shape of the particular cam. As will be understood from Fig. 2, the contact members may all be pivotally mounted on a rod 68a having a conductor y681) electrically connecting the switch members with the motor circuit. Each of the cams must have such a form and angular adjustment that when the corresponding push button is depressed, the motor will move piston 8 until the propeller R. P. M. is adjusted to correspond to the legend (Fig. 3) which appears on panel 8| adjacent the push button. All the other adjustments of the propeller are effected in the same way.

According to the Crane et al. Patent No. 2,311,642, dated February 23, 1943, it is old to employ a set of five or more cams mounted on a shaft rotated by a servomotor, each of said cams moving a switch member against one of two contacts to close circuits effecting rotation of the servomotor in one direction or the other, the servomotor effecting adjustment ofthe throttle-controlling element of the airplane engine. 'Ihe amount of rotation of each cam determines the setting of the throttle. The predetermined throttle positions are selected by closing switches each associated with a cam-actuated switch member. However, the several cams must be set, during flight, by means under the control of the pilot or engineer; hence provision is made to allow slipping of each cam relative to its shaft and to lock each cam while the shaft continues its rotation, to vary the angular position of the cam to correspond exactly to the throttle position controlled thereby.

Obviously, in my arrangement of parts, the cams should be individually adjustable on the cam shaft and should be rigidly held in adjusted positions, so that the action may be very precise and certain; but as satisfactory cam adjusting and locking means are known, no disclosure is made of any particular arrangement. Furthermore, the motor circuit need not be completed through the switch members, but a control circuit of low voltage, controlled by the cam followers, may operate the motor circuit through relays, as is well known in the art of motor control. The motor is preferably provided with a self-contained solenoid-controlled spring-loaded clutch (not shown) so that when the motor is de-energized it will be immediately declutched, whereby overrunning of the motor armature due to momentum will not affect the setting of the governor. The seven legends marked on panel 8| are obviously illustrative and may be changed to suit the different operating conditions encountered in handling different types of airplanes. While the illustrative embodiment is shown as connected With the governor of a hydraulic pitchchanging and R. P. M. regulating apparatus, the invention is readily usable with electric pitchchanging devices and may find application in various fields and industrial arts. For instance, on a multi-motored airplane or motorboat, the engineer with the aid of the described remote selective control may select a desired R. P. M. for the master synchronizer, which then governs the individual engines.

Advantages of the described control mechanism include simplication of the propellerengine R. P. M. control for the pilot or engineer, and what is probably more important, the fact that resonant engine-propeller R. P. M. ranges, wherein Iprohibitive propeller blade stresses frequently occur, can be avoided. My control mechanism may be so adjusted that it is impossible for the pilot or engineer to operate in the restricted (resonant) range.

What I claim is:

1. A selective speed control mechanism for governor-controlled engine-driven aircraft propellers comprising, a propeller governor having a speed regulating means actuated by rotatable engine-driven governor Weights and a speeder spring under compression, means for adjusting the compression of said speeder spring including a slidable piston-like element in abutment with said spring, means including reduction gearing for adjusting the position of said piston-like element in response to rotation of a drive shaft extending from said propeller governor to a remote control point, an electric motor, driving means connecting the remote end of said drive shaft to the shaft of said motor, a plurality of push button switches corresponding to the number of desired speed adjustments of said control mechanism, a movable contact for each of said push button switches and connected in series therewith, a pair of spaced contacts for each of the movable contacts and arranged on opposite sides of the respective movable contacts, a plurality of disk cams mounted on a common camshaft and each adapted to operate one of said movable contacts, driving means connecting said camshaft to the shaft of said motor, a plurality of energizing circuits for said motor and each including one of said push button switches, one of said movable contacts and a corresponding pair of said fixed contacts, the connections between said pairs of xed contacts and said motor being such that closing the motor circuit through one contact of each pair causes motor rotation in one direction and closing the motor circuit through the other contact of each pair causes motor rotation in the opposite direction, and said cams being individually contoured to cause operation of said motor in such a direction and for such length of time as to produce definite and individual adjustments of the compression of said Speeder 6 REFERENCES CITED The following references are of record in the le of this patent:

5 UNITED STATES PATENTS Number Name Date 2,098,761 Schlpfer Nov. 9', 1937 2,144,429 Martin Jan. 17, 1939 10 2,218,760 MacNeiI Oct. 22, 1940 Yardeny Feb. 29, 1944

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