US2192790A - Propeller pitch indicator - Google Patents

Description

March 5, 1940. c. i-l. HAvlLL I PROPELLER FITCH INDICATOR Filed June 2'?, 1934 Patented Mar. 5, 1940 UNITED STATES PROPELLER PITCH INDICATOR Clinton H. Havill, South Orange, N. J., assignor to Eclipse Aviation Corporation, East Orange, N. J., a corporation of New Jersey Application June 27, 1934, Serial No. 732,724

3 Claims.

This invention relates to indicators, and more particularly to indicators of the type adapted to register the displacement of power-operated devices.

One of the objects of the present invention `is to provide, in a controllably-operated powerdriven device, an indicating mechanism therefor, so constituted as to be simultaneously controllably operated with the power-driven device.

Another object is to`provide, in a system such as that outlined above, novel means forthe simultaneous control of both the power-driven mechanism and of the indicator, so that the indicator will proportionately reproduce the motion of the power-operated device.

A further object is to provide anV indicating mechanism of the above type which is especially adapted to indicate-the pitch of a variable pitch propeller.

A further object is to provide a variable pitch propeller construction and an indicating mechanism therefor, in which both the pitch-changing and the'indcating mechanisms are driven by separate controllable driving connections from the propeller shaft, and wherein a common control means is employed for simultaneously controlling both driving connections.

A further object is to provide, in a system such as that outlined above,. novel electric control means for controlling the driving connection from the engine to the indicating mechanism.

A further object is to provide automatic cali- Abrating means for tlie indicator of a system of the above character.

The above and other objects of the invention will appear more fully hereinafter from the following detailed description when taken in connection with the accompanying drawing. It is to be expressly understood, however, that the.

drawing is for the purpose of illustration only, and is not designed as a definition of thev limits of the invention, reference being had for this purpose to the appended claims. v

. Inthe drawing, wherein similar reference characters refer to' like parts throughout the severalv Fig. 5 is a view of the dial and pointer mechanism embodied in the Vindicating device.

Referring more particularly to Fig. 1, the present invention is disclosed therein as being associated with a variable pitch propeller I, suitably driven by an engine 2 through a propeller shaft 3, thelatterrbeing preferably employed to actuate any suitable pitch-changing mechanism 4 for varying the pitch of the propeller in either direction. Pitch-indicating mechanism shown dim agrammatically vat 5 is provided for indicating the pitch of the propeller and preferably such mechanism may be selectively drivably connected with the propeller shaft or anysuitable engine driven member such as the tachometer take-off, for example, through a flexible cable 6. Preferably the mechanism 5 is drivably connected with the driving cable 6 only when the pitch-changing mechanism 4 is actuated, and to this end a control member 1 is provided whichy effects operation of the pitch-changing mechanism 4 in either direction through links 8 and 9 and simultaneously establishes a driving connection between the indicating device 5 and the driving cable 6 through any suitable meansv suchas an 25 electrical circuit I0, to be described hereinafter more in detail. Y

'I'he indicating mechanism 5 as disclosed in Figs. 2 and 3 more particularly includes a casing II, la bracket I2 secured to the rear wall of the g casing, and a suitable frame I3 which is secured to the bracket and supports certain parts of the indicating mechanism. Preferably, a reversing transmission forms the first part ofthe indicating mechanism and includes a driving shaft I4 g and a driven shaft I5 journalled respectively 4in bushings I6 and I1 supported by the frame. 'Ihe driving shaft I4 is constantly rotated in a clockwise direction as seen in Fig. 4 at a speed proportional to the speed of the propeller shaft by any suitable means, such as the flexible cable 6 extending from the tachometer take-off I8 tothe said shaft I4. The latter in turn constantly drives a countershaft I9 in a counter-clockwise direction, for example, as viewed in Fig. 4, by means of the meshing gears 20 and 2l secured respectively to the said shafts I4 and I9, the said shaft I4 also constantly driving a countershaft 22 in a clockwise direction as viewed in said figure by means of the gear ZIJ, an idler gear 23 rotatably mounted on the frame I3, and a gear 24 mounted on the shaft 22.

Means are provided whereby the constantlyrotating countershafts I9 and 22 may selectively drive thefdriven shaft I5 in opposite directions.

I, howver, the gears 21 and 28 are freely rotatable upon their respective shafts I9 and 22. In the event that clutch is engaged, the shaft I9, which rotates in a counter-clockwise direction as viewed from the left, in Fig. 2, will drive the shaft I5 in a clockwise direction by means of the gears 21 and 29. If the other clutch 26 is engaged, however, the shaft 22, which rotates clockwise, will drive the shaft I5 in a counterclockwise direction through the gears 28 and 2II.

The clutches 25 and 26 are selectively engaged by any suitable means simultaneously with the actuation of `the pitch-controlling member 1. As shown, such means is electrically controlled and includes a sleeve 38 splined upon the shaft 22 so as to rotate therewith and to slide freely longitudinally thereof. A driving clutch member 3l is secured to the sleeve 30, while a driven clutch member 32 is mounted for free rotation upon the shaft 22, in operative relation to the driving clutch member 3|. 'I'hrusting the sleeve 38 to the right in Fig. 3 will carry the driving clutch member 3| into engagement with the driven clutch member 32. In normal position, however, a spring 33, encircling the shaft 22, holds the clutch members 3| and 32 in disengaged position.

'I'he electromagnetic means further comprise ya solenoid 34 wound upon a stationary core 35 which encircles the revolving sleeve 38. A pole piece 36 is mounted on the frame I9 and supports the solenoid core 35 by means of a screw 31 passing through the pole piece and threaded in an ear 38 formed on the core 35. Cooperating with the pole piece 36 and solenoid 35 is an armature 39 formed coaxially with the sleeve 38 and rotating therewith. Energizing the solenoid 34 will draw the sleeve to the right as seen in Fig. 3, so as to engage the driving clutch member 3| with the driven clutch member 32, such movement of the armature 39 andsleeve 38 to the right being arrested, however, by the contact of vthe clutch member 3| with the clutch member 32 before the air gap 48 is completely closed, this arrangement preventing the scraping of the rotating armature 39 against the stationary horns 4I of the pole piece 36. A similar solenoid mechanism 6I is provided for actuating the other clutch de'vice.

Suitable indicating means including a pointer 42 are drivably connected with the shaft I5 through a reduction gear train which more particularly includes a planet-carrying disk 43 setooth than the fixed gear 48 in order that each revolution of the planet carrier 43 will advance the gear 49 by,the.width of one tooth. In this v manner, a great speed reduction is provided between the shaft I5 and the gear 49. vThe gear 49 drives the pointer 42 through a hub 58.

Frictional means are provided whereby the pointer 40 is retained upon hub 58 but may be shifted angularly with respect thereto. Such means comprise a screw 5I passing loosely through the hub 52 of the pointer 42 and threaded into the shaft I5, the head of the screw lightly engaging the hub of the pointer so as to frictionally maintain the same in proper position. A plurality of fingers 53 integral with the hub 52 of the pointer grip the hub 50 and provide a yieldable frictional driving connection therewith.

Electrical interlocking means are shown in Fig. 1 which effect engagement of one or the other of the clutches 25 or 26 whenever the propeller pitch is changed. These means comprise a battery 54, one pole of which is electrically connected to the terminals 55 and 56 of the solenoid coils 34 and 6I respectively, the other pole of the battery 54 being connected to the lever 1 which is of conducting material. Contacts 51 and 58 are provided to cooperate with the lever 1 and are connected to the terminals 59 and 60 of the solenoids 34 and 6I. When the lever 1 is shifted forwardly, a circuit will be completed through the contact 51, thus energizing the solenoid coil 34, and thereby causing engagement of the clutch 26. Similarly, when the lever 1 is shifted rearwardly, the solenoid coil 6| will be energized, and will cause engagement of the clutch 25. y

In operation, assume for example that the pilot moves-the lever 1 forwardly, engaging the pitchchanging gearing 4 to cause an increase in the propeller pitch. Simultaneously, the lever 1 will engage the contact 51, energizing the solenoid coil 34 to engage the clutch means 26 so as to cause the engine I to drive the indicating hand 40 clockwise as seen in Fig. 5 through the train including tachometer take-off I8, cxible shaft 6, shaft I4, gears 2|) and 2|, countershaft I9, clutch 26, gear 28, driven gear 29, shaft I5, reducing planetary gears 44, 48 and 49 and the collar 50 to the indicating pointer 42. Release of the lever 5 willk disengage both the propeller shifting and indicating gear trains. The increase in pitch of the propeller during this operation will be proportional tothe number of revolutions of the engine during the time in which the lever is held in its forward position. Also, since the gear train from the engine I to the indicating hand 42 is held engaged during the same time. the clockwise shift of the indicating pointer will likewise be proportional to the number of revolutions of the engine during which the lever 5 is held forward. Therefore, the angular clockwise displacement of the indicating pointer 40 will be proportional to the increase in pitch of the propeller.

Similarly, when the lever 5 is shifted rearwardly to decrease the propeller pitch, the clutch 25 is engaged s0 as to cause the indicating hand 48 to be driven counter-clockwise and the counterclockwise shift of the indicating hand 4l) will be proportional to the decrease in pitch of the propeller.

A suitable scale 62 is provided for the pointer 42, such scale being shown in Fig. 5, and'being calibrated in degrees of propeller pitch. Thus', whenever the pitch of the propeller is increased or decreased by a certain numberof degrees, the reading of the indicator is correspondingly increased or decreased. Obviously, if the pointer is once set so as to indicate the actual pitch of the propeller, it will thereafter contnue to indicate-the pitch of the propeller.

Discrepancies between the control of the pitchchanging and indicating mechanisms mayin f time cause an error in the indication. Accordingly, a correction is periodically applied to the indicator, as will now be explained.

As is common in pitch-changing devices, automatic means are provided in the pitch-changing mechanism 4 for arresting the change of pitch Whenever the pitch has attained a predetermined maximum or minimum. Such means may operate independently of the lever 1, that is if the lever 1 is held in its forward position, the pitch of the propeller l will rst increase to a certain maximum value, after which it will remain at that value even though the lever 1 is not released. Similarly, holding the lever 1 in its rearward position will cause the pitch to decrease to, but not below, the minimum value.

In a manner corresponding to the above described action of the pitch-changing mechanism 4l, the pointer 42 cannot shift above or below a certain range, even though the lever 1 is held in a forward or rearward position. 'I'his is accomplished by providing a pair of adjustable stops 63 and 64 placed to arrest the pointerf42 at the points on the scale indicating respectively the maximum and minimum possible values` of propeller pitch. If the lever 1 is continuously held in its forward position, the-pointer 42 will rotate into contact with the stop 63, which will prevent further clockwise rotation of the pointer 40. Theyieldable frictional connection 53 between the indicating pointer 42 and the collar i 50 permits the indicator gearing to continue rotation without injury to the pointer. Similarly,

holding the lever 'I in its rearward position will decrease the reading of the indicator to, but not below, the value of the minimum possible pitch angle of the propeller. 'I'he above described characteristics of 'the pitch-changingand indicating means produce an automatic calibration of the pitch-indicating means 5 whenever the pilot causes the propellerpitch to assume its maximum value. For instance, if the pilot shifts the lever 1 forwardly and does not Arelease it until he is sure that both the propeller pitch and the indication of the pointer 42 have reached their corresponding maximum values, the indicating hand 42 has been automatically reset to the correct value of the propeller-pitch angle; that is, the propeller-pitch is at its maximum value, and the pitch indicator indicates such maximum value; A similar resetting action will obviously occur when the pilot holds the lever 1 in its rearward position so asv to decrease'both the pitch of the propeller and the reading of the indicating pointer to their corresponding minimum values.

While there has been shown and described only one embodiment of the invention, it is to be unf derstood that the same is not limited thereto but may be embodied in various mechanical forms. It is also to be understood that various changes may be made in the relative sizes, shapes and relative location of the parts without departing from the spirit of the invention, as well understood by those'skilled in the art. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

-What is claimed is:

1. In combination, a variable pitch propeller, a propeller shaft, means for changing the pitch of the propeller, a controlling means for the pitch-changing means for increasing or decreasing the pitch of the propeller, and a pitch indicator comprising an indicating member, two driving connections from the propeller shaft to said indicating member, one of said driviim' connections tending to drive the indicating member in one direction and the other of said driving connections tending to drive the indicating member in the opposite direction, a clutch included in each of said driving connections, and electrical means governed by said controlling means for engaging one of said clutches when the pitch of the propeller is being increased and for engaging the other of said clutches when the pitch of the propeller is being decreased.

2. In combination, a variablepitch propeller, a propeller shaft, shaft-operated means for changing the pitch of the propeller in reverse directions, a pitch indicator comprising an indicating member, and means for connecting the propeller shaft and member comprising a pinion operatively connected with the propeller shaft and rotated thereby, a pair of gears operatively connected with said pinion and rotated in opposite directions, a shaft4 carrying each gearof said pair of gears, speed reduction gearing connected with said member and including a pair of clutch members, a sleeve surrounding each shaft and mounted thereon so as to be axially movable thereof but rotatable therewith, clutch members carried by the sleeves and adapted to respectively frictionally engage and drive said rst named clutch members, electromagnetic means for selectively moving either .of said sleeves axially of the respective shafts to move the clutch member carried by the sleeve into frictional driving engagement with the corresponding one of the rst named clutch members, and common means for controlling said rst means and said electromagnetic means.

3'. In combination, a variable pitch propeller, a propeller shaft, shaft-operated means for changing the pitch of the propeller in reverse directions, a pitch indicator comprising an indicatingv member, and means for connecting the propeller shaft and member comprising a pinion operatively connected with the propeller shaft and rotated thereby, a pair of gears operatively connected with said pinion and rotated in opposite directions, a shaft carrying each gear of said pair of gears, a clutch member drivably connected with each shaft, speed reduction gearing connected with said indicating member and including a pair of drivenclutch members mounted for cooperation with the rst named clutch members, electrically operated means for selec- CLINTON H. HAVILL.

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