US2371160A - Single-blade propeller - Google Patents

Description

Mar'e'h 13,1945, w. w. EVERTS 2,371,160

SINGLE-BLADE PROPELLER Filed NOV. 1, 1939 3 Sheets-Sheet 1 as Q Walter WEye-ris.

iMarc'h 13, 1945. w. w. EVERT-S 2,371,160

S INGLE-BLADE PROPELLER Filed Nov. 1, 1939 5 Sheets-Sheet 3 Patented Mar. 13,1945

SINGLE-BLADE PROPELLER Walter W. Everts. Baltimore, Md., assignor to Everel Propeller Corporation, Baltimore, Md., a corporation of Maryland Application November 1, 1939, Serial No. 302,423

11 Claims. My invention relates to improvements in single-blade propellers.

An important object of the invention is to Provide a single-blade propeller which is particu-' larly well adapted for use upon air craft, but which is also adapted for use in connection with boats including surface, ships or submarines and fans used for ventilating purposes or the like.

A further object of the invention is to provide a propeller of the above mentioned character, which is automatically actuated by the action of centrifugal force, to vary its pitch, as the pressure of the fluid medium within which the propeller is operating varies.

A further'object of the invention is to provide a simplified pivotal mounting for the variable pitch propeller which will permit of the propeller automatically finding its plane of rotation.

A further object of the invention is to provide means for accurately balancing the propeller statically, vertically and horizontally.

A further object of the invention is to provide means to balance the propeller dynamically.

A further object of the invention is to provide a propeller of the above mentioned character, having its pivotal mounting enclosed and its leading side covered.

A further object of the invention is to provide means to limit the swinging movement of the propeller for varyingits pitch.

Figure is a rear end elevation of the front n, a a

Figure 11 is an exploded perspective view of the coupling hub and associated elements.

In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral l0 designates a singleblacle propeller as a whole. The propeller includes a single blade [0' having a center-line Ill. The propeller blade Ill has a leading section II and a trailing section l2, whichare unbalanced, the trailing section having the greater area. This propeller may be formed of any suitable material, such as aluminum, an aluminum alloy, Bakelite, wood, or the like. The propeller is preferably formed integral and comprises a hub H, carrying a shank I2 upon'one side, which carries the blade Ill. The hub has a counterweight shank or member l3 integral therewith, arranged opposite the shank l2. The hub II has circularly curved portions l4, extending radially beyond the shank l2 and counter-weight shank or member 13. The action ofcentrifugal force upon the blade l0 and counter-weight shank or Other objects and advantages of the invention will beapparent during the course of the following description.

In the accompanying drawings forming a part or this application and in which like numerals are employed to designate like parts throughout the same,

Figure l is a front elevation of a single-blade propeller embodying my invention,

Figure 2 is a transverse section taken on' llne 2- -2 of Figure 1,

Figure 3 is a vertical section taken on lined-3 I of Figure 2, parts broken away,

Figure 4 is a plan view or the propeller, parts broken away, i K

Figure 5 is a horizontal section taken on line 5-4) of Figure 1, I Figure 6 is a vertical section taken on line, 6-

of Figure 4,

Figure '7 is a front elevation of the propeller, partly diagrammatic, with the propeller horizontal,

Figure 8 is a plan view of the same, Figure 9 is a front elevation of the propeller,

. artly diagrammatic, showing the samevertical,

member I3, produces radial thrusts in opposite directions which are balanced. The entire propeller is also substantially statically balanced both horizontally and vertically.

The propeller hub II is provided with a central circular recess 15, receiving oppositely arranged bearing blocks or members I 6, having fiat inner faces I1 and cylindricall'y curved outer faces l8. Each bearing block It has curved end flanges l9 and flat end faces 20. Each bearing block it has a cylindrical recess 2|. Arranged within each cylindrical recess 2i is a bearing sleeve 22, having a tapered opening 23, which is circular in cross-section, and increases in diameter inwardly. This bearing, sleeve receives a bronze bushing 24, having an outer tapered wall 7 and an inner tapered opening or bore 25, which iscircular in cross-section and increases in diameter inwardly. The bronze bushing 24 is prefe'rably apertured for the passage of a lubricant. The bronze bushings receive preferably hollow pivot elements 26, which are exteriorly tapered to properly fit within the bronze bushings. The pivot elements are preferably formed integral with a coupling hub 21, which is tubular, to receive the crank shaft 28 of the engine of .an aeroplane or the like. The pivot elements 26 are diametrically oppositely arranged with respect to the coupling hub 21 and shaft 28 and their central longitudinal axes are in a line 2B. The

21 and disposed in a transverse plane at a right angle to the central longitudinal axis of the coupling hub 21. The line 26' is inclined or diagonal with respect to the center line l. Lines l0 and 26' intersect and both pass through the center of the coupling hub 21. The numeral 29 designates a washer or sealing ring, which fits within an annular recess or groove 30 formed in the inner face l1 and also rests against a flat shoulder or face 3|, formed upon the coupling hub 21. This washer or sealing ring surrounds the bronze bushing 24 and engages the inner end of the bearing sleeve 22, and extends across the meeting faces of elements 22 and I8.

The bearing blocks l6 and associated elements are assembled upon the coupling hub 21 and these assembled parts are inserted into the circular opening l5.

A disc 32 is arranged upon the rear side of the propeller hub II, and this disc is provided upon' its inner face with an annular groove 33, to receive the flanges l3. .This disc also has a center opening 34 which is slightly elliptical. .Disposed upon the front side of the propeller hub II is a companion disc 35, provided upon its inner face with an annular groove 36, receiving the flanges l9. This disc has a center opening 31 which is preferably circular. The discs 32 and 35 are connected by main bolts 38, passing through openings 33v and formed in the discs 32 and 35 re-. spectively. These bolts also pass through suitable openings formed in the propeller hub H. The main bolts carry tapered washers 4| at their forward ends, and nuts 42, having any suitable means to lock-the nuts against accidental rotation. The discs 32 and 35 are further connected by auxiliary bolts 44 ,and through openings in the propeller hub ll 43, passing through openings and carrying nuts at their forward ends, with any suitable means to prevent accidental unscrewing of these nuts. The several bolts are so arranged with relation to each other that the propeller remains substantially statically balanced, both horizontally and vertically, and the central longitudinal axes of the bolts 38 are in alignment with the center line ill of the' propeller. Screws 44' pass through openings in the discs 32 and 35 and engage in screw-threaded openings 45 formed in the bearing blocks I 6.

The counter-weight shank or member I3 is provided with a longitudinally extending bore 46, receiving a sleeve 41, preferably formed of metal. This sleeve is cylindrical and has its central longitudinal axis in alignment with the center line Ill. The sleeve 46 has transverse openings 48 near its inner end to receive themain bolt 36-. The sleeve 41 has its outer end portion counterbored and provided with internal screw-threads 49, to engage with screw-threads 50, formed upon the outer enlarged end portion of a weight 5|.

This weight has a slot 52 at its outer end to.

receive a screw driver or the like for turning the same. The sleeve 41 has its outer'end also exteriorly screw-threaded, as shown at 53, for engagement within a cap 54, internally screwthreaded. This cap has an opening 55 at its end for the passage of a screw driver or the like. A 'set screw 56 has screw-threaded engagement within a screw-thre ded opening '51formed in' the cap 54-and this se screw has a reduced shank 58, which is smooth, and extends through an .\opening 59 in the sleeve 41. This reduced shank passes to the'interior of the sleeve 41 and clamps against the weight 5| to lock the weight in the selected adjusted position. The propeller as orig inally made, is balanced statically both horizontally and vertically, as much as possible, but is ordinarily not in true balance and the accurate balancing of the propeller statically horizontally, is effected by the adjustment of the weight 5|.

Means are also provided to accurately balance the propeller statically vertically, comprising bolts 60, held within openings 6| formed in the propeller hub I I. These bolts. carry nuts '62 arranged within recesses 63. Arranged beneath the nuts 62 are removable weight washers 63. By using a suitable number of these weight washers 63', the static balancing of the propeller vertically may be approximately effected. The bolts 60 have their central longitudinal axes in alignment with the diagonal line or axis 26. The bolts 60 are provided at their outer ends with longitudinally extending screw-threaded openings receiving adjustable weight-screws 64, passing through caps 65, which are preferably resilient. The weight-screws 64 are turned to accurately adjust the static balancing of the propeller vertically and the resilient caps 65 hold the weight-screws against accidental movement.

The numeral 66 designates a torque weight,

torque on a single-blade propeller. The moment i exerted by the weight of this torque weight is equal and opposite to the unbalanced aerodynamic torque moment, thereby making the propeller balanced dynamically. The weight of this torque weight is calculated by a theoretical formula. The propeller assembly-is balanced statically on a balance bloek with the propeller *in both a horizontal and vertical position. When the balancing about these axes is completed, the torque weightis mounted at the intersection of the two planes; one passing through the hub axis in a vertical plane and another plane perpendicular to it passing through the longitudinal blade axis III. the propeller out of static balance vertically after balance static considerationsare finished, and then balances-the propeller when in motion.

The crank shaft 28 has its forward end tapered i and inserted within the tapered bore of the coupling hub 21, and the crank shaft has a reduced screw-threaded portion 16, which receives there- -on, the rear endof a tubular shaft e xtension H,

which rear end is internally threaded, as shown. The tubular shaft extension'1l is provided at its rear end with an exterior flange 12, to,engage with a lock nut'13, engaging within a screwthreaded counter-bore 14, formed in the coupling hub 21. This lock nut preventsthe accidental turning of the tubular shaft extension 1|: The lock nut-is held against accidental unscrewing by a cotter pin 15 or' the like.

Arranged upon the front disc 35 is a cap 16, having a flange 11, secured to the bearing blocks l6 by screws 18 engaging/ within openings 18 formed in the block l6. The screws J8 have the further function of properly locating the cap 16 upon the disc 35 so thatthe recesses 60 will receive' the screws 44'. Additional bolts 8| are also employed to secure-the cap to the disc 35. The opening 18 leads into the bearing recess 2|, so that grease or. other lubricant may be fed into The torque weight then throws upon its diagonal axis 26'. As stated, the opening 34 is elliptical and the longitudinal axis of the ellipse is at a right angle to the diagonal line or axis 20.

Operation The operation of the propeller is as follows: The propeller is driven counter-clockwise,

' viewed from the front of the aeroplane, which is the practice in the United States. As soon as the propeller rotates, centrifugal force acts upon the propeller and tends to move it to a radial position. This action of centrifugal force is opposed by the air thrust, which tends to swing the propeller forwardly so that the outer end of the blade l moves forwardly from the radial position and inwardly of the maximum sweep. These two opposing forces act against each other and the blade will assume a normal operating position between the extreme forward position and the true radial position. When the blade is in the extreme forward position it is at the minimum pitch and when in the true radial position it has the maximum pitch, due to centrifugal force. Assuming that the aeroplane is now flying at substantially sea level, the air thrust is then at the maximum and the blade has moved forwardly about the surface of a cone, to assume the forwardmost position which will impart tothe blade the minimum pitch. During this action of the blade, the center line Ill of the blade travels about the surface of a cone; and the center of the cone is the line 26. The action or centrifugal force tends'to move the blade rearwardly about the surface of the cone toward the true radial position, thereby increasing the pitch of the blade. As the speed of the aeroplane increases, the air pressure acting upon the forward face of the blade tends to move the blade rearwardly about the surface of a cone for increasing the pitch of the blade. Assuming that the propeller is being flown in level flight at 2,000 R. P. M., at sea level, the propeller will then have the minimum pitch, with respect to the pitches which it will have at increased elevations. the aeroplane now rises to a considerably higher elevation, the air thrust acting upon the propeller will be reduced, while the action of centrifugal force remains the same and hence the action of centrifugal force will overcome the air thrust upon the propeller blade, and the blade would be moved rearwardly about the surface of the.

cone, and thereby increasing the pitch of the propeller blade. This increased pitch of the propeller blade will cause the propeller to drive, the aeroplane at an increased speed but the speed of rotation of the propeller will remain substantially constant.

When the air pressure upon the front face of th blade I0 is sufficient to overcome the action of centrifugal force, as when the aeroplane is making a nose dive, wardly beyond the radial position, and the pitch of the blade is increased over the maximum pitch which can be impartedto it due to the action of centrifugal force, which would occur when the blade is shifted by centrifugal force into a true radial position. i v

the blade I0 is shifted rear-' Theblade I0 is capable of beingshifted about the surface of thecone, as described within limits, to vary its pitch, and this shifting movement is limited by the tubular shaft extension ll engaging the annularbumper 02.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, what I claim is:

. 1. In a propeller, a rotary driving element having pivot elements arranged radially thereof, said pivot elements having a common longitudinal axis, a single-blade propeller including a hub carrying a blade and counter-weight member, the

blade and counter-weight member being oppo-- sitely arranged and having a, common center line which passesv through the center of the rotary driving element, said hub having an opening to receive the rotary driving element and its pivot elements, bearing devices arranged within the opening of the hub and secured to the hub and receiving the pivot elements, the common longitudinal axis of the pivot elements being arranged perpendicularly to and intersecting'the axis of rotation of the driving element and diagonally with respect to the center line of the blade, so that the blade turns upon the pivot elements and the center line of the blade travels about the surface of a cone having the common longitudinal axis of the pivot elements as the center of the cone.

2. In a propeller, a rotary driving element having oppositely arranged radial pivot elements having a common longitudinal axis, a single-blade propeller including a hub carrying an oppositely arranged blade and counter-weight member, said hub having an opening to receive the rotary driving element and its pivot elements, bearing devices arranged within the opening of the hub for receiving the pivot elements, the common longitudinal axis of the pivot elements being arranged perpendicularly to and intersecting the axis of I rotation of the driving element and diagonally with respect to the longitudinal axis of the blade, so that the blade turns-about the pivot elements and its center line travels about the 'surface of a cone, discs arranged upon oppositesides of the propeller hub, means for securing the discs to the propeller hub, and means for securing the discs to the bearing devices.

3. In a propeller, a rotary driving .elem'ent having oppositely arranged radial pivot elements, a single-blade propeller including a hub carrying oppositely arranged blade and counterweight member, said hub having an openingto receive the rotary driving element and its pivot elements, bearing devices arranged withi the opening of the hub for receiving the pivot elements, the

turning axes of the pivot elements being arranged secured to the leading disc, said driving element having a part extending into the cap and a rub- '-ber bumper mounted within the cap to engage with said extending part of the rotary driving element to limit the movement of the blade {or changing its pitch.

4. In a propeller, the combination of a propeller shaft, a tubular coupling hub to receive a portion of the propeller shaft, said coupling hub having .ppositely arranged radial pivot elements, a single-blade propeller including a hub having an opening and a blade and a counter-weight member disposed upon opposite sides of the opening, the opening receiving the coupling hub and pivot elements, bearing devices arranged within the opening of the propeller hub to receive the pivot elements, the turning axes of-the pivot elements being arranged diagonally with respect to the longitudinal axis of the blade, discs arranged upon opposite sides of the propeller hub, means for securing the discs to the propeller hub and to the bearing devices, a cap secured to the leading disc, a rubber bumper held within the cap, a tubular shaft extensionadapted to have screwthreaded engagement with the end of the propeller shaft and engaging the coupling hub the tubular shaft extension being arranged to engage the rubber bumper, and a lock nut havingscrewthreaded engagement with the coupling hub and engaging the tubular shaft extension.

5. Ina propeller, a coupling hub having oppositely arranged pivot elements rigidly secured thereto, a single-blade propeller having a hub provided with an opening and opposed blade and counter-weight members arranged upon opposite sides of the openingybearing blocks arranged within the opening and fixedly secured to the hub, said bearing gblocks having recesses, hearing sleeves within the recesses, tubular bushings within the bearing sleeves and receiving the pivot elements, sealing rings arranged between the free ends of the bearing sleeves and the coupling hub, the pivot elements having their turning axes arranged perpendicularly to and intersecting the axis of rotation of the driving element and diagonally with relation to the longitudinal axis of the blade; I

6. In a propeller, a rotary driving element, a single-blade propeller including opposed blade and counter-weight members arranged upon opposite sides of the axis of rotation of the rotary driving element, pivot means fixed upon the rotary driving element and serving to, connect the propeller with the rotary driving element, the fixed pivot means having its turning axis arranged diagonally with respect to the longitudinal axis of theblade, the counter-weight member having a longitudinal bore, the center line of the bore being in alignment with the center line of the counter-weight member, a sleeve held within the bore, a weight arranged within the sleeve and having screw-threaded engagement therewith, and means to lock the weight in the adjusted position. l

7. In a propeller, a rotary driving element, a single-blade propeller including a hub having an opening and opposed blade and counter-weight members, pivot means fixed upon the rotary driving element, bearing devices arrangedwithin the opening andreceiving the pivot meansfthe pivot means having its turning axis arranged diagonally with relation to the longitudinal axis of theblade, discs arranged upon opposite sides of the hub, transverse bolts connecting the discs andsecuring them to the hub, means to attach sleeve and screw-threaded to engage with the internal threads of the sleeve, 8. cap having screw-threads to engage with the exterior threads of the sleeve, and means to lock the weight and cap against accidental unscrewing.

' 8. In a propeller, a rotary driving element, a single-blade propeller including opposed blade and counter-weight members arranged upon opposite sides of the axis of rotation of the rotary driving element, fixed pivot means serving to connect the propeller vwith the rotary driving element and having its turning axis arranged diagonally with respect to the longitudinal axis 01' the blade so that the blade moves about the surface of a cone, adjustable means to accurately balance the propeller statically horizontally, and adjustable means to accurately balance the, propeller statically vertically. l

9. In a propeller, a rotary driving element, a single-blade propeller including opposed blade and counter-weight members arranged upon opposite sides of the axis of rotation of the rotary driving element, fixed pivot means serving to connect the propeller with the rotary driving element and having its turning axis arranged diagonally with respect to the longitudinal axis of the blade, a device to accurately balance the propeller statically horizontally and adjustable along the longitudinal axis of the counter-weight mem-. ber, a device to accurately balance the propeller statically vertically and adjustable along the line which is diagonal with respect to the longitudinal axis of the counter-weight member, and a device to balance the propeller dynamically and including one of more weight plates arranged between the first named devices and detachably secured to the propeller. i 10. A propeller construction comprising a propeller hub having an axial opening, a rotary driving element having a part extending through the opening, means for pivotally mounting said hub on said driving element for pivotal movement about an axis transverse to the axis of the and counter-weight members arranged upon opposite sides of the axis of rotation of the rotary driving element, pivot means fixed upon the rotary driving element and serving to connect the propeller with the rotary driving element, the fixed pivot means having its turning axis arranged diagonally with respect to the longitudinal axis of the blade, the counter-weight member having a longitudinal bore, the center line of the bore being in alignment with the center axially adjustably mounted in said bore.

WALTER w; EVERTS.

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