US2638171A - Automatic variable pitch propeller - Google Patents

Description

May 12, 1953 F c, Foss 2,638,171

' AUTOMATIC VARIABLE PITCH PROPELLER Filed Sept. 50, 1947 2 sheets-sheet 1 Fig. 7.

Inventor F [9. 6. Freeman 0. Fuss y 12, 1953 F. c. Foss 2,638,171

AUTOMATIC VARIABLE PITQI-I PROPELLER Filed Sept. :50, 1947 2 Sheets-Sheet 2 36 I W /V Inventor Freeman 0. Foss Attorneys Patented May 12, 1953 "1Z5 UNITED STATES PATENT OFFICE AUTOMATIC VARIABLE PITCH PROPELLER Freeman 0. Foss, Twin Falls, Idaho Application September 30, 1947, Serial No. 777,004

This inventionappertains to novel and useful improvements in propellers of the automatic cOntrollable pitch type.

An object of this invention is to provide an improved blade construction which, by selectively shaping certain portions thereof, the blade 18 urged to selected controlled pitch positions while being acted on by a fluid medium.

Another object of this invention is to provide means for retaining propeller blades in the reversed flow position.

Another object of this invention is toprovide means for adjustably controlling the travel of the blades.

A further object of this invention is to provide means for controlling the pitch of the propeller blades in order that the usual power plant associated therewith may be operated at the most efficient horsepower output.

Another purpose of this invention is to provide a relatively simple device capable of performing all of the above mentioned objects which is commercially feasible, practical and smoothly operative.

Other objects and features of novelty will be come apparent to those skilled in the art, in following the description of the preferred embodiment of the present invention, illustrated in the accompanying drawings, wherein:

Figure l is an elevational view of the present invention;

Figure 2 is a fragmentary front view of the invention disclosed in Figure 1 and taken substantially on the line 2-2 thereof and in the direction of the arrows;

Figure 3 is a longitudinal sectional view of the actuating means with the propeller blades removed, taken substantially on the line 3-3 of Figure 2 and in the direction of the arrows;

Figure 4 is a side view of theinvention disclosed in Figure 1, the blades being in a reversed position and portions being broken away in section to illustrate details of construction;

Figure 5 is a perspective view of the cam means forming part of the invention and the offset shaft for pivoting the blades;

Figure 6 is a reduced plan view of the body member forming part of the invention, portions being broken away to illustrate details of construction;

Figures 7, 8 and 9 are sectional views of the blade construction taken on the respective lines of Figure 1.

The device illustrated by the present invention may be utilized with substantially all outboard 1 Claim. (Cl. 170-160.51)

and inboard motors as either an accessory or, if desired, a stock part. The general operation of the invention is relatively simple and will be set forth at this time, since this will lead to a better understanding of the mechanical elements to be set forth hereinafter.

A plurality of blades ID are provided which, due to a particular flare back on the trailing edge, the pitch of the blades vary whenever the motor speed is changed. Each of the blades utilized in the present invention is pivoted at substantially the center of pressure or in a plane parallel or substantially parallel thereto. Of course, it is well known that the center of pressure varies under certain conditions. However, it is also realized that the said center of pressure varies onl within certain limits and it is within these limits that the pivot for the blades is secured. Due to the water pressure increasing on the blades as the same increases in torque and decreasing when the motor is decelerated or torque is lessened, the blades always seek a predetermined value of pitch angle, commensurate with the most efficient operation of the associated power means.

There is provided cam means for actuating certain elements to be described later, and this cam means is provided with a flat part whereby the blades may even be held in a position to effect traction in a reverse direction. Under these conditions the pivot point of each blade is in a dead center relation with regard to an edge ofthe cam and the urging force of either the spring or the hydraulic means.

Taking, now, a feature of the present invention, the blades will be described in detail. The leading edge of each blade is provided with a slight sweep back l2. The trailing edge of each blade is provided with a forwardly flared portion I4. The last-mentioned flared portion forms'a material part of the present invention, since it is this forwardly flared portion which, when utilized in conjunction with the pivot location, urges the blades automatically to the proper pitch position. A cam I6 is secured to the base of each blade and the cam has a flat part or seat l8.

A shaft 20 is secured to each cam l 6 and is substantially at the center of pressure of the blade as a whole. It will be noted that the said shaft 20 is supplied with threads at the terminal portion thereof.

A body member or housing 22 is provided for use in conjunction with the present invention. For this construction, reference is made to Figure 3 wherein there is disclosed the body member 22 having a sleeve 24 slidably disposed thereover. Bearings 26 with apertures 21 are secured to, or formed integral with the body member 22 adjacent one end thereof for the purpose of supporting the shaft 20 of the respective blades. The flat cams l6 engage a complemental cam surface I! on the forward portion of the said sleeve 24 and, as the blades are rotated about the pivot pin 20, the sleeve 24 is urged axially of the housing or body member 22, against the biasing action of a spring 28.

The spring 28 is disposed between the sleeve 24 and the housing 22. The terminal portion of the said housing 22 is externally threaded and a nut 30 applied thereto in order to retain the said spring 28 Within the sleeve 24. Suitable packing means 32, conventional in nature, may be supplied as well as any number of Washers and the like, which may be found advantageous- It will be noted that a plurality of apertures 34 provided in the body member 22 for the purpose of preventing vacuum lock between the member 22 and sleeve A power shaft 3t extends through the said housing 22 and a shear pin 31?, extendsv therethrough and through said power shaft. The terminal. portion of the shaft 3% is received in a second. housing 49, positioned within a bore in the said. housing 22. This second housing 40 is threadedly received on the terminal portion of the said power shaft St. A limiting bolt 42 is provided, in the said second housing id and en-- gages-the said power shaft Means. for limiting the pivotal travel of the blades is. provided. This means consists of a pair of set screws 44 and respectively, which are adj-ustabiy secured in holes in an outer 41- of said: housing These set screws engage a selected portion of the said cams it, as is quite apparent. from an inspection of Figure 1.

As is' seen in Figure 1, the shaft 25 extends through the bore 275 or the bearing 26 and a. suitable castle n-ut or the like 48 is applied to the threaded. portion thereof. of course, a cotter pin 50, or the like, may be utilized in conjunction therewith for the. usual function of retaining the castle nut. in the desired, tight position.

It is noted that most outboard motors or even inboard motors utilize the conventional gasoline or oil asfuel. Accordingly, in marine engines of this nature, fouling and insufiicient operation may be effected if the engine operated very slowly for a. long time. With theuse oi the present invention, the engine may run or operate at a. higher value of R- F. and. supply the same horsepower output or value of torque- Obviously, this permits higher eiiiciency of engine operation.

A portion of this reserved, slower speed of. engine operation can be used to reverse the direction of. the water displacement by the blades. At difierent values. of torque, the blades, due to the flare back of the trailing edge and due to the advantageous. position of the pivot on, or substantially onv the center of pressure, assume varied angles of. pitch- At very slow speed, the pitch angle approaches a reverse direction and even upon slower speed, the blades actually do reverse flow of displacement- Since the fiat part it of the cam I6 is then. disposed on the cam surface 4 H, the blades will be retained in this reverse direction until a burst of speed pulls them out of this reverse direction. The cams it may be designed in such a way that slight increase in speed may be efiected without pulling the blades from their reverse position in order to obtain a backward motion of the entire boat on which the invention is applied. Of course, since the blades are in the very slightly reversing direction or flow-producing direction, starting of the engine will be materially reduced in difficulty due to the almost absence of torque required to propel the blades in this position.

Having described the invention, what is claimed as new is:

In a controllable pitch propeller, a body member of longitudinal form and having a longitudinal axis, a sleeve concentrically located on the exterior of a part of said body member and slidable axially of said body member, means operatively' connected with said sleeve and said body member yieldinglyrestricting relative axial move.- ment of said sleeve and said body member, a bearing at one end. of said: body member, said bearing having openings therein each of which has a longitudinal. axis perpendicular to said b dy member axis, blades, pivot pins securedv to the root ends of said blades and. disposed in said openings thereby rotatatively' mounting, said blades about axes of rotation normal to said longitudinal axis of said body member, cams fixed to the root ends of said blades and each cam havingv a land, oomplemental cam, means on said sleeve contacted by said cams so that when said blades are rotated. a predetermined amount to move the sleeve away from said 0116:61Idof said body member, said lands rest upon: said cam means to" retain. said blades? rotated, adjustable means on said body member and: in the path. of rotation. of: said cams for limiting the. rotation; of said blades as sleeveis. moved toward the said one end of said body member, and means comprising curved. trailingedges. of each of Said blades for rotatively urging said blades to varied positions of blade. pitch. angie.

FREEMAN C. FOSS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 136,015 Wilson Feb. 18, v 187 711,021 Thaxter -1 Oct. 14, 190

1,386,490. Boerner r Aug..2,, 1921 1,555,422 Lorenzen Sept" 29-, 1925 1,887,543 Chilton NOV. 15-, 1932 1,978,788 Furgason Oct. 39,1934 1,987,651 Wiegand Jan. 15, 1935 2,005,3sl3. Kent. .--1 1 June 18, 1935 2,997,663. Raggio- Now-2, 1937 2,099,922. Bellman Nov. 23,. 1-937 2,299,666. Ashelrnan et all. July 21, 1942 2,422,138. Seewer June 1.0, 1947? 2,595,434. Troller' Jan. 24, 1950 2,498,109 Lathrem Feb. 2, 1950 FOREIGN PATENTS Number Country Date 7,084 Great Britain of. 1909 10,098

Great Britain Oct. 14,v I909

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