US2255920A - Ship propeller having rotatable blades - Google Patents

Description

Sept. 16, 1941. .1. E. ENGLESSON 2,255,920

' SHIP PROPELLER HAVING ROTATABLE BLADES Filed Jan. 12, 1938 J van/or.-

Patented 16, 1941 smr raorELLEn. HAVING BOTATABLE numes John Elev Englesson, Kristineliamn, Sweden Application January 12, 1938, Serial No. 184,513

In Sweden February 1 Claim.

protected from water which might cause corrosion of the same with a resultant rapid decrease of the endurance strength of the springs. v

With this purpose in view the springs are placed, according to the present invention, in the pressure chamber of the servomotor which is filled with oil or a fluid which does not cause corrosion, and in which a pressure is ordinarily maintained which is considerably higher than the pressure of the water outside the propeller hub. When located in the said chamber the spring or springs '15 or are eflfectively protected against the corrosive-action of ,water which would lower the strengthof. the same. Even it the flange or the packing ofia blade h p ns to become damaged, so that water penetrates into the cavity in the hub in which the crank pins of the #blades are located, such water cannot reach the springs due to the high pressure in the pressure chamber of the servomotor.

The accompanying drawing shows by way of example a constructional form of the invention. The drawing shows an axial section through the hub of a ship propeller in which the rotatable blades are adapted to be set by means of a hydraulic servomotor.

In-the propeller hub illustrated, l denotes the hub body which is rigidly connected to the hollow propeller shaft 2. In bushings 3 and l in 'said two members the hollow piston rod 5 is movable in the axial direction, the servomotor piston 6 being secured to the left-hand .end of said rod: Said piston is movable in the servomotor cylinder 1 which is closed by the head 8, the outer portion of which is formed as a hub cone 8a, and which is secured to the cylinder 1 by means of screws 9. III denotes one of the propeller blades which by means of its flange and the crank pin ring H is journalled on a ring l2 secured to the hub body I, in such manner that the blade is rotatable on an axis perpendicular to the axis of the hub body.

Made integral with the crank pin ring H is a crank pin I which turns in a slide block l3 which is slidable in a groove in a projection from the piston rod 5, said groove being perpendicular to the axis of the piston rod 5. Secured in the sleeve II which forms a seat for a hollow control slide l8 which is movable in the axial direction. Said slide I6 is connected to the slide rod 11 which extends through the hollow propeller shaft 2, and which is also hollow so'that pressure liquid, such as oil, may be supplied through the same for actuating the servomotor.

, In a manner previously described in my U. S. Patent No. 1,510,436 of Sept. 30, 1924, the slide it and the sleeve I! as well as the portion of th piston rod surrounding the latter are so shaped and provided with passages so arranged that when the slide I6 is moved a distance in one direction or the other, pressure liquid is supplied to the chamber on the right-hand or left-hand side of the servomotor piston 6 in such manner that the piston is caused to move in the same direction as the slide l6. For this purpose the slide I6 is provided with two peripheral recesses 3| and 32 which communicate through holes 33 and 34, respectively, with the bore in the slide l6. Upon movement of the slide it to the left from the position shown in the drawing, the recess 3| is put in communication with a port 35 leading through the walls oi the sleeve l5 and piston rod 5 to the chamber on the right-hand side of the piston 5, so that pressure liquid is supplied to said chamber, and the piston is also moved to the left. Again, upon movement of the slide It to the right from the position shown in the drawing, the recess 32 is put in communication with a port 36 leading through the walls of the sleeve I 5 and piston rod 5 to the chamber on the left-hand side of the piston 6, which will thus move-to the right. Upon movement of the servomotor piston 6 the blades 1 II are turned through the medium of the parts 5, l3, I4, and II. The space l8 between the piston rod 5 and the slide it serves, in a manner previously known, as a discharge conduit for pressure liquid from the servomotor.

According to the invention there are inserted in the cylinder head 8, i. e. in the pressure chamber of the servomotor on the left-hand side of the piston 8, two strong helical compression springs I! and 2B, the right-hand ends of which bear against the servomotor piston 6, while the lefthand ends of the same bear against a disk 2| which in its turn bears against a shoulder in the left-hand end of the hollow piston rod 5 is a head 8. If, for any reason, the supply of pressure liquid ceases so that the pressure on the right-hand side of the piston 6 ceases, the piston 6 is moved by the springs I9, 20 to the right in the drawing, until it comes to bear against the bottom of the servomotor cylinderl. In this way the propeller blades II are turned to the position for going ahead.

Itwill be understood that for this purpose the springs must be so powerful that they are capable of iovercoming the frictional forces in all links and bearings and of moving the blades to and retain them in the said position. The provision of. the springs II, 2I thus guards against the ship becoming incapable of maneuvering, if the pump supplying pressure liquid to the servomotor fails, and the blades II happen to occupy inoperative position.

as shown in the drawing, the outer diameter of the helical spring 2I is only slightly less than the inner diameter of the pressure chamber, 1. e. oflthe portion of the head I that surrounds said spring, with a view to prevent too large oscillations of the spring in the transverse direction.

In order that the diflerence in spring tension not be too large when the servomotor piston occupies its left-hand and right-hand extreme positions, it is necessary to use comparatively long springs i 9, 2I. In order to facilitate mounting and dismounting of these long powerful springs the following arrangement is provided. Screwed onto the left-hand end of the piston rod 5 is a stop nut 22 which is intended to cooperate with a stop flange 22 of the disk 2|. These parts are arranged in such relation to one another that the flange of the stop nut 22 bears against the flange 22 when the servomotor piston I bears against the bottom of the cylinder I.

Now, if the screws I which hold the head I to the cylinder 1, are unscrewed, the spring tension is jtaken up by the portion of the piston rod I between the piston I and the stop nut 22. The

head I can then be directly taken off, after which ayoke is forced against the disk 2| by means of longer screws inserted into some of the holes for the screws I. The stop nut 22 is' now unscrewed,

and the springs are relieved of tension. The mounting of the springs is made in a similar manner but in the reverse order.

1 The constructional form above described and illustrated in the drawing is only to be regarded as an example and it will be'understood that it is capable of modification in various ways in respect of its details without departing from the principle of the invention.

I claim: In an adjustable propeller blade assembly, a hollow shaft, a hub surrounding the end thereof and having a removable end cap, blades rotatably mounted in said hub, a sleeve having a piston secured thereon and slidable on said shaft, connections between said sleeve and said blades to rotate the latter, said piston being mounted to reciprocate in a cylindrical'chamber in said hub, said chamber having a removable end wall seated in said cap, a helical spring positioned in said cylindrical chamber with a slight clearance between the two and confined between said piston and said removable end wall to thereby tend to maintain said piston and blades normally in one of two extreme positions for normal operation of the propeller, and valve means admitting a noncorrosive fluid under pressure from said hollow shaft to said cylindrical chamber to move said piston one way or the other, said spring being continually immersed in said non-corrosive fluid to prolong the life thereof.

JOHN ELOV ENGLESSON.

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