US2215207A - Screw propeller - Google Patents

Description

Sapt. 17, 1940. o. BRocKHAus SCREW PROPELLER Filed March 7, 1939 INVENTOR. O/fa 5r X46006 5 ATTORNEY}.

Patented Sept. 17, 1940 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to propulsion devices, and more particularly to that character of propeller used for marine vessels, the object of which, generally stated, is the provision of novel 5 devices superior to those heretofore designed both from the point of efliciency in operation and serviceability over extended periods of use.

The invention has for a particular object the provision of a plurality of propeller blades so interconnected over a projected arc of the supportporting hub periphery therefor as to overcome possibility of warping from axial thrust characteristics of the blades.

A further object of the invention in such disposition of the blades is the accommodation to overlapping relationship affording extensive thrust areas axially projecting the range within which the propulsive activity of the blades is constantly maintained upon each given mass of water encountered in the vessels travel. More particularly, said blades are so arranged with respect to one another as to intercept the heretofore common retarding dead wash from a preceding blade, the curvature of each blade moreover, be-

ing designed to direct the encountered water in a relative centripetal action rearwardly of the vessel rather than centrifugally outwardly with its consequent development of a suctional attraction axially of the driving tail shaft. I

A further object, in the elimination of the consecutive thrust actions imparted by blades individually as heretofore designed, is the provision of a propeller assembly acting more as a unit to equalize the drive activity throughout the 360 circumference, overcoming strains and obviating the pronounced vibration heretofore conducted through the supporting tail shaft to the engine andthe vessel.

The invention consists in the novel construc- 40 tion, the adaptation and in the arrangement and combination of parts as hereinafter described and claimed.

In the drawing- Figure 1 is an end elevation of a propeller representative of a preferred embodiment of the present invention.

Fig. 2 is a side elevation illustrating said strucfor rotation within the stern bearing l0.

for the propeller assembly, said shaft mounted H indicates the conventional packing gland. Suchv foregoing structure may be of suitable or well known construction.

Having more especial reference to the present invention, I provide, supported about a relatively elongated hub or nave 20, said nave slidably keyed over the terminal projection [3 of the tail shaft 9 and engaged by the clamping nut l4 thereon, a 10 series of propeller blades designated as "2 l, 22 and 23, each of which is conformed to a general parabolic plan configuration, the outer extremities of each blade being disposed in planes at angularities of approximately 60 from the longitudi- 15 nal and the inner edges being relatively elongated longitudinally and joining the nave over arcs exceeding 240 thereof, said inner edges having an elevational development approximating a cubical parabola with the curvilinear leading and rear 20 edges 24, 25 being curved to merge, or approximately merge, with planes taken through the longitudinal axis of the hub.

More particularly, each of said inner hubward edges 24, 25 of the blades is configured with re- 25 spect to the nave to terminate at or beyond a radial line taken medially through an adjacent blade, with the width of each blade approximating the height of the same.

In its operation, the leading terminals of the 30 blades tend to knife into the water as distin-- guished from the hard bite characterizing the conventional propeller and, following this knifing penetration, the water tends more or less to hug the worm grooves Which lie between the blades in that the particular form of the latter tends to an axial thrust and greatly minimizes the centrifugal throw of the ordinary blade. Stated otherwise, the water which is propelled longitudinally along the nave is very dense with a 40 substantial elimination of air bubbles and, therefore, is a more effective thrust agency. Particularly noticeable in the use of the propeller is the elimination of the customary vibratory hammer, attributed to the fact that each of the 45 I blades is carried substantially about the entire circumference of the nave with a configuration such that the identical curve characterizing the forward half of each blade is reversely applied to the rear half of that blade, thereby arriving at a blade balance as well as a nave balance. In point of fact, it is found that a relatively steady drive is obtained even though a portion of the propeller clears the water.

Attention is directed to the theories propounded by numerous scientific authorities in re the desired activity of a propeller construction, more particularly with respect to the disadvantages in repelling the encountered water centrifugally rather than in planes parallel to the hub axis. In this particular, the inventor recognizes the theoretical construction of the screw propeller designed by Hugh Keitel, for which U. S. Patent No. 1,095,732 was issued May 5, 1914, improvements over the same, however, being considered obvious.

While illustrating and specifically describing the now preferred embodiment of the invention, minor structural alterations might be made without departing from the spirit of the invention and I accordingly confine myself only as limited by the scope of the hereto annexed claim.

What I claim is A screw propeller comprising a nave and a plu- 20 rality of blades of which the outer edge of each blade, viewed from the end as well as from the side of the propeller, is generally parabolic and of which the root edge of each blade, viewed from above, occupies the line of a sinusoid curve, the leading terminal of each of said root edges generally coinciding with the front-end limit of the nave and meeting the latter approximately in the plane of the longitudinal axis of the propeller and of a radial line taken medially through the preceding blade, the rear terminal of each of said root edges generally coinciding with the rear-end limit of the nave and meeting the latter approximatelyin the planeof the longitudinal axis of-the propeller and of a radial line taken medial- 1y through the succeeding blade, said parabolic figures defined by the outer edges of the blades, considered both in end and side elevation, being such that the curve produced at one side of the major axis of each parabola reversely corresponds to the curve produced at the other side of the major axis.

OTTO BROCKHAUS.

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