US3361107A - Peripherally driven ship propeller - Google Patents

Description

Jan. 2, 1968 E. R. WEBER PERIPHERALLY DRIVEN SHIP PROPELLER 2 Sheets-Sheet 1 Filed Oct. 11, 1965 BY AMI/FM ATTORNEY E. R. WEBER PERIPHERALLY DRIVEN SHIP PROPELLER Jan. 2, 1968 Filed Oct. 11, 1965 2 Sheets-Sheet 2 INVENTOR 5mm A. W455? BY, m 4/ meme ATTORNEY United States Patent 3,361,167 PERIPHERALLY DRIVEN SHIP PROPELLER Edward R. Weber, Rowayton, Conn, assignor to Esso Research and Engineering Company, a corporation of Delaware Filed Oct. 11, 1965, Ser. No. 494,587 4 Claims. (Cl. 1l534) ABSTRACT OF THE DISCLOSURE A peripherally driven ships propeller permitting optimized location of the propulsion unit in the stern portion of a ship and enhanced hydraulic flow to the propeller. Annular bearing means are provided for rotatably supporting the propeller shroud to transfer thrust and static loads to the ship and to isolate the ring gear upon the propeller shroud periphery from sea water.

This invention relates to ships in general, and in particular to an improved drive and method of mounting a ship propeller to reduce vibration and make it more efficient in operation. The invention also relates to an improved propeller drive for ships which permits optimized location of the main propulsion motor within the ships hull.

In conventional ships using one or more stern mounted propellers, the propeller efficiency is decreased to a certain extent because of the large driving shaft employed at the rotative center of the propeller which of necessity must be supported by a full bossing or underwater struc ture of the hull immediately forward thereof. This bossing and large underwater structure forward of the propeller impairs the water flow into the forward face of the propeller, and this impairment of water flow will cause different forces on the propeller blades during their rotation. This uneven flow of water through a conventionally mounted propeller is one of the principal causes of propeller induced ship vibration and has frequently been remedied in part by the use of shrouding about the propeller periphery in order to make the flow forces more even throughout the frontal area of the propeller.

Another result of conventional center or rotation drive for a ship propeller is that it generally requires the location of the propulsion engine in a lower portion of the hull structure, which with a minimum overall drive shaft length, makes the stern of the hull unnecessarily full. These full stern lines also impede the optimized flow of water through the propeller.

The present invention is concerned with a propeller drive arrangement including all the known advantages of shrouded propellers and in addition, the substantial elimination of the disadvantages of conventional center mounted drive shafts. In one form of the present invention, the conventional centerline drive shaft is replaced by a drive shaft at the top exterior of a shrouded propeller disc which is rotated by means of a coupling engaging the shroud circumference. The coupling between the drive shaft and the propeller shroud may be either by direct gearing, a hydraulic coupling, or a friction drive shroud encircling the propeller. In accordance with the invention, the shrouded propeller is supported about its periphery by a fixed outer shroud or race which may be partly open at one or more points in its outer periphery to permit engagement of driving means. With this arrange ment, the location of the ships propulsion engines need not be at a low point within the hull immediately forward of the propeller but may be, and preferably are, elevated within the hull to a point approaching the load water line. This ability to relocate the engine to a higher point within the hull structure permits the relieving of the hull shape forward of the propeller to enhance the flow of water thereto. Furthermore, the use of the periphcry of the propeller shroud as a portion of the drive train eliminates much of the needed reduction gearing normally associated with high speed ship propulsion engines and the low speed propeller. Another feature of applrcants optimized propeller drive is that the drive shaft 1s raised to or near the water surface thereby reducing the high water pressure at the point of shaft exit through the hull normally associated with lower placements of shaft exit positions. Accordingly, those skilled in the art Will readily see how applicants improved ship drive means arrangement has produced a shrouded propeller having improved efficiency with a minimum of vibration forces induced by the passage of any portion thereof into areas closely adjacent the primary hull structure.

Therefore, it is the principal object of the present invention to provide an improved ship propulsion system having increased efiiciency, lower vibration forces, less susceptibility to shaft leakage, and reduced gearing costs.

Another object of the invention is to provide an improved ship propeller drive permitting optimized location of the propulsion engines within the hull structure.

These and other objects and advantages of the invention will become apparent and the invention will be fully understood from the following description and drawings in which:

FIG. 1 is a perspective view of the stern portion of a ship showing one form of the invention;

FIG. 2 is a partial cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a view similar to FIG. 1 showing a modified form of the invention; and

FIG. 4 is a view similar to FIG. 1 showing another modified form of the invention.

It will be understood that the several drawings illustrate merely preferred embodiments of the invention, and that other embodiments are contemplated within the scope of the claims hereafter set forth.

Referring to the drawings in particular, the stern end of a ship lit includes a conventional rudder l2 and a main propulsion engine 14 which may be of any conventional type, such as diesel, steam turbine, etc. An output shaft 16 extending from the motor 14 carries a pinion gear 18, the teeth of which engage corresponding gear teeth 26 formed in the outer peripheral shroud 22 surrounding the tips of a propeller (see FIG. 2). The propeller 26, thus driven by the engagement between gear 13 and teeth 26 is supported in a fixed outer support shroud generally indicated at 24. The support shroud 24 is attached at an upper portion to the ships hull structure and includes an annular retaining ring member 28 along its rearmost edge. The retaining ring 23 is attached to the shroud 24 by means of any conventional securing means such as bolts 30. The inner rotating shroud 22 encircling the propeller blade tips includes a pair of edge flange portions 32 which respectively engage a forward thrust-bearing surface 34 and a reverse thrust-bearing surface 36. Each of the bearing surfaces 34, and 36 are preferably made of any suitable metallic or plastic bearing material.

In FIG. 3, an alternate embodiment of the invention is shown wherein a horizontal support member 452 extends from a lower portion of the bull to rearwardly to a lower portion of the fixed outer shroud 24. The support 42 provides added structural strength to the shroud 24 and reduces the bending moment thereon. Additionally, FIG. 3 differs from FIG. 1 in that a thrust shaft 38 extends from the center of rotation of the propeller 2t) forwardly to a thrust bearing box 40. The shaft 38 may be made of minimum diameter as it is not required to transmit any substantial torque to turn the propeller, this being accomplished by the peripheral drive gear 18. However, the thrust shaft 38 will be effective to transmit the greater portion of the forward propulsion thrust of the propeller directly to a suitable bearing 43 located on the ships primary hull structure, thereby reducing some of the normal thrust load occurring on bearing surfaces 34 of FIG. 2.

In FIG. 4, a further embodiment of the invention is disclosed. In FIG. 4, as in FIG. 3, elements having counterparts in the embodiment of FIG. 1 have been designated with like numerals and will not be described again. However, in FIG. 4 it will be seen how a forwardly extending curved fairing wall portion 44 is joined at its rearmost edge to the forward edge of the fixed shroud 24 and extends into and connects with the plate structure of the ship hull 10. The fairing portion 44 in combination with a corresponding fairing portion (not shown) on the opposite of the ship hull forms a semicircular tunnel 46, extending forwardly of the propeller 20 to provide a water duct for the smooth passageway of water to the forward face of the propeller. In this embodiment of the invention, as in the other embodiments, it may be seen how the peripheral drive of the ships propeller 20 permits the elevation of the drive motor 14 to an upper portion of the hull structure, at or near the normal load water line designated 4%. In this location, due to the fact that the drive shaft from the motor need only exit the hull at a water level close to the water surface, considerably reduced hydrostatic pressure will be experienced by the shaft seal in contrast to conventional propeller drives wherein the shaft is ordinarily at a water level coincident with the center of rotation of the propeller. In each of the embodiments it will also be readily apparent to those skilled in the art that the repositioning of the ships propulsion engines to a higher elevation permits more flexibility to the hull designer in optimizing the hull shape immediately forward of the propeller so that improved fluid flow to the propeller is obtainable. The improved fluid flow and removal of any significant hull structure from the immediate area forward of the propeller greatly increases its efiiciency and reduces the ordinarily induced vibrations occurring with conventional propellers as their blades pass by closely adjacent portions of the hull structure.

While applicant has for convenience illustrated his invention as employing a pinion gear drive 18 engaging with gear teeth 26, those skilled in the art will readily appreciate that other power coupling means could be employed in lieu thereof and it is wholly within the scope of applicants invention to include hydraulic or friction drive means in place of the illustrated gear drive means.

While several specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. In combination, a ship having a normal load Water line, and drive means located at the stern of said ship; said drive means comprising a bladed propeller, annular shroud means secured to the tips of the propeller blades and surrounding the periphery thereof, said shroud means having a forward-facing annular face and a rearwardfacing annular face defining a plane parallel to said forward annular face, gear means formed in an exterior peripheral surface of said shroud means between said forward-facing annular face and said rearward-facing annular face, stationary annular mounting means surrounding and enclosing the periphery of said shroud means and annular faces, a pair of L-shaped crosssection annular bearing means interposed between the outer periphery of said shroud means and said mounting means, the upright leg portions of each of said bearing means being in sliding contact with their respective faces for transmitting the thrust load on said shroud means to said mounting means, the foot portions of each of said bearing means being in sliding contact with the outer periphery of said shroud means adjacent said gear means for transmitting the gravity load of said propeller to said mounting means, whereby said bearing means effectively seals said gear means from the sea water, means securing an upper portion of said mounting means to said ship, motor means within said ship located proximate said normal load water line, and shaft means coupling said motor means in a zone proximate said load water line with said gear means.

2. The combination in accordance with claim it including an elongated generally horizontal strut support member extending between a lower portion of said annular mounting means and the hull of said ship.

3. The combination in accordance with claim 2 wherein said bearing means are made of plastic material and further including auxiliary thrust shaft means extending from the center of rotation of said propeller forwardly to a rigid underwater portion of the hull of said ship.

4. The combination in accordance with claim 1 including a curved support means extending forwardly of said stationary annular mounting means forming, in combination with a lower recessed area of the hull of said ship, an open tunnel for the smooth and uniform flow of water to the forward face of said propeller.

References Cited UNITED STATES PATENTS ID. 138,752 9/1944 Naterval. 2,085,282 6/1937 Waterval. 2,745,370 5/1956 Manis.

MILTON BUCHLER, Primary Examiner.

T. MAJOR, Assistant Examiner.

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