US1578647A - Propelling system for ships - Google Patents

Description

March 30 1926. 1,578,647

G. DE MEO PROPELLING SYSTEM FOR smFs Filed June 16, 1925 2 Sheets-Shee t 1 Mgrch 30 (5. DE MEO PROPELLING SYSTEM FOR SHIPS Filed J1me '16 1925 2 Sheets-Sheet 2 and vessels,

Patented Mar. 30, 1926.

PATENT OFFICE.

GIOVANNI DE M30, or GENOA, ITA-LY.

rnor'nnnme sYs'rnM roe snrrs.

Application-filed June 16, 1925.

To all whom it may concern: 7

Be it known that I, GIOVANNI DE Mno, a subject of the King of Italy, residing at 31 Via XX Settembre, Genoa, Italy, have invented, certain new and useful- Improvements in Propelling Systems for Ships, of which the following is a specification. p

This invention .relates to the propulsion of ships and vessels and has for its object to provide means to overcome the vibration incidental to the use of screw propellers and the conventional arrangement of the driving mechanism therefor.

Experience has shown that the .modern tendency of building longer and longer ships results in the use of excessively long propeller 'shafting and also increases the changes of the propellers and their shafts racing, due to the pitching of the vessel.

V hull, each From careful experiments made by the inventor it has been shown that vibration is due at least to two causes: (1) The excessive length of the propeller shafting with the motive power-at one end and the screw propeller at the other behind or adjacent the stern, and (2) that the water passes toand through the propeller blades at an angle to the shaft axis 7 instead of flowing parallel thereto.

According to the present invention, the vibrational effects in a- 'ship are overcome by arranging the propelling'means on each side of the vessel at or about midship and drivenby a motor arranged as close as possible thereto, each propeller being housed in a recess of stream line form and situated just above the bilge portion of the keel, and with the axis of the propeller shaft situated inside the line or surface of the hull, whereby the water flowing to and through the bladeswill move parallel with the longitudinal axis of thepropeller shaft.

In connection with screw propellers for ships, it has been proposed in order to divide the engine power to arrange the engines and propellers in pairs on opposite sides of the engine directly driving its own propeller shaft. Each propeller is accommodated in a longitudinal depression of the hull but the form of such depression is not such as would decrease the resistance to the flow of water and moreover the arrangement of the motor entails an excresence on the hull that will still further increase the resistance. It has also been suggested in a small boat to arrange a propeller amidship, the shaft 'thereof forming a part of-a crank shaft, and

Serial No. 87,571.

the arrangement being housed within a recess of partly annular form beneath each side of the hull.

Therewill now be described with reference to the accompanying drawings one embodiment by way of the example for carrying the invention into effect.

, Figure 1 shows,

diagrammatically, side view of a vessel driven by steam engines of 5 v the reciprocating type or by steam turbines in driving connection with the propelling. system according to the present invention. Figure 2 shows diagrammatically in plan View the propeller applied toa vesselr Figure 3 shows diagrammatically in transverse view the recess at each side of the ship, in which the propellers are arranged. Figures 4 and 5 are diagrammatic transverse sections of the ship taken on the lines X-X and Y-Y respectively, of Figure 2.

Figure 6 represents, diagrammatically, and in larger scale, the horizontal section of .the recess A through the propeller shaft with the horizontal propelling system.

Figure 7 shows in larger scalethe transverse positionof the, screw propeller and its connection with the propeller shaft.

Figure 8 shows diagrammatically and on an enlarged scale the propeller with one blade in section composed of four consecu tive blades forming in total an helicoidal propelling surface. Figures 9, 10, 11 and 12 show, each in end view, and cross section, some details of the bosses of propeller bl a-des for different sizes or cases; v

Towards the lower part of the sides of a ship and beneath the water load line, in the corresponding region of the centre of gravity of displacement or center of buoyancy of the vessel, in. normal loaded draft and at a suiticient depth of water above the edges of the propeller blades, is a recess A of determined and sufficient size and form, as shown in Figures 2 and 6, where the propelling system is arranged. The line of the recess and its form alongside the .hull is of such geometrical form and extension as to ensure that the total skinfriction or frictional resistance of the submerged part of the hull is not increased'as compared with a hull of ordinary construction. The recess is given a practical shapein accordance with the changing form of the geometrical transverse section in order to give free passage to the stream of water projection of the new 80 arising from the combined motion of the submerged hull and of the present propelling system, the determination of the'proper or suitable sha e being calculated for each type of vessel an for a determined speed of nor mal running of the ship, say by calculation or by experiments in a Froude tank.

In each of the recesses A, above mentioned, is installed the propeller shaft B parallel or not to of the hull and situated at such height to avoid any emersion of the propeller blades even at the maximum angle of rolling of the ships in normal condition of sea-goin The propeller shaft B is connected wlth the motor shaft of the propelling machinery througha sternbushing C and to the thrust bearing S (Figure 2) and to the reduction gears D connected to the turbines F or other proper screw nuts M other is t pe of 'pro ulsion engines. The opposite eiid of the impeller shaft is supported by a. suitable bracket H and protecting termin'al cone N. Between the stern bushing C and'the bracket H are installed, properly keyed, the consecutive propeller blades, each with its own boss L. The bosses L are properly connected with the keys G in such position that the propeller posed circumferentially at equal distance etween, forming a total circumference. The'propeller bosses are to be fixed with or by. other suitable stops to fix in proper position the various blades to the pro eller shaft.

The ropeller lades I are disposed symmetrica ly, followin an entirely helicoidal surface of one comp ete pitch, adapting the propelling system for any reasonable number of propeller blades from three and more.

he use of propellersin which the blades are arranged on the shaft one behind the A not enerally new .and no broad claim is made erein to such a form.

The lpropeller blades I may be cast in one with t eir bosses in case of small eligine power, or can be keyed, as shown in Figures 8, 9 and 10, or by other systems in use, or

for suitable adjustadapted, within limits,

In both cases the ments of their pitch. most suitable pitch of the propeller blades, for a determined form or size and propelpower, can be obtained by calculation or y experience in order to obtain the best propelling efliciency. The above illustrated new propelling system, disposed alongside thevessel, and the ractical impossibility that all-the propeler blades can emerge above the water line during changes in the running condition of the ship in heavy seas, due to pitching and rolling, show clearly how the system contributes to the almost entire elimination of the vibrations mainly caused by the normal and extraordinary reactions arising from adjacent the longitudinal section blades I are dis the present stern and, consequently, how far stabllity can be obtained, even transverse, on modern shi s.

bviously for the proper practical application of th above illustrated device the ably modified; the propelling machinery can be disposed differently than in: use at pres ent, but the great economical and commercial advantages arising from the application of this'new system of ship propulsion, even for some classes of vessels already built and others to be built, will render convenient water lines of the hull can be suit practice of propelling at the the general practical adoption of the above dev1ce,'.even. for better protection of screw propellers in some special class of war vessels or in recently built both passenger and mercantile ships.

Constructional variations of the embodiment fully described above are possible but without departing from the main principles and objects of the present device. I

Having now particularly described and ascertained the nature-of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. Improved propelling system for the purpose of overcoming vibration. in a ship or vessel, comprising. propelling means arranged on each side of the vessel at or about midship, a motorito drive said propelling means arranged in close proximity thereto, each propeller being housed and arranged entirely in a recess of stream line form with which the ship is provided and situated just above the bilge portion of the keel and so that no portion of. the propeller projects beyond the outline of the hull, and with the axis of the propeller shaft situated inside the line or surface of the hull, whereby the water flowing to and through theblades will move parallel with the longitudinal axis of the propeller shaft.

2. The combination with a propelling system as claimed in claim 1, of screw propellers comprising a series of propeller blades, each with its own boss successively keyed one behind the other and radially displaced on the longitudinal horizontal propeller shaft at such a distance, both circumferential and longitudinal, that the propelling blade surfaces are substantially on the same cylindrical helicoidal surface,

the propeller shaft being supported at one end by a suitable bracket and at the other end by an adapted stern tube reaching inside a suitable thrust block and ending in the reduction gear connected to the turbines or other system of propelling machinery.

In witness whereof I aflix my signature.

GIOVANNI DE MEO.

forming together a whole pitch of the screwpropeller,

Illa

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