WO2006048691A1

WO2006048691A1 - Variable pitch propeller with stern tube integrated mechanism

Info

Publication number: WO2006048691A1
Application number: PCT/HR2004/000043
Authority: WO
Inventors: Nenad Fles
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-11-03
Filing date: 2004-11-03
Publication date: 2006-05-11
Anticipated expiration: 2007-05-03

Abstract

The invention is aimed to simplify conventional variable pitch propeller mechanism in a way to reduce number of moving parts, incorporate mechanical actuation instead of hydraulic, improve compactness and separate torsional shaftline loads from normal ones. Unlike the conventional system the patented one is based on inverted principle: rotation of propeller blades is not acomplished by linear movement of pins (19) but with movement of propeller hub (17) itself. Hub is provided with flange (30) firmly connected to propeller shaft (4) which is put in linear movement by means of electric motor and gears (8) (9) together with thrust bearing (5)(6) housing (7). Other components of shaftline (1)(27) are not effected due to slidingonly torque transmitting- connection (2). Basically, invention combines pitch actuating and thrust bearing functions embodied in single source produced, easy to install, compact and rigid unit. Favourable load distribution between components, improved watertight integrity, ease of maintenance of electro-mechanical drive and ability to withdraw the propeller shaft while propeller remains in its position are some of the major advantages of the invention. Instead of electro mechanic drive system can accept hydraulic drive in a way that thrust bearing housing (7) simulates piston of the cylinder (13) fed from hydraulic system which is identical to what is usually provided for conventional CPP system. Principle of fixed- non-rotating- propeller carrier (22) can be utilized for fiEed pitch propellers as well.

Description

VARIABLE PITCH PROPELLER WITH STERN TUBE INTEGRATED MECHANISM

TECHNICAL FIELD

The invention relates to a marine propulsion systems, in specific, it relates to variable pitch propeller mechanism. BACKGROUND ART Well known variable pitch propeller mechanism for actuation of blade movement features one hub / shaft or gearbox mounted piston served by hydraulic oil system with oil supply to rotating drive line and feed back response to not rotating oil distribution box. Whatever the postition of the piston is, there should be pull-push rod or control rod or oil distribution pipe lines fitted within hollow propeller/ intermediate shafts. This is expensive, complex and vulnerable execution with lot of moving parts being in sensitive geometrical / mechanical relations under varying normal and torsional loads along the shaftline.

Any possible invention should aim to reduce number of moving parts, incorporate mechanical actuation instead of hydraulic, improve compactness and simplify load pattern by separation of radial and torsional loads.

DISCLOSURE OF THE INVENTION

The invention, featuring all listed advantages, should be based on inverted concept with integration of the primary functions within compact stern tube. Invented arrangement, shown on Fig 1 and Fig.2 comprises input shaft

( 1 ) sliding freely in sliding groves ( 2 ) of the bush ( 3 ) machined at the forward end of propeller shaft ( 4 ). Propeller shaft is provided with thrust flange ( 5 ) supported by conventional pads ( 6 ) for ahead and astern thrust. Pads ( 6 ) are arranged within rigid housing ( 7 ). Longitudinal position of housing ( 7 ) is controlled by means of wheel

( 8 ) acting on outside screwed part of bush ( 29 ) and gear ( 9 ) driven by electric motor ( 10 ) fitted on the housing ( 11 ). Pads' housing is prevented from rotation by means of rods ( 12 ) sliding within cylinder ( 13 ) (and serving also for pitch feed back data transfer) which is fitted at the forward end of the sterntube ( 14 ).

Oil lubricated bearings for propeller shaft ( 15 ) are provided with seals ( 16 ) at both ends of the thrust bearing housing ( 7 ). Longitudinal movement of propeller shaft ( 4 ), which is flanged to propeller hub ( 17 ), produces movement of blade flange ( 18 ) relatively to blade actucting pins ( 19 ).

Blade actuating pins ( 19 ) are fitted on bush ( 20 ) provided with sliding surfaces ( 21 ) not allowing any longitudinal displacement but allowing the bush to rotate freely on the hollow carrier ( 22 ) flanged to stern frame casting ( 23 ). Conventional aft seals ( 24 ), fitted on the hub and therefore rotating with the hub around propeller carrier (22) protects from water ingress / oil leakage in / from the hub ( 17 ). Dryness of sterntube ( 14 ) is facilitated by means of seals ( 25 ). In case of failure of electrical sources onboard the vessel hand lever or battery driven wrench can be applied at the extension ( 26 ) of electric motor shaft.

Complete stern tube ( 14 ) with propeller carrier ( 22 ) is provided for mounting into stern frame casting ( 23 ) welded to the ship structure. Withdrawal of the system components straits with short input shaft ( 1 ) (after dismantling of intermediate shaft ( 27 ) ), continues with gear housing ( 11 ), gears ( 8 )( 9 ), forward flange ( 28 ) and screwed bush ( 29 ) in order to facilitate propeller shaft ( 4 ) to be drawn inboard the vessel (providing that flange ( 30 ) is released from the shaft) by means of ordinary lifting beam ( 31 ) and lifting gear ( 32 ). Disamantling of propeller is acomplished by release of flange ( 30 ) from the propeller shaft ( 4 ) and hub ( 17 ), release of ring ( 21 ) followed with sliding of complete hub ( 17 ) with bush ( 20 ) backward along the carrier ( 22 ).

As long as propeller shaft ( 4 ) is in its position dismantling of propeller is possible while ship is afloat, suitably trimmed, as seals ( 25 ) will prevent from water ingress into the stern tube. The invented system offers following advantages: = CPP propeller function comprised in single source produced compact unit - not effecting the rest of shaft line or gearbox. Therefore, patented system can be easily retrofitted (fixed pitch propeller exchanged with CP propeller).

= rigid execution designed to receive thrust forces as close to the place of their origin as practicable. Transfer of thrust forces to gear box or main engine thrust bearing is therefore eliminated meaning that thrust variation cannot effect power train components and their fastening to the vessel's structure. = accordingly, an elastic coupling can be provided anywhere in the rest of power train not suffering from the thrust forces. = simple and compact mechanical pitch control mechanism, accessible at any time for visual inspection and maintenance as rods ( 12 ), which are in fact feed back extension (s), are not rotating as it is the case with conventional CPP mechanism. = no hydraulic oil (pressure) system with pumps, tanks, piping and oil distribution box, only wiring, electric motor and electric / electronic/ electromagnetic controls. To increase safety of the system two electric motors can be fitted for pitch actuation, ( on both sides of shaft ( 33 )) ,one fed from main electricity sources, another from emergency sources.

= relative movement, rotational or linear, is limited to parts which already perform some form of their inherent movements.

With exception of thrust pads' housing, which moves solely to produce longitudinal movement of the system, there are not any component of the system which do not move in performing its basic duty, therefore, number of contact surfaces, serving simultaneously for rotational and linear movement, is the smallest possible.

= as propeller weight is supported by carrier ( 22 ) propeller shaft ( 4 ) does not suffer from concentrated normal loads (except its own weight which is uniform load ). Pressure distribution in propeller bearing is rather uniform, without pressure peaks usually encountered at the aft portion of the aft stern tube bearing of conventional system.

Elastic line of propeller shaft itself is very moderate one reducing therefore possibility of whirling occurence. = alignment of propulsion components is facilitated as tolerances of longitudinal adjustment, due to sliding connection between propeller shaft and intermediate shaft(s) / engine, are relatively wide.

= unlike to hub mounted actuating piston design, oil in hub of invented system serves only for lubrication purposes and therefore may be replaced with water - providing that care is taken of proper selection of the materials being in sliding contact one to another. This simplifies the unit as main seals ( 24 ) can be deleted (except sand protection) while watertight integrity of the stern tube is maintained by seals ( 25 ).

Claims

1. Patent is requested for marine propulsion system featuring stern tube ( 14 ) integrated thrust bearing ( 8 )( 6 )( 7 ) and pitch controlling mechanism for variable pitch propeller comprising sliding input shaft ( 1 ), pitch actuating gear ( 8 )( 9 ) driven by electric motor

( 10 ) producing linear movement of thrust bearing housing ( 7 ), propeller shaft ( 4 ) and propeller itself in fore-aft direction, whereof propeller hub ( 17 ) rotates with the bush ( 20 ) supported by non- rotating hollow propeller carrier ( 22 ) in a way that blade pitch change is not acomplished by pin joke movement, as it is normally the case, but, on contrary, by longitudinal movement of the propeller hub ( 17 ) relative to the fixed bush with pins ( 19 ) ( Fig 1).

2. A unit as set forth in claim 1 but designed for inboard mounting of stern tube ( 14 ) in which case stern frame casting can be of smaller diameter to fitt better to the propeller hub ( 17 ) diameter. ( Fig.2)

3. A unit as set forth in claims 1 and 2 above but without gears ( 8 )

( 9 ) and electric motor ( 10 ) as longitudinal movement of the thrust bearing ( 5 )( 6 )( 7 ) is acomplished by pressurized hydraulic oil acting bothsides of housing ( 7 ) in which case housing ( 7 ) simulates piston of the cylinder ( 13 ) and hydraulic oil system with oil flow control is identical to what is normally provided for conventional CPP system.

4. A unit as set forth in claim 1 and 2 but with water lubricated bearings within propeller hub in which case seals ( 24 ) can be deleted and propeller carrier ( 22 ) made shorter.

5. A unit as set forth in claim 1 and 2 but with roller bearings instead of sliding bearings including axial roller bearings in way of thrust bearing pads.

6. A unit as set forth in claim 1 but with permanent propeller shaft flange at propeller side and dismountable thrust bearing flange ( 5 ) with bush ( 3 ) at inboard (front) side, allowing complete withdrawal of gear while vessel is afloat and complete propeller remaining in its position.

7. A unit as set forth in claim 1 but simplified for adaption of hollow fixed pitch propeller in a way that propeller carrier ( 22 ), propeller shaft ( 4 ) with aft flange ( 30 ) and ordinary thrust bearing fitted at the forward end of stern tube serve their primary functions meaning that secondary function - controlled linear movement of the components- need not be acomplished (Fig.5).

8. A unit as set forth in claim 7 but without conventional thrust bearing as thrust forces are taken by sliding axial bearings (34) fitted adjacent to the propeller hub (Fig.6).

9. A unit as set forth in claim 8 but with roller bearings (35) instead of sliding ones (Fig.7).