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Title:
INTEGRATED LATERAL THRUST FOR MARINE CRAFT
Document Type and Number:
WIPO Patent Application WO/2012/007709
Kind Code:
A1
Abstract:
A pair of handed contra rotating propellers (5) on a concentric shaft has a mechanism (4) for reversing the rotation of the rear propeller so that the propellers rotate together at low speed, baffles (6) interrupt the flow from the propellers and generate a lateral thrust without forward or rearward thrust, used with an intuitive joystick controller.

Inventors:
LEWIS IDRIS (GB)
Application Number:
PCT/GB2011/001034
Publication Date:
January 19, 2012
Filing Date:
July 11, 2011
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
LEWIS IDRIS (GB)
International Classes:
B63H5/14; B63H5/10
Foreign References:
US3590766A1971-07-06
FR2678891A11993-01-15
EP2202143A12010-06-30
US20030152461A12003-08-14
DE19524325A11997-01-09
US4074652A1978-02-21
US5009621A1991-04-23
FR2627742A21989-09-01
FR2618406A21989-01-27
US3899992A1975-08-19
US3179081A1965-04-20
Other References:
None
Download PDF:
Claims:
CLAIMS

1 A pair of handed propellers rotating in the same direction on a concentric shaft driven by a main powerplant, with baffles to control the outflow from the propellers.

2 A pair of propellers according to claim 1 , enclosed in a duct with controllable baffles.

3 A pair of propellers according to claim 1 , where the powerplant is a single internal

combustion engine.

4 A pair of propellers according to claim 1 , where the rear propeller is separately reversible by a gearbox on the propeller shaft centreline

5 A pair of propellers according to claim 1, where the rear propeller is separately reversible by a gearbox concentric with the clutch.

6 A pair of propellers according to claim 1 , where the propellers counter rotate but the thrust of the rear propeller is reversed by reversing the rear propeller blade pitch.

7 A pair of propellers according to claim 4, 5, 6, where both propellers are separately

reversible or both propellers can be reversed together before the rear propeller reverse.

8 A pair of handed propellers as claim 1 , where a bevel drive and pinion drive from the powerplant to the propellers is replaced by an alternative mechanism to change the drive direction e.g. worm & wheel or two bevel drives.

9 A pair of propellers according to claim 1 , where the speed of rotation of the rear propeller in either direction is geared to be different to the speed of rotation of the front propeller

10 A pair of handed propellers as claim 1 where the clutch in each driveline is preferred as hydraulic but may be replaced by a mechanical clutch e.g. cone clutch.

11 A pair of propellers according to claim 1 , where the powerplant is a pair of electric

motors each coupled to a propeller and each separately reversible.

12 A pair of propellers according to claim 1, where the main powerplant is an internal

combustion engine driving the front propeller with an auxiliary separately reversible electric motor driving the rear propeller.

13 A pair of handed propellers according to claim 1 , with baffles hinged above the

propellers and separately adjustable to follow the propeller arc or lifted away.

14 A pair of handed propellers according to claim 2, where the propellers are enclosed in a shroud and the baffles are hinged to the shroud and cover blowholes in the shroud.

15 A pair of handed propellers according to claim 14, with blowhole control by shutters.

16 A pair of handed propellers according to claims 14, 15, where the front and rear

propellers are not close coupled and may be in front of or behind the drive leg. A pair of handed propellers as claim 16, where the drive to each propeller may be combined in one leg or in individual front and rear legs.

A pair of handed propellers according to any of the preceding claims, where the invention is applied to multiple engine systems.

A pair of handed propellers according to claim 18 where the baffles are applied only on the inboard side of multiple engine systems.

A pair of handed propellers according to claim 18 where the shroud blow hole and baffle is only on the outboard side of multiple engine systems.

A pair of handed propellers according to claim 20 where the blowhole has no control. A pair of handed propellers according to claim 1 , where the rear propeller is reversed for high speed forward motion, where the baffles are operated as trim tabs to provide a rolling moment to control heel.

A pair of handed propellers as claim 22 where the baffles are operated together as trim tabs to provide a pitching moment.

A pair of handed propellers according to the preceding claims controlled by a mode switch and joystick with optional integration of bowthruster functions.

A pair of handed propellers according to the preceding claims operated by a throttle, mode switch and side thruster lever with optional integration of bowthruster functions. A pair of handed propellers according to claim 1 , where the preferred application is to a sterndrive system may also be applied to outboard or shaft drive systems.

Description:
INTEGRATED LATERAL THRUST FOR MARINE CRAFT

DESCRIPTION

Background

This invention relates to improved lateral control of the rear of a marine craft at low speeds where such craft have inherent difficulty.

Handed contra rotating concentric propellers create forward or rearward thrust without the torque concerns of single propellers. These propellers are generally reversible together.

A propeller duct may increase efficiency, safety or reduce vulnerability.

Main engine / propeller systems are unable to direct thrust sideways unless mounted in a steerable pod or use a water-jet or use multiple engines with vectored thrust. To move the stern of a single engined craft laterally generally requires forward or rearward movement. This can be difficult to control when the centre of rotation of the whole craft changes with the direction of movement.

Conventional stern thrusters may be difficult to fit.

A disadvantage of a typical single engined sterndrive craft is evident when reversing into a berth in that the craft is prone to swing the bow about a pivot point 1/3 the way forward of the stern.

Statement of Invention

To overcome this concern, the present invention proposes the use of handed contra rotating propellers driven by a main engine(s) where a rear propeller is separately reversible. The propellers turning together with an inward flow operate with moveable baffles to force a sideways flow and resultant lateral thrust. The system is preferably controlled at low speed by an intuitive joystick and wheel. Advantages

The use of the main engine ensures adequate power is continuously available without the addition of other systems and that the power can be applied to generate a side thrust without forward or rearward motion.

Preferably the present invention as set out in the appended Claims is applied to a single engined sterndrive craft.

There now follows by way of example of the invention a detailed description to be read with reference to the accompanying drawings in which:-

Fig 1 illustrates the manoeuvrability concern;

Fig 2 illustrates a typical schematic layout of the invention in side view; Fig 3 illustrates a typical schematic layout of the baffles in end view; Fig 4 illustrates a schematic of joystick operation;

Fig 5 illustrates a typical schematic with a full shroud replacing the baffles; and, Fig 6 illustrates alternative blowhole controls in the shroud. Fig 7 illustrates an alternative method of controlling the baffles on a single engine Fig 8 illustrates an alternative for twin engine propellers under the hull without baffles Fig 9 illustrates a 3 shaft system without a reverse gear FIG 1

Typical condition shown where on reversing a sterndrive craft and angling the thrust direction to move the stern sideways causes both a rearward motion and a large swing of the nose around a pivot point 1/3 the way forward of the stern.

Detailed description

FIG 2 illustrates the invention based on a sterndrive (outdrive) system, see :- 1 Engine to drive

The normal method of connecting an engine to a drive would continue e.g. a universal joint

1 and a splined shaft.

2 Split drive lines

After turning the drive through 90° preferably by means of a bevel drive 2a, a drive line would be split in two preferably by a pinion drive 2d

3 Clutches

The invention has a clutch 3 in each drive line.

4 Reversing Rear Propeller Drive

A splined shuttle 4 engages one of two bevel drives to reverse a rear propeller 5b.

5 Propeller design

Propellers 5a and 5b remain unchanged to normal practise, preferably the forward propeller 5a turns clock wise viewed from the rear to generate forward thrust, the rear propeller 5b turns anti-clock wise viewed from the rear to generate forward thrust.

6 Baffles

Baffles 6 are mounted to a cavitation plate and completely cover the propellers 5a and 5b in side view down to a level required to suit the desired thrust.

12 Pinion Drive

A pinion drive 12 splits the drive to the two clutches FIG 3 shows the baffles 6 in end view.

6 Baffles

The baffles 6a, 6b are mounted to a cavitation plate and are curved to follow the propeller arc in end view

FIG 4 shows the joystick 7 operation

7 The joystick 7 has five functions

• Neutral

• Fore / aft to control the propeller clutches

• Lateral to control baffle movement

• Diagonal movement to integrate fore/aft and lateral movement.

• Twist to control bow-thruster

Mode Control (not illustrated)

This would be a switch with three or optionally two functions

• High Speed

• Low Speed

• Neutral Optional

ECU functions (not illustrated)

In the High speed mode the ECU would control functions as a conventional system including engine response to throttle, leg trim etc

In the low speed mode all actions from the Mode Control and Joystick 7 would function through the ECU to control;

• Engine speed rising with joystick demand from idle to a preset maximum;

• De clutching of a propeller to achieve fore aft movement;

• Blowhole shutter opening / tab position to achieve lateral movement; and,

• Time limit status on any electrical bowthruster. As an alternative to the baffles 6 the propellers 5a and 5b operate in a shroud 10 which completely covers the propellers in side view.

The shroud 10 is formed from an extended cavitation plate plus one or more add on lower parts.

Within the shroud 10 are blowhole apertures 11

The shroud contour would suit the operating speed of the craft.

The size of the blowhole apertures 11 can be controlled by baffles 11 A or vertical shutters 11B

The propellers 5a and 5b operate in a shroud 10 that acts as a complete duct; there is no forward or rearward motion with both propellers 5a and 5b turning to balance the thrusts. Blowholes 11 in the side of the shroud 10 open to create a lateral thrust by releasing internal pressure. By opening/closing a blowhole 11 on the appropriate side lateral thrust is controllable.

Fig 6

This illustrates the shroud 10 and blowhole control 11 in end view. Fig 7

This illustrates an alternative method of baffle control where baffle 6a is either fully up for high speed or fully down for low speed mode. Baffle 6b is either fully up for high speed or low speed fully up for thrust in one direction OR partly down for a neutral position OR fully down for thrust in the other direction. The proportions of Baffles 6a, 6b are adjusted to suit.

Fig 8

This illustrates a method lateral thrust for a multi engine installation where the propellers are located under a fixed hull form which acts as a fixed baffle 6c. Operating propellers on one side generates a lateral thrust.

Fig 9

This illustrates an alternative method of separately reversing the rear propeller using bevel drives 2a, 2b, 2c. Clutches 3a & 3b change the direction of rotation of the rear propeller. Clutches 3a & 3c are engaged for high speed mode. Clutch 3b is used instead of Clutch 3a for low speed mode. Operation

The invention includes a High Speed and Low Speed Mode.

High Speed Mode in the forward direction is as common practise. The forward propeller turns to create forward thrust, the opposite hand rear propeller turns the other way to also create forward thrust. Control is via a steering wheel to direct thrust direction and throttle / gearbox lever(s) to control power and direction.

High Speed Mode in the rearward direction is preferably as the low speed mode below.

The invention introduces a Low Speed Mode where the rear propeller is individually adjusted by means of a gearbox such that the rear propeller rotates in the same direction as the forward propeller, thus the rear propeller creates a rearward thrust from a forward flow of water whilst the front propeller generates a similar forward thrust from a rearward flow of water. The propellers working in opposition generate increased pressure between them and a radial outflow from between the propellers. The propellers can be individually stopped.

Partially shrouding the propellers on one side with moveable baffles controls outflow and creates controllable lateral thrust. The baffles are initially set in a neutral position with the propellers turning together or stopped to produce zero lateral thrust. Lifting the baffle on one side with the propellers turning together produces a lateral thrust.

Preferably the tabs retract in the high speed mode to reduce high speed drag.

In the low speed mode the front propeller provides forward motion whilst the rear propeller is stopped by declutching the rear drive, conversely the rear propeller provides rearward motion whilst the front propeller is stopped by declutching the front drive.

Diagonal motion is achieved by cycling lateral thrust and forward or rearward thrust.

At all times the thrust direction can be further controlled by the steering wheel.

On a multi engine installation diagonal motion is obtained by using one set of propellers to generate lateral thrust and the other set to simultaneously generate forward or rearward motion.




 
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