GB2317597A

GB2317597A - Bladed marine propulsion device

Info

Publication number: GB2317597A
Application number: GB9620084A
Authority: GB
Inventors: Oswald Burgess
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-09-26
Filing date: 1996-09-26
Publication date: 1998-04-01
Also published as: GB9620084D0

Abstract

A propulsive device for marine use is provided which comprises a rotatably mounted plate 2, from which blades 6,8,10,12 extend. The blades are rotatable about their own axis, and, in use, rotate around their axis at half the rate of rotation of the plate 2. This produces a thrust to propel the vessel. The device may be turned to vary the direction of thrust or such thrust control may be achieved by varying the pitch of the blades. The blades may be rotated by electric, pneumatic or hydraulic actuators, or by gearing (figures 2-4).

Description

A PROPULSIVE DEVICE The present invention relates to a propulsive device and to a method of providing propulsion.

It is desirable to control the direction of thrust produced by a propulsive device, such as a propeller, on a vessel. A conventionally mounted propeller is provided at the stern of a vessel forward of a rudder. Rotation of the propeller produces a stream of water which is deflected by the rudder blade in order to manoeuvre the vessel. Such a arrangement provides reasonable steering control when the vessel is moving forward, but provides very little steerage when the vessel is moving astern.

The Voith-Schneider propeller provides more manoeuvrability than a conventional propeller. The Voith-Schneider propeller comprises a horizontally mounted rotating disc which has vertical blades depending therefrom. The blades are pivotally mounted and are arranged such that, at rest, the faces of the blades face radially inwardly and outwardly.

In order to provide thrust, the pitch of opposing blades is varied in opposite senses. The blades can only undergo a limited amount of rotation either side of the rest direction, and consequently can be regarded as undergoing a nodding motion about their own axes as the propeller rotates.

According to a first aspect of the present invention, there is provided a propulsive device, comprising at least one blade, the or each blade being rotatable about a respective axis, and further arranged to perform circular motion about a common axis, in which each blade undergoes a rotation of substantially 90" as it moves between first and second positions which are on diametrically opposing sides of the common axis.

It is thus possible to provide a propulsive device in which the direction of thrust produced by the device can be easily controlled.

Preferably, the common axis is a drive axis. Advantageously, a plurality of blades extend perpendicularly to a carrier plate and are uniformly positioned around the axis of rotation of the carrier plate. Each blade is rotatable around its own axis.

The blades need not be flat plates, but may be profiled, for example, like an aircraft wing. For the purposes of this specification, the blade is to be considered as "in line" with a given direction when the plane of the blade is parallel to the direction, and being perpendicular to the direction when the plane of the blade is perpendicular to the direction.

Each blade may be driven by an actuator so as to control its angle with respect to its instantaneous direction of motion.

The actuators may be electrically, pneumatically or hydraulically driven. Rotary actuators may be directly connected to or geared to the blades, whereas linear actuators can be coupled to the blades via associated cranks.

Preferably, the blades are in geared engagement with the driveshaft or a carrier plate, such that the blades rotate about their own axes as the carrier plate rotates about its own axis.

A 2:1 reduction gear is used such that the blades rotate at half the rate of the carrier plate. By suitable selection of the initial orientations of the blades, it is possible to provide a thrust along a first direction. In order to vary the direction of thrust, the propulsive device may effectively be rotated around the axis of the drive-shaft. Alternatively, further directional control of the blades may be superimposed on their rotary motion so as to control the direction of thrust. Thus, in use, as the carrier plate rotates, blades moving along the direction of thrust are orientated so as to be perpendicular to the direction of thrust, whereas blades moving in a second direction opposed to the direction of thrust, are orientated so as to be in line with the second direction. Blades at intermediate positions may be angled so as to generate thrust forces along the thrust direction.

According to a second aspect of the present invention, there is provided a propulsive device comprising at least one blade mounted for rotation about its own axis, and further mounted on a carrier which moves the blade around a loop, the angle of the blade being controlled such that as it moves along a first direction, the blade is perpendicular to the first direction, and as it moves along a second direction opposing the first direction, the blade is in line with the first direction.

It is thus possible to provide a propulsive unit in which the direction of thrust is continuously variable over a range of 3600. The magnitude of thrust is controlled by varying the rate of rotation of the carrier plate.

According to a third aspect of the present invention, there is provided a method of generating thrust using at least one blade rotatable about a respective axis and further arranged to perform circular motion about a common axis, in which the angles of the blades are controlled such that each blade undergoes a rotation of substantially 900 as it moves between first and second positions which are on diametrically opposing sides of the common axis.

In a ship's propeller constituting an embodiment of the present invention, the carrier plate is horizontally mounted with the propeller blades extending vertically therefrom.

The present invention will further be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a plan view schematically illustrating the blade orientations of a four-blade propeller constituting an embodiment of the present invention; Figure 2 is a cross-section through a propeller constituting an embodiment of the present invention; Figure 3 is a cross-section through a horizontal plane including the line A-A shown in Figure 2; and Figure 4 schematically illustrates a further embodiment of the present invention.

Figure 1 is schematic view of a propeller constituting an embodiment of the present invention. The propeller comprises a circular carrier plate 2 which is driven to rotate about its axis of symmetry 4. The plate 2 carries four blades 6,8,10 and 12. The blades are rotatably attached to the carrier plate 2, and are driven to rotate about their respective axes at half the rate of rotation of the carrier plate 2. The propeller shown in Figure 1 is arranged to push a surrounding fluid along the direction of the arrow T.

If the propeller is mounted on a vessel, this will cause the vessel to be urged to move along the direction indicated by arrow M.

The carrier plate 2 is shown as undergoing anti-clockwise rotation. Thus, each blade moves cyclically between the positions I,J,K,L and back to I. Blade 6 at position I is orientated such that it is in line with the instantaneous direction of its motion, i.e. the blade is parallel to the direction M. As the blade 6 moves from position I to position J, the blade is rotated in an anti-clockwise direction in order to become inclined at an angle of approximately 45" with respect to the direction M. The instantaneous motion of the blade at position J as shown in Figure 1 is from right to left. This motion causes some of the surrounding fluid to be pushed along the direction indicated by the arrow T.

As the blade moves between the position J and the position K, it rotates anti-clockwise about its own axis by a further 45".

The blade at position K is perpendicular to the direction of arrow T. The instantaneous direction of motion of the blade at the position K is along the direction of arrow T, and consequently the blade sweeps the surrounding fluid along the direction indicated by arrow T. As a blade moves from position K to position L, it rotates by a further 450 in the anti-clockwise sense. The instantaneous motion of the blade in the arrangement illustrated in Figure 1 is from left to right. Thus, motion of the blade also sweeps fluid along the direction indicated by arrow T. As the blade moves from position L to position I, it rotates by a further 450 bringing it back the start position of the cycle. The instantaneous direction of motion of the blade at position I is along the direction of arrow M. However, the blade presents a minimum cross-section along the direction of motion at this position so as to minimise drag.

In order to vary the direction of the thrust T, the propeller can be turned around the axis 4, thereby effectively moving the positions I,J,K and L with respect to a vessel fitted with the propeller. Alternatively, the pitch of each of the blades can be further varied in addition to various positions illustrated in Figure 1, in order to achieve control of the direction of thrust.

Figure 2 shows a cross-section through a propeller device constituting an embodiment of the present invention. For simplicity, only blades 6 and 10 are illustrated. The blade 6 is carried on a shaft 14 which is keyed to a gear cog 26.

The blade 10 is fixed to a shaft 16 which is keyed to a gear cog 30. The blades 8 and 12 are similarly held on shafts which are keyed to gear cogs 28 and 32, respectively. Each of the gear cogs 26,28,30 and 32 are in geared engagement with a central gear cog 34 via respective idler gears 36,38,40 and 42.

The gear cog 34 is in engagement with a direction control shaft 44.

The carrier plate comprises two opposing plates having cooperating holes for receiving axles for the gear cogs 26 to 32, and 34 to 40. An upper portion of the carrier plate 2A is fixed to the lower position of the carrier plate 2 so as to hold the gear cogs between the plates and to prevent relative movement between the upper portion and lower portion of the carrier plate.

The upper portion 2A of the carrier plate 2, is fixed to a bevelled drive-gear 46. A further bevelled gear 48 engages with the gear 46 and is driven from a drive-shaft 50.

In use, the central shaft 34 is held against rotation and the drive shaft 50 is rotated, thereby causing the carrier plate to rotate about its central axis. The rotation of the carrier plate causes the blades to undergo circular motion.

The gears 26 to 32 are obliged to roll around the central gear 34, and thereby cause the propeller blades to rotate about their own axis as the carrier plate rotates around the central axis. The gears 26 to 32 form a 2:1 reduction gear with the central cog 34 (via the idler gears 36-42), thereby causing the propeller blades to rotate at half the rate of rotation of the carrier plate.

The central shaft 44 can be rotated to superimpose an angular offset upon the positions of the blades as shown in Figure 1.

This allows the direction of thrust to be varied, thereby giving steering control over the propeller. The shaft 44 may be controlled via a worm gear arrangement, indicated generally as 52. The propeller unit is enclosed within a housing 54 which can be formed with watertight seals around the driveshaft 50 and the steering control shaft. Furthermore, the lower portion of the carrier blade 2 may be in sealed engagement with the housing 54 in order to prevent the ingress of water into the interior of the housing.

Figure 4 schematically illustrates an alternative embodiment of the present invention. The blades are held on shafts in driving engagement with gears 26 to 32 as described with reference to Figures 2 and 3. However, the gears 26 to 32 are in direct engagement with a central gear 60 which is attached to a drive-shaft 62. The shaft 62 is also drivingly connected with a first gear 64 of a differential gear arrangement, indicated generally as 66. An opposing gear 68 of the differential gear arrangement is connected to a steering control shaft 70. The intermediate gears 72 of the differential gear arrangement are supported on a housing 74 which is secured to the plate 2A. In use, the direction control shaft 70 is held fixed, or only rotated when it is desired to change the direction of thrust. Thus, rotation of the drive-shaft 62 causes the intermediate gears to roll around the gear 68, and this motion is transmitted via the housing 74 to the carrier plate 2. Furthermore, the geared engagement between the gears 26 to 32, and the central gear 60, is selected to cause the blades to rotate around their respective axes at half the rate of rotation of the carrier plate around the drive-shaft 62. Rotational motion of the steering control shaft 70, superimposes an angular offset on to the circular motion of the blades, thereby allowing directional control to be achieved.

In the above described embodiments, the rotation of the blades has been mechanically synchronised to the rotation of the carrier plate. However, each of the blades could be individually driven under the control of an actuator which may itself be controlled by a data processor, thereby allowing the magnitude of the drive to be controlled without changing the rate of rotation of the carrier plate, for example, by bringing the blades more in line with the instantaneous direction of rotation. Additionally, the pitch of the blades could be controlled to induce a turning moment about the axis of rotation of the carrier plate. It is thus possible to provide a versatile drive arrangement which may be used to control the direction of a jet of fluid, and thereby to steer a vessel.

The centre of effort of the propeller is effectively offset from the axis of rotation of the carrier plate. In order to overcome this, the propeller may be slightly offset from the centre line of a vessel, or counter-rotating pairs of propellers may be provided.

Claims

ClAIMS

1. A propulsive device, comprising at least one blade, the or each blade being rotatable about a respective axis, and further arranged to perform circular motion about a common axis, each blade undergoing a rotation of substantially 90" as it moves between first and second positions which are on diametrically opposed sides of the common axis.

2. A propulsive device as claimed in claim 1, further comprising a carrier plate, and in which a plurality of blades extend perpendicularly to the carrier plate and are uniformly positioned around the axis of rotation of the carrier plate.

3. A propulsive device as claimed in any one of the preceding claims, in which the common axis is a drive axis.

4. A propulsive device as claimed in any one of the preceding claims, in which the blades are planar or are profiled to have a cross section like an aerofoil.

5. A propulsive device as claimed in any one of the preceding claims, in which the or each blade is rotatable around its own axis.

6. A propulsive device as claimed in any one of the preceding claims, in which each blade is driven by an actuator.

7. A propulsive device as claimed in claim 6, wherein the actuators are electric, pneumatic or hydraulic actuators.

8. A propulsive device as claimed in any one of claims 1 to 5, in which the blades are in geared engagement with a drive shaft or a carrier plate such that the blades rotate around their own axis as the drive shaft or carrier plate rotates about its own axis.

9. A propulsive device as claimed in claim 8, in which a 2:1 reduction gear is used such that the blades, rotate around their respective axes at half the rate of rotation of the carrier plate.

10. A propulsive device as claimed in claim 8 or 9, in which the propulsive device is rotated about the common axis in order to vary the direction of thrust.

11. A propulsive device as claimed in claim 8 or 9, in which further rotary motion may be superimposed on the motion of the blades in order to vary the direction of thrust.

12. A propulsive device comprising at least one blade mounted for rotation about its own axis and further mounted on a carrier which moves the blade around a loop, the angle of the blade being controlled such that as it moves along a first direction the blade is perpendicular to the first direction, and as it moves along a second direction opposing the first direction, the blade is in line with the first direction.

13. A propulsive device for use on a marine vessel, comprising a propulsive device as claimed in any one of the preceding claims.

14. A propulsive device as claimed in any one of the preceding claims, in which, in use, a carrier plate thereof is mounted horizontally and the blades extend vertically therefrom.

15. A marine vessel having a propulsive device as claimed in any one of the preceding claims.

16. A method on generating thrust using at least one blade rotatable about a respective axis and further arranged to perform circular motion about a common axis, in which the angle of the or each blade is controlled such that it undergoes a rotation of substantially 900 as it moves between first and second positions which are on diametrically opposed sides of the common axis.

17. A propulsive device substantially as hereinbefore described with reference to figure 1 of the accompany drawings.

18. A propulsive device substantially as hereinbefore described with reference to figures 2 and 3 of the accompany drawings.

19. A propulsive device substantially as hereinbefore described with reference to figure 4 of the accompany drawings.