WO1998033703A1

WO1998033703A1 - Rudder

Info

Publication number: WO1998033703A1
Application number: PCT/NO1998/000033
Authority: WO
Inventors: Rolf Kvamsdal
Original assignee: Kvaerner Asa
Priority date: 1997-01-30
Filing date: 1998-01-30
Publication date: 1998-08-06
Also published as: AU5887098A; NO303974B1; NO970413L; NO970413D0; EP0956235A1

Abstract

A device for mounting a rudder (22) which is axially movably mounted in a drum (6). The drum (6) in turn is rotatably mounted in a hull (4) of a vessel, an end wall (16) of the drum (6) being substantially aligned with a section of a skin (18) of the hull (4). The rudder (22) can be moved between a first position, wherein it is substantially withdrawn into the drum (6), and a second position, wherein it extends substantially outside the drum (6) and away from the hull (4) and projecting in relation to the end wall (16). In the drum (6) there is provided a carriage device (60, 62, 72, 74) and a guide device (86, 90) which is securely connected to the drum (6) and axially extending in relation to the rudder (22) for translatorily rectilinear guidance of the carriage device (60, 62, 72, 74). The carriage device (60, 62, 72, 74) has at least one rod (60, 62) which is axially movable in a hole (40, 42) in the rudder (22), the rod (60, 62) and the hole (40, 42) having constantly mutually overlapping sections, thus enabling bending moments which are exerted against the rudder (22) to be transferred to the drum (6) via the carriage device (60, 62, 72, 74).

Description

Rudder

The invention concerns a device for mounting a rudder in a drum which is mounted rotatably about its longitudinal axis in a hull of a vessel, wherein the rudder is movable along its and substantially also the drum's longitudinal axis, an end wall of the drum is substantially aligned with a section of a skin of the hull and the rudder can be moved between a first position, wherein it is substantially withdrawn into the drum, and a second position, wherein it extends substantially outside the drum and away from the hull and projecting in relation to the end wall. In WO 93/24363 there is disclosed a rudder which is mounted in a drum in this manner. In order to prevent penetration of water into the hull, the drum may be closed at its inner end, i.e. the end which faces into the hull and sealing devices may be provided between the drum and the hull. In the same way as for spade rudders in other respects, the fluid which flows around the rudder during running of the vessel gives rise to substantially transverse forces and bending moments which have to be transferred to the hull via the drum. The rudder must be designed to be capable of also withstanding other stresses.

In the known rudder mounting device the rudder is disposed slidably in the drum, with areas of the drum and the rudder constantly overlapping one another. The transfer of forces as well as bending moments from the rudder to the drum is thereby ensured. In order to ensure the absorption of the maximum bending moments which occur when the rudder is pushed out of the drum to its maximum projecting position, however, these overlapping areas have to be relatively long. The section of the rudder which then projects into the drum cannot therefore be employed for steering the vessel, and in order to enable the rudder to be withdrawn completely into the drum it must have a length which at least corresponds to the length of this section and the length of the projecting section. The drum therefore projects a considerable distance into the hull, requiring a great deal of space.

The object of the invention is to provide a device of the type mentioned in the introduction, which is not encumbered with this drawback.

The characteristic of the rudder device according to the invention is presented by the characteristic features stated in the claims. The invention will now be described in more detail with reference to the drawing which schematically illustrates embodiments of a rudder device accordin *ag to the invention.

Fig. 1 shows a section through a drum with a thereto connected rudder according to a first embodiment of the device according to the invention.

Fig. 2 shows a cross section along line II-II in fig. 1.

Fig. 3 shows a longitudinal section through the drum and the rudder along line III-III in fig. 1.

Fig. 4 shows a section like that in fig. 1 through a rudder assembly comprising two telescopic rudder sections according to a second embodiment of the device according to the invention.

As illustrated in figures 1-3, in a circular cylindrical cavity 2 in a vessel hull 4 there is provided a circular cylindrical drum 6 which can rotate in the cavity 2 in bearings 8, 10. Between the hull 4 and the drum 6 there is provided a sealing device 12. The drum has an end wall 14 which closes the drum 4 at its inner end, i.e. the end which projects into the hull, and an outer end wall 16 which is substantially aligned with a skin 18 of the hull 4.

In the outer end wall 16 there is provided a through-going opening 20 through which there extends a cylindrical rudder 22 which can slide in its longitudinal direction through the opening 20. The expression axial direction will hereinafter be understood to mean this longitudinal direction and the expression transverse direction will be understood to mean directions across the axial direction unless otherwise specified. A first mounting device 24 which is composed of a section of the outer end wall 16 at the opening 20 is arranged to support the rudder 22 laterally, i.e. to absorb forces which are exerted by the rudder against the end wall 16 in the rudder's transverse direction. The inner end wall 14 may be connected to devices (not shown) whereby the drum can be rotated for steering the vessel.

In the rudder 22 there is provided an axial blind bore 26 which is open at the rudder's inner end. At this end the bore 26 has a narrowed section or nut section 28 which has an inner thread in which an axially extending screw 30 is screwed. At its inner end the screw 30 is mounted in the inner end wall 14 of the drum 6, thus enabling the screw 30 to rotate freely about its longitudinal axis. Near its inner end a first chain wheel 32 is rotationally rigidly connected with the screw 30. To the drum's inner wall there is attached a motor 34, which is preferably an electric motor. To the motor's rotor there is attached a second chain wheel 36. Around the chain wheels 32. 36 there extends a chain 38. The motor may be supplied with electricity via wires (not shown) which extend sealingly through the drum wall without preventing rotation of the drum 6. Thus, when the motor is running the screw 30 can be rotated via the chain wheels 32, 36 and the chain 38 for axial movement of the rudder 22. In the rudder 22 there are also provided two additional blind bores 40, 42 (see fig. 3) which extend on each side of the bore 26 for the screw 30, and which are open at the rudder's inner end. In the inner bore section of each bore 40, 42 a screw 44, 46 is inserted with a through-going, axial bore 48, 50, whose outer end forms an outwardly facing shoulder 52, 54. In the inner end of each screw 44, 46 and in the inner end section of the rudder 22 there is provided a recess 56, 58.

In each bore 40, 42 there extends a rod 60, 62 with a rod section 64, 66, the outer end of which is connected to a head 68, 70. The rod section 64. 66 extends slidably in the axial bore 48, 50 of the respective screws 44, 46. The rods' heads 68, 70 are arranged to abut against the shoulders 52, 54 for carrying the rods 60, 62 when the rudder 22 is moved out of the drum 6.

At their inner ends each of the rods 60, 62 is securely attached to a yoke 72, 74 (see fig. 2) which extends across an axial symmetry plane P for the rudder 22. Each yoke and associated rods constitutes a carriage device. The end sections of each yoke 72, 74 has radial bearings 76, 78, 80, 82 which are arranged to be slidably moved on respective axially extending guide rods 84, 86, 88, 90, the ends of which are attached to the drum's end walls 14, 16. The guide rods constitute a guide device for the carriage device. In order to ensure that the rods 60, 62 are not moved too far against the drum's outer end wall 14, e.g. by their own weight, on the guide rods 84, 86, 88, 90 there may be provided stoppers 96, 98 against which the yokes 72, 74 can come into abutment. As illustrated by a broken line in fig. 2, additional yoke sections may be provided which securely connect the yokes 72, 74 to each other. The mode of operation of the device is as follows, assuming that the fact that the rudder 22 initially has been pushed into the drum 6. In this position of the rudder the recesses 56, 58 receive adjacent sections of the yokes, thus enabling the rudder to be pushed the maximum distance up into the drum. When electricity is supplied to the motor 34 the screw 30 is rotated in one way, whereby the rudder is pushed out of the drum. In the event that a binding between the bearings 76 - 82 and the guide rods 84 - 90 or substantial friction between these bearings and rods should cause the yoke assemblies to hereby fail to be moved outwards together with the rudder, the yoke assemblies are forcibly moved outwards by the heads 68, 70 coming into abutment against the shoulders 52, 54. Before the rudder has reached its maximum projected position, the carriage device is prevented from continuing to be carried outwards by means of the stoppers 92 - 98.

If a transverse force is exerted against the rudder in the rudder's projected position in the direction perpendicular to an axially extending rudder median plane P, with the result that a bending moment is exerted at the inner section of the rudder, the forces of an associated force couple are transferred to the drum via the first mounting device 24 and to the yoke assembly via the mutually overlapping sections of the rods' rod sections 64, 66 and the respective screws 44, 46.

When the motor 34 and thereby the screw 30 are rotated the other way, the rudder is moved inwards in the drum 6. When the yokes abut against the inner end of the rudder 22, the carriage devices are carried upwards or inwards in the drum. In fig. 4 there is illustrated a drum 100 which is arranged for rotation in a vessel hull 102. In a first cavity 104 which is provided in the drum 100 and which is open away from the interior of the hull, and leads into the vessel's skin, there is provided a first rudder section 106 which is arranged to slide in its longitudinal direction, i.e. axially in the cavity 104. The direction inwards into the hull will hereinafter be described as upwards. In a second, axially through-going cavity 108 in the first rudder section 106 there is telescopically received a second rudder section 1 10 which is arranged to slide axially in the same direction as the first rudder section 106. In the second rudder section there is provided a blind hole 1 12 which is open at the top. At the opening of the second rudder section 1 10 there is arranged a nut section 1 14 into which there is screwed a screw 116, whose lower end section may extend into the blind hole 1 12, and whose upper end section is connected to the rotor of a motor 1 18, e.g. an electric motor, which is attached in the second cavity 108 and to the upper end section of the first rudder section 106. The second rudder section can thus be moved in or out of the first rudder section by rotation of the motor's rotor one way or the other. By means of devices (not shown) it is ensured that the length of the area in which the rudder sections overlap each other is not smaller than a certain value, in order to ensure that bending moments and forces which are exerted against the second rudder section 1 10 can be transferred to the drum via the first rudder section 106. A rudder comprising telescopic rudder sections similar to that described here may be employed with rudders of the known type or with rudders of the type which is illustrated in figures 1 - 3.

Claims

PATENT CLAIMS

1. A device for mounting a rudder blade in a drum, which is mounted rotatably about its longitudinal axis in a hull of a vessel, and whose longitudinal axis extends parallel to a longitudinal axis of the rudder blade and across an adjacent section of a skin of the hull, and one end of which is aligned with this hull section, where the rudder blade (22) is movable along its longitudinal axis and adjustable in operating positions between a first position, wherein it is withdrawn into the drum (6), and a second position, wherein it extends substantially outside the drum (6) and away from the hull (4) and projecting in relation to the end of the drum, and there is provided a carriage device (60, 62, 72, 74) for transfer of forces exerted laterally against the rudder blade (22) to a guide device (84, 86, 88, 90) for the carriage device (60, 62, 72, 74), which guide device is immovable along the rudder blade axis in relation to the hull and which the carriage device (60, 62, 72, 74) can slide along, and via which the forces can be transferred to the hull, characterized in that the guide device (84, 86, 88, 90) is arranged in and fixedly connected to the drum (6), and that the carriage device (60, 62, 72, 74) has at least one section (64, 66) which extends slidably in an associated axially extending hole (48, 50) of the rudder blade (22), the section (64, 66) and the hole (48, 50) overlapping each other over an axial distance whose length has been chosen to ensure absorption of the forces.

2. A device according to claim 1, characterized in that the section (64, 66) is a projecting section of a rod (60, 62) which is fixedly connected to a yoke of the carriage device, which yoke is slidably connected to the guide device and laterally supported against the hull via the section of the drum which is located near the hull skin.

3. A device according to claim 2, characterized in that at its free end the rod section (64, 66) has a stopper (68, 70) which is arranged to abut against a shoulder (52, 54) at the hole (48, 50) for restriction of the reciprocal movement of the rudder blade (22) and the carriage device (60, 62, 72, 74) away from each other and thereby ensuring the axial overlapping of the carriage device's section (64, 66) and the hole (48, 50).

4. A device according to one of the preceding claims, characterized in that the rudder (22) comprises a first, outer and a second, inner rudder section ( 106 and 1 10) which are telescopically movable in relation to each other by means of an activator device.

5. A rudder device according to claim 4, characterized in that the activator device comprises a motor (1 18) which is fixedly connected to the first, outer rudder section ( 106), and which is arranged to rotate a screw ( 1 16) which is inserted in a nut section ( 1 14) of the second, inner rudder section ( 1 10).

6. A device according to claim 5, characterized in that the motor ( 1 18) is an electric motor.