Previously there are known many forms of steering effect enhancing means or elements in connection with ships' rudders. In particular at relatively low speeds such enhanc- ed steering effect can be very useful when manoeuvring a ship.

A known form of such means are flaps or fins being hinged or pivotable in relation to the main part of the rudder, in particular being located at the trailing edge thereof. An example of such a design is to be found in Norwegian Patent 160.126.

Another form of auxiliary means are ports or nozzles in or at the rudder surface and being adapted to discharge water flows that can contribute to enhancing the steering effect of the rudder. Examples of such designs can be found in British patent 1.309.387 and Japanese patent publications Nos. 57.110.597, 57.110.598 and 57.121.998. These various designs are in part based on the supply of seawater to the rudder and its discharge openings or nozzles, through the actual rudder stock. However, there are also described designs where the seawater inlet and the transfer to the ports or openings takes place in a passive manner, i.e.

without the influence of any pump which can impart energy to the seawater flow in the form of an increase pressure or velocity.

The present invention is directed to an arrangement for such enhanced steering effect of ship rudders, with an improved efficiency and in part a simplification of the arrangement compared to the previously known designs. In this connection it is a substantial point in the basic solution according to the invention, that there is produced an additional lift as a result of extra water flow supply over substantially the whole of one rudder side or rudder surface when the rudder is deflected at an angle so as to

manoeuvre the ship to the starboard or port side. It is essential in this connection that such increased lift is generated at the rudder surface facing abaft with the rudder deflection concerned, for the desired turning movement of the ship.

Closer statements of the novel and specific features of the arrangement according to the invention, are found in the claims.

In the following description the invention will be explained more closely with reference to the drawings, whereby also various specific features and advantages will appear from the description with reference to the drawings.

An overview of the figures of drawings: Fig. 1 in elevation and partial section shows a first embodiment of the rudder arrangement according to the invention, Fig. 2 shows the arrangement of Fig. 1 from above and in partial cross section, Fig. 3 in cross section shows a distribution valve incorporated in the embodiment of Figs. 1 and 2, Fig. 4 shows a somewhat modified embodiment corresponding to Fig. 2, with the rudder in a deflected position, Fig. 5 in elevation shows a rudder arrangement according to another embodiment, Fig. 6 shows the arrangement of Fig. 5 from above and in partial cross section, Fig. 7 shows an enlarged cross sectional view along the line VII-VII in Fig. 5, Fig. 8 shows an enlarged detail of the structure at the leading edge of the rudder in Fig. 6, Fig. 9 in schematic elevation shows the leading edge of the rudder in fig. 8, and Fig. 10 shows a specific embodiment of a turning mechanism for adjusting a leading edge element of a rudder, e.g. corresponding to the embodiment of Figs. 6 and 8.

In Figs. 1, 2 and 4 the actual rudder is denoted 5 and this has an associated rudder stock 9. In Fig. 1 there are shown one part 1 and another part 2 belonging to the actual

ship structure, and in a common way serving for the journal- ling of the rudder. Fig. 1 shows a trailing turnable rudder fin 29 which in principle can be of a design known per se.

Two forms of auxiliary means for enhancing the steering effect are incorporated in the design of Figs. 1, 2 and 3.

Of primary interest in the present context is a leading edge profile or profile element 20 extending generally vertically along the whole leading edge of rudder 5. Profile element 20 is pivotable about an axis as shown at 25 in these figures of drawings, whereby Fig. 2 shows profile element 20 in a neutral, central position, whereas Fig. 4 shows the element in a deflected angular position in relation to the rest of rudder 5. As will be explained more closely below, this is related to an angular deflection of the actual rudder 5 in Fig. 4 in relation to the centerline of the ship, as indi- cated at 40 in Fig. 4.

In addition to profile element or means 20 at the lead- ing edge of rudder 5, there are also provided nozzles as shown at 30, for discharging seawater flows that can addi- tionally serve to assist in increasing the steering effect of the rudder. At this point it is to be noted that nozzle means 30 in Figs. 1 and 2 are shown to be pivotable, whereas in the modified embodiment of Fig. 4 there is a fixed nozzle 30 directing the water flow straightly backwards from rudder 5. Such fixed nozzle means are previously known from the patent specifications referred to above. However, the pivot- able nozzles 30 in Figs. 1 and 2 have a particular and advantageous combined effect together with profile element 20.

A pump (not shown) located in the ship itself, serves to furnish seawater at a pressure to rudder 5. For this purpose the rudder stock 9 has an internal passageway 9A communicating with a chamber 8 through a swivel device 3, so that seawater can be transferred from the pump in the ship to rudder 5. In the rudder there are provided ducts as shown at 11 and 12 for the further conveying of seawater to nozzle means 30 and to the region at profile element 20, respec- tively.

In order to distribute the seawater supply from above through passageway 9A in rudder stock 9, there is provided a

valve 10 that makes it possible to adjust the proportion of seawater supply to duct 11 and duct 12, respectively; a rotatable valve body 15 in valve 10 being adapted to be set angularly by means of a spindle 10A extending up through passageway 9A and possibly into the ship hull 1 concerned.

Like Fig. 1, Fig. 2 shows a setting of distribution valve 10 so that valve body 15 blocks a forward valve open- ing 14, but opens for seawater out through a valve opening 13 to duct 11 for water supply to nozzle means 30. In Fig. 2 this is shown at various angular positions, of which two are indicated 30' and 30".

Fig. 3 shows another angular setting, i.e. with valve body 15 in front of opening 13 so that this opening is blocked. Accordingly seawater will exit through opening 14 and therefrom (see Figs. 2 and 4) more or less directly out into a cavity or a portion of a distribution duct 12 being formed in the space between the leading edge of the actual rudder 5 and the inside of profile element 20. In this intermediate space therefor in the neutral position of the profile element as shown in fig. 2, there will exist two laterally directed and slot-shaped distribution ducts 12A and 12B that communicate with the common cavity 12 centrally in the rudder and preferably closely associated with valve 10.

Finally Fig. 4 shows a position of valve body 15 making possible outflow of seawater through both openings 13 and 14, so that nozzle means 30 as well as profile element 20 with associated active distribution duct 12B, contribute to an enhanced steering effect.

Of essential importance in a deflected position as shown in Fig. 4, is the extra seawater flow that is indicat- ed at 12X and coming just from distribution duct 12B in the space between the leading edge of rudder 5 and profile ele- ment 20. This additional flow 12X gives a strongly increased lift at the adjacent rudder side, that substantially as a whole contributes to this desired effect. On the other hand at the opposite side distribution duct 12A is essentially blocked since the end portion of lateral part 20A of profile element 20 engages the adjacent surface 5A of rudder 5.

Thus, it is seen that distribution ducts 12A and 12B at

either side of the rudder, are adjustable in consequence of the angular adjustability of profile element 20.

As shown quite schematically in Fig. 2, profile element 20 can be adjusted angularly by means of a turning mechanism comprising e.g. a hydraulic cylinder 21 in association with rudder stock 9, a manoeuvre rod 22 and a turning lever 23 attached to the profile element, whereby the outer end of rod 22 preferably is articulated to arm 23. Rod 22 and arm 23 are also shown in Fig. 1. Moreover, Fig. 1 shows another rod 24 at the upper edge of rudder 5, for angular adjustment of rudder fin 29. Accordingly the angular movement of pro- file element 20 and fin 29 can be coordinated.

In this connection it is an advantageous embodiment to build nozzle means 30 and rudder fin 29 together, so that the nozzle will have an angular movement corresponding to the angular adjustment of fin 29. Fig. 2 illustrates various possible angular positions in that respect, whereby arrows 30 and 30" as already mentioned above, represent two angu- lar positions of nozzle means 30 and thereby rudder fin 29.

In Fig. 2 there are also shown two nozzle positions later- ally at right angles and besides a neutral position with nozzles (30A-B) straight rearwards. It is obvious that the coordination of the profile element's angular position and the nozzle direction is decisive for a combined optimal effect of these auxiliary means.

Fig. 1 also shows a particular design of nozzle means 30, where the nozzle is subdivided into an upper nozzle outlet 30A and a lower nozzle outlet 30B, these converging here towards one another and with an intermediate splitting element 30C receiving the water flow from duct 11. At the junction from this at the trailing edge of the actual rudder 5, to fin 29 with nozzle means 30, there must apparently be provided some form of swivel connection. Such swivels are known in various embodiments and will not be more closely described in this context.

The manoeuvring of a ship being provided with a rudder arrangement as described here, in the usual way will be controlled from operating means or apparatus at the bridge of the ship, whereby control and steering systems based on electronics and/or hydraulics n a known manner, can be

utilized in a complete system. In this way there can be provided for steering or regulation of the required pump (e.g. ballast pump), distribution valve, angular setting of profile element and possibly flap or fin at the trailing edge of the rudder concerned.

The steering can be arranged so that e.g. upon a com- mand from the bridge for a starboard turn of the ship, the profile element will remain at the same angle until the rudder deflection has attained e.g. 10°, which can correspond to a situation where the-distribution duct at one side will be blocked and the whole water flow be directed to the port side of the rudder. Then there will be generated a reduced pressure at the port side of the rudder compared to the starboard side thereof and the rudder will be pushed in the port direction. Thus, the ship will turn starboard. Upon further angular movement of the rudder in the same direc- tion, the profile element will maintain the same setting in relation to the rudder and will follow the turning movement thereof.

According to the embodiment of Figs. 1 and 2 a seawater flow can at the same time be led rearwards through the duct in the rudder, whereby the splitting element 30C in nozzle means 30 (Fig. 1) can also have a venturi effect that further increases the thruster force exerted by nozzle means 30. The moveability of the output nozzles at the trailing edge of the rudder flap has particular interest at small rudder deflections, in particular thereby that the nozzle angle can be set at up to 900 in relation to the longitudinal axis of the rudder. Together with the rudder flap or fin the nozzles can be brought to have twice as large an angular deflection as the rudder itself.

In the second and in many respects preferred embodiment of the invention, as illustrated in Fig. 5 and the subse- quent figures of drawings, several of the same structural elements are incorporated as described above with reference to Figs. 1-4. Thus, Fig. 5 shows parts 41 and 42 of the actual ship structure, that as such is also indicated at 44.

At the trailing edge of rudder 45 there is mounted a pivot- able rudder fin 59 and the rudder stock is shown at 49. At the leading edge of the rudder there is provided a profile

element 60 that is preferably angularly adjustable, as is profile element 20 in the embodiment discussed above. A nozzle 70 is shown relatively schematically as an integrated part of the rudder fin 59 in Fig. 5 and likewise in Fig. 6.

In this embodiment there is not shown any distribution valve corresponding to valve 10 in Figs. 1-4, but on the other hand there are shown at 63 and 64 two supply pipes for water from the ship's pump or pumps, whereby the distri- bution of water between supplies 63 and 64 takes place by suitable means in the ship itself. The two water flows are then led further downwards in two separate passageways in the form of annular spaces outside and surrounding the rudder stock 49. As will also appear from the cross sectio- nal illustrations in Figs. 6 and 7 the annular passageway around the rudder stock 49 is subdivided into two passages 53 and 54 by means of axially extending partitions 49A and 49B. Advantageously these can be attached to or formed as integrated parts of the actual rudder stock 49. At their radially outer edges partitions 49A and 49B engage the inside of the surrounding cylindrical housing 50 and during turning movements of rudder 45 there will be maintained equally large flow cross sections in the two passages 53 and 54. As shown somewhat schematically in Fig. 5 there is in- corporated a swivel device 49S between ship part 41 and rudder 45, so that flow passages 53 and 54 can extend with- out hindrance downwards within the rudder at turning move- ments thereof in relation to the ship. Fig. 7 in this con- nection illustrates possible angular deflections of the rudder, i.e. with 450 to either side in relation to the central position. Openings 51 and 52 out through housing 45 lead to respective ducts, being also denoted 51 and 52, respectively, in Figs. 5 and 6. The preferred form of water supply being here explained with reference to Figs. 5, 6 and 7, among other things involves the advantage that it is more simple than the design of Figs. 1-4, since the distribution valve described therein, is not required.

Distribution duct 51 carry seawater to nozzle means 70 through a swivel 59S at the junction or hinge region between the main part 45 of the rudder and the rudder fin 59. Be- sides in Fig. 5 there is shown a vertical distribution duct

57C branched off from duct 51 and provided with slots or nozzles 57A and 57B at either side of the rudder, for dis- charging partial flows of seawater to one or the other rudder side 45A or 45B. At the top of distribution duct 57C for this purpose there can be provided a valve (not shown) to serve for controlling these partial flows to the desired rudder side of surface. An additional form of such partial flows of water can also be directed out from nozzles 58A and 58B as shown in Fig. 6. The outlet opening from these nozzles or slots 58A and 58B can be located in a space bet- ween the leading edge of rudder fin 59 and the trailing edge of the actual rudder 45.

The additional water flows at the trailing portions of rudder 45 as just referred to, are normally considered to be of relatively subordinate significance compared to an addi- tional flow as indicated with arrow 52X in connection with profile element 60 at the leading edge of the rudder. In contrast to profile element 20 in Figs. 1-4, the interior of profile element 60 in the first place is provided with a vertical distribution duct 62 and in association therewith laterally directed ducts or slots 52A and 52B at either side. The water flow 52X being indicated in Fig. 6 thus can be obtained by outflow of seawater through distribution duct 52B. At the top of profile element 60 as schematically illu- strated in Fig. 5, there is provided a swivel 62S for inter- connecting ducts 52 and 62 with a possibility of a certain angular rotation of profile element 60 in relation to rudder 45 itself.

Figs. 8 and 9 illustrate somewhat more in detail the structure for adjusting or controlling the water outflow to one or the other side from profile element 60. In Fig. 8 this is shown in an angular position where duct 52A is blocked, whereas duct 52B is active for discharging the additional flow 52X referred to above, along the adjacent surface of rudder 45. A control valve is provided in the form of tube elements 62 and 63 surrounding the vertical pivot axis for element 60. The inner tube element 62, surrounding the above vertical distribution duct, has two longitudinal, vertical slot openings 62A and 62B that can have a mutual angular displacement of about 900. The exterior

tube element 63 has corresponding longitudinal slot openings 63A and 63B with a somewhat larger mutual angular displace- ment than between openings 62A and 62B. Tube 63 is securely anchored within profile element 60 and will rotate together with that element. Tube 62 however, is stationary in re- lation to rudder 45. Accordingly an angular movement of profile element 60 will have influence on the water outflow from the duct within tube 62 out through the respective more or less coinciding slots and thereby to one or the other of outflow ducts 52A and 52B.

In accordance with the explanation above the inner tube element 52 can be connected to a projecting upper part of rudder 45, as will be seen from Fig. 5, and can rest on a swivel at the lower end. The outer tube element 63 can be considered to constitute a rudder stock for profile element 60 and in addition to be incorporated as a component in the control valve described, with bearing points at the upper and the lower ends respectively, where a swivel can be provided.

Whereas Figs. 5-9 have not comprised any turning mechanism for the angular movement of profile element 60, Fig. 10 in a simplified and schematic manner illustrates a design for that purpose. The turning mechanism of Fig. 10 is rotationally driven by drive means generally denoted 61 associated with the actual rudder stock, such as by a thread or worm gear transmission to two manoeuvre rods 66A and 66B which e.g. in the form of telescopical extension and arti- culation to profile element 60 at their outer ends, can provide for the desired angular setting of the profile ele- ment about the axis or duct 62.

The embodiments described above make possible rela- tively simple designs of the rudder parts, in particular when considered in relation to the advanced functions being obtained. The embodiments of Figs. 5-9 also lead to a reduc- ed flow resistance for the seawater supply to the various auxiliary means serving to enhance the steering effect of the rudder. It will be possible to manufacture the profile element and the rear fin of the rudder as separate units and likewise the swivel-sleeve arrangement around the rudder stock in Figs. 5, 6 and 7 can be assembled as a separate

unit for mounting around the rudder stock through the adjacent hull part. Such embodiments can have much com- mercial significance also because it can be possible to convert conventional rudders to more sophisticated rudders with an enhanced steering effect, as provided for by this invention.

It will be realized that the embodiments here described with reference to the drawings, are shown and explained in part in a relatively simplified and schematic form, for the purpose of primarily to explain the principles according to the invention. At many points in the designs described it will be possible to make modifications and add structural elements while maintaining the basic solutions being pre- sented by the invention.