The invention relates to a rudder for ships.
Rudders of ships with a propeller drive these days often have a so-called Costa bulb (a stream-lined body of revolution integral with a rudder and directly in line with the propeller). The purpose of the so-called Costa bulb or propulsion bulb is that a bulge, which is designed to be bulb-shaped or zeppelin-shaped and constitutes a flow body, is configured as an extension of the propulsion axis in the region of the rudder blade. The purpose of this flow body is that the overall profile of the hub is extended to the point where there is only minimal turbulence of the wake.
This type of Costa bulb is known for example from patents DE 198 44 353 A1, DE 84 23 818 U and DE 82 24 238 U.
The effect of the Costa bulb is a result of its bead-shaped configuration, by which it is distinguished from the rudder or respectively rudder blade, resulting in favorable flow.
The Costa bulb protrudes laterally relative to the rudder blade and in the event of an impact, a blow or pressure the Costa Bulb is in the immediate impact zone. This means that the Costa Bulb would be damaged before the actual rudder blade would be damaged.
However, in the event of an impact, a blow or pressure on the prior art Costa bulb the rudder blade would also be affected, because the Costa bulb transfers the force acting on it to the rudder blade and there is thus the added danger of damage to the rudder blade.
The purpose of the invention is to provide a rudder blade for ships, which in spite of favorable flow due to external effects, is less susceptible to damage or destruction due to the effect of an impact, a blow or pressure and that the flow body is independently destroyed or self-released in the event of such pressure, blow or impact.
At the same time it is advantageous if the flow body divides the rudder blade, viewed in the vertical direction, into two areas (A, B), whereby both areas are designed identically or not identically in profile. In this respect it is effective if the longitudinal middle lines of the areas of the rudder blade are not superposed with the middle line of the flow body and respectively form an angle α therewith.
It is also effective if the angle α between the longitudinal middle line of a region of the rudder blade and the middle lines of the flow body are different for both of the areas (A, B).
In terms of the invention it is advantageous if the flow body has predetermined break-off sites, which lead to the destruction of the flow body in the event of the increased effect of force, a blow, an impact or pressure on the flow body. At the same time it is a further advantage if the predetermined break-off sites are designed as predetermined break-off lines. Also, it is effective if the predetermined break-off lines are oriented in the longitudinal and/or transverse direction of the flow body. But it is also advantageous if the predetermined break-off lines are distributed in a reticulated manner over the flow body.
In terms of the invention it is effective if the predetermined break-off sites or predetermined break-off lines are designed as material weaknesses, material reductions, shear lines and/or perforations.
In an advantageous embodiment it is effective if the flow body comprises metal or a non-metallic material or a metal-non-metal mixture.
In another advantageous embodiment it is effective if the flow body comprises a carbon-fiber composite material.
In a further advantageous embodiment it is effective if the material has embedded carbon fibers, graphite fibers and/or fiberglass.
In yet another advantageous embodiment it is effective if the flow body comprises a synthetic material or synthetic materials.
In an advantageous embodiment it is effective if the flow body comprises synthetic material, such as polyoxymethylene, polyformaldehyde or polyacetates.
In a particularly advantageous configuration the flow body comprises two individual bowl-shaped longitudinal bodies conforming to the flow body and held, in longitudinal edge regions, on the outer wall faces of the rudder blade via predetermined break-off lines. The edge regions of both bowl-shaped longitudinal bodies facing the propeller are connected via predetermined break-off lines to a spherical cap-shaped component, in turn connected solidly or detachably to the rudder blade.
The advantage of the inventive configuration of the flow body of a rudder blade of a rudder for ships is that due to the possibility of the flow body being destroyed or self-released while in the event of pressure, blow or impact effect the rudder is not impaired. There is also the possibility that conventional rudder blades can be retrofitted with the inventive flow body.
The invention will be explained in greater detail hereinbelow on the basis of an embodiment by way of the drawings, in which:
To achieve the possibility of self-destruction, the flow body 20 comprises individual wall sections, interconnected via predetermined break-off lines 40 in the form of material weaknesses, material reductions, shear lines, or perforations. Such break-off lines for use in other fields are generally known to those skilled in the art of materials/design engineering and related fields. Rudders are not mass-produced articles but are rather single-unit productions that are adapted in terms of their dimensions, materials and the like for each individual ship. Hence, the specific dimensions and placement of break-off lines will differ for each individual rudder. A person skilled in the art will be able to determine the rated break points for the break-off lines 40 and how to configure the same.
Generally, the material weaknesses, material reductions, shear lines or perforations comprise a thinning or reduction in thickness of the wall of the flow body 20 near the points of attachment to the rudder blade 15 and/or the other parts of the flow body 20. Preferably, the thinning or reduction in thickness of the wall does not pass completely through the wall of the flow body 20. The predetermined break-off lines 40 are preferably designed and arranged on the inner surface such that there are no wrinkles, depressions, grooves, slots or the like in the outer surface of the flow body 20, which is hollow. Thus, the flow body 20 has a smooth outer surface to reduce drag or turbulence around the flow body 20. This is accomplished by arranging the material weaknesses, material reductions, shear lines or perforations on the inner surface of the flow body 20.
Preferably, the material weaknesses, material reductions, shear lines or perforations are configured as indentations, depressions, notches or grooves in the thickness of the material from the inside-out, without passing completely through the wall of the flow body 20. The indentations, depressions, notches or grooves, i.e., reductions in thickness, of the wall are configured such that a pre-determined thickness of material remains on the outer surface of the flow body 20 on top of the indentations, depressions, notches or grooves. Ideally, the indentations, depressions, notches or grooves would reduce the thickness of the wall of the flow body 20, by anywhere from 1% to 99%, keeping in mind that enough material must remain to support structural integrity of the flow body 20.
These material weaknesses, material reductions, shear lines or perforations are configured such that the flow body 20 maintains structural integrity under pre-determined normal operating force conditions, i.e., stresses. In the event of a blow, an impact or pressure on the flow body 20 in excess of the pre-determined normal operating force conditions, the material weaknesses, material reductions, shear lines or perforations are configured to lose structural integrity such that the flow body 20 separates from the rudder 15. Normal operating conditions will vary from ship-to-ship, depending upon the size of the vessel, the force from the wake of the propeller, and the configuration of the rudder 15, among other factors. A person skilled in the art knows how to calculate force vectors and loads on the flow body 20 to determine the required dimensions or thickness of material to maintain structural integrity under normal operating conditions and lose structural integrity when normal operating conditions are exceeded, which dimensions will vary from ship-to-ship based upon the particular rudder design.
The material weaknesses, material reductions, shear lines or perforations may comprise continuous indentations, depressions, notches or grooves in the material or be discontinuous, i.e., dashed or interrupted. The predetermined break-off lines 40 may be configured in a longitudinal direction and/or run transversely to the longitudinal direction of the flow body 20. The predetermined break-off lines 40 may also be irregular in their placement on the flow body 20 or distributed in a reticulated manner over the flow body 20. In a preferred embodiment, the break-off lines 40 are disposed adjacent to the edges of the flow body 20 where it is attached to the rudder 15, as depicted in
An essential element of the inventive design of the rudder blade 15 is that the flow body 20 self-destroys or detaches in the event of the effect of an impact, a blow or pressure. The self-destruction or detachment occurs at the point of the material weaknesses, material reductions, shear lines or perforations forming the break-off lines 40. This ensures that no excessive force is transferred through the flow body 20 to the rudder blade 15 itself so that any impairment to the rudder blade 15 resulting from substantial damage or destruction can be prevented.
Then the flow body 20 comprises two individual bowl-shaped longitudinal bodies 50, 51, conforming to the flow body, which in the region of their longitudinal edges 50a, 51a are held via predetermined break-off lines 40 on the outer wall faces 15a, 15b of the rudder blade 15. The edge regions 50a, 51b of both bowl-shaped longitudinal bodies 50, 51 facing the propeller 12 are connected via predetermined break-off lines 40 to a spherical cap-shaped component, connected solidly or detachably to the rudder blade 15 (
It is further evident from
As depicted in
The flow body 20 is advantageously comprised of metal. Though in another embodiment it can also be formed out of a non-metallic material, such as a carbon fiber composite material preferably with embedded carbon fibers, graphite fibers and/or fiberglass. A metal-non-metal mixture can also be employed.
In another embodiment the flow body 20 can also be made of synthetic material or synthetic materials, such as polyoxymethylene, polyformaldehyde or polyacetates. These materials typically have a high gliding quality, which is advantageous for friction in water.
The inventive rudder blade 15 with the flow body 20 is used advantageously in fully suspended rudders.
It is also effective if the flow body 20 is integrated in the rudder blade 15 or the flow body 20 is attached half and half for example on both sides of the rudder blade 15.
As is evident in
By the leading edge stringer strip 70, 71 of both rudder blade regions A and B being offset to one another, so that the leading edge stringer strip of the upper rudder blade section is offset to the port side and the leading edge stringer strip of the lower rudder blade section is offset to the starboard side or the leading edge stringer strip of the upper rudder blade section is offset to the starboard side and the leading edge stringer strip of the lower rudder blade section is offset to the port side, in each case resulting in two mirror-inverted cross-sectional profiles of both rudder blade regions.
The advantage of such a rudder blade 15 designed according to the invention having two mirror-inverted cross-sectional profiles is first that it prevents vapor lock and it also prevents erosion phenomena on the rudder, occurring through cavitation in fast ships with high-load propellers. The special configuration of the rudder blade contributes to a drop in fuel consumption. There is an improvement in efficiency, in addition to considerable cavitation protection. There is also substantial reduction in weight.
Number | Date | Country | Kind |
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20 2006 017 370.6 | Nov 2006 | DE | national |
Number | Date | Country | |
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Parent | 11786392 | Apr 2007 | US |
Child | 13252938 | US |