The invention relates to a rudder for ships in accordance with the preamble of Claim 1.
Rudders of ships with a propeller drive these days often have a so-called Costa bulb. The purpose of the so-called Costa bulb or propulsion bulb is that a bulge, which is designed 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 rests on its bead-shaped configuration, by which it is distinguished from the rudder or respectively rudder blade, resulting in favourable flow.
The Costa bulb however thus protrudes laterally relative to the rudder blade and in the event of the effect of an impact or a blow or pressure it is in the immediate danger zone, before the actual rudder blade would be jeopardised.
But in the event of the effect of an impact or a blow or pressure on the Costa bulb the rudder blade would also 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, before a rudder blade a without Costa bulb would be jeopardised.
The task of the invention is to provide a rudder blade for ships, which in spite of favourable flow relative to external effects due to the effect of an impact or a blow or pressure is less susceptible with respect to damage or destruction and the flow body is independently destroyed in the event of pressure or impact.
At the same time it is advantageous if the flow body divides the rudder blade, viewed in the direction of height, 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 do not match the middle lines of the flow body and form an angle α.
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 the both 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, blow, impact or pressure. 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 reticulated 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 and/or shear lines.
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-fibre composite material.
In a further advantageous embodiment it is effective if the material has embedded carbon fibres, graphite fibres and/or fibreglass.
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 POM synthetic material, such as polyoxymethylene, polyformaldehyde or polyacetates.
Advantageous further developments are described in the independent claims.
A particularly advantageous configuration of the flow body is one where the latter comprises two individual bowl-shaped longitudinal bodies conforming to the flow body, held in the region of their longitudinal edges via predetermined break-off lines on the outer wall faces of the rudder blade, whereby 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 the rudder is not impaired in the event of pressure, blow or impact effect. 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 diagrams, in which:
The flow body 20 is designed such that in the event of pressure, blow or impact effect it is self-destroying.
To achieve the possibility of self-destruction, the wall 25 of the flow body 20 comprises individual wall sections 30, interconnected via predetermined break-off lines 40 in the form of material weaknesses or shear lines (
The predetermined break-off lines 40 are designed and arranged such that in the outer wall face of the flow body 20 there are no wrinkles, depressions, grooves or the like and thus the smooth outer wall face remains intact.
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 or a blow or pressure. This ensures that no excessive force is transferred to the rudder blade itself, so that any impairment to the rudder blade resulting in 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, whereby 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 per
The flow body 20 advantageously comprises metal. Though in another embodiment it can also be formed out of a non-metallic material, such as a carbon fibre composite material preferably with embedded carbon fibres, graphite fibres and/or fibreglass. 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. POM synthetics can be used in this case, 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 vapour 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 economising in weight.
Number | Date | Country | Kind |
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20 2006 017 370.6 | Nov 2006 | DE | national |