Patent Publication Number: US-7591230-B2

Title: Rudder for ships

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a rudder for ships having a rudder blade with a rudder post supported in a rudder trunk. 
   2. Description of the Related Art 
   It is known to make the rudder trunk of a rudder system of wrought steel so that such rudder systems have high weights. 
   SUMMARY OF THE INVENTION 
   The object of this invention is to find for the rudder post an alternative material for the wrought steel. However, a sole material substitution for the rudder post can lead to difficulties in the whole system, for example, to exceeding maximally admissible bearing openings due to too great differences in the stiffness of the components rudder post and rudder trunk. For this reason, a material substitution is also provided for the rudder trunk in creating a rudder trunk with a low weight which has, in spite of a low weight, a high flexural strength and rigidity against torsion. 
   The above-described object is achieved in a rudder according to the type described above by making the rudder trunk of the rudder system consisting of the rudder blade, the rudder post and the rudder trunk of a fiber composite material and, after inserting and aligning, is cast or bonded in an outer nautical trunk tube prepared by the shipyard and extending to the lower edge of the head box. 
   The integration of the rudder trunk in fiber composite construction into the nautical steel structure is effected similarly as for a stern tube. The rudder trunk is inserted and aligned in an outer nautical trunk tube prepared by the shipyard which extends to the lower edge of the head box and is then cast or bonded. Detail solutions (for example inserting of tapered rings made of flexible materials) are to be found for the lower edge of the nautical trunk tube in order to reduce local tension concentrations in the trunk tube made of fiber composite material. 
   The following advantages are achieved with the configuration of the rudder trunk according to this invention. The main arguments for an alternative material for the wrought steel are the difficult procurement situation and the high costs for big cast parts. The use of fiber composite materials in relation with an effective method of production brings advantages as to the costs. The use of a rudder post made of fiber composite material also requires the substitution of the material for the rudder trunk. With fiber composite materials, clear weight advantages are to be achieved compared with wrought steel components. The inserting of the rudder trunk into the nautical structure prepared by the shipyard using an adhesive method brings technological advantages such as better alignment possibilities, the suppression of welded connections and welding delay. 
   Besides the configuration of the rudder trunk of a fiber composite material, according to a further embodiment of the invention, the rudder post of the rudder system is also made of a fiber composite material. 
   The fiber composite material is a carbon fiber composite material or of carbon fibers with an epoxy resin matrix or a glass fiber composite material with polyester resin matrix. 
   According to a further embodiment, the rudder post and/or the rudder trunk are manufactured according to the filament winding method. 
   The use of a rudder trunk and/or of a rudder post made of a fiber composite material is particularly advantageous for a rudder, the rudder trunk of which is provided as a projecting support with a central inner longitudinal bore for receiving the rudder post for the rudder blade and is configured reaching into the rudder blade connected with the rudder post end, wherein a bearing is placed in the inner longitudinal bore of the rudder trunk for bearing the rudder post, bearing which penetrates with its free end in a recess, taper or the like into the rudder blade, wherein the rudder post projects in its end area with a section out of the rudder trunk and is connected with the end of this section with the rudder blade, wherein the connection of the rudder post with the rudder blade is situated above the propeller shaft centre and wherein the inner bearing for the bearing of the rudder post is placed in the rudder trunk in the end area of the rudder trunk. 
   The high stability and flexural strength of the rudder trunk made of a fiber composite material allows placing the bearing for the rudder post in the end area of the rudder trunk, even if the rudder post should have a greater length. Only this bearing arrangement for the rudder post allows that the pressure forces acting onto the rudder blade of the rudder can be absorbed. 
   Furthermore, the rudder post can have end sections made of a non metallic material, in particular of wrought iron, and a central section made of a non metallic material connected with the end sections. 
   According to a further embodiment, the central section of the rudder post consisting of a non metallic material is made of a carbon fiber composite material or of carbon fibers, preferably of graphite fibers. 
   Both end sections of the rudder post made of wrought iron have, on their front sides turned to each other, neck-type reduced peg-shaped sections, the peripheral surfaces of which are provided with structures as adhesive surfaces for the central section made of carbon fibers which surround the peg-shaped sections as windings, wherein the carbon fibers are sheathed and lined with a cast resin in the whole winding area extending over the length of the central section. 
   Such a configuration of the rudder post brings the advantage that rudder posts with a big length, a big diameter and a high weight can be produced for rudders for water vehicles without the necessity of manufacturing the whole rudder post of wrought iron since only the end sections of the rudder post are produced of wrought iron, while the central section of the rudder post situated between the end sections is made of a non metallic material and in particular of a carbon fiber material or of carbon fibers, preferably of graphite fibers which form in the form of windings the central post section of the rudder post, wherein the windings of the carbon fiber composite material or the carbon fibers extend into the opposite ends of the end sections of the rudder post and are fixedly connected with them. In this manner, a rudder post is created, the end sections are made of wrought iron and can be subjected to the highest loads. Moreover, the end sections of the rudder post made of wrought iron take up the bearings for the bearing of the rudder post in a rudder trunk bearing. 
   End sections of wrought iron can be omitted when the whole rudder post is made for example of a carbon fiber composite material and is manufactured according to the filament winding method. For this configuration, neither the flexural strength nor the resistance to torsion are reduced. 
   The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
       FIG. 1  is a side view of a rudder arrangement provided in the after body area with a rudder post placed in a rudder trunk; 
       FIG. 2  shows partly in an elevational view and partly in a vertical sectional view a rudder system with the rudder trunk, the rudder post and the rudder blade; 
       FIG. 3  shows an enlarged cutout A according to  FIG. 2  with the rudder trunk reaching to the lower edge of the head box and inserted as well as cast or bonded in an outer trunk tube; 
       FIG. 4  shows partly in an elevational view and partly in a vertical sectional view the rudder system with the rudder post supported on one end side in the trunk tube and fixed on the rudder post; 
       FIG. 5  is a view of the rudder post with end-sided sections made of wrought iron and with a central rudder shaft section made of a non metallic material, and 
       FIG. 6  is a view of a rudder post with end sections made of wrought iron and a central section made of wound carbon fibers connected with the end sections. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   For the embodiment of a rudder system for ships shown in  FIGS. 1 and 4 ,  10  designates a hull,  20  a rudder trunk with its both ends  20   a ,  20   b ,  30  a rudder blade and  40  a rudder post. 
   The tube-type rudder trunk  20  configured as a projecting support is fixedly connected with its upper end  20   a  with the hull  10  and has an inner bore  25  which receives the rudder post  40 . The rudder trunk  20  is guided into the rudder blade  30  which is fixedly connected with the free lower end  20   b  of the rudder post  40  which traverses the inner bore  25  of the rudder trunk bearing  20 . The preferably cylindrical recess  35  which is configured in the rudder blade  30  for receiving the free end  20   b  of the rudder trunk  20  is limited by a lateral planking  36 ,  37  ( FIG. 4 ). 
   The rudder trunk  20  is provided with a central inner longitudinal bore  25  for receiving the rudder post  40  for the rudder blade  30  and is configured reaching into the rudder blade  40  connected with the rudder post end, wherein at least one bearing  70  is placed in the inner longitudinal bore  25  for bearing the rudder post, this bearing reaching with its free end  40   a  into a recess, taper or the like into the rudder blade  30 , wherein the rudder post  40  is guided in its end area  40   a  with a section  40   b  from the rudder trunk  20  and which is connected with the end of this section  40   b  with the rudder blade, wherein the connection of the rudder post  40  with the rudder blade  30  is situated above the propeller spindle middle PM. The inner bearing  70  for the bearing of the rudder post  40  is placed in the rudder trunk in the end area of the rudder trunk  20  ( FIG. 4 ). 
   For the bearing of the rudder post  40 , the rudder trunk  20  has at least one bearing. For the embodiment shown in  FIG. 4 , two bearings  70 ,  71  are provided, namely an inner bearing  70  and an outer bearing  71 , wherein the bearing  70  is configured on the inner wall surface of the rudder trunk bearing  20  and the other bearing  71  on the outer wall surface of the rudder trunk or on the inner wall surface of the bearing provided on the rudder blade  30 . 
   The rudder post  40  supported in the rudder trunk  20  is made of wrought iron or is preferably configured in such a manner that both its end sections  41 ,  42  are made of wrought iron, wherein the central post section  45  is made of a non metallic material, in particular of a carbon fiber composite material or of carbon fibers, preferably of graphite fibers with or without an epoxy resin matrix ( FIG. 5 ). By wrought iron, we understand an iron with a carbon content situated under 0.8%. Advantageously, the rudder post  40  is produced according to the known filament winding system. 
   For the fixing of the central post section  45  of the rudder post  40 , different construction configurations can be provided. As the embodiment according to  FIG. 5  shows, the opposite front sides of both end sections  41 ,  42  have peg-shaped sections  51 ,  52  which are preferably with an outer wall structure  51   a ,  52   a  in order to guarantee the grip and the hold of the central post section  45  made of carbon fibers. Preferably, the carbon fibers or the carbon fiber composite material are fixed according to the filament winding system on the pegs  51 ,  52  of the end sections  41 ,  42 , wherein the windings extend across the periphery of both pegs  51 ,  52  and over the whole length of the central post section  45 . The carbon fibers are sheathed or cast with a cast resin for increasing the strength. 
   The configuration of the rudder post  20  is particularly preferred in so far as very big lengths of rudder posts can be produced for a lowest weight. For a rudder post having for example a length of 10 m, the weight is reduced by more than 50% with respect to a rudder post which is completely made of wrought iron. 
   A further embodiment provides that the rudder post  40  placed in the rudder trunk  20  has material reinforcements  80  in the area of the bearings  70 ,  71  placed in the rudder trunk  20 , wherein preferably the material reinforcements  80  are provided in the area of the rudder trunk end  20   b . These material reinforcements  80  are configured on the rudder post  40  preferably on the end section  42  of the rudder post  40  in the area of the inner bearing  70  provided on the rudder trunk  20  ( FIG. 4 ). 
   For the embodiment shown in  FIGS. 2 and 3 , the rudder trunk  20  is made of a fiber composite material  100  and is inserted into a nautical outer trunk tube  90  made of steel or of another appropriate material prepared by the shipyard, reaching into the lower edge  11   a  of the head box  11  and inserted into the rudder blade, wherein, after alignment of the rudder trunk  20  in the nautical trunk tube  90  the intermediate space formed between both components  20 ,  90  is cast with a cast resin, or both components  20 ,  90  are bonded together. 
   Due to the fact that the rudder trunk  20  is connected with the trunk tube  90  because of the bonding or the use of cast resins, a firm compound is obtained between both components so that thin-walled materials can be used for the tube-type rudder trunk and the trunk tube which moreover results in a saving of weight which is particularly important when the matter is of bigger rudder installations. 
   The integration of the rudder trunk  20  in fiber composite material into the nautical steel structure, i.e. into the rudder blade  30 , takes place similarly as for the stern tube of a ship. The rudder trunk  20  is inserted into an outer nautical trunk tube  90  of steel or of another appropriate material, prepared by the shipyard, which reaches to the lower edge  11   a  of the head box  11 . This nautical trunk tube  90  is inserted and fixed in the rudder blade  30 . The rudder trunk  20  made of the fiber composite material is then aligned in the nautical trunk tube  90 . The intermediate space between the nautical trunk tube  90  and the rudder trunk  20  is then cast for example with a cast resin  95  or both components are bonded together so that a firm connection is created between the nautical trunk tube  90  and the rudder trunk  20  ( FIG. 3 ). The rudder post  40  is then inserted into the system configured in this manner into the rudder trunk  20  and is supported in the rudder blade  30  and fixed at the ends with the rudder blade. Detail solutions, for example placing of tapered rings made of flexible materials, are possible for the lower edge of the nautical trunk tube in order to reduce here local tension concentrations in the trunk tube  20  made of fiber composite material. 
   The fiber composite material for producing the rudder trunk  20  and/or of the rudder post  40  is a carbon fiber composite material or of carbon fibers of an epoxy resin matrix or a glass fiber composite material with polyester resin matrix. 
   The rudder post  40  as well as the rudder trunk  20  are produced according to the filament winding system. 
   Fiber composite materials have essential advantages compared with wrought steel since the carbon fiber materials with epoxy resin matrix compared with glass fiber materials with polyester resin matrix have the better material properties with respect to rigidity, resistance and firmness and however result in higher material costs. However, the selection of materials for the rudder trunk should take place only in connection with the dimensioning of the rudder post in order to achieve an adaptation of the structure rigidity of both components rudder trunk and rudder post. 
   The main argument for an alternative material such as a fiber composite material for the wrought steel are the difficult procurement situation and the high costs for big cast parts. The use of fiber composite materials in relation with an effective method of production brings advantages as to the costs. 
   With fiber composite materials, clear weight advantages are to be achieved compared with wrought steel components. 
   The inserting of the rudder trunk  20  by a bonding method or casting method into the nautical structure prepared by the shipyard brings technological advantages such as better alignment possibilities, suppression of welded connections and welding delay. 
   If fiber composite materials with the properties of wrought iron are used for the rudder trunk  20 , a rudder trunk  20  configured in such a manner can also be used without intercalating a trunk tube  90  of steel. 
   Furthermore, the invention comprises a method for manufacturing a rudder trunk  20  which receives the rudder post  40  and which is inserted in a rudder blade  30  of the rudder for ships, wherein a nautical outer trunk tube  90  of steel or of another appropriate material is used and fixed in the rudder blade  30 , a rudder trunk  20  made of a fiber composite material is then inserted into the nautical trunk tube  90  and is aligned in the trunk tube  90 , after which the intermediate space between the rudder trunk  20  and the trunk tube  90  is filled with a cast resin  95  or both components  20 ,  90  are bonded together. The nautical trunk tube  90  is preferably inserted by reaching to the lower edge  11   a  of the head box  11  of the rudder blade  30 . 
   While specific embodiments of the invention have been described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.