RUDDER MECHANISM FOR SHIP

Abstract: A rudder mechanism (10) for a ship comprises a support bearing (17) fixed to the bottom of a stern (12) of the ship, a rudder shaft (16) with one end rotatably supported by the support bearing (17), a swayable shaft member (20) connected to the other end of the rudder shaft (16), and a rudder wing (18) connected to the swayable shaft member (20) and disposed behind a propeller (14) of the ship. The swayable shaft member (20) and rudder wing (18) form a swayable wing portion (22) swayable in a ship backward direction. The swayable shaft member (20) comprises a projection (24) fixed to the rudder shaft (16) or the rudder wing (18), a projection receiver (26) fixed to the other of them and engaged with the projection (24), and a rotatable shaft (28) inserted into the engaged projection (24) and projection receiver (26) to enable them to sway relative to each other. The projection (24) and projection receiver (26) have restriction faces (30) for restricting the swayable wing portion (22) from swaying in a ship forward direction beyond a vertical position and from swaying in a ship backward direction beyond a maximum backward position. With this arrangement, the rudder wing (18) will not be just behind the propeller (14) of the ship while the ship is sailing, thereby improving the propelling efficiency and fuel consumption of the ship.

Description: The present invention relates to a rudder mechanism disposed at the stern of a ship and capable of reducing resistance against ship propelling water flows. Figure 9 shows a conventional rudder mechanism disposed at the stern of a ship. The rudder mechanism is positioned behind a propeller P and has a rudder shaft S vertically and rotatably supported at the stern. A rudder wing W is fixed to an end of the rudder shaft S and rotatable together with the rudder shaft S. The rudder shaft S is turned manually or by motor to provide a required rudder angle. The conventional rudder mechanism is not flexible, however, and fixedly positioned with the rudder shaft S behind the propeller P, so that, as shown in Fig. 10, the rudder mechanism may partly block water flows propelled backward by the propeller P. Particularly when the ship sails across the ocean at a full speed with no rapid steering operation, the rudder mechanism resisting the propelling water flows may increasingly deteriorate the propelling efficiency and fuel consumption of the ship. Document GB-A-259 831 shows a rudder mechanism for a ship comprising a support bearing fixed to a lower part of the stern of the ship, a rudder spindle of which one end is rotatably supported by the support bearing, a rudder wing being movable from a position in which two thirds of the surface of the rudder wing lie behind the rudder spindle to a position in which two thirds of the surface of the rudder wing lie in front of the rudder spindle. This construction is made in order to ensure that the rudder can be moved with the most extreme ease at full speed not only when the vessel is going ahead, but also when it is going astern. It is the object of the present invention to improve the propelling efficiency and the fuel consumption of the ship. This problem is solved by a rudder mechanism as defined in claim 1. According to the invention, the swayable shaft member comprises a projection fixed to and protruding from one end of the rudder shaft and the rudder wing; a projection receiver fixed to the other end of the rudder shaft and the rudder wing and engaged with the projection; and a rotatable shaft inserted into the engaged projection and projection receiver such that the engaged projection and projection receiver can sway relative to each other. The projection and projection receiver have restriction faces for securely restricting the swayable wing portion from swaying in a ship forward direction beyond a vertical position and from swaying in a ship backward direction beyond a maximum backward position. The projection is preferably a tonguelike plate having an arc edge, while the projection receiver is preferable to have a groove for receiving the tonguelike plate. The groove has an arc guide corresponding to the arc edge of the projection. The restriction faces include a first restriction face extending from the arc edge of the tonguelike plate; a second restriction face extending from the base of the tonguelike plate and substantially orthogonal to an axial line of the rudder shaft with the swayable rudder portion being in the vertical position; a third restriction face extending from the arc guide of the projection receiver; and a fourth restriction face which is an end face of the projection receiver. The first restriction face cooperates with the third restriction face while the second restriction face cooperates with the fourth restriction face, thereby restricting the swayable wing portion from swaying in the ship forward direction beyond the vertical position. The swayable shaft member may comprise a disk-like projection fixed to and protruding from the other end of the rudder shaft; a projection receiver fixed to the rudder wing and engaged with the disk-like projection; and a rotatable shaft inserted into the engaged disk-like projection and projection receiver such that the engaged disk-like projection and projection receiver can sway relative to each other. The projection receiver may have a groove for receiving the disk-like projection. The disk-like projection may have a radially protruding portion provided with a restriction face cooperating with the base of the projection receiver to restrict the swayable wing portion from swaying in the ship forward direction beyond the vertical position. The base of the disk-like projection preferably has a V-shape side. This S-shape side involves a first end face oriented downward and cooperating with an end face of the projection receiver to restrict the swayable wing portion from swaying in the ship forward direction beyond the vertical position; and a second end face oriented downward and cooperating with the end face of the projection receiver to restrict the swayable wing portion from swaying in a ship backward direction beyond a maximum backward position. The rudder wing preferably comprises a rectangular plate-like body. A rectangular part of the rudder wing defined by a long side and about one half to one third of a short side of the rectangular plate-like body is in the ship forward side relative to an axial line of the rudder shaft with the swayable wing portion being in the vertical position. According to the above rudder mechanism of the invention, the swayable rudder portion is substantially in the vertical position when the ship is stationary. When the ship is driven forward, a propeller of the ship generates backward water flows, which gradually make the swayable rudder portion sway backward around the swayable shaft member. When the ship reaches to a full speed, only a part of the swayable rudder portion is in the water and still enables a steering operation of the ship. Fig. 1 is a perspective view showing the stern of a ship employing a rudder mechanism according to an embodiment of the present invention; Fig. 2 is a view showing the essential part of a swayable shaft member; Fig. 3 is a sectional view taken along a line III-III of Fig. 2; Fig. 4 is a right side view of Fig. 2; Fig. 5(a) is a perspective view showing a projection receiver; Fig. 5(b) is a perspective view showing a projection; Fig. 6 is a back view showing an operation of the rudder mechanism; Fig. 7 and 8 are front and right side views, respectively, showing a modification of the embodiment with first and second arcing restriction faces; Fig. 9 is a view showing a conventional rudder mechanism; Fig. 10 is a back view showing an operation of the conventional rudder mechanism; Fig. 11 is a perspective view showing the essential part of a swayable shaft member according to another embodiment of the invention; Fig. 12 is a front view showing the swayable shaft member; Fig. 13 is a side view showing an operation of the swayable shaft member ; Fig. 14 is a sectional view taken along a line XIV-XIV of Fig. 13; Fig. 15(a) is a perspective view showing a projection of the swayable shaft member ; Fig. 15(b) is a perspective view showing a projection receiver of the swayable shaft member; Fig. 16 is a sectional view taken along a line XVI-XVI of Fig. 15(a); and Fig. 17 is a perspective view showing the essential part of the swayable shaft member seen from a different angle. A rudder mechanism for a ship according to an embodiment of the invention will be explained with reference to Figs. 1 to 8. Figure 1 is a side view showing a rudder mechanism 10 of the embodiment. The rudder mechanism 10 is disposed under the bottom of a stern 12 behind a propeller 14 of a ship. The rudder mechanism 10 includes a rudder shaft 16, one end of which is rotatably supported by a support bearing 17 shown in dotted line, which is fitted to the bottom of the stern 12. The rudder mechanism 10 further includes a rudder wing 18 fixed to the other end of the rudder shaft 16 through a swayable shaft member 20. This swayable shaft member 20 forms a feature of the invention. The swayable shaft member 20 and the rudder wing 18 form a swayable wing portion 22. In Figs. 2, 3 and 4, the rudder shaft 16 is a cylindrical pipe supported rotatably by the support bearing 17 fixed to the bottom of the stern 12 of the ship. The rudder shaft 16 is connected to the rudder wing 18 through the swayable shaft member 20. As shown in Fig. 5(a) and 5(b), the swayable shaft member 20 comprises a projection 24, a projection receiver 26, and a rotatable shaft 28. The projection 24 is attached to and protrudes from the rudder wing 18. The projection receiver 26 is fixed to the rudder shaft 16 and holds the projection 24 from both sides thereof. The rotatable shaft 28 is inserted into the engaged projection 24 and projection receiver 26 such that the projection 24 and projection receiver 26 can sway relative to each other. The projection 24 and projection receiver 26 have restriction faces 30 that restrict the swayable wing portion 22 from swaying in a ship forward direction beyond a vertical position and from swaying in a ship backward direction beyond a maximum backward position. When the ship moves forward, the propeller 14 generates backward water flows, by which the swayable wing portion 22 is gradually swayed backward around the swayable shaft member 20. When the ship moves forward at a full speed, the swayable wing portion 22 is swayed to the maximum backward position. Consequently, no obstacle may exist just behind the propeller 14 to block the ship propelling water flows, thus improving the propelling efficiency and fuel consumption of the ship. The swayable wing portion 22 is restricted from swaying in the ship forward direction beyond the vertical position. Namely, the swayable wing portion 22 is prevented from turning in the ship forward direction beyond a position where the swayable wing portion 22 linearly aligns with the rudder shaft 16. Also, the swayable wing portion 22 is restricted from swaying in the ship backward direction beyond the maximum backward position. The projection 24 is a tonguelike plate 36 having a center shaft hole 32 and an arc edge 34. The projection receiver 26 is fixed by bolts to the lower end of the rudder shaft 16 which is a cylindrical pipe. The projection receiver 26 holds the projection 24 from both sides thereof. The projection receiver 26 has a groove 26a forming an arc guide 38 that corresponds to the arc edge 34 of the projection 24. As explained above, the projection 24 and projection receiver 26 have the restriction faces 30 for restricting the swayable wing portion 22 from swaying in the ship forward direction beyond the vertical position and from swaying in the ship backward direction beyond the maximum backward postion. The restriction faces 30 comprise a first, second, third and fourth restriction faces 30a, 30b, 30c and 30d. The first restriction face 30a is formed on the arc edge 34 of the tonguelike plate 36 and rises obliquely upward as shown in Fig. 5(b). The second restriction face 30b extends from the base of the tonguelike plate 36 and is substantially orthogonal to an axis of the rudder shaft 16 with the swayable wing portion 22 being in the vertical position. The second restriction face 30b is formed on each side of the tonguelike plate 36. The third restriction face 30c extends from the arc guide 38 of the projection receiver 26, and rises obliquely upward as shown in Fig. 5(a) to correspond to the first restriction face 30a. The third restriction face 30c cooperates with the first restriction face 30a to restrict the swayable wing portion 22 from swaying in the ship forward direcrtion (clockwise direction) beyond the vertical position. The fourth restriction face 30d is an end face of each side portion of the projection receiver 26 for holding the projection 24. The fourth restriction face 30d cooperates with the second restriction face 30b to restrict the swayable wing portion 22 from swaying in the ship forward direction (clockwise direction) beyond the vertical position. Each side of the projection receiver 26 has a shaft hole 40, and as shown in Figs. 2 and 4, the rotatable shaft 28 is inserted into the shaft holes 40 of the projection receiver 26 and the shaft hole 32 of the engaging projection 24, thereby rotatably supporting the projection 24 and projection receiver 26. The swayable wing portion 22 is restricted from turning in the ship backward direction (counter-clockwise direction) beyond the maximum backward position by an edge 42 of the second restriction face 30b and an edge 44 of the fourth restriction face 30d. The swayable shaft member 20 is preferably located close to and higher than the bottom of the ship, so that, when the ship moves forward, the swayable wing portion 22 may sway in the ship backward direction with only a part of the rudder wing 18 sinking in the water and the main part of the rudder wing 18 not existing just behind the propeller 14. As shown in Fig. 2, the rudder wing 18 is a rectangular metal plate. With the rudder wing 18 being in the vertical position, a forward section 46 of the rudder wing 18 is in the ship forward side relative to an axial line of the rudder shaft 16. The forward section 46 may be defined by a long side and about a third of a short side of the rudder wing 18. The length of the short side of the forward section 46 may be set to occupy at most a half of the short side of the rudder wing 18, depending on a draft of the ship or a fitting position of the swayable shaft member 20. When the ship moves forward, particularly at a full speed, the forward section 46 sinks in the water as shown in Fig. 1 but enables a steering operation of the ship. When the ship is not moving, the swayable wing portion 22 takes the vertical position indicated with a continuous line in Fig. 1. If the propeller 14 is driven to move the ship forward, water flows pushed by the propeller 14 gradually turn the swayable wing portion 22 in the direction of an arrow mark "a" (the ship backward direction) in Fig. 1. When the ship reaches to a full speed, the swayable wing portion 22 may take the maximum backward postion indicated with a dotted line in Fig. 1, where only the forward section 46 of the rudder wing 18 is under the water to enable a steering operation of the ship. As shown in Fig. 6, there is no obstacle just behind the propeller 14 to block water flows, when the ship moves forward. Accordingly, a propelling force of the propeller 14 is fully utilized to move the ship, thereby saving fuel consumption. Since the resistance against the propelling force by the rudder wing 18 is reduced, the propeller 14 strongly pushes water downward to push the ship upward. With the synergetic effects, the speed and fuel consumption of the ship are improved greatly. According to an experiment, the rudder mechanism of the invention can reduce the fuel consumption by 20% to 30%, compared to the conventional rudder mechanism. In addition, the propelling efficiency of the ship is improved to increase the speed of the ship about two times the one achieved by the conventional rudder mechanism. At a full-speed forward movement, the ship travels as if it slides over the water. Particularly in the ocean where a gentle steering operation is sufficient at the full speed movemnt, the backward swaying effect of the swayable wing portion 22 is remarkable. When the ship arrives at a port, the propeller 14 is slowed to reduce the speed of the ship. Then, water flows generated by the propeller 14 are weakened, so that the weight of the rudder wing 18 brings the swayable wing portion 22 into the water. Finally, the swayable wing portion 22 takes the vertical position indicated with the continuous line in Fig. 1. This enables a rapid steering operation for a backward movement or slow forward movement of the ship. At this time, the swayable wing portion 22 is restricted from swaying in the ship forward direction beyond the vertical position by the cooperating first and third restriction faces 30a and 30c and by the cooperating second and fourth restriction faces 30b and 30d. When the ship advances at a full speed with no rapid steering operation, the swayable wing portion 22 partly sinks in the water and is not just behind the propeller 14. For a backward movement or slow speed forward movement of the ship, the swayable wing portion 22 is automatically brought just behind the propeller 14 to enable a sufficient steering operation of the ship. The projection 24 may be attached to the rudder shaft 16 and the projection receiver 26 to the rudder wing 18. Only the first and third restriction faces 30a and 30c are sufficient if they can surely restrict the swayable wing portion 22 from swaying in the ship forward direction beyond the vertical position. It is also possible to form arc faces on the first and third restriction faces 30a and 30c as shown in Figs. 7 and 8. Figures 11 to 17 are views showing a swayable shaft member of a rudder mechanism for a ship, according to another embodiment of the invention. In the figures, like parts are represented with like reference marks, and their explanations are omitted. Similar to the previous embodiment, a swayable shaft member 20 comprises a projection 24, a projection receiver 26 engaging with the projection 24, and a rotatable shaft 28 inserted into the engaged projection 24 and projection receiver 26 such that the projection 24 and projection receiver 26 are swayable relative to each other. The projection 24 is attached to and protrudes from a rudder shaft 16, while the projection receiver 26 is attached to a rudder wing 18, which forms, with the swayable shaft member 20, a swayable wing portion 22. The projection recdiver 26 has a groove 48 into which the projection 24 is inserted and held. As shown in the figures, the projection 24 comprises a disk 50, a sectorial part of which is fixed to the center of the rudder shaft 16. The disk 50 has a radial projection 52 having a restriction face 30e. The restriction face 30e extends along an axis of the rudder shaft 16 and is oriented in the ship backward direction. The restriction face 30e abuts against a base 54 of the projection receiver 26, thereby restricting the swayable wing portion 22 from swaying in the ship forward direction beyond a vertical position. The projection receiver 26 may be attached to the rudder shaft 16, and the projection 24 to the rudder wing 18. Due to resistance against water flows and the weight of the disk 50, however, it is reasonable to attach the projection 24 to the rudder shaft 16 and the projection receiver 26 to the rudder wing 18, as explained above. As shown in Figs. 11, 13 and 16, a base 50a of the disk 50 has a V-shape side face having a first end face 56 and a second end face 58. The first end face 56 is oriented downward and cooperates with an end face 26b of the projection receiver 26 to restrict, similar to the restriction face 30e, the swayable wing portion 22 from swaying in the ship forward direction beyond the vertical position. The second end face 58 cooperates with an end face 26c of the projection receiver 26 to restrict the swayable wing portion 22 from swaying in the ship backward direction (counterclockwise direction) beyond a maximum backward position. As explained above, the swayable wing portion 22 is restricted from swaying in the ship forward direction beyond the vertical position by the restriction face 30e of the radial projection 52 cooperating with the base 54 of the projection receiver 26 and by the first end face 56 of the base 50a of the disk 50 cooperating with the end face 26b of the projection receiver 26. Further, the swayable wing portion 22 is restricted from swaying in the ship backward direction beyond the maximum backward position by the end face 26c of the projection receiver 26 cooperating with the second end face 58 of the base 50a of the disk 50. In this embodiment, actions of the swayable shaft member 20 in the forward and backward movements of the ship are the same as those of the previous embodiment. In this embodiment, however, the projection 24 and projection receiver 26 are easier to manufacture, compared to those of the previous embodiments. In addition, the swayable wing portion 22 of this embodiment is more securely restricted from swaying in the ship backward direction. The rudder mechanism of the present invention is applicable not only for small ships but also for large ships, if the swayable shaft member of the rudder mechanism is made harder. As explained above, according to a rudder mechanism for a ship of the invention, a swayable shaft member is attached to a rudder shaft and to a rudder wing of the rudder mechanism to form a swayable wing portion that can sway in a ship backward direction. Accordingly, the rudder wing will not be just behind a propeller of the ship while the ship is sailing, thereby improving the propelling efficiency and fuel consumption of the ship.

Claims: A rudder mechanism for a ship, comprising: a support bearing (17) fixed to a lower part of a stern (12) of the ship; a rudder shaft (16) of which one end is rotatably supported by said support bearing (17); a swayable shaft member (20) connected to the other end of said rudder shaft (16); and a rudder wing (18) connected to said swayable shaft member and disposed behind a propeller (14) of the ship, said swayable shaft member (20) and rudder wing (18) forming a swayable wing portion (22) that is swayable in a ship backward direction, characterised in that said swayable shaft member (20) comprises: a projection (24) fixed to and protruding from one end of said rudder shaft (16) and said rudder wing (18); a projection receiver (26) fixed to the other end of said rudder shaft (16) and said rudder wing (18), and engaged with the projection (24); and a rotatable shaft (28) inserted into the engaged projection (24) and projection receiver (26), such that the engaged projection and projection receiver can sway relative to each other, the projection (24) and projection receiver (26) having restriction faces (30) for restricting the swayable wing portion (22) form swaying in a ship forward direction beyond a vertical position and from swaying in a ship backward direction beyond a maximum backward postion. A rudder mechanism for a ship according to claim 1, wherein the projection (24) is a tonguelike plate (36) having an arc edge (34), while the projection receiver (26) has a groove (26a) for receiving the tonguelike plate (36), the groove having an arc guide (38) corresponding to the arc edge (34) of the projection (24), and wherein the restriction faces (30) include: a first restriction face (30a) extending from the arc edge (34) of the tonguelike plate (36); a second restriction face (30b) extending from the base of the tonguelike plate (36) and substantially orthogonal to an axial line of said rubber shaft (16) with the swayable rudder portion (22) being in the vertical position; a third restriction face (30c) extending from the arc guide (38) of the projection receiver (26); and a fourth restriction face (30d) which is an end face of the projection receiver (26), the first restriction face (30a) cooperating with the third restriction face (30c) while the second restriction face (30b) cooperating with the fourth restriction face (30d), thereby restricting the swayable wing portion (22) from swaying in the ship forward direction beyond the vertical position. A rudder mechanism for a ship according to claim 1, wherein said swayable shaft member comprises: a disk-like projection (24,50) fixed to and protruding from the other end of said rudder shaft (16); a projection receiver (26) fixed to said rubber wing (18) and engaged with the disk-like projection (24,50); and a rotatable shaft (28) inserted into the engaged disk-like projection (24,50) and projection receiver (26) such that the engaged disk-like projection and projection receiver can sway relative to each other, the projection receiver (26) having a groove (48) for receiving the disk-like projection (24,50) the disk-like projection (24,50) having a radially protruding portion (52) provided with a restriction face (30e) cooperating with the base (54) of the projection receiver (26) to restrict the swayable wing portion (22) from swaying in a ship forward direction beyond a vertical position. A rudder mechanism for a ship according to claim 3, wherein the base (50a) of the disk-like projection (24,50) has a V-shape side, the V-shape side having: a first end face (56) oriented downward and cooperating with an end face (26b) of the projection receiver (26) to restrict the swayable wing portion (22) from swaying in the ship forward direction beyond the vertical position; and a second end face (58) oriented downward and cooperating with the end face (26c) of the projection receiver (26) to restrict the swayable wing portion (22) from swaying in a ship backward direction beyond a maximum backward position. A rudder mechanism for a ship according to any one of claims 1 to 4, wherein said rudder wing (18) comprises a rectangular plate-like body, a rectangular part of said rudder wing (18) defined by a long side and about one half to one third of a short side of the rectangular plate-like body being in the ship forward side relative to an axial line of said rudder shaft (16) with the swayable wing portion (22) being in the vertical position.

Inventors: KANAZAKI, KIHACHIRO
Applicants: KANAZAKI, KIHACHIRO
Application year: 1990
Main classification: B63H25
IPC codes: B63H25