Grid for a tunnel thruster

Abstract

A grid (100) is for a tunnel thruster (200). The grid (100) includes a plurality of first radially extending bars (101) arranged at angular intervals from each other, and a plurality of first connecting bars (102). Each of the first connecting bars (102) are connected between adjacent first radially extending bars (101).

Claims

1. A grid for a tunnel thruster, the grid comprising: a plurality of first radially extending bars arranged at angular intervals from each other, and a plurality of first connecting bars, each of the first connecting bars being connected between adjacent first radially extending bars, wherein the first radially extending bars are flat bars, each of the flat bars having a leading edge and a trailing edge that is rounded or chamfered.

2. The grid according to claim 1 wherein the first radially extending bars are flat bars, each of the flat bars being bent in a transverse direction of the flat bar.

3. The grid according to claim 1, wherein each of the first radially extending bars is connected to adjacent first radially extending bars with one of the first connecting bars.

4. The grid according to claim 1, wherein the first connecting bars are connected so that the first connecting bars are at a same distance from a center of the grid.

5. The grid according to claim 1, wherein first ends of the first radially extending bars are connected together.

6. The grid according claim 1, wherein the grid comprises a center part to which first ends of the first radially extending bars are connected.

7. The grid according to claim 1, further comprising a plurality of second connecting bars, each of the second connecting bars being connected between adjacent first radially extending bars-so that the second connecting bars are farther away from a center of the grid than the first connecting bars.

8. The grid according to claim 7, wherein the second connecting bars are connected so that the second connecting bars are at a same distance from the center of the grid.

9. The grid according to claim 7, wherein the grid comprises a plurality of second radially extending bars arranged at angular intervals from each other, each of the second radially extending bars being connected between one first connecting bar and one second connecting bar.

10. The grid according to claim 9, wherein the second radially extending bars are flat bars, each of the flat bars having a rounded or chamfered leading edge.

11. The grid according to claim 9, wherein the second radially extending bars are flat bars, each of the flat bars being bent in a transverse direction of the flat bar.

12. The grid according to claim 1, wherein the first and/or second radially extending bars and the first and/or second connecting bars are flat bars.

13. The grid according to claim 1, comprising 3-11 of the first radially extending bars and/or the second radially extending bars.

14. A tunnel thruster, comprising: a tunnel section, and a propeller arranged inside the tunnel section, wherein the tunnel thruster comprises a grid according to claim 1 arranged in connection with an end of the tunnel section.

15. The tunnel thruster according to claim 14, wherein the grid is arranged inside the tunnel section at a distance of at least 10 mm from the end of the tunnel section.

16. The tunnel thruster according to claim 14, wherein the first radially extending bars are connected to the tunnel section.

17. The tunnel thruster according to claim 14, wherein a quantity of the first radially extending bars and/or the second radially extending bars differs from a quantity of propeller blades.

18. A vessel, wherein the vessel comprises a tunnel thruster according to claim 14 installed in a hull of the vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a grid according to a first embodiment of the invention,

(2) FIG. 2 illustrates a grid according to a second embodiment of the invention,

(3) FIG. 3 illustrates a grid according to a third embodiment of the invention,

(4) FIG. 4 illustrates a grid according to a fourth embodiment of the invention,

(5) FIG. 5 illustrates a grid according to a fifth embodiment of the invention,

(6) FIG. 6 illustrates tunnel thrusters according to an embodiment of the invention, and

(7) FIGS. 7A-7E illustrate exemplary profiles of the first and second radially extending bars.

DETAILED DESCRIPTION OF THE DRAWINGS

(8) The same reference signs are used of the same or like components in different embodiments.

(9) FIG. 1 illustrates a grid according to a first embodiment of the invention. The grid 100 comprises first radially extending bars 101, which are arranged at angular intervals from each other. The first ends of the first radially extending bars 101 are connected together at the centre of the grid 100. The second ends of the first radially extending bars 101 can be connected to a tunnel section of a tunnel thruster (not shown in FIG. 1). The first radially extending bars 101 are straight and have the same length.

(10) The grid 100 also comprises first connecting bars 102. Each first connecting bar 102 is connected between two adjacent first radially extending bars 101 so that one end of the first connecting bar 102 is connected to one first radially extending bar 101 and the other end of the first connecting bar 102 is connected to another first radially extending bar 101. The first connecting bars 102 are connected at the same distance from the centre of the grid 100 and they are curved in such a manner that they together form a circle.

(11) FIG. 2 illustrates a grid according to a second embodiment of the invention. The grid of FIG. 2 differs from the grid of FIG. 1 in that the grid 100 further comprises second connecting bars 103. Each second connecting bar 103 is connected between two adjacent first radially extending bars 101 so that one end of the second connecting bar 103 is connected to one first radially extending bar 101 and the other end of the second connecting bar 103 is connected to another first radially extending bar 101. The second connecting bars 103 are connected farther away from the centre of the grid 100 than the first connecting bars 102. The second connecting bars 103 are connected at the same distance from the centre of the grid 100 and they are curved in such a manner that they together form a circle.

(12) FIG. 3 illustrates a grid according to a third embodiment of the invention. The grid of FIG. 3 differs from the grid of FIG. 2 in that the grid 100 further comprises second radially extending bars 104, which are arranged at angular intervals from each other. Each second radially extending bar 104 is connected to one first connecting bar 102 and one second connecting bar 103. The second radially extending bars 104 are arranged radially between the first radially extending bars 101 in such a manner that their extension lines intersect at the centre of the grid 100. The second radially extending bars 104 are straight and have the same length.

(13) FIG. 4 illustrates a grid according to a fourth embodiment of the invention. The grid of FIG. 4 differs from the grid of FIG. 3 in that the grid 100 comprises a centre part 105 to which the first ends of the first radially extending bars 101 are connected. In FIG. 4, the centre part 105 is a disc.

(14) FIG. 5 illustrates a grid according to a fifth embodiment of the invention. The grid of FIG. 5 differs from the grid of FIG. 4 in that the centre part 105 is a ring and that the first connecting bars 102 and the second connecting bars 103 are straight.

(15) FIG. 6 illustrates tunnel thrusters according to an embodiment of the invention. The tunnel thrusters 200 are installed in a hull 301 of a vessel 300 to provide a transverse thrust. The tunnel thruster 200 comprises a tunnel section 201 that is tubular and open at both ends. The tunnel section 201 has a round cross-section. The tunnel thruster 200 comprises a propeller 202 that is arranged inside the tunnel section 201. The propeller 202 is driven by a motor (not shown in FIG. 6) that is located outside the tunnel section 201. With the motor, the propeller 202 can be rotated to create the thrust in either direction.

(16) The tunnel thruster 200 comprises a grid 100 that is arranged inside and close to an end of the tunnel section 201. The ends of the first radially extending bars 101 are connected to the wall of the tunnel section 201. The number of the first radially extending bars 101 differs from the number of propeller blades 203 in such a manner that these numbers are non-divisible.

(17) FIGS. 7A-7E illustrate exemplary profiles of the first and second radially extending bars. In FIG. 7A there is shown a cross-section of a radially extending bar, which has a leading edge 106 that is chamfered at one side. In FIG. 7B there is shown a cross-section of a radially extending bar, which has a leading edge 106 that is chamfered at one side and a trailing edge 107 that is chamfered at both sides. In FIG. 7C there is shown a cross-section of a radially extending bar in which both the leading edge 106 and the trailing edge 107 are rounded. In FIG. 7D there is shown a cross-section of a radially extending bar in which the leading edge 106 is rounded and the trailing edge 107 is chamfered at both sides. In FIG. 7E there is shown a cross-section of a radially extending bar in which the leading edge 106 is bent in the transverse direction of the radially extending bar.

(18) Only advantageous exemplary embodiments of the invention are described in the figures. It is clear to a person skilled in the art that the invention is not restricted only to the examples presented above, but the invention may vary within the limits of the claims presented hereafter. Some possible embodiments of the invention are described in the dependent claims, and they are not to be considered to restrict the scope of protection of the invention as such.