The invention relates to a method for dampening the rolling of a vessel and recover- ing the energy of the rolling motion, in which method the rolling of the vessel is dampened by rotating a mass in rhythm with the rolling around a vertical axis along a circular track in one direction of revolution.

The invention further relates to a device for dampening the rolling of a vessel and recovering the energy of the rolling motion, which device includes a mass dampening the rolling of the vessel, which is arranged to be moved in rhythm with the rolling.

In order to dampen the rolling of a vessel, it is known to move ballast from one side of the vessel to the other. As the ballast is typically used water, such as, for example, in KR 20160069637. From WO 2016/003345 Al is known a rolling dampening arrangement, which can be used to also produce energy along with the dampening. All of these have the disadvantage that they require a specially constructed vessel. From WO 2016/110610 Al is known an adjustment system, which can be used to optimize the energy production of a wave power plant when the wave power plant is implemented as a combination of a mass rotator and a gyroscope.

From DD 157322 are known a method and a device for dampening the rolling of a vessel, in which method the rolling of the vessel is dampened by rotating a mass in rhythm with the rolling around a vertical axis along a circular track in one direction of revolution. An attempt is made to keep the phase difference in relation to the rolling of the vessel at 180 degrees, which means that an attempt is made to dampen the rolling only by means of the weight of the mass. In this case, the dampening is not the best possible, because the effect of the dynamic motion of the mass on the dampening has not been taken into consideration. Dampening efficiency cannot be adjusted. Recovery of the energy of the rolling motion has also not been arranged.

The object of the invention is to achieve a method and device for dampening the rolling of a vessel, which can also be used to produce energy along with the damp- ening and which does not require a specially constructed vessel, but instead the device can be installed into many types of vessels.

This object is achieved by a method presented in the accompanying claim 1 and a device presented in claim 7. The dependent claims present preferred embodiments of the invention.

In the following, the invention is described in more detail with reference to the accompanying drawings, in which:

Fig. 1 shows, as viewed from above, a vessel, into which are installed the rolling dampening devices according to the invention;

Fig. 2 shows schematically a device according to the invention for executing the method;

Fig. 3 shows an example of an alternative structure of the device;

Fig. 4 illustrates the functional principle of the method and the device at the different phases of the rolling using the exemplary embodiment of Fig.

2; and

Fig. 5 illustrates the functional principle of the method and the device at the different phases of the rolling using the exemplary embodiment of Fig. 3.

Fig. 1 shows a vessel 1 having an elongated hull, to the midline of which is placed a device 2 for dampening the rolling. Reference numeral 3 designates a vertical plane, which extends through the midline of the vessel and the rolling axis. The devices 2, which are units to be installed separately, can be several in a row. Alternatively, the devices 2 can be installed symmetrically to both sides of the vertical plane 3. The length of the vessel is more than 4 times the width of the vessel. In this case, waves coming from the side powerfully roll the vessel. This rolling can be dampened, i.e. decreased, by a method and device according to the invention such that, as the device operates, it is energy-neutral and, under favourable conditions, ener- gy-generating. Under suitable conditions, a device installed into a moving or anchored vessel can also be used as an electric generator functioning by wave power.

The vertical axis 4 of the device shown in Figs. 2 and 3 is placed into the vertical plane 3, and onto the vertical axis 4 is eccentrically bearing-mounted a mass or a weight 5, which can be just a mass, or a combination of a mass and a flywheel. By vertical axis is meant herein the axis, which is vertical when the vessel is in calm water. The mass 5 is rotated around the vertical axis 4 along a circular track in one direction of rotation and the position of the mass 5 in relation to the inclination an- gle of the vessel is adjusted by alternately braking and alternately boosting the rotational motion of the mass 5 around the vertical axis 4 such that the dynamic coun- terforce exerted on the vessel has a primarily dampening effect on the rolling. This is achieved by keeping the mass 5 in a suitable phase in relation to the rolling motion of the vessel. If the rolling of the vessel is considered as having a sinusoidal motion and the revolving motion of the mass is considered as having constant speed, the most preferable phase is such, in which the mass is at its most outward position to the front or to the back in the direction of the longitudinal axis at the moment when the rolling motion is at its extreme position to the right or to the left, and the mass 5 revolves one revolution during the same time as the vessel swings once to each side. This set-up dampens the rolling motion during the entire revolution as the dampening efficiency varies sinusoidally with a double frequency between zero and the maximum. The dampening work is at zero only at that moment when the swinging motion turns at its extreme position. Good dampening is achieved also with a setting slightly deviating from this phase, for example, in the range of 70-110 degrees, if the most preferred position is designated as a 90 degree phase lag. In theory, a slight dampening is always achieved when the phase lag is in the range of 0-180 degrees. The amount of dampening can thus be adjusted. Fig. 2 shows an arrangement for actively adjusting the position of the mass 5. An electric machine 7 always rotating in the same direction can be used with control as a motor or a generator. While functioning as a motor, the electric machine 7 boosts the revolving motion of the mass 5 around a vertical axis 4 and, while functioning as a generator, it brakes the revolving motion, wherein the device produces electric energy. The energy produced by braking is stored via the converter 8 into an elec- trie battery 9 on the vessel, which energy is used to boost the rotation of the mass 5. The stored electric energy can also be used to rotate a flywheel, i.e. a gyroscope, if such is arranged in connection with the mass 5. Extra electricity can also be used for other needs of the vessel. The converter is controlled by a control unit 10, which receives the control parameters from the location sensor 11 of the mass 5 and from the rolling degree sensor 12. If there is also a flywheel in connection with the mass 5, as a control parameter is also its speed of rotation, which is obtained from a speed sensor 13. By means of adjusting, the revolving motion of the mass 5 is preferably kept in the range of 70-110 degrees behind (phase lag) the lowest positions of the mass corresponding to the extreme positions of the rolling motion. Fig. 4 shows a phase lag of 90 degrees, which is most preferable both for dampening and for energy production. During one revolution of the mass, energy is produced by braking the rotation- al motion preferably two different times and, if required, energy is consumed by boosting the rotational motion preferably two different times in alternating turns with the braking. By the sensor 12 contained in the device, the rolling degree of the vessel is monitored and, by the adjustment devices 8-11, the periods of braking and boosting the rotation are synchronized to pre-defined points of the inclination of the vessel, the locations of which are dependent on the rolling degree. In this manner, the ratio of dampening and energy production can be optimized according to conditions and need.

Energy is typically consumed in the range of 0-30% as compared to the energy produced. If there is a desire to optimize the device also for the production of electricity, the revolving speed of the mass 5 can be allowed to vary suitably during one revolution in order that, along with adequate dampening, the net production of electricity is maximized. Using only the mass 5, energy production is pulsating. This can be evened out by using a flywheel in connection with the mass 5, by adjusting the spinning number of revolutions of which the energy production can be made nearly uniform. By increasing the rotation speed of the flywheel, the dampening effect increases, although it does remain sinusoidally varying in rhythm with the rolling. In this case, the weight of the mass 5 can also be decreased. Without the flywheel, the weight of the mass 5 is less than 10% the weight of the vessel. With the flywheel, it may be less than 5% the weight of the vessel. Further, the energy of the flywheel can be used to boost the rotation of the rotator 4, 5 and the speed of the flywheel can be accelerated by the braking energy.

Fig. 3 shows a principal diagram of an embodiment having two overlapping rotators. Formed by the vertical axis 4 and the mass 5, the first rotator corresponds to that described above. This first rotator is bearing-mounted into the hull 20 of the vessel by bearings 18. In this arrangement, the stator 16 of the generator 17 rotates along with the vertical axis 4 and the mass 5. The mass 5 is thus connected via the axis 4 to the stator 16 of the generator 17. The mass 15 of the second rotator is connect- ed to the rotor 14 of the generator such that they rotate together around the vertical axis 4. The mass 15 and the rotor 14 of the generator are bearing-mounted with bearings 19 onto the vertical axis 4. Using this arrangement, twice the speed is achieved to the generator 17, consequently it becomes smaller, lighter and less expensive. As the disadvantages are a slightly more complicated structure, additional bearings and a slip ring 21, which connects the stator 16 of the generator 17 electrically to the converter. The masses 5 and 15 are arranged to rotate in opposite directions to each other, as is illustrated in Fig. 5. The masses thus overtake each other twice during the revolution and are on the opposite sides of the vertical axis pointing in opposite directions twice during the revolution. In principle, both masses thus function in the same manner, even though the directions of rotation are opposite.

The dampening can be substantially intensified by placing the plane of the revolution track of the centre of gravity of the mass by a substantial distance above the rolling axis of the vessel. This distance is at least ¹ A the height of the vessel, preferably at least 1/3 or even on top of the vessel, on the upper deck. In this case, the torque related to power production and the braking or acceleration forces directed onto the mass, which have an essential component in the transverse direction of the vessel, powerfully affect the rolling motion. The location of the mass in relation to the vertical plane 3 also affects dampening, but this affect is rather slight. The centrifugal force caused by the mass also affects the rolling of the vessel, having more effect the higher up the mass is in relation to the rolling axis. Further, dampening is affected by the fact that the plane of the revolution track of the centre of gravity of the mass attempts to retain its direction (gyroscopic effect).