JPS621106B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for converting wave energy.
More specifically, by keeping the rotation period of the eccentric rotating body and the oscillation period of the floating body on which the rotating body is mounted, which is rocked by the waves, in a state of resonance or close to resonance, wave energy can be efficiently transferred to the eccentric rotating body. Concerning how to convert into kinetic energy.

Various types of energy conversion methods are known for converting wave energy into electric power for wave power generation. For example, when a floating body moves up and down due to wave force, the speed difference between the floating body and the surrounding water causes a propeller attached to the bottom of the floating body to rotate, and in a wave power generation engine that drives a generator, the conversion efficiency of wave energy is In order to increase this, a method has been disclosed in which the vertical motion period of the floating body and waves are synchronized (Japanese Patent Laid-Open No. 51-86639). However, this method requires, in addition to the above-mentioned buoyancy adjustment device for adjusting the vertical movement period, a device that extracts smoother rotation in one direction than the forward and reverse water flow that occurs every wave period, and a There are many problems, such as countermeasures to reduce efficiency due to corrosion of moving parts and adhesion of aquatic organisms.

As a result of intensive research in order to solve the above-mentioned problems, the present inventor has solved the above-mentioned problems by converting the rocking motion of a floating body caused by waves into rotational kinetic energy of an eccentric rotating body in a generator installed inside the floating body. The present invention was developed based on the knowledge that this problem could be solved. That is, an object of the present invention is to provide a wave energy conversion method using a floating body, which does not have a buoyancy adjustment device or a moving part in the water, and extracts rotational energy related to rotation in one direction that is smoother than wave motion. The purpose of the present invention is to provide a wave energy conversion method that allows for

The present invention is a method for converting wave energy according to the following items (1) and (2).

(1) Consisting of a floating body installed on the water surface or in the water that is rocked by waves, a generator having an eccentric rotating body installed inside the floating body, and a transmission mechanism connected to the eccentric rotating body in the generator through a rotating shaft. Wave energy received by the floating body, characterized in that the rotation period of the eccentric rotating body is kept at resonance or close to resonance with the oscillation period of the floating body by using a device and adjusting the energy taken out from the device to the outside. A method of converting wave energy into rotational kinetic energy of an eccentric rotating body.

(2) By rotating a pair of eccentric rotating bodies in opposite directions and creating an arbitrary and constant phase difference in the rotation, the horizontal and vertical components of the rocking energy of the floating body are adjusted to the phase difference. The wave energy conversion method according to item (1) above, wherein the wave energy conversion method converts into rotational kinetic energy of the eccentric rotating body at a proportion according to the ratio.

The configuration and effects of the present invention will be explained in detail below with reference to the drawings. FIG. 1 is an explanatory cross-sectional view of the eccentric rotating body according to the present invention in a direction perpendicular to the rotation axis. In the figure, the weight of the eccentric rotating body is W, the distance from the rotation axis O to the center of gravity D is d, and when the eccentric rotating body rotates around O at a uniform angular velocity p, a force equivalent to centrifugal force, F=(W/g)p ² d acts as an excitation force via the bearing (g is the acceleration of gravity). Assuming that the two mutually orthogonal directions perpendicular to the axis of rotation are X and Y, the Y-direction component of the excitation force is expressed as Fy=(W/g)p ² d cos pt (1) (Note: Time When t=O, the center of gravity is Y
on the shaft and rotating counterclockwise).

Now, the entire system including the eccentric rotating body is assumed to perform reciprocating motion parallel to the Y-axis with an amplitude of 2A centered around the rotation axis O, and the amount of movement y is expressed as y=Asin(ωt+α) (2) (where ω is the angular frequency of simple harmonic vibration and α is its initial phase). Here, when the rotation of the eccentric rotor and the reciprocating motion resonate, p=ω and α=O, and the energy U received by the eccentric rotor from this reciprocating motion is calculated as follows.

The work dU done while the system including the eccentric rotating body moves by a minute distance dy in a resonant state is dU=F・dy=(W/g)dp ²・cospt・dy (3) On the other hand, dy=(dy /dt)・dt, dy/dt＝Ap・cospt
Therefore, dU=(W/g)dp ³ A・cos ² pt・dt (4) Therefore, the work U′ done during a half period is U′=∫ ^A _−A F・dy=∫〓 ^/P _D (W/g)dp ³ A・cos ² pt・dt=(W/g)dp ³ A [(t/2) + (1/4p)・sin2pt]〓 ^/p _D = (W/2g)dp ² Aπ The work done per unit time U is expressed as U=(W/2g)dp ³ A (5), which is equal to the energy received by the eccentric rotating body in a resonant state.

Now, since the motion of waves propagating in the deep ocean, where the depth is more than 1/2 of the wavelength, is approximated to a sine wave, the vertical motion of a floating body in the deep ocean can also be considered to be a simple harmonic motion of a sine wave. If the rotation of the eccentric rotating body is controlled so that it resonates with the vertical motion of the floating body on which it is mounted, the rotating body will receive energy corresponding to equation (5) above, and this energy will be transferred to the rotating body. It can be taken out regularly from the rotating shaft. In this case, the energy received by the eccentric rotating body decreases depending on the degree to which it deviates from the resonance state. If such a reduction in the energy conversion rate is allowed, it is not necessarily necessary to achieve or maintain a resonant state in the strict sense, and there is no practical problem as long as a state close to resonance is maintained.

The invention will be further illustrated by the following embodiment examples. FIG. 2 is a cross-sectional view of a floating body E on which a wave energy conversion device according to the present invention is mounted, and FIG. 3 is a longitudinal cross-sectional view thereof. In Fig. 2, a pair of eccentric rotating bodies G and G' are installed symmetrically about the center line in the long axis direction of the floating body E, and the rotation axes H and H' are located parallel and horizontal to the long axis direction of the floating body E. . Eccentric rotating body G,
Excitation force when G' rotates at a constant speed in opposite directions while maintaining a symmetrical position with respect to the center line of floating body E
From equation (1), F' is F'=2(W/g)dp ²・cospt, and its point of action is at the center of the two axes H and H', and the direction of the force is on the plane created by HH'. Vertical.

The vertical motion of the floating body E is expressed by equation (2), and if this motion resonates with the motion of the eccentric rotating bodies G, G' whose weights are W, then the eccentric rotating bodies G, G' per unit time The energy received by is given by U=(W/g)dAp ³ , similar to equations (3), (4) and (5). Now, the weights (W) of the eccentric rotating bodies G and G' are 63T/m and d, respectively, per the length of the rotating shaft.
= 3.2m, the motion of floating body E is A = 2.5m, p =
If it is 0.785rad (period approximately 8 seconds), the rotation axis H,
This means that 24KW of energy can be extracted per meter in the direction of H'.

In FIG. 3, the eccentric rotating bodies G and G' are started in advance by a starting motor L at a rotation period close to the oscillation period of the floating body E and resonance. The energy given to the eccentric rotating bodies G, G' by the vertical movement of the floating body E is transferred from the rotating shafts H, H' to the generator N via the speed increaser M.
After being converted to AC power, the AC power is converted to DC power by an AC/DC converter Q, and then sent out through a cable R. By controlling the DC output of the AC/DC converter Q, the load on the generator N is increased or decreased, and the rotation periods of the eccentric rotors G and G' are thereby controlled.

In other words, the output of the AC/DC converter detects the amplitude, period, and phase of the oscillation of the floating body as well as the rotation period and phase of the eccentric rotating body, and detects whether the rotation period of the eccentric rotating body tends to be faster than the oscillating period of the floating body. If the converter tends to become slower, the output is increased, and if the converter tends to become slower, the output is decreased (in some cases by applying external energy). In this way, the rotation period of the eccentric rotating body is always maintained at or near resonance with the oscillation period of the floating body due to the period number pull-in phenomenon in the nonlinear self-excited system.

The rotation period and phase of the eccentric rotating body are detected, for example, by providing tachometers on the rotating shafts H and H'. The amplitude, period, and phase of the rocking of a floating body can be determined, for example, from the measured values of the position meter, speedometer, accelerometer, water level gauge, water pressure gauge, etc. installed on the floating body in ○a, and determined in ○b or ○a above. It is predicted by extrapolating the determined value to the time axis, or it is calculated from the wave period and wave height values detected by a wave meter etc. installed separately from the floating body. According to method ○a, the output control is a feedback method,
According to methods ○B and ○C, it is possible to adopt a feed-forward method.

Some embodiments of the present invention are shown below.

(a) In Fig. 3, an AC/DC converter Q is not provided, but a continuously variable transmission is installed between a speed increaser M and an AC generator N, and the generator is operated at a constant rotation speed and eccentrically In this method, the speed of the rotating body is controlled via the above-mentioned continuously variable transmission.

(b) In Fig. 3, a method in which the AC/DC converter Q is not provided, the generator N is a DC generator, and the speed of the eccentric rotating body is controlled by the output control of the DC generator.

(c) In Figure 3, generator N, AC/DC converter Q,
Without providing any cable R, the output of the generator K is guided to a suitable mechanical system such as a flywheel via a speed increaser M and a continuously variable transmission, and is extracted as kinetic energy, thereby increasing the speed and output of the eccentric rotating body. control is performed via the continuously variable transmission.

(d) By giving an arbitrary and constant phase difference to the rotation of the eccentric rotating bodies G and G' and giving a horizontal component to the excitation force, the horizontal movement energy of the floating body E is also absorbed. (See Figure 4).

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the rotation of the eccentric rotating body and the excitation force.
FIG. 2 is a cross-sectional view of a floating body on which a wave energy conversion device is mounted, FIG. 3 is a vertical cross-sectional view of the floating body, and FIG. 4 is an explanatory diagram of the phase of the eccentric rotating body and the direction of the excitation force. In these drawings, each symbol is W: weight of the eccentric rotating body, D: center of gravity of the eccentric rotating body, O: axis of rotation, d: distance between the center of gravity and the axis of rotation, p: angular velocity, g;
Acceleration of gravity, E; Floating body, G and G'; Eccentric rotating body, H and H'; Axis of rotation, K; Generator, L;
Starting motor, N: generator, Q: AC/DC converter,
R: cable, S: direction of excitation force.

Claims (1)

[Claims] 1. A generator having a floating body disposed on the water surface or in the water and rocked by waves, an eccentric rotating body installed inside the floating body, and a generator connected to the eccentric rotating body in the generator through a rotating shaft. The floating body is characterized in that the rotation of the eccentric rotating body is maintained at or near resonance with the rocking motion of the floating body by using a device consisting of a transmission mechanism and adjusting the energy taken out from the device to the outside. A wave energy conversion method that converts received wave energy into rotational kinetic energy of an eccentric rotating body. 2. By rotating a pair of eccentric rotating bodies in opposite directions and giving an arbitrary and constant phase difference to the rotation, the horizontal and vertical components of the rocking energy of the floating body can be adjusted according to the phase difference. 2. The method of converting wave energy according to claim 1, wherein the wave energy is converted into rotational kinetic energy of the eccentric rotating body at a ratio of 1 to 3.