JPH0415184A - Device for damping oscillation of spar buoy - Google Patents

Abstract

PURPOSE:To restrain oscillation of a spar buoy by means of the oscillation resistance of a resisting plate by axially supporting the resisting plate to a product fixed on the bottom of the sea, e.g. a sinker in such a manner as allowing the plate to freely oscillate, and connecting the spar buoy to then resisting plate via a connecting rod. CONSTITUTION:A column body 1 having the floating body 5 of a spar buoy provided in its middle portion is moored at its lower end to a sinker 4 at a 01 point and a connecting piece 3 is connected at one end to the supporting point 04 of a support piece 1' provided in the lower portion of the column body 1 and at the other end to the supporting point 03 of a resisting plate 2 axially supported to the sinker 4 at a supporting point 02. Oscillation of the spar buoy is amplified by the connecting piece 3 at some amplification factor and transmitted to the resisting plate 2 and is damped by the oscillation resistance of the resisting plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a sway reduction device for a super buoy used in relatively shallow waters.

(b) Conventional technology A buoyant body is provided in the middle of a column, the lower end of the column is moored to a sinker on the water bottom using a mooring device or a mooring mechanism, and the buoyant body is pulled into the water, so that the water line is above the buoyant body. Make sure it is in the middle of the column,
The retractable mooring type super buoy, which stands upright in the water using buoyancy, has a short protrusion distance and little oscillation, so it can be easily used in the navigation route e.
It is used for lm etc.

(A) Problem to be solved by the invention The super buoy has a natural period of vibration centered on the mooring point.
The deeper the water depth, the larger the
m, the natural period is 13 to 15 seconds, and at a depth of 30 m, the natural period is about 15 to 2.
0 seconds, which is outside the resonance range of the wave period of 8 seconds to 12 seconds, which is the design condition, so the oscillation is small. However, as the water depth becomes shallower, the natural period of the super buoy becomes smaller, so it enters the resonance region and the oscillation increases. To prevent this, a resistance plate or the like may be provided at a position away from the axis of rotation of the oscillation of the super buoy, that is, near the water surface, to increase the oscillation resistance and increase the damping force. Figure 1 shows the relationship between the wave period and the swing angle in each case where the damping force is changed in the super buoy, where t: force - bu. However, installing a resistance plate near the water surface to increase the resistance force will cause it to tilt due to water currents and waves, and the problem of super buoys in shallow water is a"4.b=2 c=5 d= The title was the size ratio of 5.

(d)! Means for Solving Problem I The present invention provides a resistance plate rotatably supported on a structure fixed to the bottom of the water, such as a sinker, and a connecting rod or cable connected to a spar buoy at one end and to the resistance plate at the other end. This is a super buoy vibration reduction device that transmits the vibration of the super buoy to the resistance plate and reduces the vibration of the super buoy by the vibration resistance of the resistance plate.

Figure 2 is an example of this, showing a state in which the column (1) is tilted by θ due to oscillation. One end of the connecting piece (3) is connected to the support point 04 of the support piece (1") provided at the bottom, and the other end is supported pivotally on the sinker (4) at the support point 02 of the resistance plate (2). 0
It is connected to 3. As shown in Figure 3, a + b r c
.

d, and Φ, V, V “, v”, then V;
◆ If, for example, the following occurs: Therefore, as can be seen from the values of θ and /θb (amplification factor) in the table above, in this case, the swing angle of the buoy is amplified approximately three times by the resistance plate (2).

As mentioned above, the resistance plate is near the bottom of the water, and the super buoy is upright! l (see Figure 144), the resistor plate is in a nearly horizontal position. Furthermore, the movement of water particles due to waves is an elliptical movement close to a circle near the water surface, as shown in FIG. 5, and becomes an elliptical movement with a flat and small diameter as it approaches the bottom of the water. In a water flow such as the Zarani S flow, the flow velocity becomes slower as it approaches the bottom of the water.

(f) Function With the above configuration, the vibration of the super buoy is amplified by a certain amplification factor by the connecting rod or connecting rope and transmitted to the resistance plate. Near the bottom of the water where the resistance plate is located, as mentioned above, the movement of water particles due to waves is small, and the vertical movement of the resistance plate easily catches water, resulting in a large dynamic resistance and a large damping force. In addition, the water flow is small near the bottom of the water, so the water flow resistance due to the resistance plate is small, and since the resistance plate is roughly far from the water surface, the agitation of the super buoy is hardly increased by the resistance plate.

In the end, even if a '14 rocking device is added, the inclination caused by the 'S flow and waves is small, and the super buoy's m rocking device has a large rocking reduction effect.

(f) Example 6th FM is a super buoy that implements an example of the present invention with 2 points.
14II indicates a state where it is tilted due to waves, etc., and the resistance plate (2) oscillates up and down with the horizontal position as the center and the 02 point as the axis. The amplification factor of the oscillation can be appropriately determined by appropriately setting each dimension of a, b, c, and d in FIG.

7S is a parent view taken along the line A-A in FIG. 6, and is a plan view showing the arrangement of the resistance plate (2). The resistance plate (2) of this example has a flat part (2
It consists of a rod Ml+2") and a shaft support (2'").

In this example, four resistive plates (2) are shown centered around the O3 point, but it is of course possible to arrange a plurality of resistive plates (611.8).

Fig. 8 shows another embodiment in which the connecting member is a cable, and (3°) is a connecting cable that connects the floating body (5) of the super buoy and the resistance plate (2). In this case, one pair of left and right resistance plates is completely destroyed! When the spar buoy tilts and the cable moves to the tension side, the resistance plate exhibits the S-sway effect of oscillation, and on the side where the cable loosens, the resistance plate acts as if by its own weight or by the biasing force of a spring (not shown). Descend. Therefore, although the operating portion is reduced by half compared to FIG. 6, a sufficient vibration reduction effect can be obtained by increasing the area of the resistance plate or by providing a sufficient number of fulcrum arms.

(G) Effects of the Invention As described above, the super buoy swing reduction device of the present invention can be used near the bottom of the water where there is little movement of water particles due to waves, and near the bottom of the water where the water flow is small even if there is a tidal current. It is located near the mooring ring of the sinker, which is the support point, and the vibration amplification factor of the resistance plate increases, so the damping force by the resistance plate is large, and there is almost no increase in the slope of the super buoy due to the installation of the resistance plate, making it an excellent The object of the present invention is to provide a swing reduction device for a super buoy that does not resonate with the wave period even in shallow water and has less vibration.

[Brief explanation of drawings]

Figure 1 is a oscillation angle-wave period curve diagram showing the resonance state depending on the magnitude of the damping coefficient near the natural period of the super buoy, 112! !
ff is an explanatory diagram showing one embodiment of the present invention in which the super buoy is tilted by eb degree, No. 31! l is an explanatory diagram of the dimensions and angles in the state shown in Figure 2, Figure 4 is an explanatory diagram of the super buoy in a stationary and upright state, Figure 5 is an explanatory diagram of the orbital movement of water particles due to waves, and Figure 6 is an explanatory diagram of the present invention. A conceptual diagram of the implemented super buoy, FIG. 7 is an AA parent diagram of FIG. 6, and FIG. 8 is a conceptual diagram showing another embodiment of the present invention. ] ...Column body, 2 ...Resistance plate, 3 ...
...Connecting rod, 3...Connecting cable, 4...Sinking weight. Patent Applicant Zenilite Buoy Co., Ltd. - L'f□ Concave 'Y+ t- Kuchitara Senichi ---------〇raguchi) L 〆:＞'-? σ - Namikawa period procedural correction sound 1. Display of the case 1990 Patent Application No. 120491 2, Name of the invention Super buoy vibration reduction device 3, Person making the amendment Relationship to the case Patent applicant Postal code 563 Location 176 Toshimaminami 2-chome, Ikeda City, Osaka Prefecture 1. FIGS. 6 and 8 of drawings subject to spontaneous correction. grace

Claims (1)

[Claims] A buoyant body is provided in the middle of the column, the lower end of the column is moored to a sinker on the bottom of the water using a mooring device, the buoyant body is drawn into the water, and the water line is located halfway above the buoyant body. This super buoy consists of a resistance plate rotatably supported on a sinker at the bottom of the water, and a connecting rod or cable connected to the spar buoy at one end and the resistance plate at the other end, and the swaying resistance of the resistance plate causes the spar buoy to A sway reduction device for a super buoy characterized by reducing the sway of the buoy.