JPS5830196B2 - Sway reduction method - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the invention of a rocking reduction method, which is applicable to a ship equipped with a passive rocking reduction water tank whose encounter period with waves is considerably different from the natural rocking period of the ship. The present invention is designed to appropriately prevent the adverse effect caused by the sway, achieve a desirable sway reduction function, and prevent the application of a tilting hydrostatic moment when the sway reduction effect is stopped.

2. Description of the Related Art It has been generally known for a long time that a passive rock-reducing water tank is installed in a ship to obtain a rock-reducing effect.

That is, such a passive type rolling reduction water tank exhibits a favorable rolling reduction effect when the ship equipped with it rolls at a wave encounter period close to the natural rolling period.

However, it is inevitable that the period of encounter with the waves described above is considerably different from the natural rolling period, and in such a case, the rocking reduction effect cannot be obtained, and on the contrary, the rolling motion is greater than if there was no rocking reduction tank. This is known to be a major drawback of conventional passive anti-sway tanks, and there have been some proposals for technical methods to overcome these drawbacks. It has disadvantages and drawbacks, such as poor operability and not necessarily being able to form a stable operating state, and an appropriate technique has not yet been obtained.

The present invention was devised after repeated studies in view of the above-mentioned circumstances, and the structure of the anti-sway water tank itself is as shown in FIG. At the same time, the upper part thereof is connected by an air duct 3, and this air duct 3 is provided with a valve and other air duct opening/closing mechanism 4. As an operating mechanism for opening/closing the air duct opening/closing mechanism 4, an air duct opening/closing mechanism as shown in FIG. A mechanism consisting of a judgment mechanism A and an air duct closing mechanism B is adopted.

That is, the air duct opening/closing judgment mechanism A is the autogyro 1.
1, the rolling waveform of the ship is sent to the digital counter 12, and the average rolling period Tw is determined by an electric circuit. T1. The arithmetic circuit 13 that determines the magnitude relationship with respect to T2 calculates whether T<Tw<T2 (or Tw<T1 or Tw>T2), and the signal from the arithmetic circuit 13 is sent to the signal separation and generator 1.
When T1 and Tw<T2, a valve opening start signal is sent from the signal mechanism 14a to the valve opening circuit 1.
5 to open the opening/closing mechanism 4 of the anti-swaying water tank and perform its function.

When it is Tw<T1 or Tw>T2, an air velocity meter measurement start signal is given to the air flow movement needle 16 to measure the air flow velocity in the air duct 3, and the measured value is sent to the differentiation circuit 17 and electrically The air flow acceleration α is calculated and the reference value α1. It is sent to the arithmetic circuit 18 that determines the magnitude relationship with respect to α2, and similarly to the arithmetic circuit 13, it determines whether α1 × α × α2, α × α1, or α>α2, and the result is The signal is sent to a signal separator and generator 19.

That is, the result obtained by this signal separation and generator 19 is the air flow acceleration near zero (-ε
~+ε) If α1, α, α2 indicates that the opening/closing mechanism 4 is closed, a valve closing start signal is given to the valve closing circuit 20 to close the opening/closing mechanism 4. Water is evenly distributed to the wing tanks 1 and 1a on the side, and no static heeling moment occurs.

Furthermore, if a mechanical time delay occurs in the closing mechanism, the timing of the valve closing signal can be adjusted in consideration of this time delay.

In this case, a measurement stop signal for the air velocity meter is sent to the air velocity meter 16 at the same time.

The operational relationship of the device according to the present invention as described above is as shown in FIG. Solid curve A-B+C when not operating
→D-E, and when the anti-sway water tank is in operation, the broken line curve F+B-+G→D-+H, but as shown in this figure, if the rolling period Tw is smaller than T1 or If it is larger than T2, the anti-sway water tank not only does not reduce the rolling motion but also increases it. However, in the present invention as described above, this disadvantage is eliminated and the curve A
It is possible to obtain a damping response close to +B→G+D+E.

According to the present invention as explained above, in a ship equipped with a rock-reducing water tank, when the period of the encountering waves is considerably different from the rocking cycle specific to the ship, the reverse effect is provided by the rock-reducing water tank. This can be effectively prevented by opening and closing valves in air ducts that are easily operated at favorable timings, and can also be prevented by opening and closing valves based on the judgment of whether the anti-sway water tank is activated or not, as described above. All of this is done automatically and does not require any manual effort, which eliminates the shortcomings of conventional anti-sway water tanks of this type at low cost.Furthermore, it is operated inside the air duct, which is easy to open and close, as described above. As a result, the air duct can be closed at a time when the airflow acceleration is close to zero, thereby accurately avoiding static side tilting and the risk of capsizing due to uneven water levels in both wing tanks. This invention has the following effects and has great industrial effects.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, and FIG. 1 is an explanatory diagram showing the general structural relationship of the anti-sway water tank to which the present invention is applied, and FIG. FIG. 3 is a diagram showing both the operational relationship according to the technology and the operational relationship according to the present invention, and FIG. 3 is a block diagram showing the mechanical configuration relationship for opening and closing the air duct of the anti-sway water tank according to the present invention. However, in these drawings, 1. Ia is the wing tank, 2 is the quarter duct, 3 is the air duct, 4 is the opening/closing mechanism, A is the air duct opening/closing judgment mechanism, and B is the air duct closing mechanism.
D→E indicates the characteristics according to the present invention.

Claims (1)

[Claims] 1. Detect the average value of the rocking period of the ship, and when the average value is within a predetermined period, open the air duct and operate the rock reduction water tank, and when the average value exceeds the predetermined period range, open the air duct. A vibration reduction method characterized by stopping the air circulation in the air duct and stopping the vibration reduction water tank function when the air flow acceleration is near zero.