JPH07251793A - Damped tank - Google Patents

Abstract

PURPOSE:To enhance a damping effect by regulating the pressure of each air chamber, and thus holding constant the natural frequency of a U-shaped communicating tank main body regardless of the inclination of a structure to be damped. CONSTITUTION:The required air is supplied to air chambers 5a, 5b from an air source 12 via an air pressure regulating valve 10 and a pressurized air pipe 11. A structure 9 to be damped is fitted with an inclinometer 15, and an inclination angle detected by the inclinometer 15 is inputted to a computing unit 14, and a valve operating device 13 controls the regulating valve 10 according to the computed signals. In a damped tank 1, its inclination angle is detected by the inclinometer 15 and its pressure is calculated by the computing unit 14 and can be set to the required value by control of the air pressure regulating valve 10, and so the natural frequency of the tank can be held constant regardless of the inclination angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping tank which is applied to damping the horizontal vibration of a living space structure of a ship or a propulsion engine.

[0002]

2. Description of the Related Art Conventionally, as a vibration control tank for a ship, the vibration control tank shown in FIG.
As shown in the perspective view and the vertical cross-sectional view of FIG. 7, in the U-shaped tank, air chambers 5 are provided in the upper portions of the left and right vertical tanks, respectively, and pressurized air is sealed therein through a pressure air pipe 11 and a valve 10. . The vibration damping tank 1 is a fluid dynamic vibration absorber composed of the mass of the internal fluid 6 and the spring of the air in the air chamber 5, and its vibration frequency is, as shown in FIG. 5, the height H of the air chamber 5. And the pressure p of the air chamber 5 can be adjusted.
However, if the horizontal plane changes, the pressure p in the air chamber 5
Even if is constant, the natural frequency of the damping tank 1 changes.

[0003]

SUMMARY OF THE INVENTION The present invention has been proposed in view of such circumstances, and keeps the natural frequency constant even when the object to be damped to which the damping tank is attached tilts. The purpose of the present invention is to provide a high-performance damping tank that enhances the damping effect.

[0004]

To this end, according to the present invention, an air chamber is provided above each of a pair of left and right vertical tank portions, and the lower portions of both vertical tank portions are connected by a fluid-filled communication portion. In the U-shaped communication tank on the vertical vertical plane, by adjusting the pressure of the air chamber according to the inclination angle within the vertical vertical plane of the structure to be damped, which mounts the U-shaped communication tank body, Despite the inclination of the structure to be damped, the above U
It is characterized in that the natural frequency of the character-shaped communication tank body is kept constant.

[0005]

According to this structure, the inclination angle of the structure to be damped is detected in the U-shaped communication tank, the calculation is performed by this detection signal, and the correction amount of the pressure in the air chamber is calculated.
Based on this, the air pressure in both air chambers of the U-shaped damping tank can be changed to maintain the natural frequency of the damping tank at a constant value.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to the damping of a ship will be described with reference to the drawings. FIG. 1 is a perspective view thereof, and FIG.
1 is a vertical cross-sectional view, FIG. 3 is a horizontal cross-sectional view of FIG. 1, and FIG. 4 is a tilt angle θ when the damping tank of FIG. 1 is applied to damping pitching.
Fig. 5 shows the relationship between the vibration frequency and the natural frequency of the vibration suppressor.
FIG. 6 is a diagram showing the relationship between the pitching inclination angle φ and the natural frequency of the vibration damper when the vibration damping tank of FIG.

First, in FIGS. 1 to 3, the vibration damping tank 1 is composed of left and right vertical tanks 2a and 2b and a horizontal tank 3 which communicates the lower portions of both tanks. Further, the left and right vertical tanks 2a and 2b have air chambers 5a and 5b at their upper portions, and the other portions are filled with the fluid 6. Also, the air chamber 5
The required air is supplied to the a and 5b from the air source 12 via the air pressure adjusting valve 10 and the pressure air pipe 11, as shown in FIG.
The structure is the same as that of the conventional damping tank shown in FIG.
Although the air pressure adjusting valve 10 is a three-way valve, it is also possible to employ a supply pressure adjusting valve 10a and an exhaust pressure adjusting valve 10b instead.

In the device of the present invention, the inclinometer 15 is provided in the structure 9 to be damped, the inclination angle detected by the inclinometer 15 is input to the arithmetic unit 14, and the valve operating unit 13 is operated by the arithmetic signal. The adjusting valve 10 is operated.

Now, if this damping tank 1 is applied to the damping of rolling of a ship, the damping tank 1 is mounted on the hull so that its left and right direction is aligned with the left and right direction of the hull. Then, θ in FIG. 2 indicates the rolling angle. Here, when the left and right vertical tanks 2a and 2b are in the upright state, the natural circular frequency ω ₀ as a horizontal damping tank shown by the arrow in FIG. It can be represented by 1). ω ₀ = √ {2 [G + (k / ρ) ・ (p / H)] / [2l + (a / A) L]} (1) where H and P = air chambers 5a and 5b Height and pressure k = Specific heat ratio of air ρ = Density of liquid 6 G = Gravitational acceleration a, l = Water line area and water level of vertical tanks 2a, 2b A, L = Cross-sectional area and length of horizontal tank 3 Since G << (k / ρ) ・ (p / H) in the frequency range such as the structure of the living space of the ship and the horizontal vibration of the propulsion engine, equation (1) should be rewritten as equation (2). You can ω ₀ = √ {2 [(k / ρ) ・ (p / H)] / [2l + (a / A) L]} ・ ・ ・ (2)

Now, consider the case where the vibration damping tank of the U-shaped communication tank system is tilted from the upright state. First, as shown in FIG. 2, when the water surface 4a is inclined in the in-plane direction of the U-shape by the rolling angle θ (water surface 7a), the natural frequency is as shown in equation (3), It changes from the natural frequency of the upright state given by (2). ω ₁ = √ {[(k / ρ) pH · (H ₁ ² + H ₂ ² ) / (H ₁ ² · H ₂ ² )] / [2l + (a / A) L · sec θ]} ・ ・ ・ ・ ( 3) Here, H ₁ = H−ΔH H ₂ = H + ΔH (4) ΔH = (L / 2) sin θ (4) Therefore, the natural vibration when tilted by θ In order to match the number ω ₁ with the natural frequency ω ₀ in the upright state, equation (3)
The pressure p in ₁ may be corrected to the pressure p ₁ given by the equation (5). p ₁ = {2p ・ (1 / H ² ) ・ (H ₁ ²・ H ₂ ² ) / (H ₁ ² + H ₂ ² )} × {[2l + (a / A) L ・ sec θ] / [2l (a / A) L]} (5) That is, in the damping tank 1 according to the present invention, the rolling angle θ is detected, and the arithmetic unit 14 calculates the pressure p ₁ using the equation 5 to adjust the air pressure. By manipulating the valve 10 to make p in equation (3) equal to p ₁ , the natural frequency ω ₀ can be held constant regardless of the rolling angle θ, as shown in FIG.

Next, as shown in FIG. 3, when the hull is tilted by φ in the out-of-plane direction of the U-shaped communication tank, that is, in the front-rear direction (waterline surface 8), the natural frequency is expressed by equation (6). become that way. ω ₂ = √ {[2 {k / ρ) ・ (p / H)] / [2l ＋ (a / A) L ・ sec φ]} (6) Therefore, the natural vibration when tilted by φ In order to match the number ω ₂ with the natural frequency ω ₂ in the upright state, the pressure p in the equation (6) is given by the pressure p ₂ given by the equation (7).
It should be corrected to. p ₂ = [2l + (a / A) L · sec φ] / [2l + (a / A) L] (7) That is, in the vibration damping tank 1 according to the present invention, the tilt angle is measured by the inclinometer 15. After detecting φ and calculating the pressure p ₂ using the equation (7) by the arithmetic unit 14, the air pressure adjusting valve 10 can be operated to set the required pressure, so that the inclination angle φ is set as shown in FIG. The natural frequency ω ₀ can be kept constant regardless of the relationship.

When the vibration damping tank is applied to pitching vibration damping, a U-shaped vibration damping tank is mounted on the hull so that the direction of the lateral tank matches the longitudinal direction of the hull.
Considering that angle θ as the pitching angle in this case

The pitching can be suppressed in the substantially same manner as described in the above. In order to suppress both rolling and pitching, it is necessary to mount two damping tanks of the present invention on the hull.

[0013]

As described above, the damping tank of the present invention exhibits the damping effect of the damping tank because the natural frequency of the damping tank does not change despite the rolling and pitching of the hull. Therefore, the reliability can be significantly increased. The present invention is applicable not only to ships but also to bridges,
It can also be widely applied to the damping of land structures such as observation towers.

In short, according to the present invention, a pair of left and right vertical tanks each have an air chamber at the upper part thereof, and the lower parts of both vertical tanks are connected by a fluid-filled communication part on a vertical vertical plane. In the U-shaped communication tank, the structure of the vibration-damping target is adjusted by adjusting the pressure of the air chamber according to the inclination angle in the vertical vertical plane of the structure of the vibration-damping target equipped with the U-shaped communication tank body. By keeping the natural frequency of the U-shaped communication tank body constant despite the inclination of the object, even when the vibration suppression target object to which the vibration suppression tank is attached tilts,
The present invention is extremely useful industrially because a high-performance damping tank is obtained which enhances the damping effect by keeping the natural frequency constant.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a damping tank showing an embodiment in which the present invention is applied to damping rolling of a ship.

FIG. 2 is a vertical sectional view of FIG.

3 is a cross-sectional view of FIG.

FIG. 4 is a cross-sectional view of the rolling of the present invention.

FIG. 5 is a diagram showing a damping effect on pitching according to the present invention.

FIG. 6 is an overall perspective view showing a conventional damping tank for a ship.

7 is a vertical cross-sectional view of FIG.

[Explanation of symbols]

 1 Damping tank 2, 2a, 2b Vertical tank 3 Horizontal tank 4a Water line surface when standing upright 5a Air chamber 6 Fluid 7a Water line surface when tilting 8 Water line surface when tilting 9 Hull 10 Air pressure control valve 10a Supply Air pressure adjusting valve 10b Exhaust pressure adjusting valve 11 Pressure air pipe 12 Air source 13 Valve operating device 14 Computing device 15 Inclinometer θ Rolling angle φ Pitching angle

Claims (1)

[Claims] 1. A U-shaped communication on a vertical vertical plane in which air chambers are provided above the pair of left and right vertical tank parts, and the lower parts of both vertical tank parts are connected by communication parts filled with fluid. In the tank, the pressure of the air chamber is adjusted according to the inclination angle in the vertical vertical plane of the structure to be damped which mounts the U-shaped communication tank body, so that the structure to be damped Despite this, a vibration damping tank characterized in that the natural frequency of the U-shaped communication tank body is kept constant.