JPH0649299U - Higher-order vibration suppression device for hull - Google Patents

Abstract

(57) [Summary] [Purpose] To effectively and inexpensively suppress higher-order vibrations that occur in ships such as ferries and passenger ships. [Structure] In the vicinity of a high-order vibration generator such as the main machine 7a or 7b, a fixed vibration absorbing material such as a granular vibration proof material typified by sand is filled in an appropriate place inside the fixed double bottom 2. A high-order vibration suppressing device for a hull, which is provided with a compartment 8 in which an object is filled.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a high-order vibration suppressing device used for attenuating high-order vibrations of a hull caused by vibration generators such as a main engine.

[0002]

[Prior art]

 High-order vibration of the hull caused by diesel engines, especially noise problems such as ferry, have been cloved up for several years, and the following measures have been taken to solve them.

That is, when concrete is put in a space directly below the installation base of the diesel engine to solidify it, or when the diesel engine is fixed to the installation base, a rubber is interposed between the two to remove the diesel engine from the diesel engine. It is designed to block the vibration propagation to the hull.

[0004]

[Problems to be solved by the device]

 The concrete solution mentioned above has problems such as the hull maintenance is not possible and the sufficient effect cannot be obtained, and the cost of using rubber is high. The reality is that there does not exist. It is an object of the present invention to provide a high-order vibration damping device for a hull that eliminates such a situation.

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, in the present invention, a damping material such as granular vibration damping material typified by sand, etc. is placed in an appropriate place inside the fixed double bottom near the generator of high-order vibration such as the main engine. It is characterized in that a compartment filled with excellent filling material is provided.

[0006]

[Function] Since the filling material filled in the compartment changes the fundamental frequency of bending vibration of the plate at the bottom of the double bottom, it vibrates itself and attenuates vibration energy due to friction between particles or viscous resistance of liquid. Yes, it effectively acts as a blocking mass against vibrations.

[0007]

【Example】

 FIG. 1 is a cross-sectional view of an engine room of a ferry embodying the present invention, in which 1 is an outer plate and 2 is a double bottom portion. The double bottom portion 2 is formed by connecting the outer bottom plate 1a and the inner bottom plate 3 to each other by an engine girder 4 in the front-rear direction and a floor plate 5 in the lateral direction. Further, the diesel engines 7a and 7b, which are the main machines, are fixed on the inner bottom plate 3 by way of a mounting table 6.

[0008] Therefore, a closed compartment 8 in which a filler such as sand is filled is formed inside the double bottom 2 at a proper place near the main machines 7a and 7b. Specifically, a closed space is formed at a position on the outside of the girders 4 ··· at appropriate intervals in the vertical direction, and an openable and closable manhole is formed on the side wall of the space. Form an openable and closable manhole used for supplying sand, etc. In this case, the positions of the compartments 8 ... Are set at a place where the vibration generated by the main machines 7a and 7b is largely propagated, for example, a place where the special frame 9 and pillars are present. Further, the amount of the filler to be filled in the compartment 8 can most effectively suppress the hull vibration in relation to the frequency of the vibration to be damped and the fundamental frequency of the bending vibration of the double bottom plate. I shall.

In the figure, 10 is a large stiffener, 11 is a special beam, 12 is a deck, 13 is an upper deck, and WL is a water level.

Next, the operation of the above embodiment will be described. Due to the rotation of the main engines 7a and 7b, a vibration with a peak at a certain frequency (for example, about 250 Hz) is generated, and this vibration is transmitted to each part of the hull through the compartments 8 filled with sand etc. Propagated. If the fundamental frequency of the bending vibration of the plate at the bottom of the hull double bottom is, for example, about 250 Hz, if no measures are taken, the vibrations generated by the main engines 7a and 7b resonate with the double bottom of the hull and produce a loud hum Will occur. However, since there is a filler such as sand in the compartments 8 ..., the fundamental frequency of the filler changes, and the above resonance does not occur. The vibrations generated by the main machines 7a, 7b also vibrate the sand, which is the filler in the compartments 8 ..., But the energy is effective due to the frictional resistance and viscous resistance between the particles. Is attenuated to. Thus, the filling material in the compartments 8 ... acts as a blocking mass against vibrations, so that the vibration propagation from the main engines 7a, 7b to the hull is effectively blocked and the hull vibrations are prevented. As the speed level is reduced, the noise level is also reduced.

The following is an experimental example. Experiments were carried out on ferries of 8,000 ton gross tonnage stern engine type (single main engine uniaxial ship). In the case of this class of ferries, the frequency at which it easily resonates in the double bottom is 250-350 Hz. As shown in Fig. 2 and Fig. 3, this ship is equipped with a speed reducer R / G to reduce the speed of the main engine M / E and transmit it to the propeller shaft. Is 50% Load-M. C. O. At 252 to 318 Hz. Further, the speed reducer R / G is fixed on the double bottom 2, and a cofferdam C / D indicated by a diagonal line in FIG. 2 is formed on both sides of the device. In this experiment, this Cough Adam C / D was made into compartments 8 and 8 into which the filler was filled, and sand s was supplied therein. As a result, in the normal operation of the main engine M / E, the vibration near 250 Hz, which showed the highest peak at the three inner bottom plates near the reduction gear R / G, was reduced by 10 dB or more, and the noise level was reduced. It decreased by about 7 dB (A). Regarding the vibration velocity level of the upper wall surface near the reduction gear R / G at this time, the vibration at the peak of 250 Hz was reduced by 6 to 9 dB.

[0012]

[Effect of device]

 According to the present invention described above, the following effects can be obtained. That is, 1) Filling material such as sand in the compartment formed in the double bottom near the vibration generator acts as a blocking mass for vibration, and the energy of high-order vibration by the main engine is attenuated as friction energy. Therefore, higher-order vibration can be effectively prevented at low cost. 2) As a measure against higher-order vibration of the main engine, increasing the plate thickness of the hull member is one of the methods to increase the panel rigidity of the hull. Since the compartments that are put in are provided, the higher-order vibrations at the double bottom can be damped faster, so the thickness of the thickened part of the entire ship can be made lower than before, making it light and quiet. It can be a ship. 3) Ferries and passenger ships generally struggle to ensure stability, but sand etc. filled in the compartment formed in the double bottom acts as a fixed ballast, contributing to increased stability. Will be things. 4) Since the compartments inside the double bottom are filled with sand, etc., the basic frequency of bending vibration of the plate at the bottom of the double bottom can be appropriately changed and adjusted by a simple process of changing the amount of sand etc. Therefore, the vibration can be effectively prevented.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an engine room of a ferry embodying the present invention.

FIG. 2 is a plan view showing a double bottom portion of an engine room of a ferry used in an experiment of the present invention.

FIG. 3 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 2 Double bottoms 7a and 7b Main engine (vibration generator) 8 sections R / G reducer (vibration generator) s sand

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[Procedure amendment]

[Submission date] September 13, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (1)

[Scope of utility model registration request] 1. A filler having excellent damping properties, such as a granular vibration-damping material typified by sand, etc., in an appropriate place inside a fixed double bottom near a generator of high-order vibration such as a main engine. A high-order vibration suppressing device for a hull, characterized by having a compartment filled with the.