JP3368564B2 - Hull structure to receive anti-vibration stay of main engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hull structure for receiving a vibration isolating stay of a main engine used for reducing lateral vibration of the main engine of a ship and vibration of the hull caused thereby.

[0002]

2. Description of the Related Art Conventionally, a hull structure for receiving an anti-vibration stay 2 of a main engine 1 is not always suitable for receiving the anti-vibration stay 2 of the main engine 1 on the hull side corresponding to the mounting position of the anti-vibration stay 2 on the main engine side, as shown in FIG. Since there is not necessarily a hull structural member, as shown in Fig. 2 (a), a pillar 7 is provided between the deck 4 and the double bottom 3 to receive a vibration-proof stay, or as shown in Fig. 2 (b). A method of providing a bracket 8 on an adjacent deck 4 to receive the vibration-proof stay 2 has been adopted.

The role of the vibration isolating stay of the main machine will be briefly described below.
When the resonance point of lateral vibration of the main engine such as shape vibration is expected to generate large vibration in the normal rotation speed range of the main engine, the natural frequency of these vibrations is increased by connecting the main engine and the hull with stays. Then, the resonance point is attempted to be driven out of the normal rotation speed range to avoid resonance.

The principle of increasing the lateral vibration natural frequency of the main machine by the vibration-proof stay will be described using a simple vibration model. The transverse vibration system of the main machine in the actual structure as shown in FIG. 3 (a) can be replaced with a simple vibration model as shown in FIG. 3 (b) assuming that the main machine 1 is a rigid body. Here, the symbol m is the mass of the main engine, and kd, ks, and kh are the rotational rigidity of the main engine stand with respect to the lateral displacement of the main engine, the left-right rigidity of the anti-vibration stay, and the left-right rigidity of the hull structure. In this model, the mass m, that is, the natural frequency of the lateral vibration of the main machine is expressed by the following equation (1), where w is the natural frequency without the vibration-proof stay and W is the natural frequency with the vibration-proof stay. ) And (2), the natural frequency is higher when the vibration-proof stay is provided than when the vibration-proof stay is not provided by (ks * kh) / (ks + kh) in the equation (2).

[Equation 1]

[0005]

As described in the prior art, the lateral vibration natural frequency of the main engine is increased by the vibration isolating stay, and the amount of the increase is the rigidity ks of the vibration isolating stay and the hull receiving it. The shape depends on both the rigidity kh of the structure, and the increase amount of the natural frequency changes depending on the rigidity kh of the hull structure.

For example, as shown in FIG. 2 (a), when the vibration isolating stay 2 of the main engine 1 is removed from the pillar 7, the rigidity k of the hull structure is
Since h is determined by the bending rigidity of the pillar 7, it is difficult to obtain high rigidity even if a relatively large pillar is used, such as when the stay height is far from the deck height, and as a result, sufficient inherent characteristics are obtained. In many cases, the increase in frequency cannot be expected. Also, as shown in FIG. 2B, the method of providing the bracket 8 on the deck 4 to receive the vibration-proof stay 2 is sufficient because the hull rigidity kh is determined by the bending and shearing rigidity of the bracket 8. It is difficult to obtain rigidity. Furthermore, these hull structures generate bending moment M in the hull due to the load transmitted from the main engine through the vibration isolating stay 2 and generate vibration in the deck 4, as shown in FIGS. 4 (a) and 4 (b). In some cases, cracks 11 and 12 were generated in the hull structure and pillars.

The present invention has been made in view of such inadequacies of the prior art, and an object thereof is to have sufficient rigidity to exert the effect of the vibration-proof stay. In addition, the present invention provides a hull structure that does not generate a bending moment that adversely affects the hull vibration.

[0008]

In order to achieve the above object, according to the present invention, a base portion 21 of a vibration isolating stay 2 is pivotally mounted on a port side of an upper portion of a main engine 1 at a predetermined position, and an outer plate 5 and a transformer. A deck 4 is provided at a fixed height on both sides of the hull structure composed of the web 6 and the main engine 1, and a vibration isolating stay 2 having a predetermined length and rigidity is horizontally provided. A tilting member 9 is provided from the tip 22 of the anti-vibration stay 2 toward the intersection of the outer plate 5 and the deck 4, and
It has a vertical member 10 linked to the inner end of the triangle and constitutes a triangle.

A base portion 21 of a vibration isolating stay 2 is pivotally mounted on a port side at a predetermined position above the main engine 1, and a hull structure composed of an outer plate 5 and a transweb 6 and both sides of the main engine 1 are fixed. The deck 4 is provided at the height of, and the vibration isolating stay 2 having a predetermined length and having rigidity is horizontally provided, and the horizontal member 13 is provided from the tip portion 22 of the vibration isolating stay 2 toward the outer plate 5. The vertical member 10 linked to the tip 21 of the anti-vibration stay 2 and the inner end of the deck 4 constitutes a quadrangle.

[0010]

EXAMPLE In the example shown in FIG. 1 (a), an inclined member 9 made of H-shaped steel or the like is attached to a tip portion 2 of a vibration-proof stay 2 of a main machine 1.
It is arranged obliquely from 2 toward the intersection of the outer plate 5 and the deck 4, and its end is fixed to the hull structure. In addition, the main engine side is linked to the vertical member 10 such as H-shaped steel, which is also lowered from the deck 4,
The vibration-proof stay 2 is linked to the intersection of the vertical member 10 and the tilting member 9.

In the embodiment shown in FIG. 1 (b), the horizontal member 13 made of H-shaped steel or the like is used for the vibration isolating stay of the main engine 1.
2 is arranged horizontally from the tip 22 of the outer plate to the outer plate, and the end is fixed to the transformer web 6 of the outer plate, and the main engine side is linked to the vertical member 10 also unloaded from the deck 4,
The vibration-proof stay 2 is linked to the intersection of the vertical member 10 and the horizontal member 13.

[0012]

Since the present invention is configured as described above, it has the following effects.

In the embodiment shown in FIG. 1 (a), the tilting member 9, the deck 4 and the vertical member 10 form a triangular truss structure, so that bending moment is unlikely to occur in each member and Even if the main machine vibration is transmitted, the vibration of the deck etc. does not occur. Further, since the pulling rigidity of the tilting member 9 is dominant in the hull rigidity, if the cross-sectional area of the tilting member 9 is large, the rigidity can be secured and the effect of the vibration isolating stay can be sufficiently exhibited.

FIG. 5 shows the lateral vibration of the main engine with and without the anti-vibration stay in an actual ship with the anti-vibration stay attached to the hull structure using the embodiment shown in FIG. 1 (a). This is a comparison of accelerations, but a large resonance peak that was generated at the normal rotation speed when the anti-vibration stay was removed, jumped out of the operating speed range with the anti-vibration stay attached. The hull structure according to the present invention proves to be effective as a hull structure for receiving a vibration isolating stay, since the hull structure has changed to a low response.

On the other hand, in the embodiment shown in FIG. 1B, the truss structure is not formed, but the transformer web 6 of the outer plate to which the horizontal member 13 is fixed is bent as compared with the pillar 7 and the bracket 8 shown in FIG. Since it has high rigidity, it exhibits the same effects as above.

Further, since the hull structure according to the present invention can be formed by a frame structure using H-shaped steel or the like, the tilting member 9
Also, piping, ventilation space, etc. can be secured between the horizontal member 13 and the hull deck 4, so that the equipment in the engine room is not hindered.

Further, since the structure is simple, construction can be easily carried out even when an anti-vibration stay is newly provided on an existing ship.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 shows a conventional hull structure for receiving a vibration-proof stay for a main engine,
It is shown schematically in a sectional view.

FIG. 3 is a diagram showing a lateral vibration of the main engine using a simple vibration model.

FIG. 4 is a sectional view showing an example of hull deformation when lateral vibration of the main engine is transmitted to the hull through the vibration isolating stay in the conventional hull structure for receiving the vibration isolating stay of the main engine.

FIG. 5 shows the effect of the embodiment as an actual measurement value of an actual ship.

[Explanation of symbols]

1 main engine 2 Anti-vibration stay 3 double bottom 4 decks 6 Transweb Seven pillars 9 Inclined member 10 Horizontal member 13 Vertical member

Claims (2)

(57) [Claims] 1. A base of an anti-vibration stay is pivotally attached to one side of a predetermined position on the upper part of the main engine, and a hull structure composed of an outer plate and a transweb and a constant height on both sides of the main engine. The anti-vibration stay, which is provided with a deck and has a predetermined length and rigidity, is provided horizontally, and an inclined member is provided from the tip of the anti-vibration stay toward the intersection of the outer plate and the deck. A hull structure for receiving an anti-vibration stay of a main engine, having a vertical member linked to the tip end and the inner end of the deck, and forming a triangle. 2. A base of an anti-vibration stay is pivotally attached to one side of a predetermined position above the main engine, and a hull structure composed of an outer plate and a transweb and both sides of the main engine have a constant height. The anti-vibration stay, which is provided with a deck and has a predetermined length and rigidity, is provided horizontally, and a horizontal member is provided from the tip of the anti-vibration stay toward the outer plate. A hull structure for receiving an anti-vibration stay of a main engine, which has a vertical member linked to an inner end portion and forms a quadrangle.