JPH08128500A - Dynamic vibration absorbing device - Google Patents

Abstract

PURPOSE: To prevent the breakage due to the fatigue of an elastic member for carrying out the reduction of vibration of a main vibration body without deteriorating the vibration reducing effect, by installing a rail having a traveling groove laid horizontally toward one direction between a supporting board and a weight, and a bearing which supports the weight on the supporting board through the turn in the traveling groove in the rail laying direction. CONSTITUTION: The operation direction of a dynamic vibration absorbing device 1 is the A direction, and a ball bearing 5 is not applied with the resistance in the A direction, and moves along a rail 4 having a V-shaped groove. However, in the B direction perpendicular to the action direction of the dynamic vibration absorbing device 1, the V-shaped groove of the rail 4 forms the resistance, and the ball bearing 5 does not move. Accordingly, a weight 2 vibrates in the A action direction of the dynamic vibration absorbing device 1 according to the vibration characteristic determined by the mass Md and the spring constant Kd of a spring member 3, and the characteristic frequency fd is allowed to accord with the characteristic frequency fA in the direction for reducing the vibration of a main vibration body, and tuning is carried out by varying Md by increasing and reducing the variable weight 2b. Accordingly, the fatigue evaluation is reduced, and the fatigue breakage of the elastic member 3 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic vibration reducer applied as a vibration reducing device for a superstructure of a ship, a diesel main engine, or various structures.

[0002]

2. Description of the Related Art A dynamic vibration reducer is a device for reducing vibrations generated in various structures such as a superstructure of a ship and a diesel main engine.

As shown in FIG. 4, on the main hull 010,
Upper structures such as a living area 011 and a chimney 012 (hereinafter, represented by a chimney) are installed. On the other hand, the main hull 01
No. 0 is equipped with a propeller 014 that generates fluctuating water pressure, or a device that becomes a vibration source such as a diesel main engine 013 for propulsion that generates a large vibration force to change linear motion into rotary motion. When the excitation frequency of these devices resonates with the natural frequency of the chimney 10 of the main hull 010, excessive vibration may occur in the chimney 010.

As a means for solving such a vibration trouble, a dynamic vibration reducer 03 is installed in a chimney 010 for reducing the vibration to reduce the vibration. Figure 5
Is a diagram for explaining the effect of the dynamic vibration reducer 03. Since excessive vibration occurs in the chimney 012 shown in FIG. 4, a vibration response curve when the dynamic vibration reducer 03 is installed on the top of the chimney 012 is shown. Shows.

That is, in FIG. 5, the horizontal axis is the chimney 01.
Propeller 014 equipped on the hull 010 where 2 is installed
The rotational speed frpm and the vertical axis represent the vibration response x. The figure is an example of tracking analysis of the rotational order component N having a large excitation force, such as the number of propeller blades and the number of diesel main engine cylinders.
Generally, the frequency f having a large excitation force can be expressed by Equation 1.

[0006]

[Equation 1]

If the dynamic vibration absorber 03 is not installed, the chimney 01
The vibration response x _{O of} 2 is the natural frequency f _A of the chimney 012 that vibrates in the front-back (longitudinal) direction of the main hull 010 (hereinafter referred to as the natural frequency in the front-back direction) and the left-right (width) direction of the ship 010. It becomes large near the natural frequency f _{T of the} vibrating chimney 012 (hereinafter referred to as the natural frequency in the left-right direction).

Therefore, the natural frequency f of the dynamic vibration reducer 03
_{If d} is tuned to a frequency close to the natural frequency f _A of the chimney 012 in the front-rear direction and installed at the top of the chimney 012, the vibration response x _d of the chimney 012 will be the natural frequency in the front-rear direction. It can be significantly reduced near f _A.

Generally, the natural frequency of the chimney 012 is the natural frequency f _A of the main hull 010 in the front-rear direction, and the natural frequency of the main hull 01.
Since the natural frequency f _T of 0 is close to the natural frequency f _T , the natural frequency f with the larger vibration response x _d , or the normal rotation frequency f of the propeller 014 which is frequently used in the operation of the ship
A dynamic vibration absorber 03 tuned to a natural frequency having a high degree of importance, such as a natural frequency closer to _NOR , is attached.

However, two dynamic vibration absorbers 03 tuned to the natural frequency f _A in the front-rear direction and two dynamic vibration absorbers 15 tuned to the natural frequency f _T in the left-right direction are also installed.

FIG. 3 shows an example of the structure of a dynamic vibration reducer conventionally used for reducing the vibration of the chimney 012. As shown in the figure, the dynamic vibration absorber 03 has a weight cone 06 and a spring 0.
5, a support frame 02, and a support base 01. The weight 06 is a weight attachment plate 06a and a fixed weight 06 at the bottom.
c, an upper variable weight 06b, which are integrated by several tightening bolts 04. And this weight 0
6 is attached to the top of the support frame 02 with several helical coil springs and a spring material 05 such as a vibration-proof rubber interposed.

The lower end of the support frame 02 is attached to a support base 01, and the support base 01 reduces the vibration by welding or the like.
Firmly installed on top of 12. In this way, the weight 06 of the dynamic vibration absorber 03 attached to the chimney 012 vibrates in the horizontal direction according to the vibration characteristic determined by the vibration mass Md and the spring constant Kd of the spring member 05.

The natural frequency fd of the weight 06 is determined by the equation 2.

[0014]

[Equation 2]

Tuning for matching the natural frequency fd to the natural frequency f _A in the front-rear direction for reducing the vibration of the chimney 012 is performed by adding and removing the variable weight 06b.
Increase or decrease. In addition, the chimney 01 by the dynamic vibration absorber 03
The vibration reduction amount of 2 is proportional to the ratio of the vibration mass Md of the dynamic vibration reducer 03 to the vibration effective mass of the chimney 012. The larger the vibration mass Md of the dynamic vibration reducer 03, the greater the reduction effect can be obtained.

In the dynamic vibration reducer 03 as described above, (1) the spring material 05 has a static stress σ _m due to bending, which is proportional to the weight of the weight 03, and the weight 03 vibrates. Is added to the dynamic stress σ _a, and if these are large, damage due to fatigue occurs.

Generally, the fatigue evaluation stress σ _t is expressed by the following _equation 3,

[0018]

(Equation 3)

When the fatigue evaluation stress σ _t exceeds the fatigue limit of the spring material 05, fatigue is accumulated and the spring material 05 is damaged.

In order to reduce the fatigue evaluation stress σ _t ,
As can be understood from Equation 3, it is necessary to reduce the average stress σ _m . For that purpose, it is necessary to reduce the amount of bending of the spring member 05 due to the weight of the weight 06. However, this means that the vibration mass Md is reduced, and the ratio with the effective vibration mass of the chimney 012 is decreased, and as described above, the vibration reduction amount of the chimney 012 is small, and the effect of the dynamic vibration reducer 03 is reduced. There is a problem of making it smaller.

(2) Further, the weight 06 shakes the chimney 012.
It vibrates freely in the horizontal direction when motion is reduced. Therefore, dynamic vibration absorption
Vibrate the working direction of the container 03 in the front-back direction of the chimney 012
In this case, the dynamic suction that vibrates in the left-right direction of the chimney 012
Vibration stress σ of weight 06 of shaker 03 _aShakes the chimney 012
The fatigue evaluation stress σ shown in the above-mentioned Equation 3 does not contribute to the dynamic reduction._t
Will only be increased.

Further, as described above, the front-rear direction dynamic vibration reducer for reducing the longitudinal vibration of the chimney 012 in the main hull 010 and the left-right dynamic vibration absorber 03 for reducing the left-right vibration of the main hull 010. If two dynamic vibration absorbers are installed at the same location to reduce vibration, the left and right vibration components of the front and rear direction dynamic vibration absorbers and the front and rear vibration components of the left and right direction dynamic vibration absorbers are tuned to the left and right. For the left and right vibrations of the dynamic vibration absorber
There is a problem in that the front and rear vibrations of the front and rear direction dynamic vibration reducer adversely affect each other, making it difficult to tune these.

[0023]

SUMMARY OF THE INVENTION The present invention solves the above problems and reduces the amount of vibration reduction of the main vibrating body for performing vibration reduction so as not to impair the vibration reducing effect. It is possible to prevent damage to the elastic material that reduces vibration due to fatigue, and to perform vibration only in the vibration direction of the main vibrating body that requires vibration reduction, and prevent vibration of the weight in the direction that does not require vibration reduction to achieve fatigue evaluation stress. It is an object of the present invention to provide a dynamic vibration reducer that can reduce the increase in the vibration, reduce the fatigue damage of the elastic material, and facilitate the tuning work.

[0024]

Therefore, the dynamic vibration reducer 03 of the present invention has the following means.

In a dynamic vibration reducer in which a weight placed on a support base via an elastic material is vibrated to reduce the vibration generated in the main vibrating body to which the support base is attached, (1) It is laid in one horizontal direction between the support and the weight,
A rail with a running groove was provided. The cross-sectional shape of the running groove may be V-shaped or U-shaped.

(2) A bearing is provided which is disposed in the running groove, rotates in one direction in which the rail is laid, and receives the static load of the weight to support the weight on the support base. The bearing may be a ball bearing, a roller bearing, or the like, and the essential point is that it allows the weight to move in one direction of the running groove.

[0027]

[Action]

(1) Since the weight weight is received by the bearing and the rail having the running groove, the static stress σ _m is hardly applied to the elastic material and the fatigue evaluation stress can be kept small, so that the fatigue damage of the elastic material can be prevented.

(2) Since the bearing operates horizontally only in a fixed direction along the rail, it can be operated only in the direction in which the dynamic vibration absorber action is performed, and the weight is actuated in the direction perpendicular to the action. It can be prevented.

Therefore, the dead weight does not sense the action normal direction vibration, the fatigue of the elastic material due to the dynamic stress σ _a generated by the vibration in this direction can be prevented, and two dynamic vibration absorbers are installed. In this case, the vibrations in the direction in which the dynamic vibration reducer is operated and the vibrations in the direction orthogonal thereto do not interfere with each other, and the tuning operation becomes easy.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a dynamic vibration reducer of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing an embodiment of the dynamic vibration reducer of the present invention, and FIG. 2 is a top view of the embodiment shown in FIG. As shown in the figure, the dynamic vibration reducer 1 of this embodiment includes a weight 2, a spring material 3 as an elastic material, a rail 4, a ball bearing 5, a support frame 6,
And a support base 7. The weight 2 includes a weight mounting plate 2a, a fixed weight 2C mounted on the lower surface of the weight mounting plate 2a, and a variable weight 2b stacked on the upper surface of the weight mounting plate 2a. It is integrated with the tightening bolt 8.

A spring member 3 is interposed between a support frame 6 attached to a support base 7 fixed to a main vibrating body such as a chimney (not shown) and the weight attachment plate 2a. Material 3
A plurality of rails 4 each having a ball bearing 5 and a V-shaped groove are mounted in parallel with each other, as shown in FIG. The weight of the weight 2 is received by a rail 4 having a ball bearing 5 and a V-shaped groove, and the amount of deflection of the spring material 3 is constant regardless of the weight of the weight 3.

As shown in FIG. 2, the dynamic vibration reducer 1 of the present embodiment.
Is in the direction of arrow A, and the ball bearing 5 is in the direction of arrow A.
There is no resistance in the direction of and moves along the rail 4 having the V-shaped groove. However, in the direction of arrow B, which is perpendicular to the acting direction of the dynamic vibration reducer 1, the V-shaped groove of the rail 4 becomes a resistance and the ball bearing 5 does not move. In this embodiment, the rail 4 having the V-shaped groove,
Although the ball bearing 5 is used, the sectional shape of the groove may be U-shaped or concave, and a roller bearing may be used. Therefore, the weight 2 has a mass Md and a spring constant K of the spring member 3.
The dynamic vibration absorber 1 vibrates in the acting direction of arrow A according to the vibration characteristic determined by d.

This natural frequency fd is as shown in the above-mentioned equation 2, and in order to match this natural frequency fd with the natural frequency f _A in the direction of reducing the vibration of the main vibrating body, Tuning is performed by increasing or decreasing the weight 2b and changing Md.

As a result, the main vibration body has a fatigue evaluation stress σ.
The vibrating mass Md of the dynamic vibration reducer 1 can be increased without considering the damage of the spring material 3 due to the increase of _t , the ratio with the effective vibration mass of the main vibrating body can be increased, and a large reduction effect can be obtained. it can.

Since the weight 2 vibrates only in the direction of arrow A for the purpose of vibration reduction, the vibration stress σ _a associated with the vibration in the direction of arrow B does not occur, and the fatigue evaluation stress σ
It does not increase _t .

Further, even when the dynamic vibration reducers are installed at the same location in order to reduce the vibrations in the directions of the arrow A and the arrow B, the amount of vibration in the direction of the arrow B of the dynamic vibration absorber for the direction of arrow A,
Since the vibration of the dynamic vibration absorber for the direction of arrow B does not occur in the direction of arrow A, they do not adversely affect each other, and tuning work becomes extremely easy.

[0038]

As described above, according to the dynamic vibration reducer of the present invention, the weight of the weight is received by the rail having the bearing and the running groove, due to the structure shown in the claims. , Static stress due to bending hardly occurs in the elastic material. This reduces the fatigue evaluation stress,
Fatigue damage of the elastic material can be prevented.

(2) Since the bearing moves only in one direction along the rail having the traveling groove, it is possible to make the weight vibrate only in the action direction of the dynamic vibration reducer. It can be prevented from vibrating in the right angle direction.

As a result, the elastic member does not sense the displacement in the direction perpendicular to the acting direction, the fatigue of the elastic member due to this displacement can be prevented, and when two dynamic vibration absorbers are installed,
The two dynamic vibration absorbers can be prevented from interfering with each other in the same direction and the tuning operation can be performed to adjust the natural frequency in the direction in which the two dynamic vibration absorbers act.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a dynamic vibration reducer of the present invention.

FIG. 2 is a top view of the embodiment shown in FIG.

FIG. 3 is a front view showing a conventional dynamic vibration reducer.

FIG. 4 is a diagram in which a dynamic vibration reducer is applied to reduce vibration of a chimney of a ship.

5 is a characteristic diagram for explaining the effect of the dynamic vibration reducer in the application example shown in FIG.

[Explanation of symbols]

 1 Dynamic vibration absorber 2 Weight 2a Weight mounting plate 2b Variable weight 2c Fixed weight 3 Spring material as elastic material 4 Rail 5 Ball bearing 6 Support frame 7 Support base 8 Tightening bolt

Claims (1)

[Claims] 1. A dynamic vibration reducer comprising a support base and a weight mounted on the support base with an elastic material interposed therebetween, which is horizontally laid in one direction between the support base and the weight. A dynamic vibration absorber, comprising: a rail provided with a running groove; and a bearing for rotating the weight in the running groove in the running direction of the rail to support the weight on the support base.