JPH09329183A - Dynamic vibration absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and rapidly adjust the characteristic frequency of a dynamic vibration absorber, to the frequency of the vibration body, so that the vibration is not increased, when the frequency of the vibration body is changed. SOLUTION: A dynamic vibration absorber comprises an outer cylindrical member 5 attached to a vibration body 7 in a condition that the vibrating direction is the direction of a center line, a cylindrical damping rubber 4 of which an outer peripheral face is kept into contact with an inner peripheral face of the outer cylindrical member 5 to be supported thereby, a mass bolt 2 coaxially installed in such manner that a basic part is attached to one end part of the damping rubber 4, and the pointed end part is projected outward from the other end part of the damping rubber 4, and a mass nut 1 screwed in the pointed end of the mass bolt 2 for adjustably pressing the rubber cushion 4.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to ships, bridges, towers,
The present invention relates to a so-called dynamic damper, which is a dynamic vibration absorber used for deresonating a structural element that vibrates or forcibly vibrates in a shaft system or for absorbing vibration energy.

[0002]

2. Description of the Related Art FIG. 4 is a conceptual diagram of a conventional dynamic vibration reducer.
The dynamic vibration reducer includes a mass body 2 and a spring 4, and the mass body 2 is attached to a vibrating body 7 which is an object for reducing vibration via the spring 4. The vibrating body 7 vibrates by itself or by being forced by others. The natural frequency of this dynamic vibration absorber is 2
And the spring constant of the spring 4. If the natural frequency of this dynamic vibration absorber matches the frequency of the vibrating body 7,
Since the mass body 2 resonates and vibrates greatly, the vibration of the vibrating body 7 can theoretically be zero. When the vibration frequency of the vibrating body 7 changes and does not match the natural frequency of this dynamic vibration absorber, the vibration of the vibrating body 7 becomes large. Is increased or decreased to tune the natural frequency of the dynamic vibration absorber to the frequency of the vibrating body 7.

[0003]

Although the conventional dynamic vibration reducer is as described above, when the vibration frequency of the vibrating body 7 changes, the mass body 2 is adjusted to match the natural frequency of the dynamic vibration reducer. It is necessary to increase or decrease the mass by adding or removing the iron plate of, but it is necessary to precisely adjust the mass to match the natural frequency, and it is troublesome to prepare iron plates of various masses. You have to adjust the mass. In addition, there is a problem that the work place may be difficult due to a narrow working space.

The present invention has been made in order to solve the above problems, and even if the vibration frequency of the vibrating body 7 changes,
It is an object of the present invention to obtain a dynamic vibration reducer capable of easily and quickly matching the natural frequency of the dynamic vibration reducer with the vibration frequency of.

[0005]

SUMMARY OF THE INVENTION A dynamic vibration reducer according to the present invention includes an outer ring cylinder mounted on a vibrating body with its vibration direction as a centerline direction, and an outer peripheral surface on an inner peripheral surface of the outer ring cylindrical body. A cylindrical vibration-absorbing rubber provided so as to contact and be supported by,
A base is adhered to one end of the vibration-absorbing rubber, and a tip end thereof is concentrically provided so as to project outward from the other end of the vibration-absorbing rubber, and is screwed into the tip end of the mass bolt. And a mass nut that adjustably presses the vibration-absorbing rubber.

In the dynamic vibration reducer according to the present invention, the vibration of the vibrating body is transmitted from the outer ring cylindrical body to the mass bolt and the mass nut functioning as the mass body through the vibration absorbing rubber functioning as the spring. When the mass nut is screwed into the mass bolt and lightly pressed against the vibration absorbing rubber, the spring constant of the vibration absorbing rubber is small, and the natural frequency of this dynamic vibration reducer is low, and when strongly pressed, the spring constant of the vibration absorbing rubber is large. The natural frequency of the dynamic vibration absorber becomes high. That is, the natural frequency of this dynamic vibration absorber can be changed simply by turning the mass nut. Thus, even if the frequency of the vibrating body changes, the natural frequency of the dynamic vibration reducer can be changed to match the frequency of the vibrating body to reduce the vibration of the vibrating body.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a dynamic vibration reducer according to the present invention will be described below with reference to the drawings. In FIG. 1, 1
Is a mass nut, 2 is a mass bolt, 3 is a holding plate, 4 is a vibration absorbing rubber, 5 is an outer ring cylinder, 6 is a mounting bolt, and 7 is a vibrating body. The vibrating body 7 vibrates by itself or by being forced by others.
This dynamic vibration reducer is provided to reduce the vibration of the vibrating body 7. The outer ring cylinder 5 has a cylindrical shape, and the center line of the outer ring cylinder 5 is aligned with the vibration direction of the vibrating body 7 indicated by an arrow. It is attached. The vibration-absorbing rubber 4 has a thick-walled cylindrical shape.
The outer peripheral surface of is formed so as to be in close contact with the inner peripheral surface of the outer ring tubular body 5, and in the lower part of the figure, the vibration absorbing rubber 4 and the outer ring tubular body 5 are bonded. The mass bolt 2 is attached so as to be embedded in the center line of the vibration-absorbing rubber 4, and the mass bolt 2 and the vibration-absorbing rubber 4 are adhered to each other in the lower portion of the figure, and the inner peripheral surface of the vibration-absorbing rubber 4 is attached to the mass bolt 2 above the mass bolt. There is a gap between the outer surface of No. 2 and the outer surface of No. 2. The holding plate 3 has a washer shape and is placed on the upper surface of the vibration absorbing rubber 4 in the figure. The mass nut 1 and the mass bolt 2 are mass bodies of this dynamic vibration absorber, and the vibration absorbing rubber 4 corresponds to a spring.

Next, the operation of the dynamic vibration reducer shown in FIG. 1 will be described. When the vibrating body 7 vibrates in the vertical direction as shown by the arrow, the outer ring cylinder 5 attached to the vibrating body 7 with the mounting bolts 6 also has the same amplitude, the same frequency, and the same frequency in the same direction as the vibrating body 7. Vibrates in phase. Since the mass nut 1 and the mass bolt 2 which are the mass bodies of this dynamic vibration absorber are attached to the outer ring cylindrical body 5 through the vibration absorbing rubber 4 corresponding to the spring, the vibration direction is the same, but the mass The amplitude and the phase of vibration of the nut 1 and the mass bolt 2 are different from the amplitude and phase of the vibrating body 7.

Mass of the mass body of the dynamic vibration reducer (in the dynamic vibration reducer shown in FIG. 1, a total of the mass of the mass nut 1, the mass bolt 2, and the holding plate 3 plus a part of the mass of the vibration absorbing rubber 4) ) Is m, and the spring constant of the vibration-absorbing rubber 4 acting as a spring is k, the natural frequency f or the natural angular frequency ω of this dynamic vibration absorber
Becomes as shown in the following equation.

2πf = ω = √ (k / m)

That is, the natural frequency f of the dynamic vibration absorber is determined by the mass m of the mass body and the spring constant k of the spring or the vibration absorbing rubber 4.

When the natural frequency of the dynamic vibration absorber matches the frequency of the vibrating body 7, the mass body of the dynamic vibration absorber resonates with the vibration of the vibrating body 7 and vibrates greatly in a phase different by 180 degrees. , Theoretically the vibration of the vibrating body 7 becomes zero. However, if the natural frequency of the dynamic vibration absorber does not match the frequency of the vibrating body 7 and there is a certain difference, the vibration of the vibrating body 7 becomes very large because the dynamic vibration reducer is attached. Therefore, the natural frequency of the dynamic vibration absorber must always match the frequency of the vibrating body 7. The vibrating body 7 also tries to vibrate at its own natural frequency, but the forced vibration may cause it to vibrate at a frequency deviating from the natural frequency of the vibrating body 7 itself, so the frequency of the vibrating body 7 is not constant. .

When the frequency of the vibrating body 7 changes in this way, it is necessary to change the natural frequency of the dynamic vibration absorber to match the changed frequency of the vibrating body 7. Therefore, although the mass m was increased or decreased in the conventional dynamic vibration reducer shown in FIG.
In the dynamic vibration absorber shown in (1), the natural frequency is changed and adjusted by changing the spring constant k of the vibration absorbing rubber 4. That is, when the mass nut 1 is screwed in and the vibration absorbing rubber 4 is pressed through the pressing plate 3, the elastic coefficient of the vibration absorbing rubber 4 is non-linear, or the vibration absorbing rubber 4 is compressed.
The spring constant of the vibration absorbing rubber 4 increases due to the fact that the upper part of the outer peripheral surface of the element strongly hits the inner peripheral surface of the outer ring cylindrical body 5 or the inner peripheral surface of the vibration absorbing rubber 4 comes into contact with the mass bolt 2. .
In the above equation, if the spring constant k of the vibration absorbing rubber 4 becomes higher, the natural frequency f becomes higher in proportion to its square root. On the contrary, when the mass nut 1 is unscrewed, the spring constant k of the vibration absorbing rubber 4 decreases and the natural frequency f decreases. in this way,
By simply turning the mass nut 1, the natural frequency of this dynamic vibration absorber can be changed to match the frequency of the vibrating body 7,
The vibration of the vibrating body 7 can be reduced.

Next, another embodiment of the dynamic vibration absorber according to the present invention shown in FIG. 2 will be described. In the dynamic vibration absorber shown in FIG. 2, in order to ensure the adhesion between the lower part of the mass bolt 2 and the lower part of the vibration absorbing rubber 4, the receiving plate 8 is welded to the lower end of the mass bolt 2. In the dynamic vibration absorber shown in FIG. 2, the mass nut 1
When is turned and screwed in, the vibration-absorbing rubber 4 can be pressed more reliably.

Next, still another embodiment of the dynamic vibration absorber according to the present invention shown in FIG. 3 will be described. In the dynamic vibration absorber shown in FIG. 3, the receiving plate 8 is provided to ensure the adhesion between the lower portion of the mass bolt 2 and the lower portion of the vibration absorbing rubber 4. Further, the lower part of the mass nut 1 is formed in a conical shape. In the dynamic vibration reducer shown in FIG. 1, the mass nut 1 is rotated to press the vibration absorbing rubber 4 in the axial direction. However, in the dynamic vibration reducer shown in FIG. 3, the mass nut 1 is rotated to be screwed back to form a conical shape. The vibration absorbing rubber 4 is pressed and loosened in the lower part of the mass nut 1 in the axial direction as well as the radial direction to change mainly the contact state of the outer peripheral surface of the upper part of the vibration absorbing rubber 4 with the outer ring cylindrical body 5. , The part of the vibration-absorbing rubber 4 that acts as a spring works only when the mass nut 1 is loosened, and when tightened, both the lower part and the upper part work, changing the spring constant of the vibration-absorbing rubber 4 and changing the natural frequency. I did it.

In the dynamic vibration reducer shown in FIG. 3, a plurality of cuts in the radial direction including the center line may be cut in the vibration absorbing rubber 4 in a symmetrical manner. If there is a break, when the mass nut 1 is turned, the vibration absorbing rubber 4 is easily displaced in the radial direction, so that the mass nut 1 can be easily rotated.

When the dynamic vibration absorber according to the present invention shown in FIG. 1, FIG. 2 or FIG. 3 becomes large, the mass nut 1 or the mass bolt 2 is fitted with an electric motor, and the mass nut 1 is mounted, for example, via a worm gear. It is also possible to rotate the mass nut 1 only by operating the switch button of the electric motor to change the spring constant of the vibration absorbing rubber 4 to change the natural frequency of the dynamic vibration reducer. it can. In this case, the shape and the like of the mass nut 1 may be changed appropriately.

When the electric motor is provided and the mass nut 1 is rotated only by operating the switch button as described above, a sensor and a microcomputer for detecting the frequency of the vibrating body 7 are further provided to detect the frequency. It is also possible to automatically rotate the mass nut 1 according to the frequency of vibration.

[0019]

As described above, in order to prevent the vibration from increasing when the frequency of the vibrating body changes, the natural frequency of this dynamic vibration absorber is changed to match the frequency of the vibrating body. However, according to the present invention, the natural frequency of this dynamic vibration absorber can be easily and quickly changed by simply turning the mass nut. Can be changed continuously.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a dynamic vibration reducer according to the present invention.

FIG. 2 is a side sectional view showing another embodiment of the dynamic vibration reducer according to the present invention.

FIG. 3 is a side sectional view showing still another embodiment of the dynamic vibration reducer according to the present invention.

FIG. 4 is a conceptual diagram showing a conventional dynamic vibration reducer.

[Explanation of symbols]

 1: mass nut, 2: mass bolt, 3: presser plate, 4: vibration absorbing rubber, 5: outer ring cylinder, 6: mounting bolt, 7: vibrating body, 8: receiving plate.

Claims (1)

[Claims] 1. An outer ring cylinder attached to a vibrating body with its vibration direction as a centerline direction, and a cylinder provided so that an outer peripheral surface is in contact with and supported by an inner peripheral surface of the outer ring cylindrical body. -Shaped vibration-absorbing rubber, a mass bolt provided concentrically so that the base portion is adhered to one end of the vibration-absorbing rubber, and the tip end portion projects outward from the other end of the vibration-absorption rubber member, and the tip end of this mass bolt A dynamic vibration reducer comprising a mass nut that is screwed into a portion and presses the vibration absorbing rubber in an adjustable manner.