JPH06159435A - Coaxial type dynamic vibration absorbing device - Google Patents

Abstract

PURPOSE:To obtain a coaxial type dynamic vibration absorbing device of high performance and economy which can be adapted within a wide oscillation number range including a specified Herz of high frequency with a compact structure, and can remarkably control oscillations in a specified direction without interference of oscillations in other directions. CONSTITUTION:A coaxial type dynamic vibration absorbing device coaxially supports an outer cylinder 1 and an inner cylinder 2 by means of an elastic body 3 inserted in the circular space between both the cylinders 1, 2. The elastic body 3 is composed of a cylindrical elastic body 3 or a plurality of elastic segments which is prepared by longitudinally dividing the cylindrical elastic body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coaxial dynamic vibration reducer.

[0002]

2. Description of the Related Art A dynamic vibration reducer is one of the means for reducing the vibration of rotating machines and structures. This is because by installing a vibrating body having the same natural frequency as the vibration frequency of the structure to be damped, the vibrating body vibrates and consumes vibration energy, thereby rotating machines and structures of the structure. It reduces the vibration response amount of. The dynamic vibration absorber
It is composed of a vibrating mass body and an elastic body supporting it, and the primary frequency f of the one-degree-of-freedom system is the mass M and the spring constant K of the elastic body.
Is determined from the following equation. f = (1 / 2π) √ (K / M) (H _Z ) In the conventional dynamic vibration absorber, as shown in FIG. 5, the mass body 2 is fixed on the leaf spring 6, and the leaf spring 6 is the target structure. Support the object 4. Further, as shown in FIG. 6, the mass body 2 is supported on the target structure 4 by a commercially available vibration-proof rubber 7. by the way,
The magnitude of the vibration absorbing effect of this type of dynamic vibration absorber depends on the following conditions. (1) The ratio of the mass of the mass body 2 of the dynamic vibration reducer to the vibration mass of the target structure is about 10%, but the larger the ratio, the greater the effect. (2) Attenuation rate of the elastic body. When the attenuation rate is small, the effect at a specific frequency is large, but the frequency width is small. On the contrary, the larger the attenuation rate, the wider the frequency range and the more the reduction effect is obtained. (3) Match the frequency of the target structure with the natural frequency of the dynamic vibration absorber. The higher the matching accuracy is, the larger the effect is. However, when the attenuation rate in (2) is large, the effect can be obtained even if the matching does not occur a little.

[0003]

However, the conventional structure of this type of dynamic vibration reducer has the following problems. In the case of the leaf spring type shown in Fig. 5:
Due to the restriction on the strength of the leaf spring, one with a low natural frequency does not hold. (2) The leaf spring has a small damping rate, and the effect cannot be obtained unless the natural frequency exactly matches the frequency of the target structure, and the frequency range in which the effect is obtained is narrow. In the case of the structure supported by a commercially available anti-vibration rubber or the like in FIG. (1) When the natural frequency is desired to be set high, the spring constant of the elastic body 7 is relatively small, so that it is necessary to reduce the mass of the mass body 2, and the reducing effect is small. (2) Since the vibration directions have 6 degrees of freedom and the frequencies are close to each other, adverse effects may occur at frequencies other than the target frequency. Therefore, a structure in which the vibration direction is one direction and the damping factor and the mass can be set large and the range of the frequency that can be set is wide has a high reduction effect, a wide range of use, and high reliability.

As shown in FIG. 7, a structure in which an inner cylinder and an outer cylinder are coaxially supported by a plurality of springs in the radial direction is also known. In the X- and Y-directions, the frequencies around the X-axis and the Y-axis are close to those in the Z-axis direction. Therefore, due to mutual interference, a vibration in one direction is attenuated, but a phenomenon such as an increase in vibration in the other direction may occur, which requires a detailed study at the time of design.
Further, when the damping rate of the spring is small, if the vibration frequency is constant, the vibration response will be as shown by the solid line in FIG. 8A, and there is no problem, but if the target device has a variable frequency, A) As shown by the broken line, peaks appear at two other frequencies. When the attenuation rate is large, this broken line attenuates as shown in FIG.

[0005] The present invention has been proposed in view of such circumstances, a compact structure can be applied to the frequency band of a wide range including high frequency of several 100H _Z, vibrate the vibration in the specific direction in the other direction It is an object of the present invention to provide a high-performance and economical coaxial type dynamic vibration absorber capable of significantly suppressing vibrations without interference by.

[0006]

To this end, the present invention is directed to a coaxial dynamic vibration reducer in which an outer cylinder and an inner cylinder are coaxially supported by an axial elastic body inserted in an annular space between them. ,
It is characterized in that the elastic body is composed of a plurality of elastic body segments which are formed by vertically dividing the cylindrical elastic body or the cylindrical elastic body and are arranged at equal intervals in the same annular space.

[0007]

With this structure, the natural frequency can be adjusted by the ratio of the mass and the spring constant, so that the spring constant is G ^* , r.
_Since it can be adjusted with four parameters of ₁ , r ₂ and h, and the mass can be adjusted by γ, r ₁ , r ₂ , r ₃ , and h, it is possible to design a wide range of dynamic vibration absorbers by selecting each size and material. Becomes The vibration response when the present device is installed on the target structure or a rotating machine is as shown in FIG. That is,
When the damping rate of the elastic body is small, as shown by the broken line, there is a large reduction effect at a certain frequency, but at other frequencies, the vibration is rather greatly increased, while the elasticity with a high damping rate is high. When the body is used, a remarkable damping effect appears in a wide frequency range as shown by the thick solid line. However, since the dynamic spring constant is higher than the static spring constant as a characteristic of rubber and it is difficult to adjust it by only calculation, it is effective to prepare an additional weight for adjustment to be attached.

[0008]

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 is a vertical cross-sectional view of a dynamic vibration reducer showing a first embodiment in which an outer cylinder is fixed to a target object and an inner cylinder is a vibrating body, FIG. 2 is a cross-sectional view of the dynamic vibration reducer of FIG. 1, and FIG. It is a longitudinal cross-sectional view showing a second embodiment in which an inner cylinder is fixed to a target object and an outer cylinder is a vibrating body.

1 and 2, 1 is an outer cylinder having a square cross section, 2 is a square cross section coaxially inserted and fixed to the outer cylinder 1 through a cylindrical elastic body 3 having a square cross section. Is an inner cylinder having. Here, the cross section of the inner and outer cylinders is shown in FIG.
As shown in FIG. 2, the shape may be a regular octagon, a circle, or the like, and the elastic body may be a cylindrical body having a cross section that matches the cross sectional shape of the inner and outer cylinders, and is made of rubber or the like. A shape in which a plurality of segments are divided in the axial direction may be arranged in the annular space between the inner and outer cylinders at equal intervals. As the elastic body, a material having a higher damping rate such as rubber than a coil spring is used, and a new material such as resin or gel is adopted depending on required specifications. 1 and 3 show a shape in which the main vibration absorber is hung vertically on the lower surface of the target object, but it may be upside down, and when horizontal vibration is targeted, it is horizontal. To install.

In such a structure, for example, the static spring constant in the shearing direction of a cylindrical elastic body is approximately obtained by the following equation. K _S = G ^* × 2.73 [1+ (1/3) {(r ₂ −r ₁ ) / r ₁ } ² ] ・
h ₁ / log (r ₂ / r ₁ ) where G ^* : elastic coefficient of elastic body r ₂ , r ₁ : outer radius and inner radius of cylindrical elastic body h: length of cylindrical elastic body The mass is calculated by the following formula. The inner cylinder (in the case of ^{_{cylindrical): M = πr 1 2 h}} 2 · γ 1 / g sheath (case of a _{cylindrical): M = π (r 3} 2 -r 2 2) · h 3
・ Γ ₂ / g where γ ₁ and γ _{2 are} : specific gravity of material g: acceleration of gravity r ₂ , r ₃ : radius of inner cylinder and outer cylinder h ₃ : length of outer cylinder When inner cylinder is a cylinder Is calculated similarly to the outer cylinder.

According to this structure, since the natural frequency can be adjusted by the ratio of the mass and the spring constant, the spring constant can be adjusted by the four parameters G ^* , r ₁ , r ₂ and h.
Since the mass can be adjusted by γ, r ₁ , r ₂ , r ₃ , and h, a wide range of dynamic vibration absorber designs can be made by selecting each size and material. The vibration response when this device is installed in a target structure or a rotary machine is as shown in FIG. That is, when the damping rate of the elastic body is small, as shown by the broken line, there is a large reduction effect for a certain frequency, and at other frequencies, the vibration is rather large, but the elasticity with a high damping rate is large. When the body is used, a remarkable damping effect appears in a wide frequency range as shown by the thick solid line. However, since the dynamic spring constant is higher than the static spring constant as a characteristic of rubber and it is difficult to adjust it by only calculation, it is effective to prepare an additional weight for adjustment to be attached.

[0012]

According to such an invention, the following effects can be obtained. (1) Applicable to a wide range of target frequencies. In particular damping is also possible to target the high-frequency (several 100H _Z). (2) Since a spring constant higher than that of the conventional structure can be obtained, the mass of the mass body can be increased at the same frequency, so a high reduction effect can be obtained. (3) A low frequency can be applied by increasing the thickness of the elastic body. (4) When the length is changed, the natural frequency is constant and only the vibrating mass is increased, which facilitates the design. (5) The vibration direction can be limited to one direction, and adverse effects at frequencies other than the target frequency can be avoided. This is because, in the structure of the present invention, the spring constant of the elastic body is higher in the radial direction (X and Y directions in FIG. 7) than in the shear direction (Z direction in FIG. 7) (the ratio depends on the thickness). Since vibration is performed in the axial direction, the frequencies in the X direction, the Y direction, the Z direction, and the rotation direction around the Y axis largely differ from the frequencies in the Z axis direction. Therefore, the design becomes easy. By the way, in the coaxial dynamic vibration absorber shown in FIG. 7, since the frequencies in the X, Y directions, around the X axis, and around the Y axis are close to those in the Z axis direction, respectively, even if vibration in one direction can be suppressed, The phenomenon in which the vibration of (3) increases is likely to occur, and in order to avoid this, a great amount of time is required at the time of design. (6) Compared with a dynamic absorber using a metal spring, the damping rate is high and a stable reduction effect can be obtained even if the frequency slightly shifts. Incidentally, in the coil spring, the vibration response has a pair of peaks as shown by the broken line in FIG. 8 (A), but in the present invention, it becomes as shown by the broken line in FIG. 8 (B) and no peak occurs. Disappear.

In short, according to the present invention, in the coaxial dynamic vibration reducer in which the outer cylinder and the inner cylinder are coaxially supported by the axial elastic body inserted in the annular space between them, the elastic body is The cylindrical elastic body or the cylindrical elastic body is vertically divided, and is composed of a plurality of elastic body segments which are arranged at equal intervals in the same annular space.
It can be applied to a wide frequency range including high frequency of 00H _Z , and vibration in a specific direction can be performed without interference by vibration in another direction.
INDUSTRIAL APPLICABILITY The present invention is of great industrial benefit because it provides a high-performance and economical coaxial dynamic vibration absorber that can be significantly limited.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a dynamic vibration absorber showing a first embodiment of the present invention in which an outer cylinder is fixed to a target object and an inner cylinder is a vibrating body.

FIG. 2 is a cross-sectional view of the dynamic vibration reducer of FIG.

FIG. 3 is a vertical sectional view of a dynamic vibration reducer showing a second embodiment of the present invention in which an inner cylinder is fixed to a target object and an outer cylinder is a vibrating body.

FIG. 4 is a diagram showing a vibration response of a target structure according to the present invention.

FIG. 5 is a side view showing a conventional dynamic vibration reducer.

FIG. 6 is a side view showing a conventional dynamic vibration reducer different from that of FIG.

FIG. 7 is a plan view showing a conventional coaxial cylindrical dynamic vibration absorber,
FIG. 8 is a diagram showing a vibration response by the vibration absorber of FIG. 7. FIG.

[Explanation of symbols]

 1 Outer Cylinder 2 Inner Cylinder 3 Elastic Body 4 Fixed Surface of Target Structure 5 Natural Frequency Adjustment Weight 6 Leaf Spring 7 Elastic Body such as Antivibration Rubber on the Market

Claims (1)

[Claims] 1. A coaxial dynamic vibration absorber in which an outer cylinder and an inner cylinder are coaxially supported by an axial elastic body inserted in an annular space between the outer cylinder and the inner cylinder, wherein the elastic body is a cylindrical elastic body or A coaxial type dynamic vibration absorber, characterized in that the same cylindrical elastic body is vertically divided, and is constituted by a plurality of elastic body segments arranged in the same annular space at equal intervals.