JPH06100245B2 - Dynamic damper - Google Patents

Description

The present invention relates to a dynamic damper that suppresses harmful vibrations of a vibration system. This dynamic damper can be used, for example, to suppress harmful vibrations of mechanical elements such as an engine mount bracket, a differential, and a motor housing.

[Prior Art] Conventionally, in a vibration system such as an engine mount bracket of an automobile, for example, a dynamic damper is used to suppress harmful vibration in a normal range. The dynamic damper has two elastic legs fixed to the vibration system,
It is composed of one mass body elastically supported by elastic legs. In the vibration system equipped with such a dynamic damper, the harmful vibration of the vibration system in the normal range can be suppressed by the vibration absorbing effect for the vibration in the specific frequency range.

Here, the resonance point of the dynamic damper is basically
It is determined by the spring constant of the elastic legs that support the mass body in the vibration direction and the mass of the mass body. The natural frequency is smaller as the spring constant is smaller and the mass is larger.

[Problems to be Solved by the Invention] By the way, although the above-mentioned dynamic damper can prevent harmful vibration of the vibration system in a certain frequency range, if the frequency of the vibration system deviates from the frequency range, the vibration is suppressed by the dynamic damper. The effect decreases.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a dynamic damper that exhibits a vibration damping effect in a wider frequency range.

[Means for Solving the Problems] A dynamic damper according to the present invention comprises at least two elastic legs fixed to a vibration system, and an opposing surface and an edge of the opposing surface elastically supported by the elastic legs. In a dynamic damper consisting of one mass body having a side surface portion that is continuously provided in a direction intersecting with the elastic body, the elastic leg portion is provided between the vibration system and the facing surface on one end side of the facing surface of the mass body. At least 1 that is interposed and compresses and stretches with vibration
The first elastic legs, and the remaining one of the other ends on the facing surface, which extends outward from the side surface of the mass body, is interposed between the vibration system and the side surface, and which undergoes shear deformation with vibration. A second elastic leg portion, and a ratio of a spring constant of the first elastic leg portion and a supporting mass supported by the first elastic leg portion is determined by a spring constant of the second elastic leg portion and a supporting mass of the second elastic leg portion. It is characterized in that it is set to be larger than the ratio to the supporting mass.

In general, the material of the elastic leg portion can be rubber, resin, or a spring material in some cases, and the material of the mass body can be metal such as steel, stainless steel, or ceramics such as alumina.

The first elastic leg elastically supports the mass body in the compression / tension direction with respect to the vibration direction, and the second elastic leg elastically supports the mass body in the shear direction with respect to the vibration direction. When elastically supporting the mass body in the compression / tension direction, the spring constant described above is basically determined by the compression / tension spring constant. Also, when elastically supporting in the shear direction, the above spring constant is basically determined by the shear spring constant.
Although it depends on the shape, the value is generally a fraction to a few hundredths, which is considerably smaller than the compression / tension spring constant.

When fixing the elastic leg portion to the vibration system, the elastic leg portion may be directly fixed to the vibration system by an adhesive means, or may be fixed with a band or the like using another fixing portion such as a bracket. Good.

[Embodiment] A first embodiment of the dynamic damper of the present invention will be described below with reference to FIGS. 1 and 2. This dynamic damper has an elastic leg portion 2 which functions as a rubber first elastic leg portion held by a fixing portion 1 fixed to a vibration system.
And an elastic leg portion 3 functioning as a second elastic leg portion, and a disc-shaped metal mass body 4 elastically supported by the elastic leg portions 2 and 3. The elastic leg portion 2 has a substantially vertical side surface 2a and elastically supports one end side portion 4a of the facing surfaces of the mass body 4, while the elastic leg portion 3 has inclined side surfaces 3a and 3b. A part 4b on the other end side of the mass body 4 along with
The side portion on the side is elastically supported. The mass body 4 is covered with the film-shaped covering portion 5.

In the present embodiment, the mass body 4 generally has an arrow P at the time of resonance.
It vibrates with vibration in the P1 and P2 directions. At this time, the elastic leg portion 2 is compressed and stretched, and the elastic leg portion 3 is sheared. This is because the elastic leg portion 3 extends outward from the side surface portion of the mass body 4 and is interposed between the vibration system and the side surface portion. The spring constant (compression / tension spring constant) of one elastic leg portion 2 in the vibration direction of the mass body 4 is K1, and the supporting mass of the mass body 4 supported by the elastic leg portion 2 is M1.
Let K2 be the spring constant (shear spring constant) of the other elastic leg 3 in the vibration direction of, and M2 be the supporting mass of the mass body 4 supported by the elastic leg 3, the spring constant K1 and the supporting mass M1.
The ratio of and is set to be larger than the ratio of the spring constant K2 and the support mass M2. That is, since K1 is considerably larger than K2, (K1 / M1) is set to be considerably larger than (K2 / M2).

Here, since the spring constant K2 of the elastic leg portion 3 is considerably smaller than the spring constant K1 of the elastic leg portion 2, the natural frequency of the elastic leg portion 3 side becomes lower than the natural frequency of the elastic leg portion 2 side. Therefore, in the first embodiment, when the frequency of the vibration system gradually increases, first, the elastic leg portion 2 having a large spring constant is used as a fulcrum, and the elastic leg portion having a small spring constant is located on the portion 4b side of the mass body 4. 3 resonates in the direction of arrow P1.

Then, as the frequency increases, the portion 4a of the mass body 4 resonates in the direction of arrow P2 via the elastic leg 2 with the elastic leg 3 as a fulcrum. That is, as the frequency changes, the part 4a of the mass body 4 resonates mainly, and the part 4b resonates mainly. Therefore, it is advantageous to widen the frequency range of the dynamic damper for obtaining the damping effect as compared with the conventional case.

Further, since the damping effect can be exerted in a wider frequency range than the conventional one, even if the spring constant of the elastic legs 2 and 3 changes due to the temperature change due to the change of the operating environment temperature of the dynamic damper, the dynamic damper It is possible to reduce the influence of temperature change on the vibration damping action.

In the first embodiment described above, when the X-axis is the frequency and the Y-axis is the response magnification, the characteristic line is schematically shown. The vibration system, the portion 4a on the elastic leg 2 side, the elastic leg 2 Corresponding to the portion 4b on the third side, generally, three peaks of the characteristic line are generated.

In a special example, the planar shape of the mass body may be a triangular shape, and elastic legs having different spring constants may be provided at the respective corners of the triangular shape. Depending on the case, the planar shape of the mass body may be a disk shape, and a large number of elastic leg portions having different spring constants may be arranged in parallel along the circumferential direction of the disk shape. Also in this case, a wide-area dynamic damper can be provided as in the above-described embodiments.

[Operation and Effect of the Invention] In the present invention, when harmful vibration is excited in the vibration system, the mass body of the dynamic damper resonates. This suppresses harmful vibrations of the resonance system.

According to the present invention, it is possible to provide a dynamic damper that exhibits a damping effect in a wide frequency range.

Especially, since the frequency range for damping effect can be widened,
Even if the spring constant of the elastic leg changes due to the change in the operating environment temperature of the dynamic damper, the damping effect that is less affected by the temperature change can be expected.

[Brief description of drawings]

FIGS. 1 and 2 show a first embodiment of the present invention.
The figure shows a side view of the dynamic damper, and Fig. 2 shows A in Fig. 1.
It is sectional drawing which follows the -A line. In the figure, 2 is an elastic leg portion, 3 is an elastic leg portion, and 4 is a mass body.

Claims (1)

[Claims] 1. At least two elastic legs fixed to a vibration system, a surface elastically supported by the elastic legs, and a surface facing the vibration system, and an edge of the surface facing the vibration system. In the dynamic damper including one mass body having a side surface portion, the elastic leg portion is interposed between the vibrating system and the facing surface on one end side of the facing surface of the mass body, and vibrates. At least one first elastic leg portion that compresses and stretches in accordance with, and the vibration system and the side surface portion that extend outward from the side surface portion of the mass body at the other end side on the facing surface. A second elastic leg portion that is interposed between the elastic member and the second elastic leg portion, and the ratio between the spring constant of the first elastic leg portion and the supporting mass supported by the first elastic leg portion is It is larger than the ratio of the spring constant of the second elastic leg and the supporting mass supported by the second elastic leg. Dynamic damper characterized in that it is a constant.