JPH0314093B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pendulum spring type dynamic vibration absorber.

In a pendulum spring type dynamic vibration absorber, the amplitude of the pendulum is generally large in order to absorb a large amount of energy, so special consideration must be given to the spring used. In other words, stress should be reduced so that fatigue does not occur even when used for long periods of time. On the other hand, it is also necessary that the spring constant has a certain degree of magnitude.
However, no dynamic vibration reducer has hitherto been found that can satisfy these requirements.

The object of the present invention is to provide a dynamic vibration absorber that can satisfy the above requirements.

The dynamic vibration absorber of the present invention has a weight suspended at the center of the frame via a suspension shaft, and a pair of U-shaped leaf springs are symmetrically connected at one end to the pivot of the weight suspension shaft. It is attached adjacent to the fulcrum and the other end is fixed to the wall of the frame at a position below the one end.

An embodiment of the present invention will be described below with reference to the drawings. A bracket 2 is suspended from the center of the top plate 1a of the cylindrical frame 1, and a weight hanging shaft 3 having a weight 4 at the lower end is swingably provided on the bracket. The leaf springs 6, 6 each having a U-shaped cross section are attached to the suspension shaft 3 at one end and fixed to the inner wall of the frame 1 at the other end, and are provided symmetrically with respect to the suspension shaft. In this case, the attachment point 6a to the suspension shaft 3 is adjacent to the swinging fulcrum 2a of the suspension shaft, while the attachment point 6b to the wall of the frame is located below the attachment point 6a. In other words, the distance from the swing fulcrum 2a to the attachment point 6a
The distance l ₂ to the fixed point 6b is larger than l ₁ .

With the above configuration, even if the weight 4 swings significantly, the displacement of the leaf spring 6 can be reduced because the distance l ₁ of the attachment point 6a from the swing fulcrum 2a is small. This allows the stress acting on the leaf spring to be reduced. In addition, as the weight 4 swings, a pressing force P acts on the leaf spring 6 at the attachment point 6a, and as the leaf spring 6 deforms, a force acts in the direction of the hanging shaft 3 at the attachment point 6a. A reaction force P' acts on the leaf spring 6. Then, the radius of curvature at the bending point A of the leaf spring 6 is r, the length of the straight part of the leaf spring 6 on the hanging shaft side, that is, the distance from the attachment points 6a to 6c, is l ₃ , and the leaf spring 6 on the wall side of the frame If the length of the straight line part, that is, the distance from 6b to 6d, is l ₄ , then the bending moment M _A acting on the leaf spring 6 at the bending point A is M _A =
P(l ₃ +r)−P′r, and the stress σ _A =M _A・t/2/
Becomes I. Here, t is the thickness of the leaf spring 6.
In FIG. 3, l ₃ /r is plotted on the horizontal axis and l ₄ /r is plotted on the vertical axis, and the points where the stress σ _A is constant are shown by solid lines, and the points where the spring constant k is constant are shown by broken lines. In the diagram, the spring constant k is the same at the intersection, but the stress σ _A is smaller at the intersection. This means that for U-shaped leaf springs with equal spring constants, l ₃ is large, l ₄ is small,
That is, when l ₁ <l ₂ , the stress acting on the leaf spring 6 can be further reduced. On the other hand, if the required spring constant is keq when the attachment point position is the position of the weight 4, that is l, then the spring constant k when the attachment point position is l ₁ is k = keq (l/l ₁ ) ² . Although necessary, this can be dealt with by increasing the width of the leaf spring 6.

Note that the natural frequency of the dynamic vibration reducer can be adjusted by providing the weight 4 on the hanging shaft 3 so as to be movable in the vertical direction and adjusting the distance l from the swing fulcrum. Further, by supporting the plate spring 5 at the attachment point 6a using a pin support structure, the stress acting on the plate spring 6 can be alleviated.

The dynamic vibration absorber of the present invention as described above has a required spring constant and can reduce the stress acting on the plate spring.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an embodiment of the present invention when the frame body is cut vertically, Fig. 2 is an explanatory diagram of the positional relationship of the main parts, and Fig. 3 shows l ₃ /r on the horizontal axis and l 3 /r on the vertical axis. FIG. 3 is an explanatory diagram showing the relationship between the stress σ _A of the leaf spring and the spring constant k when l ₄ /r is taken. 1... Frame body, 3... Hanging shaft, 4... Weight, 6...
...U-shaped leaf spring.

Claims (1)

[Claims] 1. A weight is swingably suspended from the center of the frame via a suspension shaft, and a pair of U-shaped leaf springs are symmetrically attached with one end to the weight suspension shaft adjacent to the swing fulcrum. A dynamic vibration absorber having the other end fixed to the inner wall of the frame at a position below the one end.