JPS628927B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to stationary induction electric appliances such as transformers and reactors, and particularly to a soundproofing device for reducing noise generated from a tank thereof.

Recently, as urban areas have expanded and residential areas have been built closer to substations, there has been an increasing demand for low noise static induction appliances. Most of the noise from stationary induction appliances comes from magnetostrictive vibrations generated in the iron core of the appliance, which radiate from the tank into the atmosphere through the bottom plate and insulating oil.

Soundproofing measures using concrete and steel plates have traditionally been used as noise countermeasures.
In this method, electrical equipment is placed inside a soundproof building made of concrete or iron plates to insulate or absorb sound. However, this method had various drawbacks, such as an increase in the installation area of the equipment, a prolonged construction period, and an increase in costs.

Therefore, as shown in Figs. 1 to 3, a thin plate 4 made of a thin steel plate and having a predetermined spring constant is provided around the periphery of a reinforcing stay 3 fixed to the side plate 2 of the tank 1 by welding. The present inventors have recently proposed a method of supporting the tone plate 5 and arranging an annular square weight body 6 near the boundary between the thin plate 4 and the tone plate 5 ( Unexamined Japanese Patent Publication 1986
−87306). Note that the tank 1 houses an electric appliance body consisting of an iron core 7 and a winding 8, and is filled with mineral oil 9. Further, a pushing 10 is attached to the upper part of the tank 1, and connects the winding and the external bus bar. According to this method, noise reduction can be achieved efficiently in a simple manner, and the above-mentioned drawbacks can be overcome.

However, even with the anti-vibration effect of the thin plate 4 and the weight body 6, it is difficult to sufficiently reduce the vibration transmitted to the reinforcement stay 3 and the tone plate 5, and each Vibrations were still transmitted to the plate 5 and noise was radiated, which was an obstacle to achieving further noise reduction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stationary induction electric appliance which eliminates the above-mentioned drawbacks of the prior art and can further reduce noise with a simple structure.

In order to achieve this object, the present invention provides a dynamic vibration absorber in which a weight body for a dynamic vibration absorber is supported by a support body through a plurality of elastic bodies, at least some of which have non-linear spring characteristics. This dynamic vibration absorber reduces the vibration of the heavy body.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 4 to 7. Note that in these figures, the first
The same reference numerals as those in the figures to FIG. 3 indicate the same or equivalent parts.

This embodiment differs from FIGS. 1 to 3 in that a dynamic vibration absorber 11 is attached to each corner of the annular quadrangular weight body 6. This dynamic vibration absorber 11 consists of a U-shaped housing 12 fixed to a weight body 6, and a dynamic vibration absorber 12 attached via leaf springs 13, 14, 15, and 16 between opposing surfaces of this housing 12. A weight body 17 for a vibration absorber, an adjusting plate 20 attached via leaf springs 18 and 19 between opposing surfaces of the casing 12, and a center between the adjusting plate 20 and the weight body 17 for a dynamic vibration absorber. Disc spring 21 interposed in the part
and an adjustment bolt 22 which passes through the external mustard sound plate 5, the weight body 6, the housing 12, and the dynamic vibration absorber weight body 17, and whose tip end is screwed into the adjustment plate 20.

The vibrations transmitted from the reinforcing stay 3 to the weight body 6 via the thin plate 4 and the sound plate 5 are further transmitted to the dynamic vibration absorber weight body 17 via the casing 12 of the dynamic vibration absorber 11 and leaf springs 13 to 16. It is transmitted and makes it vibrate. By the way, magnetostrictive vibrations have harmonics that are even multiples of the power supply frequency. Therefore, among these harmonics, the natural frequency of the dynamic vibration absorber weight body 17 is approximately set to the frequency at which the vibration is maximum. Then, the adjustment bolt 22 is rotated in the direction in which the disc spring 21 is compressed while it is actually vibrating.

FIG. 5 shows a typical characteristic example of the change in force with respect to displacement when the disc spring 21 is compressed. This characteristic curve can be expressed as the following equation.

F=Aδ ³ +Bδ ……(1) where F: Force δ: Compressive displacement A, B: Constant Now, since the vibration is sufficiently small compared to the compressive displacement, the spring constant k _D is given by equation (1). It becomes as shown in equation (2).

k _D = dF / d δ = 3 A δ ² + B ... (2) In other words, in Fig. 8, when the disc spring is compressed between 0 and δ ₁ , its spring constant k _D
will decrease in proportion to the square of the compressive displacement δ, as shown in equation (2). On the other hand, since the natural frequency of the dynamic vibration absorber weight body 17 is proportional to the 1/2 power of the spring constant, it ultimately decreases approximately in proportion to the compression displacement δ.

Therefore, when the adjusting bolt 22 is rotated to adjust the natural frequency of the dynamic vibration absorber weight body 17 to bring it into a resonant state, a large reaction force corresponding to the vibration will have a phase opposite to that of the vibration of the weight body 6. Therefore, the vibration of the weight body 6 is suppressed and becomes extremely small. At this time, the vibration direction of the leaf springs 13 to 16 is regulated so that a reaction force is applied to the weight body 6. When the vibration of the weight body 6 becomes extremely small in this way, the vibration of the sound plate 5 also becomes extremely small, and the sound effect of the sound plate 5 is significantly improved.

In addition, after adjusting the rotation, the adjustment bolt 22 is fixed to the tone plate 5 so as not to rotate.

According to this embodiment, the following effects can be obtained.

(1) Since the vibration of the weight body 6 can be reduced by the vibration damping effect of the dynamic vibration absorber 11, the noise effect of the sound plate 5 is increased, and the noise reduction effect is improved.

(2) Since the natural frequency of the dynamic vibration absorber weight body 17 can be changed in proportion to the first power of the compression displacement δ of the disc spring 21, the natural frequency can be easily adjusted.

(3) Since the natural frequency of the dynamic vibration reducer weight body 17 can be adjusted from the outside while it is still attached, vibrations can be reliably and easily reduced.

Note that the disc spring 21 used in the above embodiment
Instead, a coil spring with nonlinear characteristics, such as a conical spring or an unequal pitch spring, can also be used.

Furthermore, as the sound plate, it is possible to use a damping steel plate made by laminating multiple thin steel plates with plastic or joining them by spot welding, or a damping plate made of a plastic material with good damping properties. desirable. In the case of using a damping steel plate made of a plurality of thin steel plates as described above, one of the thin steel plates is extended, and this extension is made into a thin plate with the above-mentioned spring characteristics, and it is directly welded to the reinforcing stay. You can also do it.

As explained above, according to the present invention, since the dynamic vibration absorber is attached to the heavy body, the vibration of the heavy body is reduced by its vibration-proofing effect, and the sound effect of the sound plate is improved. It is possible to reduce noise. Moreover, since at least some of the elastic bodies that support the dynamic vibration absorber weight body have nonlinear spring characteristics, it becomes easy to adjust the natural frequency of the dynamic vibration absorber weight body.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional side view showing the overall configuration of a conventional low-noise transformer, Fig. 2 is an enlarged side view of the main parts of Fig. 1 viewed from the direction of arrow A, and Fig. 3 is B--B in Fig. 2. 4 is a vertical sectional side view showing the overall configuration of a transformer according to an embodiment of the present invention, FIG. 5 is an enlarged side view of the main part of FIG. 4 viewed from the direction of arrow C, and FIG. 6 is a sectional view of FIG. is the fourth
An enlarged sectional view of the dynamic vibration reducer part of the transformer shown in the figure.
FIG. 7 is a side view of FIG. 6 viewed from the direction of arrow D, and FIG. 8 is a spring characteristic diagram of the disc spring. 2...Tank side plate, 3...Reinforcement stay, 4...
Thin plate, 5...Stone plate, 6...Heavy body, 11...
Dynamic vibration absorber, 12... Enclosure (support), 13-16
...Plate spring, 17... Weight body for dynamic vibration absorber, 21...
...Disc spring (non-linear spring), 22...adjustment bolt.

Claims (1)

[Scope of Claims] 1. A plurality of structural members protruding from the side plate of the tank that houses the main body of the electric appliance are provided, and the tone plate is supported with a thin plate having spring characteristics interposed between the structural members. In a stationary induction electric appliance having a substantially annular weight body near the boundary between the thin plate and the tone plate, the weight body includes a plurality of elastic bodies at least a part of which has nonlinear spring characteristics on the support body. A stationary induction electric appliance characterized in that a dynamic vibration absorber is attached that supports a weight body for the dynamic vibration absorber via an elastic body. 2. The stationary induction electric appliance according to claim 1, wherein the elastic body having nonlinear spring characteristics is a disc spring. 3. The stationary induction electric appliance according to claim 1, wherein the elastic body having nonlinear spring characteristics is a coil spring. 4. The stationary induction electric appliance according to claim 1, further comprising means for adjusting a spring constant of the elastic body having nonlinear spring characteristics. 5. In claim 4, the weight body and the dynamic vibration absorber are arranged in a chamber formed between the side plate and the thin plate and the tone plate, and the spring constant adjusting means is arranged in the nonlinear A stationary induction electric appliance characterized in that a spring constant of an elastic body having spring characteristics can be adjusted from outside the chamber.