Patent Application
20180204668
The present invention relates to a stationary induction apparatus typified by a transformer and relates to a low noise transformer which suppresses vibration of a transformer tank to reduce the radiated sound of the tank.
The noise of a transformer is caused by vibration of a core and a coil due to magnetostriction of the core or an electromagnetic force acting on the coil. The vibration of the core and the coil causes a bottom surface of a tank on which the core and the coil are mounted to vibrate and this vibration is transmitted to a side surface of the tank so that the vibration of the bottom surface, the side surface and a top surface of the tank is radiated to a space as noise. Although there is a countermeasure for shutting off the noise by accommodating the transformer inside a soundproofing building of concrete or iron plate in order to reduce the radiated sound from such a transformer, there are problems in this method that an installation area and manufacturing cost increase and construction period is prolonged.
In JP-A-2002-134336, there is a structure in which a reinforcing rib of a tank bottom is separated into a central portion reinforcing rib and a peripheral portion reinforcing rib and the peripheral portion reinforcing rib is fixed to a foundation. A core as a vibration source is disposed on the central portion reinforcing rib and a tank bottom plate between the central portion reinforcing rib and the peripheral portion reinforcing rib is made to have low rigidity. Accordingly, it is said that vibration transmission from the core to a tank side surface is suppressed and the radiated sound from the tank side surface is reduced.
In the structure of fixing the entire periphery of a tank peripheral portion to a foundation in JP-A-2002-134336, since the difficulty in construction is high, there are problems that the manufacturing cost increases and the construction period is prolonged. In addition, in order to secure a strength of the tank as a pressure container while reducing the rigidity between the central portion reinforcing rib and the peripheral portion reinforcing rib, it is necessary to increase the thickness of a tank bottom plate to ensure the strength and there is a problem that to increase the thickness contradicts the reduction in the rigidity between the central portion reinforcing rib and the peripheral portion reinforcing rib.
In addition to this, the natural frequency of the tank is very large and thus it is extremely difficult to predict all the natural frequency at a design stage. As a result, in a case where a frequency of an exciting force acting on the core and the coil during actual operation coincides with the natural frequency of the tank, there is a problem that the tank resonates and the radiated sound increases.
According to the invention, there is provided a stationary induction apparatus having a tank accommodating a transformer main body therein, in which a vibration suppression steel material is provided in at least a portion in the vicinity of an edge portion on a tank bottom surface.
By installing the vibration suppression steel material, transmission of vibration of the tank bottom surface to a side surface of the tank is suppressed, the vibration of the side surface of the tank is reduced, and thus the noise is reduced.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Example 1 will be described with reference to
In the stationary induction apparatus of
In the stationary induction apparatus of
In the stationary induction apparatus, the transformer main body 3 is vibrated by the magnetostriction of the core 3a and an electromagnetic force acting on the coil 3b. This vibration causes the bottom surface 1a of the tank 1 to vibrate and is transmitted to the side surface 1b, and the vibrations of the bottom surface 1a and the side surface 1b are radiated to a space as noise.
In Example 1, a vibration suppression steel material 5 is installed by being welded to the bottom surface 1a of the tank 1. An installation position thereof is in the vicinity of a joint portion with the side surface 1b of the bottom surface 1a over the entire periphery of an edge portion of the bottom surface 1a and is between the grounding stays 2a and the grounding stay 2a which are installed in plural. As illustrated in
The vibration suppression steel material 5 suppresses the transmission of the vibration of the bottom surface 1a of the tank 1 to the side surface 1b thereof, causes the vibration of the side surface 1b of the tank 1 to reduce, and reduces the noise.
With reference to the schematic diagrams of
As in the prior art document, despite of the effect of not vibrating the side surface 1b by the lower portion of the side surface 1b being fixed to the foundation surface 8 by bolts, since the prior art has a high degree of difficulty in construction, there is a problem that manufacturing cost increases and the construction period is prolonged. In Example 1, the vibration suppression steel material 5 installed on the bottom surface 1a of the tank 1 does not need to be fixed to the foundation surface 8. Therefore, the degree of difficulty in construction is the same as in the case where the vibration suppression steel material 5 or the like is not installed, the vibration on the side surface 1b is reduced and the noise is reduced without increasing the manufacturing cost and prolonging the construction period.
As described above, the vibration suppression steel material 5 is spaced apart from the foundation surface 8. This is because an outlet 8b of the space is not closed which is the outlet of a bottom surface space 8a between the bottom surface 1a and the foundation surface 8 illustrated in
The vibration analysis result illustrated in
The acoustic analysis result illustrated in
Although the vibration suppression steel material 5 is installed on the entire periphery of the edge portion of the bottom surface 1a, the vibration suppression steel material 5 may be installed not on the entire periphery of the edge portion but on a portion of the edge portion. Although the noise reduction effect is smaller than a case where the vibration suppression steel material 5 is installed on the entire periphery of the edge portion of the bottom surface 1a, the manufacturing cost thereof can be suppressed. In addition, the shape of the vibration suppression steel material 5 is not limited to the U-shape, and even in the case of a V shape, for example, the vibration of the side surface 1b can be reduced and low noise can be realized. In addition, the vibration suppression steel material 5 may be a solid shape filled with contents other than a hollow shape. From the viewpoint of weight saving, however, it is preferable to have a hollow shape.
According to Example 1 explained above, the installation of the vibration suppression steel material suppresses the transmission of vibration of the bottom surface to the side surface of the tank, the vibration on the side surface of the tank is reduced and the noise is reduced. In addition, by installing the vibration suppression steel material, an outlet area of the space on the bottom surface is reduced compared with the structure in which the vibration suppression steel material is not installed. Accordingly, the noise (noise due to vibration of bottom surface) radiated to the side of the tank outer surface from the outlet of the space on the bottom surface is reduced.
Example 2 will be described with reference to
In Example 2, a structure in which a portion of the vibration suppression steel material 5 is made attachable and detachable is described. A vibration suppression steel material fixing portion 5a is installed by welding and a vibration suppression steel material attachable and detachable portion 5b is fixed by a bolt 5c.
Also in Example 2, the vibration of the side surface 1b can be reduced by the same action as in Example 1 and thus noise can be reduced.
In addition, the vibration suppression steel material attachable and detachable portion 5b can be replaced with one having different thickness dimension and length dimension. By replacing with one having different thickness dimension and a length dimension, the mass and the rigidity of the vibration suppression steel material attachable and detachable portion 5b can be changed. This makes it possible to change the natural frequency of the tank 1. This makes it possible to avoid resonance due to the coincidence between the exciting frequency of the core 3a and the coil 3b and the natural frequency of the tank 1.
According to Example 2 described above, in addition to the effect of Example 1, it is made possible to change the natural frequency of the tank by making a portion of the vibration suppression steel material to be made attachable and detachable. This makes it possible to avoid resonance due to the coincidence of the frequency of the exciting force of the core and the coil and the natural frequency of the tank.
Example 3 will be described with reference to
In Example 3, a closing member 6 is installed in the vibration suppression steel material 5. As the material of the closing member 6, rubber or the like is used. Since closing the entire area of the outlet 8b of the space by installing the closing member 6 has a problem of being likely to be rusted by penetration of rainwater, holes, slits and the like for ventilation are provided.
In Example 3 as well, it is possible to reduce the vibration of the side surface 1b and thus low noise can be realized. In addition, since the area of the outlet 8b of the space can be reduced, there is an effect of reducing the noise (noise due to vibration of bottom surface 1a) radiated to the side of the outer surface of the tank 1 from the outlet 8b of the space.
Further, in this example, the bottom surface space 8a and the outlet 8b of the space constitute a silencer based on the principle of Helmholtz. The sound deadening characteristics are determined by the volume of the bottom surface space 8a, and the cross-sectional area and the length of the outlet 8b of the space. This silencer has an effect of reducing radiated sound due to vibration of the side surface 1b of the tank 1.
Example 4 will be described with reference to
In Example 4, a sound absorbing material 7 is installed on the bottom surface 1a. By the sound absorbing material 7, the noise of the bottom surface space 8a can be absorbed and the noise can be reduced. Generally, the sound absorbing material 7 has a different sound absorbing rate with respect to the frequency of noise depending on the material. In this example, a material having a high sound absorbing rate with respect to the exciting frequency of the transformer is preferable. In addition, it is preferable that the sound absorbing material 7 is disposed at a position where the vibration velocity of air particles is high. In the present example, the sound absorbing material 7 is disposed at a position close to the outlet 8b of a space narrower than the bottom surface space 8a.
In Example 4 as well, the vibration of the side surface 1b can be reduced and thus low noise can be realized. In addition, since the noise of the bottom surface space 8a can be absorbed and the noise can be reduced, there is an effect of reducing the noise (noise due to vibration of bottom surface 1a) radiated to the side of the outer surface of the tank 1 from the outlet 8b of the space.
The invention is not limited to the examples described above but includes various modification examples. For example, the examples described above have been described in detail in order to explain the invention in an easy-to-understand manner and are not necessarily limited to those having all the configurations described. In addition, it is possible to replace a portion of the configuration of certain example with the configuration of another example and the configuration of another example can be added to the configuration of certain example. In addition, it is possible to add, delete, and replace other configurations with respect to a portion of the configuration of each example.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2017-003773 | Jan 2017 | JP | national |
