JPS62277044A - Silencer for rotary electric machine - Google Patents

Abstract

PURPOSE:To reduce the leakage of a noise from a vent port by refracting a sound generated by the rotation of a cooling fan by an acoustic lens in a direction different from the port, and attenuating the energy of the sound in a sound absorber. CONSTITUTION:When a fan 4 rotates, atmospheric air is sucked from a suction port 7a into an air guide cover 5, diffused from a diffuser 8a toward the outer periphery of a rotary electric machine body 1, thereby cooling the body 1. At this time, the sound of the fan is generated by the rotation of the fan 4. The sound of the fan is refracted by an acoustic lens 9 in a direction different from the diffuser 8a, and absorbed by a sound absorber 18 provided in the refracting direction. Thus, it can prevent the sound of the fan from being leaked from the diffuser 8a on the stream of the air, thereby sufficiently reducing the sound level.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention relates to a muffling device for a rotating electric machine that reduces noise leaking from an air guide cover that covers a cooling fan. .

(Prior art) Conventionally, a cooling fan is attached to a rotating shaft protruding from the outside of a rotating electric machine body, and a wind guide cover is provided to cover the cooling fan, and the wind generated by the cooling fan is transferred to the wind guide cover. There is a rotating electrical machine configured to cool the rotating electrical machine main body by discharging air from a ventilation hole onto the outer circumference of the rotating electrical machine main body. In order to reduce the noise leaking from the air guide cover, a sound absorbing member made of porous plastic, glass wool, felt, etc. in the shape of a flat plate is attached to the inner surface of the air guide cover. there were.

By the way, the noise coming from the air guide cover is mainly caused by the sound generated by the rotation of the cooling fan (hereinafter referred to as "fan noise"). It tends to propagate toward the mouth. For this reason, there is a large proportion of the fan sound that is not absorbed by the sound absorbing member on the inner surface of the air guide cover, but rather rides on the flow of the wind and leaks out from the ventilation opening of the air guide cover, resulting in increased noise.

(Problems to be Solved by the Invention) As mentioned above, with the conventional structure, it is not possible to prevent the sound carried by the wind flow from leaking directly from the ventilation holes of the wind guide cover, so it is not possible to sufficiently reduce noise. There was a problem in that it was not possible to do so.

The present invention aims to solve these problems,
Therefore, the purpose is to develop a muffler for rotating electric machines that can sufficiently reduce noise.

[Structure of the Invention] (Means for Solving the Problems) The noise reduction device for a rotating electrical machine of the present invention includes an acoustic lens provided in the air guide cover so as to be located in the flow path of the air generated by the cooling fan. The acoustic lens is configured to refract the propagation direction of K during rotation of the cooling fan in a direction different from that of the ventilation opening of the air guide cover, and is located within the air guide cover in the direction of sound refraction by the acoustic lens. A sound absorbing section is provided.

(Function) The sound generated by the rotation of the cooling fan passes through the acoustic lens and is refracted in a direction different from that of the ventilation opening of the air guide cover. Furthermore, since the sound absorbing section is provided in the direction in which the sound is refracted, the sound after passing through the acoustic lens is directed toward the sound absorbing section and is absorbed by the sound absorbing section.

(Example) Hereinafter, a first example of the present invention will be described based on FIGS. 1 to 3. Reference numeral 1 denotes a rotating electrical machine main body, which has a large number of cooling fins 2 formed on its outer periphery, and a rotating shaft 3 that protrudes to the outside.
A cooling fan 4 is attached to one end. Reference numeral 5 denotes an air guide cover attached to the main body 1 of the rotating electric machine so as to cover the cooling fan 4. A protective net 6 is disposed in the opening of a partition wall 5a formed inside the cover, and the air guide cover 5 The inside of the cover 5 is divided into an intake chamber 7 and a ventilation chamber 8 on the cooling fan 4 side. An intake lower a is formed in the lower part of the intake chamber 7,
On the other hand, an air outlet 8a serving as a ventilation opening is formed between the outer circumferential portion of the ventilation chamber 8 and the rotating electrical machine main body 1, and air is blown to the outer circumferential portion of the rotating electrical machine main body 1 from this air outlet 8a.

9 is an acoustic lens provided in the air guide cover 5 so as to be located in the flow path of the air generated by the cooling fan 4. In this embodiment, the acoustic lens 9 has an annular shape with a convex lens cross section. It is arranged around the outer periphery of the cooling fan 4, and is fixed by a fixing member 10 provided on the partition wall 5a and a fixing part 11 provided on the rotating electric machine main body 1. The specific configuration of this acoustic lens 9 is as shown in FIG.
2 are placed side by side at a predetermined interval in the J° direction of the axis, and each Taber cylindrical body 12 is attached to the support piece 13.
．． The tightening is fixed according to 14.15. In this case, the outer circumferential side of the passage 16 formed between each Taper cylindrical body 12 is inclined toward the outlet 8a as shown in FIG.
As a result, the air from the cooling fan 4 is blown out through each passage 16 toward the outlet 8a, while the propagation direction of sound passing through each passage 16 is bent in a direction different from that of the outlet 8a.

Furthermore, in this embodiment, each passage 16 is formed by forming the outer circumference of the acoustic lens 9 into an arc shape, that is, a convex lens shape.
The refraction direction of the sound is concentrated on a predetermined annular region within the wind guide cover 5, and this is made to be the focal point of the sound. R
The specific design method of the fi lens 9 is provided by the Acoustical Society of Japan, B.
As described on pages 359 and 360 of 7, 7 Performance Results (October 1982), the sound waves enter the population of each passage 16 of the acoustic lens 9 and then reach the focal point. The length of the passage 16 is appropriately set so that the length of the passage is the same no matter which passage 16 is passed through. On the other hand, a sound absorbing member 17 made of, for example, glass wool, rock wool, felt, foamable synthetic resin, etc. is pasted on the inner peripheral surface of the air guide cover 5 and the partition wall 5a.

Of the inner circumferential surface of the air guide cover 5, an annular four part 5b is formed to surround the acoustic lens 9 in a part located in the direction of sound refraction by the acoustic lens 9. The sound absorbing portion 18 is formed by filling the sound absorbing portion +417 and increasing the thickness of the sound absorbing portion 17 in this portion. In this embodiment, the position of the sound absorbing section 18 is made to match the focal point of the acoustic lens 9.

Next,” - note! The effect of A formation will be explained. When the cooling fan 4 rotates, outside air flows from the intake lower a to the wind guide cover 5.
The air is sucked into the interior of the rotating electrical machine, passes through each passage 16 of the acoustic lens 9, and is blown out from the air outlet 8a toward the outer circumference of the rotating electrical machine main body 1, thereby cooling the rotating electrical machine main body 1. At this time, fan noise is generated by the rotation of the cooling fan 4. Although this fan noise is radiated in all directions around the cooling fan 4, it tends to propagate particularly in the direction of the wind flow. Therefore, the fan noise mainly comes from the cooling fan 4.
It propagates along the wind flow in the direction of the outer periphery of the acoustic lens 9 and passes through each passage 16 of the acoustic lens 9. In this case, the sound waves will follow a path as shown in FIG. That is, when it is assumed that single waves 81 to S5 of the fan sound are simultaneously incident on the inner peripheral surface of the acoustic lens 9, the sound waves 81 to S5 pass through each passage 16 in the acoustic lens 9, and the air outlet 8'a is It is refracted toward focal points P located in different directions. At this time, since the lengths of the passages 16 are different, the sound waves 51-S incident on the passages 16 produce a phase difference at the exits of the passages 16 due to the difference in their propagation distances. Here, if the length of the path 16 through which the 'g-wave S2 passes is, for example, one wavelength, when the sound waves 61 to S5 travel a distance equivalent to one wavelength, it is indicated by 81' to S, + in the figure. When it reaches the circular arc surface and travels a distance corresponding to two wavelengths, it reaches the circular arc surface indicated by Si' to S and 1 in the figure, and when it travels a distance equivalent to three wavelengths, it reaches the focal point P. Here, for convenience of explanation, the distance to the focal point P is assumed to be three wavelengths, but the same holds true if the distance is four wavelengths or more. In this way, after passing through the acoustic lens 9, the fan sound is refracted in a direction different from that of the air outlet 8a and is focused at the focal point P of the acoustic lens 9. Since the sound absorbing portion 18 with increased noise is disposed, the sound energy is efficiently attenuated by the sound absorbing portion 18, thereby preventing leakage of fan sound from the one-half circular opening 8a.

In this embodiment, since the sound absorbing member 17 is attached to the entire inner peripheral surface of the air guiding cover 5, the sound that does not pass through the acoustic lens 9, that is, the sound that does not pass through the acoustic lens 9, that is, the sound that passes through the protective net 6 and enters the intake chamber 7. The sound is absorbed by the sound absorbing member 17 on the intake chamber 7 side. In this case, the sound directed toward the intake lower a side will go against the wind flow, and the energy of the meter will be attenuated to some extent by the wind flow, so even if the sound is absorbed by the sound absorbing member 17, the fan noise from the intake lower a will be reduced to a certain extent. leakage can be suppressed to a sufficiently low level.

According to the above embodiment, the fan sound is refracted by the acoustic lens 9 in a direction different from that of the air outlet 8a, and the sound is absorbed by the sound absorbing section 18 provided in the direction of refraction. It is possible to prevent leakage from the air outlet 8a as much as possible, and to achieve sufficient noise reduction.

Further, in the embodiment 1-, the g-sounding lenses 9 are configured in an annular shape,
Since this is arranged so as to surround the outer periphery of the cooling fan 4, the acoustic lens 9 reliably absorbs the fan sound carried by the wind flow.
can pass through and be bent in a direction different from that of the air outlet 8a, thereby reliably preventing leakage of fan noise caused by the flow of air. Furthermore, since the position of the sound absorbing section 18 is made to match the focal point P of the acoustic lens 9, the range in which the sound absorbing section 18 is provided can be narrowed down, and the cost of the sound absorbing material for forming the sound absorbing section 18 can be reduced accordingly. Can be reduced.

FIG. 4 shows a second embodiment of the present invention.
In the embodiment, in order to smooth the flow of air inside the wind guiding cover 5, the inner circumference of the g2 lens 20 is connected to the rotating electric machine main body 1.
By configuring the side to have a tapered shape with a small diameter, each passage 16 of the acoustic lens 20 is directed toward the air outlet 8a. Also in this second embodiment, the sound absorbing portion 22 is provided in the four annular portions 19 corresponding to the focal point of the acoustic lens 20.

FIG. 5 shows a third embodiment of the present invention.
In this embodiment, in order to make the direction of sound refraction by the acoustic lens 23 farther away from the air outlet 8a than in the first and second embodiments, the inner circumference of the acoustic lens 23 is tapered such that the diameter is smaller on the partition wall 5a side. 11 are made like this. Then, the sound absorbing member 2 is placed in the annular recess 24 at the portion corresponding to the focal point of the acoustic lens 23, that is, the portion f1''1. placed near the partition wall 5a.
5 is set.

In this case, since the direction in which the sound is refracted by the acoustic lens 23 is directed further away from the air outlet 8a, it is possible to more reliably prevent the fan sound from leaking into the wind flow.

In each of the embodiments described above, the sound toward the intake lower a goes against the flow of the wind, so the energy of the sound is attenuated to some extent by the flow of the wind, and the sound absorption by the sound absorbing member 17 is sufficient to prevent the fan sound from leaking. In consideration of the JlG situation of being able to suppress the noise, an acoustic lens was not installed on the intake side of the wind flow path.

However, it goes without saying that the present invention may be configured such that an acoustic lens is also provided on the intake side, the acoustic lens is used to refract sound in a direction different from that of the intake port which is a ventilation hole, and a sound absorbing portion is provided in the direction of refraction. be.

Further, in the 1-Reporter embodiment, the sound absorbing section is located at the focal point of the acoustic lens, but the present invention is not limited to this, and for example, the sound absorbing section may be arranged closer to the acoustic lens side than the focal point. In this case, the range in which the sound absorbing section is provided may be expanded to receive all the sound refracted by the acoustic lens. In addition, in the present invention, the shape of the acoustic lens is not limited to an annular shape, but may be flat, for example, and can be modified in various ways without departing from the scope of the invention.

[Effects of the Invention] As is clear from the above description, the present invention refracts the sound generated by the rotation of the cooling fan in a direction different from that of the ventilation hole using an acoustic lens, and provides a sound absorbing section in the direction of the refraction h. Because I tried to attenuate the sound energy here,
This has the excellent effect of reducing noise leakage from the ventilation openings as much as possible, and achieving sufficient noise reduction.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is an overall longitudinal sectional front view, FIG. 2 is a partially cutaway perspective view of an acoustic lens, and FIG. 4 is a longitudinal sectional view of a main part showing a second embodiment of the present invention, and FIG. 5 is a view corresponding to FIG. 4 showing a third embodiment of the present invention. In the drawings, reference numeral 1 indicates a rotating electric machine body, 4 a cooling fan, 5 a wind guide cover, 9.20 and 23 acoustic lenses, 17 a sound absorption member, and 18.22 and 25 a sound absorption section. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. An air guide cover is attached to the rotating electrical machine main body for guiding the wind generated by a cooling fan provided outside the rotating electrical machine main body to the outer circumference of the rotating electrical machine main body, in which the air guide cover is attached to the rotating electrical machine main body. an acoustic lens located in a flow path of the air generated by the cooling fan and refracting the propagation direction of sound generated by the rotation of the cooling fan in a direction different from that of the ventilation opening of the air guide cover; A sound muffling device for a rotating electrical machine, comprising a sound absorbing portion located in a direction in which sound is refracted by the acoustic lens.