JP2656662B2 - Centrifugal blower for automobile - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reduction structure of an air conditioner for a vehicle, and more particularly to a scroll casing structure which is meaningful for noise reduction of a centrifugal blower.

INDUSTRIAL APPLICABILITY The present invention can be widely used not only for air conditioners for automobiles but also for household centrifugal blowers requiring low noise, office machines, centrifugal blowers for cooling electronic computers, and the like.

[Conventional technology]

A conventional centrifugal blower comprises a fan, a scroll casing containing the fan, and a motor for rotating the fan, as described in Japanese Utility Model Application Laid-Open No. 48-63305.
This structure sucks air from one side of the fan and discharges air in the radial direction of the fan. The scroll casing has a function of gradually restoring dynamic pressure generated by rotation of the fan to static pressure in the scroll casing. However, with this structure, no measures have been taken to reduce the air pulsation noise generated by the fan, the sound due to peeling, the turbulent sound in the scroll casing, and the like. However, as described in Japanese Utility Model Publication No. 57-24566, in-vehicle air conditioners have devised an inside / outside air switching box as an indirect means for reducing these radiated sounds. On the other hand, as described in JP-A-63-90415, noise reduction is achieved by attaching a sound absorbing material in which a non-porous elastic material is added to the surface of a porous elastic material to a scroll casing for the purpose of reducing noise. There are also some examples.

[Problems to be solved by the invention]

In the prior art described in Japanese Utility Model Application Publication No. 48-63305, the air pulsation noise generated from the fan, the vortex generation sound due to the separation, the turbulence sound in the scroll casing, etc. are generated, and the noise of the entire blower is considerably large. There was a problem of becoming large.
Also, as described in Japanese Utility Model Publication No. 57-24566, in the air conditioner for automobiles, the inside / outside air switching box is devised to improve these, so the restrictions on the vehicle mounting conditions and the structure of the inside / outside air switching box are reduced. A complicated, highly versatile and inexpensive automotive air conditioner has not been provided.

On the other hand, as described in JP-A-63-90415, this is an example in which a sound absorbing material is attached to a scroll casing for the purpose of reducing noise, but a flexible polyurethane foam generally used as a sound absorbing material has a frequency of 1000 Hz or more. Has a high sound absorption effect for high frequencies, but has little effect for low frequencies below 1000 Hz. The example described in JP-A-63-90415 states that in order to eliminate the above-mentioned problems, as a sound absorbing material, the vibration energy of sound waves having a wide range of frequencies can be absorbed by bonding two types of sound absorbing materials. I have. However, if this sound absorbing material is used, the vibration energy of the sound wave can be absorbed at a low frequency due to the use of the porous material on the surface, but the sound wave does not go to the lower layer and is reflected in reverse. The effect of the porous elastic material provided on the lower layer side is almost lost, and the effect of the porous elastic material alone cannot be obtained, so that high-frequency sound cannot be reduced. Furthermore, in order to make the most of the effect of attaching the sound absorbing material to the scroll casing, if you try to go all around the inner wall surface of the scroll casing, it is difficult to attach the curved surface and it is expensive because it can not be easily attached At the same time, there is a problem that an improvement measure against peeling after pasting is necessary because it is always in contact with the air passage surface.

Means for Solving the Problems The present invention holds a fan, a motor that rotates the fan, a first scroll casing that houses the fan and guides the direction of blowing air, and a main body of the motor. In a centrifugal blower for automobiles having a resin housing, a second scroll casing integrally formed with the resin housing and having an air reservoir formed around the first scroll casing and the second scroll casing are formed. This is achieved by connecting and fixing the scroll casings through a porous body.

Preferably, the present invention is achieved by forming a plurality of air reservoirs in the second scroll casing with intermediate partition walls.

[Action]

The flat porous body is a combination of a pulsating sound of air generated in the first scroll casing serving as a lower bottom wall surface of the centrifugal blower, a vortex sound caused by separation due to rotation of the fan, and a turbulent sound in the casing. The sound wave passes through the porous body, and reduces the middle and high frequency bands of the sound wave. Further, the sound waves pass through the plate-shaped porous body, reach the inner wall surface of the second scroll casing, are reflected, interfere with each other in the air reservoir, and reduce sound in a low frequency band.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a sectional view of the present invention. Centrifugal blower for automobile 1
Generally has an inside / outside air switching box 2 for selectively opening / closing and introducing air inside and outside the vehicle compartment at an upper portion thereof, a scroll casing 3 and a fan 4 housed in the scroll casing. It comprises a motor 5 for rotating the fan. The air outside the vehicle compartment and inside the vehicle compartment is sucked from the inside / outside air switching box 2 which is selectively opened / closed, and the scroll casing 3
Of the fan 4 introduced into the scroll casing 3 in the radial direction, and discharges the wind to the discharge port 7 of the scroll casing 3. The scroll casing has a role of converting dynamic pressure generated by rotation of the fan into static pressure.

The scroll casing 3 is a first scroll casing, and a second scroll casing 9 that covers the lower surface of the scroll casing 3 is formed by a resin housing 8 that covers and holds substantially the entire motor body 5. The second scroll casing 9 is cup-shaped and has an intermediate partition wall 9A to form an air reservoir 10 having a double structure.

An annular porous body 11 whose periphery is sandwiched by a flat frame 12 is arranged and fixed at a contact portion (divided surface) between the first scroll casing 3 and the second scroll casing 9. The first scroll casing 3 and the second scroll casing 9 are simultaneously fastened and fixed by a fastening spring 13. In this state, the central portion of the mask of the porous body 11 is supported by the intermediate partition wall 9A and does not hang down. It is preferable that the second scroll casing 9 formed integrally with the resin housing 8 avoids interference of vehicle parts when mounted on a vehicle and changes its shape arbitrarily according to a required reduction frequency described later. However, it is not always necessary to match the shape of the first scroll casing 3. The porous body 11 held by the flat frame body 12 is made of a material in which the gaps of aggregates such as fibers and fine particles and the bubbles in the foam are continuous with each other, or the same kind of activated carbon-containing elastic body or honeycomb-shaped elastic body. Of a porous body containing a deodorant. Sound waves incident on the surface of these materials propagate through the air in the gaps and enter the inside of the material, and lose their energy mainly due to viscosity and heat conduction. These are the principles of sound absorption of a porous body. In general,
If the porous body is thickened, the sound absorbing effect is increased, but the cost is increased and the molding becomes difficult. Further, the main sound absorbing band of the porous body is a middle and high frequency band, and the sound absorbing effect in a low frequency band is considerably small.

In the present invention, by providing the air reservoir 10 on the back surface of the porous body, it is possible to reduce noise in all frequency bands, and at the same time, freely select the air volume, the thickness of the porous layer, and the material to be used. It is possible to change the reduction amount.
The principle will be described below. When the fan 4 rotates, the pulsating sound of air and the vortex sound due to the separation of the blades,
In addition, various miscellaneous sounds such as turbulent sound of air turbulence are mixed,
The sound wave passes through a porous member 11 provided at a contact portion between the first scroll casing 3 and the second scroll casing 9. At that time, the sound in the high frequency band is reduced by the above-described operation. After that, the sound wave entering the space of the air reservoir 10 and entering based on the principle of the silencer is applied to the inner wall surface of the second scroll casing 9 formed by the resin housing 8.
The sound waves reflected at 14 and previously passed through the porous body 11 interfere with each other, and in particular, low-frequency bands not previously attenuated by the porous body 11 are attenuated.

As described above, by using the scroll casing in which the porous body 11 and the air reservoir 10 are combined, the reduction can be performed in all frequency bands, and the reduction amount can be freely adjusted. Further, by forming the porous body as an elastic body containing activated carbon or a porous body containing a honeycomb-like deodorant, a structure having both a deodorizing function and a sound deadening function can be obtained.

Next, an assembly structure of the second scroll casing 9 formed by the porous body 11 and the resin housing 8 will be described in detail.

FIG. 2 is an assembly diagram of the resin housing 8 holding the motor body 5 and the annular porous body 11 part. The outer periphery of the iron yoke 15 of the motor body 5 is press-fitted and fixed to a small protrusion 17 extending in the axial direction inside a cylindrical body 16 provided at the center of the second scroll casing 9. A receiving portion 18 for holding an outer peripheral portion of the porous body 11 is provided on an inner peripheral portion of the second scroll casing 9. The resin housing does not necessarily need to cover the entire circumference of the motor body. Also, the lower bottom wall surface 9B of the cup-shaped second scroll casing 9
Is located substantially at the same position as the shaft end of the motor main body 5 or at a position slightly protruding therefrom. The motor main body 5 is surrounded by the air reservoir 10 and the second scroll casing 9.

Therefore, noise radiated from the motor body 6 is absorbed and reflected by these silencer members, and is hardly radiated to the outside. On the other hand, the porous body 11 is fixed to the second scroll casing 9 with its outer peripheral portion sandwiched between the flat frame members 12, but when the porous body 11 is an elastic body such as urethane foam, the like. Then, ventilation holes are formed in the flat frame member 12 as necessary. The flat frame member 20 is supported by the plurality of partition walls 9A standing upright from the lower bottom wall inner surface 14 of the second scroll casing 9 similarly to the receiving portion 18. However, partition wall 9A
The flat frame 12 is unnecessary when the porous body can sufficiently support the porous body. Further, since the frame 20 is configured to be able to be separated and independent from the first scroll casing 3 and the second scroll casing, various porous bodies, for example,
Polyurethane, vinyl chloride, polyethylene, polypropylene, polyamide, polystyrene, and other synthetic resin foams, or NBR, SBR, natural rubber-based rubber foams, and glass wool can be easily assembled. Has become.

FIG. 3 shows the noise measurement result of the centrifugal blower provided with the above-mentioned silencing function. The total sound was measured at a point 1 m from the inlet. In FIG. 3, black circles indicate the conventional scroll casing, and white circles indicate the noise frequency analysis results of the scroll casing structure of the present invention. From this figure,
It can be seen that the noise has been reduced over a wide range from 200 Hz to 10 KHz. FIG. 4 shows a noise measurement result when only the porous elastic material is used. Also in this case, as in FIG. 3, black circles indicate a conventional scroll casing, and white circles indicate the results of noise frequency analysis of a structure combining a porous elastic material and a scroll casing. The difference from the previous case is that the frequency band of 1 KHz is hardly reduced, and the noise in the frequency band of 1 KHz or more is reduced. As can be seen from the results of these two experiments, when the porous body and the scroll casing were combined, the medium. The high frequency band can be reduced, and the low frequency band can be reduced by combining the air layer.

〔The invention's effect〕

According to the present invention, the first scroll casing and the second scroll casing
A porous body is provided between the scroll casings, and an air reservoir is formed by the porous body and the second scroll casing. Therefore, the pulsation sound of the air generated in the first scroll casing, and the rotation of the fan, Variously combined sound waves, such as vortex sounds generated by the separation of the blades and turbulent sounds in the casing, pass through the porous body, and the middle and high frequency bands of the sound waves are reduced. Further, the sound wave reaches the inner wall of the second scroll casing through the air layer,
The reflected light interferes with each other in the air reservoir, and the sound in the low-frequency band, which has not been reduced, is also reduced. As a result, noise in all frequency bands can be reduced. Also, when the air reservoir is formed by the second scroll casing, a part of the resin housing for holding the motor body is extended so as to cover the motor body, so that the noise from the motor body is also reduced in the second scroll casing. It is now possible to suppress noise that is silenced, reflected inside, and radiated outside. Furthermore, since the porous body can be manufactured and assembled independently and sandwiched and locked between the first scroll casing and the second scroll casing, various porous bodies can be selected.
The noise reduction amount and the reduction frequency can be arbitrarily changed, and at the same time, the noise can be easily and reliably fixed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a centrifugal blower for an automobile of the present invention, FIG. 2 is an assembly view of a resin housing for holding a motor main body of the present invention, a motor main body, and a porous body portion, and FIG. FIG. 4 is a diagram showing a noise measurement result of the added centrifugal blower, and FIG. 4 is a diagram showing a noise measurement result when only the porous elastic material is used. 1 ... centrifugal blower for automobile, 2 ... box for switching between inside and outside air, 3 ...
... first scroll casing, 4 ... fan, 5 ...
Motor body, 8: Resin housing for holding motor body 5, 9: Second scroll casing, 10: Air reservoir, 11: Porous body.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuhiko Hashimoto, Inventor 502, Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratory, Hitachi, Ltd. (56) References JP-A-61-277900 (JP, A) JP-A-1-240797 (JP, A) JP-A-2-45130 (JP, U) JP-A-62-183847 (JP, U)

Claims (4)

(57) [Claims] 1. An automobile comprising a fan, a motor for rotating the fan, a first scroll casing for accommodating the fan and guiding a wind blowing direction, and a resin housing for holding a main body of the motor. In the centrifugal blower for motor, at least an outer peripheral portion of the motor is covered with a resin housing, and the housing is formed integrally with a second scroll casing having an air reservoir formed around the outer peripheral portion, and A centrifugal blower for an automobile, wherein the first scroll casing and the second scroll casing are connected and fixed via a porous body disposed so as to cover the air reservoir. 2. A centrifugal blower according to claim 1, wherein said second scroll casing has a plurality of air reservoirs formed by intermediate partition walls. 3. The centrifugal blower for an automobile according to claim 1, wherein the porous body is held by a scroll casing with its periphery held by a flat frame. 4. The centrifugal blower according to claim 1, wherein the porous body has an intermediate portion supported by an intermediate partition wall.