JP4777685B2 - Blower casing and centrifugal blower - Google Patents

Description

  The present invention relates to a blower casing and a centrifugal blower mainly used in a low specific speed (low flow rate) region.

  An example of a centrifugal blower will be described. A centrifugal fan that rotates by driving a motor or the like is provided in a swirl chamber in a casing. The fluid is sucked into the swirl chamber from the suction port provided in the central portion of the casing, and the fluid is moved along the swirl chamber using the centrifugal force of the fluid generated by the rotation of the centrifugal fan and discharged from the discharge port. It has become.

  Specifically, in FIG. 3A, the casing 51 has a swirl chamber 54 formed of an upper case 52 and a lower case 53. A centrifugal fan 55 is provided in the swirl chamber 54. A motor 56 is provided on the lower case 53 side of the centrifugal fan 55. A centrifugal fan 55 is assembled to the motor shaft of the motor 56 and driven to rotate. A suction port 57 for sucking fluid (air, water, etc.) is provided at the center of the upper case 52.

In FIG. 3B, a discharge port 58 is provided on the downstream side in the rotation direction of the centrifugal fan 55. In the vicinity of the discharge port 58, a tongue 59 that partitions the swirl chamber 54 and the discharge port 58 is provided. The tongue 59 prevents recirculation of the fluid discharged from the discharge port 58 into the swirl chamber 54 while sucking from the suction port 57 by the rotation of the centrifugal fan 55 and circling the swirl chamber 54. In FIG.3 (c), the tongue part 59 is formed by abutting a part of upper case 52 and the lower case 53 in an axial direction (refer patent document 1).
JP-A-11-303796

In the centrifugal blower described above, since the tongue 59 is provided at a position intersecting with the rotation surface of the centrifugal fan 55 (see FIG. 3C), the fluid that has passed through the centrifugal fan 55 directly collides with the tongue 58. As a result, periodic pressure fluctuations occur near the discharge port, which is one of noise sources.
FIG. 4 shows frequency characteristics of sound pressure generated by a centrifugal fan having a conventional structure as an example. In order to reduce this noise, generally, a technique such as changing the shape of the tongue 59 or changing the distance between the centrifugal fan 55 and the tongue 58 of the case is employed. However, if the noise level is greatly reduced, the performance of the blower such as a decrease in static pressure often decreases.

  The present invention has been made to solve these problems, and an object of the present invention is to provide a casing for a blower and a centrifugal blower that can reduce noise without lowering the performance of the blower.

In order to achieve the above object, the present invention comprises the following arrangement.
A flow formed in the swirl chamber along the rotation direction of the centrifugal fan by the rotation of the centrifugal fan housed in the swirl chamber formed by abutting the end surfaces of the upper case and the lower case. a blower casing for circulating along the road, at a site a discharge side air passage and the whirling chamber of the air path intersecting the tongue portion is provided for dividing the swirling chamber and the discharge side air passage, the tongue portion is the It is characterized in that it is formed at a position where all parts are shifted in the axial direction from the radial extension line of the centrifugal fan .
Further, in the centrifugal blower, the rotary shaft is housed in the upper case side of the swirl chamber formed by abutting the end surfaces of the upper case and the lower case, and the rotation axis is centered by the drive source provided on the lower case side. A centrifugal fan that is rotationally driven, and the blower casing of claim 1 that accommodates the centrifugal fan in the swirl chamber, wherein the fluid sucked from the axial direction by the rotation of the centrifugal fan along the rotational direction of the centrifugal fan. It is made to circulate along the flow path formed in a turning chamber, and it discharges from a discharge outlet through the said discharge side ventilation path .
Also characterized in that the discharge side air flow passage which communicates with said swirl chamber is provided with a shift to the drive source side axial direction.

If the above-described blower casing and centrifugal blower are used, the tongue portion that partitions the swirl chamber and the discharge-side air passage is formed at a position shifted in the axial direction from the fan discharge portion of the fluid. Can reduce the amount of collision with the tongue that separates the swirl chamber and the discharge-side air passage. Therefore, the generation of interference noise caused by the tongue can be reduced.
The centrifugal fan is provided in the upper case that protrudes upward by providing the discharge-side air passage connected to the swirl chamber shifted to the drive source side in the axial direction, but the drive source is relatively located on the upper case side. Therefore, a centrifugal fan with a high static pressure and a low flow rate can be provided without changing the height in the axial direction of the entire apparatus.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a best mode of a centrifugal blower according to the invention will be described with reference to the accompanying drawings. The casing for a blower and the centrifugal blower according to the present invention are preferably used when a fluid is mainly sent out in a low specific speed (low flow rate) region.

A schematic configuration of the centrifugal blower will be described with reference to FIG.
In FIG. 1A, a swirl chamber 4 is formed inside the casing 1 by abutting the upper case 2 and the lower case 3 with each other. For the upper case 2 and the lower case 3, for example, aluminum die casting is used. A centrifugal fan 6 that is rotationally driven by a motor 5 is provided in the swirl chamber 4. The motor 5 may be either a brushed motor or a brushless motor, but a brushless motor is desirable in order to reduce noise.

  In FIG. 1B, a suction port 7 is provided at the center of the upper case 2, and fluid (for example, air) is sucked into the swirl chamber 4 from the suction port 7 in the axial direction by the rotation of the centrifugal fan 6. Is done. The air sucked into the swirl chamber 4 circulates along the flow path formed in the swirl chamber 4 along the rotation direction of the centrifugal fan 6 and is discharged from the discharge port 8 through the discharge side air passage 9. It has become.

  Further, in FIG. 1C, the lower case 3 is provided with a tongue portion 10 that partitions the swirl chamber 4 and the discharge side air passage 9 at a portion where the discharge side air passage 9 and the air passage in the swirl chamber 4 intersect. It has been. The tongue portion 10 is formed at a position shifted in the axial direction from the fan discharge portion (outer peripheral portion) 11 of the fluid. Thereby, the quantity which the fluid sent out from the centrifugal fan 6 collides with the tongue part 10 can be reduced, and generation | occurrence | production of the interference noise caused by the tongue part 10 can be reduced.

  FIG. 2 is a frequency characteristic of sound pressure measured under the same conditions as FIG. 4 measured using the centrifugal fan having the structure of the present invention. In FIG. 2, it can be seen that the number of blades × the number of revolutions component (so-called NZ sound) 1.7 kHz, which is an integral multiple thereof, and the sound pressure level in the 2-3 kHz band are significantly reduced.

  In addition, since the discharge-side air passage 9 connected to the swirl chamber 4 is provided shifted in the axial direction toward the motor 5 (lower case 3 side), the centrifugal fan 6 is provided in the upper case 2 protruding upward. However, since the motor 5 is assembled to the lower case 3 side relatively shifted to the upper case 2 side, a centrifugal fan with a high static pressure and a low flow rate can be provided without changing the height of the entire apparatus in the axial direction. .

  In the present embodiment, the blower has been described. However, the fluid is not limited to air but may be a reactive fluid such as a gas or liquid for a specific purpose. Further, as the drive source, various motors can be used regardless of, for example, a motor with a brush or a brushless motor.

It is the fragmentary sectional view of a centrifugal blower, the top view which removed the upper case, and arrow AA sectional drawing. It is a graph of a sound pressure frequency characteristic. It is the fragmentary sectional view of the conventional centrifugal blower, the top view which removed the upper case, and arrow BB sectional drawing. It is a graph of the conventional sound pressure frequency characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Upper case 3 Lower case 4 Swirling chamber 5 Motor 6 Centrifugal fan 7 Suction port 8 Discharge port 9 Discharge side air passage 10 Tongue part 11 Fan discharge part

Claims (3)

A flow formed in the swirl chamber along the rotation direction of the centrifugal fan by the rotation of the centrifugal fan housed in the swirl chamber formed by abutting the end surfaces of the upper case and the lower case. A blower casing that circulates along a road ,
A tongue portion that partitions the swirl chamber and the discharge-side air passage is provided at a portion where the discharge-side air passage and the air passage in the swirl chamber intersect, and the tongue portion is partly extending in the axial direction from the radial extension line of the centrifugal fan. The blower casing is characterized by being formed at a shifted position. A centrifugal fan that is housed on the upper case side of the swivel chamber formed by abutting the end surfaces of the upper case and the lower case, and is driven to rotate about a rotation axis by a drive source provided on the lower case side ; The blower casing according to claim 1, wherein the centrifugal fan is accommodated in the swirl chamber.
The fluid sucked from the axial direction by the rotation of the centrifugal fan is circulated along the flow path formed in the swirl chamber along the rotation direction of the centrifugal fan, and discharged from the discharge port through the discharge side air passage. Features a centrifugal blower. The centrifugal blower according to claim 2, wherein the discharge-side air passage connected to the swirl chamber is provided by being shifted toward the drive source in the axial direction.

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