Casing for centrifugal fan

The present invention relates to a casing of a centrifugal fan for improving performance in terms of both air volume and static pressure.

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 09-228997</text></patcit>

The above-mentioned well-known prior application is also an example of measures for improving both the wind speed and air volume performance of the centrifugal fan. are doing.

<p> However, all of the conventional configurations as described above involve the addition of some kind of member, which inevitably complicates the structure, and thus has a disadvantage in terms of cost.</p>

<p> The casing of the centrifugal fan according to the present invention preferably has an arcuate surface in which the tongue of the nose portion of the discharge port expands toward the end of the discharge port.</p><p> The opening angle of the line connecting the most downstream portion of the inner peripheral arc surface of the ventilation path and the side surface of the discharge port of the nose portion tongue is in the range of 24 ° to 33 °, and is formed so as to have an arcuate surface communicating with the enlarged angle. Has been done.</p>

<p> The casing of the centrifugal fan according to the present invention realizes improvement in both air volume and static pressure performance by suppressing pressure reduction of the discharged air at the discharge port.</p>

Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view illustrating the shape of the nose portion tongue of the present invention, showing that the nose portion tongue has an arc shape that expands from the front end toward the discharge port end edge.

As is well known, the maximum static pressure of the centrifugal fan is determined by the position of the tongue from the center of the impeller, and the maximum air volume is determined by the area of the discharge port. In order to increase the area of the discharge port, an expanding arcuate surface is formed.

The expansion of the nose tongue is such that the opening angle of the line connecting the most downstream portion of the inner peripheral arc surface of the ventilation path and the side surface of the discharge port of the nose tongue with respect to the inner surface of the casing on the outer peripheral side of the ventilation path is in the range of 24 ° to 33 °. Therefore, it has been confirmed that it is effective to form an arcuate surface communicating with the enlarged angle.

Further, even in the prior art, a means for expanding the discharge port is adopted. In FIG. 2, the opening angle: θ of the line connecting the most downstream portion of the circular arc surface on the inner circumference of the ventilation passage and the side surface of the discharge port of the tongue of the nose with respect to the inner surface of the casing on the outer peripheral side of the ventilation passage is expanded by a constant angle. As shown in Fig. 4 at 27 ° and 33 ° in the practical range as the same as the prior art (a), the static pressure is increased compared to the example in Fig. 3, which is a general-purpose structure. The configuration having an arcuate enlarged surface according to the invention realizes further improvement of air volume characteristics.

The casing of the centrifugal fan according to the present invention can be widely used for the purpose of achieving both performance improvement of both air volume and static pressure by reducing the pressure of the discharged air at the discharge port.

<figref num="1">It is a front perspective schematic diagram for demonstrating the example which becomes the present invention.</figref><figref num="2">It is a front perspective schematic diagram for demonstrating an improved example in the prior art.</figref><figref num="3">It is a front perspective schematic diagram for demonstrating an example well known in the prior art.</figref><figref num="4">It is a performance comparison diagram which compares the performance by the example of an invention technique and a well-known conventional technique.</figref>

Code description

1 Casing 1-1 Suction port 1-2 Discharge port 1-3 Nose part Tongue 1-31 Enlarged arcuate surface of tongue 1-32 Enlarged plane of tongue 1-33 Parallel surface of tongue 2 Multi-wing impeller 2-1 Many Outer peripheral surface of the impeller (circular arc surface on the inner circumference of the ventilation path) θ Opening angle of the line connecting the most downstream portion of the inner peripheral arc surface of the ventilation path and the side surface of the discharge port of the tongue of the nose with respect to the inner surface of the casing on the outer peripheral side of the ventilation path R Arc diameter of the enlarged arcuate surface of the tongue