JP2005291048A - Casing for centrifugal fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress noise by smoothing the flow of air flowing toward an impeller of a multiblade impeller internally mounted from a suction port of a casing. <P>SOLUTION: The cross-sectional form of a bell-mouth provided at the peripheral edge of the suction port has a semicircular arc face gradually reduced/enlarged within a range of approximately 180° from the outer surface of the casing, or a small circular arc surface gradually reduced within a range of approximately 90° from the outer surface of the casing and a large circular arc surface gradually enlarged communicating with the edge of the circular arc surface, or a circular arc surface gradually reduced within a range of approximately 90° from the outer surface of the casing and a conical surface gradually enlarged communicating with the edge of the circular arc surface. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of a centrifugal fan casing that is effective for noise suppression.

JP H05-231393 A

  The overall configuration and function of the centrifugal fan according to the present invention is a technique deceived as seen in the above-mentioned well-known prior application examples, and will not be described in detail. For example, in the example of FIG. The bell mouth 1-1 that forms the suction port of the casing 1 has a circular arc surface 1-16 that is sequentially reduced so as to form a circular arc section from the outer surface, a so-called R shape, and a multi-blade impeller 2 that is internally provided. The tip edge close to and facing the impeller 2-1 is formed in a substantially cylindrical shape 1-17.

  As shown in FIG. 4, in the configuration of the bell mouth 1-1 according to the well-known technique described above, the pulsation of ventilation in the vicinity of the suction port accompanying the generation of the vortex 4 near the tip of the impeller 2-1 is a cause of noise. This is well known, and the above-mentioned prior application known example can be said to be an example of the improvement measure, and achieves the described effects.

  However, in the conventional configuration as described above, in order to obtain the effect realization means, various processes are inevitably added, and there is a need for measures for countermeasures / improvements against the contradicting requirements of quietness and cost reduction that do not stay. It was the actual situation.

  The casing of the centrifugal fan according to the present invention has a suction port that opens in the axial direction and a discharge port that opens in the circumferential direction so that the annular inner peripheral surface expands sequentially from the upstream side toward the downstream side. A cochlear casing that is formed, and a rotatable multi-blade impeller disposed in the cochlear casing, and the bell mouth cross-sectional shape provided on the periphery of the suction inlet of the casing is from the outer surface of the casing It is formed so as to be a semicircular arc surface that is sequentially reduced and enlarged within a range of about 180 °, or

  The bell mouth provided on the peripheral edge of the suction opening of the casing has a small circular arc surface that sequentially reduces in a range of approximately 90 ° from the outer surface of the casing, and a large circle that sequentially expands in communication with the edge of the small circular arc surface. Formed with an arcuate surface, or

  The cross-sectional shape of the bell mouth provided at the peripheral edge of the suction port of the casing is an arc surface that sequentially reduces within a range of approximately 90 ° from the outer surface of the casing, and a conical surface that sequentially expands in communication with the edge of the arc surface. It is formed to provide.

  The casing of the centrifugal fan according to the present invention realizes an improvement effect that is compatible with the contradicting requirements of quietness and cost reduction.

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

  FIG. 1 is a partial view for explaining the first embodiment of the present invention, in which air from the suction port of the casing 1 is formed on a semicircular arc surface 1-11 communicating from the outside to the inside of the bell mouth 1-1. A state in which the suction ventilation 3 in the entire impeller 2-1 of the multi-blade impeller 2 is made smooth by the accompanying flow is shown.

  FIG. 2 is a partial view for explaining a second embodiment of the present invention, in which the air from the suction port of the casing 1 communicates with the small circular arc surface 1-12 outside the bell mouth 1-1. A state in which the suction ventilation 3 in the entire impeller 2-1 of the multi-blade impeller 2 is made smooth by the flow along the circular arc surface 1-13 is shown.

  FIG. 3 is a partial view for explaining a third embodiment of the present invention. An inner conical surface in which air from the suction port of the casing 1 communicates with an arc surface 1-14 on the outer side of the bell mouth 1-1. A state in which the suction ventilation 3 in the entire impeller 2-1 of the multi-blade impeller 2 is made smooth by the flow along 1-15 is shown.

  In any of the above-described embodiments, the generation of eddy currents in the vicinity of the impeller tip in the prior art shown in FIG. 4 is suppressed. FIG. 5 shows the prior art shown by the one-dot chain line and the first embodiment shown by the solid line (FIG. 1). ), In contrast to the performance of the second embodiment (FIG. 2) indicated by a broken line, and the third embodiment (FIG. 3) indicated by a dotted line. In any embodiment, the reduction effect is realized with respect to the technology (dashed line).

  The centrifugal fan casing according to the present invention can be widely used as a centrifugal fan casing capable of achieving both noise reduction and cost reduction.

It is explanatory drawing which concerns on 1st Example which consists of this invention. It is explanatory drawing which concerns on 2nd Example which consists of this invention. It is explanatory drawing which concerns on 3rd Example which becomes this invention. It is explanatory drawing which concerns on the example which becomes a prior art. It is a figure which contrasts the performance of the example which becomes this invention, and a prior art example.

Explanation of symbols

1 Casing 1-1 Bellmouth 1-11 Semicircular Arc Surface 1-12 Outer Small Arc Surface 1-13 Inner Large Arc Surface 1-14 Outer Arc Surface 1-15 Inner Conical Surface 1-16 R Shaped Section 1-17 Cylinder Part 2 Multi-blade impeller 3 Inflow ventilation 4 Eddy current

Claims (3)

A cochlear casing having a suction port that opens in the axial direction and a discharge port that opens in the circumferential direction, and an annular inner peripheral surface that is formed so as to sequentially expand from the upstream side toward the downstream side; In a centrifugal fan casing provided with a rotatable multi-blade impeller disposed in a cochlear casing, a cross-sectional shape of a bell mouth provided at a peripheral edge of the suction port of the casing is in a range of approximately 180 ° from the outer surface of the casing. A centrifugal fan casing, wherein the centrifugal fan casing is formed to have a semicircular arc surface that is successively reduced and enlarged. A cochlear casing having a suction port that opens in the axial direction and a discharge port that opens in the circumferential direction, and an annular inner peripheral surface that is formed so as to sequentially expand from the upstream side toward the downstream side; In a centrifugal fan casing provided with a rotatable multi-blade impeller disposed internally in a cochlear casing, the bell mouth provided on the periphery of the suction inlet of the casing has a cross-sectional shape in a range of approximately 90 ° from the outer surface of the casing. A centrifugal fan casing, comprising: a small arc surface that is sequentially reduced in step (a) and a large arc surface that is in communication with an end edge of the small arc surface and that is sequentially enlarged. A cochlear casing having a suction port that opens in the axial direction and a discharge port that opens in the circumferential direction, and an annular inner peripheral surface that is formed so as to sequentially expand from the upstream side toward the downstream side; In a centrifugal fan casing provided with a rotatable multi-blade impeller disposed internally in a cochlear casing, the bell mouth provided on the periphery of the suction inlet of the casing has a cross-sectional shape in a range of approximately 90 ° from the outer surface of the casing. A centrifugal fan casing comprising: an arcuate surface that is sequentially reduced in step 1; and a conical surface that is successively enlarged in communication with an edge of the arcuate surface.