JP2014139412A - Multiblade centrifugal fan and multiblade centrifugal blower including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multiblade fan suppressing degradation in fluid noise without increasing the number of components and a multiblade centrifugal blower including the same.SOLUTION: A multiblade centrifugal fan includes: a hub 4 having a circular outer circumference; a boss portion 3 formed at the center part of the hub 4 and having a drive shaft hole 3a into which a drive shaft 2a is inserted; a blade portion 5 including a plurality of blades 5a provided on the outer circumference of the hub 4 at intervals; and a bridge 8 coupling the adjacent blades 5a. The bridge 8 is gradually thinner from a rounded front edge 8a located upstream of air flowing between the blades 5a toward a rear edge 8b located downstream of the air flowing between the blades 5a.

Description

  The present invention relates to a multiblade centrifugal fan and a multiblade centrifugal fan provided with the same.

  Conventionally, a hub attached to a drive shaft such as a motor and driven to rotate, a wing portion having a plurality of elongated blades provided at equal intervals on the outer periphery of the hub, and an end portion of the wing portion There was a multiblade centrifugal fan provided with a ring that was provided and reinforced with a spacing between the blades.

  However, in recent years, the electromagnetic vibration of the motor is transmitted to the multi-blade centrifugal fan and resonates by matching with the natural frequency of the multi-blade centrifugal fan.

  Against the backdrop of such problems, a vibration isolating member made of two plates sandwiched with rubber is supported by sandwiching a boss portion having a drive shaft hole into which the motor drive shaft is inserted, and the motor has a lot of electromagnetic vibration. An air conditioner fan that suppresses propagation to a blade centrifugal fan has been proposed (for example, Patent Document 1). Some have provided a ring between the blades to suppress the generation of noise (for example, Patent Document 2).

Japanese Patent Laid-Open No. 7-103191 ([0008], FIG. 2) JP 2000-320490 A ([0026], FIG. 1)

However, the fan for an air conditioner disclosed in Patent Document 1 has a problem in that the number of parts is increased by using the vibration-proof rubber, and therefore, it is complicated and expensive. Moreover, in the fan for an air conditioner of Patent Document 1, there is a problem that the effect of suppressing the generation of electromagnetic vibration noise is diminished due to the aging deterioration of the vibration-proof rubber.
Moreover, in the multiblade fan of patent document 2, there existed a subject that fluid noise was caused by providing a ring (bridge).

  The present invention has been made against the background of the above-described problems, and an object of the present invention is to provide a multiblade centrifugal fan that suppresses deterioration of fluid noise without increasing the number of parts and a multiblade centrifugal fan including the same. And

  A multi-blade centrifugal fan according to the present invention is a multi-blade centrifugal fan connected to a motor having a drive shaft, wherein an outer peripheral portion is formed in a circular hub and a central portion of the hub, and the drive shaft is inserted therein. A boss portion having a drive shaft hole, a wing portion having a plurality of blades provided at intervals on an outer peripheral portion of the hub, and a bridge connecting the adjacent blades, the bridge including the blade From the rounded front edge located on the upstream side of the air flowing between the blades, the taper gradually becomes thinner toward the rear edge located on the downstream side of the air flowing between the blades.

  A multiblade centrifugal fan according to the present invention includes the multiblade centrifugal fan of the present invention, a scroll casing in which the multiblade centrifugal fan is accommodated, and a motor having a drive shaft inserted into the drive shaft hole. It is.

  According to the present invention, since the configuration described above is provided, the deterioration of fluid noise can be suppressed without increasing the number of components.

It is a longitudinal cross-sectional view of the multiblade centrifugal blower which concerns on Embodiment 1 of this invention. It is a cross-sectional view of the multiblade centrifugal blower according to Embodiment 1 of the present invention. It is a perspective view of the multiblade centrifugal fan which concerns on Embodiment 1 of this invention. It is a fragmentary longitudinal cross-sectional view of the multiblade centrifugal fan which concerns on Embodiment 1 of this invention. It is a fragmentary longitudinal cross-sectional view of the multiblade centrifugal fan which concerns on a comparative example. It is a fragmentary longitudinal cross-sectional view of the multiblade centrifugal fan which concerns on Embodiment 2 of this invention. It is a fragmentary longitudinal cross-sectional view of the multiblade centrifugal fan which concerns on Embodiment 2 of this invention, and shows the modification of FIG.

  Below, the multiblade centrifugal fan 100 and the multiblade centrifugal fan 300 which concern on this invention are demonstrated in detail based on drawing. In addition, this invention is not limited by the following embodiment.

Embodiment 1 FIG.
FIG. 1 is a longitudinal sectional view of a multiblade centrifugal blower 300 according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view of multi-blade centrifugal blower 300 according to Embodiment 1 of the present invention.
As shown in FIGS. 1 and 2, the multiblade centrifugal fan 300 includes a scroll casing 1, a motor 2, and a multiblade centrifugal fan 100.

  The scroll casing 1 constitutes the outer wall of the multiblade centrifugal fan 300. On the upper wall of the scroll casing 1, a bell mouth 1a is provided, and a circular air inlet 1b is formed. The air inlet 1 b is an opening for introducing the air outside the multiblade centrifugal fan 300 into the multiblade centrifugal fan 300. An air outlet 1 c is formed on the side wall of the scroll casing 1. The air outlet 1 c is an opening for discharging the air introduced into the multiblade centrifugal blower 300 to the outside of the multiblade centrifugal blower 300. The air suction port 1 b is formed to face the suction side of the multiblade centrifugal fan 100.

  The multiblade centrifugal fan 100 includes a boss portion 3 to which a motor 2 having a drive shaft 2a is connected, a hub 4, a wing portion 5 having a blade 5a, and a ring 6, and is formed of, for example, resin or metal. ing. The multiblade centrifugal fan 100 is accommodated in the scroll casing 1.

  The boss 3 has a drive shaft hole 3 a into which the drive shaft 2 a is inserted, and is rotated by the rotation of the motor 2, and is formed integrally with the hub 4. The hub 4 includes a central portion 4a projecting in the axial direction in the vicinity of the boss portion 3, and a disk-shaped flat plate portion 4b extending radially outward from the central portion 4a. is there. A drive shaft hole 3a is located at the center of the central portion 4a. In addition, the boss | hub part 3 and the hub 4 may be comprised separately. Further, the central portion 4a may have a flat shape that does not protrude in the axial direction in the vicinity of the boss portion 3.

  As shown in FIG. 2, the wing part 5 includes a plurality of blades 5 a having an elongated and curved shape. The plurality of blades 5a are provided at substantially equal intervals, for example, on the outer peripheral portion of the hub 4 so that the longitudinal direction thereof is in the same direction as the axial direction of the drive shaft 2a. The blade 5a is in a state of being inclined in the radial direction so as to blow out air toward the outer peripheral flow path 1d when the blade 5a rotates. The ring 6 is provided on the air inlet 1b side (upper end side) of the wing part 5, and reinforces it while maintaining the interval between the blade 5a end parts. Thereby, each blade 5 a is connected via the ring 6. The inclination direction of the blade 5a is not limited to the radial direction as described above, and may be an axial direction.

Below, operation | movement of the multiblade centrifugal air blower 300 is demonstrated.
When the multiblade centrifugal fan 100 is rotated by driving the motor 2, an air flow as shown by an arrow A in FIG.
Specifically, by the rotation of the multiblade centrifugal fan 100, external air is introduced into the scroll casing 1 via the air suction port 1b, sucked in the direction of the drive shaft 2a, and is caused by the curved pressure surface of the blade 5a. Speed and pressure are applied. The air thus given speed and pressure is bent by a predetermined angle α and blown in the centrifugal direction from between the adjacent blades 5a, flows into the outer peripheral flow path 1d, and the kinetic energy is statically converted by the outer peripheral flow path 1d. The air is blown out of the scroll casing 1 through the air outlet 1c.

FIG. 3 is a perspective view of the multiblade centrifugal fan 100 according to Embodiment 1 of the present invention.
As shown in FIG. 3, the bridge 8 is integrally formed with the blade 5a and is provided so as to connect the adjacent blades 5a, and is formed of, for example, resin or metal. By providing the bridge 8 in this way, the natural frequency of torsional vibration can be shifted and the amplitude of the blade 5a can be suppressed. Although it is effective to change the arrangement position of the bridge 8 according to the vibration mode, it is provided in the vicinity of the center in the longitudinal direction of the blade 5a. Further, it is desirable to make the bridge 8 as large as possible in consideration of the air volume and fluid noise.

FIG. 4 is a partial longitudinal sectional view of multiblade centrifugal fan 100 according to Embodiment 1 of the present invention.
FIG. 5 is a partial longitudinal sectional view of a multiblade centrifugal fan according to a comparative example.
As shown in FIG. 4, the bridge 8 includes a leading edge portion 8a located in the inner direction of the blade 5a (upstream side of air flowing between the blades 5a) and an outer direction of the blade 5a (air flowing between the blades 5a) It has an airfoil shape (streamline shape) including a rear edge portion 8b located on the downstream side. Specifically, the front edge 8a has a semicircular round cross section, the rear edge 8b is sharper than the front edge 8a, and the bridge 8 extends from the front edge 8a to the rear edge. It gradually becomes thinner toward 8b.

  As described above, in the multiblade centrifugal fan 100 according to the first embodiment, the bridge 8 flows between the blades 5a from the rounded front edge portion 8a located on the upstream side of the air flowing between the blades 5a. The thickness gradually decreases toward the rear edge 8b located on the downstream side of the air. For this reason, compared with the rectangular bridge 8 having a constant width as shown in FIG. 5, it is possible to suppress the turbulent separation of the air at the front edge 8a, the air flow turbulence at the rear edge 8b, and the air bridge The vortex generated when flowing in the vicinity of the surface of 8 can be suppressed. Therefore, it is possible to suppress deterioration of fluid noise caused by providing the bridge 8.

Embodiment 2. FIG.
FIG. 6 is a partial vertical sectional view of multiblade centrifugal fan 100 according to Embodiment 2 of the present invention.
FIG. 7 is a partial longitudinal sectional view of the multiblade centrifugal fan 100 according to Embodiment 2 of the present invention, and shows a modification of FIG.
The bridge 8 according to the second embodiment is provided between the blades 5a in a different direction from the bridge 8 according to the first embodiment.

The angle at which air flows into the bridge 8 between the blades 5a is approximately 20 ° to 70 °, although it varies depending on the position of the blade 5a and the environment in which the multiblade centrifugal fan 300 is used. This angle is a value when the direction in which the front edge 8a is separated from the hub 4 is a positive angle with respect to a plane perpendicular to the axial direction of the drive shaft 2a.
As shown in FIG. 6, the bridge 8 of the second embodiment is arranged to be inclined by an angle β (β = 20 ° to 70 °) along the flow of air flowing into the bridge 8 between the blades 5a. Yes. That is, the angle β is determined to be the same as the angle at which air flows into the bridge 8 between the blades 5a.

  As described above, in the multiblade centrifugal fan 100 according to the second embodiment, the bridge 8 has the airfoil shape (streamline shape) shown in the first embodiment, and the bridge 8 is in the axial direction of the drive shaft 2a. The front edge portion 8a is inclined within a range of 20 ° to 70 ° in a direction away from the hub 4 with respect to a plane perpendicular to the horizontal axis. For this reason, it can suppress that the inflow of the air to the braid | blade 5a is inhibited and air peeling becomes large, and the deterioration of fluid noise can be suppressed.

  As the angle β becomes smaller than 20 ° and approaches 0 °, or as the angle β becomes larger than 70 ° and approaches 90 °, the inflow of air into the blade 5a is hindered, and the air is peeled off. There is a risk that the fluid noise becomes worse. Moreover, there is a possibility that pressure drop and air volume drop may occur due to increased pressure loss. For this reason, it is desirable that the angle β is in the range of 20 ° to 70 °.

  Further, as shown in FIG. 7, even when the bridge 8 is rectangular and the angle β is 20 ° to 70 ° as described above, the deterioration of fluid noise can be suppressed.

  The multi-blade centrifugal fan 100 according to the first and second embodiments of the present invention is useful for a multi-blade centrifugal fan used in a duct ventilation fan, a total heat exchange type ventilation device, and the like, and in particular, a blower together with a scroll casing and a motor. Suitable for multi-blade centrifugal fans.

  1 scroll casing, 1a bell mouth, 1b air inlet, 1c air outlet, 1d outer peripheral flow path, 2 motor, 2a drive shaft, 3 boss part, 3a drive shaft hole, 4 hub, 4a central part, 4b flat plate part, 5 blades, 5a blades, 6 rings, 8 bridges, 8a leading edge, 8b trailing edge, 100 multiblade centrifugal fan, 300 multiblade centrifugal blower, α angle, β angle, A air flow.

Claims (4)

A multiblade centrifugal fan connected to a motor having a drive shaft,
A hub with a circular outer periphery,
A boss portion formed at the center of the hub and having a drive shaft hole into which the drive shaft is inserted;
A wing portion having a plurality of blades provided at intervals on the outer periphery of the hub;
A bridge connecting adjacent blades,
The bridge is
The taper is gradually narrowed from a rounded front edge located on the upstream side of the air flowing between the blades toward a rear edge located on the downstream side of the air flowing between the blades. Wing centrifugal fan. The bridge is
The multiblade centrifugal fan according to claim 1, wherein the front edge portion is inclined in a direction away from the hub with reference to a plane perpendicular to the axial direction of the drive shaft. The multiblade centrifugal fan according to claim 2, wherein an inclination angle of the bridge is in a range of 20 ° to 70 °. The multiblade centrifugal fan according to any one of claims 1 to 3,
A scroll casing that houses the multiblade centrifugal fan;
And a motor having a drive shaft inserted into the drive shaft hole.

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