JP6709899B2 - Blower fan and blower unit using the same - Google Patents

Description

The present invention relates to a centrifugal turbo blower fan and a blower unit including the blower fan, a fan case, and a motor.

As a conventional centrifugal turbo blower fan, ones shown in FIGS. 11 and 12 are known. The blower fan of FIG. 11 includes a main plate 54 to which the rotation shaft of the motor is fixed, a sub plate 52 opposed to the main plate 54, and fan blades 53 arranged between the main plate 54 and the sub plate 52. There is. When the blower fan is rotated counterclockwise along with the rotation of the motor, air is sucked into the opening of the sub plate 52 and is radially discharged toward the rear edge of the fan blade 53. There is.

A cutout portion 55 is provided at a rear edge portion of the fan blade 53 on the side of the sub plate 52 so that a gap is provided between the fan blade 53 and the sub plate 52. Due to this gap, the local flow velocity is increased, the pressure fluctuation value with the tongue of the case is reduced, and the blade passing frequency is reduced. Further, since the position of the cutout portion 55 is a portion where the blade performance is low, even if there is a gap, the air blowing performance is hardly deteriorated (see Patent Document 1).

The blower fan shown in FIG. 12 reduces the blade passing frequency in the same manner as described above, but has a cutout portion 65 at the rear edge of the fan blade 63 on the main plate 64 side. The notch portion 65 reduces the pressure fluctuation value that occurs when passing near the case, and reduces the blade passing frequency (see Patent Document 2).

JP, 2011-058442, A JP-A-63-289295

In order to achieve low noise in the blower unit, there are many factors in the blower fan and the fan case, and noise can be improved by the shapes of the blower fan and the fan case. Generally, in order to reduce noise, the distance between the blower fan and the tongue of the fan case must be secured at about 10% of the outer diameter of the fan. Due to the size limitation of the fan case, if the distance between the blower fan and the fan case cannot be 10% or more of the outer diameter of the fan, a noise problem may occur. However, although the noise can be improved by increasing the distance between the blower fan and the fan case, there is a problem that the blowing ability is reduced.

The blower fans disclosed in Patent Documents 1 and 2 can reduce the fan noise without reducing the blowing ability, but for that purpose, the construction of the auxiliary plate is essential.

The present invention has been made in view of the above-mentioned conventional problems, and has a low noise effect in a configuration of a blower fan without a sub-plate, and there is no limitation on the shape of the main plate, and the blower fan has a fan outer diameter of 10% or less. It is an object of the present invention to provide a blower unit that achieves a low noise effect even when the distance between the fan case and the fan case cannot be secured.

In order to achieve the above-mentioned object, the blower fan of the present invention has a main plate to which a rotating shaft is fixed and a main plate that is curved so that both ends are located rearward with respect to the central part in the rotational direction, and the rotational direction It has a plurality of blades including a rear edge portion protruding from the main plate in the opposite direction, and a notch is provided on the main plate side of the rear edge portion, and the opposite side of the blade where the main plate is located is open. It is characterized by The size of the notch is preferably 0.8<(c/d)<0.96, where c is the minimum diameter of the blade on the main plate side and d is the maximum diameter of the blade. The height of the cutout is 1.0<(b/a)<2.5, where a is the dimension on the main plate side and b is the dimension on the side opposite the main plate with the maximum diameter of the blade as the boundary. desirable.

The blower unit of the present invention includes the blower fan described above, a fan case, and a motor. The fan case has a suction port that faces a surface of the main plate on which the plurality of blades are located, and a blowout port that is positioned in a direction intersecting the rotation axis. The motor rotates the blower fan. Further, the shortest distance between the blower fan and the tongue of the fan case is set to 10% or less of the diameter of the blower fan.

With this configuration, noise performance can be improved by reducing the blade passing frequency without substantially reducing the blowing capacity. A remarkable effect can be exhibited when the distance between the fan and the tongue of the fan case is 10% or less of the outer diameter of the fan.

According to the present invention, a blower unit that uses a blower fan that does not form a sub-plate can achieve low noise without lowering the blowing ability.

The block diagram of the ventilation unit in embodiment of this invention. Vertical sectional view of the blower unit The perspective view of the ventilation fan in embodiment of this invention. Side view of the fan Diagram showing the flow of wind on the surface of the blower fan blades Diagram showing the relationship between c/d and the static pressure that can be blown from the blower unit (A) Diagram showing pressure state when c/d is 0.95 (b) Diagram showing pressure state when c/d is 0.98 The figure which shows the relationship between b/a and the air volume which can be ventilated from a ventilation unit. The figure which shows the pressure state when b/a is 2.33, and the figure which shows the pressure state when b/a is 3.0. (A) Noise spectrum diagram when a blower fan according to the embodiment of the present invention is used (b) Noise spectrum diagram when a conventional blower fan is used Perspective view of a conventional blower fan Perspective view of another conventional blower fan

Hereinafter, embodiments of the present invention will be described with reference to FIGS.

FIG. 1 is a configuration diagram of a blower unit, and FIG. 2 is a sectional view thereof. FIG. 3 is a perspective view of the blower fan of this embodiment, and FIG. 4 is a schematic side view of the blower fan.

The blower unit is composed of at least a cochlear fan case 10 and a blower fan 11 whose inner air flow path is driven to rotate by a motor 14. By the rotation of the blower fan 11, air is sucked from the suction port 13 and the sucked air is discharged to the air outlet 12. If such a blower unit is mounted on, for example, an air circulation path for circulating cold air in the refrigerator, the inside of the refrigerator can be cooled by combining it with some cooling means.

As shown in FIG. 3, the blower fan 11 includes a flat main plate 21 having a fixed rotating shaft and a main plate 2
1 is a centrifugal turbofan in which a plurality of fan blades 22 curved rearward with respect to the rotation direction are arranged. A notch 23 is provided at the rear edge of the fan blade 22 on the main plate side, and the diameter of the main plate 21 is smaller than the maximum outer diameter of the fan blade 22. It should be noted that a sub plate unlike the conventional example is not provided.

In this embodiment, the distance e (see FIG. 2) that is the closest to the tongue portion 15 of the fan and the fan case is 5 mm that is 10% or less of the maximum diameter d of the blower fan, and the distance e is set to reduce noise. It does not have a widely known configuration that it should be 10% or more of the maximum diameter d.

With the above-described configuration, it is possible to reduce the pressure difference between the blower fan and the fan case when passing near the fan case, which is the cause of the blade passing frequency sound. Further, since the position of the cutout portion is a portion where the blade performance is low, even if the cutout portion has the cutout portion, the blowing performance is hardly deteriorated. The blower fan 11 can be made of sheet metal, and when made of resin, it can be manufactured at low cost because it does not require an undercut shape.

The blower fan configured as described above and the blower unit using the blower fan will be described in detail.

When the air that has flowed in from the center of the blower fan 11 flows between the plurality of fan blades 22 provided, the air flows along the fan blades 22 toward the trailing edge side.

Here, FIG. 5 shows the results of analysis of the air flow on the fan surface of the blower fan according to the present embodiment and the fan surface of the blower fan in the case where the cutout portion is not provided by using the numerical fluid analysis (CFD). FIG. 5A shows the flow of the blower fan in the present embodiment, and FIG. 5B shows the flow of the blower fan when the cutout is not provided.

As shown in FIG. 5(b), the flow of air is small at the end of the fan blades 22 on the main plate side of the fan blades, and even if a cutout is provided in that portion, the reduction of the blowing performance should be minimized. You can

In the present embodiment, since the fan blade has a cutout at the bottom of the fan blade where the end of the fan blade is closest to the fan case, the space between the fan and the fan case (corresponding to the distance e) is increased. It is possible to reduce the pressure between the fan and the fan case as a result.

It is known that the pressure difference generated every time the blower fan passes through the tongue portion of the fan case becomes the blade passing frequency sound, and reducing the pressure fluctuation is effective for reducing the blade passing frequency sound.

As shown in FIG. 4, the size of the cutout 23 in the present embodiment is 0 when expressed by the ratio of the minimum diameter c of the cutout (corresponding to the diameter of the main plate) and the maximum diameter d of the fan blades 22. .8<(c/d)<0.96. Further, the height of the cutout 23 is 1.0<(b/a)<2.5 when it is represented by the ratio of the upper dimension a and the lower dimension b of the fan blade, with the maximum diameter of the fan blade as a boundary. I am trying.

If both exceed this range, an effect can be expected with respect to blade passing frequency noise, but there is a risk that the blowing performance of the blower fan will be reduced, resulting in an increase in fan speed and a decrease in fan efficiency. Inevitable.

FIG. 6 is a graph showing changes in the ratio of c/d and the static pressure that can be blown by the blower unit. When c/d is 0.8 or less, the generated static pressure is about 20% lower than the static pressure when c/d is 0.96, and the air blowing performance is significantly reduced. When c/d is 0.96 or more, the pressure between the fan and the fan case rises poorly, which is not preferable.

When the pressure between the fan and the case is high, noise tends to increase. FIG. 7 shows pressure states when c/d is 0.95 and when it is 0.98. Pressure points of 4 [Pa] or more are painted black. In the case of 0.98, it can be seen that the region of pressure increase is large.

Next, FIG. 8 is a graph showing a change in b/a ratio and the amount of air that can be blown from the blowing unit. When b/a is 1.0 or less, the generated air volume is about 20% lower than the air volume when b/a is 2.5, and the air blowing performance is significantly reduced. When b/a is 2.5 or more, the pressure between the fan and the fan case rises poorly, which is not preferable.

When the pressure between the fan and the case is high, the noise becomes loud. FIG. 9 shows pressure states when the b/a ratio is 2.33 and when it is 3.0. The pressure points of 5 [Pa] or more are painted black. It can be seen that the region of pressure increase is large in the case of 3.0.

Here, the noise characteristic result in this embodiment is shown in FIG. FIG. 10A shows the result when the blower fan of this embodiment with c/d=0.95 and b/a=2.3 is used, and FIG. 10B shows a blower fan with no cuts. Is the result when is used. Since the number of fan blades is 13 and the rotation speed is 1580 rpm, the blade passing frequency exists near 340 Hz which is the NZ component. 340 Hz is calculated by the number of fan blades 13×1580 rpm/60 (rps).

As shown in the figure, when the blower fan of this embodiment was used, a noise reduction effect of about 5 dB(A) was obtained as compared with the case of using the blower fan having no cutouts.

The blower unit of the present invention can be applied to blower units of various electric devices such as refrigerators and air conditioners.

10 Fan Case 11 Blower Fan 12 Outlet 13 Suction Port 14 Motor 15 Tongue 21 Main Plate 22 Fan Blade 23 Missing

Claims (6)

A main plate to which a rotary shaft is fixed, and a rear edge portion that is curved so that both end portions are located behind the central portion with respect to the rotation direction of the main plate, and that protrudes from the main plate in a direction opposite to the rotation direction. A blower fan, characterized in that it has a plurality of blades including, and that a notch is provided on the trailing edge portion on the side of the main plate, and the opposite side of the blade on which the main plate is located is open. The size of the cutout portion is 0.8<(c/d)<0.96, where c is a minimum diameter of the blade on the main plate side and d is a maximum diameter of the blade. The blower fan according to item 1. The height of the cutout is 1.0<(b/a)<2., where the dimension on the main plate side is a and the dimension on the anti-main plate side is b, with the point of the maximum diameter of the blade as a boundary. The blower fan according to claim 1, wherein the blower fan is 5. A main plate to which a rotary shaft is fixed, and a rear edge portion that is curved so that both end portions are located behind the central portion with respect to the rotation direction of the main plate, and that protrudes from the main plate in a direction opposite to the rotation direction. Having a plurality of blades, including a notch on the side of the main plate of the trailing edge, and a blower fan that opens the opposite side of the blade where the main plate is located ,
A fan case having a suction port facing a surface of the main plate on which the plurality of blades are positioned, and a blower port positioned in a direction intersecting the rotation axis ,
And a motor for rotating the blowing fan,
A blower unit, wherein the shortest distance between the blower fan and the tongue of the fan case is 10% or less of the diameter of the blower fan . The size of the cutout portion is 0.8<(c/d)<0.96, where c is a minimum diameter of the blade on the main plate side and d is a maximum diameter of the blade. The blower unit according to item 4. The height of the cutout is 1.0<(b/a)<2., where the dimension on the main plate side is a and the dimension on the anti-main plate side is b, with the point of the maximum diameter of the blade as a boundary. The blower unit according to claim 4, wherein the blower unit is 5.