JP2000314394A - Blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blower capable of maintaining low noise equivalent to a fan with ring and improving a fan efficiency. SOLUTION: Each blade 4 of an impeller 2 is provided with an aileron 5. The aileron 5 is provided virtually perpendicular to a blade surface along a radial circumferential periphery of the blade 4. This aileron 5 is capable of extending a reverse flow passage, when air flows reversely through a gap between a tip of the blade 4 and a shroud 1, thus resulting in a reduction of noise caused by an eddy because the eddy generation is suppressed by a reduced reverse air flow. The total surface area of each aileron is less than the surface area of ring. This results in a suppressed rotational torque increase and improved fan efficiency, because the air amount trailed by the aileron 5 of the rotating impeller 2 is less than in the case of a fan with ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial blower.

[0002]

2. Description of the Related Art Conventionally, there is a propeller fan (axial fan) for blowing air to a heat exchanger of a vehicle air conditioner, for example.
As shown in FIG. 9A, the propeller fan includes an impeller 120 in which a plurality of blades 110 are attached around a hub 100, and a shroud 130 surrounding the outer periphery of the impeller 120. By rotating 120, for example, an air flow can be generated from below to above in FIG. 9A. However, when the impeller 120 rotates, a pressure difference is generated on both sides of the blade 110, and the pressure difference causes the tip of the blade 110 and the shroud 130.
The air flows backward through the gap (the air flow indicated by the broken line in FIG. 9A). The fan blade 1
A vortex is generated at the tip of No. 10, and the generation of the vortex causes a large noise.

As a means for reducing the noise of a propeller fan, as shown in FIG. 8, a fan 1 having a ring 140 attached to the tip of a blade 110 is used.
50 are known. According to the fan 150 with the ring, when the air flows backward due to the pressure difference between the pressure side and the suction side of the blade 110, the ring is compared with the propeller fan without the ring (the fan shown in FIG. 9A). 1
The length of the reverse flow path of the air can be lengthened by the amount corresponding to 40 (FIG. 9).
(B)). As a result, the reverse flow rate of the air is reduced and the generation of the vortex can be suppressed, so that the noise accompanying the generation of the vortex can be reduced.

[0004]

However, in the fan 150 with a ring described above, the ring 140 is
Since the entire circumference of 0 is surrounded, the surface area of the ring 140 increases. As a result, when the ring 140 rotates integrally with the impeller 120, the ring 140 entrains the surrounding air, so that there is a problem that the rotational torque increases and the fan efficiency deteriorates. The present invention has been made based on the above circumstances, and an object of the present invention is to provide a blower that can maintain the same low noise as a fan with a ring and improve the fan efficiency.

[0005]

By providing an auxiliary wing having a predetermined height with respect to the blade surface along the radial peripheral edge of the blade within the height range of the shroud,
The reverse flow path when air flows backward in the gap between the blade tip and the shroud can be lengthened. As a result, the reverse flow rate of the air is reduced and the generation of the vortex can be suppressed, so that the noise accompanying the generation of the vortex can be reduced. Further, in the present invention, the auxiliary wing is provided along the radial peripheral portion of the blade. In other words, since the auxiliary wings are provided only on the blades (the respective auxiliary wings are not connected in a ring), the total surface area of each auxiliary wing is smaller than the surface area of the ring described in the related art even if the surface area of each auxiliary wing is totaled. Is smaller. As a result, it is possible to reduce the amount of air entrained by the auxiliary wing when the impeller rotates, thereby suppressing an increase in rotational torque and improving fan efficiency as compared with a fan with a ring. The auxiliary wing is
It can be provided in any of the following. Only the pressure side of the blade, only the suction side of the blade, both the pressure side and the suction side of the blade.

[0006]

Next, a blower according to the present invention will be described with reference to the drawings. (First Embodiment) A blower of this embodiment is used as a cooling fan for blowing a refrigerant condenser of an air conditioner for a vehicle, for example, as shown in FIG. And an axial flow type in which air flows upward from below in FIG. 1 by rotation of the impeller 2. The shroud 1 has a cylindrical shape surrounding the outer periphery of the impeller 2, and the air inlet side (the lower side in FIG. 1) extends in a bell-mouth shape.

As shown in FIG. 2, the impeller 2 has a circular hub 3 attached to a rotating shaft of a motor (not shown).
And a plurality of blades 4 fixed to the outer peripheral surface of the hub 3. Each blade 4 is provided with an auxiliary wing 5 described below. The auxiliary wings 5 are means for reducing noise generated as the impeller 2 rotates.
As shown in FIG. 2, the impeller 2 is provided substantially upright with respect to the blade surface (positive pressure surface) along the radial peripheral edge of the blade surface which is on the positive pressure side when the impeller 2 rotates.

Next, the operation of this embodiment will be described. When the impeller 2 rotates in a predetermined direction (the direction of the arrow in FIG. 2) by the motor, air is sucked in from the inlet side of the shroud 1,
It is discharged from the outlet side of the shroud 1 through between the blades 4. At this time, due to the pressure difference generated on both sides of the blade 4, air flows backward from the positive pressure side to the negative pressure side through the gap between the tip of the blade 4 and the shroud 1, as indicated by the broken arrow in FIG. Noise is generated as a result.

On the other hand, in this embodiment, the noise is reduced by providing an auxiliary wing 5 at the tip of the blade 4.
Here, the noise reduction effect due to the provision of the auxiliary wings 5 and the effect of the provision of the auxiliary wings 5 on the fan efficiency were determined by experiments. The specifications of the impeller 2 used in the experiment are shown below (see FIG. 3). D (outer diameter of impeller 2): 320 φ d (outer diameter of hub 3): 120 φ H (height of blade 4): 40 mm h (height of auxiliary wing 5): 5 mm w (width of auxiliary wing 5) : 150mm

FIG. 4 shows measurement results of noise and fan efficiency generated when the impeller 2 and the fan with a ring described in the prior art are driven to rotate at a predetermined rotation speed (2200 rpm). The specification of the fan with a ring is the same as that of the impeller 2 described above, and the height of the ring is the same as the height H of the blade 4. According to this measurement result, when the above-described impeller 2 is used, a noise reduction effect substantially equal to that of the fan with a ring can be obtained, and the rotational torque is reduced more than that of the fan with a ring, thereby improving the fan efficiency. Results were obtained. Furthermore, the height h of the auxiliary wing 5
When the relationship between noise and fan efficiency was measured, as shown in FIG. 5, the effect of noise reduction was obtained most when h = 5 mm. However, as the height h of the auxiliary wing 5 increases, the impeller 2
Since the amount of air that the auxiliary wing 5 entrains when the blade rotates is increased, the fan efficiency is reduced.

(Effect of the present embodiment) According to the blower of the present embodiment, the auxiliary wing 5 having a predetermined height is provided along the radial peripheral edge of the blade 4, so that the blower shown in FIG. As in the case of the fan with a ring shown, the reverse flow path when air flows backward in the gap between the tip of the blade 4 and the shroud 1 can be lengthened (see FIG. 9C). As a result, the reverse flow rate of the air is reduced, and the generation of the vortex can be suppressed, so that the noise caused by the generation of the vortex can be reduced, and the same noise reduction effect as that of the fan with a ring can be obtained. Further, since the auxiliary wings 5 are provided only on the blades 4 (that is, the auxiliary wings 5 are not connected in a ring shape), even if the surface areas of the respective auxiliary wings 5 are summed, each of the auxiliary wings 5 has a smaller surface area than the ring surface area described in the related art. The total surface area of the auxiliary wing 5 becomes smaller. As a result, as compared with a fan with a ring, the amount of air that the auxiliary wings 5 follow when the impeller 2 rotates can be reduced, so that an increase in rotational torque can be suppressed and fan efficiency can be improved. .

(Second Embodiment) This embodiment is an example in which an auxiliary wing 5 is provided on the negative pressure side of a blade 4 as shown in FIG. In this case, as in the first embodiment, the same noise reduction effect as that of the fan with a ring can be obtained, and the fan efficiency can be improved as compared with the fan with a ring.

Third Embodiment This embodiment is an example in which auxiliary blades 5 are provided on both the pressure side and the suction side of the blade 4 as shown in FIG. In this case, as in the first embodiment, the same noise reduction effect as that of the fan with a ring can be obtained, and the fan efficiency can be improved as compared with the fan with a ring.

[Brief description of the drawings]

FIG. 1 is a sectional view of a blower.

FIG. 2 is a perspective view of an impeller.

FIG. 3 is a drawing showing a shape of an impeller (first embodiment).

FIG. 4 is a graph comparing the effect of the blower of the present invention with a fan with a ring.

FIG. 5 is a graph showing the effect of the height of the auxiliary wing.

FIG. 6 is a view showing a shape of an impeller (second embodiment).

FIG. 7 is a view showing a shape of an impeller (third embodiment).

FIG. 8 is a perspective view of a fan with a ring (prior art).

FIG. 9 is a diagram illustrating a noise generation mechanism and a noise reduction mechanism.

[Explanation of symbols]

 Reference Signs List 1 shroud 2 impeller 3 hub 4 blade 5 auxiliary wing

Claims (4)

[Claims] 1. An axial-flow blower having an impeller configured by fixing a plurality of blades around a hub, and a shroud surrounding an outer periphery of the impeller, wherein a height of the shroud is within a range. An air blower, further comprising an auxiliary wing having a predetermined height with respect to the surface of the blade along a radial peripheral portion of the blade. 2. The blower according to claim 1, wherein the auxiliary wing is provided on the pressure side of the blade. 3. The blower according to claim 1, wherein the auxiliary wing is provided on a side of a suction surface of the blade. 4. The blower according to claim 1, wherein the auxiliary wings are provided on both the pressure side and the suction side of the blade.