JP3161127B2 - Blower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blower, and more particularly to a fan shroud.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, in a blower provided with a fan shroud 101 on the outer periphery of an axial fan 100, fan noise caused by rotation of the axial fan 100 has been a problem. As shown in FIG. 7, the fan noise is divided into peak-shaped rotation noise existing at discrete frequencies and turbulent noise randomly present in a wide frequency range. Conventionally, turbulent noise, which is a major factor in fan noise, has been reduced.

[0003]

However, as the turbulent noise is reduced, the rotational noise becomes relatively conspicuous, and there is a problem that even if the noise overall value is the same, it is perceived as harsh. This rotational noise is generated by the fan shroud 1
01 and the like, for example, upstream of the fan shroud 101 (wind suction side)
When the opening shape is concentric with the axial fan 100, the noise is the lowest. When the opening shape is not concentric with the axial fan 100, the effective area for sucking the wind particularly near the tip of the axial fan 100 changes in the circumferential direction. Therefore, a change in ventilation resistance occurs in the circumferential direction, and the change in ventilation resistance in the circumferential direction leads to an increase in rotational noise. Therefore, when a blower is mounted on the rear side of a heat exchanger used for a vehicle or the like (suction type fan), the heat exchanger generally has a rectangular shape, so that it is inevitably upstream of the fan shroud 101. The opening shape (heat exchanger side) is also rectangular, which causes an increase in rotational noise. The present invention has been made based on the above circumstances,
An object of the present invention is to reduce rotation noise in a blower including a fan shroud in which an opening on the upstream side, which is a wind suction side, is not concentric with the fan.

[0004]

Technical idea for solving the problem Observing the flow of the wind when the upstream opening shape of the fan shroud 101 is not concentric with the axial fan 100, as shown in FIG. Due to the small opening angle α ₁ of the opening, the portion having high ventilation resistance flows in the centrifugal direction, and as shown in FIG. 9, the portion having low ventilation resistance due to large opening angle α ₁ has the axial direction wind. Flowing. Since the downstream opening of the fan shroud 101 is a portion that effectively releases the wind flow generated by the rotation of the axial fan 100 to the atmosphere, as described above, when the wind flow changes in the circumferential direction, , when the opening angle alpha ₂ of the downstream opening portion is constant, and a portion where wind flow is not along the portion along the downstream side opening occurs. Therefore, when the upstream opening shape of the fan shroud 101 is not an axial flow fan 100 and the concentric shape, in accordance with the change in the flow direction of the wind, the opening angle alpha ₂ of the downstream side opening of the fan shroud 101 circumferentially , The change in the ventilation resistance in the circumferential direction is reduced, and an increase in rotational noise can be prevented.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an axial fan for generating an airflow by rotation, and an axial fan provided on the outer periphery of the axial fan to rotate the axial fan. An introduction portion for guiding the wind generated by the introduction portion, a cylindrical portion connected to the introduction portion, an outflow portion downstream of the cylindrical portion, and an upstream opening shape of the introduction portion does not form a concentric shape with the axial fan. In the blower provided with a fan shroud, the fan shroud has an internal upstream end point A of the introduction portion, a connection point B on an internal surface between the introduction portion and the cylindrical portion, and the cylindrical portion and the outflow portion. The connection point on the inner surface side is C, the downstream end point on the inner surface side of the outflow portion is D, the angle between the straight line AB and the rotation axis of the axial flow fan is the opening angle of the introduction portion, and the straight line CD is the rotation of the axial flow fan. The angle between the axis and the When the opening angle of the introduction section is small, the opening angle of the outflow section is increased when the opening angle of the introduction section is small, and the opening angle of the outflow section is reduced when the opening angle of the introduction section is large. The technical means is that the opening angle of the outflow portion is changed in the circumferential direction according to the opening angle of the introduction portion.

[0006]

According to the blower of the present invention having the above structure, when the opening angle of the introduction portion is small and the wind flows in the centrifugal direction,
The opening angle of the outflow portion is set to be large, and when the opening angle of the introduction portion is large and wind flows in the axial direction, the opening angle of the outflow portion is set to be small. That is, by changing the opening angle of the outflow portion in the circumferential direction in accordance with the change in the flow direction of the wind generated according to the change in the opening angle of the introduction portion, the circumferential change of the ventilation resistance is reduced. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the blower according to the present invention will be described with reference to FIGS. FIG. 1 is a front view of the blower, and FIG. 2 is a side half sectional view of FIG. Blower 1 of the present embodiment
Consists of an axial fan 2, a fan motor 3, and a fan shroud 4, and is mounted on the rear side of a vehicle heat exchanger (not shown). The axial fan 2 includes a boss 2a that is driven to rotate by a fan motor 3, and seven fan blades 2b radially arranged around the boss 2a.
The fan shroud 4, as shown in FIG.
a, a cylindrical portion 4b, and an outflow portion 4c. The introduction portion 4a has a rectangular opening (see FIG. 1) whose upstream opening shape is in accordance with the outer shape of the heat exchanger, and generates wind generated by rotation of the axial fan 2 from the front of the axial fan 2. 2
To effectively lead to The cylindrical portion 4b is connected to the introduction portion 4a and forms a cylindrical shape on the outer periphery of the axial fan 2 to prevent a backflow of wind before and after the axial fan 2. The outflow portion 4c has a divergent shape downstream of the cylindrical portion 4b, and effectively releases the wind to the rear of the axial fan 2.

The fan shroud 4 has an internal upstream end point A of the introduction portion 4a, an internal connection point B between the introduction portion 4a and the cylindrical portion 4b, and an internal surface connection between the cylindrical portion 4b and the outflow portion 4c. The point is C, the downstream end point on the inner surface side of the outflow portion 4c is D,
When the angle formed by the straight line AB with the rotation axis of the axial fan ₂ is defined as the opening angle α ₁ of the introduction portion 4a, and the angle formed by the straight line CD with the rotation axis of the axial flow fan ₂ is defined as the opening angle α ₂ of the outflow portion 4c. as if the opening angle alpha ₁ of the inlet portion 4a is small to increase the opening angle alpha ₂ of the outlet section 4c, if large opening angle alpha ₁ of the inlet portion 4a is smaller the angle alpha ₂ open outflow portion 4c opening angle alpha ₂ of the outlet portion 4c is determined depending on the opening angle alpha ₁ of the change in the inlet section 4a. The opening angle alpha ₂ of the set value of the outlet section 4c for opening angle alpha ₁ of the concrete inlet portion 4a in this example are shown below. α ₂ = K−α ₁ (K = 60 °, when α ₁ <0 °, α
₁ = 0 °, α ₁ = K when α ₁ > K). Further, the airflow generated by the rotation of the axial fan 2 flows backward of the axial fan 2 while turning in the rotation direction of the axial fan 2. Therefore, in this embodiment, α ₂
The circumferential direction (theta direction) position relative to alpha ₁ in are arranged offset to [delta] = 10 ° direction of rotation (see FIG. 4).

Next, the operation of this embodiment will be described. The axial fan 2 is driven to rotate by the fan motor 3, thereby sucking wind from the front of the axial fan 2 and sending the wind to the rear of the axial fan 2. At this time, the fan shroud 4 is configured such that the upstream opening shape of the introduction portion 4a for guiding the wind to the axial flow fan 2 is not concentric with the axial flow fan 2 but a rectangular shape according to the outer shape of the heat exchanger. In particular, the effective area for sucking wind near the tip of the axial fan 2 changes in the circumferential direction. That is, the opening angle α ₁ of the introduction portion 4a in the circumferential direction.
Changes. On the other hand, the outflow portion 4c of the fan shroud 4 has an opening angle α _{2 that} is equal to the opening angle α of the introduction portion 4a.
₁ and as shown in FIG. 4, as shown in FIG. 4, when the opening angle α ₁ of the introduction portion 4 a is small, the outflow portion 4
opening angle alpha ₂ is large c, opening the inlet portion 4a angle alpha ₁
There is an opening angle alpha ₂ of the outlet section 4c becomes small at large.

Therefore, a change in the flow direction of the wind generated in response to a change in the opening angle α ₁ of the introduction portion 4a (when the opening angle α ₁ of the introduction portion 4a is small, the wind flows in the centrifugal direction at the outflow portion 4c;
When the opening angle alpha ₁ of the inlet portion 4a is large in accordance with the flow in the axial direction) by the outlet section 4c, opening of the outlet portion 4c angle alpha
_{When 2} changes in the circumferential direction, the change in the ventilation resistance in the circumferential direction is reduced, and as shown in FIG. 5, rotation noise can be reduced. FIG. 5 shows the relationship between the frequency and the sound pressure level, and the rotational noise (peak-like noise existing at discrete frequencies) is reduced by 3 to 6 dB as compared with the related art (see FIG. 7). You can see that. In the present embodiment, K = 60 ° and δ = 10 ° are set. However, even if K = 50 to 70 ° and δ = 0 to 20 °, rotation noise reduction effects can be obtained. Can be.

[0011]

According to the blower of the present invention, in accordance with the change in the flow direction of the wind caused by the change in the opening angle of the introduction section,
By changing the opening angle of the outflow portion in the circumferential direction, the change in the ventilation resistance in the circumferential direction is reduced, and as a result, rotation noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view of a blower according to the present embodiment.

FIG. 2 is a half sectional side view of the blower shown in FIG.

FIG. 3 is a partial sectional view of the fan shroud according to the embodiment.

FIG. 4 is a graph showing a relationship between an opening angle of an introduction portion and an opening angle of an outflow portion.

FIG. 5 is a graph showing the relationship between the frequency and the sound pressure level of the blower according to the embodiment.

FIG. 6 is a front view of a blower according to the related art.

FIG. 7 is a graph showing a relationship between a frequency and a sound pressure level of a blower according to the related art.

FIG. 8 is a schematic diagram illustrating a flow of wind when an opening angle of an introduction unit is small.

FIG. 9 is a schematic diagram showing a flow of wind when an opening angle of an introduction portion is large.

[Explanation of symbols]

Opening angle of the first blower unit 2 axial fan 4 opening of the fan shroud 4a introduction part 4b cylindrical portion 4c outflow section alpha ₁ introduction section angle alpha ₂ outlet portions

Claims (1)

(57) [Claims] An axial fan for generating an air flow by rotation; an introduction portion provided on an outer periphery of the axial flow fan for guiding wind generated by the rotation of the axial fan; a cylindrical portion connected to the introduction portion; It has an outflow portion downstream of the cylindrical portion,
In a blower provided with a fan shroud in which an upstream opening shape of the introduction portion does not form a concentric circle with the axial fan, the fan shroud has an inner surface upstream end point of the introduction portion as A and the introduction portion. The connection point on the inner surface side with the cylindrical portion is B,
The inner surface side connection point between the cylindrical portion and the outflow portion is C, the inner surface downstream end point of the outflow portion is D, and the angle formed by the straight line AB with the rotation axis of the axial flow fan is the opening angle of the introduction portion, the straight line. When the angle formed by the CD with the rotation axis of the axial fan is defined as the opening angle of the outflow portion, when the opening angle of the introduction portion is small, the opening angle of the outflow portion is increased, and the opening of the introduction portion is increased. The blower, wherein the opening angle of the outflow portion is changed in the circumferential direction in accordance with the opening angle of the introduction portion so as to reduce the opening angle of the outflow portion when the angle is large.