JPH1193893A - Centrifugal multiblade fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve air blowing capacity of a centrifugal multiblade fan, and reduce a siren sound by specifying fan outlet angles, and making a first inside radius smaller than a second inside radius. SOLUTION: In blades 71a and 71b, a first inside radius R1IN of the first inside diameter edge S1IN by the first blade 71a is made smaller than a second inside radius R2IN of the second inside diameter edge S2IN by the second blade 71b, and fan outlet angles βa and βb of the respective blades 71a and 71b are set so as to become 70 deg. to 120 deg.. Therefore, a part of centrifugal force imparted to air is converted into static pressure, and since static pressure of air blown off from a fan 72 increases, air blowing capacity can be improved by a single body of the fan 72. Since the second blade 71b is also provided on the outside diameter side of the fan 72, a dimension between the respective blades 71a and 71b does not expand as it proceeds to the external shape side from the inside diameter side. Therefore, besides improving air blowing capacity, a noise can also be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal multi-blade fan that sucks air from the direction of a rotating shaft and blows air outward, and is effective when applied to a centrifugal blower of a vehicle air conditioner. is there.

[0002]

Conventionally, a so-called sirocco fan having a fan outlet angle β of less than 60 ° has been used for a centrifugal blower of a vehicle air conditioner in order to realize a high air volume (discharge pressure) while reducing the size. (See FIG. 12). In the centrifugal multi-blade fan, the fan exit angle β is the intersection angle between the outer diameter edge S of the centrifugal multi-blade fan and the blade, and is the angle measured from the rotating forward side of the centrifugal multi-blade fan. (See FIG. 12).

[0003]

However, since the sirocco fan generates almost no static pressure by itself, the dynamic pressure of the air blown out of the sirocco fan is reduced by the spiral scroll casing that houses the sirocco fan. Need to be converted to Therefore, in a centrifugal blower using a sirocco fan, it is important to optimize the scroll casing in order to improve the blowing capacity.

However, in a vehicle air conditioner, since there are a number of dimensional restrictions when mounted on a vehicle, it is not always possible to optimize the scroll casing, resulting in a reduction in air blowing capacity. . The present invention has been made in view of the above circumstances, and has as its object to improve the blowing capacity of a single centrifugal multi-blade fan.

[0005]

The present invention uses the following technical means to achieve the above object. Claim 1
In the invention described in Item 4, the first inner radius (R1 _IN ) of the first inner diameter edge (S1 _IN ) by the first blade (71a) is equal to the second inner radius (S2 _IN ) of the second blade (71b). It is smaller than the second inner radius (R2 _IN ), and each wing (71a, 71
b) The fan exit angles (βa, βb) are 70 ° to 120 °.
°.

First, the fan exit angles (βa, βb) are:
Since it is 70 ° to 120 °, a part of the centrifugal force applied to the air is converted into static pressure by each blade (71a, 71b). Therefore, the static pressure of the air blown out from the centrifugal multi-blade fan while passing between the respective blades (71a, 71b) increases, and the centrifugal multi-blade fan alone can improve the blowing capacity.

Second, since the first inner radius (R1 _IN ) is smaller than the second inner radius (R2 _IN ), the air flow from the inner diameter side to the outer diameter side of the centrifugal multi-blade fan is reduced. When viewed along, the number of blades decreases on the inner diameter side of the centrifugal multi-blade fan, while the number of blades increases on the outer diameter side. Therefore, the suction resistance on the first inner peripheral edge (S1 _IN ) side,
Further, since the wind speed distribution curve can be made smooth while reducing the friction loss of the air flowing between the first and second blades (71a, 71b), it is possible to reduce the siren sound described later.

In the present invention, the first inner radius (R1 _IN )
Is smaller than the second inner radius (R2 _IN ), the second blade (71b) is located on the outer diameter side of the centrifugal multi-blade fan. The dimensional change can be reduced. Therefore, the loss of the dynamic pressure when the air flows between the blades (71a, 71b) can be reduced, so that the blowing capacity can be improved and the noise can be reduced.

As described above, according to the present invention, it is possible to reduce the siren noise while improving the blowing performance of the centrifugal multi-blade fan. In addition, the code | symbol in the parenthesis of each said means shows the correspondence with the concrete means of embodiment mentioned later.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a schematic diagram in which a centrifugal blower (hereinafter, abbreviated as a blower) using a centrifugal multi-blade fan according to the present embodiment is applied to a vehicle air conditioner 1 of a vehicle equipped with a water-cooled engine. It is.

At the air upstream side of the air conditioning casing 2,
An inside air inlet 3 for sucking vehicle interior air and an outside air inlet 4 for sucking outside air are formed, and an inlet switching door 5 for selectively opening and closing these inlets 3, 4 is provided. Have been. The inlet switching door 5 is opened and closed by driving means such as a servomotor or by manual operation.

At the downstream side of the inlet switching door 5,
A blower 7 according to the present embodiment is provided, and the air sucked from both suction ports 3 and 4 by this blower 7 is blown toward respective outlets 14, 15 and 17 described below. An evaporator 9 serving as an air cooling means is provided downstream of the blower 7 in the air, and all the air blown by the blower 7 passes through the evaporator 9. A heater core 10 serving as air heating means is provided downstream of the evaporator 9 in the air. The heater core 10 heats the air using the cooling water of the engine 11 as a heat source.

A bypass passage 12 for bypassing the heater core 10 is formed in the air-conditioning casing 2, and an air flow ratio between an air flow passing through the heater core 10 and an air flow passing through the bypass passage 12 is adjusted upstream of the heater core 10. An air mix door 13 is provided. The adjustment of the air volume ratio is adjusted by adjusting the opening of the air mix door 13.

At the most downstream side of the air-conditioning casing 2, there are provided a face outlet 14 for blowing air-conditioned air to the upper body of the passenger in the passenger compartment, and a foot outlet 15 for discharging air to the feet of the passenger in the passenger compartment. Defroster outlet 1 for blowing air toward the inner surface of windshield 16
7 are formed. Each of the outlets 14, 1
Blow-out mode switching doors (blow-out adjusting means) 18, 19, and 20 are provided at the air upstream side of the air blowers 5 and 17, respectively. In addition, these blowing mode switching doors 18, 19,
20 is opened and closed by driving means such as a servomotor or by manual operation.

Next, the blower 7 will be described in detail. As described above, this blower 7 is a blower having a centrifugal multi-blade fan (hereinafter abbreviated as a fan) 72 that blows out the air sucked in from the direction of the rotating shaft 73a outwardly (see FIG. 2).
reference). As shown in FIG. 3, the fan 72 includes a plurality of first blades (first blades) 71a circumferentially disposed around the rotation shaft 73a and a first blade 71a disposed between the first blades 71a. A two-blade (second wing) 71b, and a flange portion 71c holding the two blades 71a and 71b and having a concave outer surface with a circumferential outer diameter edge (see FIG. 2).
It is composed of

Incidentally, the fan 72 is rotationally driven by driving means (hereinafter, referred to as a motor) 73 such as a motor via a flange portion (boss portion) 71c, and the amount of air blown is controlled by the rotation of the motor 73. This is done by controlling the number. The blades 71a, 71b and the flange 71c are integrally formed of resin. By the way, as shown in FIGS. 3 and 4, both the blades 71a and 71b have the first inner radius R1 _IN of the first inner edge S1 _IN of the first blade 71a and the second inner edge S2 _IN of the second blade 71b. It becomes smaller than the second inner radius R2 _IN (R1
_IN <R2 _IN ), and the fan outlet angles βa, βb of the blades 71a, 71b are set to be 70 ° to 120 ° (about 90 ° in the present embodiment) (see FIG. 6).

Here, the fan exit angle βa is, as shown in FIG. 4, an intersection angle between the first blade 71a and the first outer diameter edge S1 _OUT by the first blade 71a, and is a rotational direction of the fan 72. This is the angle measured from the forward side. Similarly, the fan outlet angle βb is defined by the second blade 71b and the second blade 71b.
This is the angle of intersection of the blade 71b with the second outer diameter edge S2 _OUT, and is the angle measured from the forward side in the rotation direction of the fan 72. In the present embodiment, two outer diameter edges S1
_OUT and S2 _OUT coincide with each other (overlap).

The outer diameter edge S of the second blade 71b is
The difference between the second outer radius R2 _OUT and the second within a radius R2 _IN of 2 _OUT (hereinafter, referred to as the difference between the blade length L _S of the second blade 71b.) Is outside of the first blade 71a diameter edge S1 the difference between the first outer radius R1 _OUT and the first inside radius R1 _iN the _OUT (hereinafter,
This difference is referred to as the blade length L of the first blade 71a. 3)
0% to 70% (in this embodiment, approximately ○%) (see FIG. 8), and the blade length L of the first blade 71a is determined by the outer diameter edge S1 of the first blade 71a. _OUT
10% to 30% of the diameter D (in this embodiment, approximately OO
%) (See FIG. 9).

The number of the blades 71a and 71b is 20% to 40% of the diameter D in millimeters.
(See FIG. 8). Incidentally, in the present embodiment, the first blade 71a has ○ sheets, the second blade 71b has ○ sheets, and the diameter D is ○ mm. By the way, in FIG.
2 and a casing made of a resin such as polypropylene spirally formed around a rotation shaft 73a of the fan 72 and constituting an air flow path 74a through which air blown from the fan 72 flows. An air outlet 75 communicating with the air conditioning casing 2 is formed downstream of the end portion 74b in the air (see FIG. 3).

A suction port 76 for introducing air into the casing 74 is opened on the opposite side of the motor 73 in the direction of the rotation shaft 73 a of the casing 74. A bell mouth 77 is formed in a casing 74 at the outer edge of the suction port 76.
The intake air is smoothly guided from the intake port 76 toward the wing 71.

An annular shroud on the suction port 76 side of the fan 72 reduces the cross-sectional area of the air flowing between the blades 71 toward the motor 73 toward the outer diameter side of the fan 72. 78 are formed. On the other hand, in a portion of the casing 74 facing the shroud 78, the shroud 7 is separated from the shroud 78 by a predetermined gap δ.
An opposing wall 79 is formed in an annular shape so as to extend from the bell mouth 77 along the line 8.

On the suction port 76 side of the casing 74, an inclined wall 80 having an inclined surface 80a inclined with respect to the direction of the rotation shaft 73a is formed so as to extend from the opposite wall 79 to the outside of the fan 72. The inclined surface 80 a of the inclined wall 80 is smoothly continuous over the entire winding angle θ of the casing 74. Next, features of the present embodiment will be described.

According to the present embodiment, each blade 71a,
Since the fan outlet angles βa and βb of the fan 71b are set to 70 ° to 120 °, a part of the centrifugal force applied to the air is converted into static pressure by the blades 71a and 71b (see FIG. 5). Therefore, the static pressure of the air blown out from the fan 72 increases, so that the fan 72 alone can improve the blowing capacity.

By the way, not only the fan 72 according to the present embodiment but also a normal centrifugal fan gives a centrifugal force to the air existing between the blades by rotating the blades, so that the air existing between the blades is removed by the centrifugal fan. As shown in FIG. 6, since the air blows out radially outward, the maximum wind speed is substantially at the center of the adjacent blade 71, and the blade surface (surface in contact with air) 71d of the blade 71 It is distributed so that the wind speed becomes minimum in the vicinity. For this reason, the wind speed distribution curve around the entire circumference of the centrifugal fan has a shape like a gear.

For this reason, the air having the maximum wind speed blown out from the approximate center of the adjacent blade 71 (the portion corresponding to the tooth tip of the gear-shaped wind speed distribution curve) flows into the nose portion 74c of the casing 74 (see FIG. 3). , A noise proportional to the number of rotations of the centrifugal fan and the number of blades 71 (the number between the blades 71) (hereinafter, this noise is referred to as a siren sound) is generated.

Therefore, in order to reduce the siren sound,
As is clear from the cause of the siren sound mentioned above,
What is necessary is just to make the wind speed distribution uniform, that is, to make the gear-shaped wind speed distribution curve a smooth circumference. Specifically, as in the case of increasing the number of teeth to reduce the noise generated when the gears mesh with each other, the number of blades 71 is increased, and the dimension between the blades 71 on the outer diameter side of the centrifugal fan is reduced. I just need.

However, when the size between the blades 71 is reduced by increasing the number of the blades 71, the suction resistance when air is sucked between the blades 71 and the air flowing between the blades 71 on the inner diameter side of the centrifugal fan. The friction loss of air increases. Further, when the centrifugal fan is formed of resin, if the dimension between the blades 71 is reduced, the workability (releasing property) of the die cutting operation is reduced, so that the yield of the centrifugal fan is reduced, and This leads to an increase in manufacturing costs.

On the other hand, the fan 7 according to the present embodiment
2, since the first inner radius R1 _IN is smaller than the second inner radius R2 _IN, when viewed from the inner diameter side of the fan 72 to the outer diameter side along the air flow, the inner diameter of the centrifugal multi-blade fan On the outer side, the number of blades decreases, while on the outer diameter side, the number of blades increases (see FIG. 4). Thus, the blade adjacent the first inner diameter edge S1 _IN side (first blade 7
1a), the dimension between adjacent blades (first and second blades 71a, 71b) on the first outer diameter edge S1 _OUT (second outer diameter edge S2 _OUT ) side is reduced while preventing the size between the first and second blades from decreasing. can do.

Therefore, the wind speed distribution curve is made smooth while reducing the suction resistance on the first inner edge S1 _IN side and the friction loss of the air flowing between the first and second blades 71a, 71b (see FIG. 7). ) Siren sound can be reduced. Also, since the size between the first and second blades 71a and 71b can be prevented from being reduced, the fan 72
Can be improved in releasability.

Incidentally, the dimension between the blades 71 of a normal centrifugal fan (radial fan) is as shown in FIG.
Since the air expands from the inner diameter side to the outer diameter side of the centrifugal fan, the air flow becomes more unstable as the air moves from the inner diameter side to the outer diameter side of the centrifugal fan. For this reason, in the centrifugal fan as shown in FIG. 6, problems such as a decrease in blowing capacity and an increase in noise occur.

However, in the present embodiment, since the second blade 71b is provided on the outer diameter side of the fan 72, each of the blades 71a, 71a is compared with a centrifugal fan as shown in FIG.
The dimension between 1b does not increase from the inner diameter side to the outer diameter side. Therefore, it is possible to improve the blowing capacity and reduce the noise. As described above, according to the present embodiment, it is possible to reduce the manufacturing cost of the fan 72 while improving the blowing ability of the fan 72 and reducing noise (siren sound).

The first inner radius R1 _IN is equal to the second inner radius R2.
Since it is smaller than _IN , the air intake area is substantially larger than that of a centrifugal fan having the same blade length as shown in FIG. Therefore, even if the height dimension H (see FIG. 2) of the flange portion (boss portion) 71c is increased, a suction area equal to or larger than a predetermined value can be secured. (See FIG. 10).

As shown in FIG. 2, the height H is the distance from the end of the flange (boss) 71c on the side of the suction port 76 to the end of the motor 73 on the side of the motor 73. FIG.
0, the solid line is the fan 72 according to the present embodiment, and the broken line is a centrifugal fan having the same blade length as shown in FIG. By the way, the shapes and arrangement relations of the first and second blades 71a and 71b are not limited to those shown in FIGS. 4 and 7, and the shapes and arrangement relations as shown in FIGS. It may be.

FIG. 11C shows the first blade 71.
a and the shape of the second blade 71b are different,
(B) shows the first blade 7 adjacent to the second blade 71b.
1a is an example of being located at a position shifted from the approximate center of 1a,
(G) is an example in which (a) to (f) are combined. Incidentally, as is clear from FIG. 11B, the arrangement position of the second blade 71b is not limited to substantially the center of the first blade 71a.

Incidentally, the definitions of the terms of the air volume Va and the specific noise Ks are based on JIS B 0132, and the test method is based on JIS B 8340.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram when a centrifugal blower according to the present invention is applied to an air conditioner for a vehicle.

FIG. 2 is a sectional view of the centrifugal blower according to the embodiment of the present invention.

FIG. 3 is a view taken in the direction of arrow A in FIG. 2;

FIG. 4 is an enlarged view of a fan according to the present invention.

FIG. 5 is a graph showing a relationship between a fan outlet angle and a static pressure.

FIG. 6 is an enlarged view of a fan having the same blade length.

FIG. 7 is an enlarged view of a fan according to the present invention.

FIG. 8 is a graph showing test results of the relationship between specific noise and air flow, blade length, and number of blades.

FIG. 9 is a graph showing test results of a relationship between specific noise and air flow and fan diameter D of blade length.

FIG. 10 is a graph showing a test result of a relationship between a height dimension of a flange portion (boss portion) and an air volume.

FIG. 11 is a schematic diagram showing a modification of the shape and arrangement of the first and second blades.

FIG. 12 is an enlarged view of a sirocco fan.

[Explanation of symbols]

71a: first blade (first wing), 71b: second blade (second wing).

Continued on the front page (72) Inventor Toru Tanaka 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Denso Co., Ltd. (72) Inventor Koji Ito 1-1-1, Showa-cho, Kariya-shi, Aichi pref. ) Inventor Sugi Hikari 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Inside DENSO Corporation

Claims (4)

[Claims] 1. A centrifugal multi-blade fan that sucks air from a rotation axis direction and blows air outwardly, comprising a plurality of first blades circumferentially disposed around the rotation axis. (71a), and a second wing (71b) disposed between the first wings (), and a first inner radius (S1 _IN ) of a first inner diameter edge (S1 _IN ) of the first wing (71a). R1 _IN ) is smaller than the second inner radius (R2 _IN ) of the second inner diameter edge (S2 _IN ) of the second blade (71b), and further, the fan exit angle (β) of each blade (71a, 71b).
a, βb) is 70 ° to 120 °, a centrifugal multi-blade fan. 2. A difference (L _S ) between a second outer radius (R2 _OUT ) of a second outer diameter edge (S2 _OUT ) by the second wing (71b) and the second inner radius (R2 _IN ) is: The first wing (71a)
The first outer radius (R1) of the first outer diameter edge (S1 _OUT )
1 _OUT ) and the difference (L) between the first inner radius (R1 _IN ) and 3
The centrifugal multi-blade fan according to claim 1, wherein the ratio is 0% to 70%. 3. The number of the two wings (71a, 71b) is
The first outer diameter edge whose unit is millimeter (S1 _OUT )
The centrifugal multi-blade fan according to claim 1 or 2, wherein the integral value is an integer value included in 20% to 40% of the diameter (D) of the fan. 4. The first outer radius (R1 _OUT ) and the first outer radius (R1 _OUT ).
The difference (L) from the inner radius (R1 _IN ) is equal to the first outer diameter edge (S
The centrifugal multi-blade fan according to any one of claims 1 to 3, wherein the diameter is 10% to 30% of the diameter (D) of 1 _OUT ).