JPH1162895A - Centrifugal blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noise of the whole blower while restraining the separating phenomenon of vanes and air to be allowed to flow between the vanes by providing a shroud. SOLUTION: The inclined surface 80a inclined toward a motor side is formed in the range from the tongue of a casing 14 to the volute angle of 90 deg. on the inclined wall 80, the inclined surface 80a inclined toward a suction port 76 side is formed in the range of 90 deg. to 180 deg. of the volute angle, and the inclined surface 80a is made to be parallel to a rotary shaft after the volute angle of 180 deg.. Therefore, air blown off from a fan can be prevented from being allowed to flow back from a clearance to the suction port 76 side, and reduction of noise can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal blower, and is suitable for use in a vehicle air conditioner.

[0002]

2. Description of the Related Art Centrifugal blowers (hereinafter abbreviated as blowers).
As is well known, a centrifugal multi-blade fan (hereinafter abbreviated as a fan) in which a number of blades (blades) are arranged around a rotation axis, and a spiral shape having an air inlet and an air outlet. And a drive unit such as a motor for rotating the fan. The performance of the blower, such as the blowing capacity and noise, greatly depends on the shape of the fan blades, the shape of the casing, and the like, and these must be sufficiently considered when designing the blower.

[0003]

SUMMARY OF THE INVENTION Incidentally, the present inventors have proposed, for example, Japanese Patent Laid-Open No. 5-296 in order to reduce the noise of a blower.
As described in Japanese Patent Publication No. 194, various types of fans having a shroud for reducing the cross-sectional area of the air flowing between the blades toward the motor side toward the outer diameter side of the fan have been trial manufactured and examined. Could not get. Therefore, the inventors continued examination and examination,
The following points became clear.

That is, as a cause of noise generation, there is a turbulence of an air flow generated by a separation phenomenon between blades and air flowing between the blades. With respect to this cause, by providing the shroud, the air flow between the blades can be made substantially uniform, and the phenomenon of separation between the blades and the air flowing between the blades can be suppressed. In addition, the larger the shroud portion occupying the blade, the smaller the ratio (h ₂ / h ₁ ) of the outer diameter side height h ₂ of the blade 71 to the inner diameter side height h ₁ of the blade 71, the more the separation phenomenon can be suppressed. Have been confirmed by further examinations by the inventors.

However, as the shroud 77 portion occupying the wing becomes larger, the air blown out from the fan 72 becomes larger as shown in FIG.
As shown in FIG.
It will blow out toward. Therefore, the fan 72
A part of the air blown out from the casing flows along the inner wall surface 74d on the radial side casing and the inner wall surface 74b on the casing on the suction port side. Therefore, the air flowing along the casing inner wall surface 74b on the suction port 75 side is
Backflow from the gap 77c between the casing 7 and the casing 74 to the suction port 75 side, the interference between the air sucked from the suction port 75 and the backflowing air, and the shroud 77 and the casing 7
Noise is generated due to the turbulence of the flow generated when flowing backward through the gap 77c with the gap 4c.

In other words, by providing the shroud 77, noise caused by the separation phenomenon between the blade 71 and the air flowing between the blades can be reduced. Gap 7
The airflow flowing backward through 7c becomes remarkable, and on the contrary, the noise of the entire blower increases. As described above, the present invention has been made based on various tests and examinations of the inventors and the like, and by providing a shroud, the separation phenomenon of air flowing between the blades and the blades is suppressed, and the entire blower is The aim is to reduce the noise as a result.

[0007]

The present invention uses the following technical means to achieve the above object. Claim 1
In the invention described in Item 3, the surface (80a) inclined toward the other end in the axial direction from the start of winding of the casing (74) to the predetermined winding angle (θ ₂ ) of the inclined wall (80). On the other hand, between the predetermined winding angle (θ ₂ ) and the end of the winding of the inclined wall (80), a surface (80a) inclined toward one end in the axial direction is formed. Features.

Thus, in the region where the winding angle (θ) is smaller than the predetermined winding angle (θ ₂ ), the surface (8) inclined toward the other axial end is provided.
0a) is formed smoothly and continuously, and among the air blown out of the centrifugal multi-blade fan (72), the air blown out from a region before a predetermined winding angle (θ ₂ ) is equal to the inclined wall (80). ), It is turned toward the other end in the axial direction while being gathered toward the winding end side.

Therefore, the air blown out from the area before the predetermined winding angle (θ ₂ ) is supplied from the gap (78a) between the shroud (78) and the casing (74) to the suction port (76).
Since it can be prevented from flowing back to the side, interference with air blown from the centrifugal multi-blade fan (72) sucked through the suction port (76) (hereinafter, this air is referred to as blown air) is prevented. Can be.

In the region where the winding angle (θ) is equal to or larger than the predetermined winding angle (θ ₂ ), one end in the axial direction (the suction port (7
6) side is smoothly and continuously formed, so that the rotation axis of the rotating air from the outside of the blown air extends along the inner wall of the casing (74) on the suction port (76) side. Is diverted toward the other end in the axial direction, so that backflow of air from the gap (78c) to the suction port (76) is suppressed, and the air flow path (74)
With the expansion of a), the blown air is smoothly gathered toward the winding end side.

Therefore, it is possible to prevent the air blown out from the area after the predetermined winding angle (θ ₂ ) from flowing backward from the gap (78a) to the suction port (76) side, and thus to be sucked from the suction port (76). It is possible to prevent interference between the blown air and the blown air. As described above, according to the present invention, by providing the shroud (78), the wing (71) is provided.
The noise of the centrifugal blower as a whole can be reduced while suppressing the separation phenomenon between the air and the air flowing between the blades (71).

The reference numerals in parentheses of the above means indicate the correspondence with specific means described in the embodiments described later.

[0013]

FIG. 1 is a schematic diagram showing a case where a centrifugal blower (hereinafter abbreviated as a blower) according to the present embodiment is applied to an air conditioner 1 for a vehicle equipped with a water-cooled engine. At the air upstream side of the air-conditioning casing 2, there are formed an inside air inlet 3 for sucking the air inside the vehicle and an outside air inlet 4 for sucking the outside air.
Is provided with an inlet switching door 5 for selectively opening and closing the suction port. 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.

The air conditioning casing 2 is provided with a bypass passage 12 for bypassing the heater core 10, and on the upstream side of the heater core 10, the ratio of the amount of air flowing through the heater core 10 to the amount of air flowing through the bypass passage 12 is adjusted. 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.

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 blowing air to the feet of the passenger in the passenger compartment are provided at the most downstream side of the air-conditioning casing 2. 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 will be described in detail with reference to FIG. The blower 7 is a centrifugal blower that blows air sucked in from the direction of the rotating shaft 73a toward the outside in a radial direction.
Is a well-known centrifugal multi-blade fan having a number of blades (blades) 71 around a rotation axis 73a (hereinafter, abbreviated as a fan).
It is. The fan 72 is driven to rotate by driving means (hereinafter, referred to as a motor) 73 such as a motor, and the amount of air blown is controlled by controlling the number of rotations of the motor 73.

Reference numeral 74 denotes a resin casing made of polypropylene or the like, which houses the fan 72 and forms an air flow path 74a through which air blown from the fan 72 flows, and which is spirally formed around a rotation shaft 73a of the fan 72. ,
An air outlet 75 communicating with the air conditioning casing 2 is formed downstream of the winding end portion 74d of the casing 74 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 73a 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 passage 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 toward 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. Specifically, as shown in FIG. 4, the inclined surface 80 a is provided until the winding angle θ is 0 ° to 30 ° (hereinafter, this winding angle θ is referred to as a first predetermined winding angle θ ₁ ).
Is inclined at 60 ° to 30 ° so that
Until the winding angle θ becomes the first predetermined winding angle θ ₁ (= 30 °) to 90 ° (hereinafter, this winding angle θ is changed to the second winding angle θ).
It referred to as a predetermined wrap angle θ _2. ), The inclination angle Θ is gradually increased until the inclined surface 80a is orthogonal to the rotation axis 73a (the inclination angle 傾斜 = 90 °).

Incidentally, as shown in FIG. 2, the inclination angle Θ is an intersection angle between the inclined surface 80a and the rotating shaft 73a, and the direction from the motor 73 side to the suction port 76 side is measured as positive. Angle. Further, when the winding angle θ is from the second predetermined winding angle θ ₂ (= 90 °) to 180 ° (hereinafter, this winding angle θ is referred to as a third predetermined winding angle θ ₃ ),
The inclination angle Θ is increased (Θ> 90 °) so that the inclined surface 80a is inclined to the suction port 76 side, and the winding angle θ becomes the third predetermined winding angle θ ₃ (= 180 °) to 345 ° (hereinafter, this is referred to as “ Winding angle θ
Is referred to as a fourth predetermined winding angle θ ₄ . ) Until the slope 8
0a is substantially parallel to the rotation shaft 73a (tilt angle Θ ≒ 180
°).

Incidentally, the winding angle θ is equal to the fourth predetermined winding angle θ.
₄ (= 345 °) to 360 °, the inclination angle Θ is 1
The inclined surface 80 changes smoothly from 80 ° to 60 °.
a is formed. The first to fourth predetermined angles θ _{1 to} θ
₄ and the inclination angle Θ are not limited to the above-mentioned angles, but are appropriately selected based on the specifications of the blower 7 such as a required air volume required for the blower 7.

Incidentally, according to tests and studies by the inventors, as shown in FIGS. 2 and 4, in the casing 74 of the type in which the cross-sectional area of the air flow path 74a does not expand toward the motor 73, the third predetermined winding angle It is desirable that θ ₃ be about 75 ° to 105 °, and as shown in FIG. 5, a type in which the cross-sectional area of the air flow path 74a increases toward the motor 73 as the winding angle θ increases (hereinafter referred to as “motor 73”). in the casing 74 of the type referred to as a lower spreading type.), to obtain a conclusion that it is desirable to a third predetermined winding angle theta ₃ and 0.99 ° to 210 ° about.

Further, a casing 74 of a downwardly expanding type is provided.
In is concluded with it is desirable to a second predetermined winding angle theta ₂ to about 120 ° to 150 DEG. Next, features of the present embodiment will be described. The winding angle θ is the second predetermined winding angle θ
Before the area ₂ , the inclined surface 80 a inclined toward the motor 73 is provided.
Are formed smoothly and continuously, so that among the air blown out from the fan 72, the winding angle θ is the second predetermined winding angle θ
_The air blown out from the previous area is collected by the inclined wall 80 toward the winding end side while the motor 7
It is turned to the 3rd side.

Therefore, it is possible to prevent the air blown out from the area before the second predetermined winding angle θ ₂ from flowing back from the gap 78 a (see FIG. 2) between the shroud 78 and the casing 74 to the suction port 76 side. It is possible to prevent interference between the air sucked from the port 76 and the air blown out from the fan 72. Further, in the area after the second predetermined winding angle θ ₂ , the inclined surface 80 a inclined toward the suction port 76 is formed smoothly and continuously, so that the inner wall of the casing 74 of the blowing air near the suction port 76 is formed. 74b (see FIG. 2)
The reverse air flowing from the outside to the rotating shaft 73a is turned toward the motor 73 so as to follow
The backflow of air from 8c to the inlet 76 is suppressed, and the blown air is smoothly gathered toward the winding end side with the expansion of the air flow path 74a.

Therefore, it is possible to prevent the air blown out from the area after the second predetermined winding angle θ ₂ from flowing back from the gap 78 a to the suction port 76 side, and thus the air sucked from the suction port 76 and the blown air can be prevented from flowing. Interference can be prevented. As described above, according to the present embodiment, by providing the shroud 78, it is possible to suppress the separation phenomenon of the air flowing between the blades 71 and the blades 71 and to reduce the noise of the blower 7 as a whole. .

Incidentally, according to further examinations by the inventors, in particular, a fan having an outlet angle α of the blade 71 of 90 ° ± 20 ° (hereinafter, such a fan is referred to as a radial fan).
72, it has been confirmed that the noise caused by what was described in the section of “Problems to be Solved by the Invention” becomes remarkable. Therefore, it is particularly effective to apply the present invention to the blower 7 having the fan 72 whose outlet angle α is 90 ° ± 20 °.

Here, the exit angle α is, as shown in FIG. 6, the angle between the outer diameter edge of the fan 72 and the blade surface 71a of the blade 71, from the forward side to the backward side in the rotational direction of the fan 72. The angle toward. FIG. 7 shows the results of tests on the air volume Va, the total pressure DPt, and the specific noise Ks of the blower 7 having the radial fan 72. As is clear from the graph shown in FIG. 7, it can be seen that the specific noise Ks and the total pressure DPt are improved irrespective of the presence or absence of the downward expansion (the expansion of the air flow path 74a to the motor 73 side).

Incidentally, the terms of the air volume Va, the total pressure DPt and the specific noise Ks are defined according to JIS B0132, and the test method is based on JIS B8340.

[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 a schematic diagram showing a change in an inclination angle Θ.

FIG. 5 is a sectional view of a centrifugal blower according to a modification of the present invention.

FIG. 6 is an explanatory diagram of an exit angle α.

FIG. 7 is a graph showing test results for air volume Va, total pressure DPt, and specific noise Ks of blower 7;

[Explanation of symbols]

7 ... centrifugal blower, 71 ... blade, 72 ... centrifugal multi-blade fan,
73 ... motor (drive means), 74 ... casing, 76 ...
Inlet, 77 ... Bellmouth, 78 ... Shroud, 79 ...
Opposing wall, 80 ... inclined wall.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toru Tanaka 1-1-1 Showa-cho, Kariya-shi, Aichi Prefecture Inside DENSO Corporation

Claims (4)

[Claims] 1. A centrifugal multi-blade fan (72) having a number of blades (71) around a rotation axis, and blowing out air taken in from the axial direction of the rotation shaft (73a) outward. The centrifugal multi-blade fan (72) is housed therein and constitutes an air flow path (74a) through which air blown from the centrifugal multi-blade fan (72) flows. A casing (74) spirally formed around the rotation axis of the centrifugal multi-blade fan (72)
And a driving means (73) for rotationally driving the centrifugal multi-blade fan (72), wherein the suction port (7) of the centrifugal multi-blade fan (72) is provided.
6) On the shroud, the cross-sectional area of the air flowing between the blades (71) decreases toward the other end in the axial direction toward the outer diameter side of the centrifugal multi-blade fan (72). (78) is formed, the casing (74) is provided with an opposing wall (79) formed along the shroud (78) with a predetermined gap (78a) from the shroud (78); (79) The centrifugal multi-blade fan (72)
The inclined wall is formed continuously to the outside of the diameter of the casing, has a surface (80a) inclined with respect to the axial direction, and smoothly continues over the entire circumference of the winding angle (θ) of the casing (74). (80), and the casing (7) of the inclined wall (80).
A surface (80a) inclined toward the other end in the axial direction is formed between the start of winding of 4) and a predetermined winding angle (θ ₂ ). The predetermined winding angle (θ
A centrifugal blower characterized in that a surface (80a) inclined toward one end in the axial direction is formed between ₂ ) and the end of winding of the casing (74). 2. A plane (80a) substantially parallel to the axial direction is formed in the inclined wall (80) in a range where the winding angle (θ) is 75 ° to 105 ° or more. The centrifugal blower according to claim 1, wherein: 3. The casing (74) is configured such that a cross-sectional area of the air flow path (74a) increases toward the other end in the axial direction as the winding angle (θ) increases. And the winding angle of the inclined wall (80) is 15
The centrifugal blower according to claim 1, wherein a plane (80a) substantially parallel to the axial direction is formed in a range from 0 ° to 210 ° or later. 4. The centrifugal blower according to claim 1, wherein an outlet angle (α) of the centrifugal multi-blade fan (72) is 90 ° ± 25 °.