JP3876830B2 - Centrifugal blower and blower for air conditioner - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a centrifugal blower and is effective when applied to a vehicle blower of a vehicle air conditioner.
[0002]
[Prior art]
As shown in FIG. 9, the conventional centrifugal blower has an annular projecting wall 77b projecting from the end of the blade 72 to the suction port 75 side at the end of the centrifugal multiblade fan 71 on the suction port 75 side. By providing a bell mouth portion 76 that surrounds the protruding wall 77b with a predetermined clearance from the protruding wall 77b at the outer edge portion of the suction port 75 to form a labyrinth structure, it is blown out from the centrifugal multiblade fan 71. The air is prevented from flowing backward from the gap between the scroll casing 74 and the centrifugal multiblade fan 71 toward the suction port 75 (see, for example, Patent Document 1).
[0003]
Incidentally, when the air blown out from the centrifugal multiblade fan 71 flows backward to the suction port 75 side, the backward flow air and the intake air interfere with each other, and vortex loss and noise are generated.
[0004]
[Patent Document 1]
JP-A-5-296194 [0005]
[Problems to be solved by the invention]
By the way, in the invention described in Patent Document 1, the suction side outer wall surface 74c connected to the bell mouth portion 76 of the outer wall surface of the scroll casing 74 is formed with a step that is greatly raised at the bell mouth portion 76. As shown in FIG. 10, of the intake air flowing toward the suction port 75, the air flowing in the vicinity of the suction side outer wall surface 74 c collides at the step of the bell mouth portion 76.
[0006]
And the air flow which collided by the level | step difference of the bellmouth part 76 and became turbulent flow induces a new vortex loss and noise.
[0007]
In view of the above points, the present invention firstly provides a novel centrifugal blower different from the conventional one, and secondly, it is intended to suppress the disturbance of the air flow in the bell mouth portion.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has a plurality of blades (72) arranged around the rotating shaft (7a) and sucks air from the axial direction side. The centrifugal multiblade fan (71) for blowing air in the radial direction and the centrifugal multiblade fan (71) are housed, and an air inlet (75) is formed on the end side of the rotating shaft (7a). A spiral scroll casing (74),
An annular projecting wall (77b) projecting from the end of the blade (72) toward the suction port (75) is provided at the end of the centrifugal multiblade fan (71) on the suction port (75) side,
The outer peripheral portion of the suction port (75) of the scroll casing (74) surrounds the protruding wall (77b) with a predetermined gap from the protruding wall (77b), and air is supplied to the centrifugal multiblade fan (71). The bell mouth part (76) leading to is provided,
Further, the scroll casing (74) is connected to the bell mouth portion (76) in a flat shape without a step, and is connected to the suction side outer wall surface (74c) extending radially outward and the bell mouth portion (76) and inhaled. An inner wall (74b) positioned on the inner side in the axial direction by a predetermined distance from the side outer wall surface (74c),
The inner wall (74b) is characterized by extending in a flat shape radially outward along the suction side outer wall surface (74c) .
[0009]
As a result, it is possible to suppress the turbulence and the like from being generated in the intake air flowing toward the suction port (75). Therefore, it is possible to suppress the air flow from being disturbed in the bell mouth portion (76), and a new vortex loss or noise Etc. can be prevented from being induced.
[0010]
According to a second aspect of the present invention, in the centrifugal blower according to the first aspect, the inner wall (74b) is integrally formed with the scroll casing (74), and
A separate plate (74d) is attached to the scroll casing (74), and the separate plate (74d) constitutes the suction side outer wall surface (74c) .
[0011]
According to a third aspect of the present invention, in the centrifugal blower according to the first aspect, the inner wall (74b) and the suction side outer wall surface (74c) are integrally formed in the scroll casing (74), and the scroll casing (74) The molded portion of the suction side outer wall surface (74c) and the inner wall (74b) is thicker than other portions .
In the invention according to claim 4, in the centrifugal blower according to claim 1, the inner wall (74b) and the suction side outer wall surface (74c) are integrally formed in the scroll casing (74),
A hollow portion is formed between the suction side outer wall surface (74c) and the inner wall (74b).
[0013]
Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
In this embodiment, a centrifugal blower (hereinafter abbreviated as “blower”) according to the present invention is applied to a vehicle air conditioner for a vehicle equipped with a water-cooled engine, and FIG. 1 is a schematic diagram of the air conditioner 1.
[0015]
In the air upstream side portion of the air conditioning casing 2 forming the air flow path, the opening ratio of the inside air introduction port 3 for introducing the vehicle interior air, the outside air introduction port 4 for sucking outside air, and the both introduction ports 3 and 4 That is, an inside air / outside air switching unit 6 including an inlet switching door 5 and the like for adjusting the ratio of the inside air amount and the outside air amount to be introduced into the air conditioning casing 2 is provided, and this inside air / outside air switching unit 6 supplies air to the blower 7. The guiding duct part is configured.
[0016]
A blower 7 is disposed on the downstream side of the air flow of the inside / outside air switching unit 6, and air sucked from both the inlets 3, 4 by the blower 7 is supplied to the respective outlets 14, 15, which will be described later. The air is blown toward 17. In addition, the air blower 7 shown by FIG. 1 is typical, and it mentions later for details.
[0017]
Further, an evaporator 9 serving as an air cooling means is disposed on the air downstream side of the blower 7, and all the air blown by the blower 7 passes through the evaporator 9. A heater core 10 serving as an air heating means is disposed on the air downstream side of the evaporator 9, and the heater core 10 heats air using the cooling water of the engine 11 as a heat source.
[0018]
The air conditioning casing 2 is provided with a bypass passage 12 that bypasses the heater core 10, and the air volume ratio between the air volume passing through the heater core 10 and the air volume passing through the bypass passage 12 is adjusted on the air upstream side of the heater core 10. An air mix door 13 is provided.
[0019]
Further, at the most downstream part of the air conditioning casing 2, a face outlet 14 for blowing conditioned air to the upper body of the passenger in the passenger compartment, a foot outlet 15 for blowing air to the feet of the passenger in the passenger compartment, and the windshield A defroster outlet 17 for blowing air toward the inner surface of 16 is formed.
[0020]
And the blowing mode switching doors 18, 19, and 20 are disposed at the air upstream side portions of the respective outlets 14, 15, and 17, respectively. Note that these blow mode switching doors 18, 19, and 20 are opened and closed by a driving means such as a servo motor or by manual operation.
[0021]
Incidentally, in the actual vehicle air conditioner, since the foot outlet 15 and the defroster outlet 17 are smaller than the face outlet 14, the foot mode and the differential mode have an air flow resistance (pressure loss) compared to the face mode. It is getting bigger.
[0022]
Next, the blower 7 will be described.
[0023]
2 is a half sectional view of the blower 7, FIG. 3 is an explanatory view showing the air flow in the blower 7, and FIG. 4 is an enlarged view of FIG.
[0024]
In FIG. 2, the fan 71 is a centrifugal multiblade fan having a large number of blades 72 around the rotating shaft 7a and blowing out air sucked from the other end side in the direction of the rotating shaft 7a toward the radially outer side. The motor 73 is an electric drive unit that rotationally drives the fan 71.
[0025]
The casing 74 is a resin scroll casing formed in a spiral shape that houses the fan 71 and forms a flow path 74 a of the air blown out from the fan 71 (see FIG. 3). An air inlet 75 is formed that opens toward one end in the direction 7a and whose opening diameter D is set larger than the minimum inner diameter dmin of the fan 72.
[0026]
Incidentally, on the suction port 75 side of the fan 71, as shown in FIG. 4, a shroud 77 formed with an opposing surface 77 a facing the inner wall 74 b of the casing 74 with a gap δ is formed on the resin together with the blade 72. Are integrally molded.
[0027]
Note that the cross-sectional shape of the shroud 77 is a streamline of mainstream air flowing through the blade 72 so that the cross-sectional area of the air flow path decreases (blade height decreases) from the fan inner diameter side toward the outer diameter side. Is formed in a shape (substantially arc shape).
[0028]
Further, the shroud 77 is formed with an annular projecting wall 77b projecting from the end portion on the suction port 75 side of the blade 72 toward one end in the direction of the rotation shaft 7a, that is, toward the suction port 75 side. A predetermined gap connected to the wall 77b from the gap δ is provided so as to surround and cover the protruding wall 77b, and extends from the outer edge portion of the suction port 75 toward the fan inner diameter side to smoothly air to the fan 71. Configured to lead to.
[0029]
Of the outer wall surfaces of the casing 74, the suction-side outer wall surface 74 c connected to the bell mouth portion 76 is configured to have a flat shape without a step by increasing the thickness of the casing 74.
[0030]
In the present embodiment, the suction-side outer wall surface 74c is a plane orthogonal to the axial direction of the fan 71. However, the present invention is not limited to this, and for example, the suction port 75 is located at the axial center. It may be a flat shape with no conical taper.
[0031]
Further, a predetermined inclination angle θ1 (50 ° in the present embodiment) with respect to the radial direction of the fan 72 is formed on the suction port 75 side of the blade 72 so that the fan inner diameter increases toward the suction port 75 side. And a linearly inclined inclined portion 72a is formed. A portion of the blade 72 connected to the inclined portion 72a is parallel to the rotating shaft 7a (see FIG. 2) so that the inner diameter of the fan is substantially constant. A part (constant part) 72b is formed.
[0032]
Next, features of the present embodiment will be described.
[0033]
In the present embodiment, the suction side outer wall surface 74c connected to the bell mouth portion 76 of the outer wall surface of the casing 74 is configured to have a flat shape without a step, and therefore, toward the suction port 75 as shown in FIG. It is possible to suppress the occurrence of turbulence and the like in the flowing intake air. Therefore, since it is possible to suppress the air flow from being disturbed by the bell mouth portion 76, it is possible to prevent new vortex loss and noise from being induced as is apparent from the test results shown in FIG.
[0034]
(Second Embodiment)
In the first embodiment, by increasing the thickness of the casing 74, the suction-side outer wall surface 74c has a flat shape with no steps. However, in the present embodiment, as shown in FIG. It is a thing.
[0035]
(Third embodiment)
In the first embodiment, the thickness of the casing 74 is increased to make the suction-side outer wall surface 74c flat without a step. However, in the present embodiment, a separate plate 74d is used as shown in FIG. The suction side outer wall surface 74c has a flat shape with no step.
[0036]
(Other embodiments)
In the above-described embodiment, the casing 74, that is, the blower 7 is improved so that the portion 74c connected to the bell mouth portion 76 from the inner wall of the inside / outside air switching unit 6 has a flat shape without a step, but the present invention is limited to this. However, for example, the inside / outside air switching unit 6 may be modified such that the portion 74c connected from the inner wall of the inside / outside air switching unit 6 to the bell mouth portion 76 has a flat shape without a step.
[0037]
Moreover, in the above-mentioned embodiment, although the air blower concerning this invention was applied to the vehicle air conditioner, application of this invention is not limited to this.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a vehicle air conditioner.
FIG. 2 is a cross-sectional view of the blower according to the first embodiment of the present invention.
FIG. 3 is a schematic view of the blower according to the first embodiment of the present invention as viewed from the inlet side.
4 is a partially enlarged view of FIG. 2;
FIG. 5 is an explanatory diagram showing an air flow in the blower according to the first embodiment of the present invention.
FIG. 6 is a graph showing the relationship between noise (SPL) and frequency.
FIG. 7 is a partially enlarged view of a blower according to a second embodiment of the present invention.
FIG. 8 is a partially enlarged view of a blower according to a third embodiment of the present invention.
FIG. 9 is a view of a blower according to a conventional technique.
FIG. 10 is an explanatory diagram showing an air flow in a blower according to a conventional technique.
[Explanation of symbols]
71 ... Blower, 72 ... Blade, 72a ... Inclined part, 72b ... Parallel part,
75 ... Inlet, 76 ... Bellmouth part.

Claims (4)

A centrifugal multiblade fan (71) having a plurality of blades (72) disposed around the rotating shaft (7a) , sucking air from the axial direction side and blowing air in a radial direction;
A spiral scroll casing (74) that houses the centrifugal multiblade fan (71) and has an air inlet (75) formed on the end side of the rotating shaft (7a) ;
An annular projecting wall (77b) projecting from the end of the blade (72) toward the suction port (75) side at the end of the centrifugal multiblade fan (71) on the suction port (75) side. Is provided,
An outer edge portion of the suction port (75) of the scroll casing (74) surrounds the protruding wall (77b) with a predetermined gap from the protruding wall (77b), and air is supplied to the centrifugal multi-portion. A bell mouth part (76) leading to the wing fan (71) is provided,
Further, the scroll casing (74) is connected to the bell mouth portion (76) in a flat shape without a step, and extends to the suction side outer wall surface (74c) extending radially outward and to the bell mouth portion (76). An inner wall (74b) that is connected to the suction-side outer wall surface (74c) and is located on the inner side in the axial direction by a predetermined distance;
The centrifugal blower characterized in that the inner wall (74b) extends in a flat shape radially outward along the suction side outer wall surface (74c) . While integrally molding the inner wall (74b) in the scroll casing (74),
The centrifugal plate according to claim 1 , wherein a separate plate (74d) is attached to the scroll casing (74), and the suction side outer wall surface (74c) is constituted by the separate plate (74d). Blower. The inner wall (74b) and the suction side outer wall surface (74c) are formed integrally with the scroll casing (74), and the suction side outer wall surface (74c) and the inner wall (74b) of the scroll casing (74) are integrally formed. The centrifugal blower according to claim 1, wherein the molding part is thicker than other parts. While integrally forming the inner wall (74b) and the suction side outer wall surface (74c) in the scroll casing (74),
The centrifugal blower according to claim 1, wherein a hollow portion is formed between the suction side outer wall surface (74c) and the inner wall (74b).

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