JP3351438B2 - Multi-wing 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 multi-blade blower, and more particularly, to a multi-blade blower suitable for use in an air conditioner mounted on a vehicle.

[0002]

2. Description of the Related Art Conventionally, a multi-blade fan used for an air conditioner or the like has a configuration in which a multi-blade fan having a large number of blades is housed in a case having a bell mouth.
The multi-blade fan has a structure in which a number of blades are arranged between a bottom plate and a retaining ring.

According to this type of conventional multi-blade blower shown in FIG. 7, when a multi-blade fan is driven by a motor, air flows in the directions of arrows 105 and 106 shown in FIG. The discharged air flows out of the scroll discharge port through the space between the main blades 25.

[0004]

However, in such a conventional multi-blade blower, according to an experimental study conducted by the present inventor, as shown in FIG. 7, for example, as shown in FIG. Backflow through the gap of 10
1, and it was found that a vortex indicated by an arrow 104 was generated on the radially outer portion of the holding ring 42. The generation region of the backflow 101 or the vortex 104 is generated regardless of the air volume of the blower, is an unstable region that wastes the work of the multi-blade fan, and has a large effect of disturbing the discharge flow and the suction flow. It is also a cause of increasing noise.

According to such a conventional blower,
As shown in FIG. 7, the wind speed distribution at the outlet of the main blade 25 is such that the wind speed increases below the main blade 25, and it is found that almost no air flows above the main blade 25. did. Furthermore, it has been found that if there is an extra space 38 inside the case above the main blade 25, a vortex or a backflow will occur in this space 38, and noise performance and fan efficiency will decrease.

The problem to be solved by the present invention is to prevent the backflow flowing through the gap between the top of the blade and the inner wall of the case and to prevent the vortex at the upper portion of the scroll, thereby improving the fan efficiency and reducing the noise. It is an object of the present invention to provide a multi-blade blower which can be measured.

[0007]

A multi-blade blower according to the present invention for solving the above-mentioned problems is provided with a case having a bell mouth forming an air intake, and housed in the case and arranged in a circumferential direction. Centrifugal multi-blade fan having a plurality of blades, an annular shroud formed at an air suction side end of the number of blades, and a bottom plate formed at an anti-air suction side end of the number of blades, The shroud has an annular protrusion and a top surface, and is formed into a substantially arc-shaped cross-sectional shape along the air flow that flows from the air intake port between the blades from a fan axial direction to a fan radial outside direction. is formed such that the inner wall sectional shape of the bell mouth vicinity of the case along the cross-sectional shape of the shroud through the small gap between the shroud, the fine
Small gaps are formed at substantially regular intervals,
Is formed from the outer peripheral wall of the raised up radially outward end of the top surface, said case of bell mouth is formed with an annular recess as viewed from the blade side, the recess of the annular in radially inward direction end of the shroud is said annular projection is formed extending within said annular projection of height H1, when the gap H2 of between the bell mouth and the upper end of the annular projection, 5 ≦ H1 ≦ 10 (mm ), 3 ≦ H2 ≦ 5 (mm ) And.

[0008]

According to the centrifugal multi-blade fan of the present invention, the shroud is formed in a substantially arc-shaped cross-sectional shape so as to change the direction of the air flow taken in from the air intake from the axial direction of the fan to the radially outward direction of the fan. Is formed so that the cross-sectional shape of the inner wall near the bell mouth follows the cross-sectional shape of the shroud with a small gap between the shroud and the case.
Formed between the inner wall near the bellmouth and the shroud
Small gaps are formed at almost regular intervals, with annular projections on the shroud.
Formed from the outer peripheral wall to the radially outer end of the top surface, the occurrence of backflow from the blade outlet to the inner diameter side passing through the minute gap is prevented, and noise performance and fan efficiency are improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment in which the present invention is applied to a blower that takes in air of a vehicle air conditioner. As shown in FIG. 2, the ventilation system supplies the air taken in from the outside air intake 2 for taking in the air outside the vehicle compartment or the inside air intake 3 for taking in the air inside the vehicle compartment from the air intake 36 of the blower 6 into the case 1. And guided to the evaporator 7 by the centrifugal multi-blade fan 20. The outside air inlet 2 and the inside air inlet 3 are opened and closed by a rotatable damper 5. An air mix damper 8 is provided on the outlet side of the evaporator 7, and a heater core 17 is attached to a second flow path 19 on one side of the first flow path 18 and the second flow path 19 partitioned by the air mix damper 8. ing. Air mix damper 8 and air mix chamber 9 formed on the outlet side of heater core 17
Communicates with the defroster outlet 13, the chest outlet 12, and the foot outlet 10. Each outlet 10, 12, 1
A damper 14 for adjusting the opening of the outlet,
15 and 16 are attached rotatably.

The specific structure of the blower 6 is shown in FIG.
Is shown in The blower 6 includes a fan driving motor 33, the case 22, and the centrifugal multi-blade fan 20. The shaft 50 of the fan drive motor 33 is supported and fixed to the motor case 38 and is connected to the boss 28 of the centrifugal multi-blade fan 20.
The case 22 is formed in a well-known scroll shape formed of resin, and has an air outlet portion 37 shown in FIG. 2 extending in a radially outward direction. The air outlet portion 37 is connected to the air inlet side of the evaporator 7. ing. As shown in FIG. 3, the bell mouth 31 forming the air intake is provided with an annular rising portion 6.
1, an arc portion 62 which is curved in a radially inward direction in a semi-arc shape from the tip of the rising portion 61, and an annular projecting portion 63 which hangs down from an inner lower end of the arc portion 62. The upper surface 23 and the lower surface 27 of the case 22 are inclined downward as they go radially outward. The upper surface 23 and the lower surface 27 of the case 22 are inclined downward as they go radially outward, so that the flow of air is smoothly guided radially outward from the outlet of the main blade 25 along a bottom plate 24 described later. This is for suppressing the eddy current.

The centrifugal multi-blade fan 20 includes a bottom plate 24, a number of main blades 25, a shroud 26, and sub-blades 70. The bottom plate 24 has a boss 28 to which a driving force from a fan driving motor 33 shown in FIG. 2 is transmitted. Also, the top surface 2 of the bottom plate 24
4a is formed into a curved surface that smoothly curves from the center to the outer periphery.

The main blade 25 is formed so as to rise from the vicinity of the outer peripheral end 24b of the bottom plate 24. The main blade 25 is provided at a predetermined arc interval along the circumferential direction near the outer peripheral end 24b of the bottom plate 24. Many are arranged. The shroud 26 includes a top surface 26c formed in an annular shape on the top of the main blade 25, and an annular protrusion 26b rising upward from the upper end on the inner diameter side of the top surface 26c, and also serves as a reinforcing ring. In the shroud 26, a line connecting the inner peripheral end 26 a of the shroud and the outer peripheral end 24 b of the bottom plate coincides with the parting line 30. The top surface 26c has a narrow gap with the inner wall of the case extending radially and annularly. By increasing the distance from the exit side to the entrance side of the main blade 25 in this gap, the backflow of the flow 201a shown in FIG. 3 is effectively suppressed.

Next, the features of the sub-blade of this embodiment will be described with reference to FIGS. Sub blade 70
Is formed integrally with the main blade 25 by resin molding. This sub-blade 70 is attached to the bottom plate 24
Extends below. An annular notch 72 cut upward is formed at the lower end of the sub-blade 70.
The notch 72 has a function of improving the loadability and transportability during storage of the centrifugal multi-blade fan. That is, as shown in FIG. 6, when storing the centrifugal multi-blade fan 20, a plurality of fans 20 are stacked upward. At this time, the protrusion 26b of the lower fan 20 fits into the notch 72 of the upper fan 20. The cut length of the notch 72 is longer than the rising length of the projection 26b. As a result, the protrusion 26b at the upper end of the main blade 25 and the notch 7 at the lower end of the sub-blade 70 are formed.
When the two abut against each other in an annular manner, the fans 20 can be stacked upward, and since the fans 20 are stacked by annular engagement, the collapse of the load of the fan 20 is prevented, so that storage and transportability are improved.

The case 22 for accommodating the centrifugal multi-blade fan 20 has a bell mouth 31 formed in a semicircular cross section so as to enclose the projection 26b of the shroud 26.
There is formed, a gap δ example about 3mm of small constant during this bellmouth inner wall 31a and the protrusion 26b.
The case inner wall 22c near the base of the bell mouth 31 is formed with a substantially constant small gap δ, for example, about 3 mm from the top surface 26c of the shroud 26. Such a substantially constant minute gap δ is formed from the outer peripheral wall of the projection 26b of the shroud 26 to the radially outer end 26d of the top surface 26c which is smoothly curved in the radially outward direction.

Generally, shroud 26 and bellmouth 31
It is desirable to narrow the gap between them. This is because a backflow is likely to occur in the gap between the shroud 26 and the bell mouth 31 due to a pressure difference between the low pressure side on the inlet side of the main blade 25 and the high pressure side on the outlet side of the main blade 25, so as to prevent this backflow. It is. The flow of the wind flowing from the blade inlet side to the blade outlet side is a flow 201 shown in FIG.
a, flow 201b, flow 201c, etc. The flow 201a is generated by the bell mouth 31 and the shroud 2 due to the pressure difference between the blade inlet side and the blade outlet side.
6, which is a cause of generating noise peculiar to the fan. The feature of the embodiment of the present invention is that this backflow is prevented.

Here, the height H _{1 of} the annular projection 26b, the gap H between the upper end of the annular projection 26b and the inner wall of the bell mouth 31
_2. The gap H ₃ between the main blade 25 and the protrusion 63 is
Each is set to have the following relationship. _{5 ≦ H 1 ≦ 10 (mm} ), 3 ≦ H 2 ≦ 5 (mm), 3 ≦ H 3 ≦ H 1 (mm), it was a _{5 ≦ H 1 ≦ 10 5 ≦} H 1 is, 5> H ₁ Then, shroud 2
This is because the amount of backflow of the flow 201a increases due to an increase in the gap between the protrusion 26b of No. 6 and the arc portion 62 of the bell mouth 31, and noise rises excessively. The reason why H ₁ ≦ 10 is that if H ₁ > 10, as can be understood from the graph shown in FIG. 4, if H ₁ is 8 mm or more, there is a sufficient noise reduction effect, and H ₁ is excessively large. Then, it extends upward and the mounting space becomes too large.

FIG. 4 is experimental data showing the relationship between the height of the annular projection 26b and the specific noise rise value when H ₂ = 3 mm (constant). The experimental conditions were as follows: fan diameter: 150
mm, fan width: 85 mm, scroll spread angle: 5.
5 °, blower motor voltage: 12 V (constant). 3 ≦ H ₂ ≦ 53 3 ≦ H ₂ because the size of H ₂ is at least 3 mm or more in order to prevent hitting due to assembly tolerance. The reason for setting H ₂ ≦ 5 is that, as shown in FIG. 5, when H ₂ exceeds 5 mm, the flow rate of the flow 201a is excessively increased and the noise becomes remarkable.

[0018] Note that FIG. 5 shows the experimental data showing the relationship between the gap H ₂ and the specific noise rise value of the upper end and the bell mouth inner wall of the annular projection 26b when the H ₁ = 8 mm (constant).
The experimental conditions were as follows: fan diameter: 150 mm, fan width: 85 m
m, scroll spread angle: 5.5 °, and blower motor voltage: 12 V (constant). The reason for setting 3 ≦ H ₃ ≦ H ₁₃ ≦ H ₃ is that it is necessary to secure at least 3 mm or more due to assembly tolerance in order to avoid contact between the protrusion 63 and the blade. Was a H ₃ ≦ H _1, the length of the projecting portion 63 is shown that may be at 0 or greater. In the present invention, the protrusion 63 may be formed, and even if it is not formed, the backflow prevention effect as shown by the flow 201a is obtained.

According to the above-described embodiment, the air flow taken in from the air inlet 36 is directed outward from the fan axial direction to the fan radial direction.
The shroud 26 is formed into a substantially arc-shaped cross-sectional shape so as to change the direction, and the gap between the shroud 26 and the bell mouth inner wall 31a and the case inner wall 22c is narrow due to the minute gap δ, and a long distance from the inner diameter side to the outer diameter side. Therefore, the amount of air that tends to flow backward from the outlet of the main blade 25 to the inner diameter side through the gap is reduced. Therefore, it is possible to improve fan efficiency and reduce noise.

Next, the embodiment of the present invention and a conventional comparative example will be described with reference to FIGS. Backflow Prevention Effect In the embodiment shown in FIG. 3, the air flow is formed in the direction of arrow 200 from the air inlet 36 of the bell mouth 31, and the air flow direction is gradually changed from the fan axis direction to the fan radial outside direction. Arrow 201 from the outer end of the main blade 25
A flow is formed in the directions b and 201c. At this time, since the bell mouth inner wall 31a, the upper surface 23 of the case 22, and the shroud 26 are kept in a narrow gap δ over a long area, the backflow flowing through the gap δ shown in the above-described range hardly occurs. On the other hand, in the conventional comparative example shown in FIG.
The area of the narrow gap with 3a is very short, and the backflow 101 flowing through this gap cannot be completely eliminated. This backflow causes a reduction in fan efficiency and an increase in noise.

The effect of preventing eddy currents between blades The wind speed distribution at the outlet of the main blade 25 is biased to the lower side of the main blade 25 as shown in FIG. Air hardly flows above the main blade 25.
For this reason, when the ventilation resistance is slightly increased, the vortex 102 and the backflow 103 occur in the comparative example of FIG. On the other hand, in the embodiment shown in FIG. 3, since the shroud 26 is provided, no eddy current or backflow occurs between the main blades 25, so that it is possible to effectively improve the fan efficiency and reduce the noise.

The effect of preventing eddy currents at the upper portion of the scroll The multi-blade blowers of the above embodiment and the comparative example are blowers applied to a ventilation system of a vehicle air conditioner. However, such a blower has a larger air volume than a static pressure. Large. Therefore, in the comparative example shown in FIG. 7, since the extra space 38 is provided inside the scroll above the position of the main blade 25, the vortex 104 is generated, so that the fan efficiency is reduced and the noise is likely to increase. On the other hand, in the embodiment shown in FIG. 3, since the extra space on the radially outer side of the main blade 25 is formed narrow, eddy currents and backflows are less likely to occur, improving fan efficiency and reducing noise. Reduction can be effectively achieved.

The present invention has the above-mentioned effects when applied to a multi-blade blower in general. Particularly, when the present invention is applied to a ventilation system having a relatively large ventilation resistance, such as a ventilation system of an air conditioner, the effects are remarkable. It is.

[0024]

As described above, according to the multi-blade blower of the present invention, a shroud is formed at the top of a large number of blades, and air is blown from the air inlet to the fan radial direction from the fan axial direction to the fan axial direction. A shroud is formed in a substantially arc-shaped cross-sectional shape along the inflowing air flow so as to change the direction of the flow, and a height H ₁ of an annular projection formed at a radially inner end of the shroud, an upper end of the annular projection, Having defined a clearance of H ₂ between the bellmouth inner wall within a certain range, to suppress the backflow through the gap, there is an effect that it is possible to improve and reduce the noise of the fan efficiency.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a right half of a multi-blade blower according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment in which the multi-blade blower of the present invention is applied to a vehicle air conditioner.

FIG. 3 is a schematic configuration diagram illustrating a main part of a multi-blade blower according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a height of an annular protrusion and a specific noise rise value.

FIG. 5 is a characteristic diagram showing a relationship between a gap between an annular protrusion and a bellmouth inner wall and a specific noise rise value.

FIG. 6 is a sectional view of a main part showing a state in which fans according to an embodiment of the present invention are stacked before being assembled.

FIG. 7 is a sectional view of a main part showing a conventional multi-blade blower.

[Explanation of symbols]

 Reference Signs List 6 multi-blade blower 20 centrifugal multi-blade fan (fan) 22 case 22c case inner wall 24 bottom plate 25 main blade 26 shroud 26b annular protrusion 26c top surface 31 bell mouth 36 air intake

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-356631 (JP, A) JP-A-64-60799 (JP, A) JP-A-57-68600 (JP, A) 70408 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04D 29/42 F04D 29/16

Claims (1)

(57) [Claims] 1. A case having a bell mouth forming an air intake, a number of blades housed in the case and arranged in a circumferential direction, and formed at an air suction side end of the number of blades. A centrifugal multi-blade fan having an annular shroud and a bottom plate formed at a non-air suction side end of the plurality of blades, wherein the shroud comprises an annular protrusion and a top surface, and the shroud extends from the air intake to the air inlet. It is formed in a substantially arc-shaped cross-section along the air flow that flows between the blades while changing its direction from the fan axis direction to the fan diameter outside direction, and the inner wall cross-section near the bell mouth of the case is between the blade and the shroud. The shroud is formed along the cross-sectional shape of the shroud via a minute gap.
The annular projection is formed from the outer peripheral wall to the radially outer end of the top surface, and the bell mouth of the case is formed with an annular concave portion as viewed from the blade side.The annular inner end of the shroud is formed with the annular shape. said annular projection extending into the recess is formed, the annular projection of height H1, when the gap H2 of between the upper end and the bell mouth of the annular projection, 5 ≦ H1 ≦ 10 (mm ), 3 ≦ H2 ≦ 5 ( mm), The multi-blade blower characterized by these.