CN109958633B

CN109958633B - Multi-blade centrifugal fan

Info

Publication number: CN109958633B
Application number: CN201810938653.2A
Authority: CN
Inventors: 重田明广
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2017-12-26
Filing date: 2018-08-17
Publication date: 2022-02-18
Anticipated expiration: 2038-08-17
Also published as: JP6844526B2; JP2019113037A; CN109958633A; EP3505769B1; ES2871900T3; EP3505769A1

Abstract

The invention provides a multi-blade centrifugal fan, which can inhibit a part of an air flow (W) blown out from an impeller (1) in a centrifugal direction from being sucked into the impeller (1) again through a gap between a bell mouth (8) and a retaining ring (6) to form a circulating flow (W'), and can separate the air flow when the air flow flows in again from blades (5) along the retaining ring (6), thereby reducing the noise caused by the air flow separation. In a multi-blade centrifugal fan including an impeller (1) and a scroll case (2) disposed so as to surround the impeller (1), a retainer ring (6) of the impeller (1) includes: a retaining ring 1 st end surface 6a which is substantially perpendicular to the central axis of the impeller 1 and is the outermost end of the impeller 1; a retainer ring inner surface (6c) that is substantially parallel to the central axis of the impeller (1) and is connected to the blade (5); and a connecting surface (6e) formed between the 1 st end surface (6a) of the retainer ring and the inner surface (6c) of the retainer ring.

Description

Multi-blade centrifugal fan

Technical Field

The present invention relates to a multiblade fan as a multiblade centrifugal fan used in, for example, an air conditioner or the like.

Background

As shown in fig. 8, 9, 10, and 11, a conventional centrifugal fan of this type includes a scroll casing 101 and an impeller 102 (see, for example, patent document 1).

Fig. 8 is a perspective view of the conventional sirocco fan disclosed in the above publication.

Fig. 9 is a cross-sectional view of a plane passing through the center axis of the impeller of the conventional sirocco fan and a substantially central portion in the height direction of the air outlet (X-X' cross-sectional view of fig. 8).

Fig. 10 is a perspective view of an impeller of a conventional multiblade centrifugal fan.

Fig. 11 is a partial sectional view of the impeller of the conventional multiblade centrifugal fan, taken along the Y-Y' section in fig. 10.

As shown in fig. 8 and 9, the centrifugal impeller is composed of a scroll casing 101 and a multi-blade centrifugal impeller 102, wherein the scroll casing includes: an air outlet 103, a bell mouth 104 as an air inlet, a spiral air flow path 105, and a substantially arc-shaped tongue 106 connecting a lower portion of air outlet 103 and air flow path 105, impeller 102 is configured by arranging a plurality of blades 109 in a ring shape in scroll casing 101 from a main plate 108 integrated with a bearing 107, and blows out air sucked in from an inlet 110 formed at one end in the rotation axis direction opposite to bell mouth 104 in the centrifugal direction from between blades 109. A retaining ring 111 for retaining the blades 109 is provided at an axial end portion of the outer periphery of the impeller 102, and a recess 112 wider than the retaining ring 111 is provided near the tongue 106 of the inner surface of the scroll casing 101 facing the retaining ring 111, whereby the gap size between the scroll casing 101 and the impeller 102 can be made closer (smaller) than in the related art, and noise and power consumption at the same air volume as in the related art can be reduced.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-50031

Disclosure of Invention

Problems to be solved by the invention

As shown in fig. 9, in general, in a multiblade centrifugal fan having a scroll casing, a circulating flow W' is generated in which a part of air W blown out from an impeller flows into the impeller again from a suction port through the inside of a bell mouth.

However, in the above-described conventional structure, as shown in fig. 11, when the circulating flow W' flowing near the retainer ring 111 returns to the blades 109 in the partial cross-sectional view of the retainer ring 111, separation of the flow occurs at the retainer ring 1 st end surface 111a which is substantially perpendicular to the central axis Z of the impeller 102 and is the endmost portion of the impeller 102, and the connecting portion 111c which is substantially parallel to the central axis Z of the impeller 102 and is connected to the retainer ring inner surface 111b connected to the blades 109 at substantially right angles, and noise increases.

Means for solving the problems

In order to solve the above-described conventional problem, in a multiblade centrifugal fan including an impeller and a scroll casing disposed so as to surround the impeller, a retaining ring of the impeller includes: a 1 st end surface of the retaining ring which is approximately vertical to the central axis of the impeller and is positioned at the position closest to the end part of the impeller; an inner surface of the retainer ring substantially parallel to a central axis of the impeller and connected to the blades; and a connecting surface formed between the 1 st end surface of the retainer ring and the inner surface of the retainer ring.

Thus, even if the separation of the airflow occurs at the connection portion between the 1 st end surface of the retainer ring and the connection surface or at the connection portion between the connection surface and the inner surface of the retainer ring, the airflow that again adheres to the connection surface or the inner surface of the retainer ring and flows along the wall surface is formed.

Therefore, the connection portion between the 1 st end surface of the retainer ring and the connection surface and the connection portion between the connection surface and the inner surface of the retainer ring are connected at an obtuse angle, and therefore, the separation of the air flows is reduced as compared with the connection portion connected at a substantially right angle.

Effects of the invention

The present invention provides a multiblade centrifugal fan which can suppress separation of air flow generated at a connecting portion between a connecting surface and an inner surface of a retaining ring when a circulating flow which is again sucked into an impeller flows again along the retaining ring from between blades while a part of the air flow blown out from the impeller in a centrifugal direction passes through a gap between a bell mouth and the retaining ring, and reduce noise caused by the separation of the air flow.

Drawings

Fig. 1 is a perspective view of a sirocco fan according to embodiment 1 of the present invention.

Fig. 2 is a sectional view a-a' of a sirocco fan according to embodiment 1 of the present invention.

Fig. 3 is a B-B' sectional view of a sirocco fan according to embodiment 1 of the present invention.

Fig. 4 is a perspective view of an impeller of a multiblade centrifugal fan according to embodiment 1 of the present invention.

Fig. 5 is a partial sectional view of a section C-C' of the impeller according to embodiment 1 of the present invention.

FIG. 6 is a partial cross-sectional view of a retaining ring in section C-C' of the arcuate connecting surface of embodiment 1 of the present invention.

Fig. 7 is an enlarged perspective view of the blade according to embodiment 1 of the present invention.

Fig. 8 is a perspective view of a conventional multiblade centrifugal fan.

FIG. 9 is a cross-sectional view of a conventional multiblade centrifugal fan at X-X

Fig. 11 is a partial sectional view of a conventional impeller of a multiblade centrifugal fan, taken along the Y-Y' section.

Description of the reference numerals

1 impeller

2 volute casing

3 mainboard

5 blade

5a blade extension

6 retaining ring

6a retaining Ring 1 st end face

6b retaining ring 2 nd end face

6c inner surface of retaining ring

6d outer surface of retaining ring

6e connecting surface

6h arc connecting surface

7 air outlet

8 horn mouth (air suction inlet)

Detailed Description

The multiblade centrifugal fan of claim 1 comprises: an impeller including a main plate, a plurality of blades radially arranged on an outer periphery of the main plate with respect to a central axis of the main plate, and a retaining ring for fixing outer peripheries of the plurality of blades on a side opposite to a joint portion between the blades and the main plate; and a scroll casing having an air outlet and a bell mouth as an air inlet and disposed so as to surround the impeller, wherein the holding ring includes at least: a 1 st end surface of the retainer ring which is substantially perpendicular to a central axis of the impeller and is located at a position closest to an end of the impeller; a retainer ring 2 nd end surface substantially perpendicular to a central axis of the impeller and facing the retainer ring 1 st end surface; an inner surface of the retainer ring substantially parallel to a central axis of the impeller and connected to the blades; a retaining ring outer surface which is substantially parallel to a central axis of the impeller and is an outermost periphery of the impeller; and a connecting surface formed between the 1 st end surface of the retainer ring and the inner surface of the retainer ring.

This makes it possible to suppress separation of the airflow at the connection portion between the connection surface and the inner surface of the retainer ring when a circulating flow formed by a portion of the airflow blown out from the impeller in the centrifugal direction passing through the gap between the bell mouth and the retainer ring and being sucked into the impeller again flows along the retainer ring again between the blades, thereby reducing noise caused by the separation of the airflow.

The invention described in claim 2 is characterized in that the connection surface is formed in an arc shape in a cross-sectional view obtained by cutting the retainer ring at an arbitrary position in the central axis direction of the impeller. This reduces the separation of the airflow at the connection between the 1 st end surface of the retainer ring and the inner surface of the retainer ring, as compared with the polygonal connection.

In addition, generally, the slower the velocity of the gas stream, the greater the separation of the gas stream. Therefore, even when the difference in pressure in the space between the bell mouth and the retainer ring is small and the speed of the circulating flow is low, the flow separation at the connection surface can be suppressed.

Thus, even during low-load operation in which the rotation is low and the circulation flow is slow, the airflow at the connection portion between the connection surface and the inner surface of the retainer ring when the airflow again flows between the blades can be suppressed, and noise caused by the separation of the airflow can be reduced.

The invention of claim 3 is characterized in that the blade extends to a position contacting the connection surface. Thereby, a part of the air flow along the retaining ring is directed towards the blades.

Therefore, even when the rotation speed of the impeller is high and the airflow along the retainer ring flows in at an angle to the blade end, disturbance of the airflow due to collision with the blades is suppressed.

Thus, even in a high-load operation in which the rotation speed of the impeller is the highest, separation of the airflow due to collision with the blades when the airflow flowing along the retainer ring flows at an angle to the end portions of the blades can be suppressed, and noise caused by the separation of the airflow can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment.

(embodiment mode 1)

Fig. 1 is a perspective view of a sirocco fan according to embodiment 1 of the present invention. Fig. 2 is a longitudinal sectional view of the sirocco fan according to embodiment 1 of the present invention, taken from the bellmouth side to the center side of the impeller, at an arbitrary position between the bellmouth as the air inlet and the main plate of the impeller (a sectional view a-a' in fig. 1).

Fig. 3 is a sectional view (a sectional view B-B' in fig. 2) of a plane passing through substantially the center of the center axis of the impeller and the center of the air outlet in the height direction of the sirocco fan according to embodiment 1 of the present invention.

In fig. 1 to 4, the centrifugal fan with multiple blades is composed of an impeller 1 and a scroll casing 2.

The impeller 1 includes: a main board 3; a bearing 4 disposed substantially at the center of the main plate 3 and integrated with the main plate 3; a plurality of blades 5 arranged radially with respect to the central axis of the main plate 3 at the outer periphery of the main plate 3 so as to be inclined forward with respect to the rotation direction M; and a retaining ring 6 that fixes the outer peripheries of the plurality of blades 5 on the opposite side of the portion where the blades 5 are joined to the main plate 3. A rotary shaft of a fan motor (not shown) is pivotally fixed to the bearing 4.

The scroll casing 2 includes: an air outlet 7; a bell mouth 8 as an air suction inlet; and an arc-shaped tongue portion 9 disposed at a position where a gap between the outer periphery of the impeller 1 and the inner periphery of the scroll casing 2 is minimum.

In fig. 5, the retaining ring 6 includes: a retaining ring 1 st end surface 6a which is substantially perpendicular to the central axis of the impeller 1 and is the outermost end of the impeller 1; a retaining ring 2 nd end surface 6b which is substantially perpendicular to the central axis of the impeller 1 and is positioned opposite to the retaining ring 1 st end surface 6 a; a retainer ring inner surface 6c which is substantially parallel to the central axis of the impeller 1 and connected to the blades 5; a retainer ring outer surface 6d that is substantially parallel to the central axis of the impeller 1 and serves as the outermost periphery of the impeller 1; and a 1 st joint part 6f formed between the 1 st end surface 6a of the retainer ring and the inner surface 6c of the retainer ring, and having a joint of the 1 st end surface 6a of the retainer ring and the joint surface 6 e; and a 2 nd connecting portion 6g connecting the connecting surface 6e and the inner surface 6c of the retainer ring.

The connection surface 6e is preferably an angle formed by a line connecting the 1 st connection portion 6f and the 2 nd connection portion 6g and the central axis Z of the impeller 1, and the angle D on the side closer to the retainer ring 6 is about 20 ° to 70 °.

Next, the operation and action of the centrifugal fan with multiple blades configured as described above will be described. First, as shown in fig. 2, when the impeller 1 rotates in the rotation direction M, the air W between the plurality of blades 5 is discharged to the outer periphery of the impeller 1 by the blades 5, collides with the inner periphery of the scroll casing 2, flows along the inner periphery of the scroll casing 2 in the same direction as the rotation direction M, and is blown out from the air outlet 7. Then, the air pressure in the inner periphery of the impeller 1 decreases, and the air flows into the impeller 1 from the bell mouth 8 due to the pressure difference with the atmospheric pressure.

Particularly in the sirocco fan according to the present embodiment, the air having a high speed discharged to the outer periphery of the impeller 1 is converted into pressure when the speed decreases as the gap between the impeller 1 and the scroll casing 2 gradually increases from the tongue portion 9, and a high air volume and a high static pressure are both satisfied.

When the air flow W as the main flow collides with the inner periphery of the scroll casing 2 and then a part thereof is guided to a portion where the air pressure between the blades 5 is low, a circulating flow W' is generated, and at this time, as shown in fig. 3, the air flow bypasses the retainer ring 6 from a flow path formed in a gap between the inner surface of the bell mouth 8 and the impeller 1, and then flows into the impeller 1 again from between the blades 5.

In the present embodiment, since the connecting surface 6e is formed between the retaining ring 1 st end surface 6a and the retaining ring inner surface 6c, the connecting portion 6f between the retaining ring 1 st end surface 6a and the connecting surface 6e and the connecting portion 6g between the connecting surface 6e and the retaining ring inner surface 6c are connected at an obtuse angle, and therefore, separation of the air flow flowing into the impeller 1 again is reduced as compared with an impeller having a connecting portion connected at a substantially right angle.

Therefore, the circulating flow W' flowing along the retainer ring 6 can be reattached to the connection surface 6e and the retainer ring inner surface 6c, and smoothly merges with the main flow W.

As described above, in the present embodiment, the connecting surface 6e is formed between the retaining ring 1 st end surface 6a and the retaining ring inner surface 6c, and the connecting portion 6f between the retaining ring 1 st end surface 6a and the connecting surface 6e and the connecting portion 6g between the connecting surface 6e and the retaining ring inner surface 6c are connected at an obtuse angle, so that the separation of the air flow can be reduced compared to a connecting portion connected at a substantially right angle, and the noise caused by the separation of the air flow can be reduced.

Fig. 6 is a partial cross-sectional view of the retaining ring at the C-C' section of the arcuate connecting surface according to embodiment 1 of the present invention.

By using the arc-shaped connecting surface 6h as shown in fig. 6 as the connecting surface of the present embodiment, the separation of the air flow is reduced as compared with the polygonal connecting surface 6 e.

In addition, generally, the slower the velocity of the gas stream, the greater the separation of the gas stream. Therefore, even when the difference in pressure in the space between the bell mouth 8 and the retainer ring 6 is small and the speed of the circulating flow W' is low, the separation of the air flow at the arc-shaped connecting surface 6h is suppressed.

Accordingly, even during low load operation in which the rotation is low and the circulating flow W' is slow, the airflow at the connection between the arcuate connection surface 6h and the retainer ring inner surface 6c when the airflow again flows between the blades 5 can be suppressed, and noise due to separation of the airflow can be reduced.

Fig. 7 is an enlarged perspective view of the impeller according to embodiment 1 of the present invention.

As shown in fig. 7, in the present embodiment, by providing the vane extension portion 5a that extends the joint portion of the vane 5 and the retainer ring 6 to the position where the joint portion contacts the arcuate joint surface 6h, a part of the airflow along the arcuate joint surface 6h from the retaining ring 1 st end surface 6a is guided to the vane 5.

Therefore, even when the rotational speed of the impeller 1 is high and the airflow along the retainer ring 6 flows in at an angle to the end of the blade 5, disturbance of the airflow due to collision with the blade 5 is suppressed.

Thus, even in the high load operation in which the rotation speed of the impeller 1 is the highest, when the airflow flowing along the retainer ring 6 flows in at an angle to the end of the blade 5, the airflow separation due to the collision with the blade 5 can be suppressed, and the noise caused by the airflow separation can be reduced.

Industrial applicability

As described above, the sirocco fan according to the present invention is used for suppressing separation of a circulating flow formed by inflow of a part of an air flow discharged from the outer periphery of the impeller from between the blades, in the retainer ring, and is applicable to applications such as an air conditioner, an air cleaner, a dryer, and an automobile air conditioner.

Claims

1. A multi-vane centrifugal fan comprising:

an impeller including a main plate, a plurality of blades arranged radially on an outer periphery of the main plate with respect to a central axis of the main plate, and a retaining ring for fixing outer peripheries of the plurality of blades on a side opposite to a joint portion between the blades and the main plate; and a scroll casing having an air outlet and a bell mouth as an air inlet and disposed so as to surround the impeller,

the retaining ring includes at least: a 1 st end surface of the retainer ring, which is substantially perpendicular to a central axis of the impeller and is located at a position closest to an end of the impeller; a retainer ring No. 2 end surface which is substantially perpendicular to a central axis of the impeller and is positioned opposite to the retainer ring No. 1 end surface; a retaining ring inner surface substantially parallel to a central axis of the impeller and connected to the blades; a retaining ring outer surface that is substantially parallel to a central axis of the impeller and that is an outermost periphery of the impeller; and a connecting surface formed between the 1 st end surface of the retainer ring and the inner surface of the retainer ring,

the connecting surface is formed in an arc shape in a cross-sectional view obtained by cutting the retaining ring at an arbitrary position in the central axis direction of the impeller,

the multiblade centrifugal fan includes a blade extension extending a joint portion of the blade with the retaining ring to a position contacting the connection face,

the air flowing from the 1 st end surface of the retainer ring along the joint surface is guided toward the vane by the vane extension.