JP6844526B2 - Multi-wing centrifugal fan - Google Patents

Description

The present invention relates to a sirocco fan, which is a multi-blade centrifugal fan used in, for example, an air conditioner.

Conventionally, as shown in FIGS. 8, 9, 10 and 11, some multi-blade centrifugal fans of this type are composed of a scroll casing 101 and an impeller 102 (see, for example, Patent Document 1).

FIG. 8 shows a perspective view of the conventional multi-blade centrifugal fan described in the publication.

Further, FIG. 9 shows a cross-sectional view (XX'cross-sectional view in FIG. 8) in a plane passing through the central axis of the impeller of the conventional multi-blade centrifugal fan and substantially the center in the height direction of the air outlet. Is.

FIG. 10 shows a perspective view of an impeller of a conventional multi-blade centrifugal fan.

FIG. 11 shows a partial cross-sectional view of a YY'cross section in FIG. 10 of an impeller of a conventional multi-blade centrifugal fan.

As shown in FIGS. 8 and 9, an abbreviation that connects the air outlet 103, the bell mouth 104 serving as an air suction port, the spiral air flow path 105, and the lower portion of the air outlet 103 and the air flow path 105. A scroll casing 101 having an arc-shaped tongue portion 106, and a large number of blades 109 arranged in an annular shape from a main plate 108 in the scroll casing 101 integrated with a bearing 107 and facing the bell mouth 104. It is composed of a multi-blade centrifugal impeller 102 that blows out air sucked from a suction port 110 formed at an end in the direction of the rotation axis from between the blades 109 in the centrifugal direction. A holding ring 111 for holding the blade 109 is provided at the axial end portion on the outer circumference of the impeller 102, and the width is wider than that of the holding ring 111 near the tongue portion 106 on the inner surface of the scroll casing 101 facing the holding ring 111. By providing the recess 112 having the above, the gap size between the scroll casing 101 and the impeller 102 can be made closer than before, and the noise and power consumption at the same air volume as the conventional one can be reduced.

Japanese Unexamined Patent Publication No. 2013-50031

As shown in FIG. 9, in a multi-blade centrifugal fan generally having a scroll casing, a circulation flow in which a part of the air W blown out from the impeller passes through the inside of the bell mouth and re-flows into the impeller from the suction port. W'occurs.

However, in the conventional configuration, as shown in FIG. 11, in the partial cross-sectional view of the holding ring 111, when the circulating flow W'flowing in the vicinity of the holding ring 111 returns between the blades 109, the central axis of the impeller 102 The first end surface 111a of the holding ring, which is substantially perpendicular to Z and is the outermost end of the impeller 102, and the inner surface 111b of the holding ring connected to the blade 109 substantially parallel to the central axis Z of the impeller 102 are connected at a substantially right angle. There is a problem that the air flow is separated at the connecting portion 111c and the noise is increased.

In order to solve the above-mentioned conventional problems, in a multi-blade centrifugal fan provided with an impeller and a scroll casing arranged so as to surround the impeller, the holding ring of the impeller is abbreviated as the central axis of the impeller. It is configured between the first end face of the holding ring, which is the most extreme end of the impeller vertically, the inner surface of the holding ring connected to the blades substantially parallel to the central axis of the impeller, and the first end face of the holding ring and the inner surface of the holding ring. It is provided with a connected connection surface.

As a result, even if the airflow is separated at the connection portion between the first end surface of the holding ring and the connecting surface or the connecting portion between the connecting surface and the inner surface of the holding ring, the airflow reattaches to the connecting surface or the inner surface of the holding ring and flows along the wall surface. To form.

Therefore, since the connection portion between the first end surface of the holding ring and the connection surface and the connection portion between the connection surface and the inner surface of the holding ring are connected at an obtuse angle, the airflow is separated as compared with the connection portion connected at a substantially right angle. Will be made smaller.

In the multi-blade centrifugal fan of the present invention, a part of the airflow blown out from the impeller in the centrifugal direction passes through the gap between the bell mouth and the holding ring, and the circulating flow that is sucked into the impeller again flows along the holding ring. It is possible to suppress the separation of the airflow at the connection portion between the connecting surface and the inner surface of the holding ring when re-inflowing from between, and it is possible to reduce the noise caused by the separation of the airflow.

Perspective view of the multi-blade centrifugal fan according to the first embodiment of the present invention. AA'cross-sectional view of the multi-blade centrifugal fan according to the first embodiment of the present invention. BB'cross-sectional view of the multi-blade centrifugal fan according to the first embodiment of the present invention. Perspective view of the impeller of the multi-blade centrifugal fan according to the first embodiment of the present invention. Partial sectional view of CC'cross section of the impeller according to the first embodiment of the present invention. Partial cross-sectional view of the CC'cross section of the holding ring of the arcuate connecting surface according to the first embodiment of the present invention. Enlarged perspective view of the impeller according to the first embodiment of the present invention. Perspective view of a conventional multi-blade centrifugal fan X-X'Cross section of the multi-blade centrifugal fan of the conventional multi-blade centrifugal fan Perspective view of impeller of conventional multi-blade centrifugal fan Partial cross-sectional view of the YY'cross section of the impeller of a conventional multi-blade centrifugal fan

In the first invention, the main plate, a plurality of blades radially arranged on the outer periphery of the main plate with respect to the central axis of the main plate, and the plurality of blades on the side opposite to the portion where the blades and the main plate are joined. An impeller equipped with a holding ring for fixing the outer periphery of the blades, an air outlet, a bell mouth serving as an air suction port, and a scroll casing arranged so as to surround the impeller. In the multi-blade centrifugal fan, the holding ring is at least substantially perpendicular to the central axis of the impeller and substantially perpendicular to the first end surface of the holding ring which is the outermost end of the impeller and the central axis of the impeller. The second end surface of the holding ring facing the first end surface of the holding ring, the inner surface of the holding ring connected to the blade substantially parallel to the central axis of the impeller, and the blade substantially parallel to the central axis of the impeller. The outer surface of the holding ring, which is the outermost periphery of the vehicle, and the connecting surface formed between the first end surface of the holding ring and the inner surface of the holding ring are provided , and the blade end portion of the blade reaches a position where it comes into contact with the connecting surface. A blade extending portion to be extended is formed, and the blade extending portion and the blade end portion are arcuate, and the air flowing through the connecting surface of the holding ring is guided to the blade by the blade extending portion. is there.
It is configured to be less than. In the first invention, the main plate, a plurality of blades radially arranged on the outer periphery of the main plate with respect to the central axis of the main plate, and the above-mentioned on the side opposite to the portion where the blades and the main plate are joined. A multi-blade centrifuge equipped with an impeller having a holding ring for fixing the outer circumferences of a plurality of blades, a bell mouth serving as an air outlet and an air suction port, and a scroll casing arranged so as to surround the impeller. In the fan, the blades are extended from the main plate in the direction of the holding ring, and a negative pressure surface that becomes a negative pressure when the impeller rotates, a positive pressure surface that becomes a positive pressure when the impeller rotates, and the impeller. A blade side portion serving as an axial end portion of the above, at least one negative pressure side connecting surface formed between the negative pressure surface and the blade side portion, and between the positive pressure surface and the blade side portion. A first negative pressure side connection portion which includes at least one positive pressure side connection surface and is a connection portion between the blade side portion and the negative pressure side connection surface, and a connection portion between the negative pressure surface and the negative pressure side connection surface. A wire connecting the second negative pressure side connection portion, or a first positive pressure side connection portion which is a connection portion between the blade side portion and the positive pressure side connection surface, and a connection portion between the positive pressure surface and the positive pressure side connection surface. The angle between one of the lines connecting the second positive pressure side connection portion and the substantially center line in the cross-sectional view in which the blade is cut at an arbitrary position in the direction of the central axis of the impeller is less than 90 °. It is configured to be.

As a result, even if the airflow is separated at the connection portion between the first end surface of the holding ring and the connecting surface or the connecting portion between the connecting surface and the inner surface of the holding ring, the airflow reattaches to the connecting surface or the inner surface of the holding ring and flows along the wall surface. To form. Further, even when the rotation speed of the impeller is high and the flow along the holding ring flows in at an angle facing the end of the blade, the turbulence of the air flow due to the collision with the blade is suppressed.

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

(Embodiment 1)
FIG. 1 shows a perspective view of a multi-blade centrifugal fan according to the first embodiment of the present invention. Further, FIG. 2 shows a vertical cross section at an arbitrary position between the bell mouth, which is the air suction port of the multi-blade centrifugal fan in the first embodiment of the present invention, and the main plate of the impeller, from the bell mouth side. It is a cross-sectional view (AA'cross-sectional view in FIG. 1) seen on the center side of the above.

FIG. 3 is a cross-sectional view (BB'in FIG. 2) in a plane passing through the central axis of the impeller of the multi-blade centrifugal fan and substantially the center in the height direction of the air outlet according to the first embodiment of the present invention. Sectional view) is shown.

FIG. 4 shows a perspective view of an impeller of a multi-blade centrifugal fan according to the first embodiment of the present invention.

In FIGS. 1 to 4, the multi-blade centrifugal fan is composed of an impeller 1 and a scroll casing 2.

The impeller 1 is arranged at substantially the center of the main plate 3, the bearing 4 integrated with the main plate 3, and the outer circumference of the main plate 3 radially with respect to the central axis of the main plate 3 with respect to the rotation direction M. It is provided with a plurality of blades 5 arranged so as to be tilted forward, and a holding ring 6 for fixing the outer periphery of the plurality of blades 5 on the side opposite to the portion where the blade 5 and the main plate 3 are joined. A rotating shaft of a fan motor (not shown) is pivotally attached to the bearing 4.

The scroll casing 2 is an arc-shaped tongue arranged at a position where the gap between the air outlet 7, the bell mouth 8 serving as an air suction port, and the outer circumference of the impeller 1 and the inner circumference of the scroll casing 2 is minimized. It is provided with a part 9.

FIG. 5 shows a partial cross-sectional view of the CC'cross section of the impeller according to the first embodiment of the present invention.

In FIG. 5, the holding ring 6 has a holding ring first end surface 6a that is substantially perpendicular to the central axis of the impeller 1 and is the outermost end of the impeller 1, and a holding ring first end surface that is substantially perpendicular to the central axis of the impeller 1. The second end surface 6b of the holding ring facing 6a, the inner surface 6c of the holding ring connected to the blade 5 substantially parallel to the central axis of the impeller 1, and the impeller 1 substantially parallel to the central axis of the impeller 1. It is composed of an outermost holding ring surface 6d and a connecting surface 6e formed between the holding ring first end surface 6a and the holding ring inner surface 6c, and the holding ring first end surface 6a and the connecting surface 6e. It has a first connection portion 6f of the connection portion and a second connection portion 6g of the connection portion between the connection surface 6e and the inner surface 6c of the holding ring.

The connection surface 6e is an angle formed by a line connecting the first connection portion 6f and the second connection portion 6g and the central axis Z of the impeller 1, and the angle D on the side close to the holding ring 6 is 20 ° to 70. ° is desirable.

The operation and operation of the multi-blade centrifugal fan configured as described above will be described below. 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 by the blades 5 to the outer periphery of the impeller 1 and inside the scroll casing 2. After colliding with the circumference, it flows along the inner circumference 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 pressure of the air on the inner circumference of the impeller 1 decreases, and the air flows from the bell mouth 8 to the impeller 1 due to the pressure difference from the atmospheric pressure.

Air is blown by this series of flows. In particular, in the multi-blade centrifugal fan as in the present embodiment, the air discharged to the outer periphery of the impeller 1 and having a high speed is the gap between the impeller 1 and the scroll casing 2. Is converted into pressure when the speed decreases as the speed decreases from the tongue portion 9, achieving both a high air volume and a static pressure.

After the mainstream air flow W collides with the inner circumference of the scroll casing 2, a part of the air flow W'is attracted to a portion between the blades 5 where the air pressure is low, and a circulating flow W'is generated. As shown in the above, after bypassing the holding ring 6 from the flow path formed in the gap between the inner surface of the bell mouth 8 and the impeller 1, the air flows back into the impeller 1 from between the blades 5.

In the present embodiment, the connecting surface 6e is configured between the holding ring first end surface 6a and the holding ring inner surface 6c, so that the connecting portion 6f between the holding ring first end surface 6a and the connecting surface 6e is connected. Since the connecting portion 6g between the surface 6e and the inner surface 6c of the holding ring is connected at an obtuse angle, the separation of the airflow re-inflowing into the impeller 1 is smaller than that of an impeller having a connecting portion connected at a substantially right angle. To do.

Therefore, the circulating flow W'flowing along the holding ring 6 is the connecting surface 6e and the holding ring inner surface 6
It reattaches to c and can smoothly merge with the mainstream W.

As described above, in the present embodiment, the connection surface 6e is configured between the holding ring first end surface 6a and the holding ring inner surface 6c, so that the connecting portion between the holding ring first end surface 6a and the connecting surface 6e Since 6f and the connection portion 6g between the connection surface 6e and the inner surface 6c of the holding ring are connected at an obtuse angle, the separation of the airflow is smaller than that of the connection portion connected at a substantially right angle, which is caused by this separation of the airflow. Noise can be reduced.

Further, FIG. 6 shows a partial cross-sectional view of a CC'cross section of the holding ring of the arc-shaped connecting surface according to the first embodiment of the present invention.

By forming the connecting surface of the present embodiment as an arc-shaped connecting surface 6h as shown in FIG. 6, the separation of the airflow is reduced as compared with the multi-sided connecting surface 6e.

In general, the slower the airflow velocity, the greater the separation of the airflow. Therefore, even when the difference between the pressure in the space between the bell mouth 8 and the holding ring 6 is relatively small and the velocity of the circulating flow W'is slow, the separation of the air flow on the arc-shaped connecting surface 6h is suppressed. It becomes.

Therefore, the circulation flow W'is relatively slow at low rotation, and even during low load operation, the airflow at the connection portion between the isolated connection surface 6h and the holding ring inner surface 6c when re-flowing from between the blades 5 is generated. This is suppressed, and the noise caused by the separation of the airflow can be reduced.

Further, FIG. 7 shows an enlarged perspective view of the impeller according to the first embodiment of the present invention.

As shown in FIG. 7, in the present embodiment, the holding ring No. 5 is provided by providing the blade extending portion 5a in which the joint portion of the blade 5 with the holding ring 6 is extended to a position where it comes into contact with the arc-shaped connecting surface 6h. A part of the flow from the end surface 6a along the arc-shaped connecting surface 6h is guided to the blade 5.

Therefore, even when the rotation speed of the impeller 1 is high and the flow along the holding ring 6 flows in at an angle facing the end of the blade 5, the turbulence of the air flow due to the collision with the blade 5 is suppressed.

Therefore, even in the case of high load operation in which the rotation speed of the impeller 1 is the highest, the airflow flowing along the holding ring 6 is caused by the collision with the blade 5 when it flows in at an angle facing the end of the blade 5. It is possible to suppress the separation of the airflow and reduce the noise caused by the separation of the airflow.

As described above, in the multi-blade centrifugal fan according to the present invention, a part of the airflow discharged from the outer periphery of the impeller suppresses separation at the holding ring of the circulating flow flowing in from between the blades, and is air-conditioned. It can be applied to machines, air purifiers, dryers, car air conditioners, etc.

1 Impeller 2 Scroll casing 3 Main plate 5 Blades 5a Blade extension 6 Holding ring 6a Holding ring 1st end surface 6b Holding ring 2nd end surface 6c Holding ring inner surface 6d Holding ring outer surface 6e Connection surface 6h Arc-shaped connection surface 7 Air outlet 8 Bellmouth (air suction port)

Claims (1)

The main plate, a plurality of blades radially arranged on the outer periphery of the main plate with respect to the central axis of the main plate, and the outer periphery of the plurality of blades are fixed on the side opposite to the portion where the blade and the main plate are joined. In a multi-blade centrifugal fan provided with an impeller equipped with a holding ring, an air outlet, and a bell mouth serving as an air suction port, and a scroll casing arranged so as to surround the impeller.
The holding ring includes at least the first end surface of the holding ring which is substantially perpendicular to the central axis of the impeller and is the most end portion of the impeller.
A holding ring second end surface that is substantially perpendicular to the central axis of the impeller and is opposed to the holding ring first end surface.
The inner surface of the holding ring connected to the blade substantially parallel to the central axis of the impeller,
The outer surface of the holding ring, which is substantially parallel to the central axis of the impeller and is the outermost circumference of the impeller,
A connecting surface formed between the first end surface of the holding ring and the inner surface of the holding ring is provided .
A blade extending portion extending to a position in contact with the connecting surface is formed on the blade tip portion of the blade.
The blade extension portion and the blade tip portion are arcuate and have an arc shape.
A multi-blade centrifugal fan characterized in that air flowing through the connecting surface of the holding ring is guided to the blades by the blade extending portion.