JP2019173621A - Axial flow fan - Google Patents

Abstract

To provide an axial flow fan in which noise is reduced by decreasing back flow.SOLUTION: An inner peripheral region 73 in a range of a radius of a connecting part 100 between a blade 71 and a hub 72, an intermediate radius between the radius of the connecting part 100 and a radius at an outer peripheral part of an axial flow fan 70 is provided with auxiliary blades 74 extending toward a more rear point in a rotating direction than a reference rear edge line 80 connecting a front end point 79 positioned most-forward on a ridge line 76 at a rear side in a rotating direction of the blade 71 with an intermediate point 78 on the rear ridge line 76 in a rotating direction at a radius of the connecting part 100 and a radius at an outer peripheral part of the axial flow fan 70. With this arrangement as described above, since an area of the blade 71 at the inner peripheral region 73 is increased, it is possible to reduce reverse flow air flowing into a device where the axial flow fan 70 is operated, weaken eddy flow becoming a cause of noise of blowing air and reduce blowing air noise.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an axial fan that generates an air flow in the direction of a rotation axis by rotating.

  Conventionally, this type of axial fan is designed to reduce blowing noise by reducing the number of revolutions for blowing a predetermined air volume. In order to reduce the rotational speed of the axial fan, the area on the outer peripheral side of the blades of the axial fan having a large rotational peripheral speed and high air blowing capacity is increased (see, for example, Patent Document 1).

  FIG. 5 shows a conventional axial fan described in Patent Document 1. In FIG. As shown in FIG. 5, the axial fan 1 is composed of a hub 2, a blade 3, an outer peripheral region 4, and an outer peripheral region trailing edge 5 extended to increase the outer peripheral side area of the blade 3. Has been.

JP 2013-144951 A

  However, in the conventional configuration, the pressure difference between the internal pressure of the refrigeration cycle apparatus and the atmospheric pressure increases due to the increase in ventilation resistance accompanying the downsizing of the apparatus using the axial flow fan (for example, the refrigeration cycle apparatus). The increase in pressure in the axial fan due to the reduction in the rotational speed of the axial fan interacts with each other, and the air on the inner peripheral side of the axial fan with a low rotational peripheral speed and a low blowing capacity As a result, the vortex became strong and the blowing noise of the axial fan increased.

  The present invention solves the above-described conventional problems, and an object thereof is to provide an axial fan that reduces backflow of air on the inner peripheral side of the axial fan and reduces blowing noise.

  In order to solve the above-described conventional problems, an axial fan according to the present invention includes a plurality of blades, a hub, and a connecting portion between the blades and the hub, and the blades are arranged around the rotation axis by the hub. The axial flow fan is configured to be held at regular intervals and with a predetermined angle with respect to a plane orthogonal to the rotation axis, and the airflow is generated by rotating the blades. In the projection view in the direction of the axis of rotation of the axial fan, from the outer periphery of the axial fan between the radius of the connecting portion and the radius between the radius of the connecting portion and the radius of the outer periphery of the axial fan. , The most forward point on the rear ridge line in the rotational direction of the blade in the range up to the middle radius between the outer peripheral part of the axial fan and the connecting part, the radius of the connecting part and the outer peripheral part of the axial fan A point on the ridge line behind the rotation direction at an intermediate radius of Than the line, in which the axial flow fan is characterized in that it comprises a support blade extending rearward in the rotational direction.

This increases the blade area on the inner peripheral side of the axial fan and increases the pressure rise due to the axial fan. Therefore, the device that uses the axial fan is called a unit. When air is transferred from the outside air to the outside air, the air flowing backward from the outside air toward the inside of the unit is reduced, or when an axial fan is used to carry air from the outside air to the inside of the unit. The air flowing backward from the inside of the unit toward the outside air is reduced.

  The axial fan of the present invention can reduce the air that flows backward, and can reduce the blowing noise by weakening the vortex that causes the blowing noise.

Configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. The front view of the axial-flow fan in Embodiment 1 of this invention The front view of the 1st derivative form of the axial flow fan in Embodiment 1 of this invention The front view of the 2nd derivative form of the axial flow fan in Embodiment 1 of this invention Front view of a conventional axial fan

  A first invention includes a plurality of blades, a hub, and a connecting portion between the blades and the hub, and the blades are spaced by the hub at equal intervals around the rotation axis and orthogonal to the rotation axis. The axial fan is configured to be held at a predetermined angle with respect to the blade, and the airflow is generated by the rotation of the blades, and is projected in the direction of the rotation axis of the axial fan. In the figure, between the outer radius of the axial fan and the outer radius of the axial fan and the connecting portion between the radius of the connecting portion and the radius between the radius of the connecting portion and the outer radius of the axial fan. At the most forward point on the rearward ridge line in the rotational direction of the blade in the range up to the middle radius of the blade, and the radius between the radius of the joint of the blade and the hub and the radius of the outer periphery of the axial fan Than the straight line connecting the points on the ridge line behind the rotation direction, By providing an axial fan characterized by having auxiliary blades extending toward the shaft, the area of the blades can be increased on the inner peripheral side of the axial fan, and the pressure rise by the axial fan can be increased. A device that uses a flow fan is called a unit, and when an axial fan is used to transfer air from the inside of the unit to the outside air, the amount of air that flows backward from the outside air toward the inside of the unit decreases, or the shaft When a flow fan is used to convey air from outside air to the inside of the unit, the air flowing back from the inside of the unit toward the outside air will decrease, and the air flowing back can be reduced. The vortex can be weakened and the blowing noise can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment. In addition, the radius in the following embodiments includes a concept of an arc based on the radius as necessary.

(Embodiment 1)
FIG. 1 shows a configuration diagram of a refrigeration cycle apparatus according to a first embodiment of the present invention. FIG. 2 is a front view of the axial fan according to the first embodiment of the present invention. FIG. 3 is a front view of a first derivative form of the axial fan according to the first embodiment of the present invention. FIG. 4 is a front view of a second derivative form of the axial fan according to the first embodiment of the present invention.

  1, the refrigeration cycle apparatus 10 includes a main circuit 11, a compressor 20, an outdoor heat exchanger 31, an indoor heat exchanger 32, a four-way valve 40, an outdoor expansion valve 51, and an indoor expansion valve 52. The refrigerant storage tank 53, the outdoor blower 61, and the indoor blower 62 are provided, and radiate heat by the outdoor heat exchanger 31, absorb heat by the indoor heat exchanger 32, or absorb heat by the outdoor heat exchanger 31. The operation of radiating heat with the indoor heat exchanger 32 can be switched. A product using the refrigeration cycle apparatus 10 for the purpose of heating or cooling air is called an air conditioner or the like, and a product used for the purpose of heating or cooling water is called a chiller or the like.

  Moreover, as a form of the refrigeration cycle apparatus 10, an outdoor unit 12 including a compressor 20, an outdoor heat exchanger 31, a four-way valve 40, an outdoor expansion valve 51, a refrigerant storage tank 53, and an outdoor blower 61, The unit may be configured by separating the indoor unit 13 including the indoor heat exchanger 32, the indoor expansion valve 52, and the indoor blower 62, or the outdoor unit 12 and the indoor unit 13 may be configured. It may be configured as an integral unit. Further, in the configuration in which the outdoor unit 12 and the indoor unit 13 are separated, there are a case where the number of the outdoor units 12 and the indoor units 13 are the same, and a case where the number of the indoor units 13 is larger than that of the outdoor units 12.

  In the present embodiment, an example of the configuration of an air conditioner in which the outdoor unit 12 and the indoor unit 13 are separated and the outdoor unit 12 and the indoor unit 13 are one each, which is often seen in home air conditioners and store air conditioners. Show.

  When the main circuit 11 performs an operation of radiating heat with the outdoor heat exchanger 31 and absorbing heat with the indoor heat exchanger 32, the compressor 20, the first path 41 of the four-way valve 40, the outdoor heat exchanger 31, and the outdoor expansion. The valve 51, the refrigerant storage tank 53, the indoor expansion valve 52, and the indoor heat exchanger 32 are connected in this order, and the circuit returns from the indoor heat exchanger 32 to the compressor 20 via the second path 42 of the four-way valve 40. It is. The first path 41 of the compressor 20 and the four-way valve 40 flows through the flow path 91, the first path 41 of the four-way valve 40 and the outdoor heat exchanger 31 flow through the flow path 92, and the outdoor heat exchanger 31 and the outdoor expansion valve 51 flow. The passage 93 allows the outdoor expansion valve 51 and the refrigerant storage tank 53 to pass through the flow path 94, the refrigerant storage tank 53 and the indoor expansion valve 52 pass through the flow path 95, and the indoor expansion valve 52 and the indoor heat exchanger 32 pass through the flow path 96. The indoor heat exchanger 32 and the second path 42 of the four-way valve 40 are connected by a flow path 97, and the second path 42 of the four-way valve 40 and the compressor 20 are connected by a flow path 98. Moreover, when performing the operation | movement which absorbs heat with the outdoor heat exchanger 31 and thermally radiates with the indoor heat exchanger 32, the compressor 20, the 3rd path | route 43 of the four-way valve 40, the indoor heat exchanger 32, the indoor expansion valve 52, The refrigerant storage tank 53, the outdoor expansion valve 51, and the outdoor heat exchanger 31 are connected in this order, and return from the outdoor heat exchanger 31 to the compressor 20 via the fourth path 44 of the four-way valve 40. The third path 43 of the compressor 20 and the four-way valve 40 flows through the flow path 91, the third path 43 of the four-way valve 40 and the indoor heat exchanger 32 flows through the flow path 97, and the indoor heat exchanger 32 and the indoor expansion valve 52 flow. By the path 96, the indoor expansion valve 52 and the refrigerant storage tank 53 are connected by the flow path 95, the refrigerant storage tank 53 and the outdoor expansion valve 51 are connected by the flow path 94, and the outdoor expansion valve 51 and the outdoor heat exchanger 31 are connected by the flow path 93. The outdoor heat exchanger 31 and the fourth path 44 of the four-way valve 40 are connected by a flow path 92, and the fourth path 44 of the four-way valve 40 and the compressor 20 are connected by a flow path 98. Switching of the main circuit 11 according to the operation of the refrigeration cycle apparatus 10 is performed by a four-way valve 40. Inside the main circuit 11, a refrigerant represented by R32 and R410A and a compressor oil for lubricating the sliding portion of the compressor 20 are enclosed.

  The compressor 20 is slidably accommodated in a rotary compressor, that is, a cylinder having a cylindrical inner space, a rotor arranged eccentrically with respect to the central axis inside the cylinder, and a slit provided on the cylinder wall surface. The gate valve is configured such that the tip is always in contact with the cylindrical surface of the rotor, and the passage 91 and the communication hole to the passage 98 are provided on both sides of the gate in the cylinder.

  The outdoor heat exchanger 31 and the indoor heat exchanger 32 are fin-and-tube heat exchangers, that is, a plurality of round holes having a diameter of about 5 mm to 8 mm are opened in an aluminum plate having a thickness of about 0.1 mm, and It is equipped with fins with round holes bent in a collar shape and copper or aluminum tubes, and several hundreds of fins are arranged side by side, and the tubes are inserted into the round holes, so that the tubes are spread and closely attached to the fins. It is composed.

  The four-way valve 40 has a configuration in which a combination of the first path 41 and the second path 42 or the combination of the third path 43 and the fourth path 44 can be switched using a valve provided therein.

  The outdoor expansion valve 51 and the indoor expansion valve 52 are configured to partially reduce the flow of the refrigerant by reducing the cross-sectional area of the path through which the refrigerant flows with respect to the main circuit 11 or switching between closing and opening. Yes.

  The refrigerant storage tank 53 includes a container and two communication holes for connecting to the flow path 94 and the flow path 95. The pipe extends from the communication hole to the lower part inside the container. The accumulated liquid phase refrigerant is returned to the main circuit 11.

  The indoor blower 62 is generally a turbo fan, a sirocco fan, or a cross flow fan, but may be an axial fan.

  The outdoor blower 61 includes an axial fan 70, a bell mouth 88, and an electric motor 89. In the direction from the upstream side to the downstream side of the air flow generated by the axial fan 70, the outdoor heat exchanger 31, the electric motor 89, the axial fan 70, and the bell mouth 88 are arranged in this order. . The axial fan 70 is fixed to the rotating shaft of the electric motor 89. The electric motor 89 is fixed to the outdoor unit 12. The bell mouth 88 has a substantially cylindrical shape surrounding the axial flow fan 70 with a predetermined gap in the circumferential direction with respect to the rotation axis of the axial flow fan 70, and at least partially in the rotation axis direction. It arrange | positions so that it may overlap with the axial fan 70, and is being fixed to the outdoor unit 12.

  In FIG. 2, the axial fan 70 includes a plurality of blades 71 and a hub 72. The blade | wing 71 is fan shape which expands as it goes to an outer periphery. The forward ridge line 81 in the rotational direction of the blade 71 is positioned forward in the rotational direction toward the outer periphery. A ridge line 76 on the rear side in the rotation direction of the blade 71 is substantially linear, and is convex toward the upstream side of the air flow generated by the blade 71 in all radial cross sections around the rotation axis of the axial fan 70. In the form of a plate having a depth of about 6% of the length of the cross-section of the blade 71 and being bent in a substantially arc shape, and at equal intervals around the rotation axis by the hub 72, and It is configured to be held at a predetermined angle with respect to a plane orthogonal to the rotation axis, and the air flow is generated by rotating the blades 71 by the electric motor 89.

  In particular, the axial fan 70 includes a radius of the connecting portion 100 between the blade 71 and the hub 72, a radius of the connecting portion 100 between the blade 71 and the hub 72, and a projection of the axial fan 70 in the direction of the rotation axis. An intermediate radius between the outer peripheral portion of the axial fan 70 and the connecting portion 100 is changed from the outer peripheral portion of the axial fan 70 to the inner peripheral region 73 that is in the range of the radius of the outer peripheral portion of the axial fan 70. Between the front end point 79 located on the foremost edge 76 on the rearward ridge 76 in the rotational direction of the blade 71, the radius of the connecting portion 100 between the blade 71 and the hub 72, and the radius of the outer peripheral portion of the axial fan 70. The auxiliary blades 74 extend toward the rear in the rotational direction from the reference trailing edge line 80 connecting the intermediate point 78 on the rear ridge line in the rotational direction at the radius of. When the axial fan 70 is used for transporting air from the inside of the outdoor unit 12 to the outside air by increasing the area of the blade 71 by the auxiliary blades 74 and increasing the pressure rise by the axial fan 70, the outside air 12 Configuration that reduces backflow toward the inside of the outdoor unit 12 or reduces backflow from the inside of the outdoor unit 12 to the outside air when the axial fan 70 is used to transfer air from the outside air to the inside of the outdoor unit 12 I have to.

  In FIG. 3, the auxiliary vane 74 has a vane gap 75, which is a gap with a vane behind the rotational direction of the axial fan 70, having a substantially constant width and 5% of the circumference at the minimum radius of the inner circumferential region 73. It is as follows.

In FIG. 4, the auxiliary blade 74 includes an end point 77 in the rotational direction at the maximum radius of the auxiliary blade 74, an intermediate point 78 on a ridge line 76 in the rearward direction of the blade 71 in the maximum radius of the inner peripheral region 73, and Are expanded by connecting them in a straight line, and the corners and corners formed thereby are rounded so that the curved surface of the blade 71 changes smoothly.

  The operation and action of the refrigeration cycle apparatus 10 and the axial fan 70 configured as described above will be described below.

  First, when the refrigeration cycle apparatus 10 performs the operation of radiating heat with the outdoor heat exchanger 31 and absorbing heat with the indoor heat exchanger 32, in the main circuit 11, the refrigerant sealed in the main circuit 11 is in a low-temperature and low-pressure gas phase state. Is sucked into the compressor 20 and compressed by the compressor 20 into a high-temperature and high-pressure gas phase. The direction of flow of the refrigerant is selected by the four-way valve 40 and flows to the outdoor heat exchanger 31, and heat is radiated by the outdoor heat exchanger 31 to be in a liquid phase state of intermediate temperature and intermediate pressure. After the refrigerant is stored in the refrigerant storage tank 53, the amount of refrigerant flowing is adjusted and discharged by the indoor expansion valve 52. The refrigerant absorbs heat from the outside air and evaporates in the indoor heat exchanger 32, and enters a low-temperature and low-pressure gas phase state. The compressor 20 is compressed again by the compressor 20 into a high-temperature and high-pressure gas phase. With this series of operations, the indoor heat is moved to the outside through the refrigerant, and thus the cooling operation in the air conditioner is performed.

  Further, when the refrigeration cycle apparatus 10 performs an operation of absorbing heat in the outdoor heat exchanger 31 and dissipating heat in the indoor heat exchanger 32, in the main circuit 11, the refrigerant sealed in the main circuit 11 is a low-temperature and low-pressure gas phase. In this state, the air is sucked into the compressor 20 and compressed by the compressor 20 into a high-temperature and high-pressure gas phase. The direction of the flow of the refrigerant is selected by the four-way valve 40 and flows to the indoor heat exchanger 32, and the heat is radiated by the indoor heat exchanger 32 to become a liquid-phase refrigerant of medium temperature and medium pressure. After the refrigerant is stored in the refrigerant storage tank 53, the amount of refrigerant flowing is adjusted and discharged by the outdoor expansion valve 51, and is radiated and evaporated to the outside air in the outdoor heat exchanger 31, resulting in a low-temperature and low-pressure gas phase state. The compressor 20 is compressed again by the compressor 20 into a high-temperature and high-pressure gas phase. By this series of operations, the outdoor heat is moved into the room through the refrigerant, so that the heating operation in the air conditioner is performed.

  In addition, when heat is radiated or absorbed by the outdoor heat exchanger 31, the axial flow fan 70 is used in combination to improve the efficiency of the outdoor unit 12. That is, when the axial flow fan 70 is not used together, the outdoor heat exchanger 31 dissipates heat by a natural air flow in which hot air moves vertically upward or cold air moves vertically downward, so that the outdoor unit 12 has little air replacement. In contrast, when the axial fan 70 is used together, the outdoor heat exchanger 31 radiates heat by the air flow generated by the axial fan 70, so the air is often replaced and the efficiency of the outdoor unit 12 is improved. can do.

  In particular, when the outdoor unit 12 is downsized, the cross-sectional area of the outdoor heat exchanger 31 is also reduced. Therefore, the thickness of the outdoor heat exchanger 31 is increased, the degree of integration of aluminum fins is increased, and the like. Although the efficiency of the outdoor unit 12 is maintained, the ventilation resistance of the outdoor heat exchanger 31 increases due to the influence, and the pressure difference between the air upstream and downstream of the axial fan 70 increases, and the rotational peripheral speed increases. Since the pressure hardly rises on the inner peripheral side of the small axial fan 70, the air flows backward and vortexes to increase the blowing noise. Therefore, the auxiliary blade 74 reduces the backward flow, thereby reducing the blowing noise. ing.

As described above, in the present embodiment, in the projection view in the direction of the rotation axis of the axial fan 70, the radius of the connecting portion 100 between the blade 71 and the hub 72 and the connecting portion between the blade 71 and the hub 72 are shown. The outer peripheral portion of the axial fan 70 and the connecting portion 100 are moved from the outer peripheral portion of the axial fan 70 to the inner peripheral region 73 that is an intermediate radius between the radius of 100 and the radius of the outer peripheral portion of the axial fan 70. The front end point 79 located at the foremost position on the rearward ridge line 76 in the rotation direction of the blades 71 in the range up to the middle radius of the blade 71, the radius of the connecting portion 100 between the blades 71 and the hub 72 and the outer periphery of the axial fan The auxiliary blades 74 are provided to extend rearward in the rotational direction from the reference rear edge line 80 connecting the intermediate point 78 on the ridge line 76 in the rotational direction at the intermediate radius of the part radius. Thereby, since the area of the blade | wing 71 increases in the inner peripheral side of the axial flow fan 70, the pressure rise by the axial flow fan 70 can be increased. For this reason, when it is used for the conveyance of the air from the inside of the outdoor unit 12 to the outside air, it is possible to reduce the air that flows backward from the outside air toward the inside of the outdoor unit 12, or the axial fan 70 is connected to the outdoor unit 12 from the outside air. When used for conveying air to the inside, it is possible to reduce the air flowing backward from the inside of the outdoor unit 12 toward the outside air. By reducing the backflow of air, the vortex that is the cause of the blowing noise can be weakened, so that the blowing noise can be reduced.

  In addition, as a first derivative form of the present embodiment, the environment used in a home air conditioner or a store air conditioner (the rotational speed of the axial fan 70, a predetermined air flow, the differential pressure upstream and downstream of the axial fan 70) ), When the axial fan 70 is projected in the direction of the rotational axis, the gap 75 between the blades is made substantially constant, and the width of each of the blade gaps 75 equal to the number of the blades 71 is By configuring the auxiliary blade 74 so as to be 5% or less of the circumference at the minimum radius of the peripheral region 73, the circumference of the circumference at the minimum radius of the inner peripheral region 73 is determined from the ridge line 76 in the rearward direction of the blade 71. While the reverse flow is about 10% backward, it can be reduced by damming the reverse flow with the auxiliary blades 74, the vortex causing the blowing noise can be weakened, and the blowing noise can be further reduced. .

  Further, as a second derivation form of the present embodiment, the rear ridge line 76 in the rotational direction of the blade 71 is defined by the rear end point 77 in the rotational direction at the maximum radius of the auxiliary blade 74 and the maximum radius of the inner peripheral region 73. Also, the intermediate blade 78 on the ridge line 76 in the rotation direction of the blade 71 on the inner peripheral side is connected in a straight line, and the corners and the corners are rounded to form the auxiliary blade. When 74 is configured with the same radius, there is no auxiliary blade 74 on the end face on the outer peripheral side of the auxiliary blade 74 because the blade shape is substantially arcuate in the circumferential direction but not in the radial direction. Although it is weaker than the reverse flow of the air flow, the leakage flow in the outer circumferential direction occurs, but the blade shape is also formed in the radial direction, so that the leakage flow can be suppressed, and the curved surface of the blade 71 is not formed by connecting it in a straight line. Continuous The air can be easily peeled off from the blades 71, while the curved surface can be kept continuous to suppress the air peeling, thereby reducing the vortex that causes the blowing noise generated around the auxiliary blades 74. Noise can be further reduced.

  The refrigeration cycle apparatus 10 may have the following configuration with respect to the first embodiment.

  The compression type of the compressor 20 may be a rotary type, a scroll type, a reciprocating type, or a turbo type. The power of the compressor 20 may be an electric motor provided in the compressor 20, an electric motor independent of the compressor may be used as power, or a motor instead of the motor may be used as power. As long as it is a mechanism capable of compressing a gas-phase refrigerant, its type and power are not limited.

  The indoor unit 13 may be a chiller module that adjusts the temperature of water instead of adjusting the temperature of indoor air, and is integrated into a chemical fractionation facility or the like without taking the form of a single casing. It may be. As long as the heat exchange from the main circuit 11 to the outside is possible, the target and form of temperature adjustment are not limited.

  The indoor heat exchanger 32 may be a heat exchanger in which flat tubes are arranged, or a heat exchanger in which cylindrical tubes having different diameters are arranged coaxially, and the tubes are arranged inside the container. It may be a heat exchanger. Any form is possible as long as heat can be exchanged from the main circuit 11 to the outside.

The outdoor heat exchanger 31 may be a heat exchanger in which flat tubes are arranged. Any format can be used as long as heat exchange can be promoted by passing the air flow generated by the axial fan 70.

  In addition, the refrigerant | coolant enclosed with the main circuit 11 may be CO2 etc. which do not accompany a phase change, and the kind of refrigerant | coolant is not ask | required.

  As described above, the axial fan according to the present invention can reduce the blowing noise by reducing the backflow even when the ventilation resistance is increased. In addition to the device, the present invention can also be applied to applications such as a ventilation device, a spray device, an intake device of a combustor such as a fan heater, and an airflow circulation device such as a biobench.

DESCRIPTION OF SYMBOLS 1 Axial fan 2 Hub 3 Blade | blade 4 Outer peripheral area 5 Outer peripheral area trailing edge 10 Refrigeration cycle apparatus 11 Main circuit 12 Outdoor unit 13 Indoor unit 20 Compressor 31 Outdoor heat exchanger 32 Indoor heat exchanger 40 Four-way valve 41 First path 42 Second path 43 Third path 44 Fourth path 51 Outdoor expansion valve 52 Indoor expansion valve 53 Refrigerant storage tank 61 Outdoor blower 62 Indoor blower 70 Axial fan 71 Blade 72 Hub 73 Inner peripheral region 74 Auxiliary blade 75 Blade clearance 76 Ridge line 77 End point 78 Intermediate point 79 Front end point 80 Reference trailing edge line 81 Edge line 88 Bell mouth 89 Electric motor 91-98 Flow path 100 Connection part

Claims (1)

A plurality of blades, a hub, and a connecting portion between the blades and the hub, wherein the blades are equidistant around the rotation axis by the hub and are perpendicular to the rotation axis. It is configured to be held at a predetermined angle, and an axial fan that generates an air flow by rotating the blades,
In the projection view in the direction of the rotation axis of the axial fan,
Between the radius of the connecting portion and a radius intermediate between the radius of the connecting portion and the radius of the outer peripheral portion of the axial fan,
A point located at the forefront on the rear ridge line in the rotational direction of the blades in the range from the outer peripheral part of the axial fan to an intermediate radius between the outer peripheral part of the axial fan and the connection part;
Auxiliary blades extending rearward in the rotational direction rather than a straight line connecting a point on the rear ridge line in the rotational direction at a radius intermediate between the radius of the connecting portion and the radius of the outer peripheral portion of the axial fan An axial fan characterized by comprising.