JP2012207612A - Axial fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial fan capable of reducing concentration of stress to a connection between a rib provided in a hub section and a rotary shaft so as to remarkably improve in terms of damage by the stress.SOLUTION: A propeller fan 10, which includes the hub section 12 including the rotary shaft 11 at the center and a plurality of forwarding wings 20 provided along the circumference of the hub section 12, includes a plurality of ribs 13 extending from the rotary shaft 11 to the inner periphery of the hub section 12 wherein a direction (arrow D) where the ribs 13 extend is brought close to a direction (arrow E) of the stress applied to the ribs 13 by the rotation.

Description

  The present invention relates to an axial fan including a hub portion having a rotating shaft portion and a plurality of forward blades provided on the outer periphery of the hub portion.

  An axial fan that sucks air from the axial direction and blows it in the axial direction is adopted in an outdoor unit, a ventilation fan, a fan, and the like of the air conditioner. The axial fan includes a hub portion having a rotating shaft portion and a plurality of forward blades disposed on the outer periphery of the hub portion, and the blades have a three-dimensional curved surface shape (see, for example, Patent Document 1). ).

  For such an axial fan, the rotational speed is controlled, for example, in the range of 0 to 1000 rpm. If a partial stress is concentrated on the joint between the hub portion and the blade at the center of rotation due to high-speed rotation, the strength of the portion is weakened. Therefore, in order to improve the overall rigidity of the axial fan, ribs are formed radially from the rotating shaft portion to the inner periphery of the hub portion.

  FIG. 7 is a partially enlarged view seen from the suction surface side of an axial fan (propeller fan) 100 for explaining the stress applied to the blade and the hub. The propeller fan 100 has a hub portion 102 having a rotating shaft portion 101, and a plurality of the same-shaped forward blades 105 arranged at a predetermined interval on the outer periphery of the hub portion 102 and connected at a connection portion 103. Configured. The hub portion 102 and the forward blades 105 are integrally molded with resin, for example.

  In the hub portion 102, ribs 106 are formed radially from the rotary shaft portion 101 to the inner periphery of the hub portion 102. In this case, each rib 106 includes a rib 106A extending toward the substantial center of each wing 105 and a rib 106B extending toward the center between the ribs 106A.

  The rotation in the direction of arrow N causes air (outside air) to flow from the blade leading edge 107 side to the blade trailing edge 108 side, and the whole air is blown from the back side of the propeller fan 100 to the front side direction.

Japanese Utility Model Publication No. 5-69400

  In the forward blade 105, the blade leading edge 107 is positioned on the suction surface 110F side with respect to the blade trailing edge 108. Therefore, when the blade is rotated, a force that twists the blade leading edge 107 toward the pressure surface due to centrifugal force is generated. 108 is applied with a twisting force toward the suction surface 110F. At this time, since the ribs 106 in the hub portion 102 extend radially from the rotating shaft portion 101 over the inner periphery of the hub portion 102, each rib 106 has a rib 106 with the torsional force applied to the advancing blade 105. Stress that pulls down the rib in a direction substantially orthogonal to the extending direction is applied. Therefore, stress concentrates on the rib 106, in particular, the connecting portion 109 between the rib 106A extending toward the approximate center of each blade 105 and the rotating shaft 101 (a large stress line is indicated by T1), and breakage occurs. There is a fear.

  The present invention has been made to solve the conventional technical problems, and reduces stress concentration at the connection portion between the rib provided on the hub portion and the rotary shaft portion, thereby significantly improving breakage due to stress. It is an object of the present invention to provide an axial fan that can be used.

  In order to solve the above problems, an axial fan according to the present invention includes a hub portion having a rotation shaft portion at the center and a plurality of forward blades provided on the outer periphery of the hub portion. A plurality of ribs extending from the rotating shaft portion to the inner periphery of the hub portion are provided, and the extending direction of the ribs is made closer to the direction of stress applied to the ribs by rotation.

 An axial fan according to a second aspect of the present invention includes a hub portion having a rotation shaft portion at the center thereof, and a plurality of forward blades provided on the outer periphery of the hub portion. A plurality of ribs extending over the inner periphery of the hub portion are provided, and the angle formed by the direction of stress applied to the ribs by rotation and the extending direction of the ribs is made smaller than a right angle.

  An axial fan according to a third aspect of the present invention includes a hub portion having a rotation shaft portion at the center thereof, and a plurality of forward blades provided on the outer periphery of the hub portion, the rotation shaft portion, A plurality of ribs provided between the inner circumferences of the hub portion are provided, and the center line of the ribs passes between the center of the rotation shaft portion and the outer circumference of the center in the counter-rotation direction.

  An axial fan according to a fourth aspect of the present invention includes a hub portion having a rotation shaft portion at the center, and a plurality of forward blades provided on the outer periphery of the hub portion, and the rotation shaft portion, A plurality of ribs provided between the inner circumferences of the hub part are provided, and the connection position between the ribs and the hub part is moved in the anti-rotation direction without changing the connection position between the ribs and the hub part. And

  The invention of claim 5 is characterized in that, in each of the above inventions, the rib has an arc shape whose center is located on the rotation direction side of the rib.

  The invention of claim 6 is characterized in that, in each of the above inventions, an auxiliary rib is provided between the ribs.

  According to the present invention, the force applied in the direction in which the plurality of ribs provided between the rotating shaft portion and the inner periphery of the hub portion are pulled down by the rotation can be relaxed, and the connection between the rib and the rotating shaft portion can be achieved. Stress concentration on the part can be reduced. As a result, it is possible to avoid inconvenience that the connecting portion between the rib and the rotating shaft portion is damaged.

  In particular, according to the invention of claim 5, in each of the above inventions, the rib is formed into an arc shape whose center is located on the rotation direction side of the rib, whereby stress concentration at the connection portion between the rib and the rotation shaft portion is achieved. Can be effectively reduced.

  According to the invention of claim 6, in each of the above inventions, by providing the auxiliary rib between the ribs, the force applied in the direction in which the rib is pulled down by the rotation can be supported by the reinforcing rib, Also by this, the stress concentration on the connecting portion between the rib and the rotating shaft portion can be reduced.

It is a perspective view of the outdoor unit to which the propeller fan concerning one Embodiment of the axial fan of this invention is applied. It is the perspective view seen from the positive pressure surface side of the propeller fan. It is the top view seen from the negative pressure surface side of the propeller fan. It is the perspective view seen from the negative pressure surface side of the propeller fan. It is the top view seen from the suction side explaining the stress added to a propeller fan. It is the top view seen from the suction surface side explaining the stress added to the propeller fan as another Example. It is the top view seen from the suction surface side explaining the stress added to the conventional propeller fan.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of an outdoor unit 1 to which a propeller fan according to an embodiment of an axial fan of the present invention is applied. This outdoor unit 1 is arranged outside and is connected to an indoor unit (not shown) arranged on the ceiling or wall of the room by piping to constitute an air conditioner. The air conditioner performs a cooling operation, a heating operation, or the like by flowing a refrigerant through a refrigerant circuit including the outdoor unit 1 and the indoor unit. The outdoor unit 1 exchanges heat between the outside air and the refrigerant, condenses the refrigerant during the cooling operation and releases heat to the outside air, and evaporates the refrigerant during the heating operation to take in heat from the outside air.

  The outdoor unit 1 is provided with a compressor and a heat exchanger (not shown) in a housing 2, and in this embodiment, an air inflow portion (not shown) is formed on the side surface of the housing 2, The air discharge part (orifice) 4 is formed. And in this air discharge part 4, the propeller fan 10 as one Example of the axial fan of this invention is arrange | positioned. The propeller fan 10 is connected to a fan motor 10M located on the upstream side (therefore, the propeller fan 10 is located on the downstream side of the fan motor), and the fan motor 10M is disposed on the downstream side of the heat exchanger. By rotation driving of the propeller fan 10 by the fan motor 10M, air (outside air) is sucked into the housing 2 from the air inflow portion, reaches the heat exchanger, and heat is exchanged between the refrigerant in the heat exchanger and the outside air. The The air after the heat exchange is discharged to the outside from the air discharge unit 4 by the rotation of the propeller fan 10.

   Next, a propeller fan 10 as an example of the axial fan of the present invention will be described with reference to the drawings. 2 is a perspective view seen from the pressure side of the propeller fan 10, FIG. 3 is a plan view seen from the suction side of the propeller fan 10, and FIG. 4 is a perspective view seen from the suction side of the propeller fan 10.

  The propeller fan 10 has a hub portion 12 having a rotation shaft portion 11 at the center, and a plurality (for example, three) of the same shape arranged (provided) on the outer periphery of the hub portion 12 at a predetermined blade row pitch. And a forward wing 20. The hub portion 12 and each advance blade 20 are integrally molded with resin, for example.

  The hub portion 12 has the motor shaft 5 of the fan motor inserted through the rotating shaft portion 11 and rotates each forward blade 20 in the direction of arrow N in each figure by driving the fan motor. In this embodiment, since the propeller fan 10 is disposed in the air discharge portion 4 formed on the front surface of the housing 2, the positive pressure surface 21S side of the propeller fan 10 is the front surface, and the negative pressure surface 21F side is the housing 2 side ( It is arranged so that it may become the back.

  In addition, the hub portion 12 is configured to have a substantially cylindrical outer diameter, and a plurality of ribs 13 are integrally molded from the rotating shaft portion 11 to the inner periphery. In this embodiment, the rib 13 includes a rib 13A extending toward the substantial center of each blade 20 and ribs 13B extending toward the center between the ribs 13A. The hub portion 12 is not limited to a cylindrical shape, and may be a triangular pyramid shape or a truncated cone shape with the connecting portion of the blade 20 as a base.

  As a result, the blade 20 causes air (outside air) to flow from the blade leading edge 22 side toward the blade trailing edge 23 side by rotation in the direction of arrow N, and this air as a whole from the back side of the propeller fan 10 to the front side. Direction, in this case, air is blown from the inside of the housing 2 toward the front surface of the housing 2.

  At this time, in the present embodiment, each rib 13 is moved in the counter-rotating direction by moving the connection position 15 between the rib 13 and the rotating shaft portion 11 without changing the connection position 14 with the hub portion 12. The center line is a position that passes between the center C of the rotation shaft portion 11 and the outer periphery of the center C on the side opposite to the rotation direction.

  Thereby, the angle α formed by the direction of stress applied to the rib 13 by rotation (arrow E in FIG. 2) and the extending direction of the rib 13 (arrow D in FIG. 2) can be made smaller than a right angle. The extending direction of the rib 13 (arrow D) can be brought closer to the direction of the stress applied to the rib 13 (arrow E).

  As described in the prior art, since the blade leading edge 22 is positioned on the suction surface 21F side of the blade trailing edge 23, when the propeller fan 10 rotates, the outer end portion of the blade trailing edge 23 is caused by centrifugal force. A twisting force (arrow A in FIG. 4) is applied to the suction surface 21F side, and a twisting force (arrow B in FIG. 4) is applied to the outer end portion of the blade leading edge 22 to the positive pressure surface 21S side. This is caused by a phenomenon similar to that when the suspended pendulum is rotated about the vertical axis, the weight of the tip is raised by centrifugal force.

  Therefore, if each rib 13 in the hub portion 12 is configured to extend radially from the rotary shaft portion 11 over the inner periphery of the hub portion 12 as in the prior art, the torsional force applied to the advancing blade 20 causes The rib 13, in particular, the rib 13 </ b> A extending toward the substantial center of the wing 20 is subjected to stress that pulls down the rib 13 </ b> A in a direction substantially orthogonal to the extending direction (arrow D) of the rib 13 </ b> A. Become. However, by providing the rib 13 so that the extending direction (arrow D) of the rib 13 is brought close to the direction of stress (arrow E) applied to the rib 13 by rotation as in this embodiment, the rib 13 is pulled. The force applied in the direction of being knocked down can be relaxed.

  FIG. 5 is a partially enlarged view seen from the suction surface side of the propeller fan 10 for explaining the stress applied to the blade 20 and the hub portion 12. Comparing FIG. 5 with FIG. 7 showing the prior art, the extending direction (arrow D) of the rib 13 is brought closer to the direction of stress (arrow E) applied to the rib 13 by rotation as in this embodiment. By providing the ribs 13 in this way, the ribs 13 indicated by T1 in FIG. 6, in particular, the ribs 13 </ b> A extending toward the approximate center of each blade 20 and the connecting portion 15 between the rotary shaft portion 11 are provided. It can be seen that the concentrated stress line has disappeared (the stress in that portion has decreased).

  Thereby, the connection part of the rib 13 and the rotating shaft part 11 is provided by providing the rib 13 so that the extending direction (arrow D) of the rib 13 may be brought close to the direction of stress applied to the rib 13 by rotation (arrow E). The stress concentration to 15 can be reduced. Therefore, it is possible to avoid inconvenience that the connecting portion 15 between the rib 13 and the rotating shaft portion 11 is damaged.

  For this reason, the rib 13 can be formed by reducing the thickness of the rib 13 while maintaining the same strength as the conventional one by adopting the rib 13 as a configuration. Thereby, cost reduction can be aimed at.

  As shown in FIG. 6, each rib 13 in the above embodiment may be a rib 16 having an arc shape whose center is located on the rotational direction side of the rib. Thereby, the stress concentration to the connection part 15 of the rib 16 and the rotating shaft part 11 can be reduced further effectively.

  In each of the above embodiments, auxiliary ribs (not shown) extending between the ribs 13 or 16 may be integrally formed. By providing such an auxiliary rib, the force applied in the direction in which the rib 13 or 16 is pulled down by rotation can be supported by the reinforcing rib, and also by this, the connecting portion between the rib 13 or 16 and the rotary shaft portion 11 is supported. The stress concentration to 15 can be reduced.

1 Outdoor unit 2 Housing 4 Air discharge part (orifice)
10 Propeller fan (axial fan)
DESCRIPTION OF SYMBOLS 11 Rotating shaft part 12 Hub part 13, 13A, 13B Rib 14, 15 Connection position 16 Rib 20 Forward blade 21S Pressure surface 21F Negative pressure surface 22 Blade front edge 23 Blade trailing edge

Claims (6)

In an axial fan including a hub portion having a rotation shaft portion at the center and a plurality of forward blades provided on the outer periphery of the hub portion,
A plurality of ribs extending from the rotating shaft portion to the inner periphery of the hub portion;
An axial fan characterized in that an extending direction of the rib is made closer to a direction of stress applied to the rib by rotation. In an axial fan including a hub portion having a rotation shaft portion at the center and a plurality of forward blades provided on the outer periphery of the hub portion,
A plurality of ribs extending from the rotating shaft portion to the inner periphery of the hub portion;
An axial fan characterized in that an angle formed between a direction of stress applied to the rib by rotation and an extending direction of the rib is smaller than a right angle. In an axial fan including a hub portion having a rotation shaft portion at the center and a plurality of forward blades provided on the outer periphery of the hub portion,
A plurality of ribs provided across the inner periphery of the rotating shaft portion and the hub portion;
A centerline of the rib passes between the center of the rotating shaft portion and the outer periphery of the center on the side opposite to the rotation direction. In an axial fan including a hub portion having a rotation shaft portion at the center and a plurality of forward blades provided on the outer periphery of the hub portion,
A plurality of ribs provided across the inner periphery of the rotating shaft portion and the hub portion;
An axial fan, wherein the connecting position between the rib and the hub portion is left unchanged, and the connecting position between the rib and the rotating shaft portion is moved in the counter-rotating direction.   The axial fan according to any one of claims 1 to 4, wherein the rib has an arc shape whose center is located on a rotation direction side of the rib.   6. The axial fan according to claim 1, further comprising auxiliary ribs extending between the ribs.

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