JP6171955B2 - Axial fan - Google Patents

Description

  The present invention relates to an axial fan that forms an air flow in a rotation axis direction.

  Conventionally, as this type of axial fan, for example, there is one described in Patent Document 1. In the axial fan described in Patent Document 1, a plurality of blades are arranged around the boss portion along the rotation direction, and the outer edge portions of the blades are connected by a ring. In order to reduce noise, a plurality of serrated projections are formed along the radial direction on the front edge or the rear edge of the blade.

Japanese Patent No. 3448136

  By the way, a tensile load due to centrifugal force acts on the blade, and stress concentrates on the valley of the protrusion. More specifically, in an axial fan in which the outer edge portions of the blades are connected by a ring, a particularly large stress is generated in the valley portion of the protruding portion located on the outermost radial direction.

  And stress concentration can be avoided by making the valley part of a projection part into the curved surface of predetermined curvature radius, and the stress reduction effect is so large that the curvature radius of the valley part of a projection part is enlarged.

  However, when the curvature radius of the valley portion of the protrusion is increased, there is a problem that the stress reduction effect is large but the noise reduction effect is reduced.

  The present invention has been made in view of the above points, and an object of the present invention is to achieve both a stress reduction effect and a noise reduction effect in an axial flow fan in which the outer edges of blades are connected by a ring.

  In order to achieve the above object, in the invention described in claim 1, the boss portion (1) disposed at the center of rotation, the boss portion extends radially outward from the boss portion, and a plurality of the boss portions are disposed along the rotation direction. A blade (2), a ring (3) for connecting the outer edges of the plurality of blades, and a sawtooth-shaped protrusion (21) formed on the front edge or the rear edge of the blade and arranged in a radial direction. And the radius of curvature of the valley (211a) of the protrusion (21a) located on the outermost radial direction is larger than the radius of curvature of the valley (211b) of the protrusion (21b) located on the innermost radial direction. It is characterized by being.

  According to this, it is possible to sufficiently exert the noise reduction effect on the protrusions located on the radially inner side while reducing the stress of the valleys located on the radially outer side where a large load acts.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a front view of the axial flow fan concerning one embodiment of the present invention. It is an enlarged front view of the blade in the axial flow fan concerning one embodiment. It is a front view of the braid | blade which shows the modification of the axial fan which concerns on one Embodiment.

  An embodiment of the present invention will be described.

  As shown in FIG. 1, the axial fan of this embodiment includes a boss portion 1, a blade 2, a ring 3, and an electric motor (not shown). The boss part 1, the blade 2, and the ring 3 are integrally formed of resin.

  The boss 1 has a bottomed cylindrical shape, and an output shaft (rotary shaft) of the electric motor is fixed to the center of the bottom. That is, the boss portion 1 is disposed at the rotation center.

  A plurality of blades 2 extend radially outward from the outer peripheral surface of the cylindrical portion of the boss portion 1 and are arranged along the rotational direction R. Further, the outer edge portions of the plurality of blades 2 are connected by an annular ring 3.

  As shown in FIG. 2, a plurality of serrated projections 21 are arranged on the front edge of the blade 2 along the radial direction. In addition, the protrusion part 21a located in the radial direction outermost among the several protrusion parts 21 is hereafter called the outermost protrusion part 21a. In addition, the protrusion 21b located on the innermost radial direction among the plurality of protrusions 21 is hereinafter referred to as an innermost protrusion 21b.

  The valley 211 of the protrusion 21 is a curved surface with a predetermined radius of curvature. And the curvature radius of the trough part 211a of the outermost projection part 21a is set larger than the curvature radius of the trough part 211b of the innermost projection part 21b.

  More specifically, in this embodiment, the radius of curvature of the valley 211a of the outermost protrusion 21a is set to be larger than the radius of curvature of the valleys 211 of all other protrusions 21. Note that the valleys 211 of the protrusions 21 other than the outermost protrusion 21a may have a pin angle (that is, a radius of curvature ≈ 0).

  In the axial fan configured as described above, the boss portion 1, the blade 2, and the ring 3 are rotationally driven by an electric motor to form an air flow in the rotation axis direction.

  At this time, a particularly large tensile load acts on the trough portion 211a of the outermost projection portion 21a. However, since the curvature radius of the trough portion 211a of the outermost projection portion 21a is large, the stress on the trough portion 211a of the outermost projection portion 21a. Concentration is avoided and the stress of the valley 211a of the outermost projection 21a is reduced.

  On the other hand, since the curvature radius of the trough part 211 of the projection parts 21 other than the outermost projection part 21a is small, the noise reduction effect can be sufficiently exerted in the projection parts 21 other than the outermost projection part 21a.

  Therefore, according to the present embodiment, both the stress reduction effect and the noise reduction effect can be achieved.

  In the above embodiment, the valley 211a of the outermost protrusion 21a is curved, but the valley 211a of the outermost protrusion 21a is flat (that is, the radius of curvature) as in the modification shown in FIG. May be infinite).

(Other embodiments)
In the said embodiment, although the curvature radius of the trough part 211a of the outermost projection part 21a was made larger than the curvature radius of the trough part 211 of all the other projection parts 21, the trough part 211a of the outermost projection part 21a is included. The curvature radii of the valleys 211 of the plurality of projections 21 located on the radially outer side may be larger than the curvature radii of the valleys 211 of the projections 21 located on the radially inner side.

  Alternatively, the curvature radii of the valleys 211 of all the protrusions 21 may be made different so that the curvature radii increase in order from the innermost protrusion 21b toward the outermost protrusion 21a.

  Further, the protrusion 21 may be divided into a plurality of groups, and the radius of curvature of the valley 211 may be increased stepwise from the group located on the radially inner side to the group located on the radially outer side.

  Moreover, in the said embodiment, although the projection part 21 was arrange | positioned in the front edge of the braid | blade 2, you may arrange | position the protrusion part 21 in the rear edge of the braid | blade 2. FIG.

  In addition, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably.

  Further, in the above-described embodiment, it is needless to say that elements constituting the embodiment are not necessarily indispensable except for the case where it is clearly indicated that the element is essential and the case where the element is clearly considered to be essential in principle. .

  Further, in the above embodiment, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is particularly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to a specific number except for cases.

  In the above embodiment, when referring to the shape, positional relationship, etc. of components, the shape, position, etc., unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to relationships.

1 Boss 2 Blade 3 Ring 21 Projection 211 Valley

Claims (2)

A boss part (1) arranged at the center of rotation;
A plurality of blades (2) extending radially outward from the boss portion and arranged along the rotational direction;
A ring (3) connecting outer edges of a plurality of the blades;
A plurality of serrated protrusions (21) formed on the front edge or the rear edge of the blade and arranged in a radial direction,
The curvature radius of the valley portion (211a) of the projection (21a) located on the outermost radial direction is larger than the curvature radius of the valley portion (211b) of the projection (21b) located on the innermost radial direction. An axial fan characterized by being.   2. The axial fan according to claim 1, wherein a radius of curvature of a valley portion of the protruding portion located on the outermost radial direction is larger than a curvature radius of a valley portion of all the other protruding portions. .

Images