Patent Description:
An outdoor unit of an air conditioner has a propeller fan inside. The wind speed of the propeller fan is high at the outer peripheral portion of the blade, and the wind speed decreases toward the rotation center. In recent years, in order to improve the energy-saving performance of an air conditioner, the air volume of a propeller fan has been increased, the diameter of the propeller fan has been increased, and the speed of the propeller fan has been increased.

<CIT> discloses a propeller fan comprising: a hub having a side surface around a central axis; and a plurality of blades provided to the side surface, wherein the blade has, in a portion from a base connected to the hub to an outer periphery, an inner peripheral portion positioned on the base side and an outer peripheral portion positioned on the outer peripheral side, and has a plurality of blade elements branching on a way from the outer peripheral portion to the inner peripheral portion, the plurality of blade elements have a trailing edge on a downstream side of rotation with the central axis as a rotation center, and a leading edge on an upstream side of the rotation, are connected to the side surface at a pitch angle with respect to the central axis, and form a hole which is a flow path for airflow, between the adjacent blade elements, the plurality of blade elements have a first blade element on the upstream side of the rotation and a second blade element on the downstream side of the rotation to be adjacent to the first blade element which branch at a branch point on the way from the outer peripheral portion to the inner peripheral portion.

However, the above-described related art has the following problem. That is, the distribution of the wind speed in a radial direction becomes non-uniform, and a surging phenomenon such as suction of air from the downstream side occurs in the inner peripheral portion of the blade, resulting in an abnormal operation state. In a case where a propeller fan is used for an outdoor unit, if a surging phenomenon occurs, noise or damage to the propeller fan may occur. In addition, since the inner peripheral portion where the wind speed is low does not contribute to the air blowing, the amount of air blowing is small for the size, and the airflow is easily disturbed, so that it can be said that the blade surface is not effectively used.

The present invention has been made in view of the above problems, and an object of the invention is to provide a propeller fan which can increase the air volume of the propeller fan while suppressing the occurrence of a surging phenomenon.

This object is achieved by a propeller fan having the features of claim <NUM>. Advantageous further developments are defined in the dependent claims.

According to the present invention, for example, it is possible to increase the air volume of a propeller fan while suppressing the occurrence of a surging phenomenon.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The embodiments disclosed below do not limit the technology disclosed in the present application. In addition, the embodiments and modifications described below may be appropriately combined and implemented as long as they fall within the scope of the invention which is defined by the appended claims. Note that the same or similar elements will be denoted by the same reference numerals and description thereof will be omitted below.

<FIG> is a schematic diagram illustrating an outdoor unit having a propeller fan according to a first embodiment. As illustrated in <FIG>, an outdoor unit <NUM> of the first embodiment is an outdoor unit of an air conditioner. The outdoor unit <NUM> has a housing <NUM>, and accommodates a compressor <NUM> that compresses a refrigerant, a heat exchanger <NUM> which is connected to the compressor <NUM> and through which the refrigerant flows, and a propeller fan <NUM> that blows air to the heat exchanger <NUM>, in the housing <NUM>.

The housing <NUM> has an inlet <NUM> for taking in outside air and an outlet <NUM> for discharging air inside the housing <NUM>. The inlet <NUM> is provided on a side surface 6a and a rear surface 6c of the housing <NUM>. The outlet <NUM> is provided on a front surface 6b of the housing <NUM>. The heat exchanger <NUM> is disposed from the rear surface 6c facing the front surface 6b of the housing <NUM> to the side surface 6a. The propeller fan <NUM> is disposed to face the outlet <NUM>, and is driven to rotate by a fan motor (not illustrated). In the following description, the direction of the wind discharged from the outlet <NUM> by the rotation of the propeller fan <NUM> is defined as a positive pressure side, and the direction of the wind opposite thereto is defined as a negative pressure side.

<FIG> is a schematic plan view of the propeller fan according to the first embodiment as viewed from the positive pressure side. <FIG> is a plan view of one of blades of the propeller fan according to the first embodiment as viewed from the positive pressure side. <FIG> is a schematic plan view of the propeller fan according to the first embodiment as viewed from the negative pressure side. <FIG> is a plan view of one of the blades of the propeller fan according to the first embodiment as viewed from the negative pressure side. <FIG> is a perspective view of the propeller fan according to the first embodiment. <FIG> is a side view illustrating the propeller fan according to the first embodiment. <FIG> is a side view illustrating one of the blades of the propeller fan according to the first embodiment.

As illustrated in <FIG>, the propeller fan <NUM> according to the first embodiment includes a hub <NUM> formed in a cylindrical shape (or a polygonal pillar shape) in appearance, and a plurality of blades <NUM> provided on a side surface 11a (refer to <FIG> and <FIG>) of the hub <NUM>, the side surface 11a being provided around a central axis of the hub <NUM>. The hub <NUM> and the plurality of blades <NUM> are integrally formed using, for example, a resin material as a molding material. The blade <NUM> has a leading edge <NUM>-<NUM> that is a front side of the blade <NUM> in a rotational direction, and a trailing edge <NUM>-<NUM> that is a rear side of the blade <NUM> in the rotational direction. The leading edge <NUM>-<NUM> is formed to be curved so as to be concave toward the trailing edge <NUM>-<NUM> positioned on the opposite side of the leading edge <NUM>-<NUM>. The blade is also called a wing.

The hub <NUM> has a boss (not illustrated) into which a shaft (not illustrated) of a fan motor is fitted, at a position of a central axis O of the hub <NUM> at the end of the propeller fan <NUM> on the negative pressure side (refer to <FIG> and <FIG>). The hub <NUM> is rotated in a direction of "R" illustrated in <FIG>, <FIG>, and <FIG>, around the central axis O of the hub <NUM> with the rotation of the fan motor. The plurality of (five in the example of <FIG>) blades <NUM> are integrally formed on the side surface 11a of the hub <NUM> at predetermined intervals along a circumferential direction of the hub <NUM>. The blade <NUM> is formed in a curved plate shape.

In the plan view illustrated in <FIG> and <FIG>, the propeller fan <NUM> has an inner peripheral portion 12a of the blade <NUM> which is positioned within the circumference of a circle having a radius r1 from the central axis O, and an outer peripheral portion 12b of the blade <NUM> which is positioned outside the circle having the radius r1 from the central axis O and within the circle having a radius R1 from the central axis O. As illustrated in <FIG> and <FIG>, the outer peripheral portion 12b extending in the radial direction of the hub <NUM> has a larger blade area than the inner peripheral portion 12a connected to the hub <NUM>.

In the plan view illustrated in <FIG> and <FIG>, the propeller fan <NUM> has blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> on the inner peripheral portion 12a of each of the blades <NUM>. The blade element <NUM>-<NUM> is an example of a first blade element, and the blade element <NUM>-<NUM> is an example of a second blade element.

The size relationship of the blade areas of the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> can be appropriately changed in design, and the blade area of the blade element <NUM>-<NUM> may be the largest as compared with the blade areas of the blade elements <NUM>-<NUM> and <NUM>-<NUM>.

In the plan view illustrated in <FIG> and <FIG>, the propeller fan <NUM> has a hole <NUM>-<NUM> between the blade elements <NUM>-<NUM> and <NUM>-<NUM> of the inner peripheral portion 12a of each of the blades <NUM>, and a hole <NUM>-<NUM> between the blade elements <NUM>-<NUM> and <NUM>-<NUM> of the inner peripheral portion 12a of each of the blades <NUM>. The hole <NUM>-<NUM> is provided to be in contact with the boundary between the inner peripheral portion 12a and the outer peripheral portion 12b (position at the radius r1 from the central axis O). The holes <NUM>-<NUM> and <NUM>-<NUM> are flow paths for the airflow.

That is, each of the blades <NUM> is connected to the hub <NUM> such that a base <NUM>-11a of the blade element <NUM>-<NUM> and a base <NUM>-12a of the blade element <NUM>-<NUM> form the hole <NUM>-<NUM> in the inner peripheral portion 12a. Further, each of the blades <NUM> is connected to the hub <NUM> such that the base <NUM>-12a of the blade element <NUM>-<NUM> and a base <NUM>-13a of the blade element <NUM>-<NUM> form the hole <NUM>-<NUM> in the inner peripheral portion 12a. In each of the blades <NUM>, the outer peripheral portion 12b is continuous with the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>, and the inner peripheral portion 12a and the outer peripheral portion 12b form one blade surface.

In other words, the three blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> branch on the way from the outer peripheral portion 12b to the inner peripheral portion 12a of the blade <NUM>. The hole <NUM>-<NUM> between the blade elements <NUM>-<NUM> and <NUM>-<NUM> and the hole <NUM>-<NUM> between the blade elements <NUM>-<NUM> and <NUM>-<NUM> serve as flow paths for the airflow passing through the propeller fan <NUM>, respectively.

As illustrated in <FIG>, the blade element <NUM>-<NUM> of the blade <NUM> is connected to the hub <NUM> with the base <NUM>-11a as a connection part. The blade element <NUM>-<NUM> of the blade <NUM> is connected to the hub <NUM> with the base <NUM>-12a as a connection part. The blade element <NUM>-<NUM> of the blade <NUM> is connected to the hub <NUM> with the base <NUM>-13a as a connection part.

In addition, in the blade <NUM> the blade element <NUM>-<NUM> positioned on the downstream side (trailing edge side) of the airflow is connected to the hub <NUM> on the positive pressure side with respect to the blade element <NUM>-<NUM> positioned on the upstream side (leading edge side). The hole <NUM>-<NUM> of the blade <NUM> is positioned between the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM> in the central axis O direction and the circumferential direction.

In addition, in the blade <NUM> the blade element <NUM>-<NUM> positioned on the downstream side (trailing edge side) of the airflow is connected to the hub <NUM> on the positive pressure side with respect to the blade element <NUM>-<NUM> positioned on the upstream side (leading edge side). The hole <NUM>-<NUM> of the blade <NUM> is positioned between the blade elements <NUM>-<NUM> and <NUM>-<NUM> in the central axis O direction and the circumferential direction.

The number of blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> of the blade <NUM> and the number of holes <NUM>-<NUM> and <NUM>-<NUM> of the blade <NUM> in the first embodiment are not limited to those illustrated in <FIG>. One hole may be provided for two blade elements, or holes of which the number is (the number of blade elements - <NUM>) may be provided for four or more blade elements.

Further, as illustrated in <FIG>, the blade element <NUM>-<NUM> has a leading edge <NUM>-<NUM>-<NUM> on the upstream side (leading edge side) in the rotational direction ("R" direction in the drawing), and a trailing edge <NUM>-<NUM>-<NUM> on the downstream side (trailing edge side) in the rotational direction ("R" direction in the drawing). The blade element <NUM>-<NUM> has a leading edge <NUM>-<NUM>-<NUM> on the upstream side (leading edge side) in the rotational direction ("R" direction in the drawing), and a trailing edge <NUM>-<NUM>-<NUM> on the downstream side (trailing edge side) in the rotational direction ("R" direction in the drawing). The blade element <NUM>-<NUM> has a leading edge <NUM>-<NUM>-<NUM> on the upstream side (leading edge side) in the rotational direction ("R" direction in the drawing), and a trailing edge <NUM>-<NUM>-<NUM> on the downstream side (trailing edge side) in the rotational direction ("R" direction in the drawing).

According to the invention, as illustrated in <FIG>, in the blade <NUM>, the blade element <NUM>-<NUM> has a base portion <NUM>-11A and an extension portion <NUM>-11B which are defined by a boundary C1. The boundary C1 has a positional relationship substantially parallel to the leading edge <NUM>-<NUM>-<NUM> of the blade element <NUM>-<NUM>. As illustrated in <FIG>, the boundary C1 has one end corresponding to a branch point 12p of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM> which branch on the way from the outer peripheral portion 12b to the inner peripheral portion 12a of the blade <NUM>, and the other end corresponding to an end point of the base <NUM>-11a on the positive pressure side.

As illustrated in <FIG>, the extension portion <NUM>-11B is a portion further extending from the base portion <NUM>-11A of the blade element <NUM>-<NUM> toward the hole <NUM>-<NUM> present between the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>, to the downstream side of the airflow. In the side view illustrated in <FIG>, the extension portion <NUM>-11B has a triangular or convex shape having the boundary C1 as the base and both ends of the boundary C1 as vertices of base angles.

In the side view illustrated in <FIG>, the extension portion <NUM>-11B has a triangular or convex shape. From this, a part of the hole <NUM>-<NUM> is shielded from the airflow along the blade element <NUM>-<NUM> near the branch point 12p of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>. The remaining unshielded part of the hole <NUM>-<NUM> is exposed to the airflow along the blade element <NUM>-<NUM> near the side surface 11a of the hub <NUM>.

In other words, the extension portion <NUM>-11B has a portion which overlaps with the blade element <NUM>-<NUM> in the rotational direction ("R" direction in the drawing), in the vicinity of the branch point 12p of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>, and a portion which does not overlap with the blade element <NUM>-<NUM> in the rotational direction ("R" direction in the drawing), in the vicinity of the base <NUM>-11a of the blade element <NUM>-<NUM>. The blade element <NUM>-<NUM> has the extension portion <NUM>-11B that overlaps with the blade element <NUM>-<NUM> in the rotational direction ("R" direction in the drawing) at least in the vicinity of the branch point 12p of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>.

That is, the extension portion <NUM>-11B has a shape in which the height of the extension portion <NUM>-11B from the boundary C1 in the positive pressure side of the hub <NUM> gradually increases from the one end of the boundary C1 in the vicinity of the branch point 12p of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>, and the height thereof from the boundary C1 in the positive pressure side of the hub <NUM> decreases after a point where the extension portion <NUM>-11B becomes highest from the boundary C1 in the positive pressure side of the hub <NUM> to reach the other end of the boundary C1.

The extension portion <NUM>-11B has a shape in which the height of the extension portion <NUM>-11B from the boundary C1 in the positive pressure side of the hub <NUM> gradually increases, in the vicinity of the branch point 12p of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>. In other words, the extension portion <NUM>-11B has a portion having a shape that allows the airflow flowing along the blade surfaces of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM> to escape to the hole <NUM>-<NUM>, at the branch point 12p of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>. Therefore, since the outer end of the extension portion <NUM>-11B is positioned at the branch point 12p, during the operation of the air conditioner with a high load or at a high speed, the airflow flowing from the hole <NUM>-<NUM> along the blade surface of the blade element <NUM>-<NUM> (airflow inclined in the radial direction due to the influence of centrifugal force in particular) is less likely to become a ventilation resistance, and part of this airflow escapes to the hole <NUM>-<NUM> so that the load on the outer peripheral blade surface of the blade element <NUM>-<NUM> is reduced and an increase in input power supplied to the fan motor (not illustrated) to drive the propeller fan <NUM> can be suppressed.

In addition, since the airflow along the blade element <NUM>-<NUM> moves in the outer circumferential direction due to centrifugal force by the rotation of the propeller fan <NUM>, even if the extension portion <NUM>-11B only overlaps with the blade element <NUM>-<NUM> in the rotational direction ("R" direction in the drawing) at least in the vicinity of the branch portion of the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>, the number of blades on the inner peripheral side is increased to increase the wind speed of the inner peripheral portion, and thus it is possible to suppress the occurrence of an abnormal operation state such as a turbulence in airflow or a surging phenomenon caused by the difference in wind speed between the outer peripheral portion and the inner peripheral portion, and to increase the air volume. This becomes more remarkable in a case where the blade element <NUM>-<NUM> has the same extension portion as the extension portion <NUM>-11B. That is, since the airflow along the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> moves in the outer circumferential direction due to centrifugal force by the rotation of the propeller fan <NUM>, it is possible to expect an increase in air volume by providing the extension portion in the outer circumferential direction of at least the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>.

Further, a positional relationship between the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM> which are adjacent to each other will be described with reference to <FIG> is a cross-sectional view illustrating an outline of the I-I cross section of the propeller fan according to the first embodiment. Here, the I-I cross section is a cross section when the blade <NUM> of the propeller fan <NUM> is cut along a cutting line I-I in the plan view of the propeller fan <NUM> in <FIG> and viewed from the outer peripheral portion 12b side.

The blade <NUM> has the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM>. The blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> partially overlap with one another when viewed in the rotational direction ("R" direction in the drawing) in order of the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> from the upstream side (leading edge side) in the rotational direction ("R" direction in the drawing).

Specifically, as illustrated in <FIG>, the blade <NUM> has the extension portion <NUM>-11B, which partially overlaps with the leading edge <NUM>-<NUM>-<NUM> of the blade element <NUM>-<NUM> when viewed in the rotational direction ("R" direction in the drawing), on the trailing edge <NUM>-<NUM>-<NUM> side of the blade element <NUM>-<NUM>. The portion of the extension portion <NUM>-11B partially overlapping with the leading edge <NUM>-<NUM>-<NUM> of the blade element <NUM>-<NUM> when viewed in the rotational direction ("R" direction in the drawing) has the highest height of H1 from the boundary C1 in the positive pressure direction in the axial direction of the hub <NUM>.

Pitch angles α, β, and γ of the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> with respect to the central axis O of the hub <NUM> can be appropriately changed in design, and the pitch angle α of the blade element <NUM>-<NUM> may be the largest as compared with the pitch angles β and γ of the blade elements <NUM>-<NUM> and <NUM>-<NUM>.

Further, as can be seen from <FIG>, in the blade <NUM>, the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> do not overlap in the direction of the central axis O on the side surface 11a of the hub <NUM>. The blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> are connected to the position of the side surface 11a of the hub <NUM> so as not to overlap in the direction of the central axis O on the side surface 11a of the hub <NUM>.

In the blade <NUM>, the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> may overlap in the direction of the central axis O of the hub <NUM>. That is, the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> may be connected to the side surface 11a of the hub <NUM> such that the bases <NUM>-11a, <NUM>-12a, and <NUM>-13a are aligned substantially on a straight line on the side surface 11a of the hub <NUM>.

As illustrated in <FIG>, the extension portion <NUM>-11B partially overlaps the blade element <NUM>-<NUM> in the rotational direction ("R" direction in the drawing). In other words, a part of the leading edge <NUM>-<NUM>-<NUM> of the blade element <NUM>-<NUM> overlaps with a rotation orbit of the extension portion <NUM>-11B with the hub <NUM> as the rotation center. That is, the extension portion <NUM>-11B overlaps a part of the leading edge <NUM>-<NUM>-<NUM> of the blade element <NUM>-<NUM> along an airflow A2 flowing from the upstream side to the downstream side in the rotational direction ("R" direction in the drawing) with the rotation of the blade <NUM>. From this, both the airflows A1 and A2 flowing from the upstream side to the downstream side in the rotational direction ("R" direction in the drawing) with the rotation of the blade <NUM> flow along the blade surfaces from the upstream side to the downstream side of the blade surfaces of the blade elements <NUM>-<NUM> and <NUM>-<NUM>. That is, since the airflow A2 having flowed along the blade surface of the blade element <NUM>-<NUM> continues to flow along the blade surface of the blade element <NUM>-<NUM> without flowing into the hole <NUM>-<NUM> present between the blade element <NUM>-<NUM> and the blade element <NUM>-<NUM>, there is no loss of air volume.

Further, the blade elements <NUM>-<NUM> and <NUM>-<NUM> are arranged to overlap with the rotation orbits of the blade elements <NUM>-<NUM> and <NUM>-<NUM> with the hub <NUM> as the rotation center. By arranging the blade elements <NUM>-<NUM> and <NUM>-<NUM> to overlap with the rotation orbits of the blade elements <NUM>-<NUM> and <NUM>-<NUM> with the hub <NUM> as the rotation center, the airflow flowing along the position of the blade surface separated from the extension portion <NUM>-11B can be affected by the next blade elements <NUM>-<NUM> and <NUM>-<NUM>.

<FIG> is a cross-sectional view for comparing a propeller fan according to a comparative example with the propeller fan according to the first embodiment in the I-I cross section. <FIG> is a cross-sectional view of a blade 12Z of a propeller fan according to the comparative example when viewed along the same I-I cross section (not illustrated) as the I-I cross section of the propeller fan <NUM> according to the first embodiment in <FIG>.

The blade 12Z has blade elements 12Z-<NUM>, 12Z-<NUM>, and 12Z-<NUM>. The blade elements 12Z-<NUM>, 12Z-<NUM>, and 12Z-<NUM> do not overlap with one another when viewed in the rotational direction ("R" direction in the drawing) in order of the blade elements 12Z-<NUM>, 12Z-<NUM>, and 12Z-<NUM> from the upstream side (leading edge side) in the rotational direction ("R" direction in the drawing).

Specifically, as illustrated in <FIG>, the blade 12Z does not have a portion partially overlapping with a leading edge 12Z-<NUM>-<NUM> of the blade element 12Z-<NUM> in the rotational direction ("R" direction in the drawing), on a trailing edge 12Z-<NUM>-<NUM> side of the blade element 12Z-<NUM>. The interval between the trailing edge 12Z-<NUM>-<NUM> of the blade element 12Z-<NUM> and the leading edge 12Z-<NUM>-<NUM> of the blade element 12Z-<NUM> is H01 at the widest part in the axial direction of the hub <NUM>.

For this reason, in the blade 12Z of the propeller fan according to the comparative example, since an airflow A02 is sandwiched between the blade elements 12Z-<NUM> and 12Z-<NUM>, an airflow A01 flowing from the upstream side to the downstream side in the rotational direction ("R" direction in the drawing) with the rotation of the blade 12Z flows along the blade surfaces on the downstream side of the blade elements 12Z-<NUM> and 12Z-<NUM>. However, since the airflow A02 flowing from the upstream side to the downstream side in the rotational direction ("R" direction in the drawing) with the rotation of the blade 12Z directly follows the blade surfaces of the blade elements 12Z-<NUM> and 12Z-<NUM>, the airflow A02 flows into a hole 12Z-<NUM> present between the blade element 12Z-<NUM> and the blade element 12Z-<NUM> without flowing along the blade surface of the blade element 12Z-<NUM> after flowing along the blade surface on the downstream side of the blade element 12Z-<NUM>. For this reason, the airflow A02 flowing into the hole 12Z-<NUM> present between the blade element 12Z-<NUM> and the blade element 12Z-<NUM> becomes a loss of air volume as compared with the first embodiment.

The change in static pressure of the propeller fan between the first embodiment and the comparative example will be described with reference to <FIG>. <FIG> is an air volume-input (input power) curve diagram. <FIG> is an air volume-rotation speed curve diagram. <FIG> is an air volume-static pressure curve diagram. <FIG> illustrate preconditions for comparing the static pressure of the propeller fan between the first embodiment and the comparative example.

<FIG> illustrates that the input (input power) is W1 [W] when the air volume of the propeller fan is Q01 [m<NUM>/h] and the input (input power) is W2 [W] when the air volume of the propeller fan is Q02 [m<NUM>/h]. <FIG> illustrates that the rotation speed is RF1 [rpm] when the air volume of the propeller fan is Q01 [m<NUM>/h] and the rotation speed is RF2 [rpm] when the air volume of the propeller fan is Q02 [m<NUM>/h]. That is, the first embodiment and the comparative example illustrate that the input (input power) and the rotation speed are the same if the air volume is the same.

Here, as illustrated in <FIG>, in the comparative example, the static pressure is P1 [Pa] when the air volume of the propeller fan is Q01 [m<NUM>/h], whereas in the first embodiment, the static pressure is a higher value than P1 [Pa] when the air volume of the propeller fan is Q01 [m<NUM>/h], and the static pressure is increased to be higher than P1. Further, in the comparative example, the static pressure is P2 [Pa] when the air volume of the propeller fan is Q02 [m<NUM>/h], whereas in the first embodiment, the static pressure is a higher value than P2 [Pa] when the air volume of the propeller fan is Q02 [m<NUM>/h], and the static pressure is increased to be higher than P2.

That is, if the static pressure is the same at P1 [Pa], the air volume of the propeller fan according to the comparative example is Q01 [m<NUM>/h], and the air volume of the propeller fan according to the first embodiment is Q11 [m<NUM>/h], which is increased from Q01 [m<NUM>/h] to Q11 [m<NUM>/h]. Further, if the static pressure is the same at P2 [Pa], the air volume of the propeller fan according to the comparative example is Q02 [m<NUM>/h], and the air volume of the propeller fan according to the first embodiment is Q12 [m<NUM>/h], which is increased from Q02 [m<NUM>/h] to Q12 [m<NUM>/h]. Conversely, in the first embodiment, even in a case where the static pressure is higher than in the comparative example, the same air volume as in the comparative example can be secured. That is, from <FIG>, it can be said that the air volume of the propeller fan <NUM> can be increased according to the first embodiment.

In the first embodiment described above, the blade <NUM> has a shape of branching into the blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> from the outer peripheral portion 12b to the inner peripheral portion 12a. The blade elements <NUM>-<NUM>, <NUM>-<NUM>, and <NUM>-<NUM> are connected such that the bases <NUM>-11a, <NUM>-12a, and <NUM>-13a form a row around the hub <NUM>. The blade element <NUM>-<NUM> has the extension portion <NUM>-11B having a triangular or convex shape in the vicinity of the branch point 12p of the blade elements <NUM>-<NUM> and <NUM>-<NUM> on the trailing edge <NUM>-<NUM>-<NUM> side on the downstream side of the hub <NUM> in the rotational direction.

Therefore, since the extension portion <NUM>-11B suppresses the airflow from being deflected due to the centrifugal force by the rotation of the propeller fan <NUM>, the occurrence of a surging phenomenon can be prevented. Further, by arranging the blade elements <NUM>-<NUM> and <NUM>-<NUM> to overlap with the rotation orbits of the blade elements <NUM>-<NUM> and <NUM>-<NUM> with the hub <NUM> as the rotation center, the airflow flowing along the position of the blade surface separated from the extension portion <NUM>-11B is affected by the next blade element <NUM>-<NUM>. Thereby, the force of the blade <NUM> is exerted even on the airflow that could not exert the force of the blade <NUM> in the related art, and the air volume of the propeller fan <NUM> can be increased. That is, according to the first embodiment, it is possible to increase the air volume of a propeller fan while suppressing the occurrence of a surging phenomenon.

Similarly, the blade element <NUM>-<NUM> may have the same extension portion as the extension portion <NUM>-11B, on the trailing edge <NUM>-<NUM>-<NUM>, and the blade element <NUM>-<NUM> may have the same extension portion as the extension portion <NUM>-11B, on the leading edge <NUM>-<NUM>-<NUM>.

Alternatively, the blade element <NUM>-<NUM> may have the extension portion <NUM>-11B on the trailing edge <NUM>-<NUM>-<NUM>, the blade element <NUM>-<NUM> may have the same extension portion as the extension portion <NUM>-11B, on the leading edge <NUM>-<NUM>-<NUM>, the blade element <NUM>-<NUM> may have the same extension portion as the extension portion <NUM>-11B, on the trailing edge <NUM>-<NUM>-<NUM>, and the blade element <NUM>-<NUM> may have the same extension portion as the extension portion <NUM>-11B, on the leading edge <NUM>-<NUM>-<NUM>.

<FIG> is a side view illustrating one of blades of a propeller fan according to a second embodiment. A blade element 12A-<NUM> of a blade 12A of a propeller fan 5A according to the second embodiment is connected to the hub <NUM> with a base 12A-11a as a connection part. Further, in the blade 12A, the extension portion 12A-11B of the blade element 12A-<NUM> has a substantially trapezoidal shape with the boundary C1 as the base.

The height of the extension portion 12A-11B from the boundary C1 in the positive pressure side of the hub <NUM> gradually increases from the one end of the boundary C1 in the vicinity of the branch point 12p of the blade element 12A-<NUM> and the blade element <NUM>-<NUM>, and the height thereof from the boundary C1 in the positive pressure side of the hub <NUM> is substantially constant up to the connection point with the hub <NUM> after a point where the extension portion 12A-11B becomes highest from the boundary C1 in the positive pressure side of the hub <NUM>.

That is, similarly to the extension portion <NUM>-11B of the first embodiment, the extension portion 12A-11B of the second embodiment has a shape in which the height of the extension portion 12A-11B from the boundary C1 in the positive pressure side of the hub <NUM> gradually increases, in the vicinity of the branch point 12p of the blade element 12A-<NUM> and the blade element <NUM>-<NUM>. In other words, the entire leading edge <NUM>-<NUM>-<NUM> of the blade element <NUM>-<NUM> overlaps with the rotation orbit of the extension portion 12A-11B with the hub <NUM> as the rotation center. Therefore, since the outer end of the extension portion 12A-11B is positioned at the branch point 12p, during the operation of the air conditioner with a high load or at a high speed, the airflow flowing from the hole 12A-<NUM> along the blade surface of the blade element <NUM>-<NUM> (airflow inclined in the radial direction due to the influence of centrifugal force in particular) is less likely to become a ventilation resistance, and part of this airflow escapes to the hole 12A-<NUM> through a notched portion so that the load on the outer peripheral blade surface of the blade element <NUM>-<NUM> is reduced and an increase in input power supplied to the fan motor (not illustrated) to drive the propeller fan <NUM> can be suppressed.

Claim 1:
A propeller fan (<NUM>) comprising:
a hub (<NUM>) having a side surface (11a) around a central axis (O); and
a plurality of blades (<NUM>) provided to the side surface (11a),
wherein the blade has, in a portion from a base connected to the hub (<NUM>) to an outer periphery, an inner peripheral portion positioned on the base side and an outer peripheral portion (12b) positioned on the outer peripheral side, and has a plurality of blade elements (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) branching on a way from the outer peripheral portion (12b) to the inner peripheral portion,
the plurality of blade elements (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) have a trailing edge (<NUM>-<NUM>-<NUM>) on a downstream side of rotation with the central axis (O) as a rotation center, and a leading edge (<NUM>-<NUM>-<NUM>) on an upstream side of the rotation, are connected to the side surface (11a) at a pitch angle with respect to the central axis (O), and form a hole (<NUM>-<NUM>) which is a flow path for airflow, between the adjacent blade elements (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>),
the plurality of blade elements (<NUM>-<NUM>, <NUM>-<NUM>, <NUM>-<NUM>) have a first blade element (<NUM>-<NUM>) on the upstream side of the rotation and a second blade element (<NUM>-<NUM>) on the downstream side of the rotation to be adjacent to the first blade element (<NUM>-<NUM>) which branch at a branch point (12p) on the way from the outer peripheral portion (12b) to the inner peripheral portion, and include an extension portion (<NUM>-11B) as a part of the first blade element (<NUM>-<NUM>), on the trailing edge (<NUM>-<NUM>-<NUM>) of the first blade element (<NUM>-<NUM>) from the branch point (12p) to the side surface (11a),
the extension portion (<NUM>-11B) is defined by a boundary (C1), the boundary (C1) having a positional relationship substantially parallel to the leading edge (<NUM>-<NUM>-<NUM>) of the second blade element (<NUM>-<NUM>) and the boundary (C1) having one end corresponding to the branch point (12p), and
at least a part of the leading edge (<NUM>-<NUM>-<NUM>) of the second blade element (<NUM>-<NUM>) overlaps with a rotation orbit of the extension portion (<NUM>-11B) with the central axis (O) as the rotation center.