EP3043077A1

EP3043077A1 - Propeller fan, air-blowing device, and outdoor unit

Info

Publication number: EP3043077A1
Application number: EP14840958.4A
Authority: EP
Inventors: Takahide Tadokoro; Yasuaki Kato; Atsushi Kono
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2013-09-02
Filing date: 2014-08-27
Publication date: 2016-07-13
Anticipated expiration: 2034-08-27
Also published as: WO2015029245A1; JP6095025B2; EP3043077A4; WO2015030048A1; EP3043077B1; JPWO2015030048A1

Abstract

A propeller fan (1, 201, 301, 401) includes: a boss (3); and a plurality of blades (5) arranged on an outer periphery of the boss (3). A protruding portion (17, 217, 317, 417) is formed on a suction surface (15) of at least one of the blades (5). The protruding portion (17, 217, 317, 417) extends in a rotating direction at a position separated away from an outer peripheral edge of the blade. An inclination of a radially-inner skirt portion (17a) of the protruding portion (17, 217, 317, 417) is gentler than an inclination of a radially-outer skirt portion (17b) of the protruding portion (17, 217, 317, 417). A blowing flow is uniformized in a radial direction, thereby being capable of suppressing a locally-high velocity air stream.

Description

Technical Field

The present invention relates to a propeller fan, an air blower, and an outdoor unit.

Background Art

Nowadays, various blade shapes are proposed in order to achieve a low-noise and high-efficient air blower. Noise and loss of a fan are increased in accordance with turbulence of an air stream and the magnitude of an air velocity. Therefore, in order to attain reduction in noise and enhancement in efficiency of the fan, it is required to reduce the turbulence of the air stream to be generated around the blade and suppress generation of a locally-high air velocity portion to the extent possible.
As an existing fan, for example, in Patent Literature 1, there is disclosed a fan in which a linear projection extending substantially along an extending direction of the blade is formed on an edge portion of a suction surface of the blade on a backward side in a rotating direction to intend to avoid a situation that an air stream entering the suction surface of the blade suddenly impinges on an air stream entering a pressure surface of the blade.
In Patent Literature 2, there is disclosed a fan in which a thick portion is formed on a blade trailing edge to intend to cause the separated air stream to attach again at the thick portion.
Further, in Patent Literature 3, there is disclosed a fan curved so that a portion on an outer periphery side has a concave shape and a portion on a boss side has a convex shape with respect to a suction side of the air stream.
Further, in Patent Literature 4, there is disclosed a fan in which a ring-shaped member is provided so as to rectify the flow along the blade. In Patent Literature 5, there is disclosed a fan in which a groove extending substantially in a circumferential direction is formed in the suction surface of the blade to intend to hold a blade tip vortex.

Citation List

Patent Literature

[PTL 1] JP 2013-19335 A (FIG. 4)
[PTL 2] JP 2005-76501 A (FIGS. 2)
[PTL 3] JP 2011-179330 A (FIGS. 4)
[PTL 4] JP 2009-257260 A (FIG. 1 and FIG. 2)
[PTL 5] JP 2000-192898 A (FIGS. 6)

Summary of Invention

Technical Problem

The blade tip vortex is generated at a radially outer periphery end of the blade suction surface of the rotating fan due to a flow leaking from the pressure surface to the suction surface so that a low-pressure portion is formed on the blade surface. Therefore, the air stream flowing along the suction surface flows toward the radially outer side. As a result, the air stream blowing out from the suction surface has a distribution biased on the radially outer side, thus leading to a problem in that an air blow velocity is increased.
Considering the above-mentioned problem, in the fan disclosed in Patent Literature 1, with the linear projection, the turbulence at the time when the air streams of the pressure surface and the suction surface are joined at the trailing edge may be able to be reduced. However, the possibility that the blowing air stream may be biased on the radially outer side still remains.
Also in the fan disclosed in Patent Literature 2, the thickness portion corresponds to one mode of the convex shape. Similarly to the case of the fan disclosed in Patent Literature 1, the possibility that the blowing air stream may be biased on the radially outer side still remains.
In the fan disclosed in Patent Literature 3, the convex shape is formed on the suction surface of the blade so that the air stream at a portion on the boss side easily stagnates on an inner side in a radial direction. However, the air stream on the radially outer side with respect to an apex of the convex shape easily flows toward the radially outer side due to the inclination. Thus, there is a possibility that the air blow velocity may become non-uniform. Further, the air stream along the suction surface is directed to the boss side. Thus, it is understood that the entire suction surface is inclined toward the boss side. On the pressure surface side, a blade surface inclined toward the upstream side as approaching from the boss side to the outer periphery side is formed. The flow easily leaks from the pressure surface to the suction surface. Thus, there is a possibility that a leakage vortex may be increased.
Further, in the fan disclosed in Patent Literature 4, the ring-shaped member provides an effect of partitioning the flow roughly into the inner side and the outer side in the radial direction with the ring-shaped member being a boundary. However, there is a possibility that, when the flow climbing over the ring-shaped member is generated due to the turbulence of the flow between the blades, significant separation may be generated adversely. Further, in the fan disclosed in Patent Literature 5, when the vortex is held in the groove portion, the flow is biased. Thus, there is a possibility that the air blow velocity of the flow may be biased.
The present invention has been made in view of the above, and has an object to provide a propeller fan capable of uniformizing a blowing flow in a radial direction to suppress a locally-high velocity air stream.

Solution to Problem

In order to achieve the above-mentioned object, according to one embodiment of the present invention, there is provided a propeller fan, including: a boss; and a plurality of blades arranged on an outer periphery of the boss, in which a protruding portion is formed on a suction surface of at least one of the blades, in which the protruding portion extends in a rotating direction at a position separated away from an outer peripheral edge of the blade, and in which an inclination of a radially-inner skirt portion of the protruding portion is gentler than an inclination of a radially-outer skirt portion of the protruding portion.
The height of the protruding portion may be increased as approaching from a forward side to a backward side in the rotating direction. Further, a protruding portion non-forming portion may be present at a portion of the suction surface of the blade on a trailing edge side. The apex of the protruding portion may be positioned to be closer to the boss as approaching to the forward side in the rotating direction RD. The protruding portion may include a curved surface.
Further, in order to achieve the same object, according to one embodiment of the present invention, there is provided an air blower, including: the above-mentioned propeller fan according to the one embodiment of the present invention; a driving source configured to apply a driving force to the propeller fan; and a casing in which the propeller fan and the driving source are housed.
Further, in order to achieve the same object, according to one embodiment of the present invention, there is provided an outdoor unit, including: the above-mentioned propeller fan according to the one embodiment of the present invention; a driving source configured to apply a driving force to the propeller fan; and a casing in which the propeller fan, the driving source, and the heat exchanger are housed.

Advantageous Effects of Invention

According to the one embodiment of the present invention, it is possible to uniformize the blowing flow in the radial direction to suppress the locally-high velocity air stream.

Brief Description of Drawings

FIG. 1 is a perspective view for illustrating an overview of a propeller fan according to a first embodiment of the present invention.
FIG. 2 is a plan view of the propeller fan of FIG. 1.
FIG. 3 is a sectional view taken along the line II of FIG. 2.
FIG. 4 is a perspective view for illustrating a suction surface of one blade of the propeller fan according to the first embodiment of the present invention.
FIG. 5 is a view for illustrating a flow of an air stream in FIG. 4.
FIG. 6 is a view according to an illustration example in the same manner as that of FIG. 5, in which an effect of the present invention is not obtained.
FIG. 7 is a plan view of a propeller fan according to a second embodiment of the present invention.
FIG. 8(a), FIG. 8(b), and FIG. 8(c) are sectional views respectively taken along the line VIIIa, the line VIIIb, and the line VIIIc of FIG. 7.
FIG. 9 is a plan view of a propeller fan according to a third embodiment of the present invention.
FIG. 10(a), FIG. 10(b), and FIG. 10(c) are sectional views respectively taken along the line Xa, the line Xb, and the line Xc of FIG. 9.
FIG. 11 is a plan view of a propeller fan according to a fourth embodiment of the present invention.
FIG. 12(a), FIG. 12(b), and FIG. 12(c) are sectional views respectively taken along the line XIIa, the line XIIb, and the line XIIc of FIG. 11.
FIG. 13 is a perspective view for illustrating one blade, specifically, illustrating a cross section of FIG. 12 (c) andaportion on a forward side in a rotating direction with respect to the cross section in the propeller fan according to the fourth embodiment of the present invention.
FIG. 14 is a perspective view for illustrating an outdoor unit according to a sixth embodiment of the present invention as viewed from an air outlet side thereof.
FIG. 15 is a view for illustrating a configuration of the outdoor unit according to the sixth embodiment as viewed from a top surface side thereof.
FIG. 16 is a view for illustrating a state in which a fan grille is removed according to the sixth embodiment.
FIG. 17 is a view for illustrating an internal configuration in a state in which a front panel and the like are further removed according to the sixth embodiment.

Description of Embodiments

Now, a propeller fan according to embodiments of the present invention is described with reference to the accompanying drawings. Note that, in the drawings, the same reference symbols represent the same or corresponding parts.

First Embodiment

FIG. 1 is a perspective view for illustrating an overview of a propeller fan according to a first embodiment of the present invention. The arrow denoted by the reference symbol RD represents a rotating direction RD of a propeller fan 1, and the arrow denoted by the reference symbol FD represents a flowing direction FD of an air stream at the time of blowing air.
The propeller fan 1 includes a boss 3 having a rotation axis RA and a plurality of (three in the illustrated example) blades 5. The boss 3 is provided so as to be rotatable about the rotation axis RA. The plurality of blades 5 are formed along a side surface 3a of the boss 3. Further, as one example, the plurality of blades 5 are formed into the same shape and arranged equiangularly. Note that, the present invention is not limited thereto, and some of the blades or each blade may have different angular intervals or shapes in arrangement.
Each of the blades 5 has a leading edge 7, a trailing edge 9, and an outer peripheral edge 11. The leading edge 7 is an edge portion on a forward side in a rotating direction of the blade 5, and the trailing edge 9 is an edge portion on a backward side in the rotating direction. The outer peripheral edge 11 is an edge portion connecting a radially outer end of the leading edge 7 and a radially outer end of the trailing edge 9.
Further, each of the blades 5 has a pressure surface 13, which is a surface that pushes the air stream at the time of rotation for blowing the air (at the time when the air stream in the flowing direction FD is generated), and a suction surface 15, which is another surface on a back side of the pressure surface 13. Further, in other words, the pressure surface 13 is such a surface that, when a blade-surface normal direction extending from the surface is decomposed into an axial component and a circumferential component, the circumferential component is oriented to the same direction as the rotating direction RD of the propeller fan 1 at the time of the rotation to blow the air. The suction surface 15 is a surface on the back thereof, specifically, the suction surface 15 is such a surface that, when the blade-surface normal direction extending from the surface is decomposed into the axial component and the circumferential component, the circumferential component is oriented to a direction opposite to the rotating direction RD of the propeller fan 1 at the time of the rotation to blow the air.
FIG. 2 is a plan view for illustrating the propeller fan according to the first embodiment when the propeller fan is projected on a plane orthogonal to the rotation axis RA. More specifically, the rotation axis RA extends orthogonally to the drawing sheet of FIG. 2, the propeller fan 1 is viewed from an upstream side in the flowing direction FD of the air stream, and the suction surface 15 is illustrated on the front side of the drawing sheet of FIG. 2.
Next, mainly referring to FIG. 3 to FIG. 5, the details of a protruding portion formed on the blade are described. FIG. 3 is an illustration of the propeller fan according to the first embodiment in a cross section extending in a radial direction, specifically, a sectional view taken along the line II of FIG. 2. FIG. 4 is a perspective view for illustrating the suction surface of one blade of the propeller fan according to the first embodiment. FIG. 5 is a view for illustrating the flow of the air stream in FIG. 4.
A protruding portion 17 is formed on the suction surface 15 of the blade 5. The protruding portion 17 extends substantially in a circumferential direction. When viewed in the cross section of FIG. 3, the protruding portion 17 corresponds to a portion protruding in a direction separated away from the pressure surface 13 with respect to a reference line RL of the suction surface 15 of the blade 5. The reference line RL is an imaginary curved line on the suction surface 15, which smoothly extends from a radially inner side to a radially outer side similarly to a curved line forming the pressure surface 13. The protruding portion 17 extends in the rotating direction. A width of the protruding portion 17 (dimension in the radial direction) becomes smaller as approaching to a forward side in the rotating direction RD, and the protruding portion 17 ends without reaching the leading edge 7. Further, the protruding portion 17 reaches the trailing edge 9.
Further, in each of the cross sections in the radial direction as illustrated in FIG. 3 as one example, the protruding portion 17 has an apex Pt as a portion at which a height H of the protruding portion 17 becomes maximum. The height H extends from the suction surface 15 toward an upstream side in the flowing direction FD. More precisely, the height H corresponds to a length in a direction orthogonal to the reference line RL.
Further, the protruding portion 17 includes skirt portions respectively on the radially inner side and the radially outer side with the apex Pt being a boundary. A radially-inner skirt portion 17a and a radially-outer skirt portion 17b are each a portion reduced in the height H as the portion is separated away from the apex Pt in the radial direction. The radially-inner skirt portion 17a and the radially-outer skirt portion 17b are each smoothly joined with the reference line RL at a portion sufficiently separated away from the apex Pt. In addition, as one feature of the first embodiment, an inclination of the radially-inner skirt portion 17a is gentler than an inclination of the radially-outer skirt portion 17b. That is, assuming that, as illustrated in FIG. 3, a length along the reference line RL in the cross section of the entire protruding portion 17 in the radial direction is defined as a protruding portion width Pw, a width of the radially-inner skirt portion 17a in the protruding portion width Pw is defined as a radially-inner skirt portion width Wa, and a width of the radially-outer skirt portion 17b is defined as a radially-outer skirt portion width Wb, a relationship of radially-inner skirt portion width Wa> radially-outer skirt portion width Wb is satisfied. That is, the fact that the inclination of the radially-inner skirt portion 17a is gentler than the inclination of the radially-outer skirt portion 17b means that, regarding a decreasing ratio of the height H in the separation distance from the apex Pt (dimension in a width direction), a decreasing ratio in the radially-inner skirt portion 17a is smaller than a decreasing ratio in the radially-outer skirt portion 17b.
Further, a thickness of the blade 5 is described. First, the suction surface 15 has the protruding portion 17 as described above, but the pressure surface 13 has no protruding portion. Therefore, the thickness of the blade 5 is gradually reduced as approaching from a root portion of the blade 5, which is connected to the boss 3, to the outer peripheral edge 11, is once increased as approaching to the apex of the protruding portion 17, and is again reduced as approaching from the apex of the protruding portion 17 to the outer peripheral edge 11.
Note that, the apex Pt of the protruding portion 17 may be any of an acute angle or a gentle curved portion. In FIG. 4, as an example of the case where the apex Pt of the protruding portion 17 is the gentle curved portion, a continuous portion of the apex Pt is indicated by the broken line. Further, as one example, the apex Pt is set at a position on the blade 5, which is closer to the outer peripheral edge 11 being a leading end than the root portion connected to the boss 3 in the radial direction. The protruding portion 17 is formed at a position separated away from the outer peripheral edge 11. The suction surface 15 along the reference line RL is present between the protruding portion 17 and the outer peripheral edge 11. In other words, the dotted line 17b' indicating the outermost portion of the radially-outer skirt portion 17b (that is, the dotted line 17b' indicating a boundary portion between the radially-outer skirt portion 17b and the suction surface 15 along the reference line RL) is present at a position separated away from the outer peripheral edge 11 toward the radially inner side.
Next, an action of the propeller fan having the above-mentioned configuration according to the first embodiment is described. The propeller fan 1 is mounted to a publicly known fan motor, and is configured to be rotated by a rotating force of the fan motor. When the propeller fan 1 is rotated, the air stream flows in from the leading edge 7 of each blade, and is discharged from the trailing edge 9. The air stream is changed in air stream direction due to an inclination and a camber of the blade when the air stream flows along the blade 5, and a static pressure thereof rises due to the change in momentum.
More specific description is given. As illustrated in FIG. 5, due to the flow leaking from the pressure surface 13 to the suction surface 15 at the outer peripheral edge 11 of the blade 5, a leakage vortex 19 (blade tip vortex) is generated at the outer peripheral edge 11. The leakage vortex 19 stagnates in a region in the vicinity of the outer peripheral edge 11 of the suction surface 15, which is hatched in FIG. 5, to thereby generate a low-pressure portion. Then, the air stream flowing along the suction surface 15 is sucked toward the vortex having the low pressure so that the air stream easily flows toward the outer peripheral edge 11 side.
Under such a tendency, in the first embodiment, the protruding portion 17 is formed on the suction surface 15. In particular, due to the presence of the inclination of the radially-inner skirt portion 17a of the protruding portion 17, suction of an air stream 21a, which flows on the boss side, toward the radially outer side is suppressed. Further, the radially-inner skirt portion 17a is formed in a manner of gently changing the height in the radial direction. Thus, the radially-inner skirt portion 17a can apply an action to the air stream 21a in a wide range on the radially inner side with respect to the apex Pt of the protruding portion 17 so that the air stream 21a flows on the inner peripheral side. In this manner, an air blowing direction can be controlled to a desired direction. On the other hand, on the radially outer side with respect to the apex Pt of the protruding portion 17, the radially-outer skirt portion 17b is limitedly arranged in a local range as compared to the radially-inner skirt portion 17a. Therefore, an air stream 21b on the radially outer side can be caused to flow so as to reach the trailing edge without applying an action of causing the air stream 21b to flow toward the outer peripheral edge 11 side to the extent possible. Also with this, drift toward the outer peripheral edge 11 can be suppressed.
Further, as an advantage of providing, on the radially outer side, the radially-outer skirt portion 17b limitedly formed in the local range as compared to the radially-inner skirt portion 17a, there is given an advantage of being capable of reducing the thickness (mass) on the radially outer side to keep high stability at the time of rotation.
Further, in the first embodiment, independently of a mode of the outer peripheral edge of the blade, only with the mode of the suction surface in which the protruding portion 17 is formed on the suction surface 15, deviation of the flow along the suction surface toward the radially outer side can be suppressed. If the protruding portion is not formed and the blade is bent toward the upstream side as approaching to the outer peripheral edge while keeping the constant thickness as in FIG. 6 so that the entire suction surface applies a force acting toward the radially inner side to the flow, an inclination of an opposite pressure surface also becomes an inclination 23 inclined toward the upstream side as approaching from the boss to the outer periphery, thus leading to a problem in that the flow leaking from the pressure surface to the suction surface is increased at the outer peripheral edge. In view of this problem, in the first embodiment, the flow along the suction surface is controlled only with the mode of the suction surface. Thus, the first embodiment does not involve such a problem. Note that, in the first embodiment, as illustrated in FIG. 3, the region on the radially outer side with respect to the apex Pt of the protruding portion 17 (the radially-outer skirt portion 17b and the portion on the radially outer side with respect to the radially-outer skirt portion width Wb) is bent so as to be positioned gradually toward the downstream side in the flowing direction FD as approaching to the outer peripheral edge 11 both in the suction surface 15 and the pressure surface 13. Due to a synergistic effect of the camber of the radially outer side portion toward the downstream side in both the suction surface 15 and the pressure surface 13 as described above and the presence of the above-mentioned protruding portion 17, non-uniformization of the flow along the suction surface in the radial direction can further be suppressed.
As described above, according to the propeller fan of the first embodiment, the deviation of the flow toward the radially outer side can be reduced on the entire suction surface of the blade in the radial direction, thereby being capable of uniformizing the blowing flow from the trailing edge in the radial direction. Therefore, generation of a local high-velocity region can be reduced. As a result, reduction in noise and enhancement in efficiency can be attained.

Second Embodiment

Next, referring to FIG. 7 and FIGS. 8, a propeller fan according to a second embodiment of the present invention is described. Note that, except for parts to be particularly described below, the second embodiment is similar to the above-mentioned first embodiment. FIG. 7 is a plan view of the propeller fan according to the second embodiment. FIG. 8(a), FIG. 8(b), and FIG. 8(c) are sectional views respectively taken along the line VIIIa, the line VIIIb, and the line VIIIc of FIG. 7.
A propeller fan 201 according to the second embodiment includes blades 205 in which a height H of a protruding portion 217 is increased as approaching from a forward side to a backward side in the rotating direction RD (from the upstream side to the downstreamside). Thatis, three cross sections illustrated in FIGS. 8 have a relationship of height H1<H2<H3. Note that, as one example, the reference line also has an inclination in a direction in which the outer peripheral edge 11 is positioned on the downstream side in the flowing direction FD, which is increased as approaching from the forward side to the backward side in the rotating direction RD. That is, regarding the three cross sections illustrated in FIGS. 8, the inclination in the direction in which the outer peripheral edge 11 is positioned on the downstream side in the flowing direction FD is increased in the order of the reference lines RL3, RL2, and RL1.
According to the propeller fan of the second embodiment, which is constructed as described above, the same advantage as that of the above-mentioned first embodiment can be obtained, and further, the following advantages can be obtained. In general, the pressure difference between both surfaces of the blade is increased as approaching to the trailing edge. Accordingly, the leakage vortex generated in the vicinity of the outer peripheral edge 11 also becomes stronger as approaching to the trailing edge. Therefore, the air stream passing along the blade surface is easily sucked toward the radially outer side as approaching to the trailing edge. In view of the above, the height of the protruding portion is increased as approaching from the forward side to the backward side in the rotating direction RD so that particularly the air stream flowing along a portion of the suction surface on the trailing edge side is less easily sucked toward the outer peripheral edge side. In this manner, the non-uniformization of the flow in the radial direction can be suppressed efficiently. Note that, it is more effective to set the starting point S of the protruding portion in a region on the leading edge side with respect to a half point of a blade chord from the leading edge to the trailing edge (portion closer to the leading edge than to the trailing edge) with reference to the flow along the blade surface by an air stream analysis.

Third Embodiment

Next, referring to FIG. 9 andFIGS. 10, a propeller fan according to a third embodiment of the present invention is described. Note that, except for parts to be particularly described below, the third embodiment is similar to the above-mentioned first embodiment. FIG. 9 is a plan view of the propeller fan according to the third embodiment. FIG. 10(a), FIG. 10(b), and FIG. 10(c) are sectional views respectively taken along the line Xa, the line Xb, and the line Xc of FIG. 9.
As understood from FIG. 10 (c) and FIG. 9, a protruding portion 317 of a blade 305 of a propeller fan 301 according to the third embodiment ends without reaching the trailing edge 9. That is, the protruding portion 317 is absent at the trailing edge 9 (a protruding portion non-forming portion 315a is present at a portion of the suction surface on the trailing edge 9 side). Note that, as a mode in which the protruding portion 317 ends without reaching the trailing edge 9, for example, as can be seen from three cross sections illustrated in FIGS. 10 and from FIG. 9, a portion reduced in the height H as approaching from the forward side to the backward side in the rotating direction RD (from the upstream side to the downstream side) may be provided at a portion closer to a trailing edge of the protruding portion 317. In the illustrations, the two cross sections illustrated in FIGS. 10 have a relationship of height H4>H5.
According to the propeller fan of the third embodiment, which is constructed as described above, the same advantage as that of the above-mentioned first embodiment can be obtained, and further, the following advantages can be obtained. For example, when the protruding portion is formed to reach the trailing edge, the thickness of the trailing edge is increased. Thus, there is a possibility that a slipstream may be generated in the blowing flow at the trailing edge. On the other hand, in the third embodiment, the protruding portion is not formed at the trailing edge. Accordingly, the increase in thickness in the vicinity of the trailing edge is avoided, thereby further reducing the possibility that the slipstream may be generated. Also with this, the non-uniformization of the flow can further be suppressed.
Note that, the third embodiment may be carried out in combination with the above-mentioned second embodiment. That is, in the blade having the protruding portion increased in height as approaching from the forward side to the backward side in the rotating direction, the protruding portion non-forming portion may be provided at the portion of the suction surface on the trailing edge side.

Fourth Embodiment

Next, referring to FIG. 11 to FIG. 13, a propeller fan according to a fourth embodiment of the present invention is described. Note that, except for parts to be particularly described below, the fourth embodiment is similar to the above-mentioned first embodiment. FIG. 11 is a plan view of the propeller fan according to the fourth embodiment. FIG. 12(a), FIG. 12(b), and FIG. 12(c) are sectional views respectively taken along the line XIIa, the line XIIb, and the line XIIc of FIG. 11. Further, FIG. 13 is a perspective view for illustrating one blade, specifically, illustrating a cross section of FIG. 12(c) (cross section taken along the line XIIc of FIG. 11) and a portion on the forward side in the rotating direction with respect to the cross section in the propeller fan according to the fourth embodiment.
As can be seen from FIG. 11 to FIG. 13, an apex Pt of a protruding portion 417 of a blade 405 of a propeller fan 401 according to the fourth embodiment is positioned to be closer to the boss 3 as approaching to the forward side in the rotating direction RD (formed to be positioned on the radially inner side). That is, regarding three cross sections illustrated in FIGS. 12, radii R7, R8, and R9 for illustrating the radial position of the apex Pt of the protruding portion 417 have a relationship of radius R7<R8<R9. Further, as a mere example, the reference line has an inclination in a direction in which the outer peripheral edge is positioned on the downstream side in the flowing direction FD, which is increased as approaching from the forward side to the backward side in the rotating direction RD.
According to the propeller fan of the fourth embodiment, which is constructed as described above, the same advantage as that of the above-mentioned first embodiment can be obtained, and further, the following advantages can be obtained. That is, on the downstream side (trailing edge side) on which a value of the pressure rise by the propeller fan is increased, the pressure difference between the pressure surface and the suction surface of the blade is also increased so that the leakage vortex generated at the outer peripheral edge becomes stronger. Thus, a suction force by the leakage vortex is increased. Therefore, there is a tendency that the air stream easily flows toward the radially outer side in a wide range of the blade. In view of this tendency, in the fourth embodiment, the protruding portion is present on the radially outer side as approaching to the downstream side on the blade surface (as approaching to the trailing edge side) so that a suppression force acting in a direction toward the radially inner side can be applied to the air stream in the wide range, which is to flow toward the radially outer side. With this action, the blowing flow can be uniformized in the radial direction.
Note that, the fourth embodiment may be carried out in combination with the above-mentioned second or third embodiment.

Fifth Embodiment

Next, a propeller fan according to a fifth embodiment of the present invention is described. Note that, as can be seen from the drawings for illustrating the already described embodiments, the fifth embodiment has a feature in that the protruding portion having the apex and the skirt portions on both sides is formed by a curved surface in any one of the above-mentioned first to fourth embodiments. With this, in addition to the advantage as that of each of the above-mentioned corresponding first to fourth embodiments, the following advantage can also be obtained. There is a possibility that a part of the air stream passing along the blade surface may climb over the protruding portion. Regarding this possibility, according to the fifth embodiment, when the air stream flows while climbing over the protruding portion, the generation of the significant separation at the protruding portion can be prevented to prevent significant loss.

Sixth Embodiment

Next, an outdoor unit (air blower) according to a sixth embodiment of the present invention is described. FIG. 14 is a perspective view for illustrating the outdoor unit (air blower) according to the sixth embodiment as viewed from an air outlet side thereof, and FIG. 15 is a view for illustrating a configuration of the outdoor unit as viewed from a top surface side thereof. Further, FIG. 16 is an illustration of a state in which a fan grille is removed, and FIG. 17 is a view for illustrating an internal configuration in a state in which a front panel and the like are further removed.
As illustrated in FIG. 14 to FIG. 17, an outdoor-unit main body (casing) 51 is formed as a casing including a pair of right and left side surfaces 51a and 51c, a front surface 51b, a back surface 51d, a top surface 51e, and a bottom surface 51f. The side surface 51a and the back surface 51d each have an opening portion through which the air is sucked from an outside of the outdoor-unit main body (see the arrows A of FIG. 15). Further, in a front panel 52 of the front surface 51b, an air outlet 53 is formed as an opening portion through which the air is blown out to the outside (see the arrows A of FIG. 15). In addition, the air outlet 53 is covered with a fan grille 54. This configuration prevents contact between an object or the like and the propeller fan 1, to thereby assure safety.
The propeller fan 1 is mounted in the outdoor-unit main body 51. The propeller fan 1 is the propeller fan according to any one of the above-mentioned first to fifth embodiments. The propeller fan 1 is connected to a fan motor (driving source) 61 on the back surface 51d side through intermediation of a rotation shaft 62, and is rotationally driven by the fan motor 61.
An inside of the outdoor-unit main body 51 is partitioned by a partition plate (wall) 51g into an air-blowing chamber 56 in which the propeller fan 1 is housed and mounted, and a machine chamber 57 in which a compressor 64 and the like are mounted. On the side surface 51a side and the back surface 51d side in the air-blowing chamber 56, a heat exchanger 68 extending substantially in an L-shape in a plan view is provided.
A bellmouth 63 is arranged on a radially outer side of the propeller fan 1 arranged in the air-blowing chamber 56. The bellmouth 63 is positioned on an outer side of the outer peripheral edge of each of the blades 5, and exhibits an annular shape along the rotating direction of the propeller fan 1. Further, the partition plate 51g is positioned on one side of the bellmouth 63 (on a right side in the drawing sheet of FIG. 15), and a part of the heat exchanger 68 is positioned on another side (opposite side) thereof (on a left side in the drawing sheet of FIG. 15).
A front end of the bellmouth 63 is connected to the front panel 52 of the outdoor unit so as to surround an outer periphery of the air outlet 53. Note that, the bellmouth 63 may be formed integrally with the front panel 52, or may be prepared as a separate component to be connected to the front panel 52. Due to the bellmouth 63, a flow passage between an air inlet side and an air outlet side of the bellmouth 63 is formed as an air passage in the vicinity of the air outlet 53. That is, the air passage in the vicinity of the air outlet 53 is partitioned by the bellmouth 63 from another space in the air-blowing chamber 56.
The heat exchanger 68 provided on the air inlet side of the propeller fan 1 includes a plurality of fins aligned side by side so that respective plate-like surfaces are parallel to each other, and heat-transfer pipes passing through the respective fins in an aligning direction of the fins. Arefrigerant, which circulates through a refrigerant circuit, flows in the heat-transfer pipes. In the heat exchanger 68 according to this embodiment, the heat-transfer pipes extend in an L-shape along the side surface 51a and the back surface 51d of the outdoor-unit main body 51, and as illustrated in FIG. 17, the heat-transfer pipes in a plurality of tiers are constructed so as to pass through the fins in a zigzag manner. Further, the heat exchanger 68 is connected to the compressor 64 through piping 65 or the like. In addition, the heat exchanger 68 is connected to an indoor-side heat exchanger, an expansion valve, and the like (not shown) so as to form a refrigerant circuit of an air conditioner. Further, a board box 66 is arranged in the machine chamber 57. Devices mounted in the outdoor unit are controlled by a control board 67 provided in the board box 66.
Also in the sixth embodiment, the same advantage as that of each of the above-mentioned corresponding first to fifth embodiments can be obtained. Further, when the propeller fan of one of the above-mentioned first to fifth embodiments is mounted to the air blower, a flow rate of the air to be blown can be increased with high efficiency. Further, when the propeller fan of one of the above-mentioned first to fifth embodiments is mounted to the outdoor unit of the air conditioner, which serves as a refrigeration cycle system including the compressor, the heat exchanger, and the like, or to the outdoor unit of a hot-water supply device, the flow rate of the air to pass through the heat exchanger can be secured with low noise and high efficiency. With this, the low noise and high energy efficiency of the devices can be achieved.
Note that, in the sixth embodiment, the outdoor unit of the air conditioner is exemplified as an outdoor unit including anairblower. However, the present invention is not limited thereto, but can be implemented as, for example, an outdoor unit of a hot-water supply device or the like. In addition, the present invention can be widely employed as an apparatus for blowing the air, and can be applied to an apparatus, equipment, and the like other than the outdoor unit.
Although the details of the present invention are specifically described above with reference to the preferred embodiments, it is apparent that persons skilled in the art may adopt various modifications based on the basic technical concepts and teachings of the present invention.
For example, the protruding portion is formed similarly on each of all the blades. However, the present invention is not limited thereto. The protruding portion may be selectively formed on the plurality of blades constructing the propeller fan. Note that, for the sake of clarity of illustration, the illustration of the protruding portions is omitted in FIG. 1, FIG. 2, and FIG. 14 to FIG. 17.

Reference Signs List

1, 201, 301, 401 propeller fan, 3 boss, 5, 205, 305, 405 blade, 7 leading edge, 9 trailing edge, 11 outer peripheral edge, 13 pressure surface, 15 suction surface, 17, 217, 317, 417 protruding portion, 17a radially-inner skirt portion, 17b radially-outer skirt portion, 315a protruding portion non-forming portion

Claims

A propeller fan, comprising:
a boss; and

a plurality of blades arranged on an outer periphery of the boss,

wherein a protruding portion is formed on a suction surface of at least one of the blades, and

wherein an inclination of the radially-inner skirt portion of the protruding portion is gentler than an inclination of the radially-outer skirt portion of the protruding portion.
A propeller fan according to claim 1, wherein the height of the protruding portion is increased as approaching from a forward side to a backward side in the rotating direction.
A propeller fan according to claim 1 or 2, wherein a protruding portion non-forming portion is present at a portion of the suction surface of the blade on a trailing edge side.
A propeller fan according to any one of claims 1 to 3, wherein the apex of the protruding portion is positioned to be closer to the boss as approaching to the forward side in the rotating direction RD.
A propeller fan according to any one of claims 1 to 4, wherein the protruding portion comprises a curved surface.
An air blower, comprising:
the propeller fan of any one of claims 1 to 5;

a driving source configured to apply a driving force to the propeller fan; and

a casing in which the propeller fan and the driving source are housed.
An outdoor unit, comprising:
a heat exchanger;

the propeller fan of any one of claims 1 to 5;

a driving source configured to apply a driving force to the propeller fan; and

a casing in which the propeller fan, the driving source, and the heat exchanger are housed.