EP4350151A1 - Propeller fan and air conditioner - Google Patents

Propeller fan and air conditioner Download PDF

Info

Publication number
EP4350151A1
EP4350151A1 EP21942926.3A EP21942926A EP4350151A1 EP 4350151 A1 EP4350151 A1 EP 4350151A1 EP 21942926 A EP21942926 A EP 21942926A EP 4350151 A1 EP4350151 A1 EP 4350151A1
Authority
EP
European Patent Office
Prior art keywords
blade
propeller
leading edge
edge portion
trailing edge
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21942926.3A
Other languages
German (de)
French (fr)
Inventor
Taku IWASE
Tetsushi Kishitani
Hideshi OBARA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Johnson Controls Air Conditioning Inc
Original Assignee
Hitachi Johnson Controls Air Conditioning Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Johnson Controls Air Conditioning Inc filed Critical Hitachi Johnson Controls Air Conditioning Inc
Publication of EP4350151A1 publication Critical patent/EP4350151A1/en
Pending legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/38—Blades
    • F04D29/384—Blades characterised by form
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2240/00—Components
    • F05D2240/20—Rotors
    • F05D2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
    • F05D2240/303—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor related to the leading edge of a rotor blade
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2240/00—Components
    • F05D2240/20—Rotors
    • F05D2240/30—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor
    • F05D2240/304—Characteristics of rotor blades, i.e. of any element transforming dynamic fluid energy to or from rotational energy and being attached to a rotor related to the trailing edge of a rotor blade

Definitions

  • the present invention relates to a propeller fan and the like.
  • Patent Literature 1 describes an axial fan configured such that a sectional shape along a blade rotation direction is formed alternately with three or more bulging portions bulging toward a blade suction surface side and three or more bulging portions bulging toward a blade pressure surface side.
  • PATENT LITERATURE 1 JP-A-2010-150945
  • Patent Literature 1 there is a possibility that separation of an air flow occurs on the suction surface side of the bulging portion bulging toward the pressure surface side. When pressure fluctuation due to such separation of the air flow occurs, aerodynamic noise increases. For this reason, the technique described in Patent Literature 1 has room for improvement in noise reduction.
  • the present invention is intended to provide, e.g., a low-noise and high-efficiency propeller fan of which the thickness can be reduced.
  • the present invention provides a propeller fan including a propeller including a boss portion rotating integrally with a motor shaft and a plurality of blades installed in the boss portion, and a bell mouth provided on the outer peripheral side of the propeller, a first position closest to a suction side at a leading edge portion of each blade being provided between a blade leading edge tip and a blade leading edge root, the leading edge portion having, between the blade leading edge tip and the first position, a recessed shape curved toward a blowing side, and a trailing edge portion of each blade having a raised shape curved toward the blowing side.
  • the present invention it is possible to provide, e.g., the low-noise and high-efficiency propeller fan of which the thickness can be reduced.
  • Fig. 1 is a configuration diagram including a refrigerant circuit Q of an air-conditioner 100 including a propeller fan according to a first embodiment.
  • the air-conditioner 100 is a device that performs air-conditioning such as the heating operation or the cooling operation.
  • the air-conditioner 100 includes a compressor 1, an outdoor heat exchanger 2, a propeller 3 (outdoor fan), and an expansion valve 4.
  • the air-conditioner 100 further includes an indoor heat exchanger 5, an indoor fan 6, and a four-way valve 7 in addition to the above-described configuration.
  • the compressor 1 is a device that compresses low-temperature low-pressure gas refrigerant and discharges high-temperature high-pressure gas refrigerant.
  • a compressor 1 for example, a scroll compressor or a rotary compressor is used.
  • the outdoor heat exchanger 2 is a heat exchanger in which heat is exchanged between refrigerant flowing in a heat transfer pipe (not shown) thereof and external air sent from the propeller 3.
  • the propeller 3 (outdoor fan) is an axial fan that sends external air to the outdoor heat exchanger 2.
  • the propeller 3 includes a fan motor 31 as a drive source, and is installed in the vicinity of the outdoor heat exchanger 2.
  • the expansion valve 4 is a valve that decompresses refrigerant condensed in a "condenser” (one of the outdoor heat exchanger 2 or the indoor heat exchanger 5). Note that the refrigerant decompressed by the expansion valve 4 is guided to an "evaporator" (the other one of the outdoor heat exchanger 2 or the indoor heat exchanger 5).
  • the indoor heat exchanger 5 is a heat exchanger in which heat is exchanged between refrigerant flowing in a heat transfer pipe (not shown) thereof and room air (air in an air-conditioning room) sent from the indoor fan 6.
  • the indoor fan 6 is a fan that sends room air to the indoor heat exchanger 5.
  • the indoor fan 6 includes an indoor fan motor 61 as a drive source, and is installed in the vicinity of the indoor heat exchanger 5. As such an indoor fan 6, for example, a cross flow fan is used.
  • the four-way valve 7 is a valve that switches the flow path of refrigerant according to the operation mode of the air-conditioner 100.
  • refrigerant circulates sequentially through the compressor 1, the outdoor heat exchanger 2 (condenser), the expansion valve 4, and the indoor heat exchanger 5 (evaporator) in the refrigerant circuit Q.
  • the heating operation see the solid arrows in Fig. 1
  • refrigerant circulates sequentially through the compressor 1, the indoor heat exchanger 5 (condenser), the expansion valve 4, and the outdoor heat exchanger 2 (evaporator) in the refrigerant circuit Q.
  • the compressor 1, the outdoor heat exchanger 2, the propeller 3 (outdoor fan), the expansion valve 4, and the four-way valve 7 are installed in an outdoor unit 10.
  • the indoor heat exchanger 5 and the indoor fan 6 are installed in an indoor unit 20.
  • devices such as the expansion valve 4, the indoor fan 6, and the four-way valve 7 are controlled by a control device (not shown) in a predetermined manner.
  • Fig. 2 is a sectional view of the outdoor unit 10 including a propeller fan U1.
  • Fig. 2 shows a schematic section of the side blowing outdoor unit 10 taken along a predetermined horizontal plane including the center axis Y of the propeller 3.
  • Fig. 2 also shows the meridian plane of a blade 32 of the propeller 3 (also see Fig. 3 ).
  • the "meridian plane" of the blade 32 is obtained by rotationally projecting the shape of the blade 32 in a predetermined manner with reference to the center axis Y of the propeller 3.
  • the flow of air is indicated by white thick arrows.
  • the propeller fan U1 includes the propeller 3 and a bell mouth 8, and is installed inside the outdoor unit 10.
  • the propeller 3 is an axial fan that sends air substantially in an axial direction.
  • the propeller 3 includes the fan motor 31 as the drive source, a boss portion 33 having a circular columnar outer shape and rotating integrally with a motor shaft 31a of the fan motor 31, and three blades 32 (see also Fig. 3 ) installed on a peripheral wall of the boss portion 33.
  • the propeller fan U1 is installed such that the direction of the center axis Y (the axial direction of the motor shaft 31a) is parallel with the front-back direction of the outdoor unit 10.
  • the bell mouth 8 is a rectifying member that guides air sucked into the propeller 3 in a predetermined manner and guides air blown from the propeller 3 in a predetermined manner.
  • the bell mouth 8 has a cylindrical shape, and is provided on the outer peripheral side (outside in the radial direction) of the propeller 3. Note that the center axis of the bell mouth 8 substantially coincides with the center axis Y of the propeller 3.
  • the bell mouth 8 includes a curved portion 81 and an enlarged-diameter portion 82.
  • the curved portion 81 has a thin cylindrical shape, and is curved in a predetermined manner such that the diameter thereof decreases toward the downstream side (blowing side) of the air flow.
  • the enlarged-diameter portion 82 has a side surface shape of a truncated cone, and is continuous with the downstream side (blowing side) of the curved portion 81.
  • the enlarged-diameter portion 82 is formed such that the diameter thereof increases toward the downstream side (blowing side) of the air flow.
  • the outdoor heat exchanger 2 having an L shape in a cross-sectional view is provided on the back and left sides of the outdoor unit 10.
  • a portion on the back side of the outdoor unit 10 is positioned on the upstream side of the propeller 3 in an air flow direction. Air subjected to heat exchange in the outdoor heat exchanger 2 is sucked into the propeller 3 while being rectified by the bell mouth 8, and is blown from the propeller 3 in a predetermined manner.
  • a machine room R1 shown in Fig. 2 is a space where the compressor 1 (see Fig. 1 ), an accumulator (not shown), the expansion valve 4 (see Fig. 1 ) and the like are housed, and is provided on the right side of the propeller fan U1.
  • a fan chamber R2 where the propeller fan U1 is housed and the machine room R1 are partitioned in a predetermined manner by a partition plate (not shown).
  • a first position ⁇ , a second position ⁇ , and a third position ⁇ will be described later.
  • Fig. 3 is a perspective view of the propeller 3 included in the propeller fan.
  • a hatched thick arrow shown in Fig. 3 and the like indicates the direction in which the propeller 3 rotates.
  • a thick white arrow shown in Fig. 3 and the like indicates the direction in which air flows in association with rotation of the propeller 3.
  • the three blades 32 shown in Fig. 3 are provided at equal angular intervals on the peripheral wall of the boss portion 33, and radially extend substantially in the radial direction from the boss portion 33. More specifically, each of the three blades 32 extends so as to be inclined forward in the rotation direction with respect to the radial direction about the center axis Y (also see Fig. 4 ). Note that the number of blades 32 may be two or four or more other than the three blades shown in Fig. 3 .
  • Fig. 4 is a view of the propeller 3 from an air suction side in the direction of the center axis Y of the propeller 3.
  • each of the plurality of blades 32 includes a leading edge portion 32a, a trailing edge portion 32b, a blade tip portion 32c, and a blade root portion 32d.
  • the leading edge portion 32a is an edge portion of the blade 32 positioned on the front side in the rotation direction of the propeller 3.
  • the trailing edge portion 32b is an edge portion of the blade 32 positioned on the back side in the rotation direction of the propeller 3.
  • the blade tip portion 32c is an outer peripheral side edge portion of the blade 32.
  • the blade root portion 32d is an inner peripheral side edge portion of the blade 32.
  • the blade tip portion 32c and the leading edge portion 32a are adjacent to each other through the blade leading edge tip 321.
  • the blade tip portion 32c and the trailing edge portion 32b are adjacent to each other through the blade trailing edge tip 322.
  • the blade root portion 32d and the leading edge portion 32a are adjacent to each other through the blade leading edge root 323.
  • the blade root portion 32d and the trailing edge portion 32b are adjacent to each other through the blade trailing edge root 324.
  • the blade leading edge tip 321, the blade trailing edge tip 322, the blade leading edge root 323, and the blade trailing edge root 324 are also shown on the meridian plane of the propeller 3 in Fig. 2 .
  • the leading edge portion 32a has a recessed shape so as to curve toward the back side in the rotation direction.
  • the trailing edge portion 32b has a raised shape so as to curve toward the back side in the rotation direction.
  • the blade tip portion 32c has an arc shape so as to form a predetermined clearance with the inner peripheral surface of the bell mouth 8 (see Fig. 2 ).
  • the blade root portion 32d is formed in an arc shape along the outer peripheral surface of boss portion 33.
  • Each blade 32 includes a pressure surface 32e (see Fig. 3 ) and a suction surface 32f.
  • the pressure surface 32e is a surface on the front side (blowing side, far side of the plane of paper of Fig. 4 ) in the direction of the center axis Y among two surfaces of the blade 32.
  • air is pushed out by the pressure surface 32e in a predetermined manner as the blades 32 move.
  • the suction surface 32f is a surface on the back side (suction side, near side of the plane of paper of Fig. 4 ) in the direction of the center axis Y among the two surfaces of the blade 32. That is, the suction surface 32f is a back-side surface of the pressure surface 32e (see Fig. 3 ).
  • the suction surface 32f f is visible, but the pressure surface 32e on the back side (see Fig. 3 ) is not visible.
  • Fig. 5A is a sectional view of the blade 32 taken along a cylindrical plane including an arc A-A in Fig. 4 .
  • the arc A-A indicated by a dashed line in Fig. 4 is a virtual arc passing through the vicinity of the blade tip portion 32c about the center axis Y of the propeller 3 (the center of the arc).
  • each arrow in the vicinity of reference numerals such as the arc A-A in Fig. 4 indicates a direction when the blade 32 is viewed in section.
  • a hatched thick arrow shown in Fig. 5A and the like indicates the direction in which the blade 32 moves in association with rotation of the propeller 3.
  • a thick white arrow shown in Fig. 5A and the like indicates the direction in which air flows in association with rotation of the propeller 3.
  • the vicinity of the blade tip portion 32c (see Fig. 4 ) is inclined in a predetermined manner so as to be positioned on the air suction side (upper side in the plan of paper of Fig. 5A ) while extending forward (right side in the plan of paper of Fig. 5A ) in the rotation direction of the propeller 3, as shown in Fig. 5A .
  • Fig. 5B is a sectional view of the blade 32 taken along a cylindrical plane including an arc B-B in Fig. 4 .
  • the arc B-B indicated by a dashed line in Fig. 4 is a virtual arc passing through an intermediate portion between the blade tip portion 32c and the blade root portion 32d about the center axis Y of the propeller 3 (the center of the arc). That is, the distance from the center axis Y to the arc B-B shown in Fig. 4 is a value obtained by dividing the sum of the distance from the center axis Y to the blade tip portion 32c and the distance from the center axis Y to the blade root portion 32d by 2. As shown in Fig.
  • the intermediate portion of the blade 32 is also inclined in a predetermined manner so as to be positioned on the air suction side (upper side in the plan of paper of Fig. 5B ) while extending forward (right side in the plan of paper of Fig. 5B ) in the rotation direction of the propeller 3.
  • Fig. 5C is a sectional view of the blade 32 taken along a cylindrical plane including an arc C-C in Fig. 4 .
  • the arc C-C indicated by a dashed line in Fig. 4 is a virtual arc passing through the vicinity of the blade root portion 32d about the center axis Y of the propeller 3 (the center of the arc).
  • the vicinity of the blade root portion 32d (see Fig. 4 ) is also inclined in a predetermined manner so as to be positioned on the air suction side (upper side in the plan of paper of Fig. 5C ) while extending forward (right side in the plan of paper of Fig. 5C ) in the rotation direction of the propeller 3, as shown in Fig. 5C .
  • the blade 32 is curved in a gently-raised shape as viewed from the air suction side in the vicinity of the blade root portion 32d (see Fig. 5C ). With this configuration, the pressure of air is easily increased by the pressure surface 32e of the blade 32.
  • Fig. 6A is a sectional view of the blade 32 taken along a span line D-D in Fig. 4 .
  • the "span line” is a line connecting points, at which a ratio between the distance from the leading edge portion 32a (see Fig. 4 ) to the distance from the trailing edge portion 32b (see Fig. 4 ) is constant, from the blade tip portion 32c (see Fig. 4 ) to the blade root portion 32d (see Fig. 4 ) in each of a plurality of cylindrical sections with respect to (about) the center axis Y (see Fig. 4 ).
  • the distance from the leading edge portion 32a to the span line D-D and the distance from the trailing edge portion 32b to the span line D-D are measured in a predetermined manner along the warp line of the blade 32.
  • a direction along the span line will be referred to as a "span direction.”
  • the span line D-D (corresponding to the section of Fig. 6A ) shown in Fig. 4 is a span line passing the vicinity of the leading edge portion 32a of the blade 32.
  • the leading edge portion 32a (see Fig. 2 ) of the blade 32 also has a shape similar to that of Fig. 6A .
  • reference numerals of the blade leading edge tip 321, the blade leading edge root 323 and the like are also shown in Fig. 6A showing the section in the span direction in the vicinity of the leading edge portion 32a.
  • the section of the vicinity of the leading edge portion 32a (see Fig. 4 ) taken along the span line D-D has an inverted S shape as shown in Fig. 6A .
  • the leading edge portion 32a also has a similar inverted S-shape.
  • the first position ⁇ closest to the suction side at the leading edge portion 32a of the blade 32 is provided between the blade leading edge tip 321 and the blade leading edge root 323.
  • the leading edge portion 32a has a recessed shape curved toward the blowing side.
  • the "recessed shape" curved toward the blowing side refers to such a shape that a portion of the leading edge portion 32a closer to the third position ⁇ between the blade leading edge tip 321 and the first position ⁇ is positioned closer to the blowing side.
  • the blade leading edge tip 321 is positioned on the blowing side with respect to the first position ⁇ .
  • the propeller height HP (dimension in the axial direction) of the propeller 3 is shorter than that when the blade leading edge tip 321 is positioned on the suction side with respect to the first position ⁇ .
  • the propeller 3 can be reduced in thickness.
  • Fig. 6B is a sectional view of the blade 32 taken along a span line E-E in Fig. 4 .
  • a span line E-E in Fig. 4 is a span line passing through an intermediate position in the circumferential direction between the leading edge portion 32a and the trailing edge portion 32b.
  • the section along the span line E-E also has an inverted S-shape as in Fig. 6A , but the degree of curvature of the inverted S-shape is gentler than that of the section (see Fig. 6A ) along the span line D-D (see Fig. 4 ). That is, the degree of curvature of the inverted S-shape gradually decreases from the leading edge portion 32a (see Fig. 2 ) toward the intermediate position (see Fig. 6B ) in the span direction.
  • Fig. 6C is a sectional view of the blade 32 taken along a span line F-F in Fig. 4 .
  • the span line F-F in Fig. 4 is a span line passing the vicinity of the trailing edge portion 32b of the blade 32.
  • the trailing edge portion 32b also has a shape similar to that of Fig. 6C .
  • reference numerals of the blade trailing edge tip 322, the blade trailing edge root 324 and the like are also shown in Fig. 6C showing the section in the span direction in the vicinity of the trailing edge portion 32b.
  • the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side (a recessed shape when viewed from the suction side.).
  • the second position ⁇ positioned closest to the blowing side at the trailing edge portion 32b is provided between the blade trailing edge tip 322 and the blade trailing edge root 324.
  • a portion of the trailing edge portion 32b closer to the second position ⁇ is positioned closer to the blowing side.
  • the degree of curvature of the blade 32 toward the blowing side gradually increases from the intermediate position in Fig. 6B toward the trailing edge portion 32b (see Fig. 2 ) in the span direction.
  • the entire trailing edge portion 32b is curved in a raised shape toward the blowing side.
  • the first position ⁇ is preferably provided at a first intermediate portion 325 (see Fig. 6A ) between the blade leading edge tip 321 and the blade leading edge root 323.
  • the second position ⁇ is preferably provided at a second intermediate portion 326 (see Fig. 6C ) between the blade trailing edge tip 322 and the blade trailing edge root 324.
  • the first intermediate portion 325 described above for example, an intermediate portion in a case where the leading edge portion 32a is divided into three equal portions in the span direction, i.e., the blade tip side, the intermediate portion, and the blade root side.
  • an intermediate portion obtained by dividing the trailing edge portion 32b into three equal portions in the span direction may be used.
  • an area between the first position ⁇ and the blade leading edge tip 321 can be sufficiently ensured in the span direction. Accordingly, the diagonal flow of air having an inward velocity component in the radial direction is easily along the blade 32. In addition, the length between the first position ⁇ and the second position ⁇ is easily ensured in the axial direction of the propeller 3. As a result, it is possible to suppress a decrease in the rate of increase in static pressure and in air volume while reducing the propeller 3 in thickness.
  • Fig. 15 is a sectional view of a blade 34 of a general propeller taken along a predetermined cylindrical plane.
  • a chord length L shown in Fig. 15 is the length of a chord line S.
  • the chord line S is a line segment connecting a leading edge 34a and a trailing edge 34b in the blade section of the blade 34.
  • An attachment angle ⁇ is an angle between ⁇ the chord line S and a rotation plane X. Note that it is assumed that the rotation plane X is perpendicular to the center axis (not shown) of the propeller.
  • chord length L The longer the chord length L shown in Fig. 15 , the greater the rate of increase in static pressure and the greater the air volume. Moreover, the greater the attachment angle ⁇ , the greater the rate of increase in static pressure and the greater the air volume. Thus, the chord length L and the attachment angle ⁇ are important design values for ensuring the rate of increase in static pressure and the air volume.
  • Fig. 16 is a sectional view of an outdoor unit 10G including a propeller 3G according to a comparative example.
  • Fig. 16 shows the meridian plane of a blade 32G of the propeller 3G (also see Fig. 17 ).
  • a leading edge portion 32Ga is positioned closer to the suction side toward a blade leading edge tip 321G.
  • a trailing edge portion 32Gb is positioned closer to the blowing side toward a blade trailing edge tip 322G.
  • the propeller 3G is formed such that the chord length L (see Fig. 15 ) and the attachment angle ⁇ (see Fig. 15 ) are maximized at a blade tip portion 32Gc.
  • the propeller height HP is determined by the chord length L and the attachment angle ⁇ at the blade tip portion 32Gc.
  • Fig. 17 is a perspective view of the propeller 3G according to the comparative example.
  • the propeller 3G shown in Fig. 17 corresponds to the configuration of Fig. 16 .
  • HP see Fig. 16
  • a method of decreasing the chord length L (see Fig. 15 ) at the blade tip portion 32Gc or decreasing the attachment angle ⁇ (see Fig. 15 ) has been adopted.
  • the rate of increase in static pressure of the propeller 3G decreases, but also the air volume decreases.
  • noise may increase.
  • the leading edge portion 32a has the recessed shape curved toward the blowing side between the blade leading edge tip 321 and the first position ⁇ as shown in Fig. 2 .
  • the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side.
  • the first position ⁇ and the second position ⁇ which define the propeller height HP are at predetermined positions (for example, in the vicinity of the intermediate portion in the span direction) between the blade tip portion 32c and the blade root portion 32d.
  • the chord length L (see Fig. 15 ) and the attachment angle ⁇ (see Fig. 15 ) can be relatively great in the vicinity of the first position ⁇ and the second position ⁇ .
  • the propeller height HP is determined by the first position ⁇ at the leading edge portion 32a of the blade 32 and the second position ⁇ at the trailing edge portion 32b of the blade 32.
  • the leading edge portion 32a has the recessed shape on the blowing side.
  • the trailing edge portion 32b of the blade 32 since the trailing edge portion 32b of the blade 32 has the raised shape on the blowing side, air blown from the propeller 3 is guided in the diagonal direction so as to include the outward velocity component in the radial direction (see the arrows W3, W4 in Fig. 2 ), and further flows along the enlarged-diameter portion 82 of the bell mouth 8. Thus, it is possible to reduce the pressure loss of air in the bell mouth 8 and to enhance the efficiency.
  • the trailing edge portion 32b of the blade 32 has no recessed portion as viewed from the blowing side, and therefore, almost no separation of the air flow occurs on the suction surface 32f (see Fig. 3 ) of the blade 32. Thus, it is possible to suppress a decrease in the rate of increase in static pressure.
  • a second embodiment is different from the first embodiment in that a distance RD in the radial direction from the center axis Y of a propeller 3A (see Fig. 7 ) to the first position ⁇ is equal to a distance RD in the radial direction from the center axis Y to the second position ⁇ .
  • Note that other configurations are the same as those of the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 7 is a sectional view of an outdoor unit 10A including a propeller fan UA1 according to the second embodiment.
  • Fig. 7 shows the meridian plane of a blade 32A of the propeller 3A.
  • the distance RD in the radial direction from the center axis Y of the propeller 3A to the first position ⁇ is equal to the distance RD in the radial direction from the center axis Y to the second position ⁇ .
  • the first position ⁇ and the second position ⁇ can be appropriately adjusted at a design stage based on one blade section (section of the blade 32A taken along a predetermined cylindrical plane) including the first position ⁇ and the second position ⁇ .
  • a work load at the design stage can be reduced.
  • the propeller 3A since the first position ⁇ and the second position ⁇ can be appropriately adjusted at the design stage in the predetermined blade section (one blade section) of the propeller 3A taken along the predetermined cylindrical plane, the propeller 3A can be easily designed.
  • a third embodiment is different from the first embodiment in that the attachment angle of a blade section is maximized at the first position ⁇ (see Fig. 2 ), but is otherwise similar to the first embodiment.
  • contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 8 is a graph for describing the attachment angle ⁇ of the blade section in a propeller fan according to the third embodiment.
  • the horizontal axis in Fig. 8 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2 ).
  • the vertical axis in Fig. 8 represents the attachment angle ⁇ of the blade section corresponding to each radius.
  • the "blade section” is the section of the blade 32 taken along a predetermined cylindrical plane.
  • a value "0" on the horizontal axis in Fig. 8 indicates the radius of the boss portion 33 (see Fig. 2 ).
  • a value "1" on the horizontal axis in Fig. 8 indicates the radius of the blade tip portion 32c (see Fig. 2 ).
  • a solid line in Fig. 8 indicates the attachment angle ⁇ of the blade section at each radius in the propeller 3 according to the third embodiment.
  • a chain line in Fig. 8 indicates the attachment angle ⁇ of the blade section at each radius in the propeller 3G according to the comparative example (see Figs. 16 and 17 ).
  • the attachment angle ⁇ decreases toward the blade tip portion ("1" on the horizontal axis).
  • the attachment angle ⁇ of the blade section is maximized at a radius R ⁇ at the first position ⁇ (see Fig. 2 ).
  • the degree of the attachment angle ⁇ can be sufficiently ensured in the vicinity of the first position ⁇ , and therefore, the rate of increase in static pressure and the air volume can be increased.
  • the second position ⁇ (see Fig. 2 ) is not particularly shown in Fig. 8
  • the second position ⁇ may be provided on either the blade tip side or the blade root side with respect to the first position ⁇ .
  • the attachment angle ⁇ of the blade section is maximized at the first position ⁇ (see Fig. 2 )
  • the amount of work by the propeller 3 in the vicinity of the first position ⁇ is relatively great.
  • the rate of increase in static pressure and the air volume can be sufficiently ensured.
  • a fourth embodiment is different from the first embodiment in that the attachment angle of a blade section is maximized at the second position ⁇ (see Fig. 2 ), but is otherwise similar to the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 9 is a graph for describing the attachment angle ⁇ of the blade section in a propeller fan according to the fourth embodiment.
  • the horizontal axis in Fig. 9 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2 )
  • the vertical axis represents the attachment angle ⁇ .
  • the attachment angle ⁇ of the blade section is maximized at a radius R ⁇ at the second position ⁇ (see Fig. 2 ).
  • the degree of the attachment angle ⁇ can be sufficiently ensured in the vicinity of the second position ⁇ , and therefore, the rate of increase in static pressure and the air volume can be increased.
  • the first position ⁇ (see Fig. 2 ) is not particularly shown in Fig. 9
  • the first position ⁇ may be provided on either the blade tip side or the blade root side with respect to the second position ⁇ .
  • the attachment angle ⁇ of the blade section is maximized at the second position ⁇ (see Fig. 2 )
  • the amount of work by the propeller 3 in the vicinity of the second position ⁇ is relatively great.
  • the rate of increase in static pressure and the air volume can be sufficiently ensured.
  • a fifth embodiment is different from the first embodiment in that a chord length is maximized at the first position ⁇ (see Fig. 2 ), but is otherwise similar to the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 10 is a graph for describing a chord length L in a propeller fan according to the fifth embodiment.
  • the horizontal axis in Fig. 10 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2 ).
  • the vertical axis in Fig. 10 represents the chord length L of the blade section corresponding to each radius.
  • a solid line in Fig. 10 indicates the chord length L at each radius in the propeller 3 according to the fifth embodiment.
  • a chain line in Fig. 10 indicates a chord length L at each radius in the propeller 3G according to the comparative example (see Figs. 16 and 17 ). As shown in Fig. 10 , in the comparative example (chain line in Fig. 10 ), the chord length increases toward the blade tip portion ("1" on the horizontal axis).
  • the chord length L is maximized at a radius R ⁇ at the first position ⁇ (see Fig. 2 ).
  • the chord length L can be sufficiently ensured in the vicinity of the first position ⁇ , and therefore, the rate of increase in static pressure and the air volume can be increased.
  • the second position ⁇ (see Fig. 2 ) is not particularly shown in Fig. 10
  • the second position ⁇ may be provided on either the blade tip side or the blade root side with respect to the first position ⁇ .
  • the chord length L is maximized at the first position ⁇ (see Fig. 2 )
  • the amount of work by the propeller 3 in the vicinity of the first position ⁇ is relatively great.
  • the rate of increase in static pressure and the air volume can be sufficiently ensured.
  • a sixth embodiment is different from the first embodiment in that a chord length is maximized at the second position ⁇ (see Fig. 2 ), but is otherwise similar to the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 11 is a graph for describing a chord length L in a propeller fan according to the sixth embodiment.
  • the horizontal axis in Fig. 11 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2 )
  • the vertical axis represents the chord length L.
  • the chord length L is maximized at a radius R ⁇ at the second position ⁇ (see Fig. 2 ).
  • the chord length L can be sufficiently ensured in the vicinity of the second position ⁇ , and therefore, the rate of increase in static pressure and the air volume can be increased.
  • the first position ⁇ (see Fig. 2 ) is not particularly shown in Fig. 11
  • the first position ⁇ may be provided on either the blade tip side or the blade root side with respect to the second position ⁇ .
  • the chord length L is maximized at the second position ⁇ (see Fig. 2 )
  • the amount of work by the propeller 3 in the vicinity of the second position ⁇ is relatively great.
  • the rate of increase in static pressure and the air volume can be sufficiently ensured.
  • a seventh embodiment is different from the first embodiment in that a propeller fan UB1 (see Fig. 13 ) is provided in a top blowing outdoor unit 10B (see Fig. 13 ). Moreover, the seventh embodiment is different from the first embodiment in that an air-conditioner 100B is a multi-type air-conditioner including a plurality of indoor units 21 to 24 (see Fig. 12 ). Note that other configurations (e.g., the configuration of the propeller 3: see Fig. 13 ) are similar to those of the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 12 is a configuration diagram of the air-conditioner 100B including a propeller fan according to the seventh embodiment.
  • a refrigerant pipe K1 is simplified and, e.g., a refrigerant pipe for guiding refrigerant from the outdoor unit 10B to the indoor unit 21 and the like and a refrigerant pipe for guiding refrigerant from the indoor unit 21 and the like to the outdoor unit 10B are indicated by a common solid line.
  • the multi-type air-conditioner 100B shown in Fig. 12 includes the top blowing outdoor unit 10B and the four ceiling embedded indoor units 21 to 24.
  • Refrigerant circulates in a predetermined manner in a refrigerant circuit QB in which the indoor units 21 to 24 are connected in parallel through the refrigerant pipe K1.
  • the number of indoor units connected to the outdoor unit 10B may be three or less or five or more.
  • Fig. 13 is a sectional view of the outdoor unit 10B including the propeller fan UB1.
  • the propeller fan UB1 is provided in the vicinity of the upper end of a housing 11 of the outdoor unit 10B.
  • the outdoor heat exchanger 2 and an electric component box 13 are installed in a space on the upstream side (suction side) of the air flow of the propeller 3.
  • the propeller fan UB1 includes the propeller 3 (outdoor fan) and a bell mouth 8B.
  • the fan motor 31 is installed in the boss portion 33 of the propeller 3.
  • the fan motor 31 is fixed to a motor clamp 14 such that the motor shaft 31a is in the vertical direction. Note that the configuration of the propeller 3 is similar to that of the first embodiment (see Fig. 2 ), and therefore, detailed description thereof will be omitted.
  • the bell mouth 8B is provided on the outer peripheral side (outside in the radial direction) of the propeller 3. As shown in Fig. 13 , the bell mouth 8B includes a curved portion 81B and the enlarged-diameter portion 82.
  • the curved portion 81B has a thin cylindrical shape, and is curved in a predetermined manner such that the diameter thereof decreases toward the downstream side (blowing side) of the air flow.
  • the enlarged-diameter portion 82 has a side surface shape of a truncated cone, and is continuous with the downstream side (blowing side) of the curved portion 81B.
  • W5 As the propeller 3 rotates, air is blown upward through the bell mouth 8B. Specifically, as indicated by arrows W5, W6, air having an inward velocity component in the radial direction flows into the propeller 3 diagonally from below.
  • the seventh embodiment it is possible to ensure the rate of increase in static pressure and the air volume while reducing the propeller 3 in thickness.
  • the dimension of the outdoor unit 10B in the height direction thereof can be shortened.
  • the outdoor heat exchanger 2 is relatively apart from the propeller 3, but on the other hand, the distance between a wall of the housing 11 in the vicinity of the upper end thereof and the bell mouth 8B is relatively short.
  • the propeller 3 since the propeller 3 has, between the blade leading edge tip 321 and the first position ⁇ , a recessed shape in which the leading edge portion 32a is curved toward the blowing side, the flow of air can be along the blade 32. With this configuration, the rate of increase in static pressure and the air volume can be ensured. Moreover, it is possible to suppress a decrease in the efficiency while reducing the propeller 3 in thickness.
  • the present invention is not limited to such description, and various changes can be made.
  • the configuration of the enlarged-diameter portion 82 included in the bell mouth 8 (see Fig. 2 )
  • the diameter of the enlarged-diameter portion 82 linearly and monotonously increases toward the downstream side (blowing side) of the air flow in the axial direction.
  • the present invention is not limited to this configuration.
  • the bell mouth 8 may have configurations as shown in Figs. 14A to 14C described below.
  • Fig. 14A is a sectional view of a propeller fan UC1 according to a first modification. Note that in Fig. 14A , the fan motor 31 of the propeller 3 is not shown. In the modification of Fig. 14A , the diameter of an enlarged-diameter portion 82C of a bell mouth 8C increases in a stepwise manner toward the downstream side (blowing side) of the air flow in the axial direction. Also in such a configuration, since the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side, the flow of air blown from the propeller 3 can be along the bell mouth 8C. Thus, the pressure loss of air in the propeller fan UC1 can be reduced, and a high efficiency can be achieved.
  • Fig. 14B is a sectional view of a propeller fan UD1 according to a second modification.
  • the diameter of an enlarged-diameter portion 82D of a bell mouth 8D monotonously increases toward the downstream side (blowing side) of the air flow in the axial direction, and the enlarged-diameter portion 82D has a shape raised inward in the radial direction.
  • the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side, the flow of air blown from the propeller 3 can be along the bell mouth 8D.
  • Fig. 14C is a sectional view of a propeller fan UE1 according to a third modification.
  • the diameter of an enlarged-diameter portion 82E of a bell mouth 8E monotonously increases toward the downstream side (blowing side) of the air flow in the axial direction, and the enlarged-diameter portion 82E has a shape raised outward in the radial direction.
  • the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side, the flow of air blown from the propeller 3 can be along the bell mouth 8E.
  • the configuration in which the second position ⁇ is provided between the first position ⁇ (see Fig. 2 ) and the third position ⁇ (see Fig. 2 ) in the span direction has been described, but the present invention is not limited thereto.
  • the second position ⁇ may be provided closer to the blade root side than the first position ⁇ in the span direction. Also with such a configuration, effects similar to those of the first embodiment are obtained.
  • the configuration in which the first position ⁇ is provided at the first intermediate portion 325 (see Fig. 6A ) between the blade leading edge tip 321 (see Fig. 2 ) and the blade leading edge root 323 (see Fig. 2 ) has been described, but the present invention is not limited thereto. That is, the first position ⁇ may be provided closer to the blade tip side or the blade root side with respect to the first intermediate portion 325.
  • the configuration in which the second position ⁇ is provided at the second intermediate portion 326 (see Fig. 6C ) between the blade trailing edge tip 322 (see Fig. 2 ) and the blade trailing edge root 324 (see Fig. 2 ) has been described, but the present invention is not limited thereto. That is, the second position ⁇ may be provided closer to the blade tip side or the blade root side with respect to the second intermediate portion 326. Note that the same applies to the second to seventh embodiments.
  • the configuration in which the blade leading edge tip 321 (see Fig. 2 ) is positioned closer to the blowing side than the first position ⁇ . That is, the blade leading edge tip 321 and the first position ⁇ may be substantially at the same position in the axial position, or the blade leading edge tip 321 may be positioned closer to the suction side than the first position ⁇ . Also with such a configuration, effects similar to those of each embodiment are obtained.
  • leading edge portion 32a has the shape raised toward the suction side in the area from the blade leading edge root 323 to the first position ⁇
  • the present invention is not limited thereto.
  • the leading edge portion 32a may have a shape changing from a shape raised toward the blowing side to a shape raised toward the suction side through a predetermined inflection point (not shown) from the blade leading edge root 323 to the first position ⁇ .
  • the propeller fan U1 and the like described in each embodiment can also be applied to various types of air-conditioners such as a packaged air-conditioner and a building multi-type air-conditioner in addition to a room air-conditioner. Moreover, the propeller fan U1 and the like described in each embodiment can also be applied to various devices other than the air-conditioner.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

Provided is a low-noise and high-efficiency propeller fan of which the thickness can be reduced. A propeller fan U1 includes a propeller (3) having a boss portion (33) and a plurality of blades (32), and a bell mouth (8) provided on the outer peripheral side of the propeller (3). A first position (a) closest to a suction side in a leading edge portion (32a) of each blade (32) is provided between a blade leading edge tip (321) and a blade leading edge root (323). A leading edge portion (32a) has, between the blade leading edge tip (321) and the first position (a), a recessed shape curved toward a blowing side. A trailing edge portion (32b) of each blade (32) has a raised shape curved toward the blowing side.

Description

    TECHNICAL FIELD
  • The present invention relates to a propeller fan and the like.
    • BACKGROUND ART
  • As a technique of reducing a propeller in thickness (shortening a dimension in an axial direction), for example, a technique described in Patent Literature 1 has been known. That is, Patent Literature 1 describes an axial fan configured such that a sectional shape along a blade rotation direction is formed alternately with three or more bulging portions bulging toward a blade suction surface side and three or more bulging portions bulging toward a blade pressure surface side.
    • CITATION LIST PATENT LITERATURE
  • PATENT LITERATURE 1: JP-A-2010-150945
    • SUMMARY OF INVENTION PROBLEMS TO BE SOLVED BY INVENTION
  • However, in the technique described in Patent Literature 1, there is a possibility that separation of an air flow occurs on the suction surface side of the bulging portion bulging toward the pressure surface side. When pressure fluctuation due to such separation of the air flow occurs, aerodynamic noise increases. For this reason, the technique described in Patent Literature 1 has room for improvement in noise reduction.
  • In addition, for example, when a chord length or an attachment angle at a blade tip portion is decreased in order to reduce the propeller in thickness, not only the rate of increase in static pressure (also referred to as a static pressure increase) but also an air volume are reduced. In this case, if the rotation speed of the propeller is increased in order to ensure the rate of increase in static pressure and the air volume, noise may increase.
  • Thus, the present invention is intended to provide, e.g., a low-noise and high-efficiency propeller fan of which the thickness can be reduced.
    • SOLUTION TO PROBLEMS
  • In order to solve the above-described problems, the present invention provides a propeller fan including a propeller including a boss portion rotating integrally with a motor shaft and a plurality of blades installed in the boss portion, and a bell mouth provided on the outer peripheral side of the propeller, a first position closest to a suction side at a leading edge portion of each blade being provided between a blade leading edge tip and a blade leading edge root, the leading edge portion having, between the blade leading edge tip and the first position, a recessed shape curved toward a blowing side, and a trailing edge portion of each blade having a raised shape curved toward the blowing side.
    • EFFECTS OF INVENTION
  • According to the present invention, it is possible to provide, e.g., the low-noise and high-efficiency propeller fan of which the thickness can be reduced.
    • BRIEF DESCRIPTION OF DRAWINGS
    • Fig. 1 is a configuration diagram including a refrigerant circuit of an air-conditioner including a propeller fan according to a first embodiment;
    • Fig. 2 is a sectional view of an outdoor unit including the propeller fan according to the first embodiment;
    • Fig. 3 is a perspective view of a propeller included in the propeller fan according to the first embodiment;
    • Fig. 4 is a view of the propeller included in the propeller fan according to the first embodiment from an air suction side in the direction of the center axis of the propeller.
    • Fig. 5A is a sectional view of a blade taken along a cylindrical plane including an arc A-A in Fig. 4;
    • Fig. 5B is a sectional view of the blade taken along a cylindrical plane including an arc B-B in Fig. 4;
    • Fig. 5C is a sectional view of the blade taken along a cylindrical plane including an arc C-C in Fig. 4;
    • Fig. 6A is a sectional view of the blade taken along a span line D-D in Fig. 4;
    • Fig. 6B is a sectional view of the blade taken along a span line E-E in Fig. 4;
    • Fig. 6C is a sectional view of the blade taken along a span line F-F in Fig. 4;
    • Fig. 7 is a sectional view of an outdoor unit including a propeller fan according to a second embodiment;
    • Fig. 8 is a graph for describing the attachment angle of a blade section in a propeller fan according to a third embodiment;
    • Fig. 9 is a graph for describing the attachment angle of a blade section in a propeller fan according to a fourth embodiment;
    • Fig. 10 is a graph for describing a chord length in a propeller fan according to a fifth embodiment;
    • Fig. 11 is a graph for describing a chord length in a propeller fan according to a sixth embodiment;
    • Fig. 12 is a configuration diagram of an air-conditioner including a propeller fan according to a seventh embodiment;
    • Fig. 13 is a sectional view of an outdoor unit including the propeller fan according to the seventh embodiment;
    • Fig. 14A is a sectional view of a propeller fan according to a first modification;
    • Fig. 14B is a sectional view of a propeller fan according to a second modification;
    • Fig. 14C is a sectional view of a propeller fan according to a third modification;
    • Fig. 15 is a sectional view of a blade of a general propeller taken along a predetermined cylindrical plane;
    • Fig. 16 is a sectional view of an outdoor unit including a propeller according to a comparative example; and
    • Fig. 17 is a perspective view of the propeller according to the comparative example.
    DESCRIPTION OF EMBODIMENTS < <First Embodiment> > <Configuration of Air-Conditioner>
  • Fig. 1 is a configuration diagram including a refrigerant circuit Q of an air-conditioner 100 including a propeller fan according to a first embodiment. Note that solid arrows in Fig. 1 indicate the flow of refrigerant in heating operation. On the other hand, dashed arrows in Fig. 1 indicate the flow of refrigerant in cooling operation. The air-conditioner 100 is a device that performs air-conditioning such as the heating operation or the cooling operation. As shown in Fig. 1, the air-conditioner 100 includes a compressor 1, an outdoor heat exchanger 2, a propeller 3 (outdoor fan), and an expansion valve 4. Further, the air-conditioner 100 further includes an indoor heat exchanger 5, an indoor fan 6, and a four-way valve 7 in addition to the above-described configuration.
  • The compressor 1 is a device that compresses low-temperature low-pressure gas refrigerant and discharges high-temperature high-pressure gas refrigerant. As such a compressor 1, for example, a scroll compressor or a rotary compressor is used. The outdoor heat exchanger 2 is a heat exchanger in which heat is exchanged between refrigerant flowing in a heat transfer pipe (not shown) thereof and external air sent from the propeller 3.
  • The propeller 3 (outdoor fan) is an axial fan that sends external air to the outdoor heat exchanger 2. The propeller 3 includes a fan motor 31 as a drive source, and is installed in the vicinity of the outdoor heat exchanger 2. The expansion valve 4 is a valve that decompresses refrigerant condensed in a "condenser" (one of the outdoor heat exchanger 2 or the indoor heat exchanger 5). Note that the refrigerant decompressed by the expansion valve 4 is guided to an "evaporator" (the other one of the outdoor heat exchanger 2 or the indoor heat exchanger 5).
  • The indoor heat exchanger 5 is a heat exchanger in which heat is exchanged between refrigerant flowing in a heat transfer pipe (not shown) thereof and room air (air in an air-conditioning room) sent from the indoor fan 6. The indoor fan 6 is a fan that sends room air to the indoor heat exchanger 5. The indoor fan 6 includes an indoor fan motor 61 as a drive source, and is installed in the vicinity of the indoor heat exchanger 5. As such an indoor fan 6, for example, a cross flow fan is used.
  • The four-way valve 7 is a valve that switches the flow path of refrigerant according to the operation mode of the air-conditioner 100. For example, in the cooling operation (see the dashed arrows in Fig. 1), refrigerant circulates sequentially through the compressor 1, the outdoor heat exchanger 2 (condenser), the expansion valve 4, and the indoor heat exchanger 5 (evaporator) in the refrigerant circuit Q. On the other hand, in the heating operation (see the solid arrows in Fig. 1), refrigerant circulates sequentially through the compressor 1, the indoor heat exchanger 5 (condenser), the expansion valve 4, and the outdoor heat exchanger 2 (evaporator) in the refrigerant circuit Q.
  • Note that in the example of Fig. 1, the compressor 1, the outdoor heat exchanger 2, the propeller 3 (outdoor fan), the expansion valve 4, and the four-way valve 7 are installed in an outdoor unit 10. On the other hand, the indoor heat exchanger 5 and the indoor fan 6 are installed in an indoor unit 20. In addition to the compressor 1 and the propeller 3, devices such as the expansion valve 4, the indoor fan 6, and the four-way valve 7 are controlled by a control device (not shown) in a predetermined manner.
  • Fig. 2 is a sectional view of the outdoor unit 10 including a propeller fan U1. Note that Fig. 2 shows a schematic section of the side blowing outdoor unit 10 taken along a predetermined horizontal plane including the center axis Y of the propeller 3. In addition, Fig. 2 also shows the meridian plane of a blade 32 of the propeller 3 (also see Fig. 3). Here, the "meridian plane" of the blade 32 is obtained by rotationally projecting the shape of the blade 32 in a predetermined manner with reference to the center axis Y of the propeller 3. In Fig. 2, the flow of air is indicated by white thick arrows.
  • As shown in Fig. 2, the propeller fan U1 includes the propeller 3 and a bell mouth 8, and is installed inside the outdoor unit 10. The propeller 3 is an axial fan that sends air substantially in an axial direction. The propeller 3 includes the fan motor 31 as the drive source, a boss portion 33 having a circular columnar outer shape and rotating integrally with a motor shaft 31a of the fan motor 31, and three blades 32 (see also Fig. 3) installed on a peripheral wall of the boss portion 33. In the example of Fig. 2, the propeller fan U1 is installed such that the direction of the center axis Y (the axial direction of the motor shaft 31a) is parallel with the front-back direction of the outdoor unit 10.
  • The bell mouth 8 is a rectifying member that guides air sucked into the propeller 3 in a predetermined manner and guides air blown from the propeller 3 in a predetermined manner. The bell mouth 8 has a cylindrical shape, and is provided on the outer peripheral side (outside in the radial direction) of the propeller 3. Note that the center axis of the bell mouth 8 substantially coincides with the center axis Y of the propeller 3.
  • As shown in Fig. 2, the bell mouth 8 includes a curved portion 81 and an enlarged-diameter portion 82. The curved portion 81 has a thin cylindrical shape, and is curved in a predetermined manner such that the diameter thereof decreases toward the downstream side (blowing side) of the air flow. The enlarged-diameter portion 82 has a side surface shape of a truncated cone, and is continuous with the downstream side (blowing side) of the curved portion 81. The enlarged-diameter portion 82 is formed such that the diameter thereof increases toward the downstream side (blowing side) of the air flow.
  • In the example of Fig. 2, the outdoor heat exchanger 2 having an L shape in a cross-sectional view is provided on the back and left sides of the outdoor unit 10. Of the outdoor heat exchanger 2, a portion on the back side of the outdoor unit 10 is positioned on the upstream side of the propeller 3 in an air flow direction. Air subjected to heat exchange in the outdoor heat exchanger 2 is sucked into the propeller 3 while being rectified by the bell mouth 8, and is blown from the propeller 3 in a predetermined manner.
  • A machine room R1 shown in Fig. 2 is a space where the compressor 1 (see Fig. 1), an accumulator (not shown), the expansion valve 4 (see Fig. 1) and the like are housed, and is provided on the right side of the propeller fan U1. Note that a fan chamber R2 where the propeller fan U1 is housed and the machine room R1 are partitioned in a predetermined manner by a partition plate (not shown). In addition to a blade leading edge tip 321, a blade trailing edge tip 322, a blade leading edge root 323, and a blade trailing edge root 324 of the blade 32 shown in Fig. 2, a first position α, a second position β, and a third position γ will be described later.
  • Fig. 3 is a perspective view of the propeller 3 included in the propeller fan. Note that a hatched thick arrow shown in Fig. 3 and the like indicates the direction in which the propeller 3 rotates. Note that a thick white arrow shown in Fig. 3 and the like indicates the direction in which air flows in association with rotation of the propeller 3. The three blades 32 shown in Fig. 3 are provided at equal angular intervals on the peripheral wall of the boss portion 33, and radially extend substantially in the radial direction from the boss portion 33. More specifically, each of the three blades 32 extends so as to be inclined forward in the rotation direction with respect to the radial direction about the center axis Y (also see Fig. 4). Note that the number of blades 32 may be two or four or more other than the three blades shown in Fig. 3.
  • Fig. 4 is a view of the propeller 3 from an air suction side in the direction of the center axis Y of the propeller 3. As shown in Fig. 4, each of the plurality of blades 32 includes a leading edge portion 32a, a trailing edge portion 32b, a blade tip portion 32c, and a blade root portion 32d. The leading edge portion 32a is an edge portion of the blade 32 positioned on the front side in the rotation direction of the propeller 3. The trailing edge portion 32b is an edge portion of the blade 32 positioned on the back side in the rotation direction of the propeller 3. The blade tip portion 32c is an outer peripheral side edge portion of the blade 32. The blade root portion 32d is an inner peripheral side edge portion of the blade 32.
  • As shown in Fig. 4, the blade tip portion 32c and the leading edge portion 32a are adjacent to each other through the blade leading edge tip 321. The blade tip portion 32c and the trailing edge portion 32b are adjacent to each other through the blade trailing edge tip 322. The blade root portion 32d and the leading edge portion 32a are adjacent to each other through the blade leading edge root 323. The blade root portion 32d and the trailing edge portion 32b are adjacent to each other through the blade trailing edge root 324. Note that the blade leading edge tip 321, the blade trailing edge tip 322, the blade leading edge root 323, and the blade trailing edge root 324 are also shown on the meridian plane of the propeller 3 in Fig. 2.
  • As shown in Fig. 4, when the propeller 3 is viewed from the air suction side, the leading edge portion 32a has a recessed shape so as to curve toward the back side in the rotation direction. On the other hand, the trailing edge portion 32b has a raised shape so as to curve toward the back side in the rotation direction. The blade tip portion 32c has an arc shape so as to form a predetermined clearance with the inner peripheral surface of the bell mouth 8 (see Fig. 2). The blade root portion 32d is formed in an arc shape along the outer peripheral surface of boss portion 33.
  • Each blade 32 includes a pressure surface 32e (see Fig. 3) and a suction surface 32f. The pressure surface 32e is a surface on the front side (blowing side, far side of the plane of paper of Fig. 4) in the direction of the center axis Y among two surfaces of the blade 32. When the propeller 3 is rotating, air is pushed out by the pressure surface 32e in a predetermined manner as the blades 32 move.
  • The suction surface 32f is a surface on the back side (suction side, near side of the plane of paper of Fig. 4) in the direction of the center axis Y among the two surfaces of the blade 32. That is, the suction surface 32f is a back-side surface of the pressure surface 32e (see Fig. 3). When the propeller 3 is rotating, air is sucked toward the suction surface 32f in association with movement of the blades 32. Note that since Fig. 4 is a view of the propeller 3 from the suction side, the suction surface 32f f is visible, but the pressure surface 32e on the back side (see Fig. 3) is not visible.
  • Fig. 5A is a sectional view of the blade 32 taken along a cylindrical plane including an arc A-A in Fig. 4. Note that the arc A-A indicated by a dashed line in Fig. 4 is a virtual arc passing through the vicinity of the blade tip portion 32c about the center axis Y of the propeller 3 (the center of the arc). Moreover, each arrow in the vicinity of reference numerals such as the arc A-A in Fig. 4 indicates a direction when the blade 32 is viewed in section. A hatched thick arrow shown in Fig. 5A and the like indicates the direction in which the blade 32 moves in association with rotation of the propeller 3. Moreover, a thick white arrow shown in Fig. 5A and the like indicates the direction in which air flows in association with rotation of the propeller 3.
  • The vicinity of the blade tip portion 32c (see Fig. 4) is inclined in a predetermined manner so as to be positioned on the air suction side (upper side in the plan of paper of Fig. 5A) while extending forward (right side in the plan of paper of Fig. 5A) in the rotation direction of the propeller 3, as shown in Fig. 5A.
  • Fig. 5B is a sectional view of the blade 32 taken along a cylindrical plane including an arc B-B in Fig. 4. Note that the arc B-B indicated by a dashed line in Fig. 4 is a virtual arc passing through an intermediate portion between the blade tip portion 32c and the blade root portion 32d about the center axis Y of the propeller 3 (the center of the arc). That is, the distance from the center axis Y to the arc B-B shown in Fig. 4 is a value obtained by dividing the sum of the distance from the center axis Y to the blade tip portion 32c and the distance from the center axis Y to the blade root portion 32d by 2. As shown in Fig. 5B, the intermediate portion of the blade 32 is also inclined in a predetermined manner so as to be positioned on the air suction side (upper side in the plan of paper of Fig. 5B) while extending forward (right side in the plan of paper of Fig. 5B) in the rotation direction of the propeller 3.
  • Fig. 5C is a sectional view of the blade 32 taken along a cylindrical plane including an arc C-C in Fig. 4. Note that the arc C-C indicated by a dashed line in Fig. 4 is a virtual arc passing through the vicinity of the blade root portion 32d about the center axis Y of the propeller 3 (the center of the arc). The vicinity of the blade root portion 32d (see Fig. 4) is also inclined in a predetermined manner so as to be positioned on the air suction side (upper side in the plan of paper of Fig. 5C) while extending forward (right side in the plan of paper of Fig. 5C) in the rotation direction of the propeller 3, as shown in Fig. 5C.
  • As shown in Figs. 5A, 5B, and 5C, the closer to the blade root portion 32d (see Fig. 4) in the radial direction, the shorter the circumferential length of the blade 32. In addition to the vicinity of the blade tip portion 32c (see Fig. 5A) and the intermediate portion (see Fig. 5B), the blade 32 is curved in a gently-raised shape as viewed from the air suction side in the vicinity of the blade root portion 32d (see Fig. 5C). With this configuration, the pressure of air is easily increased by the pressure surface 32e of the blade 32.
  • Fig. 6A is a sectional view of the blade 32 taken along a span line D-D in Fig. 4. Here, the "span line" is a line connecting points, at which a ratio between the distance from the leading edge portion 32a (see Fig. 4) to the distance from the trailing edge portion 32b (see Fig. 4) is constant, from the blade tip portion 32c (see Fig. 4) to the blade root portion 32d (see Fig. 4) in each of a plurality of cylindrical sections with respect to (about) the center axis Y (see Fig. 4). Note that the distance from the leading edge portion 32a to the span line D-D and the distance from the trailing edge portion 32b to the span line D-D are measured in a predetermined manner along the warp line of the blade 32. A direction along the span line will be referred to as a "span direction."
  • The span line D-D (corresponding to the section of Fig. 6A) shown in Fig. 4 is a span line passing the vicinity of the leading edge portion 32a of the blade 32. Note that the leading edge portion 32a (see Fig. 2) of the blade 32 also has a shape similar to that of Fig. 6A. Thus, for the sake of easy understanding of description, reference numerals of the blade leading edge tip 321, the blade leading edge root 323 and the like are also shown in Fig. 6A showing the section in the span direction in the vicinity of the leading edge portion 32a.
  • The section of the vicinity of the leading edge portion 32a (see Fig. 4) taken along the span line D-D has an inverted S shape as shown in Fig. 6A. As shown in Fig. 2, the leading edge portion 32a also has a similar inverted S-shape. As shown in Fig. 2, the first position α closest to the suction side at the leading edge portion 32a of the blade 32 is provided between the blade leading edge tip 321 and the blade leading edge root 323. Between the blade leading edge tip 321 and the first position α, the leading edge portion 32a has a recessed shape curved toward the blowing side. Here, the "recessed shape" curved toward the blowing side refers to such a shape that a portion of the leading edge portion 32a closer to the third position γ between the blade leading edge tip 321 and the first position α is positioned closer to the blowing side.
  • According to this configuration, even in a case where diagonally-directed air (see arrows W1, W2 in Fig. 2) having a radially inward velocity component flows into the blade 32, the recessed portion is provided between the blade leading edge tip 321 and the first position α so that the air can flow along the blade 32. Thus, separation of the air flow from the blade 32 can be reduced, and a high efficiency can be achieved. Such a configuration is particularly suitable for the side blowing outdoor unit 10 in which air easily flows in diagonally with respect to the blade 32 due to influence of the outdoor heat exchanger 2 and the machine room R1 provided on the side of the propeller 3.
  • In the example of Fig. 2, in the direction of the center axis Y of the propeller 3, the blade leading edge tip 321 is positioned on the blowing side with respect to the first position α. According to such a configuration, the propeller height HP (dimension in the axial direction) of the propeller 3 is shorter than that when the blade leading edge tip 321 is positioned on the suction side with respect to the first position α. Thus, the propeller 3 can be reduced in thickness.
  • Fig. 6B is a sectional view of the blade 32 taken along a span line E-E in Fig. 4. Note that a span line E-E in Fig. 4 is a span line passing through an intermediate position in the circumferential direction between the leading edge portion 32a and the trailing edge portion 32b. The section along the span line E-E also has an inverted S-shape as in Fig. 6A, but the degree of curvature of the inverted S-shape is gentler than that of the section (see Fig. 6A) along the span line D-D (see Fig. 4). That is, the degree of curvature of the inverted S-shape gradually decreases from the leading edge portion 32a (see Fig. 2) toward the intermediate position (see Fig. 6B) in the span direction.
  • Fig. 6C is a sectional view of the blade 32 taken along a span line F-F in Fig. 4. Note that the span line F-F in Fig. 4 is a span line passing the vicinity of the trailing edge portion 32b of the blade 32. As shown in Fig. 2, the trailing edge portion 32b also has a shape similar to that of Fig. 6C. Thus, for the sake of easy understanding of description, reference numerals of the blade trailing edge tip 322, the blade trailing edge root 324 and the like are also shown in Fig. 6C showing the section in the span direction in the vicinity of the trailing edge portion 32b.
  • As shown in Fig. 2, the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side (a recessed shape when viewed from the suction side.). Specifically, the second position β positioned closest to the blowing side at the trailing edge portion 32b is provided between the blade trailing edge tip 322 and the blade trailing edge root 324. A portion of the trailing edge portion 32b closer to the second position β is positioned closer to the blowing side.
  • According to such a configuration, air blown from the propeller 3 is pushed out diagonally by the pressure surface 32e in the region outside the second position β in the radial direction so as to include the velocity component outward in the radial direction (see arrows W3, W4 in Fig. 2). As a result, the air blown from the propeller 3 flows along the enlarged-diameter portion 82 of the bell mouth 8. Thus, it is possible to reduce the pressure loss of air in the bell mouth 8 and to suppress a decrease in the rate of increase in static pressure.
  • Note that the degree of curvature of the blade 32 toward the blowing side gradually increases from the intermediate position in Fig. 6B toward the trailing edge portion 32b (see Fig. 2) in the span direction. The entire trailing edge portion 32b is curved in a raised shape toward the blowing side.
  • In the span direction along the leading edge portion 32a in Fig. 2, the first position α is preferably provided at a first intermediate portion 325 (see Fig. 6A) between the blade leading edge tip 321 and the blade leading edge root 323. Further, in the span direction along the trailing edge portion 32b in Fig. 2, the second position β is preferably provided at a second intermediate portion 326 (see Fig. 6C) between the blade trailing edge tip 322 and the blade trailing edge root 324. As the first intermediate portion 325 described above, for example, an intermediate portion in a case where the leading edge portion 32a is divided into three equal portions in the span direction, i.e., the blade tip side, the intermediate portion, and the blade root side. Similarly, for the second intermediate portion 326, an intermediate portion obtained by dividing the trailing edge portion 32b into three equal portions in the span direction may be used.
  • According to such a configuration, an area between the first position α and the blade leading edge tip 321 can be sufficiently ensured in the span direction.
    Accordingly, the diagonal flow of air having an inward velocity component in the radial direction is easily along the blade 32. In addition, the length between the first position α and the second position β is easily ensured in the axial direction of the propeller 3. As a result, it is possible to suppress a decrease in the rate of increase in static pressure and in air volume while reducing the propeller 3 in thickness.
  • Note that in the example of Fig. 2, the distance in the radial direction from the center axis Y of the propeller 3 to the second position β is longer than the distance in the radial direction from the center axis Y to the first position α, but the magnitude relationship between these distances may be reversed. Next, the definitions of "chord length" and "attachment angle" will be briefly described with reference to Fig. 15.
  • Fig. 15 is a sectional view of a blade 34 of a general propeller taken along a predetermined cylindrical plane. A chord length L shown in Fig. 15 is the length of a chord line S. The chord line S is a line segment connecting a leading edge 34a and a trailing edge 34b in the blade section of the blade 34. An attachment angle ξ is an angle between\ the chord line S and a rotation plane X. Note that it is assumed that the rotation plane X is perpendicular to the center axis (not shown) of the propeller.
  • The longer the chord length L shown in Fig. 15, the greater the rate of increase in static pressure and the greater the air volume. Moreover, the greater the attachment angle ξ, the greater the rate of increase in static pressure and the greater the air volume. Thus, the chord length L and the attachment angle ξ are important design values for ensuring the rate of increase in static pressure and the air volume.
  • Fig. 16 is a sectional view of an outdoor unit 10G including a propeller 3G according to a comparative example. Note that Fig. 16 shows the meridian plane of a blade 32G of the propeller 3G (also see Fig. 17). In the comparative example of Fig. 16, a leading edge portion 32Ga is positioned closer to the suction side toward a blade leading edge tip 321G. On the other hand, a trailing edge portion 32Gb is positioned closer to the blowing side toward a blade trailing edge tip 322G. The propeller 3G is formed such that the chord length L (see Fig. 15) and the attachment angle ξ (see Fig. 15) are maximized at a blade tip portion 32Gc. In such a configuration, the propeller height HP is determined by the chord length L and the attachment angle ξ at the blade tip portion 32Gc.
  • Fig. 17 is a perspective view of the propeller 3G according to the comparative example. Note that the propeller 3G shown in Fig. 17 corresponds to the configuration of Fig. 16. In order to shorten the propeller height HP (see Fig. 16) in the conventional design of the propeller 3G, a method of decreasing the chord length L (see Fig. 15) at the blade tip portion 32Gc or decreasing the attachment angle ξ (see Fig. 15) has been adopted. However, in such a design, not only the rate of increase in static pressure of the propeller 3G decreases, but also the air volume decreases. In addition, if the rotation speed of the propeller 3G is increased in order to compensate for a decrease in the rate of increase in static pressure and in the air volume, noise may increase.
  • On the other hand, in the first embodiment, the leading edge portion 32a has the recessed shape curved toward the blowing side between the blade leading edge tip 321 and the first position α as shown in Fig. 2. The trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side. With such a configuration, the propeller height HP (see Fig. 2) is determined by the first position α and the second position β in the axial direction. Specifically, the distance in the axial direction between the first position α and the second position β is the propeller height HP.
  • As described above, in the first embodiment, the first position α and the second position β which define the propeller height HP are at predetermined positions (for example, in the vicinity of the intermediate portion in the span direction) between the blade tip portion 32c and the blade root portion 32d. With this configuration, the chord length L (see Fig. 15) and the attachment angle ξ (see Fig. 15) can be relatively great in the vicinity of the first position α and the second position β.
    • <Effects>
  • According to the first embodiment, as shown in Fig. 2, the propeller height HP is determined by the first position α at the leading edge portion 32a of the blade 32 and the second position β at the trailing edge portion 32b of the blade 32. Thus, by adjusting the first position α and the second position β at the design stage of the propeller 3 as necessary, it is possible to sufficiently ensure the rate of increase in static pressure and the air volume while reducing the propeller 3 in thickness. In addition, by reducing the propeller 3 in thickness, the length of the side blowing outdoor unit 10 in the front-back direction can be shortened.
  • Between the blade leading edge tip 321 and the first position α, the leading edge portion 32a has the recessed shape on the blowing side. With this configuration, even in a case where the outdoor heat exchanger 2 and the machine room R1 are provided at positions relatively close to the propeller fan U1 in the lateral direction, air in the diagonal direction (see the arrows W1, W2 in Fig. 2) flows along the blades 32. That is, the flow of air having the inward velocity component in the radial direction is easily induced from the outer peripheral side of the propeller 3. As a result, separation of air from the blade 32 can be reduced, and therefore, the rate of increase in static pressure and the air volume can be ensured.
  • In addition, as shown in Fig. 2, since the trailing edge portion 32b of the blade 32 has the raised shape on the blowing side, air blown from the propeller 3 is guided in the diagonal direction so as to include the outward velocity component in the radial direction (see the arrows W3, W4 in Fig. 2), and further flows along the enlarged-diameter portion 82 of the bell mouth 8. Thus, it is possible to reduce the pressure loss of air in the bell mouth 8 and to enhance the efficiency. The trailing edge portion 32b of the blade 32 has no recessed portion as viewed from the blowing side, and therefore, almost no separation of the air flow occurs on the suction surface 32f (see Fig. 3) of the blade 32. Thus, it is possible to suppress a decrease in the rate of increase in static pressure.
  • For example, even in a case where the propeller height HP of the propeller 3 in the first embodiment is reduced by 26% as compared to the comparative example of Figs. 16 and 17, such a result that the efficiency of the propeller 3 is equivalent to that of the comparative example in addition to the rate of increase in static pressure and the air volume is obtained. As described above, according to the first embodiment, it is possible to provide, e.g., the low-noise and high-efficiency propeller fan U1 of which the thickness can be reduced.
    • <<Second Embodiment>>
  • A second embodiment is different from the first embodiment in that a distance RD in the radial direction from the center axis Y of a propeller 3A (see Fig. 7) to the first position α is equal to a distance RD in the radial direction from the center axis Y to the second position β. Note that other configurations are the same as those of the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 7 is a sectional view of an outdoor unit 10A including a propeller fan UA1 according to the second embodiment. Note that Fig. 7 shows the meridian plane of a blade 32A of the propeller 3A. In the example of Fig. 7, the distance RD in the radial direction from the center axis Y of the propeller 3A to the first position α is equal to the distance RD in the radial direction from the center axis Y to the second position β. According to such a configuration, the first position α and the second position β can be appropriately adjusted at a design stage based on one blade section (section of the blade 32A taken along a predetermined cylindrical plane) including the first position α and the second position β. Thus, since the propeller 3A can be easily designed, a work load at the design stage can be reduced.
    • <Effects>
  • According to the second embodiment, since the first position α and the second position β can be appropriately adjusted at the design stage in the predetermined blade section (one blade section) of the propeller 3A taken along the predetermined cylindrical plane, the propeller 3A can be easily designed.
    • < <Third Embodiment> >
  • A third embodiment is different from the first embodiment in that the attachment angle of a blade section is maximized at the first position α (see Fig. 2), but is otherwise similar to the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 8 is a graph for describing the attachment angle ξ of the blade section in a propeller fan according to the third embodiment. Note that the horizontal axis in Fig. 8 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2). In addition, the vertical axis in Fig. 8 represents the attachment angle ξ of the blade section corresponding to each radius. Note that the "blade section" is the section of the blade 32 taken along a predetermined cylindrical plane.
  • A value "0" on the horizontal axis in Fig. 8 indicates the radius of the boss portion 33 (see Fig. 2). On the other hand, a value "1" on the horizontal axis in Fig. 8 indicates the radius of the blade tip portion 32c (see Fig. 2). A solid line in Fig. 8 indicates the attachment angle ξ of the blade section at each radius in the propeller 3 according to the third embodiment. On the other hand, a chain line in Fig. 8 indicates the attachment angle ξ of the blade section at each radius in the propeller 3G according to the comparative example (see Figs. 16 and 17).
  • As shown in Fig. 8, in the comparative example (chain line in Fig. 8), the attachment angle ξ decreases toward the blade tip portion ("1" on the horizontal axis). On the other hand, in the third embodiment (solid line in Fig. 8), as indicated by a point Pα, the attachment angle ξ of the blade section is maximized at a radius Rα at the first position α (see Fig. 2). With this configuration, the degree of the attachment angle ξ can be sufficiently ensured in the vicinity of the first position α, and therefore, the rate of increase in static pressure and the air volume can be increased. Note that although the second position β (see Fig. 2) is not particularly shown in Fig. 8, the second position β may be provided on either the blade tip side or the blade root side with respect to the first position α.
    • <Effects>
  • According to the third embodiment, since the attachment angle ξ of the blade section is maximized at the first position α (see Fig. 2), the amount of work by the propeller 3 in the vicinity of the first position α is relatively great. As a result, the rate of increase in static pressure and the air volume can be sufficiently ensured.
    • <<Fourth Embodiment>>
  • A fourth embodiment is different from the first embodiment in that the attachment angle of a blade section is maximized at the second position β (see Fig. 2), but is otherwise similar to the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 9 is a graph for describing the attachment angle ξ of the blade section in a propeller fan according to the fourth embodiment. Note that the horizontal axis in Fig. 9 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2), and the vertical axis represents the attachment angle ξ. As shown in Fig. 9, in the fourth embodiment (solid line in Fig. 9), as indicated by a point Pβ, the attachment angle ξ of the blade section is maximized at a radius Rβ at the second position β (see Fig. 2). With this configuration, the degree of the attachment angle ξ can be sufficiently ensured in the vicinity of the second position β, and therefore, the rate of increase in static pressure and the air volume can be increased. Note that although the first position α (see Fig. 2) is not particularly shown in Fig. 9, the first position α may be provided on either the blade tip side or the blade root side with respect to the second position β.
    • <Effects>
  • According to the fourth embodiment, since the attachment angle ξ of the blade section is maximized at the second position β (see Fig. 2), the amount of work by the propeller 3 in the vicinity of the second position β is relatively great. As a result, the rate of increase in static pressure and the air volume can be sufficiently ensured.
    • <<Fifth Embodiment>>
  • A fifth embodiment is different from the first embodiment in that a chord length is maximized at the first position α (see Fig. 2), but is otherwise similar to the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 10 is a graph for describing a chord length L in a propeller fan according to the fifth embodiment. Note that the horizontal axis in Fig. 10 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2). In addition, the vertical axis in Fig. 10 represents the chord length L of the blade section corresponding to each radius. Moreover, a solid line in Fig. 10 indicates the chord length L at each radius in the propeller 3 according to the fifth embodiment. On the other hand, a chain line in Fig. 10 indicates a chord length L at each radius in the propeller 3G according to the comparative example (see Figs. 16 and 17). As shown in Fig. 10, in the comparative example (chain line in Fig. 10), the chord length increases toward the blade tip portion ("1" on the horizontal axis).
  • On the other hand, in the fifth embodiment (solid line in Fig. 10), as indicated by a point Pα, the chord length L is maximized at a radius Rα at the first position α (see Fig. 2). With this configuration, the chord length L can be sufficiently ensured in the vicinity of the first position α, and therefore, the rate of increase in static pressure and the air volume can be increased. Note that although the second position β (see Fig. 2) is not particularly shown in Fig. 10, the second position β may be provided on either the blade tip side or the blade root side with respect to the first position α.
    • <Effects>
  • According to the fifth embodiment, since the chord length L is maximized at the first position α (see Fig. 2), the amount of work by the propeller 3 in the vicinity of the first position α is relatively great. As a result, the rate of increase in static pressure and the air volume can be sufficiently ensured.
    • <<Sixth Embodiment>>
  • A sixth embodiment is different from the first embodiment in that a chord length is maximized at the second position β (see Fig. 2), but is otherwise similar to the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 11 is a graph for describing a chord length L in a propeller fan according to the sixth embodiment. Note that the horizontal axis in Fig. 11 represents the radius R (i.e., a distance in the radial direction from the center axis Y) of the propeller 3 (see Fig. 2), and the vertical axis represents the chord length L. In the sixth embodiment (solid line in Fig. 11), as indicated by a point Pβ, the chord length L is maximized at a radius Rβ at the second position β (see Fig. 2). With this configuration, the chord length L can be sufficiently ensured in the vicinity of the second position β, and therefore, the rate of increase in static pressure and the air volume can be increased. Note that although the first position α (see Fig. 2) is not particularly shown in Fig. 11, the first position α may be provided on either the blade tip side or the blade root side with respect to the second position β.
    • <Effects>
  • According to the sixth embodiment, since the chord length L is maximized at the second position β (see Fig. 2), the amount of work by the propeller 3 in the vicinity of the second position β is relatively great. As a result, the rate of increase in static pressure and the air volume can be sufficiently ensured.
    • <<Seventh Embodiment>>
  • A seventh embodiment is different from the first embodiment in that a propeller fan UB1 (see Fig. 13) is provided in a top blowing outdoor unit 10B (see Fig. 13). Moreover, the seventh embodiment is different from the first embodiment in that an air-conditioner 100B is a multi-type air-conditioner including a plurality of indoor units 21 to 24 (see Fig. 12). Note that other configurations (e.g., the configuration of the propeller 3: see Fig. 13) are similar to those of the first embodiment. Thus, contents different from those of the first embodiment will be described and description of overlapping contents will be omitted.
  • Fig. 12 is a configuration diagram of the air-conditioner 100B including a propeller fan according to the seventh embodiment. Note that in Fig. 12, a refrigerant pipe K1 is simplified and, e.g., a refrigerant pipe for guiding refrigerant from the outdoor unit 10B to the indoor unit 21 and the like and a refrigerant pipe for guiding refrigerant from the indoor unit 21 and the like to the outdoor unit 10B are indicated by a common solid line. The multi-type air-conditioner 100B shown in Fig. 12 includes the top blowing outdoor unit 10B and the four ceiling embedded indoor units 21 to 24. Refrigerant circulates in a predetermined manner in a refrigerant circuit QB in which the indoor units 21 to 24 are connected in parallel through the refrigerant pipe K1. Note that the number of indoor units connected to the outdoor unit 10B may be three or less or five or more.
  • Fig. 13 is a sectional view of the outdoor unit 10B including the propeller fan UB1. As shown in Fig. 13, the propeller fan UB1 is provided in the vicinity of the upper end of a housing 11 of the outdoor unit 10B. In the housing 11, in addition to the compressor 1 and an accumulator 12, the outdoor heat exchanger 2 and an electric component box 13 are installed in a space on the upstream side (suction side) of the air flow of the propeller 3.
  • The propeller fan UB1 includes the propeller 3 (outdoor fan) and a bell mouth 8B. The fan motor 31 is installed in the boss portion 33 of the propeller 3. The fan motor 31 is fixed to a motor clamp 14 such that the motor shaft 31a is in the vertical direction. Note that the configuration of the propeller 3 is similar to that of the first embodiment (see Fig. 2), and therefore, detailed description thereof will be omitted.
  • The bell mouth 8B is provided on the outer peripheral side (outside in the radial direction) of the propeller 3. As shown in Fig. 13, the bell mouth 8B includes a curved portion 81B and the enlarged-diameter portion 82. The curved portion 81B has a thin cylindrical shape, and is curved in a predetermined manner such that the diameter thereof decreases toward the downstream side (blowing side) of the air flow. The enlarged-diameter portion 82 has a side surface shape of a truncated cone, and is continuous with the downstream side (blowing side) of the curved portion 81B. As the propeller 3 rotates, air is blown upward through the bell mouth 8B. Specifically, as indicated by arrows W5, W6, air having an inward velocity component in the radial direction flows into the propeller 3 diagonally from below.
    • <Effects>
  • According to the seventh embodiment, it is possible to ensure the rate of increase in static pressure and the air volume while reducing the propeller 3 in thickness. In addition, by reducing the propeller 3 in thickness, the dimension of the outdoor unit 10B in the height direction thereof can be shortened. In the example of Fig. 13, the outdoor heat exchanger 2 is relatively apart from the propeller 3, but on the other hand, the distance between a wall of the housing 11 in the vicinity of the upper end thereof and the bell mouth 8B is relatively short. Here, since the propeller 3 has, between the blade leading edge tip 321 and the first position α, a recessed shape in which the leading edge portion 32a is curved toward the blowing side, the flow of air can be along the blade 32. With this configuration, the rate of increase in static pressure and the air volume can be ensured. Moreover, it is possible to suppress a decrease in the efficiency while reducing the propeller 3 in thickness.
    • <<Modifications>>
  • Although the propeller fan U1 and the like according to the present invention have been described above in each embodiment, the present invention is not limited to such description, and various changes can be made. For example, in each embodiment, as the configuration of the enlarged-diameter portion 82 included in the bell mouth 8 (see Fig. 2), the diameter of the enlarged-diameter portion 82 linearly and monotonously increases toward the downstream side (blowing side) of the air flow in the axial direction. However, the present invention is not limited to this configuration. For example, the bell mouth 8 may have configurations as shown in Figs. 14A to 14C described below.
  • Fig. 14A is a sectional view of a propeller fan UC1 according to a first modification. Note that in Fig. 14A, the fan motor 31 of the propeller 3 is not shown. In the modification of Fig. 14A, the diameter of an enlarged-diameter portion 82C of a bell mouth 8C increases in a stepwise manner toward the downstream side (blowing side) of the air flow in the axial direction. Also in such a configuration, since the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side, the flow of air blown from the propeller 3 can be along the bell mouth 8C. Thus, the pressure loss of air in the propeller fan UC1 can be reduced, and a high efficiency can be achieved.
  • Fig. 14B is a sectional view of a propeller fan UD1 according to a second modification. In the modification of Fig. 14B, the diameter of an enlarged-diameter portion 82D of a bell mouth 8D monotonously increases toward the downstream side (blowing side) of the air flow in the axial direction, and the enlarged-diameter portion 82D has a shape raised inward in the radial direction. Also in such a configuration, since the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side, the flow of air blown from the propeller 3 can be along the bell mouth 8D.
  • Fig. 14C is a sectional view of a propeller fan UE1 according to a third modification. In the modification of Fig. 14C, the diameter of an enlarged-diameter portion 82E of a bell mouth 8E monotonously increases toward the downstream side (blowing side) of the air flow in the axial direction, and the enlarged-diameter portion 82E has a shape raised outward in the radial direction. Also in such a configuration, since the trailing edge portion 32b of the blade 32 has a raised shape curved toward the blowing side, the flow of air blown from the propeller 3 can be along the bell mouth 8E.
  • In the first embodiment, the configuration in which the second position β is provided between the first position α (see Fig. 2) and the third position γ (see Fig. 2) in the span direction has been described, but the present invention is not limited thereto. For example, the second position β may be provided closer to the blade root side than the first position α in the span direction. Also with such a configuration, effects similar to those of the first embodiment are obtained.
  • In the first embodiment, the configuration in which the first position α is provided at the first intermediate portion 325 (see Fig. 6A) between the blade leading edge tip 321 (see Fig. 2) and the blade leading edge root 323 (see Fig. 2) has been described, but the present invention is not limited thereto. That is, the first position α may be provided closer to the blade tip side or the blade root side with respect to the first intermediate portion 325. Note that the same applies to the second to seventh embodiments. In the first embodiment, the configuration in which the second position β is provided at the second intermediate portion 326 (see Fig. 6C) between the blade trailing edge tip 322 (see Fig. 2) and the blade trailing edge root 324 (see Fig. 2) has been described, but the present invention is not limited thereto. That is, the second position β may be provided closer to the blade tip side or the blade root side with respect to the second intermediate portion 326. Note that the same applies to the second to seventh embodiments.
  • In each embodiment, the configuration in which the blade leading edge tip 321 (see Fig. 2) is positioned closer to the blowing side than the first position α. That is, the blade leading edge tip 321 and the first position α may be substantially at the same position in the axial position, or the blade leading edge tip 321 may be positioned closer to the suction side than the first position α. Also with such a configuration, effects similar to those of each embodiment are obtained.
  • In the first embodiment, the case where the leading edge portion 32a has the shape raised toward the suction side in the area from the blade leading edge root 323 to the first position α has been described, but the present invention is not limited thereto. For example, the leading edge portion 32a may have a shape changing from a shape raised toward the blowing side to a shape raised toward the suction side through a predetermined inflection point (not shown) from the blade leading edge root 323 to the first position α.
  • The propeller fan U1 and the like described in each embodiment can also be applied to various types of air-conditioners such as a packaged air-conditioner and a building multi-type air-conditioner in addition to a room air-conditioner. Moreover, the propeller fan U1 and the like described in each embodiment can also be applied to various devices other than the air-conditioner.
  • Each embodiment has been described in detail for the sake of easy understanding of the present invention, and is not limited to those having all the configurations described above. In addition, it is possible to make addition, omission, and replacement of other configurations for part of the configuration of each embodiment. Further, the above-described mechanisms and configurations are described as being necessary for description, and not all the mechanisms and configurations are necessary for a product.
    • LIST OF REFERENCE SIGNS
    • 1
    Compressor
    2
    Outdoor Heat Exchanger
    3, 3A
    Propeller (Outdoor Fan)
    4
    Expansion Valve
    5
    Indoor Heat Exchanger
    6
    Indoor Fan
    7
    Four-Way Valve
    31
    Fan Motor
    31a
    Motor Shaft
    32, 32A
    Blade
    33
    Boss Portion
    321
    Blade Leading Edge Tip
    322
    Blade Trailing Edge Tip
    323
    Blade Leading Edge Root
    324
    Blade Trailing Edge Root
    325
    First Intermediate Portion
    326
    Second Intermediate Portion
    32a
    Leading Edge Portion
    32b
    Trailing Edge Portion
    32c
    Blade Tip Portion
    32d
    Blade Root Portion
    8, 8B, 8C, 8D, 8E
    Bell Mouth
    100, 100B
    Air-Conditioner
    α
    First Position
    β
    Second Position
    γ
    Third Position
    Q, QB
    Refrigerant Circuit
    U1, UA1, UB1, UC1, UD1, UE1
    Propeller Fan
    Y
    Center Axis

Claims (9)

  1. A propeller fan comprising:
    a propeller including a boss portion rotating integrally with a motor shaft and a plurality of blades installed in the boss portion; and
    a bell mouth provided on an outer peripheral side of the propeller,
    wherein a first position closest to a suction side at a leading edge portion of each blade is provided between a blade leading edge tip and a blade leading edge root,
    the leading edge portion has, between the blade leading edge tip and the first position, a recessed shape curved toward a blowing side, and
    a trailing edge portion of each blade has a raised shape curved toward the blowing side.
  2. The propeller fan according to claim 1, wherein
    a second position closest to the blowing side at the trailing edge portion is provided between a blade trailing edge tip and a blade trailing edge root, and
    a portion of the trailing edge portion closer to the second position is positioned closer to the blowing side.
  3. The propeller fan according to claim 2, wherein
    the first position is provided at a first intermediate portion between the blade leading edge tip and the blade leading edge root in a span direction along the leading edge portion, and
    the second position is provided at a second intermediate portion between the blade trailing edge tip and the blade trailing edge root in a span direction along the trailing edge portion.
  4. The propeller fan according to claim 2, wherein
    a distance in a radial direction from a center axis of the propeller to the first position is equal to a distance in the radial direction from the center axis to the second position.
  5. The propeller fan according to claim 2, wherein
    each blade has a maximum attachment angle of a blade section at the first position.
  6. The propeller fan according to claim 2, wherein
    each blade has a maximum attachment angle of a blade section at the second position.
  7. The propeller fan according to claim 2, wherein
    each blade has a maximum chord length at the first position.
  8. The propeller fan according to claim 2, wherein
    each blade has a maximum chord length at the second position.
  9. An air-conditioner comprising:
    a compressor;
    an outdoor heat exchanger;
    an expansion valve;
    an indoor heat exchanger;
    an outdoor fan including a boss portion rotating integrally with a motor shaft and a plurality of blades installed in the boss portion; and
    a bell mouth provided on an outer peripheral side of the outdoor fan,
    wherein a first position closest to a suction side at a leading edge portion of each blade is provided between a blade leading edge tip and a blade leading edge root,
    the leading edge portion has, between the blade leading edge tip and the first position, a recessed shape curved toward a blowing side, and
    a trailing edge portion of each blade has a raised shape curved toward the blowing side.
EP21942926.3A 2021-05-25 2021-05-25 Propeller fan and air conditioner Pending EP4350151A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2021/019737 WO2022249270A1 (en) 2021-05-25 2021-05-25 Propeller fan and air conditioner

Publications (1)

Publication Number Publication Date
EP4350151A1 true EP4350151A1 (en) 2024-04-10

Family

ID=84229550

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21942926.3A Pending EP4350151A1 (en) 2021-05-25 2021-05-25 Propeller fan and air conditioner

Country Status (4)

Country Link
EP (1) EP4350151A1 (en)
JP (1) JPWO2022249270A1 (en)
CN (1) CN116964333A (en)
WO (1) WO2022249270A1 (en)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6215296B2 (en) * 2013-02-22 2017-10-18 ジョンソンコントロールズ ヒタチ エア コンディショニング テクノロジー（ホンコン）リミテッド Propeller fan and air conditioner equipped with the same
US20220186742A1 (en) * 2019-05-21 2022-06-16 Mitsubishi Electric Corporation Axial fan, air-sending device, and refrigeration cycle apparatus

Also Published As

Publication number Publication date
WO2022249270A1 (en) 2022-12-01
CN116964333A (en) 2023-10-27
JPWO2022249270A1 (en) 2022-12-01

Similar Documents

Publication Publication Date Title
EP3333431B1 (en) Centrifugal blower, air-conditioning device, and refrigeration cycle device
TWI731570B (en) Centrifugal blower, blower, air conditioner and refrigeration cycle device
KR20190035852A (en) Indoor unit and air conditioner
EP2835585A1 (en) Indoor unit for air conditioning device
KR102451220B1 (en) Centrifugal blowers, blowers, air conditioners and refrigeration cycle units
US10890194B2 (en) Air-sending device and air-conditioning apparatus using the same
EP3460254B1 (en) Air conditioner
EP3705729B1 (en) Centrifugal blower, blowing device, air conditioner, and refrigeration cycle device
JP6952905B2 (en) Centrifugal blower, blower, air conditioner and refrigeration cycle device
EP4350151A1 (en) Propeller fan and air conditioner
EP3382295A1 (en) Indoor unit of air conditioner
US11976824B2 (en) Centrifugal fan, air conditioning apparatus, and refrigeration cycle apparatus
WO2018092262A1 (en) Propeller fan and refrigeration cycle device
US11333166B2 (en) Propeller fan and refrigeration cycle apparatus
JP7130061B2 (en) Centrifugal blowers, blowers, air conditioners and refrigeration cycle devices
EP3916238A1 (en) Fan blower, indoor unit, and air conditioner
JP6430032B2 (en) Centrifugal fan, air conditioner and refrigeration cycle apparatus
JP7378505B2 (en) Centrifugal blower and air conditioner equipped with it
JP7360823B2 (en) air conditioner
JP2022069998A (en) Indoor unit of air conditioner
JPWO2020129179A1 (en) Centrifugal blower, blower, air conditioner and refrigeration cycle device

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20230927

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR