EP3660405B1

EP3660405B1 - Air conditioner

Info

Publication number: EP3660405B1
Application number: EP17919054.1A
Authority: EP
Inventors: Yasuaki Kato; Takuya Teramoto; Takashi Ikeda; Seiji Nakashima; Katsuyuki Yamamoto
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2017-07-26
Filing date: 2017-07-26
Publication date: 2021-09-08
Anticipated expiration: 2037-07-26
Also published as: CN110892201A; EP3660405A4; CN110892201B; JP6710337B2; WO2019021391A1; JPWO2019021391A1; EP3660405A1; ES2892967T3; TW201910693A; TWI664381B

Description

Technical Field

The present invention relates to an air-conditioning apparatus provided with a turbo fan.

Background Art

Patent Literature 1 describes an air-conditioning apparatus. The air-conditioning apparatus includes a centrifugal fan, and a heat exchanger around the centrifugal fan. An impeller of the centrifugal fan includes a hub attached to a motor shaft, a shroud provided opposite to the hub, and a plurality of blades disposed between an outer circumferential portion of the hub and an outer circumferential portion of the shroud. The centrifugal fan has an air inlet at a center portion of the shroud. The centrifugal fan has an air outlet at the outer circumferential portion of the impeller.
Patent Literature 2 describes an air-conditioning apparatus anticipating the features of the preamble of claim 1.

Citation List

Patent Literature

Patent Literature 1: Japanese Patent No. 3092554
Patent Literature 2: WO 2017/115490 A1

Summary of Invention

Technical Problem

In the centrifugal fan, air is sucked into the impeller through the air inlet in the axial direction of the centrifugal fan. The air sucked into the impeller has a momentum in the axial direction from the shroud toward the hub. In a low-pressure centrifugal fan provided in, for example, an air-conditioning apparatus, blades have a relatively short length in the radial direction. Thus, air blown out from the air outlet of the centrifugal fan flows such that the volume of the air-flow distribution on a hub side in the axial direction is larger.
Air blown out from the air outlet of the centrifugal fan flows into the heat exchanger provided close to the centrifugal fan. In general, for the air outlet of the centrifugal fan, the heat exchanger is located closer to the shroud than to the hub in the axial direction of the centrifugal fan. The degree of an imbalance in an air-flow distribution of air that flows into the heat exchanger is thus greater than that of the imbalance in an air-flow distribution of air that is blown out at the air outlet of the centrifugal fan.
The heat exchanger also works as a resistor against an air flow. Thus, when air flows into the heat exchanger such that the distribution of the flow of the air is imbalanced, the degree of the imbalance in the air-flow distribution is reduced, but a dynamic pressure loss occurs. Therefore, the air-conditioning apparatus described in Patent Literature 1 causes a large energy loss to occur and thus requires a large amount of power.
The present invention has been made to solve the above problem, and aims to provide an air-conditioning apparatus that requires a small amount of power and improves its energy efficiency to achieve energy savings.

Solution to Problem

An air-conditioning apparatus according to an aspect of the present invention includes a turbo fan that includes an impeller and a fan motor that drives the impeller, and a heat exchanger provided leeward of the impeller. The impeller includes a main plate connected to a drive shaft of the fan motor, a side plate provided opposite to the main plate and having an air inlet at a center portion of the side plate, and a plurality of blades disposed between the main plate and the side plate. Each of the plurality of blades includes a front edge and a rear edge located outward of the front edge in a radial direction of the turbo fan. The rear edge has a notch. Each of the plurality of blades includes a first side and a second side, which are a pair of sides located opposite to each other with respect to the notch, the first side being located on a side of the notch that is closer to the main plate, and the second side being located on another side of the notch which is closer to the side plate. The second side is formed convex toward the main plate.

Advantageous Effects of Invention

According to the embodiment of the present invention, air flow along the second side can be curved in a direction toward the side plate, whereby the imbalance in the air-flow distribution of air that flows into the heat exchanger can be reduced. It is therefore possible to reduce the dynamic pressure loss occurring in a time period in which air is blown out of the impeller and flows into the heat exchanger. Thus, an air-conditioning apparatus that requires a small amount of power and improves its energy efficiency to achieve energy savings can be obtained.

Brief Description of Drawings

[Fig. 1] Fig. 1 is a schematic diagram of a cross-sectional configuration of an air-conditioning apparatus according to Embodiment 1 of the present invention.
[Fig. 2] Fig. 2 is an enlarged view of a configuration of a blade 15 of the air-conditioning apparatus according to Embodiment 1 of the present invention.
[Fig. 3] Fig. 3 is an enlarged view of the configuration of the blade 15 of the air-conditioning apparatus according to Embodiment 1 of the present invention.
[Fig. 4] Fig. 4 illustrates the positional relationship between the blade 15 and a heat exchanger 20 of the air-conditioning apparatus according to Embodiment 1 of the present invention.
[Fig. 5] Fig. 5 illustrates a first modification of the configuration of the blade 15 of the air-conditioning apparatus according to Embodiment 1 of the present invention.
[Fig. 6] Fig. 6 illustrates a second modification of the configuration of the blade 15 of the air-conditioning apparatus according to Embodiment 1 of the present invention.
[Fig. 7] Fig. 7 illustrates a configuration of a blade 15 of an air-conditioning apparatus according to Embodiment 2 of the present invention.
[Fig. 8] Fig. 8 illustrates a configuration of a blade 15 of an air-conditioning apparatus according to Embodiment 3 of the present invention.

Description of Embodiments

Embodiment 1

An air-conditioning apparatus according to Embodiment 1 of the present invention will be described. With respect to Embodiment 1, as an example of an indoor unit of the air-conditioning apparatus, a four-way airflow type of ceiling cassette indoor unit will be described. Fig. 1 is a schematic diagram of a cross-sectional configuration of the air-conditioning apparatus according to Embodiment 1. Fig. 1 illustrates a cross section of an air-conditioning apparatus that is taken along a meridian plane of a turbo fan 10. It should be noted that the meridian plane is a plane in which an axis O of the turbo fan 10 is located. The shape of a blade 15 as illustrated in Fig. 1 and Figs. 2 to 8 to be referred to later is that on the meridian plane of the turbo fan 10, on which the shape of one of the plurality of blades 15 is projected when they are rotated.
As illustrated in Fig. 1, the air-conditioning apparatus includes: a turbo fan 10 that includes an impeller 11 and a fan motor 12 that drives the impeller 11; a heat exchanger 20 provided leeward of the impeller 11 ; and a housing 21 that houses the turbo fan 10 and the heat exchanger 20. The fan motor 12 of the turbo fan 10 is fixed to a center portion of an inner surface of an upper side of the housing 21. The turbo fan 10 has an axis O, which extends vertically. The heat exchanger 20 is provided in such a manner as to surround an outer circumferential portion of the impeller 11, and is formed in the shape of a substantially rectangular frame as viewed in a direction along the axis O. The heat exchanger 20 is included in a refrigeration cycle system that circulates refrigerant, along with a compressor, an outdoor heat exchanger, and an expansion valve, which are not illustrated. The heat exchanger 20 operates as an evaporator during a cooling operation, and operates as a condenser during a heating operation.
In a center portion of a lower surface of the housing 21, an air inlet 22 is provided as an air inlet of the air-conditioning apparatus to allow indoor air to flow into the housing 21. In an outer portion of the lower surface of the housing 21 that is located around the air inlet 22, an air outlet 23 is provided as an air outlet of the air-conditioning apparatus to allow conditioned air that has passed through the heat exchanger 20 to be blown out from the housing 21. The four-way airflow type of ceiling cassette indoor unit includes four air outlets 23 that allow conditioned air to be blown out in four different directions.
The impeller 11 includes a main plate 13 connected to a drive shaft 12a of the fan motor 12, a ring-shaped side plate 14 provided opposite to the main plate 13, and a plurality of blades 15 disposed between the main plate 13 and the side plate 14. At a center portion of the side plate 14, an air inlet 16 is formed in the shape of a circular opening which is circular about the axis O, as an air inlet of the impeller 11. The air inlet 16 of the impeller 11 is located opposite to the air inlet 22 of the air-conditioning apparatus. Between the air inlet 22 of the air-conditioning apparatus and the air inlet 16 of the impeller 11, a bellmouth 18 is provided to guide indoor air sucked from the air inlet 22 to the air inlet 16. In the impeller 11, an air outlet 17 is formed in the outer circumferential portion of the impeller 11. The plurality of blades 15 are arranged at regular or irregular intervals in the circumferential direction about the axis O. All the blades 15 have the same shape. The shape of the blades 15 will be described in detail later.
When the impeller 11 is rotated about the axis O by a driving force of the fan motor 12, indoor air sucked into the housing 21 through the air inlet 22 of the air-conditioning apparatus is guided by the bellmouth 18, and sucked into the impeller 11 through the air inlet 16 of the impeller 11. The indoor air sucked into the impeller 11 passes through space between two adjacent blades 15 arranged in the circumferential direction, and is blown out from the air outlet 17 of the impeller 11 to an outer circumferential region located outward of the impeller 11. The indoor air blown out to the outer circumferential region passes through the heat exchanger 20 and exchanges heat with refrigerant to be cooled or heated and thus conditioned. The conditioned air is blown into an indoor space through the air outlets 23 of the air-conditioning apparatus.
Fig. 2 is an enlarged view of a configuration of each of the blades 15 in the air-conditioning apparatus according to Embodiment 1. It should be noted that the vertical direction in Fig. 2 is the axial direction in which the axis O of the turbo fan 10 and the impeller 11 extends; and the lateral direction in Fig. 2 is the radial direction of the turbo fan 10 and the impeller 11. Also, the left side of Fig. 2 illustrates an outer region in the radial direction, and the right side of the Fig.2 illustrates an inner region in the radial direction.
As illustrated in Fig. 2, each blade 15 includes an upper end portion 32 joined to a lower surface of the main plate 13, and a lower end portion 33 joined to an upper surface of the side plate 14. Also, each blade 15 includes a front edge 30 and a rear edge 31 located rearward of the front edge 30 in a rotation direction of the impeller 11. The rear edge 31 is also located outward of the front edge 30 in the radial direction. The front edge 30 and the rear edge 31 both extend from the upper end portion 32 to the lower end portion 33. Hereinafter, an end portion of the rear edge 31 that is jointed to the upper end portion 32 and an end portion of the rear edge 31 that is jointed to the lower end portion 33 may be referred to as a main-plate-side end portion 31a and a side-plate-side end portion 31b, respectively.
In part of the rear edge 31, a single notch 34 is formed in such a manner as to have a substantially triangular shape. To be more specific, the notch 34 is formed in the shape of a substantially triangle which tapers from the rear edge 31 toward the front edge 30. Each blade 15 has a first side 35a and a second side 35b as a pair of sides that are opposite to each other with respect to the notch 34, and the first side 35a is located closer to the main plate 13 than the notch 34 in the axial direction, and the second side 35b is located closer to the side plate 14 than the notch 34 in the axial direction. The notch 34 is formed such that the beginning of the notch 34 is located at a first contact point 37 at which the first side 35a and the rear edge 31 are connected to each other and the end of the notch 34 is located at a second contact point 38 at which the second side 35b and the rear edge 31 are connected to each other.
Bottom part 36 of the notch 34 is also innermost part thereof in the radial direction. In the axial direction, the bottom part 36 is located between the first contact point 37 and the second contact point 38. To be more specific, the bottom part 36 is located between a plane that extends through the first contact point 37 in a direction perpendicular to the axial direction and a plane that extends through the second contact point 38 in the direction perpendicular to the axial direction. The first side 35a connects the first contact point 37 and the bottom part 36, and the second side 35b connects the second contact point 38 and the bottom part 36. The notch 34 in Embodiment 1 is substantially triangular, and the bottom part 36 is provided as a point.
A depth D1 of the notch 34 in the radial direction is the distance between the second contact point 38 and the bottom part 36 in the radial direction. That is, the depth D1 is equal to a distance obtained by subtracting the distance between the bottom part 36 and the axis O from the distance between the second contact point 38 and the axis O. A width W1 of the notch 34 in the axial direction is the distance between the first contact point 37 and the second contact point 38 in the axial direction. The depth D1 is greater than the width W1 (D1>W1). The depth D1 is greater than or equal to a quarter of the distance between the front edge 30 and the rear edge 31 in the radial direction.
The second side 35b is smoothly curved toward the main plate 13 as a whole. Specifically, the second side 35b is convex toward the inside of the notch 34. The second side 35b is, for example, arcuate.
The first side 35a is smoothly curved as a whole in such a manner as to project toward the main plate 13. That is, the first side 35a is concave with respect to the notch 34. The first side 35a is, for example, arcuate.
Fig. 3, as well as Fig. 2, is an enlarged view of the configuration of each blade 15 of the air-conditioning apparatus according to Embodiment 1. As illustrated inFig. 3, the notch 34 is formed in part of the rear edge 31 that is closer to the main plate 13. More specifically, where an imaginary plane that is located at an intermediate position between the main-plate-side end portion 31a and the side-plate-side end portion 31b of the rear edge 31 in the axial direction is a first plane P1, the bottom part 36 of the notch 34 is located closer to the main plate 13 than the first plane P1. The first plane extends in the direction perpendicular to the axial direction, and is equidistant from the main-plate-side end portion 31a and the side-plate-side end portion 31b.
Fig. 4 indicates a positional relationship between each blade 15 and the heat exchanger 20 of the air-conditioning apparatus according to Embodiment 1. As illustrated in Fig. 4, the heat exchanger 20 faces the air outlet 17 of the turbo fan 10, and is located closer to the side plate 14 than the main plate 13. To be more specific, where an imaginary plane that is located at an intermediate position between an upper end portion 20a and a lower end portion 20b of the heat exchanger 20 in the axial direction is a second plane P2, the second plane P2 is located closer to the side plate 14 than the first plane P1. The second plane P2 extends in the direction perpendicular to the axial direction, and is equidistant from the upper end portion 20a and the lower end portion 20b. The bottom part 36 of the notch 34 is located closer to the main plate 13 than the first plane P1. Thus, needless to say, the bottom pat 36 is located closer to the main plate 13 than the second plane P2.
When the impeller 11 is rotated, each blade 15 operates to push air out on a positive-pressure side and to draw air in on a negative-pressure side. Similarly, this operation is also performed in the vicinity of the notch 34. When air that flows from the front edge 30 along a blade surface of the blade 15 that is located on the positive-pressure side or the negative-pressure side reaches the bottom part 36 of the notch 34, the air flows from the bottom part 36 toward the rear edge 31 along the first side 35a or the second side 35b.
The turbo fan 10 sucks air into the impeller 11 through the air inlet 16 in the axial direction. Thus, air sucked into the impeller 11 has a momentum in the axial direction from the side plate 14 toward the main plate 13. Thus, as indicated by thick arrow F1 in Fig. 2, air flowing along the blade surface of each blade 15 flows from the front edge 30 toward the bottom part 36 while gradually approaching the main plate 13. However, since the second side 35b is convex toward the main plate 13, air that flows from the bottom part 36 toward the rear edge 31 along the second side 35b is gradually curved in a direction toward the side plate 14 as it approaches the rear edge 31, as indicated by thick arrow F2 in Fig. 2.
The first side 35a is also convex toward the main plate 13. Thus, air that flows from the bottom part 36 toward the rear edge 31 along the first side 35a is also gradually curved in the direction toward the side plate 14 as it approaches the rear edge 31.
Air that flows through space between two adjacent blades 15 arranged in the circumferential direction flows to follow an air flow along the blade surface of each of the blades 15. Thus, in an outer circumferential region located outward of the bottom part 36 of the notch 34, an air flow is curved toward the side plate 14 as a whole, from the flow direction of air in an inner circumferential region located inward of the bottom part 36.
Because of provision of the notch 34 in the rear edge 31 of each blade 15, airflow distribution of air blown out through the air outlet 17 of the impeller 11 is further uniformized, thus reducing such an imbalance in the air-flow distribution in the axial direction that a larger amount of air flows toward the main plate 13. Thus, the imbalance in the air-flow distribution of air that flows into the heat exchanger 20 is also reduced. Therefore, according to Embodiment 1, it is possible to reduce a dynamic pressure loss that occurs in air in a time period in which the air is blown out from the air outlet 17 of the impeller 11 and flows into the heat exchanger 20, and thus obtain an air-conditioning apparatus that requires a small amount of power and thus improves its energy efficiency to achieve energy savings.
Next, modifications of Embodiment 1 will be described. Fig. 5 illustrates a first modification of the configuration of each blade 15 in the air-conditioning apparatus according to Embodiment 1. As illustrated in Fig. 5, in the rear edge 31 of each blade 15 in the first modification, a notch 34 is formed to have a substantially trapezoid. The bottom part 36 is shaped to linearly extend in the axial direction. Other components are the same as those as illustrated in Figs. 1 to 4. Also in the first modification, when air that flows from the front edge 30 along the blade surface of the blade 15 reaches the bottom part 36 of the notch 34, the air flows from the bottom part 36 toward the rear edge 31 along the first side 35a or the second side 35b. Therefore, in the first modification also, it is also possible to obtain the same advantages as those obtained in the configuration as illustrated in Fig. 1 to Fig. 4.
Fig. 6 illustrates a second modification of the configuration of each blade 15 in the air-conditioning apparatus according to Embodiment 1. As illustrated in Fig. 6, the first side 35a includes an R portion 35a1 in an area adjoining the first contact point 37. Also, the second side 35b includes an R portion 35b1 in an area adjoining the second contact point 38. Also, in this configuration, the notch 34 is formed such that the beginning of the notch 34 is located at the first contact point 37 and the end of the notchy 34 is located at the second contact point 38. The first side 35a is smoothly curved toward the main plate 13 substantially as a whole, except for the R portion 35a. The second side 35b is smoothly curved toward the main plate 13 as a whole including the R portion 35b1. Also, in the second modification, it is possible to obtain the same advantages as those obtained in the configuration as illustrated in Figs. 1 to 4.
As described above, the air-conditioning apparatus according to Embodiment 1 includes the turbo fan 10 provided with the impeller 11 and the fan motor 12 that drives the impeller 11, and the heat exchanger 20 provided leeward of the impeller 11. The impeller 11 includes the main plate 13 connected to the drive shaft 12a of the fan motor 12, the side plate 14 provided opposite to the main plate 13 and having the air inlet 16 at the center portion of the side plate 14, and the plurality of blades 15 arranged between the main plate 13 and the side plate 14. Each of the blades 15 includes the front edge 30 and the rear edge 31 located outward of the front edge 30 in the radial direction of the turbo fan 10. In the rear edge 31, the notch 34 is formed. Each of the blades 15 has the first side 35a and the second side 35b, which are a pair of sides located opposite to each other with respect to the notch 34. The first side 35a is located on a side of the notch 34 that is closer to the main plate 13 than the notch 34, and the second side 35b is located on another side of the notch 34 that is closer to the side plate 14. The second side 35b is convex toward the main plate 13.
Because of the above configuration, the flow of air that flows along the second side 35b can be curved in a direction toward the side plate 14, and thus can reduce the imbalance in the air-flow distribution of air that flows into the heat exchanger 20. It is therefore possible to reduce a dynamic pressure that occurs in air in a time period in which the air is blown out from the impeller 11 and flows into the heat exchanger 20, and thus provide an air-conditioning apparatus that requires a small amount of power and improves its energy efficiency to achieve energy savings.
In the air-conditioning apparatus according to Embodiment 1, where one of both two end portions of the rear edge 31 that is located closer to the main plate 13 is the main-plate-side end portion 31a, the other is the side-plate-side end portion 31b, the plane that extends in the direction perpendicular to the axial direction of the turbo fan 10 and is equidistant from the main-plate-side end portion 31a and the side-plate-side end portion 31b is the first plane P1, and the innermost part of the notch 34 in the radial direction of the turbo fan 10 is the bottom part 36 of the notch 34, the bottom part 36 of the notch 34 is located closer to the main plate 13 than the first plane P1. In this configuration, the notch 34 is formed at a position where the airflow rate is relatively high, and it is therefore possible to effectively reduce the imbalance in the air-flow distribution of air that flows into the heat exchanger 20.
In the air-conditioning apparatus according to Embodiment 1, where one end portion (for example, the upper end portion 20a) of the heat exchanger 20 in the axial direction is a first end portion, another end portion (for example, the lower end portion 20b) of the heat exchanger 20 in the axial direction is a second end portion, and a plane perpendicular to the axial direction and equidistant from the first end portion and the second end portion is the second plane P2, the second plane P2 is located closer to the side plate 14 than the first plane P1. In this configuration, the degree of the imbalance in the air-flow distribution in the axial direction of air that flows into the heat exchanger 20 is greater than that of the imbalance in the air-flow distribution in the axial direction at the air outlet 17 of the impeller 11. Therefore, because of provision of the notch 34, it is possible to reduce the imbalance in the air-flow distribution, and thus greatly reduce a dynamic pressure loss that occurs in a time period in which air is blown out from the impeller 11 and flows into the heat exchanger 20.
In the air-conditioning apparatus according to Embodiment 1, the depth D1 of the notch 34 in the radial direction of the turbo fan 10 is greater than the width W1 of the notch 34 in the axial direction of the turbo fan 10. In this configuration, the second side 35b can be provided to have a sufficiently great length in the radial direction, thus enabling the air flow along the second side 35b to be reliably curved.
In the air-conditioning apparatus according to Embodiment 1, the first side 35a is formed convex toward the main plate 13. In this configuration, not only the air flow along the second side 35b, but the air flow along the first side 35a can be curved toward the side plate 14. It is therefore possible to reliably reduce the imbalance in the air-flow distribution of air that flows into the heat exchanger 20.

Embodiment 2

An air-conditioning apparatus according to Embodiment 2 of the present invention will be described. Fig. 7 illustrates a configuration of each blade 15 of the air-conditioning apparatus according to Embodiment 2. As illustrated in Fig. 7, the blade 15 includes a notch group 39 that comprises a plurality of notches 39a, 39b, 39c, and 39d arranged side by side in the axial direction and formed in the rear edge 31. Each of the notches 39a, 39b, 39c, and 39d has the same shape as the notch 34 as illustrated in Figs. 2 and 3. The notches 39a, 39b, 39c, and 39d are arranged in this order from a side closer to the main plate 13 toward the side plate 14.
Where a connection point at which the rear edge 3 and the first side 35a of the notch 39a in the notch group 39, which is the closest to the main plate 13, are connected to each other is an end portion 40 of the notch group 39 on the side closer to the main plate 13, a connection point at which the rear edge 31 and the second side 35b of the notch 39d in the notch group 39, which is located closest to the side plate 14, are connected to each other is an end portion 41 of the notch group 39 on the side closer to the side plate 14, and an imaginary plane that is located at an intermediate position between the end portion 40 and the end portion 41 in the axial direction is a third plane P3, the third plane P3 is located closer to the main plate 13 than the first plane P1. Also, the third plane P3 is a plane perpendicular to the axial direction and equidistant from the end portion 40 and the end portion 41.
As described above, in the air-conditioning apparatus according to Embodiment 2, the notch group 39 comprising the notches 39a, 39b, 39c, and 39d is formed in the rear edge 31. Where the plane perpendicular to the axial direction of the turbo fan 10 and equidistant from the main-plate-side end portion 31a and the side-plate-side end portion 31b is the first plane P1, and the plane perpendicular to the axial direction and equidistant from the end portion 40 of the notch group 39, which is closer to the main plate 13, and the end portion 41 of the notch group 39, which is closer to the side plate 14, is the third plane P3, the third plane P3 is located closer to the main plate 13 than the first plane P1.
In this configuration, each blade 15 includes the notch group 39 in a wide area close to the main plate 13 in the axial direction. Thus, an advantage in which the air flow can be curved in the direction toward the side plate 14 by the notches 39a, 39b, 39c, and 39d can be obtained for the air flow that passes through the wide area of each blade 15 in the axial direction, that is, the air flow that passes through the wide area of each blade 15 in the axial direction can also be curved in the direction toward the side plate 14 by the notches 39a, 39b, 39c. Thus, the imbalance in the air-flow distribution of air that flows into the heat exchanger 20 can be effectively reduced.

Embodiment 3

An air-conditioning apparatus according to Embodiment 3 of the present invention will be described. Fig. 8 illustrates a configuration of each blade 15 of the air-conditioning apparatus according to Embodiment 3. As illustrated in Fig. 8, in order to divide rear-edge flowing-out vortexes into small vortexes, a plurality of notched portions 42 are formed in part of the rear edge 31 that is closer to the side plate 14 than the notch 34, such that they are arranged side by side in the axial direction. Thus, the part of the rear edge 31 that is closer to the side plate 14 than the notch 34 is saw-toothed. It should be noted that no notched portions 42 are formed in part of the rear edge 31 that is closer to the main plate 13 than the notch 34. That is, the notched portions 42 are formed only in the part of the rear edge 31 that is closer to the side plate 14 than the notch 34. The notched portions 42 are formed throughout the part of the rear edge 31 that is closer to the side plate 14 than the notch 34.
A depth D2 of each of the notched portions 42 in the radial direction is smaller than or equal to a width W2 of each notched portion 42 in the axial direction (D2≤W2). The width W2 of each notched portion 42 in the axial direction is smaller than the width W1 (refer to Fig. 2) of the notch 34 (W2<W1). The depth D2 of each notched portion 42 in the radial direction is smaller than the depth D1 (see Fig. 2) of the notch 34 (D2<D1).
As described above, in the air-conditioning apparatus according to Embodiment 3, the rear edge 31 has a plurality of notched portions 42 in part of the rear edge 31 that is located closer to the side plate 14 than the notch 34. The width W2 of each of the multiple notched portions 42 in the axial direction of the turbo fan 10 is smaller than the width W1 of the notch 34 in the axial direction. The depth D2 of each of the notched portions 42 in the radial direction of the turbo fan 10 is smaller than the depth D1 of the notch 34 in the radial direction.
When the air flow is curved by the notch 34 in the direction toward the side plate 14, the flow rate of air in an area closer to the side plate 14 than the notch 34 increases to be relatively high. In the configuration in Embodiment 3, the notched portions 42 are formed in the part of the rear edge 31 that is closer to the side plate 14 than the notch 34, that is, in the area in which the flow rate of air is relatively high. Thus, the rear-edge flowing-out vortexes that flow out from the rear edge 31 can be effectively divided into small vortexes. It is therefore possible to reduce the noise of the turbo fan 10 and the air-conditioning apparatus.
The above embodiments can be put to practical use in combination. Reference Signs List
10 turbo fan, 11 impeller, 12 fan motor, 12a drive shaft, 13 main plate, 14 side plate, 15 blade, 16 air inlet, 17 air outlet, 18 bellmouth, 20 heat exchanger, 20a upper end portion, 20b lower end portion, 21 housing, 22 air inlet, 23 air outlet, 30 front edge, 31 rear edge, 31a main-plate-side end portion, 31b side-plate-side end portion, 32 upper end portion, 33 lower end portion, 34 notch, 35a first side, 35b second side, 35a1, 35b1 rounded portion, 36 bottom part, 37 first contact point, 38 second contact point, 39 notch group, 39a, 39b, 39c, 39d notch, 40, 41 end portion, 42 notched portion, O axis, P1 first plane, P2 second plane, P3 third plane

Claims

An air-conditioning apparatus comprising:
a turbo fan (10) including an impeller (11) and a fan motor (12) configured to drive the impeller (11); and

a heat exchanger (20) provided leeward of the impeller (11),

wherein the impeller (11) includes
a main plate (13) connected to a drive shaft (12a) of the fan motor (12), a side plate (14) located opposite to the main plate (13) and having an air inlet (16) at a center portion of the side plate (14),

a plurality of blades (15) disposed between the main plate (13) and the side plate (14),

wherein each of the plurality of blades (15) includes a front edge (30) and a rear edge (31) located outward of the front edge (30) in a radial direction of the turbo fan (10), and

wherein in the rear edge (31), a notch (34) is formed,
characterised in that
each of the plurality of blades (15) includes a first side (35a) and a second side (35b), which are a pair of sides located opposite to each other with respect to the notch (34), the first side (35a) being located on a side of the notch (34) that is closer to the main plate (13), the second side (35b) being located on another side of the notch (34) that is closer to the side plate (14), and

wherein the second side (35b) is formed convex toward the main plate (13).
The air-conditioning apparatus of claim 1,
wherein where one of two end portions of the rear edge (31) that is located closer to the main plate (13) is a main-plate-side end portion, the other of the two end portions, which is located closer to the side plate (14), is a side-plate-side end portion, a plane perpendicular to an axial direction of the turbo fan (10) and equidistant from the main-plate-side end portion and the side-plate-side end portion is a first plane (P1), and innermost part of the notch (34) in the radial direction of the turbo fan (10) is bottom part (36) of the notch (34), the bottom part (36) is located closer to the main plate (13) than to the first plane (P1).
The air-conditioning apparatus of claim 2,
wherein where one end portion of the heat exchanger (20) in the axial direction is a first end portion, an other end portion of the heat exchanger (20) in the axial direction is a second end portion, and a plane perpendicular to the axial direction and equidistant from the first end portion and the second end portion is a second plane (P2), the second plane (P2) is located closer to the side plate (14) than the first plane (P1).
The air-conditioning apparatus of any one of claims 1 to 3,
wherein the notch (34) has a depth in the radial direction of the turbo fan (10) that is greater than a width of the notch (34) in an axial direction of the turbo fan (10).
The air-conditioning apparatus of any one of claims 1 to 4,
wherein the first side (35a) is formed convex toward the main plate (13).
The air-conditioning apparatus of any one of claims 1 to 5,
wherein the rear edge (31) has a notch group (39) comprising the plurality of notches (34) and formed in the rear edge (31), and

wherein where a plane perpendicular to an axial direction of the turbo fan (10) and equidistant from the main-plate-side end portion and the side-plate-side end portion is a first plane (P1), and a plane perpendicular to the axial direction and equidistant from an end portion of the notch group (39) that is closer to the main plate (13) and another end portion of the notch group (39) that is closer to the side plate (14) is a third plane (P3), the third plane (P3) is located closer to the main plate (13) than the first plane (P1).
The air-conditioning apparatus of any one of claims 1 to 6,
wherein in part of the rear edge (31) that is closer to the side plate (14) than the notch (34), a plurality of notched portions (42) are formed,

wherein each of the plurality of notched portions (42) has a width in an axial direction of the turbo fan (10) that is smaller than a width of the notch (34) in the axial direction of the turbo fan (10), and

wherein each of the plurality of notched portions (42) has a depth in the radial direction of the turbo fan (10) that is smaller than a depth of the notch (34) in the radial direction.