EP3064776A1

EP3064776A1 - Cross-flow fan and air conditioner

Info

Publication number: EP3064776A1
Application number: EP13896431.7A
Authority: EP
Inventors: Takashi Ikeda; Seiji Hirakawa; Mitsuhiro Shirota
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2013-10-29
Filing date: 2013-10-29
Publication date: 2016-09-07
Anticipated expiration: 2033-10-29
Also published as: JPWO2015063851A1; WO2015063851A1; EP3064776B1; EP3064776A4

Abstract

An impeller (8a) of a cross-flow fan (8) includes a plurality of support plates (8b) and a plurality of blades (8c). Each blade (8c) is shaped such that each of an outer peripheral end portion (15a) and an inner peripheral end portion (15b) is advanced again in a rotational direction after being retreated in the rotational direction from one corresponding support plate toward the other corresponding support plate, or is retreated again in the rotational direction after being advanced in the rotational direction from one corresponding support plate toward the other corresponding support plate.

Description

Technical Field

The present invention relates to a cross-flow fan and an air conditioner using the cross-flow fan.

Background Art

In Patent Literature 1, there is disclosed a transverse fan including blades, each being inclined at a predetermined angle with respect to a fan axis and being mounted with unequally set mounting pitches. Further, in the transverse fan, each blade is thin in an impeller longitudinal direction.
In Patent Literature 2, there is disclosed an axial fan including blades each formed so that a blade cross section orthogonal to a rotational axis decreases in size as approaching from a base portion to a distal end portion of each of the blade portions arranged side by side on a main surface. Further, in the axial fan, a center of the blade cross section orthogonal to the rotational axis is displaced frontward or backward in a direction of rotation about the rotational axis as approaching from the base portion of the blade portion toward the tip portion of the blade portion. Further, the blade cross section is curved radially outward.
Further, in Patent Literature 3, there is disclosed a fan including first components in each of which a tip portion of a blade is inclined in a rotational direction from a base of the blade, and second components in each of which the tip portion of the blade is inclined in a counter-rotational direction from the base of the blade. The first components and the second components are alternately stacked.

Citation List

Patent Literature

[PTL 1] JP 3107711 B2
[PTL 2] JP 4549416 B2
[PTL 3] JP 09-158890 A

Summary of Invention

Technical Problem

However, as for the space between a pair of rings, the cross-flow fan tends to blow out relatively a large amount of flow from the vicinity of the center between the pair of rings, which is located away from the pair of rings, thus causing a problem of a non-uniform flow between the pair of rings. Further, the above-mentioned related-art fans disclosed in Patent Literature 1 to Patent Literature 3 can generate flow components directed from one ring toward the other ring but have difficulty in alleviating the above-mentioned problem of the non-uniform flow between the pair of rings.
The present invention has been made in view of the above, and an object of the present invention is to provide a cross-flow fan capable of alleviating a non-uniform flow between a pair of support plates.

Solution to Problem

In order to attain the above-mentioned object, according to one embodiment of the present invention, there is provided a cross-flow fan, including: an impeller; and a shaft configured to support the impeller in a rotatable manner, the impeller including: a plurality of support plates; and a plurality of blades arranged between a corresponding pair of the support plates at intervals in a circumferential direction, each of the plurality of blades being shaped such that an inner peripheral end portion is advanced again in a rotational direction after being retreated in the rotational direction from one corresponding support plate toward another corresponding support plate, or is retreated again in the rotational direction after being advanced in the rotational direction from the one corresponding support plate toward the another corresponding support plate, and that an outer peripheral end portion is advanced again in the rotational direction after being retreated in the rotational direction from the one corresponding support plate toward the another corresponding support plate, or is retreated again in the rotational direction after being advanced in the rotational direction from the one corresponding support plate toward the another corresponding support plate.
Further, the each of the plurality of blades may include a pair of ring-side portions extending along a rotational axis direction without being advanced or retreated in the rotational direction.
Further, in order to attain the above-mentioned object, according to one embodiment of the present invention, there is provided an air conditioner, including: a stabilizer configured to partition an inlet-side air duct and an outlet-side air duct inside a main body; a cross-flow fan arranged between the inlet-side air duct and the outlet-side air duct; a ventilation resistor arranged inside the main body; and a guide wall configured to guide air discharged from the cross-flow fan to an air outlet of the main body, the cross-flow fan being the above-mentioned cross-flow fan according to the one embodiment of the present invention.

Advantageous Effects of Invention

According to the one embodiment of the present invention, it is possible to alleviate the non-uniform flow between the pair of support plates.

Brief Description of Drawings

FIG. 1 is a view for illustrating an installing state of an air conditioner according to a first embodiment of the present invention when viewed from the interior of a room.
FIG. 2 is a vertical sectional view of the air conditioner of FIG. 1.
FIG. 3 is a view for illustrating a front side and a lateral side of an impeller of a cross-flow fan to be mounted on the air conditioner of FIG. 1.
FIG. 4 is a perspective view of a single blade of the impeller of the cross-flow fan when viewed from a surface on an impeller rotational direction side (blade pressure surface).
FIG. 5 is a view for illustrating a blade lateral shape taken along the line A-A in FIG. 3 and a blade lateral shape taken along the line B-B in FIG. 3.
FIG. 6 is a cross-sectional view of a blade of the cross-flow fan at a center portion between a pair of rings in a rotational axis direction.
FIG. 7 is a cross-sectional view of the blade of the cross-flow fan at the center portion between the pair of rings in the rotational axis direction.
FIG. 8 is a cross-sectional view of the blade of the cross-flow fan at the center portion between the pair of rings in the rotational axis direction.
FIG. 9 is a view for illustrating a second embodiment of the present invention in the same manner as in FIG. 3.
FIG. 10 is a view for illustrating the second embodiment of the present invention in the same manner as in FIG. 5.
FIG. 11 is a view for illustrating a third embodiment of the present invention in the same manner as in FIG. 3.
FIG. 12 is a view for illustrating the third embodiment of the present invention in the same manner as in FIG. 4.
FIG. 13 is a view for illustrating the third embodiment of the present invention in the same manner as in FIG. 5.
FIG. 14 is a view for illustrating a fourth embodiment of the present invention in the same manner as in FIG. 4.

Description of Embodiments

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

First Embodiment

FIG. 1 is an installation schematic view of an air conditioner having a cross-flow fan mounted thereon according to a first embodiment of the present invention when viewed from a room. FIG. 2 is a vertical sectional view of the air conditioner of FIG. 1. FIG. 3 is a view for illustrating a front side and a lateral side of an impeller of the cross-flow fan to be mounted on the air conditioner of FIG. 1.
As illustrated in FIG. 1, an air conditioner (indoor unit) 100 includes a main body 1 and a front panel 1b installed on the front side of the main body 1, which form an outer shape of the air conditioner 100. In this case, in FIG. 1, the air conditioner 100 is installed on a wall 11a of a room 11 that is a space to be air-conditioned. That is, FIG. 1 is an illustration of the air conditioner 100 of a wall-mounting type as an example, but the present invention is not limited to this mode. For example, a ceiling concealed type may be employed. Further, the air conditioner 100 is not limited to be installed in the room 11, and may be installed in a room of a building or a storehouse, for example.
As illustrated in FIG. 2, in a main body upper portion 1a forming the upper portion of the main body 1, a suction grille 2 configured to suck air inside the room into the air conditioner 100 is formed. On the lower side of the main body 1, an air outlet 3 configured to supply the conditioned air into the room is formed, and further a guide wall 10 configured to guide the air discharged from a cross-flow fan 8 described later to the air outlet 3 is formed.
As illustrated in FIG. 2, the main body 1 includes a filter (ventilation resistor) 5 configured to remove dust and the like in the air sucked through the suction grille 2, a heat exchanger (ventilation resistor) 7 configured to generate conditioned air by transferring hot or cold energy of refrigerant to air, a stabilizer 9 configured to partition an inlet-side air duct E1 and an outlet-side air duct E2, the cross-flow fan 8, which is arranged between the inlet-side air duct E1 and the outlet-side air duct E2, and is configured to suck air through the suction grille 2 and blow out air through the air outlet 3, and a vertical airflow-direction vane 4a and a lateral airflow-direction vane 4b configured to adjust the direction of the air blown out from the cross-flow fan 8.
The suction grille 2 is an opening through which the air inside the room is forcibly introduced into the air conditioner 100 by the cross-flow fan 8. The suction grille 2 is formed as an opening in the upper surface of the main body 1. The air outlet 3 is an opening through which air, which has been sucked through the suction grille 2 and passed through the heat exchanger 7, passes when the air is supplied into the room. The air outlet 3 is formed as an opening in the front panel 1b. The guide wall 10 forms the outlet-side air duct E2 in cooperation with the lower surface side of the stabilizer 9. The guide wall 10 forms a helical surface from the cross-flow fan 8 toward the air outlet 3.
The filter 5 is formed into, for example, a mesh shape, and is configured to remove dust and the like in the air sucked through the suction grille 2. The filter 5 is mounted on the downstream side of the suction grille 2 and on the upstream side of the heat exchanger 7 in the air duct from the suction grille 2 to the air outlet 3 (center portion inside the main body 1).
The heat exchanger 7 (indoor heat exchanger) functions as an evaporator to cool the air during cooling operation, and functions as a condenser (radiator) to heat the air during heating operation. The heat exchanger 7 is mounted on the downstream side of the filter 5 and on the upstream side of the cross-flow fan 8 in the air duct from the suction grille 2 to the air outlet 3 (center portion inside the main body 1). Note that, in FIG. 2, the heat exchanger 7 is shaped so as to surround the front side and the upper side of the cross-flow fan 8. However, this shape is merely an example, and the present invention is not limited thereto.
The heat exchanger 7 is connected to an outdoor unit of a known mode including a compressor, an outdoor heat exchanger, an expansion device, and the like, to thereby construct a refrigeration cycle. Further, as the heat exchanger 7, for example, a cross-fin type fin-and-tube heat exchanger including a heat transfer tube and a large number of fins is used.
The stabilizer 9 is configured to partition the inlet-side air duct E1 and the outlet-side air duct E2, and as illustrated in FIG. 2, the stabilizer 9 is mounted on the lower side of the heat exchanger 7. The inlet-side air duct E1 is positioned on the upper surface side of the stabilizer 9, and the outlet-side air duct E2 is positioned on the lower surface side of the stabilizer 9. The stabilizer 9 includes a drain pan 6 configured to temporarily accumulate dew condensation water adhering on the heat exchanger 7.
The cross-flow fan 8 is configured to suck air inside the room through the suction grille 2 and blow out conditioned air through the air outlet 3. The cross-flow fan 8 is mounted on the downstream side of the heat exchanger 7 and on the upstream side of the air outlet 3 in the air duct from the suction grille 2 to the air outlet 3 (center portion inside the main body 1).
The cross-flow fan 8 includes, as illustrated in FIG. 3, an impeller 8a made of a thermoplastic resin such as an AS resin (styrene-acrylonitrile copolymer) with glass fibers, a motor 12 configured to rotate the impeller 8 a, and a motor shaft 12a configured to transmit the rotation of the motor 12 to the impeller 8a. The impeller 8a itself rotates to suck the air inside the room through the suction grille 2 and send the conditioned air to the air outlet 3.
The impeller 8a is formed by coupling a plurality of impeller elements 8d to each other, and each of the impeller elements 8d includes a plurality of blades 8c and at least one ring (support plate) 8b fixed to the end portion side of the plurality of blades 8c. That is, in the impeller element 8d, each of the plurality of blades 8c extends from a side surface of an outer peripheral portion of the disc-shaped ring 8b so as to be substantially perpendicular to the side surface. In addition, the plurality of blades 8c are arrayed at predetermined intervals in the circumferential direction of the ring 8b. The impeller 8a is integrated by welding and coupling the plurality of impeller elements 8d to each other as described above.
The impeller 8a includes a fan boss 8e protruding on the inner (center) side of the impeller 8a. The fan boss 8e is fixed to the motor shaft 12a with a screw or the like. Further, in the impeller 8a, one side of the impeller 8a is supported by the motor shaft 12a via the fan boss 8e, and the other side of the impeller 8a is supported by a fan shaft 8f. Withthis, the impeller 8a rotates in a rotational direction RO about an impeller rotation center O of the impeller 8a under a state in which both end sides thereof are supported, which enables sucking of the air inside the room through the suction grille 2 and sending of the conditioned air through the air outlet 3. Note that, the impeller 8a is described in detail later.
The vertical airflow-direction vane 4a is configured to vertically adjust the direction of the air blown out from the cross-flow fan 8, and the lateral airflow-direction vane 4b is configured to laterally adjust the direction of the air blown out from the cross-flow fan 8. The vertical airflow-direction vane 4a is mounted on the downstream side with respect to the lateral airflow-direction vane4b. Note that, the vertical direction herein corresponds to the vertical direction of FIG. 2, and the lateral direction herein corresponds to a front-back direction of the drawing sheet of FIG. 2.
FIG. 4 is a perspective view of a single blade of the impeller of the cross-flow fan when viewed from a surface on an impeller rotational direction side (blade pressure surface). FIG. 5 is a view for illustrating a blade lateral shape taken along the line A-A in FIG. 3 and a blade lateral shape taken along the line B-B in FIG. 3.
As illustrated in FIG. 4 and FIG. 5, each of the plurality of blades 8c is constructed to have such a shape that an inner peripheral end portion 15b is advanced again in the rotational direction after being retreated in the rotational direction from one corresponding ring toward the other corresponding ring, and an outer peripheral end portion 15a is also advanced again in the rotational direction after being retreated in the rotational direction from one corresponding ring toward the other corresponding ring. In other words, as illustrated in FIG. 3 and FIG. 4, when the pressure surface of the blade 8c is viewed in a projective manner, the inner peripheral end portion 15b and the outer peripheral end portion 15a in each of the plurality of blades 8c have inverted V-shapes, respectively. Therefore, each of the inner peripheral end portion 15b and the outer peripheral end portion 15a is retreated most in the rotational direction at the center portion between a pair of rings in a rotational axis direction and is advanced more in the rotational direction at portions on both sides of the center portion as approaching to the rings. Further, as illustrated in FIG. 5, the blade 8c has a constant cross section (cross section in a direction orthogonal to the rotational axis) over the rotational axis direction, but the center portion in the rotational axis direction is displaced from portions facing the rings by an angle δ.
Further, in each of the plurality of blades 8c, as illustrated in FIG. 5, the blade outer diameter (distance between the outer peripheral end portion 15a to be described later and the rotational axis O) and the blade outer diameter (distance between the inner peripheral end portion 15b to be described later and the rotational axis O) are kept the same over the rotational axis direction. Further, the cross-sectional area shapes of the blades 8c are also kept the same over the rotational axis direction. In other words, each of the plurality of blades 8c is formed into such a three-dimensional shape as to advance or retreat in the impeller rotational direction while keeping the same blade cross section orthogonal to the impeller rotational axis.
Next, the cross-sectional shape of the blade 8c in the direction orthogonal to the rotational axis is described in detail. FIG. 6 to FIG. 8 are cross-sectional views of the blade of the cross-flow fan at the center portion between the pair of rings in the rotational axis direction.
As illustrated in FIG. 6 to FIG. 8, the outer peripheral end portion 15a and the inner peripheral end portion 15b of the blade 8c are each formed into an arc shape. Further, the blade 8c is formed so that the outer peripheral endportion 15a side is inclined forward in the impeller rotational direction RO with respect to the inner peripheral end portion 15b side. That is, when the blade 8c is viewed in the vertical cross section, a blade pressure surface 13a and a blade suction surface 13b of the blade 8c are curved in the impeller rotational direction RO as approaching from the impeller rotation center (rotational axis) O of the impeller 8a toward the outer side of the blade 8c.
A center of a circle corresponding to the arc shape formed in the outer peripheral end portion 15a is represented by P1 (also referred to as "arc center P1"), and a center of a circle corresponding to the arc shape formed in the inner peripheral end portion 15b is represented by P2 (also referred to as "arc center P2"). Further, when a line segment connecting together the arc centers P1 and P2 is represented by a blade chord line (blade chord) L, as illustrated in FIG. 8, the length of the blade chord line L is set to Lo (hereinafter also referred to as "blade chord length Lo").
The blade 8c includes the blade pressure surface 13a, which is a surface on the rotational direction RO side of the impeller 8a, and the blade suction surface 13b, which is a surface on an opposite side to the rotational direction RO side of the impeller 8a. In the vicinity of the center of the blade chord line L, the blade 8c has a concave shape curved in a direction from the blade pressure surface 13a toward the blade suction surface 13b.
Further, in the blade 8c, a radius of a circle corresponding to the arc shape on the blade pressure surface 13a side is different between the outer peripheral side of the impeller 8a and the inner peripheral side of the impeller 8a. That is, as illustrated in FIG. 7, the surface of the blade 8c on the blade pressure surface 13a side is a multiple-arc curved surface and includes an outer peripheral curved surface Bp1 in which a radius (arc radius) corresponding to the arc shape on the outer peripheral side of the impeller 8a is Rp1, and an inner peripheral curved surface Bp2 in which a radius (arc radius) corresponding to the arc shape on the inner peripheral side of the impeller 8a is Rp2. Further, the surface of the blade 8c on the blade pressure surface 13a side includes a flat surface Qp having a planar shape, which is connected to an inner peripheral end portion of the end portions of the inner peripheral curved surface Bp2.
As described above, the surface of the blade 8c on the blade pressure surface 13a side is formed in a manner that the outer peripheral curved surface Bp1, the inner peripheral curved surface Bp2, and the flat surf ace Qp are continuously connected to one another. Note that, when the blade 8c is viewed in the vertical cross section, the straight line forming the flat surface Qp is a tangent at a point connected to the arc forming the inner peripheral curved surface Bp2.
On the other hand, the surface of the blade 8c on the blade suction surface 13b side is a surface corresponding to the surface on the blade pressure surface 13a side. Specifically, the surface of the blade 8c on the blade suction surface 13b side includes an outer peripheral curved surface Bs1 in which a radius (arc radius) corresponding to the arc shape on the outer peripheral side of the impeller 8a is Rs1, and an inner peripheral curved surface Bs2 in which a radius (arc radius) corresponding to the arc shape on the inner peripheral side of the impeller 8a is Rs2. Further, the surface of the blade 8c on the blade suction surface 13b side includes a flat surface Qs having a planar shape, which is connected to an inner peripheral end portion of the end portions of the inner peripheral curved surface Bs2.
As described above, the surface of the blade 8c on the blade suction surface 13b side is formed in a manner that the outer peripheral curved surface Bs1, the inner peripheral curved surface Bs2, and the flat surface Qs are continuously connected to one another. Note that, when the blade 8c is viewed in the vertical cross section, the straight line forming the flat surface Qs is a tangent at a point connected to the arc forming the inner peripheral curved surface Bs2.
Next, the blade thickness is described. When the blade 8c is viewed in the vertical cross section, and when a diameter of a circle inscribed in the blade surfaces is represented by a blade thickness (thickness) t, as illustrated in FIG. 7, a blade thickness (thickness) t1 at the outer peripheral end portion 15a is smaller than a blade thickness (thickness) t2 at the inner peripheral end portion 15b. Note that, the blade thickness t1 corresponds to 2 × radius R1 of the circle forming the arc of the outer peripheral end portion 15a, and the blade thickness t2 corresponds to 2 × radius R2 of the circle forming the arc of the inner peripheral end portion 15b.
In other words, when the diameter of the circle inscribed in the blade pressure surface 13a and the blade suction surface 13b of the blade 8c represents the blade thickness, the blade thickness is formed as follows. The blade thickness of the outer peripheral end portion 15a is smaller than that of the inner peripheral end portion 15b, and the blade thickness gradually increases as approaching from the outer peripheral end portion 15a toward the center to become maximum at a predetermined position in the vicinity of the center. Then, the blade thickness gradually decreases as approaching toward the inner side to become substantially the same thickness at a straight portion Q.
More specifically, in a range of the outer peripheral curved surface Bp1, the inner peripheral curved surface Bp2, the outer peripheral curved surface Bs1, and the inner peripheral curved surface Bs2 formed in the blade pressure surface 13a and the blade suction surface 13b excluding the outer peripheral end portion 15a and the inner peripheral end portion 15b, the blade thickness t of the blade 8c gradually increases as approaching from the outer peripheral end portion 15a toward the center of the blade 8c, becomes a maximum thickness t3 at the predetermined position in the vicinity of the center of the blade chord line L, and gradually decreases as approaching toward the inner peripheral end portion 15b. Then, in a range of the straight portion Q, that is, in a range between the flat surface Qp and the flat surface Qs, the blade thickness t is the inner peripheral end portion thickness t2 that is a substantially constant value.
In this case, a part of the blade 8c having the flat surfaces Qp and Qs of the inner peripheral end portion 15b as surfaces is referred to as the straight portion Q. That is, the blade suction surface 13b of the blade 8c is formed of the multiple arcs and the straight portion Q in a range from the outer peripheral side toward the inner peripheral side of the impeller.
The cross-flow fan having the above-mentioned configuration and the air conditioner having the cross-flow fan mounted thereon can achieve the following effects.
First, in the case where air is sucked to the inside from the outside of the cross-flow fan 8 (that is, in the case of a flow in the cross-flow fan 8 at the blades 8c that are located at an upper left position in the drawing sheet in FIG. 2, in other words, in the case of a flow at the blades 8c that are positioned on the inlet-side air duct E1 side), the air flows along each of the plurality of blades 8c from the outer peripheral end portion 15a toward the inner peripheral end portion 15b as indicated by the dotted arrows in FIG. 4. Therefore, the air flowing out from the inner peripheral end portion 15b toward the inside of the cross-flow fan 8 flows so as to diffuse toward a corresponding pair of rings 8b. Accordingly, as for the space between the pair of rings, in the cross-flow fan that tends to blow out relatively a large amount of flow from the vicinity of the center between the pair of rings, which is located away from the pair of rings, the flow can also be positively distributed to the vicinities of the pair of rings to achieve a uniform flow between the pair of rings.
On the other hand, in the case where air is blown out to the outside from the inside of the cross-flow fan 8 (that is, in the case of a flow in the cross-flow fan 8 at the blades 8c that are located at a lower right position in the drawing sheet in FIG. 2, in other words, in the case of a flow at the blades 8c that are positioned on the outlet-side air duct E2 side), the air flows from the inner peripheral end portion 15b toward the outer peripheral endportion 15a as indicated by the solid arrows in FIG. 4. Therefore, when flowing over the inner peripheral end portion 15b, the air is accompanied by a blade tip vortex with the inner peripheral end portion 15b as an end portion and flows along the blade 8c as a flow with suppressed separation. Such suppressed separation allows a uniform flow to be maintained in a promotive manner.
In addition, the following functions and effects can be obtained.

(1) The suction surface 13b of the blade 8c is formed of the multiple arcs and the straight portion Q in the range from the outer peripheral side toward the inner peripheral side of the impeller. Thus, when the blade 8c passes through the inlet-side air duct E1, the flow on the blade surface that is about to separate at the outer peripheral curved surface Bs1 reattaches onto the following inner peripheral curved surface Bs2 having a different arc radius.
(2) Further, the blade 8c has the flat surface Qs to generate a negative pressure. Therefore, the flow reattaches even when the flow is about to separate at the inner peripheral curved surface Bs2.
(3) Further, the blade thickness t is larger on the impeller inner peripheral side than on the impeller outer peripheral side, and hence the distance between the adjacent blades 8c is reduced.
(4) Further, the flat surface Qs is flat. Therefore, unlike the case of a curved surface, the blade thickness t does not abruptly increase as approaching toward the impeller outer periphery, and hence the frictional resistance can be suppressed.
(5) The pressure surface 13a of the blade 8c is also formed of the multiple arcs and the straight portion (flat surface) in the range from the outer peripheral side toward the inner peripheral side of the impeller. Thus, when air flows from the outer peripheral curved surface Bp1 toward the inner peripheral curved surface Bp2 having a different arc radius, the flow gradually accelerates to generate a pressure gradient on the suction surface 13b. Therefore, the separation is suppressed and no abnormal fluid noise is generated.
(6) Further, the flat surface Qp on the downstream side is a tangent to the inner peripheral curved surface Bs2. In other words, the blade 8c has the flat surface Qp on the downstream side, and hence the blade 8c is shaped so as to be bent by a predetermined angle with respect to the rotational direction RO. Therefore, unlike the case where the straight surface (flat surface Qp) is absent, the flow can be directed toward the suction surface 13b even when the blade thickness t2 of the inner peripheral end portion 15b is large. Thus, the wake vortex can be suppressed when air flows into the impeller from the inner peripheral end portion 15b.
(7) The blade 8c has the thick inner peripheral end portion 15b. Thus, separation is less liable to occur in various inflow directions in the outlet-side air duct E2.
(8) Further, the blade 8c has the maximum thickness in the vicinity of the center of the blade chord, which is positioned on the downstream side of the flat surface Qs. Therefore, when the flow is about to separate after passing along the flat surface Qs, the air flows along the inner peripheral curved surface Bs2 because the blade thickness t is gradually increased toward the vicinity of the center of the blade chord, which can suppress the separation.
(9) Further, the blade 8c has the inner peripheral curved surface Bs1 having a different arc radius on the downstream side of the inner peripheral curved surface Bs2. Therefore, the separation of the flow is suppressed, the effective outlet-side air duct from the impeller can be increased, the outlet airflow velocity is reduced and equalized, and the load torque applied to the blade surface can be reduced.
Further, according to this embodiment, advantageous effects are obtained over the related-art configurations disclosed in Patent Literature 1 to Patent Literature 3. First, in the configuration disclosed in Patent Literature 1, the blade becomes thinner in accordance with the position in the impeller rotational axis direction. Further, in the configuration disclosed in Patent Literature 2, the blade is formed into a tapered shape in which the blade has a smaller outer diameter and a larger inner diameter as the blade extends from the base on the blade ring side. Further, the blade tip portion is inclined in the rotational axis direction, and the blade outer diameter varies in the impeller longitudinal direction. Therefore, a flow directed from one ring toward the other ring in the impeller rotational axis direction is generated. Further, the space between the impeller and the stabilizer or the casing facing the impeller is enlarged in the rotational axis direction to increase the leakage loss of the flow, and the space varies in the impeller rotational axis direction to cause a flow from a region having a narrow space to a region having a wide space, thus further increasing the leakage loss. Further, the efficiency deterioration increases the motor power consumption. Further, two components are necessary in the configuration disclosed in Patent Literature 3. Further, the orientation of the blade inclination is alternately changed for each impeller element. Thus, regions where the flow concentrates in the vicinity of the ring and regions where the flow separates from the vicinity of the ring are alternately formed on a ring basis, and the blowing-out airflow velocity distribution varies from a sparse state to a dense state or vice versa at wide intervals on a two-ring basis. When dust and the like are deposited on the filter installed at the air inlet of the air conditioner to increase the pressure loss, the sparseness and denseness become significant to cause back flow in a wide sparse region in the worst case. Therefore, high-humidity air flows back during the cooling, which may cause dew condensation to discharge dew condensation water to the outside.
(10) In connection with those problems, according to this embodiment, the blade 8c is formed so that the inter-blade-ring center portions are retreated (or advanced) in the impeller rotational direction in the impeller rotational direction while the blade cross section orthogonal to the impeller rotational axis is the same. Thus, the space between the impeller and the stabilizer 9 facing the impeller is the same, and hence the flow leakage can be prevented from increasing due to a circular vortex g1 caused by a difference in the space in the longitudinal direction, though this increase of the flow leakage has been a problem in the above-mentioned related-art configuration. Accordingly, the power consumption of the motor to be driven can be reduced while achieving high efficiency.
(11) Further, the blade is retreated in the impeller rotational direction and each blade tip portion has a region that is inclined with respect to the impeller rotational axis. Therefore, when the blade passes in the vicinity of the stabilizer 9 facing the impeller, the flow is dispersed in the entire region of each blade tip portion in the impeller longitudinal direction without pressure variations, thus reducing harsh rotational noise (NZ noise) due to the number of rotations and the number of blades. Accordingly, the noise can be reduced. As a result, the separation of the flow from the blade surface can be suppressed on the inlet side and the outlet side of the impeller. Therefore, the noise can be reduced, and further the power consumption of the fan motor can be reduced. In other words, an indoor unit 100 having a quiet and energy-saving cross-flow fan 8 mounted thereon can be obtained.

Second Embodiment

Next, a second embodiment of the present invention is described with reference to FIG. 9 and FIG. 10. FIG. 9 and FIG. 10 are views for illustrating the second embodiment of the present invention in the same manner as in FIG. 3 and FIG. 5, respectively. The configuration in the second embodiment is the same as that in the above-mentioned first embodiment except for portions to be described below.
In short, the second embodiment has an inverse relationship with the above-mentioned first embodiment in the above-mentioned form indicated by the V-shape. According to the second embodiment, each of a plurality of blades 108c is constructed to have such a shape that the inner peripheral end portion 15b is retreated again in the rotational direction after being advanced in the rotational direction from one corresponding ring toward the other corresponding ring, and the outer peripheral end portion 15a is also retreated again in the rotational direction after being advanced in the rotational direction from one corresponding ring toward the other corresponding ring. In other words, when the pressure surface of the blade 8c is viewed in a projective manner, the inner peripheral end portion 15b and the outer peripheral end portion 15a in each of the plurality of blades 8c have V-shapes, respectively. Therefore, each of the inner peripheral end portion 15b and the outer peripheral end portion 15a is advanced most in the rotational direction at the center portion between the pair of rings in the rotational axis direction and is retreated more in the rotational direction at portions on both sides of the center portion as approaching to the rings.
The second embodiment configured as described above can also achieve the same functions as in the first embodiment regarding the air flow. In other words, in each of the plurality of blades 108c, in a case where air is sucked to the inside from the outside of the cross-flow fan 8, when flowing over the outer peripheral end portion 15a, the air is accompanied by a blade tip vortex with the outer peripheral end portion 15a as an end portion and flows along the blade 108c as a flow with suppressed separation, thereby allowing a uniform flow to be maintained in a promotive manner. In a case where air is blown out to the outside from the inside of the cross-flow fan 8, the air flowing out from the outer peripheral end portion 15a toward the outside of the cross-flow fan 8 flows so as to diffuse toward a corresponding pair of rings 8b, and the flow can also be positively distributed to the vicinities of the pair of rings to achieve a uniform flow between the pair of rings.

Third Embodiment

Next, a third embodiment of the present invention is described with reference to FIG. 11, FIG. 12, and FIG. 13. FIG. 11, FIG. 12, and FIG. 13 are views for illustrating the third embodiment of the present invention in the same manner as in FIG. 3, FIG. 4, and FIG. 5, respectively. The configuration in the third embodiment is the same as that in the above-mentioned first embodiment except for portions to be described below.
In short, each blade according to the third embodiment has the same form as in the above-mentioned first embodiment as indicated by the V-shape, and further, portions of each blade in the vicinities of a corresponding pair of rings (ring-side portions) extend along the rotational axis direction (are not advanced or retreated in the rotational direction). In other words, as illustrated best in FIG. 12, each of a plurality of blades 208c has ring-side portions 220 at portions in a predetermined range from the rings as portions in the vicinities of the corresponding pair of rings. The ring-side port ions 220 extend along the rotational axis direction without being advanced or retreated in the rotational direction.
The third embodiment configured as described above can also achieve the same functions as in the first embodiment regarding the air flow. Further, according to the third embodiment, each of the plurality of blades achieves the following advantages due to the pair of ring-side portions that extend along the rotational axis direction without being advanced or retreated in the rotational direction. In other words, when the plurality of impeller elements are stacked together and blades of one impeller element are welded to the ring of another stacked impeller element, the blade tips are upright and hence come into contact with the ring surface in an upright state. Accordingly, the weldability is improved while achieving good assembling workability. Further, the blade parallel portions (ring-side portions) at both ends have no inclination to suppress concentration or dispersion of the flow on or from the ring surface, thus stabilizing the flow in the vicinity of the ring. In this way, a uniform airflow velocity distribution can be achieved and back flow can be prevented from occurring even when dust and the like are deposited on the filter installed at the air inlet of the air conditioner to increase the pressure loss. Therefore, a high-quality air conditioner causing no dew condensation also during the cooling can be obtained.
Although the third embodiment is described above in an illustrative manner as a combination with the first embodiment, the third embodiment may also be carried out in combination with the second embodiment. In other words, the above-mentioned second embodiment may be carried out so that the ring-side portions 220 extending along the rotational axis direction without being advanced or retreated in the rotational direction are formed in each blade 108c at portions in the vicinities of the corresponding pair of rings.

Fourth Embodiment

Next, a fourth embodiment of the present invention is described with reference to FIG. 14. FIG. 14 is a view for illustrating the third embodiment of the present invention in the same manner as in FIG. 4. The configuration in the fourth embodiment is the same as that in the above-mentioned first embodiment except for portions to be described below.
In the above-mentioned first to third embodiments, the mode set so that each of the inner peripheral end portion and the outer peripheral end portion in each of the plurality of blades is advanced again in the rotational direction after being retreated in the rotational direction, or the mode set so that each of the inner peripheral end portion and the outer peripheral end portion in each of the plurality of blades is advanced again in the rotational direction after being retreated in the rotational direction is applied. However, the present invention is not limited thereto, but those modes set as described above may be applied to one or both of the inner peripheral end portion and the outer peripheral end portion at a plurality of portions. An example of the fourth embodiment as described above is illustrated in FIG. 14.
In a blade 308c of FIG. 14 as an example of the fourth embodiment, a mode set so that the inner peripheral end portion 15b is advanced again in the rotational direction after being retreated in the rotational direction is applied at only one portion. In other words, the inner peripheral end portion 15b is formed in the same manner as the inner peripheral end portion of each blade according to the first embodiment. On the other hand, in the outer peripheral end portion 15a of each blade 308c, the modes set as described above are applied at a plurality of portions. In each of the blade illustrated in the fourth embodiment and the blades illustrated in the above-mentioned first to third embodiments, both sides of the blade with respect to its center between the pair of rings in the rotational axis direction are constructed to have a symmetric form.
Also in the fourth embodiment as described above, the same functions and effects as in the above-mentioned first to third embodiments are obtained in each of corresponding portions in the inner peripheral end portion and the outer peripheral end portion of each blade.
In the description of the example illustrated in the fourth embodiment, the feature of the fourth embodiment is applied to the blade having the inverted V-shape according to the first embodiment. However, the fourth embodiment may also be carried out by applying the feature of the fourth embodiment to the V-shaped blade according to the second embodiment.
The details of the present invention have been described above specifically with reference to the preferred embodiments, but it is apparent that a person skilled in the art may employ various modifications based on the basic technical thoughts and teachings of the present invention.

Reference Signs List

1 main body, 8 cross-flow fan, 8a impeller, 8b ring (support plate), 8c, 108c, 208c, 308c blade, 9 stabilizer, 15a outer peripheral end portion, 15b inner peripheral end portion, 100 air conditioner

Claims

A cross-flow fan, comprising:
an impeller; and

a shaft configured to support the impeller in a rotatable manner,

the impeller comprising:
a plurality of support plates; and

a plurality of blades arranged between a corresponding pair of the support plates at intervals in a circumferential direction,

each of the plurality of blades being shaped such that an inner peripheral end portion is advanced again in a rotational direction after being retreated in the rotational direction from one corresponding support plate toward another corresponding support plate, or is retreated again in the rotational direction after being advanced in the rotational direction from the one corresponding support plate toward the another corresponding support plate,

the each of the plurality of blades being shaped such that an outer peripheral end portion is advanced again in the rotational direction after being retreated in the rotational direction from the one corresponding support plate toward the another corresponding support plate, or is retreated again in the rotational direction after being advanced in the rotational direction from the one corresponding support plate toward the another corresponding support plate.
A cross-flow fan according to claim 1, wherein the each of the plurality of blades comprises a pair of ring-side portions extending along a rotational axis direction without being advanced or retreated in the rotational direction.
An air conditioner, comprising:
a stabilizer configured to partition an inlet-side air duct and an outlet-side air duct inside a main body;

a cross-flow fan arranged between the inlet-side air duct and the outlet-side air duct;

a ventilation resistor arranged inside the main body; and

a guide wall configured to guide air discharged from the cross-flow fan to an air outlet of the main body,

the cross-flow fan comprising the cross-flow fan of claim 1 or 2.