EP2894345A1

EP2894345A1 - Cross-flow fan

Info

Publication number: EP2894345A1
Application number: EP13836035.9A
Authority: EP
Inventors: Satoshi Nakai; Hideshi Tanaka
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2012-09-04
Filing date: 2013-08-29
Publication date: 2015-07-15
Also published as: CN104603466A; EP2894345A4; WO2014038467A1

Abstract

To reduce flow path loss caused by an intermediate plate or the like without reducing the strength of a cross-flow fan. Plural blades (40) extend in a lengthwise direction from a disc-shaped or circular annular support plate. A ring portion (61) of an auxiliary ring (60) is positioned on a lengthwise direction intermediate section of the plural blades (40) and is disposed on the outside of outer ends (40a) of the plural blades (40). Plural connection portions (62) of the auxiliary ring (60) extend from the ring portion (61) as far as spaces between adjacent blades of the plural blades (40) and are joined to the blades (40) in the spaces between adjacent blades. Plural notch portions (40g) are formed in the outer ends (40a) of the blades (40).

Description

TECHNICAL FIELD

The present invention relates to a cross-flow fan.

BACKGROUND ART

Cross-flow fans used, for example, in air conditioners have disc-shaped or circular annular support plates that are disposed on both lengthwise direction ends and plural blades that extend in the lengthwise direction and are disposed between the support plates. Additionally, there are cases where, as described in patent document 1 (Japanese Patent Unexamined Publication No. H05-87086 ), for example, a disc-shaped or circular annular intermediate plate is disposed between both support plates in order to reinforce the strength of the plural blades.

SUMMARY OF THE INVENTION

In this connection, when many support plates are disposed, air friction loss ends up occurring due to the plural support plates, so when many support plates are disposed, flow path loss increases. However, if the number of support plates is reduced in order to reduce flow path loss caused by the support plates, the strength of the cross-flow fan ends up being reduced.
It is an object of the present invention to reduce flow path loss caused by a support plate or the like without reducing the strength of a cross-flow fan.

A cross-flow fan pertaining to a first aspect of the present invention comprises: a support plate; plural blades that extend in a lengthwise direction from the support plate and have plural notch portions formed in their outer ends; and an auxiliary ring having a ring portion that is positioned on a lengthwise direction intermediate section of the plural blades and is disposed on the outside of the outer ends of the plural blades and plural connection portions that extend from the ring portion as far as spaces between adjacent blades of the plural blades and are joined to the blades in the spaces between adjacent blades.
According to the cross-flow fan pertaining to the first aspect, the auxiliary ring is joined to the blades at the connection portions that extend only as far as the spaces between adjacent blades, so that flow path pressure loss is suppressed, and the auxiliary ring is joined to the blades at the lengthwise direction intermediate section of the plural blades and bundles together the plural blades, so that the strength of a fan block including the support plate and the plural blades can be reinforced. However, for that reason the blades of the fan block become longer and so noise such as wind noise increases. Therefore, by forming the notch portions in the outer ends of the blades, noise can be suppressed.
A cross-flow fan pertaining to a second aspect of the present invention is the cross-flow fan pertaining to the first aspect, wherein the auxiliary ring is disposed in a position where the notch portions of the plural blades are not formed.
According to the cross-flow fan pertaining to the second aspect, the auxiliary ring is disposed in a position where the notch portions are not formed, so the joint strength between the connection portions of the auxiliary ring and the blades can be increased and a drop in wind speed at the ring portion of the auxiliary ring can be suppressed.
A cross-flow fan pertaining to a third aspect of the present invention is the cross-flow fan of the second aspect, wherein intervals between the plural notch portions of the plural blades are set in such a way as to be larger at the place where the auxiliary ring is disposed than at places where the auxiliary ring is not disposed.
According to the cross-flow fan pertaining to the third aspect, the distance from the place where the auxiliary ring is disposed to the notch portions can be lengthened, mutual interference between the auxiliary ring and the notch portions can be reduced, and a drop in wind speed at the ring portion can be suppressed.
A cross-flow fan pertaining to a fourth aspect of the present invention is the cross-flow fan of any of the first aspect to the third aspect, wherein the auxiliary ring is molded integrally with the plural blades.
According to the cross-flow fan pertaining to the fourth aspect, the auxiliary ring and the plural blades are integrally molded, so assembly of these becomes unnecessary.
A cross-flow fan pertaining to a fifth aspect of the present invention is the cross-flow fan of any of the first aspect to the fourth aspect, wherein the thickness of the ring portion of the auxiliary ring becomes thinner heading from the inner peripheral side toward the outer peripheral side.
According to the cross-flow fan pertaining to the fifth aspect, the thickness of the ring portion becomes thinner heading toward the outer peripheral side, so loss caused by air flow at the ring portion can be reduced.
A cross-flow fan pertaining to a sixth aspect of the present invention is the cross-flow fan of any of the first aspect to the fifth aspect, wherein the plural connection portions of the auxiliary ring are joined to suction surfaces of the plural blades and are each formed in a triangular shape projecting inward from the ring portion, with one side of each of the connection portions having the triangular shape being joined to the suction surfaces of the blades.
According to the cross-flow fan pertaining to the sixth aspect, one side of each of the connection portions having the triangular shape is joined to the suction surfaces of the blades, so the joint sections can be enlarged, and, the pressure surface sides of the blades are not used for connection, so connection portions existing on the pressure surface sides of the blades can be reduced so that flow path loss that increases due to the connection portions can be kept low.
A cross-flow fan pertaining to a seventh aspect of the present invention is the cross-flow fan of any of the first aspect to the sixth aspect, wherein the shape of the notch portions of the plural blades is a delta shape that widens heading in the direction of the outer ends.
According to the cross-flow fan pertaining to the seventh aspect, by forming the notch portions in a delta shape, the vortex produced by the flow blown out from the fan is reduced and broken down so that noise can be reduced.
A cross-flow fan pertaining to an eighth aspect of the present invention is the cross-flow fan of any of the first aspect to the seventh aspect, wherein the shapes of the notch portions of the plural blades are made different from one another between at least one pair of adjacent blades.
According to the cross-flow fan pertaining to the eighth aspect, by making the shapes of the notch portions different between adjacent blades, the regularity in the flow of air produced by the notch portions can be disrupted, and air vibration produced by the notch portions can be reduced.
A cross-flow fan pertaining to a ninth aspect of the present invention is the cross-flow fan of any of the first aspect to the eighth aspect, wherein the spacing between mutually adjacent blades of the plural blades is made different in at least one place.
According to the cross-flow fan pertaining to the ninth aspect, by making the spacing between the adjacent blades different, the regularity in the movement of the blades can be disrupted and air vibration produced by the movement of the blades can be suppressed.
A cross-flow fan pertaining to a tenth aspect of the present invention is the cross-flow fan of any of the first aspect to the ninth aspect, wherein the support plate includes plural support plates, the auxiliary ring includes plural auxiliary rings, a fan block formed by integrally molding one of the support plates, one of the auxiliary rings, and the plural blades is plurally formed, and at least one pair of mutually adjacent fan blocks are fixedly attached to one another in such a way that the blades of the mutually adjacent fan blocks are a predetermined angle out of alignment so that the blades are not lined up in straight lines.
According to the cross-flow fan pertaining to the tenth aspect, by ensuring that the blades are not lined up in straight lines between the adjacent fan blocks, the regularity in the movement of the blades between the adjacent fan blocks can be disrupted and air vibration produced in accompaniment with the movement of the blades of the adjacent fan blocks can be suppressed.

In the cross-flow fan pertaining to the first aspect of the present invention, not only can flow path loss be reduced without reducing the strength of the cross-flow fan, but noise can also be suppressed.
In the cross-flow fan pertaining to the second aspect of the present invention, the auxiliary ring is disposed in a position where the notch portions are not formed, so a drop in the strength of the cross-flow fan and flow path loss can be reduced.
In the cross-flow fan pertaining to the third aspect of the present invention, the distance between the auxiliary ring and the notch portions can be lengthened and the effect of controlling a drop in wind speed at the ring portion of the auxiliary ring is enhanced.
In the cross-flow fan pertaining to the fourth aspect of the present invention, assembly of the auxiliary ring and the plural blades can be saved and thus costs can be reduced.
In the cross-flow fan pertaining to the fifth aspect of the present invention, the thickness of the ring portion is made thinner heading toward the outer peripheral side, so loss caused by air flow can be reduced and blowing characteristics can be improved.
In the cross-flow fan pertaining to the sixth aspect of the present invention, because of the structure wherein one side of each of the connection portions having the triangular shape is joined to the suction surfaces of the blades, the effects of reducing flow path loss of the cross-flow fan and preventing strength from being reduced can be improved at the same time.
In the cross-flow fan pertaining to the seventh aspect of the present invention, the effect of reducing wind noise is improved.
In the cross-flow fan pertaining to the eighth aspect of the present invention, by making the shapes of the notch portions different between adjacent blades, wind noise can be reduced.
In the cross-flow fan pertaining to the ninth aspect of the present invention, by making the spacing between adjacent blades different, wind noise can be reduced.
In the cross-flow fan pertaining to the tenth aspect of the present invention, by ensuring that the blades are not lined up in straight lines between the adjacent fan blocks, wind noise can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing an overview of an indoor unit of an air conditioning apparatus;
FIG. 2 is a perspective view showing an overview of an impeller of a cross-flow fan pertaining to an embodiment;
FIG. 3 is a perspective view for describing a step in the assembly of the impeller of the cross-flow fan;
FIG. 4 is a plan view showing an example of the configuration of an end plate of the impeller;
FIG. 5 is a perspective view showing an example of the configuration of a fan block of the impeller;
FIG. 6 is a side view showing an example of the configuration of the fan block of the impeller;
FIG. 7 is a plan view showing an example of the configuration of a support plate of the fan block;
FIG. 8 is a cross-sectional view showing an example of the configuration of an auxiliary ring of the fan block;
FIG. 9 is a partially enlarged plan view for describing the configuration of the fan block shown in FIG. 5;
FIG. 10 is a partially enlarged side view for describing the configuration of the fan block shown in FIG. 6;
FIG. 11 is a side view showing another example of the configuration of the fan block of the impeller;
FIG. 12 is a side view showing another example of the configuration of the fan block of the impeller;
FIG. 13 is a side view showing another example of the configuration of the impeller; and
FIG. 14 is a perspective view showing the configuration of another fan block contrasted with the fan block of FIG. 5.

DESCRIPTION OF EMBODIMENT

A cross-flow fan pertaining to an embodiment of the present invention will be described below taking as an example a cross-flow fan installed in an indoor unit of an air conditioning apparatus.

(1) Cross-flow Fan in Indoor Unit

FIG. 1 is a drawing showing an overview of a cross section of an indoor unit 1 of an air conditioning apparatus. The indoor unit 1 is equipped with a main body casing 2, an air filter 3, an indoor heat exchanger 4, a cross-flow fan 10, vertical flaps 5, and a horizontal flap 6. As shown in FIG. 1, the air filter 3 is disposed on the downstream of an air inlet 2a in the top surface of the main body casing 2 and opposes the air inlet 2a. The indoor heat exchanger 4 is disposed on the downstream of the air filter 3. Room air that passes through the air inlet 2a and reaches the indoor heat exchanger 4 all passes through the air filter 3 and has dirt and dust removed from it.
The indoor heat exchanger 4 is configured as a result of a front surface side heat exchanger 4a and a back surface side heat exchanger 4b being coupled to one another so as to form an inverted V shape as seen in a side view. In a plan view seen from the top surface of the main body casing 2, the front surface side heat exchanger 4a is disposed in a position opposing substantially the front surface side half of the air inlet 2a, and the back surface side heat exchanger 4b is disposed in a position opposing substantially the back surface side half. Both the front surface side heat exchanger 4a and the back surface side heat exchanger 4b are configured by arranging numerous plate fins parallel to one another in the width direction of the indoor unit 1 and attaching them to heat transfer tubes. When the room air that has been sucked in from the air inlet 2a and passed through the air filter 3 travels between the plate fins of the front surface side heat exchanger 4a and the back surface side heat exchanger 4b, heat exchange takes place and air conditioning is performed.
On the downstream of the indoor heat exchanger 4, the substantially cylindrically shaped cross-flow fan 10 extends long along the width direction of the main body casing 2 and is disposed parallel to the width direction of the main body casing 2 together with the indoor heat exchanger 4. The cross-flow fan 10 is equipped with an impeller 20, which is disposed in a space surrounded so as to be sandwiched by the inverted V-shaped indoor heat exchanger 4, and a fan motor (not shown in the drawings) for driving the impeller 20. The cross-flow fan 10 generates an air flow as a result of the impeller 20 being rotated in direction A1 (clockwise) indicated by the arrow in FIG. 1.
An outlet passage leading to an air outlet 2b downstream of the cross-flow fan 10 has a back surface side configured by a scroll member 2c. The scroll member 2c has substantially the same width as the open portion of the air outlet 2b in the main body casing 2 as seen in a front view. The upper end of the scroll member 2c is positioned higher than the upper end of the cross-flow fan 10 and, as seen in a side view, is positioned in a location offset toward the back surface side of the central axis of the cylindrical cross-flow fan 10. The lower end of the scroll member 2c is coupled to the open end of the air outlet 2b. A guide surface of the scroll member 2c has, in order to smoothly and quietly guide to the air outlet 2b the air blown out from the cross-flow fan 10, a smoothly curvilinear shape having a centre of curvature on the side of the cross-flow fan 10 as seen in a cross-sectional view.

(2) Schematic Structure of Impeller of Cross-flow Fan

FIG. 2 shows the schematic structure of the impeller 20 of the cross-flow fan 10. The impeller 20 is, for example, configured as a result of end plates 21 and 24 and three fan blocks 30 being joined to one another. The end plate 21 is disposed on one end of the impeller 20 and has a rotary shaft 22 made of metal on an axial centre O. Additionally, ordinarily a boss portion (not shown in the drawings) that becomes connected to a fan motor shaft (not shown in the drawings) is disposed in the central portion of the end plate 24, which is disposed on the other end of the impeller 20 and has blades 40 and an auxiliary ring 60. Alternatively, there are also cases where the end plate 24 disposed on the other end of the impeller 20 has another configuration, such as, for example, that end plate 24 being configured so as to have a member that combines with part of the fan motor and so as to have a metal shaft in its central portion. The rotary shaft 22 of the end plate 21 and the boss portion (or metal shaft) of the end plate 24 on the other end of the impeller 20 are supported so that the impeller 20 rotates about the axial centre O. For the end plate 21, one that is the same as what has conventionally been used is used. However, in order to apply the present invention, it is not necessary for the structure of the end plate 21 to be one that is the same as what has conventionally been used, and the structure of the end plate 21 can be appropriately changed.
Each fan block 30 is equipped with plural blades 40, a circular annular support plate 50, and an auxiliary ring 60. In the assembly of the impeller 20, the plural blades 40 of one fan block 30 are fused to the support plate 50 of an adjacent fan block 30 or the end plate 21. FIG. 3 shows a step in which two mutually adjacent fan blocks 30 are fused to one another. Ordinarily, the end plate 21 is first placed on a jig 103, distal end portions 40d of the blades 40 of a fan block 30 are fitted into recessed portions 23 in the end plate 21, a horn 102 is applied to the support plate 50 of the fan block 30, and ultrasonic fusing is performed. Next, as shown in FIG. 3, the distal end portions 40d of the blades 40 of a subsequent fan block 30 are fitted into recessed portions 51 in the support plate 50 of the fan block 30 that was just fused, the horn 102 is applied to the support plate 50 of the subsequent fan block 30 in the same way as before, and ultrasonic fusing is performed. At this time, the support plate 50 to be fused is chucked from its outer peripheral direction in such a way that it does not become uncentreed. This work is repeated so that finally the horn 102 is applied to the end plate 24 having the blades 40 and fusing is performed. As shown in FIG. 4, a number of recessed portions 23 equal to the number of the blades 40 are formed in the end plate 21 in order to position the blades 40 on the end plate 21 during this fusing. The recessed portions 23 each have a planar shape slightly larger than the cross-sectional shape of the blades 40, so the blades 40 fit into and are fitted together with the recessed portions 23. Among the plural recessed portions 23, there is just one recessed portion 23 in which a step portion 23a is formed in order to position the end plate 21 and the fan block 30.

(3) Detailed Configuration of Fan Block

FIG. 5 to FIG. 10 show the detailed configuration of the fan blocks 30 pertaining to the present embodiment. FIG. 5 is a perspective view showing one of the plural fan blocks 30 configuring the impeller 20 shown in FIG. 2, and FIG. 6 is a side view of that fan block 30. The fan block 30 shown in FIG. 5 and FIG. 6 comprises plural blades 40, a support plate 50, and an auxiliary ring 60 that are integrally molded by injection molding, for example, using a thermoplastic resin as their main material. The rotational direction of the fan block 30 is direction A1 indicated by the arrow in FIG. 5.

(3-1) Blades

The plural blades 40 extend in the lengthwise direction (the direction along the axial centre O) from a first surface 50a of the circular annular support plate 50. The blades 40 are molded integrally with the support plate 50, and thus blade base portions 40c are fixed to the first surface 50a of the support plate 50 and the sides of the blades 40 opposite the blade base portions 40c in the lengthwise direction become blade distal end portions 40d. A length L1 of the blades 40 (the dimension from the blade base portions 40c to the blade distal end portions 40d) is, for example, about 10 cm. The blades 40 have suction surfaces 40f and pressure surfaces 40e. When the fan block 30 rotates in direction A1 indicated by the arrow in FIG. 5, the pressure on the side of the pressure surfaces 40e of the blades 40 becomes higher and the pressure on the side of the suction surfaces 40f becomes lower.
Among the plural blades 40, there is just one blade 40 having a cutaway portion 40i formed in the blade distal end portion 40d. The cutaway portion 40i is for positioning two fan blocks 30 or a fan block 30 and the end plate 21, and is a section that fits together with the step portion 23a of the recessed portion 23 of the end plate 21 described above or a step portion 51c of a recessed portion 51 of the fan block 30 described later. Because there is the cutaway portion 40i, the blades 40 and the recessed portions 23 of the end plate 21 or the recessed portions 51 of the fan block 30 can be made to have a one-to-one correspondence with one another in this way. In other words, the cutaway portion 40i is disposed in order to bring the distal end portions 40d of the blades 40 and the recessed portions 51 into a one-to-one correspondence with one another and prevent mis-fitting in a case where the circumferential direction arrangement of the blades 40 is not uniform or a case where the shapes (thicknesses, inclinations, etc.) of the blades 40 are not uniform.

(3-2) Support Plate

FIG. 7 shows a state in which the circular annular support plate 50 is seen from its bottom surface, that is, a state in which the circular annular support plate 50 is seen from the side of a second surface 50b. Recessed portions 51 into which the blades 40 fit are formed in the second surface 50b, which is opposite the first surface 50a of the support plate 50. The recessed portions 51 each have a planar shape slightly larger than the cross-sectional shape of the blades 40, so when two fan blocks 30 are placed on top of one another, the blades 40 fit into and are fitted together with the recessed portions 51. A ring-shaped raised portion 52 higher than the second surface 50b is formed along the inner periphery of the support plate 50. The outer peripheral side of the raised portion 52 is slanted off of the horizontal plane, and the raised portion 52 fulfills the role of guiding the blades 40 to the recessed portions 51 when two fan blocks 30 are placed on top of one another.
An outer periphery 51 a of the recessed portions 51 that outer ends 40a of the blades 40 touch is located on the inside of an outer periphery 50c of the support plate 50, and inner ends 51 b of the recessed portions 51 that inner ends 40b of the blades 40 touch are located on the outside of an inner periphery 50d of the support plate 50. In other words, a distance d1 from the centre (a point on the axial centre O) of the support plate 50 to the outer periphery 51 a of the recessed portions 51 (the distance to the outer ends 40a of the blades 40) is smaller than a radius r1 from the centre of the support plate 50 to the outer periphery 50c. Furthermore, a distance d2 from the centre (a point on the axial centre O) of the support plate 50 to the inner ends 51 b of the recessed portions 51 (the distance to the inner ends 40b of the blades 40) is larger than a radius r2 from the centre of the support plate 50 to the inner periphery 50d. In order to keep high the strength with which the support plate 50 supports the blades 40, a width W1 (radius r1 - radius r2) of the support plate 50 is set larger than the radial direction distance (distance d1 - distance d2) from the outer ends 40a of the blades 40 to the inner ends 40b.

(3-3) Auxiliary Ring

The auxiliary ring 60 is positioned on the lengthwise direction intermediate section of the blades 40 and is located in a position away from the blade base portions 40c by a distance of 60% of the dimension from the blade base portions 40c to the blade distal end portions 40d (the length L1 of the blades 40). It is preferred that the position where the auxiliary ring 60 is disposed be away from the blade base portions 40c by a distance equal to or greater than 55% of the length L1 in order to improve the strength of the cross-flow fan 10 and facilitate the assembly step such as ultrasonic welding. However, it is not invariably necessary for the position where the auxiliary ring 60 is disposed to be away from the blade base portions 40c by a distance equal to or greater than 55% of the length L1, and it suffices for the auxiliary ring 60 to be positioned on the lengthwise direction intermediate section of the blades 40. As will be understood from the above description, a configuration where the auxiliary ring 60 is located in a position a little offset from the exact middle is also included in the concept of the lengthwise direction intermediate section of the blades 40.
FIG. 8 shows the cross-sectional shape of the section where the auxiliary ring 60 and the blades 40 are joined to one another. The cross section shown in FIG. 8 is a cross section that appears when the auxiliary ring 60 and the blades 40 are cut by a plane perpendicular to the axial centre O. In FIG. 9, the auxiliary ring 60, the blades 40, and the support plate 50 when looking from the blade distal end portions 40d of the blades 40 toward the blade base portions 40c are shown partially enlarged. The auxiliary ring 60 mainly comprises a ring portion 61, connection portions 62, and auxiliary connection portions 63. A radius r3 of an outer periphery 61 a of the ring portion 61 is larger than the radius r1 of the outer periphery 51 a of the support plate 50. Furthermore, the radius r3 of the outer periphery 61 a of the ring portion 61 is larger than the distance d1 from the centre (a point on the axial centre O) of the auxiliary ring 60 to the outer ends 40a of the blades 40. That is, the outer periphery 61 a of the ring portion 61 runs along the outside of the outer ends 40a of all the blades 40. A radius r4 of an inner periphery 61 b of the ring portion 61 of the auxiliary ring 60 is larger than the radius r2 of the inner periphery 50d of the support plate 50 and is slightly larger than the distance d1 to the outer ends 40a of the blades 40, and the inner periphery 61 b of the ring portion 61 runs along the neighborhood of the outside of the outer ends 40a of the blades 40.
The connection portions 62 are each formed in a triangular shape projecting inward from the ring portion 61 as seen in the direction of the axial centre O. The connection portions 62 having the triangular shape each have three vertex portions 62a, 62b, and 62c; the sides between the vertex portions 62a and 62b are connected to the ring portion 61, and the sides between the vertex portions 62a and 62c are connected to the suction surfaces 40f of the blades 40. The connection portions 62 are not connected to the pressure surfaces 40e of the blades 40. A length L4 of the sections where the connection portions 62 are connected to the suction surfaces 40f (the length from the vertex portions 62a to the vertex portions 62c) is shorter than 1/2 of a chord length L3. By setting the length L4 of the sections connected to the suction surfaces 40f shorter than 1/2 of the chord length L3, blowing characteristics are improved compared to a case where the length L4 is set longer than 1/2 of the chord length L3.
The auxiliary connection portions 63 are formed in the neighborhood of the outer ends 40a of the blades 40. The auxiliary connection portions 63 are sections filling in the spaces between the outer ends 40a of the blades 40, the connection portions 62, and the ring portion 61, and aid the connection of these three.
In FIG. 10, part of the auxiliary ring 60 as seen from the side is shown enlarged. The auxiliary ring 60 has a first surface 60a on the side of the blade distal end portions 40d, a second surface 60b on the side of the blade base portions 40c, an outer peripheral surface 60c, and an inner peripheral surface 60d. A curved surface 60e having a radius of curvature R1 is formed in the section interconnecting the first surface 60a and the outer peripheral surface 60c, and a curved surface 60f having a radius of curvature R2 is formed in the section interconnecting the second surface 60b and the outer peripheral surface 60c.
The thickness of the auxiliary ring 60 becomes thinner heading from the inner peripheral side toward the outer peripheral side. In other words, a thickness t2 of the auxiliary ring 60 at the outer peripheral surface 60c is smaller than a thickness t1 of the auxiliary ring 60 in the neighborhood of the blade base portions 40c. Seen in greater detail, an angle of inclination θ1 with which the first surface 60a of the auxiliary ring 60 intersects a plane perpendicular to the axial centre O is set so as to be larger than an angle of inclination θ2 with which the second surface 60b intersects this perpendicular plane. It will be noted that the thickness t1 of the auxiliary ring 60 is set smaller than a thickness t3 of the support plate 50.

(3-4) Notch Portions

As shown in FIG. 5 and FIG. 6, numerous notch portions 40g are formed in the blades 40. A recessed portion 40h is formed around each notch portion 40g. The notch portions 40g are formed in the outer ends 40a of the blades 40. The notch portions 40g each have a delta shape as seen from a direction perpendicular to the suction surfaces 40f of the blades 40 and widen heading toward the outer ends 40a. Because of this, in the fan blowing region, the trailing vortex can be reduced and broken down so that noise can be suppressed. In this fan block 30, a distance d3 between mutually adjacent notch portions 40g is set so as to be the same between any adjacent notch portions 40g.
The thickness of the V-shaped sections along the notch portions 40g is thinnest in the recessed portions 40h. For example, the thickness at the V-shaped sections is substantially equal to the thickness of the outer ends 40a of the blades 40. The recessed portions 40h surround the notch portions 40g in a C shape and gently slant from the suction surfaces 40f toward the notch portions 40g. In the recessed portions 40h, there is no unevenness from the suction surfaces 40f toward the notch portions 40g, so it is difficult for noise to occur. Furthermore, there are no steps from the suction surfaces 40f toward the notch portions 40g, so it is difficult for noise to occur.
The auxiliary ring 60 is disposed in a position where the notch portions 40g are not formed, between the two notch portions 40g located in the central portion of each of the blades 40.

(4) Example Modifications

(4-1)

In the above-described embodiment, a case was described where one auxiliary ring 60 is disposed on one fan block 30, but plural auxiliary rings 60 may also be disposed on one fan block 30.

(4-2)

In the above-described embodiment, a case was described where the radius r3 of the outer periphery 61 a of the ring portion 61 is larger than the radius r1 of the outer periphery 51 a of the circular annular support plate 50, but the radius r3 of the outer periphery 61 a of the ring portion 61 may also be set the same as the radius r1 of the outer periphery 51 a of the support plate 50.

(4-3)

In the above-described embodiment, a case was described where the radius r4 of the inner periphery 61 b of the ring portion 61 is slightly larger than the distance d1 to the outer ends 40a of the blades 40, but the radius r4 may also be configured to be equal to the distance d1 so that the inner periphery 61 b of the ring portion 61 runs along the outer ends 40a of the blades 40.

(4-4)

In the above-described embodiment, a case was described where the shape of the auxiliary ring 60 is circular annular, but the shape of the auxiliary ring 60 is not limited to being circular annular and may also, for example, be a polygonal shape having the same number of corners as the number of blades 40 or a shape having serrations (numerous indentations) in the outer peripheral end.

(4-5)

In the above-described embodiment, a case was described where, as shown in FIG. 6, the shapes of all the notch portions 40g of the fan block 30 are the same, but the shapes of the notch portions may also be made different. For example, like mutually adjacent blades 401 and 402 shown in FIG. 11, the shapes of their mutual notch portions 40g and 40j can be made different. It will be noted that the pair of blades 401 and 402 where the shapes of the notch portions are made different may be given a configuration where they are continuously disposed (a configuration where the blade 401 and the blade 402 appear alternately while making one circuit around the fan block 30), but they may also be disposed here and there in the fan block 30 as shown in FIG. 11.
By making the shapes of the notch portions 40g and 40j different between the adjacent blades 401 and 402, the regularity in the flow of air produced by the notch portions 40g and 40j can be disrupted. As a result, air vibration produced by the notch portions 40g and 40j can be reduced and wind noise can be reduced.
It will be noted that the concept here wherein the shapes of the notch portions are different is a concept that includes not only a case where, as shown in FIG. 11, the shapes of the notch portions are different in such a way that the notch portion 40j has a circular arc shape whereas the notch portion 40g has a delta shape but also a case where the notch portions have the same shape but differ only in size.
Furthermore, here, a case was described where the shapes of the notch portions 40g and 40j are different, but the shape of the recessed portions 40h may also be made different together with making the shapes of the notch portions 40g and 40j different, or the blades 40 can also be configured in such a way that just the shape of the recessed portions is made different between mutually adjacent blades 40.

(4-6)

In the above-described embodiment, a case was described where, as shown in FIG. 6, the pitch at which all the notch portions 40g of the fan block 30 are disposed (the distance d3 between mutually adjacent notch portions 40g) is the same, but the pitch at which the notch portions are disposed may also be made different. For example, as shown in FIG. 11, the pitch may also be set in such a way that a distance d4 at the place where the auxiliary ring 60 is disposed is larger than the distance d3 at places where the auxiliary ring 60 is not disposed.
When the pitch is set like it is in FIG. 11, the distance from the place where the auxiliary ring 60 is disposed to the notch portions 40g (a distance of about 1/2 of the distance d4) can be lengthened compared to the case of FIG. 6 (about 1/2 of the distance d3). As a result, mutual interference between the auxiliary ring 60 and the notch portions 40g can be reduced and the effect of suppressing a drop in wind speed at the ring portion 61 of the auxiliary ring 60 is enhanced.

(4-7)

In the above-described embodiment, a case was described where the spacing between the blades 40 is the same, but as shown in FIG. 12, spacings L5 and L6 between mutually adjacent blades 403, 404, 405, and 406 may also be made different. Here, just one place between the blade 405 and the blade 406 in one fan block 30 is made different. However, the place where the spacing between blades is made different may be plural per one fan block, and, for example, the space between the blade 403 and the blade 404 can also be set to a spacing L7 different from the spacings L4 and L5. The spacing between blades here is the distance from the position of the centre of gravity of the one blade 403 to the position of the centre of gravity of the adjacent blade 404 when seen in a cross section perpendicular to the central axis O.
In a case where the spacing between the blades 40 is the same, there is repeated a situation where the blades 40 exist in the same positions every amount of time (tf/nf) obtained by dividing the amount of time tf required for the fan block 30 to complete one rotation by the number nf of the blades 40 of the fan block 30. When the movement of the blades 40 is performed regularly in this way, it becomes easier for noise having a frequency corresponding to the value of nf/tf to occur. When the spacings L5 and L6 between the blades 403, 404, 405, and 406 are made different as shown in FIG. 12, there exists the blade 406 that is not in a position where a blade 40 formerly was after the amount of time (tf/nf), and the regularity in the movement of the blades 40 is disrupted. Because of that, air vibration produced by the movement of the blades 40 can be suppressed, and wind noise can be reduced.

(4-8)

In the above-described embodiment, as shown in FIG. 2, the blades 40 of the mutually adjacent fan blocks 30 are disposed in such a way as to be lined up in straight lines. However, the blades of the mutually adjacent fan blocks do not have to be lined up in straight lines. For example, like blades 407 and 408 of mutually adjacent fan blocks 310 and 320 shown in FIG. 13, the fan blocks 310 and 320 are ultrasonically fused to one another in a position where the blades 407 and 408 are a predetermined angle θ3 out of alignment so that they are not lined up in straight lines. By ensuring that the blades 407 and 408 are not lined up in straight lines between the adjacent fan blocks 310 and 320 in this way, the regularity in the movement of the blades 407 and 408 between the adjacent fan blocks 310 and 320 can be disrupted. As a result, air vibration produced in accompaniment with the movement of the blades 407 and 408 of the adjacent fan blocks 310 and 320 can be suppressed, and wind noise can be reduced.

(5) Characteristics

(5-1)

As described above, the ring portion 61 of the auxiliary ring 60 is positioned on the lengthwise direction intermediate section of the plural blades 40 and 401 to 408 and is disposed on the outside of the outer ends 40a of the plural blades 40 and 401 to 408. Furthermore, the plural connection portions 62 of the auxiliary ring 60 extend from the ring portion 61 as far as spaces between adjacent blades of the plural blades 40 and 401 to 408 and are joined to the blades 40 and 401 to 408 in the spaces between adjacent blades, and the plural notch portions 40g and 40j are formed in the outer ends 40a. The "spaces between adjacent blades" means, in other words, each region sandwiched between the pressure surface 40e of one blade 40 and 401 to 408 of the plural blades 40 and 401 to 408 and the suction surface 40f of the adjacent blade 40 and 401 to 408.
The auxiliary ring 60 is joined to the blades 40 and 401 to 408 at the connection portions 62 that extend only as far as the spaces between adjacent blades, so that flow path pressure loss is suppressed. At the same time, the circular annular ring portion 61 bundles together the plural blades 40 at the lengthwise direction intermediate section of the plural blades 40 and 401 to 408, so that the strength of the fan blocks 30, 310, and 320 including the circular annular support plate 50 and the plural blades 40 and 401 to 408 is reinforced.
The auxiliary ring 60 is joined to the blades 40 and 401 to 408 at the connection portions 62 that extend only as far as the spaces between adjacent blades, so that flow path pressure loss is suppressed. At the same time, the circular annular ring portion 61 bundles together the plural blades 40 and 401 to 408 at the lengthwise direction intermediate section of the plural blades 40 and 401 to 408, so that the strength of the fan blocks 30, 310, and 320 including the circular annular support plate 50 and the plural blades 40 and 401 to 408 is reinforced. Noise such as wind noise increases as a result of the blades 40 and 401 to 408 of the fan blocks 30, 310, and 320 becoming longer, but the noise is controlled by forming the notch portions 40g and 40j in the outer ends 40a of the blades 40 and 401 to 408.
A configuration will be considered where, for example, in order to obtain a block resembling the fan block 30 having the length L1, instead of the auxiliary ring 60, as shown in FIG. 14, two fan blocks 130 whose blades 140 are relatively short are joined to one another by a circular annular support plate 150. Here, the structure of the support plate 150 is the same as that of the support plate 50 described above. Comparing the two fan blocks 130 of FIG. 14 with the one fan block 30 of FIG. 5, their strength when configuring an impeller is substantially the same, but in the configuration of FIG. 14 the flow path loss of the two fan blocks 130 increases compared to the case of the auxiliary ring 60 because the support plate 150 is positioned in the middle of the blocks. Moreover, in the configuration of FIG. 14, an increase in costs relating to assembly is also conceivable because there is an added step for joining the two fan blocks 130 to one another.
It will be noted that, although in the above-described embodiment a case was described where the support plate 50 is circular annular, even if the support plate is disc-shaped it can be formed in the same way as in a case where it is circular annular, and even in a case where a disc-shaped support plate is used, effects that are the same as those in a case where the circular annular support plate 50 is used are achieved.

(5-2)

Specifically, the auxiliary ring 60 is disposed in a position where the notch portions 40g and 40j of the plural blades 40 and 401 to 408 are not formed. By giving the cross-flow fan this kind of configuration, the joint strength between the connection portions 62 of the auxiliary ring 60 and the blades 40 and 401 to 408 can be increased and a drop in wind speed at the ring portion 61 of the auxiliary ring 60 can be suppressed.

(5-3)

In the cross-flow fan 10 described above, the auxiliary ring 60 and the plural blades 40 and 401 to 408 are formed of resin, and the auxiliary ring 60 is molded integrally with the plural blades 40 and 401 to 408 by injection molding, for example. By molding the auxiliary ring 60 integrally with the plural blades, assembly of the auxiliary ring and the plural blades becomes unnecessary and costs can be reduced. Likewise, the support plate 50 is also formed of resin and is molded integrally with the auxiliary ring 60 and the plural blades 40 and 401 to 408 by injection molding, for example, at the same time as molding the plural blades 40 and 401 to 408 and the auxiliary ring 60. For that reason, the effect of reducing costs resulting from reducing the number of assembly man-hours becomes even greater.

(5-4)

Furthermore, the thickness of the ring portion 61 of the auxiliary ring 60 becomes thinner heading from the inner peripheral side toward the outer peripheral side. In other words, the thickness t1 on the inner peripheral side is larger than the thickness t2 on the outer peripheral side. For that reason, loss caused by air flow at the auxiliary ring 60 can be reduced and blowing characteristics can be improved. Furthermore, it is preferred that the thickness of the auxiliary ring 60 become thinner heading toward the outer peripheral side from the connection portions 62 to the ring portion 61. In this case also, blowing characteristics can be further improved. Moreover, because the thickness of the auxiliary ring 60 is thinner on the outer peripheral side than it is on the inner peripheral side, it becomes easier to remove the fan block 30 of the cross-flow fan 10 from the mold during injection molding.

(5-5)

Furthermore, the connection portions 62 are each formed in a triangular shape projecting inward from the ring portion 61. Additionally, one side (the side between the vertex portion 62a and the vertex portion 62c) of each of the connection portions 62 having the triangular shape is joined to the suction surfaces 40f of the blades 40 and 401 to 408. Because one side of each of the connection portions 62 having the triangular shape is joined to the suction surfaces 40f of the blades 40 and 401 to 408, the joint sections can be enlarged relative to the area of the connection portions 62. In addition, one of the vertices lies on the pressure surface side of other blades, so flow path loss that increases due to the connection portions can be kept low. Because of this structure, the effects of reducing flow path loss of the cross-flow fan 10 and preventing strength from being reduced can be improved at the same time. The sides of the connection portions 60 between the vertex portions 62a, 62b, and 62c are substantially linear, but each side may also be somewhat irregular.

(5-6)

The shape of the notch portions 40g of the plural blades 40, 401, and 404 to 408 is a delta shape that widens heading in the direction of the outer ends. By forming the notch portions 40g in a delta shape, the air flows smoothly and air vibration at the notch portions 40g is controlled compared to a case where the shape is a square U shape, for example. As a result, the effect of reducing wind noise is improved.

REFERENCE SIGNS LIST

10: Cross-flow Fan
20: Impeller
30, 310, 320: Fan Blocks
40, 401 to 408: Blades
50: Support Plate
60: Auxiliary Ring

CITATION LIST

Patent Document 1: Japanese Patent Unexamined Publication No. H05-87086

Claims

A cross-flow fan comprising:
a support plate (50);

plural blades (40, 401 to 408) extending in a lengthwise direction from the support plate and having plural notch portions (40g, 40j) formed in their outer ends; and

an auxiliary ring (60) having
a ring portion (61) positioned on a lengthwise direction intermediate section of the plural blades and disposed on the outside of the outer ends of the plural blades and
plural connection portions (62) extending from the ring portion as far as spaces between adjacent blades of the plural blades and joined to the blades in the spaces between adjacent blades.
The cross-flow fan according to claim 1, wherein the auxiliary ring is disposed in a position where the notch portions of the plural blades are not formed.
The cross-flow fan according to claim 2, wherein intervals between the plural notch portions of the plural blades are set in such a way as to be larger at the place where the auxiliary ring is disposed than at places where the auxiliary ring is not disposed.
The cross-flow fan according to any one of claims 1 to 3, wherein the auxiliary ring is molded integrally with the plural blades.
The cross-flow fan according to any one of claims 1 to 4, wherein the thickness of the ring portion of the auxiliary ring becomes thinner heading from the inner peripheral side toward the outer peripheral side.
The cross-flow fan according to any one of claims 1 to 5, wherein the plural connection portions of the auxiliary ring are joined to suction surfaces (40f) of the plural blades and are each formed in a triangular shape projecting inward from the ring portion, with one side of each of the connection portions having the triangular shape being joined to the suction surfaces of the blades.
The cross-flow fan according to any one of claims 1 to 6, wherein the shape of the notch portions of the plural blades is a delta shape that widens heading in the direction of the outer ends.
The cross-flow fan according to any one of claims 1 to 7, wherein the shapes of the notch portions of the plural blades are made different from one another between at least one pair of adjacent blades.
The cross-flow fan according to any one of claims 1 to 8, wherein the spacing between mutually adjacent blades of the plural blades is made different in at least one place.
The cross-flow fan according to any one of claims 1 to 9, wherein
the support plate includes plural support plates,
the auxiliary ring includes plural auxiliary rings,
a fan block formed by integrally molding one of the support plates, one of the auxiliary rings, and the plural blades is plurally formed, and
at least one pair of mutually adjacent fan blocks (310, 320) are fixedly attached to one another in such a way that the blades (407, 408) of the mutually adjacent fan blocks are a predetermined angle (θ3) out of alignment so that the blades are not lined up in straight lines.