DESCRIPTION

CROSS FLOW FAN

Technical Field

[0001] The present invention relates to a cross flow fan for use in an air conditioner that cools and heats a room.

Background Art

[0002] A cross flow fan for use in an indoor unit of an air conditioner for home use is desired to enhance an air-conveying performance (air volume, noise) in terms of miniaturization, electrical power saving and the like of the air conditioner. The cross flow fan is also desired to be operated at higher speeds or to further increase a variable range of speeds. To this end, blades of an impeller of the cross flow fan are made thin and, at the same time, the strength of the impeller itself is maintained by increasing a quantity of fiberglass or carbon fiber to be mixed into a resin material to form the impeller.

[0003] In recent years, an increase in diameter of the cross flow fan is also desired to increase the air volume of the indoor unit in terms of electrical power saving, but the increase in diameter is reaching a limit in terms of the impeller strength.

[0004] In view of this, another cross flow fan has been proposed that can be increased in size without detriment to the strength and working accuracy of the blades or impeller (see, for example, Patent Document 1).

[0005] Figs. 7 to 9 depict a construction of the cross flow fan as disclosed in Patent Document 1. As shown in Fig. 7, the cross flow fan 1 includes a plurality of impellers 2, an end plate 3 and an end plate 4, each of which is made by injection molding with the use of a resin. The plurality of impellers 2, the end plate 3 and the end plate 4 have respective connecting portions that are in abutment with and connected to one another by ultrasonic welding to complete the cross flow fan 1.

[0006] As shown in Fig. 8, each impeller 2 includes an annular base plate 5, a plurality of blades 6 extending from a side surface of the annular base plate 5 and arranged in a cylindrical form, and a ring plate 8 for connecting the plurality of blades 6 at respective inner edges (inner peripheral portions) of free ends employed as connecting portions 7. All the component parts are unitarily formed with one another by injection molding. The ring plate 8 has a plurality of protruding guides 8b unitarily formed therewith on an outer peripheral surface thereof and each having a guide surface 8a for guiding an adjacent impeller 2 during welding.

[0007] The ring plate 8 is intended to prevent the blades 6 from shifting in a circumferential direction or expanding in a radial direction upon application of a pressure during ultrasonic welding in order to ensure the dimensional accuracy and strength of the impeller 2 at a component level. A thickness L1 of the ring plate 8 is set to about 2 mm to minimize the influence on the air-conveying performance (air volume, noise) and a length L2 of the connecting portion 7 between the ring plate 8 and the blades 6 (i.e., a length of overlap between the outer peripheral surface of the ring plate 8 and the inner edges of the free ends of the blades 6) is set to about 1 mm. Also, each blade 6 has an airfoil cross-section. The connecting portion 7 of one of the two impellers 2 connected to each other has welding protrusions 6a formed therewith and the annular base plate 5 of the other of the two impellers 2 has a welding recess 6b defined therein.

[0008] The disc-shaped end plate 3 has a boss 3a formed along an axial central portion thereof, into and to which a motor shaft (not shown) is inserted and fixed, a welding recess 3b defined therein into which the welding protrusion 6a of each blade 6 is inserted, and a guide recess 3c defined therein to guide an adjacent impeller 2 during assemblage.

[0009] The disc-shaped end plate 4 located at the other end of the cross flow fan 1 opposite to the end plate 3 has a bearing (not shown) disposed at an axial central portion thereof, into which a shaft 4a is inserted, a welding protrusion 4b to be inserted into the welding recess 5b in the annular base plate 5, and a guide recess 4c defined therein to guide an adjacent impeller 2 during assemblage.

[0010] As shown in Fig. 9, such a conventional cross flow fan 1 is used in an indoor unit 100 of an air conditioner. The indoor unit 100 includes a heat exchanger 101, the cross flow fan 1 employed as an air-conveying means, a fan casing 103, an outer casing 104, a grille 105 and the like.

[0011] A method of assembling the conventional cross flow fan 1 of the above-described construction is explained hereinafter. The end plate 3 is first joined to one of the impellers 2 and, at this time, the outer peripheral surface 8a of the ring plate 8 of the impeller 2 is guided along and inserted into an inner peripheral surface 3d of the guide recess 3c in the end plate 3, and the welding protrusions 6a of the blades 6 are received in the welding recess 3b in the end plate 3 in readiness for subsequent connections. Thereafter, the blades 6 and the end plate 3 are connected together by ultrasonic welding. Because the ultrasonic welding technique of applying ultrasonic energy is well known, explanation thereof is omitted.

[0012] The impeller 2 connected to the end plate 3 is next connected to an adjacent impeller 2 of a shape completely identical to that of the impeller 2. A method of connecting them is the same as that of connecting the end plate 3 and the impeller 2 referred to above.

[0013] After multiple repetitions of the same procedure, the plurality of impellers 2 are connected to one another and the end plate 4 is eventually connected thereto to complete the cross flow fan 1. A method of connecting the end plate 4 is also the same as that of connecting the end plate 3 and the impeller 2 referred to above.

[0014] In the construction of the above-described conventional cross flow fan 1, because the ring plate 8 is located on an inner side of the blades 6 (inside the inner edges of the free ends), a radial length L3 of the ring plate 8 can be freely determined as required, thus making it possible to ensure a sufficient strength of the ring plate 8 and reduce a possibility that weld lines or whitening may occur on or in the ring plate 8 between the blades 6.

[0015] Operation of the indoor unit 100, in which the cross flow fan 1 of the above-described construction has been installed, is explained hereinafter.

[0016] The cross flow fan 1 is rotatably supported by a shaft and disposed within the fan casing 103 on a downstream side of the heat exchanger 101 with a predetermined gap (Y2) left between the cross flow fan 1 and the fan casing 103 behind it. The cross flow fan 1 is driven by a motor (not shown).

[0017] An outdoor unit (not shown) is connected to the indoor unit 100 via piping to define a refrigerating cycle in which a refrigerant is supplied from the outdoor unit to the heat exchanger 101. When the cross flow fan 1 is driven, air drawn from a room is cooled by the heat exchanger 101 and blown out in the form of a cold wind from a discharge opening 106.

[0018] In the cross flow fan 1 as disclosed in Patent Document 1, the ring plate 8 and the blades 6 are unitarily formed by injection molding such that the ring plate 8 for connecting the blades 6 together is connected to the inner edges of the blades 6. In a molded article formed by such injection molding, stepped parting lines are created on an outer surface thereof as a result of removal of molds. In the construction of the impellers 2 of Patent Document 1, the parting lines (unevenness) are created in the vicinity of the inner edges of the blades 6. Specifically, each of the blades 6 so molded has an uneven outer surface in a cross-sectional shape perpendicular to a rotational axis of the cross flow fan 1.

[0019] In view of this, a blade configuration as shown in Figs. 10 to 12 has been proposed in which a slope 16 is positively formed on each stepped portion 15, which is created in the vicinity of the inner edge of each blade 6 in contact with the ring plate 8, to reduce the stepped portion 15 (see, for example, Patent Document 2). Such a blade configuration can make the stepped portion 15 small to reduce turbulence components created on the stepped portion 15, thus making it possible to restrain a reduction in air-conveying performance and an increase in noise.

[0020]

Patent Document 1: JP 2002-31080 A

Patent Document 2: JP 2004-124819 A

Summary of the Invention

Problems to be solved by the Invention

[0021] In the conventional construction as disclosed in Patent Document 1 or 2, the cross flow fan can be increased in diameter while securing the strength of the blades of the cross flow fan, but the stepped portions created on the outer surfaces of the blades cannot be eliminated. That is, the conventional cross flow fan is provided with the ring plate to connect the blades of each impeller and is of a construction in which the ring plate and the blades are molded unitarily such that the inner edges of the blades are connected to the outer peripheral surface of the ring plate. In such a construction, the stepped portions (parting lines) are created on the outer surfaces of the blades upon removal of the molds.

[0022] Even if the slopes are provided on respective sides of each stepped portion, the stepped portions on the outer surface of each blade cannot be eliminated and cause flow separation, which in turn disturbs a flow within the impeller, thus posing a problem of reducing the air-conveying performance or increasing noise due to emission of a disturbed flow into a room.

[0023] The present invention has been developed to solve the above-described problems inherent in the conventional art and is intended to provide a cross flow fan that can be increased in diameter while securing the strength of the blades, eliminate the stepped portions from the outer surfaces of the blades to avoid flow separation, which has been hitherto caused by the stepped portions, and restrain a reduction in air-conveying performance and noise.

Means to Solve the Problems

[0024] In order to solve the problems inherent in the conventional art, the cross flow fan according to the present invention includes a plurality of impellers connected to one another in an axial direction and each having a plurality of blades arranged in a cylindrical form. Each impeller also has an annularly- or disc-shaped reinforcing plate having an outer diameter smaller than a diameter of inner edges of the plurality of blades arranged in the cylindrical form and further has a plurality of protrusions formed so as to protrude radially inwardly from the inner edges of respective blades. The blades, the protrusions and the reinforcing plate are characterized by a one-piece construction in which the reinforcing plate is connected to the inner edges of the blades via the protrusions.

Effects of the Invention

[0025] The cross flow fan according to the present invention can be increased in diameter while securing the strength of the blades, eliminate the stepped portions from the outer surfaces of the blades to avoid flow separation, which may be caused by the stepped portions, and restrain a reduction in air-conveying performance and noise.

Brief Description of the Drawings

[0026]

Fig. 1 is an exploded cross-sectional view of a cross flow fan according to a first embodiment of the present invention.

Fig. 2 is a cross-sectional view of an impeller of the cross flow fan according to the first embodiment.

Fig. 3 is a cross-sectional view of the impeller of Fig. 2 along a line A-A.

Fig. 4 is a cross-sectional view of an essential portion (portion (a) in Fig. 3) of the impeller according to the first embodiment, depicting a connecting portion of a blade, a protrusion and a reinforcing plate.

Fig. 5 is a cross-sectional view of the connecting portion of the blade, the protrusion and the reinforcing plate of Fig. 4 along a line B-B.

Fig. 6 is a cross-sectional view of an impeller of a cross flow fan according to a second embodiment of the present invention.

Fig. 7 is an exploded cross-sectional view of a conventional cross flow fan.

Fig. 8 is a perspective view of an impeller of the conventional cross flow fan.

Fig. 9 is a structural view of an interior of an air conditioner for home use employing the conventional cross flow fan.

Fig. 10 is a front view of another conventional cross flow fan.

Fig. 11 is a cross-sectional view of the cross flow fan of Fig. 10 along a lineX1-X2.

Fig. 12 is an enlarge view of a portion (b) of the cross flow fan of Fig. 11.

Embodiments for Carrying out the Invention

[0027] A first invention is directed to a cross flow fan that includes a plurality of impellers connected to one another in an axial direction and each having a plurality of blades arranged in a cylindrical form. Each impeller also has an annularly- or disc-shaped reinforcing plate having an outer diameter smaller than a diameter of inner edges of the plurality of blades arranged in the cylindrical form and further has a plurality of protrusions formed so as to protrude radially inwardly from the inner edges of respective blades. The blades, the protrusions and the reinforcing plate are unitarily formed such that the reinforcing plate is connected to the inner edges of the blades via the protrusions.

[0028] This construction allows the reinforcing plate to have an outer diameter smaller than an inner diameter of the blades. The provision of the protrusions for connecting the reinforcing plate to the blades can increase a diameter of the cross flow fan while securing the strength of the blades. Also, when the blades, the protrusions and the reinforcing plate are unitarily formed, stepped portions (parting lines) that are created upon removal of molds can be positioned on portions other than the blades, for example, on the protrusions located radially inwardly from the blades. Because of this, the cross-sectional shape of each blade has no unevenness and, accordingly, flow separation that
has been hitherto caused by the stepped portions can be avoided, thus making it possible to restrain a disturbance that may be caused by the flow separation and also restrain a reduction in air volume and an increase in noise. As a result, a cross flow fan that can be increased in diameter while securing the strength of the blades, restrain a disturbance on each blade and also restrain a reduction in air volume and an increase in noise can be realized.

[0029] In the cross flow fan according to the first invention, a second invention is such that the protrusions are each formed on an end portion of one of the blades in the axial direction of the impellers and connected to a side surface of the reinforcing plate.

[0030] This configuration allows the protrusions and the reinforcing plate to be formed at the end portions of the blades to reduce the influence on the air-conveying performance. Also, even if blades that are long in the axial direction of each impeller are employed, the cross flow fan can secure the strength of the blades.

[0031] In the cross flow fan according to the first or second invention, a third invention is such that parting lines created when the blades, the protrusions and the reinforcing plate are unitarily formed by injection molding with use of molds are not present between the inner edges and outer edges of the blades.

[0032] By this configuration, because any parting lines that cause flow separation are not present on the blade surfaces that exert an air-conveying effect, a disturbance that may be caused by the flow separation can be restrained, thereby making it possible to restrain a reduction in air volume and an increase in noise.

[0033] In the cross flow fan according to the third invention, a fourth invention is such that the parting lines are created on the protrusions.

[0034] This configuration allows the parting lines, which are created when the blades, the protrusions and the reinforcing plate are unitarily formed by injection molding with the use of molds, to be positioned on the protrusions, thereby making it possible to avoid formation of the stepped portions on the blades. Accordingly, a disturbance that may be caused by the flow separation can be restrained and a reduction in air volume and an increase in noise can also be restrained.

[0035] In the cross flow fan according to the fourth invention, a fifth invention is such that each blade and a corresponding one of the protrusions are formed such that a thickness of the blade and that of the protrusion reduce radially outwardly from the parting lines and the thickness of the protrusion increases radially inwardly from the parting lines.

[0036] This configuration allows the protrusion to be connected to the inner edge of the thinned blade along the outer surface thereof while ensuring the thickness of the protrusion required for a sufficient strength at the connecting portion between the reinforcing plate and the protrusion. Accordingly, the cross flow fan can be increased in diameter while, securing the strength of the blades and, at the same time, no stepped portions are created on the blades, thus making it possible to restrain flow separation.

[0037] In the cross flow fan according to any one of the third to fifth inventions, a sixth invention is such that each blade is in the form of a smooth airfoil shape having no unevenness from the inner edge to the outer edge and a connecting portion between the inner edge of the blade and the protrusion has a smooth surface.

[0038] By this configuration, no stepped portions are created on the blade and also on the connecting portion between the protrusion and the blade, thus making it possible to restrain flow separation.

[0039] In the cross flow fan according to any one of the first to sixth inventions, a seventh invention is such that a radially inwardly protruding length of the protrusion from the inner edge of the blade reduces with increasing distance from the reinforcing plate and a height of the protrusion in the axial direction of each impeller ranges from 1% to 15% of a height of the impeller in the axial direction thereof.

[0040] This configuration can restrain flow separation on the entire protrusion while securing a sufficient strength of the protrusion for connecting the reinforcing plate and the blade and also restrain a reduction in air volume and an increase in noise of the cross flow fan.

[0041] Embodiments of the present invention are described hereinafter with reference to the drawings, but the present invention is not limited to the embodiments.

(Embodiment 1)

[0042] Fig. 1 is an exploded cross-sectional view of a cross flow fan according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view of an impeller of the cross flow fan according to the first embodiment. Fig. 3 is a cross-sectional view of the impeller of Fig. 2 along a line A-A. Fig. 4 is a cross-sectional view of an essential portion of the impeller according to the first embodiment, depicting a connecting portion of a blade, a protrusion and a reinforcing plate. Fig. 5 is a cross-sectional view of the connecting portion along a line B-B. The same component parts as those of the cross flow fan as disclosed in the conventional art documents (Figs. 7 to 12) are designated by the same signs and explanation thereof is omitted.

[0043] As shown in Figs. 1 to 5, a cross flow fan 21 includes a plurality of impellers 22 connected to one another in an axial (rotational axis 21 x) direction and each having a plurality of blades 9 arranged in a cylindrical form. The cross flow fan 21 also includes an end plate 3 and an end plate 4 located at opposite ends thereof, respectively. Each impeller 22 has a disc-shaped reinforcing plate 10 disposed on an inner side thereof. The reinforcing plate 10 has a diameter smaller than an inner diameter of the plurality of blades 9 arranged in the cylindrical form (i.e., diameter of inner edges 9a of the blades 9). The reinforcing plate 10 is connected at a side surface thereof to the inner edges 9a of the plurality of blades 9 via respective protrusions 11. The plurality of blades 9, the reinforcing plate 10 and the protrusions 11 are unitarily formed by injection molding with the use of, for example, a resin. Because connections between the impellers 22 and connections between the impellers 22 and the end plates 3, 4 are the same as those in the cross flow fan as disclosed in the conventional art documents, explanation thereof is omitted.

[0044] A configuration of the blades 9, the reinforcing plate 10 and the protrusions 11 of each impeller 22 is explained in detail with reference mainly to Figs. 4 and 5. Each blade 9 has a protrusion 11 formed at one end portion 9x thereof (end portion opposite to the annular base plate 5) in an axial direction of the impeller 22 so as protrude radially inwardly from the inner edge 9a of the blade 9.

[0045] As shown in Fig. 4, the protrusion 11 is generally in the form of a
triangle as viewed from the front and has a protruding length from the inner edge 9a of the blade 9 that increases as it approaches the side surface of the reinforcing plate 10 and reduces as it approaches the side surface of the reinforcing plate 10. The reinforcing plate 10 is formed into a disc and connected at the side surface in the vicinity of an outer periphery thereof to the protrusions 11. An outer peripheral edge of the reinforcing plate 10 is positioned radially inwardly from the inner edges 9a of the blades 9.

[0046] As shown in Fig. 5, each blade 9 has a smooth airfoil shape having no unevenness between the inner edge 9a and an outer edge 9c. The protrusion 11 protruding radially inwardly from a portion of the inner edge 9a of the blade 9 has a shape resembling an extended form of the airfoil shape itself. In the impeller 22 according to the first embodiment, a surface of the end portion 9x of each blade 9 lies on the same plane as the side surface (side surface on the inner side of the impeller 22) of the reinforcing plate 10 in the axial direction.

[0047] Each of the protrusions 11 for connecting the reinforcing plate 10 and the inner edges 9a of the plurality of blades 9 has a stepped cross-sectional shape in a direction perpendicular to the rotational axis 21 x of the cross flow fan 21, the cross-sectional shape having stepped portions 12 on the side of the rotational axis 21 x. The stepped portions 12 are parting lines formed on the outer surface of each protrusion 11 by injection molds. As shown in Figs. 4 and 5, the stepped portions 12 are formed on the outer surface of the blade 9 so as to extend along an outer peripheral surface of the reinforcing plate 10.

[0048] The blade 9 and the protrusion 11 are formed such that the thickness of the blade 9 and that of the protrusion 11 reduce radially outwardly from the stepped portions 12 of the protrusion 11 and the thickness of the protrusion 11 increases radially inwardly from the stepped portions 12 of the protrusion 11.

[0049] Operation, functions and effects of the cross flow fan 21 of the above-described construction according to the first embodiment are explained hereinafter.

[0050] First, in forming the impeller 22, the outer diameter of the reinforcing plate 10 is made smaller than the diameter (inner diameter) of the inner edges 9a of the blades 9 and the protrusions 11 are provided to connect the reinforcing plate 10 to the blades 9. This configuration allows the impeller 22 to have an increased diameter and to be formed in a unified fashion while securing the strength of the blades 9.

[0051] Also, because the outer diameter of the reinforcing plate 10 is smaller than the inner diameter of the blades 9, the parting lines (i.e., stepped portions 12) that have been hitherto created on the outer surface of the reinforcing plate 10 upon removal of the molds used for injection molding can be created on the protrusions 11. That is, the stepped portions 12 can be created on the protrusions 11 by positioning the molds so that the parting lines may be positioned on the outer surface of the protrusions 11 and not on the blades 9 between the inner edges 9a and the outer edges 9c in cross-sectional shapes of the protrusions 11 perpendicular to the rotational axis 21 x of the cross flow fan 21. Because of this, the cross-sectional shape of each blade 9 (between the inner edge 9a and the outer edge 9c) has no unevenness and, hence, no parting lines are created on a pressure surface side 9p and also on a negative pressure surface side 9s between the inner edge 9a and the outer edge 9c of the blade 9, thus making it possible to avoid flow separation that may be caused by the stepped portions. Accordingly, the cross flow fan 21
employing therein the impellers 22 each formed in a unified fashion can restrain a disturbance that may be caused by flow separation, thereby making it possible to restrain a reduction in air volume and an increase in noise of the cross flow fan 1.

[0052] Also, because each blade 9 is in the form of a smooth airfoil shape having no unevenness from the inner edge 9a to the outer edge 9c, noise emitted from the blade 9 can be reduced.

[0053] Further, the formation of the stepped portions 12 on the outer surface of the protrusion 11 positioned radially inwardly from the inner edge 9a of the end portion 9x of the blade 9 can restrain flow separation and reduce noise as compared with the formation of the stepped portions on the outer surface of the blade 9.
[0054] In addition, the thickness of a radially outer portion of the protrusion 11 is gradually reduced radially outwardly from the stepped portions 12 of the protrusion 11 and the thickness of a radially inner portion of the protrusion 11 is gradually increased radially inwardly from the stepped portions 12. While maintaining a required strength at the connecting portion (i.e., inner peripheral portion 11a) between the reinforcing plate 10 and the protrusion 11, this configuration allows the protrusion 11 to be connected to the blade 9 so as to provide a smooth surface along the outer surface of the blade 9 of a thinned airfoil shape at the connecting portion (i.e., outer peripheral portion 11b) between the protrusion 11 and the inner edge 9a of the blade 9. Accordingly, no unevenness is created on the blade 9 to thereby restrain flow separation.

[0055] Also, at the end portions 9x (i.e., on the side of the end portions) of the plurality of blades 9 arrange in the cylindrical form opposite to the annular base plate 5 in an axial direction of the blades 9, the reinforcing plate 10 is connected to the inner edges 9a of the blades 9 via the protrusions 11. By this configuration, even if each impeller 22 is long in an axial direction thereof, the cross flow fan 21 can secure the strength of the blades 9.

[0056] Accordingly, the cross flow fan 21 according to the first embodiment can be increased in diameter while securing the strength of the blades 9 and, at the same time, any stepped portions 12 or parting lines are not created on the blades 9. Because of this, an indoor unit of an air conditioner accommodating such a cross flow fan 21 therein can increase the air volume, achieve electrical power saving, and minimize an increase in noise that may be caused by, for example, flow separation.

(Embodiment 2)

[0057] Fig. 6 is a view depicting an essential portion of an impeller 32 of a cross flow fan 31 according to a second embodiment of the present invention. The same component parts as those of the cross flow fan 21 according to the above-described first embodiment are designated by the same signs and explanation thereof is omitted.

[0058] As shown in Fig. 6, each protrusion 13 connected to the reinforcing plate 10 is formed such that a radially inwardly protruding length (a horizontal length in Fig. 6) from the inner edge 9a of the blade 9 gradually reduces with increasing distance from the reinforcing plate 10 in an axial direction. A height (h) of the protrusion 13 in the axial direction of the impeller 32 (a vertical length in Fig. 6) is determined so as to range from 1% to 15% of a height (H) of the blade 9 (impeller 32) in the axial direction (i.e., h/H=1-15%).

[0059] The above-described shape of the protrusion 13 with respect to the entire impeller 32 can reduce flow separation, which may be caused by the entire protrusion 13 or the stepped portions 12 formed on the protrusion 13, while securing a sufficient strength required for connection between the blade 9 and the reinforcing plate 10 and restrain a disturbance on the protrusion 13 that may be caused by the flow separation, thereby making it possible to minimize a reduction in air volume and an increase in noise of the cross flow fan 31.

[0060] Although in the above-described embodiments the reinforcing plate has been described as being disc-shaped, it may be annularly-shaped.

[0061] Also, although the surface of the end portion of each blade 9 lies on the same plane as the inner side surface of the reinforcing plate 10 in the axial direction, other various positional relationships may be employed. By way of example, when the impellers are connected to one another, the annular base plate 5 may be positioned so as to overlap with the reinforcing plate 10 in the axial direction. In such a configuration, the influence of the annular base plate 5 and the reinforcing plate 10 on the air-conveying performance can be reduced.

[0062] Further, it is sufficient if the parting lines (stepped portions 12) are formed on the outer surfaces of the protrusions and the positions of the former are not limited.

[0063] The connections between the impellers and the end plates may be those disclosed in the conventional art documents, but any other known connections may be employed.

[0064] Any combination of the various embodiments referred to above can produce respective effects.

[0065] Although the present invention has been fully described by way of preferred embodiments with reference to the accompanying drawings, it is to be noted here that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications otherwise depart from the scope of the present invention as set forth in the appended claims, they should be construed as being included therein.

[0066] The contents of a specification, drawings and claims of a Japanese patent application No. 2011-168102 filed August 1, 2011 are herein expressly incorporated by reference in their entirety.

Industrial Applicability

[0067] As described above, the cross flow fan of the construction according to the present invention can increase the diameter thereof while securing the strength of the blades and sufficiently restrain a reduction in air-conveying performance caused by a turbulent flow within the impeller and an increase in noise when the turbulent flow is discharged into a room. Also, the application of such a cross flow fan to an indoor unit of an air conditioner can increase the air volume from the indoor unit and achieve electrical power saving of the air conditioner.

[0068] Accordingly, the cross flow fan according to the present invention is applicable not only to a separate indoor unit of an air conditioner for home use and an indoor unit of an air conditioner for business use, but also to refrigerating equipment for business use and an air curtain for commercial or industrial use.

Explanation of reference numerals

[0069]

21.31 cross flow fan

22.31 impeller

9 blade

9a inner edge

9c outer edge

9x end portion

10 reinforcing plate

11,13 protrusion

11a inner peripheral portion of protrusion

11b outer peripheral portion of protrusion

12 stepped portion

CLAIMS

1. A cross flow fan comprising:

a plurality of impellers connected to one another in an axial direction;

each of the plurality of impellers having a plurality of blades arranged in a cylindrical form, an annularly- or disc-shaped reinforcing plate having an outer diameter smaller than a diameter of inner edges of the plurality of blades arranged in the cylindrical form, and a plurality of protrusions formed so as to protrude radially inwardly from the inner edges of respective blades; and

the blades, the protrusions and the reinforcing plate being unitarily formed such that the reinforcing plate is connected to the inner edges of the blades via the protrusions.

2. The cross flow fan according to claim 1, wherein the protrusions are each formed on an end portion of one of the blades in the axial direction of the impellers and connected to a side surface of the reinforcing plate.

3. The cross flow fan according to claim 1 or 2, wherein parting lines created when the blades, the protrusions and the reinforcing plate are unitarily formed by injection molding with use of molds are not present between the inner edges and outer edges of the blades.

4. The cross flow fan according to claim 3, wherein the parting lines are created on the protrusions.

5. The cross flow fan according to claim 4, wherein each blade and a corresponding one of the protrusions are formed such that a thickness of the blade and that of the protrusion reduce radially outwardly from the parting lines and the thickness of the protrusion increases radially inwardly from the parting lines.

6. The cross flow fan according to any one of claims 3 to 5, wherein each blade is in the form of a smooth airfoil shape having no unevenness from the inner edge to the outer edge and a connecting portion between the inner edge of the blade and the protrusion has a smooth surface.

7. The cross flow fan according to any one of claims 1 to 6, wherein a radially inwardly protruding length of the protrusion from the inner edge of the blade reduces with increasing distance from the reinforcing plate and a height of the protrusion in the axial direction of each impeller ranges from 1% to 15% of a height of the impeller in the axial direction thereof.