EP2270338B1

EP2270338B1 - Blower and heat pump device using same

Info

Publication number: EP2270338B1
Application number: EP09734028.5A
Authority: EP
Inventors: Yasuaki Kato; Takahide Tadokoro
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2008-04-22
Filing date: 2009-03-11
Publication date: 2018-11-14
Anticipated expiration: 2029-03-11
Also published as: EP2270338A1; ES2702364T3; CN102016327A; WO2009130954A1; US20110017427A1; EP2270338A4; JPWO2009130954A1; JP5213953B2

Description

Technical Field

The present invention relates to a propeller fan type blower provided with a bellmouth and an impeller and to a heat pump apparatus using such a blower and, more particularly, to improvement of a bellmouth structure.

Background Art

In order to provide a low-noise blower, it is necessary to minimize a turbulent air flow coming into a blower. Until now, various efforts have been made to improve the shape of a bellmouth to reduce blast noise emissions from a blower provided with a bellmouth and an impeller. For example, there has been proposed a bellmouth that increases a diameter in a bending fashion toward an upstream side from a straight pipe section having the smallest bellmouth diameter and has a straight section formed radially outwardly from its edge. Even if an air flow separation takes place at a rim of such a straight section, such air flow again attaches to the inner surface of the straight section while flowing therealong, and thereafter smoothly moves and is inhaled into the bellmouth, thereby reducing blast noise emissions (for example, see Patent Document 1).
Also, there has been proposed a bellmouth which has an inlet side wall having a cross-sectional shape which is a almost semi-circular shape curved toward a radially outward direction from the inner surface of an inlet opening, thereby suppressing separation of air flow at the inlet opening to reduce noise emissions when operating a fan (for example, Patent Document 2).
A bellmouth shape is proposed in such a way that, while keeping a front panel of the outdoor unit of an air conditioning apparatus rectangular, by changing the magnitude of a curvature of the upstream diameter expanding curved portion from the portion having the minimum bellmouth inner diameter in accordance with the distance between the top, bottom, left, and right peripheral side plates of a surrounding outdoor unit enclosure and the outer circumference of the impeller, an orifice shape can be set in accordance with a different inflow air flow angle in the vicinity of the impeller, separation of flow is reduced in the vicinity of the orifice, so that low noise is achieved. (For example, refer to Patent Document 3.)

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-184797 (Figs. 1 to 3)
[Patent Document 2] Japanese Patent No. 3084790 (Figs. 1 and 2)
[Patent Document 3] Japanese Patent No. 2769211 (Figs. 2 and 3)

JP-A-2003 184797 discloses a blower reducing blowing noises and an air conditioner comprising this blower. This blower has a bellmouth surrounding radial outside of a propeller fan and is formed comprising an extending part serially connecting the bellmouth with a straight part, a blow out side are part, a suction side org part and a large diameter end of the suction side are part and extending from these parts to the radial outside.
EP 1 357 337 A1 discloses a fan guard of a fan unit. This fan guard comprises an outer frame, a plurality of radiating ribs and a plurality of annular ribs.
DE 19751042 A1 discloses a fan having a smaller downstream distance between the fan and the obstacles like a motor or the like.
WO 01/96746 A1 discloses an automotive assembly having a high efficiency and low noise. This is achieved by flaring the inlet to the shroud barrel and shaping the tips of the fan blades to conform to the shape of the inlet.
JP-A-360251914 discloses a propeller fan mounted in an air purifier main body. This purifier main body has an air sucking port having a filter interposed thereto provided to the upstream side surface of that main body in the fan axial direction.
JP-B-2775796 further discloses a fan of an air conditioner placed within an air suction port.

Disclosure of Invention

Problems to be solved by the Invention

A bellmouth having a radially outwardly extending straight section formed at the rim, or having its inlet side wall curved in an almost semi-circular shape toward a radially outward direction from the inner surface of an inlet opening so as to reduce separation of air flow on the bellmouth incoming from the outer circumferential edge of a blade such as air flow incoming from a region concealed by the bellmouth when seen from a blade of the blower, can fulfill its function only when the blower is used under an ideal air passage environment, that is, an environment where air passage is circumferentially uniform about its rotation shaft. However, such an ideal air passage environment is rare as an actual air passage where the blower is operated. In addition, even if the air passage is circumferentially uniform about the rotation shaft, air flow coming into a blower is hardly stable and uniform. In fact, incoming air flow is always changing and significantly turbulent when viewed from a rotating blade, which makes it difficult for a blower to sufficiently fulfill its function.
Further, a blower having a bellmouth whose curvature changes according to un-uniformity resulting from a circumferential position of an inlet side air passage just reduces separation on the bellmouth, and is not effective in reducing the turbulence of incoming air flow, assuming that such a blower is mounted on an air conditioning apparatus.
An objective of the present invention is to reduce the turbulence of incoming air flow itself to obtain a low noise blower even if there is un-uniformity resulting from circumferential positions about the rotation shaft of the inlet side air passage.

Means for Solving the Problems

A blower according to the present invention comprises;
a blade having an outer circumferential edge having a recessed warp in a rotational direction, and
a bellmouth covering the circumference of the blade at an air outlet side,
wherein a surface of the bellmouth facing the blade has a first upstream expanding portion formed in a shape of a convex in an upstream direction of a rotation shaft, extending upstream from a minimum inner diameter position and a second upstream expanding portion formed in a shape of a concave in the upstream direction of the rotation shaft, being continuous with and extending upstream from the first upstream expanding portion.

Advantages

In a blower according to the present invention, a surface of the bellmouth facing the blade has a first upstream expanding portion formed in a shape of a convex in an upstream direction of a rotation shaft, extending upstream from a minimum inner diameter position and a second upstream expanding portion formed in a shape of a concave in the upstream direction of the rotation shaft, being continuous with and extending upstream from the first upstream expanding portion, whereby the outer circumferential edge of the blade is enclosed and a distance between the outer circumferential edge and the bellmouth becomes wider. This allows more air to be drawn in from around the outer circumferential edge, thereby preventing a pressure change on the bellmouth surface arising from turbulence by the blade tip vortex. In addition, this allows air passage around the outer circumferential edge of a blade to be circumferentially uniform, which suppresses fluctuation of air flow coming into the blade, leading to the achievement of a low-noise blower. Furthermore, this allows a section from the second upstream expanding portion to the minimum inner diameter point to form a smoothly continuous shape, which suppresses the turbulence of the air flow itself and effectively reduces noise levels.

Brief Description of Drawings

[Fig. 1] Fig. 1 is a front view of a blower according to Embodiment 1 of the present invention, as viewed from an outlet opening.
[Fig. 2] Fig. 2 is a cross-sectional view taken along the line A-A of Fig. 1.
[Fig. 3] Fig. 3 is a cross-sectional view taken along the line B-B of Fig. 1, whose outer circumferential edge is developed into a plane with lines indicating a position of each part in a bellmouth.
[Fig. 4] Fig. 4 is an enlarged partial view of Fig. 2.
[Fig. 5] Fig. 5 is the same view as Fig. 3, with the addition of a line illustrating the state of airflow in the vicinity of an outer circumferential edge of a blade.
[Fig. 6] Fig. 6 is the same view as Fig. 2, with the addition of lines indicating a conventional bellmouth for comparison.
[Fig. 7] Fig. 7(a) is a front view of an outdoor unit of an air conditioning apparatus according to Embodiment 2, 6 of the present invention. Fig. 7(b) is a cross-sectional view taken along the line C-C.
[Fig. 8] Fig. 8 is a view showing the direction of an air passage, as seen from the rotational shaft of an outdoor unit of an air conditioning apparatus according to Embodiment 2, 6 of the present invention.
[Fig. 9] Fig. 9(a) is a front view of an outdoor unit of an air conditioning apparatus according to Embodiment 3 of the present invention. Fig. 9(b) is a cross-sectional view taken along the line D-D. Fig. 9(c) is a cross-sectional view taken along the line E-E.
[Fig. 10] Fig. 10 is a view showing the direction of an air passage, as seen from the rotational shaft of an outdoor unit of an air conditioning apparatus according to Embodiment 3 of the present invention.
[Fig. 11] Fig. 11 is a partially enlarged cross-sectional view of a main section of a bellmouth and a propeller fan, as seen from an inlet side.
[Fig. 12] Fig. 12(a) is a front view of an outdoor unit of a heat pump water heater according to Embodiment 4 of the present invention. Fig. 12(b) is a cross-sectional view taken along the line F-F. Fig. 12(c) is a cross-sectional view taken along the line G-G.
[Fig. 13] Fig. 13 is an enlarged view of a main section of a blower according to Embodiment 5 of the present invention.
[Fig. 14] Fig. 14 is a view obtained by developing an outer circumferential edge of a blade of a blower according to Embodiment 5 of the present invention into a plane with the addition of leader lines indicating a position in a bellmouth as well as those indicating the state of air flow in the vicinity of the outer circumferential edge of a blade.
[Fig. 15] Fig. 15 is an enlarged view of a main section of a blower according to Embodiment 5 of the present invention, with a comparison with conventional one.
[Fig. 16] Fig. 16 is a comparison chart of aerodynamic noise properties of a heat pump apparatus according to Embodiment 7 of the present invention with conventional one.
[Fig. 17] Fig. 17 is a comparison chart of aerodynamic noise properties of a heat pump apparatus according to Embodiment 7 of the present invention with conventional one.
[Fig. 18] Fig. 18 is a diagram showing the shape of a blade of a propeller fan according to Embodiment 7 of the present invention.
[Fig. 19] Fig. 19 is a diagram showing the shape of a blade of a propeller fan according to Embodiment 7 of the present invention.

Reference Numerals

1: blade
1a: leading edge
1b: trailing edge
1c: outer circumferential edge
1d: pressure surface
1e: negative pressure surface
2: hub
3: propeller Pb1 point
Pb2: trailing edge end
Pb3: minimum inner diameter position
Pb4: point (transition position)
Pf1: point at intersection
Pf2: point at intersection
Pf3: maximum warpage position
Ld1-Ld11: dividing meridians
4: chord
5: bellmouth
5a: expanding portion
5b: minimum inner diameter portion
5c: first upstream expanding portion
5d: second upstream expanding portion
5e: third upstream expanding portion
6: baffle plate
7: fan motor
8: leakflow
9: blade tip vortex
10: rotational direction
11: convex shaped curved section
12: outdoor unit
13: air outlet face
14: air inlet face
15: heat exchanger (side face)
16: grill
17: top face of enclosure
18: bottom plate (side face)
19: Inboard air passage chamber
20: compressor
21: compressor chamber
22: separation plate (side face)
23: end warpage (curved surface)
24: waterheat exchanger
24a: top plate
25: outdoor unit and air inlet space and air outlet space
α: air inlet space
β: air outlet space

Best Modes for Carrying Out the Invention

Embodiment

1

Embodiment 1 of the present invention is described below with reference to the accompanying drawings.
Fig. 1 is a front view of a blower according to Embodiment 1 of the present invention, as viewed from an outlet opening. Fig. 2 is a cross-sectional view taken along the line A-A of Fig. 1. Fig. 3 is a cross-sectional view taken along the line B-B of Fig. 1, whose outer circumferential edge is developed into a plane with lines indicating a position of each part in a bellmouth. Fig. 4 is an enlarged partial view of Fig. 2. Fig. 5 is the same view as Fig. 3, with the addition of a line illustrating the state of airflow in the vicinity of an outer circumferential edge of a blade. Fig. 6 is the same view as Fig. 2, with the addition of lines indicating a conventional bellmouth for comparison.
In a blower according to the present embodiment, a propeller fan 3 having a plurality of blades 1 around a hub 2 is driven by a fan motor 7. The blade 1 is formed of a joining edge with the hub 2, a leading edge 1a facing a rotational direction, a trailing edge 1b opposed to the leading edge 1a, an outer circumferential edge 1c, which is opposed to the joining edge and connecting the leading edge 1a and the trailing edge 1b, and a curved surface surrounded by these joining edges, the leading edge 1a, the trailing edge 1b, and the outer circumferential edge 1c. The blade 1 has a pressure surface 1d facing the rotational direction 10 formed at one side thereof and a negative-pressure surface 1e formed at the other side thereof. Pf1 is a point at the intersection of the leading edge 1a with the outer circumferential edge 1c, while Pf2 is a point at the intersection of the trailing edge 1b with the outer circumferential edge 1c. The outer circumferential edge 1c has a concave warpage in the rotational direction, as shown in Fig. 3. Pf3 represents a maximum warpage position at which the distance between a chord 4 connecting Pf1 and Pf2 and the outer circumferential edge 1c is the largest.
In Figs. 2 and 4, lines of the blade 1 show a rotational trajectory of the leading edge 1a, the trailing edge 1b, and the outer circumferential edge 1c. A shaft about which the fan motor 7 and the propeller 3 rotate is referred to as a rotational shaft. A direction toward the air inlet side of the rotational shaft (the left side of Fig. 2) is set as an upstream direction of the rotation shaft, while a direction toward the air outlet side of the rotational shaft (the right side of Fig. 2) is set as a rotational downstream direction of the rotation shaft.
The outer periphery of the air outlet of the blade 1 is covered with a bellmouth 5. As shown in Fig. 4, the bellmouth 5 is located so as to cover the entire blade outer circumference or part of the trailing edge 1b. When classifying characteristics of each section of the bellmouth 5 by a cross-section shape in the blade side face, a section between Pb2 and Pb3 is a minimum inner diameter portion 5b that is the closest to the outer circumferential edge 1c of the blade 1 so as to cover the trailing edge 1b of the outer circumference edge 1c of the blade 1. A section from Pb2 to a Pb1 curves to form a downstream of expanding portion 5a for expanding an air passage toward the rotational downstream of the rotation shaft direction, and at Pb1 connects to a baffle plate 6 for separating an air outlet space β from an air inlet space α.
The bellmouth 5 has the following air passage expanding shape (contraction flow shape as seen from the air flow direction)in the inlet side direction. The bellmouth 5 has a convex shaped first upstream expanding portion 5c between Pb3 and Pb4, Pb3 being an upstream end of the rotation shaft of the minimum inner diameter portion 5b of the bellmouth 5. The bellmouth 5 has a concave shaped second upstream expanding portion 5d from Pb4 to Pb5, which follows the first upstream expanding portion 5c. The second upstream expanding portion 5d has a large curvature in the vicinity of Pb4, while it has a small curvature in the vicinity of Pb5, and has a substantially conic section in the vicinity of Pb5. In addition, the bellmouth 5 has a convex shaped third upstream expanding portion 5e from Pb5 to Pb6, which follows the second upstream expanding portion 5d.
Next, the positional relationship in the rotational shaft direction between the propeller fan 3 and the bellmouth 5 is described below with reference to Figs. 3 and 4. Dashed lines Lb3, Lb4, Lb5, and Lb6 in Fig. 3 represent positions of Pb3, Pb4, Pb5, and Pb6 in the rotational shaft direction in the bellmouth 5, respectively. In Fig. 4, a dashed line Lf3 represents a position in the rotational direction of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1. Pb3, the upstream end of the rotation shaft of the minimum inner diameter portion 5b of the bellmouth 5, is located upstream of the rotation shaft direction of the trailing edge end Pb2 in the outer circumferential edge 1c of the blade 1. Pb4 in the transition portion between the first upstream expanding portion 5c and the second upstream expanding portion 5d of the bellmouth 5 is located downstream of the rotation shaft direction of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1. In other words, a position in the rotation shaft direction of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1 is included within the range covered by the second upstream expanding portion 5d.
The operation of a blower according to the present embodiment is described using Figs. 1 to 5.
In the blower having the structure described above, the propeller fan 3, when driven by the fan motor 7, sends to the air outlet space β the air inside a region where the propeller fan 3 rotates and at the same time draws in the air in the air inlet space α to the region where the propeller 3 rotates. Gases enter the propeller fan 3 from the face formed of a rotational trajectory of the leading edge 1a and the face formed of the rotational trajectory of the outer circumferential edge 1c. In this way an air flow from the inlet side space α to the outlet side space β takes place.
As shown in Fig. 5, part of the gas entering the propeller fan 3 becomes a leak flow 8 to a negative pressure surface 1e from a pressure surface 1d via the outside of the outer circumferential edge 1c. A flow having a vortex structure called a blade tip vortex 9 takes place at a position along the outer circumferential edge 1c of the negative pressure surface 1e, originating from the leak flow 8 occurring in the vicinity of the leading edge of the outer circumferential edge 1c. The blade tip vortex 9 becomes larger as it moves toward the trailing edge side from the leading edge side, and moves away from the outer circumferential edge 1c in the vicinity of the maximum warpage position Pf3 at which a flow deflection becomes large. The blade tip vortex 9 having moved away from the outer circumferential edge 1c is pushed by the entire flow from the inlet side space α to the outlet side space β to gradually proceed to the outlet side space β and is discharged out of the blower as the structure of the vortex weakens.
The positional relationship in the downstream side between the bellmouth 5 and the outer circumferential edge 1c is described below. In order for the blower to generate a required flow rate, a pressure difference should be maintained between the inlet side space α and the outlet side space β depending upon the flow rate. The portion at which the distance between the blade 1 and the bellmouth 5 is smallest is the gap between the minimum inner diameter portion 5b from Pb2 to Pb3 and the outer circumferential edge 1c. In the present embodiment, such a gap is set at a position in the vicinity of the trailing edge 1b of the outer circumference edge 1c. If the gap is too large, the required pressure difference and flow rate cannot be attained when there is a greater air flow resistance before and after the blower. Accordingly, the present embodiment makes the gap between the bellmouth 5 and the blade 1 in the vicinity of the trailing edge 1b of the outer circumferential edge 1c smaller. Preferably, the gap is about one to three percent of the blade outer diameter (diameter of a rotation circle of the outer circumferential edge 1c).
The positional relationship in the upstream side between the bellmouth 5 and the outer circumferential edge 1c is described below. As described above, the face composed of the rotational trajectory of the outer circumferential edge 1c of the blade 1 is an air inlet face. Receiving incoming flow from a larger inlet area has an effect to reduce incoming flow speed at the same flow amount and reduce noise levels. Accordingly, it is preferable to make the distance between the outer circumferential edge 1c of the blade 1 and the bellmouth 5 sufficiently wide. The outer circumferential edge 1c of the blade 1 is also a place where the blade tip vortex 9 originates, grows, and moves away. The blade tip vortex 9 has large turbulence, and, if there is a wall such as a bellmouth 5 in the vicinity, a pressure change on the wall surface becomes so large that results in an increase in noise. To prevent these problems, it is preferable to make the distance between the bellmouth 5 and the outer circumferential edge 1c of the blade 1 in the upstream side sufficiently large.
A blower for practical use, however, it is quite rare that there is a wide area around the blade 1 in the inlet space α and the blade has a circumferentially uniform shape. Air flow to the blade tends to become circumferentially nonuniform and varies in terms of time, as seen from the rotating blade 1, causing an increase in noise. Accordingly, in order to achieve a low-noise blower, it is preferable to provide a circumferentially uniform air passage shape. More preferably, the outer circumferential edge 1c of the blade 1 is covered with the bellmouth 5.
In order to achieve a low-noise blower while maintaining the pressure difference between the inlet space α and the outlet space β, it is preferable to narrow the distance between the outer circumferential edge 1c of the blade 1 and the bellmouth 5 in the vicinity of the trailing edge 1b and to secure a wider space at a position closer to the upstream side to take in more air flow. In addition, in order to prevent a pressure change on the bellmouth wall surface resulting from the blade tip vortex 9, it is preferable while covering the outer circumferential edge 1c of the blade 1 to widen the distance between the outer circumferential edge 1c of the blade 1 and the bellmouth 5 to suppress an increase in noise arising from the nonuniform air passage shape.
In a blower according to the present embodiment, since following a convex-shaped first upstream expanding portion 5c formed upstream of the rotation shaft, there is the concave-shaped upstream second expanding portion 5d formed upstream of the rotation shaft, as is evident from Fig. 6, it is found that the distance between the outer circumference 1c of the blade 1 and the bellmouth 5 can be made larger while surrounding the outer circumference 1c of the blade 1 than the upstream expanding shape in a convex-shaped curved section 11 (shown by dashed line in the figure) upstream of the rotation shaft from inner diameter minimum portion conventionally employed in general. This allows more air to be drawn in from around the outer circumferential edge 1c of the blade 1, thereby preventing a pressure change in the bellmouth surface resulting from turbulence by the blade tip vortex 9. In addition, this allows air passage around the outer circumferential edge 1c of a blade 1 to be circumferentially uniform, which suppresses fluctuation of air flow coming into the blade 1, leading to the achievement of a low-noise blower. Furthermore, this allows a section from the upstream of the rotation shaft direction of the second upstream expanding portion 5d to the minimum inner diameter point Pb3 to form a smoothly continuous shape, which is effective in suppressing the turbulence of air flow and efficiently reduces noise.
Furthermore, the second upstream expanding portion 5d has a large curvature close to the first upstream expanding portion 5c and a smaller curvature at more upstream position and has a substantially conic section at the upstream portion, which allows for a wider opening area upstream of the rotation shaft of the second upstream expanding portion 5d, thereby guiding a large amount of air flow to the space between the outer circumferential edge 1c and the bellmouth 5. This enables a large-air-capacity, low-noise blower to be implemented. In addition to the second upstream expanding portion 5d, the blower has a convex-shaped third upstream expanding portion 5e upstream of the rotation shaft. The blower allows air entering from the end of the bellmouth to follow the third upstream expanding portion 5e for reduction in turbulence and guides it to the blade 1. As a result, a much lower-noise blower can be obtained.
An advantage of the relationship between the warpage of the outer circumferential edge 1c of the blade 1 and the expanded shape of the bellmouth 5 in the blower according to the present embodiment is described below. The blade tip vortex 9 undergoes significant fluctuation in the vicinity of the maximum warpage where the blade tip vortex grows and moves away, having great influence on a pressure change on the bellmouth wall surface. Here, the bellmouth 5 has the transition point Pb4 between the first upstream expanding portion 5c and the second upstream expanding portion 5d located downstream of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1, which results in a large distance between the outer circumferential edge 1c of the blade 1 and the bellmouth 5 in the vicinity of the maximum warpage point Pf3, thereby suppressing a pressure change on the bellmouth wall surface.
In addition, the location in the rotation shaft direction of the maximum warpage point Pf3 on the outer circumferential edge 1c of the blade 1 falls within the range covered by the second upstream expanding portion 5d, which reduces turbulent air flow around the blade tip vortex 9 when it moves away and also reduces the turbulence of the blade tip vortex 9, thereby suppressing the noise caused by the moving blade tip vortex 9.
Descriptions will be given to the case when the location in the rotation shaft direction of the maximum warpage point Pf3 on the outer circumferential edge 1c of the blade 1 falls within the range covered by the second upstream expanding portion 5d. A similar advantage is also provided when the maximum warpage point Pf3 is located within the range covered by the third upstream expanding portion 5e.

Embodiment 2

Figs. 7 and 8 show a heat pump apparatus, namely an air conditioning apparatus according to Embodiment 2 of the present invention. Fig. 7 (a) is a front view of a box-shaped outdoor unit of an air conditioning apparatus, while Fig. 7 (b) is a cross-section taken along the line C-C of Fig. 7 (a). Fig. 8 is a view showing the direction of air passage, as seen from the rotation shaft. The reference numerals and symbols in Fig. 7 refer to the same components as those with the same numerals and symbols in the above-described Embodiment 1. Reference is also made to Figs. 1 to 6 when describing a blower.
An air conditioning apparatus, namely, a box-shaped outdoor unit 12 according to the present embodiment includes an air outlet face 13 formed in the front face, an air inlet face 14 formed at two faces including its opposite face (back face) and one face on the left-hand side, and a L-shaped heat exchanger 15 disposed so as to cover the air inlet face 14. A blower is disposed close to the heat exchanger 15. Such a blower includes a blower according to above described Embodiment 1. The heat exchanger 15 includes a pipe having a multilayer fin for heat dissipation formed on an outer surface thereof, the pipe having a refrigerant circulating thereinside. The heat exchanger 15 does not necessarily have an L-shaped form, and may be provided on a back face only. In such a case, the side surrounding the air outlet face 13 on the box-shaped unit is formed of a plurality of side plates.
A grill 16 is disposed downstream of the rotation shaft of the blower, which protects a propeller fan 3 or protects a person from the rotating propeller fan 3. The air outlet face 13 and the bellmouth 5 are surrounded by the heat exchanger 15, top plate 17, bottom plate 18, and separating plate 22. The separating plate 22 separates an inboard air passage chamber 19 housing the blower inside the outdoor unit 12 from a compressor chamber 21 housing a compressor 20.
As shown in Fig. 3, a blade 1 of the propeller fan 3 has a concave-shaped warpage in the outer circumferential edge 1c in the rotational direction 10. As described in Fig. 4, with the bellmouth 5 surrounding the entire periphery side of the blade or trailing edge side of the propeller fan 3, a minimum inner diameter portion 5b having the shortest distance with the outer circumferential edge 1c of the blade 1 in the section from Pb2 to Pb3, covers a trailing edge 1b of the outer circumferential edge 1c in any of directions (i) to (viii) shown in Fig. 8. A downstream expanding portion 5a is provided whose air passage bends at a section from Pb2 to Pb1 to expand in the rotation shaft downstream direction. The air passage expanding shape (contraction flow shape as seen from the air flow direction) in the inlet direction includes a convex shaped first upstream expanding portion 5c between Pb3 and Pb4, Pb3 being an end point of upstream direction of the rotation shaft of the minimum inner diameter portion 5b. Also, the bellmouth 5 has a concave shaped second upstream expanding portion 5d from Pb4 to Pb5 upstream of the rotation shaft, which follows the first upstream expanding portion 5c. The second upstream expanding portion 5d has a large curvature in the vicinity of Pb4, while it has a small curvature in the vicinity of Pb5, and has a substantially conic section in the vicinity of Pb5, which is an upstream portion. Furthermore, the bellmouth 5 has a convex shaped third upstream expanding portion 5e in a section from Pb5 to Pb6, which follows the second upstream expanding portion 5d.
As described in Fig. 4, in the rotation shaft direction of the propeller fan 3 and the bellmouth 5, Pb3, an upstream end of the minimum inner diameter portion 5b of the bellmouth 5 in the rotation shaft direction, is located upstream of the rotation shaft direction of the trailing edge end Pb2 in the outer circumferential edge 1c of the blade 1. Pb4 in the transition between the first upstream expanding portion 5c and the second upstream expanding portion 5d is located downstream of the rotation shaft of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1. In other words, a position in the rotation shaft direction of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1 falls within the range covered by the second upstream expanding portion 5d.
An air conditioning apparatus, namely an outdoor unit 12 according to the present embodiment is described with regard to operation. When driven by the fan motor 7, the propeller fan 3 rotates to send the air inside the inboard air passage chamber 19, a region where the propeller fan 3 rotates, from the air outlet face 13 to the air outlet space β, and at the same time draws in the air in the air inlet space α from the air inlet face 14 through the fin of the heat exchanger 15, which enters the inboard air passage chamber 19 where the propeller fan 3 rotates. The heat exchanger 15 include a refrigerant having higher or lower temperature than the gas outside the exchanger circulating thereinside, providing heat exchange when the air outside the exchanger 15 passes therethrough. The air, which becomes warmer or colder after undergoing heat exchange by the heat exchanger 15 when entering the inboard air passage chamber 19, is blown out to the outside with the rotating propeller fan 3.
Air flow around the blade of the propeller fan 3 behaves in the same manner as that in Embodiment 1. That is, as shown in Fig. 5, part of the air entering the propeller fan 3 becomes a leak flow 8 to the negative pressure surface 1e from the pressure surface 1d via the outside of the outer circumferential edge 1c. A blade tip vortex 9 takes place at a position along the outer circumferential edge 1c of the negative pressure surface 1e, originating from the leak flow 8 occurring in the vicinity of the leading edge of the outer circumferential surface 1c. The blade tip vortex 9 grows as it transits to the trailing edge side from the leading edge side, and moves away from the outer circumferential edge 1c of the blade in the vicinity of the maximum warpage position Pf3 at which a flow deflection becomes large. The blade tip vortex 9 that left the outer circumferential edge 1c is pushed by an entire flow from the inboard air passage chamber 19 to the outside of the unit and is discharged out of the blower through the air outlet face 13, while weakening its vortex structure.
As described above, since an air conditioning apparatus according to the present embodiment employs the blower described above in Embodiment 1 as a blower for promoting heat exchanger by the heat exchanger 15 in the outdoor unit 12, it is characterized by the shape of the bellmouth 15 around the propeller fan 3 and the positional relationship between the propeller fan 3 and the bellmouth 5. Accordingly, in the same way as with the above described Embodiment 1, a great amount of air can be drawn in from the outer circumferential edge 1c of the blade 1 of the blower, which suppresses a pressure change on the surface of the bellmouth 5 arising from turbulence of the blade tip vortex 9. In addition, air passage around the outer circumferential edge 1c of the blade 1 can be circumferentially homogenized, which helps to suppress fluctuation of air entering the blade 1, leading to the achievement of a lower-noise blower.
A section between the upstream side of the rotation shaft of the second upstream expanding portion 5d and the minimum inner diameter point Pb3 can be constructed into a smoothly continued shape, which effectively suppresses turbulent of air flow and efficiently reduces noise. In particular, in a box-shaped outdoor unit 12, the distance to the end of air passage except the bellmouth 5 seen from the blade 1 is small, for example, in the direction of (i), (iii), (v), or (vii) in Fig. 8 and large in the direction of (ii), (iv), (vi), or (viii). An outdoor unit employing a conventional blower which has no sufficient distance between the bellmouth 5 and the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1 experiences significant fluctuation in incoming flow and the blade tip vortex 9 due to the change in air passage distance resulting from the rotation position of the blade 1. However the outdoor unit 12 employing a blower according to the present embodiment having a sufficient distance between the bellmouth 5 and the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1 is capable of preventing fluctuation of incoming flow of the air passage distance resulting from the rotation position of the blade 1, leading to a significant reduction in noise.
Also, a change in air flow at the rotational position of the blade 1 can be reduced, which results in reduction of a change of force exerted by the propeller fan 3 on the fan motor 7, leading to reduction of bearing wear or shaft deflection of the fan motor 7. This prolongs the durability of the outdoor unit 12 and helps to achieve the outdoor unit 12 that provides a stable quality during a long period of service.

Embodiment 3

In the above-described Embodiment 2, an air conditioning apparatus as a heat pump is described which has a bellmouth 5 around a propeller fan 3, the bellmouth 5 having a second upstream expanding portion 5d formed at the circumferential surface thereof and a third upstream expanding portion 5e formed upstream of the second upstream expanding portion 5d. An objective of the present invention can also be achieved by forming the second upstream expanding portion 5d and the third upstream expanding portion 5e only at a portion where the distance to the end of an air flow passage other than the bellmouth 5 seen from the blade 1 rapidly changes in the circumferential direction, for example, a portion (having a long distance to the end of the air flow passage) corresponding to a corner of a box-shaped outdoor unit 12. An outdoor unit 12 of a heat pump apparatus, namely an air conditioning apparatus having an upstream portion including the second upstream expanding portion 5d formed only in some portions of the circumferential direction of the bellmouth 5 is described below with reference to Figs. 9 to 11.
Fig. 9(a) is a front view of an outdoor unit of an air conditioning apparatus according to Embodiment 3 of the present invention. Fig. 9(b) is a cross-sectional view taken along the line D-D including its rotation shaft. Fig. 9(c) is a cross-sectional view taken along the line E-E. Fig. 10 is a view showing the direction of an air passage, as seen from the rotational shaft. Fig. 11 is a partially enlarged cross-sectional view of a main section of a bellmouth and a propeller fan, as seen from an inlet side. In each figure the same reference numerals and symbols are given to the same parts in Embodiments 1 and 2. Reference is also made to Figs. 1 to 6 to describe below a blower.
An air conditioning apparatus, namely a box-shaped outdoor unit 12 according to the present embodiment includes a blade 1 of a propeller fan 3 of its blower having a concave-shaped warpage (see Fig. 3) formed at the circumferential edge 1c thereof so as to warp in a rotational direction 10.
As shown in Fig. 9(a), the bellmouth 5 surrounding the entire periphery or the trailing edge of the propeller fan 3 has its upstream portion terminated at a first upstream expanding portion 5c (see Fig. 4) in a portion extending in any of directions (i), (iii), (v), and (vii) as shown in Fig. 10, namely in a portion having a smaller distance to an air flow passage other than the bellmouth 5. In contrast, the bellmouth 5 has a minimum inner diameter portion 5b being face-to-face with the trailing edge 1b of the outer circumferential edge 1c in a portion defined by lines extending in the directions of (ii) and (iv) in a section consisting of a separating plate 22, a top plate 17, and a bottom plate 18 and in a portion defined by lines extending in the directions of (vi) and (viii) in a section consisting of a heat exchanger 15, the bottom plate 18, and the top plate 17, the minimum inner diameter portion 5b being the closest to the outer circumferential edge 1c of the blade 1 in a section from Pb2 to Pb3, as described in Embodiment 1 with reference to, for example, Fig. 4. The bellmouth 5 has a downstream expanding portion 5a formed at a section from Pb2 to Pb1 so as to expand the air passage in the rotational shaft upstream direction. The air passage expanding shape (contraction flow shape as seen from the air flow direction) in the air inlet direction includes a convex shaped first upstream expanding portion 5c upstream of the rotation shaft between Pb3 and Pb4, Pb3 being an upstream end of the minimum inner diameter portion 5b. Also, the bellmouth 5 has a concave shaped second upstream expanding portion 5d from Pb4 to Pb5, which follows the first upstream expanding portion 5c. The second upstream expanding portion 5d has a large curvature in the vicinity of Pb4, while it has a small curvature in the vicinity of Pb5, and has a substantially conic section in the vicinity of Pb5. Furthermore, the bellmouth 5 has a convex shaped third upstream expanding portion 5e in a section from Pb5 to Pb6, which follows the second upstream expanding portion 5d.
As described in Embodiment 1, in the rotation shaft direction of the propeller fan 3 and the bellmouth 5, Pb3, an upstream end of the minimum inner diameter portion 5b, is located upstream of the trailing edge end Pb2 in the outer circumferential edge 1c in any of directions of (ii), (iv), (vi), and (viii). Pb4 in the transition between the first upstream expanding portion 5c and the second upstream expanding portion 5d is located downstream of the rotation shaft direction of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1. A position in the rotation shaft direction of the maximum warpage position Pf3 on the outer circumferential edge 1c of the blade 1 falls within the range covered by the second upstream expanding portion 5d.
An air conditioning apparatus according to the present embodiment that is an outdoor unit 12 is also characterized by the shape of the bellmouth 15 around the propeller fan 3 and the positional relationship between the propeller fan 3 and the bellmouth 5. Accordingly, as with the above described Embodiments 1 and 2, a great amount of air can be drawn in from the outer circumferential edge 1c of a blade 1 of a blower, which suppresses a pressure change on the surface of the bellmouth 5 arising from turbulence of the blade tip vortex 9.
A section between the upstream side of the second upstream expanding portion 5d and the minimum inner diameter point Pb3 can be constructed with a smoothly continued surface, which effectively suppresses turbulent air flow and efficiently reduces noise. In particular, in an outdoor unit 12, the second upstream expanding portion 5d and the third upstream expanding portion 5e cover the periphery of the blade in any of directions (ii), (iv), (vi), and (viii) as shown in Fig. 8 where a distance to an air flow passage other than the bellmouth 5 rapidly changes in the circumferential direction, thereby efficiently suppressing the fluctuation of incoming air flow and the blade tip vortex 9 as well as attaining reduction in noise.
Also, a change in air flow at the rotational position of the blade 1 can be reduced, which results in reduction of a change of force exerted by the propeller fan 3 on the fan motor 7, leading to reduction of bearing wear or shaft deflection of the fan motor 7. This prolongs the durability of the outdoor unit 12 and helps to achieve the outdoor unit 12 that provides a stable quality during a long period of service.
Since in the present embodiment, an upstream portion of the bellmouth 5 including the second upstream expanding portion 5d exists only at a part of the periphery direction of the outer circumferential edge 1c, the effect of suppressing fluctuation of incoming air flow or the blade tip vortex 9 is reduced compared with above-described Embodiment 2 where such a upstream portion is provided around the entire periphery. Instead, the diameter of the propeller fan 3 can be large. A propeller fan 3 having an increased diameter reduces the revolution of the fan for a required amount of air, leading to reduced noise. In addition, an increased-diameter fan reduces the velocity of air flow blown out by the propeller fan 3 and passing through the grill 16, leading to a reduction in noise emissions caused by the grill 16. So that low noise outdoor unit 12 can be obtained
Also, reduced velocity of air flow passing through the grill 16 results in reduced air flow resistance of the grill 16, leading to electric power saving as well as the achievement of an highly energy-saving outdoor unit 12. Furthermore, reduced air flow resistance of the grill 16 leads to a reduction in a required pressure boost, resulting in reduction in noise emissions from the propeller fan 3 and resultant lower-noise outdoor unit 12.
As shown in Fig. 11 depicting a cross-section perpendicular to the rotation shaft in the second upstream expanding portion 5d, the bellmouth 5 has a convex-shaped end warpage 23 formed at both circumferential ends of the second upstream expanding portion 5d in the rotation shaft direction. This makes continuously smooth a transitional section between the second upstream expanding portion 5d and a portion where no such portion is found, for example, between the direction of (vii) and that of (viii), or between the direction of (viii) and that of (i), thereby suppressing the fluctuation due to separation of the air flow coming into the bellmouth 5 in these transitional section, so that low noise effect can be easily obtained.

Embodiment 4

Fig. 12(a) is a front view of a rectangular box-shaped outdoor unit of a heat pump water heater according to Embodiment 4 of the present invention. Fig. 12(b) is a horizontal cross-sectional view including a rotation shaft taken along the line F-F. Fig. 12(c) is a cross-sectional view including a rotation shaft taken along the line G-G. The reference numerals and symbols in Fig. 12 refer to the same components as those in Embodiments 1 and 3. Reference is also made to Figs. 1 to 6 to provide descriptions on the blower.
In a heat pump water heater, namely a rectangular box-shaped outdoor unit 25 according to the present embodiment, its blower has the same structure as in Embodiment 3. Accordingly, descriptions on the blower are omitted, and differences in structure from those in Embodiment 3 are described below. As shown in Fig. 12, the heat pump water heater according to the present embodiment has an outlet face 13 provided in the front of the outdoor unit 25, an external air inlet face 14 provided in two faces, that is, its opposing face (back face) and a face of the left-hand side of the figure, and an L-shaped heat exchanger 15 is disposed so as to cover the air inlet face 14. Also, a water heat exchanger 24 for performing heat exchange between a refrigerant and water is provided at the bottom of the inboard air passage chamber 19. The water heat exchanger 24 occupies the bottom of the inboard air passage chamber 19. When viewed from the propeller fan 3, the top plate 24a of the water heat exchanger 24 is replaced by the bottom plate 18 in Embodiment 3. Therefore, the outdoor unit 25 of a heat pump water heater according to the present embodiment also provides the same advantages and effects as the blower described in Embodiment 3, leading to the implementation of the outdoor unit 25 which provides low-noise and preserves quality for a long period of time.

Embodiment 5

In addition to features described in Embodiment 1, a blower according to the present embodiment is characterized in that a circumferential edge of the blade 1 is warped toward an inlet side (α) from an outlet side (β). The shape of such a circumferential edge is described below in terms of the warpage toward the inlet side from the outlet side. Features of a bellmouth 5 except the shape of the blade, the relative position of a propeller fan 3 and bellmouth 5, and the structure with a fan motor 7 are the same as Embodiment 1. Accordingly, reference is also made to Figs. 1 to 6 to provide a description on the blower.
Fig. 13 is an enlarged view, equivalent to Fig. 4, of a main section of a blower according to Embodiment 5 of the present invention, where dashed lines Ld1 to Ld11 are dividing meridians obtained by equally dividing a radial section of a blade with the rotation shaft being the center and rotating lines that connect divided points from hub side to an outer circumference side about the rotational shaft to project the dividing points to a plane containing the rotation shaft. The outer circumference side is shown. Fig. 13 shows 12 divisions ranging from the leading edge to the trailing edge. The dividing meridian is warped in front and at the back of a line Lf4 drawn in the outer circumferential edge of a blade in such a manner that the outer circumferential edge curves toward an inlet side (inlet space a) from an outlet side (outlet space β). Such a warpage shown in Fig. 13 is becoming greater at in the middle between the leading edge and the trailing edge, Ld5 to Ld7, and is gradually becoming smaller toward the leading edge or the trailing edge, while no warpage is found at a leading edge 1a and a trailing edge 1b (represented as meridian in Fig. 13) that are ends of the dividing meridian.
A blower provided with a propeller fan 3 according to the present embodiment having a blade outer circumferential edge warped toward the inlet side is described below in terms of its operation. As described above, the propeller fan 3, when driven by the fan motor 7, sends to the air outlet space β the air inside a region where the propeller fan 3 rotates and at the same time draws in the air in the air inlet space α to the region where the propeller 3 rotates through surfaces defined by a leading edge 1a or an outer circumferential edge 1c when a blade is rotating.
Like fig. 5, Fig. 14 is a view of an outer circumferential edge of a blade, with the addition of leader lines indicating the state of air flow in the vicinity of the outer circumferential edge of the blade. As shown in Fig. 14, part of the air entering the propeller fan 3 becomes a leak flow 8 to the negative pressure surface 1e from the pressure surface 1d via the outside of the outer circumferential edge 1c. In the present embodiment, the outer circumferential edge of a blade is warped toward an inlet side, which reduces the pressure difference between the pressure surface 1d and the negative pressure surface 1e in the outer circumferential edge 1c as well as makes smooth the leak flow 8 coming into the negative pressure surface 1e from the pressure surface 1d. Accordingly, a blade tip vortex 9 occurring at a position along the outer circumferential edge 1c on the negative pressure surface 1e, originating from the leak flow 8 occurring in the vicinity of the leading edge of the outer circumferential surface 1c, has a higher central pressure than those with no warped outer circumferential edge made toward an inlet side, which causes the vortex to be weaker.
The blade tip vortex 9 grows as it transits to the trailing edge side 1b from the leading edge side 1a, and moves away from the outer circumferential edge 1c of the blade 1 at the maximum warpage position Pf3 at which a flow deflection becomes large. The blade tip vortex 9 that left the outer circumferential edge 1c is pushed by an entire flow from the inlet space α to the outlet space β and is discharged out of the blower, while it is weakening in vortex structure.
The vortex that left the outer circumferential edge 1c interferes with the bellmouth 5 and an adjacent blade causing noise emissions and impedes air flow from the inlet space α to the outlet space β. For this reasons, fan rotating speeds is increased to obtain a required amount of air volume and pressure, increasing in noise emissions. Like the present embodiment, the blade outer circumferential edge is warped toward an upstream side, thereby weakening the blade tip vortex 9 and suppressing increased noise level caused by the blade tip vortex 9.
However, the blade tip vortex 9 becomes unstable such that its position and vortex diameter are easily changed although it is weak as a vortex due to its relatively high central when the outer circumferential edge of the blade is warped toward the inlet side. For this reason, a conventional bellmouth 25 having only a first upstream expanding portion as shown in Fig. 15 cannot sufficiently obtain effects. As described above, actual blowers rarely have a wide area around the blade 1 in the air inlet space α and a circumferentially uniform shape. A bellmouth 24 having a small first expanding portion indicated by a solid line is susceptible to fluctuation in the periphery, causing the weak, unstable blade tip vortex 9 to further become unstable, which disturbs a flowing path and induces noise emissions. In contrast, in the case of the bellmouth 25 having a large first expanding portion indicated by dashed-dotted lines an influence of fluctuations in the periphery of the outer circumferential edge is mitigated. However, due to a narrow air passage from the outer circumferential edge 1c, air flow coming from the outer circumferential edge 1c declines at the upstream side of the rotation shaft direction, and at the same time a leak flow 8 from the pressure surface 1d to the negative pressure surface 1e also declines, resulting in a narrower region where the blade tip vortex 9 grows. Accordingly, if the warped outer circumferential edge technique according to the present invention is applied to this case, the blade tip vortex 9 becomes weak and therefore moves away from the blade earlier. This tends to cause interfere with the bellmouth and its adjacent blade and expand a disturbance in the flowing path, resulting in increased noise emissions. As described above, a combination of a conventional bellmouth and a propeller fan having warped outer circumferential edges cannot achieve maximum noise reduction effects.
As shown in Fig. 15 using dashed lines, in a blower according to the present embodiment having a convex-shaped first upstream expanding portion and a concave-shaped second upstream expanding portion formed at the upstream side of the rotation shaft, the bellmouth 5 covers area of the outer circumferential edge 1c of the blade 1 and provides a greater distance to the outer circumferential edge 1c of the blade 1 than a conventional bellmouth indicated by solid lines or dashed-dotted lines. This makes circumferentially uniform air passage around the outer circumferential edge 1c of the blade 1, thereby suppressing fluctuations of the air flow coming into the blade 1 and unstable blade tip vortex as well as allowing more air flow to be taken in from the outer circumferential edge 1c of the blade 1 and preventing the blade tip vortex 9 from moving away. Consequently, a propeller fan 3 having the warped blade outer circumferential edge can effectively achieve noise reduction effects, leading to the achievement of a low-noise blower.
The warpage of the outer circumferential edge made toward the inlet side from the outlet side, as shown in Fig. 13, is becoming greater in the middle between the leading edge 1a and the trailing edge 1b and is gradually becoming smaller toward the trailing edge 1b, while no warpage is found at the trailing edge 1b, an end of the dividing meridian. As described above, the bellmouth 5 causes less air flow to come from the outer circumferential edge 1c of the blade 1, and the less warped outer circumferential edge at the trailing edge 1b where there is less leak flow 8 where the blade tip vortex 9 originates and grows results in a greater turning angle at an outer circumferential edge having a high circumferential velocity, thereby effectively heightening blade boosting. This reduces the rotating speed for a required amount of air volume and pressure, resulting in a reduction in relative velocity of air flow on the blade surface. Such a reduction in relative velocity of air flow on the blade surface means a reduction in pressure change which causes noise emissions, leading to the achievement of a low-noise blower.

Embodiment 6

A heat pump apparatus, for example, an air conditioning apparatus is described with reference to Figs. 7 and 8 provided with a blower, with a blade outer circumferential edge of a propeller fan 3 being warped toward an inlet side from an outlet side, having a second upstream expanding portion 5d along the entire circumference in the circumference direction continuously upstream of the first upstream expanding portion of the bellmouth 5. Reference to Figs. 1 to 6 is made to describe the blower.
An air conditioning apparatus to which a blower according to the present embodiment is applied has the same structure and operation as those described in Embodiment 2, and provides the same advantages and effects as those in Embodiment 2. Accordingly, descriptions provided below are mainly regarding warped outer circumferential edge of a blade 1 of the propeller fan 3.
As described above, a conventional bellmouth structure cannot provide sufficient effect even if the blade 1 of the propeller fan 3 has a warped outer circumferential edge toward the inlet side. In particular, when installed in a heat pump apparatus such as an air conditioning apparatus, a conventional bellmouth structure has difficulties in providing noise reduction effect resulting from a blade having a warped outer circumferential edge, due to low circumferential uniformity in air passages at the periphery of the blade circumferential edge.
An air conditioning apparatus according to the present embodiment includes a bellmouth that has a first upstream expanding portion and a second upstream expanding portion provided at the entire circumference thereof and a propeller fan 3 that has an outer circumferential edge of its blade 1 warped toward an air inlet side, which suppresses the effect of non-uniform air passage around the outer circumferential edge and ensures the entry of air from the outer circumferential edge 1c as well as weakens a blade tip vortex 9 and achieves noise reduction effects, leading to the achievement of a low-noise heat pump apparatus.

Embodiment 7

Descriptions will be given to a heat pump apparatus, for example, an air conditioning apparatus provided with a propeller fan 3 having a outer circumferential edge of its blade warped toward an inlet side from an outlet side and a second upstream expanding portion 5d formed along part of the circumference continuously upstream side of the first upstream expanding portion 5c. Reference to Figs. 1 to 6 is made to describe the blower.
An air conditioning apparatus to which a blower according to the present embodiment is applied has the same structure and operation as those described in Embodiment 3 using Figs. 10 and 11, and provides the same advantages and effects of Embodiment 3. Accordingly, descriptions provided below are mainly regarding warping outer circumferential edge of a blade 1 of the propeller fan 3 toward the inlet side.
As described above, a conventional bellmouth structure cannot achieve sufficient effects even if a blade 1 of a propeller fan 3 has a warped outer circumferential edge toward the inlet side. In particular, when installed in a heat pump apparatus such as an air conditioning apparatus, uniformity is low in the air passage around the outer circumferential edge of the blade. When adopting a large outer diameter of the fan, the distance between ambient faces and the blade becomes small, so that it is difficult to obtain low noise effect in the case of warping the outer circumferential edge of the blade toward the inlet side.
An air conditioning apparatus according to the present embodiment includes a bellmouth that has a first upstream expanding portion and a second upstream expanding portion provided at a location in which there is a significant change in distance between the blade and the surface of the apparatus, as viewed from the rotating blade, which effectively suppresses the effect of un-uniform air passage of the outer circumferential edge and ensures the entry of air from the outer circumferential edge 1c as well as weakens a blade tip vortex 9 and achieves noise reduction effects, leading to the achievement of a low-noise heat pump apparatus.
Figs. 16 and 17 are graphs showing the relationship of air volume and aerodynamic noise level by combining cases of an outdoor unit of an air conditioning apparatus having a blade 1 of a propeller fan 3 with and without a warped outer circumferential edge, second upstream expanding portion upstream of the bellmouth first upstream expanding portion in a corner consisting of a separation plate, a top plate, and a bottom plate of the outdoor unit, and those having a conventional bellmouth. The outer circumferential edge of a blade 1 has a different shape between Fig. 16 and Fig. 17. Blade shapes in Figs. 16 and 17 are hereinafter referred to as propeller fan A and propeller fan B, respectively.
Warpage of the propeller fan A and the propeller fan B is concretely described below. Fig. 18 shows dividing meridians, like those in Fig. 13. A θ being an angular difference between before and after the inclination of the dividing meridian changes, in the propeller fan A, θ at a dividing meridian in the middle of the leading edge 1a and the trailing edge 1b, that is, a dividing meridian Ld6 in Fig. 18 is set at a maximum of about 14 degrees,. In the propeller fan B, θ at a dividing meridian closer to the leading edge 1a, that is, a dividing meridian Ld4 in Fig. 18 is set at a maximum of about 14 degrees. Radius position which is a base point where the gradient of the dividing meridian changes is specified as 85 % radius of the outer circumferential diameter for both fans. The maximum θ value (about 14 degrees) is obtained after various tests are conducted and preferably approximately 14 degrees. Fig. 19 is a development view of the outer circumferential edge of a blade 1. Warpage ratio is defined as D divided by L, where D is a maximum distance between the blade chord and the blade and L is the length of the chord. Warpage ratio is set to 5.8 percent at a position 85 percent of the radius and to 8.7 percent at a position of the outer diameter.
Both of Figs. 16 and 17 shows that a bellmouth having a second upstream expanding portion provides more noise reduction than a conventional bellmouth in the case where no warpage is formed in the outer circumferential edge of a blade. In the case where a warpage is formed in the outer circumferential edge of a blade toward the inlet side, the conventional bellmouth provides nearly no noise reduction for an outdoor unit, while a bellmouth having a second upstream expanding portion provides a significant noise reduction.

Industrial Applicability

An outdoor unit 12 of an air conditioning apparatus and an outdoor unit 25 of a heat pump water heater are described above as an example of applications of a blower according to the present invention. The blower according to the present invention can be widely used in other various types of apparatuses (for example, a ventilating fan) and facilities which are provided with a blower.

Claims

A blower comprising:
a blade (1) having an outer circumferential edge (1c) having a recessed warp in a rotational direction, and

an annular bellmouth (5) covering the circumference of the blade (1) at an air outlet side,

wherein a surface portion of the bellmouth (5) facing a face composed of a rotational trajectory of the outer circumferential edge (1c) has a first upstream expanding portion (5c) formed in a shape of a convex, facing an upstream direction of a rotation shaft and extending upstream from a minimum inner diameter position (Pb3) and a second upstream expanding portion (5d) formed in a shape of a concave, facing the upstream direction of the rotation shaft, being continuous with and extending from the first upstream expanding portion (5c), and characterized in that a transition portion between the first upstream expanding portion (5c) and the second upstream expanding portion (5d) is located downstream of a maximum warpage position (Pf3) on the outer circumferential edge (1c) of the blade (1).
The blower of claim 1, wherein an upstream portion of the second upstream expanding portion (5d) is formed generally in a shape of a cone.
The blower of claim 1 or 2, wherein a third upstream expanding portion (5e) is formed in a shape of a convex in the upstream direction of the rotation shaft, the third upstream expanding portion (5e) being continuous with and extending upstream from the second upstream expanding portion (5d).
The blower of claim 3, wherein the second upstream expanding portion (5d) or the third upstream expanding portion (5e) covers the maximum warpage portion (Pf3) on the outer circumferential edge (1c) of the blade (1).
The blower of any one of claims 1 to 4, wherein an outer circumferential edge side of the blade (1) of a propeller fan (3) is warped toward an inlet side from an outlet side.
The blower of claim 5, wherein regarding a warp formed from the outlet side toward the inlet side in the outer circumferential edge side of the blade (1) of the propeller fan (3), a degree of the warp becomes gradually smaller from a middle point between a leading edge (1a) and a trailing edge (1b) toward the trailing edge (1b).
A heat pump apparatus comprising:
an air outlet face (13) provided on a top face or a side face of an enclosure and disposing a blower of any one of claims 1 to 6 thereon,

an air inlet face (14) provided on at least one face except the air outlet face (13),

a heat exchanger (15) disposed so as to cover the air inlet face (14); and

a plurality of side plates to form the other faces except the air outlet face (13) and the air inlet face (14),

wherein the first upstream expanding portion (5c) of the blower is formed from a minimum inner diameter position (Pb3) at an entire portion of a circumferential direction of the bellmouth, and

the second upstream expanding portion (5d) of the blower is formed continuous with a the first upstream expanding portion (5c) at an entire portion of the circumferential direction of the bellmouth.
A heat pump apparatus comprising;
an air outlet face (13) provided on a top face or a side face of an enclosure and disposing a blower of any one of claim 1 to 6 thereon,

an air inlet face (14) provided on at least one face except the air outlet face (13),

a heat exchanger (15) disposed so as to cover the air inlet face (14); and

a plurality of side plates to form the other faces except the air outlet face (13) and the air inlet face (14),

wherein a first upstream expanding portion (5c) of the blower is formed from a minimum inner diameter position (Pb3) at an entire portion of a circumferential direction of the bellmouth, and

the second upstream expanding portion (5d) of the blower is formed continuous with the first upstream expanding portion (5c) at some portions of the circumferential direction of the bellmouth.
The heat pump apparatus of claim 8, wherein the second upstream expanding portion (5d) of the bellmouth (5) has a curved surface (23) at both circumferential ends thereof, the curved surface (23) being formed in a shape of a convex in the direction of a rotation shaft.
The heat pump apparatus of claim 8 or 9, wherein a circumferential position of the bellmouth (5) where the second upstream expanding portion (5d) partly extends upstream from the first upstream expanding portion (5c) corresponds to a corner between side faces surrounding the air outlet face (13) of the enclosure.
The heat pump apparatus of claim 10, wherein the side faces surrounding the air outlet face (13) of the enclosure consist of the plurality of side plates.
The heat pump apparatus of claim 10, wherein the side faces surrounding the air outlet face (13) of the enclosure consist of the plurality of side plates and the heat exchanger (15).