JPH10184591A - Turbo fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress noise caused by separation of air on the negative pressure side of a blade by improving on the blade of a turbo fan. SOLUTION: A blade 22 of a turbo fan 5 mounted in a ceiling suspended air conditioner 1 is formed in hollow shape, and its upper part is opened to the end plate 21 side. A by-pass hole 33 for communicating blade internal space with negative pressure face side space is formed in a negative pressure part constituting the negative pressure face of the blade 22. At the time of driving the turbo fan 5, part of air coming around to the upper side of the end plate is supplied to the negative pressure face side through the blade internal space and by-pass hole 33.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbofan, and more particularly to a countermeasure for reducing noise generated due to separation of air on a suction side of a blade.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. 8-75240
There is known an air conditioner installed on a ceiling as disclosed in Japanese Unexamined Patent Publication (Kokai) No. H11-15095.

Generally, this type of air conditioner is provided with a turbo fan inside a casing. After the indoor air sucked from the lower surface of the casing is driven by the fan and the temperature of the indoor air is adjusted by a heat exchanger, the indoor air is blown into the room from four directions of the casing, for example.

[0004] As shown in FIG.
Comprises an end plate (b), a shroud (c), and a plurality of blades (d) held between the lower surface of the end plate (b) and the upper surface of the shroud (c). The end plate (b) is made of a circular plate material and has a central portion swelling downward, and forms a motor accommodation space above the swelling portion. The shroud (c) is made of a circular plate having an air introduction opening (c1) in the center, and is curved downward toward the inner peripheral side. The blade (d) has an airfoil section and is arranged at a predetermined angle with respect to the radial direction of the turbofan (a). Thus, the blade (d) is provided with a positive pressure surface facing the fan outer peripheral side and a negative pressure surface facing the fan inner peripheral side. With this configuration, when the turbo fan (a) is driven to rotate, the blade (d)
The centrifugal force is applied to the air on the positive pressure side of, and the pressure is increased. As a result, a blowing operation is performed in which the indoor air sucked from the air introduction opening (c1) is boosted and blown radially outward.

[0005]

However, in the conventional turbo fan (a), air separation occurs near the outer peripheral end of the negative pressure surface of the blade (d). The blowing noise increases with the occurrence, and there is a limit in reducing the operating noise of the air conditioner as a whole.

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and it is an object of the present invention to improve the flow of air in the vicinity of a suction surface of a turbofan, especially a blade, so as to reduce noise caused by separation of air on the suction surface side. The purpose is to suppress the occurrence of.

[0007]

In order to achieve the above object, the present invention suppresses the blowing noise by supplying air for preventing peeling to the negative pressure surface portion of the blade.

[0008] Specifically, the invention according to claim 1 is based on a turbofan that supports a blade (22) between an end plate (21) and a shroud (20). An air supply means (33) is provided for supplying auxiliary air toward the negative pressure surface side of the blade (22) to prevent air from separating on the negative pressure surface.

According to this specific matter, when the turbo fan is driven, the pressure of the air is increased on the pressure side of the blade, whereby the blowing operation is performed. On the other hand, on the suction side,
Air separation is likely to occur near the outer peripheral edge. In the present invention, auxiliary air is supplied to this portion by the air supply means (33), thereby preventing peeling.

According to a second aspect of the present invention, in the turbofan according to the first aspect, the inside of the blade (22) is formed hollow, and this internal space (D) is opened to the end plate (21) side. . Further, as an air supply means, an air supply hole (33) formed in the suction surface (22b) is provided so as to supply air introduced from the open portion to the suction surface side of the blade (22). I have.

According to this specific matter, when the turbofan is driven, for example, a part of the air blown from the turbofan is introduced into the internal space (D) of the blade (22) from the end plate (21) side. This air is supplied as auxiliary air to the negative pressure side of the blade (22) via the air supply hole (33).
Accordingly, the supply mode of the auxiliary air is embodied, and the operation of supplying the auxiliary air can be reliably performed.

According to a third aspect of the present invention, in the turbo fan according to the second aspect, the air supply hole (33) is provided with a blade.
A slit formed at a position near the outer peripheral end of the negative pressure surface (22b) of (22), with one longitudinal end located near the end plate (21) and the other end located near the shroud (20). It is formed in a shape. The ratio of the width dimension of the air supply hole (33) to the dimension from the inner peripheral end to the outer peripheral end of the blade (22) is set to 0.3 or less.

[0013] By these specific items, the shape of the air supply hole (33) can be specifically obtained. In particular, when part of the air blown out from the turbo fan is used as auxiliary air, the blowing noise can be reduced while the amount of auxiliary air is kept to a minimum.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to a ceiling-suspended air conditioner will be described.

FIG. 1 is a perspective view of an air conditioner (1) according to the present embodiment, FIG. 2 is a plan view showing the internal structure of the air conditioner (1), and FIG. 3 is a longitudinal sectional view thereof.

As shown in these figures, the present air conditioner
(1) is provided with a box-shaped casing (3) installed on the ceiling surface (A) and having air outlets (2A, 2B, 2C, 2D) opened horizontally on four sides. Inside this casing (3)
A heat exchanger (4) formed in an annular shape so as to face each of the air outlets (2A, 2B, 2C, 2D) and a turbo fan (5) located at the center of the casing are housed. At each of the air outlets (2A, 2B, 2C, 2D), horizontal blades (6) for adjusting the direction of the conditioned air into the room are provided rotatably about a horizontal axis.

A suction grill (8) having an air suction port (7) at the center is attached to the lower surface of the casing (3) so as to be openable and closable. (9) in FIG. 3 is an air filter for removing dust and the like in the intake air.

The heat exchanger (4) is of a cross fin type in which a number of plate-like fins are attached to a plurality of heat transfer tubes arranged in parallel with each other in an orthogonal state. During heating operation, it functions as a condenser. This regulates the temperature of the air derived from the turbo fan (5).

The heat exchanger (4) is provided below the heat exchanger (4).
Drain pan (1) for collecting drain water generated in (4)
0) is provided.

At one corner (the lower right corner in FIG. 2) of the casing (3), a piping space (12A) partitioned by a partition plate (11) with respect to the casing internal space.
Are formed. In this piping space (12A), a hanging pipe (15A) for hanging the refrigerant pipe (13), the drain pump (14), and the casing (3) to a concrete member in the space above the ceiling with a hanging bolt are provided. Are located. This piping space (12A) is covered by a corner cover (16A) that is detachable from the casing (3). Also,
At the other three corners, spaces (12B, 12C, 12D) are formed with respect to the inner space of the casing by a heat insulating material (17). Hanging fittings (15B, 15C, 15D) are arranged in each of these spaces (12B, 12C, 12D), and each is covered with a corner cover (16B, 16C, 16D). These corner covers (16A to 16D) ensure the good appearance of the air conditioner (1).

Hereinafter, the turbo fan (5) will be described. 4 is a plan view of the turbofan (5), FIG. 5 is a bottom view of the turbofan (5), FIG. 6 is a sectional view taken along the line ZZ in FIG. 4, and FIG. Each of the cross-sectional views along the -Y line is shown. This turbo fan (5) has a circular end plate (21) and an air introduction opening (20a) in the center.
A circular shroud (20) with
And a blade (22) held between them. Thereby, between the end plate (21) and the shroud (20),
An air passage (C) is formed to guide the air sucked from the air inlet (7) toward the heat exchanger (4). Blade (2
2) is formed in an airfoil that is inclined in a counterclockwise direction toward the outer peripheral side in FIG.

As shown in FIGS. 4 and 7, the blade (22) has a hollow interior, and the interior is open on the end plate (21) side. In other words, this blade (2
2) A positive pressure portion (22a) constituting the pressure side (outer peripheral surface) and a negative pressure portion (22b) constituting the negative pressure side (inner side) of the side surfaces extending in the vertical direction. And a bottom portion (22c) formed by the shroud (20) and connecting the lower ends of the positive pressure portion (22a) and the negative pressure portion (22b).

The feature of this embodiment resides in the bypass hole (33) formed in the negative pressure portion (22b) of the blade (22). As shown in FIG. 7, the bypass hole (33) opens the internal space (D) of the blade (22) to the suction surface side at a position near the outer peripheral end of the suction portion (22b) of the blade (22). It is formed as follows. More specifically, the bypass hole (33) is a slit-shaped opening formed from the upper end to the lower end of the negative pressure portion (22b) of the blade (22), and has a width dimension (dimension t in FIG. 7).
The ratio to the length dimension (dimension T in FIG. 7) of the blade (22) is, for example, 0.3 or less (about 0.1 in this embodiment).
Is set to

On the other hand, the center portion of the end plate (21) bulges downward to form a hub (23). Due to this bulging, a housing space for the motor (25) is formed above the hub (23). A columnar boss (24) is integrally formed at the center of the hub (23). This boss (24) is the casing (3)
The drive shaft (25a) of the motor (25) disposed at the center is directly connected to the lower end. More specifically, the boss (24) is provided inside a cylindrical boss body (24a) with a metallic first ring (24b).
, A vibration-proof rubber (24c), and a second metal ring (24d) are integrally fitted. A drive shaft (25a) of the motor (25) is fitted into the center of the second ring (24d). Opening for (24e)
Are formed. The drive shaft (25a) of the motor (25) is fitted into the opening (24e), and the nut (N) is screwed from below so that the turbo fan (5) rotates integrally with the drive shaft (25a). It is attached (see FIG. 3). This allows the motor
With the drive of (25), the entire turbo fan (5) rotates (Fig. 4
), And blows air sucked from below the turbo fan (5) outward in the radial direction.

The hub (23) has an opening (3) formed by a long hole.
0, 30,...) Are formed at eight locations on a concentric circle centered on the boss portion (24). This opening (30,30,…) is a part of the air blown from the outer periphery of the turbo fan (5).
When the heat enters the periphery of the motor (25) by wrapping around the back side of the (21) and takes heat from the motor (25), this air is again transferred to the hub (2).
3) for discharging to the lower side (arrow B in FIG. 3)
reference). In other words, the motor (25)
Is cooled.

A plurality of ribs (27, 27, 27) are provided on the upper surface of the hub (23).
...) are formed radially around the boss portion (24). These ribs (27, 27,…) are connected to the openings (30, 30,…)
Are formed at eight places between the bosses (2
The outer end is located on the upper surface of (4), and faces the substantially central portion in the longitudinal direction of the opening (30). By providing the ribs (27, 27,...) Having such a shape, not only the strength of the hub portion (23) of the turbofan (5) can be sufficiently obtained, but also the rotation of the turbofan (5). Sometimes this rib (27,
The air flowing around the motor (25) is stirred by the rotation of the motor (25,...), So that the cooling efficiency of the motor (25) can be improved.

The turbo fan (5) according to the present embodiment is
As shown in FIGS. 3 and 6, the lower end of the shroud (20) is located above the lower end of the boss (24). Specifically, the lower end portion of the hub portion (23) and the boss portion (24) project downward from the lower end of the shroud (20). Therefore, the dimension from the upper end of the end plate (21) to the lower end of the shroud (20) is set to be equal to or less than the dimension from the upper end of the end plate (21) to the lower end of the boss (24). Thus, the height of the turbo fan (5) can be kept to a minimum.

As shown in FIG. 3, a bell mouth (26) for guiding room air to the turbo fan (5) is disposed below the turbo fan (5). This bellmouth (2
6) has an opening (26a) slightly smaller than the opening (20a) of the shroud (20) at the center. The edge of the opening (26a) is formed in an arc shape in cross section, and the turbo fan (5)
The air flows smoothly.

Next, the characteristic operation of the turbo fan (5) according to the present embodiment when it is driven will be described. During the operation of the air conditioner (1), part of the air blown from the outer periphery of the turbo fan (5) goes around the back side of the end plate (21). A part of the air wrapped around the back side of the end plate (21) flows around the motor (25) and contributes to cooling of the motor (25) as described above (arrow B in FIGS. 3 and 4). reference). On the other hand, other air is introduced into the internal space (D) from above the blade (22) (see the arrow E in FIGS. 4 and 7). This air is led out to the suction side through a bypass hole (33) formed in the suction section (22b) of the blade (22) (see arrows F in FIGS. 4 and 7). That is, the air led out to the negative pressure side merges with the air flowing through the negative pressure side. For this reason, the separation of the air does not occur at the outer peripheral end portion of the negative pressure surface unlike the related art, and the generation of noise due to the separation is suppressed.

As described above, in the present embodiment, a part of the air wrapped around the back side of the end plate (21) is supplied to the negative pressure side to suppress the noise due to the separation of the air. 1) The driving noise as a whole can be reduced.

Further, since the blade (22) is formed to be hollow, the weight of the turbofan (5) can be reduced as a whole.

In this embodiment, the case where the present invention is applied to a turbo fan (5) housed in a ceiling-suspended air conditioner has been described. The present invention is also applicable to turbofans.

[0033]

As described above, according to the present invention, the following effects can be obtained. According to the first aspect of the present invention, the auxiliary air is supplied to the turbo fan toward the suction side of the blade (22), thereby preventing the separation of air on the suction side. Therefore, noise due to air separation can be suppressed. In particular, when this turbofan is applied to an air conditioner, the operation noise can be reduced.

According to a second aspect of the present invention, the blade (22) is provided with a path for supplying auxiliary air toward the suction side of the blade (22).
The interior space of (22) was used. Therefore, a separate member for supplying the auxiliary air to the negative pressure surface side is not required. Therefore, it is possible to prevent the separation of air on the negative pressure side while avoiding an increase in the number of parts and a complicated structure of the turbofan.

According to the third aspect of the present invention, the air supply hole is provided.
The shape of (33) can be specifically obtained.Especially, when part of the air blown out from the turbo fan is used as auxiliary air, the blowing noise is reduced while the amount of auxiliary air is minimized. Can be reduced. That is, it is possible to reduce the blowing noise while maintaining the blowing performance of the turbofan high.

[Brief description of the drawings]

FIG. 1 is a perspective view of a ceiling-suspended air conditioner according to an embodiment.

FIG. 2 is a plan view showing the internal structure of the air conditioner.

FIG. 3 is a longitudinal sectional view of the air conditioner.

FIG. 4 is a plan view of a turbo fan.

FIG. 5 is a bottom view of the turbo fan.

FIG. 6 is a sectional view taken along the line ZZ in FIG.

FIG. 7 is a sectional view taken along line YY in FIG. 4;

FIG. 8 is a sectional view showing a conventional turbo fan.

[Explanation of symbols]

 (5) Turbo fan (20) Shroud (21) End plate (22) Blade (22b) Negative pressure part (33) Bypass hole (D) Blade internal space

Claims (3)

[Claims] 1. A turbo fan comprising a blade (22) supported between an end plate (21) and a shroud (20), wherein auxiliary air is supplied to a suction side of the blade (22). Air supply means (33) for preventing separation of air on the negative pressure surface
The turbo fan characterized by being provided. 2. The turbo fan according to claim 1, wherein the blade (22) has a hollow interior, and the internal space (D) is open to the end plate (21) side. Is a turbo fan provided with an air supply hole (33) formed in the suction surface (22b) so as to supply the air introduced from the open portion to the suction surface of the blade (22). . 3. The turbo fan according to claim 2, wherein the air supply hole (33) is formed at a position near the outer peripheral end of the suction surface (22b) of the blade (22), and one end in the longitudinal direction is an end. The other end is located near the plate (21) and the shroud (2
0), and the width dimension of the air supply hole (33) is such that the ratio to the dimension from the inner peripheral end to the outer peripheral end of the blade (22) is 0.3 or less. A turbo fan characterized by being set.