JP3128952B2 - Blower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal blower used for home air conditioners and combustion equipment.

[0002]

2. Description of the Related Art A conventional blower of this type has an impeller 2 housed in a scroll casing 1 and a rotating shaft of a motor 3 mounted outside the scroll casing 1 as shown in FIG. 2 is connected to a boss 2b provided on the main plate 2a. The blade 4 of the impeller 2 is the main plate 2
a and a sub-plate 2c. Generally, thin blades having a uniform thickness or various airfoil blades are used. The scroll casing 1 includes an upper bottom plate 1a, a lower bottom plate 1b, and a side plate 1c. A suction port 5 is formed in the upper bottom plate 1a, and a discharge port 6 is formed in the side plate 1c.

In the above configuration, the impeller 2 is rotated by the motor 3 so that the upper bottom plate 1 of the casing 1 is rotated.
The air is blown from the suction port 5 provided in the casing 1, and the air passing through the impeller 2 is blown out from the discharge port 6 of the casing 1.

[0004]

However, in the above-mentioned conventional configuration, there is a problem that the flow passing through the impeller 2 is disturbed due to the flow rate and the shape of the blade 4, and the performance is reduced. That is, when the inter-blade flow as shown in FIG. 5 occurs, the flow is pressed on the pressure surface 4a of the blade, so that separation does not occur. However, the flow tends to separate from the blade on the suction surface 4b. A peeled area occurs. This is because the flow between the blades is a decelerated flow, and the flow is such that the pressure increases toward the downstream side, and the tendency becomes stronger as the flow rate becomes smaller. Such peeling is likely to occur on the negative pressure side in any blade shape, but is particularly likely to occur in the case of a radial blade as shown in FIG. The radial blade is a shape that is often used when a relatively large air volume is obtained at a low rotation speed. However, as described above, in a small air volume region, the blade is separated and performance is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a blower capable of efficiently using from a large air flow to a small air flow while taking advantage of a radial air flow characteristic while suppressing separation on a low air flow side. It is intended.

[0006]

In order to achieve the above object, a blower of the present invention comprises a main plate having a boss portion at a central portion, a plurality of blades provided on an upper surface of the main plate, and an upper end of the blade. An impeller composed of a holding sub-plate, and an impeller that houses the impeller, and a bottom plate facing the main plate and an upper bottom plate having a suction port in the center opposed to the sub-plate and a side plate having a discharge port, A scroll casing composed of:
A motor for rotating the impeller, wherein the blade is located forward in the rotational direction and has a positive pressure surface curved concavely in the rotational direction, and a negative surface located rearward in the rotational direction and convexly curved in the rotational direction. A pressure surface, and a hollow structure composed of three surfaces of an outer peripheral surface covering the outer peripheral end of the positive pressure surface and the outer peripheral end of the negative pressure surface,
The negative pressure surface has a plurality of small holes, the main plate has an opening at a position facing a hollow portion of the blade, and the lower bottom plate of the scroll casing is
A portion facing the main plate projects outward to form a disk-shaped space between the main plate and the lower bottom plate, and connects a pressure hole provided near a discharge port of the casing to the disk-shaped space. A communication pipe is provided.

[0007]

According to the present invention, the pressure surface of the blade has the same shape as that of the radial blade, and the suction surface has the shape of a thick wall having a wide width on the outer peripheral side of the blade. Therefore, a change in the cross-sectional area of the passage between the blades is reduced, and the deceleration rate of the flow speed between the blades is reduced, so that separation from the blade surface is suppressed. Furthermore, the wing has a hollow structure,
A plurality of small holes are formed on the negative pressure surface, and an opening is provided on the main plate side. In a space opposed to the opening,
Since the high pressure near the casing discharge port is guided, the hollow portion inside the blade also has a higher pressure than between the blades. Therefore, air blows out from the small holes provided in the negative pressure surface of the blade, and acts to suppress the flow from separating on the negative pressure surface when the air volume is low.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 to 3, reference numeral 11 denotes a scroll casing, 12 denotes an impeller, and 13 denotes a motor. A boss 12b is provided at the center of the main plate 12a of the impeller 12, and the rotation shaft of the motor 13 is connected to the boss 12b. The blade 14 is the main plate 1
2a and the auxiliary plate 12c, and has a hollow structure surrounded by three surfaces of a positive pressure surface 14a, a negative pressure surface 14b, and an outer peripheral surface 14c. A plurality of small holes 15 are formed in the negative pressure surface 14b. Further, an opening 12d is formed in a portion of the main plate 12a corresponding to the hollow portion of the blade 14.

The scroll casing 11 includes an upper bottom plate 11
a, a bottom plate 11b, and a side plate 11c.
A suction port 16 is provided at the center of 1a, and a discharge port 17 is provided at the side plate 11c. Pressure hole 1 near discharge port 17
8 are formed. A portion of the lower bottom plate 11b facing the impeller 12 protrudes outward, and forms a disc-shaped space 19 between the lower bottom plate 11b and the main plate 12a. Furthermore, this disc-shaped space 19
A communication pipe 20 is provided to connect the pressure hole 18 with the communication hole 20.

In the above configuration, when the impeller 12 is rotated by the motor 13, the air sucked from the suction port 16 by the blowing action of the impeller 12 is blown into the scroll casing 11 through the space between the impeller blades. Then, it is guided to the scroll casing 11 and discharged from the discharge port 17 to the outside.

At this time, the flow between the blades is a smooth flow without separation, as shown in FIG. That is, since the blade 14 rotates in the direction indicated by the arrow,
Air flows in a state where air is pressed against a, and peeling does not occur.

On the other hand, the negative pressure surface 14b is curved in a direction opposite to the positive pressure surface 14a, and the effect of narrowing the inter-blade passage becomes greater toward the outer periphery of the impeller 12, so that the deceleration rate of the flow velocity is suppressed. And peeling is less likely to occur. further,
The hollow portion of the blade 14 is maintained at a high pressure near the discharge port 17 through the opening 12 d provided in the main plate, the disc-shaped space 19, the communication pipe 20, and the pressure hole 18.
When the flow along the line b causes separation and the pressure on the negative pressure surface 14b decreases, air is ejected from the hollow portion of the blade to the space between the blades through the small holes 15. For this reason, the dead water area of the peeling is eliminated, and the turbulence and loss due to the vortex are suppressed, so that the performance deterioration is suppressed.

Further, the separation from the negative pressure surface 14b is more likely to occur at the operating point with a lower air flow, but the pressure in the hollow portion of the blade 14, that is, the pressure near the discharge port 17, becomes higher as the air flow becomes lower. Therefore, the adjustment that the number of jets from the small holes 15 is increased automatically at the time of the low air flow at which the separation easily occurs, and a high-efficiency flow without the separation can be maintained even if the air flow changes.

According to the structure of this embodiment, even if the air volume changes, there is no separation between the blades, so that there is an effect that the air can always be efficiently blown.

[0016]

As described above, in the blower of the present invention, the blades of the impeller have a hollow structure composed of a pressure surface, a suction surface and an outer peripheral surface, and the suction surface is opposite to the pressure surface. The effect of narrowing the inter-blade passage becomes greater toward the outer periphery of the impeller, so the deceleration rate of the flow velocity is suppressed,
This has the effect of making peeling less likely to occur. Furthermore, since the hollow portion of the blade is maintained at a high pressure near the discharge port through the opening provided in the main plate, the disk-shaped space, the communication pipe, and the pressure hole, the flow along the negative pressure surface causes separation. Then, when the pressure on the negative pressure surface decreases, air is ejected between the blades from the hollow portion of the blade through the small hole. For this reason, the dead water area of the separation is eliminated, and the turbulence and loss due to the vortex are suppressed.

Further, the separation from the negative pressure surface is more likely to occur at the operating point with a lower air flow, but the pressure in the hollow portion of the blade, that is, the pressure near the discharge port, becomes higher as the air flow becomes lower. Therefore, the adjustment that the number of jets from the small holes is increased automatically when the air volume is low at which the peeling is likely to occur automatically has an effect that even if the air volume changes, a highly efficient flow without peeling can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a blower according to an embodiment of the present invention.

FIG. 2 is a detailed view of a main part of an impeller of the blower.

FIG. 3 is a plan view showing a flow between blades of an impeller of the blower.

FIG. 4 is a cross-sectional view of a conventional blower.

FIG. 5 is a plan view showing the flow between the blades of the impeller of the blower.

[Explanation of symbols]

 Reference Signs List 11 scroll casing 11a upper bottom plate 11b lower bottom plate 11c side plate 12 impeller 12a main plate 12b boss portion 12c sub plate 12d opening 13 motor 14 blade 14a positive pressure surface 14b negative pressure surface 14c outer peripheral surface 15 small hole 16 suction port 18 discharge port 18 19 Disc-shaped space 20 Communication pipe

Claims (1)

(57) [Claims] 1. An impeller comprising a main plate having a boss portion at a central portion, a plurality of blades provided on an upper surface of the main plate, and a sub-plate holding an upper end of the blade, and the impeller is housed. A scroll casing composed of a lower bottom plate facing the main plate, an upper bottom plate having a suction port in the center opposed to the sub-plate, and a side plate having a discharge port, and a motor for rotating the impeller. The blade is located forward in the rotation direction and has a pressure surface curved concavely with respect to the rotation direction, a suction surface located rearward in the rotation direction and curved convexly with respect to the rotation direction, and an outer peripheral end of the pressure surface. The suction surface has a hollow structure composed of three outer peripheral surfaces that cover an outer peripheral end of the suction surface, the suction surface has a plurality of small holes, and the main plate has an opening at a position facing a hollow portion of the blade. Part, and the scroll case The lower bottom plate of the ring has a portion facing the main plate protruding outward, forming a disc-shaped space between the main plate and the lower bottom plate, and a pressure hole provided near a discharge port of the casing. And a communication pipe connecting the disc-shaped space with the blower.