JPH02157539A - Air conditioner - Google Patents

Abstract

PURPOSE:To provide a substantial improvement of an air conditioning capability, a low noise and a low power consumption by a method wherein a fan guide for use in circulating a turbulent flow formed at a rear part of a side plate of a vane wheel constituting a centrifugal fan 8 to a suction side of the vane wheel is arranged. CONSTITUTION:A fan guide 25 projected by a predetermined amount from an outer circumferential end of a side plate 5 to a main plate 4 and having an arcular surface at its inner diameter surface is arranged before a heat exchanger 13 within a casing 1. A back-flow formed at a rear part of the side plate 5 is recirculated from an arcular surface of the fan guide 25 to an air suction side at the front end of the side plate 5. Accordingly, a laminar flow at the upper surface of the side plate 5 is flowed around an air suction side within the vane wheel at a high flow speed without generating any separation of the flow through an air circulating passage 18 between the side plate 5 and the bottom wall 14 of the outer casing 1. Even at the air suction side the air is sucked around the upper part of the front end 9b of the side plate 5 effectively through an arcular surface of the opening edge 11a and the air is discharged in a centrifugal direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air conditioner equipped with a centrifugal fan type blower.

(Prior art) In general, a so-called centrifugal fan type blower that is equipped with moving blades (blades) achieves the blowing function by using the lift of the moving blades, so kinetic energy is transferred to a fluid such as air. Because of their extremely high transmission and conversion efficiency, they have been widely used as blowers for air conditioners, for example.

Recently, ceiling-embedded type air conditioners have become increasingly popular due to their advantages in terms of installation space and freedom in indoor design. Among various types of blowers, centrifugal fans or mixed-flow fans, which are a type of centrifugal fans, are generally used in this type of air conditioner due to their ability to change the wind direction, as shown in Japanese Patent Laid-Open No. 62-194128. is normal.

However, among the air blowers, centrifugal fans, mixed flow fans, and the like have a drawback that their air blowing capacity is relatively lower than that of normal axial fans.

The following is an explanation of the problem in the case of a conventional air conditioner equipped with a centrifugal fan as shown in FIG. 4, for example.

In the figure, the reference numeral 30 includes a main plate 31 and a side plate 32, and between the main plate 31 and the side plate 32, a plurality of air blowing blades 33, 33...
This is a centrifugal fan composed of impellers 35 arranged radially. The centrifugal fan 30 is rotated in a horizontal direction at a predetermined rotational speed by a fan driving electric motor 36.

On the other hand, reference numeral 37 is an external casing that houses the centrifugal fan 30 in the center and supports a heat exchanger 38 around the outer periphery of the impeller 35. 39, and an air outlet 40 is formed at the outer peripheral edge of the lower side.

When the centrifugal fan 30 is rotated by the electric motor 36, the air sucked in at the air suction port 39 by the action of the impeller 35 flows as shown by the arrow and is supplied to the heat exchanger 38. After the heat is exchanged in the heat exchanger 38, the air is blown into the room from the air outlet 40.

(Problem to be Solved by the Invention) By the way, in the ceiling-mounted air conditioner configured as described above, the height Hl of the heat exchanger 38 (see Fig. 4) is equal to the given vertical fan space. In this case, the height Hl of the heat exchanger 38 is necessarily larger than the height H3 of the blades 33 of the impeller 35. becomes.

On the other hand, in such a centrifugal fan 30, noise reduction can be achieved by increasing the diameter of the impeller 35 and reducing the required rotation speed, but in this case, the heat exchanger 3
8 and the outer end of the impeller 35 are very close to each other.

As a result, the free jet boundary line FL of the blown air formed behind the main plate 31 and side plate 32 of the impeller 35 crosses only the center of the heat exchanger 38 as shown in the figure. There is a problem that the overall wind speed (flow speed) distribution deteriorates. For this reason, normally, as shown in the figure, the outer diameter of the blade 33 is kept within the required dimension, and the outer periphery of the blade 33 and the heat exchanger 3 are
By installing both of them with a predetermined distance between them and 8, the diffusion effect is utilized to obtain an even wind introduction effect.

However, if this is done, a Karman vortex is generated behind the side plate 32, which generates noise and also causes the free jet to cross only the central portion of the heat exchanger 38. As a result, the wind speed distribution deteriorates. Therefore, the ventilation resistance also increases, and the heat exchanger 3
Since the heat exchange amount of 8 decreases, in order to obtain a constant heat exchange amount, it is necessary to further increase the number of air blowers, resulting in inconveniences such as an increase in power consumption and noise.

(Problems to be Solved by the Invention) The present invention has been made for the purpose of solving the above-mentioned problems. For example, as shown in FIGS. 1 to 3, a A plurality of air blowing blades 6, 6
A centrifugal fan 8 that has an impeller 7 and blows air in a direction perpendicular or substantially perpendicular to the rotating shaft 9a, and an air conditioning heat exchanger disposed around the outer periphery of the impeller 7 of the centrifugal fan 8. 13, in an air conditioner comprising: A fan guide 25 is provided in front of the heat exchanger 13 in front of the main plate 4 by a predetermined amount beyond the outer peripheral end of the side plate 5, and has an arcuate surface on its inner diameter side, and the arcuate surface of the fan guide 25 This device is characterized in that the wake formed behind the side plate 5 is made to flow back to the air suction portion on the front end side of the side plate 5.

(Function) In the configuration of the air conditioner of the present invention, the turbulent flow formed behind the side plate 5 of the impeller 7 constituting the centrifugal fan 8 is directed toward the suction portion of the impeller 7. Since the fan guide 25 for recirculating the air is provided, the air flow recirculating action of the fan guide 25 can increase the flow velocity of the air flow to achieve a turbulence elimination effect, and the air flow is supplied to the heat exchanger. The flow velocity distribution of the blown air flow can be made uniform.

(Effect of the invention) Therefore, according to the air conditioner of the present invention, the centrifugal fan,
The air conditioning capacity of an air conditioner using a fan such as a mixed flow fan can be substantially improved, and the noise and power consumption can be lower than that of conventional devices.

(Embodiment) FIGS. 1 and 2 show, for example, a ceiling-embedded cassette type air conditioner according to a first embodiment of the present invention.

First, FIG. 1 shows the overall structure of the cassette body 10 of the Oi built-in air conditioner, and reference numeral 1 in the figure indicates an external casing for being installed in the ceiling of the cassette body 10 of the air conditioner.

On the central lower surface of the outer casing 1, there are a plurality of rearwardly curved air blowers formed by radially bending the inlet side in the rotation direction between the upper main plate 4 and the lower side plate (shroud) 5. A centrifugal fan 8 equipped with an impeller 7 configured by disposing blades 6, 6, . . . is suspended via a driving electric motor 9. The centrifugal fan 8 has a fitting part 4b for connection with the rotating shaft 9a of the driving electric motor 9 at the center of the main plate 4 side, and is fitted with the rotating shaft 9a of the electric motor 9 at the fitting part 4b. connected. As a result, when the electric motor 9 is driven, the impeller 7 of the centrifugal fan 8 rotates in the horizontal direction, sucking air in the direction of arrow (A), and the blower blade 6.
The lift generated in the part 6... sends it out in the centrifugal direction shown by the arrow (b).

On the other hand, the external casing 1 has an opening 11 of a predetermined size located at the air suction portion, and the opening 11 is configured as an air suction grill. Furthermore, air outlet ports 12,12 are provided at the lower edge of the outer periphery of the outer casing 1 so as to be inclined in the diffusion direction.

Furthermore, symbols ta and ta are heat exchangers disposed around the outer periphery of the centrifugal fan 8 and supported on the bottom wall 14 of the outer casing 3, and are heat exchangers that are sucked in from the air suction port by the centrifugal fan 8. The airflow pushed out in the radial direction by the action of centrifugal force from the impeller 7 is heat exchanged in the heat exchanger 13, and then flows from the outlet 12.12 in the direction indicated by the arrow (
C) The air is blown out in the outward direction.

Incidentally, in this case, the upper surface 14a of the donut-shaped bottom wall portion 14 of the outer casing 1 is partitioned into an inner region and an outer region by a locking edge 15 that stands upward at a predetermined angle, and the outer (radial direction) The heat exchanger 13 is installed with a predetermined drain space 17 in the outside) region.

The extending end 15a side of the locking edge 15 corresponds to the front end (outer peripheral end) 5a of the side plate 5 described above, and the front end 5a
2, which is curved and extended (in other words, forming a bend surface with an extremely small loss coefficient) at a predetermined interval upwardly than the A fan guide 25 is provided to form the air recirculation passage 18 at a front portion of the heat exchanger 13. On the other hand, in the front part of the air recirculation passage 18, the rear end (inner peripheral end) 5b of the side plate 5 has a radius different from the rounded surface of the casing side opening edge 11a;
is curved downward. As a result, a slit-shaped air suction port is formed on the inner edge side of the air suction portion on the opening 11 side of the lower surface of the center of the outer casing, drawing a rounded surface in the air blowing direction of the impeller 7.

Therefore, in the case of the configuration of this embodiment, the laminar flow on the upper surface side of the side plate 5 is caused to flow backward as shown in FIG. Even on the edge side, it flows around to the air suction part side inside the impeller at a high flow velocity without causing any separation. Also, on the air suction section side, the rounded surface (bend surface) on the outside of the opening edge 11a effectively causes the air to wrap around the upper side of the front end 5b of the side plate 5 and is discharged in the centrifugal direction. In particular, the air recirculation passage 18 has a large dynamic pressure P1 at its inlet side as shown in the figure, and an intermediate dynamic pressure P which is lower by a predetermined pressure than the large dynamic pressure P1 at a part of the middle position. Negative pressure P at the outlet on the side.

Since each of these occurs, the above-mentioned air recirculation effect can be realized more effectively.

In this case, the suction grill side opening edge 11a
For example, as shown in FIG. 2, it is more advantageous for the edge portion on the inner end side of the bottom wall 14 to have a sharp shape, since separation of flow at the suction portion is less likely to occur, and noise is reduced.

Therefore, according to the configuration of the present embodiment, if the height of the blades 6 of the impeller 7 is smaller than the height of the heat exchanger 13 inside the outer casing l of the air conditioner main body 10 as shown in the figure, Even in such a case, the air flow pushed out from the impeller 7 can be sent uniformly and efficiently over the entire area from the upper end region to the lower end region of the heat exchanger 13.

For this reason, it is no longer necessary to increase the outer diameter of the blades 6 and bring the blades 6 closer to the heat exchanger 13 as in the past, and the blades 6 are formed behind the main plate 4 and side plate 5 of the impeller. The free jet boundary line PL (see FIG. 4) of the blown air no longer crosses only the central portion of the heat exchanger 13. As a result, the flow velocity distribution of the heat exchanger 13 becomes favorable, the ventilation resistance is reduced, and the heat exchange efficiency is also improved. Furthermore, as a result, the amount of air blown can also be reduced, reducing noise and saving driving power.

Next, FIG. 3 shows an air conditioner according to a second embodiment of the present invention. The basic configuration is exactly the same in this embodiment, but a donut-shaped guide ring 27 is provided on the lower surface of the side plate 5 in the air recirculation passage 18 to reduce the cross-sectional area of the passage. It is.

With this configuration, the space within the air recirculation passage 18 is prevented from becoming a resonance space, and the air flow rate is further increased. Moreover, since more air than necessary is prevented from being recirculated, wasteful recirculation action is also eliminated, and the overall ventilation efficiency is improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the configuration of an air conditioner according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the same essential parts, and FIG. 3 is a configuration of a second embodiment of the present invention. FIG. 4 is a vertical cross-sectional view showing the configuration of a conventional air conditioner. l...External casing 4...Main plate 4a...Main plate extension 5...Side plate 5a...Side plate front end 6...Blower blade 7... ... Impeller 8 ... Centrifugal fan 9 ... Drive motor 9a ... Rotating shaft 0 ... Air conditioner main body L ... Opening 2 ... Air blowout Port 3... Heat exchanger 4... Bottom wall portion 5... Locking edge 7... Drain space 25... Fan guide

Claims (1)

[Claims] 1. An impeller (7) consisting of a plurality of blades (6), (6)... arranged between a main plate (4) and a side plate (5), and a rotating shaft of the impeller (7). A centrifugal fan (8) that blows air in a direction perpendicular or substantially perpendicular to (9a);
), in which the air conditioning heat exchanger (13) disposed around the impeller (7) is housed in a predetermined casing (1), wherein the casing (1)
A fan guide (25) is provided in front of the heat exchanger (13) in the fan guide (25), which extends beyond the outer peripheral end of the side plate (5) by a predetermined amount toward the main plate (4) and has an arcuate surface on its inner diameter side. The arcuate surface of the fan guide (25)
2.) An air conditioner characterized in that a wake formed behind the side plate (5) is made to flow back to the air suction portion on the front end side of the side plate (5).