EP1726832A2

EP1726832A2 - Turbo fan and blade thereof

Info

Publication number: EP1726832A2
Application number: EP06010115A
Authority: EP
Inventors: Ki Young Moon; Ki Su Hong; Jung Hoon Kim
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2005-05-17
Filing date: 2006-05-16
Publication date: 2006-11-29
Anticipated expiration: 2026-05-16
Also published as: KR20060118713A; KR100654993B1; EP1726832B1; EP1726832A3

Abstract

A turbo fan is provided. The turbo fan includes a plurality of blades (4), a shroud (2), and a circular hub (3). The shroud (2) is provided at ends of the blades (4) to guide a flow of suctioned air. The circular hub (3) guides a discharging of the suctioned air. The blade (4) includes a leading edge (5) formed wider than a trailing edge (7) thereof.

Description

The present invention relates to a turbo fan, and more particularly, to a turbo fan with improved guiding efficiency of air blown by the fan blades to reduce noise and increase the amount of air blown.
A turbo fan is used in picture frame-type indoor units of air conditioners and in other devices, and suctions air in the direction of the rotating shaft and expels air in a radial direction from the blades. As in fans according to the related art, turbo fans suction and forcibly push and expel the air with their rotating blades. The quantity of air blown depends on the rotating speed of the turbo fan.
While raising the rotating speed of a turbo fan increases the amount of blown air and static pressure, the amount of noise and vibration also increase. The problem is further exacerbated by recent demands in the industry for narrower and thinner fans which can, at the same time, provide a higher output.
Accordingly, the present invention is directed to a turbo fan that substantially obviates one or more problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a turbo fan that operates with reduced noise and blows a greater amount of air.
Another object of the present invention is to provide a turbo fan with a limited increase in its diameter and overall thickness, while increasing its capacity for blowing air without increasing its rotational speed.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a turbo fan including: a plurality of blades; a shroud provided at ends of the blades for guiding a flow of suctioned air; and a circular hub for guiding a discharging of the suctioned air, wherein the blade includes a leading edge formed wider than a trailing edge thereof.
In another aspect of the present invention, there is provided a blade of a turbo fan for suctioning air at a rotating shaft thereof and discharging the air in a radial direction thereof, the blade including: a first extending portion having a larger width; and a second extending portion having a width smaller than the larger width.
The present invention provides a turbo fan with a reduced level of operating noise while increasing the quantity of air that it blows - especially while retaining the same overall dimensions and rotating speed of a conventional turbo fan.
It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:
Fig. 1 is a perspective view of a turbo fan according to the present invention;
Fig. 2 is a perspective view of a turbo fan according to the present invention covered with a casing; and
Fig. 3 is a sectional view of Fig. 1 taken along line I-I'.
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Fig. 1 is a perspective view of a turbo fan according to the present invention.
Referring to Fig. 1, a turbo fan 1 according to the present invention includes a shroud 2, a plurality of blades 4 provided beneath the shroud 2 for forcibly blowing air, a hub formed below the blades 4 for guiding the direction in which air is discharged, and a motor mounting portion 9 formed at the center of the hub 3 for connecting to a rotating shaft.
In detail, the rotating shaft of a motor connects to the mounting portion 9 to impart its rotating force on the hub 3.
A description of the operation of the turbo fan 1 will now be provided.
In detail, when the turbo fan in Fig. 1 is installed and rotates, outside air enters the turbo fan downward from above, and is compressed and blown in a centrifugal direction by the blades 4. The compressed and blown air is expelled through the spaces formed by the blades 4 between the shroud 2 and the hub 3 at the outer edge of the turbo fan 1.
This flow of air is brought about through the rotation of the blades 4 causing air to slide along the blade surfaces 3 (in Fig. 8).
The quantity of blown air resulting from the above airflow is dependant on the width of the blade surfaces 3. That is, the wider the area of the blade surface 3, the larger the quantity of blown air is.
Fig. 2 is a perspective view of a turbo fan according to the present invention covered with a casing.
Referring to Fig. 2, a casing 10 is provided at the intake side of the turbo fan 1 to support the entire turbo fan 1 and guide the suctioning and flow of air.
As explained above, in a turbo fan according to the related art, the output of blown air increases as the rotating speed of the turbo fan increases. However, due to the ensuing increase in noise, increasing rpms is not a favorable option.
Therefore, the present invention increases the width of the blades 4 (or the width of the blade surface 8) to increase the output of blown air without raising the rpms. That is, the present invention improves the shape of the blades 4, keeping in mind that the larger the area of the blade surface 8, the greater the amount of air is blown.
Also, if the shape of the blade 4 follows the path of airflow, the air flows that much more smoothly to reduce noise. Using this principle, the present invention provides a blade 4 with a shape that follows the path of airflow in order to reduce noise.
In order to widen the blade surface 8 and reduce noise, the present invention uses a blade 4 having a special shape, which will be described below in detail.
Fig. 3 is a sectional view of Fig. 1 taken along line I-I'.
Referring to Fig. 3, the blade 4 according to the present invention is provided between the shroud 2 and the hub 3, with the casing 10 (see Fig. 2) of a predetermined size mounted above the top surface of the shroud 2. The blade 4 has a span (width) that is greater at the side for intaking air formed by the hole in the casing 10 than toward the discharging end thereof.
In detail, the width W1 of the blade 4 at the intake portion is greater than the width W2 of the blade at the discharging end. In other words, the width of the blade 4 at its leading edge 5 is formed to be greater than that at its trailing edge 7.
This shape is provided because when the blade 4 is wide at the portion where the casing 10 is, vibration causes the blade 4 and the casing 10 to collide, leading to unreliable operation.
Thus, by increasing the width of the blade 4 from the edge of the hole formed by the casing 10 to the center of the hole, not only is the vibration problem solved, but the blade guides the path of airflow, and an increase in the amount of blown air can be realized.
By thus increasing the width of the blade at the suctioning portion thereof, the area of the blade surface 8 increases and the flow of air can be guided more smoothly. Also, a larger quantity of air is blown and operating noise is reduced. In this case, even when the width W1 of the blade 4 increases at the suctioning portion, the overall size of the fan is not greatly affected, so that there is no increase in the overall size of the turbo fan.
The upper portion 6 of the blade extends unevenly. That is, the upper portion 6 of the blade has a first extending portion 11 provided close to the suctioning portion, and a second extending portion 13 provided at the end for discharging air. A connecting portion 12 is provided between the first extending portion 11 and the narrower second extending portion 13 to connect the two extending portions. The extending portions 11 and 13 respectively extend a predetermined length at a uniform width. That is, the extending portions 11 and 13 extend in parallel to the hub 3.
The reason that the extended portions 11 and 13 are provided to respectively extend uniformly is to allow the air to be blown in a centrifugal direction without escaping from the edges of the fan.
Of course, because the width W1 of the first extending portion is greater than the width W2 of the second extending portion, the area of the blade surface 8 increases, and air is smoothly guided in the discharging direction as explained above.
Also, the connecting portion 12 smoothly connects the first and second extending portions 11 and 13, so that the air stream is minimally disturbed. Thus, the flow of air can be smoothly guided, and noise can be reduced.
If the connecting portion 12 were to be formed in an abruptly stepped shape, air flowing along the blade surface 8 would likely leak outside of the blade surface 8, reducing the amount of blown air and increasing noise.
The smooth transitioning shape of the connecting portion 12 substantially reduces noise over turbo fans according to the related art, in which the outer end of the blade is abruptly recessed according to the bend of the shroud or is stepped (which produces a sudden increase in noise when the rotating speed of the fan increases).
By making the width W1 at the leading edge 5 of the blade 4 larger than the width W2 at the trailing edge 7, a large quantity of air can be suctioned at the suctioning region of the blade 4 and blown along the surface of the blade 4 to increase the quantity of air blown. Also, the by making a smooth transition, the connecting portion 12 reduces the amount of noise emitted.
As described above, when the thickness of the turbo fan 1 according to the present invention is the same as turbo fans according to the related art, the amount of blown air increases and the noise level decreases in comparison, without increasing the rotating speed of the fan. The size of the turbo fan 1 does not increase, and the overall width of the blades does not increase, so that the turbo fan 1 cannot be compared to other products, whose overall size increases due to an increase in the space taken up by the fan.
Accordingly, the space in which the turbo fan 1 is installed and the overall size of the turbo fan 1 do not change, while the amount of air blown increases and the amount of generated noise decreases.
In further detail, when applied to a turbo fan with a height (H) to distance (D) ratio R (H/D) of the blade of less than 0.1, the turbo fan according to the present invention displays maximum results. When such a turbo fan is rotated at the same speed as a conventional turbo fan, the increase in blown air quantity and decrease in generated noise are readily apparent, as illustrated by testing. A test reveals that a turbo fan with a ratio of 0.1 or less according to the present invention, when displacing 9.5cm/m (cubic meters per minute) of air, generates 42dB, compared to 43dB generated by a conventional turbo fan with the same ratio. Here, the ratio 0.1 applies to turbo fans that are thin overall - i.e., turbo fans employed in indoor wallmounted units for split system air conditioners.
The turbo fan according to the present invention improves the quantity of blown air and decreases the amount of generated noise. Because a reduction in noise can be obtained for a turbo fan according to the present invention over a conventional turbo fan of the same size, the overall performance level of the inventive turbo fan can be raised.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

A turbo fan comprising, a plurality of blades, a shroud provided at ends of the blades for guiding a flow of suctioned air, and a circular hub for guiding a discharging of the suctioned air, characterized in that the blade includes a leading edge formed wider than a trailing edge thereof.
The turbo fan according to claim 1, wherein the blade includes an upper edge that does not extend entirely in one straight line.
The turbo fan according to claim 1 or 2, wherein the blade includes a connecting portion inclined at a predetermined angle for smoothly connecting a width of the leading edge and a width of the trailing edge.
The turbo fan according to any of claims 1 to 3, wherein the blade further includes a first portion and a second portion, the first portion being wider and extending further than the second portion.
The turbo fan according to any of claims 1 to 4, wherein the width of the leading edge and the width of the trailing edge respectively extend over predetermined lengths, and the width of the leading edge is smoothly reduced over a predetermined declining angle to the width of the trailing edge.
A blade of a turbo fan for suctioning air at a rotating shaft thereof and discharging the air in a radial direction thereof, characterized in that the blade comprises;
a first extending portion having a width; and

a second extending portion having a width smaller than the width of the first extending portion.
The blade according to claim 6, wherein the first extending portion is formed at a center of the turbo fan, and the second extending portion is formed at an edge of the turbo fan.
The blade according to claim 6 or 7, further comprising:
a hub attached to a lower end of the blade for guiding a flow of discharged air; and

a shroud attached to an upper outer edge of the blade for guiding a flow of suctioned air, wherein the second extending portion extends a predetermined distance from the shroud toward the rotating shaft.
The blade according to claim 6 or 8, further comprising a connecting portion that curves gently to connect the first extending portion to the second extending portion.
The blade according to claim 9, wherein the connecting portion is formed in a position closer to an outer end of the blade than an inner end of the blade.
The blade according to any of claims 6 to 10, wherein the blade has a distance to height (D/H) ratio of 0.1 or less.