TURBO FAN
TECHNICAL FIELD
The present invention relates to a turbo fan and in particular to a turoo fan consisting of a blade plate having a hub at central portion thereof blades and a shroud which are integrally molded in one piece to thereby improve a productivity
BACKGROUND ART Generally, a turbo fan is a kind of centrifugal fan that presses air by using a concentric force of air generated by rotation of blades As the turbo fan is able to generate a large quantity of air flow, it is employed to an air conditioner of a large capacity
As shown in Figures 1 through 4, the conventional turbo fan includes a fan body 10 having several blades formed in a circumferential direction at a predetermined angle and its central portion combined with a rotational shaft (not shown) of a drive motor to be rotated to suck and discharge air, and a shroud 20 combined at the front end portion of each blade of the fan body 10 to prevent the blades from vibrating and to guide the air flow The fan body 10 includes a blade plate 11 in a disk form, a hub 12 protrusively formed at the central portion of the blade plate 11 and blades 13 radially formed at the front marginal portion of the blade plate 11 at a predetermined angle
Each of the blades 13 is a zonary body having a certain width and
length One end portion of the blade 3 is integrally molded with the marginal portion of the front surface of the blade plate 11
As shown in Figures 1 and 2, a combining side portion 13a is formed at the front end portion of the blade 13, which has a certain slope angle so 5 that its extended line is commensurate with the inner circumferential surface of the fixing portion of the shroud 20
The shroud 20 has a frustotruncated shape with its head cut Its rear side is fixed with the combining side portion 13a of the blade 13 forming a large-diameter portion 21 And as the diameter becomes gradually shortened 1 so that the opposite side of the large-diameter portion 21 , that is, a small- diameter portion 22 is formed at the front side Thus, the air sucked by the blades 13 proceeds toward the front side without being diffused while passing from the large-diameter portion 21 to the small-diameter portion 22
The conventional turbo fan constructed as described above is _ 5 fabricated as follows
The fan body 10 and the shroud 20 are separately fabricated to be assembled First a cavity with a predetermined shape is formed on a metal mold for fan body A flux such as PVC is injected into the cavity to thereby integrally fabricate the blade plate 11 , the hub 12 and the blades 13 i c And then a predetermined shape of cavity is formed on a mold for a shroud into which a flux such as PVC is injected thereby fabricating a ring- shape shroud 20
In this manner the combining side portion 13a formed at the front end portion of the blade 13 that is integrally molded in a circumferential direction
at the forward marginal portion of the fan body 10 is combined with the inner circumferential surface of the large-diameter portion 21 of the shroud 20 and attached by thermofusion to fabricate a turbo fan
However as to the conventional method for making a turbo fan in which the fan body 10 and the shroud 20 are separately fabricated by using each mold and then assembled, since they are assembled by a postprocessing such as the thermofusion, the number of operation processes is increased Also since the fan body 10 and the shroud 20 should be molded in different molds to each other, the molds are separately manufactured causing an increase in a production cost
TECHNICAL GIST OF THE PRESENT INVENTION
Accordingly, an object of the present invention is to provide a turbo fan of which a fan body and a shroud are molded in a single metal mold, thereby reducing the number of operation processes, reducing a production cost and improving its productivity
In order to achieve the above objects, there is provided a turbo fan comprising a blade plate having a hub at its central portion to be coupled with a rotational shaft of a drive motor, a plurality of blades integrally formed at the front side of the blade plate for sucking and forcibly delivering air by being rotated with the blade plate and a shroud integrally formed at the front end section of the blades for preventing the blade from vibrating and forming a passage for the air, in which an outer diameter of the blade plate is smaller than or the same as the minimum inner diameter of the small-diameter portion
of the shroud
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of disassembled turbo fan in accordance with a conventional art, 5 Figure 2 is a vertical-sectional view of Figure 1 in accordance with the conventional art,
Figure 3 is a vertical-sectional view showing a combined state of the turbo fan in accordance with the conventional art,
Figure 4 is a plan view showing a combined state of the turbo fan from ι o rear viewing in accordance with the conventional art,
Figure 5 is a perspective view of a turbo fan in accordance with the present invention,
Figure 6 is a vertical-sectional view of the turbo fan in accordance with the present invention, 15 Figure 7 is a plan view of the turbo fan from rear viewing in accordance with the present invention, and
Figure 8 is a schematic view for explaining a method for fabricating the turbo fan in accordance with the present invention
20 DETAILED DESCRIPTION OF THE INVENTION
The turbo fan in accordance with the present invention will now be described with reference to the accompanying drawings
Figure 5 is a perspective view of a turbo fan in accordance with the present invention Figure 6 is a vertical-sectional view of the turbo fan in
accordance with the present invention and Figure 7 is a plan view of the turbo fan from rear viewing in accordance with the present invention
As shown in the drawings, the turbo fan of the present invention includes a disk-type blade plate 31 , a hub 32 protrusively formed at the central portion of the blade plate 31 so as to be coupled with a rotational shaft of a drive motor a plurality of blades 33 integrally molded in the front portion of the blade plate 31 for sucking and forcibly delivering air, and a ring-type shroud 34 integrally molded at the front end section of the blades 33 for preventing a vibration of the blades 33 and guiding the air The shroud 34 is in a ring shape and integrally molded at the front end portion of the blades 33 The rear side of the shroud 34, that is, the side contacting the blade 33, is a large-diameter portion 34a that has a larger diameter and the diameter becomes smaller as it goes toward the front side, forming a small-diameter portion 34b The air sucked by the blades 33, without being diffused passes through the large-diameter portion 34a and the small-diameter portion 34b to proceed toward the front side
The blade plate 31 is molded so that its outer diameter is smaller than or the same as the minimum inner diameter of the shroud 34 That is as shown in Figure 6, the outer diameter difference 'L' between the shroud 34 and the blade plate 31 is larger than or the same as the inner and outer diameter difference 'H' of the shroud 34
Accordingly, as shown in Figures 4 and 5, as to the rear end portion of the blades 33, about 1/3 to 1/4 of the whole the blade 33 is integrally molded at the marginal portion of the blade plate 31 , and the other portion is
exposed.
The blade 33 is formed curved in a radial direction at the front marginal portion of the blade plate 31 so as to forcibly deliver the air by generating centrifugal force or centripetal force when it is rotated with the blade plate 31. The sectional figure of the blade 33 is the same as that of the typical blade.
In this respect, in case that the upper and lower line of the blade 33 are curved and the section of the blade 33 has a crescent moon shape that the distance of the upper and lower line becomes greater as it goes from the both ends toward the center, the air is prevented from diffusing into a space between the outer circumferential portion of the blade plate 31 and the end of the blade 33. Accordingly, the turbulent air can be restrained and a noise can be prevented
The process of fabricating a turbo fan of the present invention will now be described
In the present invention, the turbo fan having the blade plate with the hub. the blades and the shroud is molded in a single metal mold.
With reference to Figure 8. a fusion such as PVC is injected into a lower metal mold (M1 ) having a predetermined shape of cavity, on which an upper metal mold (M2) is mounted having a predetermined shape to cover And then, after a certain time elapses, the fusion is hardened, and then the upper metal mold M2 is opened to take out a turbo fan.
At this time, as the blade plate 31 and the shroud 34 have sides facing to each other and thus a mutual interference may happen between them
when the turbo fan is taken out. However, the blade plate 31 is removed as wide as the area occupied by the shroud 34 in the axial direction and the rear end portion of the blade 33 is integrally molded at the marginal portion of the blade plate 31 by 1/3 to 1/4 portion of the width thereof which the other portion
5 thereof is exposed outwardly of the marginal portion of the blade plate 31. so as for the blade plate 31 and the shroud 34 not to be overlapped in the axial direction. In this manner, the product can be easily taken out
As so far described, according to the turbo fan of the present invention, such a post-process as in the conventional art in which the blade plate and
.0 the blade are molded and then the shroud is separately molded and attached to the blade is omitted. Instead, the turbo fan is fabricated with the blade plate including the hub, the blade and the shroud at one time, so that the number of working processes can be reduced. Also, since no additional metal mold is necessary, the number of the metal mold is reduced, resulting in a
.5 reduction of a production cost.
INDUSTRIAL APPLICABILITY
The turbo fan according to the present invention includes a plurality of : 0 blades at the front side of the blade plate, a shroud formed at the front end section of the blade, of which the outer diameter of the blade plate is smaller than or the same as the minimum inner diameter of the shroud. Since the turbo fan is fabricated in a single metal mold, the number of assembling processes are reduced, which leads to reduction of the number of the metal
molds required for fabricating the turbo fan, resulting in a reduction of a production cost