KR101463455B1

KR101463455B1 - Exhaust ventilation of re-spread prevention and Increasing the displacement

Info

Publication number: KR101463455B1
Application number: KR1020140107107A
Authority: KR
Inventors: 최상도; 최지원
Original assignee: (주) 토네이도테크
Priority date: 2014-08-18
Filing date: 2014-08-18
Publication date: 2014-11-21

Abstract

More particularly, the present invention relates to an exhaust system, and more particularly, to an exhaust system, and more particularly, to an exhaust system, To prevent the air from being re-diffused due to the bell mouth which is spaced apart from the bell mouth, and to prevent the air from being re-diffused and capable of increasing the amount of exhausted air, will be.
Accordingly, the present invention provides an exhaust device for preventing the re-diffusion and increasing the amount of exhaust, comprising: a housing having an interior formed in a hollow shape and having an exhaust pipe formed on one side thereof for discharging air introduced into the interior thereof; The exhaust fan according to any one of claims 1 to 3, further comprising: a motor having a rotating shaft, an exhaust fan mounted on the rotating shaft of the motor, a rotatable fan disposed coaxially with the exhaust fan, A blowing fan connected to the side flow type fan and connected to the blowing fan so as to rotate at the same time when the side flow type fan rotates and to introduce the outside air into the blowing fan; A mouth and a bell mouth extending from the one end of the bell mouth in a vertical direction and having a tilt inclined inward at a predetermined portion, That shrouds; comprises a.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an exhaust system,

More particularly, the present invention relates to an exhaust system, and more particularly, to an exhaust system, and more particularly, to an exhaust system, To prevent the air from being re-diffused due to the bell mouth which is spaced apart from the bell mouth, and to prevent the air from being re-diffused and capable of increasing the amount of exhausted air, will be.

Exhaust systems, or ventilators, are generally used in factories, homes, restaurants, etc. where pollution sources are frequent. The ventilator is useful when it is difficult to install the exhaust pipe near the pollution source due to the partial pollution source on the floor away from the exhaust pipe, or when the pollution source occurs momentarily. In addition to pollution sources, the ventilator discharges the odor and moisture generated in the bathroom of the home to the outside.

Such a fan has various problems in performance. As the ventilator moves away from the exhaust pipe, the efficiency of removing the pollutant source sharply decreases. For example, if the odor and moisture generated in the bathroom stays near the floor, it is difficult to discharge because the distance to the ceiling fan is too far. Further, the fan installed in the closed room has a problem that a great noise is generated due to driving of the motor and rotation of the fan.

Therefore, although it is preferable that the ventilator is installed close to the position where possible pollutants are generated, it interferes with the work process and the movements of the workers, and there is a restriction on the installation condition because there is a distance from the floor to the ceiling. In order to solve this problem, a ventilator has been developed which uses a vortex to expand the exhaust area. In the vortex type fan, a fan generating a vortex is installed on the suction port side of the exhaust pipe and the fan is rotated. The fan generates a vortex in the form of a donut around the exhaust pipe, thereby efficiently sucking contaminated air into the exhaust pipe.

However, before the suction flow into the exhaust housing, the flow of the blades is stronger than before, so the products developed so far have not solved the problem of re-diffusion. Attempts have been made to increase the suction flow rate of the exhaust port to solve the problem, but there is a limit and there is a problem that the power consumption is increased. For this reason, even though the size of the vortex is increased by maximizing the rotational force of the fan, in the conventional vortex type fan structure, due to various structures including the motor provided between the fan and the exhaust pipe due to the vortex generated by the fan, And the noise is increased due to the turbulence caused by the mutual interference between the flow blowing in the narrow region below the exhaust pipe and the suction flow, and by the flow blown into the space, There is a fear that the additional diffusion of the pollution may occur.

As a conventional technique for solving the above problems, Korean Patent Registration No. 10-0821295 (Apr. 03, 2008) discloses a vortex type local exhaust system in which an exhaust pipe is installed at a suction port, A swirler rotating about the exhaust pipe; And at least two vortex-type local exhaust systems provided in the exhaust pipe, wherein the vortex-type local exhaust systems include a driving unit for rotating the swirler, wherein each of the vortex- Wherein the swirlers are arranged such that the swirlers are directed in the same direction, and the adjacent pair of vortex-type local exhaust devices are arranged in such a manner that the areas of the vortexes of the adjacent vortexes are mutually spaced apart from each other, System is known.

However, although the vortex type local exhaust system includes a plurality of vortex-type local exhaust systems, a large amount of polluted air can be sucked in, but the amount of power used is increased. In addition, contamination sources are provided between the fan and the exhaust pipe. Therefore, there is a problem that the vortex and the pollutant source are reflected to the structure to cause the discharge of the pollutant in the direction of the pollutant source, and the pollutant introduced by the fan moves rapidly toward the exhaust pipe.

As another conventional technique for solving the above problems, Korean Patent Application No. 10-2012-0102049 discloses a vortex type ventilator having a bell mouth. The vortex type ventilator has an inner hollow cylindrical shape, and one end has an inner diameter larger than the other side ; A motor provided inside the housing; A rotating shaft mounted on the motor; A first fan including a rotating plate mounted on the rotating shaft and having a curved shape with an outer edge bent toward the motor and a plurality of blades disposed along the outer edge of the rotating plate and fixed in a radial direction; A bell mouth surrounding the first fan at a lower portion of the first fan; And a second fan mounted on the rotating shaft and provided at a lower portion of the bell mouth, the second fan being composed of a plurality of individual blades combined with each other at a predetermined angle with respect to the radial direction, and a vortex- .

However, in the above-described conventional technique, the central portion of the rotating shaft is clogged, and the amount of re-discharged by the rotational force of the wing is larger than the inflow amount into the housing. That is, the contamination source introduced into the central portion by the first fan has a drawback that the second fan installed inside the housing is stronger than the suction force of the second fan, resulting in additional re-diffusion.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide an air conditioner and an air conditioner in which a blowing fan rotates to generate a vortex, And an object of the present invention is to provide an exhaust device for preventing re-diffusion of air introduced by a bell mouth and for increasing the amount of exhaust.

In addition, the shroud extending perpendicularly to the bell mouth has a shroud structure in which the shroud is formed in a shape of an upper light having a slope inward at a certain portion, so that the air introduced into the shroud is quickly discharged to the exhaust pipe, And to provide an exhaust device for preventing diffusion and increasing the amount of exhaust.

In addition, when the exhaust fan is driven, due to the strong suction flow speed of the exhaust fan, the side flow type fan and the blowing fan are rotated to operate the side flow type fan and the blowing fan in order to prevent energy saving and resonance, So as to provide an exhaust device.

According to an aspect of the present invention, there is provided an exhaust device for preventing re-diffusion and increasing the amount of exhaust, comprising: a housing having an internal hollow formed therein and having an exhaust pipe formed on one side thereof for discharging air introduced into the interior thereof; An exhaust fan that is mounted on the rotary shaft of the motor and rotates by an intake flow rate of the exhaust fan when the exhaust fan is rotated while being vertically aligned with the exhaust fan; A blower fan connected to the fan and connected to the blower fan to blow the outside air into the blower fan while being rotated simultaneously with the rotation of the side air fan, and a bell mouth horizontally spaced apart from the blower fan by a predetermined distance; And a bell mouth which is vertically extended from the one end of the bell mouth and is fixed to the housing in a shape of an upper light having a slope inclined inward at a predetermined portion It comprises a; loud.

The side-stream type fan is equipped with a bearing for stable rotation and a gear for supporting the rotation of the blowing fan by transmitting the rotational force of the side-stream type fan to the blowing fan between the side-flow type fan and the blowing fan.

The blowing fan includes a rotating plate connected to the connecting shaft, and a plurality of blades disposed along the edge of the rotating plate and fixed in an upright state.

In the operation of the blowing fan, a vortex is generated by the contact surface of the blade and the rotating plate, and air flows into the periphery of the blowing fan along the circumference of the blowing fan by a pressure difference due to vortex formation and an air flow direction.

A plurality of connection rods are formed to connect the center portion and the rotary plate so that the rotary plate can rotate along the connection axis.

Wherein the blowing fan includes a rotating plate rotating along a connecting shaft and a plurality of connecting rods disposed along an outer circumferential surface of the rotating plate and fixing the connecting rods to form wings along the connecting rod edges, And a circular band member formed in a circular band shape.

The wings form an insertion groove and a part of the bell mouth is inserted.

The vortex is generated by the rotating plate and the vanes when the blowing fan is operated. By the air pressure difference due to vortex formation and the air flow direction, air is drawn to the outer peripheral surface of the vane and hits against the inner wall of the circular band member, do.

The blowing fan is provided at its lower end with an expansion plate having a diameter larger than the diameter of the blowing fan.

According to the present invention, the effect of preventing the rediffusion of the air introduced into the housing due to the bell mouth formed at the half height of the blowing fan and the expansion plate formed at the lower end of the blowing fan can be prevented have.

In addition, since the vortex is formed by the rotation of the air blowing fan, the air flow rate is increased due to the air pressure difference generated by the air flow and the upper and lower light shade structure, so that the air containing the contamination source is rapidly exhausted.

Also, by driving the exhaust fan, the side flow type fan and the blowing fan are simultaneously rotated due to the strong suction flow speed of the exhaust fan, so that the air including the contamination source flows into the inside, There is an effect to save resonance and to prevent resonance.

1 is a perspective view showing an embodiment according to the present invention;
2 is a cross-sectional view showing an embodiment according to the present invention;
3 is a perspective view illustrating a blowing fan having an insertion groove according to an embodiment of the present invention;
FIG. 4 is another perspective view illustrating a blowing fan having an insertion groove according to an embodiment of the present invention. FIG.
5 is a perspective view showing a blowing fan in which a connecting rod is formed according to an embodiment of the present invention;
6 is a perspective view showing a blowing fan in which an insertion groove and a connecting rod are formed according to an embodiment of the present invention;
7 is a perspective view showing a blowing fan in which a circular strip member is formed in an embodiment according to the present invention.
8 is a perspective view showing a blowing fan in which an insertion groove and a circular strip member are formed in an embodiment according to the present invention.
9 is an exemplary view showing a use state in an embodiment according to the present invention.

The present invention relates to an exhaust device for preventing re-diffusion and increasing the amount of exhaust, comprising: a housing having an interior formed in a hollow shape and having an exhaust pipe formed on one side thereof for discharging air introduced into the interior thereof; An exhaust fan that is mounted on the rotary shaft of the motor and rotates by an intake flow rate of the exhaust fan when the exhaust fan is rotated while being vertically aligned with the exhaust fan; A blower fan connected to the fan and connected to the blower fan to blow the outside air into the blower fan while being rotated simultaneously with the rotation of the side air fan, and a bell mouth horizontally spaced apart from the blower fan by a predetermined distance; And at least one bell mouth extending from the one end of the bell mouth in a vertical direction and having a slope inclined inward at a predetermined portion, Wood; including characterized in that formed.

The side-stream type fan is equipped with a bearing for stable rotation and includes a gear for transmitting the rotational force of the side-flow type fan to the blowing fan between the side-flow type fan and the blowing fan to assist rotation of the blowing fan.

The blowing fan may include a rotating plate connected to the connecting shaft, and a plurality of blades disposed along the edge of the rotating plate and fixed in an upright state.

Further, in the operation of the blowing fan, a vortex is generated by the contact surface of the blade and the rotating plate, and air is introduced into the periphery of the blowing fan along the circumference of the blowing fan by the air pressure difference due to the vortex formation and the air flow direction .

In addition, a plurality of connecting rods are formed to connect the center portion and the rotary plate so that the rotary plate can rotate along the connection shaft.

The blowing fan may include a rotating plate that rotates along a connecting shaft and a plurality of connecting rods disposed along an outer circumferential surface of the rotating plate so as to form wings along the connecting rod edges. And a ring-shaped band member formed in a ring-shaped band shape.

Also. The wings form an insertion groove, and a part of the bell mouth is inserted.

In addition, when the blowing fan operates, a vortex is generated by the rotating plate and the vanes, and air is drawn to the outer peripheral surface of the vane by the air pressure difference due to vortex formation and the air flow direction, Is introduced.

Further, the blowing fan is characterized in that an expansion plate having a diameter larger than the diameter of the blowing fan is provided at the lower end.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment of an exhaust device for preventing redeposition and increasing exhaust amount according to the present invention will be described in detail with reference to the drawings. Prior to this, terms and words used in the present specification and claims are to be interpreted in accordance with the technical idea of the present invention based on the principle that the inventor can properly define the concept of the term in order to explain his invention in the best way. It must be interpreted in terms of meaning and concept.

As shown in FIGS. 1 and 2, an exhaust device for preventing the redeposition and increasing the exhaust amount according to the present invention includes a housing 10, a motor 20, an exhaust fan 30, A blower fan 40, a blower fan 50, a bell mouth 60 and a shroud 70.

The housing 10 is open at one end thereof, is formed in a hollow shape, and has an exhaust pipe 13 formed at one side thereof for discharging air to the inside thereof.

The housing 10 accommodates a motor 20 and an exhaust fan 30 therein and a shroud 70 is seated on the upper end of the housing 10 to receive a part of the shroud 70 therein Respectively.

The exhaust pipe (13) is formed on one side of the housing (10) and discharges the air introduced into the outside.

The motor 20 is installed inside the housing 10 and mounts a rotary shaft 23 thereon. The rotary shaft 23 rotates when the motor 20 is operated to rotate the exhaust fan 30. The motor 20 is fixed by the motor case and housed in the housing 10.

The exhaust fan 30 is mounted on the rotary shaft 23 of the motor 20 and rotates to generate a strong suction flow rate during rotation. The exhaust fan 30 is made up of a plurality of individual blade combinations that are angled at an angle relative to the radial direction.

It is preferable that the exhaust pipe 13 is eccentric to the left at a predetermined interval with respect to the rotary shaft 23 which is the center of rotation of the exhaust fan 30. That is, when the exhaust pipe 13 is viewed from the front, the diameter connecting the upper end and the lower end of the exhaust pipe 13 is not located on the same line as the rotation axis 23, but is deviated to the left by a predetermined distance relative to the rotation axis 23. This is to discharge the air including the contamination source to be delivered more effectively while the exhaust fan 30 rotates.

The side flow type fan (40) is positioned on the same line perpendicular to the exhaust fan (30). The side flow type fan 40 rotates due to the strong suction flow velocity generated when the exhaust fan 30 is operated.

The side-stream type fan 40 is connected to the blowing fan 50 by attaching a connecting shaft 41 thereto. A bearing 42 is provided under the side-flow fan 40 so that the rotating side-flow fan 40 can be fixed at a predetermined position and rotated stably.

The side-flow fan (40) has a gear (44) on a connecting shaft (41) between the fan (50) and the blower fan (50). The gear 44 transmits rotational force to the blowing fan 50 during rotation of the side-stream type fan 40 to assist in rotating the blowing fan 50 at the same time.

The blowing fan 50 is connected to the connecting shaft 41 and rotates around the connecting shaft 41 to generate a vortex. The blowing fan 50 is mounted on the connecting shaft 41 and includes a rotating plate 52 having an outer edge bent toward the motor 20 and having a curved shape and a plurality of the rotating plates 52 disposed along the outer edge of the rotating plate 52, And a wing (54) fixed in the state.

The rotating plate 52 is formed in a curved shape whose outer edge is bent in a downward direction (motor 20 direction). This prevents the air or the like including the contaminants introduced by the vortex formed by the rotation of the air blowing fan 50 from being reflected in the reverse direction against the rotating plate 52 so that the air including the contamination source can be quickly discharged to the exhaust pipe 13 .

The rotating plate (52) has a wide contact surface to enhance vortex formation, and air, including contaminants, can easily flow into the interior of the swash plate (52).

The vanes 54 are preferably fixed on the upper surface of the rotary plate 52 so as to be perpendicular to the disk surface. It is preferable that the wing 54 is formed with an inclined portion in a portion of the vane 54 positioned on the rotation center side so that the height of the wing 54 decreases gradually toward the rotation center of the rotation plate 52. This is because the frictional resistance with air decreases in the direction of the rotation center of the rotary plate 52 when the blowing fan 50 rotates and the air inside the rotary plate 52 moves away from the rotation center of the rotary plate 52 in the outward direction And more efficiently.

When the air blowing fan 50 rotates, the rotating plate 52 and the blades 54 push the air inside the rotating plate 52 outward in the radial direction of the rotating plate 52. When the contaminated air is sucked into the exhaust pipe 13, not only the contaminated air sucked but also the surrounding air tends to enter the inside of the exhaust pipe 13 and the outer periphery of the rotating plate 52. Due to the flow of air, a pressure difference is generated in the lower portion of the rotary plate 52, and a flow direction of the air is formed.

3 and 4, the ventilation fan 50 forms an insertion groove 55 in the blade 54 to insert a part of the bell mouth 60 therein. The blowing fan 50 in which the insertion groove 55 is formed is preferably formed to have a diameter larger than that of the blowing fan 50 shown in FIGS. 1 and 2 so that a part of the bell mouth 60 is inserted. The blowing fan 50 having the insertion groove 55 blocks the clearance between the blades 54 and the bell mouth 60 to prevent the air introduced into the blades 54 from diffusing again.

The insertion groove 55 is formed in the direction of the bell mouth 60 so that the open surface such as a 'C' shape is formed in the direction of the bell mouth 60. It is preferable that the insertion groove 55 is formed to be larger than the thickness of the bell mouth 60 so as not to interfere with the rotation of the vane 54. The blowing fan 50 in which the insertion groove 55 is formed prevents the air including the inflowing contamination source from diffusing again.

5, a penetrating portion 57 is formed on the inner side so as to allow air to flow into the inside of the rotating plate 52, and a plurality of through- A plurality of connection rods 56 for connecting the central portion 50a and the rotary plate 52 are formed so that the rotor 52 can rotate. It is possible to introduce air into the penetrating portion 57 formed between the connecting rods 56 when the blowing fan 50 rotates. Therefore, it is possible to increase the amount of air to be introduced.

As shown in FIG. 6, the air blowing fan 50 may also have an insertion groove 55 formed in the blade 54. A part of the bell mouth 60 is inserted into the insertion groove 55 to prevent the air including the inflowing contamination source from diffusing again. It is preferable that the insertion groove 55 is formed to be larger than the thickness of the bell mouth 60 so as not to interfere with the rotation of the vane 54.

7, a plurality of connecting rods 56 are arranged along the outer circumferential surface of the rotating plate 52 having the disk shape and the rotary plate 52, and a plurality of connecting rods 56, And a circular band member 58 having a predetermined height and formed in a circular band shape is formed through the plurality of connection rods 56. [

The radius of the circular band member 58 is formed to be larger than the radius of the rotary plate 52 but smaller than the radius of the outer circumferential surface of the connection rod 56. The circular strip member 58 is pulled in the direction of the wing 54 by the air containing the contamination source introduced into the central portion 50a by the high speed rotation and then strikes against the inner wall of the circular strip member 58 so that the contamination source flows into the penetration portion 57 do.

As shown in Fig. 8, the blowing fan 50 can also form an insertion groove 55 in the blade 54 of the blowing fan 50 of Fig. A part of the bell mouth 60 is inserted into the insertion groove 55 to prevent the air including the inflowing contamination source from diffusing again. It is preferable that the insertion groove 55 is formed to be larger than the thickness of the bell mouth 60 so as not to interfere with the rotation of the vane 54.

The blowing fan 50 may also be provided with an extension plate 49 at the lower end of the blowing fan 50 to prevent re-diffusion. The expansion plate 49 is formed to be larger than the diameter of the blowing fan 50 to prevent the air including the contaminant introduced when the blowing fan 50 rotates from being diffused again.

In addition to the air blowing fan shown in the drawing, the air blowing fan 50 may be a variety of fans such as a sirocco fan, a turbo fan, a reel fan, an alternating fan, and a radial fan.

The bell mouth 60 is horizontally formed at a predetermined distance from the blowing fan 50 at a half height of the blowing fan 50. The bell mouth 60 increases the flow rate of the air including the contamination source to the empty space separated from the blowing fan 50 during the rotation of the blowing fan 50 without decreasing the flow rate.

The shroud 70 is formed in a vertical direction in the bell mouth 60 and has a sloped inclined inner surface at a predetermined portion. The portion of the shroud 70 where the inclination starts is seated and fixed to the housing 10.

The shroud 70 is formed in a shape of a lower light shield so as to increase the flow rate of air including pollutants introduced into the interior of the shroud 70, thereby increasing the amount of exhaust.

The exhaust fan 30 mounted on the rotary shaft 23 is rotated by the driving of the motor 20 as shown in Fig. 9 in the embodiment of the exhaust device for preventing the redeposition and increasing the exhaust amount according to the present invention, The side flow type fan 40 rotates at a strong suction flow velocity of the fan 30. [ As the side flow type fan 40 rotates, the blowing fan 50 also rotates.

A vortex is formed by the rotating plate 52 and the vanes 32 of the blowing fan 50 and the air including an external contamination source flows into the inside by the air pressure difference due to the vortex and the formation of the air flow direction. Due to the strong suction flow velocity of the exhaust fan 30 and the slope of the shroud 70, the air introduced into the interior increases the flow rate of the air without decreasing the flow rate and discharges the air to the exhaust pipe 13.

It will be apparent to those skilled in the art that various modifications, substitutions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. will be. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are intended to illustrate and not to limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments and the accompanying drawings . The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10: housing 13: exhaust pipe 20: motor
23: rotary shaft 30: exhaust fan 40: side flow fan
41: connecting shaft 42: bearing 44: gear
49: extension plate 50: blower fan 50a: center
52: spindle 54: wing 55: insertion groove
56: connecting rod 57: penetrating part 58: circular strip member
60: Bell Mouth 70: Shuraud

Claims

A housing having an interior formed in a hollow shape and having an exhaust pipe formed on one side thereof for discharging air introduced into the interior thereof;
A motor provided inside the housing and having a rotation axis;
An exhaust fan mounted on the rotating shaft of the motor and rotated;
A side-flow fan which is positioned in the same vertical line as the exhaust fan and is rotated by an intake flow rate of the exhaust fan when the exhaust fan is rotated;
A fan connected to the counterflow fan and connected to the fan, the fan rotating simultaneously with the rotation of the counterflow fan to introduce outside air into the fan;
A bell mouth which is horizontally formed at a predetermined distance from the blowing fan at a half height of the blowing fan;
And a shroud extending in a vertical direction at one end of the bell mouth and being fixed to the housing in a shape of an upper light having a slope inclined inward at a certain portion. Device.

The method according to claim 1,
Wherein the side-stream type fan is equipped with a bearing for stable rotation and a gear for transmitting rotation force of the side-stream type fan to the air blowing fan to assist rotation of the air blowing fan between the side-stream type fan and the air blowing fan. And an exhaust device for increasing the exhaust amount.

The method according to claim 1,
Wherein the blowing fan includes a rotating plate connected to the connecting shaft, and a plurality of blades disposed in an upright position along the edge of the rotating plate to prevent re-diffusion and to increase the amount of exhaust.

The method of claim 3,
Characterized in that a vortex is generated by the contact surface of the blade and the rotating plate during operation and air is introduced into the periphery of the blowing fan along the circumference of the blowing fan by a pressure difference due to vortex formation and an air flow direction, And an exhaust device for increasing the amount of exhaust.

The method of claim 3,
Wherein a plurality of connection rods are formed to connect the center portion and the rotary plate so that the rotary plate can rotate along the connection shaft. .

The method according to claim 1,
Wherein the blowing fan includes a rotating plate rotating along a connecting shaft and a plurality of connecting rods disposed along an outer circumferential surface of the rotating plate and fixing the connecting rods to form wings along the connecting rod edges, Characterized in that the exhaust gas purification device comprises a ring-shaped band member formed in a circular strip shape.

The method according to any one of claims 3 to 6,
Wherein the wing forms an insertion groove, and a part of the bell mouth is inserted into the insertion hole, thereby preventing re-diffusion and increasing the amount of exhaust.

The method of claim 6,
The vortex is generated by the rotating plate and the vanes when the blowing fan is operated. By the air pressure difference due to vortex formation and the air flow direction, air is drawn to the outer peripheral surface of the vane and hits against the inner wall of the circular band member, Wherein the exhaust gas is supplied to the exhaust pipe.

The method according to claim 1,
Wherein the blowing fan is provided with an expansion plate having a diameter larger than the diameter of the blowing fan at the lower end thereof.