Duct

Abstract

A duct including a duct body is disclosed. The duct is a hollow tube and includes an air channel and an exit end. The exit end has a windward portion and an air-guiding portion on two sides thereof.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a duct of a smokestack and, more particularly, to a duct of a smokestack that provides faster heat expelling by increasing air pressure difference between interior air and exterior air.

2. Description of the Related Art

Smokestacks are commonly seen in a variety of buildings and factories. A smokestack has a duct and can create a difference in air pressure between interior air and exterior air. Heat (or waste gas) in the duct will rise, and the air pressure difference can facilitate expelling the heat in the duct while drawing clean air from the outside at the same time. When the heat gets to an exit of the smokestack, the wind will blow away the expelled heat, thereby attaining ventilation and cooling effects of the smokestack.

Referring to FIG. 1, a conventional duct 9 has an air channel 91 and an exit 92. The duct 9 can be used to construct a smokestack for some equipment such as a furnace or the like. The smokestack has an entry and an exit, and there is a big difference in air pressure between the entry and the exit. During operation of the furnace, a significant amount of heat will be generated, and the heat will rise in the air channel 91 of the duct 9. At this point, the air pressure difference will push the heat out of the duct 9. When the rising heat gets to the exit 92 of the duct 9, an air-pulling effect created by the wind blowing over the smokestack will blow away the heat. In such a manner, desired ventilation can be provided to improve burning of the furnace.

Since the exit 92 of the duct 9 has an even periphery, however, the wind tends to interact with the expelled heat at the exit 92. The interaction between the wind and the expelled heat will slow down the heat in the duct 9. As a result, heat emission and cooling efficiency of the duct 9 are impacted. In light of this problem, it is desired to improve the duct 9.

SUMMARY OF THE INVENTION

It is therefore the primary objective of this invention to provide a duct capable of increasing the air pressure difference between interior air and exterior air to better create an air-pulling effect at an exit of the duct.

It is another objective of this invention to provide a duct capable of automatically adjusting the direction thereof based on wind direction, thus maintaining the air-pulling effect at the exit of the duct.

The invention discloses a duct including a duct body. The duct is a hollow tube and includes an air channel and an exit end. The exit end has a windward portion and an air-guiding portion on two sides thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a cross-sectional view of a conventional duct.

FIG. 2 is a cross-sectional view of a duct according to a first embodiment of the invention.

FIG. 3 is an exploded view of a duct according to a second embodiment of the invention.

FIG. 4 is a cross-sectional view of the duct of the second embodiment of the invention.

FIG. 5 is a top view of a first tube of the duct rotating upon a sliding member according to the second embodiment of the invention.

FIG. 6 is a top view of the first tube of the duct resting on the sliding member according to the second embodiment of the invention.

FIG. 7 is an exploded view of a duct according to a third embodiment of the invention.

In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the term “first”, “second”, “third”, “fourth”, “inner”, “outer” “top”, “bottom” and similar terms are used hereinafter, it should be understood that these terms refer only to the structure shown in the drawings as it would appear to a person viewing the drawings, and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 2, a duct including a duct body 1 is disclosed according to a first embodiment of the invention. The duct body 1 is a hollow tube and has an air channel 11 that allows air to pass therethrough. The duct body 1 has an exit end 12 on one end thereof, and the exit end 12 may form a windward portion 13 and an air-guiding portion 14. In this embodiment, the exit end 12 forms a cut-off portion with an uneven periphery. Namely, a portion of circumferential wall of the duct body 1 is cut off at the exit end 12 to form the cut-off portion. Specifically, the windward portion 13 has two ends 131 and 132, and the two ends 131 and 132 may jointly define the air-guiding portion 14. The two ends 131 and 132 of the windward portion 13 may be parallel to a vertical direction of the duct as shown in FIG. 3, but is not limited thereto.

Referring to FIG. 2, when the duct is in use, the duct should be disposed according to wind direction. Specifically, the windward portion 13 of the duct body 1 should face the wind such that a high air pressure area A can be defined on a surface of the windward portion 13. When the strong wind of the high air pressure area A blows over the cut-off portion of the exit 12, the wind will be instantaneously speeded up due to the gradient in air pressure, creating a low air pressure area B on the air-guiding portion 14. At the instant, the air pressure difference between the high air pressure area A and the low air pressure area B will result in boundary layer separation of the airflows on the air-guiding portion 14. Therefore, eddy occurs. At the same moment, there results in a difference in air pressure between interior air and exterior air of the duct body 1, creating an air-pulling effect that pulls up the air from the air channel 11.

Referring to FIG. 2, the duct body 1 preferably comprises a narrow portion 15 which can speed up the heat passing therethrough. This causes a local low air pressure that facilitates expelling the heat of the duct body 1 and therefore provides improved air circulation.

Referring to FIGS. 3 and 4, a duct is disclosed according to a second embodiment of the invention. The duct body 1 also has the exit end 12, windward portion 13, air-guiding portion 14 and narrow portion 15 described in the first embodiment. The duct of the second embodiment differs from that of the first embodiment in that the duct body 1 consists of a first tube 1a and a second tube 1b. The first tube 1a has a first air channel 11a and the second tube 1b has a second air channel 11b. The exit end 12, windward portion 13, air-guiding portion 14 and narrow portion 15 are formed on one end of the first tube 1a.

The first tube 1a and the second tube 1b are coupled together in various conventional ways. As shown in FIG. 3, the first tube 1a and the second tube 1b are coupled together via a sliding member 16. In this embodiment, the first tube 1a further comprises a first coupling member 17a abutting against one face of the sliding member 16, with the other face of the sliding member 16 coupled with a coupling seat 17b of the second tube 1b. In such a manner, the sliding member 16 can support the first tube 1a and allow the first tube 1a to rotate about the second tube 1b. The sliding member 16 may be a ball bearing, a needle bearing, a sliding bearing, a magnetic suspension bearing, a hydraulic bearing, a tapered and cylindrical roller bearing or any similar structures that can support the first tube la and provide rotation therefor. In this embodiment, the sliding member 16 is implemented as the tapered and cylindrical roller bearing.

The first tube 1a may further comprise a pair of wings 18 capable of generating a torque when the direction of the wind changes. The wings 18 are shown to be arranged on the first tube 1a for illustration purpose. Specifically, the wings 18 are aligned with each other in a radial direction of the duct while located at two opposing positions on an outer circumferential face of the first tube 1a. Further, the wings 18 are preferably located on two ends of the windward portion 13 and aligned with the cut-off portion of the exit end 12. Specifically, the wings 18 are aligned with the cut-off portion in such a way that the wings 18 are aligned with the two ends 131 and 132 of the windward portion 13 in the vertical direction. In addition, the wings 18 are preferably not higher than the cut-off portion of the exit end 12 in order not to disturb the eddy system at the exit end 12.

Referring to FIGS. 5 and 6, operation diagrams of the wings 18 and the sliding member 16 are shown. The wings 18 can define a central reference line X having two ends. The two ends of the central reference line X may experience different wind strength. For example, referring to FIG. 5, one end of the central reference line X may experience larger wind strength than the other one. In this case, the wings 18 will be driven by the wind and therefore cause the first tube 1a to rotate via the sliding member 16 until the two ends of the central reference line X experience the same wind strength. By the time the first tube 1a stops rotating, the windward portion 13 of the first tube 1a will face the wind, allowing eddies to be generated at the exit end 12 of the first tube 1a. The eddies will help blow away the expelled heat of the duct. In such an arrangement, the duct in the second embodiment can automatically adjust the direction of the windward portion 13 based on wind direction, thereby providing faster heat emission.

Referring to FIG. 7, a duct is disclosed according to a third embodiment of the invention. In the third embodiment, the duct also has the first tube 1a, second tube 1b and narrow portion 15 described above. The duct of the third embodiment differs from those of the first and second embodiments in that the exit end 12 has an inclined periphery. Similar to the first and second embodiments, the duct in this embodiment also has the windward portion 13 and the air-guiding portion 14. Thus, it will be more convenient to manufacture the first tube 1a.

The duct of the invention can be installed on a roof of a building to expel dirty air of the building. Further, the duct of the invention can also construct a part of a smokestack for a conventional furnace or the like. In generally, the furnace will generate a significant amount of heat during the burning process thereof. Since the heat has a smaller density, the heat will rise in the duct. At this point, the air-guiding portion 14 can increase the speed of airflows, creating a low air pressure area B and resulting in an air pressure difference between interior air and exterior air of the duct. Thus, the heat at the exit 12 will be blown away quickly by wind while external clean air is drawn into the duct via the bottom end of the duct, thereby providing improved burning of the furnace.

Although the invention has been described in detail with reference to its presently preferable embodiment, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.

Claims

1. A duct comprising a duct body being a hollow tube, wherein the duct comprises an air channel and an exit end, and the exit end has a windward portion and an air-guiding portion on two sides thereof.

2. The duct as claimed in claim 1, wherein the duct body further comprises a narrow portion.

3. The duct as claimed in claim 1, wherein the duct body further comprises a first tube and a second tube coupled with the first tube via a sliding member.

4. The duct as claimed in claim 3, wherein the sliding member is a ball bearing, a needle bearing, a sliding bearing, a magnetic suspension bearing, a hydraulic bearing or a tapered and cylindrical roller bearing.

5. The duct as claimed in claim 3, wherein the first tube further comprises a pair of wings.

6. The duct as claimed in claim 5, wherein the wings are aligned with the exit end.

7. The duct as claimed in claim 1, wherein the exit end is formed as a cut-off portion.

8. The duct as claimed in claim 1, wherein the exit end has an inclined periphery.