JPH05157306A - Air discharging device - Google Patents

Abstract

PURPOSE:To provide an air discharging device for forming a superior tornado flow even if an air blowing column is eliminated. CONSTITUTION:An air discharging device is comprised of an air suction port 3 arranged at a hood 7 and an air blowing port similarly arranged at a hood 6. The air blowing port is comprised of a primary air blowing port 4 with its air blowing direction being substantially oriented toward a tangential line on an imaginary circle having as its center an axis of suction flow and a secondary air blowing port 5 arranged to be substantially in an opposite direction to that of the suction flow on another imaginary circle with an axis of the suction flow being applied as a center so as to generate a tornado flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust device suitable for exhausting a local area of an arbitrary space.

[0002]

2. Description of the Related Art It is known that when a vortex flow similar to a tornado flow is formed and exhausted to an air inlet, the air in the zone can be exhausted even with a small amount of treated air.

For example, Japanese Laid-Open Patent Publication No. 58-223444 discloses a device for forming a vortex in a box-shaped experimental hood so that dust generated in the hood is discharged to the outside of the hood without leaking to the outside. ing.

Similarly, Japanese Patent Laid-Open No. 62-178826 discloses that a space inside a pillar is surrounded by a cylindrical air curtain by blowing air from a plurality of blowing pillars in the circumferential direction. Disclosed is a harmful gas diffusion preventing device for generating a topping flow in the space by exhausting the air from the inside.

[0005]

The devices of any of the above-mentioned publications use the blown air flow as a driving force for swirling the suction air flow. Therefore, an air outlet is provided around the suction air flow. Although it is provided, in the case of the former publication, it is limited to the air flow control in the box called the experimental hood, and for this reason, it cannot be used to exhaust only a certain local area in the space.

The latter publication is suitable for exhausting only a certain area in the space, but since it is necessary to erect a plurality of air outlet columns, it is limited to the space where the air outlet columns can be installed. In addition, there is a problem that this blowout column restricts the work space.

The present invention is intended to solve such a problem and, as in the latter publication, it is possible to generate a vortex flow similar to a good tornado air flow even without the blowing column. The exhaust system is intended to be provided.

[0008]

An exhaust system according to the present invention comprises an air inlet provided in a hood and an air outlet provided in the same hood, and the air outlet has a suction flow axis as a center. On the imaginary circle, the primary outlets are arranged so that the outlet direction is almost tangential, and on the other imaginary circles around the axis of the inlet flow, the outlet direction is directed in the direction almost opposite to the inlet flow. It consists of a secondary outlet arranged.

[0009]

[Operation] When the air in the space below the hood is sucked vertically upward from the suction port provided in the exhaust hood, the air is injected from the primary outlet provided near the suction port so that a swirl flow is formed around the suction flow. When air is blown downward from the secondary outlet provided in the vicinity of the primary outlet, the air in the space below the hood becomes a good tornado state and is exhausted to the inlet. In other words, unlike the Japanese Patent Laid-Open No. 62-178826, a tornado air flow is generated below the hood without providing a blow column, and the suction port can be provided without polluting the surroundings from the dust or harmful gas generation source existing under the hood. The exhaust is led to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an exhaust system of the present invention for exhausting a tornado flow that forms vertically upward. This exhaust device 1 has the shape of a canopy hood as a whole, and the whole thereof is installed above the dust generation source 2.

In the exhaust device 1 of the present invention having the shape of a canopy hood as a whole, an air suction port 3, a primary outlet 4 and a secondary outlet 5 are provided in the hood in a predetermined relationship. A tornado flow is formed in the lower space by the suction and blowout of the air. The structure will be described in detail below.

The hood is composed of an outer hood 6 and an inner hood 6, and a space between the outer hood 6 and the inner hood 6 serves as an air supply chamber 8.

The air suction port 3 has a cylindrical shape in which the suction port diameter is reduced toward the inside, and is installed in the center of the inner hood 6 with the suction port facing downward. The cylinder forming the air suction port 3 is connected to an exhaust air passage 10 in which an exhaust fan 8 is installed. The exhaust air passage 10 with the exhaust fan 8 installed therein is disconnected from the supply air chamber 8
After passing through the inside, it penetrates the outside air hood 6 and is connected to the exhaust port 11. In the illustrated example, the exhaust port 11 is provided on the side of the jacket hood 6, and a unit filter 12 is detachably attached to the exhaust port side of the exhaust air duct 10. With this configuration, when the exhaust fan 8 is driven, the air in the space below the hood is sucked into the air suction port 3, passes through the exhaust air passage 10, is dust-removed by the filter 12, and is then discharged from the exhaust port 11 to the outside of the apparatus.

On the other hand, a primary outlet 4 and a secondary outlet 5 are provided outside the air inlet 3. These air outlets are attached to a hollow outer cylinder 15 having an inner peripheral surface 14 which is separated from the outer peripheral wall 13 of the cylindrical body for forming the air suction opening 3 by a predetermined distance. That is, the hollow outer cylinder 15 is formed as a part of the air supply chamber 8 and the primary outer outlet 4 whose outlet direction is tangential to the inner peripheral surface 14 of the hollow outer cylinder 15 and the hollow outer cylinder The bottom plate of the cylinder 15 is provided with a secondary outlet 5 whose outlet direction is downward.

As shown in the bottom view of FIG. 2, a plurality of primary outlets 4 are provided on the inner peripheral surface 14 of the hollow outer cylinder 15 with the outlet direction directed substantially tangentially (slightly inward of the tangent) (illustrated). In the example of (4), they are arranged at equal intervals), and each is composed of air injection nozzles of the same shape.

As shown in the bottom view of FIG. 2, a plurality of secondary outlets 5 are provided on the bottom surface 16 of the hollow outer cylinder 15 with the outlet direction facing downward (in the illustrated example, at regular intervals in the circumferential direction). To 4)
They are arranged, and they consist of slits with long sides in the circumferential direction. The plurality of air injection nozzles forming the primary outlet 4 and the slit forming the secondary outlet 5 are all the axes of the suction airflow sucked into the suction inlet 3 (actually, the center of the cylinder forming the suction inlet 3). It is placed on a virtual circle centered on the axis.

The inner space of the hollow outer cylinder 15 in which the primary outlet 4 and the secondary outlet 5 are provided has an outer hood 6 and an inner hood 7.
Since it is part of the air chamber 8 surrounded by,
When air is sent into the air chamber 8, it is blown out as a jet from these air outlets. This air chamber 8
Air is supplied to the inside by the air supply fan 18.

In the illustrated embodiment, the fan case 19 of the air supply fan 18 is installed in the air supply chamber 8, and the discharge port 20 of the fan case is opened in the air supply chamber 8. An air intake 21 to the fan case 19 is provided on the outer side (upper surface) of the jacket hood 6. A filter unit 22 is detachably attached near the air intake 21. Reference numeral 23 indicates a fan motor. The fan motor 23 is shared by both the air supply fan 18 and the exhaust fan 9, and both fans are rotated by its drive. However, the exhaust fan 9 is designed to have a larger amount of air blow than the air supply fan 18 by a predetermined amount.

1 to 2 according to the present invention, the air in the space below the hood is sucked from the suction port 3 located substantially in the center of the inner hood 7 by the operation of the exhaust fan 9 and the exhaust port 11 The air discharged and taken in from the air intake 21 at the upper part of the jacket hood 6 by the operation of the air supply fan 18 reaches the hollow outer cylinder 15 via the air supply chamber 8.
The air is blown out from the primary outlet 4 and the secondary outlet 5 provided in the hollow outer cylinder 15, respectively.

At that time, the blowout flow from the primary outlet 4 is
A swirling flow is formed in the annular space between the outer peripheral wall 13 of the suction port 3 and the inner peripheral surface of the hollow outer cylinder 15, and after rotating around this annular space, it keeps its rotation and moves downward away from the annular space. At the same time, a downward airflow is formed from the secondary outlet 5, and the swirl flow and the downward blowout flow form a vortex in the suction flow toward the suction port 3. This vortex flow having an upward component is attracted and transmitted downward, and becomes a tornado flow that converges as it goes upward as a whole. Therefore, the dust existing inside the tornado flow rides on the vortex flow toward the suction port 3 without being diffused to the surroundings.
Therefore, when the dust generating source 2 is positioned below the exhaust device of the present invention, the dust generated from the dust generating source 2 rides on the tornado flow and is discharged from the suction port 3.

FIG. 3 shows another example of the exhaust system according to the present invention. In this example, the horizontal hood plate (disc)
A donut-shaped hollow cylinder 26 is attached to the lower surface of the periphery of 25, and a primary outlet 4 and a secondary outlet 5 are provided in this hollow cylinder 26 in the same relationship as in the previous example, and a suction port 3 is provided in the center of the hood plate 25. It is provided, and air is blown into the hollow cylinder 26 by a blower 27, and the suction port 3 is connected to a blower 28 by a duct.

In the case of FIG. 3, the suction port 3 is an opening provided on the surface of the hood plate 25, and therefore differs from the previous example in that it does not project downward from the hood plate 25. Also with this configuration, the air flow from each of the primary outlets 4 (four air injection nozzles similar to the previous example) provided on the inner peripheral surface 14 of the hollow cylinder 26 with the outlet direction substantially in the tangential direction is inside the outlet. Circumference 14
While swirling along, the swirl force is applied to the suction flow that descends in the end of the space below the exhaust system and rises in the center. At that time, the secondary outlet 5 (as in the previous example, 4
The downward flow blown downward from the individual slit-shaped outlets serves to reduce the degree of divergence when the air blown out from the primary outlets 4 descends while swirling.

According to the exhaust device according to the present invention, a good tornado flow is formed even if the lower space of the device is left open, that is, without providing an outlet column or the like for imparting a swirling force to the suction flow. However, for this purpose, it is necessary to appropriately set the parameters such as the air volume and the air velocity from the primary outlet 4 and the secondary outlet 5, the exhaust amount, and the suction port diameter. Such specifications can be appropriately determined by experiments according to the usage of the device.

Typical examples of experiments conducted by the present inventors using the apparatus shown in FIG. 3 will be described below.

As shown in FIG. 4, the apparatus has a suction port 3 having a diameter of 80 mm, an inner peripheral surface 14 of the hollow cylinder 26 having an inner diameter of 265 mm, and a hollow cylinder 26 having a height of 55 mm. The nozzles are 30 × 5 mm (length 60 mm), and four nozzles are arranged on the inner peripheral surface 14 in the same direction and in the tangential direction at equal intervals. An annular slit with a width of 1.5 mm is formed behind the inner peripheral surface 14 on the bottom surface of the hollow cylinder 26, and the opening length in the circumferential direction of this slit (secondary outlet) can be freely adjusted. There is.

The opening length of this slit is adjusted as shown in FIG. 5 (the position where the black line portion of the annular slit 5 is closed), and the nozzle wind speed V _1, the suction wind speed V ₃ at the suction port, and the slit wind speed V _3, the nozzle air volume Q _1, suction air quantity Q ₃ of the suction port, the air flow rate Q ₃ of the slit was performed under the conditions shown in Table 1 were observed tornado occurrence using dry ice. The position where the dry ice was placed was 800 mm or 1100 mm below the device. The criteria for determining the tornado were evaluated as follows. The percentage of time that a tornado is generated stably during continuous operation is defined as the occurrence rate (%).
Incidence 50% → 1, 60% → 2, 70% → 3, 80% →
4, 5% or more from 90% or more, and a 5-level evaluation was performed. The results are shown in Table 1.

[0027]

[Table 1]

Further, the slit was fully closed as shown in FIG. 5 (a), and the same experiment was conducted under the conditions of the nozzle air velocity V ₁ = 8 m / s and suction air velocity V ₃ = 3.6 m / s. As a result, it is considered that the air blown out from the nozzle flows divergently downward in the device of the present invention and a part of it is caught in the suction flow, but the tornado stability is lower than 1 of the evaluation standard. ,
It caused a cross flow.

From these test results, it is understood that it is important to form the downward blowout flow by using the secondary blowout port 5 in order to obtain a good tornado flow.

Further, a hollow cylindrical curtain (draft length = 40 mm) having a diameter larger than the imaginary circle in which the secondary outlet is arranged is used as the hollow cylinder 26.
A similar experiment was conducted under the conditions of the pattern (f) in Fig. 5 except that the tornado stability was evaluated as 5, except that the tornado was very good.

[0031]

As described above, according to the exhaust system of the present invention in which the suction inlet and the primary and secondary outlets are integrated in a predetermined relationship, the suction flow is in a tornado state without using a blowing column or the like. Can be exhausted as. Therefore, by simply installing the device of the present invention above a place where dust is generated in a work space such as a clean room, a local space where dust is generated can be formed in an unexhausted exhaust zone, and the dust is prevented from diffusing into the surrounding space. Can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of an exhaust device according to the present invention.

2 is a bottom view of the device of FIG. 1. FIG.

FIG. 3 is a schematic cross-sectional view showing another embodiment of the exhaust device according to the present invention.

FIG. 4 is a schematic cross-sectional view showing the dimensions of the device used in the experiment.

FIG. 5 is a diagram for explaining an opening / closing pattern of a slit of the device used in the experiment.

[Explanation of symbols]

 1 Exhaust device 2 Dust generation source 3 Suction port 4 Primary outlet 5 Secondary outlet 6 Outer hood 7 Inner hood 8 Air supply chamber 9 Exhaust fan 10 Exhaust air passage 11 Exhaust port 12 Filter unit 15 Hollow outer cylinder 18 Supply Air fan 21 Air intake 22 Filter unit 23 Fan motor 27 Fan 28 Exhaust fan 26 Hollow cylinder

Claims (6)

[Claims] 1. An air suction port provided in a hood and an air outlet provided in the same hood, the air outlet being substantially tangential to the air outlet on a virtual circle centered on the axis of the suction flow. Exhaust that consists of a primary outlet that is placed toward the inlet and a secondary outlet that is placed on another virtual circle centered on the axis of the inlet flow with the outlet direction facing in the direction almost opposite to the inlet flow apparatus. 2. The air suction port comprises a cylindrical body that sucks air in the axial direction, and an outer cylinder provided outside the cylindrical body is provided with a primary outlet and a secondary outlet. Exhaust system. 3. The exhaust system according to claim 1, wherein the primary outlets are a plurality of air injection nozzles arranged in the same circumferential surface with the air outlet directions being substantially tangential. 4. The secondary outlet is a plurality of slit-shaped outlets arranged on the same circumferential surface with the air outlet direction facing the direction opposite to the suction flow. Exhaust device according to. 5. The exhaust system according to claim 1, 2, 3 or 4, wherein the hood includes an exhaust fan communicating with the air inlet and an air supply fan communicating with the air outlet. 6. The air suction port and the air outlet are connected to an air blowing system such that the amount of air sucked from the air inlet is larger than the amount of air blown from the air outlet. The exhaust device according to 3, 4, or 5.