Apparatus for providing an air curtain

An air flow apparatus for providing a continuous curtain of air or other fluid includes a body member defining a first elongate plenum chamber, at least one inlet opening through which the first plenum chamber receives compressed air and an outlet opening for discharging air from the body member. The apparatus may also include a second plenum chamber (which communicates with the outlet opening) and at least one passageway connecting the first and second plenum chambers. The body member discharges the air without deflecting it towards one of its outer surfaces.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to an air flow apparatus and, more 
specifically to an air flow apparatus which provides a thin and continuous 
layer of jetting fluid. 
2. Description of the Prior Art 
The prior art includes a variety of air flow devices that produce air 
curtains and columns. For examples, Iglis U.S. Pat. No. 4,046,492 which 
issued Sep. 6, 1977, discloses an air flow amplifier with an annular 
nozzle for producing a column of air. Broerman U.S. Pat. No. 4,930,705, 
which issued Jun. 5, 1990, discloses an air flow apparatus with a linear 
nozzle that provides a thin layer or curtain of jetting air. 
The devices identified above typically include a protuberance at the outlet 
for redirecting the discharging air onto an angled surface of the device. 
This direction change of the air results in a reduction in its velocity 
and a loss of kinetic energy. 
Other prior devices do not employ means for deflecting the air as it 
discharges. One such device, known as a coanda-type air flow amplifier, 
discharges air out of a slit and directs it along a curved surface and 
eventually along a plane disposed generally perpendicularly to the slit 
(see FIG. 1). The air in this application also loses velocity after 
discharging from the device and accordingly loses kinetic energy. 
The apparatus of the present invention amplifies the velocity of fluid 
through its body and discharges the fluid through a linear nozzle or slit 
without redirecting the flow after discharge. It isolates the turbulence 
of the fluid it receives and distributes and regulates air flow evenly to 
the linear outlet. This design allows introduction of fluid into the 
device at a variety of positions without requiring an increased length. It 
facilitates the combination of two or more of the devices in end to end 
relation. 
The apparatus of the present invention produces greater thrust efficiencies 
and air velocities than those of prior devices. It provides a construction 
which minimizes the expense of manufacture and assembly and gives precise, 
uniform and reliable performance. It comprises a small number of 
components which provide a continuous curtain of fluid. 
SUMMARY OF THE INVENTION 
In accordance with one embodiment of this invention, an air flow apparatus 
which provides a curtain of jetting fluid (e.g., air) includes an elongate 
body member made of metal or any other material of high strength and 
rigidity. This member defines a first, elongate plenum chamber for 
receiving the fluid and at least one inlet opening through which the first 
plenum chamber receives the fluid from a source. 
The body member may also define a second, elongate plenum chamber which 
receives fluid from the first plenum chamber through at least one 
passageway. The first plenum chamber suppresses any turbulence in the 
fluid which the apparatus receives; and it distributes and regulates the 
flow of the fluid to the second plenum chamber. The second plenum chamber 
further suppresses turbulence in the fluid before the fluid discharges 
from the device. 
In addition, the body member defines an elongate outlet opening or nozzle 
through which the fluid discharges after flowing through the second plenum 
chamber. This outlet opening restricts the flow of fluid, increasing its 
velocity as it discharges. After it discharges from the body member, the 
fluid continues to travel in the direction it flowed immediately before 
discharging, i.e., the body member does not redirect the flow of the fluid 
after it discharges from the slit or linear nozzle.

While the applicant will describe the invention in connection with one 
embodiment, and a number of modifications, one should understand that the 
invention is not limited to this embodiment. Furthermore, one should 
understand that the drawings are not necessarily to scale. In certain 
instances, the applicant may have omitted details which are not necessary 
for an understanding of the present invention. 
DETAILED DESCRIPTION OF THE DRAWINGS AND AN EMBODIMENT 
Turning now to the drawings, FIGS. 2 and 3 show an embodiment of an air 
flow apparatus generally at 10. The apparatus includes a main body member 
11 with a base member 12 and a cap member 13. The members 12 and 13 are 
elongate and made of metal or any other suitable material of high strength 
and rigidity. Bolts 14 (or any other suitable securing devices) secure the 
cap member 13 to the base member 12; and a shim 15, disposed between the 
members 12 and 13, determines the size of the thickness of a linear slit 
16 (see discussion below) defined by the members 12 and 13. The shim 15 is 
a strip of metal foil or any other suitable material. 
The base member 12 has an elongate opening 17 formed through it. This 
opening 17 has a circular configuration; and it extends the length of the 
base member 12. The opening 17 is the first plenum of the apparatus 10. A 
pair of metal plate and gasket assemblies (not shown) secured at opposite 
ends of the main body member 11 with bolts close the ends of the plenum 
chamber 17 as well as the ends of a second plenum chamber described below. 
The base member 12 has an inlet 18 through which the plenum chamber 17 
receives compressed fluid, e.g., air. This inlet opening 18 is threaded to 
receive a fitting or any other suitable connector which provides fluid 
communication with a source of compressed fluid (not shown). 
Alternatively, the base member 12 may include two or more inlet openings 
for the first plenum chamber 17. 
The inlet opening 18 extends perpendicularly to the longitudinal axis of 
the first plenum chamber 17. Thus, when compressed air flows into the 
first plenum chamber 17, its direction of flow changes. This change in 
direction of flow of the fluid creates turbulence at the inlet opening. In 
addition, the sudden expansion of the fluid when it enters into the first 
plenum chamber 17 also creates turbulence. The first plenum chamber 17 
isolates this turbulence before the fluid moves further into the apparatus 
10. 
The base member 12 also has a trough 19 formed along the end adjacent the 
cap member 13. The trough 19 and a trough 20 formed in cap member 13 
combine to define a second plenum chamber 21 disposed between the base 
member 12 and the cap member 13. The second plenum chamber 21 communicates 
with the first plenum chamber 17 through passageways 22. 
The passageways 22 include a plurality of round bores, with one spaced a 
predetermined distance apart from the other. In the embodiment shown, the 
passageways 22 lie in equal distance from each other. They distribute the 
fluid evenly in the second plenum chamber 21. Alternatively, the 
passageways may lie at unequal spacings. 
One side of the second plenum chamber 21 has curved surfaces 21a and 21b 
which merge into flat surfaces 16a and 16b. The curved surfaces 20a and 
20b help reduce turbulence in the second plenum 20 by gradually reducing 
the cross-section through which the fluid must travel before it enters the 
gap 15. The flat surfaces 16a and 16b define the linear nozzle or slit 16 
and determine the direction in which the fluid will discharge from the 
apparatus 10. In the embodiment shown the direction of discharge is 
perpendicular to the face 11a of the main body member 11. 
The elongate slit or passage 16 has a substantially uniform width 
throughout its length. It defines a nozzle which restricts the flow of 
fluid. Thus, the fluid discharges from this nozzle at a velocity 
substantially greater than the velocity at which it enters the apparatus 
10. 
The main body member 11 does not include any structure which deflects the 
discharging fluid. In the embodiment shown, the slit walls 16a and 16b lie 
perpendicularly to the face 11a of the main body member 11. Thus, the 
fluid discharges in a direction which lies perpendicularly to this face. 
Alternatively the surfaces 16a and 16b may lie parallel to each other but 
at an angle to the face 11a. In this case, the fluid would discharge at an 
angle to the face 11a. 
In operation, compressed fluid enters the main body member 11 through the 
inlet 18 and into the first plenum 17. There, the turbulence in the 
incoming fluid dissipates as the fluid fills the first plenum chamber 17. 
The fluid then flows into passageways 22 and into the second plenum 
chamber 21. The fluid then discharges from the apparatus 10 through the 
nozzle 16 and outwardly of the apparatus. 
Thus, the applicant has provided an air flow apparatus capable of providing 
a continuous layer of jetting fluid. While the applicant has shown one 
embodiment of the invention, one will understand, of course, that the 
invention is not limited to this embodiment since those skilled in the art 
to which the invention pertains may make modifications and other 
embodiments of the principles of the invention, particularly upon 
considering the foregoing teachings. 
For example, as shown in FIGS. 4-6, a modification includes placing a flow 
rate adjustment tube 23 into the first plenum chamber (see FIG. 4). This 
tube is made of metal or any other suitable material. It includes an 
opening 24 which cooperates with the inlet 18 of the main body member 11 
and outlet openings 25 which cooperate with the passageways 22. The tube 
has a predetermined outside diameter which allows the tube to fit snugly 
inside the first plenum chamber 17 while still allowing the tube to 
rotate. 
In addition, the tube 23 has a length slightly greater than the length of 
the main body member 11 so that the end plates on the compression gaskets 
at opposite ends of the apparatus 10 may hold the tube in place and 
prevent unintended rotation inside the first plenum chamber 17 after 
placement in a desired position. By rotating and adjusting the tube 23 in 
relation to the base member 12, the open area between the holes 25 in the 
tube 23 and the passageways 22 in the base member 12 changes, resulting in 
a change in the flow rate of fluid. 
One may adjust the flow between the first and second plenums by removing an 
end plate and gasket from the main body member 11 and adjusting the tube 
23. Alternatively, a shaft (not shown) connected to one end of the tube 23 
for rotating the tube may extend through a suitable opening in an end 
plate of the apparatus 10 and allow adjustment of the tube 23 without 
removal of the end plate. 
Another modification of the apparatus 10 (shown in FIGS. 7-10) includes a 
baffle 26 which is an elongate piece of corrugated metal or any other 
material of high strength and rigidity. This baffle 26 extends along the 
entire length of a passageway 27 between the first and second plenum 
chambers. Edge portions 26a and 26b extend into grooves 28 and 29 in the 
base member 12. The groove 28 has a portion 28a which cooperates with the 
corrugations in the baffle 26 to channel the fluid from the first plenum 
chamber 17 to the second plenum chamber 21. 
One may insert the baffle 26 in place through either one side of the main 
body member 11 or the other and secure the baffle 26 in place by securing 
the end plates and compression gaskets to the main body member 11. The 
baffle 26 has a length slightly greater than the length of the main body 
member so that the end plates and compression gaskets at opposite ends of 
the member 11 may securely hold the baffle in place. Alternatively, the 
baffle may have a length equal to or less than the length of the main body 
member. 
Yet another modification (See FIGS. 11-13) includes an optional inlet 
position 30 at the side of the apparatus 10. In this modification, the end 
plate 31 merely covers a portion of the end surface of the apparatus 10. 
As shown in FIG. 13 a supply tube 32 extends into the first plenum 17 from 
a side of the main body member 12. 
Finally, the apparatus 10 may include only one plenum chamber 17, as shown 
in FIG. 14. In this modification, the passageway means 22 connects the 
chamber 17 with a slit 33, through which the apparatus discharges fluid. 
The applicant, therefore, by the appended claims, intends to cover any 
modifications and other embodiments that incorporate those features which 
constitute the essential features of this invention.