US3338265A

US3338265A - Regulator for constant volumetric rate of gas flow

Info

Publication number: US3338265A
Application number: US394967A
Authority: US
Inventors: Walter W Kennedy
Original assignee: Barber Colman Co
Current assignee: Barber Colman Co
Priority date: 1964-09-08
Filing date: 1964-09-08
Publication date: 1967-08-29
Anticipated expiration: 1984-08-29

Description

29, 1967 w. w. KENNEDY REGULATOR FOR CONSTANT VOLUMETRIC RATE OF GAS FLOW 2 Sheets-Sheet l Filed Sept.

L/Afi 9% A TTORNEYS Aug. 29, 1967 w. w. KENNEDY REGULATOR-FOR CONSTANT VOLUMETRIC RATE! OF GAS FLOW 2 Sheets-Sheet 2 Filed Sept. 8, 1964 INVENTOR.

h a/ar Kennedy BY United States Patent Ofi ice 3,338,265 Patented Aug. 29, 1967 REGULATOR FOR CONSTANT VOLUMETRIC RATE OF GAS FLOW Walter W. Kennedy, Rockford, Ill., assignor to Barber- Colman Company, Rockford, 111., a corporation of Illinois Filed Sept. 8, 1964, Ser. No. 394,967 Claims. (Cl. 137-517) This invention relates to a regulator of the type disclosed in Patent No. 3,049,146 for. automatically controlling the flow of gas through a duct by controlling the rolling of a flexible curtain onto and off from a perforated backing in response to changes in the static pressure differential acting on an unsupported area of the curtain and varying with changes in the supply pressure.

The primary object is to provide a regulator of the above character which is much simpler and less expensive in construction than the patented regulator.

A more detailed object is to control the rolling and unrolling of the curtain by a member supporting the upstream end of the curtain and movable along a fixed path extending transversely of the duct.

Another object is to provide a flow regulator of the above character in which said member is carried by the free' end of a swingable arm projecting downstream.

A further object is to utilize a simple contractile spring to provide the variable force for opposing the static pressure differential acting on the unsupported area of the curtain.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which FIGURE 1 is a fragmentary longitudinal section through a duct equipped with the improved flow regulator, the section being taken along the line 11 of FIGS. 4 and 5 and showing the full open position.

FIG. 2 is a similar sectional view showing the flow controlling curtain in closed position.

FIG. 3 is an enlarged view of a portion of FIG. 2.

FIG. 4 is a fragmentary plan section taken along the line 33 of FIG. 1.

FIG. 5 is a fragmentary perspective view with parts of one duct wall and the curtain broken away.

As in the patented construction, the improved regulator is adapted to vary the flow passage through an intermediate cross-section of a rectangular duct comprising parallel top and bottom walls and 11 and parallel side walls 12 and supplied with air under pressure through one or more inlets 13. Said flow passage is defined at any given time by the uncovered area 14 of a screen or plate 15 extending transversely across the duct and forming on its upstream face a backing for an imperforate and flexible curtain 16 which is rolled onto and oif from the perforated area of the plate to correspondingly vary the area of the flow passage. The perforations in the plate are sized to provide a large free air area extending across substantially the full width and major depth of the duct between the inturned flanges 17 of plate 18 secured to the duct walls and to the margins of the screen.

Preferably, the curtain 16 is a thin and flexible sheet of coated fabric rectangular in shape and extending substantially across the full width of the duct. One end of the curtain is secured as by a clamping bar 20 against the upstream face of the upper flange 17 and along a transverse line paralleling the upper and lower duct walls. To utilize the pressure of the oncoming air most effectually in sealing the side edges of the curtain against the upright flanges 17, the backing between the line of attachment of the curtain and the lower wall of the duct is preferably inclined to provide a slightly obtuse angle between the screen and the bottom duct wall on the upstream side of the screen.

In accordance with the present invention, the free edge 21 of the curtain is secured to a member 22 which is movable in a path 23 extending transversely of the duct and disposed relatively close .to the screen near the bottom wall of the duct at its lower end. The path extends upwardly and away from the screen to a point about midway between the top and bottom walls of the duct where the free edge of the curtain will be spaced a substantial distance from the screen as shown in FIG. 1, this being the position of maximum uncovering of the screen.

Herein, the path 23 is arcuate and defined by the free end of an elongated arm or yoke projecting downstream from a fulcrum axis 25 spaced upstream a substantial distance from the screen and near the bottom wall 11 so that the arm is disposed substantially horizontally when the curtain is in the position of maximum coverage of the screen as shown in FIG. 2. The yoke arm is formed by two elongated bars 24 lying adjacent the side walls 12 and pivoted at their upstream ends on pins 27 which define the fulcrum 25. At their downstream ends, the arms are spanned and rigidly joined by a cross-member 22 around which the free end of the curtain, as indicated at 29 (FIG. 3), is looped and suitably secured as by adhesive between the overlapping areas.

A simple contractile spring 30 is connected at one end to the center of a bar 31 and disposed intermediate the ends of the side arms 24. The opposite end of the spring is fixed to the center of a bar 32 extending across the top wall of the duct, the spring being tensioned to peel the curtain off from the screen 15 and to exert its greatest force when the member 22 is in the position of minimum opening (FIG. 2) determined by a stop 33. The latter is located in a position which, as shown in FIGS. 2 and 3, prevent complete covering of the outlet area 14 for a reason to presently appear.

By spacing the path 23 of swinging of the cross-bar 22 upstream from the screen 15, it will be apparent that the free and unsupported end portion of the curtain, in the different vertical positions of the cross-bar, will project upstream and away from the screen as shown in FIGS. 1 and 2 and cooperates with the side walls 12 and the top and bottom walls 11 to define upper and lower chambers 35 and 36. The upper chamber is closed at its downstream end by the upper flange 17 and the end portion of the curtain lying against and covering the screen 15. Thus, the pressure in this chamber is always equal to the static pressure of the air delivered into the duct through the inlet 13.

The downstream end of the lower chamber 36 is defined by the uncovered screen openings which, being of lesser area than the upstream cross-section of the duct, constitute an orifice or restriction which varies in area according to the extent of unrolling of the curtain from the screen. The increase in the velocity of the flow through this orifice as compared to the velocity at the duct inlet results in a lower static pressure in the lower chamber 36. A pressure differential is thus exerted on the unsupported or dividing portion of the curtain in a direction to reduce the size of the uncovered area of the screen. This differential is balanced against the force of the spring 30 so that, as in the patented construction, the extent of peeling of the curtain 16 away from the screen 15 will vary inversely with the inlet air pressure and the size of the restricted flow area 14 will be adjusted automatically with changes in this pressure to maintain a substantially constant rate of flow in spite of variations in the supply pressure.

To make the pressure in the upper chamber 35 accurately follow the changes in the inlet pressure, an imperforate bafile plate 38 spaced upstream from the curtain is positioned to intercept the incoming air and divert a portion thereof upwardly toward the chamber 35. This plate is substantially flat, is inclined upwardly toward the chamber 35 and occupies an area at the center of the duct which is a small fraction of the cross-section of the duct. It is secured to a cross-bar 40 extending across the duct with opposite ends fixed to the duct side walls 12.

By supporting the free edge of the curtain on the pivoted arm 24 whose motion is controlled by a contractile spring, an exceedingly simple and inexpensive construction has been provided to compensate automatically for changes in the pressure of the suppliedair and maintain at all times a constant rate of flow through the duct.

I claim as my invention.

1. The combination of, a duct of rectangular crosssection adapted for the forced flow of air therethrough in one direction, a rigid plate extending across the full crosssection of the duct and having a perforated area adjacent one wall of the duct, means defining a pivot extending transversely of said duct and spaced upstream from said plate, an elongated arm fulcrumed on said pivot and projecting downstream therefrom with its free end disposed opposite but short of said perforated area, an elongated flexible and rectangular curtain secured at one end to said free arm end and at the other end to said plate for flexing and covering areas of the perforations which increase and decrease as the arm swings across the perforated area and toward and away from one wall of the duct, said curtain cooperating with the walls of said duct on the opposite side thereof to define a chamber opening upstream but closed at its downstream end to create a drop between the static pressures in such chamber and the upstream side of said perforated area, and yieldable means continuously urging said arm in a'direction to unroll said curtain and expose a greater area of the perforations as said pressure drop decreases with a decrease in the pressure of the air supplied to the inlet end of said duct.

2. A flow regulator as defined in claim 1 in which the path of movement of said free arm end converges toward said perforated plate area whereby the effective area of said curtain defining the inner wall of said chamber decreases progressively during movement of the member to close said flow passage.

3. A flow regulator as defined in claim 1 in which said yieldable means is a contractile spring stretched between said arm and the outer wall of said pressure chamber.

4. An air flow regulator as defined in claim 1 in which said swingable arm comprises a U-shaped yoke substantially corresponding in width to said duct.

5. An air flow regulator as defined in claim 1 including a bafile smaller in cross-section than said duct and positioned to intercept a portion of the air stream delivered through said duct inlet and deflect the same laterally of the duct and toward the inlet of said pressure chamber.

References Cited UNITED STATES PATENTS 3,049,146 8/1962 Hayes 137-517 WILLIAM F. ODEA, Primary Examiner. H. M. COHN, Assistant Examiner.

Claims

1. THE COMBINATION OF, A DUCT OF RECTANGULAR CROSSSECTION ADAPTED FOR THE FORCED FLOW OF AIR THERETHROUGH IN ONE DIRECTION, A RIGID PLATE EXTENDING ACROSS THE FULL CROSSSECTION OF THE DUCT AND HAVING A PERFORATED AREA ADJACENT ONE WALL OF THE DUCT, MEANS DEFINING A PIVOT EXTENDING TRANSVERSELY OF SAID DUCT AND SPACED UPSTREAM FROM SAID PLATE, AN ELONGATED ARM FULCRUMED ON SAID PIVOT AND PROJECTING DOWNSTREAM THEREFROM WITH ITS FREE END DISPOSED OPPOSITE BUT SHORT OF SAID PERFORATED AREA, AN ELONGATED FLEXIBLE AND RECTANGULAR CURTAIN SECURED AT ONE END TO SAID FREE ARM END AND AT THE OTHER END TO SAID PLATE FOR FLEXING AND COVERING AREAS OF THE PERFORATIONS WHICH INCREASE AND DECREASE AS THE ARM SWINGS ACROSS THE PERFORATED AREA AND TOWARD AND AWAY FROM ONE WALL OF THE