US 3452667 A
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July i, 1969 M, H, @LEMAN Em] 3,452,667
AIR DISTRIBUTION TERMINAL Filed June 29, 196'? INVENTORS.v
MILTON H. COLEMAN.
DARWIN G. TRAVER. BY CARL C. HERB.
U.S. Cl. 98--41 3 Claims ABSTRACT F THE DISCLOSURE A room terminal Ifor use in an air conditioning system to discharge air into the space being conditioned employing a sound attenuating chamber having a perforate section for entrance lof sound waves therein to minimize noise produced by air ilow through the unit.
Background of the invention This invention relates to air conditioning terminals and more particularly to air conditioning terminals for discharging conditioned air from a central source into the area to be conditioned. In many air conditioning applications, it is desirable to provide air to the room terminals from a central location to either supply the entire room heating or cooling requirements or to act as primary air for inducing room air through the terminal into contact with heat exchange means therein to meet room heating and cooling requirements. `In either type of installation, the room terminals are normally provided with a damper for balancing each room terminal so as to apportion the required amount of air through the terminal -from the central source to meet the requirements of the area served thereby. One of the problems encountered with terminal-s of this type is that the dampers generate high frequency sound Ias the air passes therethrough which is objectionable in the area being conditioned.
Summary of the invention Brief description of the drawing FIGURE 1 is a perspective view of an al1-air type air conditioning terminal; and
FIGURE 2 is a sectional end View of the terminal of FIGURE 1.
Description of the preferred embodiment Referring to the drawing, there is illustrated a room terminal 2 having a front panel 3, a yrear panel 5, a bottom panel 7, a top panel 9 and end panels 10 so as to provide a box-like enclosure for passage of air therethrough as evidenced by the arrows having non-wavy shafts. A grille 1'1 is disposed in top panel 9 for discharge of air into the area being conditioned. A first plenum 13 defined by rear panel '5, bottom panel 7, Afront panel 3, end panels and a sliding plate damper 15 is supplied with conditioned air from a central source (not shown) through opening 17 formed in one of the termin-al end panels 10. A second plenum 19, defined by Ifront panel 3, rear panel 5, end panels 10 and sliding plate damper overlies first plenum 13 and communicates with air discharge stack 21. Stack 21 is defined by generally L- 3,452,667 Patented July 1, 1969 shaped walls 23 and end panels 10, the bottom legs of the walls 23 defining a portion of the top of plenum 19. Suitable sound attenuating material 25, such las glass fiber blanket, is provided for lining the sides, ends, and bottom of plenum 13, the sides, ends, and top sections of plenum 1'9 and the 'walls and ends of discharge stack 21. A sound attenuating baille 27 having imperforate walls 29 and a perforate base panel 31 is -disposed in plenum 19. Sound attenuating material 25 is also utilized to completely cover the exterior of sound baille 27. The baille 27 is suitably sized and located to minimize the sound level of the terminal.
Since a major source of objectionable noise in the terminal results from high frequency sound waves, shown in the drawing by arrows having wavy shafts, produced by the throttling of air through the damper, the baille 27 must be located so as to block thi-s sound. Care must be taken in the placement of the baille however, so as to avoid the generation of further sound waves by the impingement of air on the baffle. The base of baille 27 must therefore be located in relation to the velocity of air discharged lfrom the damper so that the velocity of the air impinging on the baille is insuilicient to create additional unwanted noise. Base 31 of the baille is sized in -relation to legs 24 of L-shaped walls 23 so as to provide line-of-sight blocking of the high frequency sound waves produced by damper 15.
The perforations in base plate 31 provide a path for sound waves into the center of the baille. The sound waves that are deflected therein so as to pass outwardly through the perforations in the plate must therefore travel through the sound attenuating material 25 twice, which results in a double dissipation of the acoustic energy. To further aid in reducing the noise level of the terminal, the baille is provided with as great a depth in the direction of air ilow as possible in relation to the sound wave length. To provide a suiliciently large passage Ifor air between the baille 27 and walls 23 while providing the greatest depth for sound wave penetration into the baille, the triangular shape illustrated in the drawing is preferred. However, any configuration which .provides a sufficient-ly large air passage between the baille and the unit walls while providing sufficient baille depth for penetration of sound therein is deemed to be within the scope of our invention.
While we have described a preferred embodiment of our invention, it is to be understood the invention is not limited thereto but may be otherwise embodied 4within the scope of the following claims.
1. A room terminal for use in an -air conditioning system comprising:
means defining a first enclosure adapted for connection to a course of conditioned air;
means Idefining a second enclosure in communication with said first enclosure;
a damper disposed between the first and second enclosures for regulating air flow from the first to the second enclosure;
3 terial into the interior of said chamber for di'ssipatio 'of the sound energy waves therein.
2. A room terminal according to claim 1 wherein the base section of said attenuating means is comprised of rat per-forate plate disposed parallel to said damper, the top section of said sound attenuating means comprising an inverted V-shaped imperforate plate so as to Iform a triangular shaped member.
'3. A room terminal according to claim 2 wherein said air discharge means includes shoulder sections above said sound attenuating means to block line-of-.sight sound waves passing alongside said sound attenuating means from the damper, and, sound attenuating mate-rial disposed on said shoulder sections for dissipating sound energy therein.
References Cited UNITED STATES PATENTS 3,074,339 1/1963 Pennat-i 98-40 3,145,926 8/1964 ODay y 98-38 X 3,186,327 6/ 1965 vGiurlando et ial. 98-38 3,250,203 5/1966 Spradling et al. 98-38 3,330,379 7/ 1967 Cook 181-50 FOREIGN PATENTS 610,221 1 0/1960 Italy. 1,018,084 1/ 1966 Great Britain.
U.S. Cl. X.R.
'(15530 UNTTED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,162,667 Dated Julv l. 1%@
Invencor(s) MILTON H' COLEMAN, ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 2, line 5'5, for "course" read --souTce-.
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