US3750839A

US3750839A - Air distribution apparatus

Info

Publication number: US3750839A
Application number: US00194281A
Authority: US
Inventors: J Mcnabney
Original assignee: Trane Co
Current assignee: Trane US Inc
Priority date: 1971-11-01
Filing date: 1971-11-01
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07
Also published as: DE2254169A1; AU463019B2; JPS4853545A; ZA727516B; IT966873B; GB1382910A; AU4827872A; FR2158408A1; FR2158408B1; CA969798A

Abstract

Apparatus for controlling and distributing the flow of air to one or more zones. The apparatus includes a sound-dampening baffle to aid in delivering air with a minimum of perceptible noise.

Description

United States Patent 1191 McNabney {4 1 Aug. 7, 1973 [54] AIR DISTRIBUTION APPARATUS 2,644,389 7/1953 Dauphinee 98/40 R v. 2,820,406 1 1958 Ar 6111161 181/42 [751 McN'bmh La 2,970,531 2/1961 cuiranm 181/50 W1s. 3,059,564 10/1962 Curran 61111. 181/50 3,179,125 4/1965 ODay et al. 98/41 R [73] Ass'gnee' La 3,391,756 7/1968 Larkeldt 61 al. 181/69 [22] Filed: Nov. 1 1971 FOREIGN PATENTS 0R APPLICATIONS 1,118,819 3/1956 France 911/41 R [21] A l. No.: 194,281 1 Primary Examiner-'Richard B. Wilkinson 52 us. c1 181/50, 181/68, 98/41 R 51 Int. (:1. F24f 13/10, Fl6l 55/02 WW-Arthur Andem" ct [58] Field 61 Search 181/42, 50, 46, 56,

l8l/68-70; 98/40 0, 40 D, 40 R, 41 R 1 ABSTRACT Apparatus for controlling and distributing the flow of [56] References Cited air to one or more zones. The apparatus includes a UNITED STATES PATENTS sound-dampening baffle to aid in delivering air with a 511,369 12/1893 Stafford 98/8 mmimum pe'ceptible mise- Ashley R Cl-ims. 8 Dr.wlng Figures 2,890,717 6/1959 Werder..... 118/41 R 3,126,811 3/1964 Kennedy 98/40 D 1,982,747 12/1934 1011111 911/40 R -1 wxzmwwmefimxm 22 27 26 A I} 28 4 |3- j .ef .3 1'

25 32g 29 24 h 33 l7 s k I I a 1 Pmmnm 3.750.839

' km 1 or 4 INVENTOR. H6 2 JOHN c. MCNABNEY ATTORNE PAIENIEU 7 SHEEN w W w w m FIG. 3

a Q m m a m a m a. a m m FIG. 4

INVENTOR.

JOHN C BY i MCN NEY ATTORNEY PATENIEBIUB m I 3.750.839

sim 3 or 4 FIG. 6 E .2 SP SP SP SP SP SP SP SP 2 Z 87 o 0 [u' so I00 200 500 I000 2000 5000 IOOOO FREQUENCY IN CYCLES PER SECOND INVENTOR.

JOHN c. MC NABNEY FIG. 7

PAIWEDM F I G. 8

I N VEN FOR JOHN C. MC BNEY BY ATTORN Y 1 AIR DISTRIBUTION APPARATUS BACKGROUND OF THE INVENTION This invention relates toair distribution systems generally, and'particularly to apparatus forreceivingconditionedair from a source and delivering'the air to one ormore spaces; Forexample, the invention deals with" the-distribution of airto offices within an office building, rooms within-a school-building, and'the'like:

Various apparatus and'methods have'been suggested in the art'to accomplishithe control and'distribution of conditioned air to -aplurality of' spaces" in a building. These'devices seek toprovid'e for efficient control of the air-flow, uniform distribution of air in the spaces;

relatively 1 high velocities while maintaining the quiet operation which isg'particularly desirable.

SUMMARY OF THE INVENTION" The present invention provides an air distribution apparatus'including'anair controlsection andat'least one air diffuser section in fluid'communication such that air fl'owsfrom 'the cont'rol section to one'or more diffuser sections. The 'control section includes a' damper m'echa-- nism for throttling-airflow-through thecontrol section,-

and-atleast one sound attenuating shafil e which is'effectivein dampening annoying .sounds" with the: damper mechanism ineither an open enclosed position, andwherein thebaffle-is effectively at'relatively high airvelocities. The air diffuser section-is adaptedto deliver air in a smooth pattern across the ceiling: of the-space to provide even, draft-free air distribution.

DESCRIPTION or Tn a PREFERRED EMBODIMENTS Certain preferred embodimentsof the invention=will bedescribed with particular reference to'the accompa-- nying drawings, inwhich:

FIG. 1 isaperspective view, partially'brokenaway, of an airdistribution apparatus;

FIGVZ is afrontview'in-elevation of the appa'ratusof 45" FIG. 1;

FIG. 3 is ase'ction view'taken along line 3-3 inFlG. r

FIG. 4 is a section view taken alongline 4-4 of FIG. 3.

FIG. 5 is an enlarged section of one form of sound baffle;

In thedrawings, an air distribution apparatus: is

shownfgenerally at The apparatusiis' made up of controlsection ll an'd'diffiiser section 12. While the" control-sectionll andfdiffuser section 12*are shown to be'contiguous, it-will be understood that such is notnecessary to thepresent" invention; and that diffuser section 12- may be located at some distance. remote from control section 11, the two-sections'in that instance being: connected'by suitable conduit or ductwork.

is provided sound dampening baffle 26. Baffle 26is in Control section 11 and diffuser section l2are generally,rectangular in cross section and are preferably constructed'of metal such as galvanized or enameled steel." Ailayer of' sound absorbing insulation 15 is attached to the interior'walls of both sections.

Diffuser section 12 includes depending flanges 16 at each longitudinal 'end thereof which are useful in attaching the diffuser section to the ceiling supports, such asaT-bar, generally providedfor installations of this;

type.

Control'section includes an air'inlet l3 and air outlets" l4 and 171 Outlet 14 may be usedto connect control section" 11 to an additional diffuser section re-- motely located from control section 11. Outlet 17 places control section 11 into fluid communication with diffuser section 12 whereby a portion of the air" passin'glthrough control section 11 passes through outlet-I7 into diffuser section 12.

Air passing: into diffuser section 12 is distributed throughout the'length of the section, and is then delivered to the space through slots 18. The air delivery slots are formed by depending flanges 19, which are preferably semi-octagonal in contour, with a center strip 20 disposed between flanges 19, the center strip 20 having;

projections 21 extending horizontally in the direction of the'flanges. ,It has been found that the aforementioned configurationisbeneficial in deliveringthe air substantially horizontally along and parallel to the ceilingtin thespace. Accordingly, the air tends to clingto the'ceiling' asit' travels horizontallyv under the influence of Coanda effect, resulting in more uniform distributionof'conditionedair in thespace, whereby annoying drafts are'avoided.

Air entering control section 11 through inlet 13 passes through aV-shaped'perforated screen 22 which has been found to be useful in dampeningthe sound of theincoming-air. Air flow-through control section 11, and-subsequently into and through difiuser section 12, iscontrolled' by damper 25 rotatable about rod-3]. It has been found that air flow can be effectively controlledwhen damper'25 is arranged to turn through an angle of about 60 from the fullyopen to the fully closed'positions. To-accomplish this, damperstops 23 the-general form of 'a perforated plate, and is of'a particular configuration for best results. The baffle 26includesan angled portion 27, a horizontal portion 28,

and a vertical portion 29, aswell as a horizontal projection 34 which is useful in holding the-baffle in position as 'the portion 34 is-capturedby tab 33 on damper stop 24'' I While the specific angle of angled portion 27 may be somewhat varied, it is preferred that this portion be at an angle'which' is about 0 to l5 from the horizontal less than the angle of damper 25 from the horizontal with the damper inthe closed position. For example, if angle A in FIG. 3 is about 60, it would be preferred that angle 8 be'from' about 45 to about 60.

Inasmuch as portion 28 is substantially horizontal, it can be seen that it will be essentially parallel'to damper 25 'when the damper is in the open position. It is also preferred that portion 29'be substantially vertical.

After the air has passed through baffle 26, a portion of the flow will exitthrough outlet 14 to a satellite diffuser, and a portion of the flow will pass through outlet 17, through perforated screen 30, into diffuser section 12, to be delivered to the space in the manner previously described hereinbefore.

As previously mentioned, it is preferred that sound dampening baffle 26 be of the particular configuration described, as that configuration has been found to be most effective in reducing the types of noise emissions most objectionable to most people. However, some beneficial results can be obtained with slightly different shaped baffles as will be more fully described with reference to FIGS. 5, 6 and 7.

An alternative shaped baffle 26a is shown in FIG. 5. Baffle 260 includes angled portion 27a, curved portion 28a, and horizontal projection 34a. Yet another baffle shape is illustrated at 26b of FIG. 6, wherein baffle 26b includes angled portion 27b, vertical portion 29b, and horizontal projection 34b.

FIG. 8 is illustrative of an alternative installation of baffle 26 and damper 25 within the air distribution apparatus 10. In effect, the structure is essentially the same as that illustrated in FIG. 3, for example, except that the damper mechanism and the sound baffle 26 have been inverted. It will be noted that the essential relationships between damper 25 and baffle 26 have been maintained in that the damper lies adjacent horizontal portion 28 when in the open position, and lies in angular disposition along and spaced from slanted portion 27 in the closed position. In this configuration, damper 25 rotates counter-clockwise from the open to the closed position, rather than clockwise as in the configuration shown in FIG. 3, for example. Although the sound dampening characteristics of the structure of FIG. 8 are identical to the sound dampening characteristics of the structure of FIG. 3, the apparatus of FIG. 8 covers an advantage in that outlet 17 can be shifted more toward the center of control section 11, subjacent slanted portion 27. The more central location of outlet 17 provides improved distribution to diffuser section 12.

Various sound measurements were made to gauge the sound dampening effectiveness of various shaped baffles in an air distribution apparatus as illustrated in FIGS. 1-4. Measurements were made with no baffle downstream of damper 25, and with baffles of the configurations of baffle 26 in FIGS. 1-4 and FIG. 8, baffle 26a in FIG. 5, and baffle 26b in FIG. 6. The sound measurements, expressed as Noise Criteria (NC) levels, effectively measured at a distance of 3.3 feet from the noise source in a free field over a reflective surface, are tabulated in Table I.

TABLE I Air Flow Noise Criteria Level (NC) Rate (CFM) No Bafile Baffle Baffle Bafile 2 26a 26b 300 44 34 36 36 50 22 24 33 24 Within the science of acoustics, there have been numerous attempts at methods which might be useful to express sound in terms of its effect on people, however,

no single method has gained universal acceptance. Within the air handling and distribution industry, the NC level has gained wide recognition, and is an accepted standard of the American Society of Heating, Refrigeration and Air Conditioning Engineers.

Noise criteria have'been developed from detailed studies and engineering experience in a number of architectural spaces. Two of the principal factors which are considered are Speech Interference Levels (SlL) and loudness level (L,,). The SlL is a single number derived by taking the arithmetic average of sound pressure levels in the three octave frequency bands 600l,200, l,200-2,400, and 2,400-4,800 cycles per second. L,,, in phons, isobtained by measuring the sound pressure in each of eight octave bands, converting each to loudness in sones, and summing these to obtain a loudness in sones. This can then be converted to loudness in phons, or L,,, by the formula:

L,, 33 log N 40 phons where N is the sum of the loudnesses in sones.

The above mentioned factors, and subjective studies of the annoyance level produced by sounds of particular frequency at particular loudness levels, have been combined to produce the NC curves depicted in FIG. 7. The NC curves are plotted over a graph showing octave band level in decibels on the vertical axis, and sound frequency in cycle per second along the horizontal axis.

As has been indicated, NC levels are, in essence, an objective or empirical expression of a subjective matter. That is, NC levels seek to express the effect on humans of sounds of particular groups of frequencies and loudness levels. In general, the lower the NC level the less noticeable. and less annoying the sound represented; the higher NC levels indicating more noticeable and more annoying sounds. Accordingly, with reference to FIG. 7, it can be seen that for two sounds of equal loudness, the noise criteria level increases with the frequency of the sound. For example, at a level of 40 decibels, a sound at a frequency of I25 cps would have an NC level of about 20 whereas abound of 4,000 cps would have an NC level of about 42. That.

is, the latter sound would be approximately twice as noticeable and annoying as the former in the same environment.

Acceptable NC levels for air delivery equipment for different types of environments have been suggested in the industry as general design guidelines. For example, a concert hall--NC 22, private hospital room--NC 30, school classroom--NC 35, general office space--NC 40, cafeteria--NC 45, and factory--NC 65. Viewing Table I, it can be seen without a sound dampening baffle such as

baffles

26, 26a, and 26b, the NC level at 300 CFM (damper 25 in the open position) was too high for most air conditioning applications. However, with

baffle

26, 26a, or 26b installed, the NC level has been brought within acceptable ranges, although some increases were noted at 50 CFM (danper 25 nearly closed).

Thus, the apparatus of the present invention provides for the control and delivery of conditioned air to a space or plurality of spaces in a manner that insures the comfort of the occupants of the space from both a phsyiological and psychological view point by providing for air delivery which is relatively draft-free and does not create annoying background noise.

While in the foregoing specification, the present invention has been described in considerable detail, it will be understood that such detail is for the purpose of illustration and is not intended to limit the scope of the invention, which is defined in the appended claims.

I claim:

1. An air distribution apparatus for providing conditioned air to at least one space, said apparatus comprismg:

an air receiving portion having an air inlet and a plurality of air outlets;

damper means disposed in said air receiving portion to vary the volume of air passing through said portion;

a first perforated baffle disposed between said air inlet and said damper means;

a second perforated baffle disposed between said damper means and said air outlets;

and a plurality of air diffuser portions each in fluid communication with one of said air outlets, said diffuser portions including slot means for discharg-v ing air therefrom in a flow generally along the ceiling of said space.

2. The apparatus of claim 1 wherein said air receiving portion includes top and bottom walls, and wherein said second baffle slants downwardly and rearwardly from said top wall, thereafter extends substantially horizontally and rearwardly, and thereafter extends substantially vertically downwardly into contact with said bottom wall.

3. The apparatus of claim 1 wherein said second baffle includes a slanted portion, said slanted portion disposed at an angle measured from the horizontal which is from about 0 to about 20 less than the angle at which said damper means is disposed from the horizontal when said damper means is in the closed position.

4. The apparatus of claim 3 wherein said angle of said slanted portion is about less than said angle of said damper means in the closed position.

5. The apparatus of claim 1 wherein said air receiving portion includes top and bottom walls; and wherein said second baffle slants downwardly and rearwardly from said top wall and thereafter smoothly curves downwardly and forwardly into contact with said bottom wall.

6. The apparatus of claim I wherein said air receiving portion includes top and bottom walls, and wherein said second baffle slants downwardly and rearwardly from said top wall and thereafter extends substantially vertically downwardly into contact with said bottom wall.

7. The apparatus of claim 1 wherein said air receiving portion includes top and bottom walls, and wherein said second baffle extends substantially vertically downwardly from said top wall to a point about midway between said top and bottom walls, thereafter extends substantially horizontally and forwardly toward said damper means, and thereafter slants downwardly and forwardly into contact with said bottom wall.

8. The apparatus of claim 1 wherein said first perforated baffle comprises a substantially V-shaped perforated plate between said damper means and said air inlet, said first baffle extending substantially across the area of said air inlet.

9. The apparatus of claim 1 wherein said slot means includes a semi-octagonal side and an L-shaped side facing said semi-octagonal side, whereby air passing through said slot means flows along the ceiling of said space.

10. The apparatus of claim 1 wherein said slot means includes two spaced apart semi-octagonal sides and an inverted U-shaped member disposed between said semi-octagonal sides, said U-shaped member having horizontal projections at each tip thereof facing toward a respective semi-octagonal side, whereby air passing through said slot flows along the ceiling of said space in two oppositely directed streams.

11. The apparatus of claim 1 wherein each of said diffuser portions includes a third perforated baffle disposed in the fluid passageways between said air outlets and each of said diffuser portions.

12. The apparatus of claim 1, said second perforated baffle including a slanted portion, a horizontal portion, and a vertical portion, and said damper means including a rotatable damper blade, wherein said slanted portion is disposed at an angle measured from the horizontal which is about 0 to 20 less than the angle at which said damper blade is disposed from the horizontal when said damper blade is in the closed position.

13. The apparatus of claim 12 wherein said angle of said slanted portion is about l5 less than said angle of said damper blade in the closed position.

l i i l l

Claims

1. An air distribution apparatus for providing conditioned air to at least one space, said apparatus comprising: an air receiving portion having an air inlet and a plurality of air outlets; damper means disposed in said air receiving portion to vary the volume of air passing through said portion; a first perforated baffle disposed between said air inlet and said damper means; a second perforated baffle disposed between said damper means and said air outlets; and a plurality of air diffuser portions each in fluid communication with one of said air outlets, said diffuser portions including slot means for discharging air therefrom in a flow generally along the ceiling of said space.

3. The apparatus of claim 1 wherein said second baffle includes a slanted portion, said slanted portion disposed at an angle measured from the horizontal which is from about 0* to about 20* less than the angle at which said damper means is disposed from the horizontal when said damper means is in the closed position.

4. The apparatus of claim 3 wHerein said angle of said slanted portion is about 15* less than said angle of said damper means in the closed position.

6. The apparatus of claim 1 wherein said air receiving portion includes top and bottom walls, and wherein said second baffle slants downwardly and rearwardly from said top wall and thereafter extends substantially vertically downwardly into contact with said bottom wall.

12. The apparatus of claim 1, said second perforated baffle including a slanted portion, a horizontal portion, and a vertical portion, and said damper means including a rotatable damper blade, wherein said slanted portion is disposed at an angle measured from the horizontal which is about 0* to 20* less than the angle at which said damper blade is disposed from the horizontal when said damper blade is in the closed position.

13. The apparatus of claim 12 wherein said angle of said slanted portion is about 15* less than said angle of said damper blade in the closed position.