US2284161A - Air conditioning apparatus - Google Patents

Description

J. M ELGlN May 26, 1942.

AIR CONDITIONING APPARATUS Filed June 9, 1939 "WW A AAQAA N W M QM F M M AM m 6 9 m N 6 m 9 m 2 m F n- \W m J? fl Q a F m JOHN Mc ELG/N 4 TTOfi/VEYS Patented May 26, 1942 g Am CONDITIONING APPARATUS J ohn -McElgin, Philadelphia, Pa., assignor to John J.. Nesbitt,. Inc.,, Philadelphia, Pa... a corporation of Pennsylvania Applicationdu nefi, 1939, s i Nogzvaziv' '8 Claims. (01. ass-38.)

field is the influence of outside wind pressure on the unit capacityand performance. The relatively lowfan tip speed employed. for quiet operationof unit-ventilating. equipments makes-the equipment quite sensitive to. changes in outside Wind. conditions. It is. quite easy for the windv to reach a velocity. or. pressure under which the quantity of air entering theoutdoorair intake exceeds the fan capacity. Where all of. the air is introduced from. outdoors duringthe ventilate ing cycle, this. effect. isof ,importanceonly in that it increases the predetermined ventilation rate.

However, if the unit is designed, to. introduce a minimum percentage of outdoor air for. ventilation, there mayoccur not only anv increasein ventilation rate, but a condition that is commonly described as blow through. Underthis condition, excess outdoor air, unable. to. pass.

through the fans, may enterthe room through the recirculating grille. It. canbereadily ap preciated that .such leakage is uncomfortable for the occupants of=the room.

In order to prevent this .blow through con dition, the prior art has devised several schemes, none of which have been. altogether satisfactory. Perhaps. the best known method inthis respect is thatin which. a. back draft damper. is employed inthe recirculating opening of the unit ventilator. The damperis operated, to. prevent entry of air into .the casing through therecirculating grille by automatically closing when the fan suction-reachesa minimum level. In order more accuratelyto gauge my invention described hereinafter, itis desired .to. point out some. of the diificulties. brought aboutby wind in unit wind pressure isexerted on the interior of the cabinet or. .unit as. well. as on the ins ide of the back draft dampers. It is. impossible to con'- struct such self-closing. dampers absolutely tight at the point of contact and, therefore, some.leakagewill take place. The.degree of leakage is not important; since even a small leakage isjust as troublesome for the adjacent occupantsaaa larger qua'ntity, particularly in I cold weather.

The air delivery of. the unit. with back.draf t dampersis at the mercy of outside winds. The introduction of an excessive amount of outdoor air into the room is .very liable to.,cause drafts,

even where a means is providedto limitjthej low: est discharge temperature. .An airstream control cannot react quickly .enough to sense. a sud.-.

den gust; of wind and, hence. the. dischar t mperature will be depressed.

Finally, in order .to achieve. gravity. heating. effect during shut-down periods of the fan, the.

backdraft .darnpersmust be connected tojthe. outdoor damper .insuch a mannenthatthe backv 3 draft dampers. will, open, when the. outdoor, damper is closed, This introduces. a complex spring linkage which mayreadily destroy. the.- sensitivitvof the dampers and the protection.

they offer against blow through.

Theprimaryobject of thepresent invention is to .eliminatethe diflicultiesreferred to in .the.

immediatel preceding, paragraphs and, in particular, to. provide anarrangement bywhich the.

wind is .preventedfrom.entering, the outdoor air inlet and .thusexcluded entirely from the casing.

The general object is to provideanimprovedunit ventilator which-prevents an excess of .outdoor air pressure from afiecting the unit.

Other. objects are to .eliminatethe condition known in theventilatoriartas blow through when .thegusts, ,oi wind-aresevere; to providea;

unit .in'which .the size of the .outdoorlairinlet is varied in accordance. with thepressure of .the

ventilators and particularly as .these difficulties 7 are applied to thosesysterns inwhich backdraft,

dampers are employed.

In the first place, to have any degree of ,effectiveness, back draft dampers. must be. constructed so sensitive to variations in .fan suction pressure that they will. completely close, Well be.- fore the full fan. capacity. from outdoors is reached The result is that, even. on moderately outdoor. air; to. providea device .of this character which is controlledhdirectly by .the'pre'ssuraofu the wind. andwhich responds instantaneously to.

pressurefchangesand finally to..provide, as. a.

combination. aunitventilator. of .the variable outdoor air inlet type and a simple, inexpensive adjustment member for varying. the. size ofthe V inlet. which operates much faster .forhigh wind pressures than for low pressures.

These. objects are .attained in brief, by providing one or more baffles mounted in.the.outdoor.

These baffles have such a shapewand'are so.

' spondto the mixed air being discharged bythe Figure l is a sectional view taken across the o improved unit ventilator which isprovicled with one exemplary form of baflie.

Figure 2 shows a fragmentary cross sectional modified ba'file ar view of a unit employing a. rangement, while 7 Figures 3, 4 and 5 show still other m'odifica tions. r

Referring more particularly to Figure 1, numeral l designates the casing of anair-conditioning unit, the lower portions of which'termiblowers 6 will respond to any change in temperature of the mixed air and thus detect any change in the proportion between the outdoor and recirculated air passing through the inlets 3 and 2 respectively. In case the outdoor air is at lower temperature than the indoor air, a greater Jamount of outdoor air than the predetermined amount for which the thermostat 22 is set will cause the latter to swing the damper 9 to the right and thusreduce the amount of outdoor air admitted to the blowers. The thermostat 22 will likewise sense a preponderance of the'recirculated or room air admitted through the inlet 2 nate at one side in an indoor or recirculated air inlet 2 and at the other sidein an outdoor-or fresh air inIetdesignated generally bythe character 3.. The-casing is of restricted dimension at itsupper endfas'in'dicate'd at 4, and termi nates in a mixed air outlet'5.

The lower end or larger portion of the casing contains one-or more blowers 6 preferably of the well-known centrifugaltype having an eye I. In linewith the eye 1, there is'a shaft 8 which carries a damper 9' of arcuate configuration and adapted' to oscillate, pendulum fashion. The lower end of the dampernrests .on a plate [0 which f rms'the upper terminus of a partition or} walLl I, positioned approximately midway between theltwo. sides of the casing I- The recirculated .air-inlet'2- is preferably provided with a grillei l 2 and theoutdoorair or fresh air inlet 3 is preferably provided with an angular form of louvre IS. The, latter is, conveniently mounted-in a casing llhavingopenings I5 at" each side; 'The casing I 4. is shown as being positionedwithin a'casement opening l6. of a wall I! which constitutes, part of the building which isbeing air conditioned. ,The inlet opening 3 of the casing I is, positioned in line, with. the open-v ings-l5, "andprefera'bly in line with the inlet opening 2, from which it is separated'by' the par- 7 tition ll.

The, upper or contains a. heat exchanger [8 which may consist. ofpip'es l9 provided with fins '20, the pipes being adapted to carry. either a heating fluid 511611.28 steam or a cooling fluid such as brine restrictedportion of the casing or.other refrigerant. On each side of the heat exchanger. I8, there is positioned a thermostat 2|, 22 which may be of the pneumatic, electric or bimetallic strip type. .However, for practical reasons, I prefer. to employv a,.leakstat form of thermostat such as is described inmy application Serial No. .144,216, filed .May 22, 1937. A thermostat of this type depends on the relative expansionof, twometals when subjected to heat, these metals .being soarranged that the change in expansion. causes the pressure in a fluid systern tochange in'a corresponding degree. This change in pressure operatesa pneumatic motor or engine (not shown).. The latter is mechanically connected to the damperiaand serves to actuate the. damper ,It. is pparent that, if desired, the thermostats 2|, 22 can be soarrangedas to operate electriclmotors .for actuation purposes; These 'thermostats have been indicated purely;bydiagrampsince their construction is well.kno, in the 'art., .As shown on the drawing, the outlet or discharge opening. 5 is pro-.

videdwith a grille 23.

and will thereupon cause the damper 9 to swing tothe left to cut down the amount of recirculated air; The thermostat 2| is provided for the purpose of controlling the temperature of the mixed air after it has passed through the heat exchanger [8 and this it does by regulating in any suitable and well-known manner the amount of the cooling 'or heating medium passing through the pipes 19; i

The system; as described above, operates quite satisfactorily under normalconditions, but it is apparent that if a sudden gust of wind, particularly of cold air were to strike the inlet 3, the thermostats 2|, 22 ,could not operate with 'suflicient speed to turn on more steam through the radiator and to move the damper 9 to the right. In case of periodic gusts, it is apparent that the thermostats and associated controlmechanism mayfluctuate. ratherwildly. which would prevent the unit from delivering air of a proper and even temperature to the room through theoutlet 5.

In. accordance with the present invention, I

provide an improved structure which takes care considerably greater than the portion which extendsupwardly from the.pivot. The latter portion .is preferably of the same length as the distance between the pivot and the flange 26. The lower or angular portion of the bafiiehas a curved rather than a sharp corner.

It is apparent that, in case a gust of wind comes through the louvres l 3 and the inlet opening 3, the pressure developed thereby will cause the baflle to swing to the left, as indicated by the dotted lines in Figure. 1, and the area of the bafile as projected against the inlet opening becomes greater. It will be further noted that, due

to this increase in projected area, depending on wind become .moresevere. Thus, the baffle will assume its proper position determined by the instantaneous forces exerted by the wind in a very short period of time and hence immediately preventing an excess of outdoor air to find its way into the blowers 6. The excess of air brought about by increased wind pressure is, in one sense, excluded practically entirely from the casing and hence the thermostats 2 I. 22 are not called upon to exercise any. control.functioninsofar as the inthesamaplanaas the baffles?! is indicated short blasts ofiair are concerned." However, it will be understood that'th'e lattenwill malre the necessary adjustments in'the, heat exchanger, l8 and the damper 9 when thechanges in outdoor air temperature or the changes in the volume of the outdoor air at the same temperature are of a steady characterand thusgcan' be sensed by the two thermostats.

The optimumshape of the baffle to, take care of abrupt changes in wind pressure can readilybe determinedby experiment and its position carefully adjusted in the. absence ofp windconditions in any suitable manner,- for example, byapplying 1 weights at any part of the bafile. In general,- this position will be thatv shown; in thedrawing in which the long leg 'of'the baffle is substantially vertical. In case the shape of the baffle or its initial position-is such thatgthe bafiie does not take care of all of the increase in pressure brought about by the gusts of wind, the excess pressure as represented by the small portion of wind which gets into the casing can be readily accommodated by the thermostats 2!, 22; This proportion is usually so small that,reven if it is not sensed quickly enough by the thermostats, its effect is sufficiently diluted by mixture with the operateas aunit, to-close'off the spacebetween the partition Hand'the flange: 30,1 except for a bin-.Figure provides a very positive movement of all of the baiiies. in response to changes in recirculated air in the blower Gas to cause little or no discomfort to the occupants of theroom.

In order more nearly to close off-the outdoor inlet to the casing in responseto wind pressures, it may be desirable to provide a plurality of bafiles. of baffles 21 which are pivoted-at'28 at positions just below a filter 29 of any suitable and wellknown type. While these baffles may assume a pronounced angular shape. as in the case of Figure l, I have shown them in the form of a flat plate with a short curved portion at the bottom.

The inlet opening in this case is determined by the space between the partition H and the flange- 39 which may provide a support-at one endfor the filter.

It will be noted in this case that the 'baliles 27 have no projection or extension above the pivots 23. As gusts of wind pass through the louvres 13, the baflies 21. are swung to the left and it is apparentthat they can assume positions depending on increase in wind pressure such as to practically entirely out off the space between the partition I l and the flange 30, except for the small space between therighthand baffle and the flange. As in the caseof Figure 1, their projected area increases as they are swung to the left, but in Figure 2, this area is measured with respect to the lower surface of the filter 29 rather than the space between the flange 30 and the lower edge of the casing.

It is evident that the greater the number of baiiles which are employed to break the wind, the less will be the space between the righthand baiiie and the flange 33 which is always left exposed to the wind. Thus, in Figure 3, I have shown four baiiles 2i, hanging in vertical planes and pivoted at 28 with only a very small space between the righthand baffle and the inner edge of the flange 3%.

Figure 4 shows a modification, in baffles 2! are mechanically interconnected by levers Si, 32, 33. The pivots 28 may carry shafts which extend across the entire width of the filter 29 and the levers 3!, 32 are connected to these shafts at a position beyond the edge of the filter. The fact that the levers 3!, 32 and 33 are positioned away from the filter 29 and, therefore, not

Thus in Figure 2, I have shown a pair which the tion'sofj the levers- 3l,g32;and 33. The leveroperated 'bafliesshown in Figure e mayhave advantages; under certain conditions, particularly in case thewindzpressure is notthesame over the entirefheight'of' the outdoor air' inlet. Thus, when any, part; of' either of; the bafiies 21 is subjectedto i wind pressure, au'or the-- baflies small space between the righthand'bailie and the flange.

It is also apparent that the lever system shown outdoor air velocity pressure. As in the case of Figure 3, additionalbafiles may be employed in Figure 4,- with a corresponding increase in-the leversystem.

Instead. of providing levers between the various baffles, I mayemploy gears for causing the bafifles to operate, in synchronisrn'. Thusyin Figure 5, the baffle 34-; which may take-the general form shownin Figure 1, is. adapted toswing with a shaft 35. .This shaft extends to a position beyond the filter 29 and carries a gear 36 which meshes with a gear 31 which is mounted'on a shaft 38. The latter carries a plate baflie 39 which, as in the case of the baflie 34, extends the entire length of the filter. Thus, as a gust of wind enters the inlet 3 through the louvres |3, the bafile 34 is swung to the left andv the gear 36- is rotated clockwise, depending on the amount that the baffle has shifted. The rotative effort of the gear 36 causes the gear 3'! to. rotate in the counterclockwise direction which, in turn, rotates the shaft 38 and moves the baffle plate 39 to the left.

It is apparent that if the gust of 'lwindis sufficiently severe, the bafiles 34' and 39 may be caused-to take positions such as practically entirely to close thespace between the partition I I and the flange'30. Thus, the wind or rather the majority of theexcess pressure due to a sudden gustof 'wind is prevented from deleteriously affecting the ventilating system;

From the foregoing it is evidentthat I have invented an improved unit jventilator which contains an adequa te provision for taking care of sudden gusts of wind or other abrupt increases in pressure of the outdoor air. By;providing the baffle or baflles in -the region of the outdoor air inlet, it is apparent that the excessive air pressure is not introducedinto the casing at all. Furthermore, there is no opportunity for the Wind to pass through the outdoor air inlet'and get by the damper in such quantity as to cause a blow through effect; It is, therefore, possible to position the unit ventilator on either the leeward orthewindward side of a building and still obtain conditioned air at-an even temperature through the outlet 5, regardless'of any abrupt changes in air velocity pressure conditions onthe outside of the building.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A ventilating unit comprising a casing having a recirculated air inlet, an outdoor air inlet and a mixed air outlet, a passageway leading from said outdoor air inlet into said unit, a damper for controlling the proportion of outdoor air with respect to, recirculated air, and means for materially reducing the size of the, outdoor air inlet passageway in accordance with instantane ous increases in the velocity pressure of the outdoor air, said means comprising abaflle of L- shaped cross-section pivoted along one edge of one ofthe legs in order to swing in response to wind pressure andadapted toassume such a posi tion that the size of the outdoor air inlet passage way is materially reduced in accordance "with increases of said velocity pressure.

2. A ventilating unit comprising a casing having a recirculated air inlet, an outdoor air'inlet door air inlet, said means comprising a lurality of battles of'similar configuration and each having a pair of legscangularly positioned with respect to one another, one of said legs being longer and a mixed air outlet, a passageway leading from said outdoor air inlet into said unit, a damper for controlling the proportion oiioutdoor air with respect to recirculated air, and means for reducing the size of the outdoor air'inlet passageway in accordance with instantaneous increases in the velocity pressure of the outdoor air,

said means comprising a baflle adapted to swing in response to wind pressure, said' bafile being L- shaped in cross section and pivoted along one edge of one of the legs 'so that upon being swung out of position directly by the wind, the area of the bafile projected in the'direction ofthe' wind materially increases.

3. A unit ventilator comprising a casing having a recirculated air inlet, an outdoor air inlet anda mixed air outlet, a damper for controlling the proportion of outdoor air with respect to, recirculated air,,and means for preventing a gust of wind from entering the, casing through said outdoorair inlet, said means comprising a battle of angular cross section and pivoted at its upper edge in line with the upper edge of the outdoor air inlet whereby the projected areapresented by the baiile "to the wind'increases rapidly as the battle is swung away from its normal vertical position 4. A unit ventilator comprising a casing having a recirculated air inlet, an outdoorair inlet and a mixed air outlet, a passageway leading from said outdoor air: inlet'into said unit, a damper recirculated air, and means for preventing a gust of wind from entering the casing through said outdoor'air inlet, said means comprising a baffle having a pair of legs angularly disposed with respect to one another and pivoted at the end of one of the legs in line with the upper edge of the outdoor air inlet, the legcontaining the pivot being longer than the other leg whereby the projectedarea presented by the baffle to the wind attempting'to enter through the outdoor air inlet increases rapidlyas the bafile is swung away from its normal position.

7. A'unit ventilator comprising a casing having a recirculated air inlet, an outdoor air inlet and a mixed air outlet, a damper for controlling the proportion of outdoor air with respect to recirculated air, and means for preventing a gust of for controlling the proportion of outdoor air with respect to recirculated air, and means for preventing a gust of wind from entering the casing through said outdoor air inlet passageway, said means comprising a plurality of baflles of similar configuration and each pivoted at one end in line with the upper edge of the outdoor air inlet whereby the bafiles hang in a substantially paral-, lel relationship'and when'struck by wind each baflle tendsto close a proportionate amount of the area of the outdoor inlet passageway.

5. A unit ventilator comprising a casing having a recirculated air inlet, an outdoor air inlet and a mixed air outlet, a damper for'controlling the proportion of outdoor air with respect to recirculated air, and means for preventing a gust of wind from entering the casing through said outwind from entering the casing through said outdoor air inlet, said means comprising a battle pivoted intermediate its ends and nearer the upper end inlinewith the upper edge of the outdoor air inlet opening whereby the baflle hangs vertically downward across the opening, said baffle being L-shaped in cross section with the apex of the baflle directed away from the outdoor air inlet opening, the distance between the pivot and the nearer'end of the baflle being commensurate with the distance between the pivot and the casing whereby when the bafl'le is swung out of position by an impinging wind, the pivoted end of the baffle tends to close the space between the pivot and the casing.

8. A ventilating unit comprising a casing having a recirculated air inlet, an outdoor air inlet and a'mix'ed air outlet, a damper for controlling the proportion of outdoor air with respect to recirculatedair, and means for preventing a gust of wind from entering said casing through the outdoor air inlet, said means comprising a pair of bafiies operatively connected together by gearing, ne of said baffles having an angular configuration and pivoted at one end and the other of saidbaflles having a flat configuration and so positioned with respect to the angular battle that the two bafliestogether restrain the entry of wind into the casing over the entire area of the outdoor air inlet.

JOHN MCELGIN.

Images