US2692547A - Ceiling construction for the deadening of sound and the distribution of circulating air - Google Patents

Description

1954 w. M. ERICSON 2,

CEILING CONSTRUCTION FOR THE DEADENING OF SOUND AND THE DISTRIBUTION OF CIRCULATING AIR Filed March. 15, 1951 2 Sheets-Sheet l 3nventor WHATEE M. 52/550 Gttornegs Oct. 26, 1954 w. M. ERICSON 2,692,547 CEILING CONSTRUCTION FOR THE DEADENING OF SOUND AND THE DISTRIBUTION OF CIRCULATING AIR Filed March 15. 1951 2 Sheets-Sheet 2 3 nventor WHLTE/e M. Ee/c 50M W, Mia

Gttorncgs Patented Oct. 26, 1954 UNITED STATES PATENT OFFICE CEILING CONSTRUCTION FOR THE DEADEN- IN G OF SOUND AND THE DISTRIBUTION OF CIRCULATIN G AIR Walter M. Ericson, Wauwatosa, Wis.

Application March 15, 1951, Serial No. 215,682

3 Claims.

This invention relates to a ceiling construction for the deadening of sound and the distribution of circulating air.

The invention makes use of acoustical elements to achieve the uniform flow of circulating air through the entire area of a ceiling embodying the invention. In the past, attempts to use the same elements for the dual functions of acoustical treatment and air distribution have failed to prevent the air from finding selected channels through which it flows at relatively high velocity. Through the constructions herewith disclosed, sound absorption may actually be increased, as compared with previous use of the same materials.

In one construction the sound absorbing pads, which are individually of relatively small area, are spaced above ported pans and also spaced from each other to obstruct all channels of sound penetration, to provide maximum impingement; and to subdivide and re-subdivide the air flow so that such flow will be uniform throughout all of the apertures of all of the panels at low velocity, the pads not only distributing the flow, but also filtering it, and being readily replaceable when dirty.

In another, and frequently preferred, construction, the sound absorbing pads have individually controllable valves which are readily adjusted to distribute flow uniformly. In this embodiment the air flow is always downward through the pads to the perforate pans, and the elimination of flow horizontally on the pan surfaces avoids entrainment of room air and consequently avoids dirt deposits on the under surfaces of the perforate pans.

In the drawings:

Fig. l fragmentarily illustrates in plan a ceiling constructed in accordance with the present in vention, different portions of the view showing the construction at different levels in the ceiling.

Fig. 2 is a View taken in cross section on the line 2-2 of Fig. 1.

Fig. 3 is a view taken in cross section on the line 3-3 of Fig. 2.

Fig. 4 is an enlarged detail view in perspective showing a portion of the metallic structure erected before the pads are applied.

Fig. 5 is a further enlarged fragmentary detail view showing in section a small portion of the completed ceiling.

Fig. 6 is a plan view of a modified false ceiling, some of the pads being omitted.

Fig. 7 is a diagrammatic view in vertical section through the structure of Fig. 5.

Fig. 8 is an enlarged detail view of a sound absorbing pad provided with a valve port for the purpose of the structure shown in Figs. 6 and '7.

The metallic framework shown in Fig. 4 is conventional and any such conventional framework can be used, without change, for the purposes of the present invention. The channels 1 serve as girders which are supported in any desired manner, as by means of the tension rods 8, from the true ceiling 9. Supported on the girders l are the conventional stringers l0, one of which is shown in enlarged cross section in Fig. 5. These have downwardly converging flanges ii and I2 formed to provide opposing semi-circular channels at i3 and M, respectively, beyond which the flanges have diverging lips l5 and I6.

Perforated pans 20 are likewise conventional, each comprising a foraminous bottom wall 2! which is perforated with numerous holes representing about 5% the total area of the bottom. The upstanding flanges 22 comprising the side and end walls of each pan have ribs 23 which are complementary tothe channels l3, M, of the flanges ll, l2, of stringers I 0, whereby the pans may be snapped into engagement with the stringers to receive support therefrom.

In practice, these pans are made two feet wide and four feet long and the stringers [0 are usually set at four foot spacing between centers so that the ends of two consecutive pans are connected to each stringer. In the prior art, a pad of insulating material of predetermined thickness is then laid in each pan to intercept and damp the sound waves penetrating into the pad through the apertures of the pan.

The space 25 which, as shown in Fig. 2, is present between the true ceiling 9 and the false ceiling thus erected, is ideally adapted to constitute a plenum chamber into which circulating air can be delivered, as by duct 6, from the out-of-doors or from any heating or cooling system. However, it has been found in practice that air admitted into the space at 25 does not distribute itself to flow downwardly through the pans uniformly, but flows in unpredictable fashion, all of the flow tending to be concentrated at relatively high velocities in relatively limited areas.

According to the present invention, the total thickness of acoustical padding is divided into two layers of pads, each of which has half of the total desired thickness.

Starting with the metallic framework of the false ceiling erected conventionally and comprising the girders l, the stringers l0 and the pans 29 as shown at the left in Fig. 1, I first lay the relatively spaced pads 26 upon the respective stringers 10, each pad being desirably centered upon a given stringer as shown at the center of Fig. 1, the side margins of each pad resting on the side flanges of the underlying pans as clearly shown in Fig. 2. Since the tops of the stringers are at a slightly higher level than the upper margins of the flanges 22 of pans 20, as appears both in Fig. 2 and Fig. 5, the side margins of the pads 26 will tend to fall slightly until supported on the flanges. It will, of course, be understood that pads of any suitable acoustical material may be used, pads of glass wool and pads of fiber being illustrative. Since the air is not required to flow through the pads, their density is of little importance so far as air circulation is concerned and may be determined entirely from an acoustical standpoint.

The way that the pads appear when draped over the stringers ID will depend to a considerable extent upon the nature of the pads themselves. However, they have quite a measure of stiffness and will readily bridge the space between the upstanding pan flanges. Assuming the dimensions given above for the sizes of pans and spacing of stringers and girders, the pads used may conveniently be four feet long and twentyone and one-quarter inches wide.

Pads are made somewhat narrower than they would be made if they were to fill the pans. The purpose of this is to leave well-defined slots at 21 between consecutive pads. of these slots are desirably predetermined with reference to the areas of the holes in the pans, the total slot area and the total area of the holes being desirably about equal, although there is nothing critical about this.

Supported upon the pads 26 are the pads 28 which may be of identical size and shape to pads 26, being likewise spaced from each other to provide slots at 29. The pads 28 are, however, staggered with reference to the pads 26 so that the slots 29 are offset from the slots 21. The pads 28 are not laid directly upon pads 25, but are supported above pads 26 by means of blocks 30, in any desired number, which may be made of pad material or otherwise and which may be cemented beneath pads 28 or held thereto by staples as shown at 3| in Fig. 5. I have shown in dotted lines in Fig. 1, six such blocks or feet supporting each pad. According to the stiffness of the pad, a smaller or greater number may be used. The block will ordinarily approximate the pads themselves in thickness, so that the spacing between the lower pads 26 and the staggered upper pads 28 will be about the same as the thickness of the respective pads. ing used, it should be adequate for the flow of air desired and should preferably provide airflow channels of a capacity equal to the ag gregate capacity of the holes in the pans and the slots between the pads. The pads are sufficiently porous so that if the capacity of the slots between pads or the channels between the lower and upper layers of pads were less than the capacity of the holes, the difference might be made up by flow through the pads themselves. However, this is undesirable because the pads are not of uniform density and, for perfect distribution, it is desired that the air stream be uniformly subdivided and re-subdivided by flow through the non-registering ofiset slots and, ultimately, through the individual holes of the respective pans.

Since the pads are merely laid in place, the first layer being draped on the metallic framework and the pans and the second layer being The dimensions Obviously, whatever the spaci supported directly upon the first, there is no difficulty either in the original placement or in the replacement of the pads. Ultimately, they will require replacement, since their rough surfaces will tend to collect dust and lint which may be entrained with the air moving at very low velocities through the devious channels provided by the structure. It will be observed, however, that accumulations of dust do not block air flow, since the flow does not necessarily occur through the porous pads, but through the channels between them. However, the pads do supply a very comprehensive filtering effect, notwithstanding that much of the air does not pass through them, because the sinuous path traveled by the air exposes the broad faces of the pads to the air and their rough surfaces collect dust as heretofore pointed out.

It is to be noted that the aggregate thickness of the two layers of pads need not necessarily equal the pad thickness which would be required for acoustical purposes if only a single pad were used, since the mutually spaced layers provide multiple impingement surfaces, being thereby more emcient for acoustical purposes than a single layer.

The lower layer is desirably close to the holes in the pans and thereby attains an acoustical absorption effect which is greater than would be the case if the lower layer were either in direct contact with the bottom of the pan or were spaced more remotely therefrom.

In the structure of Figs. 6 to 8, the same conventional metallic framework is shown, this being representative of any adequate support for the perforated pans 20 and the special pads 260. While these pads are desirably made of glass wool or other suitable fiber, they may be somewhat more compact than the pads previously described so that very little, if any, air flow can pass through the pads. Moreover, the pads 26!) are desirably quite rigid to span rectilinearly the spaces between the stringers I0 upon which their margins rest, as shown in Figs. 6 and 7.

A number of such pads, desirably each of them, is provided with an opening at 32 controlled by a valve plate 33 which may be a simple disk of thin sheet metal having a laterally projecting tab 34 through which a nail or tack extends at 35 into the pad 260 to provide a pivot on which the valve plate is movable. No such pivotal connection is required, since the valve, once adjusted, remains untouched. There is no tendency for any such valve to move from the position in which it is lying on the upper surface of the pad.

When a false ceiling is erected in accordance with this invention, the pads are laid upon the stringers with their several edges in substantial contact so that the bottom of plenum chamber 25 is completely closed except for the ports 32. It will, of course, be understood that the pads are desirably small for convenience of placement, with one port per pad, but that a larger number of ports per pad would be provided if the size of the pads were to be increased. Before the pans 20 are attached to the stringers ill in the manner above described, the valves 33 are set in positions which, in the best judgment of the contractor; will give approximately uniform flow. As aforesaid, the actual flow is unpredictable and it cannot be measured with instruments because the rate of fiow is necessarily extremely low in any given portion of the ceiling. However, the relative flow through the several ports can be extended by introducing chemical or other smoke into the air stream admitted through the ventilator 6 to the plenum chamber 25. The contractor can reach through the ports 32 to open or close the valves 33 by oscillating them across the ports until the rate at which the smoke issues from the respective ports is substantially uniform throughout the false ceiling. Thereupon the perforated pans 26 are applied to complete the false ceiling.

As in the device previously described, the acoustical effect is superior to that which is achieved when the pads are in direct contact with the pans. In practice, the control achieved through the use of the device of Figs. 6 and 8 is superior to that achieved through the use of the device disclosed in Figs. 1 to 5 because the latter is not so readily adjusted. In addition, I have found the embodiment of Figs. 6 to 8 to be preferred because of the fact that the direction of air movement is always downward. Where the air has any substantial lateral movement, as is required in the embodiment of Figs. 1 to 5, there may be a tendency to entrain room air, causing the latter to pass upwardly through some of the openings of pans 29, thus depositing dirt on the lower surfaces of such pans and about the margins of the openings through which the flow is upward. Such deposits have not been found where the embodiment of Figs. 6 to 8 is used.

In both embodiments the fresh air is admitted to the room Without perceptible draft and with a high degree of uniformity of distribution, virtually perfect uniformity being achievable with the structure of Figs. 6 to 8.

From the foregoing disclosure, it will be evident that in both embodiments my improved ceiling structure uses its component parts both for air distribution and for acoustical absorption with results which are more eflicient for both purposes than the same parts would be if assembled in a conventional manner.

I claim:

1. In combination with a ceiling, a set of pans having perforated bottoms, supports carrying the pans at a level below the ceiling to provide a plenum chamber, means providing a ventilating air supply connection to said chamber, laterally spaced pads comprising a first fibrous layer spaced above the bottoms of the pans, and means for controlling air flow from said chamber through the spaces between the pads of said first fibrous layer toward said pans, said flow controlling means comprising laterally spaced pads in a second fibrous layer spaced above said first layer, the pads of the second layer being offset from the pads of the first layer, whereby the spaces between the pads of the second layer are staggered respecting the spaces between pads of the first layer.

In a ceiling of the character described for sound absorption and air distribution, the said ceiling spaced from the true ceiling of a room to provide a plenum chamber, the combination with a network of supporting girders and stringers, and pans having perforated bottoms and having upstanding flanges, certain of which are in detachable connection with the stringers, of pads of acoustical material having an aggregate extent less than the aggregate extent of the pans by an amount approximately equal to the aggregate area of the apertures in the pan bottoms, the pads being individually laid upon the stringers and being narrower than the spaces between stringers, whereby the pads on one stringer are laterally spaced from like pads laid upon adjacent stringers to constitute channels between said pads, the margins of the pads being supported in part by the flanges of the pans and the respective pads being thereby supported free of the perforated bottoms of the respective pans, together with a second layer of pads laterally spaced from each other and each of which is disposed to span the openings between adjacent pads in the first layer, the pads of the second layer being provided with feet supporting them from the adjacent pads of the first layer and being mutually spaced to provide channels at least approximately equal in aggregate area to the channels between the pads of the first layer.

3. In a ceiling, a plurality of layers of acoustical pads, means supporting the pads in the respective layers in positions laterally spaced from each other, means supporting the pads of one layer vertically spaced from the pads in the other layer to provide air channels between layers, the pads of the respective layers being vertically staggered whereby the lateral spaces between the pads of one layer are ofiset respecting the lateral spaces between pads of another layer.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,933,221 Rockhoff Oct. 31, 1933 1,964,473 Lesher June 26, 1934 1,998,423 Stubbs Apr. 16, 1935 2,009,512 Oifutt et al. July 30, 1935 2,017,548 Rosenblatt Oct. 15, 1935 2,073,036 Voigt Mar. 9, 1937 2,172,771 Norris Sept. 12, 1939 2,172,944 Norris Sept. 12, 1939 2,180,945 Morey Nov, 21, 1939 2,221,001 Lucius Nov. 12, 1940 2,276,788 Norris Mar. 17, 1942 2,349,158 Fowles et a1 May 16, 1944

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