US2564334A

US2564334A - Air outlet

Info

Publication number: US2564334A
Application number: US713855A
Authority: US
Inventors: Walter W Kennedy
Original assignee: Barber Colman Co
Current assignee: Barber Colman Co
Priority date: 1946-12-04
Filing date: 1946-12-04
Publication date: 1951-08-14
Anticipated expiration: 1968-08-14

Description

1951 w. w. KENNEDY 2,564,334

AIR .OUTLET Filed Dec. 4, 1946 4 Sheets-Sheet l INVENTOR. h a/ t er Kennedy BY ATTORNEYS 4, 1951 w. w. KENNEDY 2,564,334

AIR OUTLET Filed Dec. 4, 1946 4 Sheets-Sheet 2 INVENTOR. h a/ter M Kennedy ATTORNE Y5 1951 w. w. KENNEDY 2,564,334

AIR OUTLET Filed Dec. 4, 1946 I 4 Sheets-Sheet 5 INVENTOR. h a/ter h /1 0106615 BY 4449 a? M44. ,1- 41% A T TORNEYS 1951 w. w. KENNEDY 2,564,334

AIR OUTLET Filed Dec. 4, 1946 4 Sheets-Sheet 4 n I6 25 27 2 5 Q y 52 I 1/ ////l I I9 20 I INVENTOR. 42 4 h a/ter 2 KGflflec/g a Q I MMvJlfu ATTORNEYS Patented Aug. 14, 1951 AIR- OUTLET Walter W. Kennedy, Rockford, 111., assignor to Barber-Golman Company, Rockford, 111., a corporation of Illinois Application December 4, 1946, Serial No. 713,855

- The invention pertains to an air outlet for air conditioning systems and the like and has particular reference to a wall outlet for use in conjunction with an elongated air duct concealed behind the wall.

In providing for the distribution of conditioned air to large rooms, the common practice is to arrange an air supply duct along the room wall, either above the ceiling or behind a side wall, and to cause the discharge of the air into the room through the medium of a plurality of distributing outlets located at a plurality of points along the wall spaced apart a distance calculated to effect proper distribution of the air throughout the room. This method of distribution is customarily employed in large rooms such as are found in public buildings and entails the use of individual outlets commonly circular in form, a characteristic which is frequently objectionable to designers and architects because outlets of this shape do not conform to the conventional rectangular shape of the room.

One object of the invention is to provide an air distributing outlet especially adapted for use with an air supply duct extending lengthwise of the ceiling or other wall of a room so as to be concealed thereby, which for economy in manufacture and ease of installation is composed of a plurality of rectangular sections fashioned for disposition in end-to-end relation in a slot cut in the room wall so as to be substantially concealed thereby and having exposed panels disposed substantially flush with the room wall and coacting to form a continuous face panel.

A further object is to provide a sectional panel outlet of the character indicated wherein the sections are composed of rectangular housing units of uniform construction adapted for insertion through a slot in the room wall and panel units of varying construction detachably connected with the housing units and wherein at least certain of the panel units coact with their respective housing units to efiectually control the delivery of air to the room.

The provision of concealed lighting in present day building constructionhas presented a serious problem, especially from the standpoint of appearance. With this in view,my invention contemplates the provision of panel units for certain of the sections incorporating lighting fixtures in a manner such as to be efiectually enclosed and yet readily accessible. I

Another object is to provide an outlet of rectangular form constructed almost entirely of sheet metal strips rolled or bent to shape transversely Claims.

for economy in manufacture and composed of a housing unit for attachment to the air supply duct and a panel unit coacting therewith to provide a plurality of outlet passages of a length coextensive with the length of the entire outlet.

A further object is to provide an elongated air outlet in which the air is discharged in a plurality of streams spaced apart along th surface of the wall so as to provide between the streams intervening spaces exposed to the room air and permitting the flow of the latter toward the wall surface so as to enter the aforesaid negative pressure zones created by the discharge of the air streams, thereby effectually overcoming the tendency of such streams to scrub the wall surface.

The objects of the invention thus generally set forth, together with other and ancillary advantages, are attained by the construction and arrangement shown by way of illustration in the accompanying drawings, in which:

Figure 1 is a fragmentary perspective view showing the improved panel outlet applied to the ceiling of a room.

Fig. 2 is a fragmentary central longitudinal sectional view of the outlet.

Fig. 3 is a fragmentary perspective view showing one form of outlet attached to an air supply. duct.

Fig. 4 is an exploded view showing an air distributing section with the panel unit disassociated from the housing unit.

Figs. 5 and 6 are views similar to Fig. 3 but showing a modified form of panel unit.

1 Fig. 7 is a top plan view of a single air distributing section.

. Fig. 8 is a fragmentary sectional view taken approximately in the plane of line 8-8 of Fig. 7.

Fig. 9 is a fragmentary sectional view showing one of the lighting sections in particular.

Fig. 10 is an exploded view showing in section the panel unit for the lighting section in disassocia'ted relation to the housing section.-

V In the preferred embodiment of my invention, the improved panel outlet comprises, in general, a plurality of sections arranged in end-to-end relation and includin air distributor sections l0 alternating-with light emitting sections l I. Herein, the panel outlet is shown mounted in the ceiling'of a room with the distributor sections in communication with an elongated air supply duct l2. The lighting sections may or may not communicate with the air supply duct but man case are utilized for the enclosure of lighting fixtures so that the'entire panel outlet performs a com 3 bined air distributing and lighting function. If desired the lighting sections may instead of communicating with an air supply duct communicate with a return air duct (not shown) and this serves as an air outlet for room air.

Each of the sections composing the panel outlet comprises a generally rectangular housing unit I3 permanently incorporated in the room wall, and a panel unit detachably connected with the housing unit, such panel unit being generally designated I4 in the case of the distributor section and I5 in the case of the spacing section. For economy in manufacture, the housing units for both sections are made alike. As shown, each comprises a pair of spaced parallel side plates or strips I6 of sheet metal connected at their opposite ends by end plates I! to form a rectangular frame. The side strips are shaped to provide inner parallel edge portions I8 and outwardly and laterally diverging edge portions I9 preferably terminating in external beads 20. If desired the end plates may be appropriately shaped to conform to the shaping of the side strips and formed with beads 20a. These end plates are secured to the side strips in any suitable way as by means of ears 22 formed integral with the end plates and spot welded to the side strips.

As best shown in Figs. 3 and 4, the housing units are inserted through an elongated slot 23 in the ceiling, and in the case of the distributor units communicate with spaced openings in the supply duct defined by depending flanges or collars 24. The parallel side portions I8 of the side strips I6 are secured to the collar, as by means of screws or rivets 26 and serve to form supply channels 25 one for each unit. The unit is thus secured in position with the [heads 20 engaging the ceiling at the marginal edges of the elongated opening 23 in the ceiling. Preferably the upper portions of the beads 20 are constructed to form channel shaped recesses for receiving packing or sealing strips 21 of felt or the like.

The sections I6 and II are preferably secured together in end-to-end relation. For this purpose, the adjacent end plates of the adjoining sections are connected by suitable fastening devices such as bolts 28. Where beads 20a are employed on the end plates I! the bolts may be equipped with suitable spacer sleeves 28a.

The panel units I4 for the distributor sections may be variously constructed. Their function is to control the discharge of air into the room and to diffuse the same so as to avoid impingement of the delivered air upon the occupants of the room. As shown in Figs. 3 and 4, each panel unit I4 comprises a pair of spaced parallel side or louver strips 30 of sheet metal connected at opposite ends by end plates 3 I, and a central louver plate 32 secured at its opposite ends to the end plates SL The louver strips 36 are made relatively narrower than the side strips I6 of the housing units but are shaped to correspond generally to the shape of the housing strips and are spaced therefrom so as to form downwardly and outwardly opening passages 33. Thus the upper edges of the inner louver strips 3!] terminate in a plane substantially downward from the upper edges of the side strips I6 of the housing unit and define between them a chamber 34 communicating with the outlet channel 25 formed by the collar 24.

In Figs. 3 and 4, the central louver plate 32 is shaped to form two upwardly convex side portions 35 disposed in downwardly and inwardly spaced relation to the louver strips 30 so as to define two outwardly and downwardly inclined passages 31. Preferably, the louver strips 30 and the edge of the central louver plate 32 terminate in

beads

38 and 39 in spaced parallel relation to each other and to a central rib 40 formed between the two curved portions 36 of the face plate. As shown, such beads are disposed in a common plane substantially coincident with the beads 20 of the housing unit so as to present the appearance of a louvered panel.

The end plates 3| of the panel units are utilized to advantage in cooperation with the end plates of the housing unit in removably securing the panel unit in position in the housing unit. Thus, with the panel unit dimensioned to fit into the housing units, the end plates of the panel units are conveniently secured to the corresponding end plates of the housing unit as by means of screws or rivets inserted through holes 4| and 42.

It will be seen that air delivered to each of the distributor sections is received first in its out-- let chamber 25. It is then divided, with portions passing downwardly and thence outwardly through passages 33, and the remainder directed into the central channel 34 and thence outwardly and downwardly through passages 31.

For the purpose of intercepting and directing air flowing through the duct I2 into the channels 25, each of the collars 24 is preferably equipped with a series of vanes 43 (Fig. 2) adjustably mounted in the collar and projecting upwardly into the duct transversely thereof. The vanes may be supported in any suitable or preferred manner. Herein they are shown provided with ears 43a mounted on pivot pins 43b so as to be swingable relative to the collar, the construction being such that the vanes are frictionally held in any desired position of adjustment.

In the embodiment of the invention as shown in Figs. 2 and 9, the lighting section II does not communicate with the air duct I2 so that the housing unit serves merely to provide a chamber for the reception of the panel unit I5 constructed for the incorporation of concealed lighting fixtures. In Fig. 10, the housing unit does communicate with the duct in the manner above set forth and the panel unit serves not only to incorporate lighting fixtures but also to provide for the discharge of air from the duct. In either case, the construction of the housing units is the same, but instead of being supported directly from the duct they are supported from. the distributor sections by the

bolt connections

28, 28a as seen in Fig. 2. Preferably, in this instance, circulation of air is cut off and the unit strengthened by a cap 44 having edge flanges fitting downwardly into the upper portion of the housing unit and secured thereto by means of screws or rivets 45.

Referring now to Figs. 9 and 10, the panel unit I5 is constructed in a manner generally similar to that of the panel unit I4 of the distributor unit. Thus it has laterally spaced side strips 36 and connecting end plates 3I forming a generally rectangular framework adapted to be secured removably in the housing unit by means of fastening screws entered through holes M and 42 in the end plates [1 and 3|, respectively. However, in lieu of the central louver plate 32, I provide a narrow elongated casing 46 comprising a sheet metal top member 41 having outwardly and laterally inclined side portions 48, end,

plates 49 and a panel member 50 of glass or other transparent or translucent material. Asshown, the panel member 50 is generally channel shaped in cross section and has edge flanges 51 resting upon inturned side flanges 52 on the side portions 48 of the casing. A chamber is thus formed for the reception of appropriate lighting fixtures 53 to which current may be supplied by a cord conductor 54 (Fig. equipped with a plug 55 for insertian into a receptacle 5G in one side of the duct 12.

It will be seen that when the housing unit is arranged for communication with the duct as shown in Fig. 10, the side strips 30 of the panel unit coact withthe side strips 16- of the housing unit to form outwardly and laterally inclined passages for delivery of air to the room,-where-' as the central portion of the panel unit is utilized for the reception of the lighting fixture casing 46.

Referring now to Fig. 5, I have here shown a somewhat modified form of panel unit for the distributor sections of the outlet. In this instance, instead of employing the single central louver plate 32 of Figs. 3 and 4, I employ a pair of

narrow strips

51 and 58 spaced apart laterally so as to form an air slot 59 and the outer edges of these panel strips are spaced from the portions IQ of the housing side strips It to form outlet passages 3311. Above the two strips 51-, 58 is mounted a convexly curved deflector 60 overlying the air slot 59 and having its side edges disposed in overlying relation to said strips and in spaced relation to the diverging portions 19 of the housing strips l6. By this construction, air received from the central portion of the duct and entering the channel 3 formedbetween the side strips 39 of the panel unit is directed outwardly and laterally through narrow passages BI, and room air is drawn by aspiration through. the center slot 59 whence it passes laterally and outwardly mixing with the air discharged through the passages 6|.

Still another form of panel unit is shown in Fig. 6. In this instance, provision is made for adjustably controlling the delivery of air. For this purpose, I provide a pair of laterally spaced panel strips 62 and 63 stationarily secured in the unit in laterally spaced relation to the side strips 30 so as to form discharge passages 54, and coacting with these narrow panel strips is a central panel consisting of two

arcuate wings

65 and 56 hinged together at 67 for movement'relative to the narrow panel strips 62 and 63. The hinged connection 61 is adapted to hold the wings 65, 6E frictionally in various positions or adjustment. When swung downwardly, as for example, into the dotted line position shown in Fig. 6, an additional pair of outlet slots are formed and the widths of these slots may be varied as desired.

It will be observed that all of the housing units are of uniform or standard construction fashioned for insertion through the wall slot 23 and permanently mounted on the air duct l2 with the marginal beads and 20a in abutting relation to the outer face of the wall, and that the panel units may be variously constructed according to requirements and mounted in *the housing units so as to coact therewith in the formation of air passages of a length coextensive with the length of the housing unit. Thus when a plurality of sections are arranged in end-to-end relation, the elongated air passages thereof extend substantially continuously throughout the entire length of the outlet so that the latter presents the appearance of a rectangular face panel, neat and attractive in appearance and disposed substantially flush with the inner face of the room wall. Except for the useof a central glass panel in the case of the panel units for the lighting sections, both the housing and panel units are.

made entirely from sheet metal strips which need only be bent or formed transversely of their lengths as distinguished from relatively expensive spinning operations. required in the case of circular outlets. The detachable mounting of the panel units with respect to the housing units is important not only from the standpoint of interchangeability but also for convenience in gaining access to the'interior of the outlet to the duct as may be desired. The sections are made of lengths convenient for handling. In practice they are made fifty inches in length. When the sections are assembled in end-to-end relation, as shown in Fig. 1, the adjoining sections cooperate to form an elongated panel of rectangular form extending lengthwise ofthe room and conforming to the rectangular shape of the latter. The number of. sections employed may obviously be varied to suit requirements.

The angle of discharge of air from the distributor units must be carefully chosen so as to avoid impingement of air upon the room occupants.

At the same time, itis highly desirable that the air be prevented from scrubbing the outer face of the wall. To avoid undesirable impingement, the air is discharged outwardly and laterally at an angle of approximately 24 to the outer face of the wall. Moreover, the air stream upon leaving the outlet passages at the outer edges of the outlet is spaced a short distance from the face of the room wall by the beads 20, the latter being of a thickness of approximately three-eighths' of an inch.

But. notwithstanding the discharge of the air otuwardly and laterally in the manner set forth, it has been found in practice that the air streams tend nevertheless to hug and scrub the face of the room wall with a resulting smudglng or discoloration thereof. I have discovered that by interrupting these outer air streams at longitudinally spaced intervals, the objectional scrubbing action is avoided. Such interruption may be accomplished in various ways. In Fig. 7, I have shown generally V-shaped members 68 interposed in the passages 33 between the side louver strips it of the housing units and the side louver strips 30 of the panel unit. Similar abutments 69 are provided in the passages 31 between the louver strips 30 and the central panel strip 32.

That the

abutments

68 and 69 are effective in preventing the objectionable scrubbing action is apparently due to the fact that the discharge of the air laterally in wide streams longitudinally of the outlet even though in spaced relation to the face of the room wall, tends to create negative pressure zones between the delivered air and the room wall, causing the air to move into contact with the wall. By interrupting the streams lon- 'gitudinally, room air is permitted to enter between the streams and into the negative pressure areas at opposite sides thereof with the result that the tendency of the discharging air streams to hu the wall is avoided.

It has been found that for effectual control, it is necessary that the air streams be divided longitudinally at rather closely spaced intervals preferably so that each stream does not exceed eighteen inches in width. As the width of each stream is increased above eighteen inches, the room air entering the negative pressure areas fails to penetrate far enough to prevent scrubbing of the wall centrally of the streams. In Fig. 7,

I have shown three abutments 6'8, 69 for the

respective discharge passages

33 and 31, spaced apart longitudinally of the distributor sections approximately sixteen and two-thirds inches. When lighting sections are used in alternation with distributor sections as shown in Fig. 1 to form the panel outlet, with the lighting sections cut ofi from communication with the duct, the lighting sections serve to interrupt the discharging streams at longitudinally spaced points and to this extent permit entry of room air into negative pressure areas created in the discharge of air from the distributor units. However, as above pointed out, when the distributor units are made of a length greater than eighteen inches, additional means such as the abutments B8, 69 are nec essary to effectually prevent an objectionable scrubbing action.

I claim as my invention:

1. A sectional panel outlet for mounting in a room wall having an elongated slot and an air duct on the inner side of the wall with an opening communicating with the wall slot, said panel outlet including a plurality of elongated sections for insertion through the wall slot in end-to-end relation and each comprising a housing unit rectangular in cross section in the plane of the room wall in which they are to be mounted and a panel unit detachably mounted in the housing unit, the housing units each comprising laterally spaced side strips and connecting end plates, the end plates of adjoining sections being disposed in abutting face-to-face relation, and said panel units each comprising laterally spaced side strips and connecting end plates with the side strips in laterally spaced relation to the side strips of the corresponding housing unit and the end plates abutting in face-to-face relation the end plates of such housing unit, the outer edge portions of the side strips of the housing and panel units of each section being spaced apart to form elongated slots between them and the corresponding slots of adjoining sections being in alignment.

2. A sectional panel outlet for mounting in a room wall having an elongated slot and an air duct on the inner side of the wall with an opening communicating with the wall slot, said panel outlet including a plurality of elongated sections for insertion through the wall slot in end-to-end relation and each comprising a housing unit rectangular in cross section in the plane of the room wall in which they are to be mounted and a panel unit detachably mounted in the housing unit, the housing units each comprising laterally spaced side strips and connecting end plates, the end plates of adjoining sections being disposed in abutting face-to-face relation, and said panel units each comprising laterally spaced side strips and connecting end plates with the side strips in laterally spaced relation to the side strips of the corresponding housing unit and the end plates abutting in face-to-face relation the end plates of such housing unit, the outer edge portions of the side strips of the housing and panel units of each section being spaced apart to form elongated slots between them and the corresponding slots of adjoining sections being in alinement, the slots in the case of at least some of the sections opening inwardly for communication with the supply duct.

3. A sectional panel outlet for mounting in a room wall having an elongated slot and an air duct on the inner side of the wall with an opening communicating with the wall slot, said panel outlet including a plurality of elongated sections for insertion through the Wall slot in end-to-end relation and each comprising a housing unit rectangular in cross section in the plane of the room wall in which they are to be mounted and a panel unit detachably mounted in the housing unit, the housing units each comprising laterally spaced side strip and connecting end plates, the end plates of adjoining sections being disosed in abutting face-to-face relation, and said panel units each comprising laterally spaced side strips and connecting end plates with the side strips in laterally spaced relation to the side strips of the corresponding housing unit and the end plates abutting in face-to-face relation the end plates of such housing unit, the outer edge portions of the side strips of the housing and panel units of each section being spaced apart to form elongated slots between them, the slots in the case of at least some of the sections opening inwardly for communication with the supply duct, and the side strips and end plates of certain of the panel units having an inner closure plate secured to their inner edges so as to form a casin for the reception of a lighting fixture.

4. A sectional panel outlet for mounting in a room wall having an elongated slot and an air duct on the inner side of the wall with an opening communicating with the wall slot, said panel outlet including a plurality of elongated sections for insertion through the wall slot in end-to-end relation and each comprising a housing unit rectangular in cross section in the plane of the room wall in which they are to be mounted and a panel unit detachably mounted in the housingunit, the housin units each comprising laterally spaced side strips and connecting end plates, the end plates of adjoining sections being disposed in abutting face-to-iace relation, and said panel units each comprising laterally spaced side strips and connecting end plates, the side strips of the panel units in the case of certain of the sections being spaced from the side strips of their corresponding housing units to form outwardly and laterally directed air passages open at their inner ends for connection with the air supply duct, and the panel units of the other sections having elongated chambers formed between the side strips thereof for the reception of lighting fixtures.

5. An air outlet for mounting in a room wall having an elongated slot and an air duct on the inner side of the wall, said outlet comprising a housing unit for insertion through the wall slot and comprising a pair of laterally spaced side strips and connecting end plates forming a long narrow rectangular frame, and a panel unit supported by said housing unit in nested relation thereto, said panel unit comprisin spaced parallel side strips and connecting end plates, the side strips of the panel units being spaced laterally from the side strips of the housing unit and being of a length substantially corresponding to the length of the latter side strips so as to form elongated air passages of a length substantially coextensive with the length of the housing unit.

6. An air distributin panel outlet for mounting in a rool wall having an elongated slot and an air duct on the inner side of the wall, said panel outlet comprising a housing unit for insertion through the wall slot and comprising a pair of laterally spaced side strips and connecting end plates forming a rectangular frame, said side strips having inner edge portions for attachment to the air duct and outwardly and laterally diverging outer edge portions, and a panel unit supported by said housing unit between the end plates thereof and comprising spaced parallel side strips and connecting end plates, the side strips of the panel units being spaced laterally from the side strips of the housing unit to form elongated air passages of a length substantially coextensive with the length of the housing unit, and the end plates of the panel unit being disposed closely adjacent to and detachably connected with the end plates of the housing unit.

7. An air distributin panel outlet for mounting in a room wall having an elongated slot and an air duct on the inner side of the wall, said panel outlet comprising a narrow elongated housing unit for insertion through the wall slot and comprising a pair of laterally spaced side strips and connecting end plates, said housing unit being rectangular in cross section in the plane of the room wall in which it is to be mounted, and a panel unit interposed between the side strips of the housin unit and detachably connected thereto, said panel unit comprising spaced parallel side strips and connecting cross plates, the side strips of the panel units being spaced laterally from the side strips of the housing unit to form elongated air outlet passages of a length substantially coextensive with the length of the housing unit, and said panel unit having a central panel with opposite edges spaced from the side strips of such unit to form additional air outlet passages, said central panel and the side strips of the housin and panel units being of substantially equal length so that all of said outlet passages present the appearance of parallel slots of uniform length.

8. An outlet for an air duct or the like comprising a pair of laterally spaced side strips of substantial width and end plates connecting the side strips to form a rectangular frame open at its inner side for communication with the air duct, the outer portions of said side strips diverging outwardly in opposite directions, and a panel unit comprising a plurality of louver strips and connecting end plates with the side strips reof the panel unit, the opposite edges of said panel plate being spaced from said louver plates to define additional air passages.

9. An air distributing outlet for an elongated air supply duct having a projecting collar defining an outlet opening, said outlet comprising a pair of laterally spaced side plates and connecting end plates, the inner edge portions of said side plates being shaped for attachment to the collar of the V supply duct to form an elongated channel communicating with the duct, the outer edge portions 10 of said plates diverging outwardly and laterally, and a panel unit interposed between said side plates and detachably connected thereto, said panel unit comprising spaced parallel side strips and connecting-"end plates, the side strips being spaced from said side plates to form elongated air discharge, passages substantially coextensive with the length of the side plates and communicating at their inner ends with said channel, said panel unit further comprising a central panel having laterally spaced strips forming an air slot between them and spaced from the side strips to form a second set of outwardly and laterally diverging air discharge passages, and a deflector plate overlying said air slot and spaced from the central panel strips to form aspiration passages opening laterally into said second set of discharge passages.

10. An air distributing outlet for an elongated air supply duct havin a projecting collar defining an outlet opening, said outlet comprising a pair of laterally spaced side plates and connecting endplates, the inner edge portions of the side plates being shaped for attachment to the collar of the supply duct to form an elongated channel communicating with the duct and the outer edge portions of said plates diverging outwardly and laterally, and a panel unit interposed between said side plates and detachably connected thereto, said panel unit comprising spaced parallel side strips and connecting end plates, the side strips being spaced from said side plates to form elongated air discharge passages substantially coextensive with the length of the side plates and communicating at their inner ends with said channel, said panel unit further comprising a central face panel having a pair of laterally spaced stationary members Spaced from the side strips to form a second set of outwardly and laterally diverging air discharge passages, and hinged panel members disposed between said stationary members and movable toward and from the latter. v

WALTER W. KENNEDY.

REFERENCES CITED The following, references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,099,452 Schepmoes Nov. 16, 1937 2,102,944 Doane Dec. 21, 1937 2,199,525 Kurth May 7, 1940 2,229,747 Kurth Jan. 28, 1941 2,240,617 Harrigan May 6, 1941 2,282,587 Kurth May 12, 1942 2,337,280 Serre et a1 Dec. 21, 1943 2,380,553 Serre et al July 31, 1945 2,396,025 Seid Mar. 5, 1946 2,407,284 Kennedy Sept. 10, 1946 2,423,241 Kurth July 1, 1947 FOREIGN PATENTS Number Country Date 503,594 Great Britain Apr. 12,1939