US3255686A

US3255686A - Door air screen

Info

Publication number: US3255686A
Application number: US337942A
Authority: US
Inventors: Larson Eugene; London Stuart Paul
Original assignee: NAT IND EQUIPMENT CO
Current assignee: NAT IND EQUIPMENT CO; NATIONAL INDUSTRIAL EQUIPMENT Co
Priority date: 1964-01-15
Filing date: 1964-01-15
Publication date: 1966-06-14
Anticipated expiration: 1983-06-14

Description

June 14', 1966 E. LARSON ETAL DOOR AIR SCREEN Filed Jan, 15, 1964 INVENTOR5 EUGENE 4/7250 5704.?7' PAUL 40/1/00 W X/VM free/W976 United States Patent DUOR AIR SCREEN Eugene Larson, Milibrae, and Stuart Paul London, San

Carlos, Califi, assiguors to National Industrial Equipment Co., a corporation Filed .lan. 15, 1964, Ser. No. 337,942 3 Claims. ((11. 9836) Our invention relates to an improved version of a device adapted to be mounted over a doorway and effective to blow air downwardly over the doorway opening in order to prevent the ingress of insects and debris from outside and to permit the passage of people and goods through the doorway, all without requiring the use of a door panel. A related device is shown in Patent 3,086,441.

In previous installations of door air screens, it has been observed that, without having a high velocity air stream, it is difficult to arrange the flow of air in such a way as to ensure that insects and the like flying from the outside cannot penetrate the doorway. In the event only goods are to go through the doorway, then a high velocity-air stream is not objectionable, but in the event people pass through the doorway, the velocity of the stream must be limited to an amount which is not unpleasant to the doorway users.

Also, and particularly where retail work is carried on as distinguished from wholesale shipping and the like, the noise level of the apparatus and the kinds of noise generated by the apparatus are of considerable importance.

White noise and some high pitched noises as given off :by some devices are annoying to customers and do not make the entranceway or doorway inviting.

It is therefore an object of the invention to provide a 8 door air screen arranged in such a way as to afford a relatively large volume of low velocity air, relatively, so that external penetration by insects and the like is precluded, yet use of the doorway by customers is pleasant.

Another object of the invention is to provide a door air screen in which means are provided for varying the flow of the air stream from the screen not only longitudinally of the doorway, but also transversely thereof in order that the air flow pattern can be made most effective and least unpleasant for the particular installation.

Another object of the invention is to provide a relatively simple and straightforward door air screen in which many of the sounds arising in-the motor and fan mechanism are not readily amplified, but, on the contrary, are damped and suppressed so that the operating noise level of the structure and the nature of the emitted sound are satisfactory and not obtrusive.

Another object of the invention is to provide a door air screen which can simply and easily be manufactured and serviced.

Another object of the invention is in general to provide an improved door air screen.

Other objects together with the foregoing are attained in the embodiment of the invention described in the ac companying description and illustrated in the accompanying drawings, in which:

FIGUREl is a side elevation of a door air screen in a typical installation on the exterior of a doorway, portions of the doorway being shown in cross section;

FIGURE 2 is a front elevation of the door air screen shown in FIGURE 1;

FIGURE 3 is a crosssection on a transverse vertical plane through the door air screen of the invention;

FIGURE 4 is a cross section similar to FIGURE 3 but taken on a vertical longitudinal plane through the door air screen;

FIGURE 5 is a detail in plan of some of the hexagonal I cellular material used in the lateral deflector panels; and FIGURE 6 is a detail showing in elevation from below the appearance of a means for rigidly joining the shrouds. While the door air screen can be incorporated in a number of different ways, it is typically embodied as shown herein for use on a vertical, planar wall 4 having 1 pair of vertical side panels 19 and 21. These panels are all generally planar and are arranged to form a rectangular enclosure entirely open at the top and at the bottom. The housing is mounted on the wall by fastenings 5 on the rear panel 18.

Within the housing so formed and extending generally horizontally therein is a diaphragm plate 22. This is usually fabricated of light metal and is appropriately secured in place, for example by spot welding or the like. The diaphragm plate 22 extends entirely between the side panels 19 and 21 and entirely between the front and rear panels 17 and 18 so as to define an upper compartment 23 and a distinct lower compartment 24 within the housing. The diaphragm plate is provided with a pair of

circular openings

26 and 27 affording communication between the upper and lower compartments 23 and 24. The circular openings are each bounded by one of a pair .of

shrouds

28 and 29. These conveniently are circular cylindrical flanges secured to the diaphragm plate 22 and depending for a substantial distance into the compartment 24.

Spanning the interior of the upper compartment 23 and overlying the

openings

26 and 27 are

support beams

31 and 32 preferably in the form of channels disposed with their Webs uppermost and their flanges depending downwardly. In some instances, the support beams are formed integrally with the diaphragm plate 22. When the support beams are separate members, it is preferred to fasten them and thediaphragm plate together quite rigidly so that they do not move or vibrate relatively to each other, but rather serve as stiffening reinforcements for each other. At appropriate intervals, the

beams

31 and 32 are provided with fastenings 33 which pass through and are secured to the diaphragm plate.

As an additional means for affording beam strength and for imparting considerable additional rigidity to the diaphragm plate assembly, we especially provide a connector 34 secured to the adjacent portions of the lower margin of the

shrouds

28 and 29. In effect, the

beams

31 and 32, the diaphragm plate 22 and the deeply extending circular cylindrical shrouds 28 and 29' are joined by the connector 34 to afford a beam structure virtually of the rigidity of a single beam having the same depth as the vertical dimension of the

beams

31 and 32 and together with the verticaldimension of the

shrouds

28 and 29.

An extremely stiff support is thus afforded for a pair of

electric motors

41 and 42, each resting upon and being fastened to the

beams

31 and 32 by appropriate fastening bolts 43. Each of the motors has one of a pair of depending shafts 44 and 46 centralized with respect to the

openings

26 and 27 and serving as a drive and support for the respective one of a pair of

fans

47 and 48 disposed within the .

individual shrouds

28 and 29. Preferably, the

motors

41 and 42 are both driven in the same direction of rotation, so that the

fans

47 and 48 are identical. The fans when operated are effective to blow an air current through the housing from the upper open end thereof and outwardly and downwardly through the lower open end thereof. If the downward air currents are simply left to impinge upon the generally horizontal floor 12, they tend to eddy and flow in various directions including directions having substantial components toward the doorway 6. Insects, such as flies, which appear in some portion of the downward stream are then actually carried into and through the doorway rather than being kept outside thereof.

To obviate this effect, the housing is preferably provided with a pair of

panels

51 and 52. These are substantially alike. Each panel is a rectangular structure comprised of a plurality of hexagonal cells 53. Customarily, these are formed of stiff paper or thin aluminum or comparable material and serve as means for channeling and directing the helically and vortically swirling air discharged by the fans into a homogeneous parallel flow with a major downward component and only slight eddies. The fact that the two

fans

47 and 48 may operate in the same or opposite directions is not important since the eddies from the vortical flow of the air discharged by the fans are straightened and cancelled by the hexagonal panel materials. The air flow below the panels is practically rectilinear.

The reduction of eddy currents is best accomplished by locating the

panels

51 and 52 quite close to the

fans

47 and 48 but not so close as to induce any sound or siren effects. This easily can be accomplished in substantially the way illustrated in FIGURES 3 and 4. Preferably, the

panels

51 and 52 at their adjacent portions rest on flange projections 54 at the bottom of the housing and also rest upon adjusting screws 56 passing through lips 57 projecting inwardly into the housing. When the screws 56 are appropriately adjusted, the

panels

51 and 52 are preferably both inclined to form a dihedral angle so that there is a direction or component given to the air transversely or laterally of the doorway opening 6 and generally parallel to the plane of the wall 4. Thus, air flowing downwardly and having passed through the

panels

51 and 52 and impinging upon the planar floor 12 has flow components directed outwardly or away from the doorway in lateral directions and thus tends to repel any otherwise inflowing material.

The air flow is likewise controlled by a plurality of louvers 61. Each of these is conveniently made of a metal envelope having a stream-lined or airfoil cross section and is mounted at its opposite ends on securing

pivots

62 and 63 in 21 depending collar frame 64 detachably secured to the housing 16. The louvers 61 are substantially in abutment at their ends with friction washers 65 so that the louvers can readily be oriented or directed about the pivotal axes of

thefastenings

62 and 63 and can be pointed more or less outwardly of the doorway. When the louvers have been properly adjusted during installation, the

fastenings

62 and 63 are secured and the louvers are then frictionally held in an inclined attitude. The collar frame at its forward and rearward walls is augmented by

guide plates

66 and 67 so that between the respective guide plates and the adjacent louvers appropriate venturi-form throats are afforded. The louvers 61 are set more or less at an inclination to the vertical in such a way that downflowing air does not impinge upon the floor 12 perpendicularly.

4 Rather, the air stream is given an outward horizontal or repelling component so that upon approaching or striking the floor the air flow is outwardly and thus repels insects or debris which might tend otherwise to travel inwardly of the air screen.

In the operation of the device, the air is sometimes inducted into the housing without any baflle or screen, but in most instances it is preferred to provide a framework 68 around the upper margins of the housing in order that one or more filter plates 69 can movably be positioned therein. The filters are not intended to exclude all particles, but are merely to restrain larger items which might tend to clog the

panels

51 and 52. The filters also have an acoustic effect, as does the hexagonal

cellular panelling

51 and 52, tending to prevent the spread of sound. The incoming air passes over and tends to cool the motors and then flows through the

fans

47 and 48. The air flow is relatively quiet and the operation of the motors is likewise quiet since it has been found that by connecting the entire structure together quite rigidly and especially by joining the shrouds by the connector 34 to provide a deep beam, the period of vibration is reduced substantially to a subsonic level or at least to pleasant frequencies. The sound is not at high, annoying frequencies which are easily amplifiied and disseminated by relatively free, sheet metal parts.

The air flowing from the fans traverses the

cellular panels

51 and 52. This not only affords a rectilinear flow in a downward direction, but also substantially cancels eddy currents. This itself tends markedly to reduce the noise. Further reduction is caused by some absorption by the cellular material, particularly if it is paper. The

inclined panels

51 and 52 impart transverse components to the air, following which the air then passes between the louvers 61 imparting an outward component to the air. The resulting air blast in striking the floor tends to spread out or diverge outwardly. Thus insects, such as flies, are incapable of penetrating the downwardly flowing current, although the velocity thereof is not so great as to interfer with or become unpleasant to customers. While insects flying into the curtain may have sufficient velocity to penerate part way, yet the thickness and width of the curtain are so great that before the insects can penetrate into the interior and through the doorway, they are forced downwardly toward and against the floor 12 and then blown outwardly away therefrom. A person passing through the doorway 6 and being subjected to the downwardly flowing relatively broad curtain of air does not have any disturbing impingement since the velocity of the flow is relatively low over a relatively long and wide area.

The net result of the structure, therefore, is to provide a door air screen which operates quietly and effectively to keep out flying insects, debris and rubbish from the outside, yet is not unpleasant for the passage of people through the doorway 6 in either direction.

What is claimed is:

1. A door air screen for use on'a wall over a doorway comprising a housing having a vertical front panel, a vertical rear panel, a pair of vertical side panels and being open at the top and bottom, means for securing said rear panel to said wall, a diaphragm plate extending horizontally entirely across said housing and dividing said housing into an upper compartment and a lower compartment, said diaphragm plate having a pair of circular openings therein affording communication between said upper compartment and said lower compartment, means on said diaphragm plate cylindrical shrouds around said openings and depending into said lower compartment, supports extending across said housing and spanning said openings, means for rigidly uniting said diaphragm plate and said supports, electric motors within said upper compartment and rigidly secured to said supports, fans mounted on said motors and disposed within said shrouds, means for joining adjacent depending portions of said shrouds, a

pair of panels extending across and supported in said lower compartment, each being disposed beneath one of said fans and each defining vertical air directing passage Ways, means for supporting said panels in said housing at a variable lateral inclination, a plurality of louvers in said lower compartment beneath said anels, and means for supporting said louvers in said housing at variable longitudinal inclination.

2. A door air screen as in claim 1 in which said panels are comprised of hexagonal cellular material forming vertical air directing passageways.

3. A door air screen as in claim 1 in which said diaphragm plate, said supports, said shrouds and said means for joining adjacent depending portions of said shrouds are rigidly connected to form a stiff beam support for said motors and said fans.

References Cited by the Examiner UNITED STATES PATENTS ROBERT A. OLEARY, Primary Examiner.

JOHN F. OCONNOR, Examiner.

Claims

1. A DOOR AIR SCREEN FOR USE ON A WALL OVER A DOORWAY COMPRISING A HOUSING HAVING A VERTICAL FRONT PANEL, A VERTICAL REAR PANEL, A PAIR OF VERTICAL SIDE PANELS AND BEING OPEN AT THE TOP AN BOTTOM, MEANS FOR SECURING SAID REAR PANEL TO SAID SIDE WALL, A DIAPHRAGM PLATE EXTENDING HORIZONTALLY ENTIRELY ACROSS SAID HOUSING AND DIVIDING SAID HOUSING INTO AN UPPER COMPARTMENT AND A LOWER COMPARTMENT, SAID DIAPHRAGM PLATE HAVING A PAIR OF CIRCULAR OPENINGS THEREIN AFFORDING COMMUNICATION BETWEEN SAID UPPER COMPARTMENT AND SAID LOWER COMPARTMENT, MEANS ON SAID DIAPHRAGM PLATE CYLINDRICAL SHROUDS AROUND SAID OPENINGS AND DEPENDING INTO SAID LOWER COMPARTMENT, SUPPORTS EXTENDING INTO SAID HOUSING AND SPANNING SAID OPENINGS, MEANS FOR RIGIDLY UNITING SAID DIAPHRAGM PLATE AND SAID SUPPORTS, ELECTRIC MOTORS WITHIN SAID UPPER COMPARTMENT AND RIGIDLY SECURED TO SAID SUPPORTS, FANS MOUNTED ON SAID MOTORS AND DISPOSED WITHIN SAID SHOURDS, MEANS FOR JOINING ADJACENT DEPENDING PORTIONS OF SAID SHROUDS, A PAIR OF PANELS EXTENDING ACROSS AND SUPPORTED IN SAID LOWER COMPARTMENT, EACH BEING DISPOSED BENEATH ONE OF SAID FANS AND EACH DEFINING VERTICAL AIR DIRECTING PASSAGEWAYS, MEANS FOR SUPPORTING SAID PANELS IN SAID HOUSING AT A VARIABLE LATERAL INCLINATION, A PLURALITY OF LOUVERS IN SAID LOWER COMPARTMENT BENEATH SAID PANELS, AND MEANS FOR SUPPORTING SAID LOUVERS IN SAID HOUSING AT VARIABLE LONGITUDINAL INCLINATION.