MXPA99009536A - Portable germicidal air filter - Google Patents

Abstract

A lightweight portable germicidal air filter (10) for home and personal use is described. The air filter (10) includes a cabinet (12) which houses an electrostatic air filter (28), an ultraviolet lamp (26) and a parabolic reflector (36), or a convex lens (54) for focusing the ultraviolet radiation emitted by the lamp on an upstream side of the air filter. The reflector or the lens are constantly oscillated to systematically sweep the upstream side of the filter with germicidal levels of radiation. A fan (30, 32) located adjacent the downstream side of the filter draws air through the filter and impels it out through areas for air exhaust (20) in the side walls (16) of the cabinet. The advantage is a simple, lightweight germicidal air filter with few moving parts which is inexpensive to manufacture.

Description

PORTABLE GERMICIDA AIR FILTER TECHNICAL FIELD The present invention relates to the removal of particulate matter suspended from the air and, in particular, to the removal of particulate matter from the air by filtering and destroying microorganisms in the particulate matter removed.

BACKGROUND OF THE INVENTION Airborne transmission of pathogenic organisms, especially respiratory pathogens, has long been recognized as a serious problem. Health care authorities and aerobiologists are currently quite aware of the problem due to the evolution of strains resistant to streptococcal antibiotics and tuberculosis, for example. Despite this, the airborne transmission of the disease is not well understood, it is quite clear that many diseases caused by both bacteria and viruses are transmitted mainly from one host to another host by air currents. It is also known that certain infectious agents such as tuberculosis bacteria can survive many hours suspended in the air. Therefore, quarantine people infected with the resistant strains of tuberculosis is sometimes only a partial solution, since the air that contaminates the long run circulates in the space occupied by uninfected people, unless it is a question of eliminating the air and destroying the resistant bacteria. For this purpose, germicidal air filters have been invented. Examples of these filters are described in U.S. Patent 5,330,722 issued July 19, 1994 to W.E. Pick and that was subsequently assigned to the applicant. Although the germicidal air filtration systems described in this patent have proven to be very effective in removing microorganisms from the air and destroying them, the described air filtration systems are mainly adapted to permanent or semi-permanent installations and do not adapt in general. to lightweight portable filters intended for home and / or personal use. Another recently noticed risk of the modern world is the dust tick. Modern houses with airtight seals, central heating and cooling systems, abundant carpets and minimal external air flow provide ideal cropland for dust ticks. These ticks are almost microscopic and can be easily transported through the air. The ticks transported by air are, of course, inhaled, which can cause strong allergic reactions in some people and contribute to lack of comfort for all. With an adequate filtration equipment, especially in the areas of. In addition, dust ticks can be removed from the air and destroyed, thus limiting exposure to airborne ticks, restraining population growth and controlling infestations. A germicidal air filter unit in a sleeping area can contribute to the control of dust ticks. Therefore, an object of the invention is to provide a lightweight germicidal air filter that is portable and can be adapted for domestic and / or personal use. Another object of the invention is to provide a germicidal air filter that requires a minimum number of moving parts. A further object of the invention is to provide a lightweight germicidal air filter that is simple to build and inexpensive in its manufacture.

COMPENDIUM OF THE INVENTION These and other objects of the invention are carried out in a germicidal air filter (10) which includes a filter medium (28) to remove particulate matter including at least a portion of microorganisms of an air stream to be filtered, the medium of the air has one side upward exposed to the air to be filtered, in at least one source of ultraviolet radiation (26) located in proximity to the rising side of the filter medium to expose at least a portion of the ascending side of the filter medium to ultraviolet radiation, one where the filter medium and the ultraviolet radiation source can be displaced with respect to each other in order to systematically expose the rising side of the filter medium to the germicidal levels of ultraviolet radiation, characterized by: the filter medium (28) and the ultraviolet radiation source (26) are mounted stationary in proximity, and a means for focusing (36, 54) the ultraviolet radiation emitted by the ultraviolet radiation source that oscillates on the ultraviolet radiation source so that the radiation is focusing on a predefined area of the filter medium and substantially all the upstream side of the filter medium is systematically irradiated. The germicidal air filter according to the invention preferably includes a cabinet having an air intake area and an air discharge area with a filter medium positioned between the air discharge area, such way that almost all the air has brought through the cabinet passes through the middle of the filter. The filter medium is preferably a flat filter and more preferably an electrostatically enhanced flat filter of the type described, for example, in U.S. Patents 4,978,372 and 4,886,526 issued on December 18, 1990 and on December 12, 1990. December 1989, respectively. The air is preferably moved through the cabinet by means of a fan located adjacent to the downstream side of the filter medium. A source of ultraviolet radiation is located adjacent to the rising side of the filter medium. The ultraviolet radiation source is preferably an ultraviolet lamp which is mounted stationary in proximity to the upstream side of the filter medium. In order to ensure that substantially the entire surface of the filter medium is exposed to radiation levels that are lethal to known microorganisms, it is preferred that a means be provided to focus the radiation emitted by the ultraviolet source, such that the radiation is focused on a predefined area of the filter surface, and the means for focusing the ultraviolet radiation oscillates on the ultraviolet source so that substantially the entire surface of the filter is systematically irradiated with a level of radiation intensity that is lethal to known microorganisms. The approach of ultraviolet radiation can be achieved by means of a parabolic reflector placed behind the bulb or a reflector in combination with an elongated lens placed in front of the bulb, in such a way that substantially all the ultraviolet radiation emitted by the ultraviolet source is focused on a elongated band, relatively narrow, on the rising side of the filter surface. The means for focusing the radiation, for example, a reflector or the elongated lens, oscillates on an axis parallel to the axis of the radiation source by means of an electric motor, for example, which drives an assembly of the cam shaft at a speed predefined to effect the desired irradiation of the rising side of the filter medium. It has been found that the motor preferably rotates the cam shaft assembly at approximately 2 rpm, which produces a sliding of the filter surface every 30 seconds, despite the fact that other oscillation speeds are equally effective. Since the germicidal air filter according to the invention includes very few components and the components are lightweight, it is possible to provide a germicidal air filter that is easily handled and can be used in domestic and / or personal applications as for example in the instead of job .

BRIEF DESCRIPTION OF THE ILLUSTRATIONS The invention will be explained below by means of examples only and with reference to the following illustrations where: Figure 1 is a perspective view of the external part of the cabinet for a portable germicidal air filter according to the invention; Figure 2 is a perspective view of the cabinet shown in Figure 1, with a service door open on the front of the unit showing the preferred position of the ultraviolet source and the filter medium; Figure 3 is a top plan view taken along lines 3-3 of the portable germicidal air filter shown in Figure 1; Figure 4 is a schematic elevated view of the mechanism for oscillating a parabolic reflector or lens to focus the ultraviolet radiation emitted by a source of ultraviolet radiation on the portable germicidal air filter shown in Figure 1. Figures 5a through 5c are cross-sectional views taken along lines 5-5 of the portable germicidal air filter shown in Figure 1, to illustrate the form in which ultraviolet radiation is focused on an ascending side of the filter medium in the portable germicidal air filter; Figure 6, which appears on sheet two of the illustrations, _ shows an alternative arrangement for focusing ultraviolet radiation in which a combination of a lens and a reflector focuses the radiation of the filter medium; and Figure 7 is a wiring diagram suitable for the portable germicidal air filter according to the invention.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a perspective view of the external part of a portable germicidal air filter generally indicated with reference 10. The germicidal air filter 10 includes a cabinet 12 having a front wall 14 and side walls opposite 16. The front wall 14 includes an area for the air intake 18 which may have a perforated shape (as illustrated) or may be covered with a thick open cell plastic foam (not illustrated), or something similar. The area for the air intake allows the air to be filtered to be attracted inside the cabinet. The side walls 16 respectively include areas for air discharge 20 which are preferably covered by a grid but may also be covered by shutters or the like. An upper part of the front wall 14 also includes a control panel 22 which will be explained in more detail with reference to Figure 7. Figure 2 shows the germicidal air filter 10 with a service door 24 in an open condition. The service door forms a substantial part of the front wall 14 and is hinged to a side wall 16 so that it can be conveniently opened to service the interior of the filter. Mounted in the center of the service door 24 is an ultraviolet source 26, preferably an ultraviolet lamp. The ultraviolet lamp 26 can be an ozone generating lamp to facilitate and improve the germicidal effect of the filter. The details of the mechanism for mounting the ultraviolet lamp 26 and for focusing the ultraviolet radiation it emits will be explained later with reference to Figures 3-6. Positioned between the service door 24 and the air discharge areas 20 is an air filter 28, whose construction and operation will also be explained later in more detail. An electric power cable 25 supplies the operating current to the ultraviolet lamp 26 and an engine electric 38 (see Figure 3) from a suitable inductance coil and transformer (see Figure 7) that are housed in a compartment (not shown) in the upper part of the cabinet 12. Figure 3 is a cross-sectional view of the cabinet 12 taken along lines 3-3 of Figure 1. As can be seen, a fan formed by a fan motor 30 and fan blades 32 is mounted on the rear wall 15 of the cabinet 12. The fan blades 32 they are positioned at an inclination, preferably 30 ° -40 °, to pull the air through the air intake area in the front wall 14 of the cabinet 12 and expel the air through the air discharge areas. in the side walls 16 of the cabinet 12. The inclination of the fan blades is preferably in the range of 30 ° - 40 ° because this inclination is more effective in moving the air through the cabinet with the lower generation of noise In this inclination, the fan blades drive the air laterally through the air discharge areas 20 and the resulting vacuum pulls the air through the air intake 18. Therefore, the air is pulled through the air. air filter 28 which is preferably an electrostatic air filter of the loaded media type known in the art and described, for example, in the Patent of the United States 4,886,526 which was issued on December 12, 1989. The air filter 28 can be serviced by disassembling the filter of the cabinet 12 through the service door 24. After the air filter is removed from the cabinet 12 , the service is carried out in a manner known in the art and described for example in the Patent! of the United States 4,886,526. The only improvements to the filter 28 described in this patent are several modifications to ensure that ultraviolet radiation is not reflected back out of the filter cabinet through the air intake area 18 (see Figure 1). To reduce reflection, the structure of the aluminum filter is painted matt black, as is the external screen on the upstream side of the filter 28. Furthermore, the fiber filter medium is preferably manufactured from a fiberglass pad painted with black with the addition of carbon black to the glass mixture. It has been discovered that other dyes are unstable and transient when exposed to ultraviolet radiation. The interior of the cabinet 12 between the service door 24 and the filter 28 (see Figure 2) are preferably painted in the same way as matt black to reduce reflection. A pair of support brackets 34 mount the ultraviolet lamp 26 in the center of the service door 24.

Only the lower bracket 34 is illustrated in Figure 3 for clarity. When the service door 24 is in a closed position, the distance from the ultraviolet lamp 26 to the rising side of the filter 28 is preferably about 2.65"(6.73 cm.) The rising side of the filter medium is preferably about 10 inches. "(25.4 cm) wide and the cabinet is approximately 12" (30.48 cm) wide Given these dimensions, the distance from the ultraviolet lamp 26 to any of the outer edges of the rising side of the filter 28 is approximately 5.88" (14.94 cm). A single ultraviolet lamp 26 is not suitable for irradiating the entire filter surface at germicidal levels. In order to conserve weight, manufacture and maintenance costs, however, and to ensure that unacceptable levels of radiation do not escape outside the cabinet 12, it is preferable that the unit include only one ultraviolet lamp 26. A mechanism to focus the radiation from the lamp towards a predefined area on the rising side of the filter 28 is convenient for this reason. The preferred mechanism for focusing the ultraviolet radiation is a parabolic reflector 36 that oscillates on the lamp 26 to systematically pass the focused radiation through the rising side of the filter 28. The oscillation of the reflector The parabolic circuit is preferably achieved by means of a 24 volt double coil gear reduction motor 38 well known in the art which activates a compensating circuit 40. The compensating circuit 40 in turn moves an assembly of the cam shaft 42 which it has a first arm connected to the compensator circuit 40 and a second arm connected to an axis that supports the parabolic reflector 36 as will be explained in more detail with reference to the Figure. Figure 4 shows an elevated view of the preferred mechanism for oscillating the parabolic reflector 36. The ultraviolet lamp 26 is preferably stationary and is connected to the plugs of the lamp 44. Each plug of the lamp 44 is supported by a bracket in the form of U 46 which is fixed to the respective support brackets 34 which are mounted to the center of the inner side of the service door 24. Mounted under each U-shaped bracket 46 is a bearing 48 which accepts an adapter shaft 49 which supports to a reflector support bracket 50 attached to the opposite ends of the parabolic reflector 36. At the upper end of the reflector 36, an adapter shaft 49 interconnects the reflector support bracket 50 with the cam shaft assembly 42 that at its once it is connected to the compensator circuit 40 of the gear reduction motor 38. As the gear reduction motor, this turns the compensating circuit 40 preferably to approximately 2 revolutions per minute. The rotation of the compensating circuit causes the assembly of the axis of the cam 42 to oscillate the parabolic reflector 36 which passes the focused radiation through the rising side of the filter 28 as can be seen in Figures 5a-c. Figures 5a-c are cross-sectional views taken along lines 5-5 of Figure 1. The parabolic reflector is preferably made of metal foil of an aluminum alloy having a bright polished side to increase reflection. This metal sheet is available for example, at Ideal Metal in Toronto, Canada, and is identified as Aluminum Bright (1100-H24). The metal sheet is usually rolled into the desired shape using techniques well known in the art. The focal length of the parabolic reflector 36 is preferably such that the radiation emitted by the ultraviolet lamp 26 is more concentrated when the radiation is focused on the edges of the rising side of the air filter 28, such that the germicidal effect on the side The ascending air filter is as consistent as possible. In the preferred embodiment shown in Figures 5a-c, the focal length of the parabolic reflector 36 is therefore preferably approximately 5.88"(14.94 cm) As the parabolic reflector 36 oscillates in such a way that the ray passes through the center of the filter (see Figure 5b), it is apparent that the radiation is less focused on the rising side of the medium of the filter 28, but since the force of the radiation is inversely proportional to the distance of the source, the same germicidal effect is achieved over a larger area, in this way, as the oscillation completes a path as shown in FIG. Figure 5c the radiation is focused more as the distance from the ultraviolet lamp increases, until the focus is more intense at the outer edge of the rising surface of the filter medium.The persons skilled in the art will understand that the oscillation of the reflector Parabolic 36 also has a beneficial effect by constantly changing the angle of incidence of the ultraviolet radiation on the rising side of the air filter 28. This pro it moves a deeper penetration of the radiation into the middle of the air filter and has to eliminate the shaded areas where bacteria, viruses or other organisms transported by the air can survive. Figure 6 shows an alternative arrangement for focusing the ultraviolet radiation emitted by the ultraviolet lamp 26. In this embodiment, a reflector 52, which is not "a focused parabolic reflector, reflects the ultraviolet radiation on a convex lens 54 which focuses the ultraviolet radiation in a very similar way as the parabolic reflector 36. The lens 54 is preferably a plastic lens made with, for example, acrylate plastic (ROP-4), available in Cyro Industries of Mount Arlington, New Jersey, USA Plastic for lens 54 is preferred because it is lightweight and fracture-proof. Acrylate plastic is preferred because it is resistant to the effects of ultraviolet radiation and most of the ultraviolet radiation passes through it. The lens 54 is preferably designed to have a focal length such that the radiation emitted by the ultraviolet lamp 26 is more concentrated when the radiation is focused at the edges of the rising side of the air filter 28. In the preferred embodiment shown in FIG. Figures 5a-5c, the focal length of the lens 54 is therefore preferably about 5.88"(14.94 cm). Although it is obvious that the lens 54 protects the ultraviolet lamp 26 from exposure to suspended dust particles In the air to be filtered, it should be noted that the shape of the parabolic reflector 36 also protects the ultraviolet lamp 26 from exposure to dust particles suspended in the air to be filtered as the air is pulled around the reflector 34. , the form of The reflector creates a substantially static vacuum around the ultraviolet lamp 26, which inhibits the dust particles suspended in the air to be filtered to prevent them from coming into contact with the ultraviolet lamp and therefore tends to keep the lamp clean. Figure 7 is a wiring diagram suitable for wiring the germicidal air filter 10 according to the invention. A three-pronged power plug 54 is connected to a power cable 56 that usually supplies an input current of 120 VAC. A ground conductor of the power cable 56 is connected to ground 58 and a power conductor 55 of the power cable 56 is disconnected by means of a fuse 60 to protect the circuit against overload. An interlock switch 62 which is operatively associated with the service door 24 disconnects the power conductor 55 from the supply cable 56 in such a way that the unit stops when the service door 24 (see Figure 2) opens with In order to protect people in the surroundings from exposure to ultraviolet radiation. A conductor 63 connects the power conductor 55 of the power cable 56 to a double speed fan motor switch 64 that is mounted on the control panel 22 (see Figure 1). The fan motor switch double speed 64 controls the operation of the fan motor 30 and supplies power to the high voltage electronic system 66 which activates the charged medium type electrostatic air filter 28 in a manner well known in the art. Each pole of the double speed fan switch 64 is connected to a conductor 65 to supply power to a transformer 68. The return conductor of the transformer 68 is connected to the return conductor 57 of the supply cable 56 by means of a lead 67. The high voltage electronic system 66 requires AC current exiting the transformer 68. The power conductor 55 of the power cable 56 is likewise connected to a lamp and an oscillation motor switch 70 which allows the ultraviolet radiation of the Filter medium is controlled independently from fan operation and electrostatic filter, if desired. The switch 70 is optional but is preferred in such a way that the ultraviolet unit can be controlled without opening the service door 24 or disconnecting the power cable 56. The independent operation of the fan / filter and the ultraviolet lamp oscillator also allows the irradiation of the filter medium 28 continues for a minute or two after the fan is stopped, to ensure that any live microorganism from the filter medium 28 is destroyed before servicing the filter. This feature is important if the filter is used in an environment where microorganisms resistant to antibiotics are known to be present. An inductance coil 74 is connected to the lamp and to the oscillation motor switch 70 by means of a conductor 72, which is likewise connected by means of a conductor 73 to the return conductor 57 of the supply cable 56. inductance coil 74 transforms the 120 volt AC input to a suitable voltage to activate the ultraviolet lamp 26. Also connected to the lamp and the oscillation motor switch 70 by means of a conductor 75, there is a transformer 76 which is also connected to the return conductor 57 of the power cable 56. The transformer 76 outputs an AC voltage of 24 volts to activate the gear reduction motor of the double coil 38. The transformer 68, the inductance coil 74 and the transformer 76 are preferably mounted in a bottom wall of a compartment (not shown) in the cabinet 12 located on the filter 28 and behind the control panel 22 (co nsultate Figure 2). The persons skilled in the art will understand that this wiring diagram is only an example and that they can also operate other wiring arrangements in the same way. The efficiency of germicidal air filters has been tested in a 70 cubic foot test chamber filled with ambient air as described in U.S. Patent 5,330,772. In this test, a petri dish containing agar agar was exposed to air in the test chamber to collect a control sample of bacteria suspended in the chamber air prior to activation of the germicidal air filter installed in the chamber. proof. The temperature in the test chamber was 65 ° F and the relative humidity was 50% at the time of testing. After the control sample was taken, the germicidal air filter was operated for a period of 5 minutes. The air flow through the filter was approximately 250 cubic feet per minute. After 5 minutes of operation, an identical petri dish containing agar agar was exposed to air in the chamber using the same procedure used for the control sample, and both petri dishes were incubated to determine bacteria containing particle counts before and after the filtration. Approximately 65 particles containing bacteria were collected in the control sample. In the test sample taken after five minutes of operation, no particles containing bacteria were collected. As far as the culture method was able to test the presence of bacteria transported by air, the test chamber was completely free of these bacteria. Therefore, it is apparent that germicidal air filters are very effective in eliminating and destroying at least a portion of microorganisms suspended in the air.

INDUSTRIAL APPLICABILITY A light weight, simple germicidal air filter is provided, suitable for domestic and / or personal use. The filter removes at least a part of the microorganisms suspended in the filtered air and destroys those microorganisms with ultraviolet radiation that is systematically focused to germicidal levels on an ascending side of the filter medium. It is known that these filters are effective against microorganisms including bacteria, and microscopic insects such as, for example, dust ticks and the like. The germicidal air filter according to the invention therefore contributes to the comfort and safety of people, and offers a portable unit suitable for domestic and personal use that can be manufactured at an affordable price.

The construction of the preferred embodiment described above is intended to work only as an example. Despite those described with reference to portable electrostatic air filters, the invention is not limited to portable applications, nor to electrostatically enhanced filter media. The invention can be adapted to permanent installations in air handling systems, or filtration units hung on the roof or with large walls. It can also be adapted for use with passive filter media. Variations, modifications and alterations may be apparent to those skilled in the art. It is intended that the scope of the invention be limited only by the scope of the appended claims.

Claims (14)

1. CLAIMS 1. A germicidal air filter (10) including a filter means (28) for removing particulate matter including at least a portion of microorganisms from the air stream to be filtered, where the filter medium possesses a ascending side exposed to the air to be filtered, in at least one ultraviolet radiation source (26) located in proximity to the upstream side of the filter medium to expose at least a part of the rising side of the filter medium to the radiation ultraviolet, where one of the filter media and the ultraviolet radiation source can be displaced with respect to each other in order to systematically expose the rising side of the filter medium to germicidal levels of ultraviolet radiation, characterized in that: the filter medium (28) ) and the source of ultraviolet radiation (26) are mounted stationary in proximity and a means for focusing (36, 54) the ultraviolet radiation emitted by the fu The ultraviolet radiation element oscillates on the ultraviolet radiation source in such a way that the radiation is focused on a predefined area of the filter medium and substantially the entire ascending side of the filter medium is systematically irradiated.
2. 2. A germicidal air filter as indicated in claim 1, wherein the means for focusing the ultraviolet radiation emitted by the ultraviolet radiation source includes a parabolic reflector (36) that focuses the ultraviolet radiation in a narrow narrow band on the filter medium. -
3. 3. A germicidal air filter as set forth in claim 1, wherein the means for focusing the ultraviolet radiation are a reflector (52) and an elongated lens (54) that focuses the ultraviolet radiation on an elongated band on the medium of the filter.
4. 4. A germicidal air filter as set forth in claim 2 or 3, wherein the means for oscillating the reflector (36, 52) is a gear reduction motor and a cam assembly for oscillating the reflector on an axis in such a way that the ascending side of the filter medium is systematically exposed to the focused ultraviolet radiation.
5. 5. A germicidal air filter as set forth in any of the preceding claims, wherein the filter medium is a fibrous filter medium.
6. 6. A germicidal air filter as set forth in claim 5, wherein the medium of the fibrous filter is a folded paper medium suitable for use in air filtration.
7. 7. A germicidal air filter as set forth in claim 5, wherein the fibrous filter medium is a glass fiber medium suitable for use in air filtration. A germicidal air filter as set forth in claims 5, 6 or 7 wherein the medium of the fibrous filter is electrostatically enhanced in such a way that the filter fibers are polarized by an electrostatic field to increase the efficiency of the filter medium by capturing particulate matter suspended in the air to be filtered. 9. A germicidal air filter as set forth in claim 8, wherein the medium of the fibrous filter is impregnated with carbon black to reduce reflection of the ultraviolet radiation from the upstream side of the filter medium. 10. A germicidal air filter as set forth in any of the preceding claims, wherein the source of radiation is an ultraviolet lamp. 11. A germicidal air filter as set forth in any of the preceding claims, wherein the filter medium (28), the ultraviolet radiation source (26) and the focusing means (36, 54) the ultraviolet radiation emitted by the source of ultraviolet radiation, are mounted inside of a cabinet (12) having at least one air intake area (18) and at least one area for air discharge (20). 12. A germicidal air filter as set forth in claim 11, wherein at least one area for the air intake includes an access door for the service (24) that has a front panel that has the form of a blind to admit air. 13. A germicidal air filter as set forth in claim 11, wherein at least one area of the air discharge includes a grid in each side wall of the cabinet. 14. A germicidal air filter as set forth in claims 11, 12 or 13, wherein the rising side of the filter medium includes a structure surrounding the filter medium and a loading screen that covers the middle of the attached fibrous filter. to the structure, the structure, the loading screen and an inner part of the ascending part of the cabinet of the middle of the filter, painted matt black to reduce the reflection of ultraviolet radiation.