Patent Application
20090129974
The present invention relates to a ceiling paddle fan fixture for improving the quality of the air in the room and to various methods of enhancing room air quality. The present invention finds particular application in public spaces such as hospitals, health care institutions, dormitories, schools and offices.
Ceiling paddle fans are quiet, efficient and high volume air mixers and are well known and often used both indoors and outdoors. The large slowly rotating blades are designed to move large volumes of air at a relatively slow speed, creating a cooling effect by causing more rapid evaporation of perspiration. Indoors, they are often used as a less expensive alternative (or supplement) to air conditioning. Outdoors, they are often used on porches, verandas and patios to supplement natural breezes.
The blades of paddle fans are typically slanted at an angle of about 10° to 15° from the horizontal on the leading edge—i.e., when operated in a clockwise direction, the blades will cause a generally horizontal and downward flow of air. This causes evaporation and a general sensation of cooling. Conversely, if the blades are operated in a counterclockwise direction, air will tend to be pulled up vertically and then redistributed in a downward direction. If used in this manner, the fans may help to redirect heated air back into the lower room which would be useful in colder months. In addition, operation in a way that pulls air upward will move recently generated germs from proximity of those generating them immediately through the UV-C field and thus tend to effect sterilization before the contaminated air is circulated to others in the room.
Paddle fans can typically be operated at a range of revolutions (typically three speeds) which enables the user to control drafts. Because of their potential to circulate air and reduce energy consumption, paddle fans have been widely adopted.
In recent years, a much broader selection of ceiling fans has become available with less emphasis on function and price and more emphasis on design and aesthetic considerations. “Light kits” are often added to ceiling paddle fans to increase utility and energy-efficient models feature angled paddle blades and two-way fluorescent lighting (up, down or both). Some state governments are now specifying energy standards for paddle ceiling fans—e.g., they may use only fluorescent sockets, energy efficient motors, etc.
As disclosed in applicant's co-pending application Ser. No. 11/823,507 filed Jun. 28, 2007, the entire disclosure of which is hereby incorporated by reference herein, the use of short wave ultra violet (“UV-C”) sources for the sterilization of air is well known. The usefulness of UV-C irradiation on air quality lies in the effect on germs (microorganisms) transmitted in aerosolized form. Such infectious germs are generally less than 0.3 microns in diameter and are suspended or “float” in the air.
Different types of microorganisms vary significantly in their resistance to UV-C irradiation. For example, spores such as anthrax have a “cell wall” (like bacteria) as well as an outer “shell” which must be penetrated by the UV-C energy. Viruses such as influenza, the common cold, SARS, measles and small pox do not have a cell wall and are about five times more susceptible to UV-C radiation than spores. Bacteria with a cell wall such as tuberculosis, even extended drug resistant (XDR) TB, may be ten times more vulnerable to UV-C radiation than anthrax spores. The UV-C “dose” needed to destroy germs is generally expressed as joules (one UV-C watt of energy for one second) per square meter; or the equivalent γj/cm2—micro-joules per square centimeter.
It is desirable to effect air sterilization within the room where the germs originate. However, there are safety issues. Keratoconjunctivitis (external inflammation of the eye) and erythmea (reddening of the skin) can result from overexposure to UV-C and the National Institutes for Occupational Safety and Health (NIOSH) recommends an upper limit on the amount of UV-C radiation for the safety of personnel in the room, i.e., 6 m j/cm2—6 micro-joules per square centimeter over a continuous eight-hour period. Although they may be modified from time to time, the NIOSH guidelines must be considered in the design of fixtures for public spaces and home use.
Because of safety considerations, air sterilization products (e.g., in-duct, ceiling and floor mounted fixtures) generally avoid UV-C radiation into a room and have attempted to confine UV-C radiation to the interior of a closed (i.e., UV-C baffled) chamber, and pass air through the baffled chamber for sterilization.
Initial efforts to effect air sterilization with a UV-C field external of the fixture transmitted an intense UV-C beam at a room height well above the “eye level” of people occupying the room, i.e., generally considered to be approximately 60 inches above the floor. Germ reduction occurred in the air passing through the beam as a result of convection currents and ventilation systems. While the intensity of the beam was effective in sterilizing the air passing through the beam, the volume and velocity of the air passing through the beam was not controlled and, being thus subject to external forces, such devices have generally been ineffective. In addition, the narrowing of the beam vertically, typically through the use of louvers, wasted most of the UV-C energy making such fixtures highly inefficient.
Experiments have been conducted with high intensity UV-C sources in which the amount of room air passing through the field of UV-C radiation is increased by the use of independent air movers such as floor fans. Such air movers serve to stir or mix the air in the room, combining treated air with untreated air, so that mixed air is circulated back through the UV-C killing field. Experimental data suggest that such systems are much more effective in reducing the concentration of microorganisms in the room than conventional “beam” sterilizers.
It has been proposed to combine the air sterilization and air movement features needed to effectively sterilize air. One such proposal was for a ceiling mounted, squirrel cage motor driven, impeller with a high intensity UV-C array located circumferentially around the impeller so that air drawn upwardly into the impeller could be laterally exhausted by the UV-C array into the room. Such device proved impractical because of its large size, interference with air flow by the motor and the baffling required to avoid an unacceptable radiation level in the lower part of the room.
More recently, applicant's co-pending application discloses an improved ceiling device of much smaller size that uses a low intensity source with easily replaced arcuate UV-C bulbs. Such devices rely on a relatively concentrated centralized air intake and the mixing of treated with untreated air by the exhaustion of treated air along the ceiling and are particularly suitable for rooms with relatively low ceilings.
This application is directed to the combination of a UV-C source and an air mover in a single fixture which uses a low intensity UV-C source and a paddle ceiling fan to significantly increase the mixing of the treated with the untreated room air. Sterilization of room air is achieved by the passage of a high volume of air at a relatively slow speed through a relatively low intensity UV-C field. Thus, the novel paddle ceiling fan fixture of the present invention provides room lighting, air circulation and safe and effective room air sterilization.
In one aspect, this invention relates to a ceiling fan fixture that utilizes movable sources of radiation in providing effective room air sterilization.
In another aspect, this invention relates to a ceiling fan fixture having a diffused source of radiation for effective room air sterilization.
In still another aspect, this invention relates to the establishment of a UV-C radiation field by directing radiation across the upper surface of the paddle blades.
In yet another aspect, the intensity of the UV-C radiation may be varied independently of, or as a function of, air flow to match the amount of room air mixing. The UV-C source may also be automatically varied as a function of the presence of persons or objects in an area of the room above eye level.
In a further aspect, the fixture of the present invention is fully integrated with smoke and carbon monoxide detection to provide a holistic safety approach for germ killing, alarms and emergency back up lighting.
In yet a further aspect, the fixture of the present invention may originate the UV-C field from within the canopy from which the paddle fan is suspended.
The present invention aims to enable common paddle-type ceiling fans to incorporate UV-C air sterilization as a countermeasure to deadly aerosolized infectious diseases like influenza, tuberculosis, and SARS, as well as biological weapons such as anthrax and small pox. By combining UV-C radiation with ceiling paddle fans, it will be possible to equip schools, government buildings, military barracks, dormitories, assisted living centers, hospitals and health care facilities with sufficient air sterilization potential to address a broad range of emergencies and health crises.
Many other objects and advantages will be apparent from the following detailed description of preferred embodiments when read in conjunction with the appended drawings.
As shown in
In the embodiment of
With reference to
The UV-C lamps 28 are desirably located along the upper edge of the rotor unit 16 so that the rotor unit defines the lower edge of the opening 27 and prevents the downward emission of direct UV-C radiation into the lower part of the room. The upper end of the opening 27 is defined by the UV-C absorbing cover 34 of the upper illumination assembly 26. The angle α through which direct UV-C radiation may exit the opening 27 is between about 10 and about 45 degrees. The upward limitation of the angle α limits the indirect radiation of the lower part of the room by reflection of direct radiation by the ceiling.
So that visible room light is controlled solely as a function of the control of the source 32, the source 28 of UV-C radiation may be provided with a filter for visible light emanating from the UV-C source. “Notched” dichroic or thin film filters are contemplated for this application, but other suitable conventional filtering may be employed. In this way, hospital patients, e.g., may have the benefits of continuous air sterilization at night without potential sleep impairment from the visual light components of the UV-C source.
The upper illumination unit 26 may also include a circular fluorescent bulb 36 the visible light from which passes through a glare reducing or diffusing glass cover 34 opaque to UV-C radiation.
The lower illumination unit 24 may also house a circular fluorescent bulb 38 with a glare reducing or diffusing cover to illuminate the lower part of the room.
The UV-C source 28 may be any suitable conventional type such as light emitting diodes (LED), high intensity discharge (HID) or fluorescence, and include any required starters, ballasts or other current regulators. They may, for example, may be in the shape of conventional two armed PL lamps and the sources of visible illumination may be located on the same plane as shown in
With reference to
The sources 36 of UV-C radiation may be any of suitable conventional type including fluorescents, cold cathode fluorescent, HID or LED sources and may include any required starters, ballasts or other current regulators. The electrical connection to all of the sources may be automatically interrupted by the mechanical removal of a blade 22 from the motor unit 16 and may be independently switched so that the sources may be operated independently of the rotation of the blades 22.
The blades or paddles 18 may be any suitable conventional configuration designed to move air and to provide appropriate aesthetics
The control circuit (not shown) is desirably located in the housing proximate to the motor 32 and is desirably remotely controlled in a conventional manner. The fixture may also include electrical ports for the addition of smoke, carbon monoxide, or motion detectors, and the UV-C radiation, visible light and blade rotation may be independently controlled as a function of these sensors or the desires of those in the room.
The capability of the UV-C ballast and radiation source to be adjusted provides a larger or smaller amount of UV-C energy in the radiation field. Such adjustment can be made via manual or remotely controlled switches, or may be triggered by sensors and/or detectors of microorganisms and/or concentration levels of microorganisms in the room. For instance, the presence of anthrax spores may be detected via imaging technologies triggering an immediate and sustained pulse of voltage resulting in UV-C irradiation capable of eliminating a pre-determined amount of anthrax spores within the space. Since anthrax spores would require other activity (evacuation), the limits of the predetermined eye level threshold could be increased due to the short duration of human exposure.
It is desirable that the unit contain indicator lights, e.g. LEDs, or glass surfaces, to indicate to those in the room that the UV-C source is in operation, This is especially true when the visible light from the UV-C source is suppressed and cannot provide such indication.
A manual or automatic override may also be provided to allow a user to increase the UV-C intensity for contingencies such as flu, bird flu, outbreaks/epidemics; bio-terrorist attack; black mold, etc. When the intensity of UV-C radiation is temporarily increased, it is desirable to provide a further indicator lights to those in the room, e.g. “excess UV-C is in operation”-“may exceed safe threshold-protect eyes and skin.”
In another embodiment, the UV-C radiation field may be established by sources in the ceiling medallion or canopy from which the fan is suspended. As shown in
By limiting the downward angle, direct radiation may not reach eye level within the dimensions of the room and the radiation will be reduced in intensity over the distance traveled. In addition, the radiation will pass through the space through which the fan blades rotate so that the radiation will be periodically interrupted by the rotating blades. This will reduce the time that direct radiate is present at any specific spot in the room below eye level and permit a higher radiation intensity than would otherwise be acceptable.
The control circuit as described supra may be housed within the canopy 50 or within the fan housing as desired.
In another embodiment, the source of UV-C radiation may be carried by one or more of the paddle blades. As shown in
Microorganisms are killed in the air through which the blades move and in the air circulated through the upward and horizontally radiation field extending from each source as it is moved. Since the sterilized air is constantly being mixed with air that has not been sterilized by the fan blades, a significant reduction in viable airborne microorganisms in the air in the lower part of the room where people are present is achieved.
The fixture may include other air improvement features such as filters to remove dust from the air circulated through the fixture. For example, the lower surface of the blades 46 may be provided with removable conventional “stick-on” filters where they will not interfere with UV-C radiation absorption and the aesthetics of the fixture. Alternatively, the upper part of the blades may include photocatalytic crystal films or other coatings which reduce fluorocarbons (smoke, odors, etc.), dust or both.
Power to the UV-C sources 48 on the blades 46 may be conventionally provided by a commutator ring and in such application it may be desirable that the control circuit interrupt power when the blades are not turning or when a blade is removed from the fan.
As understood from the embodiment of
By limiting the downward angle, direct radiation may not reach eye level within the dimensions of the room and will be reduced in intensity over the distance traveled. In addition, the interruption of the radiation by the rotating blades will reduce the time that direct radiation is present at any specific spot in the room below eye level and permit a higher radiation intensity than would otherwise be acceptable.
While the foregoing is a description of preferred embodiments, many variations and modifications will naturally occur to those of skill in this art from a perusal hereof. The invention is therefore not to be limited to the embodiments disclosed, but defined only by the claims when accorded a full range of equivalents.
