Patent Publication Number: US-2023158197-A1

Title: Uv-light air purifying apparatus

Description:
FIELD OF THE INVENTION 
     The present invention relates to an air purifying apparatus, and more particularly to an air purifying apparatus such as a plenum equipped with a diffuser for distributing air into a destination area, that purifies the air of micro-organisms by means of UV light. 
     BACKGROUND OF THE INVENTION 
     In commercial or industrial buildings, a ventilation system conveys air into the different rooms through air ducts, by means of usual components such as air pumps or fans to provide positive pressure to push the air towards the rooms, heating and cooling systems, macro-particulate air filtration, air recuperation systems and air ducts that carry the air to and from the rooms. 
     It is known to install plenums in the room ceilings, which are connected to the air ducts, to supply the air through a diffuser panel (also called the diffuser face) of the plenum. The diffuser panel is provided with air outlets that comprise openings that are disposed and configured to allow the air to be injected into the room along a determined direction. Some plenums are also equipped with a particulate air filter for filtering macro-particulate air-borne particles. The size and type of particles that will be filtered depend on the type of filter being used. 
     However, conventional particulate air filters in air plenums do not allow purification or sterilization of the air from micro-organisms such as viruses, including for example the SARS-CoV-2 that causes the COVID-19 disease. 
     One method of sterilizing the air from micro-organisms comprises using ultraviolet germicidal irradiation (UVGI), e.g. by forcing air through UV lamps. Known air purification UVGI systems include e.g. freestanding units with shielded UV lamps that use a fan to force air past the UV light. 
     Ultraviolet (UV) light is a form of electromagnetic radiation with wavelength shorter than that of visible light, but longer than X-rays. UV light is consequently invisible to the human eye. UV radiation is present in sunlight, but it is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. The chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Ultraviolet light of the “C” type, also called UV-C, is notably known for its germicidal effects. 
     However, UV light adversely affects humans: excessive exposure to UV radiation can result in acute and chronic harmful effects on the eye&#39;s dioptric system and retina, and exposure to UV radiation may cause some forms of skin cancer. UV-C notably is the highest-energy, most-dangerous type of ultraviolet radiation, and causes adverse effects that can variously be mutagenic or carcinogenic. 
     Consequently, using UV lights to purify the air by adding them to plenums that have air outlets that open into the room, has not been used yet, for the reason that the regulated safety standards that relate to the use of UV lights for purifying the air, would not be met by simply adding a UV light source to a conventional air plenum. Indeed, the concentration of UV light at the air outlet of the plenum, then remains too high for meeting the regulated safety standards. 
     SUMMARY OF THE INVENTION 
     The present invention relates to an air purifying apparatus for purifying air, comprising:
         a purifying chamber comprising a peripheral wall that has an air inlet for receiving air into said purifying chamber from an air source and an air outlet for supplying air from said purifying chamber to an air destination area;   a UV light source located within an irradiation portion of said purifying chamber, for emitting air purifying UV light therein;   an air channel extending between said air inlet and said air outlet for allowing the air to flow therein from an upstream end at said air inlet towards a downstream end at said air outlet and to be purified by the UV light between said upstream and downstream ends; and   a main baffle plate fixed within said purifying chamber downstream of said air inlet and upstream of said air outlet such that said air channel will be formed about said main baffle plate, said main baffle plate comprising a UV-reflective surface in register with said UV light source and that is tangentially oriented at least partly upstream to reflect at least part of the UV light emitted by said UV light source upstream in said air channel.       

     In one embodiment, said main baffle plate reflective surface comprises at least two segments with different angulations relative to said air channel, said at least two segments comprising an upstream segment located at an upstream extremity of said main baffle plate reflective surface and a downstream segment located at a downstream extremity of said main baffle plate reflective surface, with said downstream segment being more tangentially oriented upstream than said upstream segment. 
     In one embodiment, said at least two segments further comprise an intermediate segment located intermediate said upstream and downstream segments, with the intermediate segment being less tangentially oriented upstream than said upstream and downstream segments. 
     In one embodiment, the air purifying apparatus further comprises at least one secondary baffle plate within said purifying chamber located in said air channel downstream of said main baffle plate reflective surface, said at least one secondary baffle plate comprising a UV-absorbing surface, said at least one secondary baffle plate tangentially oriented at least partly upstream for blocking and absorbing at least part of the UV light emitted by said UV light source before it reaches said air outlet. 
     In one embodiment, said at least one secondary baffle plate is located on an opposite side of said main baffle plate relative to said main baffle plate reflective surface. 
     In one embodiment, said at least one secondary baffle plate comprises three secondary baffle plates disposed adjacent to said air outlet. 
     In one embodiment, the air purifying apparatus further comprises an auxiliary baffle plate within said purifying chamber located in said air channel between said main baffle plate reflective surface and said secondary baffle plates, said auxiliary baffle plate comprising a UV-reflective surface that is tangentially oriented at least partly upstream to reflect at least part of the UV light emitted by said UV light source upstream in said air channel, said auxiliary baffle plate positioned such that straight lines cannot be traced from said UV light source to said air outlet with less than three reflections within said purifying chamber to increase the absorption of said UV light therein. 
     In one embodiment, said purifying chamber peripheral wall is made of UV-reflective material. 
     In one embodiment, the air purifying apparatus further comprises a UV-absorbing panel provided on said peripheral wall downstream of said main baffle plate. 
     In one embodiment, said UV light source is a generally U-shaped UV-emitting light tube attached to said peripheral wall. 
     In one embodiment, said UV light source further emits visible light that is in the humanly perceptible visible spectrum, said visible light being less absorbed within said purifying chamber than said UV light such that at least some of said visible light will emanate out through said air outlet. 
     The present invention also relates to an air purifying apparatus for purifying air, comprising:
         a purifying chamber comprising a peripheral wall that has an air inlet for receiving air into said purifying chamber from an air source and an air outlet for providing air from said purifying chamber to an air destination;   a UV light source located within an irradiation portion of said purifying chamber, for emitting air-purifying UV light therein;   an air channel extending between said air inlet and said air outlet for allowing the air to flow from an upstream end at said air inlet towards a downstream end at said air outlet and to be purified by the UV light between said upstream and downstream ends; and   the air channel having a wider cross-sectional area at said irradiation portion of said purifying chamber than at said air inlet, for decreasing the speed of the air flowing through said air channel from said air inlet into said irradiation portion of said purifying chamber and for increasing the time during which air particles will be exposed to the UV light source within said irradiation portion of said purifying chamber.       

     In one embodiment, said purifying chamber comprises a plenum and a diverging collar upstream of said plenum, said diverging collar having a first end at said upstream end of said purifying chamber and a second end downstream of said first end, said diverging collar having a wider cross-sectional area at said second end than at said first end. 
     In one embodiment, the air purifying apparatus further comprises a main baffle plate fixed within said purifying chamber downstream of said air inlet and upstream of said air outlet, said main baffle plate comprising an air deflection surface that is tangentially oriented at least partly upstream, said main baffle plate deflection surface creating a first deviation of said air channel, said main baffle plate further decreasing the cross-sectional area of said air channel in said irradiation portion downstream of said irradiation portion. 
     In one embodiment, the air purifying apparatus further comprises an auxiliary baffle plate within said purifying chamber located in said air channel between said main baffle plate deflection surface and said secondary baffle plates, said auxiliary baffle plate being inclined at least partly upstream such that a portion of the air circulating in said air channel will be at least partly deviated toward an area located between some secondary baffle plates where it would otherwise circulate at a lesser debit rate. 
     In one embodiment, said air outlet is provided with a particulate air filter for filtering macro-particulate air-borne particles being conveyed through said air outlet, said particulate air filter further creating an air debit rate restriction upstream of said air outlet. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       In the annexed drawings: 
         FIG.  1    is a bottom perspective view of an air purifying apparatus according to the present invention; 
         FIG.  2    is a top perspective view of the air purifying apparatus of  FIG.  1   , which is partly broken along a vertical plane, with the macro-particulate air filter being shown entirely nonetheless and extending beyond that vertical plane; 
         FIG.  3    is a top perspective view of the air purifying apparatus of  FIG.  1   , which is partly broken along a first horizontal plane in the plenum and a second horizontal plane in the diverging collar, with the UV lamp being shown nonetheless above the first horizontal plane; 
         FIG.  4    is an enlarged partial cross-sectional view, partly schematic, of the air purifying apparatus of  FIG.  1   ; 
         FIG.  5    is similar to  FIG.  4   , but it suggests with arrows the UV-light reflection against different surfaces of the apparatus; and 
         FIG.  6    is similar to  FIG.  4   , but it suggests with arrows the air flow speed, with the relative length of the arrows symbolically suggesting the magnitude of the air flow speed. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIGS.  1 - 4    show an air purifying apparatus  10  for purifying air, according to the present invention. Air purifying apparatus  10  is for supplying air into a destination area (not shown) such as the room of a building, from an air source (not shown) such as a ventilation system that includes an air duct (not shown) destined to be connected to the air purifying apparatus  10  as detailed hereinafter. 
     Air purifying apparatus  10  comprises a purifying chamber  12  that has a peripheral wall  14 . Peripheral wall  14  comprises an air inlet  16  for receiving air into purifying chamber  12  from the air source and an air outlet  18  for supplying air from purifying chamber  12  to the air destination area. The purifying chamber  12  comprises a plenum  20  to which a diverging collar  22  is connected. Peripheral wall  14  may be considered to include both the peripheral wall of the plenum  20  and of the diverging collar  22 , and purifying chamber  12  may be considered to include both the inside of plenum  20  and the inside of collar  22 . 
     Air purifying apparatus  10  further defines an air channel extending between air inlet  16  and air outlet  18  for allowing the air to flow therein from an upstream end  10   a  at air inlet  16  towards a downstream end  10   b  at air outlet  18 . The diverging collar  22  itself has a first end  22   a  at the air inlet  16  and a second end  22   b  downstream of its first end  22   a  that connects to a first open end  20   a  of plenum  20  that allows air to flow from within collar  22  to within plenum  20 . Collar  22  has a wider cross-sectional area at its second end  22   b  than at its first end, as detailed hereinafter. Plenum  20  has a second end  20   b  at air outlet  18 . 
     Upstream and downstream references in the present specification, are made with respect to the air channel, i.e. the path followed by the air that flows through air purifying apparatus  10  from its upstream end  10   a  to its downstream end  10   b.    
     A UV light source  24  is located within purifying chamber  12 . In one embodiment, the UV light source is a generally U-shaped, including e.g. a J-shaped (where one leg is shorter than the other), UV-emitting light tube attached to peripheral wall  20 . In one embodiment, the UV light emitted by light source  24  is of the “C” type, i.e. UV-C light. A non-exclusive example of a UV light source usable with the present invention is the Sanuvox T6 High Intensity Germicidal 10.5″ UV “J” Lamp (model # LMPHGJ105). Other UV lamps with similar air purifying effects, including germicidal effects, may also be used, as will be obvious to someone skilled in the art. UV light source  24  includes a suitable enabling circuit  26  such as a ballast that, when plugged to an electric grid or connected to a battery (not shown), will allow light source  24  to emit UV light. 
     In the present specification, reference will be made to UV-absorbing and UV-reflective surfaces or materials. This means that each such reflective surface or material is considered to allow at least some significant reflection of UV light, while each such absorbing surface or material is considered to allow at least some significant absorption of UV light. Perfect reflection or absorption are not necessary, and in practice, will probably not exist. In addition to being interpreted by the person skilled in the art, the UV light “reflective” or “absorbing” qualities of surfaces or materials should also be interpreted with respect to each other, namely, UV-reflective surfaces or materials are considered to reflect more UV light per surface area than UV absorbing surfaces or materials referred to herein; and inversely, UV-absorbing surfaces or materials are considered to absorb more UV light per surface area than UV-reflective surfaces or materials referred to herein. 
     Air purifying apparatus  10  further comprises a main baffle plate  30  installed downstream of air inlet  16  and upstream of air outlet  18  such that the air channel will deviate in non-linear fashion about main baffle plate  30 . More particularly, main baffle plate  30  is fixed within purifying chamber  12  to peripheral wall  14  within plenum  20 , and extends from near plenum first end  20   a  in inclined fashion up and away into plenum  20  such that the air channel will be forced around main baffle plate  30  when flowing from plenum first end  20   a  to plenum second end  20   b.    
     Main baffle plate  30  comprises at least two segments with different angulations relative to the air channel. More particularly, main baffle plate  30  comprises three segments, namely, a first segment  30   a  fixed near the plenum first end  20   a ; a second segment  30   b  attached to first segment  30   a ; and a third segment  30   c , attached to second segment  30   b.    
     An irradiation portion  28  of purifying chamber  12  is defined as that portion of purifying chamber  12  which is located in the general area above main baffle plate  30  about UV light source  24  and within collar  22 , where UV light from UV light source  24  may irradiate directly. 
     Main baffle plate  30  comprises a UV-reflective and air-deflection surface  32  that is in register with UV light source  24  and that is tangentially oriented at least partly upstream in the air channel, i.e. it is inclined at least partly towards the direction from which the air flows, to reflect at least part of the UV light emitted by UV light source  124  upstream in the air channel; and to create a first deviation of the air flow and to decrease the cross-sectional area of the air channel downstream of irradiation portion  28 . 
     With its different angulations, main baffle plate  30  defines a downstream segment of its reflective surface  32  (that is the surface of third segment  30   c  that faces towards irradiation portion  28 ) that is more tangentially oriented upstream than an upstream segment thereof (that is the surface of segment  30   a  that faces towards irradiation portion  28 ) and than an intermediate segment thereof (that is the surface of second segment  30   b  that faces towards irradiation portion  28 ). The intermediate segment of reflective surface  32  is less tangentially oriented upstream than its upstream and downstream segments. This variation in the angulation of segments  30   a ,  30   b ,  30   c  of main baffle plate  30  allows to balance a desired air flow through purifying chamber  12  and a suitable control of UV light reflection therein, as detailed hereinafter. 
     Reflective surface  32  of main baffle plate  30  and peripheral wall  14  are made from a UV-reflective material. For example, peripheral wall  14  and baffle plate reflective surface  32  can be made from aluminium. For ease of construction, the entire baffle plate  30  and peripheral wall  14  may be made from aluminium; or, they may be coated or covered with a UV-light reflective material on their surface that faces irradiation portion  28 . 
     Air purifying apparatus  10  further comprises at least one secondary baffle plate, and more particularly, three secondary baffle plates  34 ,  36 ,  38  within purifying chamber  12  and located in the air channel downstream of main baffle plate reflective surface  32 , and more particularly, near air outlet  18  on the opposite site of main baffle plate  30  relative to reflective surface  32 . Secondary baffle plates  34 ,  36 ,  38  comprise a UV-absorbing surface, e.g. secondary baffle plates may be made from steel. Secondary baffle plates  34 ,  36 ,  38  are tangentially oriented partly upstream for blocking and absorbing at least part of the UV light emitted by UV light source  24  before it reaches air outlet  18 , as detailed hereinafter. 
     Air purifying apparatus  10  further comprises an auxiliary baffle plate  40  within purifying chamber  12  located in the air channel between main baffle plate reflective surface  32  and secondary baffle plates  34 ,  36 ,  38 . Auxiliary baffle plate  40  comprises a UV-reflective surface, e.g. auxiliary baffle plate  40  may be made form aluminium or coated on its reflective surface that faces upstream, with a UV-reflective material. Auxiliary baffle plate  40  is tangentially oriented at least partly upstream to reflect at least part of the UV light emitted by UV light source  24  back upstream in the air channel as detailed hereinafter. 
     Air purifying apparatus  10  also comprises a UV-absorbing panel  42  provided on peripheral wall  14  downstream of main baffle plate  30 , near auxiliary baffle plate  40 . UV-absorbing panel  42  is made from a UV-absorbing material, e.g. from polycarbonate. 
     Air purifying apparatus  10  comprises a particulate air filter  44  adjacent to, and upstream of, air outlet  18 , for filtering macro-particulate air-borne particles. A diffuser panel  46  is provided at air outlet  18  with openings  48  disposed according to a desired configuration to allow air to flow out of air purifying apparatus  10  into the destination area. 
     In use, air purifying apparatus  10  allows air from an air source to be purified, i.e. notably from micro-organisms by means of the UV light source  24 , before it is supplied to a destination area through air outlet  18 . Air purifying apparatus  10  allows optimizing the air purification through a control of the reflection of the UV light within the air channel while limiting UV light emission beyond air outlet  18 ; and through a control of the air flow through the air channel. Both of these aspects will be detailed below. 
     1. UV Light Reflection is Controlled within Air Purifying Apparatus  10   
       FIG.  5    suggests how UV light reflection is controlled within air purifying apparatus  10  by symbolizing UV light with arrows. 
     The UV light emitted by light source  24  within irradiation portion  28  of purifying chamber  12  will directly irradiate the air within irradiation portion  28 , including in plenum  20  in area A but also in collar  22  in area B. Furthermore, the UV light will reflect on reflective surface  32  of main baffle plate  30 , on the peripheral wall  14  of plenum  20  and on auxiliary baffle plate  40  such that the actual exposure of the air to the light from UV light source  42  in area A will be significantly increased. The main baffle plate  30  and the auxiliary baffle plate  40 , helped by the UV light absorbing panel  42 , form a UV light barrier in area C that most UV light will not pass. Indeed, the disposition of the light source  24  with respect to this UV light barrier is such that most UV light will be reflected back within irradiation portion  28 ; while that which hits the light absorbing panel  42  will be mostly absorbed as shown at D. The angle of the third segment of baffle plate  30   c , a.k.a. the downstream segment of its reflective surface, is particularly inclined to be tangentially oriented upstream and contributes to help reflect the UV light as shown at E. Also, auxiliary baffle plate  40  is positioned such that straight lines cannot be traced from UV light source  24  to air outlet  18  with less than three reflections within said purifying chamber, including at least two reflections against a light absorbing surface. 
     Downstream of this UV barrier, most of the light is likely to be reflected multiple times against the inclined almost parallel secondary baffle plates  34 ,  36 ,  38  to be mostly absorbed before it reaches the air filter  44 —that incidentally also absorbs UV light—such that the UV light emitted beyond air outlet  18  will remain below the regulated safety standards of UV-light emission. 
     2. Air Flow Controlled within Air Purifying Apparatus  10 . 
       FIG.  6    suggests how air flow is controlled within air purifying apparatus by symbolizing air flow with arrows, where longer arrows mean greater air speed. As a reminder, the air is fed to air inlet  16  from an air source that normally includes positive air pressure, e.g. by using an air pump or a fan. 
     As it enters diverging collar  22  at area V, the air flow is relatively quick. Then, the increase of the cross-sectional area of the air channel in irradiation portion  28  between air inlet  16  and UV light source  24  will force the air flow speed to decrease, before gradually increasing again through area X as the cross-sectional area of the air channel decreases towards Y at the UV barrier formed at the main baffle plate third segment  30   c  and the auxiliary baffle plate  40 . This decrease of the air flow speed at area W and, to a lesser extent, at area X, will allow a prolonged exposition of the air to the UV irradiation in irradiation portion  28  to increase the germicidal effect of the UV exposition. 
     Beyond area Y, air speed will unavoidably decrease upstream of the air filter, since the latter will restrict air flow somewhat. 
     The auxiliary baffle plate  40  is inclined such that air circulating in the air channel at area Y will not entirely flow out through air outlet  18  on either side of secondary baffle plate  34  where it would normally flow if not for auxiliary baffle plate  40 . Indeed, auxiliary baffle plate  40  will instead deviate part of the air flow towards an area located on either side of secondary baffle plates  36  and  38  where it would otherwise circulate much less were it not for auxiliary baffle plate  40 . This is desirable since it allows a relatively even distribution of air through air outlet  18 . 
     In one embodiment, UV light source  24  further emits visible light that is in the humanly perceptible visible spectrum, such as blue light. By selecting light absorbing materials such as that mentioned in the present specification (steel, polycarbonate), it has been found that this allows the visible blue light to be less absorbed within purifying chamber  12  than the UV light, such that at least some of the visible blue light will emanate out through air outlet  18 . This has two advantages: (a) it acts as a confirmation that the air purifying apparatus is emitting light, and since this light is emitted by the same light source as the UV light, then this means that the purifying process is working, which is relevant information for the maintenance staff. Also, (b) the visible blue light acts as a notice to anyone standing in the room that they are within an area wherein the air being supplied is purified by an apparatus  10  according to the present invention, which is comforting.