US20050000509A1

US20050000509A1 - Exhaust hood with UVC light assembly

Info

Publication number: US20050000509A1
Application number: US10/855,905
Authority: US
Inventors: Thomas Carter
Original assignee: Caddy Corp
Current assignee: Caddy Corp
Priority date: 2003-05-27
Filing date: 2004-05-26
Publication date: 2005-01-06

Abstract

An exhaust hood is provided for filtering pollutants from exhaust air. The exhaust hood includes a light assembly and an air blower assembly for generating a stream of air in front of the light assembly.

Description

This application claims the benefit of U.S. Provisional Application No. 60/473,151, filed May 27, 2003, the disclosure of which is hereby incorporated by reference in its entirety, as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention generally relates to an exhaust hood which utilizes ultraviolet light to decontaminate exhaust air.
2. Description of the Related Art
In a number of work environments, such as kitchens and laboratories, exhaust hoods are used to vent exhaust air containing grease, fat, odors, and other pollutants. (hereinafter referred to as “pollutants”) produced by the utilization of cooking or heating appliances (ranges, ovens, stoves, burners, etc.). The exhaust hoods are positioned above the appliances, where a fan draws and directs exhaust air to an exhaust outlet. Before reaching the exhaust outlet, the exhaust air is drawn through at least one filter, such as a baffle filter or cartridge filter. The filter removes large particles of the pollutants from the exhaust air, leaving small particles in the exhaust air, such as grease vapor.
The exhaust hood may also have a mesh filter. The exhaust air exiting the mechanical filter enters the mesh filter which removes even smaller particles of pollutants before the exhaust air enters the exhaust outlet.
To avoid grease buildup in the hood and exhaust system, exhaust hoods may also use ultraviolet lights, typically in the “C” wavelength range (known in the art as “UVC lights”). FIGS. 1A, 1B, and 2 depict conventional exhaust hoods with UVC lights.
FIG. 1A shows an exhaust system manufactured by HALTON, in which exhaust air including grease vapor & particulate enters a hood 100 along with a supplemental supply of air, capture jet air curtain, 123. The exhaust air combined with the jet air curtain enters a cartridge, a KSA cartridge, 104 and flows past a bank of UVC lights 107, controlled by a ballast/control unit 201, before being exhausted to the atmosphere through a clean exhaust duct and hood chamber 105. The exhaust system also includes an optional make up air duct 120, a capture jet fan and air intake 121, and an optional low velocity front discharge plenum (200 feet per minute) 122.
FIG. 1B depicts a system manufactured by VENT MASTER, in which exhaust air comprising grease particulate and grease vapor enters a hood 100. The exhaust air circulates through a filter 104 which removes the grease particulate from the exhaust air. The exhaust air with grease vapors flows past a bank of ultraviolet lights 107, causing a chemical reaction, described in more detail below. Entering the clean duct work 105, is the exhaust air exposed to UVC light and O³(ozone).
A detailed description of how conventional exhaust hoods with UVC lights operates follows. FIG. 2 shows a cross-sectional view of exhaust hood 100.
Exhaust hood 100 includes a housing 101 having a rear wall 102, a front wall 103 spaced from the rear walls. Exhaust hood 100 is positioned above the appliance 106. Exhaust hood 100 also includes a filter 104, positioned between exhaust fan 108/exhaust outlet 105 and the exhaust inlet 109. As discussed above, the exhaust hood may also use a secondary filtration mechanism, such as a mesh filter 202, which is positioned between the filter 104 and the exhaust outlet 105. Exhaust hood 100 may also include a light assembly housing a plurality of UVC lights 107 controlled by a conventional UVC ballast/control unit 201, together or in place of the mesh filter 202. As shown in FIGS. 1 and 2, the UVC lights 107 are installed between the filter 104 and the exhaust outlet 105 in a generally horizontal position, such that when the exhaust air exits the filter 104 and, if applicable, the mesh filter 202, the exhaust air passes in front of the UVC lights 107. A resulting chemical reaction converts, for example, some of the grease and fat molecules in the exhaust air into water, carbon dioxide, and mineral acids. These by-products are then drawn out through the exhaust outlet 105. The UVC lights 107 may also be installed in a generally vertical position along the rear wall 102 of the exhaust hood 100, as shown in FIG. 3. FIG. 3 also shows lamp 221 used to illuminate the cooking area.
The exhaust air is also partially deodorized by the chemical reaction because small particles of pollutants which causes odors, are removed.
Conventional exhaust hoods with UVC lights, as described above, have drawbacks. As shown in FIGS. 1 and 2, the UVC lights 107 are positioned directly in the path of the exhaust air. Thus, “dirty” exhaust air, that is, containing grease, fat, etc. passes over the bulbs of the UVC lights 107, forming a coating of pollutants on the bulbs. This reduces the efficiency of the ultraviolet lights, and when the UVC light bulbs are completely covered, they are no longer capable of removing pollutants from the exhaust air. Similarly, when the UVC lights 107 are positioned along the rear wall 102 of the exhaust hood 100 (see FIG. 3), grease vapors adhere to the UVC bulbs, again reducing the efficiency of the UVC lights to remove pollutants. Consequently, to maintain the efficiency and functionality of the UVC lights 107, they must be periodically cleaned. For example, expensive, quarterly maintenance cleaning of the UVC bulbs by a qualified technician may be required.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an apparatus to overcome the drawbacks of conventional exhaust hoods with UVC flights.
In order to achieve the above object, according to one aspect of the present invention, an apparatus is provided that includes a light assembly, and an air blower assembly for generating a stream of air in front of the light assembly.
According to another aspect of the present invention, a method of removing pollutants from exhaust air is provided. The method includes the steps of drawing exhaust air through a filter, causing a chemical reaction between ultraviolet rays emitted from a light assembly and the pollutants in the exhaust air, and directing a stream of air in front of the light assembly.
Further objects, features, and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross-sectional views of a cooking environment, depicting conventional exhaust hoods with UVC lights;
FIG. 2 is a cross-sectional view of a conventional exhaust hood with UVC lights positioned in a generally horizonal direction;
FIG. 3 is a cross-sectional view of a conventional exhaust hood with UVC lights positioned in a generally vertical direction;
FIG. 4 is a cross-sectional view of an embodiment of the present invention;
FIG. 5 is a cross-sectional view of another embodiment of the present invention;
FIG. 6 corresponds to the exhaust hood of FIG. 4, showing preferred dimensions; and
FIG. 7 corresponds to the exhaust hood of FIG. 5, showing preferred dimensions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4 is a cross-sectional view of an exhaust hood 400 according to an embodiment of the invention. Exhaust hood 400 has a rear wall 401 and a front wall 402 and two side walls (not shown) connecting the front and rear walls. Attached to the bottom of the rear wall is a bracket 403 extending forward in a substantially horizontal direction towards the front wall 402. An exhaust collar 406 extends upward from the ceiling 405 of the exhaust hood 400 and is attached to an exhaust fan 408. The exhaust fan 408 draws the exhaust air generated by an appliance (not shown) into the exhaust collar 406. Attached to the exhaust fan 408 is an exhaust duct 407 for venting the exhaust air out into, for example, the atmosphere. Attached to the bottom of the front wall 402 is an optional heat shield 410 which extends in a substantially horizontal direction towards the rear wall 401. The heat shield 410 prevents circulating exhaust air within the exhaust hood chamber 411 from exiting underneath the front wall 402 of the exhaust hood 400. Located within the exhaust hood chamber 411, between the exhaust collar 406 and the appliance, is a filter 404, such as a baffle filter or a cartridge filter, removing particles of pollutants from the exhaust air as the exhaust air is drawn through the filter 404. One end of the filter 404 is held by the bracket 403. The other end of the filter 404 is held to the ceiling member 405 by bracket 413.
As further shown in FIG. 4, a light assembly 414 having at least one light bulb, preferably an ultraviolet light bulb emitting ultraviolet rays having a wavelength of between 1 and 310 nanometers, is located along the inside of the rear wall 401 within the exhaust hood chamber 411, in a substantially vertical position, such that it is not within the direct path of the exhaust air. Further, the light assembly 414 is positioned so that the filter 404 prevents ultraviolet rays emitted from the light assembly 414 from escaping the exhaust hood chamber 411. The light assembly 414 is attached to the rear wall 401 by bracket 415 and is controlled by a ballast/control unit 416.
Exhaust hood 400 also includes an air chamber 417 located above the ceiling member 405 and along the length of the rear wall 401. The air chamber terminates near the bottom of the rear wall 401 with an outlet opening 419 in a substantially upward direction, past the front of the light assembly 414. Fan or air blower 420 is communicatively attached to the end of the air chamber 417, above the ceiling member 405. Fan or air blower 420 generates a stream of clean air that travels through the air chamber 417, through outlet opening 419, and in front of light assembly 414, thereby creating a “wall” of clean air between the “dirty” exhaust air and the light assembly 414. This, in turn, substantially reduces the amount of pollutants that adhere to the light bulbs.
Exhaust hood 400 also includes an optional lamp 421 that is used to illuminate the hood chamber 411 and the appliance.
The exhaust hood 400 operates as follows. Exhaust air containing pollutants is created by normal operation of the appliance. To vent the exhaust air away from the appliance, an exhaust hood 400 is positioned above the appliance. The exhaust fan 408, attached to the exhaust duct 407 and the exhaust collar 406, draws the exhaust air away from the appliance into the exhaust hood chamber 411.
Exhaust air is drawn through the filter 404, which removes particles of pollutants from the exhaust air. Exiting the filter 404, the exhaust air, still containing pollutants (usually as vapor), is exposed to the ultraviolet rays from a light assembly 414, which further treats the exhaust air before venting it into, for example, the atmosphere. That is, additional pollutants and odors are removed from the exhaust air by a chemical reaction between the pollutants and ultraviolet rays emitted from light assembly. The by-products of this chemical reaction and the treated exhaust air are drawn out from the exhaust hood chamber 411 into the exhaust collar 406 and the exhaust duct 407.
To minimize contact between the “dirty” exhaust air and the light bulbs of the light assembly 414, the wall of clean air, generated by the fan or blower 420, is discharged from the air chamber 417 through the outlet opening 419 in front of the light assembly 414, thereby separating the light assembly 414 from the exhaust air. The wall of clean air is vented out from the exhaust hood chamber 411, through the exhaust collar 406 and the exhaust duct 407, in a similar manner as the treated exhaust air.
By providing the wall of clean air between the light assembly 414 and the exhaust air, pollutants and contaminants in the exhaust air are substantially prevented from coming into contact with light assembly 414. Thus, any coating of the light bulbs is minimized, and the efficiency and functionality of the light assembly 414 is maintained over a much longer period of time than in a conventional exhaust hood. Further, expensive periodic cleaning of the UVC lights is minimized, if not eliminated outright.
Another embodiment of the present invention is to provide a second outlet opening 418 at the end of the air chamber 417, as shown in FIG. 5. The operation of the second embodiment is substantially similar as that of the exhaust hood 400 in the first embodiment, with the exception of the second outlet opening 418. The second outlet opening 418 is positioned such that a second stream of clean air exiting opening 418 is introduced behind the light assembly 414. This second stream of clean air flows upwards in a substantially vertical direction, where it collides with the bracket 415, which redirects it across the front of light assembly 414, where it combines with the wall of clean air from the outlet opening 419.
The second stream of clean air pressurizes the back of the light assembly 414 so that grease vapor is substantially prevented from migrating towards the light assembly 414. This is especially useful when having to vent a great amount of exhaust air containing large volumes of pollutants.
FIGS. 6 and 7 respectively correspond to the exhaust hoods of FIGS. 4 and 5, showing preferred dimensions. However, as will be appreciated by those skilled in the art, these dimensions may vary.
While the present invention has been described with reference to what are considered to be the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. For example, while this invention has been described in connection with exhaust hoods, it may be applied in other apparatuses in which one desires to separate a light assembly from a “dirty” stream of air. Accordingly, the scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An apparatus comprising:

a light assembly; and

an air blower assembly for generating a stream of air in front of the light assembly.

2. An apparatus according to claim 1, wherein the light assembly comprises one or more ultraviolet light bulbs.

3. An apparatus according to claim 2, wherein the one or more ultraviolet light bulbs emit ultraviolet rays in the “C” wavelength range of ultraviolet light.

4. An apparatus according to claim 1, further comprising:

a hood for housing the light assembly and the air blower assembly, wherein the hood has front, rear, and side walls, and a ceiling.

5. An apparatus according to claim 1, wherein the air blower assembly comprises a fan and an air chamber communicatively connected thereto, wherein the air chamber directs the stream of air in front of the light assembly.

6. An apparatus according to claim 5, wherein the air chamber has an opening to discharge the stream of air in front of the light assembly.

7. An apparatus according to claim 6, wherein the air chamber has a second opening to discharge a second stream of air behind the light assembly.

8. An apparatus comprising:

a hood positioned above a cooking surface, wherein the hood has front, rear, and side walls, and a ceiling;

an exhaust collar creating an opening in the ceiling of the hood;

a first fan attached to the exhaust collar, for drawing exhaust air from the hood into an exhaust duct positioned above the exhaust collar;

a filter for filtering the exhaust air, positioned between the exhaust collar and the cooking surface;

a light assembly positioned between the exhaust collar and the filter;

a second fan for producing a first stream of clean air;

an air intake chamber communicatively connected at a first end to the second fan, the air intake chamber having an opening at a second end for discharging the first stream of clean air in front of the light assembly.

9. An apparatus according to claim 8, wherein the air intake chamber has a second opening at the second end for discharging a second stream of clean air behind the light assembly.

10. An apparatus according to claim 9, wherein the second stream of clean air is redirected to the front of the light assembly, and combines with the first stream of clean air.

11. An apparatus according to claim 8, wherein the light assembly comprises one or more ultraviolet light bulbs.

12. An apparatus according to claim 11, wherein the one or more ultraviolet light bulbs emit ultraviolet rays in the “C” wavelength range of ultraviolet light.

13. An apparatus according to claim 11, wherein the filter blocks ultraviolet rays from escaping from the exhaust hood.

14. A method of substantially removing pollutants from exhaust air, the method comprising the steps of:

drawing exhaust air through a filter;

causing a chemical reaction between ultraviolet rays emitted from a light assembly and the pollutants in the exhaust air; and

directing a first stream of clean air in front of the light assembly.

15. A method according to claim 14, further comprising a step of directing a second stream of clean air behind the light assembly.

16. A method according to claim 15, further comprising the step of redirecting the second stream of clean air to the front of the light assembly, and combining with the first stream of clean air.

17. A method according to claim 14, wherein the filter blocks the ultraviolet rays from escaping from the exhaust hood.