Exhaust hood

Details Exhaust hood Exhaust hood

1999-03-01

2001-02-06

Lazarus, Ira S. (Department: 3743)

Stoves and furnaces

Stove hoods

C126S29900R, C055SDIG003, C454S067000

Reexamination Certificate

active

06182653

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an exhaust hood for moving air laden with grease, smoke, vapors, or other contaminants or particulates from a working environment, and more specifically, to such an exhaust hood having an inverted V-shaped transverse configuration for more efficiently funneling the contaminated air from the working environment.
2. Related Art
Exhaust hoods are employed in a variety of environments such as kitchens, laboratories, and commercial food-preparation spaces, in which there are typically several cooking units aligned in a row. Some of these units; e.g., boilers and fryers, may produce considerable quantities of smoke, fumes, grease particles and moisture, while other units, e.g., ranges and griddles, may generate pollutants in substantially smaller amounts. Kitchen exhaust ventilation systems have traditionally been designed with enough airflow capacity to remove pollutants from broilers, fryers, and more active pollution-generating cooking units.
Because of the amount of negative pressure necessary to remove a large volume of contaminants, operating these exhaust ventilators is costly. More particularly, most island-type commercial exhaust hoods having a grease filtering capability include a grease filter installed in the center of the hood cavity at approximately 45° from horizontal in a V-shape having a downwardly directed apex and running the full length of the hood. This configuration is shown as
FIG. 1
, labeled Prior Art. The principal of operation of this prior art configuration is to create enough negative air pressure in front of the filter in order to capture the heat, smoke, grease and other airborne contaminants and remove them from the working environment.
The negative air pressure downstream of these grease filters must be substantial enough to alter the vertical direction of the hot contaminated air created in the cooking process and draw it toward and then into the grease filters. Failure to exhaust sufficient volumes of air through the filters will result in some hot contaminated air becoming trapped in the hood cavity rather than being exhausted through the filters. Once the hood cavity is filled with the hot, vertically rising, contaminated air that has not been captured by the grease filters, it will begin to escape around the lower edges of the hood into the room or other working space.
The prior-art solution for the foregoing problem, which is commonplace in island-type food preparation surfaces, is to exhaust larger quantities of air through the grease filters until the negative air pressure created is high enough to alter the direction of the vertical air flow toward the grease filter. This requires an exhaust fan; a motor; and a heating, ventilation, and air conditioning (“HVAC”) system capable of handling a larger volume of airflow, which, consequently, means higher construction cost when installing the system and higher utility costs when operating the system.
What has been needed is a more efficiently and economically designed hood requiring a smaller or less powerful exhaust fan, motor, and HVAC system, yet providing effective exhaustion of contaminated air.
SUMMARY OF THE INVENTION
In its broader aspects, the present invention provides an exhaust hood comprising a housing having a pair of opposing end panels and an open underside. Interior surfaces form an inverted V in transverse section, the interior surfaces and the end panels defining a cavity extending upwardly within the housing from the open underside. At least one filter provides at least a portion of the interior surfaces. An exhaust outlet is formed in the housing above the apex of the inverted V formed by the interior walls, the exhaust outlet being in fluid communication with the cavity by way of the filter. The cavity and the exhaust outlet thereby provide a flow path in the manner of an inverted funnel for rising gases and entrained contaminants.
In preferred embodiments of the invention, the housing includes an upper panel, the end panels depending from the upper panel. A pair of grease filters is supported within an upper portion of the housing, the grease filters extending between the end panels and sloping downwardly and outwardly in opposite directions from a central portion of the housing. A pair of interior walls are supported within the housing in spaced relation to each other, each of the interior walls extending between the end panels below a respective one of the grease filters and sloping downwardly and outwardly in planes parallel to the planes of the respective grease filter. Thus, the grease filters and the interior walls define the cavity in an inverted V-shape in transverse section. An exhaust plenum is formed in the housing above the apex of the inverted V formed by the interior walls and the grease filters, the exhaust plenum being in fluid communication with the cavity by way of the grease filters. The exhaust outlet is formed in the upper panel of the housing and is in fluid communication with the exhaust plenum, whereby the exhaust plenum, together with the cavity and the exhaust outlet, provides the flow path in the manner of an inverted funnel for the rising gases and entrained contaminants.
The housing preferably includes a pair of side panels depending from the upper panel and extending between the end panels.
A grease drain system is also preferably provided, in which each of a pair of grease troughs, removably supported within the cavity, extends along a lower edge of a respective one of the grease filters. A removable grease cup is supported on one of the end panels, a first one of the grease troughs having an open end disposed above the grease cup, whereby grease draining from the respective grease filter is caught by the first grease trough and deposited in the cup by way of the open end of the first grease trough. A grease drain in the form of a channel is supported on the same end panel at an angle from the horizontal. The other grease trough also has an open end, the grease drain having an upper end disposed below the open end thereof, and a lower end disposed above the grease cup. Thus, grease draining from the second grease filter is caught by the other grease trough, directed to the grease drain by way of the open end of such other grease trough, and deposited in the grease cup by way of the lower end of the grease drain.
Also in preferred emodiments, each of a pair of grease catches extends between the end panels along a lower edge of a respective one of the interior walls.
The exhaust hood of the present invention provides a simple and more effective solution to the problem of providing adequate air exhaustion at a lower cost by providing an exhaust hood having an inverted V-shaped interior, wherein the walls comprising the inverted V include grease filters and the apex of the inverted V lies adjacent an exhaust duct in communication with an exhaust fan. Because the hood is thereby shaped like an inverted funnel, the naturally rising hot airflow must move toward the grease filters and exhaust duct. Thus, a relatively large negative pressure is not necessary to alter the airflow direction; instead, only negative pressure sufficient to draw the adjacent air through the duct is required. Consequently, a smaller exhaust fan and motor can be used. Also, a lower-powered HVAC system for exhausting air from the building may be employed. All these factors act in concert to lower building and utility costs.
Other features and advantages of the invention will be apparent from the ensuing description in conjunction with the accompanying drawings.


REFERENCES:
patent: 3411428 (1968-11-01), Ahlrich
patent: 3537442 (1970-11-01), Berger
patent: 4047519 (1977-09-01), Nett
patent: 4323373 (1982-04-01), Fritz
patent: 4700688 (1987-10-01), Searcy et al.
patent: 4827903 (1989-05-01), Kim
patent: 4896657 (1990-01-01), Glassman
patent: 5522377 (1996-06-01), Fritz
patent: 5524607 (1996-06-01), Grohman et al.
patent: 5927268 (1999-07-01), Chiang et al.

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