Abstrict An exhaust hood is disclosed which comprises an open underside
and a grease filter defining an exhaust plenum between the hood
and the grease filter and a flow path through the grease filter.
A shutter-like panel is slidable into the flow path adjacent to
the grease filter for blocking a portion of the flow path to adjust
the distribution of air across the face of the hood without altering
the volume of air flowing through the exhaust hood. Multiple side-by-side
panels may be provided and each panel preferably tapers in height
across its width. An intake fan is provided at a front portion of
the hood to direct room air from adjacent the hood through an intake
plenum and downwardly at a front portion of the space beneath the
hood to create a partial air curtain which is then exhausted through
the hood.
Claims What is claimed is:
1. An exhaust hood comprising:
a housing having an open underside,
a grease filter cooperating with the housing to define an exhaust
plenum therebetween and an exhaust flow path through the grease
filter,
a shutter panel mounted adjacent to the grease filter and having
a first end and a second end opposite the first end, the height
of the shutter panel varying from the first end to the second end,
and slidable into the flow path wherein the distribution of air
across the open underside is adjustable without decreasing the volume
of air, the amount of flow restriction effected by the shutter panel
varying between the ends,
an intake plenum at a front portion of the housing in direct communication
with space adjacent the housing, with diffuser opening at a front
portion of the housing facing downwardly to define an intake flow
path, and
a fan mounted to the housing for drawing air from adjacent the
housing into the intake plenum and out the diffuser opening along
the intake flow path which is then exhausted along the exhaust flow
path.
2. An exhaust hood according to claim 1, wherein a first plane
is defined by the grease filter and the shutter panel is slidable
in a second plane parallel to the first plane.
3. An exhaust hood according to claim 2, including a pair of opposed
channel members mounted in the second plane, the shutter panel having
a first end and a second end opposite from the first end, each of
the ends having a flange slidably received within a respective one
of the channel members.
4. An exhaust hood according to claim 2, wherein the second plane
is disposed above the first plane.
5. An exhaust hood according to claim 3, wherein the flanges are
similarly shaped, whereby either of the flanges is receivable within
each of the channels and the shutter panel is thereby reversible.
6. An exhaust hood according to claim 1, wherein the shutter panel
has an upper edge and a lower edge opposite the upper edge, the
edges extending between the ends of the panel means and converging.
7. An exhaust hood according to claim 1, wherein the height of
the shutter panel tapers uniformly from the first end to the second
end.
8. An exhaust hood according to claim 1, wherein the height of
the shutter panel at the first end is approximately twice the height
at the second end.
9. An exhaust hood according to claim 1, including a pair of opposed
channel members mounted in the second plane, each of the ends of
the shutter panel having a flange slidably received within a respective
one of the channel members.
10. An exhaust hood according to claim 9, wherein the flanges are
similarly shaped, whereby either of the flanges is receivable within
each of the channels and the shutter panel is thereby reversible.
11. An exhaust hood according to claim 1, including a second shutter
panel mounted adjacent to the grease filter for sliding movement
in the second plane into the flow path, the second shutter panel
being disposed horizontally adjacent to said one shutter panel.
12. An exhaust hood according to claim 11, wherein the configuration
of the second shutter panel is substantially similar to that of
said one shutter panel.
13. In an exhaust hood comprising a housing having an open underside
and a grease filter defining a first plane, the housing and grease
filter cooperating to define an exhaust plenum therebetween and
an exhaust flow path through the grease filter, the housing further
having an intake plenum at a front portion thereof, an intake opening,
and a diffuser opening to direct air from the intake plenum downwardly
across the front of the space beneath the open underside, the improvement
comprising:
the intake opening being in direct communication with the space
adjacent to and in front of the hood,
a fan mounted in communication with the intake opening to draw
air into the intake plenum whereby air from the intake plenum is
forced out the diffuser opening to create at least a partial air
curtain beneath the hood and across the front of the space beneath
the open underside, and
a shutter panel adjacent to the grease filter, the shutter panel
defining a second plane parallel to the first plane, the shutter
panel being slidable in the second plane into the exhaust flow path,
the shutter panel having an upper edge and a lower edge opposite
the upper edge, the edges extending between the ends of the panel
and converging.
14. In an exhaust hood comprising a housing having an open underside
and a grease filter defining a first plane, the housing and grease
filter cooperating to define an exhaust plenum therebetween and
an exhaust flow path through the grease filter, the housing further
having an intake plenum at a front portion thereof, an intake opening,
and a diffuser opening to direct air from the intake plenum downwardly
across the front of the space beneath the open underside, the improvement
comprising:
the intake opening being in direct communication with the space
adjacent to and in front of the hood,
a fan mounted in communication with the intake opening to draw
air into the intake plenum whereby air from the intake plenum is
forced out the diffuser opening to create at least a partial air
curtain beneath the hood and across the front of the space beneath
the open underside,
a shutter panel adjacent to the grease filter, the shutter panel
defining a second plane parallel to the first plane, the shutter
panel being slidable in the second plane into the exhaust flow path,
and
a pair of opposed channel members mounted in the second plane,
the shutter panel having, a first end and a second end opposite
from the first end, each of the ends having a flange slidably received
within a respective one of the channel members, the height of the
shutter panel tapering uniformly
from the first end to the second end.
15. In an exhaust hood comprising a housing having an open underside
and a grease filter defining a first plane, the housing and grease
filter cooperating to define an exhaust plenum therebetween and
an exhaust flow path through the grease filter, the housing further
having an intake plenum at a front portion thereof, an intake opening,
and a diffuser opening to direct air from the intake plenum downwardly
across the front of the space beneath the open underside, the improvement
comprising:
the intake opening being in direct communication with the space
adjacent to and in front of the hood,
a fan mounted in communication with the intake opening to draw
air into the intake plenum whereby air from the intake plenum is
forced out the diffuser opening to create at least a partial air
curtain beneath the hood and across the front of the space beneath
the open underside,
a shutter panel adjacent to the grease filter, the shutter panel
defining a second plane parallel to the first plane, the shutter
panel being slidable in the second plane into the exhaust flow path,
and
a pair of opposed channel members mounted in the second plane,
the shutter panel having a first end and a second end opposite from
the first end, each of the ends having a flange slidably received
within a respective one of the channel members, the height of the
shutter panel at the first end being approximately twice the height
at the second end. Description BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an exhaust hood for removing air laden
with grease, smoke or other contaminants from a working environment,
and more specifically to such an exhaust hood with mechanisms for
adjusting the volume of air passing through the hood and generating
an air curtain beneath the hood.
2. Description of Related Art
Exhaust hoods are used in a variety of environments such as kitchens,
laboratories and factories for exhausting heated or contaminated
air from a working environment. In a restaurant kitchen, for example,
there are usually a number of cooking units aligned in a row. Some
of these units, broilers and fryers for example, may produce considerable
quantities of smoke, fumes, grease particles and moisture, while
other units such as ranges and griddles may generate such pollutants
in considerably smaller amounts. Kitchen exhaust ventilators have
traditionally been designed with enough airflow capacity to remove
pollutants from broilers, fryers and other more active pollution-generating
cooking units. This results in excessive ventilation for those cooking
units which generate less pollution, such as the ranges and griddles.
A typical exhaust hood comprises a housing in the form of a box-like
structure with an intake comprising an open underside, and an exhaust
duct leading outwardly from its upper side. Air from the kitchen
environment passes into the housing through a series of grease filters,
and into an exhaust plenum above the grease filters. From the exhaust
plenum, it is drawn out of the hood through the exhaust duct. In
a kitchen the hoods are typically horizontally elongated to accommodate
a row of cooking units.
An elongated hood may give rise to uneven distribution of air across
the width of the hood. The portion of the hood directly beneath
the exhaust duct tends to remove air at the greatest volume-rate,
while portions of the hood displaced from the exhaust duct tend
to exhaust air at lower volume-rates. A common solution to this
problem is to situate the most active of the pollution-generating
cooking units directly beneath the exhaust duct and to place the
least active pollution-generating units furthest from the exhaust
duct. However, such an arrangement may not promote optimal efficiency
of the cooks working at the equipment, and many chefs prefer to
experiment with different equipment locations to achieve maximum
efficiency within the kitchen
To improve the flow distribution across a given exhaust hood, prior
designs have incorporated a flow restriction strategically located
in the path of the exhaust air to provide a desired flow distribution.
For example, U.S. Pat. No. 4,281,635, issued Aug. 4, 1981 to E.
C. Gaylord, discloses a kitchen ventilator or exhaust hood mounted
over an arrangement of kitchen equipment which includes a broiler,
a fryer, a range and a griddle. Air and grease pass from the equipment
through an inlet opening and take a circuitous path through a series
of opposing horizontal baffles to extract grease and other contaminants.
A damper baffle mounted on a horizontal pivot at the inlet opening
is pivotable toward and away from the lowest baffle to vary the
width of a gap between the damper and the baffle, whereby to vary
the volume of air flowing past the damper. To accommodate the varying
exhaust requirements of different pieces of kitchen equipment, additional
baffling is provided to reduce the rate of air flow into portions
of the ventilator positioned above the range and griddle units.
The additional baffling comprises choke plates attached to the hood
in strategic locations and extending into the path of the exhaust
air passing through the grease baffles. Several of the choke plates
are bolted in place and others are spot-welded in place. To rearrange
equipment beneath the exhaust hood, the choke plates must be removed
and repositioned. To remove those choke plates which are spot-welded,
the welds must be burned off
The volume of air exhausted through the hood must be replenished
from some source. If exterior air is drawn into the kitchen area,
it is typically tempered, particularly in northern climes. Such
systems require additional energy expenditures. It is also known
to draw air (often called "make-up" air) from adjacent
rooms in restaurants, for example, but such systems require additional
ducting and sometimes result in uneven air distribution from room
to room.
Sometimes air curtains are generated across the front of a hood
to "seal" smoke and grease-laden air beneath the hood
and prevent it from entering the kitchen area. Many such air curtains
are generated by structure mounted to the front of a hood and obtain
source air from the exterior of a building, or from make-up air.
Both sources require costly installations of extra ductwork.
SUMMARY OF THE INVENTION
The exhaust hood of the present invention provides a simpler and
more effective solution to the problem of the requirement for varied
exhaust air flow across an exhaust hood to accommodate the requirements
of various arrangements of equipment, each having different exhaust
output, beneath the hood. The exhaust hood of the present invention
further provides a sufficient air curtain to trap exhaust gases
within the exhaust hood, without the need for extensive additional
duct installation or introduction of untempered outside air.
The invention provides an exhaust hood in which a housing and a
grease filter cooperate to define an exhaust plenum with an exhaust
air flow path through the grease filter, and a shutter panel slidable
into the flow path, adjacent to the grease filter, to block a portion
of the flow path and thereby adjust the volume of air flowing through
the exhaust hood. The height of the shutter panel varies between
its ends, whereby the volume of air flow through the exhaust hood
varies across the width of the exhaust hood.
The invention further provides that the hood comprises a second
plenum, located toward the front of the hood, with a diffused opening
facing downwardly at the front of the hood, and a second opening
in communication with the space adjacent the hood, within the room
where the hood is located. A fan is disposed in the hood in a position
to draw air into the second plenum, through the second opening,
and force it out through the diffused opening. The air which is
forced out through the diffused opening forms at least a partial
air curtain, proximate to the lower edge of the exhaust hood, and
adjacent to its open underside. This air curtain is sufficient to
trap the flow of rising exhaust air, which is warm and laden with
smoke and grease, within the exhaust hood.
Other features and advantages of the invention will be apparent
from the ensuing description in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a partial sectional perspective view of an exhaust hood
according to the invention;
FIG. 2 is a side elevational view in cross-section of the exhaust
hood of FIG. 1 taken along line 2--2 of FIG. 1;
FIG. 3 is a sectional view of the hood of FIG. 1 taken along line
3--3 of
FIG. 2 and illustrating grease baffles and an adjustable flow restriction
panel according to the invention;
FIG. 4 is a sectional view of a portion of the hood of FIG. 1 taken
along line 4--4 of FIG. 2 and illustrating a mounting arrangement
for the adjustable flow restriction panel of FIG. 3;
FIG. 5 is a perspective view of the adjustable flow restriction
panel of FIG. 3;
FIG. 6 is a partial sectional perspective view of a second embodiment
of a hood according to the invention; and
FIG. 7 is a cross sectional view of the hood taken along line 7--7
of FIG. 6.
DESCRIPTION
Referring now to the drawings and to FIG. 1 in particular, an exhaust
hood 10 is shown which includes a housing comprising upper rear
front and side panels 12, 14, 16 and 18 forming a generally rectangular
box-like structure having an open underside 20. A dividing wall
22 slopes from a rear portion of the underside 20 upwardly and forwardly
towards the top panel 12 to define an exhaust plenum 24 within the
exhaust hood 10 above the dividing wall 22. An exhaust duct 26 extends
upwardly and outwardly from the exhaust plenum 24 through the top
panel 12. Suction applied to the exhaust duct 26, as by an exhaust
fan (not shown), draws air from the exhaust plenum 24 out of the
exhaust hood 10 through the exhaust duct 26.
A portion of the dividing wall 22 comprises a grease filter 28
of a type ordinarily used in the art. Typically, an exhaust hood
such as the hood 10 will have several grease filters 28 arranged
in side-by-side arrangement to span the full width of the exhaust
hood. The grease filters 28 are mounted in upper and lower U-shaped
horizontally disposed channels 30 in the ordinary fashion.
Turning to FIG. 2, the grease filters 28 thus slope upwardly and
forwardly at an approximately 45.degree. angle. A flow adjusting
mechanism 32 is disposed immediately behind the grease filters 28.
The flow adjusting mechanism 32 comprises one or more shutter-like
panels 34 slidably mounted behind and parallel to the grease filters
28. Preferably, a pair of elongated U-shaped channels 36 are provided
for slidably receiving the panel 34. The panel 34 slides within
the channels 36 parallel to the grease filters 28 to selectively
cover and uncover portions of the grease filters 28 and thereby
adjust the quantity of air flowing through the hood. Preferably,
the components of the flow adjusting mechanism 32 are formed of
stainless steel or aluminized steel
Turning to FIG. 3, it can be seen that the panel has the shape
of an elongated, truncated right triangle providing a first end
38 (corresponding to the base of the triangle) and a second end
40 (corresponding to a truncated edge of the triangle). An upper
edge of the panel 42 is essentially horizontal, while a lower edge
44 slopes slightly upwardly toward the panel second end 40. Preferably,
the height of the panel 34 (distance between the upper and lower
edges 42 and 44) at the first end 38 will be approximately twice
the height at the second end 40. Thus, the panel first end 38 blocks
a larger portion of the grease filters 28 than the panel second
end 40 and provides for a correspondingly larger volume of air passing
through the grease filter 28 adjacent to the panel second end 40.
Turning to FIG. 4, it can be seen that the U-shaped channels 36
are oriented along lateral edges 46 of the grease filters 28 with
the open edges of the channels 36 facing each other. U-shaped return
flanges 48 are provided at the first and second ends 38 and 40 of
the panel 34. Each flange 48 comprises a lip 50 extending normal
to the panel 34 and a second lip 52 extending from the first lip
parallel to the panel 34. (See also FIG. 5). The flanges 48 are
designed to slide freely within the channels 36. Some form of locking
mechanism, such as a lock nut or pin (not shown), is preferably
provided for holding the panel 34 at a desired location within the
channels 36.
In the orientation shown in FIG. 4, the panel 34 nearly abuts the
grease filters 28, whereby air cannot flow through the grease filters
28 adjacent to the panel 34 and then travel parallel to the panel
34 and out through the exhaust duct 26. However, if the panel 34
is reversed within the channels 36, the panel 34 will be spaced
apart slightly from the grease filter 28. With the panel 34 in this
orientation and to prevent air from flowing through the grease filter
28 adjacent to the panel 34 and travelling parallel to the panel
34 to escape into the plenum 24 and out through the exhaust 26,
a lip 54 is provided at the upper edge 42 of the panel 34. If desired,
an additional lip (not shown) may be provided at the panel lower
edge 44.
In a typical kitchen installation, the kitchen equipment will be
oriented underneath the exhaust hood 10. After the kitchen equipment
has been placed into a desired arrangement, the flow adjusting mechanism
32 is adjusted to provide appropriate exhaust quantities across
the width of the exhaust hood 10. For instance, the panel 34 will
be inserted into the channel 36 with its narrower second end 40
positioned above the more active producers of smoke, fumes and grease
such as the broilers and fryers. Then, the panel 34 will be moved
within the channels to a desired location to produce an appropriate
total volume of exhaust flow through the hood 10. Thus, the flow
control mechanism 32 provides not only control over the gross volume
of air exhausted through the exhaust hood 10 but also the lateral
distribution of the exhaust air across the width of the exhaust
hood 10.
If an even distribution of air is desired across the exhaust hood
10, the exhaust duct 26 can be located adjacent to one side 18 of
the exhaust hood 10 and the wider first end 38 of the panel 34 can
be located at that same side. Thus, more flow restriction will be
placed in front of the grease filters 28 adjacent to the exhaust
duct 26 and less flow restriction placed in front of the grease
filters 28 away from the exhaust duct 26 to provide an even distribution
of air exhausted through the grease filters laterally across the
width of the exhaust hood 10.
As shown in FIG. 3, multiple panels 34 are preferably provided
in side-by-side orientation for increased flexibility in adjusting
the air distribution within the exhaust hood 10. Various orientations
of side-by-side panels can be provided. For instance, two panels
34 can be provided with their wide first ends 38 located in a central
section of the hood 10 and their narrower second ends 40 located
adjacent to the sides of the hoods 18. In this orientation, with
an exhaust duct 26 located in the center of the hood 10, an even
distribution of air can be provided as the greater suction effect
in the center of the hood due to the location of the exhaust duct
would be negated by the greater blockage of the grease filters 28
in the center of the hood. Each panel 34 could be independently
adjusted. Also, multiple panels can be provided, one behind the
other.
By varying the angle of the lower edge 44 relative to the upper
edge 42, a greater degree of flow restriction is provided on one
side of the hood versus the other. Also, other shapes may be provided
for the panel 34. For instance, the lower edge 44 can be made parallel
the upper edge 42 with one of the upper or lower edges 42 or 44
provided with a discontinuity to vary the height (distance between
the upper and lower edges 42 and 44) of the panel 34 from one end
38 to the other 40. When employed in a kitchen, the exhaust hood
10 could be provided with separate panels 34 in side-by-side relation
corresponding to each piece of kitchen equipment located beneath
the exhaust hood 10. However, for most applications, an arrangement
having one or two panels 34 shaped as illustrated in FIG. 3 provides
ample adjustability of flow distribution across the exhaust hood
10 with a simple and uncomplicated structure.
Turning now to FIGS. 6 and 7, a second embodiment of the invention
includes a hood 100, similar in all salient respects to the hood
10 of FIG. 1, but with an additional flow path A to create an air
curtain across the front of the hood with make-up air directly from
the space adjacent the hood. A front panel 102 of the hood 100 has
an opening 104 which is covered by a protective louver 106. A flow-through
fan 108, directly behind the opening, draws air from adjacent the
hood, through the opening, 104 and into a plenum 110 at a forward
portion of the hood.
A diffuser opening 112, preferably extending from one side of the
hood to the other, is disposed at the front edge of a lower panel
114 of the hood. Air in the plenum 110 is forced by the fan 108
out through the diffuser opening 112 to create a curtain of air
beneath the front panel 102 of the hood. When the hood 100 is installed
and operated in the kitchen, the air curtain is created solely from
make-up air which is already tempered since it is drawn from adjacent
the hood.
The air is expelled, not to a separate receiver, but directly through
the hood. Hence, it is not a complete air curtain in the sense of
fully sealing the front of the adjoining work area beneath the hood,
but rather curtains primarily the uppermost space beneath the hood.
However, since warm, smoke and grease-laden air generally rises,
a partial air curtain effectively seals the contaminated air from
the kitchen area and helps exhaust it through the hood.
While the invention has been particularly described in connection
with certain specific embodiments thereof, it is to be understood
that this is by way of illustration and not of limitation, and the
scope of the appended claims should be construed as broadly as the
prior art will permit. |