[0001] This invention relates to a method of and device for retarding or preventing the
rollout or curling of smoke from underneath a hood or bonnet of a grease extraction
ventilator.
BACKGROUND OF THE INVENTION
[0002] Numerous grease extraction ventilators have been developed, including those utilizing
a water bath or water spray to assist in the removal of grease, smoke and the like,
from heated air and products of cooking, as well as a dry type, in which heated air
and products of cooking are passed through a body of mesh, such as retained between
two screens. Normally, the bonnet or hood of a grease extraction ventilator comprises
a series of depending walls which essentially surround an enclosure which is placed
above the cooking equipment, so that heated air and products of cooking, rising from
the cooking equipment, will collect in the bonnet and will flow toward the grease
removal portion of the ventilator, then into a duct which extends to an exhaust fan
or blower for exhausting the remaining air and gases, such as into the atmosphere.
The exhaust fan produces a suction in the duct and draws the air and products of cooking
through the grease removal means, which also may condense water vapor and remove small
particles. All such ventilators have the problem, at times, of being flooded with
smoke, as when a fire occurs, particularly on a broiler or other type of cooking equipment
operating at higher temperatures. Normally, room air is drawn under the walls which
surround the enclosure, which walls are normally the front and end walls, since the
usual installation of a grease extraction ventilator is against a wall of a kitchen.
However, there are some ventilators which have four walls exposed to the room and
the method and device of this invention are equally applicable to such ventilators.
[0003] When an abnormal amount of smoke is produced, the smoke may tend to curl or roll
underneath the lower edges of the enclosure walls and penetrate into the room. Often,
such smoke carries cooking odors with it and may find its way into the dining area,
which is often adjacent the kitchen, and become not only visually but also olfactorily
disagreeable to the patrons. As far as is known, no success has met with attempts
which have been made to cure this problem.
[0004] Among the objects of this invention are to provide a method of retarding or preventing
the curling or rollout of smoke from beneath the edges of the depending walls which
form an enclosure for receiving the products of cooking as well as room air; to provide
such a method which is effective and efficient in overcoming this problem; to provide
such a method which may be carried out with a minimum of expense; to provide a device
which is particularly adapted to carry out the method of this invention; and to provide
such a device which is readily and inexpensively incorporated in a grease extraction
ventilator.
SUMMARY OF THE INVENTION
[0005] The method of preventing the curling or rollout of smoke from beneath the depending
enclosure walls of a grease extraction ventilator, in accordance with this invention,
comprises providing a series of apertures in the upright walls from adjacent the lower
edge thereof for a predetermined distance upwardly. The apertures are preferably comparatively
small and relatively closely spaced, being preferably placed in parallel rows, also
parallel to the lower edge of the wall, with the apertures of one row alternating
in position with the apertures of adjacent rows, in order to maintain as much strength
as possible in the walls. The number of rows may be varied, depending on the height
of the wall and the capacity of the ventilator with additional apertures for a ventilator
having a larger capacity.
[0006] The apertures may be slots, such as relatively short, and with the spacing between
parallel rows being equal to or less than the height of the slots, with the lowest
row being relatively close to the lower edge of the wall in which provided. However,
the apertures may be circular or have any other shape, such as oval, elliptical or
the like.
THE DRAWINGS
[0007]
Fig. 1 is a perspective view of a grease extraction ventilator in which the method
and device of this invention are utilized, showing also cooking equipment beneath
the ventilator.
Fig. 2 is a vertical section, taken in the plane of lines 2-2 of Fig. 1.
Fig. 3 is a fragmentary enlargement of a portion at the lower right of Fig. 2.
Fig. 4 is a front elevation of a grease extraction ventilator, capable of tempering
incoming air for discharge into the room and also of bypassing a portion of the incoming
air to a discharge duct.
Fig. 5 is a vertical section, on an enlarged scale, taken along line 5-5 of Fig. 4.
Fig. 6 is a fragmentary enlargement of a lower left portion of the ventilator of Fig.
4.
Fig. 7 is a fragmentary, enlarged vertical section, taken along line 7-7 of Fig. 4.
Fig. 8 is a front elevation of an additional type of ventilator in which the method
and device of this invention are utilized.
Fig. 9 is a vertical section, taken along line 9-9 of Fig. 8.
Fig. 10 is a fragmentary enlargement of a lower left portion of Fig. 9.
Fig. 11 is a fragmentary, vertical section, taken along line 11-11 of Fig. 8.
Fig. 12 is a fragmentary elevation of a lower corner of a front wall of a grease extraction
ventilator, in which the method and device of this invention are utilized and showing,
on a further enlarged scale, a variation in the apertures.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0008] A smoke curl or rollout prevention method for a grease extraction ventilator to prevent
or retard the curling or rollout of smoke from underneath the walls of a hood or bonnet
of the ventilator into a room, may be utilized, as illustrated in Figs. 1-3, to provide
an appropriate number of rows of alternate slots 10 and 11, disposed just above and
with each row essentially parallel to, the lower edges of each of the walls, panels,
or the like under which room air may be drawn to mix with heated air and products
of cooking produced by cooking equipment C beneath the ventilator. Such walls of the
ventilator V include a front depending flange 12, an extension 13 of one side wall
14, as in Fig. 1, and an extension 15 of the opposite side wall, as in Figs. 2 and
3. Each of extensions 13 and 15 have an upwardly inclined lower edge. Rows of holes,
circular or other shape, may be substituted for the rows of slots 10 and 11. The heated
air and products of cooking move into the hood or bonnet, both by natural convection
and suction by which the same are drawn upwardly through the ventilator and through
a duct 16 extending, as indicated by the dotted line, to an exhaust fan 17 (shown
in outline) at an appropriate location, as for discharge into the atmosphere.
[0009] The exhaust ventilator V of Fig. 1 is constructed similarly to the exhaust ventilator
of U. S. Patent No. 3,841,062, thus including a shelf 18 from which front flange 12
depends and a top plate 19 connects the end walls, as well as a front plate 20 having
an access plate 21. The top plate 19 is also connected to a back plate 22 of Fig.
2, while exhaust duct 16 extends upwardly from top plate 19. A control box B, mounted
on shelf 18, may be provided with a light switch 23 and a wash control switch 24 for
turning on a washing mechanism, which will be referred to later.
[0010] The parts shown in Fig. 2 are essentially inside the ventilator and include a front
plate 26 having a rearwardly extending curl 27 at the top, with plate 26 being connected
to a bottom plate 28, which in turn extends rearwardly to the back plate 22. A fixed
baffle 29 slopes downwardly above front plate 26 to a dow nwardly extending arcuate
portion 30, while an adjustable baffle 31 having a front planar flange 32 is connected
to arcuate portion 30 by bolts 33, to permit adjustment of the position of flange
32. Air and products of cooking are drawn between baffle 29 and curl 27, through suction
produced by the discharge fan through duct 16, to engage a water bath which, prior
to such engagement, extends upwardly to a dot-dash line 34 but is forced downwardly
to pass under flange 32 and behind baffle 31, engaging a concave water deflector plate
35, whose rear edge is spaced slightly from back wall 20.
[0011] As the heated air and gases pass around flange 32, they will churn the water, causing
tongues of water to move up into the air stream to remove grease as well as to condense
vapor products. As the body of water is forced up against the deflector plate 35,
it will overflow the upper rear edge and tend to carry grease and condensed vapor
products with it, for collection beneath plate 32, in the lower portion of the body
of water and later removal through drainage. The stream of air and heated gases will
then move upwardly against an air deflector plate 36, which is provided with a slanting
flange 37 at its upper edge and is stabilized by a series of brackets 38. Flange 37
tends to strip water droplets from the air passing around it, the droplets tending
to fall onto the top of fixed baffle 29. From the space above flange 37, the mixed
air and products of cooking, without the water and other condensable products which
have been stripped by flange 37, pass into the duct 17 for discharge.
[0012] A hot water feed pipe 39 extends along the rear wall above brackets 38 and carries
a series of nozzles 40 which spray hot water into the upper chamber against the rear
of front wall 20 and the underside of top plate 19, as well as being deflected against
the top of fixed baffle 29. One or more supply pipes 41 may extend to a manifold 42
below brackets 38, which carries a series of nozzles (not shown) for cleaning the
upper side of air deflection plate 36.
[0013] The number of rows of slots may be varied. depending upon the size of the ventilator
and also the amount of air normally drawn from the room in which the ventilator or
a series of ventilators are installed. The speed of the conventional blower, by which
air and products of cooking are removed through duct 16, may be controlled so that
the suction is increased as the amount of heated products of cooking and room air
increases, although it may happen that, even when the suction blower is operating
at full capacity, the amount of heated products of cooking further increase and, at
times, an undue amount of smoke is produced. At such times, there is a tendency for
the heated gases carrying smoke to accumulate and expand, so as to curl under the
lower edges of the hood, thereby carrying smoke and cooking odors into the room. Such
smoke, and particularly cooking odors, tend to infiltrate into the dining areas, with
a resultant distasteful effect on those partaking of food there.
[0014] It would normally be assumed, if smoke, such as carrying cooking odors, may curl
out under the edges of the depending walls of the hood or bonnet, that the provision
of a series of rows of apertures in each of the walls would cause the smoke to move
outwardly from the hood at a more rapid rate and shortly permeate not only the kitchen
but the entires premises. However, the reverse has been found to be true, since apparently
the cooler air of the room, entering the apertures, will cool the more heated air
inside the hood and, through contraction due to cooling, diminish the volume of the
air and products of cooking, causing a decrease in the temperature and the volume
of exhaust air, with the products of cooking flowing toward the inlet of the exhaust
duct. Such decrease in volume apparently also increases the velocity with which the
heated waste air rising from the cooking surfaces moves into the hood or bonnet, thereby
producing an increase in the flow of air through the apertures in the
outer walls of the ventilator and thereby eliminating the escape of waste heat, fumes
and smoke into the room.
[0015] The slots 10 and 11 are placed in stagerred relation, in order to obtain maximum
strength of the depending walls around the perimeter of the hood. The slots 10 and
11 may be on the order of 2 inches or 5,08 cm long, 1/4 inch or 0,635 cm high and
spaced apart in each row on the order of 1/2 inch or 1.27 cm, while the distance between
rows may be on the order of 1/4 inch or 0,635 cm. As shown, there are six rows of
slots, although the number of rows and the number of apertures in each may be changed
considerably.
[0016] The method of preventing smoke curl of this invention may be applied to a ventilator
Vʹ of Fig. 4, which may similarly be provided with a row of slots 10, interspaced
and alternating with rows of slots 11, in a manner similar to ventilator V of Fig.
1. The rows of slots 10 and 11 are preferably placed in parallel relation to the lower
edge of a lower front wall 45 of Figs. 1 and 6, as well as an end wall 46 of Figs.
5 and 7 and a corresponding end wall at the opposite end of front wall 45, i.e. having
slots disposed in the same manner as end wall 45 in the lower portion thereof. The
room air and heated air and products of cooking arising from the cooking equipment
over which the ventilator is placed, in a manner similar to the ventilator V of Fig.
1, flow within the walls of the hood or bonnet, which include lower front wall 45,
end wall 46 and the corresponding opposite end wall, to a device for removing grease
and a discharge duct 47 of Figs. 1 and 5, which leads to a conventional fan or blower
(not shown) for exhaust of the air and gases into the atmosphere. The ventilator Vʹ
of Figs. 4-7 is constructed similarly to the ventilator of U. S. patent No. 4,407,206,
which is also adapted to temper fresh air in one or more heat exchangers and discharge
the tempered fresh air into the room, as well as supply incoming air to the discharge
duct in a manner which automatically regulates the amount of exhaust and makeup air
required to remove and replace the minimal amount of outside air to eliminate heat,
odors, smoke, gases, grease and dirt as the cooking load changes. As will be evident,
even when the flow of makeup air to the exhaust duct 47, such as supplied from an
air intake duct 48, is so regulated, there will be times during which the amount of
smoke produced by the cooking equipment and the additional heat arising from the cooking
equipment, due to the combustion which produces the smoke, may cause the temperature
of the air and the products of cooking and combustion to increase sufficiently that
its expansion prevents the exhaust duct and its fan or blower, even operating at maximum
capacity, from removing all of the smoke from inside the hood, which then will cause
the smoke to curl under the edges of the hood and flow into the room.
[0017] As indicated previously, it would be assumed that under such conditions, the provision
of apertures at and adjacent the lower edges of the outer walls of the hood would
permit even more smoke to pour into the room. However, as also indicated, the reverse
will be true, since the flow of cooler air through the apertures 10 and 11 will tend
to cool the products of cooking and combustion, thereby decreasing the volume of air
and other gases within the hood and causing additional air to flow through the apertures
and into the duct, as well as preventing any smoke from curling out from under the
lower edges of the hood walls.
[0018] In addition to the walls 45 and 46, the exhaust duct 47 and air inlet duct 48, referred
to above, the exterior of the ventilator, as in Fig. 4, includes an upper front wall
49 and a manifold M from which tempered air is discharged into the room. The interior
of the ventilator Vʹ, as in Fig. 5, includes an upper inlet baffle 50, between which
and a lip or curl 51 at the upper end of a front plate 52, flow the air and products
of coo king and perhaps combustion, pulled by the exhaust fan out through
exhaust duct 47. The lower edge of front plate 52 is connected to a bottom plate 53,
which, in turn, is connected to a rear wall 54. The gases flow between front plate
52 and a downwardly extending baffle 55, which extends from inlet baffle 50 and has
a depending flange or lip 56 at the bottom, around which the incoming gases drive
the water of a water bath, which normally extends to a level indicated by the dotted
line 57, but is driven rearwardly against the back wall 54. The normal level of water
is determined by an overflow 58 connected to a base 59, in turn connected to an outlet
60.
[0019] In a manner similar to the ventilator V of Fig. 1, the gas stream will agitate the
water and churn it up into tongues, thereby condensing vapors which are condensable,
such as grease, then flow upwardly against a horizontal baffle 61 having a downwardly
slanting lip or flange 62, which tends to strip droplets of water or other liquid
from the gas stream, such droplets falling onto the top of upper entrance baffle 50
to flow back down into the water bath. Baffle 61 is supported by a series of spaced
braces 63, while a front panel 64 and a top panel 65 complete the compartment into
which the air and products of cooking flow. The latter, after being stripped of liquid
droplets by flange 62, proceed upwardly to pass through a mist eliminator E, which
is formed of woven or unwoven mesh, wire or the like, held by a pair of screens. Upward
flow of these gaseous products continues into the discharge duct 47, past a fire damper
67 carrying a weight 68 and pivoted on a rod 69. The lower end of the damper is connected
to a wire 70, which extends to front wall 64 and in which a fuse link 71 is interposed,
so that if the temperature rises sufficiently to melt the fuse link, as the result
of fire, the base of the damper will be released and the weight 68 will cause the
damper to fall to a closed position. For cleaning purposes, a series of nozzles 72
may be mounted at appropriate positions on the rear wall 54 and the front wall 64,
to spray the front wall and the top of baffle 61, as well as the bottom of baffle
61, the rear wall 54 below baffle 61 and the top of baffle 50. This will tend to clean
any collected grease off the interior walls of the compartment through which the air
and products of cooking flow.
[0020] A principal temperature control device 73 may be mounted adjacent the intake of exhaust
duct 47 and a secondary tempereature responsive control device 74 on the underside
of a panel 75, which extends forwardly from baffle 50, so as to be responsive respectively
to the temperature of exhaust gases just prior to entering the exhaust duct and the
temperature of the exhaust gases just prior to flowing into the grease removal compartment
of the grease extraction ventilator. A panel 76 may extend from panel 75 to lower
front wall 45 to complete the open bottomed enclosure in which air and products of
cooking are collected for flow into the ventilator. A light 77 may be installed above
panel 76, to illuminate the enclosure. A pump and motor 78, illustrated diagrammatically,
transfer the water of the water bath, heated by flow of heated gases therethrough,
to a series of heat exchangers H and supplied by a header 79, with return flow through
a header 80 to the water bath. The normally fresh air supplied to air intake duct
48 passes into a plenum chamber P flanked by a front wall 81 and an insulated rear
wall 82. A bypass duct 83 extends between chamber P and the exhaust duct 47, with
a pivotally mounted damper 84 controlling the flow from plenum chamber P to exhaust
duct 47. The control will increase the flow of bypass air when the temperature at
primary control device 73 decreases and will decrease the flow of bypass air when
the temperature at the primary control device increases. The secondary control device
74 may be utilized to increase or decrease the flow of bypass air when the temperature
at control device 73 has not change d but the temperature at control device
74 suddenly increases or decreases. In other words, the control device 74 is utilized
to anticipate a change in temperature at control device 73, which has not yet reached
it. The water transferred by pump 78 to the heat exchangers H through which the air
from plenum chamber P flows into an outer compartment 85, will be heated in the winter
time, since the water through which the heated air and products of cooking flow, will
normally be heated to a temperature higher than that of outside air. However, during
the summer time, when the outside air temperature is higher than the temperature of
the water bath, the incoming air will be cooled. The air thus tempered flows into
the manifold M and is discharged into the room, through bottom louvres 86, downwardly
alongside the upper front wall 49 and the lower front wall 45, while additional tempered
air will flow through upper louvres 87 for discharge along the ceiling of the room.
Air which flows through louvres 86 may flow into the room, or into the hood through
slots 10 and 11 or underneath the lower edge of the lower front wall 45.
[0021] The method of this invention may also be applied to a ventilator having a so-called
"dry" type of filter, such as the ventilator Vʺ of Figs. 8-11 having a filter F of
the mesh type through which the heated gases and products of cooking pass from the
cooking equipment for entrapment of smoke particles, moisture or the like, to an exhaust
duct 90. The ventilator Vʺ, in accordance with this invention, is provided with a
series of slots 10 disposed in parallel rows, alternating with slots 11 disposed in
parallel rows, above the lower edges of a front wall 91, as in Figs. 8 and 10, an
end wall 92, as in Figs. 9 and 10, and an opposite end wall 93, as in Fig. 11. The
heated products of cooking, as well as some room air, pass into the bonnet surrounded
on three sides by walls 91, 92 and 93, for passage through filter F to exhaust duct
90 in the direction of the arrows of Fig. 9, drawn by a conventional exhause blower
(not shown) disposed at an appropriate position at the end of duct 90. The slots 10
and 11, in the respective walls, as before, act to permit the flow of cooler room
air through the slots into the bonnet for cooling heated gases and thereby causing
the volume to decrease and the cooler gases to flow more readily through filter F
to the exhaust duct 90, thereby avoiding the curling of smoke around the underside
of front wall 91 or end wall 92 or 93 when the production of heated gases and smoke
is greater than the exhaust blower can accommodate.
[0022] Ventilator Vʺ is provided with a top wall 94 and a rear wall 95, and also a rearwardly
and downwardly slanting upper partition 96 for filter F, as well as a downwardly and
forwardly slanting bottom panel 97. Filter F, or a series of filters in side-by-side
relation, are received in brackets mounted on the lower edge of upper partition 96
and the upper edge of a series of rearwardly and downwardly slanting drain tubes 98,
which collect liquid draining from the filters F and transfer the same to a catch
basis 99. Ordinarily, the ventilator Vʺ is installed against a wall and, for this
purpose, a rear panel 100, at each end, may cover the space between rear wall 95 of
the ventilator and the room wall 101.
[0023] Variations of the smoke curling prevention apertures of this invention may be utilized,
including differences in the apertures and application to various types of grease
extraction ventilators, in addition to those illustrated. One variation in the apertures
is shown in Fig. 12, in which a panel 110, which may be a front, side, end or other
depending panel of a grease extraction ventilator, is provided with a series of circular
holes 111, which are disposed in spaced relation in parallel rows and in offset or
alternating relation to a series of holes 112, which are generally spaced apart in
parallel rows interspaced with the rows of holes 111. It will be noted that the holes
111 a nd 112 may be oval, rectangular, square, triangular, diamond-shaped,
elliptical, trapezoidal, or of any other geometric configuration. In each instance,
the particular shape of the holes does not matter, except that an arrangement of holes
should be provided which causes adequate strength to be retained in the panel or wall
in which the holes are placed.
[0024] In the case of the circular holes of Fig. 11, for instance, the holes may have a
diameter of 3/8 inch and be spaced apart, in each row, on the order of 1/8 inch, with
the distance between diagonally related holes in adjacent rows being on the order
of 1/8 inch. The holes, of course, may follow a different configuration and be straight
in line, while when in parallel rows, the rows may extend at different angles to the
edge of the panel in which placed. It is desirable, of course, to maintain as many
holes as possible fairly close to the lower edge of each panel in the wall in which
placed, with the distance between and relative placement of the holes involving a
consideration of the strength of the resultant structure and its ability to withstand
the stresses to which the walls of the ventilator would be subjected.
[0025] It is noted that the embodiment of Figs. 1-3 and Figs. 4-7 are shown with six rows
of apertures, while the embodiment of Figs. 8-11 is shown with five rows of apertures
and the variation of Fig. 12 is shown with seven rows of apertures. It will thus be
understood that any desired number of rows, as well as other arrangements of the aperture,
may be utilized.
[0026] It will further be understood that, although several embodiments and variations of
the type of grease extraction ventilator to which the principles of this invention
may be applied, have been illustrated and described, other embodiments may exist and
the principles applied to other types of grease extraction ventilators without departing
from the spirit and scope of this invention.
1. A method of preventing smoke curling from beneath a hood of a grease extraction
ventilator installed in a room above cooking equipment and having depending walls
including a front wall and end walls essentially surrounding an enclosure into which
pass heated air and products of cooking, then through means for removing water, grease
and other products of cooking, to an exhaust duct to which suction is applied, comprising:
providing a series of apertures in at least the lower portion of said front wall from
adjacent the lower edge thereof for a predetermined distance upwardly, said apertures
being comparatively small and relatively closely spaced, whereby room air passes through
said apertures into said enclosure.
2. A method as defined in claim 1, which includes:
providing a series of apertures in rows with apertures of one row alternating in position
with apertures in adjacent rows.
3. A method as defined in claim 2, which includes:
providing said rows in parallel relation to said lower edge of the corresponding wall.
4. A method as defined in claim 3, which includes:
providing apertures having a shape selected from slots and circular holes.
5. A method as defined in claim 1, wherein:
a sufficient volume of air at a sufficiently low temperature flows through said apertures
from said room to cool a sufficient amount of heated air and products of combustion
within said enclosure so that the volume of gases within said enclosure is decreased
and the velocity of flow to said exhaust duct is increased.
6. A device for preventing smoke curling from beneath a hood of a grease extraction
ventilator installed in a room above cooking equipment and having depending walls
including a front wall and end walls essentially surrounding an enclosure into which
pass heated air and products of cooking, then through means for removing water, grease
and other products of cooking, to an exhaust duct to which suction is ap
plied, comprising:
a series of apertures in at least the lower portion of said front wall from adjacent
the lower edge thereof for a predetermined distance upwardly, said apertures being
comparatively small and relatively closely spaced, whereby room air passes through
said apertures into said enclosure.
7. A device as defined in claim 6, wherein:
said grease extraction ventilator is provided with dry means for removing products
of cooking.
8. A device as defined in claim 6, wherein:
said grease extraction ventilator is provided with water means for removing products
of cooking.
9. A device as defined in claim 6, wherein:
the lower edges of said end walls slant upwardly; and
said apertures are disposed in rows parallel to said lower edges.
10 A device as defined in claim 6, wherein:
said walls provided with said apertures include at least the lower portion of said
depending end walls.
11. A device as defined in claim 6 including:
means for discharging makeup air for said room downwardly along at least one of said
walls having said apertures.