CA1069749A - Ventilating apparatus - Google Patents
Ventilating apparatusInfo
- Publication number
- CA1069749A CA1069749A CA294,548A CA294548A CA1069749A CA 1069749 A CA1069749 A CA 1069749A CA 294548 A CA294548 A CA 294548A CA 1069749 A CA1069749 A CA 1069749A
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- air
- chamber
- exhaust
- intake
- intake chamber
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Abstract
Abstract of The Disclosure Ventilating apparatus having an exhaust hood for mounting in a room and normally above a stove, grill, or other apparatus from which fumes arise. Ambient air from outside the room being ventilated is forced into an insulated intake chamber through a relatively narrow longitudinal slot at the bottom of the intake chamber, thence directed rear-wardly and upwardly across a fume collection chamber, through a grease filter, and into an exhaust chamber from which the fumes are exhausted to the atmosphere by a fan.
The outside air is forced through the slot in a fast moving narrow stream to form an air curtain across the fume collec-tion chamber with minimal mixing of the fume laden air and the air curtain. Tempered air is introduced into the room being ventilated adjacent the exhaust hood to provide a minimum influx of tempered air from the room being ventilated into the hood to prevent dissipation fumes into the room, and to facilitate collection of such fume laden air by the exhaust hood.
The outside air is forced through the slot in a fast moving narrow stream to form an air curtain across the fume collec-tion chamber with minimal mixing of the fume laden air and the air curtain. Tempered air is introduced into the room being ventilated adjacent the exhaust hood to provide a minimum influx of tempered air from the room being ventilated into the hood to prevent dissipation fumes into the room, and to facilitate collection of such fume laden air by the exhaust hood.
Description
Field of the Invention This invention pertains generally to ventilating . apparatus having an exhaust hood.
,' ..
Descriptian of the~Prior Art Exhaust hoods in restaurant kitchens and the like consist of a hood having an exhaust fan for drawing fume laden air upwardly into the hood and through a filter.
S The amount of air which must be withdrawn is often prescribed by building codes which may t~pically require that lO0 cubic feet per minute be exhausted for every square foot of hood opening area. The removal of conditioned room air places a great load on the heating and air conditioning equipment and is therefore very uneconomical and wasteful of energy~
Auxiliary air may be introduced directly into the hood to reduce the conditioned room air removed, but known systems have not been satisfactory.
Summary of the Invention The novel ventilating apparatus supplies a major portion, preferably about 80%, of the air that must be exhausted through the hood from untempered air which it draws directly from the environment outside the room.
This "free" outside air, never leaves the hood area. ~nly about 20% of the total air requirement for ventilation is tempered air which in a further aspect of the invention is diffused into the room adjacent the hood from the main heat-ing or air-conditioning system thereby eliminating the need for a make-up air unit. Accordingly my appara~us conserves considerable energy because it permits the use of primarily untempered outside air to ventilate the cooking area. The extensive use of cool outside air also reduces air pollution in that it causes grease to congeal and collect on the grease filter so that the air exhausted is cleaner. My apparatus also reduces the accumulation of grease in the ducts and on the roof of the building.
1069t749 Generally, in one feature of the present invention, a hood enclosure includes a fume collection chamber having a bottom opening and with a unique air intake chamber and an air exhaust chamber on opposite sides. A filter forms a common wall between the collection and exhaust chambers.
An air intake unit and an air exhaust unit are provided in the chambers to introduce untempered air and to remove fume laden air from the fume collection chamber. The air intake chamber converges downwardly to increase the velocity of the air and connects to a lateral discharge passageway along the lower portion of the fume collection chamber. The discharge passageway includes a smooth, curved lower deflection wall and an upper wall to smoothly and continuously deflect the air from the downward flow laterally and then at an upward angle to the horizontal. The air flow from the passageway is an upwardly inclined air curtain of fast moving air across the fume collection chamber to the filter and exhaust chambers.
The chambers may be formed by inclined walls located within suitable outer enclosure walls. Intake chamber walls are pre-ferably insulated.
The air curtain functions in a manner similar toan ejector pump and causes the pressure inside the fume collection chamber to be reduced below that which it would be at if only the exhaust unit were providing the suction therein. As a result the fume laden air arising from the cooking surface is drawn into the fume collection chamber and is exhausted through the exhaust unit with more effici-ency than would be the case if only the exhaust unit were being utilized. The passageway has a relatively narrow depth in order to create a narrow, fast moving air stream. This ~069749 air curtain prevents penetration thereof by the fumes and provides an air pressure differential between the moving stream and the surrounding ambient air. In accor~ance with an additional, novel feature and aspect of the invention~ a source of tempered secondary air is injected into the room essentially about the enclosure and directed toward the lower end of the hood to create an air flow which entraps and carries fume laden air into the hood rather than allowing it to become dispersed into the room.
Further objects, features and advantages of my invention will be apparent from the following detailed de-scription taken in conjunction with the accompanying drawings, showing a preferred embodiment of an exhaust hood ventilating apparatus exemplifying the principles of my invention.
Brief Description of the Drawings In the drawings:
Fig. 1 is a perspective view of my exhaust hood ventilating apparatus located above a stove or other cooking surface;
Fig. 2 is a perspective view of a portion of the apparatus of Fig. l;
Fig. 3 is a view taken generally along line 3-3 of Fig. ~; and Fig. 4 is a view showing an island unit employing this invention.
Description of the Preferred Embodiment In Fig. 1, an exhaust hood apparatus 10 has a sub-stantially rectangular hood enclosure 11 to be secured to a wall above a stove or grill 12 in a kitchen. The enclosure 11 has a front longitudinal wall lla, a rear longitudinal wall llb, two ~ide walls llc and a top wall lld. The enclosure 11 has an open bottom preferably somewhat larger than the area of the grill or stove in order to insure that a maximum amount of vapors and grease particles rising upwardly will be entrapped and pulled into the hood apparatus. Other than the rectangular configuration may be utilized provided that the bottom opening is adequately sized and shaped to collect the rising vapors and fumes.
As best shown in Figs. 2 and 3, the enclosure 11 is divided into three chambers.
The several walls of the hood apparatus 10 are preferably made of heavy gauge sheet metal such as rolled steel or stainless stell, to provide physical strength and resistance to fire. The walls are preferably welded together, although other methods of attachment may be utilized.
As shown in Figs. 2 and 3, interior walls 13 and 14 slant toward one another toward the top of the hood enclosure in a general inverted V-shape. An intake chamber 15 is formed between walls lla, llc and lld. Chamber 15 receives untempered air under pressure which passes from the air intake fan 16 (Fig. 1) through a duct 17 to an opening in the top wall lld and then across chamber 15.
In Fig. 3, the air intake chamber 15 continually converges from the top end of the chamber to the bottom end thereof.
This results in a smooth increase in the velocity of the air at the bottom over the velocity of the air entering the intake chamber. The air pressure and velocity is preferably evenly distributed throughout the length of the intake chamber 15 by an apertured distributor plate 18 across the tope end and having a plurality of holes, preferably uniformly distributed. Plate lg minimizes differences in velocity between the air that is exiting from the intake chamber directly under the entrance of the duct 17 and the air that is exiting from the intake chamber at the far ends of the S chamber away from the duct opening. Walls of chamber 15 are advantageously insulated with material such as a fiber-glass mat 19, to thereby prevent excessive cooling which might create excessive condensation of moisture and grease on the enclosure walls and interior walls.
A fume collection chamber 20 with a bottom opening is defined by the interior walls 13 and 14 and the sidewalls llc and is positioned to collect fumes, particles and heated air arising from stove 12. The fumes are passed through an opening 14a in wall 14 into an exhaus~ chamber 21 defined by the walls 14, llb and llc. The fumes are drawn up through a duct 22 by an exhaust fan 23 which exhausts the fumes into the atmosphere. Fan 23 is sufficient in capacity to lower the air pressure in the exhaust chamber 21 substantially below that of the surround-ing atmosphere. A grease filter 24 is mounted in the open-ing 14a between chamber 20 and chamber 21 to remove a substantial portion of the grease. The filter 24 for a kitchen may be any of the commonly employed types of grease filters, which, for example, may utilize a stainless steel mesh, and should extend substantially the length and width of the wall 14 to allow maximum collection of fumes in the filter.
The air in chamber 15 is deflected into the chamber 20 by a unique lateral discharge passageway and out therefrom through the filter 24. The passageway .
includes a deflector panel 25, of sheet metal or other suitable material, which is mounted at the bottom end of the intake chamber and extends substantially the length of the bottom end of the intake chamber. Panel 25 is curved along its width in a general U-shape and has a suffi-cient curvature to smoothly deflect and redirect the air from chamber 15 into the fume collection chamber 20 in a direction at an angle upward from the horizontal~ A
throat panel 26 is mounted on the bottom end of the first interior wall 13 and extends substantially the length of the bottom end of the intake chamber. As shown in Fig. 3, the throat panel 26 has horizontal portion 26a which is attached to the first interior wall 13 and extends inwardly into the fume collection chamber 20, and a portion 26b which is bent upward from the horizontal portion. The throat panel is mounted in proximity to the end of the develctor panel 25 and the passageway ends in a narrow slot therebetween. The deflector panel 25 is continuously curved to continuously and smoothly deflect the air coming in contact therewith from the narrow lower end of chamber 15 and to pass this air smoothly and continuously out through the slot. The discharge passageway is desirably convergent toward the slot, as shown in Fig. 3, to continuously increase the velocity of the air advancing in the intake chamber toward the slot.
The dimensions of the slot between the deflector panel 25 and the throat panel 26 are important to the proper operation of my exhaust ventilating apparatus 10. I have determined that for normal kitchen ventilation usage it is preferably that the slot width be no more than about two 106974~
inches wide, in which case the maximum velocity of the air flowing out of the slot would be in ~he range of 950 ft./min-ute. A one inch slot can be utilized by increasing the air flow to a maximum velocity of about 1250 ft./minute. The slot between the throat panel 26 and deflector panel 25 should be so oriented that the stream or curtain of air emerging therefrom strikes the grease filter 24 approximately perpendicular thereto.
~s shown in Fig. 3, the throat panel 26 may have an upturned portion 26b to also act as a grease gutter or trough for grease that may congeal and sccumulate on the first interior wall 13. The throat panel 26 may decline slightly from one end of the hood enclosure to the other so that grease accumulating on the throat panel may flow to a grease collector (not shown) where it can be removed. A
similar grease gutter 27 is also provided at the bottom of the rear wall llb. A horizontal bottom panel 28 i5 located underneath the deflector panel 25 and is preferably kept fairly narrow so that the major portion of ~he fumes arising from the stove flow naturally up into the chamber 20.
If all of the air exhausted from the hood were provided from the conditioned air in the room, a substantial heat loss during the winter and a similar cooling loss during the summer would result. The moving stream of air issuing from the slot between panels 25 and 26 in my ventilating apparatus 10 will tend to mix somewhat with the air which it is in contact with and will carry this air and any particles of grease or fumes which are intermixed therewith into the grease filter 24 and therethrough to the exhause chamber 21.
~y ventilating hood apparatus will thus draw more fume laden 106~3749 air into the exhaust chamber 21 than would a similar exhaust hood apparatus without the stream of forced air which utilized only the suction produced by the exhaust fan 23. Since the air that is discharged through the slot is provided from outside air and does not require heating or cooling in any way, there is a very substantial decrease in the heat load on the heating and air conditioning system.
I have determined that my exhaust hood ventilating apparatus functions most efficiently when approximately 80%
of the air drawn out through the exhaust fan 23 is provided by air forced through the slot between the throat panel 26 and the deflector plate 25, and 20% of such air is provided by heated or cooled air which is forced into the room in which the exhaust hood ventilating apparatus 10 is situated.
In the illustrated embodiment, this heated or cooled air is provided by the ducts 29 wherein a continuous outlet or spaced outlets for the tempered air are provided a various positions around the ventilating enclosure. The secondary source of tempered air preferably forced into the room at "a short distance from the exhaust hood enclosure and above the opening, creates an auxiliary flow toward the exhaust hood opening to entrain the particles of air and pull them into the hood rather than allowing them to disperse through-out the room. This auxiliary air is preferably forced into the room rather than simply being drawn in by suction from the ventilating apparatus.
As mentioned above, it is most desirable that the slot between the throat panel and the deflector panel be less than approximately two inches wide for the volumes of air normally exhausted in hoods utilized in kitchens and other 106~749 similar applications. The narrow stream o~ air issuing from the slot will not tend to disperse substantially before reaching the grease filter 24. For a narrow slot and wherein the deflector panel and the throat panel con-verge smoothly and continuously toward the slot, the airstream issuing therefrom can develop substantially laminar flow for some distance from the slot. The capability of ob-taining laminar flow is enhanced because the air issuing from the slot is issuing into a moving stream of air produced by the air being drawn up into the exhaust chamber 21 and through the fan 23. Thus the relative velocity of the air issuing from the slot and the surround-ing ambient air is less than the absolute velocity at which the air exists from the slot. Even if the flow issuing from the slot is turbulent, the flow will be relatively narrow and fast moving with minimal development of vortexes and eddys. Such smooth flow is desirable since it avoids ex-tensive mixing of the air curtain with the fume laden air arising from below, and also avoids penetration of the air curtain by the fume laden air so that very little of the fumes reach the interior walls 13 and 14. It is desirable to minimize the vortexing of the fume laden air, since such vortexing results in deposits of grease on the interior walls and also substantially reduces the pressure drop developed in the fume collection chamber 20.
It is preferable that the second interior wall 14 be at an angle greater than 45~ with the horizontal so that grease that does accumulate either on the filter 24 or on the interior wall 14 flows downwardly into the grease gutter 27 or is trapped in the filter, and does not form into large _g_ droplets which fall from the interior wall into the food preparation surface below.
In Fig. 4, the present invention is sho~m applied to an island unit which is spaced from the several walls of a room and permits the user to move completely about the grill 12.
In Fig. 4, corresponding elements of the embodiment of Figs. 1 -3 will be identified by corresponding numbers for simplicity and clarity.
In the embodiment of Fig. 4, the hood apparatus 10 includes a substantially rectangular hood enclosure 11 adapted to be secured from the celing above the island type grill 12.
Within the enclosure, a first fume collection chamber 20 is formed to one side of the unit and second similar fume collection chamber 20' is formed to the opposite side. The collection chamber 20 is formed by walls 13 and 14. Fume collection chamber 20' is similarly formed by reversely positioned walls 13' and 14' suc'n that the filters 24 and 24' are located adjacent to the central portion of the rectangular enclosure 11. They form the opposite side walls of a centrally located exhaust chamber 21.
~0 A common duct 22 is operative to exhaust the fumes into the atmosphere. Supply chambers 15 and 15' are similarly formed to the opposite ends of the rectangular enclosure and are connected to individual air entrance ducts 1/ and 17'. These ducts may be supplied from a common fan or from individual fans. The fume collection chambers 20 and ~0' are thus constructed as essentially mirror images about a central vertical plane. In accordance with the embodiment of the invention, a continuous secondary tempered air duct 29 is mounted in complete encircle-ment about the hood enclosure 11. The duct 29 is located in upwardly spaced relation to the lower end of the enclosure 11 and is provided with an éssentially continuous bottom air diffuser opening which developes a soft velocity air curtain about the total hood enclosure. The air flow is shown by both solid and dotted lines ~0, with the dotted lines indicating the air flow to the backside of the encircling duct 29. The secondary tempered air difusser is located in upward relation and particularly, generally at the ceiling line. The spaced location results in significant reduction in the velocity so as to avoid objectionable drafts over the cooks and other personnel. In a preferred constru~
ction as applied to a kitchen area, the secondary tempered air again is selected to provide about 20% of the total air exhausted by the hood apparatus, the other gO% being supplied via the ducts 17 and 17' The invention with the ability of minimizing drafts and dispersion of the fumes has been found to be particularly significant in island units where they may be located centrally of the room and particularly subjected to the effects of door openings and the like.
This application is a division of Canadian applica-tion Serial No. 246,367 filed February 23, 1976.
,' ..
Descriptian of the~Prior Art Exhaust hoods in restaurant kitchens and the like consist of a hood having an exhaust fan for drawing fume laden air upwardly into the hood and through a filter.
S The amount of air which must be withdrawn is often prescribed by building codes which may t~pically require that lO0 cubic feet per minute be exhausted for every square foot of hood opening area. The removal of conditioned room air places a great load on the heating and air conditioning equipment and is therefore very uneconomical and wasteful of energy~
Auxiliary air may be introduced directly into the hood to reduce the conditioned room air removed, but known systems have not been satisfactory.
Summary of the Invention The novel ventilating apparatus supplies a major portion, preferably about 80%, of the air that must be exhausted through the hood from untempered air which it draws directly from the environment outside the room.
This "free" outside air, never leaves the hood area. ~nly about 20% of the total air requirement for ventilation is tempered air which in a further aspect of the invention is diffused into the room adjacent the hood from the main heat-ing or air-conditioning system thereby eliminating the need for a make-up air unit. Accordingly my appara~us conserves considerable energy because it permits the use of primarily untempered outside air to ventilate the cooking area. The extensive use of cool outside air also reduces air pollution in that it causes grease to congeal and collect on the grease filter so that the air exhausted is cleaner. My apparatus also reduces the accumulation of grease in the ducts and on the roof of the building.
1069t749 Generally, in one feature of the present invention, a hood enclosure includes a fume collection chamber having a bottom opening and with a unique air intake chamber and an air exhaust chamber on opposite sides. A filter forms a common wall between the collection and exhaust chambers.
An air intake unit and an air exhaust unit are provided in the chambers to introduce untempered air and to remove fume laden air from the fume collection chamber. The air intake chamber converges downwardly to increase the velocity of the air and connects to a lateral discharge passageway along the lower portion of the fume collection chamber. The discharge passageway includes a smooth, curved lower deflection wall and an upper wall to smoothly and continuously deflect the air from the downward flow laterally and then at an upward angle to the horizontal. The air flow from the passageway is an upwardly inclined air curtain of fast moving air across the fume collection chamber to the filter and exhaust chambers.
The chambers may be formed by inclined walls located within suitable outer enclosure walls. Intake chamber walls are pre-ferably insulated.
The air curtain functions in a manner similar toan ejector pump and causes the pressure inside the fume collection chamber to be reduced below that which it would be at if only the exhaust unit were providing the suction therein. As a result the fume laden air arising from the cooking surface is drawn into the fume collection chamber and is exhausted through the exhaust unit with more effici-ency than would be the case if only the exhaust unit were being utilized. The passageway has a relatively narrow depth in order to create a narrow, fast moving air stream. This ~069749 air curtain prevents penetration thereof by the fumes and provides an air pressure differential between the moving stream and the surrounding ambient air. In accor~ance with an additional, novel feature and aspect of the invention~ a source of tempered secondary air is injected into the room essentially about the enclosure and directed toward the lower end of the hood to create an air flow which entraps and carries fume laden air into the hood rather than allowing it to become dispersed into the room.
Further objects, features and advantages of my invention will be apparent from the following detailed de-scription taken in conjunction with the accompanying drawings, showing a preferred embodiment of an exhaust hood ventilating apparatus exemplifying the principles of my invention.
Brief Description of the Drawings In the drawings:
Fig. 1 is a perspective view of my exhaust hood ventilating apparatus located above a stove or other cooking surface;
Fig. 2 is a perspective view of a portion of the apparatus of Fig. l;
Fig. 3 is a view taken generally along line 3-3 of Fig. ~; and Fig. 4 is a view showing an island unit employing this invention.
Description of the Preferred Embodiment In Fig. 1, an exhaust hood apparatus 10 has a sub-stantially rectangular hood enclosure 11 to be secured to a wall above a stove or grill 12 in a kitchen. The enclosure 11 has a front longitudinal wall lla, a rear longitudinal wall llb, two ~ide walls llc and a top wall lld. The enclosure 11 has an open bottom preferably somewhat larger than the area of the grill or stove in order to insure that a maximum amount of vapors and grease particles rising upwardly will be entrapped and pulled into the hood apparatus. Other than the rectangular configuration may be utilized provided that the bottom opening is adequately sized and shaped to collect the rising vapors and fumes.
As best shown in Figs. 2 and 3, the enclosure 11 is divided into three chambers.
The several walls of the hood apparatus 10 are preferably made of heavy gauge sheet metal such as rolled steel or stainless stell, to provide physical strength and resistance to fire. The walls are preferably welded together, although other methods of attachment may be utilized.
As shown in Figs. 2 and 3, interior walls 13 and 14 slant toward one another toward the top of the hood enclosure in a general inverted V-shape. An intake chamber 15 is formed between walls lla, llc and lld. Chamber 15 receives untempered air under pressure which passes from the air intake fan 16 (Fig. 1) through a duct 17 to an opening in the top wall lld and then across chamber 15.
In Fig. 3, the air intake chamber 15 continually converges from the top end of the chamber to the bottom end thereof.
This results in a smooth increase in the velocity of the air at the bottom over the velocity of the air entering the intake chamber. The air pressure and velocity is preferably evenly distributed throughout the length of the intake chamber 15 by an apertured distributor plate 18 across the tope end and having a plurality of holes, preferably uniformly distributed. Plate lg minimizes differences in velocity between the air that is exiting from the intake chamber directly under the entrance of the duct 17 and the air that is exiting from the intake chamber at the far ends of the S chamber away from the duct opening. Walls of chamber 15 are advantageously insulated with material such as a fiber-glass mat 19, to thereby prevent excessive cooling which might create excessive condensation of moisture and grease on the enclosure walls and interior walls.
A fume collection chamber 20 with a bottom opening is defined by the interior walls 13 and 14 and the sidewalls llc and is positioned to collect fumes, particles and heated air arising from stove 12. The fumes are passed through an opening 14a in wall 14 into an exhaus~ chamber 21 defined by the walls 14, llb and llc. The fumes are drawn up through a duct 22 by an exhaust fan 23 which exhausts the fumes into the atmosphere. Fan 23 is sufficient in capacity to lower the air pressure in the exhaust chamber 21 substantially below that of the surround-ing atmosphere. A grease filter 24 is mounted in the open-ing 14a between chamber 20 and chamber 21 to remove a substantial portion of the grease. The filter 24 for a kitchen may be any of the commonly employed types of grease filters, which, for example, may utilize a stainless steel mesh, and should extend substantially the length and width of the wall 14 to allow maximum collection of fumes in the filter.
The air in chamber 15 is deflected into the chamber 20 by a unique lateral discharge passageway and out therefrom through the filter 24. The passageway .
includes a deflector panel 25, of sheet metal or other suitable material, which is mounted at the bottom end of the intake chamber and extends substantially the length of the bottom end of the intake chamber. Panel 25 is curved along its width in a general U-shape and has a suffi-cient curvature to smoothly deflect and redirect the air from chamber 15 into the fume collection chamber 20 in a direction at an angle upward from the horizontal~ A
throat panel 26 is mounted on the bottom end of the first interior wall 13 and extends substantially the length of the bottom end of the intake chamber. As shown in Fig. 3, the throat panel 26 has horizontal portion 26a which is attached to the first interior wall 13 and extends inwardly into the fume collection chamber 20, and a portion 26b which is bent upward from the horizontal portion. The throat panel is mounted in proximity to the end of the develctor panel 25 and the passageway ends in a narrow slot therebetween. The deflector panel 25 is continuously curved to continuously and smoothly deflect the air coming in contact therewith from the narrow lower end of chamber 15 and to pass this air smoothly and continuously out through the slot. The discharge passageway is desirably convergent toward the slot, as shown in Fig. 3, to continuously increase the velocity of the air advancing in the intake chamber toward the slot.
The dimensions of the slot between the deflector panel 25 and the throat panel 26 are important to the proper operation of my exhaust ventilating apparatus 10. I have determined that for normal kitchen ventilation usage it is preferably that the slot width be no more than about two 106974~
inches wide, in which case the maximum velocity of the air flowing out of the slot would be in ~he range of 950 ft./min-ute. A one inch slot can be utilized by increasing the air flow to a maximum velocity of about 1250 ft./minute. The slot between the throat panel 26 and deflector panel 25 should be so oriented that the stream or curtain of air emerging therefrom strikes the grease filter 24 approximately perpendicular thereto.
~s shown in Fig. 3, the throat panel 26 may have an upturned portion 26b to also act as a grease gutter or trough for grease that may congeal and sccumulate on the first interior wall 13. The throat panel 26 may decline slightly from one end of the hood enclosure to the other so that grease accumulating on the throat panel may flow to a grease collector (not shown) where it can be removed. A
similar grease gutter 27 is also provided at the bottom of the rear wall llb. A horizontal bottom panel 28 i5 located underneath the deflector panel 25 and is preferably kept fairly narrow so that the major portion of ~he fumes arising from the stove flow naturally up into the chamber 20.
If all of the air exhausted from the hood were provided from the conditioned air in the room, a substantial heat loss during the winter and a similar cooling loss during the summer would result. The moving stream of air issuing from the slot between panels 25 and 26 in my ventilating apparatus 10 will tend to mix somewhat with the air which it is in contact with and will carry this air and any particles of grease or fumes which are intermixed therewith into the grease filter 24 and therethrough to the exhause chamber 21.
~y ventilating hood apparatus will thus draw more fume laden 106~3749 air into the exhaust chamber 21 than would a similar exhaust hood apparatus without the stream of forced air which utilized only the suction produced by the exhaust fan 23. Since the air that is discharged through the slot is provided from outside air and does not require heating or cooling in any way, there is a very substantial decrease in the heat load on the heating and air conditioning system.
I have determined that my exhaust hood ventilating apparatus functions most efficiently when approximately 80%
of the air drawn out through the exhaust fan 23 is provided by air forced through the slot between the throat panel 26 and the deflector plate 25, and 20% of such air is provided by heated or cooled air which is forced into the room in which the exhaust hood ventilating apparatus 10 is situated.
In the illustrated embodiment, this heated or cooled air is provided by the ducts 29 wherein a continuous outlet or spaced outlets for the tempered air are provided a various positions around the ventilating enclosure. The secondary source of tempered air preferably forced into the room at "a short distance from the exhaust hood enclosure and above the opening, creates an auxiliary flow toward the exhaust hood opening to entrain the particles of air and pull them into the hood rather than allowing them to disperse through-out the room. This auxiliary air is preferably forced into the room rather than simply being drawn in by suction from the ventilating apparatus.
As mentioned above, it is most desirable that the slot between the throat panel and the deflector panel be less than approximately two inches wide for the volumes of air normally exhausted in hoods utilized in kitchens and other 106~749 similar applications. The narrow stream o~ air issuing from the slot will not tend to disperse substantially before reaching the grease filter 24. For a narrow slot and wherein the deflector panel and the throat panel con-verge smoothly and continuously toward the slot, the airstream issuing therefrom can develop substantially laminar flow for some distance from the slot. The capability of ob-taining laminar flow is enhanced because the air issuing from the slot is issuing into a moving stream of air produced by the air being drawn up into the exhaust chamber 21 and through the fan 23. Thus the relative velocity of the air issuing from the slot and the surround-ing ambient air is less than the absolute velocity at which the air exists from the slot. Even if the flow issuing from the slot is turbulent, the flow will be relatively narrow and fast moving with minimal development of vortexes and eddys. Such smooth flow is desirable since it avoids ex-tensive mixing of the air curtain with the fume laden air arising from below, and also avoids penetration of the air curtain by the fume laden air so that very little of the fumes reach the interior walls 13 and 14. It is desirable to minimize the vortexing of the fume laden air, since such vortexing results in deposits of grease on the interior walls and also substantially reduces the pressure drop developed in the fume collection chamber 20.
It is preferable that the second interior wall 14 be at an angle greater than 45~ with the horizontal so that grease that does accumulate either on the filter 24 or on the interior wall 14 flows downwardly into the grease gutter 27 or is trapped in the filter, and does not form into large _g_ droplets which fall from the interior wall into the food preparation surface below.
In Fig. 4, the present invention is sho~m applied to an island unit which is spaced from the several walls of a room and permits the user to move completely about the grill 12.
In Fig. 4, corresponding elements of the embodiment of Figs. 1 -3 will be identified by corresponding numbers for simplicity and clarity.
In the embodiment of Fig. 4, the hood apparatus 10 includes a substantially rectangular hood enclosure 11 adapted to be secured from the celing above the island type grill 12.
Within the enclosure, a first fume collection chamber 20 is formed to one side of the unit and second similar fume collection chamber 20' is formed to the opposite side. The collection chamber 20 is formed by walls 13 and 14. Fume collection chamber 20' is similarly formed by reversely positioned walls 13' and 14' suc'n that the filters 24 and 24' are located adjacent to the central portion of the rectangular enclosure 11. They form the opposite side walls of a centrally located exhaust chamber 21.
~0 A common duct 22 is operative to exhaust the fumes into the atmosphere. Supply chambers 15 and 15' are similarly formed to the opposite ends of the rectangular enclosure and are connected to individual air entrance ducts 1/ and 17'. These ducts may be supplied from a common fan or from individual fans. The fume collection chambers 20 and ~0' are thus constructed as essentially mirror images about a central vertical plane. In accordance with the embodiment of the invention, a continuous secondary tempered air duct 29 is mounted in complete encircle-ment about the hood enclosure 11. The duct 29 is located in upwardly spaced relation to the lower end of the enclosure 11 and is provided with an éssentially continuous bottom air diffuser opening which developes a soft velocity air curtain about the total hood enclosure. The air flow is shown by both solid and dotted lines ~0, with the dotted lines indicating the air flow to the backside of the encircling duct 29. The secondary tempered air difusser is located in upward relation and particularly, generally at the ceiling line. The spaced location results in significant reduction in the velocity so as to avoid objectionable drafts over the cooks and other personnel. In a preferred constru~
ction as applied to a kitchen area, the secondary tempered air again is selected to provide about 20% of the total air exhausted by the hood apparatus, the other gO% being supplied via the ducts 17 and 17' The invention with the ability of minimizing drafts and dispersion of the fumes has been found to be particularly significant in island units where they may be located centrally of the room and particularly subjected to the effects of door openings and the like.
This application is a division of Canadian applica-tion Serial No. 246,367 filed February 23, 1976.
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Ventilating apparatus for ventilating a room which has tempered air introduced therein, comprising, an exhaust hood having an outer enclosing wall and having a fume collection chamber with a bottom opening and having an interior wall means defining an intake chamber on one side of the collection chamber and extending along at least one enclosing wall within said exhaust hood and terminating in the lower portion of the outer enclosing wall in a corres-ponding discharge passageway extending substantially along the length of the bottom of said intake chamber and defining an exhaust chamber within said hood on the opposite side of said collection chamber to said intake chamber, air intake means for drawing air from outside the room being ventilated and forcing such air under pressure into said intake chamber, said intake chamber having front and back walls froming a smooth walled passageway for said air to said discharge passage-way, said discharge passageway having a top wall and including a generally curved bottom deflector surface forming a con-tinuation of said intake chamber to establish and maintain substantially smooth deflection of the air from said intake chamber through said discharge passageway to form a sub-stantially laminar air stream flowing rearwardly and upwardly across said fume collection chamber into said exhaust chamber, and an exhaust unit for drawing air and fumes out of said exhaust chamber and exhausting such air and fumes.
2. The ventilating apparatus of claim 1 wherein said exhaust unit is a powered exhaust means connected to said exhaust chamber and having a capacity to exhaust a minimum of 20% more air by volume than introduced into said intake chamber by said air intake means.
3. The ventilating apparatus of Claim 1 having a distributor means located within the intake means for uniformly distributing the air into the intake chamber.
4. The ventilating apparatus of Claim 1 having a filter located between the fume collection chamber and the exhaust chamber, said deflector surface located to direct the air stream to engage the filter substantially perpendi-cular and defining a pressure condition for drawing air upwardly through said opening, and said front portion of the deflector surface directing said flowing stream to engage the filter in substantial upwardly spaced relation to said bottom opening.
5. The apparatus of Claim 4 wherein said intake chamber is formed with a continuously reduced cross-section to establish a smooth accelerated flow of the air into said discharge passageway and particularly into the back wall portion of the deflector surface for said smooth uninterrupted deflection.
6. The ventilating apparatus of Claim 1 having said bottom deflector surface being a smooth and continuously curved along its width.
7. The ventilating apparatus as specified in Claim 6 including heat insulation material insulating the walls of said intake chamber.
8. The ventilating apparatus of Claim 1 having a grease filter between the collection chamber and the exhaust chamber, said discharge passageway including a throat panel extending substantially along the length of the bottom of said interior wall and a bottom deflector panel also extending substantially along the length of the bottom of said front wall and positioned in spaced relation below said throat panel to form a longitudinally extending slot with said throat panel, the width of said slot being no more than about two inches, said deflector panel being continuously
8. The ventilating apparatus of Claim 1 having a grease filter between the collection chamber and the exhaust chamber, said discharge passageway including a throat panel extending substantially along the length of the bottom of said interior wall and a bottom deflector panel also extending substantially along the length of the bottom of said front wall and positioned in spaced relation below said throat panel to form a longitudinally extending slot with said throat panel, the width of said slot being no more than about two inches, said deflector panel being continuously
Claim 8 (Contd.) and smoothly curved along its width to direct the air stream upwardly through said grease filter and into said exhaust chamber, said exhaust unit having capacity to exhaust a minimum of 20% more air by volume than introduced into said intake chamber by said air intake means.
9. The ventilating apparatus as specified in claim 8 including a distributor means mounted across said intake chamber whereby air forced into said intake chamber by said air intake means is substantially uniformly distri-buted in velocity along the length of said intake chamber as the air passes through said distributor means.
10. The ventilating apparatus of claim 1 wherein said front and back wall of said intake chamber converge downwardly to said discharge passageway, a filter between the collection and exhaust chambers, said bottom deflector surface being a smooth and continuous curve along its width.
11. The ventilating apparatus of claim 10 wherein said exhaust unit comprises powered exhaust means connected to said exhasut chamber and having capacity to exhaust a minimum of 20% more air by volume than introduced into said intake chamber by said air intake means.
12. The ventilating apparatus of claim 10 wherein said intake chamber includes a front and rear wall which are flat and define a progressively reduced cross-section to said discharge passageway.
13. Ventilating apparatus for ventilating a room which as tempered air introduced therein, comprising, an exhaust hood having an outer enclosing wall and having a fume collection chamber with a bottom opening and having an interior wall means defining first and second intake chambers on the opposite sides of the collection chamber,
13. Ventilating apparatus for ventilating a room which as tempered air introduced therein, comprising, an exhaust hood having an outer enclosing wall and having a fume collection chamber with a bottom opening and having an interior wall means defining first and second intake chambers on the opposite sides of the collection chamber,
Claim 13 (Contd.) each intake chamber extending along at least one enclosing wall within said exhaust hood and terminating in the lower portion of the outer enclosing wall in a corresponding discharge passageway extending substantially along the length of the bottom of said intake chamber, an exhaust chamber means within said hood between intake chambers, air intake means for drawing air from outside the room being ventilated and forcing such air under pressure into said intake chambers, each of said intake chamber having front and back walls forming a smooth walled passageway for said air to said discharge passageway, each of said discharge passageways having a top wall and including a generally curved bottom deflector surface forming a continuation of said intake chamber to establish and maintain substantially smooth deflection of the air from said intake chamber through said discharge passageway to form a substantially laminar air stream flowing rear-wardly and upwardly across said fume collection chamber into said exhaust chamber, and an exhaust unit for drawing air and fumes out of said exhaust chamber means and exhausting such air and fumes.
14. The ventilating apparatus of Claim 13 wherein said exhaust unit is a powered exhaust means connected to said exhaust chamber and having a capacity to exhaust a minimum of 20% more air by volume than introduced into said intake chamber by said air intake means, and a distributor means located within the intake means for uniformly distributing the air into the intake chamber.
15. The ventilating apparatus of Claim 13 having said deflector surface located to direct the air stream to engage the filter substantially perpendicular and defining a pressure condition for drawing air upwardly through said
15. The ventilating apparatus of Claim 13 having said deflector surface located to direct the air stream to engage the filter substantially perpendicular and defining a pressure condition for drawing air upwardly through said
Claim 15 (Contd.) opening, and said front portion of the deflector surface directing said flowing stream to engage the filter in substantial upwardly spaced relation to said bottom opening.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA294,548A CA1069749A (en) | 1975-02-24 | 1978-01-09 | Ventilating apparatus |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/552,228 US3978777A (en) | 1975-02-24 | 1975-02-24 | Ventilating apparatus |
| CA246,367A CA1051710A (en) | 1975-02-24 | 1976-02-23 | Ventilating apparatus |
| CA294,548A CA1069749A (en) | 1975-02-24 | 1978-01-09 | Ventilating apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1069749A true CA1069749A (en) | 1980-01-15 |
Family
ID=27164345
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA294,548A Expired CA1069749A (en) | 1975-02-24 | 1978-01-09 | Ventilating apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1069749A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8038515B2 (en) | 2004-07-23 | 2011-10-18 | Oy Halton Group Ltd. | Control of exhaust systems |
| US8734210B2 (en) | 2007-05-04 | 2014-05-27 | Oy Halton Group Ltd. | Autonomous ventilation system |
| US8795040B2 (en) | 2007-08-28 | 2014-08-05 | Oy Halton Group Ltd. | Autonomous ventilation system |
| US9494324B2 (en) | 2008-12-03 | 2016-11-15 | Oy Halton Group Ltd. | Exhaust flow control system and method |
| US9574779B2 (en) | 2008-04-18 | 2017-02-21 | Oy Halton Group, Ltd. | Exhaust apparatus, system, and method for enhanced capture and containment |
-
1978
- 1978-01-09 CA CA294,548A patent/CA1069749A/en not_active Expired
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8038515B2 (en) | 2004-07-23 | 2011-10-18 | Oy Halton Group Ltd. | Control of exhaust systems |
| US8444462B2 (en) | 2004-07-23 | 2013-05-21 | Oy Halton Group Ltd. | Control of exhaust systems |
| US9011215B2 (en) | 2004-07-23 | 2015-04-21 | Oy Halton Group Ltd. | Control of exhaust systems |
| US10184669B2 (en) | 2004-07-23 | 2019-01-22 | Oy Halton Group Ltd | Control of exhaust systems |
| US11242999B2 (en) | 2004-07-23 | 2022-02-08 | Oy Halton Group Ltd. | Control of exhaust systems |
| US8734210B2 (en) | 2007-05-04 | 2014-05-27 | Oy Halton Group Ltd. | Autonomous ventilation system |
| US8795040B2 (en) | 2007-08-28 | 2014-08-05 | Oy Halton Group Ltd. | Autonomous ventilation system |
| US9587839B2 (en) | 2007-08-28 | 2017-03-07 | Oy Halton Group Ltd. | Autonomous ventilation system |
| US10302307B2 (en) | 2007-08-28 | 2019-05-28 | Oy Halton Group Ltd. | Autonomous ventilation system |
| US9574779B2 (en) | 2008-04-18 | 2017-02-21 | Oy Halton Group, Ltd. | Exhaust apparatus, system, and method for enhanced capture and containment |
| US9494324B2 (en) | 2008-12-03 | 2016-11-15 | Oy Halton Group Ltd. | Exhaust flow control system and method |
| US10082299B2 (en) | 2008-12-03 | 2018-09-25 | Oy Halton Group Ltd. | Exhaust flow control system and method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |