Abstract:
A device that augments the capture and containment of an exhaust hood using jets is retrofitable to existing exhaust hoods. The device, in embodiments, forms a self-contained system that is separate from the hood and can be installed in existing hoods providing them with increased performance. Various embodiments are shown which are suitable for canopy and backshelf hood designs.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of provisional Application No. 61/022,302, filed on Jan. 18, 2008, which is incorporated herein by reference. 
     
    
     SUMMARY 
       [0002]    The present embodiments relate to exhaust hoods, features associated with exhaust hoods, and combinations thereof, the features providing air jets that enhance capture efficiency. The embodiments also relate to mechanisms for retrofitting the features to pre-existing exhaust hoods. 
         [0003]    Disclosed embodiments include a device for enhancing capture of fumes by a backshelf-type exhaust hood with at least one side panel. The hood has a recess with an access, the access has a forward edge portion along the hood-proper and at least one side edge portion along the at least one side panel. The device includes a fan module attachable to the hood. The fan module has distribution plenum portions including at least a first portion, a bend, and a second portion that are interconnectable to form a continuous sealed channel such that air provided by the fan module flows through the first portion to the second portion. The distribution plenum portions are configured to be attachable, respectively, to the forward and side edges such that they can be interconnected with the bend therebetween and such that they extend along hood forward edge portion and side edge portion. The distribution plenum portions has orifices arranged to form curtain jets emanating from the forward edge portion and side edge portion. The distribution plenum portions are separate from the hood such that they can be fitted to an existing hood. The curtain jet emanating from the forward edge has a downwardly directed vertical component. The curtain jet emanating from the side edge is horizontally-directed aimed and toward a blind end of the recess. 
         [0004]    In a variation, the fan module includes an ambient air inlet grill and fan to draw ambient air through the grill and discharge it into the distribution plenum. The fan module may further include a flow rate controller configured to vary a flow rate of the ambient air discharged thereby. The first and second portions may have directable nozzles that permit the direction of the curtain jets to be changed. 
         [0005]    Disclosed embodiments also include a device for enhancing capture of fumes from a cooking appliance into an exhaust hood. The exhaust hood has a recess with an access positioned above the cooking appliance, and at least a forward edge and two descending side edges. The device includes a capture augmentation device to generate and direct a first curtain jet along the forward edge of the exhaust hood, a second curtain jet along at least a part of one of the two descending side edges of the exhaust hood, and a third curtain jet along at least a part of the other of the at least two descending side edges of the exhaust hood. The first, second and third curtain jets are directed so as to induce flow of contaminated air into the exhaust hood and to increase containment of the forward edge and the at least two descending side edges of the exhaust hood. The capture augmentation device is configured to direct the first curtain jet in a direction which is between a horizontal and a vertical direction. The second and third curtain jets each have direction which corresponds to the shape of the descending edge and their position therealong. 
         [0006]    The capture augmentation device may include a plenum module with a plurality of apertures and a first portion positioned at a forward edge of the exhaust hood, a second portion positioned at one of the descending side edges of the exhaust hood, and a third portion positioned at the other descending side edge of the exhaust hood; and a fan module to force ambient air toward the plenum module. The first, second and third curtain jets may be generated by discharging pressurized ambient air from the first, second and third portions of the plenum module respectively through the plurality of apertures. The fan module may include a mechanism for changing a flow rate of the ambient air moving toward the plenum module. 
         [0007]    Disclosed embodiments also include a device for enhancing capture of contaminated air rising from a cooking appliance toward an exhaust hood where the exhaust hood has a recess with an access positioned above the cooking appliance. The device includes a capture augmentation device including a tubular portion positioned along an inner surface of at least one side of the exhaust hood to generate and direct a first curtain jet in a substantially vertical direction to increase containment of the at least one side of the exhaust hood, and a second curtain jet directed in a substantially horizontal direction to induce flow of contaminated air into a main flow in the exhaust hood. The capture augmentation device further includes a fan module positioned on an outer surface of the exhaust hood so as to force ambient air into the tubular portion. 
         [0008]    Disclosed embodiments also include a device for enhancing capture of fumes by a canopy-type exhaust hood with at least one side panel, the hood having a recess with an access, the access has a an edge adjacent the access. The device includes a fan module attachable to the hood. The fan module has a distribution plenum portions including at least a first portion, a bend, and a second portion that are interconnectable to form a continuous sealed channel such that air provided by the fan module flows through the first portion to the second portion. The distribution plenum portions are configured to be attachable, respectively, inside the recess and adjacent the edge such that they can be interconnected with the bend therebetween and such that they extend along the edge. The distribution plenum portions have orifices arranged to form curtain jets. The distribution plenum portions are separate from the hood such that they can be retrofitted to an existing hood. At least one of the distribution plenum portions are connected to the elbow by a pivotable connection to permit the curtain jet to be directed in a selected direction in a range that includes the horizontal, the vertical, and at least one position therebetween. 
         [0009]    The fan module may include an ambient air inlet grill and fan to draw ambient air through the grill and discharge it into the distribution plenum. The fan module may further include a flow rate controller configured to vary a flow rate of the ambient air discharged thereby. The first and second plenum portions may be cylindrical with circular cross-sections. 
         [0010]    Disclosed embodiments also include an exhaust device for capturing contaminated air from a cooking appliance including an exhaust hood has a forward top edge and at least two descending side edges which define an exhaust hood perimeter with a recess therein. The exhaust hood recess has an access positioned above the cooking appliance and a capture augmentation device, which generates curtain jets along at least a portion of the exhaust hood perimeter, attached to the forward top edge of the exhaust hood. The curtain jets are shaped and directed so as to induce flow of contaminated air from the cooking appliance into the exhaust hood recess. The capture augmentation device includes a distribution channel extending along at least a portion of the exhaust hood perimeter. The distribution channel has a plurality of apertures. A fan module flows ambient air into the distribution channel and through the apertures thereof so as to generate the curtain jets. The apertures of the distribution channel may form a substantially straight line across straight portions of a length of the distribution channel. The distribution channel may be attached to the forward top edge of the exhaust hood so as to generate a first curtain jet has a direction which is between a horizontal and a vertical direction. The distribution channel further extends along at least a portion of each of the at least two descending side edges generating a second and a third curtain jet, respectively. The distribution channel has a circularly cylindrical shape. S flow control device may control a flow rate of the ambient air flowing into the distribution channel. The capture augmentation device may be detachable from the exhaust hood. 
         [0011]    Disclosed embodiments also include an exhaust device for capturing contaminated air from a cooking appliance, the exhaust device including an exhaust hood with a top wall and a plurality of side walls which define a perimeter with a recess therein. The recess has an access positioned above the cooking appliance. A capture augmentation device is positioned so as to generate and direct curtain jets along at least a portion of the perimeter such that contaminated air is flowed into the exhaust hood recess. The capture augmentation device includes a distribution channel positioned within the recess such that the distribution channel extends along and substantially parallel with an inside surface of at least one of the plurality of side walls. The distribution channel including a plurality of apertures; and a fan module arranged external to the exhaust hood and configured to provide pressurized ambient air to the distribution channel, wherein the curtain jets are generated by discharging the pressurized ambient air through the apertures of the distribution channel. The distribution channel is offset in an upward direction from a bottom edge of the inner surface and is offset in a horizontal direction from the inner surface. The plurality of apertures may be positioned so as to direct a first curtain jet in a vertical direction toward the cooking appliance and a second curtain jet in a horizontal direction toward the inside of the exhaust hood. The distribution channel may have a circular cross-section shape or a rectangular or other prismatic shape. The exhaust hood may include at least two inner surfaces meeting at at least one corner, and the direction of the first and second curtain jets proximate the corner can be intermediate between respective directions of the first and second curtain jets remote from the corner. The distribution channel may be configured to be tilted. 
         [0012]    Disclosed embodiments also include an exhaust enhancement apparatus for an exhaust hood. The exhaust hood has a plurality of edges which define a perimeter with a recess therein for capturing contaminated air from a cooking appliance. The exhaust enhancement apparatus includes a distribution channel configured to be attached to and extend entirely along at least one of the exhaust hood edges. The distribution channel has an inlet and a plurality of apertures extending along a length thereof. An ambient air supply is configured to supply the distribution channel inlet with a pressurized supply of ambient air. The exhaust enhancement apparatus produces at least one curtain jet by flowing the pressurized air through the distribution channel and out through the plurality of apertures. The ambient air supply may include a fan module. 
         [0013]    Disclosed embodiments also include an exhaust enhancement apparatus for an exhaust hood, the exhaust hood having a top wall and a plurality of side walls which define a perimeter with a recess therein. The recess has an access positioned above the cooking appliance. The exhaust enhancement apparatus includes; a distribution channel configured to be attached within the recess so that it extends along and substantially parallel with an inside surface of at least one of the plurality of side walls. The distribution channel includes a plurality of apertures. A fan module is configured to be arranged external to the exhaust hood to provide pressurized ambient air to the distribution channel. The exhaust enhancement apparatus generates at least one curtain jet by discharging pressurized ambient air through the apertures of the distribution channel. The at least one curtain jet may have a substantially vertical direction. A first curtain jet may have a substantially vertical direction and a second curtain jet may have a substantially horizontal direction. The distribution channel may have a circularly cylindrical shape. The distribution channel may extend along an entire perimeter of the exhaust hood. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0014]    The foregoing and other aspects, features, and advantages of the present invention will be better appreciated from the following description of the embodiments, considered with reference to the accompanying drawings, wherein: 
           [0015]      FIG. 1  is a perspective view of a back-shelf style exhaust hood according to an embodiment of the invention. 
           [0016]      FIG. 2  is a cross-sectional representation of the exhaust hood of  FIG. 1  used with a platen-grill cooking appliance. 
           [0017]      FIG. 3  is a perspective view of a back-shelf style exhaust hood according to another embodiment of the invention. 
           [0018]      FIG. 4  is a partial cutaway view of a canopy-style exhaust hood with a capture augmentation device installed therewithin. 
           [0019]      FIG. 5  is a view of a part of a distribution plenum (or header) from a bottom or top view showing a curved elbow portion and two straight portions of the plenum. 
           [0020]      FIG. 6  is a bottom plan view looking up toward a canopy at a distribution header. 
           [0021]      FIG. 7  is a partial cutaway view of a canopy-style exhaust hood with a capture augmentation device installed therewithin. 
           [0022]      FIGS. 8A through 8C  show different possible positions for distribution header portions within a canopy hood. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Exhaust hoods for ventilation of pollutants from cooking appliances, such as ranges, promote capture and containment by providing a buffer zone above the pollutant source where buoyancy-driven momentum transients can be dissipated before pollutants are extracted. By managing transients in this way, the effective capture zone of an exhaust supply can be increased. 
         [0024]    The effective capture and containment capability of the exhaust hood can be enhanced by the use of air curtain jets positioned around a perimeter of the exhaust hood. The particular range of velocities, positioning, and direction of the jets in combination with a shape of the exhaust hood, can create an enhanced buffer zone below the hood and can induce flow of contaminated air into the exhaust hood. This can reduce the volume of flow of air required to ensure full capture and containment. 
         [0025]    Referring to  FIG. 1 , an exhaust hood  100  has side skirts  106  and an exhaust collar  100  which is connectable to an exhaust duct (not shown) such that air and fumes are drawn into a recess  108  and out through the exhaust collar  110 . A retrofit discharging module  140  has a fan module  101  containing a blower (not shown), that draws ambient room air into a duct  102  and passes the air into a distribution channel  104  pressurizing it such that air issues from an array of holes in the distribution channel  104  as individual air jets that expand due to air entrainment and coalesce a short distance thereafter to form a curtain jet  112 . A cooking appliance top surface is indicated at  114 . The retrofit discharging module  140  is attached to the exhaust hood  100  at its forward edge and requires only electrical connections to operate. Preferably, the fan module  101  is provided with a flow controller, such as a damper or a speed controller, to permit the flow rate to be adjusted to fit the operating conditions of the hood  100  exhaust flow rate. Preferably, the distribution channel  104  is a plenum. The holes (apertures) in the plenum  104  can be arranged so as to form substantially a straight line across a length of the plenum  104 . The size of the holes and the distance between them can vary based on the particular application. The discharging plenum  104  can be configured to be tilted with respect to the forward edge of the exhaust hood. This can change the direction in which the holes are facing the cooking appliance, and thus the direction of the curtain jet  112 . The direction of the curtain jet  112  can be changed to be anything between a substantially vertical and a substantially horizontal direction. 
         [0026]    In the embodiment of  FIG. 2 , the curtain jet  231  is shown forming an angle intermediate between the vertical and horizontal. This configuration may be used in embodiments where the exhaust hood  234  protects a platen grill  232  having a platen  230 . The angle may be chosen such that the jet  112  clears a forward edge  235  of the platen  230  when the platen  230  is in a raised position. 
         [0027]    Referring to  FIG. 3 , an exhaust hood  200  has side panels (the panels are sometimes called skirts)  208  and an exhaust collar  201  which is connectable to an exhaust duct (not shown) such that air and fumes are drawn into a recess  209  and out through the exhaust collar  201 . A capture augmentation device  260  has a fan module  204  containing a blower (not shown separately), that draws ambient room air into a duct  205  and passes the air into a distribution plenum  206  such that the air issues from an array of holes in the plenum  206  forming a curtain jet  212 . The plenum  206 , and similar elements with jet-forming holes in them, is also referred to as a header. A cooking appliance, such as a fryer or other kitchen appliance, may be located beneath the recess  209 . 
         [0028]    The capture augmentation device  260  is attached to the hood  200  at its forward edge and requires only electrical connections to operate. Preferably, the fan module  204  is provided with a flow controller, such as a damper or a speed controller, to permit the flow rate to be adjusted to fit the operating conditions of the hood  200  exhaust flow rate. A perimeter  250  of the exhaust hood includes a forward edge  254  and at least one descending side edge  252  of the hood. The side skirts  208  of this embodiment have cut-out areas  210  shaped and sized to permit cooking implements, such as fryer baskets to be moved away from the fryer (not shown) which would reside below the recess  209 . 
         [0029]    Descending plenums  202  with arrays of holes are connected to receive air from the plenum  206  and thereby form curtain jets  214  as shown. The curtain jets  214  effectively extend the effect of the side skirts  208  into the recess areas  210 . The direction of the curtain jets may be altered according to various embodiments. For example, the curtain jets  214  can be partially directed toward the opposite side panel  208  (that is, inwardly toward the middle of the recess) rather than parallel to the side panel  208  (i.e., in the plane of panel  208 ). 
         [0030]    Referring to  FIG. 4 , an exhaust hood  300  has side walls  306  and a top wall  320  that together defines a recess  307  enclosed on all sides but an underside facing the one or more cooking appliances  400 . The hood  300  has an exhaust collar  305  which is connectable to an exhaust duct (not shown) such that air and fumes are drawn into the recess  307  and out through the exhaust collar  305 . A capture augmentation device  308  has a fan module  301  containing a blower (not shown separately), that draws ambient room into a duct  322  and passes the air into a distribution plenum  302  pressurizing it such that the air issues from an array of holes (for example, hole  324 ) forming vertical and horizontal curtain jets  304  and  326 , respectively. The distribution plenum  302  has a cylindrical cross-section with straight and curved portions such that all sides of the canopy hood can be provided with the curtain jets shown. Preferably, the fan module  301  is provided with a flow controller (not shown), such as a damper or a speed controller, to permit the flow rate to be adjusted to fit the operating conditions of the hood  300  exhaust flow rate. The distribution plenum  302  can be cylindrical as indicated at  303  with the array of holes  324  arranged in one or more substantially straight rows across a length of the plenum  302 . 
         [0031]    Referring also to  FIG. 5 , the distribution plenum  302  is positioned within the recess  307  so as to extend along and substantially in parallel with the inside facing surface of at least one of the side walls  306 . The tube  302  can be connected to the fan module  301  which is arranged external to the exhaust hood  300 . The distribution plenum  302  can be offset upwardly from the bottom edge of the side wall and be offset horizontally from the inside surface of the side wall. The distance by which the discharging tube is offset from the edge and the side wall can vary depending on the application. In this embodiment the plurality of holes are positioned in a straight line facing the cooking appliance, so that the curtain jet  304  generated can be directed downwardly toward the cooking appliance in a substantially vertical direction. In another embodiment, the discharging tube  302  can have a second set of plurality of holes positioned along the length of the tube  302 , such that the first set of holes is substantially perpendicular to the second set of holes. In this case, a second curtain jet  311  is generated facing the inside of the recess  307  in a direction which is substantially horizontal. The exhaust hood may be a canopy-style hood. In alternate embodiments, the tube  303  may be formed of a plurality of sections  400  each connectable to its own fan module  301 , as shown in  FIG. 5 . 
         [0032]    Referring to  FIG. 5 , the distribution plenum  302  is tube positioned to extend along at least two adjacent inside surfaces of the exhaust hood  300  meeting at at least one corner. In this embodiment the distribution channel  302  has at least two straight tube portions  309  each extending along a respective inside surface of the exhaust hood  300 . The two portions  309  are connected to each other through a curved tube portion  310  (or elbow). The curtain jet  311  generated in each of the straight tube portions  309  has a direction which is substantially horizontal and the curtain jet  312  generated in the curved tube portion  310  in angled relative to the direction of the curtain jet  311 . Each of the straight tube portions  309  can be tilted relative to the curved tube portion  310 . By tilting the straight tube portions  309 , the direction of the curtain jet  311  can be changed. Referring to  FIG. 7 , the distribution channel  302  is positioned so as to extend along the entire perimeter of the recess  307 . The distribution channel may be a tube. In this embodiment, the ambient air forced into one end  303  of the tube  302  may flow throughout the entire tube  302  so as to circumnavigate the entire exhaust hood  300  and generate curtain jets  311  and  312 . 
         [0033]    In the embodiment of  FIG. 8 , the distribution plenum  502  has a box-shaped cross-section as indicated at  503 . Other features are conform to the description of  FIG. 4 .  FIGS. 8A ,  8 B, and  8 C show various locations for the distribution plenum  502  (or  302 ). The plenum may be hung by hangers from within the canopy such that it does not touch the interior wall of the canopy as shown in  FIGS. 4 and 7 . Alternatively, it can be attached as shown in the  FIGS. 8A and 8C  to the hood  820  interior. Alternatively it can be hung by hangers (similar to pipe hangers, for example) such that it is at the level of the lower edge  802  of the hood  800 . In  FIG. 8C , the distribution plenum is shown below the lower edge  802  of the hood  800 . 
         [0034]    It should be understood that the present invention is not limited to the embodiments described herein. Rather, those skilled in the art will appreciate that various changes and modifications can be made in keeping with the principles exemplified by the illustrative embodiments.