Abstract:
A vortex-type smoke hood, in which the liner of the hood is substantially continuously curved in such manner that the vortex action is improved greatly. One result is that the supply air velocity may be increased by a major amount, without causing &#34;bouncing&#34; of air and fumes out of the hood. The curved wall produces the additional benefit of rendering more smooth the flow path of the inlet air. 
     In a second embodiment, a plate shelf and/or pass-through are combined with the hood, creating a very convenient relationship and one whereby the cook remains highly comfortable.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of smoke hoods for removing grease and smoke from the spaces above cooking appliances, particularly in restaurants. 
     2. Description of Prior Art 
     The original patent in the field of vortex-type smoke hoods for cooking appliances is U.S. Pat. No. 3,664,255, issued May 23, 1972. Although the invention of such patent is believed to be a major one, the specific apparatus shown and described therein did not permit achievement of the fullest benefits of the large upper vortex. Stated more specifically, the velocity of the supply air in the apparatus of such patent could be increased only to a limited extent. Further increases resulted in &#34;bouncing&#34; or &#34;rebounding&#34; of supply air and of entrained fumes down out of the hood and into the room. 
     A relatively high velocity of supply air to the vortex, especially the upper vortex, is important for a number of reasons. The vortex principle causes a first centrifugal separation of grease to occur in the capture chamber, before the air and fumes pass through the filter. An analogy to the centrifugal grease separation in the upper vortex would be a jet traveling at high speed toward a cliff to bomb a target on the side thereof. As the jet (analogous to the air) pulls up, the bomb (analogous to a grease particle) is released -- so that the forward &#34;bomb&#34; (grease) velocity sends it at high speed into the cliff (analogous to the filter). The grease after impinging against the filter clings thereto instead of passing up the chimney. A second centrifugal grease separation action then occurs in the filter itself, as stated below. 
     The faster the air flow in the vortex (especially the upper vortex) in the capture chamber, the more effective the stated centrifugal grease-separation action therein. 
     Additional important reasons for creating a high-velocity upper vortex include a substantial simplification in the method by which the apparatus is set up for use. As explained in the above-cited patent, by far the greatest part of the air which passes out through the filters is not supplied from the room (the kitchen) but instead comes directly from the outside of the room. For example, in a typical installation only about 10% of the air comes from the room whereas 90% of the air comes from the outside. In attempting to achieve the desired balance between air supply to the hood, and air exhaust therefrom, it is important that the operator not be hampered by inability to increase the volume of the air supply sufficiently by increasing its velocity. As stated above, the operator would be so hampered if the otherwise-desired intake air velocity were so great as to cause rebound of air and smoke into the room. 
     The present apparatus achieves very effective separation of grease from the cooking fumes, yet permits a relatively simple set-up procedure. Furthermore, it is capable of withstanding substantial variations in the speeds of the supply and exhaust blowers (that is, speeds of the supply and exhaust air) without malfunctioning to a substantial degree. 
     Relative to a different aspect of the present disclosure, there have long existed restaurants which have plate shelves and/or pass-throughs beneath the smoke hoods. However, such restaurants did not achieve anything approximating the economy, efficiency, etc., of the shelf-smoke hood combination disclosed herein. In particular, there were no (insofar as applicant is aware) forced-flow smoke hoods which were so constructed that only a natural convective flow of air and cooking fumes passed upwardly adjacent the pass-through and/or the plate shelf. 
     In the above-cited patent, the baffle plate or member 54 was adjustable as described therein. The baffle 18 of the present disclosure is preferably (for economy reasons) fixed instead of adjustable. Such fixed baffle 18, the lip 19 at the rear edge thereof, and the central support 22 therefor, have all been on the market more than one year prior to the filing date of the present application and thus constitute prior art. 
     Summary of the Invention 
     The present invention provides a substantially continuously curved wall at the upper portion of the capture chamber, the curve being such as to permit creation of a high-velocity upper vortex of air and cooking fumes. Furthermore, there is provided at the front portion of such curved wall a relatively wide liner extension, which extension aids greatly in preventing high-velocity upper vortex air and fumes from passing downwardly out of the hood. Instead, the vortex air and fumes are directed substantially parallel to and above the curtain of inflowing supply air. The results are surprising increases in vortex action, in ease of set-up and adjustment, and other factors. 
     The forward region of the curved wall defines, at the side thereof remote from the capture chamber wherein the vortex exists, a curved vertical throat region which aids in smoothly directing the down-flowing supply of inlet air. 
     In a second embodiment, there is provided above the forward region of the cooking appliance at least one wall or shelf, preferably a plate-storage shelf and/or a pass-through shelf. Air from the room drawn rearwardly over the upper portion of the stove or other cooking appliance, by the upwardly rising hot air therefrom, entrains cooking fumes. The hot air and fumes then convect upwardly, rearwardly of the stated wall or shelf, through the open bottom of the capture chamber. Thereafter, the air and fumes are entrained in the laminar curtain of inlet air and are directed toward the filters. Some of the air and fumes are whirled around in the upper and lower vortexes before flowing through the filters. 
    
    
     Brief Description of the Drawings 
     FIG. 1 is a vertical sectional view of the present smoke hood apparatus for removing fumes from the space above a cooking appliance, the ceiling of the room in which the smoke apparatus is disposed being unshown; 
     FIG. 2 is a vertical sectional view taken on line 2-2 of FIG. 1, and looking rearwardly, such FIG. 2 also illustrating the extended plenum and the exhaust blower; 
     FIG. 3 is a horizontal sectional view on line 3--3 of FIG. 2, illustrating filter means; 
     FIG. 4 is an isometric view illustrating the substantially curved liner of the capture chamber of the smoke hood; 
     FIG. 5 is a vertical sectional view taken on line 5--5 of FIG. 1, and looking in a forward direction; and 
     FIG. 6 is a partially schematic view illustrating a second embodiment of the invention, wherein wall means are interposed between the forward region of the cooking appliance and the forward region of the smoke hood. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Except as specifically stated herein, the apparatus is substantially the same as that described and claimed in U.S. Pat. No. 3,664,225, issued May 23, 1972, for Apparatus and Method for Removing Fumes from the Space Above a Cooking Appliance. The disclosure of said patent is hereby incorporated by reference herein as though set forth in full. 
     As described in said U.S. Pat. No. 3,664,255, a supply blower is employed to draw air from a region exterior to the room in which the cooking appliance is disposed, and supplies such air (referred to as inlet air) downwardly through a duct means (the lower region of which is shown at 10 in the present patent application, FIGS. 1, 5 and 6) to a supply chamber (numbered 11 in the present patent application) and thence to a generally horizontal throat portion (numbered 12 in the present application) which may also be generally described as a director means. 
     From the throat portion 12, the incoming air flows in a stream or air curtain 13 which is inclined upwardly and rearwardly and which is generally perpendicular to filter means 3a. Some of the air in curtain 13 passes directly through the filter means 3a; some of the air therein passes upwardly and forms part of a large-diameter upper vortex 16; and some of the air passes downwardly and forms part of a small-diameter lower vortex 17. Eventually, all of the inlet air from throat 12 (not only that which flows directly through the filter, but also that which recirculates for a period of time in the upper and lower vortexes 16 and 17) passes through the filter means 3a and is exhausted to the exterior of the room as described below. 
     The housing of the present smoke hood apparatus comprises an open-bottomed capture and entrainment chamber &#34;C&#34; into which grease-containing fumes pass from the cooking appliance which is disposed beneath the smoke hood apparatus. In such capture and entrainment chamber C, the grease-containing fumes are entrained in the air curtain 13 and therefore are directed at high velocity toward the filter means 3a. Furthermore, and particularly when the inlet air from the exterior of the room is relatively cool (although it is emphasized that the inlet air is almost always substantially cooler than the upflowing fumes) there is a substantial chilling action having a tendency to solidify the grease particles in the fumes. As the filter means 3a are approached, some of the air and fumes in air curtain 13 swerves upwardly into the upper vortex 16, whereas other of the air and fumes swerves downwardly into the lower vortex 17. However, despite such swerving of the air, the entrained heavy grease particles continue their forward motion and tend to impinge against the filter 3a, the result being a centrifugal separation action which occurs in the capture and entrainment chamber C. The grease particles which impinge against the filter means 3a cling thereto and run down into trough means described in the cited U.S. Pat. No. 3,664,255. 
     The filter means 3a is best shown in FIG. 3, and is described in U.S. Pat. No. 3,566,585, issued Mar. 2, 1971, for a Grease-Extracting Apparatus. The disclosure of said patent is hereby incorporated by reference herein as though set forth in full. Said filters are numbered 3a in the present application, and are preferably operated in the open mode (FIG. 4 of said U.S. Pat. No. 3,566,585), not in the closed mode (FIG. 5 of said patent). The numbers shown in FIG. 3 of the present application correspond to the numbering in said U.S. Pat. No. 3,566,585, except that in each instance the suffix &#34;a&#34; has been appended to the elements in FIG. 3 of the present application. 
     In the filter means 3a, a second centrifugal separation action occurs (in addition to the above described separation occurring by direct impingement), so that the degree of grease removal from the cooking fumes is very great. However, it is highly important that the flow of air and fumes through the filter means 3a be substantially uniform throughout the entire width of the filter means. The achievement of such substantially uniformity is effected, without clogging up of screens, etc., by grease particles, as described in detail in my copending application Ser. No. 336,970,  filed Mar. 1, 1973, for Apparatus and Method for Extracting Grease and Smoke, now abandoned. Said patent application is hereby incorporated by reference herein as though set forth in full. Such application describes an extended plenum 150 which communicates with the plenum chamber or exhaust chamber 27 on the downstream side of the filter means 3a. Referring to FIG. 2 of the present application, the extended plenum 150 communicates with an exhaust blower 44 which discharges filtered air and fumes to the ambient space outside of the room wherein the cooking appliance is disposed. 
     The above-mentioned generally horizontal throat portion 12 is defined on the lower side thereof by an upwardly inclined baffle plate 18 having a further upwardly inclined lip 19 at the rear edge thereof. For reasons of economy of production, and maintenance of the precise desired angles, the baffle plate 18 and its lip 19 are preferably fixed in position, for example by angle bars 21 which are suitably secured to the side walls of the apparatus and are shown in FIGS. 1 and 5. To prevent sagging of the central region of the baffle plate 18, a connector element 22 (incorporating a turnbuckle) is connected between the central region of the baffle plate and the central region of the substantially continuously curved member (described below) thereabove. 
     As described in said U.S. Pat. No. 3,664,255, not all of the inlet air from the duct means 10 passes through the throat 12, since some passes downwardly through a gap 23 (FIG. 1) and then strikes a ledge means 24 disposed at the front portion of the apparatus. The ledge means 24 redirects the air rearwardly toward the capture and entrainment chamber C. 
     THE SUBSTANTIALLY CONTINUOUSLY CURVED VORTEX LINER 
     Referring particularly to FIGS. 1 and 4, the upper liner of the upper vortex portion of capture and entrainment chamber C is designated generally by the reference numeral 31, and may sometimes be referred to as the vortex liner. Such vortex liner has a rearward-most first portion 32, the lower edge 33 of which is adjacent the upper face of filter means 3a. From such lower edge 33, the first portion 32 curves upwardly and forwardly to a region 34 which is spaced above and substantially forwardly of the lower edge 33. 
     A relatively narrow, flat, downwardly-inclined second portion 36 extends from region 34 forwardly and downwardly to a region 37. The narrow second portion 36 is just wide enough to receive a light fixture 39, preferably florescent, which fixture is mounted thereabove and is registered with an opening 41 (FIG. 4) in the second portion. 
     From region 37, the vortex liner 31 curves downwardly and forwardly to form a curved third portion 42. The third portion 42 curves downwardly and forwardly with a relatively small amount of curvature, to a region 46 best shown in FIG. 1. From region 46, the vortex liner 31 curves downwardly and substantially vertically to form a forwardmost fourth portion 47, the lower edge of such fourth portion 47 being at a region 48. The vortex liner 31 then curves downwardly and rearwardly, with a relatively sharp curvature, to form a fifth portion 49 between regions 48 and 50. Thereafter, the vortex liner extends rearwardly and generally horizontally to form a sixth portion 51 (which may be termed a &#34;linear extension&#34;) terminating in a rear edge 52. 
     The sixth portion 51 is substantially flat and substantially horizontal, this being in contrast with the upwardly and rearwardly inclined baffle plate 18 therebelow and in contrast with the much more upwardly and rearwardly inclined lip 19 on such baffle plate 18. It is emphasized that the sixth portion 51 extends rearwardly a very substantial distance from the generally vertical curved fourth portion 47 of the vortex liner 31. Stated otherwise, the two portions 49 and 51 of the vortex liner combine to form a relatively wide (front to back) section thereof, such wide section extending rearwardly from the generally vertical curved fourth portion 47. 
     This wide section (portions 49 and 51) of the vortex liner performs the function of insuring that the rapidly vortexing air and fumes in the upper vortex 16 are directed rearwardly generally toward the filter means 3a, as distinguished from being directed or bounced downwardly out of the capture and entrainment chamber C and into the room. The section comprising portions 49 and 51 cooperates with the remaining portions of the vortex liner in preventing such bouncing even though the velocity of the inlet air passing into the chamber from the generally horizontal throat portion 12 may be very high. 
     It is pointed out that the air in the upper vortex 16 which passes above the sixth portion 51 of the vortex liner is only slightly inclined relative to the air curtain 13, being generally parallel thereto. It is also pointed out that the sixth portion 51, which is substantially horizontal, converges relative to the lip 19 at the rear edge of baffle plate 18. There is thus being formed a generally vertical nozzle opening 53 at the rear edge of the generally horizontal throat 12, such nozzle opening 53 being generally between rear edge 52 and the rear edge 54 of lip 19. The opposed edges 52 and 54, and the nozzle opening 53 therebetween, and the inclined lip 19, cooperate with baffle plate 18 and other elements in insuring that the air entering the chamber C as the air curtain 13, and also the air in the upper vortex 16, do not bounce out of the chamber C but instead remain in the desired paths as indicated by the arrows in FIG. 1. 
     The nozzle is formed by the relatively long and inwardly tapering walls 51 and 18. These walls not only cause an increase in velocity of air entering chamber C from the throat portion 12, but direct, constrict and shape the flow of this air to enhance the vortex. 
     The radius of curvature of first portion 32 of the vortex liner 31 is relatively large, for example about 15 inches in a typical installation. The radius of curvature of the third portion 42 is even larger, for example about 18 inches in a typical installation. The radius of curvature of the generally vertical fourth portion 47 of the vortex liner is much smaller, such as about 71/2 inches, whereas the radius of curvature of the fifth portion 49 is the smallest, namely about 3 inches in a typical installation. In such typical installation, the portion 51 extends about 8 inches rearwardly from the generally vertical fourth portion 47. 
     It is to be noted that the vortex liner 31 not only defines the upper vortex 16 in chamber C, but that the right hand portion (relative to FIG. 1) of the vortex liner defines the rear wall of the supply chamber 11. Furthermore, the fourth portion 47 of the vortex liner 31 forms the rear wall of a vertical throat portion 56 defined between the vortex liner and the front wall 45 of the apparatus. The smoothly curving rear walls of supply chamber 11 and of vertical throat portion 56, which are thus formed by the vortex liner 31, aid in the supply of a smooth flow of air from the duct means 10 to the horizontal throat portion 12. 
     As best shown in FIGS. 1 and 2, the rear edge 52 at the lower region of the vortex liner is return bent so that it will be smooth and relatively strong. Furthermore, the lower edge 33 at the rear region of the vortex liner is bent upwardly to form a flange 57. Such flange 57 preferably bends around the sheet metal element which forms the upper support for the filter means 3a. 
     EMBODIMENT OF FIG. 6 
     Except as specifically stated below, the smoke hood shown at the upper region of FIG. 6 is identical to that described heretofore in this specification. 
     The smoke hood is shown as being mounted adjacent a vertical wall 61 which separates the kitchen 62 from, for example, the dining rooom 63 of a restaurant. In the illustrated embodiment, there is a pass-through opening 64 in such vertical wall 61, through which cooked food is passed by the chefs to waitresses in the dining room 63. The pass-through opening 64 is disposed a substantial distance above the upper surface 66 of a stove or other cooking appliance 67. 
     In accordance with the illustrated embodiment, wall means are interposed between the forward region 68 of the upper surface 66 and the forward region 69 of the smoke hood thereabove. In the illustrated embodiment there are three such wall means, one being a horizontal shelf 72 which is suitably mounted in horizontal relationship and generally level with the lower region of pass-through opening 64, the second being a horizontal plate shelf 73 which is also suitably mounted in horizontal position but level with the upper region of pass-through 64, and the third being a wall 74 which is mounted below the forward portion of the capture and entrainment chamber C. 
     The shelf 72 extends entirely through the pass-through opening 64, but an intermediate portion 75 of shelf 72 is open and provided with a perforated element or grill 76 through which fumes may pass upwardly from the stove 67 to the smoke hood. Thus, the chef may store food, etc., on the front (right in FIG. 6) portion of the shelf 72, and then, when desired, slide the food over the grill 76 and through the pass-through opening 64 to the rear region of shelf 72, where it is easily and conveniently picked up by the waitresses. 
     The plate shelf 73 is a storage area for clean plates which are maintained relatively warm due to the proximity of a chimney 79 which is defined above the grill 76 of the shelf 72 and to the rear of the plate shelf 73. Stated more specifically, the upper region of the chimney 79 is defined between the wall 61 of the room and a vertical wall 80 which extends upwardly from the rear edge of plate shelf 73 to the rear edge of wall 74. 
     In the operation of the embodiment of FIG. 6, the front (right in FIG. 6) region of shelf 72 acts somewhat in the nature of the upper portion of a fireplace in a household living room. Thus, air from the kitchen 62 tends to be drawn inwardly from the kitchen (away from the cook) into the space between stove surface 66 and the front region of the shelf 72, due to the heat generated by the stove 67 (which acts something in the nature of a household fireplace). This convective air flow path curves upwardly relatively adjacent vertical wall 61 and passes through the grill 76 to the chimney 79 and thence into the open-bottomed capture and entrainment chamber C. In passing over the upper surface 66 of the stove 67, the convectively flowing air picks up the grease-laden cooking fumes and carries them upwardly therewith into such chamber C, so that the fumes are separated and filtered and exhausted as described in detail previously in this specification. 
     Although the embodiment illustrated in FIG. 6 incorporates the pass-through opening 64 and the associated shelf 72 and grilled opening 75, these may be omitted in some restaurants. The vertical wall 62 would then be continuous and void of an opening, and the shelf 72 and the grill 76 would then be omitted. Air would then convect upwardly from the stove 67 and would tend to be relatively adjacent the vertical wall 61. It would pass upwardly through the chimney 79 to the chamber C. 
     The wall 74 preferably comprises a panel or sections of panels which may be removed for gaining access to the filters 3a. With the wall 74 removed, the filters 3a may be easily withdrawn through the resulting opening so they may be cleaned. 
     The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention bein limited solely by the appended claims.