Abstract:
A kitchen hood assembly includes a combination hood cleaning and fire suppression system. The hood assembly includes a hood structure and a riser connected thereto. An exhaust blower forces an exhaust stream of air into the hood and through the riser. A combination hood cleaning and fire suppression system is incorporated into the hood structure. The combination hood cleaning and fire suppression system includes an elongated spray bar that is connected to a water source and includes a surfactant injector that injects a surfactant into the water being directed to the spray bar. In one mode of operation, the spray bar is effective to clean the hood assembly. In another mode of operation, when a fire is sensed in or in the vicinity of the hood, the same spray bar is utilized to inject an aqueous liquid into the hood to suppress the fire.

Description:
FIELD OF THE INVENTION 
     The present invention relates to cleaning and suppressing fires in kitchen hood assemblies. 
     SUMMARY OF THE INVENTION 
     A kitchen hood assembly is provided and includes a combination cleaning and fire suppression system. That is, the hood assembly is operative in one mode to inject water or an aqueous solution into the hood structure to clean the same. In a second mode of operation, in response to a fire being detected in or adjacent to the hood, the same system injects water or an aqueous solution into the hood to suppress a fire. 
     In one embodiment, the kitchen hood assembly comprises a combination hood cleaning and fire suppression system. This hood assembly includes a hood structure and a riser connected to the hood structure and extending therefrom. An exhaust blower is provided for forcing an exhaust stream of air into and through the riser. The combination hood cleaning and fire suppression system incorporated into the hood structure is adapted in a cleaning mode to spray water and a surfactant within the kitchen hood to clean the same, and in a fire suppression mode in response to a signal from a fire sensor, spray water and a surfactant into the kitchen hood to know down and suppress the fire. 
     Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of the kitchen hood assembly with the combination cleaning and fire suppression system. 
         FIG. 2  is a perspective of the kitchen hood assembly with a top portion thereof removed to better illustrate the combination cleaning and fire suppression system. 
         FIG. 3  is a top plan view of the kitchen hood with a top portion removed to better illustrate internal components of the hood. 
         FIG. 4  is a side sectional view of the kitchen hood assembly taken through the line  4 - 4  of  FIG. 3 . 
         FIG. 4A  is a side sectional view of the kitchen hood assembly taken through the line  4 A- 4 A of  FIG. 3 . 
         FIG. 5  is a front sectional view of the kitchen hood assembly with the combination cleaning and fire suppression system. 
         FIG. 6  is a fragmentary perspective view of the kitchen hood assembly showing the control system. 
         FIG. 7  is a schematic illustration of the control system. 
     
    
    
     DESCRIPTION OF THE INVENTION 
     With further reference to the drawings, the kitchen hood assembly of the present invention is shown therein and indicated generally by the numeral  10 . As illustrated in  FIG. 1 , kitchen hood assembly  10  comprises a housing  12  generally defining the outer structure. Disposed within hood assembly  10  is a combination cleaning and fire suppression system  20  comprising a spray bar  22  and a control system  26  as shown in  FIGS. 2 ,  3 , and  4 . 
     Turning now to a more detailed description of kitchen hood assembly  10 , housing  12  encloses a vapor entrainment area  14  comprising a portion of the interior of the housing as illustrated in  FIG. 1 . In a typical application, kitchen hood assembly  10  is mounted such that it is spaced above a cooking surface or similar device in order that vapors produced in cooking are entrained upwards into vapor entrainment area  14 . Kitchen hood assembly  10  includes a grease confinement area  16  that is separated from vapor entrainment area  14  by an inclined panel  15  as shown particularly in  FIGS. 2 and 4A . Mounted within panel  15  is a filter  15 A through which the entrained vapors may flow into grease confinement area  16 . Mounted to an upper portion of hood assembly  10  and in fluid communication with grease confinement area  16  is a riser or duct  18  extending away from the hood assembly. Riser  18  includes an interior  18 A to receive vapors from grease confinement area  16  and conduct the vapors away from hood assembly  10 . An exhaust blower is disposed in fluid communication with riser  18 . The exhaust blower maintains a draft through riser  18  to facilitate entraining vapor in vapor entrainment area  14  and directing the vapors through filter  15 A into grease confinement area  16  and subsequently through riser  18  to be exhausted away from hood assembly  10 . 
     Disposed within grease confinement area  16  is a portion of the combination cleaning and fire suppression system  20 . Spray bar  22  extends generally transversely across an upper portion of the grease confinement area  16 . See  FIGS. 2 and 3 . Spray bar  22  includes a series of spaced-apart nozzles  22 A and at least one riser nozzle  22 B. Nozzles  22 A are typically angled to direct spray to the inner surfaces of the grease confinement area  16 . Nozzles  22 A may, however, be directed at various angles and all nozzles need not be directed in the same direction. Each nozzle  22 A has a spray pattern, spacing, and direction such that a spray of an appropriately pressurized aqueous liquid, such as water and a surfactant, from the nozzles impinges on the interior surfaces of grease confinement area  16  to remove contaminants, including grease and generally clean the hood in this area. At least one nozzle  22 B is positioned to align with the center of the horizontal cross-section of riser  18 . See  FIGS. 2 ,  3 , and  4 A. Nozzle  22 B is directed generally upward such that a spray of an appropriately pressurized liquid from the nozzle is directed into the center of riser  18 . 
     In one embodiment, spray bar  22  includes a series of pipe segments  23  connected together by a series of tees  22 E as illustrated particularly in  FIG. 3 . Nozzles  22 A and  22 B are associated with the tees  22 E. Note that the riser nozzle  22 B is generally oriented in position to direct an aqueous liquid into the riser  18 . Spray bar  22  in the embodiment illustrated in  FIG. 3  is offset with respect to the center of riser  18 . In order to position nozzle  22 B generally centrally with respect to the riser  18 , there is provided an arm  27  that extends between the tee  22 E and the nozzle  22 B. 
     Turning now to control system  26  ( FIG. 6 ), the control system includes a manifold  21  ( FIG. 6 ) for connecting spray bar  22  to a source of water, a surfactant controller  26 B, and a surfactant reservoir  26 C. Manifold  21  is constructed generally of pipe and fittings by common methods. The configuration of manifold  21 , in one embodiment, includes a pair of vertically-oriented tubular inlet legs  21 A,  21 B and a vertical tubular outlet leg  21 C ( FIG. 6 ). The vertically-oriented legs  21 A,  21 B,  21 C are connected and in fluid communication with a horizontal connector  21 D. Water from two sources may thus be provided to manifold  21 . For example, heated water may be directed into inlet  21 E of leg  21 A and unheated water may be directed into inlet  21 F of leg  21 B. The heated and unheated water is directed through manual shut-off valves  21 G (one in each of legs  21 A,  21 B) and electronic solenoid valves  21 H (one in each of legs  21 A,  21 B) into connector  21 D from whence the mixed heated and unheated water is directed into leg  21 C and into spray bar  22 . It is noted that spray bar  22  is in fluid communication with leg  21 C by an upper connector  21 M. 
     As noted above, each leg  21 A,  21 B includes a manual shutoff valve  21 G and an electric solenoid valve  21 H. Leg  21 C includes a temperature sensor  21 K. Control system  26  may include the capacity to respond to a desired temperature set point and adjust the flow of heated and unheated water to obtain and maintain the temperature of the water flowing in leg  21 C at a certain temperature or within a temperature range. 
     Control system  26  also includes a surfactant injection apparatus to inject surfactant into the water directed to spray bar  22 . In one embodiment, the apparatus includes a surfactant pump system  26 B and a surfactant reservoir  26 C. The pump inlet is fluidly connected to reservoir  26 C by tube  29 A, and the pump outlet is connected to connector  21 M by tube  29 B. It is appreciated that a check valve may be interposed between the connection of tube  29 B to connector  21 M and surfactant pump system  26 B to prevent backflow through the surfactant pump system. 
     Control system  26  further includes commonly known circuitry and logic for activating system  20  by admitting supply water into the system for a set or desired time period. During the time period that water is being injected into cleaning and fire suppression system  20 , control system  26  controls the amount of surfactant injected by surfactant pump  26 B. 
     The cleaning and fire suppression system  20  further includes a fire sensor  30  that is mounted on riser  18 , or in an area in the hood, such that the sensor is operative to be activated by a fire in interior  18 A of the riser  18  or grease confinement area  16 . In one embodiment, fire sensor  30  includes an active sensing element extending at least partially into interior  18 A. Fire sensor  30  may be of various extant designs that provide an electrical signal that may be used to initiate operation of combination cleaning and fire suppression system  20  in the event of a fire being detected as will be discussed here below. 
     A control schematic for control system  26  that enables both hood cleaning and fire suppression is illustrated in  FIG. 7 . Components that make-up the controls may, in one embodiment, be housed within control system cabinet  26 A ( FIG. 2 ). The elements include an uninterruptible power supply or battery back up device that is operable to automatically maintain power to the system during a power outage. Electrical power from AC supply  1  is supplied to a DC power supply which in turn provides DC electrical power for control system  26 . Typically, the hood exhaust blower is powered by an AC motor and is controlled by a manual shut-off switch  11 . Also typically, the control elements require DC electrical power that may be provided by the DC power supply and battery back-up device. The battery back-up device includes the capability to sense the state of AC supply  1 , that capability indicated by dashed line  2 . When a power outage is detected, the battery back-up supplies via line  3  the DC power to maintain operation of cleaning and fire suppression system  20  during the power outage. Exhaust blower shut-off switch  11 , which generally is a manually actuated on-off switch, is coupled to a wash switch  12  such that closing switch  11  opens switch  12 , and opening switch  11  closes switch  12 . The coupling of switches  11  and  12  may be of various known forms including a mechanical linkage and electrical relays. With switches  11  and  12  thus coupled, when the exhaust blower is operating, cleaning with cleaning and fire suppression system  20  is not normally energized. This is the normal operation of hood  10  in which, for example, cooking of foods is occurring under or near the hood. The exhaust blower may be de-energized by manually opening switch  11  as would, for example, be the case at the end of a cooking period. When switch  11  is opened, switch  12  closes and energizes water valves  21 H to admit water into manifold  21  and surfactant pump system  26 B to provide surfactant such that cleaning and fire suppression system  20  performs a cleaning cycle for range hood assembly  10 . In one embodiment, a timer switch is provided in series with switch  12  and is operable to de-energize water valves  21 H and surfactant pump  26 B upon completing a desired or set cleaning period. In the example just discussed, the power supply is DC. However, it is appreciated that AC power could be used to power the control system  26  shown in  FIG. 7 . Various components of the system would be changed to make them AC compatible. Further, a back-up power source, such as an AC generator, could be used. 
     Fire sensor  30  is coupled to a fire switch  13 , the coupling symbolically indicated in  FIG. 7  by dashed line  4 . When a fire in range hood  10  occurs, fire sensor  30  closes fire switch  13  to energize water valves  21 H and surfactant pump  26 B. Line  5  connects to switch  13  and effectively interconnects the DC power supply and battery back-up to the water valves  21 H and surfactant pump system  26 B. This connection by-passes switch  12  and the timer switch. Whether the exhaust blower is energized or not, should a fire be sensed by fire sensor  30 , fire switch  13  closes and energizes valves  21 H and pump system  26 B for fire suppression. Thus energized, water and surfactant is sprayed into hood assembly  10 , including into riser  18 , to suppress the fire. A manual reset feature of common design may be provided to de-energize cleaning and fire suppression system  20  when the fire is suppressed. Alternatively, when the level of fire suppression is such that fire sensor  30  no longer senses a fire, switch  13  may be configured to open and de-energize valves  21 H and surfactant pump system  26 B. 
     It is appreciated that cleaning and fire suppression system  20  functions similarly during cleaning and fire suppression. Once energized, whether by manual shut-off of hood assembly  10  or by a fire being sensed by fire sensor  30 , system  20  functions the same way using the same aqueous liquid. 
     To be effective in cleaning hood assembly  10 , cleaning and fire suppression system  20  may be supplied with water having a temperature between about 140° F. and about 170° F. To be effective in cleaning and fire suppression, water pressure may be maintained at about 30 psi. Nozzles  22 A can provide a flow of about 0.7 gpm at 30 psi. Riser nozzle  22 B may be rated to provide 2.4 gpm at 30 psi. In a typical application, nozzles  22 A are equivalent to Macola Model No. 2591 or 2592 and nozzles  22 B are equivalent to Macola Model No. 2593. All plumbing is brass pipe or tube. Spray bar  22  comprises ¾″ pipe nipples  23  and  24 , tees  22 E, and elbows. Riser nipple  27  comprises ¼″ tubing or pipe and commonly available fittings to connect to spray bar  22 . In a typical application, pipe nipples  23  are about 12″ long and provide for nozzles  22 A to be spaced apart about 13″ and preferably spaced at between 12½″ and 13½″. It is appreciated that all of these sizes discussed above can vary and will probably vary depending upon application. Fire suppression sensor  30  should be of a design capable of sensing the presence of fire typical of range hood systems. Fire sensors are well known in the art and are commercially available. Hood drain  28  is typically formed of brass pipe and fittings. In one embodiment, 1½″ pipe is used in forming hood drain  28 , and the hood drain extends at least 72″ away from hood assembly  10 . 
     Commonly available surfactants may be used and function also as detergents. Generally, during cleaning or fire suppression, control system  26  provides for surfactant to be injected for 1 second for every minute of operation. The surfactant is effective in the fire suppression mode to knockdown the fire. The amount of surfactant administered during a fire and the time period for injecting a surfactant can vary. However, in a preferred design and process, surfactant is continuously injected into the water stream in a fire situation. 
     There are many advantages to the new kitchen hood assembly of the present invention. One principal advantage is that the kitchen hood assembly utilizes substantially the same structure and system for both cleaning the hood assembly and for fire prevention. Also, it should be pointed out that the kitchen hood assembly disclosed herein and the fire proof prevention system is fully certified to Standard UL300. 
     The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the scope and the essential characteristics of the invention. The present embodiments are therefore to be construed in all aspects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.