Abstract:
A barbeque grill includes a cooking grate within the interior space of a main housing for receiving food items to be cooked. A primary heat source is below the cooking grate for transmitting heat to food items located on the cooking grate. A secondary housing structure is located within the interior space and a secondary heat source is below the secondary housing for transmitting heat to the secondary housing. A container for receiving wood pellets is accessible from the exterior of the main housing and is positioned for delivering wood pellets to the secondary housing structure.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a barbecue grill with smoke generator.  
           [0002]    A conventional charcoal grill comprises a metal housing for receiving charcoal briquettes and a cooking grate positioned over the briquettes for receiving food items to be cooked. The burning charcoal briquettes emit smoke that imparts a characteristic barbecue flavor to the food items being cooked.  
           [0003]    A conventional gas or electric barbecue grill comprises a metal housing and a gas burner or electrical resistance heating element supported within the housing beneath a cooking grate. Sear bars may be located between the heat source (the gas burner or electrical resistance heating element) and the cooking grate for receiving and evaporating grease that falls from the food on the cooking grate.  
           [0004]    The conventional gas or electric grill is generally more convenient and less expensive to operate than a conventional charcoal grill but is subject to the disadvantage that the heat source does not emit smoke that can impart flavor to the food items being cooked.  
           [0005]    It is known to use wood pellets as fuel in a barbecue grill. When burned, wood pellets, like charcoal briquettes, emit smoke that imparts additional flavor to the food items being cooked. In this case, the barbecue grill may include a fire pot and an auger mechanism for feeding pellets from a hopper to the fire pot for burning to provide the heat for cooking. However, in order to generate sufficient heat for cooking food the wood pellets must be ignited and burned at a high temperature. This causes the wood pellets to be consumed relatively quickly and thus a large quantity of wood pellets must be used for cooking and a less than optimum amount of smoke is emitted from the wood pellets.  
         SUMMARY OF THE INVENTION  
         [0006]    In accordance with the present invention there is provided a barbeque grill comprising a main housing having an interior space, a cooking grate within the interior space for receiving food items to be cooked, a primary heat source below the cooking grate for transmitting heat to food items located on the cooking grate, a secondary housing structure within the interior space, a secondary heat source below the secondary housing for transmitting heat to the secondary housing, and a container for receiving wood pellets, said container being accessible from the exterior of the main housing.  
           [0007]    The present invention utilizes a secondary heat source for heating wood pellets. The wood pellets are heated to a lower temperature than is necessary to ignite the wood pellets such that heat emitted by the pellets could be used for safely cooking food items on the grate. The temperature is chosen so the wood pellets emit smoke over a longer period of time than if they were exposed to a higher temperature and ignited. This causes the wood pellets to be consumed at a more efficient rate than they would be if the wood pellets were used as the primary fuel for cooking, and thus provides the advantages of added flavor to the food items that is gained from wood pellet or charcoal briquette cooking at a cost closer to that of using a gas or electric grill. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which  
         [0009]    [0009]FIG. 1 is a sectional view of a first barbecue grill embodying the present invention,  
         [0010]    [0010]FIG. 2 is an enlarged perspective view of a first smoke generator included in the FIG. 1 grill,  
         [0011]    [0011]FIG. 3 is a longitudinal sectional view of the smoke generator,  
         [0012]    [0012]FIG. 4 is an enlarged perspective view of a second smoke generator included in the FIG. 1 grill,  
         [0013]    [0013]FIG. 5 is a sectional view of a second barbecue grill embodying the present invention,  
         [0014]    [0014]FIG. 6 is an enlarged perspective view of a third smoke generator included the the FIG. 5 barbeque grill,  
         [0015]    [0015]FIG. 6A-6C are longitudinal views of three configurations of the third smoke generator. 
     
    
     DETAILED DESCRIPTION  
       [0016]    Referring to FIG. 1, the illustrated barbecue grill comprises a main or lower housing  4 , a primary heat source  8 , a cooking grate  12 , sear bars  16  disposed between the heat source and the cooking grate and a hood or upper housing  20  that is hinged to the lower housing so that it can be pivoted between a lowered position, shown in FIG. 1, and a raised position, in which it allows access to food items located on the cooking grate.  
         [0017]    In addition, the lower housing  4  contains a smoke generator  24  located between the sear bars  16  and the rear wall  28  of the lower housing. Referring to FIGS. 2 and 3, the smoke generator comprises a secondary or inner housing  30  having a channel  32  at the bottom that extends from an inlet opening to a discharge opening. The secondary housing  30  includes a longitudinal wall  34  adjacent the rear sear bar and a top wall  36  that slopes downwards from the wall  34  towards the rear wall  28  of the lower housing and is formed with a vent slot  40  for allowing smoke to discharge from the secondary housing at the rear of the main housing. Accordingly, smoke leaving the secondary housing flows upwards and over the food items, and not under the sear bars, to discharge from the barbecue grill.  
         [0018]    A fuel hopper  56  communicates with the channel  32  through the inlet opening and a discharge drawer  64  is positioned adjacent the discharge opening of the secondary housing  30  and can be withdrawn from the main housing through an aperture in the wall of the main housing. A secondary heat source  68 , which is preferably an electrical resistance heating element but may alternatively be a gas burner and is in any event independent of the primary heat source  8 , is located beneath the secondary housing  30 . Extending through the length of the channel is a means for moving the wood pellets  70  from the hopper  56 , through the channel  32 , to the discharge drawer  64 . While the wood pellets are in the channel they are heated by the secondary heat source  68 .  
         [0019]    In one embodiment of the invention, the means for moving the wood pellets  70  is implemented by an auger  44  that extends through the channel  32  of the secondary housing. The auger is driven by a spring drive motor  48  that is located outside the main housing  4  and is provided with a handle  52  for winding up the motor. The spring drive motor  48  drives the auger  44 , and rotation of the auger transfers wood pellets  70  from the hopper  56  into the channel  32  of the secondary housing and advances the pellets  70  slowly along the channel  32  towards the discharge drawer  64 . The spring drive motor may also be provided with a latch for stopping operation of the motor.  
         [0020]    In another embodiment of the invention, a saw-toothed plate  80 , as shown in FIG. 4, may replace the auger  44  as the means for transporting the wood pellets through the channel  32 . Wood pellets are deposited onto the plate  80  from the fuel hopper  56 . An electric motor  84 , connected to the plate via a linkage  88 , causes the plate to oscillate horizontally. The teeth  96  on the surface  92  of the plate form pockets  94  that the wood pellets rest in and the oscillating motion of the plate acts to impel or jog the wood pellets from pocket to pocket, the net direction of movement being from the inlet opening towards the discharge drawer  64 . Referring to FIG. 4, as the plate  80  advances (moves in the direction of the discharge drawer  64 ) the steeper wall  100  of the pocket  94 A pushes the wood pellets  70  forward. When the plate  80  withdraws, the wood pellets tend to slide over the less steep wall  104  of the pocket  94 A and fall into the next pocket  94 B. The rate of vibration of the plate  80  and the steepness of the teeth  96  are selected so the wood pellets  70  move at an optimum speed for generating smoke.  
         [0021]    In operation, the user places a supply of wood pellets  70  in the hopper  56 . Various blends of wood pellets that are suitable for generating wood flavored smoke in a barbecue grill are commercially available from Hutton Marketing LLC of St. Helens, Oreg. The user also energizes the main heat source  8 . At a convenient time, which may be just before placing food items on the cooking grate  12 , the user will activate the means for moving the wood pellets, and energize the secondary heat source  68 . The speed of travel of the wood pellets  70  and the heat output of the secondary heat source  68  are selected so the wood pellets  70  are heated to a sufficient temperature to emit smoke but are not ignited. The smoke emitted from the wood pellets  70  escapes from the secondary housing through the slot  40  and accumulates above the sear bars  16 . The food items being cooked on the cooking grate  12  are thereby exposed to the flavor-imparting smoke, enhancing the flavor of the food items.  
         [0022]    In some instances, it is desirable that a large portion of the smoke generated by the wood chips be directed at only a portion of the cooking grate  12  and conversely, that little or no smoke come into contact with another portion of the cooking grate.  
         [0023]    In a third embodiment of the invention, as shown in FIG. 6, the secondary housing  30  contains a removable hopper  110 , located centrally with respect to the width of the main housing  4  and above the secondary heat source  68 . A vane  114  in the secondary housing extends from above the hopper  110  upwards towards a vent  116 . The vane  114  is pivotable, with respect to the secondary housing  30 , via a knob  118  on the exterior of the main housing  4 . By rotating the knob  118 , the user can direct smoke from the wood pellets  70  to the right or left sides of the cooking grate, as shown in FIGS. 6A and 6B respectively, or, by orienting the vane  114  in a central position, as shown in FIG. 6C, to the entire cooking grate.  
         [0024]    It will be appreciated that the invention is not restricted to the particular embodiment that has been described, and that variations may be made therein without departing from the scope of the invention as defined in the appended claims and equivalents thereof. For example, in a modification of the FIG. 4 embodiment, the plate  80  may have a smooth upper surface but be inclined slightly downwards from the inlet opening towards the discharge opening so that vibration of the plate induces a net movement of the pellets in the direction of the discharge opening. Unless the context indicates otherwise, a reference in a claim to the number of instances of an element, be it a reference to one instance or more than one instance, requires at least the stated number of instances of the element but is not intended to exclude from the scope of the claim a structure or method having more instances of that element than stated.