Patent Publication Number: US-9903595-B2

Title: Noise reduction in cooking system

Description:
BACKGROUND 
     Cooking may produce various volatile and particulate byproducts. Thus, an interior cooking installation may include a ventilation system for removing such byproducts. Many ventilation systems vent to an exterior of the cooking environment to avoid recirculating such byproducts into the cooking environment. Installing such ventilation systems may be quite expensive, as installation may involve structural modifications of a cooking facility. Additionally, ventilation systems also may produce significant noise, which may impact a dining experience where the ventilation system is located close to a dining area. 
     SUMMARY 
     Examples are disclosed herein that relate to cooking systems with internal ventilation systems. One example provides a cooking system including a body supporting a cooking surface, an air duct located within the body, and an air inlet disposed adjacent the cooking surface and in fluid communication with the air duct. The cooking system further comprises a fan disposed within the body and configured to pull exhaust from cooking through the air inlet and the air duct, a muffler configured to receive the exhaust from the fan, and an exhaust duct disposed within the body and connecting the fan to the muffler to carry the exhaust from the fan to the muffler, the exhaust duct having a curved configuration between an outlet of the fan and an inlet of the muffler. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an example cooking system. 
         FIG. 2  shows a top view of the cooking system. 
         FIG. 3  shows a top view of the cooking system with a cooking surface removed. 
         FIG. 4  shows the cooking system having a back portion removed. 
         FIG. 5  shows example components of a ventilation system. 
         FIG. 6  shows another view of the example components of  FIG. 5  with some surfaces removed. 
         FIG. 7A  and  FIG. 7B  show an example tapered channel structure that extends between an electrostatic precipitation system and fan of an example cooking system. 
         FIG. 8  shows two example cooking systems in an example arrangement. 
     
    
    
     DETAILED DESCRIPTION 
     In some indoor cooking settings, such as a restaurant, foods may be prepared in the presence of customers rather than in a separate kitchen. One example of such a setting is a teppanyaki-style restaurant, in which food preparation atop a large cooking surface is observed by customers sitting at a table surrounding the cooking surface. In such settings, a ventilation system hood is often positioned over the cooktop, and the ventilation system vents to the outside of the restaurant. Installing such systems may be expensive, and may involve modification of the roof and ceiling of the facility. Further, cleaning such ventilation systems may require accessing a roof of the facility. 
     Recently, indoor cooking grills have been developed with internally integrated ventilation systems that permit cooking exhaust to be cleaned, cooled and vented back into the cooking environment. Such internally ventilated grill systems may be installed without modifying the roof or ceiling of the cooking environment, and thus may provide significant cost savings to a cooking facility. Further, such ventilation systems may be conveniently accessed for cleaning. However, in such a system, the fan that pulls cooking exhaust away from the cooking surface is located within a body of the grill, rather than above a ceiling or on a roof of a facility. As a relatively high exhaust velocity may be employed to cool the exhaust sufficiently for internal venting, the fan and exhaust flow out of the grill both may produce noise. 
     Accordingly, examples are disclosed herein that relate to reducing ventilation system noise in an internally ventilated cooking system. Briefly, the examples provide for a cooking system having a curved exhaust duct connecting a fan to a muffler. The use of a curved exhaust duct between the fan outlet and the muffler inlet may allow a longer muffler to be used than if the path from the fan outlet into the muffler inlet were straight. Such a duct also may increase a path length of an exhaust path through the cooking system relative to the use of a straight path between the fan outlet and muffler inlet due to the combined length of the curved duct and longer muffler, and thereby may help to cool exhaust to a greater extent than an exhaust path without the curved duct and with a smaller muffler. Additionally, the disclosed examples may include a noise reduction screen on the body of a cooking system to reduce impingement noise arising from muffler exhaust of another cooking system arranged in a back-to-back manner, as found in some teppanyaki restaurants. 
     A cooking system may have other sources of noise than exhaust noise. For example, the cooking system may include a filtration assembly between the air duct and the fan, and a tapered channel structure (e.g. a cone-shaped flange connector) connecting the filtration assembly to the fan. Depending upon the construction of the tapered channel structure and the fan, low frequency resonances may form that are audible within the cooking environment. As such, the tapered channel structure may be configured to avoid such resonances, thereby helping to further reduce noise. 
       FIG. 1  shows a rear perspective view of an example cooking system  100 . The cooking system  100  includes a body  102  supporting a cooking surface  104 , and an air inlet  106  disposed adjacent to the cooking surface  104 .  FIG. 2  shows a top plan view of the cooking system  100 . The body includes a front side  108  by which customers may sit, and a backside  110  of the body  102  by which a chef may stand when preparing food. The cooking system  100  also includes a noise reduction screen  128  positioned on the backside  110  of the body  102  at a location laterally spaced from an outlet  130  of the muffler  122 . 
       FIGS. 3 and 4  respectively show top and back perspective views of the cooking system  100  of  FIG. 2  with some external surfaces removed to illustrate internal components. The body  102  encloses an air duct  112  in fluid communication with the air inlet  106  to receive exhaust pulled through the air inlet  106 . Further, an internal housing  115  that contains a fan  116  and electrostatic precipitator system  118  is disposed within the body  102 .  FIG. 3  also shows a curved exhaust duct  120  connecting an outlet of the fan  116  to an inlet of a muffler  122 . 
     In some examples, the fan  116  may take the form of a blower wheel fan (e.g. a squirrel cage fan) that draws air in along an axial direction relative to the blower motion, and exhausts the air in a direction tangential to the blower wheel motion. In the arrangement of  FIG. 4 , if the outlet of the fan  116  were directed toward the backside  110  of the body  102 , it would be difficult to include a muffler between the fan outlet and the cooking system exhaust outlet  130  back of the body without the muffler extending a potentially significant distance out of the body. 
     Thus, the outlet of the fan  116  of the cooking system  102  is oriented toward a front side  108  of the cooking system  102 , and a curved exhaust duct redirects the air into a muffler.  FIG. 5  is a rear perspective view of an example curved duct  120  and muffler  122  configured to receive exhaust from a fan housed in an internal housing  115 .  FIG. 6  is a front perspective view of these structures with a portion of the internal housing  115  removed to illustrate the fan  116  and electrostatic precipitator  118 . Exhaust from the air duct  112  may pass through a first filtration stage (not shown), and then into the electrostatic precipitator  118 . The electrostatic precipitator system  118  may include various filters in addition to the electrostatic precipitator, such as inlet and exit filters disposed respectively upstream and downstream of the electrostatic precipitator. The electrostatic precipitator  118  is connected to an inlet of the fan  116  via a tapered channel structure  600 , as mentioned above. 
     In the depicted example, the fan exhaust is oriented toward the front side  108  of the cooking system  100 . Exhaust from the fan  116  is directed into the curved exhaust duct  120 , which redirects the exhaust into the muffler  122 . As can be seen, the use of the curved exhaust duct  120  allows a longer muffler to be incorporated within the body  102  of the cooking system  100  than if the fan outlet were directed toward the backside  110  of the cooking system  100 . In the depicted examples, the exhaust duct  120  includes a 180-degree turn between the outlet of the fan  116  and the inlet of the muffler  112 . In this configuration, the turn of an exhaust duct may have any suitable angular magnitude, such as between 160-200 degrees, or between 170-190 degrees. A duct having a turn in this range may redirect a flow of fan exhaust from a direction toward a front of a cooking system to a direction toward a back of a cooking system. In other examples, a duct may have any other suitable curvature, depending upon a direction in which a fan directs exhaust and a side of a cooking system from which the exhaust is to be vented after passing through a muffler. 
     The cooking system  100  may further include a sound-dampening material disposed on one or more surfaces within the body of the cooking system. For example, sound-dampening material may be placed on the filtration assembly  118 , air duct  112 , exhaust duct  120 , fan  116 , as well as the inside surfaces of the body walls. Any suitable sound-dampening material may be applied to such surfaces. 
     As mentioned above, various structures within the ventilation system of cooking system  102  may on occasion be subject to low frequency pressure oscillations, which may be audible. As such, continuing with  FIG. 6 , the tapered channel structure  600  may be formed in a way that helps to avoid such oscillations.  FIG. 7A  shows a side view of an example of the tapered channel structure  600  attached to the fan  116 , and  FIG. 7B  shows a cross-sectional view representing section A-A illustrating these components.  FIG. 7B  shows the fan  116  attached to the tapered channel structure  600 , such that a portion of the tapered channel structure  600  is surrounded by and/or inserted into a body of the fan  116 . It is noted that the inserted portion of the tapered channel structure  600  terminates without a flared end (e.g. the radius of the tapered channel does not increase at the end of the taper in a direction from the electrostatic particulate system to the fan). Any suitable length of the tapered channel structure  600  may be inserted into the body fan  116 . As a non-limiting example, a length of more than ⅛ inch may be inserted into the body of the fan. Further, the tapered channel structure  600  is illustrated as having a relatively smooth curve. The use of such a shape for the tapered channel structure  600  may help to reduce the occurrence of low frequency noise compared to a tapered channel structure of a different shape, e.g. where the inserted portion has a flared configuration, and/or where the taper is discontinuous and/or segmented. 
     The fan may take any suitable form. For example, the fan  116  may take the form of a blower wheel fan. The use of a rigid blower wheel, such as a metal or composite blower wheel, may offer advantages over the use of a less rigid blower wheel, such as a blower wheel made from a flexible plastic, as a less rigid blower wheel may cause noticeable vibration in the cooking system, whereas a more rigid blower wheel may avoid such vibrations. Likewise, in some examples, the tapered channel structure  600  may be formed at least partially from a less rigid material, e.g. a plastic material, while in other examples, the tapered channel structure  600  may be formed at least partially from a rigid material. 
       FIG. 8  shows a plan view of an example arrangement of two cooking systems  800  and  810 . Restaurants may arrange cooking systems in this manner to maintain a separation of customer space and staff space. However, exhaust exiting out of the backside of one cooking system may impinge on the backside of the other cooking system, resulting in noise. Thus, as mentioned above, the cooking systems  800 ,  810  may include noise reduction screens  802 ,  812  positioned to mitigate impingement noise arising from exhaust of adjacent cooking systems. As mentioned in  FIG. 1 , a noise reduction screen  128  is positioned on the backside  110  of the body  102  of the cooking system  100  at a location laterally spaced from an outlet  130  of the muffler  122 . As shown in  FIG. 8 , exhaust  804  exiting from muffler outlet  806  of the cooking system  800  is directed towards the noise reduction screen  812  of neighboring cooking system  810 . Likewise, exhaust  814  exiting from muffler outlet  816  of the cooking system  810  is directed towards the noise reduction screen  802  of the cooking system  800 . As such, each of the noise reduction screens  802 ,  812  may reduce potential noise resulting from exhaust impinging on the backside of the other cooking system. 
     It will be understood that the configurations and/or approaches described herein are exemplary in nature, and that these specific embodiments or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and/or described may be performed in the sequence illustrated and/or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed. 
     The subject matter of the present disclosure includes all novel and nonobvious combinations and subcombinations of the various processes, systems and configurations, and other features, functions, acts, and/or properties disclosed herein, as well as any and all equivalents thereof.