Patent Publication Number: US-6655393-B2

Title: Grease exhaust cleaning system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of application Ser. No. 09/632,560, filed Aug. 4, 2000, now U.S. Pat. No. 6,357,459. issued Mar. 19, 2002. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the cleaning of ventilation passages such as ducts or flues. More specifically, the present invention relates to the cleaning and maintenance of ventilation passages associated with kitchen ventilation systems wherein grease or other airborne particulates may accumulate within the passageway structure. 
     2. State of the Art 
     Restaurants, cafeterias or other such facilities where large amounts of food are cooked and prepared typically implement cooking hoods adjacent the food preparation area. Cooking hoods are large ventilation openings, often overhanging the cooking area such as the stove. The hoods are coupled with air passages, such as ducts or flues, which lead to an external environment. An air handling unit is coupled to the air passages to draw air from the cooking area through the passages and to the external environment. In essence, the hood is an exhaust system to draw smoke, heat and gases created in the cooking and preparation of food away from the cooking area. Such systems are not only desirable, but are typically required for facilities preparing large quantities of food. These systems, however, are not limited to commercial establishments and are often found in residential dwellings. 
     Over an extended period time, use of the hood and exhaust system results in an accumulation of cooking grease and other associated particulates along the interior of the ventilation ducts. Accumulation of grease within the exhaust system poses various hazards and further impacts the safety and efficiency of the system. The most obvious hazard is the possibility of a fire. The close proximity of the exhaust system to the cooking area, typically above the stove or cooking range, combined with the hot gases passing through the ventilation ducts, creates a serious threat of combustion within the ducts which may develop if the system is not properly maintained. Accumulation of grease within the ductwork, for any length of time, also negatively affects the cleanliness and sanitary condition of a food preparation area, which can affect both food preparers and patrons. 
     Beyond sanitary and safety concerns, the operation of an exhaust system can be impeded without proper cleaning and maintenance of the duct system. Air handling systems are designed to operate at specific airflow capacities. Typically, a given facility is designed to have an air supply and an air return or, alternatively, an exhaust. It is noted that an air return and an air exhaust are not the same concept. Air return typically refers to the passage of a volume of air from a specific location within a building to the air handling unit for conditioning of the air and subsequent reintroduction of the air into the building. On the contrary, the term exhaust more typically refers to the removal of air from an interior of a building to an external environment. The integration of the supply, return, and exhaust subsystems into a complete system requires design and adjustment of each subsystem with regard to the rate of airflow (expressed in cubic feet per minute, or CFM) imposed upon a particular environment. The system may be designed to create a positive pressure requiring a net positive supply of air (i.e., the supply being rated at a higher CFM than the return/exhaust). Conversely, a system may be designed to create a negative pressure requiring a net negative supply of air. The most common design is a balanced system wherein the supply of air equals the return and/or exhaust of the air. 
     The intended use of a specific room, such as for cooking, determines, at least in part, the design of the air system. With this in mind, the accumulation of grease or other materials within a ventilation duct can restrict airflow and prevent the overall air system from operating efficiently. For example, an eight inch diameter duct experiencing a quarter inch accumulation of grease on the interior walls represents approximately a thirteen percent reduction in area. A reduction in the cross sectional area of the duct results in an altered rate of air flow thus disrupting the overall system performance. 
     To ameliorate the above hazards and impediments, ducts must receive regular cleaning and maintenance. Indeed, with regard to commercial establishments, local ordinances often impose scheduled cleaning of such systems. However, such scheduled cleaning is not always performed. Noncompliance may be based upon a number of factors. Removal of accumulated grease from a ventilation system is typically a difficult and time consuming process. The tight confined spaces of a ventilation system make it extremely difficult to manually remove accumulated grease. For example, a ventilation duct running from the cooking area to an external outlet is typically formed of numerous vertical, horizontal and angular sections joined together. The angular connection of each section makes it difficult for cleaning implements to pass from one section to another. Thus, manual cleaning is typically required, which entails cleaning the ducts section by section. Furthermore, each section varies in length. In many cases a length of duct may be a hundred feet or more requiring clean-outs, or access doors, to be spaced along the length. Each clean-out must then be accessed individually in order to appropriately clean the entire length of duct. The job is even more onerous when the length is horizontally positioned, and the cleaning process cannot be assisted by gravity to help extricate the grease from the duct. Manual cleaning of such exhaust systems is tedious, time consuming, and not always effective. 
     To assist in the cleaning of ventilation ducts, various systems and devices have been implemented. However, these devices have not been entirely effective and, in many instances, have created additional difficulties. For example, U.S. Pat. No. 3,795,181 issued to Lawson discloses an apparatus for cleaning a ventilation flue utilizing a fixture mounted within the interior of the flue or duct. The system includes a plurality of nozzles or spraying devices mounted on a common tube. A turbine is mounted at the base of the tube causing the tube to rotate about its longitudinal axis upon the passage of fluid through the turbine. While this system may be effective in cleaning the surface of the duct adjacent the plurality of nozzles, it poses various problems. A system of this type does not account for the need to clean out multiple sections, whether they be vertical, horizontal or angular. Indeed, the disclosure only teaches the cleaning of the first vertical section immediately adjacent the hood, or ventilation inlet. Additionally, the system must be physically mounted within the ventilation ductwork requiring various physical modifications to the ductwork and hood. Such a device may be difficult to implement in an existing ventilation system. As a permanent fixture within the duct or flue, the device presents an additional surface to which grease and other particulates can adhere leading to an accumulation of grease within a smaller region of the duct. 
     Another approach may be seen in U.S. Pat. No. 4,031,910 issued to Lawson. The device disclosed attempts to address the issue of cleaning independent duct lengths regardless of angular orientation. The device also utilizes a tube containing a plurality of spray nozzles, the tube rotating about its longitudinal axis. However, the instant device attempts to put an individual rotating tube in each section of duct, with pipe fittings such as elbows connecting each rotating tube section. While this device attempts to address the issue of cleaning each duct section regardless of its angular orientation, it still poses a few drawbacks. Again, this device is a permanent fixture to be mounted within the ducts. Installation of such a device undoubtedly requires disassembly of any existing ductwork. Such an installation would be time consuming and would likely be cost prohibitive. Thus, there is little likelihood that owners of existing systems would implement such a device. Furthermore, as discussed above, additional components mounted in the interior of the ductwork may result in an increase of grease accumulation over shorter periods of time. 
     In view of the shortcomings in the art, it would be advantageous to provide an apparatus for cleaning ventilation systems which is effective in removing accumulated grease and deposits, thus reducing or eliminating the need for manual cleaning of the ductwork. 
     It would also be advantageous to provide a device which does not require any special or permanent fixtures within the ductwork. Such a system could be portable and utilized within various systems regardless of duct length or cross sectional area. 
     It would be a further advantage to provide a system which is easily implemented within a ventilation system having a plurality of ducts or angular orientations. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with one aspect of the invention, an apparatus for cleaning a ventilation passageway is provided. The cleaning device includes a body having a central axis. A fluid channel is formed within the body and is defined to have a first and second end. The first end of the fluid channel is adapted to be removably coupled to a fluid source. A nozzle (or alternatively a plurality of nozzles) is sealingly coupled to, and in communication with, the fluid channel. The nozzle is configured to rotate about the central axis. The nozzle may be positioned such that fluid passing through the nozzle causes the nozzle to rotate about the central axis. Furthermore, the nozzle may be positioned such that fluid passing through it propels the entire cleaning device in a direction along the central axis. 
     A cage is coupled to the body and circumscribes the nozzle. The cage keeps the nozzle from striking an interior surface of a duct during operation of the cleaning device. The cleaning device may be utilized in ducts of various shapes and sizes. The self-propelling feature of the cleaning device, coupled with a properly designed cage, allows the apparatus to work its way through a system of ducts, including maneuvering through elbow type connections or angular transitions of the duct. For example, the cleaning device may transition from a vertical section to an angular, or a horizontal section, for efficient cleaning of the interior of the entire ventilation system. 
     In accordance with another aspect of the invention, a method is provided for the cleaning of ventilation passageways. The method includes providing an apparatus having a body, a fluid nozzle rotatably coupled to the body and a cage which circumscribes the nozzle. The apparatus is placed in the ventilation passageway and the nozzle is then operably coupled to a fluid source. Fluid is passed through the nozzle and sprayed on the interior of the duct. The nozzle is rotated about a central axis such that the fluid being sprayed from the nozzle is distributed about the entire region adjacent the apparatus. The nozzle is also configured such that passage of fluid through the nozzle imparts a propelling force to the apparatus along the central axis. 
     The fluid which is passed through the nozzle may be introduced at a high pressure, creating a greater propelling force, as well as a stronger shearing force when the spray contacts the duct surfaces. The fluid may also be heated prior to passage through the nozzle for influencing the physical characteristics of the accumulated deposits within the duct. Similarly the fluid may contain a composition for the dissolution of grease or other type of accumulated matter to improve the efficiency of the cleaning operation. 
     The method may further include placing a catch basin below the ductwork such that fluid and removed matter may exit through the duct system to be collected by the catch basin. Alternatively, the duct system may be sealed at one end to prevent the fluid and removed matter from exiting the duct in an uncontrolled manner. A drain pipe or other type of outlet may then be connected to the sealed end for displacing the waste material to a remote location. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention, the advantages of this invention can be more readily ascertained from the following description of the invention when read in conjunction with the accompanying drawings in which: 
     FIG. 1 is an elevational view of an apparatus according to one embodiment of the invention; 
     FIG. 2 is an elevational view of a portion of the apparatus disclosed in FIG. 1; 
     FIG. 3 is a bottom view of the apparatus shown in FIG. 1; 
     FIG. 4 is a partial sectional view of the apparatus of the present invention employed in a duct system; 
     FIG. 5 is an additional partial sectional view of the apparatus of the present invention employed in a duct system; 
     FIG. 6 is a partial sectional view of the apparatus upon completion of cleaning a duct system; 
     FIG. 7 is an elevational view of an alternative embodiment of the cleaning device of the present invention; and 
     FIG. 8 is an elevational view of yet another alternative embodiment of the cleaning device of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, an apparatus  10  for cleaning ducts, flues, or ventilation passageways according to one embodiment of the present invention, is shown. Apparatus  10  includes a cleaning/spraying device  12 , a fluid transfer component or hose  14 , and a fluid source  16 . The cleaning device  12  is adapted for introduction into a duct or passageway for maneuvering through the passageway for removal of accumulated deposits. The fluid source  16  may be any of a number of fluid sources known in the art. For example, it may include a pump or other means for supplying fluid at a specified rate and pressure. It may also include a heating element for controlling the temperature of the fluid, or a mechanism for introducing, mixing and diluting various chemicals within the base fluid. Such devices and capabilities are well-known to those of ordinary skill in the art and are, therefore, not discussed in greater detail herein. 
     The fluid transfer component  14  couples the fluid source  16  to the cleaning device  12 . While other embodiments are contemplated as being within the scope of the invention, the presently described embodiment is formed of a flexible conduit  18  such as a tubing or hose. The flexible conduit is preferably capable of handling fluids at high pressure. The flexible conduit  18  or hose includes a first coupling  20 , shown in the present embodiment as a male quick-connect, at one end, and a second coupling  22 , shown as a corresponding female quick-connect, at the other end of the hose  18 . The couplings  20  and  22  allow for greater portability, as well as easier setup and operation of the apparatus  10 . They also allow flexibility in combining different components for an operation dependent on specific cleaning requirements. For example, some ducts, based on their cross sectional dimensions, may require a cleaning device  12  to have certain minimum or maximum dimensions. Likewise, the length of the ducts will likely vary from one operation to another. This not only affects the required length of the hose, but may affect the required diameter of the hose based of fluid flow requirements. Similarly, different fluid sources may be utilized in different situations. Thus, interconnectivity of the components adds great flexibility to the overall use and operation of the apparatus  10 . 
     A valve  24  is located adjacent to the first coupling  20 . The valve  24  is placed in the fluid path to control fluid flow from the fluid source  16  to the cleaning device  12 . The valve  24  operates to control fluid flow to the cleaning device  12  from the fluid source  16  and through the first coupling  20 . It is noted that while the valve  24  is depicted as being adjacent to the first coupling  20 , the valve  24  may be located at any location between the fluid source  16  and the cleaning device  12 . The location of the valve is preferably positioned to maximize acceptability and ease of operation during use of the apparatus  10 . 
     Referring now to FIGS. 2 and 3, a preferred embodiment of the cleaning device  12  is shown from a side view and a bottom view, respectively. The cleaning device  12  is formed of various components which may be collectively considered the body  30  of the device. The body includes a coupling device  32 , which is shown here to be a male quick-connect that is configured to mate with the female second coupling  22 , shown in FIG.  1 . The coupling device  32  is connected to a conduit section  34 , such as pipe or tubing which is appropriately sized and rated. FIG. 2 shows the connection to be a threaded connection  36 , such as a threaded nipple, however, any other known mechanical connective means are considered to be appropriate as well. A rotatable connection  38 , such as a union, swivel or bearing, is connected to the conduit section  34 . The rotatable connection  38  is also shown to be connected to the conduit  34  by means of threaded connections  40 , however, other fastening means may be employed, such as for example, welding, flanged connections, or any other mechanical means of forming a connection with a fluid tight seal. The body  30  also includes a stem  42 , or a second conduit, coupled to the rotatable connection  38 . 
     The body  30  thus comprises several components sealingly coupled together forming an internal fluid path or channel between the coupling device  32  and the stem  42 . The body  30  also forms a member which has two sections, one being rotatable with respect to the other. Specifically, the stem  42  is rotatable relative to the conduit  34  about an axis generally defined to run through the body from the coupling device  32  through the stem  42 . For sake of convenience and clarity, this axis shall be referred to as the central axis in the specification. It is noted that while the central axis has been defined in terms of the location of physical components, this is not to be considered limiting in any sense. Rather, the axis is actually determined by the relative path of the various components described below. In the presently described embodiment, the axis coincides with both descriptions. 
     While the body  30 , as described above, is formed of multiple components, it may be constructed using other various techniques. For example, the body may be constructed, in large part, by a casting or forging process. Similarly, other constructive techniques are contemplated as being acceptable. However, the mating of various components as discussed above offers the advantage of being simple and inexpensive. Such components are often readily available as standard, off-the-shelf pipe or tube fittings. Another advantage of the disclosed embodiment is the ease of replacement of individual parts, if necessary. A substantially unitary body, while offering other advantages, does not allow for such convenience. 
     Coupled to the stem  42  of the body  30  is a tee  44 . The tee  44  is used to divide and divert the fluid flow from the body into different directions. In this case, the tee  44  serves to divide the flow between two nozzles  46 , each being coupled to a separate end of the tee  44 . Each nozzle  46  includes an orifice  48  of reduced size such that fluid which passes through orifice  48  is accelerated. The orifice  48  thus forms a fluid stream having a defined trajectory and spray pattern. As seen in FIG. 2, the nozzles  46  are positioned such that the orifices  48  project a fluid stream having a generally downward and angled trajectory with respect to the horizontal plane formed by the tee  44 . As seen in FIG. 3, the nozzles  46  and orifices  48  are positioned such that the trajectory of the fluid stream is formed at an angle with respect to the radial axis defined by the tee  44 . In other words, the trajectory axis as seen in FIG. 3 does not intersect the central axis that runs through the body  30 . The nozzles  46  and/or orifices  48  can be designed to lie at various angles and to provide various spray patterns (e.g., fan or stream). 
     The angular position of the nozzles  46  plays a significant role in the operation of the cleaning device  12 . Reactionary forces experienced by the nozzles  46 , due to the flow of fluid through the orifices  48 , impart a rotating motion to the nozzles  46 , tee  44 , and stem  42 . This causes the nozzles  46  to rotate about the central axis relative to the lower portion of the body  30 , including the conduit section  34 . Furthermore, reactionary forces experienced by the nozzles  46  in combination with the downward placement of nozzles  46  also propel the cleaning device  12  in a direction which is substantially along the central axis about which the nozzles rotate. Thus, the nozzles  46  serve to both provide a rotating cleaning spray to the interior surfaces of a ventilation passageway as well as to move the cleaning device  12  along the pathway of the duct. 
     A cage  50  is coupled to body  30 , and more specifically, as shown in the disclosed embodiment, the cage  50  is coupled to the conduit section  34 . The cage  50  is formed to circumscribe or surround the nozzles  46 , as well as their rotative path. As seen in FIG. 2, the cage  50  includes an upper portion which is semispherical. As shall be seen below, the semispherical shape allows the cleaning device  12  to maneuver through various angular transitions which may be encountered in a ventilation passageway. Referring to both FIG. 2 and 3, the disclosed embodiment includes a cage  50  which might be described as having two hoop type members  50 A and  50 B coupled together in a substantially perpendicular manner. This arrangement is efficient in that it is conducive to use in ducts of various cross-sectional shapes. The cage is easily maneuvered through ducts or passageways having circular, square, or even rectangular cross-sectional geometries, which are the most commonly encountered. It is contemplated, however, that other configurations might be utilized. For example, additional hoop members might be utilized to substantially form a cylindrical shape when viewed from beneath (i.e., as in FIG.  3 ). Such an embodiment might be particularly suited for use in a duct having a circular cross section. Another alternative might be to form the cage with the hoops being joined in a nonperpendicular manner. This would result in a cage more particularly suited for ducts having a rectangular cross-sectional area. Regardless of the number or angular orientation of the individual hoop members  50 A and  50 B, the cage could also be formed to be entirely spherical. Such a spherical cage could be used in ducts which require a higher degree of maneuverability for proper navigation of the duct by the cleaning device  12 . 
     The cage  50  may be coupled to body  30  by any suitable mechanical means. Indeed, the method of fastening the cage  50  to the body may be dependent upon the material from which the cage  50  is formed. In the disclosed embodiment, the cage  50  is contemplated as being formed of stainless steel. Stainless steel offers the advantage of being corrosion resistant. Furthermore, stainless steel may be effectively and efficiently fastened to the body  30  by welding. Of course other materials may be utilized to form the cage and may be equally suited for the task. Similarly, the cage  50  need not be fastened to the body  30  by welding. Instead, it is contemplated that an appropriate coupling device may be positioned on the body  30  for removable coupling of the cage  50  to the body  30 . A removable coupling, while possibly adding complexity to the manufacture of the cleaning device  12 , would offer the advantage of flexibility in choosing a cage size and configuration which is appropriately suited for a duct having a particular size and geometric configuration. 
     Referring now to FIGS. 4,  5 , and  6 , a representative duct system  60  is shown in which the cleaning apparatus  10  is typically operated. Starting at the exhaust end  62  of the duct system  60 , a first vertical leg  64  enters the interior of a building through the roof  66 . The first vertical leg  64  makes an angular transition  68  to a horizontal leg  70 . The horizontal leg  70  makes a second angular transition  72  to a second vertical leg  74  of duct system  60 . The second vertical leg  74  extends through the ceiling  76  of a food preparation area and connects with an exhaust hood  78 . A catch-basin  80  can be placed below the hood to contain any resultant drainage  82  created by operation of the cleaning device. While not shown, the food preparation area adjacent the catch-basin  80  might also be covered with protective material to protect the equipment from splashing or errant discharge. 
     Referring to FIG. 4, the cleaning device  12  is connected to a fluid transfer component  14  which, in turn, is coupled to an appropriate fluid source (not shown). The cleaning device  12  is introduced into the first vertical leg  64  of duct system  60  at the exhaust end  62  of the duct system  60 . Fluid is then passed through the nozzles  46  of the cleaning device  12  and the fluid is sprayed onto the interior surfaces of the duct system  60 . The reactionary force of the spray propels the cleaning device downward through the first vertical leg  64 , cleaning the duct as it passes through. 
     Referring to FIG. 5, the cleaning device  12  is shown maneuvering through the angular transition  68  formed between the first vertical leg  64  and the horizontal leg  70 . The propelling force, combined with the semispherical shape of the cage  50  allows the cleaning device  12  to rotate through the angular transition  68  so that it may continue through the horizontal leg  70 . The cleaning device  12  then continues to propel itself through the horizontal leg  70 , cleaning the interior surfaces of the duct as it passes through. 
     Referring to FIG. 6, the cleaning device  12  has now navigated its way through the entire duct system  60 . Following the horizontal leg  70 , the cleaning device  12  is maneuvered through the second angular transition  72  and continued through the second vertical leg  74  until it exits through the exhaust hood  78 . The fluid source  16  (not shown) is now rendered inoperable, either by turning it off, or operating a valve to terminate the fluid flow. The cleaning device  12  may now be disconnected from the hose  14  and removed. The hose  14  is subsequently pulled through the ductwork. If desired, the operation may now be repeated for a second cleaning, if it is required. Alternatively, the cleaning device  12  can be initially passed through the duct system  60  to spray a solvent or other grease-dissolving chemical or cleaner, followed by a second operation where the cleaning device  12  sprays a fluid to rinse away any remaining grease or contaminants within the duct system  60 . 
     It is noted that various modifications are contemplated as being within the scope of the invention. For example, while the disclosed embodiment relies on the angular position of the nozzles to impart rotative motion to the nozzles, rotation may be accomplished by other means. For example, as illustrated in FIG.  7  and FIG. 8, a fluid turbine may be housed within the body  30  of the cleaning device  12  and operatively attached to the tee  44  and the nozzles  46 . Passage of fluid across the turbine (shown by arrows) would then impart rotary motion to the turbine, and subsequently to the tee  44  and the nozzles  46 . The use of a turbine for rotary motion would thus make the angular position of the nozzles  46 , relative to the radial axis, of less significance. Alternatively, as another example, a fluid turbine  94  having a plurality of orifices  48  (e.g., jet orifices) may be mounted on rotatable connection  38  by any suitable means, such as a bearing means as shown in FIG.  8 . The orifices  48  form a fluid stream having a defined trajectory and spray pattern, and are positioned to project a fluid stream having a generally downward and angled trajectory in relation to the horizontal axis of the fluid turbine  94  when fluids are introduced through the body  30 , as described in reference to FIG. 2 above. 
     In all of the illustrated embodiments, it is also contemplated that adjustable, and/or replaceable nozzles  46  may be used with the cleaning device  12 . Adjustable nozzles would allow the user to define the angular position of the nozzles  46  effectively adjusting the rotative and propulsive forces experienced by the cleaning device  12 . Thus, in certain situations, it may be desirable to have the cleaning device travel at a slower rate through the duct work. Similarly, it may be desirable to change the trajectory angle of the fluid stream depending on the type of material, or level of accumulation within the duct. Use of replaceable nozzles would allow the user to change spray patterns. For example, a direct stream nozzle might be replaced by a nozzle creating a fan pattern for subsequent washing or treatment of the duct system. The ability to interchange nozzles would allow further customization of the cleaning device  12  for use with a specific duct system. 
     It is also noted that while the invention has been disclosed in terms of cleaning exhaust systems associated with food preparation areas, the invention is not be considered as being limited to such an environment. Indeed, numerous applications exist for the invention in which extended narrow passages require cleaning or maintenance, particularly in situations which require navigation through angular transitions. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions, and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.