Abstract:
An air cleaner including an improved airflow path is provided according to the invention. The air cleaner includes a duct extending between an air inlet of the air cleaner and an air outlet, with the duct being configured to conduct an airflow. The duct includes a shaped input region located downstream of one or more air cleaning components and upstream of an impeller, a curved transition region downstream of the shaped input region, with the curved transition region transitioning the airflow from an air inlet orientation to an air outlet orientation, and an expansion output region downstream of the curved transition region, with the expansion output region allowing the airflow to expand. The air cleaner further includes the impeller located in the curved transition region of the air duct. The airflow is smoothly conducted from the air inlet to the air outlet by the duct.

Description:
TECHNICAL FIELD 
     The present invention relates to an air cleaner, and more particularly, to an air cleaner including an improved airflow path. 
     BACKGROUND OF THE INVENTION 
     Air cleaners are widely used in home and office settings for cleaning the air. An air cleaner can filter the air in order to remove airborne contaminants. An air cleaner can therefore include any type of mechanical filter element comprising a mesh, a weave, a foam, etc. An air cleaner can include an odor absorber element that removes odor-causing particles from the air stream. An air cleaner can further include electrical air cleaning components, such as a collector cell that removes dirt and debris from the airflow of the air cleaner and can include an ionizer. 
     An air cleaner also includes some manner of air moving device that creates an airflow through the filter element and/or electrical air cleaning components. The air moving device can include one or more speed settings that allow the user to control the level of operation of the air cleaner and the resulting volume and speed of the airflow. The user can manipulate controls provided through a control panel in order to select from available operating features or settings. 
     In use, a motor converts electrical power into rotation of an impeller. The impeller creates an airflow. It is highly desirable that the electrical power is efficiently transformed into airflow. In addition, it is highly desirable that the airflow is created without undue turbulence and noise. Turbulence and noise decrease efficiency of the air cleaner and increase user dissatisfaction. 
     SUMMARY OF THE INVENTION 
     An air cleaner including an improved airflow path is provided according to the invention. The air cleaner comprises a duct extending between an air inlet of the air cleaner and an air outlet, with the duct being configured to conduct an airflow. The duct comprises a shaped input region located downstream of one or more air cleaning components and upstream of an impeller, a curved transition region downstream of the shaped input region, with the curved transition region transitioning the airflow from an air inlet orientation to an air outlet orientation, and an expansion output region downstream of the curved transition region, with the expansion output region allowing the airflow to expand. The air cleaner further comprises the impeller located in the curved transition region of the air duct. The airflow is smoothly conducted from the air inlet to the air outlet by the duct. 
     An air cleaner including an improved airflow path is provided according to the invention. The air cleaner comprises a duct extending between an air inlet of the air cleaner and an air outlet, with the air outlet being substantially non-linear with the air inlet and with the duct being configured to conduct an airflow. The duct comprises a shaped input region located downstream of one or more air cleaning components and upstream of an impeller, a curved transition region downstream of the shaped input region, with the curved transition region transitioning the airflow from an air inlet orientation to an air outlet orientation, and an expansion output region downstream of the curved transition region, with the expansion output region allowing the airflow to expand. The air cleaner further comprises the impeller located in the curved transition region of the air duct. The airflow is smoothly conducted from the air inlet to the air outlet by the duct. 
     A method of forming an air cleaner including an improved airflow path is provided according to an embodiment of the invention. The method comprises providing a duct extending between an air inlet and an air outlet of the air cleaner and configured to conduct an airflow, providing a shaped input region in the duct and located downstream of one or more air cleaning components and upstream of an impeller, providing a curved transition region in the duct downstream of the shaped input region, with the curved transition region transitioning the airflow from an air inlet orientation to an air outlet orientation, and providing an expansion output region in the duct downstream of the curved transition region, with the expansion output region allowing the airflow to expand. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The same reference number represents the same element on all drawings. 
         FIG. 1  is an overhead view of an air cleaner including an improved airflow path according to an embodiment of the invention. 
         FIG. 2  is a section view AA of the air cleaner according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-2  and the following descriptions depict specific embodiments to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these embodiments that fall within the scope of the invention. Those skilled in the art will also appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific embodiments described below, but only by the claims and their equivalents. 
       FIG. 1  is an overhead view of an air cleaner  100  including an improved airflow path according to an embodiment of the invention. The air cleaner  100  includes a chassis  101 , a control panel  103 , an air outlet  106 , and an impeller  107 . Other components are shown in  FIG. 2  and are discussed below. The impeller  107  is visible through the air outlet  106 . The impeller  107  is rotated by a motor (not shown) in order to create airflow through the air cleaner  100 . Airflow traveling through the air cleaner  100  is exhausted through the air outlet  106 . 
     The air cleaner  100  can comprise a tabletop air cleaner in some embodiments. However, the air cleaner  100  can alternatively be a floor model, etc. 
       FIG. 2  is a section view AA of the air cleaner  100  according to an embodiment of the invention. This view further shows a duct  102  in the chassis  101 . The duct  102  extends between an air inlet  105  and the air outlet  106 . The air inlet  105  includes an inlet grill  115  and the air outlet  106  includes the outlet grill  116 . The air cleaner  100  further includes a series of air cleaning components and an impeller  107 . 
     In the embodiment shown, the air cleaning components include an ionizer  108  and a collector cell  112 . The air cleaner  100  additionally includes a first frame  144  and a second frame  145 . The first frame  144  and the second frame  145  can receive various filter elements, including an ozone filter element, an odor absorber element, or a mechanical filter element, for example. However, it should be understood that additional air cleaning components are contemplated and are within the scope of the description and claims. Airflow generated by the impeller  107  is drawn in through the air inlet  105 , through the ionizer  108 , through the collector cell  112 , and through any air cleaner components in the first frame  144  and the second frame  145 . 
     The impeller  107  in the embodiment shown comprises a cross-flow fan impeller that creates a substantially tangential airflow when rotated. Once the airflow enters the impeller  107 , it is accelerated and exits at a downstream point, where it enters the volume bounded by the expansion output region  124 . 
     The ionizer  108  comprises one or more corona charge elements  109  and corresponding corona ground elements  110 . The corona charge elements  109  and the corona ground elements  110  create a high voltage electrical field that electrically charges (ionizes) the airflow and any passing dirt and debris. The charging of the particles can neutralize or kill living organisms. The ionized particles of the airflow are subsequently attracted to ground potential surfaces. Subsequently, the electrically charged dirt and debris is more likely to be pulled out of the airflow when the airflow passes through the collector cell  112 , as described further below. 
     The collector cell  112  comprises interleaved charge and ground plates, wherein the airflow flows substantially in parallel through the plates. The charge plates are maintained at a high voltage. Dirt and debris in the airflow is electrostatically charged by the charge plates and the subsequently charged particles are attracted to and substantially retained on the ground plates. Dirt and debris in the airflow is therefore substantially removed. 
     Because the collector cell  112  is positioned in the airflow immediately after the ionizer  108 , the ionization performed by the ionizer  108  improves removal performance of the collector cell  112 . In addition, any charged particles not trapped or removed by the air cleaning components will be attracted to various surfaces around the home after exiting the air cleaner  100  and will subsequently be pulled out of the air. 
     The duct  102  is engineered to minimize turbulence and therefore maximize air cleaner efficiency. It should be noted that the duct  102  is smooth and is free of obstructions, sharp comers, etc. The air cleaner  100  provides substantially double the airflow as a comparable machine that employs a substantially linear, substantially rectangular ducting. As an additional benefit, the minimization of turbulence reduces noise and makes the air cleaner  100  less intrusive in an interior setting, such as in a home, office, etc. 
     The duct  102  includes a shaped input region  122 . The shaped input region  122  is located downstream of the air cleaning components and upstream of the impeller  107 . The airflow entering the shaped input region  122  is substantially linear. The airflow in one embodiment is substantially constrained in a linear manner by the parallel plate construction of the collector cell  112 . As a result, the airflow travels through the shaped input region  122  and meets the impeller  107  in a substantially radial manner (see arrows). The shaped input region  122  in some embodiments is somewhat tapered and as a result the airflow will increase in velocity before the airflow meets the impeller  107 . 
     The duct  102  further includes a curved transition region  123 . The curved transition region  123  is downstream of the shaped input region  122 . The impeller  107  resides in the curved transition region  123 . The impeller  107  accelerates the air entering from the shaped input region  122 . The curved transition region  123  transitions the airflow from an air inlet orientation to air outlet orientation. 
     In some embodiments, the air outlet  106  is non-linear with the air inlet  105 . In some embodiments, the air outlet  106  is substantially angled with respect to the air inlet  105 . In the embodiment shown, the air outlet  106  is substantially at a right angle to the air inlet  105  and therefore the airflow is transitioned substantially ninety degrees by the curved transition region  123 . 
     The duct  102  further includes an expansion output region  124 . The expansion output region  124  is downstream of the curved transition region  123  (although the two regions include some overlap). The curved transition region  123  can expand in cross-sectional area (and therefore in volume), while the expansion output region  124  can be at least partially curved. The expansion output region  124  in some embodiments comprises a partial spiral or scroll shape of expanding or increasing radius. The expansion output region  124  comprises a larger cross-sectional area adjacent to the impeller  107  that allows the airflow to expand and slow down. The expansion output region  124  directs the airflow so as to control the rate of expansion and minimize counter-flow and turbulence. As a consequence, noise generated by the air cleaner  100  is significantly reduced. For example, a reduced airspeed at the air outlet  106  reduces turbulence and noise at the outlet grill  116 . Airflow leaving the impeller  107  travels through the expansion output region  124  to the outlet grill  116  and out of the air outlet  106 . 
     The duct  102  further includes a cutoff region  130 . The cutoff region  130  separates the shaped input region  122  from the expansion output region  124 . The chassis  101  in the cutoff region  130  is formed adjacent to the impeller  107 , separated by a predetermined cutoff gap  131 . The cutoff gap  131  is relatively small. As a result, air pressure in the cutoff gap  131  is relatively high. The high pressure in the cutoff gap  131 , in combination with a rounded nose  132  (see below), serves to separate the airflow from the impeller  107  and to force the airflow to remain in the expansion output region  124 . However, the shape of the cutoff region  130  serves to minimize the high pressure and further spreads the change in pressure over a wider region using the rounded nose  132 . The minimization of this high pressure region reduces fan cutoff noise at the cutoff region  130 . 
     The cutoff region  130  in some embodiments includes a rounded nose  132  including a tip  133  that partially extends into the expansion output region  124 . The rounded nose  132  aids in separating the airflow from the impeller  107  but without creating significant turbulence. The rounded aspect of the nose  132  serves to divide or deflect the airflow, much as in a conventional aircraft airfoil, wherein the airflow is moved aside in advance of the nose  132 . 
     The inlet grill  115  and the outlet grill  116  both include grill members that allow the airflow to pass through but block any large objects from entering the duct  102 . The grill members can comprise elongate strips including rounded or shaped leading and trailing edges. In one embodiment, a grill member can comprise a substantially airfoil-shaped member. The airflow passes over the grill members with minimal disturbance or turbulence. 
     In some embodiments, the outlet grill  116  includes one or more angled grill members  116   a . The one or more angled grill members  116   a  can be disposed at a predetermined angle to the airflow at the air outlet  106 . The one or more angled grill members  116   a  can be angled in order to shape and control the exiting airflow. The one or more angled grill members  116   a  can minimize divergence in the exiting airflow. This advantageously prevents the exiting airflow from re-entering the air outlet  106 . The one or more predetermined grill members  116   a  can slow down the exiting airflow and cause it to swirl or rotate. A slower airspeed can reduce turbulence noise at the air outlet  106 .