Abstract:
A formula dispersing apparatus that increases the throw, volume and efficiency of formula distribution through aerodynamic surfaces is described. The shape of the ring airfoil in the utilization of the Coandà effect allows for efficient distribution of a formula or formula mixture into a defined space.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. 61/648,686 filed on May 18, 2012, which is incorporated herein by reference. 
     
    
     BACKGROUND OF INVENTION 
       [0002]    Traditionally, devices used to disperse a volatalizable formula such as a fragrance, insect control active or medicinal formula have either relied on the passive movement of ambient air to distribute the entrained formula throughout the living space where the device is placed or on the lower vapor pressure of the formula and formula carrier through heating of the formula containing material, typically through the use of an electrical wall socket and a resistive heater. 
         [0003]    In the case of a passive formula dispersing apparatus, the formula to be dispersed is mixed into a solid or gel matrix that slowly releases the formula to the air as the volatile materials in the solid or gel evaporate into the ambient air of the room. 
         [0004]    In the case of a heated formula dispersing apparatus, a gel or liquid with an incorporated formula is heated to distribute the formula by volatilizing the formula and the carrier material within which the formula is incorporated. 
         [0005]    Recently, auxiliary devices, such as a bladed fan, have been added to both the ambient and heated air formula dispersing apparatus to improve the distribution of the formula. The effectiveness, however, of the auxiliary devices, such as a fan, is low. 
         [0006]    It is therefore an object of the present invention to provide a formula dispersing apparatus that improves the distribution of the formula. 
       SUMMARY OF THE INVENTION 
       [0007]    The embodiments of the formula dispersing apparatus described herein use a generally circular airfoil or duct to promote the diffusion or broadcast of a formula from a formula dispersing apparatus. The generally circular airfoil has the suction side of the airfoil on the inside (closest to the wall) and the pressure side on the outside. This arrangement sets up a circular flow of an air stream through the ring airfoil. The formula dispersing apparatus may also contain a circulation fan that pushes air into the circular airfoil where the fan is disposed within the circular airfoil structure. 
         [0008]    The formula dispersing apparatus may also be comprised of an air channel within the airfoil where the air is entrained with the formula from a formula repository and then subsequently flowed out onto the edge of the airfoil. The airfoil will have a slot or slots in it such that the Coand{hacek over (a)} effect causes the formula entrained in the air stream to flow out and over the circular airfoil, enhancing the dispersion of the formula in the environment where the apparatus is placed. The circular airfoil preferably has a constant camber. 
         [0009]    The air freshener apparatus may also include an external source of formula that is entrained into the airflow subsequent to the airflow exiting the circular airfoil. 
         [0010]    In another embodiment, the vapor pressure of the formula mixture may be manipulated so as to increase the evaporation rate and increase the vapor pressure such that larger amounts of formula will be entrained into the air stream. 
         [0011]    In certain embodiments a heater is used to heat the material which contains the formula in order to assist, increase, or enable the volatilization of essential oils, formulas, or other materials intended to be delivered from a porous media in the formula source to the airstream. A fan or impeller may also be used to push the formula into the airstream travelling through the airfoil. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of an air freshener apparatus with a ring airfoil and a prop. 
           [0013]      FIG. 2  is a perspective view of an alternate embodiment of an air freshener apparatus. 
           [0014]      FIG. 3  is another perspective view of an alternate embodiment of an air freshener apparatus without a prop and with a circular airfoil and an inner distribution ring. 
           [0015]      FIG. 4  is a cross sectional diagram of the operation of a circular airfoil. 
           [0016]      FIG. 5  is a perspective view of the air freshener with a circular airfoil and a central nozzle. 
           [0017]      FIG. 6  is a perspective view of an alternate embodiment of the present invention plugged into a wall. 
           [0018]      FIG. 7  is a front view of the air freshener shown in  FIG. 6 . 
           [0019]      FIG. 8  is a rear view of the air freshener shown in  FIG. 6 . 
           [0020]      FIG. 9  is a cross sectional view of the air freshener of  FIG. 6  taken along line 9-9 of  FIG. 7 . 
           [0021]      FIG. 10  is an exploded view of the air freshener shown in  FIG. 6 . 
           [0022]      FIG. 11  is a depiction of the scalar airflow through a circular airfoil. 
           [0023]      FIG. 12  is a diagram showing the Coand{hacek over (a)} affect airflow across the interior or suction side of the circular airfoil. 
           [0024]      FIG. 13  is a diagram of a NACA 6412 airfoil. 
           [0025]      FIG. 14  is a diagram of a NACA airfoil measurement scheme. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    The embodiment of the formula dispersing apparatus shown in  FIG. 1  depicts an formula dispersing assembly  100  that has a ring airfoil  101  and a body  102 . In this assembly, the external prop  103  supplies the moving air to disperse the formula and is freewheeling. The distributed formula is also contained in the body  102  before passing through the fan. The formula is thus entrained into the air stream that is distributed through the ring airfoil  101 . 
         [0027]    In the embodiment of the formula dispersing apparatus shown in  FIG. 2 , the formula dispersing apparatus  200  has fixed structures  202  that attach directly to the ring airfoil  201 . Air and formula communicate from the base  205  though the distribution hub  203  to the ring airfoil  201 . The formula and air are then ejected through slots  204  in the ring airfoil  201  to the room environment. 
         [0028]      FIG. 3  shows an embodiment of the formula dispersing apparatus with formula dispersing assembly  300  with just a ring airfoil  301  and a base  303 . The formula dispersing body contains a means for moving air, such as a bladed fan, intake slots  302  on the base  303  and a means of supplying the air flow from the fan to the ring airfoil such that the Coand{hacek over (a)} effect is achieved. A device such as an inner ring  304  may be used to generate a jet of air and formula that may be distributed through the room through the ring airfoil  301 . The ring airfoil  301  may also have slots in it where the air and entrained formula flow into the room. The slots  302  in the base of the formula dispersing apparatus  300  allow for air to flow into the base  303  and out through the inner ring  304  or slots in the ring airfoil  301 . The ring airfoil  301  may also comprise a formula infused material such as a formula infused ethylene vinyl acetate (EVA) that allows the formula to escape over time and be entrained in the air flow through the ring airfoil  301 . 
         [0029]    The Coand{hacek over (a)} effect is utilized in aircraft. With the use of flaps and a “jet” sheet of air blowing over the curved surface, air moving over the wing can be “bent down” towards the ground. The flow is accelerated, due to Bernoulli&#39;s principle, and pressure is decreased. When pressure is decreased, aerodynamic lift is increased. 
         [0030]    By decreasing the pressure, more air may be pumped through the airfoil. With the entrainment of formula into the air stream, the distribution of the formula will be greater. 
         [0031]    All of the flow characteristics are related to Bernoulli&#39;s principle and derivations thereof 
         [0032]    Bernoulli&#39;s principle may be broadly defined by Equation 1. 
         [0000]    
       
         
           
             
               
                 
                   
                     
                       
                         v 
                         2 
                       
                       2 
                     
                     + 
                     gz 
                     + 
                     
                       p 
                       ρ 
                     
                   
                   = 
                   constant 
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   1 
                 
               
             
           
         
       
       
         
           
             v is the fluid flow speed at a point on a streamline 
             g is the acceleration due to gravity 
             z is the elevation of the point above a reference plane 
             p is the pressure at the chosen point 
             ρ is the density of the fluid at all points in the fluid 
           
         
       
     
         [0038]    The embodiment may also be comprised of a diffuser where the Venturi effect is utilized. 
         [0039]    The shape of the airfoil is of great importance for the distribution of the formula that is entrained into the airflow into the defined space where the air freshener is working One area of airfoil definitions are the NACA airfoils developed by the National Advisory Committee for Aeronautics (NACA) as possible shapes for wings for aircraft. The shape of the airfoil is described numerically using various parameters of the airfoil with digits following the NACA designation. For example, a NACA 6412 as 6% camber relative to the maximum cord, 4/10 of the cord for the location of the maximum camber and 12% as a maximum thickness as a percentage of the cord. The numerical code for each NACA airfoil can be entered into equations to precisely generate the cross-section of the airfoil and calculate its properties. 
         [0040]    The equations for calculations of the various aspects of an NACA airfoil are shown in equation 2. The various aspects of the airfoil may be manipulated to increase or decrease the effect of the airfoil on airflow. For instance, a more aggressive camber will allow for greater airflow but also suffers from the separation of the airflow from the airfoil, thus lowering the efficiency of the system. 
         [0041]    The attack angle or the angle at which the airfoil is turned also has an effect on the airflow. In this case, an airfoil that is perpendicular to the ground will have less of an effect on airflow than will an airfoil the higher degree of angle of attack. However, by changing the angle of attack, the airfoil can also possibly suffer from separation of the air stream and thus the stalling of the airflow over the airfoil. 
         [0042]    The use of the Coand{hacek over (a)} effect will allow not only improved distribution of the airflow entrained formula into a defined space but will also decrease the separation of the airflow from aggressively cambered and angle of attack airfoils. 
         [0000]    
       
         
               
             
               
               
             
           
               
                   
               
               
                 Equation 2 
               
               
                 NACA four digit series airfoils 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 The NACA 4-digit series is defined by four digits, e.g., 
               
               
                   
                 NACA 8412: m = 8%, p = 4/10, t = 12% 
               
               
                   
                 The equations are: 
               
               
                   
                 y t  = (t/0.2) (0.2969√x − 0.126x − 0.3516x 2  + 0.2843x 3  − 0.1015x 4 ) 
               
               
                   
                 y c  = (m/p 2 ) (2px − x 2 ); for x ≦ p 
               
               
                   
                 y c  = (m/(1 − p) 2 ) ((1 − 2p) + 2px − x 2 ); for x &gt; p 
               
               
                   
                 Where t is the maximum thickness as a percentage of the 
               
               
                   
                 chord, m is the maximum camber as a percentage of the 
               
               
                   
                 chord, p is the chordwise position of the maximum camber 
               
               
                   
                 as a tenth of the chord. 
               
               
                   
                 The final coordinates for the airfoil upper surface (x U , y U ) 
               
               
                   
                 and lower surface (x L , y L ) are given by: 
               
               
                   
                        x U  = x − y t (sinθ) 
               
               
                   
                        y U  = y c  + y t (cosθ) 
               
               
                   
                        x L  = x + y t (sinθ) 
               
               
                   
                        y L  = y c  − y t (cosθ) 
               
               
                   
                      where θ = arctan(Δy c /Δx) 
               
               
                   
                   
               
             
          
         
       
     
         [0043]    The NACA four digit series is one description of how to build an airfoil. There are various other ways and other NACA designations for airfoil shapes. 
         [0044]    Throughout all these constructions, however, it is important to ensure that the airfoil operates correctly within the realm of the air flow for which is intended. As mentioned above, if the design is too aggressive, the airfoil will see separation of the airflow from the airfoil surface and thus cause stalling of the airflow. 
         [0045]      FIG. 4  shows a cross section of a circular airfoil  400  and the air flow through the airfoil  400 . The cross section  401  shows an airfoil with a high camber. The suction side of the airfoil  400  is on the inside and causes a strong circulation of the air around the circular airfoil  400 . Formula is emitted as a jet  402  from a slot  406  in the circular airfoil  401 . 
         [0046]    The formula dispersing apparatus  500  shown in  FIG. 5  includes a nozzle  501 , a circular airfoil  502  and a body  503 . The air flows out through the nozzle  501  which acts like a jet to distribute the entrained formula through the ring airfoil  502 . The body  503  of the air freshener  500  contains the formula and mechanism for forcing air through the jet nozzle  501 . 
         [0047]    In all of these embodiments, it is important that the formula be dispersed evenly so that an aerosol cloud is not formed which could cause an overwhelming reaction to the formula. An understanding of the inherent tendency of an ingredient to escape into the gas phase is a useful starting point when considering formula volatility. The relative molecular mass (RMM) and the boiling point of a formula ingredient will provide some guidelines to the behavior of the material. For materials whose boiling points are not known, it is generally a sound alternative to look at chromatographic behavior. For example, the retention time for a material to elute through a gas chromatographic column containing a nonpolar phase is often strongly related to the boiling point (in fact, such columns are commonly referred to as “boiling point” columns). 
         [0048]    It is therefore important to match the Relative Molecular Mass (RMM), which can be considered as another characterization of the volatility of the formula, and the gas chromatographic characteristics of the formula mixture to the airflow through the ring airfoil. If the formula mixture vapor pressure at the operating temperature is too high and the airflow through the ring airfoil is also too high, an undesirable concentration of formula may result. 
         [0049]    The total amount of air that is set in motion in an airfoil device receives three contributions, so to speak: (a) from the air that goes through the formula dispersing apparatus, (b) from the air that gets drawn to the suction side of the ring of the formula dispersing apparatus, and (c) from the air that gets entrained into the free shear-layer that comes out of the formula dispersing apparatus ring. 
         [0050]    For example, an injected air/formula value of  2 . 5  cfm (contribution (a)) corresponds a total of 9.4 cfm of air passing through the ring (contributions (a) plus (b), above) and to a total of 267 cfm of air moving at the station 2 m downstream (i.e., contributions (a)+(b)+(c)). This example is for half of the airflow stream. Therefore the total of the airflow stream will be greater than 500 cfm at 2 m downstream from the device. If the vapor pressure of the formula is too high, say 200 kPa, the dispersion of the formula may be too high. 
         [0051]    Is therefore desirable to have the mass flow at 2 m downstream of the device to be less than 750 cfm and the vapor pressure of the formula mixture to be less than 200 kPa. The 750 ft. 3  per minute (CFM) is achieved through adjustment of (a) the speed of the fan, (b) the shape of the ring airfoil and (c) the attack angle of the ring airfoil. The vapor pressure of the formula mixture is a factor of the temperature of the formula mixture and its inherent evaporative properties. For instance, acetone has a vapor pressure of 240 hPa at 20° C. By heating the acetone, the vapor pressure would increase above 240 hPa 
         [0052]    Referring to  FIGS. 6-10 , another embodiment of the formula dispersing apparatus  600  of the present invention is shown. Formula dispersing apparatus  600  includes a body  602  to which an airfoil  604  is attached. The taper of the ring airfoil  604  from thickest portion or leading edge  605  to the trailing edge  607  is constant and in the embodiment shown the angle of attack of the ring airfoil is  15  degrees. The portion of the airfoil  604  from the trailing edge  607  to the end of the airfoil on the pressure side  612  is a foil duct that is used to corral the air flow and move it across the porous media to entrain the formula in the air stream. 
         [0053]    A removable formula reservoir  606  is connected to body  602  to supply formula which is discharged from the body  602  through opening  608  where it is entrained in the air supply travelling through the airfoil  604 . Formula dispersing apparatus  600  is intended to be plugged into a wall socket  631  so that the airfoil  604  is spaced slightly from a wall  632  when the formula dispersing apparatus  600  is plugged into the wall socket  631 . Air is drawn in from the suction side  610  of the airfoil  604  closest to the wall  630  and exits from the pressure end of the airfoil  604  on the side  612  furthest away from the wall  630 . 
         [0054]    A front view of the formula dispersing apparatus  600  is shown in  FIG. 7  in which the airflow  611  (which includes unmarked arrows around the perimeter as well) carries the formula emitting through opening  608  out of the airfoil  604 . 
         [0055]    Referring now to  FIG. 8 , the rear side of the formula dispersing apparatus shown in  FIGS. 6 and 7  is shown. AC power plug  614  is used to plug the formula dispersing apparatus  600  into an AC socket  631  to provide AC power to the formula dispersing apparatus  600 . The power is used to run impeller  616  which is a fan housed behind grill  618 . The impeller  616  blows air up into the ring airfoil  604  and then the air flowing out through the slot  626  in the ring airfoil  604 , parallel to the ground and thus generating the Coand{hacek over (a)} effect. The rotation of the impeller  616  is axial to the ground. 
         [0056]      FIG. 9  shows a cross section and  FIG. 10  shows an exploded view of the components of the airfoil  604  and the other internal components of the formula dispersing apparatus  600 . The removable formula supply  606  which in this embodiment is a bottle includes a porous media (such as a cotton reed)  620  which extends into the bottle  606  and draws the liquid formula and carrier material by capillary action up to opening  608  where it becomes entrained in the air flow through air foil  604 . 
         [0057]    The plug  614  is supported in housing  622 . The wires  634  from plug  614  are connected to a power supply  635  to adjust the voltage from line voltage (such as 120V AC or 22V AC) to one that will drive the fan (such as 5V DC or 12V DC). In addition, certain embodiments may include a means to alter or adjust the impeller  612  speed including but not limited to a rheostat, pulsed width modulation of the power, or discrete switched resistor values. Such control action can be done manually or via a preprogrammed or customizable programmed controller or microprocessor. As shown in  FIG. 9  the impeller  616  draws air through grate  618  and forces it in an upward direction into a tunnel  624  before it is forced out through a slot  626  formed between the leading edge  605  of the ring airfoil  628  and the inner surface  630  of the ring airfoil  604 . While in the embodiment shown in  FIGS. 6-10  the carrier including the fragrance is emitted through opening  608 , in other embodiments, the formula supply can be positioned (a) at a location relative to impeller  616  so that impeller  616  forces the carrier and formula into tunnel  624 , (b) on the suction side  610  so that the carrier and formula is drawn into formula dispersing apparatus  600  through the suction side  610  or (c) between grate  618  and impeller  616  so that the impeller draws the formula into the apparatus  600  and discharges the formula into the tunnel  624 . 
         [0058]    In some embodiments the formula reservoir  606 , in which the carrier and formula are incorporated, is heated. Whether heat is applied will depend on the volatility or vapor pressure of the carrier at ambient temperature. In the embodiment shown in  FIGS. 6-10 , a heater  640  is positioned near the upper portion of the porous media  620  where evaporation takes place. Heater  640  is a resistive heater with a resistor positioned on wire  642 . In this embodiment it is preferred that the carrier and formula are heated to 120° F.-180° F. and more preferably 150° F. Other formulas would be heated to other temperature ranges. As is well known in the art a circuit board with a programmed integrated circuit would allow for a resistive heater to be both variable and/or intermittent based on either outside input or algorithms that are written to the programmed integrated circuit. 
         [0059]    The configuration that is depicted in  FIG. 11  depicts the computational fluid dynamics (CFD) analysis of a ring airfoil  1100  and the air flow downrange from the ring airfoil. The ring airfoil  1101  generates a multiplied airflow  1102 . The angle of attack of the ring airfoil  1101  is modified to 15°  1103 . 
         [0060]    The air flow through the ring airfoil, utilizing the Coand{hacek over (a)} effect, is shown in  FIG. 12 . The airfoil configuration  1200  consists of the ring airfoil, shown in cross section  1205  with a slot  1201  running on the interior portion of the ring airfoil toward the intake  1206  of the ring airfoil. The air stream  1203  from the slot  1201  is flowing from the interior of the ring airfoil and is entrained with a formula. The air stream  1203  also allows for higher air flow  1204  due to the Coand{hacek over (a)} effect air stream  1203  keeping the air flow  1204  attached to the ring airfoil  1205  and thus enables higher efficiency flow through the ring airfoil  1201 . This efficiency is accomplished by turning the flow  1202  through the intake  1206  of the ring airfoil  1205  and keeping the Coand{hacek over (a)} effect air stream  1203  attached to the ring airfoil  1205 . 
         [0061]    In  FIG. 13 , a  6412  airfoil  1300  is shown with a mean line  1301  and a trailing edge  1302 . 
         [0062]      FIG. 14  shows a generic airfoil  1400  with a cord line  1401  and a mean line  1402 . The cord line  1401  is a connection between the leading edge  1403  of the airfoil and the tip of the trailing edge  1404 . The mean line  1402  bisects the airfoil from the leading edge  1403  to the trailing edge  1404 . 
         [0063]    While the invention has been described with respect to its preferred embodiments, various alterations and modifications will be apparent to those skilled in the art and all such alterations and modifications are intended to fall within the scope of the appended claims.