Abstract:
The present invention is generally directed toward a method of measuring surfactant penetration into a foam layer of a filter for an air filter assembly. The method comprises the addition of a dye to a surfactant, adding the dye laden surfactant to the foam layer, illuminating the foam layer after the dye laden surfactant has been added, observing the amount of illumination, and determining the amount of surfactant penetration by the amount of illumination of the foam layer.

Description:
BACKGROUND  
       [0001]     1. Technical Field  
         [0002]     This invention generally relates to an air filter assembly and more specifically to the measuring surfactant penetration in a foam filter of the air filter assembly.  
         [0003]     2. Known Technology  
         [0004]     It is known to provide air induction filters for the engine of a motor vehicle so as to filter out contaminants in air entering the engine. In the past, the air induction filter was typically made of pleated paper or fibrous media housed in a plastic or metal frame mounted in the engine compartment of the motor vehicle. Once the customer or service technician evaluates the filter as dirty, this filter was discarded and replaced with a new one.  
         [0005]     Another variety of filter is made of reticulated foam and located in a plastic housing in the engine compartment. The foam material is one or more layers thick and is attached to the housing. The sealed box in combination with sufficient foam can make this a long life filter. The filter must still be replaced after many miles, but it is greatly increased from traditional filters. However, reticulated foam has at least one drawback. For example, experiments have found that untreated foam does not absorb dust very efficiently, which decreases the cleaning efficiency of the air filter. In order to increase the efficiency of the air filter, it is known to treat the filters with a contaminant attracting substance, such as an oil or surfactant.  
         [0006]     Experiments have also found that the efficiency of the air filter, depends directly on the amount of oil and the depth that it has penetrated the thickness of the foam filter. Unfortunately, once the oil is added to the foam filter it is not visible, and there is no known method of measuring the distribution or the depth that it has penetrated into the foam filter.  
         [0007]     Therefore, there is a need in the industry to be able to determine oil penetration into the foam of a filter so as to enable the maximum dust absorbing capability of the air filter.  
       SUMMARY  
       [0008]     In overcoming the drawbacks and limitations of the known technology, a method is provided to reliably determine the oil penetration into a filter of an air filter assembly. By determining the depth of oil penetration into the filter media, the manufacturing process can be modified, if necessary, to ensure that full and complete penetration of the oil occurs. This further ensures that the air filter achieves its maximum contaminant trapping ability and its longest useful life.  
         [0009]     According to the present invention, the method of measuring oil penetration into a filter of an air intake assembly comprises: providing an oil or surfactant; adding an illuminable material to the oil or surfactant; providing a filter having at least one foam layer; applying the oil or surfactant containing the illuminable material to the foam layer; illuminating the illuminable in the oil or surfactant after being applied to the foam layer; examining the foam layer while being illuminated; and determining the depth of oil penetration based on the amount of the foam layer illuminated.  
         [0010]     In yet another aspect, the foam layer is perforated. Perforating may occur before the oil or surfactant is added to the foam layer. After the oil or surfactant is added to the foam layer, the foam layer may be torn along the perforations. In this matter, the penetration of the oil or surfactant into the foam layer is not disturbed and an accurate determination of the depth of penetration may be made.  
         [0011]     In still another aspect, the foam layer is observed under black light to measure the depth of penetration of the oil foam layer into the surfactant.  
         [0012]     Further features and advantages of the invention will become apparent to those skilled in the art from a review of the following discussion and claims, in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]      FIG. 1  is a perspective view of an air filter assembly as installed in or near the engine bay of a motor vehicle;  
         [0014]      FIG. 2  is an exploded view of the air filter assembly seen in  FIG. 1 ;  
         [0015]      FIG. 3  is a sectional view of the foam layers of the filter assembly seen in  FIG. 2 ;  
         [0016]      FIG. 4  is flow chart of the steps of a method in accordance with the teachings of the present invention;  
         [0017]      FIG. 5  is a perspective view of a foam layer as used in connection with the present invention; and  
         [0018]      FIGS. 6A and 6B  are sectional views of a foam layer illustrating partial surfactant penetration and full surfactant penetration, respectively.  
     
    
     DETAILED DESCRIPTION  
       [0019]     Referring now to the drawings and in particular  FIG. 1 , an air filter assembly  10  produced according to the principles of the present invention is illustrated as being installed in a motor vehicle  12 . As shown, the motor vehicle  12  includes a vehicle body  14  defining an engine bay  15 . An air inlet tube  16  is operatively connected to the air filter assembly  10  to direct air into the assembly  10 . The air filter assembly  10  receives ambient air through the air inlet tube  16 , filters the air and thereafter delivers the cleaned air to the engine of the motor vehicle  12 . Although in this application the air filter assembly  10  is discussed as being specifically installed in the air induction system of the motor vehicle, it will be understood that the air filter assembly  10  may be used in connection with other automotive components, such as a heating/ventilation/air conditioning system (HVAC) or may be used in non-automotive application where filtered air is desired.  
         [0020]     As seen in  FIG. 2 , the air filter assembly  10  includes a housing  20  in which a filter  22  is disposed to filter contaminants from the air supplied to the engine. The housing  20  includes a tray or body  24  on which is provided suitable means, such as a bracket  23 , to mount the assembly  10  within the engine bay  15  of the motor vehicle  12 . The housing  20  also includes a cover  26  that may be removeably attached to the tray  24 . The tray  24  and cover  26  cooperate to define an interior cavity  25  into which the filter  22  is received. The filter  22  may have any suitable shape, but preferably is shaped complementary to the interior shape of the cavity  25 . Further the filter  22  is preferably sized to substantially or fully occupy the cavity  25  of the housing, such shapes including complex geometrical shapes.  
         [0021]     In one embodiment, the filter  22  is multi-layered having a plurality of individual layers  28 ,  30 ,  32 ,  34  and  36 . Although in the drawings a five layer filter  22  is shown and described, it will be understood that the filter  22  can be comprised of more than or fewer than five layers. The number of layers in that the filter  22  is dictated by the particular application, manufacturing, packaging and other conditions. The thickness and the porosity of these layers  28 - 32  can be identical or different depending on the requirements dictated by the application in which the air filter assembly  10  is used. An example of a multi-layered air filter is described in U.S. Pat. No. 6,464,761, which is herein incorporated by reference.  
         [0022]     The layers  28 ,  30 ,  32 ,  34  and  36  of the filter  22  are made of reticulated foam and are perforated along lines  37 . As will be explained later, the perforations  37  are formed in the filter  22  to help expose the internal surfaces of the layers  28 - 32  without disturbing the oil distributions.  
         [0023]     As mentioned above, in order to increase the contaminant absorbing capability of the filter  22 , the multi-layers  28 - 32  of the filter  22  are treated with an oil or surfactant (hereinafter just “surfactant”). All of the layers  28 - 36  of the filter  22  may be treated with the surfactant or only some of the layers  28 - 36  may be treated as such.  
         [0024]     Referring to the cross-section view of the filter assembly  10  seen in  FIG. 3 , one layer  28  of the filter  22  is shown as having been fully treated with a surfactant. The surfactant in layer  28  is illustrated by darker lines being used to define the layer  28 . It is believed that the specific surfactant is not relevant to the present invention and that any surfactant could be used. Since the efficiency of the filter  22  depends on the depth of surfactant penetration into the layer  28 , it is important to measure the surfactant penetration. With the present invention this is achieved in part by pre-treating the surfactant before it is added to the layer  28 .  
         [0025]     As detailed in the flowchart of  FIG. 4  and seen in  FIGS. 5 and 6 , a method of measuring surfactant penetration into a foam layer  60  or layers of a filter is generally shown and represented by reference number  38 . The method first comprises the step S 40  of providing a layer of foam  60  and forming within the layer(s) perforations  37 . As discussed below, the perforations  37  enable the layer(s)  60  to be severed without impacting the measurements to be taken. In step S 42  a pre-determined amount of dye is added to a surfactant. Approximately, 0.1 grams of dye is used per liter of surfactant. The dye used is preferably a florescent dye capable of being illuminated under black light, however, other illumination means could be used. The florescent dye may be a dry, solvent based dye or an other suitable dye/illuminable material. The method next comprises the step S 44  of initially weighing the foam layer  60  before the dye laden surfactant is added to the foam layer  60 .  
         [0026]     The dye laden surfactant is then added to the foam layer  60  in step S 46 . The dye laden surfactant is added to the with the help of an oiler machine and evenly distributed in the foam layer  60  with the help of a nip machine in step S 47 . The quantity of dye laden surfactant added to a given foam layer  60  generally depends on the thickness and porosity of the given layer  60 . For example, if the porosity of the layer is 80 ppi (pores per inch) then the amount of dye laden oil added would be approximately 7.5 grams per 13 grams of foam. With a porosity of 30 ppi, then the amount of dye laden surfactant added to the layer(s)  60  is approximately 12 grams per 35 grams of foam.  
         [0027]     In step S 48 , the weight of the foam layer  60  after the dye laden surfactant has been added is taken. Once the foam layer  60  has been weighed, the foam layer  60  is severed in step S 50  along perforations  37  made in step S 40 . Perforating the foam layer  60  ensures that the surfactant distribution in the foam layer  60  is not disturbed or otherwise impacted upon severing for testing. Once the foam layer  60  has been torn along the perforations, the severed foam layer  62  is illuminated with black light or other means and is examined. Illuminated in this manner, the depth of penetration of the dye laden surfactant into the foam layer  62  is measured, visually or otherwise. Partial penetration occurs as seen in  FIG. 6A , when the full depth or thickness of the severed foam layer  62  is not illuminated. As seen in this figure, the penetration of the surfactant is identified at  64  and the portion of the foam layer  62  not penetrated by the surfactant is identified at  66 . Surfactant penetration depth, when less than complete, is measured as the combined depth of penetration from the two exterior sides (the top and bottom sides  68 ) of the foam layer  62 . Full penetration occurs when the complete thickness of the foam layer  70  appears illuminated. As seen in  FIG. 6B , full surfactant penetration is identified by the cross hatching at  72  and the penetration is seen as being through the full depth or thickness  74  of the foam layer  70 .  
         [0028]     As a person skilled in the art will recognize from the above description, taken in conjunction with the figures and claims, modifications, variations and changes can be made without departing from the proper scope and fair meaning of the invention, as defined in the claims that follow.