Abstract:
An air filter assembly for delivering clean air to primary and secondary components such as a vehicle engine and a catalytic converter of the vehicle, for example. Air flow sensors are calibrated to sense the amount of air flow going to the engine to ensure optimum engine performance. The air filter assembly segregates the air flow between the engine and catalytic converter in a manner that allows intermittent air flow to the secondary component without substantially affecting the continuous air flow to the primary component.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to air filters and, more particularly, to an air filter having a segregation feature to provide air to a primary component such as a vehicle engine, and a secondary air component such as a catalytic converter of a vehicle, for example.  
       BACKGROUND OF THE INVENTION  
       [0002]     Gasoline engines need the proper mixture of clean air and fuel for optimum operation and efficiency. The clean air is transported to the engine by an air induction system consisting of a dirty air cavity exposed to outside air, an air filter cleaning element, and a clean air cavity that is attached to the air intake of the engine, typically with flexible air ducting. Outside air, which is considered “dirty air”, is pulled by the vacuum of the engine into the dirty air cavity and drawn through the air filter element. The air filter removes particulates from the dirty air before it passes through to the clean air cavity and on to the engine. The clean air flow to the engine is monitored and metered to ensure the proper air/fuel mixture for optimum engine performance and efficiency. These air monitoring/metering devices are calibrated based on the optimum air flow volume at known engine vacuum levels and are very sensitive to any deviations from the calibrated air flow rate.  
         [0003]     Some vehicle components other than the engine also need clean air to operate efficiently (e.g., the catalytic converter) and the clean air cavity of the air filter assembly is a convenient source to access for this purpose. A normally-off secondary air pump cycles on when the secondary component requires the secondary air which results in a change to the air flow rate in the air induction system. If the air flow sensor reads an air flow rate that is not within the accepted the calibrated air flow rate, an error signal is triggered and engine performance and efficiency may thereby be compromised.  
         [0004]     It would therefore be desirable to have an air filter design and method that segregates the clean air flow to the engine and a secondary air component such that when air flow is drawn by the secondary component, it does not negatively impact the calibrated air flow rate to the engine.  
       SUMMARY OF THE INVENTION  
       [0005]     The present invention addresses the above stated need by providing an air filter assembly having an air flow segregation feature that provides air to a primary component (e.g., an engine), and a secondary component (e.g., a catalytic converter). A typical air filter assembly includes an air filter housing and a filter element disposed therein which separates the housing into a dirty air cavity and clean air cavity on either side of the filter. A dirty air inlet port allows air to be drawn from the outside into the dirty air cavity side of the housing. When the engine is running, the engine creates a vacuum which draws the dirty air through the filter to the clean air cavity side of the filter housing. An air outlet port on the clean air cavity side of the housing delivers the clean air to the engine through appropriate ducting.  
         [0006]     According to an aspect of the invention, a secondary air cavity is formed within the air filter assembly housing. The secondary air cavity is defined in part by secondary filter walls positioned in the filter which effectively separates the air filter into a primary air filter portion and a secondary air filter portion. The primary air filter portion of the filter cleans the air that is directed to a first clean air outlet leading to the primary component (e.g., the engine). The secondary air filter portion of the filter cleans the air that is directed to a second clean air outlet leading to the secondary component (e.g., the catalytic converter). The clean air cavity side of the housing also includes cavity walls which align with the filter walls to define a secondary clean air cavity that is segregated from the primary clean air cavity. The air flow is thus segregated beginning at the filter and continuing uninterrupted through the clean air cavity of the housing. As such, air flow that is drawn by the secondary component will not negatively impact the calibrated air flow rate to the primary component. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0008]      FIG. 1  is an assembled, perspective view with a part broken away according to one embodiment of the inventive air filter assembly;  
         [0009]      FIG. 2  is an exploded, perspective view of the air filter assembly of  FIG. 1 ;  
         [0010]      FIG. 3  is an enlarged, fragmented view showing particular details of the secondary air cavity of the air filter assembly of  FIG. 1 ;  
         [0011]      FIG. 4  is a fragmented, cross-sectional view as taken through the line  4 - 4  in  FIG. 1 ; and  
         [0012]      FIG. 5  is a fragmented, perspective view of the top cover of the air filter assembly of  FIG. 1 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     Referring now to the drawings, there is seen in  FIGS. 1-5  an air filter assembly designated generally by the reference numeral  10 . It is understood that the overall shape and design of assembly  10  is for description purposes only and the present invention is not to be limited thereby. In the embodiment shown and described herein, air assembly  10  is part of an automobile engine air induction system (not shown) although the present invention may be applied to air filter assemblies in other air filter applications.  
         [0014]     Air assembly  10  includes a housing having upper and lower halves  12 ,  14 , respectively. A filter  16  is positioned within the housing between the upper and lower halves  12 ,  14  and thereby defines a lower “dirty air” cavity  18  and upper “clean air” cavity  20 . An air inlet port  22  is formed on lower housing half  14  wherethrough dirty air from the outside may pass into the filter assembly  10 . Primary and secondary air outlets  24 , 26  are provided on upper housing half  12  with primary outlet  24  leading to the primary component requiring clean air, for example the vehicle engine (not shown). Secondary air outlet  26  leads to a secondary component requiring clean air, for example a catalytic converter (not shown). When the engine is running, the engine pulls a vacuum at primary outlet  24  and dirty air is drawn from the outside through inlet port  22  into the dirty air cavity  18  of the housing. Since the vacuum is located at primary outlet port  24  which is on the clean air side of the housing, the dirty air in cavity  18  is drawn upward through filter element  16  which captures particulate and thus passes clean air into the clean air cavity  20  of the housing.  
         [0015]     The present invention segregates the air flow between the primary air outlet  24  and secondary air outlet  26 . Clean air cavity  20  is thus segregated into two cavities; a primary clean air cavity  40  in fluid communication with the primary outlet port  24 , and a secondary clean air cavity  42  in fluid communication with the secondary outlet port  26 . This segregation also extends through the filter element  16  and thereby operates to provide clean air to both the primary and secondary air outlets as needed without any substantial affect on the calibrated air flow through the primary outlet port  24 .  
         [0016]     More particularly, the filter element  16  is segregated into a primary clean air portion  16   a  and a secondary clean air portion  16   b  by a filter wall  46  that extends entirely through the filter element  16  from the dirty air filter side  16   c  to the clean air filter side  16   d  thereof. In the illustrated embodiment, filter wall  46  has three walls with filter frame  16   e  forming a fourth wall to form a generally rectangular enclosure which effectively segregates secondary filter portion  16   b  from the primary filter portion  16   a . It is understood, however, that the filter wall can be of any desired shape so long as the filter wall acts to segregate filter  16  into primary and secondary filter portions  16   a ,  16   b , respectively. As seen best in  FIG. 4 , filter element  16  is pleated and filter wall  46  is bifurcated such that one of the filter pleats extends between the bifurcated segments  46   a  and  46   b . The filter frame  16   e  including wall  46  and filter  16  may be attached to each other in any known manner such as by over-molding the two components, for example. In this regard, filter  16  may be made of any appropriate filter media such as a multi-layered synthetic, for example, which is over-molded onto the filter frame  16   e  including filter wall  46  which may be injected molded plastic, for example. The upper portion  46   c  of wall  46  is also bifurcated to form a channel  46   d  which extends above air filter  16  (e.g., by about 10 mm) into clean air cavity  20  for aligning and mating with the secondary air cavity wall in the upper housing half  12  as described below. It is noted that the particular configuration of filter  16  and filter wall  46  may vary according to the particular filter assembly design employed. For example, the filter element may be other than pleated (e.g., honey-comb) and the filter wall  46  may be a single planar wall.  
         [0017]     The clean air cavity  20  within the housing upper half  12  is also segregated into a primary clean air cavity  40  and a secondary clean air cavity  42  by a secondary clean air cavity wall  44 . Secondary clean air cavity wall  44 , together with housing upper wall  12   a  (see  FIG. 4 ), forms an enclosed secondary clean air cavity  42  that is thus segregated from the primary clean air cavity  40 . The secondary air cavity wall  44  has a free edge  44   a  that is aligned with filter wall  46  such that when housing upper half  12  is attached to housing lower half  14 , free edge  44   a  of secondary air cavity wall  44  may be press fit into channel  46   d  of filter wall  46 . Thus, when the housing is fully assembled, secondary clean air cavity wall  44  is coextensive with filter wall  46  to provide a secondary air cavity  42  that extends substantially uninterrupted through filter  16 . Furthermore, the filter frame outer edge  16   f  is captured between the outer edge  12   b  of upper housing half  12  and the outer edge  14   b  of lower housing half  14  (see  FIG. 4 ). Screws (not shown) may be secured through aligned holes  12   c ,  14   c  in lower and upper housing halves  12 ,  14 , respectively, to firmly secure the assembled air filter housing  10 .  
         [0018]     When the engine is running, a vacuum is drawn at primary outlet port  24  which draws outside dirty air through air inlet port  22  into dirty air cavity  18 . Since the vacuum is originating at outlet port  24 , the primary clean air cavity  40  of the clean air cavity  20  which is in fluid communication with primary outlet port  24  draws the dirty air from dirty air cavity  18 , through primary filter portion  16   a  and into the primary clean air cavity portion  40  where the now clean air may exit the housing at primary outlet port  24  and travel to the engine. This clean air is monitored by calibrated sensors (not shown) located downstream of primary outlet port  24 . As is well known to those skilled in the art, the air flow sensors are calibrated to predetermined air flow rates that correspond to the prevailing engine condition to achieve optimum engine performance.  
         [0019]     Upon a secondary component requiring clean air, a secondary vacuum source such as an air pump (not shown) draws a vacuum at secondary outlet port  26  causing dirty air to be drawn from dirty air cavity  18  through secondary filter portion  16   b  and into secondary clean air cavity  42 . The now clean air in air cavity  42  may exit the housing at secondary outlet port  26  and travel to the secondary component requiring clean air (e.g., the catalytic converter). It is noted that the secondary component requiring the clean air may require clean air only intermittently with respect to the primary component. The secondary vacuum source may therefore cycle on and off while the engine is continuously running. Since the secondary air cavity  42  is effectively segregated from the primary clean air cavity  40 , the air flow and sensors monitoring the clean air downstream of primary outlet  24  are not substantially affected (i.e., they do not sense a substantial change in air flow volume in an amount that would trigger an out-of-calibration error signal) and clean air may flow to both the engine and the secondary component without interruption.  
         [0020]     In the presently illustrated embodiment of the invention, the primary clean air cavity  40  and primary air outlet port  24  are much larger than the secondary clean air cavity  44  and secondary air outlet port  26 . This is because a secondary component (e.g., the catalytic converter) requires much less of a clean air flow rate than the engine. The proportion between the primary and secondary cavities and outlet ports will therefore vary depending on the specific application of the air assembly  10  and may be readily determined by those skilled in the art without undue experimentation.  
         [0021]     While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.