Abstract:
Provided is an exhaust gas filter, including: an external case connected with an exhaust pipe; a filtering unit provided in the external case; a filtering path supplying exhaust gas to the filtering unit; and a pressure relief flange provided in the external case to discharge exhaust gas by bypassing the filtering unit. 
     According to an exemplary embodiment of the present invention, an exhaust gas filter can prevent the exhaust gas filter from being broken by circuitously discharging exhaust gas even when particular matters collected in the exhaust gas filter increase and thus, pressure in the exhaust gas filter excessively increases 
     Further, engine components such as an EGR, a turbocharger, and the like can be prevented from being broken or outputs thereof can be prevented from deteriorating.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent 
         [0002]    Application No. 10-2009-0119832 filed in the Korean Intellectual Property Office on Dec. 4, 2009, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0003]    (a) Field of the Invention 
         [0004]    The present invention relates to an exhaust gas filter, and more particularly, to an exhaust gas filter capable of preventing the exhaust gas filter from being broken by circuitously discharging exhaust gas when particular matters collected in the exhaust gas filter increase and thus, pressure in the exhaust gas filter excessively increases. 
         [0005]    (b) Description of the Related Art 
         [0006]    Exhaust gas discharged by combustion of an internal combustion engine includes a variety of harmful substances such as nitrogen oxide (NOx), carbon dioxide, ass, and the like. Apparatuses and methods for removing the harmful substances have been contrived. 
         [0007]    In particular, in a diesel engine vehicle, a particular matter is removed by using an exhaust gas filter or a postprocessing apparatus such as a diesel particular filter (DPF), a diesel oxidation catalyst (DOC), and the like. 
         [0008]      FIG. 13  is a schematic diagram illustrating a general exhaust gas filter. As illustrated in  FIG. 13 , the exhaust gas is filtered through a filter medium  20  surrounding the outer periphery of a porous tube  10 . The filtered exhaust gas is discharged to the outside through an exhaust gas passage  30 . 
         [0009]    However, when the exhaust gas filter is used for a long time, pressure in the filter is raised due to excessive collection of the particular matters, thereby causing the filter to be broken or the performance of an engine to deteriorate. 
         [0010]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention has been made in an effort to provide an exhaust gas filter capable of preventing the exhaust gas filter from being broken by circuitously discharging exhaust gas when particular matters collected in the exhaust gas filter increase and thus, pressure in the exhaust gas filter excessively increases. 
         [0012]    An exemplary embodiment of the present invention provides an exhaust gas filter, including: an external case connected with an exhaust pipe; a filtering unit provided in the external case; a filtering path supplying exhaust gas to the filtering unit; and a pressure relief flange provided in the external case to discharge exhaust gas by bypassing the filtering unit. 
         [0013]    The filtering unit may include: a porous tube provide in the longitudinal direction of the external case; a filter medium provided in the outer peripheral direction of the porous tube; a first flange provided at one end of the longitudinal direction of the porous tube; and a second flange provided at the other end of the longitudinal direction of the porous tube. 
         [0014]    The plurality of filter media having a cylindrical shape may be provided in the longitudinal direction of the porous tube. 
         [0015]    The filter medium may be provided as a plurality of layers around the porous tube. 
         [0016]    The exhaust gas filter may further include a jacket provided to cover the filter medium. 
         [0017]    The filter medium may contain at least one of materials selected from a group including a diesel particular filter (DPF) for removing diesel particular matters, a diesel oxidation catalyst (DOC), a selective catalytic reduction (SCR), a lean NOx trap (LNT), and a three way catalyst. 
         [0018]    An exhaust gas relief path may be formed inside the pressure relief flange to discharge exhaust gas in the filtering path by bypassing the filtering unit. 
         [0019]    The pressure relief flange may include a first plate and a second plate that are attached to each other and the exhaust gas relief path may be formed on at least one of the first plate and the second plate. The exhaust gas relief path may include a first line opened to the inner periphery and the outer periphery of the pressure relief flange; and a second line branched from the first line and opened to the outer periphery of the pressure relief flange. 
         [0020]    The pressure relief flange may include a first plate and a second plate that are attached to each other, and the exhaust gas relief path is formed on at least one of the first plate and the second plate. 
         [0021]    The exhaust gas relief path may be formed linearly in a radiation direction inside the pressure relief flange. The exhaust gas relief path may be formed curvedly in the radiation direction inside the pressure relief flange. 
         [0022]    The pressure relief flange may include a front pressure relief flange provided between the first flange and the filter medium. 
         [0023]    The pressure relief flange may further include a rear pressure relief flange provided between the second flange and the filter medium. 
         [0024]    The pressure relief flange may include a middle pressure relief flange provided between the filter media. 
         [0025]    According to an exemplary embodiment of the present invention, an exhaust gas filter can prevent the exhaust gas filter from being broken by circuitously discharging exhaust gas even when particular matters collected in the exhaust gas filter increase and thus, pressure in the exhaust gas filter excessively increases. Further, engine components (an EGR, a turbocharger, and the like) can be prevented from being broken or outputs thereof can be prevented from deteriorating. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a cross-sectional view of an exhaust gas filter according to a first exemplary embodiment of the present invention. 
           [0027]      FIG. 2  is a perspective view of a filter medium of the exhaust gas filter according to the first exemplary embodiment of the present invention. 
           [0028]      FIGS. 3 to 5  are perspective views of a filtering unit of the exhaust gas filter according to the first exemplary embodiment of the present invention. 
           [0029]      FIGS. 6 to 7  are diagrams of a modified example of the exhaust gas filter according to the first exemplary embodiment of the present invention. 
           [0030]      FIG. 8  is a cross-sectional view of an exhaust gas filter according to a second exemplary embodiment of the present invention. 
           [0031]      FIG. 9  is a cross-sectional view of an exhaust gas filter according to a third exemplary embodiment of the present invention. 
           [0032]      FIG. 10  is a cross-sectional view of an exhaust gas filter according to a fourth exemplary embodiment of the present invention. 
           [0033]      FIG. 11  is a cross-sectional view of an exhaust gas filter according to a fifth exemplary embodiment of the present invention. 
           [0034]      FIG. 12  is a cross-sectional view of an exhaust gas filter according to a sixth exemplary embodiment of the present invention. 
           [0035]      FIG. 13  is a schematic diagram illustrating a general exhaust gas filter. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0036]    An exemplary embodiment of the present invention will hereinafter be described in detail with reference to the accompanying drawings. 
         [0037]      FIG. 1  is a cross-sectional view of an exhaust gas filter according to a first exemplary embodiment of the present invention and  FIG. 2  is a perspective view of a filter medium of the exhaust gas filter according to the first exemplary embodiment of the present invention.  FIGS. 3 to 5  are perspective views of a filtering unit of the exhaust gas filter according to the first exemplary embodiment of the present invention. 
         [0038]    A configuration of the exhaust gas filter according to the first exemplary embodiment of the present invention will be described with reference to  FIGS. 1 to 5 . 
         [0039]    The exhaust gas filter according to the first exemplary embodiment of the present invention includes an external case  120  connected with an exhaust pipe, a filtering unit provided in the external case  120 , and a front pressure relief flange  130  provided in the external case  120  to discharge exhaust gas by bypassing the filtering unit. 
         [0040]    The filtering unit includes a porous tube  135  provided in the longitudinal direction of the external case  120 , a filter medium  140  provided in the outer peripheral direction of the porous tube  135 , a first flange  150  provided at one end of the longitudinal direction of the porous tube  135 , a second flange  155  provided at the other end of the longitudinal direction of the porous tube  135 , and a jacket  160  covering the filter medium  140 . 
         [0041]    The jacket  160  may be provided to connect the first flange  150  and the second flange  155 . 
         [0042]    An exhaust gas passage  156  is formed in the second flange  155 . 
         [0043]    The porous tube  135  and the jacket  160  support the filter medium  140  and have a plurality of holes to allow exhaust gas to flow into the filter medium  140  and are made of a material which is resistant to thermal shock. 
         [0044]    A filtering path in the first exemplary embodiment of the present invention is defined by the inside of the porous tube  145  and a space crossing the filter medium  140  in the porous tube  135 . 
         [0045]    A sealing mat (not illustrated) is provided between the first and second flanges  150  and  155  and the filter medium  140  to prevent exhaust gas from leaking. 
         [0046]    The filter medium  140  may be formed by a plurality of cylindrical filters  142  that are provided in the longitudinal direction of the porous tube  135  as illustrated in  FIG. 2(   a ). 
         [0047]    Referring to  FIG. 2(   b ), the filter medium  140  may be formed by filters  144  and  146  formed as a plurality of layers around the porous tube  135 . 
         [0048]    The filter medium  140  may be made of SiC, Cordierite, AT, SiN, and the like which are ceramic materials or made of foil type, foam type, wire mesh type, metal fiber, and the like which are metallic materials. 
         [0049]    The filter medium  140  may contain at least one of materials selected from a group including a diesel particular filter (DPF), a diesel oxidation catalyst (DOC), a selective catalytic reduction (SCR), a lean NOx trap (LNT), and a three way catalyst. 
         [0050]    That is, different types of filters as the filter medium  140  are stacked in sequence to simultaneously filter a variety of harmful substances such as nitrogen oxide (NOx), carbon dioxide, ass, and the like contained in exhaust gas and further, to save a space, improve filtering efficiency, and reduce a production cost as compared with a case in which the DPF, the DOC, and the three way catalyst are separately installed. 
         [0051]    The front pressure relief flange  130  is provided between the first flange  150  and the filter medium  140 . 
         [0052]    Further, the front pressure relief flange  130  is in contact with one side of the porous tube  135  and an exhaust gas relief path  132  is formed inside the front pressure relief flange  130 . The exhaust gas relief path  132  is in communication with the exhaust gas passage  145  of the second flange  155 . 
         [0053]    The exhaust gas relief path  132  includes a first line  134  and a second line  136 . 
         [0054]    The first line  134  is opened to the inner periphery and the outer periphery of the front pressure relief flange  130 . 
         [0055]    The second line  136  is branched at one side of the first bypass  134  and opened to the outer periphery of the front pressure relief flange  130 . 
         [0056]    When no particular matter (PM) is deposited on the filter medium  140 , the exhaust gas is filtered through the filter body  140  and when the particular matters (PM) are deposited on the filter body  140  and thus the filter medium  140  is clogged, the exhaust gas is discharged through the front pressure relief flange  130  to release the pressure of the filtering path. 
         [0057]    Meanwhile, the front pressure relief flange  130  includes a first plate  138  and a second plate  139  that are attached to each other. The exhaust gas relief path  132  is formed on at least one of the first plate  138  and the second plate  139 . For example, both surfaces of the first plate  138  are flat and the exhaust gas relief path  132  may be formed on one surface of the second plate  139 . In this case, the first plate  138  and the second plate  139  are attached to each other to form the front pressure relief flange  130 . 
         [0058]    Referring back to  FIG. 1 , an operating principle of the exhaust gas filter according to the first exemplary embodiment of the present invention will be described. 
         [0059]    In a normal operating state, exhaust gas is discharged through an exhaust pipe (not illustrated), the porous tube  130 , the filter medium  140 , and the exhaust gas passage  156  and only a small amount of exhaust gas passes through the exhaust gas relief path  132 . 
         [0060]    However, when the particular matters (PM) are excessively accumulated in the filter medium  140 , the pressure of the exhaust gas filter is significantly increased. In this case, some of exhaust gas cannot flow into the filter medium  140 . The exhaust gas that cannot flow into the filter medium  140  flows out to the outside through the exhaust gas relief path  132  and the exhaust gas passage  156 . 
         [0061]    As such, when the particular matters (PM) are excessively accumulated and the pressure of the exhaust gas filter is excessively increased, the exhaust gas filter according to the first exemplary embodiment of the present invention bypasses the exhaust gas to prevent the exhaust gas filter from being broken. 
         [0062]      FIGS. 6 to 7  are diagrams of a modified example of the exhaust gas filter according to the first exemplary embodiment of the present invention. 
         [0063]    Referring to  FIGS. 6 and 7 , the modified example of the exhaust gas filter according to the first exemplary embodiment of the present invention will be described. 
         [0064]    In the modified example of the exhaust gas filter according to the first exemplary embodiment of the present invention, an exhaust gas relief path  232  may be formed inside a pressure relief flange  231  linearly in a radiation direction. 
         [0065]    Further, in another modified example of the exhaust gas filter according to the first exemplary embodiment of the present invention, an exhaust gas relief path  332  may be formed inside a pressure relief flange  331  curvedly in the radiation direction. 
         [0066]    Shapes of the exhaust gas relief paths  232  and  332  formed on the pressure relief flanges  231  and  331  are not limited to shapes illustrated in the figures and may include various modified examples to release excessive exhaust gas pressure in the filtering path. 
         [0067]      FIG. 8  is a cross-sectional view of an exhaust gas filter according to a second exemplary embodiment of the present invention. 
         [0068]    Hereinafter, a configuration of the exhaust gas filter according to the second exemplary embodiment of the present invention will be described with reference to  FIG. 8 . 
         [0069]    The configuration of the exhaust gas filter according to the second exemplary embodiment of the present invention is similar as the configuration of the exhaust gas filter according to the first exemplary embodiment of the present invention and a duplicated description of the same configuration will be omitted. The exhaust gas filter according to the second exemplary embodiment of the present invention includes an external case  620 , a rear pressure relief flange  630 , a porous tube  635 , a filter medium  640 , a first flange  650 , a second flange  655 , a jacket  660 , and an exhaust gas passage  656 . 
         [0070]    The rear pressure relief flange  630  is provided between the second flange  650  and the porous tube  635 . 
         [0071]    When the particular matters (PM) are excessively accumulated in the filter medium  640 , the pressure of the exhaust gas filter is significantly increased. In this case, some of exhaust gas cannot flow into the filter medium  640 . The exhaust gas that cannot flow into the filter medium  640  flows into the rear pressure relief flange  630 . The exhaust gas that flows into the rear pressure relief flange  630  flows out to the outside of the rear pressure relief flange  130  through the exhaust gas relief path. The outflow exhaust gas flows out to the outside of the exhaust gas filter through the exhaust gas passage  656 .  FIG. 9  is a cross-sectional view of an exhaust gas filter according to a third exemplary embodiment of the present invention. 
         [0072]    Hereinafter, a configuration of the exhaust gas filter according to the third exemplary embodiment of the present invention will be described with reference to  FIG. 9 . 
         [0073]    The configuration of the exhaust gas filter according to the third exemplary embodiment of the present invention is similar as the configuration of the exhaust gas filter according to the first exemplary embodiment of the present invention and a duplicated description of the same configuration will be omitted. 
         [0074]    The exhaust gas filter according to the third exemplary embodiment of the present invention includes an external case  720 , a front pressure relief flange  730 , a rear pressure relief flange  731 , a porous tube  735 , a filter medium  740 , a first flange  750 , a second flange  755 , a jacket  760 , and an exhaust gas passage  756 . 
         [0075]    The front pressure relief flange  730  is provided between the first flange  750  and the porous tube  735 . The exhaust gas relief path is formed inside the front pressure relief flange  730 . The exhaust gas relief path is in communication with the exhaust gas passage  756 . The rear pressure relief flange  731  is provided between the second flange  750  and the porous tube  735 . 
         [0076]    When the particular matters (PM) are excessively accumulated in the filter medium  640  and thus the pressure of the exhaust gas filter is significantly increased, some of exhaust gas flows out to the outside through the front pressure relief flange  730  and the rear pressure relief flange  731 . 
         [0077]      FIG. 10  is a cross-sectional view of an exhaust gas filter according to a fourth exemplary embodiment of the present invention. 
         [0078]    Hereinafter, a configuration of the exhaust gas filter according to the fourth exemplary embodiment of the present invention will be described with reference to  FIG. 10 . 
         [0079]    The configuration of the exhaust gas filter according to the fourth exemplary embodiment of the present invention is similar as the configuration of the exhaust gas filter according to the third exemplary embodiment of the present invention and a duplicated description of the same configuration will be omitted. 
         [0080]    The exhaust gas filter according to the fourth exemplary embodiment of the present invention includes an external case  820 , a front pressure relief flange  830 , a rear pressure relief flange  831 , a middle pressure relief flange  832 , a porous tube  835 , a filter medium  840 , a first flange  850 , a second flange  855 , a jacket  860 , and an exhaust gas passage  856 . 
         [0081]    The middle pressure relief flange  832  is formed at one side of the longitudinal direction of the filter medium  840 . That is, the middle pressure relief flange  832  is provided between the filter media  840 . The exhaust gas may bypass even through the middle pressure relief flange  832  in addition to the front and rear pressure relief flanges  830  and  832 . 
         [0082]      FIG. 11  is a cross-sectional view of an exhaust gas filter according to a fifth exemplary embodiment of the present invention and  FIG. 12  is a cross-sectional view of an exhaust gas filter according to a sixth exemplary embodiment of the present invention. 
         [0083]    The exhaust gas filter according to the fifth exemplary embodiment of the present invention includes a front pressure relief flange  930  and a middle pressure relief flange  932 . The exhaust gas filter according to the sixth exemplary embodiment of the present invention includes a rear pressure relief flange  1031  and a middle pressure relief flange  1032 . Since the configuration and function of the pressure relief flange are the same as those described in the above exemplary embodiment, a more detailed description thereof will be omitted. 
         [0084]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
       DESCRIPTION OF SYMBOLS 
       [0000]    
       
           120 ,  620 ,  720 ,  820 : External case 
           130 ,  730 ,  830 ,  930 : Front pressure relief flange 
           132 ,  232 ,  332 : Exhaust gas relief path 
           155 ,  630 ,  731 ,  831 ,  1031 : Rear pressure relief flange 
           832 ,  932 ,  1032 : Middle pressure relief flange 
           135 ,  635 ,  735 ,  835 : Porous tube 
           140 ,  640 ,  740 ,  840 : Filter medium 
           150 ,  650 ,  750 ,  850 : First flange 
           155 ,  655 ,  755 ,  855 : Second flange 
           156 ,  656 ,  756 ,  856 : Exhaust gas passage 
           160 ,  660 ,  760 ,  860 : Jacket