Exhaust Gas Treatment Device and Method for Operating an Exhaust Gas Treatment Device

Abstract

An exhaust gas treatment device for an internal combustion engine, with a first particle filter and a second particle filter arranged downstream of the first particle filter in the flow direction of the exhaust gas through the exhaust gas treatment device. The second particle filter includes a support device that can be flown through by the exhaust gas, on which a filter unit is disposed. A pore size of the filter unit is less than a pore size of the support device. A method for operating an exhaust gas treatment device for an internal combustion engine is also provided.

1 - 18 . (canceled) 
     
     
         19 . An exhaust gas treatment device for an internal combustion engine, comprising:
 a first particle filter; and   a second particle filter arranged downstream of and spaced from the first particle filter in a flow direction of exhaust gas through the exhaust gas treatment device, wherein the second particle filter comprises
 a support device configured such that the exhaust gas passes through the support device; and 
 a filter unit arranged on the support device, wherein a pore size of the filter unit is smaller than a pore size of the support device. 
   
     
     
         20 . The exhaust gas treatment device according to  claim 19 , wherein the filter unit is arranged to retain particles by surface filtration. 
     
     
         21 . The exhaust gas treatment device according to  claim 19 , wherein a thickness or a porosity of the one support device is respectively a multiple of a thickness or a porosity of the filter unit. 
     
     
         22 . The exhaust gas treatment device according to  claim 19 , wherein the support device is arranged downstream or upstream of the filter unit. 
     
     
         23 . The exhaust gas treatment device according to  claim 19 , wherein the second particle filter is arranged regeneratably by a heat transfer in an exhaust gas tract within a housing surrounding the first particle filter, wherein the heat transfer is effected by a thermal regeneration of the first particle filter. 
     
     
         24 . The exhaust gas treatment device according to  claim 19 , further comprising:
 pressure sensing means; and   an evaluation device configured to determine a pressure drop across the first particle filter and a pressure drop across the second particle filter.   
     
     
         25 . The exhaust gas treatment device according to  claim 20 , further comprising:
 pressure sensing means; and   an evaluation device configured to determine a pressure drop across the first particle filter and a pressure drop across the second particle filter.   
     
     
         26 . The exhaust gas treatment device according to  claim 23 , further comprising:
 pressure sensing means; and   an evaluation device configured to determine a pressure drop across the first particle filter and a pressure drop across the second particle filter.   
     
     
         27 . The exhaust gas treatment device according to  claim 19 , further comprising:
 an evaluation device configured to evaluate a difference of the pressure between a location upstream of the second particle filter and a location downstream of the second particle filter with regard to a state of the first particle filter.   
     
     
         28 . The exhaust gas treatment device according to  claim 27 , further comprising:
 a memory storing a reference value, variably depending on an aging of the first particle filter, of the pressure difference.   
     
     
         29 . The exhaust gas treatment device according to  claim 19 , further comprising:
 pressure sensing means;   an evaluation device; and   a memory storing a ratio of a difference in pressure between a location upstream of the second particle filter and a location downstream of the second particle filter to a difference of pressure between a location upstream of the first particle filter and a location downstream of the first particle filter, and   wherein the evaluation device is configured to evaluate a ratio determined by the pressure sensing means with regard to a state of the first particle filter.   
     
     
         30 . The exhaust gas treatment device according to  claim 24 , further comprising:
 pressure sensing means;   an evaluation device; and   a memory storing a ratio of a difference in pressure between a location upstream of the second particle filter and a location downstream of the second particle filter to a difference of pressure between a location upstream of the first particle filter and a location downstream of the first particle filter, and   
       wherein the evaluation device is configured to evaluate a ratio determined by the pressure sensing means with regard to a state of the first particle filter. 
     
     
         31 . The exhaust gas treatment device according to  claim 27 , further comprising:
 pressure sensing means;   an evaluation device; and   a memory storing a ratio of a difference in pressure between a location upstream of the second particle filter and a location downstream of the second particle filter to a difference of pressure between a location upstream of the first particle filter and a location downstream of the first particle filter, and   wherein the evaluation device is configured to evaluate a ratio determined by the pressure sensing means with regard to a state of the first particle filter.   
     
     
         32 . The exhaust gas treatment device according to  claim 29 , wherein the evaluation unit is configured to evaluate the ratio determined by the pressure sensing means depending on a thermal regeneration of at least the first particle filter. 
     
     
         33 . The exhaust gas treatment device according to  claim 30 , wherein the evaluation unit is configured to evaluate the ratio determined by the pressure sensing means depending on a thermal regeneration of at least the first particle filter. 
     
     
         34 . The exhaust gas treatment device according to  claim 31 , wherein the evaluation unit is configured to evaluate the ratio determined by the pressure sensing means depending on a thermal regeneration of at least the first particle filter. 
     
     
         35 . The exhaust gas treatment device according to  claim 19 , further comprising:
 an exhaust gas return line comprising a throttle device, which branches off downstream of the second particle filter.   
     
     
         36 . A method for operating an exhaust gas treatment device with a first particle filter and a second particle filter arranged downstream of and spaced from the first particle filter in a flow direction of exhaust gas passing through the exhaust gas treatment device, and comprising a support device configured such that the exhaust gas passes through by the support device and on which a filter unit is arranged, the filter unit having a pore size smaller than a pore size of the support device, the method comprising:
 determining a state of the first particle filter with regard to its functionality based on a state of the second particle filter.   
     
     
         37 . The method according to  claim 36 , further comprising:
 determining a pressure drop across the second particle filter; and   evaluating, based on the pressure drop across the second particle filter, whether the first particle filter is damaged.   
     
     
         38 . The method according to  claim 36 , wherein during a thermal regeneration with combustion of soot from the first particle filter, the second particle filter is also regenerated.