Sensor for exhaust gas purifying apparatus

Abstract

A sensor for an exhaust gas purifying apparatus includes an examining filter and a holding member. The examining filter is provided in a secondary exhaust line diverging from a primary exhaust line of an internal combustion engine. The holding member holds the examining filter on the secondary exhaust line. The holding member holds an approximately 10% to approximately 50% part by area of a peripheral portion of the examining filter so as to cover the part from a peripheral side of the examining filter.

1 . A sensor for an exhaust gas purifying apparatus, comprising:
 an examining filter provided in a secondary exhaust line diverging from a primary exhaust line of an internal combustion engine; and   a holding member that holds the examining filter on the secondary exhaust line, the holding member holding an approximately 10% to approximately 50% part by area of a peripheral portion of the examining filter so as to cover the part from a peripheral side of the examining filter.   
     
     
         2 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the peripheral portion of the examining filter is so constructed as to be used as a filter wall. 
     
     
         3 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter is held in the secondary exhaust line with a peripheral surface of the examining filter being covered with the holding member. 
     
     
         4 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter comprises a sealing part facing an inflow side of the secondary exhaust line, and is held by the holding member on an outflow side of the secondary exhaust line. 
     
     
         5 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter comprises a sealing part facing an outflow side of the secondary exhaust line, and is held by the holding member on an inflow side of the secondary exhaust line. 
     
     
         6 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 5 , further comprising:
 a coating configured to prevent a deposition of particulate matter in the secondary exhaust line, the coating being applied on a part of the examining filter, the part being held by the holding member.   
     
     
         7 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 6 , wherein the coating is one of alumina and glass. 
     
     
         8 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter is provided to determine a presence of a leak of particulate matter from a diesel particulate filter capable of trapping the particulate matter or to measure an amount of the particulate matter trapped by the diesel particulate filter. 
     
     
         9 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein:
 the secondary exhaust line is provided separately from the primary exhaust line communicating with an atmosphere, the secondary exhaust line being connected to the primary exhaust line on a downstream side of a diesel particulate filter provided on the primary exhaust line, and   the secondary exhaust line has a flow passage cross-sectional area smaller than a flow passage cross-sectional area of the primary exhaust line.   
     
     
         10 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 9 , wherein a part of exhaust gas passing through the diesel particulate filter in the primary exhaust line is drawn by suction with a pump to a side of the secondary exhaust line to pass through the examining filter. 
     
     
         11 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 9 , wherein the examining filter has a soot storage capacity smaller than a soot storage capacity of the diesel particulate filter. 
     
     
         12 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , further comprising:
 at least one of a differential pressure gauge, a flowmeter, and a temperature measuring part.   
     
     
         13 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 12 , wherein the differential pressure gauge is configured to have an output of the differential pressure gauge fed to a processing part comprising a microcomputer, and wherein the processing part is configured to detect a pressure difference caused between an upstream side and a downstream side of the examining filter in the second exhaust line based on the output of the differential pressure gauge and to measure a concentration of particulate matter in exhaust gas based on a change over time in the pressure difference. 
     
     
         14 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 12 ,
 wherein the sensor comprises the differential pressure gauge, the flowmeter, and the temperature measuring part,   wherein the differential pressure gauge is configured to have an output of the differential pressure gauge fed to a processing part comprising a microcomputer, and   wherein the processing part is configured to detect a pressure difference caused between an upstream side and a downstream side of the examining filter in the second exhaust line based on the output of the differential pressure gauge, to calculate an amount of particulate matter deposited in the examining filter or a concentration of the particulate matter in exhaust gas flowing through the secondary exhaust line based on the pressure difference, a flow rate measured by the flowmeter, and a temperature measured by the temperature measuring part, and to determine a presence or an absence of a leak of the particulate matter from a diesel particulate filter provided on the primary exhaust line based on the calculated amount or concentration of the particulate matter.   
     
     
         15 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 14 , wherein the processing part is configured to cause an alarm to be given or cause a lamp to flash or turn on in response to determining the presence of the leak of the particulate matter from the diesel particulate filter. 
     
     
         16 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter is formed of porous ceramic. 
     
     
         17 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter has a tubular shape. 
     
     
         18 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 17 , wherein the examining filter has a cylindrical shape. 
     
     
         19 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter has a shape having a single quadrangular cell. 
     
     
         20 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the examining filter has a shape having 3×3 cells. 
     
     
         21 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the secondary exhaust line comprises a canister forming at least a part of a pipe introducing exhaust gas flowing in from the primary exhaust line to a side of the examining filter. 
     
     
         22 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein the canister has a cylindrical shape. 
     
     
         23 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein the canister is fixed to the primary exhaust line with the holding member. 
     
     
         24 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein the canister is welded to the holding member. 
     
     
         25 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein the examining filter is fixed to the holding member and canister with one of a mat and ceramic paste. 
     
     
         26 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein an end portion of the examining filter on an exhaust gas inflow side projects toward the exhaust gas inflow side from the holding member inside the canister. 
     
     
         27 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein:
 the examining filter is sealed with a sealing part on the exhaust gas inflow side, and   a part of the peripheral portion of the examining filter is exposed as a filter portion inside the canister.   
     
     
         28 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein the examining filter has an end portion of the examining filter projecting toward an exhaust gas inflow side and is sealed with a sealing part on the exhaust gas inflow side inside the canister in the secondary exhaust line connecting to a downstream side of a diesel particulate filter provided on the primary exhaust line. 
     
     
         29 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 21 , wherein the canister is formed of stainless steel. 
     
     
         30 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein the holding member has a cylindrical shape. 
     
     
         31 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , further comprising:
 a heater provided inside the examining filter.   
     
     
         32 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein:
 the holding member has a through hole provided in the holding member to be open in an axial direction so as to hold the examining filter, and   the examining filter is held by the holding member through the through hole.   
     
     
         33 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein:
 the examining filter has a sealing part facing an exhaust gas inflow side and is held by the holding member on an exhaust gas outflow side, and   in the peripheral portion of the examining filter, an exhaust-gas-inflow-side region on a front-end side of a region covered with the holding member is so constructed as to be used as a filter portion to trap particulate matter in exhaust gas.   
     
     
         34 . The sensor for an exhaust gas purifying apparatus as claimed in  claim 1 , wherein:
 the examining filter has a sealing part facing an exhaust gas outflow side and is held by the holding member on an exhaust gas inflow side, and   in the peripheral portion of the examining filter, an exhaust-gas-outflow-side region on a rear-end side of a region covered with the holding member is so constructed as to be used as a filter portion to trap particulate matter in exhaust gas.