Particulate filter and method for control

Abstract

An exhaust treatment system comprises a filter device in communication with the engine and configured to receive exhaust gas therefrom. The filter device comprises a canister including an inlet, a filter structure having an upstream, inlet end, a downstream, outlet end, and a series of filtering flow passages. A center zone conduit is in sealing, fluid contact with the downstream, outlet end of the filter structure to thereby define a center flow zone and perimeter flow zone. A flow control valve assembly is disposed in the center zone conduit. A controller is in signal communication with the flow control valve and a temperature sensor and monitors a temperature profile of the filter structure wherein, upon a determination that the temperature of the center flow zone of the filter structure is above a predetermined level, the controller drives the flow control valve assembly to a closed position.

What is claimed is: 
     
         1 . An exhaust treatment system for an internal combustion engine comprising:
 a particulate filter device in fluid communication with the internal combustion engine and configured to receive exhaust gas therefrom, comprising:   a canister that includes an inlet for receipt of the exhaust gas;   a filter structure having an upstream, inlet end, a downstream, outlet end, and a series of filtering flow passages extending therebetween;   a center zone conduit in sealing, fluid contact with the downstream, outlet end of the filter structure to thereby define the filter structure into a center flow zone and perimeter flow zone;   a flow control valve assembly disposed in the center zone conduit and operable between an open and a closed position;   a temperature sensor; and   a controller in signal communication with the flow control valve and the temperature sensor and configured to monitor a temperature profile of the filter structure wherein, upon a determination that the temperature of the center flow zone of the filter structure has risen above a predetermined level, the controller will drive the flow control valve assembly to a closed position to thereby stop the flow of exhaust gas through the center flow zone of the filter and reduce the temperature thereof.   
     
     
         2 . The exhaust treatment system of  claim 1 , the particulate filter device further comprises a ceramic wall-flow filter supported by an insulating mat and disposed in a rigid canister. 
     
     
         3 . The exhaust treatment system of  claim 1 , further comprising one or more of an oxidation catalyst device and a selective catalyst reduction device. 
     
     
         4 . The exhaust treatment system of  claim 1 , wherein, upon a determination that the temperature of the center flow zone of the filter structure has dropped below a predetermined level, the controller will drive the flow control valve assembly to an open position to thereby allow the flow of exhaust gas through the center flow zone of the filter. 
     
     
         5 . A method for controlling the temperature of a particulate filter in an exhaust treatment system for an internal combustion engine comprising the steps of:
 placing a particulate filter device in fluid communication with the internal combustion engine and configuring it to receive exhaust gas therefrom, the device comprising:   a canister that includes an inlet for receipt of the exhaust gas and a filter structure having an upstream, inlet end, a downstream, outlet end, and a series of filtering flow passages extending therebetween;   locating a center zone conduit in sealing, fluid contact with the downstream, outlet end of the filter structure to thereby define the filter structure into a center flow zone and perimeter flow zone;   positioning a flow control valve assembly in the center zone conduit that is operable between an open and a closed position;   locating a temperature sensor at the downstream, outlet end of the filter structure; and   operating a controller to monitor a temperature profile of the filter structure wherein, upon determining that the temperature of the center flow zone of the filter structure has risen above a predetermined level, the controller will drive the flow control valve assembly to a closed position to thereby stop the flow of exhaust gas through the center flow zone of the filter and reduce the temperature thereof.   
     
     
         6 . The method of  claim 5 , further comprising the steps of, operating the controller to monitor the temperature profile of the filter structure wherein upon a determination that the temperature of the center flow zone of the filter structure has dropped below a predetermined level, the controller will drive the flow control valve assembly to an open position to thereby allow the flow of exhaust gas through the center flow zone of the filter. 
     
     
         7 . An exhaust treatment system for an internal combustion engine comprising:
 a particulate filter device in fluid communication with the internal combustion engine and configured to receive exhaust gas therefrom, comprising:   a canister that includes an inlet for receipt of the exhaust gas;   a filter structure having an upstream, inlet end, a downstream, outlet end, and a series of filtering flow passages extending therebetween;   a center zone conduit in sealing, fluid contact with an end of the filter structure to thereby define the filter structure into a center flow zone and perimeter flow zone;   a flow control valve assembly disposed in the center zone conduit and operable between an open and a closed position;   a temperature sensor; and   a controller in signal communication with the flow control valve and the temperature sensor and configured to monitor a temperature profile of the filter structure wherein, upon a determination that the temperature of the center flow zone of the filter structure has risen above a predetermined level, the controller will drive the flow control valve assembly to a closed position to thereby stop the flow of exhaust gas through the center flow zone of the filter and reduce the temperature thereof.   
     
     
         8 . The exhaust treatment system of  claim 7 , wherein, upon a determination that the temperature of the center flow zone of the filter structure has dropped below a predetermined level, the controller will drive the flow control valve assembly to an open position to thereby allow the flow of exhaust gas through the center flow zone of the filter.