Control System for Internal Combustion Engine, and Control Method for Internal Combustion Engine

Abstract

In an exhaust passage, a pressure detection means is provided on the upstream side of a filter, and an exhaust throttle valve is provided on the downstream side of the filter. And, when the operational state of the internal combustion engine is a steady operational state (in a step S 101 ), the opening amount of an exhaust throttle valve is controlled so that the upstream pressure detected by the pressure detection means becomes a constant value (in a step S 103 ).

1 - 9 . (canceled) 
   
   
       10 . A control system for an internal combustion engine, comprising:
 an exhaust passage of the internal combustion engine;   a filter which is provided in the exhaust passage, and which collects particulate matter within the exhaust;   a pressure detection device which detects an upstream side pressure, which is the pressure in the exhaust passage on the upstream side of the filter;   an exhaust throttle valve provided in the exhaust passage on the downstream side of the filter;   an a control device which, when an operational sate of the internal combustion engine is a steady operational state, controls an opening amount of the exhaust throttle valve so that the upstream side pressure detected by the pressure detection device becomes a constant value.   
   
   
       11 . A control system for an internal combustion engine according to  claim 10 , wherein the pressure detection device includes a pressure sensor which outputs an electrical signal corresponding to the upstream side pressure. 
   
   
       12 . A control system for an internal combustion engine according to  claim 10 , wherein the pressure detection device estimates the upstream side pressure based upon the operational state of the internal combustion engine. 
   
   
       13 . A control system for an internal combustion engine according to  claim 10 , wherein the steady operational state is an idling operational state after warming up of the internal combustion engine. 
   
   
       14 . A control system for an internal combustion engine according to  claim 10 , wherein the steady operational state is the idling operational state after a temperature of the filter has decreased to normal temperature. 
   
   
       15 . A control system for an internal combustion engine according to  claim 10 , further comprising a first collected PM amount estimation portion which is estimated an amount of collected particulate matter in the filter, based upon the opening amount of the exhaust throttle valve when the operational state of the internal combustion engine is the steady operational state. 
   
   
       16 . A control system for an internal combustion engine according to  claim 15 , further comprising:
 a pressure difference detection device which comprises a pipe whose end portions are connected to the exhaust passage at the upstream side and the downstream side of the filter, and a pressure difference detection unit which is provided in the pipe and detects the pressure difference in the exhaust passage between the upstream side and the downstream side of the filter;   a second collected PM amount estimation portion which is estimated the amount of collected particulate matter in the filter, based upon the pressure difference detected by the pressure difference detection device; and   if a value obtained by subtracting the amount of collected particulate matter as estimated by the first collected PM amount estimation portion from the amount of collected particulate matter as estimated by the second collected PM amount estimation portion is greater than or equal to a predetermined value, a determination portion which is decided that clogging of the pipe of the pressure difference detection device has occurred.   
   
   
       17 . A control method for an internal combustion engine in which a filter which collects particulate matter within the exhaust is connected to an exhaust passage, comprising the steps of:
 detecting an upstream side pressure, which is the pressure in the exhaust passage on the upstream side of the filter; and   when the operational state of the internal combustion engine is a steady operational state, controlling an opening amount of an exhaust throttle valve which is provided in the exhaust passage on the downstream side of the filter, so that the upstream side pressure becomes a constant value.