Diagnostic apparatus for catalyst in fuel-property reforming system

Abstract

A diagnostic apparatus for a catalyst in a fuel-property reforming system includes an inlet-side temperature sensor disposed upstream of the fuel-reforming catalyst and an outlet-side temperature sensor disposed downstream of the fuel-reforming catalyst. In a reforming driving mode, while the EGR valve is opened to recirculate a part of exhaust gas into the intake pipe, a reforming-fuel injector injects a reforming fuel into the EGR gas. A fuel-reforming catalyst reforms the fuel into a fuel having high-combustibility. A differential temperature between a temperature detected by the inlet-side temperature sensor and a temperature detected by the outlet-side temperature sensor is compared with a deterioration-determination threshold, whereby a computer determines whether the fuel-reforming catalyst is deteriorated.

1 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, comprising:
 a reforming-fuel injector injecting a reforming-fuel into a medium fluid which will be supplied to an intake pipe of the internal combustion engine;   a fuel-reforming catalyst for reforming the fuel in the medium fluid;   a reaction-heat detection portion which detects a reaction-heat information of the fuel-reforming catalyst; and   a catalyst-deterioration diagnosing portion which diagnoses whether the fuel-reforming catalyst is deteriorated based on the reaction-heat information.   
     
     
         2 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, according to  claim 1 , wherein:
 the reaction-heat detection portion includes an inlet-side temperature sensor disposed upstream of the fuel-reforming catalyst and an outlet-side temperature sensor disposed downstream of the fuel-reforming catalyst;   the catalyst-inlet temperature and the catalyst-inlet temperature are detected while a fuel-reforming control in which the fuel is reformed in the fuel-reforming catalyst is executed; and   the catalyst-deterioration diagnosing portion diagnoses whether the fuel-reforming catalyst is deteriorated based on a catalyst-inlet temperature detected by the inlet-side temperature sensor and a catalyst-outlet temperature detected by the outlet-side temperature sensor.   
     
     
         3 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, according to  claim 1 , wherein:
 the reaction-heat detection portion includes a temperature detecting portion which detects a temperature of the fuel-reforming catalyst or a temperature at an outlet of the fuel-reforming catalyst;   the catalyst-deterioration diagnosing portion diagnoses whether the fuel-reforming catalyst is deteriorated based on the temperatures of fuel-reforming catalyst or a temperatures at an outlet of the fuel-reforming catalyst which are detected before and after the fuel-reforming control in which the fuel is reformed in the fuel-reforming catalyst is started.   
     
     
         4 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, comprising:
 a reforming-fuel injector injecting a reforming-fuel into a medium fluid which will be supplied to an intake pipe of the internal combustion engine; a fuel-reforming catalyst for reforming the fuel in the medium fluid;   a combustion-condition detecting portion which detects a combustion-condition information of the internal combustion engine;   a catalyst-deterioration diagnosing portion which diagnoses whether the fuel-reforming catalyst is deteriorated based on the combustion-condition information.   
     
     
         5 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, according to  claim 4 , wherein:
 the catalyst-deterioration diagnosing portion diagnoses whether the fuel-reforming catalyst is deteriorated based on the combustion-condition informations which are detected before and after a fuel-reforming control in which the fuel is reformed in the fuel-reforming catalyst is started.   
     
     
         6 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, according to  claim 4 , wherein:
 the combustion-condition detecting portion detects, as the a combustion-condition information, at least one of a combustion stability index, an ignition delay period, a main combustion period, a combustion center, a maximum combustion pressure, an EGR limit, and a combustion speed.   
     
     
         7 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, comprising:
 a reforming-fuel injector injecting a reforming-fuel into a medium fluid which will be supplied to an intake pipe of the internal combustion engine; a fuel-reforming catalyst for reforming the fuel in the medium fluid;   a reforming-degree detecting portion which detects an reforming degree of the fuel at an outlet of the fuel-reforming catalyst; and   a catalyst-deterioration diagnosing portion which diagnoses whether the fuel-reforming catalyst is deteriorated based on the reforming degree of the fuel.   
     
     
         8 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, according to  claim 7 , wherein:
 the catalyst-deterioration diagnosing portion diagnoses whether the fuel-reforming catalyst is deteriorated based on the reforming-degrees of the fuel which are detected before and after a fuel-reforming control in which the fuel is reformed in the fuel-reforming catalyst is started.   
     
     
         9 . A diagnostic apparatus for a catalyst in a fuel-property reforming system of an internal combustion engine, according to  claim 7 , wherein:
 the reforming-degree detecting portion is a hydrogen sensor which detects hydrogen concentration in the fuel as the reforming-degree of the fuel.