Exhaust emission purification apparatus for an internal combustion engine
First Claim
1. An exhaust emission gas purification apparatus for an internal combustion engine, comprising:
- a lean NOx catalyst arranged in the exhaust pipe of an internal combustion engine;
a hydrocarbon supply means for supplying hydrocarbon into the exhaust gas for reducing NOx upstream of said NOx catalyst;
a state variables detection means for detecting state variables representing the operating conditions of said lean NOx catalyst;
a basic hydrocarbon supply amount determining means for determining the basic amount of hydrocarbon supplied from said hydrocarbon supply means in accordance with the state variables detected by said state variables detection means;
a temperature difference detection means for detecting the difference between the exhaust gas temperature at the inlet of said lean NOx catalyst and the temperature of the lean NOx catalyst which are included in the state variables detected by said state variables detection means; and
a hydrocarbon supply amount correction means for correcting the basic hydrocarbon amount determined by said basic hydrocarbon supply amount determining means in accordance with the temperature difference detected by said temperature difference detection means.
1 Assignment
0 Petitions
Accused Products
Abstract
An exhaust emission gas purification apparatus for an internal combustion engine is disclosed, in which a proper purification rate can be maintained even at a transient time by suppressing an excessive temperature increase of a lean NOx catalyst. In order to improve the purification efficiency of a lean NOx catalyst 307, diesel fuel constituting a hydrocarbon material capable of reducing the NOx is supplied by way of a diesel fuel injection hole 311. A basic amount of diesel fuel to be supplied is determined on the basis of a space velocity SV providing a quantity of state representing the operating conditions of the catalyst calculated from the intake air amount detected by an air flowmeter 302 and the catalyst temperature detected by an outlet exhaust gas temperature sensor 322. The basis amount of diesel fuel to be supplied is corrected based on the difference between the catalyst temperature and the inlet exhaust gas temperature detected by the inlet exhaust gas temperature sensor 321. The purification rate of the catalyst can thus be prevented from being deteriorated at a transient time.
-
Citations
10 Claims
-
1. An exhaust emission gas purification apparatus for an internal combustion engine, comprising:
-
a lean NOx catalyst arranged in the exhaust pipe of an internal combustion engine; a hydrocarbon supply means for supplying hydrocarbon into the exhaust gas for reducing NOx upstream of said NOx catalyst; a state variables detection means for detecting state variables representing the operating conditions of said lean NOx catalyst; a basic hydrocarbon supply amount determining means for determining the basic amount of hydrocarbon supplied from said hydrocarbon supply means in accordance with the state variables detected by said state variables detection means; a temperature difference detection means for detecting the difference between the exhaust gas temperature at the inlet of said lean NOx catalyst and the temperature of the lean NOx catalyst which are included in the state variables detected by said state variables detection means; and a hydrocarbon supply amount correction means for correcting the basic hydrocarbon amount determined by said basic hydrocarbon supply amount determining means in accordance with the temperature difference detected by said temperature difference detection means. - View Dependent Claims (2, 3, 4, 5)
-
-
6. An exhaust emission gas purification method for internal combustion engines, comprising the steps of:
-
supplying hydrocarbon into the exhaust gas for reducing the NOx upstream of the lean NOx catalyst arranged in the exhaust pipe of the internal combustion engine; detecting the state variables representing the operating conditions of said lean NOx catalyst; determining the basic amount of hydrocarbon supplied in said hydrocarbon supply step in accordance with the state variables detected in said state variables detection step; detecting the difference between the temperature of the exhaust gas at the inlet of said lean NOx catalyst and the temperature of said lean NOx catalyst which are included in the state variables detected at said state variables detection step; and correcting the basic hydrocarbon supply amount determined in said basic hydrocarbon supply amount determining step in accordance with the temperature difference detected in said temperature difference detection step. - View Dependent Claims (7, 8, 9, 10)
-
Specification