Apparatus for diminishing nitrogen oxides

• US 5,410,873 A
• Filed: 11/09/1993
• Issued: 05/02/1995
• Est. Priority Date: 06/03/1991
• Status: Expired due to Fees

• Current Assignee: Isuzu Motors Limited
• Original Assignee: Isuzu Motors Limited
• Inventors: Tashiro, Yoshihisa
• Primary Examiner(s): Lazarus, Ira S.
• Assistant Examiner(s): O'CONNOR, DANIEL
• Application Number:
  US08/146,097
• Time in Patent Office: 539 Days
• Field of Search: 60/274, 60/276, 60/277, 60/285, 60/286, 123/672, 123/681, 123/703
• US Class Current: 60/276
• CPC Class Codes: F01N 2430/06 by varying fuel-air ratio, e.g. by enriching fuel-air mixture
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2610/03 the substance being hydrocarbons, e.g. engine fuel
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F02B 1/04 with fuel-air mixture admission into cylinder
• CPC Class Codes: F02B 3/06 with compression ignition compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02
• CPC Class Codes: F02D 41/1462 with determination means using an estimation
• CPC Class Codes: F02D 41/1463 of the exhaust gases downstream of exhaust gas treatment apparatus
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

An apparatus for diminishing the amount of NO_x in the exhaust gases of an engine by a catalytic converter installed in its exhaust system. The apparatus includes an injector associated with the intake system of the engine, or the exhaust system upstream of the catalytic converter for injecting fuel into the intake, or exhaust system to ensure that the catalytic converter receives a sufficient supply of hydrocarbon. The amount of NO_x in the exhaust gases leaving the engine is estimated from the number of revolutions thereof and the angle of a control lever, or the concentration of NO_x in the exhaust gases leaving the catalytic converter is detected by a sensor. The amount of fuel injection into the intake, or exhaust system is controlled in accordance with the estimated amount of NO_x, or the output of the sensor.

Claims

1. In an apparatus for diminishing the amount of nitrogen oxides in the exhaust gases of an engine of the type having fuel injected into its cylinders, the improvement which comprises an injector associated with the intake system of the engine for injecting fuel into said intake system;

means for determining said amount of nitrogen oxides from the number of revolutions of the engine and the angle of a control lever; and

means for controlling the amount of fuel injection by said injector in accordance with the load of the engine and said amount of nitrogen oxides as determined.

2. In an apparatus for diminishing the amount of nitrogen oxides in the exhaust gases of an engine of the type having fuel injected into its cylinders, the improvement which comprises an injector associated with the intake system of the engine for injecting fuel into said intake system;

a sensor for nitrogen oxides installed in the exhaust system of the engine downstream of a catalytic converter for detecting the concentration of nitrogen oxides in the exhaust gases leaving said converter; and

means for controlling the amount of fuel injection by said injector in accordance with the load of the engine and the output of said sensor.

3. In an apparatus for diminishing the amount of nitrogen oxides in the exhaust gases of an engine, the improvement which comprises an injector associated with the exhaust system of the engine for injecting fuel into said exhaust system upstream of a catalytic converter;

a sensor for nitrogen oxides installed in said exhaust system downstream of said converter for detecting the concentration of nitrogen oxides in the exhaust gases leaving said converter; and

means for controlling the amount of fuel injection by said injector in accordance with the load of the engine and the output of said sensor.

4. In an apparatus for diminishing the amount of nitrogen oxides in exhaust gases of a fuel injected engine having a load applied thereto, said engine having a cylinder, an intake system and an exhaust system, the improvement which comprises an injector associated with one of the intake system and the exhaust system of the engine for injecting fuel into one of said intake and exhaust systems;

means for determining the amount of nitrogen oxides in the exhaust gases; and

means for controlling the amount of fuel injected by said injector in accordance with the load of the engine and the amount of nitrogen oxides in the exhaust gases.

5. The apparatus defined by claim 4 wherein the means for determining the amount of nitrogen oxides in the exhaust gases of said engine is a sensor for nitrogen oxides installed in the exhaust system of the engine downstream of a catalytic converter.

6. The apparatus defined by claim 5 wherein said injector is associated with the intake system of said engine for injecting fuel into said intake system.

7. The apparatus defined by claim 5 wherein said injector is associated with the exhaust system of said engine for injecting fuel into said exhaust system.

8. The apparatus defined by claim 4 which further comprises a controller, an engine rotation sensor and a control lever sensor, said controller controlling the amount of fuel injected by said injector in accordance with the outputs of said rotation and control lever sensors.

9. The apparatus defined by claim 5 which further comprises a controller, an engine rotation sensor and a control lever sensor, said controller controlling the amount of fuel injected by said injector in accordance with the outputs of said rotation, control lever and nitrogen oxide sensors.