MONITORING SYSTEM FOR SELECTIVE CATALYST REDUCTION SYSTEM

• US 20090155130A1
• Filed: 08/18/2008
• Published: 06/18/2009
• Est. Priority Date: 12/14/2007
• Status: Active Grant

• Current Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Original Assignee: Hyundai Motor Company (Hyundai Motor Group)
• Inventors: Choi, Chang Eun
• Granted Patent: US 8,894,935 B2
• Time in Patent Office: Days
• US Class Current: 422/111
• CPC Class Codes: F01N 2240/20 a flow director or deflector
• CPC Class Codes: F01N 2560/026 for measuring or detecting NOx
• CPC Class Codes: F01N 2560/14 having more than one sensor of one kind
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/146 Control thereof, e.g. control of injectors or injection valves
• CPC Class Codes: F01N 2900/08 said parameters being related to the engine
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A monitoring system for a selective catalyst reduction system according to the present invention includes a selective catalyst reduction system that reacts with ammonia and reduces NOx, a first NOx sensor that is disposed upstream of the selective catalyst reduction system and measures the amount of the NOx that flows into the selective catalyst reduction system, a second NOx sensor that is disposed downstream of the selective catalyst reduction system and measures the amount of the NOx that is reduced, an injector that is disposed between the first NOx sensor and the selective catalyst reduction system and injects a urea solution, and a control portion that calculates reduction efficiency based on signals that are detected from the first NOx sensor and the second NOx sensor, determines the necessary amount of the ammonia according to the reduction efficiency, and controls the injection amount of the urea solution through the injector.

Claims

1. A monitoring system for a selective catalyst reduction system, comprising:

the selective catalyst reduction system that reacts with ammonia and reduces NOx;

a first NOx sensor that is disposed upstream of the selective catalyst reduction system and measures the amount of the NOx that flows into the selective catalyst reduction system;

a second NOx sensor that is disposed downstream of the selective catalyst reduction system and measures the reduced amount of the NOx that flows out of the selective catalyst reduction system;

an injector that is disposed between the first NOx sensor and the selective catalyst reduction system and injects a urea solution; and

a control portion that calculates reduction efficiency based on signals detected from the first NOx sensor and the second NOx sensor, determines the necessary amount of ammonia according to the reduction efficiency, and controls the determined injection amount of the urea solution through the injector.

2. The monitoring system for a selective catalyst reduction system of claim 1, wherein a mixer is disposed between the injector and the selective catalyst reduction system.

3. The monitoring system for a selective catalyst reduction system of claim 1, wherein the control portion applies the calculated reduction efficiency to engine speed and fuel amount conditions to determine the necessary amount of ammonia according to the reduction efficiency.

4. The monitoring system for a selective catalyst reduction system of claim 1, wherein a middle value sensor is applied to at least one of the first NOx sensor and the second NOx sensor.

5. The monitoring system for a selective catalyst reduction system of claim 4, wherein the second NOx sensor is a middle value sensor.

6. The monitoring system for a selective catalyst reduction system of claim 4, wherein a possible deviation of the middle value NOx sensor is within a first predetermined range.

7. The monitoring system for a selective catalyst reduction system of claim 4, wherein a possible deviation of the middle value NOx sensor is within a second predetermined range.

8. The monitoring system for a selective catalyst reduction system of claim 4, wherein a possible deviation of the middle value NOx sensor is within a third predetermined range.

9. The monitoring system for a selective catalyst reduction system of claim 1, wherein the control portion applies an ammonia conversion coefficient of the urea solution and determines a final amount of the urea solution according to a necessary ammonia amount.

10. The monitoring system for a selective catalyst reduction system of claim 1, wherein the control portion uses signals of one of a pulse width modulation (PWM) duty, and on/off pulse controls the injector.