Exhaust purification system

Patent metadata

Field	Value
Publication number	US-2016245141-A1
Application number	US-201415026387-A
Country	US
Kind code	A1
Filing date	Oct 8, 2014
Priority date	Oct 8, 2013
Publication date	Aug 25, 2016
Grant date	—

Abstract

An exhaust purification system includes a selective catalytic reduction (SCR) catalyst disposed at an exhaust system of an engine for using ammonia that is generated from urea water as a reducing agent to reduce NOx contained in exhaust gas, a device that injects urea water to the SCR catalyst, an inlet-side electrode that detects capacitance within the SCR catalyst at least from a vicinity of an inlet of the SCR catalyst to a vicinity of an intermediate section in an exhaust gas flowing direction, an outlet-side electrode that detects the capacitance within the SCR catalyst at least from the vicinity of the intermediate section to an outlet of the SCR catalyst in the exhaust gas flowing direction, and a calculation unit that calculates an ammonia adsorption amount within the SCR catalyst on a basis of the capacitances detected from the inlet-side and the outlet-side electrodes.

First claim

1 . An exhaust purification system comprising:
at least one selective reduction catalyst arranged in an exhaust system of an internal combustion engine and configured to reduce nitrogen compounds contained in exhaust gas with ammonia generated from an aqueous urea solution as a reducing agent for purification of the exhaust gas; an aqueous urea solution injection unit configured to inject the aqueous urea solution to the selective reduction catalyst; a first capacitance detecting unit configured to detect a first capacitance in the selective reduction catalyst, at least from a vicinity of an inlet of the selective reduction catalyst to a vicinity of a middle of the selective reduction catalyst in an exhaust gas flowing direction; a second capacitance detecting unit configured to detect a second capacitance in the selective reduction catalyst, at least from a vicinity of a middle of the selective reduction catalyst to a vicinity of an outlet of the selective reduction catalyst in the exhaust gas flowing direction; and a reducing agent adsorption amount calculation unit configured to calculate an adsorbed amount of the reducing agent in the selective reduction catalyst based on the detected first capacitance and second capacitance.

2 . The exhaust purification system according to claim 1 further comprising:
an injection control unit configured to control injection of the aqueous urea solution from the aqueous urea solution injection unit based on a predetermined standard injection amount set in accordance with at least a running condition of the internal combustion engine; and
an injection amount correction unit configured to correct the standard injection amount based on the adsorbed amount of the reducing agent entered from the reducing agent adsorption amount calculation unit.

3 . The exhaust purification system according to claim 2 further comprising an internal temperature calculation unit configured to calculate an internal temperature of the selective reduction catalyst based on the detected first capacitance and second capacitance,
wherein the injection amount correction unit corrects the standard injection amount based on a difference between the calculated adsorbed amount of the reducing agent and a maximum amount of the reducing agent adsorbable by the selective reduction catalyst corresponding to the calculated internal temperature.

4 . The exhaust purification system according to claim 1 , wherein
the first capacitance detecting unit includes at least one pair of first electrodes inserted into cells of the selective reduction catalyst from the inlet up to the vicinity of the middle of the selective reduction catalyst in the exhaust gas flowing direction to form a first capacitor; and the second capacitance detecting unit includes at least one pair of second electrodes inserted into cells of the selective reduction catalyst from the outlet up to the vicinity of the middle of the selective reduction catalyst along the exhaust gas flowing direction to form a second capacitor.

5 . The exhaust purification system according to claim 2 , wherein the first capacitance detecting unit includes at least one pair of first electrodes inserted into cells of the selective reduction catalyst from the inlet up to the vicinity of the middle of the selective reduction catalyst in the exhaust gas flowing direction to form a first capacitor; and
the second capacitance detecting unit includes at least one pair of second electrodes inserted into cells of the selective reduction catalyst from the outlet up to the vicinity of the middle of the selective reduction catalyst along the exhaust gas flowing direction to form a second capacitor.

6 . The exhaust purification system according to claim 3 , wherein the first capacitance detecting unit includes at least one pair of first electrodes inserted into cells of the selective reduction catalyst from the inlet up to the vicinity of the middle of the selective reduction catalyst in the exhaust gas flowing direction to form a first capacitor; and
the second capacitance detecting unit includes at least one pair of second electrodes inserted into cells of the selective reduction catalyst from the outlet up to the vicinity of the middle of the selective reduction catalyst along the exhaust gas flowing direction to form a second capacitor.

7 . The exhaust purification system according to claim 1 , wherein said at least one selective reduction catalyst includes a plurality of selective reduction catalysts.

8 . The exhaust purification system according to claim 1 , wherein the internal combustion engine is a diesel engine.

9 . The exhaust purification system according to claim 4 , wherein said at least one pair of first electrodes includes plural pairs of first electrodes arranged in a diametrical direction of the selective reduction catalyst.

10 . The exhaust purification system according to claim 4 , wherein said at least one pair of second electrodes includes plural pairs of second electrodes arranged in a diametrical direction of the selective reduction catalyst.

Assignees

• Isuzu Motors Ltd

Inventors

• Uchiyama Tadashi
• Fujie Hidekazu
• Murasawa Naoto
• Hanawa Satoshi

Classifications

• F01N3/021

  by means of filters · CPC title

• F01N3/103

  Oxidation catalysts for HC and CO only · CPC title

• F01N13/0093

  the purifying devices are of the same type · CPC title

• F01N13/009

  having two or more separate purifying devices arranged in series · CPC title

• F01N2900/1622

  Catalyst reducing agent absorption capacity or consumption amount · CPC title