Exhaust purification device for internal combustion engine

Patent metadata

Field	Value
Publication number	US-9180410-B2
Application number	US-201114345533-A
Country	US
Kind code	B2
Filing date	Sep 20, 2011
Priority date	Sep 20, 2011
Publication date	Nov 10, 2015
Grant date	Nov 10, 2015

Abstract

A decrease in determination accuracy on filter trouble due to a decrease in detection accuracy of a PM sensor is restricted. A filter, a selective reduction type NOx catalyst provided on a downstream of the filter, the PM sensor detecting an amount of PM on a downstream of the selective reduction type NOx catalyst, and a removal section conducting a process for removing a reducing agent attached to the PM sensor in a case where at least one of conditions is satisfied that a temperature of the selective reduction type NOx catalyst is equal to or lower than a threshold, that a temperature of the exhaust is equal to or lower than a threshold, that a flow rate of the exhaust is equal to or higher than a threshold, and that an adsorption amount of the reducing agent in the selective reduction type NOx catalyst is equal to or larger than a threshold are included.

First claim

The invention claimed is:

1. An exhaust purification device for an internal combustion engine, the device comprising:
an exhaust passage that receives exhaust from the internal combustion engine;
a filter that is provided in the exhaust passage and that collects particulate matters in the exhaust;
a selective reduction NOx catalyst that is provided in the exhaust passage downstream of the filter and that reduces NOx by a supplied reducing agent;
a supply device that supplies the reducing agent to the selective reduction NOx catalyst, the reducing agent being supplied from upstream of the selective reduction NOx catalyst and downstream of the filter in the exhaust passage;
a PM sensor that detects an amount of the particulate matters in the exhaust at a location downstream of the selective reduction NOx catalyst in the exhaust passage; and
an electronic control unit configured to control a process for removing the reducing agent that attaches to the PM sensor by increasing a temperature of the PM sensor based on a determination that at least one of the following conditions is satisfied:
(a) a temperature of the selective reduction NOx catalyst is equal to or lower than a threshold, the temperature of the selective reduction NOx catalyst being received by the electronic control unit from a selective reduction NOx catalyst temperature sensor that directly detects the temperature of the selective reduction or that is provided in the exhaust passage downstream of the filter and upstream of the PM sensor,
(b) a temperature of the exhaust is equal to or lower than a threshold, the temperature of the exhaust gas being received by the electronic control unit from an exhaust gas temperature sensor provided in the exhaust passage,
(c) a flow rate of the exhaust is equal to or higher than a threshold, the flow rate of the exhaust being received by the electronic control unit from a flow meter, or
(d) an adsorption amount of the reducing agent in the selective reduction NOx catalyst is equal to or larger than a threshold, the adsorption amount of the reducing agent being calculated by the electronic control unit based on an amount of the reducing agent that passes through the selective reduction type NOx catalyst.

2. The exhaust purification device for the internal combustion engine according to claim 1 , wherein
the electronic control is configured to calculate the amount of the reducing agent that passes through the selective reduction NOx catalyst according to at least one of: the temperature of the selective reduction NOx catalyst or the temperature of the exhaust, the flow rate of the exhaust, and the adsorption amount of the reducing agent in the selective reduction NOx catalyst, and
that at least one of the conditions (a), (b), (c) or (d) is satisfied and
is a case where that the amount of the reducing agent that passes through the selective reduction NOx catalyst is equal to or larger than a threshold.

3. The exhaust purification device for the internal combustion engine according to claim 1 , wherein the electronic control unit is configured to control the process for removing the reducing agent that attaches to the PM sensor based on the determination that at least one of the conditions (a), (b), (c) or (d) is satisfied and based on a determination that a detection value of the PM sensor decreases.

4. The exhaust purification device for the internal combustion engine according to claim 1 , wherein the electronic control unit is configured to control the process for removing the reducing agent that attaches to the PM sensor based on the determination that at least one of the conditions (a), (b), (c) or (d) is satisfied and based on a determination that a time in which a detection value of the PM sensor becomes equal to or larger than a specified value after the process for removing the particulate matters that attach to the PM sensor is conducted is equal to or shorter than a threshold.

5. The exhaust purification device for the internal combustion engine according to claim 1 , wherein the electronic control unit is configured to control the process for removing the reducing agent that attaches to the PM sensor by increasing a temperature of the PM sensor to a first temperature value that is 360° C. or higher.

6. The exhaust purification device for the internal combustion engine according to claim 5 , wherein, upon increasing the temperature of the PM sensor to the first temperature value that is 360° C. or higher, the electronic control unit is further configured to determine whether a detection value of the PM sensor decreases and to increase the temperature of the PM to a higher temperature.

7. The exhaust purification device for the internal combustion engine according to claim 1 , wherein the electronic control unit increases the temperature of the PM sensor reducing agent that attaches to the PM sensor is increased by increasing the temperature of the exhaust.

8. The exhaust purification device for the internal combustion engine according to claim 7 , wherein the electronic control unit increases the temperature of the exhaust by supplying HC to the oxidation catalyst or by discharging a higher temperature gas from the internal combustion engine.

9. The exhaust purification device for the internal combustion engine according to claim 1 , wherein the electronic control unit discharges the higher temperature gas from the internal combustion engine, the higher temperature gas being heated by a heater.

Assignees

• Shirasawa Takeru
• Ogiso Makoto
• Nogi Yoshito
• Toyota Motor Co Ltd

Inventors

• Shirasawa Takeru
• Ogiso Makoto
• Nogi Yoshito

Classifications

• F01N2900/1411

  Exhaust gas flow rate, e.g. mass flow rate or volumetric flow rate · CPC title

• F01N3/2066 Primary

  Selective catalytic reduction [SCR] · CPC title

• F01N3/035

  with catalytic reactors · CPC title

• F01N2560/05

  the means being a particulate sensor · CPC title

• B01D53/9495 Primary

  Controlling the catalytic process · CPC title