Exhaust purification system

Patent metadata

Field	Value
Publication number	US-2016237872-A1
Application number	US-201415026494-A
Country	US
Kind code	A1
Filing date	Oct 8, 2014
Priority date	Oct 8, 2013
Publication date	Aug 18, 2016
Grant date	—

Abstract

An exhaust purification system includes: a diesel oxidation catalyst (DOC) provided on an exhaust path of an engine; an upstream diesel particulate filter (DPF) and a downstream DPF that are provided on the exhaust path at positions downstream of the DOC to collect particulate matter contained in exhaust gas; electrodes that detect a capacitance of the upstream DPF; a particulate matter accumulation estimating unit that estimates at least an amount of particulate matter accumulated in the downstream DPF on the basis of the capacitance received from the electrodes; and a forced regeneration control unit that injects fuels into the DOC and performs forced regeneration that burns and removes at least the particulate matter accumulated in the downstream DPF when the estimated amount of particulate matter from the particulate matter accumulation estimating unit surpasses a predetermined amount.

First claim

1 . An exhaust purification system comprising:
an oxidation catalyst provided in an exhaust passage of an internal combustion engine; a pair of first and second filters provided in the exhaust passage at positions downstream of the oxidation catalyst to collect particulate matter contained in exhaust gas; an electrostatic capacity detecting unit configured to detect an electrostatic capacity of the first filter; an accumulation amount estimating unit configured to estimate an amount of accumulated particulate matter at least in the second filter based on the electrostatic capacity entered from the electrostatic capacity detecting unit; and a filter regenerating unit configured to execute a forced regeneration to burn and remove the particulate matter that has accumulated at least in the second filter by injecting fuel to the oxidation catalyst when the amount of accumulated particulate matter entered from the accumulation amount estimating unit exceeds a predetermined amount.

2 . The exhaust purification system according to claim 1 , wherein the first filter and the second filter are disposed in series in the exhaust passage along an exhaust gas flowing direction.

3 . The exhaust purification system according to claim 1 further comprising a bypass passage that branches off from the exhaust passage at a position downstream of the oxidation catalyst so as to bypass the second filter, wherein the first filter is disposed in the bypass passage.

4 . The exhaust purification system according to claim 1 further comprising:
an internal temperature estimating unit configured to estimate an internal temperature of the first filter based on the electrostatic capacity entered from the electrostatic capacity detecting unit; and
an injection amount correcting unit configured to correct a fuel injection amount of the filter regenerating unit based on a temperature difference between a filter target temperature in a forced regeneration and the internal temperature entered from the internal temperature estimating unit.

5 . The exhaust purification system according to claim 1 , wherein the electrostatic capacity detecting unit includes at least one pair of electrodes disposed in the first filter so as to face each other with at least one partition wall interposed therebetween to form a capacitor.

6 . The exhaust purification system according to claim 2 further comprising:
an internal temperature estimating unit configured to estimate an internal temperature of the first filter based on the electrostatic capacity entered from the electrostatic capacity detecting unit; and
an injection amount correcting unit configured to correct a fuel injection amount of the filter regenerating unit based on a temperature difference between a filter target temperature in a forced regeneration and the internal temperature entered from the internal temperature estimating unit.

7 . The exhaust purification system according to claim 3 further comprising:
an internal temperature estimating unit configured to estimate an internal temperature of the first filter based on the electrostatic capacity entered from the electrostatic capacity detecting unit; and
an injection amount correcting unit configured to correct a fuel injection amount of the filter regenerating unit based on a temperature difference between a filter target temperature in a forced regeneration and the internal temperature entered from the internal temperature estimating unit.

8 . The exhaust purification system according to claim 2 , wherein the electrostatic capacity detecting unit includes at least one pair of electrodes disposed so as to face each other with at least one partition wall interposed therebetween in the first filter to form a capacitor.

9 . The exhaust purification system according to claim 3 , wherein the electrostatic capacity detecting unit includes at least one pair of electrodes disposed so as to face each other with at least one partition wall interposed therebetween in the first filter to form a capacitor.

10 . The exhaust purification system according to claim 4 , wherein the electrostatic capacity detecting unit includes at least one pair of electrodes disposed so as to face each other with at least one partition wall interposed therebetween in the first filter to form a capacitor.

11 . The exhaust purification system according to claim 2 , wherein the first filter includes a first diesel particulate filter and has a first length in the exhaust gas flowing direction.

12 . The exhaust purification system according to claim 11 , wherein the second filter includes a second diesel particulate filter and a second length in the exhaust gas flowing direction.

13 . The exhaust purification system according to claim 12 , wherein the first length of the first filter is shorter than the second length of the second filter.

14 . The exhaust purification system according to claim 1 , wherein the electrostatic capacity detecting unit is located between the first filter and the second filter.

15 . The exhaust purification system according to claim 3 further comprising an orifice disposed in the bypass passage to regulate a flow rate of the exhaust gas.

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

Assignees

• Isuzu Motors Ltd

Inventors

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

Classifications

• F01N3/106

  Auxiliary oxidation catalysts · CPC title

• F01N3/0253

  adding fuel to exhaust gases · CPC title

• F01N2900/1606

  Particle filter loading or soot amount · CPC title

• F01N13/011

  having two or more purifying devices arranged in parallel · CPC title

• F01N13/0093

  the purifying devices are of the same type · CPC title