# US 10,502,115 B2 · Exhaust gas purification apparatus for an internal combustion engine

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- Number: US 10,502,115 B2
- Document ID: US10502115B2
- Status: Granted
- Kind: B2
- Application number: 15/909,530
- Filed: 2018-03-01
- Published: 2018-09-06
- Granted: 2019-12-10
- Earliest claimed: 2017-03-02
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Masataka Ogushi; Arifumi Matsumoto; Yoshihisa Tsukamoto; Hiromasa Nishioka
- Web page: https://patentgrep.com/patent/US10502115B2

## CPC

- F01N 3/208: {Control of selective catalytic reduction [SCR], e.g. by adjusting the dosing of reducing agent}
- B01D 53/9418: {for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas}
- B01D 53/9431: {Processes characterised by a specific device}
- B01D 53/9495: {Controlling the catalytic process}
- F01N 9/00: Electrical control of exhaust gas treating apparatus (monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00)
- F01N 11/00: Monitoring or diagnostic devices for exhaust-gas treatment apparatus
- F01N 2550/02: Catalytic activity of catalytic converters
- F01N 2560/06: the means being a temperature sensor
- F01N 2610/02: the substance being ammonia or urea
- F01N 2610/148: Arrangement of sensors
- F01N 2900/1402: Exhaust gas composition
- F01N 2900/1602: Temperature of exhaust gas apparatus
- F01N 2900/1621: Catalyst conversion efficiency
- Y02T 10/12: Improving ICE efficiencies
- Y02T 10/40: Engine management systems
- F01N: GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL-COMBUSTION ENGINES (arrangements in connection with gas exhaust of propulsion units in vehicles B60K13/00; combustion-air intake silencers specially adapted for, or arranged on, internal-combustion engines F02M35/00; protecting against, or damping, noise in general G10K11/16)
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

In order to supply a reducing agent to an NOx catalyst in an appropriate manner when the temperature of the NOx catalyst is high, in cases where the temperature of the NOx catalyst is equal to or higher than a predetermined temperature at which ammonia is oxidized, and in cases where an NOx reduction rate in the NOx catalyst is smaller than a predetermined lower limit reduction rate, when the addition of the additive agent is carried out at least twice by changing an equivalent ratio with respect to an amount of NOx flowing into the NOx catalyst, the equivalent ratio in equivalent ratio control is made larger in the case where an amount of change of an amount of reduction of NOx accompanying a change of the equivalent ratio is larger than an amount of change of an amount of oxidation of ammonia accompanying the change of the equivalent ratio, than in the case where it is smaller than that.

## Claims

### Claim 1

An exhaust gas purification apparatus for an internal combustion engine comprising:
an NOx selective catalytic reduction catalyst that is arranged in an exhaust passage of the internal combustion engine and selectively reduces NOx in an exhaust gas by using ammonia as a reducing agent;
an addition valve that is arranged in said exhaust passage at the upstream side of said NOx selective catalytic reduction catalyst and configured to add an additive agent, which is ammonia or a precursor of ammonia, into the exhaust gas;
a temperature sensor configured to acquire a temperature of said NOx selective catalytic reduction catalyst; and
a controller configured to carry out equivalent ratio control in which an amount of the additive agent corresponding to an amount of NOx flowing into said NOx selective catalytic reduction catalyst and an equivalent ratio is added from said addition valve;
wherein in cases where the temperature acquired by said temperature sensor is equal to or higher than a predetermined temperature at which ammonia is oxidized, and in cases where an NOx reduction rate in said NOx selective catalytic reduction catalyst is smaller than a predetermined lower limit reduction rate, when the addition of the additive agent from said addition valve is carried out at least twice by changing the equivalent ratio with respect to the amount of NOx flowing into said NOx selective catalytic reduction catalyst, said controller configured to make the equivalent ratio in said equivalent ratio control larger in the case where an amount of change of an amount of reduction of NOx accompanying a change of the equivalent ratio is larger than an amount of change of the amount of oxidation of ammonia accompanying the change of the equivalent ratio, than in the case where the amount of change of the amount of reduction of NOx accompanying the change of the equivalent ratio is smaller than the amount of change of the amount of oxidation of ammonia accompanying the change of the equivalent ratio.

### Claim 2 (depends on 1)

The exhaust gas purification apparatus for the internal combustion engine as set forth in claim 1, wherein
in cases where said amount of change of the amount of reduction of NOx is larger than said amount of change of the amount of oxidation of ammonia, said controller is configured to make the equivalent ratio in said equivalent ratio control larger than 1.

### Claim 3 (depends on 2)

The exhaust gas purification apparatus for the internal combustion engine as set forth in claim 2, wherein
in cases where said amount of change of the amount of reduction of NOx is larger than said amount of change of the amount of oxidation of ammonia, said controller is further configured to adjust the equivalent ratio in said equivalent ratio control in such a manner that the concentration of ammonia in the exhaust gas flowing out from said NOx selective catalytic reduction catalyst becomes equal to or less than a predetermined upper limit concentration.

### Claim 4 (depends on 2)

The exhaust gas purification apparatus for the internal combustion engine as set forth in claim 2, wherein
said controller is further configured to adjust the equivalent ratio in said equivalent ratio control in such a manner that the NOx reduction rate in said NOx selective catalytic reduction catalyst becomes equal to or more than said predetermined lower limit reduction rate.

### Claim 5 (depends on 1)

The exhaust gas purification apparatus for the internal combustion engine as set forth in claim 1, wherein
in cases where said amount of change of the amount of reduction of NOx is equal to or less than said amount of change of the amount of oxidation of ammonia, said controller is further configured to make the equivalent ratio in said equivalent ratio control equal to or less than 1.