# US 10,309,332 B2 · Exhaust gas purification system for internal combustion engine

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- Number: US 10,309,332 B2
- Document ID: US10309332B2
- Status: Granted
- Kind: B2
- Application number: 15/496,317
- Filed: 2017-04-25
- Published: 2017-11-02
- Granted: 2019-06-04
- Earliest claimed: 2016-04-28
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Kazuya Suzuki; Koichi Hoshi
- Web page: https://patentgrep.com/patent/US10309332B2

## CPC

- F02D 41/263: {the program execution being modifiable by physical parameters}
- F01N 3/101: {Three-way catalysts}
- 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 11/007: {the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus}
- F01N 13/008: {Mounting or arrangement of exhaust sensors in or on exhaust apparatus (sensor arrangements for engine control F02D41/1439)}
- F02D 41/008: {Controlling each cylinder individually}
- F02D 41/1439: {characterised by the position of the sensor}
- F02D 41/1454: {the characteristics being an oxygen content or concentration or the air-fuel ratio}
- F02D 41/1473: {characterised by the regulation method}
- F01N 2430/06: by varying fuel-air ratio, e.g. by enriching fuel-air mixture
- F01N 2560/025: for measuring or detecting O2, e.g. lambda sensors
- F02D 41/0295: {Control according to the amount of oxygen that is stored on the exhaust gas treating apparatus}
- Y02T 10/12: Improving ICE efficiencies
- Y02T 10/40: Engine management systems
- F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W)
- 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)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

When the air fuel ratio dither control is carried out, an air fuel ratio of a mixture in each of one or more lean cylinders and one or more rich cylinders is controlled in a feedback manner based on an average value of a detected value of an air fuel ratio sensor, so that an average value of an air fuel ratio of exhaust gas flowing into the three-way catalyst becomes a predetermined target exhaust gas air fuel ratio. At this time, the air fuel ratio dither control is carried out, by setting at least a cylinder with the highest gas impingement intensity in a cylinder group of an internal combustion engine as the one or more lean cylinders.

## Claims

### Claim 1

An exhaust gas purification system for an internal combustion engine comprising a cylinder group including a plurality of cylinders, the system comprising:
a three-way catalyst that is arranged in an exhaust passage at the downstream side of a merge portion of exhaust branch pipes which are connected to individual cylinders of the cylinder group;
an air fuel ratio sensor that is arranged in a portion in the exhaust passage at the upstream side of the three-way catalyst; and
a controller comprising at least one processor configured to control an air fuel ratio of a mixture in a part of the cylinders of the cylinder group to a lean air fuel ratio leaner than a stoichiometric air fuel ratio, and control an air fuel ratio of a mixture in a part of the other cylinders of the cylinder group to a rich air fuel ratio richer than the stoichiometric air fuel ratio, and carry out air fuel ratio dither control in which the air fuel ratio of the mixture in each of one or more lean cylinders, in which the air fuel ratio of the mixture is controlled to the lean air fuel ratio, and one or more rich cylinders, in which the air fuel ratio of the mixture is controlled to the rich air fuel ratio, is controlled in a feedback manner based on an average value of a detected value of the air fuel ratio sensor, in such a manner that an average value of an air fuel ratio of exhaust gas flowing into the three-way catalyst becomes a predetermined target exhaust gas air fuel ratio;
wherein the controller carries out the air fuel ratio dither control by setting as the one or more lean cylinders, at least a cylinder, in which a gas impingement intensity, which is an intensity of impingement of exhaust gas discharged from the cylinder against the air fuel ratio sensor, is the highest, in the cylinder group.

### Claim 2 (depends on 1)

The exhaust gas purification system for an internal combustion engine according to claim 1, wherein
the controller further carries out the air fuel ratio dither control, by setting, as the one or more rich cylinders, at least a cylinder with the lowest gas impingement intensity in the cylinder group.

### Claim 3 (depends on 1)

The exhaust gas purification system for an internal combustion engine according to claim 1, wherein
when the air fuel ratio dither control is carried out by setting, as the one or more lean cylinders, two or more of the plurality of cylinders in the cylinder group, the controller carries out the air fuel ratio dither control, by setting, as the one or more lean cylinders, cylinders in the cylinder group in the order of decreasing the gas impingement intensity from the highest.

### Claim 4 (depends on 2)

The exhaust gas purification system for an internal combustion engine according to claim 2, wherein
when the air fuel ratio dither control is carried out by setting, as the one or more lean cylinders, two or more of the plurality of cylinders in the cylinder group, the controller carries out the air fuel ratio dither control, by setting, as the one or more lean cylinders, cylinders in the cylinder group in the order of decreasing the gas impingement intensity from the highest.

### Claim 5 (depends on 1)

The exhaust gas purification system for an internal combustion engine according to claim 1, wherein
when the air fuel ratio dither control is carried out by setting, as the one or more lean cylinders, two cylinders of which the order of combustion is continuous among the plurality of cylinders in the cylinder group, the controller carries out the air fuel ratio dither control, by setting, as the one or more lean cylinders, a cylinder with the highest gas impingement intensity in the cylinder group, and another cylinder of which the combustion order is immediately before or after the cylinder with the highest gas impingement intensity and which has a higher gas impingement intensity than that of a cylinder of which the combustion order is immediately after or before the cylinder with the highest gas impingement intensity.