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US 6,474,147 B2Granted
Exhaust-gas purification device for internal combustion engine
AssigneeHonda Giken Kogyo Kabushiki Kaisha
InventorsNobuaki Takaoka, Hiroshi Oono
Life of this patent
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Abstract
A proportional oxygen sensor, a three-way catalyst, a binary O2 sensor, a NOx purification device, and a binary O2 sensor are positioned in the named order in the exhaust system of an internal combustion engine. A correction coefficient KMON2, which is set in accordance with the degree of deterioration of a three-way catalyst, is used to correct the timer value tmMON2 used to measure the time extending from the time at which the output of the O2 sensor is changed when the air-fuel ratio is increased, until the time at which the output of the O2 sensor is changed. When the corrected timer value tmMON2 is smaller than a reference time TNOxREF, it is ascertained that deterioration of the NOx purification device has occurred.
Claims14
An exhaust-gas purification device for an exhaust system of an internal combustion engine, comprising:
- nitrogen oxide purifying means for absorbing nitrogen oxide in exhaust gases during a lean exhaust-gas condition;
- a three-way catalyst disposed upstream of said nitrogen oxide purifying means;
- a first oxygen sensor, disposed between said nitrogen oxide purifying means and said three-way catalyst, for detecting a first oxygen density in said exhaust gases;
- a second oxygen sensor, disposed downstream of said nitrogen oxygen purifying means, for detecting a second oxygen density in said exhaust gas;
- first deterioration determination means, for determining a degree of deterioration of said three-way catalyst;
- and
- second deterioration determination means, for evaluating deterioration of said nitrogen oxide purifying means, from the degree of deterioration of said three-way catalyst determined by said first deterioration determination means and a first determination time period, said first determination time period being after a lean air-fuel ratio of the exhaust gases has been shifted to a rich air-fuel ratio by an decrease in the air-fuel ratio of a mixture to be supplied to the internal combustion engine, said first determination time period being from a time when a value output by first oxygen sensor changes to a value indicating a rich air-fuel ratio until a time when a value output by said second oxygen sensor changes to a value indicating a rich air-fuel ratio.
4 more elements
An exhaust-gas purification device for an exhaust system of an internal combustion engine, comprising:
- nitrogen oxide purifying means for absorbing nitrogen oxide in exhaust gases during a lean exhaust-gas condition;
- a three-way catalyst disposed upstream of said nitrogen oxygen purifying means;
- a first oxygen sensor, disposed between said nitrogen oxide purifying means and said three-way catalyst, for detecting a first oxygen density in said exhaust gases;
- a second oxygen sensor, disposed downstream of said nitrogen oxygen purifying means, for detecting a second oxygen density in said exhaust gas;
- first deterioration determination means, for evaluating deterioration of said three-way catalyst;
- second deterioration determination means, for evaluating deterioration of said nitrogen oxide purifying means, based on the deterioration of said three-way catalyst and based on a first determination time period, said first determination time period being after a lean air-fuel ratio of the exhaust gases has been shifted to a rich air-fuel ratio by an decrease in the air-fuel ratio of a mixture to be supplied to the internal combustion engine, said first determination time period being from a time when a value output by first oxygen sensor changes to a value indicating a rich air-fuel ratio until a time when a value output by said second oxygen sensor changes to a value indicating a rich air-fuel ratio;
- and
- a third oxygen sensor, disposed upstream of said three-way catalyst, for detecting a third oxygen density in said exhaust gases;
- wherein said first deterioration means evaluates a degree of deterioration of said three-way catalyst based on a second determination time, said second determination time being after the lean exhaust gas has been shifted to the rich air-fuel ratio gas, said second determination time being from a time when a value output by said third oxygen sensor is changed to a value indicative of the rich air-fuel ratio until the value output by said first oxygen sensor is changed to a value indicative of said rich air-fuel ratio.
6 more elements
An exhaust-gas purification device for an exhaust system of an internal combustion engine, comprising:
- a nitrogen oxide purifier operative to absorb nitrogen oxide in exhaust gases during a lean exhaust-gas condition;
- a three-way catalyst disposed upstream of said nitrogen oxide purifier;
- a first oxygen sensor, disposed between said nitrogen oxide purifier and said three-way catalyst, for detecting a first oxygen density in said exhaust gases;
- a second oxygen sensor, disposed downstream of said nitrogen oxide purifier, for detecting a second oxygen density in said exhaust gases;
- a first deterioration determinator operative to determine a degree of deterioration of said three-way catalyst and generate three-way catalyst deterioration information;
- and
- a second deterioration determinator operative to evaluate deterioration of said nitrogen oxide purifier, from said degree of deterioration of said three-way catalyst determined by said first deterioration determinator and a first determination time period that occurs after a lean air-fuel ratio of the exhaust gases has been shifted to a rich air-fuel ratio by an decrease in the air-fuel ratio of a mixture to be supplied to the internal combustion engine, said first determination time period being from a time at which a value output by said first oxygen sensor changes to a value indicating a rich air-fuel ratio until a value output by said second oxygen sensor changes to a value indicating a rich air-fuel ratio.
4 more elements
Dependencies are inferred from the claim text.