Honda Giken Kogyo Kabushiki Kaisha

Nobuaki Takaoka

Hiroshi Oono

Toshikatsu Takanohashi

Masahiro Sakanushi

Yoshio Maeda

Keiichi Nagashima

A proportional oxygen sensor, a three-way catalyst, a binary O sensor, a NOx purification device, and a binary O sensor are positioned in the named order in the exhaust system of an internal combustion engine. A correction coefficient KMON which is set in accordance with the degree of deterioration of a three-way catalyst, is used to correct the timer value tmMON used to measure the time extending from the time at which the output of the O sensor is changed when the air-fuel ratio is increased, until the time at which the output of the O sensor is changed. When the corrected timer value tmMON is smaller than a reference time TNOxREF, it is ascertained that deterioration of the NOx purification device has occurred.

Exhaust-gas purification device for internal combustion engine

In order to prevent degradation of an operational mode and a fuel consumption of an internal combustion engine at the time when raising the temperature of a catalyst poisoned NOx absorbent for removing the accumulated sulfur compounds, an exhaust purifying apparatus is provided in an exhaust pipe connected to an internal combustion engine The exhaust purifying apparatus comprises an air-fuel ratio controlling device for controlling the air-fuel ratio, and a fuel feeder for feeding fuel upstream of said nitrogen oxide absorbent; a temperature raising device for raising the temperature of the nitrogen oxide absorbent by feeding fuel by means of said fuel feeder, when the absorbing capability of the nitrogen oxide absorbent is catalyst poisoned by the accumulated sulfur compounds; and a restoring device for restoring the nitrogen oxide absorbing capability of said nitrogen oxide absorbent by controlling the air-fuel ratio so as to be made richer than the stoichiometric air-fuel ratio by said air-fuel ratio controlling device.

Exhaust purifying apparatus for internal combustion engine

An exhaust emission control system for a nitrogen oxide removing device, the control system having a first oxygen concentration sensor provided upstream of the nitrogen oxide removing device, a second oxygen concentration sensor provided downstream of the nitrogen oxide removing device. A first response delay time period from the time when the output value from the first oxygen concentration sensor has changed to a value indicative of a rich air-fuel ratio to the time when the output value from the second oxygen concentration sensor becomes a value indicative of a rich air-fuel ratio is measured. A second response delay time period from the time when the output value from the first oxygen concentration sensor has changed to a value indicative of a lean air-fuel ratio, to the time when the output value from the second oxygen concentration sensor becomes a value indicative of a lean air-fuel ratio is measured. Deterioration of the nitrogen oxide removing device is determined according to the first and second response delay time periods.

Exhaust emission control system for internal combustion engine

A system for purifying exhaust gas of an internal combustion engine having a NOx reduction catalyst (NOx absorber) installed in the exhaust system of the engine which absorbs NOx in the exhaust gas generated by the engine in a lean environment where a lean fuel mixture is supplied and desorbs to reduce the absorbed NOx in a rich environment where a rich mixture is supplied. In the system, the rich fuel mixture is supplied for a period immediately before cutoff. With the arrangement, the NOx reduction catalyst desorbs the absorbed NOx and is regenerated to absorb NOx sufficiently. At the same time, the NOx reduction catalyst is regenerated from sulfur poisoning, thereby preventing the NOx purification efficiency from being degraded.

Exhaust gas purification system for internal combustion engine

An exhaust gas-purifying system for an internal combustion engine comprises an exhaust gas-purifying device arranged in the exhaust system of the engine and accommodating a nitrogen oxide absorbent for absorbing nitrogen oxides in exhaust gases emitted from the engine when the engine operates in a state where the air-fuel ratio of the exhaust gases is leaner than a stoichiometric air-fuel ratio. A cylinder internal pressure sensor detects pressure within at least one of the cylinders of the engine. The amount of nitrogen oxides generated within the engine is determined based on the pressure within the at least one of the cylinders. It is determined whether the amount of nitrogen oxides absorbed by the nitrogen oxide absorbent has been saturated, based on the determined amount of nitrogen oxides.

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Wako, Japan

Nobuaki Takaoka