Exhaust gas purification system of internal combustion engine

Details Exhaust gas purification system of internal combustion engine Exhaust gas purification system of internal combustion engine

1999-07-15

2002-03-12

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

Methods

C060S277000, C060S297000

Reexamination Certificate

active

06354076

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an exhaust gas purification system of an internal combustion engine, more particularly to a system for discriminating the deterioration of an adsorbent which adsorbs unburned components of the exhaust gas generated by the engine to enhance exhaust gas purification.
2. Description of the Related Art
Internal combustion engines are ordinarily provided with a catalyst (a three-way catalytic converter) in the exhaust system which removes HC, NOx and CO components in the exhaust gas generated by the engine. However, when the engine is cold started, for example, and the catalyst is not activated, unburned components of the exhaust gas, in particular, unburned hydrocarbons (HC) are immediately exhausted to the atmosphere.
For that reason, there is proposed an exhaust gas purification system in Japanese Laid-Open Patent Application Hei 9 (1997)-324,621. In the system, the exhaust pipe is branched out at a location downstream of the catalyst and the bypass is provided with an adsorbent made of a zeolite material or some similar materials which adsorbs unburned components when the catalyst is not activated and desorbs the same after the catalyst has been activated to be recirculated to the engine intake system and burned again in the combustion chambers. Also the assignee proposed a similar system in Japanese Laid-Open Patent Applications Hei 10 (1998)-153,112.
Since if the adsorbent deteriorates it will not achieve the expected performance it is preferable to monitor and discriminate whether the adsorbent deteriorates.
SUMMARY OF THE INVENTION
The object of the invention is therefore to provide an exhaust gas purification system of an internal combustion engine having an adsorbent for adsorbing unburned components of the exhaust gas generated by the engine, which monitors and discriminates whether the adsorbent deteriorates.
Moreover, aside from the deterioration, when the adsorbent adsorbs the unburned components there is a limit beyond which, it can adsorb no more. When this limit is exceeded and exhaust gas is supplied to the adsorbent the adsorbed components such as hydrocarbons would, upon desorption, immediately be emitted to the air. In such an instance, the supply of exhaust gas to the adsorbent should accordingly be discontinued as quickly as possible.
A second object of the invention is therefore to provide an exhaust gas purification system of an internal combustion engine having an adsorbent for adsorbing unburned components of the exhaust gas generated by the engine, which can discontinue the supply of exhaust gas to the adsorbent when the adsorbent has adsorbed the unburned components up to its limit.
This invention achieves this object by providing a system for purifying exhaust gas generated by an internal combustion engine having an adsorbent, installed in an exhaust system of the engine, which adsorbs unburned components of the exhaust gas generated by the engine when the engine has started, comprising: a first temperature sensor for detecting at least one of a temperature of the adsorbent and a temperature at a location downstream of the adsorbent; time measuring means for measuring a time until the detected temperature becomes greater or equal to a predetermined value; and adsorbent deterioration discriminating means for discriminating whether the adsorbent deteriorates based on at least the measured time.


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