Exhaust purification method and exhaust purification apparatus of internal combustion engine
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsShinicihi Takeshima, Toshiaki Tanaka, Tetsuya Yamashita
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Abstract
In an internal combustion engine, an exhaust passage is provided with a NOx storing and decomposing catalyst (20). When burning fuel under a lean air-fuel ratio, the nitrogen monoxide is adsorbed by the NOx storing and decomposing catalyst (20) and disassociated. At this time, the disassociated oxygen is held in the form of oxygen ions O− on the NOx storing and decomposing catalyst (20). By making the air-fuel ratio rich and purging part of these oxygen ions O−, the remaining oxygen ions O− are also purged. Due to this, the NOx purification performance of the NOx storing and decomposing catalyst (20) is restored.
Claims29
An exhaust purification method of an internal combustion engine wherein combustion gas or burned gas in an engine combustion chamber or an exhaust gas exhausted from the engine combustion chamber is brought into contact with a NOx storing and decomposing catalyst, nitrogen oxide contained in these gases is adsorbed at the NOx storing and decomposing catalyst and diassociated to nitrogen and oxygen when burning fuel under a lean air-fuel ratio, the diassociated oxygen is held on the NOx storing and decomposing catalyst at this time, the disassociated nitrogen is separated from the NOx storing and decomposing catalyst, an energy necessary for purging part of the oxygen held on the NOx storing and decomposing catalyst from the NOx storing and decomposing catalyst is imparted to the NOx storing and decomposing catalyst to purge part of the oxygen held on the NOx storing and decomposing catalyst from the NOx storing and decomposing catalyst, and this purging action induces the remaining oxygen held on the NOx storing and decomposing catalyst to be purged from the NOx storing and decomposing catalyst.
An exhaust purification apparatus of an internal combustion engine wherein a NOx storing and decomposing catalyst, adsorbing nitrogen oxide contained in combustion gas or burned gas and diassociating it to nitrogen and oxygen when burning fuel under a lean air-fuel ratio and, at this time, holding the disassociated oxygen and separating the disassociated nitrogen, is arranged in an engine combustion chamber or engine exhaust passage, energy imparting means for imparting to the NOx storing and decomposing catalyst the energy necessary for purging part of the oxygen held on the NOx storing and decomposing catalyst is provided, the energy necessary for purging part of the oxygen held on the NOx storing and decomposing catalyst from the NOx storing and decomposing catalyst is imparted to the NOx storing and decomposing catalyst to purge part of the oxygen held on the NOx storing and decomposing catalyst from the NOx storing and decomposing catalyst, and this purging action induces the remaining oxygen held on the NOx storing and decomposing catalyst to be purged from the NOx storing and decomposing catalyst.
An exhaust purification apparatus in an internal combustion engine providing an engine exhaust passage with an exhaust purification catalyst and making the air-fuel ratio of an exhaust gas periodically rich in a spike when continuously burning under a lean air-fuel ratio so as to purify the NOx in the exhaust gas, where a NOx storing and decomposing catalyst diassociating nitrogen monoxide and holding oxygen when burning fuel under a lean air-fuel ratio is used as an exhaust purification catalyst, a reducing agent is periodically supplied in the engine combustion chamber or in the engine exhaust passage upstream of the NOx storing and decomposing catalyst so as to periodically make the air-fuel ratio of the exhaust gas rich in a spike, and the amount of the periodically supplied reducing agent is smaller than the amount of the reducing agent necessary for reducing the nitrogen monoxide flowing into the NOx storing and decomposing catalyst in the interval from when the reducing agent is supplied the previous time to when the reducing agent is supplied the current time.
An exhaust purification apparatus in an internal combustion engine providing an engine exhaust passage with an exhaust purification catalyst and making the air-fuel ratio of an exhaust gas periodically rich in a spike when continuously burning under a lean air-fuel ratio so as to purify the NOx in the exhaust gas, where a NOx storing and decomposing catalyst diassociating nitrogen monoxide and holding oxygen when burning fuel under a lean air-fuel ratio is used as an exhaust purification catalyst, a reducing agent is periodically supplied in the engine combustion chamber or in the engine exhaust passage upstream of the NOx storing and decomposing catalyst so as to periodically make the air-fuel ratio of the exhaust gas rich in a spike, and the time interval from when the air-fuel ratio of the exhaust gas is made rich to when the air-fuel ratio of the exhaust gas is next made rich is increased the higher the temperature of the NOx storing and decomposing catalyst.
Dependencies are inferred from the claim text.