Denso Corporation

Toyota Jidosha Kabushiki Kaisha

Yoichi Kadota

Go Hayashita

Kenji Furui

Tomohiko Nakanishi

Kensuke Takizawa

Yasushi Takayama

A catalyst degradation detection apparatus includes an air-fuel ratio detector disposed downstream of a catalyst and configured to detect an air-fuel ratio of exhaust gas flowing out from the catalyst, and an electronic control unit configured to control an air-fuel ratio of inflow exhaust gas flowing into the catalyst and determine whether the catalyst is degraded. The electronic control unit is configured to execute degradation determination control that brings the air-fuel ratio of the inflow exhaust gas to an air-fuel ratio leaner or richer than a stoichiometric air-fuel ratio. The electronic control unit is configured to determine whether precious metal of the catalyst is degraded based on the air-fuel ratio detected by the air-fuel ratio detector when an oxygen storage amount of the catalyst is varying in the degradation determination control.

Catalyst degradation detection apparatus

The catalyst deterioration detection systemcomprises an air-fuel ratio detection devicedetecting an air-fuel ratio of an exhaust gas flowing out from the catalyst, an air-fuel ratio control part, and a deterioration judgment part. The air-fuel ratio control part is configured to perform a lean control making the air-fuel ratio of the inflowing exhaust gas leaner than a stoichiometric air-fuel ratio and a rich control making the air-fuel ratio of the inflowing exhaust gas richer than the stoichiometric air-fuel ratio. The deterioration judgment part is configured to calculate an amplitude of an air-fuel ratio of an exhaust gas flowing out from the catalyst due to the lean control and the rich control based on an output of the air-fuel ratio detection device and judge that the catalyst is deteriorating if the amplitude is equal to or greater than a threshold value.

Catalyst deterioration detection system

The exhaust gas purification device of the present embodiment is provided in an exhaust gas flow path of an internal combustion engine. The exhaust gas purification device includes a honeycomb catalyst and a PM trapping filter. The honeycomb catalyst is formed by supporting a catalyst on a first substrate which is made of a promoter and has a honeycomb structure. The PM trapping filter is located on the exhaust gas downstream side of the honeycomb catalyst and includes a second substrate having a honeycomb structure, configured to be capable of trapping PM.

Exhaust gas purification device

A porous honeycomb structure including multiple co-catalyst particles and multiple inorganic binder particles of smaller particle diameter than the co-catalyst particles. Each co-catalyst particle is comprised of a ceria-zirconia solid solution. The inorganic binder particles reside between the co-catalyst particles. In the honeycomb structure, an exposure fraction of the co-catalyst particles from the inorganic binder particles on a cross-section of the honeycomb structure is within a range of 3 to 10%.

Porous honeycomb structure and producing the same

A honeycomb structure body has promoter particles made of ceria-zirconia solid solution, and inorganic binder particles made of alumina arranged between the promoter particles, and a cerium aluminate phase formed on a boundary surface between the promoter particles and the inorganic binder particles. Further, a method of producing the honeycomb structure body has at least first and second steps. The first step molds raw material to form a honeycomb molded body. The raw material has a mixture of promoter particles and a sol containing inorganic binder particles. The second step fires the honeycomb molded body in an atmosphere having an oxygen concentration of not more than 0.5 vol. % to produce the honeycomb structure body.

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Kariya, Japan

Yoichi Kadota