The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 21, 1998
Filed:
Nov. 16, 1995
Yukio Kinugasa, Susono, JP;
Kouhei Igarashi, Susono, JP;
Takaaki Itou, Mishima, JP;
Toshifumi Takaoka, Susono, JP;
Toyota Jidosha Kabushiki Kaisha, Aichi, JP;
Abstract
In the present invention, a NO.sub.x absorbent is used for removing the NO.sub.x in the exhaust gas. The NO.sub.x absorbent absorbs NO.sub.x in the exhaust gas when the air-fuel ratio of the exhaust gas is lean, and releases the absorbed NO.sub.x and reduces it to nitrogen when the air-fuel ratio of the exhaust gas is rich or stoichiometric. To prevent the NO.sub.x absorbent from being saturated with the absorbed NO.sub.x, the NO.sub.x absorbent must be regenerated periodically by causing the NO.sub.x in the absorbent to be released and reduced. However, it is found that when the regenerating process by supplying a rich air-fuel ratio exhaust gas to the NO.sub.x absorbent is carried out at high NO.sub.x absorbent temperature, a part of NO.sub.x flows out from the NO.sub.x absorbent at the beginning of the regenerating process without being reduced. In the present invention, this outflow of NO.sub.x is suppressed by, for example, carrying out the regenerating process only when the temperature of the NO.sub.x absorbent is lowered to a predetermined temperature. This predetermined temperature is set low enough to ensure that the amount of the outflow of NO.sub.x is minimized.