Mazda Motor Corporation

Yuki Koda

Hiroshi Yamada

Hiroshi Murakami

Takashi Takemoto

Masahiko Shigetsu

Kenji Okamoto

Kazunari Komatsu

Satoshi Ichikawa

Taeko Shimizu

Akihide Takami

Hideharu Iwakuni

Fusatoshi Tanaka

Kenichi Yamamoto

Makoto Kyogoku

Ken Yoshida

Takuya Yamada

Kazuaki Hokazono

Toshitsugu Ueoka

Yuji Kojima

Noriaki Fujita

Kazuo Misonoo

Tomonori Nishida

Takayuki Tominaga

Shinichi Tanioka

Masayuki Koishi

Osamu Takayama

Takashi Kariya

Hiroyuki Ohmura

Keiko Matsui

Shintaro Umesaki

Arashi Imura

Takuya Nishihara

Yusaku Matsumura

Naoya Matsumoto

Kaori Imada

Tetsuya Date

Kazutoshi Matsuyama

Yusuke Ikushima

Hirotoshi Saito

An exhaust gas recirculation system for a multi-cylinder engine is provided, which includes an exhaust manifold connected to a cylinder head, a catalyst connected to a downstream end of the exhaust manifold in terms of an exhaust gas flow, an EGR gas outlet provided downstream of the catalyst, an in-head EGR passage penetrating the cylinder head, and an EGR pipe extending from the EGR gas outlet and directly connected to an inlet of the in-head EGR passage to lead EGR gas thereto. The catalyst is disposed so that the exhaust gas flows therein from a first side to a second side in an engine cylinder lined-up direction. The EGR gas outlet is located on the second side with respect to the center of the engine in the cylinder lined-up direction, and the inlet of the in-head EGR passage is located in the first side with respect to the engine center.

Engine exhaust gas recirculation system

The active temperature of an exhaust gas cleaning catalyst is shifted to a higher temperature side when Al.sub.2 O.sub.3 and/or CeO.sub.2 is used as a co-catalyst and/or when an oxidation number of Pt or Ir which is used as the noble active component is plus four.

Exhaust gas cleaning catalyst component, process of production of the

In the exhaust gas purifying catalyst (3), palladium is contained as a catalytic component and cerium oxide and (Ce, Pr) compound oxide is contained as a promoter. Now, the weight ratio of cerium oxide to (Ce, Pr) compound oxide is set between 9/1 and 7/3, and the ratio of praseodymium to cerium in the (Ce, Pr) compound oxide is set between 3 mol % and 50 mol %. In this way, because in this exhaust gas purifying catalyst (3), palladium with high low-temperature activity is used for a catalytic component, the exhaust gas purifying performance at low temperature is improved. And because cerium oxide and (Ce, Pr) compound oxide improves catalytic activity of palladium at high temperature, the exhaust gas purifying performance at high temperature, in particular, NOx purifying performance, is improved.

Catalyst for cleaning exhaust gas

An exhaust gas purifying catalyst (3) has an inner catalytic layer (5) fixed on a carrier (4). In the inner catalytic layer (5), there are held a palladium component, platinum component and a rhodium component by a base material containing an alumina component composed of alumina impregnated with lanthanum. Further, the exhaust gas purifying catalyst (3) has an outer catalytic layer (6) formed on the inner catalytic layer (5). In the outer catalytic layer (6), a palladium component is held by a base material which contains an alumina component, an oxide complex of ceria and zirconia and a magnesium component.

Catalyst for purifying exhaust gas

A catalyst (3) for purifying an automotive exhaust gas, in which inner and outer catalytic layers (5,6), each of which has a base material and a catalytic material held by the base material, are stratified on a honeycomb-type carrier (4). In the catalyst (3), the inner catalytic layer (5) contains a palladium component as the catalytic component. Further the inner catalytic layer (5) contains a nickel oxide component for preventing poisoning of the palladium component. On the other hand, though the outer catalytic layer (6) contains a rhodium component as the catalytic component, it does not contain a palladium component nor a nickel oxide component.

Growing community of inventors

Hiroshima, Japan

Yuki Koda