Patents by Inventor Hisashi Zaima

Hisashi Zaima has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Exhaust purification system for multiple cylinder engines
    Patent number: 5247793
    Abstract: An exhaust purification system has an upstream exhaust gas sensor and a downstream exhaust gas sensor disposed downstream of a catalytic device. Each sensor detects an oxygen concentration in exhaust gases and provides an output which inverts between a lean state, representative of a lean air/fuel ratio, and a rich state, representative of a rich air/fuel ratio, according to oxygen concentrations. The upstream exhaust sensor is determined to have deteriorated when an output from the upstream exhaust sensor is kept in a predetermined correlation with an output from the downstream exhaust sensor while the output from the downstream exhaust sensor remains the same.
    Type: Grant
    Filed: March 30, 1992
    Date of Patent: September 28, 1993
    Assignee: Mazda Motor Corporation
    Inventors: Hideki Yamada, Hisashi Zaima, Shigeki Yamashita, Kazuo Tanaka