Patents by Inventor Tsutomu Akita

Tsutomu Akita 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).

  • Lubricating oil composition containing a partial ester of a polyhydric alcohol and a substituted succinic acid ester
    Patent number: 5273672
    Abstract: The present invention provides a lubricating oil composition characterized in that the base oil contains (A) from 0.05 to 5% by weight of an ester of alkenyl substituted succinic acid and/or an ester of alkyl substituted succinic acid and (B) from 0.005 to 5% by weight of a fatty acid ester of a polyhydric alcohol. The lubricating oil composition of the present invention has a friction characteristic in which the (coefficient of static friction)/(coefficient of dynamic friction) ratio is small and gives only a small shock by shift change. In addition, the changes in the friction characteristics depending on the oil temperature is small and also the changes in the lapse of time are small. Accordingly, it is fully compatible with the trend toward a compact size of transmissions and the like.
    Type: Grant
    Filed: April 8, 1991
    Date of Patent: December 28, 1993
    Assignee: Idemitsu Kosan Company Limited
    Inventors: Masashi Dasai, Tsutomu Akita, Masaharu Sasaki