Patent 7302862 was granted and assigned to Omron on December, 2007 by the United States Patent and Trademark Office.
A flow sensor 22 is provided on a wall surface of a flow path 4 in which a fluid to be measured. A member having minimal cross-section flow path 17 which has a diameter extremely smaller than that of the flow path 4 where the flow sensor 22 is provided is disposed at the downstream of the flow sensor 22.