Patent ID: 8863588

Claim:
A flow sensor having a flow passage through which a fluid flows, a columnar vortex generator disposed transversely to a flow direction of the fluid in the interior of the flow passage, and a sensor element disposed in the interior of the flow passage further downstream in the flow direction than the vortex generator, such that, in an event that Karman vortexes are generated by the vortex generator upon flow of the fluid, the sensor element is capable of detecting a flow rate of the fluid based on a generated frequency of the Karman vortexes, wherein: a cross section of the flow passage perpendicular to the flow direction is defined by a first wall portion and a second wall portion, which face respective opposite ends of the vortex generator in an axial direction of the vortex generator, and a third wall portion and a fourth wall portion, which face respective opposite sides of the vortex generator in a widthwise direction perpendicular to the axial direction, and which connect the first wall portion and the second wall portion; a first dimension between the third wall portion and the fourth wall portion is longer than a second dimension between the first wall portion and the second wall portion; the third wall portion and the fourth wall portion are formed in substantially straight lines along the vortex generator; and the first wall portion and the second wall portion are curved at a predetermined radius of curvature.