Patent ID: 8347706

Claim:
A flow-rate measurement apparatus comprising: a main passage; a sub-passage configured to take part of a fluid flowing through the main passage; and a plate-shaped board having a sensor element for measuring a mass of the fluid, which is mounted on a sensor-element mounting surface side thereof, wherein the plate-shaped board is arranged in a portion of the sub-passage so that fluid passages are respectively formed at the sensor-element mounting surface side and a backside surface side of the plate-shaped board, the backside surface side being the opposite side of the plate-shaped board to the sensor-element mounting surface side, the sub-passage includes a curved passage portion which is located upstream of the plate-shaped board and which changes its direction so as to form a curved line, and the curved passage portion has an outer-side wall surface including a sloping portion that slopes so that, of two edge portions of the outer-side wall surface in a direction perpendicular to board surfaces of the plate-shaped board, the edge portion located on a first sidewall surface of the curved passage portion is positioned closer to an inner wall surface of the curved passage portion than the edge portion located on a second sidewall surface opposed to the first sidewall surface, along the sidewall surfaces, the first sidewall surface facing the sensor-element mounting surface, the second sidewall surface opposed to the first sidewall surface.