Flow-rate measurement apparatus
View Patent ↗A plate-shaped board is arranged so that fluid passages are respectively formed at a sensor-element mounting surface side of the plate-shaped board and at a backside surface side thereof being opposed to the sensor-element mounting surface side, a curved passage portion is provided which is located upstream of the plate-shaped board and 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 sidewall surface, facing the sensor-element mounting 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 sidewall surface opposed to the first sidewall surface, along the sidewall surfaces.
1. 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.
2. The flow-rate measurement apparatus according to claim 1 , wherein the outer-side wall surface has a linear shape and is formed so as to slope towards the inner-side wall surface.
3. The flow-rate measurement apparatus according to claim 1 , wherein the outer-side wall surface has a circular-arc shape and is formed so as to slope towards the inner-side wall surface.
4. The flow-rate measurement apparatus according to claim 1 , wherein the outer-side wall surface has a polygonal shape and is formed so as to slope towards the inner-side wall surface.
5. The flow-rate measurement apparatus according to claim 1 ,
wherein the curved passage portion is formed by stacking two members together in the direction perpendicular to the board surfaces of the plate-shaped board,
the outer-side wall surface is formed by outer-side wall surface portions formed respectively in the two members, and
the sloping portion is formed by the outer-side wall surface portion formed in one of the two members which forms the first sidewall surface facing the sensor-element mounting surface in the direction perpendicular to the board surfaces of the plate-shaped board.
6. The flow-rate measurement apparatus according to claim 5 , wherein the sloping portion is formed also in the outer-side wall surface portion formed in a second one of the two members which forms the second sidewall surface located on the opposite side to the side facing the sensor-element mounting surface.
7. The flow-rate measurement apparatus according to claim 1 ,
wherein the sub-passage includes:
a first sub-passage portion which changes its direction so as to form a curved line;
a third sub-passage portion which changes its direction so as to form a curved line, the first and third sub-passage portions provided in a layered manner so as not to intersect each other; and
a second sub-passage portion which has a linear shape and in which the plate-shaped board is placed,
a curved passage portion which changes its direction so as to form a curved line is provided in a communicating passage portion between the first and second sub-passage portions, and
the sloping portion is formed in the curved passage portion.
8. The flow-rate measurement apparatus according to claim 7 ,
wherein the plate-shaped board is placed in parallel with a direction of the flow of the fluid in the second sub-passage portion, and
the fluid passage located on the sensor-element mounting surface side has a cross-sectional area that is smaller than a cross-sectional area of the fluid passage located on the backside surface side.
9. The flow-rate measurement apparatus according to claim 1 ,
wherein the sub-passage includes:
a first sub-passage portion that includes an inlet portion for the fluid;
a second sub-passage portion in which the plate-shaped board is provided; and
a curved passage portion which changes its direction so as to form a curved line and connects the first sub-passage portion and the second sub-passage portion to each other, and
the sloping portion is formed in the curved passage portion.