Patent ID: 7654134
Filing Date: 2010-02-02
Classification: G01F

Abstract:
1. An air flow measuring device for measuring a flow amount of air flowing in an interior of a duct, the air flow measuring device comprising: a first sub-passage portion configured to introduce therein a part of air flowing in the duct; a throttle portion provided in the first sub-passage portion to gradually reduce a passage sectional area of the first sub-passage portion as toward an outlet of the first sub-passage portion; a second sub-passage portion branched from the first sub-passage portion at an upstream side of the throttle portion in a flow direction of air flowing in the first sub-passage portion, the second sub-passage portion being configured to introduce therein a part of air flowing in the first sub-passage portion; and a flow amount sensor located in the second sub-passage portion to measure a flow amount of air flowing in the second sub-passage portion, wherein: the second sub-passage portion has an inlet at which the second sub-passage portion is branched from the first sub-passage portion; the inlet of the second sub-passage portion is open into the first sub-passage portion at one side in a first radial direction that is perpendicular to a flow direction of air flowing in the first sub-passage portion; the throttle portion is provided to gradually reduce a passage dimension of the first sub-passage portion in a second radial direction, as toward the outlet of the first sub-passage portion, the second radial direction being perpendicular to a first plane extending in the first radial direction and extending in the flow direction of air flowing in the first sub-passage portion; the throttle portion is provided solely along a downstream side portion in the first sub-passage portion, downstream of the opening of the inlet of the second sub-passage portion; and the first sub-passage portion has a substantially constant passage dimension in the first radial direction along the downstream side portion to the outlet of the first sub-passage portion.