Patent ID: 8904854
Filing Date: 2014-12-09
Classification: G01F

Abstract:
1. An air flow measurement device to be arranged in an intake passage through which intake air flows to be drawn into an internal combustion engine, the air flow measurement device being configured to introduce a part of a main flow of the intake air therein and generate an electrical signal depending on an amount of the introduced intake air, the air flow measurement device comprising a bypass passage through which the introduced intake air passes, the bypass passage accommmodating a senor which generates an electrical signal by heat transfer with the introduced intake air, wherein the bypass passage includes an inlet open toward an upstream side of the intake passage in a flow direction of the main flow of the intake air, and an outlet open toward a downstream side of the intake passage in the flow direction of the main flow of the intake air, a hole portion, through which the bypass passage communicates with the intake passage, is provided within an outlet projected area that is formed by projecting the outlet toward upstream and in straight in the flow direction of the main flow on a surface of the bypass passage, an outer wall surface of a housing having the bypass passage is exposed to intake passage, the outer wall surface includes a curved surface that protrudes outward to be curved smoothly and is tapered toward upstream in the flow direction of the main flow of the intake air, an upstream end of the curved surface communication with the hole portion without being located upstream of an inlet rim which defines the inlet, a downstream end of the curved surface is connected to an outlet rim which defines the outlet, and a correction amount of a measurement value of the sensor is determined in accordance with at least one of a position of the hole portion within the outlet projected area and an area ratio of the hole portion to the outlet projected area.