Patent ID: 8590368

Claim:
An airflow measuring device located at an air intake passage, which is configured to flow a mainstream of intake air therethrough toward an internal combustion engine, the airflow measuring device configured to receive a part of the mainstream and to send an electric signal according to a flow rate of the mainstream, the airflow measuring device comprising: a case having a bypass passage configured to pass received intake air therethrough; and a sensor located in the bypass passage and configured to conduct heat transfer with the received intake air to generate the electric signal, wherein the bypass passage is configured to flow a part of the mainstream therethrough and further to flow the part of the mainstream out of an outlet, as an after-bypass-passage flow, the case has an outer wall surface configured to flow a part of the mainstream therealong, without passing through the bypass passage, as an outside-passage flow, the outer wall surface of the case defines a throttle at a downstream of an opening of the outlet of the bypass passage relative to the mainstream, and the throttle is configured to merge the after-bypass-passage flow with the outside-passage flow to generate a merged flow and to guide the merged flow to a downstream of the mainstream.