Patent ID: 6915688

Claim:
A gas-flow measuring instrument comprising: a main passage having an intake gas passage for sucking gas; a bypass passage into which part of gas flowing through the main passage flows; a flow measuring element disposed within the bypass passage for sensing a gas flow; and an electronic circuit electrically connected to the flow measuring element, wherein the bypass passage comprises a bypass-passage inlet opened to an upstream side in a gas mainstream direction of the intake gas passage, a first passage arranged from the upstream-side of the intake gas passage to the downstream side and inclined relative to the mainstream direction, a second passage arranged from the downstream-side to the upstream side and having the flow measuring element arranged therein, a third passage connecting the first passage to the second passage in the downstream-side of the mainstream direction, and a bypass-passage outlet arranged in the second passage and said third passage includes a curve portion to change a flow direction of said intake gas in said bypass passage to flow said intake gas upstream with respect to said mainstream direction.