Method for adjusting flow measuring device

A method for adjusting a plurality of flow measurement devices, wherein each flow measurement device includes:

• a housing including a bypass flow passage which is formed to take in part of a mainstream of air;
• a flow sensor disposed in the bypass flow passage and configured to output an electrical signal in accordance with a flow rate of air;
• and
• a writable memory, wherein:
• the bypass flow passage is formed in an asymmetrical shape with respect to the flow sensor in upstream and downstream directions of the mainstream;
• a flow from an upstream side toward a downstream side of the mainstream is a forward flow;
• and
• a flow from the downstream side toward the upstream side of the mainstream is a backward flow,
• the method comprising:
• obtaining an output in a backward-flow direction from the flow sensor in each of the flow measurement devices;
• storing the output of the flow sensor in the writable memory of the flow measuring device in each of the flow measurement devices;
• adjusting, by using a respective adjustment value stored in the writable memory of each flow measurement device, the output of each flow sensor in the backward-flow region to an adjusted output conforming to a target output on the backward-flow side, such that the flow measurement devices output the same adjusted output corresponding to a specific flow rate in the backward-flow region, wherein the adjusted output is applicable to a single conversion map that is to convert the adjusted output into a flow rate by a respective electronic control unit (ECU) and is stored in each respective ECU, wherein each ECU is provided separately from each of the flow measurement devices;
• and
• storing the adjusted output in the writable memory of each flow measurement device,
• wherein the method is implemented to reduce variation in the output of each flow measurement device with respect to each other.