Air flow measuring device

Abstract

An air flow measuring device is adapted to be attached to a duct. The device includes a first housing, a second housing, and a flow sensor. The first housing defines a bypass flow passage which takes in a part of air flowing in the duct, and includes a hollow part and a recess. The bypass flow passage is formed in the hollow part. The recess is formed on an upper side of the hollow part in a vertical direction of the device, and at the recess, an outer surface of the first housing is recessed inward of the first housing. The second housing is formed through secondary formation with the first housing as a primary formed part. The first housing is held on a lower side of the second housing in the vertical direction. The flow sensor is disposed in the bypass flow passage.

1 . An air flow measuring device adapted to be attached to a duct, the device comprising:
 a first housing that defines a bypass flow passage which takes in a part of air flowing in the duct and that includes:
 a hollow part in which the bypass flow passage is formed; and 
 a recess which is formed on an upper side of the hollow part in a vertical direction of the device and at which an outer surface of the first housing is recessed inward of the first housing; 
   a second housing that is formed through secondary formation with the first housing as a primary formed part, wherein the first housing is held on a lower side of the second housing in the vertical direction; and   a flow sensor that is disposed in the bypass flow passage.   
     
     
         2 . The air flow measuring device according to  claim 1 , wherein the recess is configured as a circumferential groove that is formed continuously along an entire periphery of the outer surface of the first housing. 
     
     
         3 . The air flow measuring device according to  claim 1 , wherein:
 the recess includes side surfaces on its both sides in the vertical direction;   a die is used in a process of the secondary formation; and   one of the side surfaces of the recess located on the second housing-side serves as a die cramp surface as a result of insertion of a part of the die into the recess at time of the formation of the second housing.