Gas sensor

摘要

There is disclosed a gas sensor having a multiple protector structure and providing uniform response or output characteristic irrespective of the direction of the gas stream relative to the protector. This protector has a first cylindrical portion (6b), and a second cylindrical portion (6a) having a sidewall. The front end of the second cylindrical portion protrudes beyond the front end ofthe first cylindrical portion. Second side gas inlets are formed in the sidewall to introduce gas under measurement. The first cylindrical portion (6b) has a tapering portion (62) having a base end and a front end. The introduced gas flows along the outer surface of the tapering portion of the first cylindrical portion from the base end toward the front end and flows out from a second side gas outlet (64). A first side gas outlet (62) is formed at the front end of the tapering portion. The stream of the gas flowing in this way produces a negative pressure in the first side gas outlet, evacuating the inside of the first cylindrical portion. As a result, the gas is drawn into the first cylindrical portion almost isotropically from the circumferentially spaced first side gas inlets. The gas is supplied to a detection portion inside the protector almost isotropically irrespective of the angle at which the gas stream strikes the surface of the detection portion. Accordingly, uniform response or output characteristic is obtained regardless of the direction of the gas stream. <IMAGE>