Gas sensor suitable for engine exhaust gases

Claim 1

A gas sensor suitable for mounting in the wall of a duct through which a gas to be measured as to its composition passes, comprising a metallic casing (11) of an external configuration having a central axis and being suitable for mounting in a duct wall, a sensor element (13) being held in said casing and projecting out therefrom to the measurement gas end of the sensor, a closure shell (14), being connected to said casing and extending therefrom away from said measurement gas end and having at its end closure away from said measurement gas end of the sensor a central aperture (16) which is aligned with said axis and through which a connection conductor leads out of the interior of the closure shell, said conductor being sealed in said aperture by a seal element (41) having an axial bore through which said conductor passes, and further comprising: a metallic connection part (17) of elongated configuration, being aligned with said axis and at least partially surrounding said axis, being constituted so as to be rigid against torsion and being electrically connected to said sensor element (13) by contact with a conductor path (33) disposed on an interior surface of a solid electrolyte piece (31) thereof and extending, as a single centrally located outward leading metallic connection conductor for said sensor element, out of said casing (11) and through and out of said closure shell (14), passing through said bore of said element (41) and having a sleeve connection region (18) on a portion of said connection part protruding out of the measurement-gas-remote end of said seal element (41), a second conductor path of said sensor element being disposed on the exterior surface of said solid electrolyte piece (31); a connection cable being electrically connected and fastened axially in said sleeve connection region (18) of said connection part (17), said cable having, beyond its fastening in said region of said connection part, an insulating covering (37); a sealing tube (51), of yielding material of substantially constant wall thickness and capable of being slipped lengthwise into place, being disposed around said connection region (18) over said connection part (17) and over the adjacent insulation-covering end section of said connecting cable (19); and an overlay shell (52) having a close-fitting mid-bore (53) being forced over said sealing tube (51) so as to compress it inwardly while forcing it axially, to seal said midbore (53) and to seal the contact surface between said end of said seal element (41) and the adjacent end of said sealing tube.