Abstract: Provided is a gas sensor including a housing made of metal through which a sensor element is inserted and an outer cylinder made of metal welded to an outer periphery of the housing, in which generation of pinholes on a surface of a welded portion is suppressed. In a gas sensor according to one aspect of the present invention, a contact distance Lg, which is a length in an axial direction of an outer peripheral surface of a housing in contact with an inner peripheral surface of an outer cylinder on a rear end side with respect to a molten portion of the outer cylinder formed by welding, is equal to or less than a reference distance Lr.

Abstract: A linear direct current motor that is able to maintain thrust at a constant level at all times regardless of changes in the relative positions of the primary and secondary sides. The motor includes a magnetic pole detection magnet having a number of magnetic poles one greater than that of a field magnet, and magnetic pole discrimination elements in the form of Hall effect elements that are acted on by the magnetic pole detection magnet.