Magnetic sensor that concentrates magnetic flux in an air gap

Magnetic sensor of the position of a movable member over a trajectory followed by said movable member, comprising first (1) and second (2, 2′) members movable relative to each other, one of the members being secured to said movable member and the other fixed, said fixed member (1) defining a circuit of ferromagnetic material having at least one air gap (4) provided with a sensor (5) delivering a signal representative of the magnetic induction prevailing in said air gap (4), said second member (2, 2′) comprising a permanent magnet in magnetic coupling relation with said first member (1) to close said magnetic circuit, the sensor moreover comprising means (6) supplied with said signal to derive from it a measurement of said position, wherein said first member (1) comprises a tubular portion (1a) and a portion in the form of a rod (1b) extending along the axis (X) of said tubular portion (1a), said portions being magnetically coupled, at one end, by said second member (2, 2′) of which said permanent magnet (2, 2′a) has a radial magnetization and, at the other end, by means (1c) for concentrating magnetic flux in said air gap (4), this latter being delimited by said concentration means (1c) and the facing end of the rod-shaped portion (1b) of said first member (1).