Hall sensor-based position measuring device and electromagnetic valve

The invention relates to a Hall sensor-based position measuring device and an electromagnetic valve. The position measuring device comprises a Hall sensor, magnetic steel arranged opposite to the Hallsensor, and a magnetic conductive ring used for connecting the Hall sensor and the magnetic steel and used for magnetic conduction, a plurality of first magnetic flux pieces being correspond to the Hall sensors and the magnetic steel in a one-to-one mode and being arranged oppositely, and a plurality of second magnetic flux pieces being located between the two opposite first magnetic flux pieces.The Hall sensor and the magnetic steel abut against one ends of the corresponding first magnetic flux pieces respectively. At least one groove (151) is formed in the outer side surface of the secondmagnetic flux piece (15); the second magnetic flux piece can reciprocate along the linear direction in the direction perpendicular to the connecting line of the two first magnetic flux pieces. The position measuring device is s