Patent attributes
A mandrel-pulling distance sensing assembly of an electric rivet gun is mounted in a barrel of a housing and has a stationary seat, a moving seat, two magnetic elements separately fixed on the stationary seat, and a Hall effect sensor fixed on the moving seat. The moving seat is driven by a driving assembly of the electric rivet gun and is movable relative to the stationary seat. While the Hall effect sensor moves along with the moving seat between the two magnetic elements, the Hall effect sensor detects a changing magnetic field and produces and outputs a changing voltages to a control unit to allow the control unit to operate the driving assembly according to the changing voltages. Thus, the moving seat can be accurately positioned and moving ranges of a snapping device that is driven by the driving assembly can be accurately controlled.