Rotation rate sensor

The utility model relates to a speed sensor for detecting the engine speed of motorcycle, dune buggy, kart and the electric vehicle or the vehicle speed. The speed sensor includes a shell group legislature and a magnet which is fixed in the shell. The shell group legislature comprises a shell and a bush which is inserted into the shell. The magnet is attached directly with Hall Integrate Circuit and sealed in the shell group legislature by seal ring. Wherein utilizing the concave-convex segment difference of metal piece which is rotation or movement on the motor vehicles, such as the segment difference of the top of the driven gear and the bottom of the driven gear at the end of the engine, the cutting change occurs with the magnetic line of the magnet which is fixed in the shell of the speed sensor. When the metal piece having the concave-convex segment difference, the magnet magnetic line generates the cutting change because of the difference of the high point and the low point of the concave-convex segment