Valve, expansion valve, and stepping control method thereof

An expansion valve, comprising:

• a valve body, is hollow and has an actuation space and a containing space, a first through hole and a second through hole are respectively communicated with the actuation space being defined on the valve body, and a valve seat being arranged in the actuation space and between the first through hole and the second through hole;
• a driver, installed in the containing space;
• a valve stem, installed in the containing space and transmissively connected to the driver;
• a limiting valve, installed in the actuation space and driven by valve stem, wherein the limiting valve has a recessed space formed therein;
• a controller, configured to control the driver, and valve stem is driven by the driver to shift the limiting valve in the actuation space relatively toward the valve seat;
• and
• a heating piece, installed in the recessed space of the limiting valve;
• wherein the valve stem includes a screw and a screw sleeve, the screw sleeve is disposed in the actuation space and connected to the limiting valve, the screw is extended from the containing space toward the limiting valve into the screw sleeve and engaged with the screw sleeve;
• wherein the screw has a wire hole extending along the axial direction thereof, the heating piece is electrically connected to a wire, and the wire is electrically connected to the controller through the wire hole;
• wherein the screw has a sealing plug disposed at an end of the wire hole and the wire is surrounded the sealing plug.