Expansion valve

An expansion valve operable by a stepper motor, the expansion valve comprising:

• a housing;
• a hollow shaft arranged in the housing;
• a valve base that supports the hollow shaft and closes the housing;
• a rotor drivable by a stator of the stepper motor;
• a center spool arranged in the hollow shaft and drivable by the rotor so that a rotation of the center spool is transferrable by a threaded connection into an axial movement of the center spool that opens or closes the expansion valve;
• and
• a sleeve that includes a receiving portion that includes at least portions of the center spool, of a compression spring and of a force transmission element respectively and a valve needle,
• wherein the receiving portion of the sleeve is closed by a bushing,
• wherein the center spool is made from a first material and the bushing is at least partially made from a second material that differs from the first material,
• wherein the second material has a lower hardness than the first material, and
• wherein the second material is a sinter material.