Patent attributes
A sleeve has an input port, an output port, an insertion hole, and only one discharge port. A spool is axially slidable through the insertion hole to communicate among the input port, the output port, and the discharge port. An electric actuator is provided to one end of the sleeve and has a variable volume chamber, which communicates with the discharge port through an axial through hole and a spool breathing hole in the spool. The spool has a communication through hole to lead fluid from the output port to the discharge port through the axial through hole. A passage partition member is in the axial through hole to define an in-spool breathing passage communicating with the spool breathing hole.