A NORMALLY CLOSED ELECTROMAGNETIC VALVE, A BRAKE CONTROL SYSTEM, A CONTROL METHOD FOR A NORMALLY CLOSED ELECTROMAGNETIC VALVE, AND AN ELECTROMAGNETIC VALVE

摘要

IIn a normally closed electromagnetic valve (10OA, 10OB, 100C, 100D), a rod (112,212) is supported so as to be able to move in a first direction toward a valve seat (114b) as well as in a second direction away from the valve seat (114b). This rod (112,212) closes off the hydraulic fluid path when seated on the valve seat (114b), and opens up the hydraulic fluid path when away from the valve seat (114b). When current is not being supplied to a coil (130), a first armature (116,216) pushes the rod (112,212) in the first direction using urging force of a first spring (122). When current is being supplied to the coil (130), the first armature (116,216) moves in the second direction, and the second armature (118) pushes the rod (112,212) in the first direction using electromagnetic force corresponding to the amount of the current. Further inventions are directed to a brake control system comprising such a valve, a control methode for controlling a normally closed electromagnetic valve having only one armature and an electromagnetic valve having flow resistance changing means (226,234) inside its armature.