Double solenoid type electromagnetic valve

摘要

A safe, double solenoid type electromagnetic valve which can be used as a single solenoid type electromagnetic valve and in which a main valve member does not change from one change-over position to another even when electric power is supplied to two pilot valves at the same time. A first piston is disposed at one end of the main valve member while second and third pistons are disposed at the opposite end. The first and second pistons have the same diameter while the third piston is smaller in diameter than the first two. Two solenoid mechanisms are provided for making a pilot fluid operate on the first piston as well as the second and third pistons. A change over device is also provided which is able to change over the operation from a first situation where the pilot fluid is allowed to operate on both the second and third pistons to a second situation wherein the pilot fluid is allowed to work only on the third piston.