Principle: electrified, the electromagnetic force to open the pilot hole, the pressure of the upper chamber rapidly drops, the formation of the upper low high pressure around the closed parts, fluid pressure to promote the closing parts move up, the valve is opened; Power, the spring force to close the pilot hole, the inlet pressure through the bypass hole rapid chamber in the valve parts around the formation of low on high pressure difference, fluid pressure to promote the closure of the parts to move down, close the valve.
