Patent ID: 6244562
Filing Date: 2001-06-12
Classification: F16K

Abstract:
A multistage switching valve comprising;a valve stem which is adapted to open or close a fluid passage,a biasing means for biasing the valve stem in a direction to close the fluid passage,a plurality of pistons which are relatively slidably fitted onto the valve stem at different axial positions to provide different flow rates,a plurality of stops which are provided on the valve stem to move the valve stem in a valve opening direction opposite to the direction of the movement of the valve stem caused by the biasing means, together with the pistons when the pistons are moved in the valve opening direction,a valve opening means for selectively exerting a pilot pressure in the valve opening direction on each piston, anda flow rate control means for individually restricting the axial displacements of the pistons in the valve opening direction.