Combined starting and rapid shut-off mechanism for steam and gas turbines

Claim 1

A combined starting and rapid shut-off valve for a turbine comprising: a housing (1) defining an inlet port (16) and an outlet port (37), a valve seat (43) circumscribing the outlet port (37), a flange (4) mounted relative to the housing (1) and having a flange bore (46) and a communicating flange chamber (24), a cylinder (6) having a cylinder chamber (42) centrally thereof and being carried by the flange (4) and extending inwardly therefrom and within the housing (1), a pressure medium controlled main valve (8) having a stepped main valve chamber (39) centrally thereof and said main valve being reciprocable within the cylinder chamber (42) toward and away from the valve seat (43), a spring (11) seated within the cylinder chamber (42) for urging the main valve (8) toward the valve seat (43), a spindle (10) having a through bore and carried by and projecting outwardly from the side of the main valve (8) remote from the valve seat (43) and being accommodated for radial play within the flange bore (46), a secondary valve opening (21) within the main valve (8), a main valve chamber spring (13) seated within the main valve chamber (39), the flange chamber (24) being in fluid communication with the main valve chamber (39) via the through bore of the spindle (10), a stepped secondary valve member (12) slidable in the stepped main valve chamber (39) and being biased by the main valve chamber spring (13) toward a closed position with respect to the secondary valve opening (21), the secondary valve opening (21) communicating with a piston chamber (51) in the main valve (8) and radial bores (19) through the main valve (8) when stepped secondary valve member (12) is opened and communicating only with outlet connection (37) when stepped secondary valve member (12) is closed, a pilot valve (5) mounted adjacent the flange (4) and having a pilot valve chamber with a passage to atmosphere (29), an inlet port passage (26) communicating between the pilot valve chamber and the inlet port (16), a double-acting pilot valve (28) movable within the pilot valve chamber between a first positon of blocking the passage to atmosphere (29) and a second position of closing off the inlet port passage (26), a radial central side connection (41) via the flange chamber (24) between the pilot valve chamber and the flange bore (46) wherein with the double-acting pilot valve (28) being in a first position a passage (25) leading from the interior of the housing (1) is connected to the flange bore (46) and being in a second position the flange bore (46) is vented to atmosphere, a groove (47) in the outer surface of the spindle (10) for establishing a fluid connection between the flange chamber (24) and the cylinder chamber (42) in the main valve fully-opened condition, and a valved throttling connection (48, 44) between the inlet port (16) and the cylinder chamber (42) with the cylinder chamber (42) providing a cushion against toorapid movement of the main valve (8) and with the degree of cushioning being determined by the play between the spindle (10) and the flange bore (46) and with the valved throttling connection regulating the flow of fluid to and from the cylinder chamber (42).