CUTOFF VALVE Russian patent published in 2013 - IPC F16K17/22 

FIELD: machine building.

SUBSTANCE: cutoff valve includes a body with adjacent chambers, an inlet opening and an outlet opening, which are interconnected with pipelines. Two chambers are interconnected with each other. The first movable piston is arranged inside the third chamber. The second adjacent chamber is made in the form of a cavity and a pressure channel, which are interconnected with each other. The pressure channel is connected to a pressure pipeline. The first movable piston is equipped with the second stock. End surface of the second stock and the cutoff valve body form the first control cavity of variable volume. The first movable piston is installed with a gap to connect the above-piston and below-piston cavities of the third chamber to each other. Below-piston cavity of the third chamber is interconnected with a return channel. The first movable piston in one of its extreme positions disconnects the below-piston cavity of the third chamber from the return channel. Cutoff valve is equipped with the second body, in which inlet and outlet openings, inlet and outlet channels, the chamber separated with the second movable piston into inlet and outlet cavities, are made. The latter are connected to inlet and outlet channels respectively. The inlet opening of the second body is interconnected with the controlled pipeline and with the above inlet channel. The outlet opening of the second body is interconnected with the outlet channel. The second movable piston is equipped with two stocks and installed with a gap attaching the inlet and outlet cavities of the chamber of the second body. The first and the second movable pistons have similar shape and dimensions. Diameters of stocks of the second movable piston are equal to diameters of stocks of the first movable piston. The first stock of the second movable piston is provided with a backward displacement limit stop, the end surface of which is adjacent to adjustable spring. That spring is adjacent to the mounting surface of an adjustment bolt connected to the second cutoff valve body by means of a threaded connection. End surface of the second stock of the second movable piston and the second body of cutoff valve form the second control cavity of variable volume, which is interconnected in series through a feedback line and a throttle channel with the first control cavity of variable volume. A drain hole and a drain channel are made in the cutoff valve body. Cavity of the second adjacent chamber is combined with above-piston cavity of the third chamber. Return channel is interconnected with the outlet opening of the cutoff valve body and the controlled pipeline. Each movable piston is equipped with two conical surfaces and at least one cylindrical surface. The first stock of the first movable piston is provided with radial and axial channels interconnected with each other. Axial channel is interconnected with the first adjacent chamber of the cutoff valve body. Radial channel is interconnected with the second adjacent chamber of the cutoff valve body in one of the extreme positions of the first movable piston. The first adjacent chamber is interconnected with the drain channel and the drain opening.

EFFECT: improvement of cutoff valve operating reliability.

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