Pneumatic executor for driving valve

Abstract

The invention relates to a pneumatic executor for driving a valve, which comprises a cylinder body, a piston arranged in the cylinder body, a limit mechanism of the piston, end covers arranged at two ends of the cylinder body, a transmission mechanism for connecting the piston and an executor shaft driven by the transmission mechanism, wherein the cylinder body is separated into an inner cavity and an outer cavity by the piston, and the inner cavity and the outer cavity are connected with an air source control valve through an air passage. The pneumatic executor is characterized in that the wall of the inner cavity is provided with a vent hole communicated with the atmosphere, a gap is reserved between the hole position of the inner cavity and the limit position of the piston stroke, the area of the hole is not less than 50 percent of the area of the piston, preferably over 1 percent of the area of the piston, and a control valve is arranged outside the vent hole. The opening-closing of the vent hole control valve and linked control of air connection and disconnection of the inner and outer cavities can realize quick communication among the inner and outer cavities, the air source and the atmosphere so as to quickly open and close a butterfly valve and a ball valve according to a set motion order. The pneumatic executor can be widely applied to a driving process of various valves with large calibers of over 200 millimeters.

Description

technical field

[0001] The invention relates to a pneumatic actuator for a valve, in particular to a pneumatic actuator capable of driving a valve with a diameter of more than 200 mm. Background technique

[0002] The existing pneumatic actuators in the market for driving valves such as butterfly valves and ball valves generally have a cylinder-piston structure, which uses gas pressure to drive the piston to make a linear motion in the cylinder, and then uses gears, racks, shift forks, linkages and other structures to move the piston. Motion is the rotation of the actuator shaft. The actuator shaft then outputs power to the valve stem through the coupling, thereby driving the valve to rotate. In order to make the actuator shaft only bear the torque but not the bending moment, there are generally two relatively moving pistons in the pneumatic actuator, which drive the actuator shaft symmetrically. These two pistons divide the cylinder into two outer cavities and one inner c...

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