Mechanical electrical valve positioner

    The mechanical electrical valve positioner is the main accessory of the regulating valve. It is usually used in conjunction with the pneumatic regulating valve. It receives the output signal of the regulator, and then uses its output signal to control the pneumatic regulating valve. When the regulating valve is actuated, the valve stem The displacement is fed back to the valve positioner through the mechanical device, and the valve position status is transmitted to the upper system through electrical signals. The disadvantage of the mechanical force balance structure is poor environmental resistance, easy to be affected by temperature and external vibration, easy to wear, time-consuming manual adjustment and need to interrupt the control loop. But because of its low price, it is still used in traditional enterprises.

    The mechanical electric valve positioner means that when the current is input into the coil, the iron core is magnetized. Under the action of the permanent magnetic field, the iron core rotates on the axis of 0. The balance spring on the lever 1 is used to adjust the initial distance between the baffle and the nozzle to ensure When there is no current in the coil, the distance between the baffle and the nozzle is at the best distance. When the input current causes the lever 2 to rotate a small angle counterclockwise, the baffle is close to the nozzle, and the pressure in the pressure chamber increases, pushing the valve stem down, driving the eccentric cam Rotate counterclockwise, push the roller to the left, pull the lever 2 to the left through the spring on the lever 2, the baffle is far away from the nozzle, the pressure in the pressure chamber is reduced, this is the negative feedback effect, to ensure the opening of the regulating valve and the input signal Proportional relationship, that is, positioning effect.