Mechanical System Design Of A Smart Valve Positioner

Smart valve positioner is the key accessory of the control valve. The valve flow characteristics, the control speed, the reliability and the control accuracy could be effectively improved by using smart valve positioner. The control accuracy of a smart valve positioner is based on the accurate information of valve position, which is realized by a precise mechanism for valve feedback. In order to get rid of the patent protection of foreign valve position feedback mechanism, it is necessary to develop a new mechanical system of smart valve.Try to achieve the purpose above, this paper carries out the following studies:(1) Design of feedback mechanism for valve position with fixed strokeThe design scheme for a new fixed-stroke valve position feedback mechanism has been proposed. By application of mechanism optimization design theory, mathematical modeling is carried out on the valve position feedback mechanism, by selecting the rod length and offset distance as design variables, while choosing the maximum transmission angle as objective function; the relationship between the displacement of the valve stem and rotation of the feedback shaft is obtained, and the motion error is analyzed.(2) Design of feedback Mechanism for valve position with variable strokeIn term of the valve position feedback mechanism with fixed stroke, a new variable stroke valve position feedback mechanism is designed; and its kinematics simulation on variable stroke valve position feedback mechanism is carried on by the ADAMS. The relationship between the displacement of the valve stem and rotation of the feedback shaft is simulated and analyzed. Simulation results show that the design requirements have been met.(3) Molding of mechanical systems in smart valve positionerMechanical systems of smart valve positioner are modeled by the Pro/Engineer software; including feedback mechanism for valve position with variable stroke, gear amplification mechanism, angular displacement sensor bracket. At last, all modules are assembled.The feedback mechanism for valve position proposed in this paper is simple in structure and easy to adjust, which will help reduce mechanical wear. It meets the requirements of different cylinder stroke in a certain stroke range.