Diaphragm Valve Control Using Selectable Correction Curves
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Solution Overview
Problem
Diaphragm valves are typically used as control valves only in exceptional cases due to their extremely non-linear valve characteristic lines, making it difficult or impossible to control processes effectively, and adjusting these lines requires significant effort and leads to operational interruptions.
Innovation Solution
A diaphragm control valve system that includes a valve housing, diaphragm, actuator, and a valve control with a correction element allowing selection of predefined correction characteristic lines to modify the diaphragm valve characteristic line, enabling linear or equal-percentage control characteristics without structural changes to the diaphragm, using a process controller to determine and correct position set values based on actual process values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a diaphragm valve is used as a control valve with its original non-linear valve characteristic line, then the valve structure is simple and requires no structural changes, but the control performance is poor and process control becomes difficult or impossible
Solution Approach 1:
The patent applies parameter changes by modifying the valve characteristic line through a correction element that transforms the originally non-linear diaphragm valve characteristic into a linear or equal-percentage characteristic. This is achieved by introducing a correction function that adjusts the relationship between actuator position and valve opening, thereby improving control performance without changing the basic valve structure
Solution Approach 2:
The patent introduces a correction element as an intermediary component between the actuator and the diaphragm valve. This correction element acts as a mediator that processes the control signal and applies the necessary correction to achieve the desired linear or equal-percentage characteristic, resolving the contradiction between structural simplicity and control performance
2Reliability
If the diaphragm shape is modified to adjust the valve characteristic line to linear or equal-percentage, then the control performance is improved, but the manufacturing complexity and operational interruptions increase due to diaphragm replacement requirements
Solution Approach 1:
Instead of modifying the diaphragm structure directly, the patent introduces a correction element as an intermediary that handles the characteristic line adjustment. This approach maintains the simplicity of the original diaphragm design while achieving the desired control performance through the correction element's transformation function
Solution Approach 2:
The patent replaces the mechanical approach of shaping the diaphragm to achieve linear or equal-percentage characteristics with a functional correction approach. The correction element substitutes for complex diaphragm geometry by applying mathematical or functional transformation to the control signal, thereby achieving the same effect without mechanical complexity
3Reliability
If the diaphragm is replaced to change the valve characteristic line, then the control performance is improved, but the operational interruptions and maintenance costs increase significantly
Solution Approach 1:
The patent implements preliminary action by pre-configuring the correction element with the necessary correction functions for linear or equal-percentage characteristics. This allows the valve to achieve improved control performance without requiring physical replacement of the diaphragm during operation, thereby eliminating operational interruptions and maintenance costs associated with diaphragm changes
4Reliability
If a special type of diaphragm valve with shaped diaphragm is used to achieve linear or equal-percentage characteristic, then the control performance is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies segmentation by separating the functions of the diaphragm (flow control) from the function of characteristic line adjustment (correction element). This segmentation allows each component to remain simple while the system as a whole achieves the desired control performance, avoiding the need for complex shaped diaphragms
Data Source
AI summary
A diaphragm control valve includes a diaphragm valve and a valve control. The diaphragm valve includes a valve housing having a flow channel, a diaphragm, and an actuator. The valve control comprises an actuating element. The valve control comprises a correction element and provides a plurality of predefined correction characteristic lines. The valve control is arranged such that a user can select one of the correction characteristic lines, and the correction element along with the selected correction characteristic line determines a corrected position set value from a preset position set value. The actuating element is configured to determine a manipulated variable from the corrected position set value and to control the actuator using the manipulated variable such that the diaphragm control valve has a predetermined diaphragm control valve characteristic line.