Diaphragm Actuator Spring Assembly for Linear Valve Control
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Solution Overview
Problem
Diaphragm actuators face challenges in maintaining consistent valve positioning due to nonlinear force variations along the actuator stem's stroke, requiring high control pressures and non-linear valve movement, which can lead to undesirable positioning and increased stress on actuator components.
Innovation Solution
A diaphragm actuator with a serially operative spring assembly and movable spring seats, allowing for different effective spring rates at various stages of the actuator stem's stroke by adjusting the forces exerted by multiple springs, enabling optimized performance at both the beginning and end of the stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single spring or multiple springs are used in a diaphragm actuator, then the actuator can provide a return force to move the valve to a known position, but the force varies linearly while the valve load varies non-linearly, causing undesirable non-linear valve positioning
Solution Approach 1:
The spring assembly is segmented into multiple springs (first spring and second spring) that can be independently configured with different spring rates. This segmentation allows each spring to contribute differently to the overall force profile, enabling the combination of linear spring forces to match the non-linear valve load characteristics and achieve more linear valve positioning throughout the stroke.
Solution Approach 2:
Different springs within the assembly are assigned different local qualities (spring rates) to optimize performance at different positions. The first spring may have a higher spring rate for initial shut-off while the second spring has a lower spring rate for full stroke, creating a tailored force distribution that matches the varying load requirements at different valve positions.
2Reliability
If the spring assembly provides high force for initial shut-off, then the valve can achieve tight sealing, but excessive control pressure is required for full stroke
Solution Approach 1:
The spring assembly dynamically adapts its effective spring rate throughout the stroke. By configuring multiple springs with different rates, the system provides high force when needed for shut-off and reduces force for the remainder of the stroke, creating a dynamic force profile that matches the actual load requirements rather than maintaining a constant high force throughout.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for tailored spring rates to suit specific applications, reducing control pressure requirements and improving valve control by providing a high spring rate for initial shut-off and a lower rate for full stroke, enhancing overall actuator performance and reducing component stress.
Implementation Method 1
a spring assembly having one or more springs. The spring assembly applies a force against the diaphragm plate to return the actuator stem and a valve or other operator coupled to the stem to a known position
Data Source
Figure 1
Figure 2~3
AI summary
Apparatus to vary the effective spring rate of diaphragm actuators are described. An example spring assembly for use in a diaphragm actuator includes a first spring operatively coupled to a diaphragm plate and an actuator stem, and a second spring operatively coupled to the actuator stem and configured to be serially operative with the first spring. Additionally, a movable spring seat is disposed between the first and second springs.