Rotary Valve Position Control from an Indeterminate Start State
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Solution Overview
Problem
Existing valve control systems face challenges in determining the rotational position of a valve closure element, especially when it is in a partially open state, making it difficult to accurately control fluid flow and risk the valve falling into an indeterminant state during initialization or operation.
Innovation Solution
A valve control system that includes a rotatable valve coupled to a motor, a valve position indicator, and at least two sensing devices (home position and end-of-travel sensing devices) with a controller using logic to monitor and determine the valve's state based on the status of these indicators, preventing over-travel and ensuring accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sensor is used to detect valve position, then the device complexity is reduced, but the reliability of determining valve state is insufficient
Solution Approach 1:
The patent applies local quality by placing sensors at specific critical locations (home position and end-of-travel position) rather than uniformly distributing sensors throughout the valve range. This targeted placement provides reliable state determination at key positions while avoiding unnecessary complexity in other areas.
Solution Approach 2:
The patent segments the valve travel range into distinct zones by using multiple sensors at different positions (home position sensor and end-of-travel sensor). This segmentation allows the system to determine valve state by checking which zone the valve is in, improving reliability without requiring a continuous complex sensing system.
2Ease of operation
If the valve operates without hard mechanical stops, then the ease of operation is improved, but the reliability of preventing over-travel is reduced
Solution Approach 1:
The patent implements feedback by using sensors to detect when the valve reaches home or end-of-travel positions and sending signals back to the control system. The controller uses this feedback to prevent further movement in the same direction, providing reliable over-travel prevention without mechanical stops and maintaining operational flexibility.
Solution Approach 2:
The patent replaces hard mechanical stops with an electrical/control system consisting of sensors and a controller. This substitution removes mechanical constraints while providing equivalent protection through electronic feedback, improving ease of operation while maintaining reliability.
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
The system effectively determines the current state of the valve, reduces the risk of indeterminant states, and allows precise control of the valve to the home or end positions, preventing mechanical errors such as springing or misalignment.
Implementation Method 1
The at least two sensing devices include a home position sensing device and an end-of-travel position sensing device. The home position sensing device is a Hall effect device, and the end-of-travel position sensing device is a Hall effect device.
Data Source
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AI summary
A valve control system includes a rotatable valve (110) operably coupled to a motor (102), a valve position indicator (108) configured to rotate with the rotatable valve, at least two sensing devices configured to detect the valve position indicator, and a controller. The at least two sensing devices include a home position sensing device (116A) and an end-of-travel position sensing device (116B). The controller (120) includes valve state determination logic having circuitry configured to monitor a status of a home indicator and an end-of-travel indicator of the rotatable valve, determine a commanded direction of movement of the rotatable valve, monitor the status of the home indicator and the end-of-travel indicator before a valve rotation stop is commanded and after the valve rotation stop is commanded, and determine a current state of the rotatable valve based on the commanded direction of movement and at least one of the status of the home indicator and the end-of-travel indicator.