Optical Valve Position Sensing with a Non-Repeating Code Plate
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Solution Overview
Problem
Existing micro-mechanical position sensors for valves are bulky, unreliable, and prone to mechanical wear, with optical absolute rotary encoders being complex and large, making them unsuitable for accurate and compact position determination.
Innovation Solution
A rotatable code plate with a non-repeating angle-dependent pattern and an optical detector module that processes time-varying signals to determine the absolute position of a valve, allowing for compact and accurate position sensing without the need for additional sensors or complex encoder designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If micro-mechanical position sensors are used to determine valve rotational position, then position feedback can be provided to the controller, but the sensors become bulky and unreliable due to mechanical wear and spurious signals from vibrations
Solution Approach 1:
The patent replaces mechanical micro-mechanical switches with an optical detection system. A code plate with optical patterns is read by optical detectors (photodetectors) to determine valve position, eliminating mechanical contact and associated wear, vibrations, and spurious signals while maintaining position feedback functionality.
Solution Approach 2:
The patent uses optical patterns on a code plate that represent positional information without requiring physical mechanical switches. The optical code plate creates a visual copy of position data that can be read remotely by optical detectors, avoiding direct mechanical interaction and improving reliability.
2Measurement precision
If optical absolute rotary encoders with photo detector arrays are used to determine shaft position, then high measurement precision can be achieved, but the encoders become complex and relatively large
Solution Approach 1:
The code plate is divided into multiple concentric circular arcs, each containing sectoral elements with optical patterns. Each arc provides positional information for a specific angular range, allowing the system to achieve high measurement precision through segmented optical coding rather than requiring a complex complete encoder system.
Solution Approach 2:
Different regions of the code plate have different optical patterns optimized for their specific angular ranges. Each sectoral element contains patterns tailored to its local angular position, enabling precise local measurement while keeping the overall device simpler than a uniform high-resolution encoder would require.
3Device complexity
If a non-repeating angle-dependent pattern with identical sectoral elements in non-adjacent sectors is used on the code plate, then a compact rotary encoder can be designed, but the pattern must be carefully designed to ensure non-repetition over a full rotation
Solution Approach 1:
The code plate uses a non-repeating asymmetric pattern where identical sectoral elements are placed in non-adjacent sectors with specific angular relationships. This asymmetric arrangement ensures that the optical pattern does not repeat over a full rotation, providing unique positional information while maintaining a simpler structure than traditional encoders.
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
Enables precise and efficient determination of valve positions using a simpler and more compact position sensor system, reducing mechanical wear and electromagnetic interference, while maintaining high accuracy and angular resolution.
Implementation Method 1
each optical detector is aligned with a respective arc of said set of one or more concentric circular arcs around the rotatable code plate and is configured to receive light passing through a void of the code plate when the code plate is in any of a first set of angular positions and to be blocked by the code plate from receiving light through the code plate when the code plate is in any of a second set of angular positions
Data Source
AI summary
A rotary encoder for a valve comprises a rotatable code plate and an optical detector module comprising one or more optical detectors. The code plate defines a set of voids arranged along a set of one or more concentric circular arcs about an axis of rotation. The voids define an angle-dependent pattern over the set of arcs, the pattern comprising a plurality of distinct sectoral elements (A-O, X). At least two of the sectoral elements, located in non-adjacent sectors of the code plate, are identical, but the pattern is non-repeating over a single full rotation of the code plate about the axis. Each optical detector is aligned with a respective concentric circular arc of the code plate. A controller processes time-varying output signals from the optical detectors to determine successive positions of the rotatable code plate.