PCB Flat-Coil Valve Rod Position Sensing for Long Stroke Valves
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Solution Overview
Problem
Existing position sensors for control valves are not suitable for different stroke lengths, especially large ones, and are not designed for low-energy applications, lacking cost-effectiveness and precision in harsh environmental conditions.
Innovation Solution
A position sensor for control valves with a magnetically or electrically conductive pointer coupled to the valve stem, featuring modules with identical flat coils on printed circuit boards, arranged equidistantly and overlapping to ensure continuous signal measurement, protected by a housing and using a transducer for precise position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic or optical stroke measurement methods are used with patterns extending over the entire stroke range or multiple sensors, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The measurement system is divided into multiple identical modules, each containing a limited number of flat coils (e.g., two coils per module). These modules are connected in series along the stroke direction, allowing the valve stem to be measured across the entire stroke range without requiring a single complex sensor assembly. Each module can be independently manufactured and replaced, simplifying the overall system complexity while maintaining continuous measurement capability.
Solution Approach 2:
The flat coils are designed with universal functionality to serve multiple purposes: they act as both measurement sensors and positioning references. The same coil structure is used throughout the entire stroke range, eliminating the need for different sensor types or complex pattern variations. This universal design reduces manufacturing complexity while maintaining measurement precision across the full valve stroke.
2Length of moving object
If multiple sensors or long-pattern sensors are used to cover large stroke lengths, then measurement range is improved, but manufacturing cost increases
Solution Approach 1:
The measurement system is divided into multiple identical modules, each containing a limited number of flat coils (e.g., two coils per module). These modules are connected in series along the stroke direction, allowing the valve stem to be measured across the entire stroke range without requiring a single complex sensor assembly. Each module can be independently manufactured and replaced, simplifying the overall system complexity while maintaining continuous measurement capability.
Solution Approach 2:
The system achieves variable stroke length adaptability by changing the number of modules connected in series rather than redesigning the entire sensor. The same standardized module design can be used for different valve sizes by simply adjusting the quantity of modules, making the system scalable and cost-effective for various stroke lengths from small to large valves.
3Measurement precision
If traditional coil arrangements are used, then measurement capability is achieved, but energy consumption increases
Solution Approach 1:
The flat coils are supplied with alternating current in a periodic manner, where only the currently active module's coils are energized while other modules remain unenergized. This periodic activation pattern significantly reduces overall energy consumption compared to continuously energizing all coils across the entire stroke range, while still maintaining the ability to measure position at any point along the valve stem's travel.
4Reliability
If non-contact measurement methods are used to withstand harsh environmental conditions, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The flat coils are embedded in printed circuit boards that serve as intermediary mounting structures within the valve stem assembly. These PCBs provide mechanical support and precise positioning for the coils, eliminating the need for complex alignment procedures during installation. The PCBs act as mediators between the measurement system and the valve stem, ensuring consistent spacing and alignment while protecting the sensitive measurement components from harsh environmental conditions.
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 sensor provides accurate position detection across varying stroke lengths with low energy consumption, reduced manufacturing costs, and resistance to environmental influences, ensuring consistent signal measurement without interruptions.
Implementation Method 1
coil arrangements are used as sensor elements, which are traversed by metallic elements and either detect a change in flux by means of induction or measure frequency changes
Implementation Method 2
the valve stem with a position sensor for determining the position of the valve stem of a control valve is proposed. This sensor has a pointer that is coupled to the valve stem in such a way that it is carried along by the stem as it moves. The pointer is made of a magnetically and/or electrically conductive material
Data Source
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AI summary
The invention relates to a position sensor for determining the position of a valve rod (230) of a control valve (200), comprising a pointer (240), which is made of a magnetically and/or electrically conductive material and which is carried along during a movement of the valve rod (200), and at least one module (250) made of a printed circuit board with at least one printed flat coil (260, 265, 270). The pointer (240) passes over the at least one flat coil (260, 265, 270) in a contactless manner when the valve rod (230) moves. The position sensor additionally comprises a measuring transducer which measures a signal on the at least one flat coil (260, 265, 270) that allows the relative position between the pointer (240) and the flat coil (260, 265, 270) to be inferred. Such a position sensor for control valves (200) is very inexpensive to produce and requires little energy by virtue of the short distance over which the pointer (240) passes over the at least one module (250).