Anti-Backlash Valve Positioner via Magnetic Coupling
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Solution Overview
Problem
Existing valve positioners face limitations due to mechanical backlash and the need for a clutch, which often require penetration of the sealed interface enclosure, increasing maintenance and risk of leakage and corrosion in harsh environments.
Innovation Solution
A valve positioner design incorporating a magnetically coupled coupler shaft with a concentrically arranged torsion spring and clutch ring, allowing for anti-backlash and clutch functionality without penetrating the sealed enclosure, using a magnetic field sensor to detect rotation and a frictional clutch to suppress backlash and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a friction clutch is interposed between the valve coupler and the sensor to allow for misalignment and tensioning adjustment, then the adaptability and ease of operation are improved, but the device complexity increases due to additional mechanical components
Solution Approach 1:
The patent places the clutch ring and torsion spring inside the sealed enclosure, nesting them within the existing valve positioner structure. The magnet is mounted on the coupler shaft outside the enclosure, while the sensor remains inside, creating a nested arrangement where the magnetic coupling transmits motion through the enclosure wall without physical penetration.
Solution Approach 2:
The patent replaces direct mechanical coupling (which would require penetration of the sealed enclosure) with magnetic coupling. The magnet mounted on the coupler shaft interacts with the sensor through the enclosure wall, eliminating the need for mechanical penetration while maintaining motion transmission.
2Ease of manufacture
If the valve coupler penetrates the sealed interface enclosure to connect the sensor, then the ease of manufacture and device simplicity are improved, but the reliability decreases due to increased risk of leakage and corrosion in harsh environments
Solution Approach 1:
The patent replaces mechanical penetration of the enclosure wall with magnetic field coupling. The magnet on the coupler shaft interacts with the sensor through the sealed enclosure wall, eliminating physical penetration points that would compromise the seal and allow ingress of harsh environmental conditions.
Solution Approach 2:
The sealed enclosure wall acts as an intermediary that transmits the magnetic field from the magnet on the coupler shaft to the sensor inside the enclosure, without requiring physical penetration. This maintains the protective barrier while enabling functional coupling.
3Reliability
If a magnetic field sensor is used to detect rotation without penetrating the enclosure, then the reliability of the sealed environment is improved, but the measurement precision may be affected by the enclosure wall interference
Solution Approach 1:
The patent uses magnetic field coupling instead of direct mechanical coupling, allowing the sensor to detect rotation through the sealed enclosure wall without physical penetration. This maintains the integrity of the sealed environment while enabling accurate rotation detection via magnetic field interaction.
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 design enhances accuracy and reliability by eliminating mechanical backlash and vibration while maintaining a sealed environment, reducing maintenance needs and preventing environmental hazards, and allows for compact integration within existing space constraints.
Implementation Method 1
A magnet on the coupler shaft is located proximal to a wall of the enclosure, so rotation of the magnet by the shaft can be sensed by a magnetic field sensor
Implementation Method 2
A torsion spring is surrounded by and concentric with the clutch ring, the torsion spring having a first end fixed to the coupler shaft and a second end fixed to the clutch ring
Implementation Method 3
a frictional clutch to suppress backlash and vibration
Data Source
AI summary
A valve positioner monitors a valve stem position by remotely sensing a magnet attached to a coupler shaft that does not penetrate a sealed enclosure surrounding the positioner. A torsion spring, which can be helical or spiral, concentrically surrounds the shaft and is fixed to the shaft and frictionally coupled to a fixed surface by a clutch ring that coaxially surrounds the spring and is vertically pressed against the fixed surface. The torsion spring thereby suppresses backlash, vibration, and chatter by maintaining a torsional force on the shaft. The clutch ring can include a notch or slot cooperative with a key tab rotationally fixed to the coupler shaft so as to limit a range of rotation of the coupler shaft. The positioner is rendered compact by the concentric arrangement of its elements, so that embodiments can be used in place of legacy positioners.