Control Valve Rod Alignment for Accurate Long-Stroke Position Sensing
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Solution Overview
Problem
Conventional control valves experience significant measurement errors due to deviations between the main extension of the actuating stem and the measuring axis, particularly with long strokes, leading to inaccurate position and displacement measurements.
Innovation Solution
A position and/or displacement measuring system with an actuating rod having a coded track aligned along its main extension direction, a measuring device with a sensing unit, and an adjusting device that orients the actuating rod parallel to the measuring axis, using magnetic or optical encoding and contact-free detection, to ensure precise alignment and minimize rotational and angular offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the control rod is aligned with typical assembly tolerances, then the mounting is easier and more practical, but measurement errors increase significantly with long strokes
Solution Approach 1:
The patent introduces an adjusting device that enables dynamic alignment of the control rod with the measuring axis. Instead of relying on fixed assembly tolerances, the system allows for real-time adjustment of the control rod's angular position, enabling precise alignment during operation while maintaining ease of mounting through the adjustment mechanism.
Solution Approach 2:
The adjusting device changes the angular parameter of the control rod's orientation relative to the measuring axis. By modifying this geometric parameter, the system transitions from a fixed misaligned state (with assembly tolerances) to an optimally aligned state, thereby improving measurement precision without compromising mounting practicality.
2Ease of manufacture
If the measuring device is mounted within typical assembly tolerances, then the installation is simpler and more practical, but large deviations between measuring axis and actuating stem occur
Solution Approach 1:
The adjusting device provides dynamic compensation for assembly tolerance deviations. Rather than requiring precise manufacturing and assembly, the system incorporates an adjustment mechanism that can dynamically correct angular misalignments between the measuring axis and the actuating stem, maintaining both installation simplicity and alignment precision.
Solution Approach 2:
The system uses the measuring device itself to provide feedback on the alignment between the control rod and measuring axis. This feedback enables the adjusting device to compensate for deviations, allowing simple installation while achieving precise alignment through active correction based on measurement data.
3Adaptability or versatility
If the control rod is allowed to twist due to process fluid torque, then the actuator can handle dynamic behavior, but the deviation from ideal linear measuring direction changes during operation
Solution Approach 1:
The measuring device continuously monitors the angular deviation of the control rod from the ideal measuring direction. This feedback information is used by the adjusting device to compensate for twists caused by process fluid torque, maintaining measurement precision even when the actuator handles dynamic behavior and rotational forces.
Solution Approach 2:
The adjusting device dynamically changes the orientation parameter of the control rod to compensate for twists. By actively adjusting the angular position in response to measured deviations, the system maintains accurate alignment between the control rod and measuring axis despite torques from process fluids that cause dynamic twisting.
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 provides highly accurate position and displacement measurements even with long strokes, minimizing measurement errors and ensuring consistent precision by maintaining the actuating rod's alignment with the measuring device, thus enhancing the reliability of control valve operations.
Implementation Method 1
using magnetic or optical encoding and contact-free detection
Implementation Method 2
using magnetic or optical encoding and contact-free detection
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The invention relates to a position and/or travel measuring system (1) for a control valve (100) for a process fluid flow of a process plant, such as a power plant, a chemical plant, a food-processing plant or the like, which comprises: a linearly moveable control rod (3) having at least one main direction of extent and at least one encoded track (33, 34) aligned along the main direction of extent; and a measuring device (5) having at least one preferably partially circular cut-out (50) for linearly moveably receiving the control rod and at least one sensing unit (53, 54) arranged on the cut-out, which sensing unit is designed and configured to detect the at least one track, preferably in a contact-free manner, wherein the position and/or travel measuring system comprises an adjusting device located in the region of the cut-out for orienting the control rod relative to the measuring device.