Valve Shaft Torque Measurement via Direct Pressure Conversion
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Solution Overview
Problem
Current process control systems rely on indirect and approximate measurements of torque on valve shafts, which are not true mechanical values but inferred based on pressure measurements, leading to inaccuracies, especially under fast-changing conditions.
Innovation Solution
The method involves using sensors mounted directly on valve shafts to output voltage or current signals, which are converted to pressure signals via V/P or I/P converters, and then routed to an instrument controller for direct torque measurement, allowing comparison with indirect measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect pressure-based measurements are used to determine torque, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent replaces indirect pressure-based measurement with direct mechanical torque sensing by mounting a torque sensor directly on the valve shaft. This mechanical substitution enables true mechanical torque measurement instead of inferring torque from pressure readings, thereby improving measurement precision while maintaining acceptable device complexity through the use of a single integrated sensor.
2Measurement precision
If direct torque measurement with shaft-mounted sensors is implemented, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent merges the torque sensing function directly into the valve shaft structure by mounting the torque sensor on the shaft itself. This integration combines the measurement function with the existing mechanical component, avoiding the need for separate external measurement devices and thereby reducing overall device complexity while achieving direct torque measurement.
3Ease of operation
If indirect torque inference based on actuator pressure is used, then ease of operation is maintained, but measurement precision deteriorates
Solution Approach 1:
The torque sensor mounted on the valve shaft performs self-service measurement by directly sensing the torque acting on the shaft. This eliminates the need for complex calculations or conversions from pressure readings, providing direct torque values that improve measurement precision while maintaining ease of operation through automatic sensing without manual intervention.
4Device complexity
If pressure-to-torque conversion calculations are used, then device complexity is reduced, but measurement precision deteriorates under fast-changing conditions
Solution Approach 1:
The torque sensor is pre-mounted on the valve shaft to enable direct torque measurement from the outset. This preliminary installation of the sensing capability allows the system to capture true mechanical torque values in real-time during fast-changing conditions, eliminating the need for subsequent pressure-to-torque conversions and their associated delays or inaccuracies.
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 approach provides improved measurement accuracy by enabling direct measurement of torque on valve shafts, enhancing the responsiveness of process control systems to varying conditions without the need for multiple devices.
Implementation Method 1
converting the signal to a pressure
Data Source
AI summary
Methods and apparatus for pressure-based direct measurement of a final control element variable are disclosed. An example method includes receiving a signal from a first sensor mounted on a shaft of a valve, converting the signal to a pressure, routing the pressure to a second sensor of a controller operatively coupled to a pneumatic actuator, the pneumatic actuator operatively coupled to the shaft, and determining, by the controller, a first torque on the shaft based on the pressure.