Pneumatic Torque Control Using Pressure-Torque Calibration
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Solution Overview
Problem
Conventional fluid-powered torque tools, particularly pneumatic and hydraulic impact or pulse torque wrenches, face challenges in accurately controlling output torque due to unstable working air pressure, leading to deviations in torque output and difficulties in signal analysis, which affects precision and operator safety.
Innovation Solution
A method involving a torque control apparatus that connects a fluid pressure system to a torque control device, calibrates output torque by driving the tool with different fluid pressures, constructs a correspondence relationship between pressure and torque, and adjusts fluid pressure to achieve a target torque value, ensuring stable working conditions and accurate torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional pneumatic torque tools control torque by adjusting air supply pressure and airflow, then the tool can operate with simple structure, but the output torque becomes unstable and difficult to control due to unstable working air pressure
Solution Approach 1:
The patent implements a feedback control system where a torque sensor detects the actual output torque, and this signal is fed back to a control unit that adjusts the air supply pressure accordingly. This closed-loop feedback mechanism ensures stable torque output despite fluctuations in the air supply system, resolving the contradiction between simple structure and reliable torque control.
Solution Approach 2:
The patent introduces an intermediary control system between the air supply and the torque-generating mechanism. This intermediary includes a pressure control valve and control unit that mediate the relationship between unstable air pressure and torque output, filtering out disturbances and providing stable torque control without requiring complete system redesign.
2Productivity
If torque tools use impact mechanisms to achieve fastening, then the operation speed increases, but the vibration and signal analysis difficulty reduce measurement precision
Solution Approach 1:
The patent replaces mechanical torque measurement methods with electronic sensing technology. A torque sensor with strain gauges converts mechanical torque into electrical signals that can be processed electronically, eliminating the interference from impact vibrations and enabling precise measurement during high-speed impact fastening operations.
Solution Approach 2:
The patent uses strain gauges that generate excessive signal during impact, then applies signal filtering and processing to extract the useful torque information. By intentionally creating a strong signal response and then selectively processing it, the system achieves accurate measurement despite the violent impact conditions.
3Measurement precision
If oil pulse torque tools adjust working air pressure and oil pressure for torque control, then torque control precision improves, but the adjustment range and control precision are limited by unstable air pressure and hydraulic system factors
Solution Approach 1:
The patent changes the control parameter from mechanical pressure adjustment to electronic pressure control. By using an electronic pressure control valve regulated by a control unit, the system can dynamically adjust air pressure over a wider range with finer resolution, overcoming the limitations of manual mechanical adjustment and unstable air pressure.
Solution Approach 2:
The patent transforms the static pressure adjustment mechanism into a dynamic control system. The electronic pressure control valve can rapidly and continuously adjust pressure in response to real-time feedback from the torque sensor, enabling adaptive torque control across a broad range of operating conditions rather than fixed preset values.
4Reliability
If torque tools are equipped with torque measuring devices for real-time control, then torque control capability is achieved, but the hysteresis in signal transmission reduces control accuracy
Solution Approach 1:
The patent implements continuous real-time monitoring and control where the torque sensor continuously detects torque during fastening, and the control unit continuously adjusts air pressure in response. This continuous feedback loop eliminates dead zones and hysteresis by maintaining constant control action throughout the entire fastening process rather than intermittent adjustments.
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 method enables precise and reliable control of torque output, reducing operator fatigue and occupational hazards by maintaining stable air pressure and adjusting fluid pressure to meet target torque values, enhancing the efficiency and accuracy of fluid-powered torque tools.
Implementation Method 1
a strain gauge, which is a known technology, is disposed on the torque output shaft
Data Source
AI summary
A method of torque control and a torque control apparatus for a pneumatic torque tool are provided. The method includes: connecting a torque control apparatus between an air supply system and a pneumatic torque tool; under predetermined working and control conditions, driving the pneumatic torque tool at the first and second working air pressures to calibrate output torque, and to obtain maximum and minimum torque values; constructing correspondence relationship between air pressure and torque value based on the first and second working air pressures and the maximum and minimum torque values obtained; entering any target torque value ranging from minimum torque value to maximum torque value of the correspondence relationship to obtain a corresponding working air pressure value and drive the pneumatic torque tool; and verifying whether all working and control conditions are controlled within a predetermined range of variation to control the output torque.