Impact Wrench Torque Control via Rotor Rebound Speed
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Solution Overview
Problem
Existing electric impact wrenches with rebound impact mechanisms lack accurate control over tightening torque, often relying on impact count or torque measurement, which can be unreliable and limited in precision.
Innovation Solution
A method and device that determine the maximum rotation frequency of the rotor during rebound impacts to control tightening torque by setting a predetermined threshold, allowing for precise torque control without direct torque measurement, using sensors or vector control to monitor and stop the operation when the threshold is reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque measurement means are added to impact wrenches to control tightening torque, then torque control accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces an intermediary parameter (rotor rebound rotation frequency) that indirectly indicates torque level without requiring direct torque measurement. The control device uses this frequency as a mediator to infer tightening torque, thereby avoiding the need for complex torque sensors while maintaining control accuracy.
Solution Approach 2:
The patent replaces the mechanical torque measurement system with an electrical/electronic measurement system that monitors rotor rotation frequency. Instead of using mechanical torque sensors, the system substitutes with electronic frequency detection of rotor rebound, simplifying the overall device architecture.
2Measurement precision
If torque measurement means are added to impact wrenches, then torque control accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent employs inexpensive rotation frequency sensors (such as Hall effect sensors or simple magnetic markers) instead of expensive torque measurement devices. These low-cost sensing elements provide sufficient information for torque control without the high manufacturing cost associated with traditional torque sensors.
Solution Approach 2:
The patent replaces expensive mechanical torque measurement systems with more economical electronic frequency detection methods, significantly reducing manufacturing costs while maintaining the ability to control tightening torque accurately.
3Device complexity
If impact count method is used to control screwing operation, then device complexity is reduced, but torque control accuracy deteriorates
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors rotor rebound rotation frequency and uses this information to control the screwing operation. This feedback loop provides real-time torque information, significantly improving control accuracy compared to simple impact counting, while keeping the device relatively simple.
Solution Approach 2:
The patent changes the monitored parameter from simple impact count to rotor rebound rotation frequency. This parameter change provides much richer information about the tightening process and torque levels, enabling accurate torque control without requiring complex measurement systems.
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
Enables reliable and efficient screwing operations by accurately controlling torque without the need for torque sensors, making the wrench more robust, compact, and cost-effective, applicable to a wide range of impact wrenches.
Implementation Method 1
at the end of each of which the rotor rotates in a rebound in the opposite direction to the screwing/unscrewing operation
Implementation Method 2
drive of the impact mechanism generating the occurrence of a plurality of successive impacts
Data Source
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AI summary
The present invention relates to a method for controlling the torque applied during a screwing/unscrewing operation by means of a screwing device comprising: - an electric motor equipped with a rotor; - an output member capable of being driven in rotation;- a rebounding impact mechanism rigidly linked to said rotor and said output member, said method comprising supplying said motor inducing a drive of said impact mechanism by said rotor and a periodic rotational drive of said output member by said impact mechanism, the drive of said impact mechanism generating the occurrence of a plurality of successive impacts, at the end of each of which said rotor rotates in a rebound in the opposite direction to the screwing/unscrewing operation, said method comprising - a step of determining a maximum rotational frequency reached by said rotor during the rebound following the occurrence of each of said impacts in said impact mechanism, and - a step of stopping said screwing/unscrewing operation when said maximum rotational frequency reaches a predetermined threshold corresponding to a predetermined torque level.