Power Tool Torque Control via Multi-Parameter Sensing
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Solution Overview
Problem
Existing power tools with clutch mechanisms often suffer from spurious blocking events due to reliance on current or acceleration measurements, leading to undesirable clutch slippage, as they do not accurately account for speed and mode settings.
Innovation Solution
A power tool with an electronic control apparatus that senses voltage, current, and angular velocity to calculate torque, allowing for precise control of angular velocity and actuation of a clutch at a predetermined torque level, thereby minimizing spurious blocking events and reducing mechanical parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current or acceleration measurements are used to detect blocking events, then the clutch mechanism can be activated, but spurious blocking events occur leading to undesirable clutch slippage
Solution Approach 1:
The patent changes the detection parameter from current or acceleration alone to a combination of voltage, current, and angular velocity measurements. By monitoring multiple parameters simultaneously and comparing their combined value against a threshold, the system achieves more accurate blocking event detection that accounts for speed and mode settings, thereby reducing spurious activations while maintaining reliable clutch engagement when actually needed.
2Reliability
If electronic clutch control is implemented, then clutch slippage can be reduced, but device complexity increases due to additional sensing and control components
Solution Approach 1:
The electronic control apparatus performs multiple functions: it monitors voltage, current, and angular velocity; calculates torque; determines blocking events; and controls clutch activation. By consolidating these functions into a single multi-functional control unit rather than separate dedicated components for each function, the system achieves reliable clutch operation while minimizing the increase in overall device complexity.
Solution Approach 2:
The patent replaces traditional mechanical clutch control mechanisms with an electronic control system that uses electrical measurements and digital processing to detect blocking events and actuate the clutch. This substitution eliminates the need for complex mechanical linkages and adjustments, reducing mechanical complexity while improving reliability through more precise and consistent electronic control.
3Measurement precision
If torque calculation uses multiple parameters (voltage, current, angular velocity), then torque detection accuracy improves, but measurement and calculation complexity increases
Solution Approach 1:
The patent introduces an electronic control apparatus as an intermediary that receives raw measurements of voltage, current, and angular velocity from separate sensors, processes these signals, and outputs a calculated torque value. This intermediary component simplifies the overall system architecture by centralizing the complex multi-parameter measurement and calculation tasks in a dedicated processing unit, thereby improving torque detection accuracy while managing complexity through functional consolidation.
Data Source
AI summary
A power tool comprises a housing and an electric motor disposed in the housing. A rotary output is driven by the motor. Electronic sensor configured to sense operating parameters of the power tool includes a voltage sensor arranged to detect the voltage across the electric motor, a current sensor arranged to detect the current through the tool, and a speed sensor arranged to detect the angular velocity ω of the output spindle. Electronic control apparatus is configured to determine from the operating parameter output signals the torque M of the rotary output and control the angular velocity of the rotary output in response to the calculation of the torque of said rotary output.