Impact Tool Anvil Position Sensing for Consistent Torque Control
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Solution Overview
Problem
Existing power tools struggle to consistently deliver a desired output characteristic, such as torque, without the use of a torque transducer, and lack accurate impact counting for controlling motor operations.
Innovation Solution
A power tool with an anvil position sensor and a controller that monitors anvil position to detect impacts, allowing for precise control of motor operations in various modes, including blow counting, angular distance, turn-of-nut, and constant energy modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque transducer is used to achieve consistent torque output, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical torque transducer with an output position sensor that measures angular position of the anvil. The controller calculates torque-based output characteristics from position data, eliminating the need for complex mechanical torque measurement devices while maintaining measurement precision through electronic sensing and computation.
Solution Approach 2:
The patent introduces an intermediary approach by using the anvil's angular position as a proxy indicator for torque output. Instead of directly measuring torque, the system measures the anvil's position angle, which correlates with torque delivery, thereby simplifying the measurement system while preserving the ability to control and monitor torque characteristics.
2Productivity
If impact counting is implemented to control motor operations, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring the anvil's angular position through the output position sensor. The controller counts impacts based on position changes and uses this feedback to dynamically control motor operation, stopping or adjusting motor power delivery when a predetermined number of impacts is reached, thereby improving productivity through automated control.
Solution Approach 2:
The system uses the anvil's own positional movement as the measurement basis for impact counting. The anvil's rotation during impacting provides the feedback signal needed to count impacts and control motor operation, eliminating the need for separate impact sensors or complex counting mechanisms.
3Measurement precision
If direct anvil position monitoring is used to achieve consistent output, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The output position sensor serves multiple functions: it measures anvil angular position for torque control, counts impacts for productivity control, and provides feedback for motor operation control. By making the sensor system multi-functional, the patent improves measurement precision across multiple parameters without proportionally increasing device complexity.
Solution Approach 2:
The patent changes the measurement parameter from direct torque measurement to angular position measurement of the anvil. This parameter transformation allows the same sensor system to infer multiple output characteristics (torque, impact count, energy) from a single position measurement, improving measurement precision while avoiding the complexity of multiple specialized sensors.
Data Source
AI summary
A power tool including a motor and an impact mechanism. The impact mechanism is coupled to the motor and includes a hammer driven by the motor, and an anvil positioned at a nose of the power tool, and configured to receive an impact from the hammer. The power tool also includes a sensor assembly positioned at the nose of the power tool, and an electronic processor. The sensor assembly includes an output position sensor configured to generate an output signal indicative of a position of the hammer or the anvil. The electronic processor is coupled to the output position sensor and to the motor, and is configured to operate the motor based on the output signal from the output position sensor.