Inductive Anvil Position Sensing for Impact Tool Torque Control
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Solution Overview
Problem
Existing power tools with impact mechanisms lack precise control over the anvil position and drive angle, leading to inefficiencies and potential damage due to improper torque application during operations.
Innovation Solution
Incorporation of a brushless DC motor with a rotor and stator, an impact mechanism featuring a hammer and anvil, and an inductive sensor to detect the anvil position, allowing for precise calculation of the drive angle and control of the motor based on this position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional impact mechanisms are used without position sensing, then the device complexity is low, but the manufacturing precision and control over anvil position deteriorates
Solution Approach 1:
The patent replaces complex mechanical position sensing mechanisms with an inductive sensor that uses electromagnetic fields to detect anvil position. The inductive sensor detects changes in inductance caused by the position of the anvil, eliminating the need for mechanical encoders or complex linkages while achieving precise position measurement.
Solution Approach 2:
The patent utilizes changes in electrical parameters (inductance, impedance) of the inductive sensor as the anvil position changes. By monitoring these electrical parameter variations, the system determines anvil position without mechanical contact, thus improving precision while keeping the system relatively simple.
2Measurement precision
If inductive sensor is added to detect anvil position, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent replaces mechanical position detection systems with an inductive sensor-based electromagnetic detection system. This substitution provides precise measurement of anvil position and drive angle while avoiding the complexity of mechanical encoders, gears, or linkages.
Solution Approach 2:
The inductive sensor system is designed to automatically detect and report anvil position and drive angle without requiring external calibration or complex signal processing. The sensor self-adjusts to provide accurate measurements across the operating range, reducing control system complexity.
3Reliability
If precise control over anvil position is implemented, then the reliability improves, but the device complexity increases
Solution Approach 1:
The patent implements a feedback control system where the inductive sensor continuously monitors anvil position and drive angle, and the controller adjusts motor operation based on this feedback. This ensures reliable torque application by preventing improper impact conditions while maintaining a relatively simple control architecture.
Solution Approach 2:
The patent replaces complex mechanical control mechanisms for torque regulation with an electronically controlled system using inductive sensing. The controller uses position data from the inductive sensor to electronically regulate motor operation, achieving reliable torque control without complex mechanical linkages or actuators.
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 precise control over the anvil position and drive angle, improving the efficiency and reducing the risk of damage by optimizing torque application in power tools with impact mechanisms.
Implementation Method 1
An inductive sensor, a first transmitting circuit trace, and a first receiving circuit trace are provided. The inductive sensor is configured to inject a signal on the transmitting circuit trace and detect a first output signal on the first receiving circuit trace
Data Source
AI summary
A power tool including a housing, a brushless direct current (DC) motor, an impact mechanism including a hammer and an anvil, an output drive device, a position sensor, and a controller. The power tool also includes a target positioned on a shaft, a magnetic shield positioned on the shaft between the target and the anvil, and a position sensor. The position sensor includes an inductive sensor, a first transmitting circuit trace, and a first receiving circuit trace. The controller is configured to calculate a drive angle based on the determined position of the anvil, and control the brushless DC motor based on the drive angle of the anvil.