Inductive Anvil Position Sensing for Power Tool Drive Angle Control
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Solution Overview
Problem
Existing power tools with impact mechanisms lack efficient control over the drive angle of the anvil, which affects the rotational output and task performance.
Innovation Solution
The power tool incorporates a brushless direct current (DC) motor, an impact mechanism with a hammer and anvil, an output drive device, a position sensor, and a controller. The position sensor detects the anvil's position, and the controller calculates the drive angle based on this position, adjusting the motor control accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If no position sensor is used, then the device complexity is reduced, but the control precision over drive angle 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 generates an alternating magnetic field that interacts with the conductive anvil, inducing eddy currents that provide position information without mechanical contact, thereby achieving precise drive angle control while minimizing mechanical complexity
Solution Approach 2:
The patent introduces an inductive sensor as an intermediary between the impact mechanism and the control system. This sensor acts as a mediator that non-invasively measures anvil position by detecting changes in inductance caused by the anvil's movement, enabling precise control without direct mechanical coupling or complex sensor assemblies
2Measurement precision
If an inductive sensor is used, then the measurement precision of anvil position is improved, but the device complexity increases
Solution Approach 1:
The patent replaces potential mechanical or optical position sensing systems with an inductive sensor that uses electromagnetic induction. The sensor generates an alternating magnetic field that penetrates non-magnetic materials and induces eddy currents in the conductive anvil, allowing position detection through electrical means rather than mechanical or optical systems, thereby achieving high precision with simpler electronics
Solution Approach 2:
The patent utilizes changes in inductance parameters as the anvil moves through different positions. The inductive sensor detects position by measuring variations in its inductance value caused by the proximity and movement of the conductive anvil, converting mechanical position into electrical parameter changes for precise measurement
3Productivity
If drive angle control is not implemented, then the device complexity is reduced, but the task performance deteriorates
Solution Approach 1:
The patent implements a feedback control system where the inductive sensor continuously monitors anvil position and provides real-time data to the controller. The controller uses this feedback information to calculate the drive angle and adjust motor operation accordingly, enabling precise control of rotational output and task performance through closed-loop feedback rather than open-loop operation
Solution Approach 2:
The patent enables the impact mechanism to self-regulate its operation through the controller that automatically adjusts motor parameters based on real-time anvil position data from the inductive sensor. The system performs self-diagnosis and self-adjustment of drive angle without external intervention, optimizing task performance autonomously
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
This solution enables precise control over the drive angle, improving the rotational output and task performance of the power tool, such as in applications like driving anchors into concrete.
Implementation Method 1
an inductive sensor positioned proximate the target... detect a first output signal on the first receiving circuit trace to determine a position of the anvil
Implementation Method 2
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.