Absolute Position Detection in Handheld Power Tools
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Solution Overview
Problem
Existing systems for determining the absolute position of moving elements in handheld power tools are complex, prone to perturbations, and lack precision, often requiring magnets on the machining member which complicates tool fabrication and can interfere with the cutting action.
Innovation Solution
A system that determines the absolute position of a moving element in a handheld power tool without requiring a magnet on the machining member, using a computing module to analyze changes in magnetic flux induced by the moving element's ferromagnetic or conductive materials, thereby simplifying tool fabrication and improving positional accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnets are placed on the machining member to determine absolute position, then position detection is enabled, but tool fabrication becomes more complex and cutting action may be interfered with
Solution Approach 1:
The patent removes the magnet from the machining member and relocates it to the body of the power tool. This extraction eliminates the interference with cutting action and simplifies machining member fabrication, while position detection functionality is preserved through the alternative magnet placement combined with Hall effect sensors on the machining member
Solution Approach 2:
Instead of placing magnets on the moving machining member as in conventional systems, the patent inverts the approach by placing the magnet on the stationary body and sensors on the moving machining member. This inversion resolves the fabrication complexity and interference issues while maintaining absolute position detection capability
2Measurement precision
If conventional position detection systems are used, then absolute position can be determined, but the systems are complex and prone to perturbations
Solution Approach 1:
The patent replaces complex mechanical position detection systems with a magnetic field-based detection system using Hall effect sensors. This substitution eliminates mechanical wear, reduces complexity, and improves reliability by using solid-state electronic components that are less susceptible to mechanical perturbations
3Measurement precision
If magnets are placed on the machining member, then position detection is achieved, but precision is reduced due to sensitivity to perturbations
Solution Approach 1:
By extracting the magnet from the moving machining member and placing it on the stationary body, the system eliminates sources of perturbation associated with magnet placement on moving parts. This improves measurement precision and reliability by creating a stable magnetic field reference that is not subject to mechanical disturbances during operation
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
The system provides a simpler and more robust method for determining the absolute position of moving elements, achieving precision in the order of micro-meters and being less sensitive to perturbations compared to existing solutions.
Implementation Method 1
A system that determines the absolute position of a moving element in a handheld power tool without requiring a magnet on the machining member, using a computing module to analyze changes in magnetic flux induced by the moving element's ferromagnetic or conductive materials
Data Source
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AI summary
The present invention concerns a system for determining an absolute position of a moving element (3, 4) of an handheld power tool (10), the system comprising: - said handheld power tool (10), comprising: - a body (9), comprising: - an actuator, - an excitation coil (E1), arranged to conduct an alternating excitation current, wherein said alternating excitation current generates a magnetic flux traversing at least a measuring coil (M1, M2), - said measuring coil (M1, M2), - said moving element (3, 4), being made at least in part of a ferromagnetic material and/or by an electrically conductive material, said element being arranged to be moved by the user and/or by said actuator with regard to the body (9), wherein the moving of said element (3, 4) modifies said magnetic flux, wherein said system comprises: - a computing module (50), arranged to determine an absolute position of said moving element (3, 4) based on said magnetic flux.