Contactless Switch in Vibration-Decoupled Side Handle
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Solution Overview
Problem
Electrical hand-held power tools face excessive wear due to high dust loads and strong vibrations, which affect mechanical contact switches, and existing contactless solutions are not compatible with power tools having side handles that extend transverse to the vibration axis.
Innovation Solution
A contactless manual switch is integrated into a side handle of an electrical hand-held power tool, utilizing a displaceable switching rod with a pivotally supported switching pivot point, allowing only axial actuation to ensure sufficient displacement of the switching means relative to the sensor switch, and featuring a Hall sensor switch and permanent magnet for robustness, with two sensor switches providing a redundant switching system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical contact switch is used in the power tool, then the switching function is simple and reliable, but the switch undergoes excessive wear due to high dust load and strong vibrations
Solution Approach 1:
The patent replaces the mechanical contact switch with a contactless sensor switch system. The actuation means generates a magnetic field detected by the sensor switch, eliminating mechanical contacts and thereby preventing wear caused by dust and vibrations. This substitution directly resolves the contradiction between switch durability and resistance to harmful environmental factors.
2Reliability
If a contactless sensor switch with actuation means is placed in the assembly, then the switch is protected from vibrations, but the actuation means cannot be conveniently located in the vibration-decoupled side handle
Solution Approach 1:
The patent divides the switching system into two separate parts: the actuation means is placed in the vibration-decoupled side handle for convenient operation, while the sensor switch is placed in the assembly for vibration protection. The magnetic field acts as the coupling between these segmented parts, allowing independent optimization of each component's location based on its functional requirements.
Solution Approach 2:
The magnetic field serves as an intermediary between the actuation means in the side handle and the sensor switch in the assembly. This intermediary allows the actuation means to be conveniently accessible while the sensor switch remains protected from vibrations, resolving the contradiction between ease of operation and switch protection.
3Ease of operation
If the actuation means is axially actuated in the side handle, then the operation is simple, but insufficient displacement is generated for reliable switching without a lever mechanism
Solution Approach 1:
The patent introduces a lever mechanism that converts the simple axial actuation motion into a pivoting motion with amplified displacement. The lever acts as a dynamic element that transforms the small axial movement of the actuation means into a larger angular displacement of the magnetic field generator, ensuring reliable switching while maintaining operational simplicity.
Solution Approach 2:
The lever mechanism transforms the one-dimensional axial actuation motion into two-dimensional pivoting motion. This dimensional change amplifies the displacement effect, allowing simple axial operation to produce sufficient magnetic field displacement for reliable switching detection.
4Device complexity
If a single sensor switch is used, then the system is simple, but the switching reliability is insufficient under harsh operating conditions
Solution Approach 1:
The patent implements a redundant switching system with multiple sensor switches that detect the same magnetic field changes. This redundancy acts as a cushion against failures, ensuring that if one sensor switch malfunctions, the system continues to operate reliably. The evaluation logic processes signals from multiple sensors to determine the final switching state, providing fault tolerance.
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 solution provides a vibration-insensitive, robust, and dust-insensitive contactless electrical manual switch, ensuring reliable operation even in tools with side handles extending transverse to the vibration axis, by decoupling the switching mechanism from axial vibrations and using redundant sensor switches for enhanced reliability.
Implementation Method 1
a contactless rotary switch which is associated, in a control manner, with a Hall sensor switch
Data Source
AI summary
An electrical hand-held power tool includes an assembly (2) vibrating along a vibration axis (A) during operation of the power tool, at least one, transversely projecting, vibration-decoupled pivotal side handle (3), a manual switch (4) having an actuation element (5) arranged in the side handle (3) and switchingly connectable with at least one sensor switch (8) which is located in the assembly (2) in vicinity of the handle pivot point (G), by a switching rod (7) having a switching element (6) and being pivotally supported on the side handle at a switching pivot point (S) spaced from the handle pivot point (G) and from the vibration axis (A).