Power Tool Switch Wiring for EMI Suppression With Less Cabling
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Solution Overview
Problem
Conventional hand-held power tools require extensive cabling to integrate the interference-suppression capacitor, leading to increased material costs and complexity.
Innovation Solution
A hand-held power tool design where the interference-suppression capacitor is connected to the drive current line via a first node and to the second electrical line arrangement via a second node, eliminating the need for a separate line to the neutral conductor and reducing cabling requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interference-suppression capacitor is integrated in the handle of the main switch and wired directly to the phase conductor and neutral conductor, then effective interference suppression is achieved, but the expenditure on cabling increases significantly
Solution Approach 1:
The patent merges the interference-suppression capacitor into the second electrical line arrangement (control circuit wiring) rather than requiring a separate connection to the neutral conductor. The capacitor is connected via a first node to the drive current line and via a second node to the second electrical line arrangement, effectively combining the interference suppression function with the existing control wiring infrastructure, thereby eliminating the need for additional cabling.
2Reliability
If a separate line is used to connect the interference-suppression capacitor to the neutral conductor, then proper interference suppression is achieved, but additional connectors and wall routing are required
Solution Approach 1:
The second electrical line arrangement, originally intended for control circuit power supply, is given a dual function: it supplies power to the control circuit and simultaneously serves as the return path for the interference-suppression capacitor. This multi-functional use of the existing wiring eliminates the need for separate connectors and wall routing for the capacitor connection.
3Reliability
If extensive cabling is used for the interference-suppression capacitor, then reliable interference suppression is achieved, but material costs and construction time increase
Solution Approach 1:
The patent extracts the neutral conductor connection function from the capacitor wiring by utilizing the existing second electrical line arrangement that already provides a reference potential to the control circuit. This extraction eliminates the need for additional neutral conductor cabling while maintaining the capacitor's ability to suppress interference.
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 design reduces cabling expenditure and eliminates the need for additional connectors, simplifying the tool's construction and operation while maintaining effective interference suppression.
Implementation Method 1
an interference-suppression capacitor for short-circuiting high-frequency interference voltages or interference currents that occur in the drive circuit during operation of the hand-held power tool to a reference potential
Data Source
AI summary
A hand-held power tool, including: a drive circuit for providing an adjustment signal as a function of actuation of a button, a control apparatus for adjusting a drive current for an electric motor of the hand-held power tool as a function of the adjustment signal, wherein the control apparatus is connected to an electrical energy source for operating the hand-held power tool via a first electrical line arrangement, the drive circuit is connected to the control apparatus via a second electrical line arrangement, a drive current line carrying the drive current for the electric motor is routed via an interruption switch, coupled to the button, for interrupting the drive current, and wherein an interference-suppression capacitor is connected to the drive power line via a first node and to the second electrical line arrangement via a second node.