Conductive Handle Frame for Power Tool EMC Grounding
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Solution Overview
Problem
Power tools, such as pistol tools, face challenges in achieving uniform electromagnetic compatibility (EMC) and electrostatic discharge (ESD) standards due to electrical isolation from plastic materials, leading to inconsistent ground levels and difficulties in assembly and maintenance, with existing solutions being cumbersome and expensive.
Innovation Solution
A power tool design featuring a handle unit with a conductive frame interconnecting the motor and battery units, along with a shock-absorbing adapter, made of conductive materials like aluminum or metal fiber reinforced plastic, ensuring a uniform ground level and facilitating assembly and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plastic materials are used extensively in the tool housing, then manufacturing cost and ease of manufacture are improved, but electrical isolation occurs between components leading to inconsistent ground levels and EMC/ESD compliance issues
Solution Approach 1:
A conductive connection element is introduced as an intermediary component between the motor unit and battery adapter. This element mediates the electrical connection through the plastic housing, providing a reliable ground level connection without requiring changes to the plastic housing structure. The connection element acts as a bridge that overcomes the electrical isolation caused by the plastic material.
Solution Approach 2:
The tool employs a composite structure combining plastic housing material with a conductive connection element. The plastic provides ease of manufacture and structural properties, while the conductive element embedded within or attached to the plastic ensures proper electrical grounding. This composite approach allows both materials to contribute their advantageous properties simultaneously.
2Reliability
If metal plates are installed in the handle shell to provide uniform ground level, then EMC and ESD compliance is improved, but assembly complexity and manufacturing cost increase
Solution Approach 1:
The conductive connection element is merged with existing structural components of the tool, such as being integrated into the motor unit housing or battery adapter structure. This merging eliminates the need for separate metal plates and reduces assembly steps. The grounding function is combined with the structural support function of existing components.
Solution Approach 2:
The conductive connection element serves multiple functions: it provides electrical grounding for EMC/ESD compliance, acts as a structural support element, and facilitates mechanical connection between components. This multi-functionality reduces the overall number of components needed and simplifies the overall assembly process.
3Productivity
If components are pressed into handle shells and shells are screwed together, then assembly is simplified, but repairability and component replacement become difficult
Solution Approach 1:
The tool is divided into modular segments (motor unit, battery adapter, handle shell) that can be independently accessed and serviced. The conductive connection element is positioned to allow access to internal components without requiring complete disassembly of the handle assembly. This segmentation enables quick replacement of individual components while maintaining overall assembly integrity.
4Strength
If rigid connection between handle and battery adapter is used, then structural strength is improved, but resistance to impact damage decreases
Solution Approach 1:
The connection between handle and battery adapter transitions from a purely rigid mechanical connection to a hybrid connection that incorporates elastic or shock-absorbing elements. This parameter change allows the connection to maintain structural strength under normal conditions while providing flexibility and shock absorption during impact events, preventing catastrophic failure.
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 design provides a reliable, robust power tool with consistent grounding across the entire tool, enhancing EMC and ESD compliance, reducing assembly complexity, and improving durability against impacts.
Implementation Method 1
the frame is made of an electrically conductive material that is strong and robust... providing a reliable, robust power tool with consistent grounding across the entire tool
Implementation Method 2
an adapter between the frame and the battery unit, which adapter is capable of absorbing shocks and impacts
Data Source
AI summary
Disclosed herein is a power tool comprising a motor unit comprising a motor and a drive axle connected to the motor, a battery unit configured to receive a battery and a handle unit interconnecting the motor unit and the battery unit, the handle unit comprising: a frame extending from the motor unit to the battery unit; a control button mounted to the frame for controlling the power tool; a circuit board mounted to the frame and connected to the control button; cables interconnecting the battery unit, the circuit board and the motor unit; an antenna connected to the circuit board for communication of the power tool with external devices; a pair of outer handle covers for covering the handle unit; wherein the frame is made of an electrically conductive material.