Power Tool Dust Collection Power Isolation for EMI Control
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Solution Overview
Problem
Existing dust collection systems for power tools experience noise transmission from the direct current motor in the dust collection attachment to the power tool, which can lead to electromagnetic interference (EMI) issues, causing the power tool to fail EMI tests.
Innovation Solution
A dust collection system that includes an alternating current motor in the power tool and a direct current motor in the dust collection attachment, with the direct current motor powered by a separate battery pack and having a responsive unit that operates independently of the power tool's signal path, ensuring electrical separation and preventing noise transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a direct current motor is used in the dust collection attachment to generate suction force, then the dust collection function is improved, but noise is transmitted to the power tool through the power path causing electromagnetic interference
Solution Approach 1:
The power supply system is segmented into two independent paths: a first power path from utility power to the alternating current motor in the power tool, and a second power path from a battery pack to the direct current motor in the dust collection attachment. This segmentation isolates the noise-generating DC motor from the tool's power path, preventing electromagnetic interference while maintaining dust collection functionality.
Solution Approach 2:
A battery pack is introduced as an intermediary power source for the dust collection attachment's direct current motor. This intermediary isolates the DC motor's electrical noise from the tool's main power path, as the battery pack provides power through a separate electrical path that does not conduct noise back to the tool's alternating current motor or control circuits.
2Ease of operation
If the dust collection attachment is electrically connected to the power tool to enable motor operation, then the dust collection function is improved, but noise transmission occurs through the power path
Solution Approach 1:
The electrical connection is segmented into two independent circuits: the tool's alternating current power path and the attachment's direct current power path from the battery pack. This segmentation allows the DC motor to operate conveniently while preventing noise from coupling into the tool's power path, as the two circuits are electrically isolated from each other.
3Device complexity
If utility power is used to drive both the power tool and the dust collection motor, then the system is simplified, but electromagnetic interference occurs from the direct current motor
Solution Approach 1:
The power supply system is divided into two independent segments: utility power for the tool and a battery pack for the dust collection attachment. This segmentation increases device complexity slightly but ensures EMI test compliance by preventing noise from the DC motor from interfering with the tool's operation or control circuits.
Solution Approach 2:
The battery pack serves as an intermediary power source that isolates the dust collection motor from the tool's power system. This intermediary approach ensures reliable EMI compliance while maintaining a relatively simple overall system architecture, as the battery pack is a self-contained power source that requires minimal integration.
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 effectively prevents noise from the direct current motor in the dust collection attachment from reaching the power tool's power path, allowing the system to pass EMI tests without additional noise mitigation measures.
Implementation Method 1
a fan configured to generate a suction force in the suction portion
Implementation Method 2
a direct current motor configured to rotate the fan
Implementation Method 3
an alternating current motor drivable with a switch
Data Source
AI summary
A dust collection system for a power tool includes a power tool including an AC motor drivable with a switch and a tool-body power path extending from utility power to the AC motor, and a dust collection attachment attachable to the power tool to collect dust produced by the power tool in use and including a suction portion, a dust collector, a fan, a DC motor, a battery pack, and a dust-collector power path extending from the battery pack to the DC motor and electrically separate from the tool-body power path with the dust collection attachment attached to the power tool. The power tool includes a responsive unit that drives the DC motor in response to an operation on the switch with the responsive unit electrically separate from a signal path of the switch.