Power Tool Control Module Sealing for Dust and Water Protection
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Solution Overview
Problem
Existing power tool control modules with snap-fit connections between the cover and case are prone to gaps, leading to inadequate dustproofing and waterproofing, which can cause corrosion and poor conduction due to dust or water ingress.
Innovation Solution
A control module design that integrates a bonded cover and case using welding or bonding agents to eliminate gaps, creating a sealed enclosure for movable switches, with components like microcomputers and FETs positioned outside the sealed space to dissipate heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If snap fit connection is used to connect the cover and case, then the assembly is easy to manufacture and disassemble, but gaps are formed between the cover and case leading to inadequate dustproofing and waterproofing
Solution Approach 1:
The patent replaces the mechanical snap fit connection system with an ultrasonic welding system. The ultrasonic welding apparatus uses high-frequency vibration to melt and bond the cover and case together, eliminating gaps and providing reliable dustproofing and waterproofing while maintaining ease of manufacture through automated welding processes.
Solution Approach 2:
The patent changes the connection parameter from mechanical interlocking (snap fit) to thermal bonding (ultrasonic welding). This parameter change transforms the connection method to achieve both gap-free sealing and manufacturing efficiency, as ultrasonic welding can be automated and provides consistent seal quality.
2Reliability
If the cover and case are bonded to form a sealed enclosure, then dustproofing and waterproofing are improved, but heat dissipation for microcomputers and FETs may be compromised
Solution Approach 1:
The patent segments the control module into two distinct zones: a sealed enclosed space containing only the movable switches for dustproofing and waterproofing, and an external area for heat-generating components (microcomputers and FETs) that remains accessible for heat dissipation. This spatial segmentation allows both requirements to be satisfied simultaneously.
Solution Approach 2:
The patent extracts the heat-generating components (microcomputers and FETs) from the sealed enclosed space and positions them outside the cover. This extraction removes the heat dissipation conflict from the sealed environment while maintaining the protective enclosure for the movable switches.
3Reliability
If movable switches are enclosed in the sealed space, then protection from dust and water is improved, but the complexity of the control module structure increases
Solution Approach 1:
The patent merges the protective function with the existing cover structure. The cover serves dual purposes: as a structural component of the control module and as a seal for the enclosed space. This merging avoids adding separate protective structures and maintains relative structural simplicity.
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 sealed design prevents dust and water ingress, ensuring reliable operation of movable switches and efficient heat dissipation, reducing the risk of contact failure and enhancing the durability of the power tool.
Implementation Method 1
at least portions of the cover and the case are melted so as to be welded to each other
Implementation Method 2
a bonding agent is used to bond the cover and the case to each other
Implementation Method 3
The bonded parts form an enclosed space, which encloses the movable switches
Data Source
AI summary
A control module (10) for a power tool includes a box-shaped case (60), one side of which is open, and a circuit board (50) housed in the case. A microcomputer (51) and FETs (52) configured to control a brushless motor (1c) of the power tool are mounted on the circuit board. Movable switches (30) are mechanically linked to movement of a trigger (20) and are electrically connected to the circuit board. A cover (70) partially covers the opening of the case such that a portion of the circuit board and the movable switches are covered. Bonded parts (14) weld or otherwise materially bond the cover and the case to form an enclosed space (13), which encloses the movable switches.