Power Tool Fan Grid Staggered Elongated Portions
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Solution Overview
Problem
Conventional power tools with motor-driven fans are prone to foreign object entry through ventilation holes, leading to fan lockage or motor shorting, which compromises their functionality.
Innovation Solution
A power tool design featuring a housing with ventilation holes adjacent to the fan, partially covered by a grid with elongated portions arranged in a staggered manner to increase air resistance and prevent foreign object entry, along with a rib portion to further suppress infiltration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ventilation hole is positioned adjacent to the fan for efficient air introduction/exhaustion, then air flow efficiency is improved, but foreign objects can enter the housing through the ventilation hole causing fan lockage or motor shorting
Solution Approach 1:
A grid is introduced as an intermediary component between the ventilation hole and the fan. The grid includes elongated portions arranged in a staggered pattern that allows air to pass through while physically blocking foreign objects from reaching the fan, thus resolving the contradiction between air flow efficiency and protection reliability
Solution Approach 2:
The grid is segmented into multiple elongated portions arranged in a staggered pattern rather than a continuous structure. This segmentation allows air to pass through the gaps between segments while the staggered arrangement creates effective barriers against foreign object entry, balancing air flow and protection requirements
2Reliability
If the grid completely covers the ventilation hole to prevent foreign object entry, then protection reliability is improved, but air passage resistance increases reducing cooling efficiency
Solution Approach 1:
The grid provides partial coverage of the ventilation hole rather than complete coverage. The elongated portions are strategically positioned to provide sufficient protection against foreign objects while leaving adequate gaps open for air passage, achieving the right balance between protection and cooling efficiency
Solution Approach 2:
The grid structure has varying local properties - the elongated portions provide protection in certain areas while gaps between them allow air flow in other areas. This local differentiation of quality (solid vs. open spaces) enables simultaneous achievement of protection and air flow requirements
Data Source
AI summary
A power tool includes: a motor; a fan driven by the motor and defining an axis and a radial direction; and a housing for accommodating the motor and the fan therein, the housing including: a peripheral wall formed with a ventilation hole; and a grid partly covering the ventilation hole, the ventilation hole being positioned adjacent to the fan and having a shape defined by a circumferential surface, the grid including at least one elongated portion extending in a longitudinal direction perpendicular to the radial direction, and a distance from the axis of the fan to the circumferential surface is different from a distance from the axis of the fan to one elongated portion in the radial direction of the fan.