Brushless Motor Cooling via Segmented Airflow and Dust Protection
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Solution Overview
Problem
Brushless motors in power tools experience significant heat-related power loss and dust accumulation due to circulating external air for cooling, which affects efficiency and functionality.
Innovation Solution
A power tool design featuring a housing with air intake and exhaust holes, a cover member to prevent dust entry, and an insulating member that covers the stator teeth and coil, creating a ventilation path for cooling while minimizing dust ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external air is circulated through the stator for cooling, then heat dissipation is improved, but dust accumulates on the rotor and stator
Solution Approach 1:
The patent divides the cooling air flow path into two separate channels: one channel directs air through the stator for cooling, while another channel allows air to flow without entering the motor interior. This segmentation enables selective cooling of the stator while preventing dust-laden air from contaminating the rotor and stator surfaces.
Solution Approach 2:
The patent introduces an intermediary structure (separation wall or baffle) that mediates between the cooling requirement and dust prevention requirement. This intermediary element guides the cooling air flow along a predetermined path that contacts the stator for heat dissipation but prevents direct entry into the motor interior where dust accumulation would occur.
2Temperature
If a fan is mounted on the rotor to draw air for cooling, then cooling efficiency is improved, but the structure becomes more complex
Solution Approach 1:
The patent makes the rotor serve multiple functions: it not only performs its primary rotational function but also acts as a driving element for air circulation. By mounting the fan on the rotor, the rotor's rotation simultaneously drives the cooling air flow through the stator and prevents dust entry, eliminating the need for a separate cooling mechanism.
Solution Approach 2:
The patent merges the cooling function with the rotor assembly by integrating a fan onto the rotor. This combination allows the rotor to simultaneously perform its rotational drive function and generate the air flow necessary for stator cooling, thereby reducing overall system complexity while maintaining effective cooling.
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 solution effectively cools the brushless motor while preventing dust buildup, enhancing efficiency and reliability by ensuring clean air circulation and reducing the risk of component malfunction.
Implementation Method 1
The inner surface of the housing and outer surface of the brushless motor define a circulation path providing communication between the air intake hole and the air exhaust hole
Implementation Method 2
The cover member covers at least one of the first endface and the second endface for preventing dust from entering the brushless motor
Data Source
AI summary
A power tool includes a housing, a brushless motor, and a cover member. The housing has an air intake hole and an air exhaust hole formed therein, the housing having an inner surface. The brushless motor has an outer surface disposed in the housing, a first endface near the air intake hole, and a second endface near the air exhaust hole. The cover member covers at least one of the first endface and the second endface for preventing dust from entering the brushless motor. The inner surface of the housing and outer surface of the brushless motor define a circulation path providing communication between the air intake hole and the air exhaust hole.