Compact BLDC Grinding Tool Venting for Debris Control
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Solution Overview
Problem
Existing power tools, such as grinders, face challenges in optimizing airflow to reduce contamination from debris entering through air intake vents, leading to inefficiencies in cooling and performance.
Innovation Solution
A compact and high-power electric motor with a brushless direct-current (BLDC) design, coupled with a advanced wheel retention mechanism and electronic braking system, is integrated into a power tool housing to maintain high rotational speeds and torque while minimizing contamination and ensuring secure accessory retention during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If screens or air filters are provided on air intake vents to filter out contamination, then air quality is improved, but small amounts of leakage dust and debris still enter and overall contamination reduction is limited
Solution Approach 1:
The harmful factor (debris-laden air) is extracted and removed from the system by directing it away from the motor through dedicated debris outlet vents, preventing contamination at the source rather than relying solely on filtration
Solution Approach 2:
The air intake system is segmented into separate pathways: clean air intakes for motor cooling and debris-laden air intakes for grinding function, allowing each to be optimized independently without compromising the other
2Volume of moving object
If a compact motor design is used to reduce tool size, then portability is improved, but maintaining high power output becomes more difficult
Solution Approach 1:
The motor operates at optimized parameters including 5000-6000 RPM rotational speed and controlled torque ranges (30-45 inch-lbs) to maximize power density within the compact form factor
Solution Approach 2:
The motor incorporates dynamic control through electronic braking and variable speed operation, allowing the compact motor to deliver high power when needed while maintaining small size through efficient energy utilization
3Loss of time
If electronic braking is applied to stop the output spindle quickly, then operational efficiency is improved, but accessory wheel retention becomes critical to prevent detachment
Solution Approach 1:
The wheel retention mechanism is pre-configured with springs and retaining structures that are ready to engage the accessory wheel before braking begins, ensuring continuous retention throughout the braking process
Solution Approach 2:
Spring elements in the retention mechanism provide cushioning and continuous contact force on the accessory wheel, preventing detachment during the high-stress electronic braking event
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 enables efficient airflow, maintains high output rotational speeds and torque levels with minimal speed drop, and effectively retains accessories during braking, enhancing performance and user experience in metalworking applications.
Implementation Method 1
A compact and high-power electric motor with a brushless direct-current (BLDC) design
Implementation Method 2
the controller configured to apply an electronic brake to the motor to bring the output spindle from an output rotational speed of approximately 5,000 to 6,000 rotations-per-minute (RPM) to a full stop in less than approximately 2.2 seconds
Implementation Method 3
the wheel retention mechanism is configured to keep the accessory wheel having a mass of approximately 800 to 900 grams and a rotational inertial of approximately of 4.35×10−3 kg·m2 to 4.44×10−3 kg·m2 in engagement with the output spindle throughout a duration of the electronic brake
Data Source
AI summary
A power tool is provided including a motor having an axial length of smaller than or equal to 65 mm and an outer diameter of smaller than or equal to 63 mm. The electric motor is configured to produce a maximum power output of greater than or equal to 2800 watts when the battery pack coupled to the battery receiver has a nominal voltage output of smaller than or equal to 60 volts and a rated capacity of approximately 9 ampere-hours (A.h.). Further, the motor drives an output spindle so as to maintain an output rotational speed of greater than 3,500 rotations-per-minute (RPM) within a torque range of 30 inch-lbs to 45 inch-lbs and exhibit a drop in the output rotational speed that is less than or equal to approximately 11.5% as the torque increases from 30 inch-lbs to 45 inch-lbs.