Outer Rotor Brushless Motor for Circular Saw Torque-Speed Trade-off
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Solution Overview
Problem
Current circular saws face a trade-off between high rotation speed and output torque, where increasing torque decreases speed, compromising cutting ability.
Innovation Solution
The design incorporates an outer rotor, brushless motor with a rotor sleeve, motor shaft, stator core, and stator coils, allowing for high torque output even at low rotation speeds, balanced by optimizing the rotation speed and transmission ratio to enhance cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the rotation speed is increased, then the cutting speed is improved, but the output torque is decreased
Solution Approach 1:
The patent changes the fundamental parameter of motor configuration from inner rotor to outer rotor. This structural parameter change allows the motor to achieve high torque output at low rotation speeds, fundamentally resolving the trade-off between speed and torque by altering the physical configuration rather than adjusting operational parameters
2Force
If the output torque is increased by decreasing the rotation speed, then the cutting ability is improved, but the cutting speed is reduced
Solution Approach 1:
The patent applies parameter change by transitioning to an outer rotor motor configuration, which fundamentally alters the torque-speed characteristic curve. This allows the motor to deliver high torque at low speeds without sacrificing cutting speed, as the transmission system can be optimized to achieve both high torque output and high cutting speed simultaneously
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 configuration improves cutting speed and ability by maintaining high torque and efficient cutting performance across various materials, as demonstrated by longer cutting lengths per unit of electricity and increased cutting speeds compared to traditional inner rotor motors.
Implementation Method 1
stator coils wound around the stator core
Data Source
AI summary
A cutting machine includes a cutting element for cutting material, a motor for driving the cutting element to rotate and a housing for containing the motor. The motor includes a rotor sleeve being formed with a receiving chamber, a motor shaft being capable of rotating together with the rotor sleeve, a stator core at least partially contained in the receiving chamber, stator coils wound around the stator core, and a stator bracket for fixing the stator core. The stator core is formed with a through hole for the motor shaft to pass there through, the stator coils are located outside the through hole and, the motor shaft is capable of rotating relative to the stator core.