Brushless Power Tool Speed Modes for Low-Noise No-Load Cutting
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Solution Overview
Problem
Electric power tools, such as circular saws, face challenges in increasing cutting efficiency while minimizing vibration, noise, and power consumption, particularly when trying to enhance rotation speed during no-load conditions.
Innovation Solution
An electric power tool with a brushless motor and a control unit that allows for multiple rotation speed modes, including high-speed and low-speed modes, using duty ratio control to manage power supply and rotation speed based on detected load values, with soft start control for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotation speed during no-load increases to increase cutting efficiency, then productivity is improved, but vibration and noise increase
Solution Approach 1:
The patent implements dynamic rotation speed control by providing multiple rotation speed modes (first rotation speed mode and second rotation speed mode) that can be switched based on operational requirements. The control unit dynamically adjusts the rotation speed of the rotary tool according to the detected rotation speed and selected mode, allowing the system to operate at high speed for productivity when needed and low speed to minimize vibration and noise when appropriate.
2Ease of operation
If the rotation speed during no-load increases to emphasize smooth cutting performance, then cutting performance is improved, but power consumption unnecessarily increases
Solution Approach 1:
The patent applies parameter changes by offering multiple rotation speed modes (first and second rotation speed modes) with different speed characteristics. The control unit changes the rotation speed parameter based on the selected mode and detected conditions, allowing smooth cutting performance to be achieved at appropriate speeds without unnecessarily increasing power consumption. The system can switch between modes to optimize the balance between cutting performance and energy efficiency.
3Adaptability or versatility
If multiple rotation speed modes are implemented to control the brushless motor, then adaptability is improved, but device complexity increases
Solution Approach 1:
The control unit automatically detects the rotation speed of the rotary tool and determines the appropriate rotation speed mode based on this detection, reducing the need for complex manual control mechanisms. The system performs self-service by autonomously selecting operating modes based on detected conditions, thereby improving adaptability while minimizing the increase in device complexity through automated decision-making rather than additional mechanical components.
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 reduces vibration and noise during no-load conditions, optimizes power consumption, and improves work efficiency by adjusting rotation speeds according to load levels, ensuring effective use of input power and reducing unnecessary power consumption.
Implementation Method 1
a brushless motor
Implementation Method 2
by duty ratio control
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An electric power tool comprising a brushless motor; a control unit configured to control power supply to the brushless motor; a rotary tool configured to be rotated by the brushless motor; a rotation speed detecting unit configured to detect a rotation speed of the brushless motor; a main switch configured to transmit, to the control unit, an ON/OFF signal for switching between driving and stopping of the brushless motor; and a mode switching unit configured to transmit, to the control unit, a mode switching signal for switching between multiple modes of rotation control of the brushless motor, wherein the control unit is configured to perform the rotation control of the brushless motor in any one of the multiple modes including at least a first mode and a second mode, wherein the control unit is configured to change the rotation control from first control to second control according to a load on the brushless motor, in the first mode, and wherein the control unit is configured not to change the rotation control from the first control to the second control according to the load on the brushless motor, in the second mode.