Brushless Motor Sensor Board Wiring for Repairable Power Tools
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Solution Overview
Problem
Existing driver-drills with brushless motors require the removal of the entire motor, controller, and battery mounting part when any component fails, making repair, replacement, and inspection labor-intensive and costly due to the interconnected nature of signal and power lines.
Innovation Solution
The design includes a stator with coils, a sensor circuit board attached to the stator, and a rotor, where power-supply lines are connected to the coils without traversing the sensor circuit board's opposite side, allowing for easier disconnection and reconnection of components, and the use of releasable connections and stranded wires with fraying prevention to facilitate maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signal lines are fastened to the sensor circuit board and power-supply lines are welded in place, then the electrical connection is reliable and stable, but the entire motor assembly must be removed collectively when any component fails, making repair labor-intensive and costly
Solution Approach 1:
The patent divides the electrical connection system into separate modular components: the sensor circuit board with its signal lines, the power-supply lines with connection terminals, and the coil assembly. This segmentation allows each component to be independently removed and replaced without affecting the others, resolving the contradiction by enabling easy repair while maintaining reliable electrical connections through dedicated connection terminals.
2Device complexity
If all signal lines and power-supply lines are interconnected through the sensor circuit board, then the system structure is compact and integrated, but disconnection requires removing the entire motor, controller, and battery-mounting part collectively
Solution Approach 1:
The patent introduces connection terminals as intermediary components between the power-supply lines and the coil assembly. These terminals serve as mediators that enable easy disconnection and reconnection of electrical components without requiring removal of the entire assembly. The sensor circuit board remains integrated with the stator, while the power-supply lines can be independently connected or disconnected through these terminal intermediaries.
3Length of moving object
If the power-supply line traverses through the second side of the sensor circuit board, then the wiring path is direct and short, but it complicates the removal and reconnection of the sensor circuit board and motor components
Solution Approach 1:
The patent extracts the power-supply line connection path from the sensor circuit board area by providing dedicated connection terminals separate from the board. The power-supply lines are connected to terminals that are positioned away from the sensor circuit board's second side, allowing the board to be removed without disturbing the power-supply wiring. This extraction resolves the contradiction by maintaining short power-supply lines while enabling easy circuit board removal.
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 design enables quicker and more cost-effective inspection and repair of brushless motor-based power tools by allowing individual components to be removed and reconnected without affecting the entire system, reducing maintenance complexity and costs.
Implementation Method 1
The rotation detection devices are configured to detect the positions of permanent magnets provided on a rotor and to output rotation-detection signals
Implementation Method 2
The brushless motor also includes a stator having a stator core on which multiple coils are sequentially wound in a delta configuration
Data Source
AI summary
A power tool includes a stator having a coil, a sensor circuit board attached to the stator and on which a magnetic sensor is provided, the sensor circuit board having a first side facing the stator and a second side opposite the first side, a rotor configured to rotate with respect to the stator, a tool-accessory retaining part configured to be driven by the rotor and a power-supply line configured to supply electrical power to the coil. The power-supply line is connected to the coil without traversing the second side of the sensor circuit board.