Brushless Motor Stator Screw Terminal Connection
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Solution Overview
Problem
Existing electric power tools with brushless motors face challenges in compactness due to large end processed portions and cumbersome handling, which impairs productivity and handleability, primarily because of the need for soldering connections and lead wires that increase the size of the stator and hinder assembly and repair processes.
Innovation Solution
The solution involves connecting coil-side and lead wire-side terminals using screws at predetermined positions on the stator, allowing for a compact design by eliminating the need for soldering and simplifying the assembly process, while also enabling easy disconnection and reconnection of the brushless motor, thereby reducing the radial size of the stator and improving productivity and handleability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering is used to connect coil ends and lead wires, then electrical connection is achieved, but the end processed portions become large in radial direction and compactness is impaired
Solution Approach 1:
The patent replaces the soldering process (thermal/chemical connection method) with a mechanical screw connection system. The coil-side terminal and lead wire-side terminal are connected through a screw hole in the insulator, eliminating the need for soldering. This mechanical connection achieves reliable electrical connection while significantly reducing the radial size of the stator, as no additional space for solder joints is required.
2Reliability
If soldering connections are made during production, then electrical connectivity is established, but productivity decreases due to time-consuming soldering processes
Solution Approach 1:
The patent replaces the time-consuming soldering process with a rapid mechanical screw connection. The screw can be installed and tightened quickly without requiring soldering equipment, flux, or extensive manual dexterity. This dramatically reduces assembly time and improves productivity while maintaining reliable electrical connection between the coil and lead wires.
Solution Approach 2:
The insulator is designed with a screw hole pre-formed at the appropriate location before assembly. This preliminary preparation of the connection path allows for rapid assembly of the screw connection without requiring additional steps to create or access the connection point, further improving productivity.
3Use of energy by moving object
If lead wires are used for connection, then power supply to coils is enabled, but handleability deteriorates due to obstacles during assembly and repair
Solution Approach 1:
The patent merges the lead wire-side terminal directly with the stator structure through the insulator. The terminal is positioned and fixed within the stator housing, eliminating loose lead wires that obstruct assembly and repair operations. Power supply is maintained through this integrated terminal connection, while handleability is improved by removing the physical obstacles of dangling wires during maintenance activities.
4Reliability
If soldered connections are made, then electrical connectivity is achieved, but ease of repair worsens due to cumbersome disassembly requirements
Solution Approach 1:
The patent segments the connection system into separable components: the coil-side terminal fixed to the stator, the lead wire-side terminal, and the screw connector. This segmentation allows the lead wire-side terminal to be easily removed from the stator by simply unscreving the screw, enabling quick repair or replacement operations. The electrical connection is maintained when assembled but can be easily disconnected for repair, unlike permanent soldered joints.
Data Source
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AI summary
In an impact driver (1), a stator is made compact to accommodate a brushless motor in a reduced space, thereby keeping a housing compact, and productivity and handleability are also improved. The impact driver (1) includes a brushless motor (13) including a stator (30) in which coils (35) are wound and that includes fusing terminals (51A to 51 C) at which the coils (35) are fused, and a rotor (31) capable of rotating relative to the stator (30), lead wires (84) for supplying power to the coils (35), respectively, and lead wire-side terminals (77A to 77C) to which the lead wires 84, 84 ·· are connected, respectively. The fusing terminals 51A to 51C and the lead wire-side terminals (77A to 77C) are connected to each other at a predetermined position (a connection plate (44)) in a circumferential direction of the stator (30) by means of screws (96).