Brushless Motor Stator Screw Connection Design

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Solution Overview

Problem

Existing brushless motors for electric work machines, such as power tools, face challenges in manufacturing variability and labor-intensive repair processes due to soldering connections between stator and controller components.

Innovation Solution

The use of screw connections instead of soldering to electrically connect coil terminals with lead-wire terminals, allowing for detachable and attachable fixation of the short-circuiting member to the insulator, simplifying the connection and disconnection of the stator and controller, and reducing assembly time and manufacturing variability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If soldering is used to connect coil terminals with lead-wire terminals, then electrical connection is achieved, but manufacturing variability increases and repair becomes labor-intensive

Engineering Contradiction:

Improveconnection reliabilityVSAvoidmanufacturing variability

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the soldering process (thermal/chemical connection method) with a mechanical screw connection system. The short-circuiting member with embedded sheet-metal members is mechanically fastened to the stator using screws, eliminating the need for soldering while providing reliable electrical connection between coil terminals and lead-wire terminals. This mechanical substitution reduces manufacturing variability and simplifies the connection process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If soldering is used to connect stator and controller, then electrical connection is achieved, but repair time increases and labor intensity increases

Engineering Contradiction:

Improveelectrical connectionVSAvoidrepair time

Core Design Contradiction:

ReliabilityVSEase of repair

Solution Approach 1:

The patent segments the electrical connection system into detachable components: the short-circuiting member with embedded sheet-metal members can be independently removed from the stator by unscrewing fasteners. This segmentation allows the controller to be repaired or replaced without removing or damaging the stator, significantly reducing repair time and labor intensity compared to permanent soldered connections.

Inventive Principle:

Principle #1Segmentation

3Reliability

If soldering is used for terminal connections, then electrical connection is achieved, but assembly time increases

Engineering Contradiction:

Improveconnection stabilityVSAvoidassembly time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent incorporates the sheet-metal members embedded within the short-circuiting member during the manufacturing process, preparing the connection system in advance. The pre-positioned sheet-metal members with exposed terminals are ready for immediate mechanical connection via screws, eliminating the time-consuming soldering process during assembly while ensuring stable electrical connection.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11355983B2Electric motor and method of manufacturing such an electric motor

Publication Date: 2022.06.07 MAKITA CORP

AI summary

A stator (25; 25A) includes an insulator (28, 29) held on a stator core (27), coils (30) wound around the insulator and on the stator core, fusing terminals (50) held by the insulator and connected to the coils, and a short-circuiting member (32) having first, second and third sheet-metal members (68A-68C) that are respectively connectable to the fusing terminals by virtue of the short-circuiting member being detachably attached to the insulator by screws (75, 76).