Brushless Motor Stator Locking and Wire Routing

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Solution Overview

Problem

Existing brushless motors in electric work machines face challenges with low alignment accuracy and reliability of the stator locking mechanism, and the method for connecting coils in parallel to achieve high output power results in complex wire routing and increased wire diameter, leading to wear and reduced space efficiency.

Innovation Solution

The stator core incorporates through-holes and ridges with tapered or rectangular cross-sections for precise locking with screws, and a delta connection configuration with metal sheets for coil winding, allowing for thinner wires and improved space efficiency, enhancing the reliability and accuracy of stator locking and reducing wire wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the stator is locked with engagement recesses on the insulator, then the stator can be locked without rotation, but the alignment accuracy is low due to tolerances and the reliability depends on the strength of the resin insulator

Engineering Contradiction:

Improvestator locking reliabilityVSAvoidstator alignment accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention extracts the locking function from the insulator and implements it directly on the stator core through protrusions that engage with recesses in the housing. This separates the locking mechanism from the insulator material, allowing for more reliable mechanical engagement with better alignment accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention incorporates through-holes in the stator core that receive screws to pre-tension and secure the stator position before operation. This beforehand securing mechanism compensates for tolerance variations and ensures high alignment accuracy and reliability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Power

If more coils are connected in parallel to achieve high output power, then the output power increases, but the wire diameter cannot be reduced further and the connecting wire routing becomes complex

Engineering Contradiction:

Improveoutput powerVSAvoidconnecting wire routing complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The invention merges the coil connections by routing all connecting wires through a common passage in the housing, consolidating multiple wire paths into a single organized route. This reduces the overall complexity of wire management while maintaining the parallel coil configuration for high power output.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention introduces a common passage as an intermediary structure that facilitates the routing of multiple connecting wires. This mediator element simplifies the complex wire routing by providing a dedicated, organized path that reduces wire crossings and management complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the connecting wire is routed back and forth between the stator and opposite side, then the coils can be connected in series and parallel, but the wire may be crossed to have crossing portions that contact each other and wear under vibrations

Engineering Contradiction:

Improvecoil connection flexibilityVSAvoidwire durability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention segments the wire routing path by providing separate, dedicated passages for different wire connections within the housing. This segmentation prevents wire crossings and contact between different connecting wires, eliminating the wear problem under vibrations while maintaining connection flexibility.

Inventive Principle:

Principle #1Segmentation

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 solution achieves highly accurate and reliable stator locking, reduces wire diameter while maintaining output power, and increases space efficiency by using thinner winding nozzles, resulting in a more compact and durable motor design.

Implementation Method 1

A known inner-rotor brushless motor includes a cylindrical stator and a rotor disposed inside the stator... The brushless motor including the stator and the rotor has three-phase coils on the stator, which are formed by winding a wire around the teeth of the stator to allow passage of electricity from a drive circuit through a switching element

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11323013B2Electric work machine

Publication Date: 2022.05.03 MAKITA CORP

AI summary

An electric work machine includes a brushless motor including a stator including a stator core, an electrical insulator located on the stator core, and at least one coil wound around the stator core with the electrical insulator in between, and a rotor rotatable with respect to the stator, and an output unit drivable by the brushless motor. The stator core has a through-hole and/or a recess to lock rotation of the stator with a screw.