Bicycle Geared Motor Stator Hub Casting to Prevent Axial Deviation

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Solution Overview

Problem

Existing electric pedal devices face challenges in preventing axial deviation of the core lamination in the stator core, which affects the generation and efficiency of electric energy during pedaling.

Innovation Solution

The electric pedal device incorporates a stator core with a hub and core lamination integrally formed using a low-pressure insert casting method, featuring grooves and locking mechanisms to prevent axial deviation, along with a reduction gear set and rotor core to generate electric energy from pedaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a separate fastening structure is used to connect the hub and core lamination, then the assembly flexibility is improved, but the manufacturing precision and structural integrity deteriorate due to potential axial deviation

Engineering Contradiction:
Improveassembly flexibilityVSAvoidaxial position accuracy of core lamination
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The hub and core lamination are merged into a single integrated component formed by low-pressure insert casting. The hub is cast directly onto the core lamination, eliminating the need for separate fastening structures and ensuring precise axial positioning without additional assembly steps.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The core lamination is positioned and fixed in the desired axial position before the hub casting process begins. The hub is then cast in place, permanently securing the core lamination at the correct position. This preliminary positioning ensures manufacturing precision is achieved during the casting process itself rather than requiring post-assembly adjustments.

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If the hub and core lamination are integrally formed, then the structural stability is improved, but the manufacturing complexity increases due to the low-pressure insert casting process

Engineering Contradiction:
Improvestructural stability of stator coreVSAvoidmanufacturing process complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent employs low-pressure insert casting, which uses controlled low pressure (typically 0.03-0.06 MPa) to inject molten metal into the mold cavity. This parameter change from conventional high-pressure casting enables the hub and core lamination to be integrally formed while preventing defects and ensuring structural stability.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The stator core combines metallic hub material with laminated core material in a composite structure. The low-pressure insert casting process is specifically designed to join these different materials, creating an integral structure that leverages the advantages of both materials while maintaining manufacturing feasibility.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If conventional casting methods are used, then the manufacturing simplicity is maintained, but the manufacturing precision deteriorates due to axial deviation of core lamination

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidaxial position accuracy of core lamination
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent replaces conventional high-pressure casting or mechanical assembly methods with low-pressure insert casting. This substitution eliminates the axial deviation problems associated with conventional methods while maintaining manufacturing simplicity through a single-casting process that integrates the hub and core lamination formation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 configuration effectively prevents axial deviation of the core lamination, enhancing the stability and efficiency of electric energy generation, allowing for reliable and efficient conversion of pedaling motion into electrical energy.

Implementation Method 1

a stator core including a hub and a core lamination coupled to the hub and having a structure preventing axial deviation of the hub

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4425767A1Geared electric motor for a bicycle
Publication Date: 2024.09.04 HL MANDO CORP
  • EP4425767A1 patent drawingFigure 1
  • EP4425767A1 patent drawingFigure 2
  • EP4425767A1 patent drawingFigure 3

AI summary

An electric device suitable for a bicycle is disclosed. Said electric pedal device includes a housing (10) configured to form a space therein, a rotating shaft (20) passes through both ends of the housing, a reduction gear set (30) configured to reduce a rotational force of the rotating shaft, a rotor (40) configured to rotate by an output of the reduction gear set, a stator (50) including a winding around core laminations (120) and a hub (100). Wherein said core laminations are coupled to the hub while prevented by a structure that an axial deviation relative to the hub is possible. Further a print circuit board (60), controlling the electric power to the stator, is fixed to said housing.