Electric Machine Rotor Vent and Axial Slot Fluid Communication

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Solution Overview

Problem

Electric machines face challenges in effectively cooling their components due to the difficulty in forming cooling paths through the stator and rotor without negatively impacting the magnetic circuit, leading to potential damage from heat buildup.

Innovation Solution

The design incorporates a rotor with annular arrays of axial slots and rotor bar openings that are fluidly communicative, combined with a spacer element to create a rotor vent opening, allowing for increased airflow and coolant exposure to rotor bars while minimizing magnetic circuit impacts, and enabling a single-punch manufacturing operation for axial slots and rotor bar openings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling paths are formed through the stator and rotor, then cooling efficiency is improved, but magnetic circuit performance deteriorates

Engineering Contradiction:

Improvecooling efficiencyVSAvoidmagnetic circuit performance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The rotor is segmented into first and second core elements with discrete axial slots and rotor bar openings, allowing cooling paths to be formed through specific segments without compromising the overall magnetic circuit integrity. The spacer element further segments the structure to create rotor vent openings that provide additional cooling pathways.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Cooling paths are locally introduced through axial slots and rotor bar openings in specific regions of the rotor where heat generation is highest, rather than uniformly throughout the entire magnetic circuit. This localized approach provides effective cooling to hot spots while minimizing impact on overall magnetic performance.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If axial slots and rotor bar openings are separately manufactured, then manufacturing precision is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveslot and opening alignmentVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The axial slots and rotor bar openings are formed in a single punching operation rather than separate operations, merging multiple manufacturing steps into one. This reduces manufacturing complexity and the number of alignment operations required while maintaining the necessary precision through proper tooling design.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single punching operation serves multiple functions: it creates both the axial slots and the rotor bar openings simultaneously, and also establishes the fluid communication between them. This multi-functional approach simplifies the manufacturing process while achieving the desired geometric precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Temperature

If coolant flow path is extended through rotor bars, then cooling efficiency is improved, but pressure losses increase

Engineering Contradiction:

Improvecooling efficiencyVSAvoidpressure losses

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The axial slots are nested within the rotor structure and fluidly communicate with rotor bar openings, creating a hierarchical cooling path system. Coolant flows through the axial slots and then into the rotor bar openings, providing extended cooling coverage while maintaining relatively short flow paths that minimize pressure losses.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The spacer element acts as an intermediary that defines rotor vent openings, serving as a bridge between the axial slots and the external environment. This intermediary structure provides additional cooling pathways that extend coolant flow through the rotor bars while managing pressure losses through optimized flow distribution.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances cooling efficiency by allowing coolant to flow along the entire length of rotor bars, reducing pressure losses and manufacturing effort, while maintaining the magnetic circuit performance.

Implementation Method 1

each axial slot being fluidly communicative with a corresponding one of the rotor bar openings

Methodology Applied

Scientific EffectFluid communication:

Implementation Method 2

allowing for increased airflow and coolant exposure to rotor bars

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 3

a spacer element interposed between the first and second core elements to define a rotor vent opening fluidly communicative with the axial slots

Methodology Applied

Scientific EffectFluid communication:

Data Source

PatentUS9653954B2Electric machine rotor with rotor vent and axial slot fluid communication

Publication Date: 2017.05.16 INNOMOTICS LLC

AI summary

A rotor of an electric machine is provided and includes first and second core elements formed to define annular arrays of axial slots and rotor bar openings, each axial slot being fluidly communicative with a corresponding one of the rotor bar openings and a spacer element interposed between the first and second core elements to define a rotor vent opening fluidly communicative with the axial slots.