Squirrel-Cage Rotor Bar Assembly for Simpler Induction Motor Manufacturing

Solution Overview

Problem

Existing methods for assembling squirrel-cage rotors in induction machines are time-consuming, complex, and costly, with conventional manufacturing processes like die-casting, extrusion, forging, and machining posing challenges in terms of efficiency, material waste, and precision.

Innovation Solution

A modified squirrel-cage rotor assembly and method involving a first and second bar assembly inserted into a rotor core, with end rings formed by welding or induction heating, reducing the need for multiple shapes and simplifying the manufacturing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional manufacturing processes (die-casting, extrusion, forging, machining) are used for squirrel-cage rotors, then traditional rotor structures can be produced, but manufacturing time is excessive, complexity increases, and cost rises

Engineering Contradiction:

Improvemanufacturing assembly timeVSAvoidmanufacturing process complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The rotor bars are divided into two distinct assemblies: a first bar assembly with first bars and a second bar assembly with second bars. These assemblies are inserted into alternating bar passages of the rotor core, creating a segmented manufacturing approach that simplifies production while maintaining structural integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first and second bar assemblies are combined within the rotor core structure, with both assemblies integrated into the same core body. The end rings then merge these distinct bar assemblies electrically and mechanically, creating a unified rotor structure from separate manufactured components

Inventive Principle:

Principle #5Merging (Combining)

2Ease of manufacture

If multiple bar shapes are used in conventional rotors, then functional requirements can be met, but manufacturing complexity and cost increase

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidbar assembly complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The rotor bars are divided into two distinct assemblies: a first bar assembly with first bars and a second bar assembly with second bars. These assemblies are inserted into alternating bar passages of the rotor core, creating a segmented manufacturing approach that simplifies production while maintaining structural integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The standardized bar design with uniform dimensions and features serves multiple functions: it can be configured as either a first or second bar, fits into different types of bar passages, and can be electrically connected through various end ring configurations. This universal bar design simplifies manufacturing while accommodating diverse rotor requirements

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If traditional end ring joining methods are used, then electrical connectivity is achieved, but material waste and processing time increase

Engineering Contradiction:

Improveelectrical conductivityVSAvoidmaterial waste

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The end rings utilize slots with precise dimensional parameters that accommodate the bar ends. The slot dimensions, bar end dimensions, and interference fit parameters are carefully controlled to achieve reliable electrical and mechanical connections while minimizing material removal and waste

Inventive Principle:

Principle #35Parameter changes

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

The proposed method reduces manufacturing assembly time, complexity, and cost by requiring a single bar shape and efficient joining techniques, enhancing production efficiency and reducing material waste.

Implementation Method 1

joining adjacent second elongated blades and first end body portions to create an electrically conductive first end ring; and joining adjacent first elongated blades and second end body portions to create an electrically conducting second end ring

Methodology Applied

Scientific EffectWelding: Welding

Implementation Method 2

joining adjacent second elongated blades and first end body portions to create an electrically conductive first end ring; and joining adjacent first elongated blades and second end body portions to create an electrically conducting second end ring

Methodology Applied

Scientific EffectInduction heating: Induction Heating

Data Source

PatentUS20260031692A1Induction machine rotor and method of making

Publication Date: 2026.01.29 FCA US LLC

AI summary

A rotor assembly is configured to rotate relative to a stator to drive a rotor shaft and at least one drive wheel of an electric vehicle. The rotor assembly includes a rotor core, and first and second bar assemblies. The rotor core includes a core body that defines a plurality of circumferentially arranged bar passages including a plurality of first bar passages and a plurality of second bar passages. The first bar assembly includes a plurality of first bars, each of the first bars having a first elongated blade portion and a first end body portion. The second bar assembly includes a plurality of second bars, each of the second bars having a second elongated blade portion and a second end body portion. the first bars and the second bars are alternately received at the respective plurality of first bar passages and second bar passages in the core body.