Copper-impregnated polymer bars for induction motor rotors
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Solution Overview
Problem
The high cost and engineering challenges associated with casting integral copper squirrel cage rotors for dynamo-electric machines, including tool damage, increased production costs, and structural integrity issues, hinder the widespread adoption of copper-based conductive bars due to the difficulties in handling molten copper and maintaining efficiency.
Innovation Solution
The use of copper-impregnated polymer bars, which allow for improved efficiency without the need for expensive manufacturing techniques and minimize structural damage, by forming bars that extend through arcuately spaced slots in a rotor core, providing enhanced conductivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If copper casting materials are used to form integral copper squirrel cage rotors, then electrical conductance and motor efficiency are improved, but manufacturing cost and production complexity increase significantly
Solution Approach 1:
The patent uses composite materials by combining copper particles or powder with a polymer matrix to create copper-impregnated polymer bars. This composite approach provides the electrical conductivity benefits of copper while using cheaper polymer materials for the structural component, significantly reducing manufacturing cost compared to pure copper casting.
Solution Approach 2:
The invention changes the physical state and form of copper from molten metal (requiring high-temperature casting) to copper particles or powder embedded in polymer. This parameter change allows the use of lower-cost polymer processing techniques while maintaining electrical conductivity, resolving the contradiction between efficiency improvement and manufacturing cost.
2Strength
If high pressure die casting methods are used for copper squirrel cage rotors, then structural integrity is improved, but tool damage and equipment cost increase
Solution Approach 1:
The patent changes the processing temperature parameter from high-temperature copper casting (requiring specialized expensive equipment) to lower-temperature polymer processing. This allows the use of standard injection molding equipment instead of costly high-pressure die casting machinery, reducing equipment investment while maintaining structural integrity through the polymer matrix.
Solution Approach 2:
The invention replaces expensive, durable copper casting tools with cheaper polymer processing tools. The polymer-based bars can be manufactured using less expensive injection molding equipment that doesn't require the specialized high-temperature resistance of copper casting tools, reducing capital expenditure.
3Loss of energy
If molten copper is used for casting, then electrical conductance is improved, but thermal damage to rotor core and coating burn off occur
Solution Approach 1:
The patent changes the temperature parameter from molten copper temperatures (exceeding 1000°C) to polymer processing temperatures (typically below 200°C). This dramatic temperature reduction eliminates thermal damage to the rotor core and prevents coating burn-off while maintaining electrical conductivity through copper particles embedded in the polymer matrix.
Solution Approach 2:
The polymer matrix acts as an intermediary material that protects the rotor core from direct exposure to extreme heat. Instead of pouring molten copper directly into the rotor slots, the copper particles are embedded in the polymer, which then sets at low temperature, preventing thermal damage while still providing electrical conductivity.
4Loss of energy
If copper alloy casting is used, then conductivity is improved, but warping, welding, and coating burn off of rotor core occur
Solution Approach 1:
The invention changes the processing temperature from copper casting temperatures to polymer curing temperatures. This parameter change prevents the thermal effects that cause warping, welding, and coating burn-off of the rotor core, while the copper particles in the polymer maintain electrical conductivity without compromising rotor core integrity.
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 enables the construction of dynamo-electric machines with improved efficiency and extended lifespan, reducing production costs and minimizing collateral damage to the rotor core, while maintaining the benefits of copper conductivity.
Implementation Method 1
Each of the bars comprises copper-impregnated polymer
Data Source
AI summary
A rotating element for a dynamo-electric machine such as an electric induction motor. The rotating element includes a plurality of axially stacked laminations cooperatively defining a plurality of arcuately spaced bar slots. The rotating element also includes a plurality of bars, with each bar extending through one of the bar slots. Each of the bars comprises copper-impregnated polymer.