Collector Insulation Using PEEK and PPS for High-Temp Dielectric Integrity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrical breakdown occurs during the hardening of impregnating varnish applied to the rotor of alternators, leading to short circuits in the commutator, due to the degradation of dielectric characteristics of materials used in the manufacturing process, particularly at elevated temperatures.
Innovation Solution
The use of high-temperature resistant insulating materials such as PolyEtherEtherKetone (PEEK) polymer for the insert and PolyPhenylene Sulfide (PPS) for overmolding, ensuring dielectric properties are retained above the varnish hardening temperature, and optionally employing pre-overmolding with PEEK to enhance insulation and prevent electrical breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional insulating materials (PPA, PPS) are used for the insert and overmolding, then the manufacturing process is simple and cost-effective, but the dielectric characteristics degrade at elevated temperatures during varnish hardening, causing electrical breakdown
Solution Approach 1:
The patent changes the material parameter (dielectric temperature resistance) by selecting PEEK polymer with a melting point of 370°C for the insert and PPS polymer with a melting point of 300°C for the overmolding. These materials maintain their dielectric characteristics at temperatures above the varnish hardening temperature (150-200°C), preventing electrical breakdown while allowing standard manufacturing processes.
Solution Approach 2:
The patent employs a composite structure combining two different polymers: PEEK for the insert requiring high temperature resistance and PPS for the overmolding providing insulation and structural support. This composite material approach allows each component to be optimized for its specific functional requirements, with the PEEK insert maintaining integrity at high temperatures and the PPS overmolding providing additional insulation.
2Reliability
If the insert material has high melting temperature (PEEK at 370°C), then dielectric integrity is maintained during varnish hardening, but the manufacturing complexity increases due to the need for pre-overmolding and material selection
Solution Approach 1:
The patent applies pre-overmolding with PEEK material on the conductive element before the final overmolding step. This preliminary action ensures that the critical insulation layer is already in place and positioned correctly before the main manufacturing process, preventing electrical breakdown during subsequent high-temperature operations without requiring complex post-processing or assembly steps.
Solution Approach 2:
The patent implements a nested structure where the PEEK insert is placed inside the PPS overmolding. The PEEK insert serves as an inner core providing high-temperature dielectric strength, while the PPS overmolding acts as an outer layer providing additional insulation and structural support. This nested arrangement allows both materials to work together synergistically, maintaining reliability while using standard molding processes.
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
Prevents electrical breakdown and short circuits by maintaining dielectric integrity at high temperatures, ensuring reliable electrical insulation and preventing creep or loss of thickness during the molding process.
Implementation Method 1
a material that retains its dielectric characteristic at least up to a temperature above a hardening temperature of an impregnating varnish applied to a rotor of the electrical machine
Implementation Method 2
an electric current is caused to flow in the excitation coil of the rotor in order to cause, by Joule effect, a rise in the temperature of the rotor. This rise in temperature accelerates the hardening of the varnish in the rotor
Data Source
Figure 1~4
Figure 3~5
AI summary
The collector has electric conduction rings (2a, 2b) provided with annular internal parts, and conducting elements (1a, 1b) whose ends are in electrical contact with the annular internal parts of the electric conduction rings. Pieces (3) are made of an insulating plastic material to prevent electric breakdown in the collector. A mold (4) is made of another plastic material, and partly covers the rings, the conducting elements and the pieces. The mold is provided with an annular part at which electric connection cable lugs of the conducting elements are fixed.