Rotary Electric Machine Terminal Cooling via Exposed Ventilation Path
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Solution Overview
Problem
Conventional vehicular AC generators face inefficiencies in heat dissipation from connection terminals due to their positioning away from ventilation passages, leading to ineffective heat removal and potential brush malfunction.
Innovation Solution
A rotary electric machine design where terminal portions are exposed on a ventilation path created by rotating fans, allowing for efficient heat dissipation from both terminals and brushes, with the brushes' cathode connected to the housing for reduced insulation needs and improved cooling, and surfaces treated for enhanced thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connection terminals are embedded in the brush holder away from ventilation passages, then insulation is improved, but heat dissipation deteriorates
Solution Approach 1:
The connection terminals are extracted from the interior of the brush holder and positioned to extend outward, with at least part of the terminal surface exposed outside the brush holder. This allows the terminals to be located away from the insulation material while maintaining proper electrical insulation, enabling efficient heat dissipation to the surrounding environment.
2Temperature
If terminals are exposed on ventilation path, then heat dissipation is improved, but insulation complexity increases
Solution Approach 1:
The brush holder serves dual functions: it provides electrical insulation and acts as a heat dissipation structure. By positioning the connection terminals to extend outward with exposed surfaces, the brush holder itself becomes the insulation barrier while the exposed terminal portions utilize the ventilation path for heat dissipation, merging insulation and cooling functions into a single integrated structure.
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 reduces terminal and brush temperatures, maintaining brush function and extending their lifespan while reducing manufacturing costs and size by optimizing heat dissipation through exposed terminal surfaces and improved airflow.
Implementation Method 1
a cooling airflow generated by rotation of the fans
Implementation Method 2
heat that occurs at the terminals accompanying the energization can be efficiently dissipated
Implementation Method 3
heat generated in the brushes due to the interfacial friction is dissipated from the exposed portions conducting through the terminals
Data Source
AI summary
A rotary electric machine includes a rotating shaft 18 rotatably supported by a housing, a stator including armature windings, a rotor including field cores and field windings, slip rings electrically connected to the field windings, brushes contacted and electrically connected to the slip rings, and a brush holder including the brushes and terminals. The rotor is provided with one or more fans. The terminals include exposed portions exposed at least partially from the brush holder, and the exposed portion are disposed on a ventilation path of a cooling airflow W generated by rotation of the fans. Accordingly, since the exposed portion are disposed on the ventilation path of the cooling airflow, heat caused by an energization can be efficiently dissipated, and heat generated in the brushes due to the interfacial friction is dissipated from the exposed portions.