Auxiliary Rectifier Thermal Management in Brushless Alternators
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Solution Overview
Problem
Brushless automotive alternators face challenges in minimizing the temperature of auxiliary rectifying elements and bearings due to increased heat transfer and limited cooling capabilities, which affects their service life and efficiency.
Innovation Solution
The alternator design includes auxiliary rectifying elements arranged between the bearing and protective cover, away from the heat sink, with a barrier to prevent direct heat transfer and an air guide wall to introduce fresh cooling air, enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power output of the alternator is increased, then the power generation capability is improved, but the temperature of the rectifier and auxiliary diodes increases significantly
Solution Approach 1:
The patent relocates the auxiliary diodes from the radial direction (on the heat sink surface) to the axial direction (between the bearing and protective cover), utilizing the previously unused axial space. This dimensional relocation separates the auxiliary diodes from the heat sink's thermal field, allowing them to be cooled independently from the main rectifying elements while maintaining high power output capability.
Solution Approach 2:
The patent segments the cooling system into two independent zones: one for the main rectifying elements (on the heat sink) and another for the auxiliary diodes (in the axial space). This segmentation allows different cooling strategies to be applied to different components based on their specific thermal requirements and operational characteristics.
2Temperature
If the outer diameter of the cooling fan is increased to suppress temperature rise, then the cooling capability is improved, but the alternator outer diameter exceeds the normalized dimension limit
Solution Approach 1:
Instead of increasing cooling capacity in the radial direction (larger fan diameter), the patent utilizes the axial dimension by relocating auxiliary diodes to the axial space between the bearing and protective cover. This allows effective cooling without increasing the alternator's radial footprint, maintaining compliance with normalized dimension standards.
3Device complexity
If auxiliary diodes are arranged on the heat sink surface, then the structure is simplified, but the auxiliary diodes receive excessive heat from the heat sink
Solution Approach 1:
The patent moves auxiliary diodes from the radial plane (heat sink surface) to the axial direction (between bearing and protective cover), creating spatial separation from the heat sink. This dimensional relocation eliminates the heat transfer problem while maintaining structural efficiency.
Solution Approach 2:
The patent introduces a barrier wall as an intermediary structure between the heat sink and the protective cover. This barrier serves as a thermal isolation element, preventing heat from the heat sink from transferring to the auxiliary diodes located in the axial space, while still allowing for compact overall design.
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 the temperature of auxiliary rectifying elements and bearings by minimizing heat transfer and improving cooling airflow, resulting in a longer service life and improved performance.
Implementation Method 1
a heat sink having the main rectifying elements provided thereon and working to dissipate heat generated by operation of the main rectifying elements
Implementation Method 2
dissipate heat generated by operation of the main rectifying elements
Implementation Method 3
a cooling fan working to cool the bearing and the auxiliary rectifying elements
Data Source
AI summary
According to the present invention, a brushless alternator includes a stationary field winding, a rotor with a rotary shaft, a bearing rotatably supporting an end portion of the rotary shaft, a stator, a protective cover, and a rectifier covered by the protective cover. The rectifier includes a plurality of main rectifying elements for providing a DC output of the alternator, a heat sink having the main rectifying elements provided thereon and working to dissipate heat generated by the main rectifying elements, and a plurality of auxiliary rectifying elements for supplying DC field current to the field winding. The auxiliary rectifying elements are arranged in an axial space between the bearing and the protective cover and kept away from the heat sink. With such an arrangement, it is possible to minimize heat transfer from the heat sink to the auxiliary rectifying elements, thereby minimizing the temperature of the auxiliary rectifying elements.