Vehicle AC Generator Frame Cooling Air Deflection
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Solution Overview
Problem
Conventional vehicle AC generators face challenges in achieving compact size, low weight, high output power, and high efficiency while minimizing noise, as increasing cooling air volume leads to upsizing and increased fan driving power, resulting in large wind noise and insufficient stator coil cooling capacity.
Innovation Solution
The design incorporates a frame structure with a bent coil-end-facing portion and recesses on the inner end surface of the coil-end-facing portion, which deflects cooling air to enhance cooling performance and reduce noise by creating a vortex flow and increasing the axial clearance for better insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling air volume is increased to improve stator coil cooling capacity, then the cooling performance is improved, but the generator size increases and wind noise increases
Solution Approach 1:
The coil-end-facing portion is bent at a predetermined curvature radius toward the coil end of the stator coil, creating a curved surface that deflects cooling air more effectively onto the coil end without requiring increased cooling air volume or generator size
Solution Approach 2:
The bent coil-end-facing portion concentrates cooling air flow specifically at the coil end region where it is most needed, providing localized enhanced cooling without increasing overall cooling air volume
2Temperature
If the cooling air volume is increased to improve stator coil cooling capacity, then the cooling performance is improved, but the fan driving power increases
Solution Approach 1:
The curved coil-end-facing portion optimizes the deflection of cooling air to directly impinge on the coil end, improving cooling efficiency without requiring increased cooling air volume, thus maintaining lower fan driving power
3Temperature
If the cooling air volume is increased to improve stator coil cooling capacity, then the cooling performance is improved, but the wind noise increases
Solution Approach 1:
The bent coil-end-facing portion efficiently directs cooling air onto the coil end with a curved surface that reduces turbulence and air flow instability, thereby reducing wind noise while maintaining effective cooling
Solution Approach 2:
By concentrating cooling air flow precisely where needed at the coil end through the bent portion, the system achieves effective cooling with lower overall cooling air volume, reducing wind noise generation
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 improves stator coil cooling performance and reduces wind noise, achieving a balance between compact size, high efficiency, and low weight while maintaining high output power.
Implementation Method 1
the cooling air, which is being blown radially outward along an inner end surface of the end wall section by the centrifugal blades (cooling fan) mounted to a rotor end surface
Implementation Method 2
to satisfactorily cool the coil end by deflecting the cooling air, which is being blown radially outward along an inner end surface of the end wall section by the centrifugal blades
Data Source
AI summary
The vehicle AC generator includes a frame including an end wall section and a peripheral wall section, a stator core, a stator coil having rear and front coil ends projecting axially rearward and frontward respectively from the stator core, a rotor supported by the frame, and a cooling fan having centrifugal blades and fixed to the rotor. The peripheral wall section has a cooling air discharge opening adjoining the end wall section. The end wall section has a centrifugal-blade-facing portion axially facing the centrifugal blades, and a coil-end-facing portion axially facing the rear coil end. The coil-end-facing portion is bent at a predetermined curvature radius and extending from the centrifugal-blade-facing portion to the cooling air discharge opening. The inner end surface of the coil-end-facing portion is formed with a recess located axially rearwardly of a radial extension line of an inner end surface of the centrifugal-blade-facing portion.