Rotary Electric Machine Cooling via Axial Plate Extension
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Solution Overview
Problem
Existing rotating electrical machines face challenges in cooling performance due to increased size and pressure loss of external air, which reduces the amount of cooling air supplied and the coolability of components like diodes, especially when the opposing plate is positioned farther radially or brought closer axially to restrict size growth.
Innovation Solution
The design features a sequential reduction in size of the rectifying units, circuit boards, and heat sinks radially away from the frame, creating gaps for increased cooling air flow and reducing overall machine size while enhancing cooling performance by optimizing air flow paths and fin configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the opposing plate is disposed farther to the radial direction outer side than the outer peripheral face of the cover, then the cooling performance is improved, but the rotating electrical machine increases in size
Solution Approach 1:
The patent introduces a third dimension (axial direction) to resolve the radial space conflict. By forming the opposing plate to extend in the axial direction beyond the cover's outer peripheral face, the design creates additional cooling surface area without increasing the radial footprint, thus improving cooling performance while maintaining compact overall dimensions.
Solution Approach 2:
The opposing plate is segmented into multiple regions: a first region that overlaps with the cover's outer peripheral face in the radial direction, and a second region that extends beyond it. This segmentation allows the plate to serve dual purposes - maintaining structural alignment with the cover while providing extended cooling surface area in the axial direction.
2Volume of moving object
If the axial direction flow path is narrowed by bringing the opposing plate nearer to the outer peripheral face of the cover to restrict size increase, then the size is reduced, but pressure loss of external air increases and cooling performance decreases
Solution Approach 1:
Instead of narrowing the axial flow path, the patent compensates by extending the opposing plate in the axial direction. This creates additional cooling surface area that offsets the reduced flow path width, maintaining cooling effectiveness while keeping the radial size compact. The extended axial portion provides alternative cooling pathways.
Solution Approach 2:
The opposing plate exhibits different functional qualities in different regions: the first region (overlapping the cover) maintains structural alignment and provides baseline cooling, while the second region (extending beyond) specifically addresses cooling needs in the extended axial zone. This local differentiation optimizes cooling distribution without uniformly increasing size.
3Temperature
If cooling air flows axially from the inlet port and changes orientation by 90 degrees at the entrance to the flow path between support frame and heat sink, then cooling is provided, but centrifugal force biases air toward the support frame creating separation regions that block flow paths
Solution Approach 1:
The patent introduces curved surfaces and inclined planes on the opposing plate to gradually redirect airflow. Instead of abrupt 90-degree turns that cause centrifugal separation, the curved geometries guide air flow smoothly around the heat sink, reducing flow resistance and preventing separation regions while maintaining effective cooling.
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 design enhances the coolability of heat-generating parts and restricts the overall size increase of the rotating electrical machine, improving cooling performance while maintaining efficient air flow and reducing pressure loss.
Implementation Method 1
a positive side radiation fin and a negative side radiation fin made of metal in which the rectifying elements are press-fit into the mounting holes
Implementation Method 2
external air is led between a support frame and the heat sink along an axial direction flow path
Implementation Method 3
the support frame is on an inner side and the heat sink is on an outer side, because of which the cooling air is biased toward the support frame due to the effect of centrifugal force
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Radial direction outer side sizes of a first rectifying unit, a circuit board, and a second rectifying unit configuring a rectifying device are disposed so as to be sequentially smaller in a direction away from a frame of a rotating electrical machine main body, and at predetermined intervals, a cover covering the rectifying device has a cover end wall portion positioned farther to an outer side in an axial line direction than the rectifying device, a cover outer wall portion positioned farther to an outer side in a radial direction than the rectifying device, and a cover intermediate portion interposed between the cover end wall portion and the cover outer wall portion, an inner peripheral side inlet portion is formed in the cover end wall portion, an outer peripheral side inlet portion is formed in the cover intermediate portion, and the outer peripheral side inlet portion is formed of an axial direction covering portion existing in a position nearer the rotating electrical machine main body than the cover end wall portion, and a radial direction covering portion that connects the axial direction covering portion and an outer peripheral portion of the cover end wall portion.