Vehicle Rotating Electric Machine Radial Cooling Inversion
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Solution Overview
Problem
Conventional rotating electric machines for vehicles experience significant power loss and reduced cooling performance due to the inefficiency of air flow through cooling fins, leading to inadequate heat dissipation for switching elements in the inverter module.
Innovation Solution
The design incorporates a cooling fan and a ventilation system with a cover that allows outside air to flow through ventilation holes, creating a path for air to be sucked in and discharged, enhancing cooling performance while maintaining a compact size by utilizing both inside and outside heat sinks with cooling fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is made to flow through cooling fins in the radial direction, then cooling function is provided, but cooling performance deteriorates because warmed air flows into the next cooling fin
Solution Approach 1:
The patent inverts the conventional cooling air flow direction by introducing ventilation holes in the radially outer circumferential portion of the cover. This allows outside air to be drawn in radially inward, opposite to the conventional radial outward flow, thereby ensuring that cooled air reaches all cooling fins without being contaminated by warmed air from previous fins, significantly improving cooling performance and reducing power loss
2Device complexity
If power element unit is located on heat sink at one end in axial direction, then structure is simplified, but cooling performance is reduced due to inefficient air flow
Solution Approach 1:
The patent transitions from conventional radial cooling fin arrangement to a three-dimensional cooling structure by positioning switching elements of upper and lower arms adjacent to each other in the axial direction. This axial arrangement combined with radially inward air flow creates an efficient three-dimensional cooling path that improves heat dissipation without increasing structural complexity
3Loss of energy
If switching elements are cooled efficiently, then power loss is reduced, but device size may increase due to additional cooling components
Solution Approach 1:
The cover serves multiple functions: it encloses the power element unit, provides structural support, and crucially, incorporates ventilation holes that enable efficient cooling air intake. The housing simultaneously acts as structural enclosure and cooling air passage. This multi-functionality achieves superior cooling performance without increasing device volume, as the same components perform both structural and cooling functions
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 significantly improves the cooling performance of switching elements and allows for a smaller-sized rotating electric machine by ensuring continuous cooling with fresh outside air, reducing power loss and enhancing overall efficiency.
Implementation Method 1
When the cooling fan is brought in rotation, outside air flows in through a ventilation hole from a radially outer circumferential portion to a radially inner circumferential portion with respect to switching elements of an upper arm and a lower arm
Implementation Method 2
a power element unit containing an inverter module is located in a circumferential direction on a heat sink
Implementation Method 3
a cooling air is made to flow in flow paths of cooling fins one after another along the cooling fins provided with the flow paths in the radial direction, thereby cooling the heat sinks
Data Source
AI summary
A rotating electric machine for vehicles is capable of improving a cooling performance of switching elements forming an inverter module, and small-sizing the entire rotating electric machine. The rotating electric machine includes: a stator; a rotor, a cooling fan; a front bracket and a rear bracket; and a cover; and in which a pair of switching elements are disposed axially adjacent to each other between the rear bracket and the cover; a ventilation hole for sucking outside air is formed in a radially outer circumferential portion of the cover; and by rotation of the cooling fan, the outside air flows radially from the ventilation hole with respect to the switching elements and goes through a suction port and is discharged through a discharge port.