Hollow-Shaft Motor Controller Cooling for Temperature Balance
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Solution Overview
Problem
Existing electric drive devices suffer from temperature imbalance within the controller due to insufficient cooling of the inner circumferential portion, leading to inefficient energy use.
Innovation Solution
The device incorporates a rotary electric machine with a hollow shaft and a housing extending on its outer circumference, featuring shaft holes and vents on the controller's casing, creating a cooling air passage that utilizes negative pressure to draw air through shaft holes and vents for effective cooling of both inner and outer circumferential portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the controller is integrated with the rotary electric machine, then space efficiency is improved, but heat generation and cooling requirements increase
Solution Approach 1:
The patent merges the controller with the rotary electric machine into a single integrated unit, reducing overall device volume and space requirements. The controller is positioned adjacent to the motor housing, forming a compact assembly that maintains efficient cooling pathways while achieving space savings.
Solution Approach 2:
The hollow shaft acts as an intermediary cooling channel, transporting cooling air from the external environment through the shaft holes into the inner circumferential portion of the controller. This intermediary structure enables effective cooling of the integrated assembly without requiring separate cooling systems.
2Quantity of substance
If centrifugal blades are used to generate air flow, then cooling air circulation is improved, but temperature imbalance within the controller deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-cooling the air in the hollow shaft before it enters the controller's internal space. Cooling air is introduced into the shaft and pre-cools components along the shaft path, then this pre-cooled air is delivered to the inner circumferential portion of the controller, ensuring uniform temperature distribution from the start of the cooling process.
Solution Approach 2:
The patent transitions from two-dimensional cooling (air flow along the outer surface) to three-dimensional cooling by utilizing the hollow shaft's internal volume as a cooling conduit. This dimensional change allows cooling air to penetrate directly into the inner circumferential portion, creating a more uniform three-dimensional temperature distribution throughout the controller volume.
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 effectively suppresses temperature imbalance by uniformly cooling the inner and outer circumferential portions of the controller, enhancing energy efficiency and reducing the need for highly heat-resistant components.
Implementation Method 1
when negative pressure is generated at the vent by the cooling air passing through the cooling air passage, this negative pressure causes the air in the internal space of the shaft to be drawn into the cooling air passage through the shaft hole, the internal space of the casing, and the vent
Implementation Method 2
centrifugal blades (a plurality of rotating blades) are attached to the shaft between the rotary electric machine and the controller. As these centrifugal blades rotate, a pressure difference is generated between the internal space of the rotary electric machine and the internal space of the controller, which generates an air flow from the internal space of the controller to the internal space of the rotary electric machine
Data Source
AI summary
An electric drive device includes a rotary electric machine and a controller. The rotary electric machine includes a hollow shaft extending in a prescribed axial direction, and a housing extending in the axial direction on an outer circumference of the shaft, the shaft includes a main body accommodated in the housing, and an extending portion extending from the main body toward the controller, the extending portion is provided with at least one shaft hole, the controller includes a casing extending in the axial direction on an outer circumference of the extending portion, and the casing is provided with at least one vent, and a cooling air passage extending in the axial direction is formed on an outer circumference of the casing, and the cooling air passage is connected to an internal space of the shaft via the shaft hole, an internal space of the casing, and the vent.