Rotary Electric Machine Cooling Structure for Sensor Accuracy
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Solution Overview
Problem
Conventional rotary electric machines face detection errors due to heat produced, which affects the accuracy of rotation sensors, and existing cooling structures do not adequately address this issue.
Innovation Solution
A rotary electric machine with a cylindrical housing featuring a coolant passage that meanders in the axial direction, where the passage width varies radially, and the circumferential passage has a narrowed input and output area with an expanded intermediate section, reducing flow rate changes and preventing coolant stagnation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conventional cooling passage is provided in the housing, then cooling function is provided, but coolant stagnation and flow separation occur reducing cooling efficiency
Solution Approach 1:
The patent applies local quality by varying the passage width along the axial direction of the cooling passage. The passage width is set to be different at different locations (narrower at inlet/outlet, wider at intermediate sections) to optimize flow characteristics at each specific location, preventing stagnation and flow separation while maintaining effective cooling.
2Ease of manufacture
If the cooling passage has uniform width, then manufacturing is simple, but flow rate changes and stagnation occur
Solution Approach 1:
The patent applies parameter changes by modifying the passage width parameter along the axial direction of the cooling passage. The width transitions from narrower at the inlet and outlet to wider at the intermediate sections, creating an optimized flow profile that enhances cooling performance while remaining manufacturable.
3Device complexity
If the cooling passage is located away from the rotation sensor, then sensor protection from heat is reduced, but structural simplicity is maintained
Solution Approach 1:
The patent applies local quality by providing enhanced cooling specifically at the location of the rotation sensor through the optimized passage width configuration. The intermediate sections with wider width create favorable flow conditions that direct coolant effectively toward the sensor area, providing localized thermal protection without requiring separate cooling structures.
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 enhances cooling efficiency, maintains detection accuracy of the rotation sensor, and reduces pressure loss, ensuring effective cooling of the sensor and other components while minimizing stagnation and flow separation.
Implementation Method 1
a coolant passage having an annular shape is provided between the inner wall portion and the outer wall portion to allow a coolant to flow through the coolant passage
Data Source
AI summary
A rotary electric machine includes a cylindrical portion. In the cylindrical portion, a coolant passage having annular shape is formed to allow the coolant to flow therethrough. The coolant passage is formed meandering in the axial direction and the passage width of the coolant passage in a first end side in the radial direction is narrower than the passage width in the radial direction in the second end side. The coolant passage includes a circumferential passage in the first end side where the coolant flows in the circumferential direction. The circumferential passage is configured such that a passage opening area of an intermediate portion between an input portion in an upstream side of the coolant passage and an output portion in a downstream side of the coolant passage is expanded compared to those of the input portion and the output portion.