Stator Piloting Tabs for Concentricity and Oil Cooling
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Solution Overview
Problem
In electric machines with long axial lengths compared to diameter, maintaining proper concentricity between the stator and housing while facilitating heat removal through an oil film is challenging, and traditional piloting methods require excessive machining and may hinder oil reach to the stator.
Innovation Solution
The stator laminations are designed with piloting tabs on their perimeter, which form axially extending serrated edge portions and housing contact pads, allowing for improved coolant flow and heat exchange without increasing steel consumption, by strategically placing these features near mounting ears and rotating them during assembly to optimize contact surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional piloting methods are used to maintain concentricity between stator and housing, then concentricity is maintained, but excessive machining is required and oil cannot reach the stator for heat removal
Solution Approach 1:
The piloting function is segmented from the main stator body by adding separate piloting tabs on the laminations. These tabs create discrete contact pads on the housing that provide piloting support without requiring extensive machining of the housing itself. The segmentation allows oil to flow to the main stator body while the piloting tabs maintain concentricity through localized contact points.
2Stability of the object's composition
If piloting features are added to maintain concentricity, then concentricity is improved, but steel consumption increases
Solution Approach 1:
Instead of adding substantial piloting features throughout the stator structure, the invention applies piloting tabs only at specific locations on the lamination perimeter. These localized tabs provide the necessary concentricity control while minimizing additional steel consumption. The tabs are positioned to contact specific areas on the housing, creating local quality improvements without global material increase.
3Temperature
If contact surface area is increased for heat exchange, then heat removal is improved, but machining requirements increase
Solution Approach 1:
The piloting tabs on the laminations serve dual functions: they maintain concentricity and create contact pads for heat exchange. The tabs themselves become the heat transfer interface with the housing, eliminating the need for separate machining operations to create cooling contact surfaces. The structure serves itself by using the piloting features as both positioning and thermal management elements.
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 heat exchange by increasing the contact surface area for coolant flow, maintaining concentricity, and reducing machining needs, thereby improving the thermal management of electric machines.
Implementation Method 1
facilitating heat removal through an oil film
Implementation Method 2
increasing the contact surface area for coolant flow
Data Source
AI summary
A stator includes a plurality of same laminations each defining a piloting tab on a perimeter thereof, and stacked to form a stator body and such that the piloting tabs define at least two axially extending serrated edge portions spaced apart from one another around a perimeter of the stator body or at least two sets of axially aligned housing contact pads spaced apart from one another around the perimeter.