Electric Motor Cooling Circuit With Interference-Fit Stator Sealing
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Solution Overview
Problem
The industry seeks to reduce the weight and dimensions of electric motors in motor vehicles while increasing torque and power density, cooling the motor efficiently with minimal changes to the rotor and stator, and facilitating installation, while also minimizing the number of components.
Innovation Solution
An electric motor design featuring a tubular stator with a coaxially housed rotor, a cooling circuit using dielectric oil, and interference coupling between the stator and casing for fluid tightness, reducing the need for additional gaskets and enhancing torque and power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional cooling methods are used with separate gaskets and seals, then cooling function is provided, but device complexity and number of components increase
Solution Approach 1:
The patent combines the cooling circuit function and sealing function into the interference fit connection between stator and casing. The interference fit simultaneously provides mechanical support, sealing, and cooling circuit containment, eliminating the need for separate gaskets and seals. This merging of functions directly reduces component count while maintaining cooling efficiency.
Solution Approach 2:
The interference fit connection serves multiple functions: mechanical support, sealing, and cooling circuit containment. This multi-functional design allows a single structural feature to address multiple requirements, reducing overall device complexity while maintaining effective cooling.
2Temperature
If additional cooling components and gaskets are added, then cooling function is improved, but weight and dimensions increase
Solution Approach 1:
The cooling circuit is integrated into the existing interference fit structure between stator and casing, eliminating the need for additional cooling components, gaskets, and seals. This integration maintains effective cooling while minimizing weight by reusing existing structural elements for multiple purposes.
3Ease of operation
If traditional mounting methods are used, then installation is straightforward, but torque and power density are limited
Solution Approach 1:
The patent employs interference fit with specific dimensional tolerances and material properties to achieve both secure mounting and high torque transmission. By optimizing the interference parameters (dimensions, materials, fit tolerance), the design achieves enhanced torque density while maintaining installation feasibility through standardized manufacturing processes.
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
The design achieves reduced weight and dimensions, increased torque and power density, efficient cooling, and simplified installation, with dielectric oil preventing short circuits and minimizing component count.
Implementation Method 1
The stator is mounted through interference inside the casing so as to discharge the reaction torque onto the casing itself
Implementation Method 2
a cooling circuit (50), through which a heat transfer fluid, in particular dielectric oil, can flow and which is thermally coupled to the stator (3) so as to remove heat from it
Data Source
Figure 1
Figure 2
AI summary
An electric motor (2) for a motor vehicle (1), comprising a stator (3), which is fixed relative to an axis (A); a rotor (4), which can rotate around the axis (A) relative to the stator (3); a casing (30) housing the rotor (4) and the stator (3); a cooling circuit (50), through which a heat transfer fluid can flow and which is thermally coupled to the stator (4) to remove heat from it; the cooling circuit (50) comprises, in turn, an inlet mouth (51) defined by the casing (30) and crossed by the fluid having a first temperature; and an outlet mouth (52) crossed by the fluid having a second temperature higher than the first temperature; the cooling circuit (30) further comprises, proceeding from said inlet mouth (51) towards said outlet mouth (52): a first branch (55) delimited between the casing (30) and the stator (3); and a second branch (56) going through the stator (3).