Trapezoidal Stator Coil Ends for Vehicle Motor Heat Dissipation
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Solution Overview
Problem
Conventional rotating electric machines for vehicles face reduced heat dissipation properties due to the use of generally U-shaped segment conductors, which limits their cooling efficiency despite being designed to be small in size and high in output.
Innovation Solution
The rotating electric machine features a stator coil with conducting wires having a trapezoidal cross-section protrusion from the slots, enhancing the contact area with refrigerant for improved heat dissipation, and incorporates insulating paper with an overlap section for increased reliability and cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If U-shaped segment conductors are inserted into slots, then the rotating electric machine can be made compact, but heat dissipation properties deteriorate
Solution Approach 1:
The patent applies local quality by creating a protruding portion with a specific shape (trapezoidal, rectangular, or semicircular cross-section) at the coil end portion that contacts the refrigerant. This localized structural modification enhances heat transfer efficiency at the cooling interface without changing the overall machine size, thereby resolving the contradiction between compactness and heat dissipation.
2Length of moving object
If coil end height in axial direction is reduced, then the rotating electric machine becomes more compact, but heat dissipation properties worsen
Solution Approach 1:
The patent resolves this contradiction by transitioning from a two-dimensional flat coil end surface to a three-dimensional protruding structure. The protruding portion extends axially from the coil end, creating additional heat transfer surface area in the axial direction. This dimensional change allows effective heat dissipation even when the overall axial height of the coil end is reduced, maintaining cooling efficiency while achieving compactness.
3Temperature
If trapezoidal cross-section conducting wires are used, then heat dissipation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the conducting wire (creating protruding portions with trapezoidal, rectangular, or semicircular cross-sections) to enhance heat dissipation. These parameter modifications are achieved through standard wire forming and shaping techniques, which, while slightly more complex than using simple round wires, remain within conventional manufacturing capabilities and do not significantly increase overall manufacturing complexity.
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 increases the cooling performance of the rotating electric machine by enhancing heat transfer without increasing the axial height of the coil end, ensuring efficient heat dissipation and improved reliability even at high operating voltages.
Implementation Method 1
a cross section of a protruding portion of each of the conducting wires that protrudes from the slots in a coil end portion of the stator coil is formed into a substantially trapezoidal shape... the refrigerant discharged from the outlet port contacts with the protruding portions
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A rotating electric machine (RM) for driving a vehicle includes: a stator (20) that comprises a stator core (21) in which a plurality of slots (25) extending in a direction of a rotation axis are arranged circumferentially and a stator coil inserted into the slots (25); and a rotor (10) that is rotatably provided in the stator (20) through a gap, wherein: the stator coil is constituted with conducting wires, and a cross section of a protruding portion of each of the conducting wires that protrudes from the slots (25) in a coil end portion (60A, 60B) of the stator coil is formed into a substantially trapezoidal shape (300).