Electric Drive Winding-Head Cooling with Gravity Oil Distribution
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Solution Overview
Problem
Thermal management and lubrication challenges in electric drive systems, particularly in compact spaces, where efficient cooling and lubrication of rotating components are essential to prevent overheating and ensure long service life, especially under varying driving conditions.
Innovation Solution
An electric drive assembly with a multi-part housing featuring an electric machine and transmission, utilizing fluid distribution elements that cover a significant axial length of the stator winding heads, allowing coolant to flow via gravity, eliminating the need for nozzles and optimizing space usage, and incorporating a separate reservoir for active lubrication to manage oil levels and prevent splash losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fluid distribution elements are used to cool winding heads, then cooling efficiency is improved, but device complexity increases
Solution Approach 1:
The fluid distribution element utilizes gravity to distribute coolant automatically without requiring additional pumps or complex control systems. The element passively receives coolant from the cooling system and distributes it across the winding head surface, allowing the system to self-regulate coolant flow based on gravitational force and system pressure.
Solution Approach 2:
The fluid distribution element serves multiple functions: it acts as both a coolant distribution mechanism and a structural component that can be integrated into the housing or mounting structure. This multi-functionality reduces the need for separate dedicated cooling components, thereby reducing overall device complexity.
2Temperature
If coolant is distributed over large circumferential area, then cooling coverage is improved, but fluid flow control becomes more difficult
Solution Approach 1:
The fluid distribution element features a gradient structure where the circumferential extension varies along the axial direction. This creates different local flow characteristics - areas with greater circumferential extension provide broader coolant distribution, while areas with lesser extension provide more concentrated flow. This local variation optimizes cooling coverage while maintaining manageable flow control.
3Temperature
If fluid distribution element covers large axial length, then cooling effectiveness is improved, but manufacturing complexity increases
Solution Approach 1:
The fluid distribution element employs a gradient in circumferential extension along the axial direction, creating a continuously varying geometric parameter. This parameter change allows the element to cover a large axial length with optimized cooling distribution while maintaining manufacturability through standardized forming processes for gradient structures.
4Quantity of substance
If separate reservoir is used for active lubrication, then oil level control is improved, but device complexity increases
Solution Approach 1:
The lubrication system is segmented into a separate reservoir and the main transmission housing. This segmentation allows independent control of oil levels in the reservoir, enabling precise management of lubricant quantity for active lubrication without affecting the overall transmission oil level. The separation facilitates targeted oil supply to specific bearing or gear regions.
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 provides reliable and efficient cooling and lubrication of the stator winding heads, enhancing the electric drive's efficiency and service life while minimizing installation space and preventing transmission splash losses, even under dynamic conditions.
Implementation Method 1
Coolant supplied to the fluid distribution element can thus be distributed in the circumferential direction and flow onto the winding head in several angular positions
Implementation Method 2
Both the electric machine and the transmission generate heat, which must be dissipated in order to avoid unacceptably high temperatures and thus promote a long service life
Implementation Method 3
A sufficient oil level must be set to ensure good lubrication and cooling of shafts, gears and bearings
Data Source
AI summary
An electric drive assembly comprises a housing, an electric machine with a stator and a rotor, the stator having a stator core and winding heads, the rotor being connected to a rotor shaft, which is rotatably mounted in the housing about an axis of rotation, a transmission rotationally drivable by the rotor shaft, at least one fluid distribution element for supplying coolant to one of the winding heads, wherein the fluid distribution element at least partially covers an upper part of the winding head in the circumferential direction and in the axial direction and has a guide structure with a gradient in the circumferential direction, so that coolant supplied to the fluid distribution element from above is distributed in the circumferential direction and runs onto the winding head in several angular positions over a circumferential area of at least 30° with respect to the axis of rotation.