Balancing Plate Assembly for Air-Gap Oil Exclusion in E-Motors
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Solution Overview
Problem
Existing electric machines in vehicle drive units face challenges such as oil ingress into the air gap, leading to drag losses and decreased efficiency, due to inadequate sealing and high rotor tip velocities.
Innovation Solution
The electromagnetic propulsion unit incorporates a balancing plate assembly with a base plate and an outer plate, featuring an air channel and planar channels that facilitate fluid flow through the air gap, reducing oil ingress and enhancing sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling oil is delivered to cool stator components, then stator cooling is improved, but oil enters the air gap causing drag losses and degraded machine performance
Solution Approach 1:
The patent introduces air as an intermediary substance that forms a barrier between the cooling oil and the air gap. Air is delivered through air passages in the rotor assembly, creating an air cushion that prevents oil from entering the air gap while allowing heat to be dissipated through the rotor structure.
Solution Approach 2:
The patent extracts the harmful oil from the air gap environment by using air flow to counteract oil migration. The air flow actively removes oil particles that attempt to enter the air gap, preventing them from causing drag losses on the rotor surfaces.
2Power
If rotor tip velocity is increased to improve machine performance, then power output is improved, but sealing of the air gap becomes more difficult due to high centrifugal forces
Solution Approach 1:
The patent uses pneumatic principles by introducing pressurized air through passages in the rotor assembly. The air flow creates a pneumatic barrier that counteracts the centrifugal forces generated by high rotor tip velocities, preventing oil from being forced into the air gap despite the high-speed rotation.
Solution Approach 2:
The patent changes the physical parameters of the air gap environment by introducing air flow with specific velocity and pressure characteristics. This modifies the fluid dynamics in the air gap to prevent oil ingress while accommodating high rotor speeds.
3Loss of energy
If air passage arrangement is added to reduce oil in the air gap, then drag losses are reduced, but device complexity increases
Solution Approach 1:
The patent makes the rotor assembly multi-functional by integrating air passages into its structure. The rotor assembly simultaneously performs its primary function of generating electromagnetic torque and the secondary function of delivering air to prevent oil ingress, eliminating the need for separate air delivery components.
Solution Approach 2:
The patent merges the air delivery system with the rotor assembly structure. The air passages are formed as integral parts of the rotor assembly, combining what could have been separate systems into a unified structure, thereby reducing overall device 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 solution effectively reduces drag losses and increases machine efficiency and performance by promoting airflow through the air gap and minimizing oil presence, thereby enhancing customer appeal.
Implementation Method 1
the fluid flow pattern generated around the air gap is conducive for reducing the amount of oil in the air gap by generating the flow of the fluid(s) axially outward through the air gap
Implementation Method 2
the centrifugal forces effectuate the flow of fluids such as air and oil through the air gap
Data Source
AI summary
An electromagnetic propulsion unit for a land-based wheeled or tracked vehicle is provided. The propulsion unit includes a rotor stack, a rotor shaft, and a balancing plate assembly. The balancing plate assembly include a base plate fixating the rotor stack to the rotor shaft, where the base plate includes an air channel that axially extends through the base plate and a planar channel formed between the rotor stack and the base plate and in fluidic communication with the air channel.