Electric Axle Drive Bearing Channel for Rotor Oil Cooling
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Solution Overview
Problem
Existing axle drives for motor vehicles with electric machines face challenges in efficiently supplying cooling fluid to the rotor shaft, particularly in coaxial designs, where traditional methods require separate elements and can lead to strength, drag loss, and cost issues due to the need for holes and rotary passages.
Innovation Solution
The proposed axle drive incorporates a bearing element with a fluid channel that conveys liquid from an intermediate space between the bearing element and the side shaft into the rotor chamber, eliminating the need for central or side shaft holes and utilizing rotational pressure to distribute fluid, thereby enhancing strength, reducing drag losses, and lowering costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If holes and rotary passages are created in the central shaft or side shaft to supply cooling fluid, then the cooling fluid can be delivered to the rotor, but the structural strength decreases and manufacturing complexity increases
Solution Approach 1:
The patent introduces an intermediary fluid supply means consisting of a fluid line connected to a fluid channel in the bearing element. This mediator transfers cooling fluid from the oil pan to the intermediate space between the bearing element and side shaft, and then to the rotor chamber, avoiding the need for holes in the shafts while maintaining cooling functionality
Solution Approach 2:
The patent replaces the mechanical system of shaft-mounted rotary passages with a fluid dynamic system. The fluid supply means utilizes the rotational movement of the shaft to generate rotational pressure that distributes the cooling fluid through the intermediate space to the rotor, eliminating complex mechanical fluid pathways in the shaft
2Temperature
If separate fluid conveying elements are added to deliver cooling fluid to the rotor, then cooling can be achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The bearing element is given a dual function: it continues to support the shaft mechanically while also serving as a fluid distribution component with integrated fluid channels. This eliminates the need for separate fluid conveying elements by making the existing bearing structure perform both mechanical and fluid delivery functions
Solution Approach 2:
The system utilizes the inherent rotational movement of the shaft to generate the pressure needed for fluid distribution. The rotational pressure automatically distributes the cooling fluid from the fluid channel through the intermediate space to the rotor chamber without requiring additional pumps or complex control mechanisms
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 supplies cooling fluid to the electric machine while improving structural integrity and reducing fluid distribution complexity, ensuring efficient lubrication and cooling of the rotor without separate fluid conveying elements, thus enhancing the overall performance and efficiency of the axle drive.
Implementation Method 1
a liquid, in particular oil, is conveyed into an intermediate space between a bearing element (8) and a side shaft (11) through a channel (16) in the bearing element (8)
Implementation Method 2
The liquid can then enter the intermediate space from the fluid channel, from where it can be conveyed into the rotor chamber
Data Source
AI summary
An axle drive for a motor vehicle, comprising an electric machine coupled by a rotor shaft to a transmission for the axle drive, wherein a torque can be transferred from the electric machine to an intermediate shaft with a first gear stage and from the intermediate shaft to another gear train, in particular a differential, with a second gear stage, wherein the rotor shaft or a shaft segment coupled to the rotor shaft is supported in a bearing element, wherein a fluid supply is designed to convey a liquid, in particular oil, into an intermediate space between the bearing element and a side shaft on the axle drive through a fluid channel, and from the intermediate space into the rotor chamber in the electric machine.