Stalactite Passive Lubrication for EV Drive Units
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Solution Overview
Problem
Current splash lubrication systems for electric vehicle drive units face challenges in providing sufficient and metered lubrication to high-speed pinion bearings and rotor cooling, especially at varying vehicle speeds and temperatures, due to reliance on passive gravity flow which is inefficient and difficult to direct effectively.
Innovation Solution
A stalactite passive lubrication system is introduced, featuring a stalactite member positioned above components that need lubrication, directing splashed lubricant droplets by gravity into a sump, with a sump extension and flow passages ensuring lubricant reaches critical areas, and an optional mechanical pump for pressurized flow, using a check valve to prevent backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive splash lubrication is used, then the system structure is simple, but sufficient and metered lubrication to high-speed pinion bearings and rotor cooling is difficult to achieve
Solution Approach 1:
The patent introduces intermediary components including a sump extension, flow passages, and a check valve as mediators between the splash lubrication system and the target components. The sump extension acts as an intermediary reservoir that collects splashed lubricant and directs it through controlled flow passages to the pinion bearings and rotor, ensuring reliable lubrication without complex pressurization systems.
Solution Approach 2:
The lubrication system is segmented into distinct functional zones: the main sump, the sump extension, flow passages, and delivery points. This segmentation allows the system to handle different lubrication requirements (pinion bearing lubrication and rotor cooling) separately while maintaining overall system simplicity. Each segment performs a specific function in the lubricant delivery chain.
2Device complexity
If gravity flow is used for lubricant distribution, then the system is passive and simple, but metered flow control is difficult
Solution Approach 1:
The patent utilizes parameter changes in the lubricant itself (temperature, viscosity, density) to achieve flow metering. As the lubricant is heated by the rotor and its viscosity changes, the flow rate through the passages is naturally regulated. The system design accounts for these parameter variations to ensure consistent lubrication delivery without active control mechanisms.
3Device complexity
If splash lubrication relies on vehicle speed, then the system is passive, but lubrication consistency varies with speed and temperature
Solution Approach 1:
The sump extension serves as a preliminary collection point that accumulates lubricant before it is delivered to the target components. This preliminary action ensures that sufficient lubricant is available regardless of vehicle speed variations. The extension acts as a buffer reservoir that maintains consistent supply to the flow passages even when splash lubrication intensity varies with speed.
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 system provides effective and metered lubrication and cooling to electric vehicle drive units, overcoming the limitations of passive gravity flow by ensuring consistent lubricant distribution to high-speed pinions and rotor components, even at high speeds and varying temperatures, without introducing additional shear surfaces or active pressurization.
Implementation Method 1
The stalactite member is directed downwardly toward the sump such that the lubricant splashed as droplets by rotation of the gear is collected on the stalactite member and is directed by the stalactite member downwardly by gravity into the sump
Implementation Method 2
A sump extension is connected to the sump, wherein the lubricant flows by gravity flow out of the sump into the sump extension
Implementation Method 3
a check valve positioned in the flow passage permits gravity flow of the lubricant in a downward direction in the flow passage and prevents pressurized back flow of the lubricant when the mPump is operating
Implementation Method 4
A mechanical pump (mPump) is connected to deliver pressurized lubricant flow into the gear input shaft passage of the gear input shaft to deliver pressurized lubricant flow to the gear
Data Source
AI summary
A vehicle stalactite passive lubrication system includes a drive unit having an electric motor and a gear. A sump has a sump extension. A lubricant is collected in the sump for gravity flow into the sump extension. A stalactite member is fixed to the drive unit and is positioned above an element to be filled with a fluid, lubricated or cooled. The stalactite member is directed downwardly toward the sump with the lubricant splashed by gear rotation collected on neighboring walls and the stalactite member and directed downwardly by gravity into the sump or target element. The stalactite member includes: a drip edge oriented at an angle to a horizontal plane; and a tip defining an end of the drip edge. The angle is selected to direct the lubricant to discharge off the stalactite member at the tip as a lubricant stream into the sump or target element.