Electric Drive Oil Pump Layout for Bidirectional Cooling Flow
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Solution Overview
Problem
Existing electric drives for vehicles face challenges in maintaining a reliable and independent supply of transmission fluid to electrical components, as mechanical oil pumps require continuous rotation in one direction, regardless of the drive shaft's rotation direction, which complicates the design and increases space requirements.
Innovation Solution
The electric drive incorporates a mechanically driven oil pump with two drive paths and a planetary differential, utilizing freewheels and a planetary gearing system to ensure the pump shaft rotates in the same direction independently of the intermediate shaft's rotation, allowing for a compact and space-saving design by placing components radially within the hollow intermediate shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a mechanical oil pump is used to supply transmission fluid to electrical components, then the cooling function is achieved, but the pump shaft must rotate in one direction regardless of drive shaft rotation direction, requiring complex drive paths with freewheels
Solution Approach 1:
The patent combines the oil pump drive mechanism with the existing differential gear system. The oil pump shaft is driven through the differential gear mechanism, merging the cooling function drive with the power transmission path. This eliminates the need for separate freewheel mechanisms, reducing structural complexity while maintaining the ability to supply transmission fluid for cooling regardless of rotation direction
Solution Approach 2:
The differential gear system serves dual functions: it continues to perform its traditional power distribution function to the drive wheels, and simultaneously provides the drive path for the oil pump shaft. This multi-functionality eliminates the need for dedicated oil pump drive mechanisms with freewheels, simplifying the overall structure
2Reliability
If two drive paths with freewheels are implemented for the oil pump, then independent rotation direction is achieved, but space requirements increase
Solution Approach 1:
The patent merges the oil pump drive mechanism with the existing differential gear system. The oil pump shaft is driven through the differential gear mechanism, merging the cooling function drive with the power transmission path. This eliminates the need for separate freewheel mechanisms, reducing structural complexity while maintaining the ability to supply transmission fluid for cooling regardless of rotation direction
Solution Approach 2:
The oil pump drive components are nested within the existing differential housing and gear structure. The oil pump shaft and its drive mechanism are positioned inside the differential assembly, utilizing the existing space rather than requiring additional external components. This nesting approach maintains independent rotation capability while minimizing space occupation
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 configuration ensures a reliable and efficient transmission fluid supply to electrical components, maintaining cooling performance in both forward and reverse directions while minimizing space and installation complexity, thus achieving a cost-effective and compact electric drive solution.
Implementation Method 1
The electric drive incorporates a mechanically driven oil pump with two drive paths and a planetary differential, utilizing freewheels and a planetary gearing system to ensure the pump shaft rotates in the same direction independently of the intermediate shaft's rotation
Implementation Method 2
The pump shaft in the oil pump can be driven in the same direction with a first drive path that has at least one first freewheel, and with a second drive path that has at least one second freewheel
Data Source
AI summary
An electric drive for may have at least one electric machine in a housing with a rotor shaft forming the drive shaft, which can be coupled to an intermediate shaft via at least one spur gear, wherein the intermediate shaft is coupled to an output differential for driving output shafts, wherein there is at least one oil pump for pumping transmission fluid, wherein a pump shaft in the oil pump can be driven in the same direction of rotation via a first drive path, which has at least one first freewheel, and via a second drive path, which has at least one second freewheel and at least one differential, and wherein at least the first freewheel and the second freewheel, as well as the differential, are located radially inside the hollow intermediate shaft.