EV Drive Gearbox Oil Recirculation Using Motor Cooling Heat
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Solution Overview
Problem
Existing powertrain solutions for electric vehicles that improve speed reducer efficiency, such as reducing oil circulation and installing oil pumps or heat exchangers, are costly and increase vehicle weight and space requirements.
Innovation Solution
A powertrain design with a hollow oil circulation disc and distribution member that recovers and redistributes oil from the differential crown, utilizing the heat from the electric motor's cooling system to reduce oil viscosity and optimize lubrication, without the need for additional pumps or exchangers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an oil pump and/or heat exchanger is installed to improve speed reducer efficiency, then lubrication is improved and oil viscosity is reduced, but vehicle weight increases and internal space requirements increase
Solution Approach 1:
The patent merges the cooling function of the electric motor with the lubrication function of the speed reducer by integrating the oil circulation system with the motor cooling system. The hollow disc serves as both a cooling element for the motor and a lubrication distribution component for the reducer, eliminating the need for separate heat exchanger and oil pump systems.
Solution Approach 2:
The hollow disc performs multiple functions simultaneously: it acts as a cooling chamber for the electric motor, an oil circulation reservoir, and a lubrication distribution system for the speed reducer. This multi-functionality eliminates the need for separate dedicated components for each function, reducing overall system weight and space requirements.
2Loss of energy
If an oil pump and/or heat exchanger is installed to improve speed reducer efficiency, then lubrication is improved and oil viscosity is reduced, but internal space requirements increase
Solution Approach 1:
The patent merges the cooling function of the electric motor with the lubrication function of the speed reducer by integrating the oil circulation system with the motor cooling system. The hollow disc serves as both a cooling element for the motor and a lubrication distribution component for the reducer, eliminating the need for separate heat exchanger and oil pump systems.
Solution Approach 2:
The hollow disc performs multiple functions simultaneously: it acts as a cooling chamber for the electric motor, an oil circulation reservoir, and a lubrication distribution system for the speed reducer. This multi-functionality eliminates the need for separate dedicated components for each function, reducing overall system weight and space requirements.
3Loss of energy
If a hollow oil circulation disc with calibrated orifices is used to reduce oil volume, then lubrication efficiency is improved and oil viscosity is reduced through heating, but the system complexity increases
Solution Approach 1:
The system uses the waste heat from the electric motor cooling system to automatically heat and thin the lubrication oil, eliminating the need for external heating devices or complex thermal management systems. The calibrated orifices automatically regulate oil flow based on pressure differential, requiring no active control mechanisms.
Solution Approach 2:
The system changes the temperature parameter of the lubrication oil by utilizing heat from the motor cooling system. This temperature increase reduces oil viscosity and improves lubrication efficiency without requiring external heating equipment or complex control systems.
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
Improves speed reducer efficiency by optimizing lubrication and reducing oil volume, maintaining efficiency without increasing weight or size, and allowing controlled oil levels for varying driving conditions.
Implementation Method 1
one of the faces of said hollow disc being in contact with a face of a cooling chamber of the electric motor
Implementation Method 2
the oil which circulates in the hollow disc, will be heated by the calories to be dissipated in the cooling wall which has been previously heated by the electric motor, and will thus reduce the viscosity of the oil
Implementation Method 3
the distribution member is placed in an upper zone of the speed reducer, the outlet orifice being placed below the inlet orifice, so that the oil passes by gravity into the hollow disc between the inlet orifice and the outlet orifice
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a power unit (1, 100) for an electric vehicle comprising an electric motor (2, 102) and a reduction gearbox (3) comprising a differential ring gear (30). According to the invention, the reduction gearbox (3) comprises an oil distribution member (200) and the power unit (1, 100) comprises a hollow oil-circulation disc (19, 121) placed against one face of a cooling chamber (10, 120) for the cooling of the electric motor (2, 102), the distribution member (200) creating a first flow of oil towards the inlet orifice (22, 132) of the hollow disc (19, 121) so as to supply said hollow disc (19, 121) with oil.