Dual Oil Pump Cooling for Compact EV Powertrains
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Solution Overview
Problem
The miniaturization of powertrains in electric vehicles leads to increased heat density and reduced cooling efficiency due to smaller oil passages, resulting in poor cooling effects for motors and reducers, as the flow resistance and flow rate of cooling oil are compromised.
Innovation Solution
Implementing a system with multiple oil pumps, where a mechanical oil pump acts as the main pump and an electronic oil pump as an auxiliary, to ensure a sufficient flow rate of cooling oil, with the mechanical pump being connected to a rotating component to increase flow rate with motor speed and the electronic pump reducing power consumption at higher speeds, and using dry oil pans to reduce churning losses and enhance heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the powertrain is miniaturized to reduce size, then the power density increases, but the heat density increases and cooling efficiency deteriorates due to smaller oil passages
Solution Approach 1:
The patent divides the cooling system into multiple independent oil pumps (main oil pump and auxiliary oil pump) that work together to provide sufficient cooling flow rate despite miniaturization. The segmentation of the pumping function compensates for the reduced oil passage size, maintaining adequate cooling capacity in a compact powertrain design.
2Volume of moving object
If the oil passage size is reduced due to miniaturization, then the powertrain size decreases, but the flow resistance increases and flow rate decreases
Solution Approach 1:
The patent combines multiple oil pumps (main oil pump driven by the motor and auxiliary oil pump) to work together, merging their pumping capabilities to achieve sufficient total flow rate despite the reduced size of individual oil passages. This combination compensates for the increased flow resistance caused by miniaturization.
Solution Approach 2:
The main oil pump is dynamically coupled to the motor, with its rotational speed varying according to motor speed. This dynamic adjustment allows the cooling system to adapt to different operating conditions, maintaining adequate flow rate through the miniaturized oil passages across a range of powertrain speeds.
3Device complexity
If a single oil pump is used for cooling, then the device complexity is reduced, but the cooling effect deteriorates due to insufficient flow rate in miniaturized passages
Solution Approach 1:
The cooling system is segmented into multiple pumping units (main oil pump and auxiliary oil pump) to achieve sufficient cooling capacity. This segmentation allows the system to overcome the flow limitations of miniaturized passages while maintaining relatively simple overall system architecture through the use of standardized pump components.
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 improves the cooling effect of the powertrain by maintaining efficient heat dissipation and reducing power consumption, allowing for higher rotational speeds and smaller, cost-effective pump designs while minimizing oil churning losses and enhancing transmission efficiency.
Implementation Method 1
cooling oil is mainly driven by an electric oil pump to circulate heat between the inside of the powertrain and a heat exchanger for lubrication and cooling
Implementation Method 2
cooling oil is mainly driven by an electric oil pump to circulate heat between the inside of the powertrain and a heat exchanger
Data Source
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AI summary
This application provides a powertrain and an electric vehicle, and relates to the field of motor cooling technologies. The powertrain includes a motor, a reducer, an oil pan, and a cooling system. The cooling system includes at least one heat exchanger and at least two oil pumps. The at least two oil pumps are configured to deliver, to the heat exchanger, cooling oil sucked from the oil pan. The heat exchanger is configured to cool the cooling oil sucked by the at least two oil pumps. An oil outlet port of the heat exchanger is connected to an oil passage in the motor and an oil passage in the reducer, so that a part of the cooling oil cools the motor through the oil passage in the motor, and another part of the cooling oil cools the reducer through the oil passage in the reducer. The technical solutions of this application improve a cooling effect of the cooling system for the powertrain.