Mechanically-Driven Cooling and Lubrication System for Hybrid Drive Units
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Solution Overview
Problem
Conventional cooling and lubrication systems in motor vehicle drive units face challenges in efficiently managing heat and lubrication, particularly in hybrid electric vehicle applications, where packaging constraints and parasitic losses are significant, and electric pumps introduce inefficiencies and high costs.
Innovation Solution
A cooling and lubrication system utilizing two mechanically-driven pumps, a heat exchanger, and an oil/air separator reservoir, which minimizes sump volume, employs an air elimination circuit, and includes check and throttle valves to selectively direct fluid flow for effective cooling and lubrication, even when mechanical pumps are not operational, thereby reducing parasitic losses and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electric pumps are used in cooling and lubrication systems, then the system can operate when mechanical pumps are not operational, but the system experiences increased costs and parasitic losses
Solution Approach 1:
The system uses the mechanical pumps' own operation to simultaneously achieve cooling and lubrication functions. The mechanically-driven pumps provide both cooling fluid circulation and lubrication oil delivery without requiring separate electric pumps, thereby eliminating parasitic losses associated with additional electric motors while maintaining system reliability through functional integration.
Solution Approach 2:
The mechanically-driven pumps are designed to perform multiple functions: delivering coolant to the heat exchanger for cooling purposes and delivering lubrication oil to various components. This multi-functionality eliminates the need for separate electric pumps for each function, reducing parasitic losses while ensuring continuous operation.
2Reliability
If conventional cooling and lubrication systems are used, then the system can provide adequate cooling and lubrication, but the sump volume increases leading to packaging constraints
Solution Approach 1:
The system merges the cooling fluid sump and lubrication oil sump into a single integrated sump. The mechanically-driven pumps draw from this combined sump and distribute both cooling and lubrication functions through shared infrastructure, significantly reducing the total volume required compared to separate sump systems while maintaining adequate performance for both functions.
Solution Approach 2:
The system segments the fluid delivery into separate mechanically-driven pump circuits - one for cooling fluid through the heat exchanger and another for lubrication oil to various components. This segmentation allows efficient use of a smaller shared sump volume by directing fluids to different functions as needed, rather than requiring a large single sump to accommodate all fluids simultaneously.
3Loss of energy
If mechanically-driven pumps are used, then the system reduces parasitic losses and costs, but the system cannot operate when the vehicle is stationary
Solution Approach 1:
The system is designed so that the mechanically-driven pumps serve multiple functions simultaneously. When the vehicle is operating and the mechanical pumps are running, they provide both cooling and lubrication functions. The system accepts that stationary operation is limited but maximizes efficiency during normal operation by eliminating the need for separate electric pumps.
Solution Approach 2:
The system dynamically adapts its operation based on vehicle status. The mechanically-driven pumps operate when the vehicle is running, providing both cooling and lubrication functions. The system design accepts the dynamic limitation of not operating when stationary but compensates by achieving superior efficiency and reduced parasitic losses during normal vehicle operation.
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
The system provides efficient cooling and lubrication functionalities with reduced sump volume, addressing packaging constraints and inefficiencies associated with electric pumps, while maintaining performance even when the vehicle is stationary, thus enhancing overall system efficiency and reducing costs.
Implementation Method 1
The heat exchanger resides downstream of the first mechanically-driven pump, and resides downstream of the second mechanically-driven pump
Implementation Method 2
an oil/air separator reservoir which receives the drive unit fluid from the first and second mechanically-driven pumps
Data Source
AI summary
A cooling and lubrication system for a motor vehicle drive unit includes a drive unit sump, a first mechanically-driven pump, a second mechanically-driven pump, and an oil/air separator reservoir, among other possible components. The drive unit sump holds drive unit fluid. The first mechanically-driven pump fluidly communicates with the drive unit sump, and the second mechanically-driven pump fluidly communicates with the drive unit sump. The oil/air separator reservoir resides downstream of the first mechanically-driven pump and resides downstream of the second mechanically-driven pump.