Electric Pump Driveline Cooling for Hybrid Vehicle Energy Recovery
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Solution Overview
Problem
Hybrid vehicles face inefficiencies in regenerative braking due to electric machine temperature increases, leading to kinetic energy conversion into heat energy loss, reducing energy recovery and conservation.
Innovation Solution
An electric pump is selectively operated to supply transmission fluid to the driveline, including when the engine and electric machine are stopped, and activated when the electric machine temperature exceeds a threshold to enhance cooling, complementing a mechanical pump during increased heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric machine operates in generator mode to recharge the electrical energy storage device during regenerative braking, then kinetic energy is converted into electrical energy, but the electric machine temperature increases to a level where current must be reduced
Solution Approach 1:
The patent extracts the cooling function from the transmission system by providing a dedicated cooling circuit that directs transmission fluid specifically to the electric machine. This separation allows the electric machine to be cooled independently from the transmission clutches, enabling higher current operation during regenerative braking without excessive temperature rise.
Solution Approach 2:
The transmission fluid is circulated through the electric machine cooling circuit in advance and during periods of high current operation to prevent temperature buildup. The system proactively manages thermal conditions before they become problematic, allowing the electric machine to operate at higher currents for longer durations.
2Temperature
If a dedicated cooling circuit for the electric machine is implemented, then electric machine cooling is improved, but system complexity increases
Solution Approach 1:
The transmission fluid serves multiple functions: it lubricates and cools the transmission clutches through one circuit path, and it cools the electric machine through a dedicated cooling circuit path. This multi-functionality allows a single fluid system to handle multiple cooling requirements without needing separate coolant systems for each component.
Solution Approach 2:
The patent merges the transmission fluid system with the electric machine cooling system by using the same transmission fluid for both purposes. The electric machine cooling circuit is integrated into the existing transmission fluid circulation system, sharing the fluid reservoir and pump resources while providing dedicated cooling capability.
3Temperature
If the electric pump operates continuously to supply transmission fluid, then driveline cooling is improved, but energy consumption increases
Solution Approach 1:
The electric pump operation is made dynamic and conditional rather than continuous. The pump is activated only when cooling is needed based on real-time monitoring of electric machine temperature and current operation status. This dynamic control allows the system to balance cooling requirements against energy consumption by running the pump only during periods of high thermal load.
Solution Approach 2:
The system uses feedback from temperature sensors and current monitoring to control electric pump operation. When the electric machine temperature exceeds thresholds or during high current regenerative braking events, the pump is activated to increase cooling. This feedback-based control ensures the pump operates only when necessary, minimizing energy consumption while maintaining adequate cooling.
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 approach improves driveline cooling, conserves energy by optimizing cooling needs, and provides additional cooling without additional expense, enhancing energy recovery during regenerative braking.
Implementation Method 1
operating an electric pump to supply transmission clutches transmission fluid when an engine and an electric machine are stopped
Implementation Method 2
The heat energy produced by the vehicle brakes may be lost to the atmosphere, thereby reducing the vehicle's ability to recover and conserve energy
Data Source
AI summary
Systems and methods for improving hybrid vehicle cooling are presented. In one example, an electric pump may supply transmission fluid to a transmission and a driveline integrated starter/generator to cool, operate, and lubricate driveline components. The electric pump may be selectively operated to conserve energy and to supply driveline cooling when driveline cooling may be desirable.