Hybrid Vehicle EOP Control for Drive Loss Reduction
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Solution Overview
Problem
Hybrid vehicles with electric oil pumps (EOP) face drive loss and inefficiency due to variable driving conditions and input torque, affecting fuel economy and transmission performance.
Innovation Solution
A method of controlling the EOP in hybrid vehicles by optimizing oil pressure and flow rate through predetermined high-speed, middle-speed, and low-speed modes, using specific RPM settings (H-point, L-point, and M-point) based on target line pressure and ATF temperature, to minimize drive loss and improve fuel economy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the EOP is driven at high RPM to ensure sufficient oil pressure and flow rate for transmission operation, then the transmission lubrication and cooling performance is improved, but the drive loss increases and fuel economy deteriorates
Solution Approach 1:
The EOP control method dynamically adjusts the pump's RPM based on real-time transmission operating conditions, including input torque, line pressure requirements, and ATF temperature. The controller selects from multiple predetermined RPM modes (high-speed, middle-speed, low-speed) to match actual demand, preventing both over-pumping and under-pumping scenarios
Solution Approach 2:
The system changes the operating parameters of the EOP by establishing predetermined high-speed, middle-speed, and low-speed modes with specific RPM ranges. The controller switches between these parameter sets based on transmission needs, allowing the pump to operate at optimal efficiency points rather than fixed high RPM, thereby reducing drive loss while maintaining sufficient lubrication and cooling
2Reliability
If the EOP operates continuously at high RPM to maintain oil pressure during vehicle operation, then the transmission control reliability is improved, but the fuel economy is reduced due to increased energy consumption
Solution Approach 1:
The system applies partial action by operating the EOP at reduced RPM (middle-speed or low-speed modes) when full oil pressure and flow rate are not required. The controller assesses actual transmission needs and applies only the necessary pumping capacity, avoiding excessive energy consumption while maintaining sufficient transmission control reliability
Solution Approach 2:
The EOP operates in periodic cycles, switching between different RPM modes based on transient transmission demands. During vehicle start-up or high-torque conditions, the pump operates at high-speed mode temporarily, then transitions to lower-speed modes during steady-state operation, creating a periodic operation pattern that balances reliability and energy efficiency
3Loss of energy
If the EOP RPM is reduced to minimize drive loss, then the fuel economy is improved, but the oil pressure and flow rate may become insufficient for proper transmission operation
Solution Approach 1:
The control system incorporates feedback mechanisms by continuously monitoring transmission operating conditions, including input torque, line pressure, and ATF temperature. Based on this feedback, the controller determines the appropriate EOP RPM mode, ensuring that the pump delivers sufficient oil pressure and flow rate for proper transmission operation while minimizing drive loss
Solution Approach 2:
The system dynamically responds to changing transmission demands by adjusting EOP RPM in real-time. When transmission load increases or ATF temperature rises, the controller increases pump speed to maintain adequate lubrication and cooling, preventing reliability issues while avoiding unnecessary high-RPM operation during low-demand periods
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 method reduces drive loss and enhances fuel economy by optimizing EOP operation, ensuring rapid transmission filling and reduced energy consumption, thereby improving vehicle performance and quality.
Implementation Method 1
an electric oil pump (EOP) that generates oil pressure to operate, lubricate, and cool a transmission
Implementation Method 2
a motor for driving the pump, and a controller for controlling an operating state of the pump and the motor
Data Source
AI summary
A method of controlling an EOP of a hybrid vehicle may include controlling the EOP in a predetermined high-speed mode when the vehicle is started; controlling the EOP in a predetermined middle-speed mode in which the EOP is driven at revolutions per minute (RPM) lower than RPM of the high-speed mode when the high-speed mode is terminated; and controlling the EOP in a predetermined low-speed mode in which the EOP is driven at RPM lower than the RPM of the middle-speed mode when the vehicle is stopped.