Hybrid Vehicle Regenerative Braking E-Pump Control
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Solution Overview
Problem
In hybrid electric vehicles, regenerative braking is limited by the need to keep the torque converter bypass clutch locked, which is not maintained efficiently due to low transmission hydraulic system line pressure, leading to loss of kinetic energy and reduced fuel economy benefits.
Innovation Solution
A method using an electric pump (e-pump) to supply hydraulic fluid to the transmission, ensuring the torque converter bypass clutch remains locked during regenerative braking events by maintaining necessary line pressure, supplemented by a mechanical pump when the e-pump is not needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is extended to higher speeds, then kinetic energy recovery increases, but torque converter bypass clutch disengagement occurs due to insufficient line pressure
Solution Approach 1:
The electric pump is activated in advance before regenerative braking events to pre-charge the hydraulic system and maintain line pressure, ensuring the torque converter bypass clutch remains locked throughout the braking maneuver even at higher speeds where previously clutch disengagement would occur
Solution Approach 2:
The electric pump serves as an intermediary device that bridges the gap between mechanical pump insufficiency at low speeds and the hydraulic pressure requirements for maintaining clutch lock during high-speed regenerative braking, providing supplemental pressure when needed
2Loss of energy
If torque converter bypass clutch is kept locked during regenerative braking, then kinetic energy recovery is maximized, but hydraulic system line pressure is lost due to mechanical pump inefficiency at low speeds
Solution Approach 1:
The system merges the mechanical pump and electric pump into a hybrid hydraulic supply system, where the electric pump supplements the mechanical pump during low-speed operation to maintain adequate line pressure for clutch lock while enabling extended regenerative braking at higher speeds
Solution Approach 2:
The electric pump replaces the mechanical pump as the primary hydraulic pressure source during low-speed regenerative braking events, eliminating the mechanical pump's speed-dependent efficiency limitations and ensuring consistent line pressure maintenance
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 method effectively recovers more vehicle kinetic energy during regenerative braking, maintaining clutch lock and enhancing fuel economy by ensuring adequate hydraulic pressure is maintained, even at varying powertrain conditions.
Implementation Method 1
maintaining necessary line pressure
Implementation Method 2
using an e-pump to supply hydraulic fluid to the transmission
Implementation Method 3
using a mechanical pump to supply fluid to the transmission
Data Source
AI summary
A method for controlling regenerative braking in a hybrid electric powertrain includes using an e-pump to supply fluid to a transmission provided an indication that a torque converter clutch disengagement will occur under current powertrain operating conditions is present, and discontinuing use of the e-pump and using a mechanical pump to supply fluid to the transmission provided the indication that a torque converter clutch disengagement will occur under current powertrain operating conditions is absent.