Regenerative Braking Clutch Control for Hybrid Vehicles
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Solution Overview
Problem
Regenerative braking efficiency in hybrid and electric vehicles is reduced due to transmission upshifts during braking events, as the torque converter clutch disengages, leading to decreased regenerative braking torque and electricity generation.
Innovation Solution
A controller prevents the transmission clutch from disengaging during expected regenerative braking events by maintaining engagement until the accelerator pedal is reapplied or the braking event indication is removed, thereby inhibiting upshifts within a predetermined shift window to ensure continuous torque transfer to the electric generator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transmission clutch is allowed to disengage during normal operation to enable upshifts, then transmission shifting capability is improved, but regenerative braking efficiency deteriorates due to reduced torque transfer
Solution Approach 1:
The controller predicts regenerative braking events in advance using various methods (detecting brake pedal activation, analyzing driver behavior patterns, monitoring vehicle deceleration rates) and proactively maintains clutch engagement before the actual braking occurs, preventing energy loss while preserving upshift capability for non-braking conditions
Solution Approach 2:
The clutch control strategy dynamically adapts to different operating conditions by switching between engagement and disengagement states based on real-time detection of braking events, vehicle speed, and predicted driver intent, optimizing the balance between transmission shifting needs and regenerative braking efficiency
2Loss of energy
If the clutch remains engaged during predicted braking events to maintain regenerative braking efficiency, then energy recovery is improved, but transmission upshift capability deteriorates during the engagement period
Solution Approach 1:
The system performs preliminary detection of braking event characteristics and predicts their duration, allowing the controller to maintain clutch engagement only for the necessary duration while planning for subsequent upshift opportunities, thus minimizing the impact on transmission adaptability
Solution Approach 2:
The controller continuously monitors vehicle operating conditions during clutch engagement, detecting when braking events conclude and immediately transitioning to allow upshifts, ensuring that the transmission system remains ready to perform useful shifting actions as soon as regenerative braking is no longer needed
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 enhances regenerative braking efficiency by maintaining clutch engagement during predicted braking events, maximizing torque transfer and electricity generation, and preventing energy loss due to upshifts, thus improving vehicle fuel economy and energy recovery.
Implementation Method 1
torque is passed through the drivetrain to an electric generator
Data Source
AI summary
A vehicle includes a powertrain and a controller. The powertrain includes a transmission mechanically coupled to an electric machine and configured to transfer torque between a wheel and the electric machine. The transmission has a gearbox configured to establish gear ratios through a shift. The controller is programmed to, in response to an indication of an expected regenerative braking event having a timing falling within a shift window of the transmission, prevent a clutch of the transmission from disengaging until first occurrence of application of an accelerator pedal or removal of the indication to inhibit the shift prompted by a shift schedule of the gearbox.