Hybrid Driveline Control for Engine Stop Energy Recovery
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Solution Overview
Problem
Hybrid vehicles face inefficiencies in converting kinetic energy into electrical energy while the internal combustion engine is stopped, leading to energy loss and increased time for engine restart and torque disturbances.
Innovation Solution
The method involves stopping the rotation of the engine and transmission input shafts at a gear ratio multiple of the transmission output shaft speed during engine stop requests, allowing kinetic energy to be converted into electrical energy by the electric machine, and pre-selecting transmission gears for faster engine reactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped to conserve fuel while the vehicle is moving, then fuel consumption is reduced, but kinetic energy conversion efficiency deteriorates because transmission input shafts continue to rotate and consume kinetic energy
Solution Approach 1:
The patent extracts the transmission input shafts from the rotating state during engine stop by decoupling them from the transmission output shaft through clutch disengagement. This allows the input shafts to stop rotating independently while the output shaft continues to rotate, eliminating the energy loss path from kinetic energy to rotating transmission components.
Solution Approach 2:
The patent applies preliminary action by stopping the transmission input shafts before engine restart is needed. By preemptively halting the rotation of input shafts and associated gears during the engine stop period, the system prepares the transmission for efficient engine reengagement while maximizing kinetic energy recovery during the stop interval.
2Loss of energy
If transmission input shafts are stopped during engine stop request, then kinetic energy conversion efficiency is improved, but engine restart time increases due to gear re-engagement requirements
Solution Approach 1:
The patent performs preliminary gear selection and clutch preparation during the engine stop period. The transmission controller pre-positions the appropriate gear and prepares the input clutch for engagement before the engine restart is initiated, so that when the engine restarts, the clutch can engage immediately without delay for gear selection or synchronization.
Solution Approach 2:
The patent dynamically adjusts the clutch engagement timing and gear selection based on real-time vehicle conditions. The system optimizes the balance between stopping transmission input shafts for energy efficiency and maintaining readiness for rapid engine restart by controlling when clutches engage and disengage based on driver demand and vehicle state.
3Speed
If transmission gears are shifted and pre-selected during engine stop, then engine response time is reduced, but driveline complexity increases due to additional control mechanisms
Solution Approach 1:
The patent makes the transmission controller multi-functional by combining engine stop management, transmission input shaft control, gear pre-selection, and clutch engagement timing in a single control system. This universal controller handles multiple functions that would otherwise require separate systems, reducing overall system complexity while achieving rapid engine response.
Solution Approach 2:
The patent implements feedback control where the transmission controller continuously monitors vehicle speed, driver demand, engine state, and transmission component positions to dynamically adjust gear pre-selection and clutch engagement timing. This feedback mechanism optimizes engine response time while managing the complexity of coordinated control through adaptive decision-making based on real-time conditions.
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 enhances the efficiency of kinetic energy conversion, reduces engine restart time, and minimizes driveline torque disturbances, thereby improving overall energy utilization and responsiveness.
Implementation Method 1
an electric machine provides propulsive effort or converts kinetic energy of the hybrid vehicle into electrical energy
Data Source
AI summary
Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, gears of a transmission may be unlocked from layshafts while an engine is stopped to conserve energy. Alternatively, the gears may be locked and unlocked from layshafts in response to vehicle operating conditions while the engine is stopped to improve driveline response.