Engine Stop Position Control via Clutch Deceleration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine start-stop systems in vehicles face inefficiencies due to the need for cam-crank resynchronization during engine restart, which can lead to inefficient fuel consumption and delayed engine reactivation.
Innovation Solution
A method for controlling engine stop position by managing crankshaft speed through clutch commands in automatic or dual-clutch transmissions, using parasitic and friction losses to achieve a precise target stop position, allowing for immediate fueling and restarting when the brake pedal is released.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional engine stop-start systems are used with cam-crank resynchronization, then engine restart can be achieved, but fuel consumption increases and restart time is delayed
Solution Approach 1:
The system performs preliminary action by controlling the engine to stop precisely at a predetermined crankshaft position (e.g., top dead center) before restart is needed. This is achieved by monitoring crankshaft position sensors and adjusting fuel injection timing during the coast-down period after engine shutdown is initiated, so that when the driver requests restart, the engine is already positioned for immediate combustion without requiring resynchronization delays
Solution Approach 2:
The system uses feedback from crankshaft position sensors and engine control unit data to continuously monitor and adjust the engine stop position. The ECU receives real-time information about crankshaft rotation and fuel injection status, making dynamic adjustments to ensure the engine stops at the optimal position for immediate restart, thereby eliminating the need for time-consuming resynchronization procedures
2Reliability
If cam-crank resynchronization is performed to identify compression cylinder, then engine restart is achieved, but fuel efficiency deteriorates
Solution Approach 1:
The system performs preliminary positioning of the crankshaft to a predetermined stop position (such as top dead center on the compression stroke) before restart is requested. This preliminary action ensures that the correct cylinder is already in the compression position when restart is initiated, eliminating the need for post-shutdown resynchronization and enabling immediate fuel injection and combustion, thereby maintaining both restart reliability and fuel efficiency
Solution Approach 2:
The system uses the engine's own rotational inertia and the natural deceleration during coast-down, combined with precise fuel injection control, to achieve proper cylinder positioning without requiring external resynchronization mechanisms. The engine essentially positions itself at the correct stop position through controlled deceleration and timed fuel cutoff, eliminating the need for additional energy-consuming resynchronization operations
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 enables rapid and predictable engine reactivation, reducing idle fuel consumption and avoiding inefficient resynchronization processes, thereby improving fuel efficiency and restart consistency.
Implementation Method 1
The controller transmits clutch commands to a clutch of an automatic or dual-clutch transmission (DCT) to slow engine inertia by inducing parasitic and friction losses.
Data Source
AI summary
A vehicle having engine stop-start functionality includes a transmission, engine, and controller. The transmission includes a clutch, and the engine includes a crankshaft. The controller is in communication with the engine and the transmission, and is configured for detecting a commanded shut down of the engine, and then engaging the clutch to control a rate of deceleration of the crankshaft and stop the crankshaft within a calibrated range of a target stop position at the end of engine shut down. A method for controlling engine stop position includes detecting a commanded shut down of the engine, and engaging the clutch after detecting the commanded shut down to thereby control the rate of deceleration of the crankshaft and stop the crankshaft within a calibrated range of a target stop position at the end of shut down of the engine. The transmission may be automatic or it may be a dual-clutch transmission.