Hybrid Engine Stop Control via Damper Clutch Locking
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Solution Overview
Problem
Hybrid powertrain systems with electro-mechanical transmissions face challenges in effectively stopping the internal combustion engine during ongoing vehicle operation, leading to objectionable vibrations due to compression torque pulses and pressure pulses.
Innovation Solution
A control scheme that includes stopping engine firing, locking the engine and transmission with a damper clutch, and selectively controlling torque outputs from electrical machines to reduce engine speed and stop rotation near a predetermined crank position, using an engine torque simulation model to manage engine compression pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is stopped during ongoing vehicle operation to optimize energy efficiency, then fuel consumption is reduced, but compression torque pulses generate objectionable vibrations
Solution Approach 1:
The control system determines in advance whether to stop the engine based on vehicle operating conditions. Before stopping the engine, the system evaluates factors such as vehicle speed, battery state of charge, and driveline conditions to ensure the stop will not generate harmful vibrations, thus preventing the problem rather than reacting to it.
Solution Approach 2:
The control system continuously monitors vehicle operating conditions and provides feedback to determine optimal engine stop events. By monitoring parameters such as vibration levels, battery charge state, and driveline load, the system adjusts engine stop decisions in real-time to maintain energy efficiency while minimizing harmful vibrations.
2Use of energy by moving object
If the engine is automatically stopped by the control system during ongoing vehicle operation, then energy efficiency is optimized, but pressure pulses and vibrations occur during engine stop events
Solution Approach 1:
The control system acts as an intermediary between the engine and the rest of the powertrain system. It manages the transition during engine stop events by coordinating the disconnection of the engine from the driveline, thereby mediating the pressure pulses and preventing them from propagating through the driveline components.
Solution Approach 2:
The control system prepares the powertrain for engine stop events by pre-positioning clutches and managing power flow before the engine stops. This preliminary action ensures that pressure pulses are contained and do not reach driveline components, reducing vibrations and harmful effects.
3Use of energy by moving object
If engine stop events are implemented to reduce fuel consumption, then energy efficiency improves, but vibrations reach the vehicle operator at resonant frequencies
Solution Approach 1:
The control system monitors vibration levels and driveline conditions in real-time, providing feedback to determine whether an engine stop event should proceed. When feedback indicates that resonant frequencies may be excited, the system modifies or cancels the engine stop command, thus preventing harmful vibrations from reaching the vehicle operator.
Solution Approach 2:
The control system applies preliminary anti-action by preventing engine stop events under conditions that would generate resonant vibrations. By evaluating operating conditions before initiating an engine stop, the system avoids creating the harmful vibrations in the first place, rather than attempting to mitigate them after they occur.
Data Source
AI summary
A control scheme is provided for stopping an internal combustion engine of a hybrid powertrain during ongoing vehicle operation. The method, executed as program code in an article of manufacture comprises the following steps in the sequence set forth. First, engine operation is controlled to stop firing the engine. A damper clutch is controlled to lock rotation of the engine and the electro-mechanical transmission. Torque outputs from the first and second electrical machines are then selectively controlled to reduce engine speed. Torque outputs from the first and second electrical machines are then selectively controlled to stop rotation of the engine substantially near a predetermined crank position.