Hybrid Powertrain Torque Smoothing via Auxiliary Motor
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Solution Overview
Problem
Skip-fire engine control technologies face challenges in managing noise, vibration, and harshness (NVH) due to the varying and irregular firing patterns, which can lead to undesirable acoustic effects and structural vibrations, affecting vehicle occupant comfort and fuel efficiency.
Innovation Solution
A hybrid vehicle system that estimates the torque profile of the internal combustion engine and uses an auxiliary power source/sink to apply a smoothing torque to the powertrain, reducing NVH by counteracting torque spikes and optimizing firing sequences for improved fuel efficiency and drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If skip-fire engine control is used to improve fuel efficiency, then fuel efficiency is improved, but noise, vibration and harshness (NVH) worsen due to varying and irregular firing patterns
Solution Approach 1:
An auxiliary power source/sink is introduced as an intermediary device to counteract the NVH effects of skip-fire operation. The auxiliary power source applies a smoothing torque to the powertrain that offsets the torque variations produced by irregular cylinder firing patterns, thereby reducing vibration and noise while allowing the skip-fire strategy to continue improving fuel efficiency
2Loss of energy
If skip-fire control with varying firing patterns is implemented, then fuel efficiency improves through reduced pumping losses, but torque delivery becomes irregular causing undesirable acoustic effects and vibrations
Solution Approach 1:
The control system calculates the expected torque profile from skip-fire operation in advance and determines a counteracting smoothing torque before it is applied. The auxiliary power source then applies this pre-calculated smoothing torque to counteract the anticipated torque variations and irregularities, maintaining stable torque delivery while preserving the fuel efficiency benefits of skip-fire control
3Adaptability or versatility
If individual cylinder deactivation is used to achieve dynamic skip-fire operation, then effective displacement control is improved, but device complexity increases due to individual cylinder control requirements
Solution Approach 1:
The system utilizes the existing auxiliary power source already present in hybrid vehicles to provide the smoothing torque function, rather than adding a separate dedicated device. This self-service approach leverages available components to address NVH issues, reducing the need for additional complex hardware while maintaining the adaptability of dynamic skip-fire operation for effective displacement control
Data Source
AI summary
Methods, devices, estimators, controllers and algorithms are described for estimating the torque profile of an engine and/or for controlling torque applied to a powertrain by one or more devices other than the engine itself to manage the net torque applied by the engine and other device(s) in manners that reduce undesirable NVH. The described approaches are particularly well suitable for use in hybrid vehicles in which the engine is operated in a skip fire or other dynamic firing level modulation manner—however they may be used in a variety of other circumstances as well. In some embodiments, the hybrid vehicle includes a motor/generator that applies the smoothing torque.