Hybrid Torque Smoothing via Electric Motor Mediator
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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, either by adding or subtracting torque, to counteract engine-generated NVH, thereby improving fuel efficiency and reducing unwanted noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If skip-fire engine control is used to vary displacement for fuel efficiency, then fuel economy improves, but noise, vibration and harshness (NVH) worsen due to varying firing patterns
Solution Approach 1:
A second power source (electric motor/generator) is introduced as an intermediary to counteract the NVH generated by the skip-fire engine. The motor/generator applies smoothing torque to the powertrain to cancel out torque variations and vibrations caused by the irregular firing patterns, allowing the engine to operate in fuel-efficient skip-fire mode while maintaining acceptable NVH levels.
Solution Approach 2:
The second power source generates counteracting torque that opposes and neutralizes the harmful torque variations and vibrations produced by the skip-fire engine. This counter-torque approach directly compensates for the NVH effects while preserving the fuel efficiency benefits of the skip-fire operation.
2Loss of energy
If irregular firing patterns are used to optimize fuel efficiency, then thermal efficiency improves, but acoustic effects and structural vibrations worsen
Solution Approach 1:
The electric motor/generator serves as a mediator between the thermally efficient but noisy skip-fire engine and the vehicle powertrain. It absorbs the harmful acoustic effects and vibrations while transmitting only the useful power, enabling the engine to operate at optimal thermal efficiency points regardless of NVH concerns.
Solution Approach 2:
The system converts the harmful vibrations and acoustic effects into useful information by using sensors and control systems to detect NVH levels. This information is then used to adjust the firing patterns and motor/generator torque to minimize harmful effects while maintaining thermal efficiency, effectively turning the NVH problem into a controllable parameter.
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.