Motor Torque Smoothing for Engine Cylinder Recharging
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Solution Overview
Problem
Recharging events in variable displacement combustion engines cause torque fluctuations, leading to undesirable noise, vibration, and harshness (NVH) due to the leakage of air/gas past piston rings, which necessitate frequent recharging and disrupt engine speed and torque delivery.
Innovation Solution
An engine controller is configured to manage electric motor torque smoothing for internal combustion engine cylinder recharging events by determining a torque profile and actuating an additional motor to provide supplemental torque during recharging, using a skip-fire technology that allows fractional engine displacement, thereby reducing NVH through staggered recharging and counteracting torque application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If skip-fire engine control is used to vary effective displacement for fuel efficiency, then fuel efficiency is improved, but torque fluctuations and NVH increase due to recharging events
Solution Approach 1:
The system applies preliminary anti-action by using a motor to counteract the torque fluctuations that occur during recharging events. The motor provides compensating torque in advance or simultaneously with the recharging event to offset the NVH-causing fluctuations, thereby maintaining fuel efficiency benefits while reducing harmful vibrations and noise.
Solution Approach 2:
The motor acts as an intermediary between the combustion engine and the drivetrain. During recharging events, the motor mediates the torque fluctuations by providing supplemental torque to smooth out the disruptions caused by cylinder recharging, thus protecting the drivetrain from harmful vibrations while maintaining the fuel efficiency advantages of skip-fire operation.
2Use of energy by moving object
If cylinders are repeatedly skipped to maintain fuel efficiency, then displacement is reduced, but air/gas leaks past piston rings requiring frequent recharging
Solution Approach 1:
The system applies dynamics by dynamically adjusting the firing pattern of cylinders based on operating conditions. The control system monitors which cylinders are skipped and when recharging is needed, dynamically switching between skip-fire and full-fire modes to maintain both fuel efficiency and adequate cylinder sealing, preventing excessive air/gas leakage past piston rings.
3Reliability
If recharging events are performed to maintain cylinder pressure, then engine operation is maintained, but torque disruptions and NVH increase
Solution Approach 1:
The system applies preliminary anti-action by using the motor to counteract torque disruptions during recharging events. The motor provides compensating torque to offset the fluctuations caused by recharging, thereby maintaining reliable engine operation while reducing harmful torque variations and associated NVH.
Data Source
AI summary
Methods, systems, and devices for managing motor torque smoothing for internal combustion engine cylinder recharging events are described herein. An engine controller in a vehicle for managing motor torque smoothing for internal combustion engine cylinder recharging events may be configured to operate the internal combustion engine at a firing fraction that is less than a value of 1.0, wherein one or more cylinders are not designated to be fired, determine a recharge event time period where a particular one of the cylinders that have not been designated to be fired is recharged, identify a disruption quantity of torque during the recharging event time period, and actuate an additional motor to initiate a supplemental quantity of torque during the recharge event time period based on the disruption quantity of torque.