Hybrid Engine DCCO Transitions Using Skip Fire Air Pumping
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Solution Overview
Problem
Deceleration fuel cut-off (DFCO) in internal combustion engines leads to undesirable emissions and limited fuel savings due to air pumping through cylinders, while deceleration cylinder cutoff (DCCO) offers improved fuel economy and emissions but faces challenges in commercial adoption, including NVH issues and inefficient transition strategies.
Innovation Solution
Implementing control strategies for transitioning an engine to and from deceleration cylinder cutoff (DCCO) mode in hybrid vehicles, where all engine working chambers are deactivated, and the crankshaft rotation is controlled by an electric motor/generator to maintain low speed, and employing techniques like skip fire and DFCO modes to mitigate NVH and emissions issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If deceleration fuel cut-off (DFCO) is used to improve fuel economy, then fuel consumption is reduced, but emissions increase due to uncombusted air pumping through cylinders
Solution Approach 1:
The patent extracts the harmful function of air pumping from the system by deactivating cylinder deactivation valves to close intake and exhaust valves during DCCO operation, preventing air from being pumped through the cylinders while maintaining the fuel cut-off benefit
Solution Approach 2:
The patent converts the potential harm of complete cylinder deactivation (which would cause NVH issues and make engine restart difficult) into a benefit by using controlled air pumping through selected cylinders to maintain catalyst temperature and oxygen saturation, thereby improving emissions during extended DCCO operation
2Use of energy by moving object
If deceleration cylinder cutoff (DCCO) is implemented to reduce air pumping losses, then fuel economy improves, but NVH issues arise due to complete cylinder deactivation
Solution Approach 1:
The patent applies local quality by selectively deactivating only certain cylinders during DCCO operation while keeping other cylinders active for air pumping, creating a localized solution that reduces pumping losses in deactivated cylinders while maintaining NVH comfort through active cylinders
Solution Approach 2:
The patent uses periodic action by implementing skip-fire modes where cylinders are alternately activated and deactivated in a periodic pattern, maintaining average fuel savings while reducing NVH through periodic air pumping events rather than continuous operation
3Use of energy by moving object
If extended DCCO operation is used to maximize fuel savings, then fuel economy improves, but emissions control becomes difficult due to catalyst oxygen saturation
Solution Approach 1:
The patent ensures continuity of useful action by maintaining periodic air pumping through selected cylinders during extended DCCO operation, continuously supplying oxygen to the catalyst to prevent saturation and maintain emissions control over extended periods
Solution Approach 2:
The patent applies preliminary action by pre-conditioning the catalyst with controlled air pumping before extended DCCO operation begins, and by maintaining oxygen saturation levels through periodic pumping events that prepare the catalyst for sustained emissions control
4Use of energy by moving object
If DCCO mode is implemented to reduce pumping losses, then fuel efficiency improves, but transition strategies become complex to manage NVH and emissions
Solution Approach 1:
The patent applies dynamics by implementing adaptive transition strategies that dynamically adjust which cylinders are deactivated and which remain active based on real-time operating conditions, vehicle speed, and catalyst state, simplifying the overall control logic through adaptive behavior rather than complex predetermined sequences
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
Enables extended DCCO operation periods, improving fuel economy and emissions by reducing pumping losses and NVH, while allowing for smoother transitions and reduced fuel wastage, thus enhancing the viability of DCCO in commercial applications.
Implementation Method 1
the crankshaft rotation rate is then controlled while the engine is disengaged from the drive train by adding or removing torque from the crankshaft by the electric motor/generator
Data Source
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AI summary
Methods and arrangements for transitioning an engine between a deceleration cylinder cutoff (DCCO) state and an operational state are described. In one aspect, transitions from DCCO begin with reactivating cylinders to pump air to reduce the pressure in the intake manifold prior to firing any cylinders. In another aspect, transitions from DCCO, involve the use of an air pumping skip fire operational mode. After the manifold pressure has been reduced, the engine may transition to either a cylinder deactivation skip fire operational mode or other appropriate operational mode. In yet another aspect a method of transitioning into DCCO using a skip fire approach is described. In this aspect, the fraction of the working cycles that are fired is gradually reduced to a threshold firing fraction. All of the working chambers are then deactivated after reaching the threshold firing fraction.