Variable Valve Actuation Switching for Miller Cycle Transients
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing variable valve actuation (VVA) systems for engines face challenges in controlling transient operation and emissions, with difficulties in measuring or sensing engine operating parameters such as cylinder pressure, leading to inefficiencies and unmet needs.
Innovation Solution
A system comprising a VVA system with electronically controlled actuators and a control system that adjusts valve actuation between Miller and non-Miller cycles based on engine conditions, including engine speed, peak cylinder pressure, air-fuel ratio, and oxygen-fuel control, using a logic-based approach and equations to optimize engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable valve actuation systems are used to control transient operation and vary combustion cycles, then engine performance and emissions are improved, but the complexity of measuring and sensing engine operating parameters such as cylinder pressure increases
Solution Approach 1:
The patent introduces a virtual sensor as an intermediary that calculates cylinder pressure indirectly using a polynomial equation based on easily measurable parameters (intake manifold pressure, exhaust manifold pressure, oxygen concentration, crankshaft position) rather than requiring direct physical pressure sensors in the cylinder, thus reducing measurement complexity while maintaining accuracy
Solution Approach 2:
The patent replaces direct mechanical pressure sensing in the cylinder with an computational model that uses electrical/electronic sensors and mathematical calculations to determine cylinder pressure, substituting a complex mechanical measurement system with a simpler electronic computation system
2Object-generated harmful factors
If VVA systems switch between Miller and non-Miller cycles during transient operation, then emissions are reduced, but the difficulty of detecting and measuring engine operating conditions increases
Solution Approach 1:
The control system continuously monitors engine operating conditions (intake manifold pressure, exhaust manifold pressure, oxygen concentration, crankshaft position) and uses feedback from these sensors to dynamically adjust valve actuation timing and duration, enabling real-time optimization of emissions while simplifying measurement requirements
Solution Approach 2:
The virtual sensor acts as an intermediary that processes readily available sensor data through a polynomial equation to provide accurate cylinder pressure information without requiring direct pressure measurement, thereby reducing the difficulty of detecting and measuring engine operating parameters
Data Source
AI summary
A system includes an engine including a valvetrain comprising one or more intake valves and one or more exhaust valves, a variable valve actuation (VVA) system electronically controllable to vary operation of the valvetrain to selectably operate the engine in either a Miller cycle or a non-Miller cycle, and an electronic control system configured to control the VVA system to change operation of the engine from the Miller-cycle to the non-Miller cycle if an engine speed condition is satisfied, a peak cylinder pressure (PCP) condition is satisfied, at least one of an air-fuel ratio (AFR) condition and an oxygen-fuel-control (OFC) condition is satisfied, and a minimum off time condition for the VVA system is satisfied.