Variable Displacement Engine Pneumatic Cylinder Springs for Aftertreatment Warm-up
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Solution Overview
Problem
Current internal combustion engines take a significant amount of time to reach operating temperatures after a cold start, leading to increased pollution emissions due to inefficient aftertreatment systems, as they emit higher levels of hydrocarbons, carbon monoxide, NOx, and particulates before reaching warm operating temperatures.
Innovation Solution
The use of different pneumatic cylinder spring types in a skip fire controlled engine, where cylinders are operated as Low Pressure Exhaust Springs (LPES) until the aftertreatment system reaches light-off temperature, then as High Pressure Exhaust Springs (HPES) after reaching that temperature, and subsequently in a skip fire manner, allowing for selective operation as LPES, HPES, or Air Spring (AS) types during skipped cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the engine operates with all cylinders firing at normal load during cold start, then the engine produces sufficient power output, but the aftertreatment system takes too long to reach light-off temperature resulting in high emissions
Solution Approach 1:
The engine operates with only one or two cylinders firing at a time during cold start, segmenting the total power output across fewer cylinders. This concentrated heat generation rapidly warms the aftertreatment system while maintaining acceptable power delivery, reducing warm-up time and associated emissions
Solution Approach 2:
The patent applies different operating modes to different cylinders - some cylinders operate as exhaust springs while others fire normally. This local differentiation allows strategic heat generation in specific cylinders to prioritize aftertreatment warming without sacrificing overall engine performance
2Loss of time
If the engine uses skip fire control with lower firing fraction during cold start, then the aftertreatment system warms up faster, but the engine power output decreases
Solution Approach 1:
The patent dynamically changes the operating parameters of individual cylinders during skip fire cycles, switching between exhaust spring mode and fired mode. This allows optimization of thermal output for aftertreatment warming while maintaining overall power output through strategic parameter manipulation
Solution Approach 2:
The engine control system dynamically adjusts which cylinders fire and which operate as exhaust springs based on real-time temperature feedback. This dynamic reconfiguration optimizes the balance between power output and aftertreatment warming at each moment of the cold start process
3Temperature
If the engine operates with higher load per cylinder during cold start, then exhaust temperatures increase and aftertreatment warms faster, but fuel consumption increases
Solution Approach 1:
The patent applies partial action by having only one or two cylinders fire at a time rather than all cylinders. This partial firing generates sufficient heat for aftertreatment warming while consuming less fuel overall, avoiding excessive fuel consumption while achieving the necessary temperature rise
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
This approach rapidly heats up the aftertreatment systems and engine block, reducing pollution emissions and improving fuel efficiency by strategically managing exhaust and coolant temperatures, enabling quicker warm-up and reduced emissions during cold starts.
Implementation Method 1
use of different types of pneumatic cylinder springs during skipped firing opportunities
Implementation Method 2
The exhaust gases of firing just two cylinders will be hotter than firing all four cylinders due to various effects such as different heat transfer rates or burn rates
Implementation Method 3
combustion occurs in multiple cylinders or other working chambers
Implementation Method 4
different heat transfer rates or burn rates
Data Source
AI summary
A system and method for a variable displacement internal combustion engine using different types of pneumatic cylinder springs on skipped working cycles to control engine and aftertreatment system temperatures are described. The system and method may be used to rapidly heat up the aftertreatment system(s) and/or an engine block of the engine following a cold start by using one or more different types of pneumatic cylinder springs during skipped firing opportunities. By rapidly heating the aftertreatment system(s) and/or engine block, noxious emissions such as hydrocarbons, carbon monoxide, NOx and/or particulates, following cold starts are significantly reduced.