Skip Fire Control for Dual Fuel Engine Efficiency

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Solution Overview

Problem

Dual fuel engine systems face inefficiencies in low-load operations due to varying combustion parameters of hydrogen and diesel, leading to suboptimal engine efficiency and emissions, particularly during idling or low-load conditions.

Innovation Solution

The method involves selectively skipping combustion in certain cylinders of a dual fuel engine by injecting a combination of hydrogen and diesel only to a subset of cylinders while disabling fuel injection in the remaining cylinders, adjusting the fuel ratio based on engine load, speed, temperature, and EGR demand, and rotating the active cylinders to ensure all cylinders are cycled through.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fuel is injected to all cylinders during low-load operations, then engine power output is maintained, but fuel consumption increases and combustion efficiency decreases

Engineering Contradiction:

Improveengine power outputVSAvoidfuel consumption

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The engine cylinders are divided into two groups: active cylinders that receive fuel injection and combust, and inactive cylinders that skip combustion. This segmentation allows the engine to maintain power output through the active cylinders while reducing overall fuel consumption by eliminating combustion in the inactive cylinders during low-load operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of fueling all cylinders, the system applies partial action by injecting fuel only to a subset of cylinders (e.g., 3 out of 6 cylinders). This partial fueling strategy maintains sufficient power output while reducing fuel consumption and improving combustion efficiency in the active cylinders.

Inventive Principle:

Principle #16Partial or excessive action

2Use of energy by moving object

If hydrogen and diesel are co-combusted in all cylinders, then energy density is maximized, but combustion control becomes difficult and emissions increase

Engineering Contradiction:

Improveenergy densityVSAvoidcombustion control

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

Cylinders are segmented into active and inactive groups, allowing the complex hydrogen-diesel co-combustion process to be confined to only the active cylinders. This reduces the overall complexity of combustion control while maintaining the high energy density benefits of hydrogen co-combustion in the active cylinders.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fuel injection strategy applies different qualities to different cylinders: active cylinders receive a controlled mixture of hydrogen and diesel for high energy density, while inactive cylinders receive no fuel injection. This local differentiation simplifies overall combustion control while preserving the energy benefits where needed.

Inventive Principle:

Principle #3Local quality

3Loss of energy

If fuel injection is disabled in some cylinders, then fuel consumption decreases, but engine temperature distribution becomes uneven

Engineering Contradiction:

Improvefuel consumptionVSAvoidengine temperature distribution

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The system implements periodic rotation of active and inactive cylinder assignments. Over time, each cylinder experiences both active and inactive roles, ensuring uniform temperature distribution across all cylinders while maintaining reduced fuel consumption through the skip-fire strategy.

Inventive Principle:

Principle #19Periodic action

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 improves combustion efficiency by increasing fuel delivery to active cylinders, reducing air-fuel ratio, and enhancing engine performance while reducing carbon emissions and deposits, particularly during low-load operations.

Implementation Method 1

The fuel injector may be configured to deliver a precise amount of fuel to the combustion chamber

Methodology Applied

Scientific EffectFuel injection:

Implementation Method 2

The piston may be configured to compress air in the combustion chamber during a compression stroke

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

The spark plug may be configured to ignite the compressed air and fuel mixture with an electric spark

Methodology Applied

Scientific EffectSpark ignition: Electric Spark

Implementation Method 4

The exhaust valve may be configured to open during an exhaust stroke to allow exhaust to exit the combustion chamber

Methodology Applied

Scientific EffectExhaust gas flow:

Implementation Method 5

The intake valve may be configured to open during an intake stroke to allow air and fuel to enter the combustion chamber

Methodology Applied

Scientific EffectIntake charge flow:

Implementation Method 6

combustion of more than one type of fuel at an engine... Co-combustion of hydrogen and diesel

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS11821375B2Methods and systems for skip fire in a multi fuel engine

Publication Date: 2023.11.21 TRANSPORTATION IP HOLDINGS LLC

AI summary

Various methods and systems are provided for skipping fire in one or more cylinders in a dual fuel engine. In one example, a method may include injecting a combination of two fuels to a first set of cylinders of the engine while disabling fuel injection to all remaining cylinders of the engine.