Dual-Fuel Engine Control With Nested Loops for Knock and NOx

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Solution Overview

Problem

Dual fuel internal combustion engines face challenges in maintaining engine knock and nitrogen oxides (NOx) emission levels while maximizing fuel economy and substitution rate of secondary fuels, particularly when operating with different fuels having varying properties.

Innovation Solution

An engine control system with a controller that adjusts injection timing (SOI), substitution rate, and air-to-fuel ratio (lambda) using nested control loops to manage engine knock and NOx levels, allowing for efficient use of secondary fuels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the substitution rate of secondary fuel is increased to maximize fuel economy and reduce environmental impact, then fuel efficiency improves, but engine knock and NOx emissions increase

Engineering Contradiction:

Improvefuel efficiencyVSAvoidengine knock and NOx emissions

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The system dynamically adjusts injection timing (SOI) and air-to-fuel ratio (lambda) based on real-time engine operating conditions and knock sensor feedback. The controller continuously modifies these parameters to maintain optimal combustion characteristics across varying loads and speeds, enabling high substitution rates without excessive knock or emissions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses knock sensors to detect engine knock in real-time and feeds this information back to the controller. The controller then adjusts injection timing and air-to-fuel ratio to eliminate knock while maintaining high secondary fuel substitution rates. This closed-loop control enables the system to operate at the boundary of knock limits safely

Inventive Principle:

Principle #23Feedback

2Object-generated harmful factors

If injection timing is adjusted to reduce engine knock, then knock levels decrease, but start of injection deviates from target timing reducing efficiency

Engineering Contradiction:

Improveengine knockVSAvoidinjection timing accuracy

Core Design Contradiction:

Object-generated harmful factorsVSProductivity

Solution Approach 1:

The system performs preliminary adjustments to injection timing based on predicted knock tendencies from operating conditions (load, speed, temperature). By pre-adjusting SOI before knock occurs, the system prevents knock without requiring large reactive timing changes that would compromise efficiency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically balances knock reduction with timing accuracy by continuously adjusting SOI based on knock sensor feedback. Small incremental timing adjustments are made to achieve knock suppression while maintaining injection timing as close as possible to the target value for optimal efficiency

Inventive Principle:

Principle #15Dynamics

3Productivity

If air-to-fuel ratio is adjusted to control substitution rate, then fuel economy improves, but engine knock increases

Engineering Contradiction:

Improvefuel economyVSAvoidengine knock

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The system changes multiple parameters simultaneously (injection timing, air-to-fuel ratio, substitution rate) to achieve knock reduction. By coordinating adjustments across these parameters, the system can lean out the mixture for better economy while compensating with timing advances to prevent knock

Inventive Principle:

Principle #35Parameter changes

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

The system improves engine efficiency, increases secondary fuel substitution rate, reduces operating costs, and minimizes environmental impact by effectively controlling engine knock and NOx emissions.

Implementation Method 1

initiation of injection adjusts a timing of injecting the primary fuel into a cylinder of the engine

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 2

determine a first adjusted substitution rate of the secondary fuel to enable the start of injection of the primary fuel to move back to the target start of injection

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 3

determine an adjusted air-to-fuel ratio to adjust the first adjusted substitution rate of the secondary fuel

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS20250305463A1Engine control system, method for controlling a dual fuel engine, and non-transitory computer-readable medium

Publication Date: 2025.10.02 CUMMINS POWER GENERATION INC

AI summary

An engine control system for an engine using a primary fuel and a secondary fuel is provided. The engine control system includes a controller configured to determine a first adjusted start of injection to satisfy an engine knock threshold responsive to an engine knock signal value exceeding the engine knock threshold. The controller is further configured to determine, based at least in part on the first adjusted start of injection and a target start of injection, a first adjusted substitution rate of the secondary fuel to adjust the first adjusted start of injection to the target start of injection and determine, based at least in part on the first adjusted substitution rate of the secondary fuel and a target substitution rate of the secondary fuel, an adjusted air-to-fuel ratio to adjust the first adjusted substitution rate of the secondary fuel to the target substitution rate of the secondary fuel.