Direct Fuel Injector Temperature Mitigation via Intake Valve Timing

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Solution Overview

Problem

Existing multi-fuel engine systems face challenges in protecting direct fuel injectors from excessive tip temperatures, leading to potential damage and fouling, especially when switching between liquid and gaseous fuel modes, as current methods do not effectively manage thermal loads across all operating conditions.

Innovation Solution

The method involves determining the temperature of direct fuel injectors based on engine operating parameters and adjusting intake valve timing to maintain temperatures below a predetermined value, optionally retarding exhaust valve timing and advancing ignition timing, while introducing fumigated fuels to reduce thermal stress and prevent fouling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If liquid fuel is introduced through direct fuel injectors to cool the injectors, then injector temperature is reduced, but fuel consumption increases

Engineering Contradiction:

Improveinjector temperatureVSAvoidfuel consumption

Core Design Contradiction:

TemperatureVSUse of energy by moving object

Solution Approach 1:

The system determines the thermal load on direct fuel injectors in advance by monitoring engine operating parameters and stored energy values. When the thermal load exceeds a threshold, the control system proactively introduces liquid fuel through the direct injectors to cool them before excessive temperature damage or carbon deposit formation occurs, rather than waiting for actual temperature damage to manifest

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors engine operating parameters (engine speed, air mass flow, coolant temperature, equivalence ratio, combustion phasing) and calculates a stored energy value representing thermal load on the direct fuel injectors. This feedback loop allows the control system to adjust liquid fuel injection timing and quantity to cool the injectors only when necessary, optimizing the balance between injector temperature control and fuel consumption

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If direct fuel injectors are used in port injection natural gas fueled mode, then engine can operate on natural gas, but injector temperature rises above threshold causing damage and carbon deposits

Engineering Contradiction:

Improvefuel system adaptabilityVSAvoidinjector temperature

Core Design Contradiction:

Adaptability or versatilityVSTemperature

Solution Approach 1:

The system dynamically adjusts the cooling strategy based on real-time engine operating conditions. When operating in port injection natural gas mode, the control system continuously evaluates engine speed, air mass flow, coolant temperature, and other parameters to determine when liquid fuel cooling is necessary through the direct injectors, adapting the cooling intervention to match the current thermal load conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Liquid fuel introduced through the direct fuel injectors serves as a thermal intermediary, absorbing excess heat from the injector nozzles during port injection natural gas operation. The liquid fuel acts as a heat sink that temporarily absorbs thermal energy from the injectors, preventing carbon deposit formation and injector damage while the engine operates in natural gas mode

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If liquid fuel is introduced to cool direct fuel injectors, then injector temperature is controlled, but liquid fuel may remain dormant in injectors causing fouling

Engineering Contradiction:

Improveinjector temperatureVSAvoidinjector performance

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The control system implements periodic or cyclic liquid fuel injection through the direct fuel injectors during natural gas operation. Rather than continuous injection, the system introduces liquid fuel in periodic pulses that are sufficient to cool the injectors and prevent carbon deposits, then allows the injectors to clear the liquid fuel through normal engine operation, preventing liquid fuel accumulation and associated fouling issues

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 effectively reduces the risk of injector damage and fouling by maintaining optimal temperature ranges, minimizing fuel consumption, and improving engine performance across various operating modes.

Implementation Method 1

heat from combustion of port injected fuel elevates the temperature of the liquid fuel inside the direct fuel injectors

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

introducing a coolant through the direct fuel injector can reduce the temperature of the direct fuel injector

Methodology Applied

Scientific EffectHeat absorption: Absorption (physical)

Data Source

PatentUS11441509B2Fuel injector temperature mitigation

Publication Date: 2022.09.13 WESTPORT FUEL SYST CANADA INC

AI summary

A technique for fuel system protection for an internal combustion engine comprises determining direct fuel injector temperature as a function of engine operating parameters; and advancing intake valve timing when the temperature rises above a first predetermined value such that the temperature is maintained below a second predetermined value.