Hydrogen Engine Fuel Injection Timing for Preignition Control
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Solution Overview
Problem
Gaseous hydrogen fuel engines face challenges in controlling undesired combustion, such as preignition and backfiring, due to hydrogen's low flammability limit and fast flame speed, which are not effectively addressed by existing technologies.
Innovation Solution
The method involves controlling the injection timing of gaseous hydrogen fuel relative to the intake valve position in a gaseous hydrogen fuel engine system, producing a leading cooling flow of pressurized intake air, a trailing purging flow of intake air, and a middle flow of both air and fuel, to create a controlled combustion charge and limit undesired combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If gaseous hydrogen fuel is used in the engine, then emission reduction is improved, but undesired combustion (preignition and backfiring) increases due to hydrogen's low flammability limit and fast flame speed
Solution Approach 1:
The intake valve is opened before top dead center (BTDC) to allow pressurized intake air to enter and cool the cylinder and intake port ahead of combustion. This preliminary cooling action prevents preignition by reducing temperatures in zones where hydrogen fuel might otherwise ignite prematurely, while still enabling the emission benefits of hydrogen combustion.
Solution Approach 2:
The patent separates the fuel injection timing from the combustion timing by injecting hydrogen fuel after top dead center (ATDC) while the intake valve is still open. This extracts the fuel introduction step from the traditional pre-combustion timing, allowing the fuel to be carried into the cylinder by the incoming air flow without causing preignition in the intake port or on hot surfaces.
2Productivity
If hydrogen fuel is injected early to ensure complete combustion, then combustion efficiency is improved, but preignition risk increases due to hydrogen's fast flame speed
Solution Approach 1:
The intake valve opens BTDC to establish a cool, pressurized air flow path before fuel injection. This preliminary preparation of the combustion environment allows subsequent fuel injection to occur safely without preignition, while the pressurized air ensures rapid and complete combustion of the hydrogen fuel for high efficiency.
Solution Approach 2:
The patent dynamically adjusts the injection timing to occur ATDC when the intake valve is open, allowing the fuel to be injected into the moving air flow. This dynamic timing strategy adapts to the piston motion and valve timing to optimize both combustion completeness and preignition prevention, achieving high efficiency without sacrificing reliability.
3Productivity
If the intake valve closes early to trap the combustion charge, then combustion completeness is improved, but fuel may remain in the intake port causing backfiring
Solution Approach 1:
The patent extracts the fuel injection step from the traditional closed-valve timing and performs it ATDC while the intake valve remains open. This allows any unburned fuel to be continuously purged by the incoming pressurized air flow, preventing fuel accumulation in the intake port that would cause backfiring, while still achieving complete combustion in the cylinder.
Solution Approach 2:
The intake valve remains open during and after fuel injection to maintain continuous purging of the intake port with fresh pressurized air. This continuous action prevents fuel residue accumulation and eliminates the backfiring hazard, while the cylinder maintains sufficient charge for complete combustion through the sustained air flow.
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 preignition and backfiring by maintaining cooler temperatures and ensuring complete purging of the intake port, thereby enhancing the operational stability and emission profiles of gaseous hydrogen fuel engines.
Implementation Method 1
cooling a cylinder in a gaseous hydrogen fuel engine via a flow of pressurized intake air admitted into the cylinder via an intake valve
Implementation Method 2
forming a combustion charge of the gaseous hydrogen fuel and pressurized intake air in the cylinder
Implementation Method 3
igniting the combustion charge in the cylinder
Data Source
AI summary
Operating a gaseous hydrogen fuel engine includes controlling an injection timing of a gaseous hydrogen fuel injected into a flow of pressurized intake air so as to produce a leading cooling flow of pressurized intake air into a cylinder in an engine, a trailing purging flow through an intake conduit, and a middle flow of both pressurized intake air and gaseous hydrogen fuel into the cylinder. Undesired combustion such as preignition and/or backfire can be limited. Related apparatus and control logic is also disclosed.