Dual Pressure Hydrogen Fuel Injection System for Knock Mitigation
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Solution Overview
Problem
Current fuel injection systems for hydrogen in internal combustion engines face challenges with pre-ignition and knock due to high in-cylinder peak pressures, especially when using port injection, and struggle to maintain high pressure for direct injection, leading to inefficient hydrogen substitution ratios and increased carbon emissions.
Innovation Solution
A dual pressure fueling system that enables high pressure direct injection (HPDI) and low pressure direct injection (LPDI) or port injection (PI) by modulating hydrogen delivery pressure based on engine operation, using a multi-fuel pressure system with mechanisms to maintain sufficient pressure for HPDI, such as sequential tank usage and pressure redistribution, and incorporating a pump to boost delivery pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If port injection of hydrogen is used, then high in-cylinder peak pressure is achieved, but pre-ignition and knock increase
Solution Approach 1:
The system changes the injection pressure parameter dynamically, switching between high pressure (for direct injection to avoid knock) and low pressure (for port injection to achieve high in-cylinder pressure). This resolves the contradiction by selecting different pressure regimes for different operational requirements, thereby achieving both high power output and reduced knock when needed.
2Object-affected harmful factors
If high pressure direct injection is used, then knock is reduced, but fuel delivery pressure must be maintained high which is difficult to sustain
Solution Approach 1:
The system dynamically adjusts the fuel delivery pressure based on operational needs rather than maintaining constant high pressure. A dual-pressure fuel delivery system is implemented where pressure can be switched between high and low states, reducing the complexity of continuously maintaining high pressure while still enabling knock-reducing direct injection when required.
Solution Approach 2:
The fuel delivery system is segmented into separate high-pressure and low-pressure delivery paths, allowing the system to select appropriate pressure levels for different injection modes. This segmentation reduces the complexity of pressure maintenance by isolating the high-pressure requirement to only when direct injection is needed.
3Loss of substance
If hydrogen substitution ratio is increased, then carbon emissions are reduced, but auto-ignition and pre-ignition are exacerbated
Solution Approach 1:
The system changes injection parameters (pressure and mode) based on the hydrogen substitution ratio. When high hydrogen substitution is used to reduce carbon emissions, the system switches to high pressure direct injection to prevent auto-ignition and pre-ignition. This resolves the contradiction by adapting injection parameters to the fuel composition, enabling high hydrogen substitution without the harmful effects.
4Stress or pressure
If pump is used to increase pressure at fuel reservoir, then high pressure direct injection is enabled, but efficiency and reliability decrease
Solution Approach 1:
The system dynamically uses a pump only when high pressure is required for direct injection, rather than continuously operating. The pump is activated selectively based on operational needs, improving reliability by avoiding continuous operation while still enabling high pressure direct injection when necessary.
Data Source
AI summary
Various methods and systems are provided for a method for a multi-pressure fueling system. In one example, the multi-pressure fueling system includes providing a first fuel delivery pressure enabling high pressure direct injection of a fuel at a first injector and a second fuel delivery pressure insufficient for high pressure direct injection, at a second injector, based on engine operation.