Common Rail Fuel Heating System for Cold Start Viscosity
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Solution Overview
Problem
High pressure fuel delivery systems in internal combustion engines are susceptible to fuel leakage, which can lead to fuel spraying onto hot engine surfaces and causing fires, and during cold starts, viscous fuel can cause flow limiters to close, preventing engines from achieving full speed and power due to increased viscosity.
Innovation Solution
A system and method that includes a high pressure fuel line with plural fuel injectors connected in series and a continuous low pressure passage with a heat exchanging portion, where a heated fluid source circulates heated fluid through the low pressure passage to heat the fuel in the high pressure line, reducing viscosity and preventing unintended flow limiter closings, and includes a mechanism to detect fuel leakage and redirect it to a containment system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a common rail fuel delivery system is used to maintain high pressure for precise injection control, then injection timing precision is improved, but the system becomes susceptible to fuel leakage that can cause fires
Solution Approach 1:
The fuel delivery system is segmented into a high-pressure common rail for precise injection control and a separate low-pressure containment system with double-wall structure. The containment system divides the fuel path into an inner high-pressure passage and an outer low-pressure passage, isolating leakage risks from the precision fueling function.
Solution Approach 2:
The low-pressure containment system is installed beforehand as a protective barrier around the high-pressure fuel line. This containment structure is prepared in advance to catch and control any fuel that leaks from the high-pressure system, preventing fire hazards before they can occur.
2Adaptability or versatility
If fuel is stored in the common rail at high pressure for independent injection timing, then injection timing independence from engine speed is improved, but fuel viscosity increases during cold starts causing flow limiter closings
Solution Approach 1:
A heated fluid circulation system is implemented to preheat the fuel in the common rail and fuel lines before cold start conditions occur. The heated fluid circulates through passages in the common rail and fuel lines during shutdown periods, maintaining fuel temperature and reducing viscosity in advance of cold start requirements.
Solution Approach 2:
A heated fluid (intermediary substance) is introduced into the fuel system to transfer thermal energy to the fuel. This heated fluid circulates through the common rail and fuel lines, acting as a mediator to maintain fuel temperature without directly mixing with the fuel, thereby preventing viscosity increase and flow limiter closings during cold starts.
3Object-affected harmful factors
If a double wall containment structure is used to control fuel leakage, then fire safety is improved, but the system complexity increases
Solution Approach 1:
The low-pressure containment system is designed to perform multiple functions: it contains fuel leakage from the high-pressure line, provides a path for heated fluid circulation to prevent cold start viscosity issues, and offers structural support. This multi-functionality reduces the need for separate systems and minimizes overall complexity.
Solution Approach 2:
The containment structure is merged with the fuel delivery system by integrating the double-wall construction into the common rail and fuel lines. The inner and outer walls are combined with connection features and sealing mechanisms that create a unified structure, reducing the number of separate components and simplifying assembly.
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 effectively reduces fuel viscosity during cold starts, preventing flow limiter closings and ensuring rapid engine startup, while also containing and detecting fuel leakage to prevent hazards, thus enhancing engine performance and safety.
Implementation Method 1
a continuous low pressure passage including a heat exchanging portion in close proximity to the high pressure fuel line
Implementation Method 2
a heated fluid source operative to fluidly communicate with the continuous low pressure passage and circulate heated fluid
Data Source
AI summary
This disclosure relates a system for heating fuel supplied by a common rail fuel supply to an internal combustion engine. The system includes a high pressure fuel line, plural fuel injectors connected in series along the high pressure fuel line in the common rail, and a continuous low pressure passage including a heat exchanging portion in close proximity to the high pressure fuel line. A heated fluid source is operative to fluidly communicate with the continuous low pressure passage and circulate heated fluid to heat fuel present in the high pressure fuel line prior to, and during a cold start operation of the internal combustion engine. Other embodiments relate to a method of providing fuel to an internal combustion engine that includes sensing the temperature of fuel supplied to a fuel system and determining whether the sensed fuel temperature is greater than a predetermined value. The method includes circulating heated fluid in a continuous low pressure circuit to heat fuel present in a high pressure fuel line if the sensed fuel temperature is less than or equal to a predetermined value, and evacuating fluid for heating fuel from a portion of the continuous low pressure passage and fluidly connecting the evacuated portion of the continuous low pressure passage to a fuel leakage detection device if the sensed fuel temperature is greater than the predetermined value.