Fuel Rail Heating for Cold Start Emission Reduction
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Solution Overview
Problem
Gasoline direct-injection engines emit particulate matter during the first 500 seconds of the Federal Test Procedure due to fuel contacting combustion chamber surfaces, which are not yet warmed up, making preheating complex and energy-intensive.
Innovation Solution
The fuel is heated to vaporize more readily before entering the combustion chamber, using a fuel rail and engine coolant circuit with a thermostat and electrical heating elements, ensuring minimal liquid fuel impact on surfaces during cold starts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the combustion chamber surfaces are preheated prior to starting the engine, then particulate matter emissions are reduced, but the system complexity and energy consumption increase significantly
Solution Approach 1:
The patent introduces fuel rail heating as an intermediary solution between the coolant system and the combustion chamber. By heating the fuel rail (which contains liquid fuel) rather than directly heating the combustion chamber surfaces, the system reduces particulate matter emissions through a simpler, indirect approach. The heated fuel rail ensures fuel vaporization occurs before injection, preventing liquid fuel contact with cold surfaces.
Solution Approach 2:
The patent replaces complex mechanical preheating systems with an electrical heating element integrated into the fuel rail. This electrical heating system is controlled by the powertrain control module, substituting elaborate mechanical preheating machinery with a simpler electrical solution that achieves the same emission reduction goal.
2Object-generated harmful factors
If combustion chamber surfaces are preheated prior to starting the engine, then particulate matter emissions are reduced, but energy consumption increases
Solution Approach 1:
The patent applies preliminary heating action to the fuel rail before engine operation begins. The powertrain control module activates the heating element in the fuel rail during the cold start condition, ensuring fuel is pre-heated and ready for immediate vaporization upon injection. This preliminary action prevents the need for more energy-intensive combustion chamber preheating while achieving the same emission control objective.
3Object-generated harmful factors
If fuel is heated to vaporize more readily before entering the combustion chamber, then particulate matter emissions are reduced, but additional heating components are required
Solution Approach 1:
The patent makes the fuel rail serve multiple functions: it stores liquid fuel during normal operation and acts as a heating chamber during cold starts. The same fuel rail structure is utilized for both fuel storage and fuel heating purposes, eliminating the need for separate dedicated heating components. The heating element is integrated within the existing fuel rail geometry, achieving multi-functionality without adding substantial complexity.
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 particulate matter emissions by ensuring fuel is mostly vaporized upon injection, improving engine efficiency and reducing emissions during cold starts without the need for complex preheating.
Implementation Method 1
an electrical heating element disposed within the fuel rail to assist in heating the fuel beyond that from the coolant
Implementation Method 2
a mechanical thermostat that is closed at a temperature below a predetermined temperature and is open at a temperature exceeding the predetermined temperature
Implementation Method 3
the fuel is heated so that it vaporizes more readily when introduced in the combustion chamber
Implementation Method 4
a portion of the water jacket proximate the exhaust ports and ducts leading out of the cylinders is coupled to the branch of the water jacket leading to the fuel rail
Data Source
AI summary
It has been found that direct-injection gasoline engines emit particulate matter during the first 500 seconds of operation due to fuel impacting combustion chamber surfaces. To largely overcome the fuel penetrating to surfaces in the combustion chamber, the fuel may be heated. In one embodiment, engine coolant that is heated in the water jacket portions nearest exhaust ducts is provided directly to a tube in physical contact with the fuel rail. In some embodiments, the tube is provided with an electric heating element. If the coolant pump is turned off at the initial portions of a cold start, the electric heater raises the temperature of the fuel in the fuel rail. After engine coolant temperature raises, water, warm coolant is provided to the tube proximate the fuel rail and the heater is turned off.