Active Expansion Chamber Accumulator for Fuel Pressure Control
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Solution Overview
Problem
Internal combustion engines face issues with increased evaporative emissions and hot restart problems due to residual fuel pressure in fuel lines after engine shut-off, which existing solutions like hydrocarbon absorbers address inadequately, being costly and requiring external hardware.
Innovation Solution
A fuel delivery system incorporating an active expansion chamber accumulator that actively adjusts its volume using a motor-driven plunger assembly to maintain fuel pressure below a threshold, preventing fuel leakage at injectors, and utilizing sensors to model pressure changes and adjust accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a hydrocarbon absorber is used to manage residual fuel pressure, then evaporative emissions are reduced, but the system becomes more costly and requires external hardware
Solution Approach 1:
The accumulator is integrated directly into the fuel delivery system, merging the pressure management function with the existing fuel rail structure. This eliminates the need for separate external hydrocarbon absorbers while maintaining evaporative emissions control
Solution Approach 2:
The system uses the engine control unit and existing fuel pressure sensor to automatically control the accumulator via an actuator, allowing the system to self-regulate residual pressure without requiring external hardware or additional control systems
2Reliability
If residual pressure is maintained in fuel lines after engine shut off, then fuel delivery readiness is improved, but fuel leakage at injector tips increases
Solution Approach 1:
The accumulator features an adjustable expansion chamber whose volume can be dynamically changed by an actuator. This allows the system to actively manage fuel pressure by varying the chamber volume, enabling pressure reduction after engine shut-off to prevent leakage while maintaining readiness
Solution Approach 2:
The system changes the physical parameter of chamber volume to control fuel pressure. By adjusting the expansion chamber volume, the system can modulate pressure levels to prevent fuel leakage at injector tips while maintaining fuel delivery readiness
3Productivity
If fuel pressure is increased in the fuel rail, then combustion performance is improved, but hot restart issues occur due to fuel boiling
Solution Approach 1:
The system uses feedback from the fuel pressure sensor and engine control unit to monitor and adjust fuel pressure in real-time. This feedback mechanism allows the system to reduce pressure when conditions indicate risk of fuel boiling, preventing hot restart issues while maintaining combustion performance
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
Effectively reduces fuel leakage and maintains consistent fuel rail pressure, thereby minimizing evaporative emissions and ensuring reliable hot starts without the need for external hardware, enhancing engine performance and reducing emissions.
Implementation Method 1
a lead screw threadably engaged with the hub
Implementation Method 2
the seal is in sealing arrangement between the plunger and an interior wall of the housing
Implementation Method 3
the actuator is a motor with an output shaft coupled to the lead screw
Implementation Method 4
a fuel pressure sensor configured to sense a pressure in the fuel delivery system
Data Source
AI summary
A fuel delivery system for a vehicle having an engine includes a fuel injection system, a fuel supply line configured to supply fuel from to the fuel injection system, and a fuel pressure sensor. An active expansion chamber (AEC) accumulator is fluidly coupled to the fuel supply line and includes a housing defining an interior chamber and an adjustable expansion chamber, a plunger assembly separating the interior chamber and the adjustable expansion chamber, and an actuator configured to selectively move the plunger assembly to actively adjust a volume of the adjustable expansion chamber. A controller is configured to detect a pressure change condition in the fuel delivery system and, in response, automatically adjust the volume of the adjustable expansion chamber to maintain the pressure of the fuel delivery system below a predetermined threshold to thereby facilitate preventing fuel leakage at the fuel injectors when the engine is shut off.