Fuel Pressure Control for Engine Startup Air Purging
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Solution Overview
Problem
Air trapped within the fuel rail during engine assembly can prevent the fuel pressure control system from providing a desired air/fuel mixture, leading to engine misfire, stalling, and diagnostic issues due to a lean air/fuel mixture when the engine is started for the first time.
Innovation Solution
A fuel pressure control system that selectively increases fuel pressure to a predetermined purging pressure greater than the startup pressure when the engine is first started, compressing trapped air and allowing for accurate air/fuel mixture control, comprising a pressure regulator module and a pressure increasing module that adjust fuel pressure based on engine coolant temperature and runtime conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine is started for the first time after assembly, then the fuel pressure control system provides a desired air/fuel mixture, but trapped air in the fuel rail causes lean mixture, misfire, and stalling
Solution Approach 1:
The system performs a preliminary action by increasing fuel pressure to a predetermined purging pressure before normal operation begins. This preliminary high pressure compresses and purges trapped air from the fuel rail, eliminating the harmful factor before it can cause misfire or stalling during normal engine operation.
Solution Approach 2:
The system changes the fuel pressure parameter dynamically based on engine conditions. During first startup after assembly, the pressure is increased to a higher predetermined purging pressure. During normal operation, the pressure is maintained at a lower predetermined operating pressure. This parameter change allows the system to address trapped air specifically when needed without affecting normal operation.
2Measurement precision
If fuel pressure is increased to compress trapped air, then air/fuel mixture control accuracy improves, but system complexity increases
Solution Approach 1:
The fuel pressure control system is made dynamic by allowing the pressure to vary between different predetermined levels based on engine conditions. The system transitions from a static fixed pressure system to a dynamic system that adjusts pressure between a lower operating pressure and a higher purging pressure, enabling accurate mixture control when needed without excessive complexity.
Solution Approach 2:
The system uses parameter changes by switching between discrete predetermined pressure values (lower operating pressure and higher purging pressure) rather than requiring continuous complex control. This approach achieves accurate air/fuel mixture control through simple parameter switching, avoiding the need for complex control mechanisms while maintaining precision.
3Reliability
If fuel pressure is maintained at high level continuously, then trapped air is compressed effectively, but energy consumption increases
Solution Approach 1:
The system applies periodic action by temporarily increasing fuel pressure to the predetermined purging pressure only during specific conditions (first startup after assembly or when trapped air is detected), then returning to the lower predetermined operating pressure. This periodic high pressure application effectively compresses trapped air without requiring continuous high energy consumption.
Solution Approach 2:
The high fuel pressure is applied as a preliminary action only when trapped air is present (during first startup after assembly). Once the trapped air is purged, the system returns to normal operation at lower pressure, avoiding unnecessary energy consumption during extended periods when trapped air is not an issue.
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
Enables accurate control of the air/fuel mixture by compressing trapped air in the fuel rail, preventing engine misfire and stalling, and ensuring proper engine operation during initial startup.
Implementation Method 1
The pressure increasing module selectively increases the fuel pressure to a second predetermined pressure... compressing trapped air and allowing for accurate air/fuel mixture control
Data Source
AI summary
A fuel pressure control system for a vehicle comprises a pressure regulator module and a pressure increasing module. The pressure regulator module regulates a fuel pressure supplied to an engine to a first predetermined pressure during an engine running period. The pressure increasing module selectively increases the fuel pressure to a second predetermined pressure during the engine running period when a counter value is one of greater than and less than a predetermined final value. The second predetermined pressure is greater than the first predetermined pressure, and the counter value is set to the predetermined final value after the engine is started for a first time after being assembled.