Fuel Return Device Vapor Purging High Pressure DI Rail
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Solution Overview
Problem
In direct injection fuel systems, fuel vaporization within the high pressure side can lead to abnormally high pressure, preventing fresh liquid fuel from being pumped in, which can cause engine stalling or prevent engine starting.
Innovation Solution
A fuel return device with an electronically controlled valve is used to purge the high pressure fuel rail before engine starting and to provide a continuous flow from the high pressure rail to the low pressure fuel supply system during engine operation, preventing vapor accumulation and maintaining efficient engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel is stored in the high pressure fuel rail after engine shutdown, then fuel availability is maintained, but fuel vaporization causes pressure to rise to abnormally high levels
Solution Approach 1:
The patent extracts the vaporized fuel from the high pressure fuel rail through a return line that connects to a check valve. This allows the harmful vaporized fuel to be removed from the system while maintaining the beneficial liquid fuel supply, directly resolving the contradiction between fuel availability and pressure buildup.
Solution Approach 2:
The check valve acts as an intermediary component that mediates between the high pressure fuel rail and the return line. It allows vaporized fuel to escape through the return line while preventing liquid fuel from leaking back, thus resolving the pressure issue without compromising fuel supply reliability.
2Reliability
If a check valve is used to prevent fuel escape, then fuel supply reliability is maintained, but vaporization prevents fresh liquid fuel from being pumped in
Solution Approach 1:
The return line extracts vaporized fuel from the high pressure fuel rail before it can interfere with the fuel pumping process. This removes the obstacle (vaporized fuel) that was preventing fresh liquid fuel from being pumped in, thereby restoring fuel pumping efficiency while maintaining supply reliability through the check valve.
Solution Approach 2:
The system takes preliminary action by providing a escape path for vaporized fuel through the return line and check valve configuration. This prevents vaporized fuel from accumulating and blocking the fuel pumping process, maintaining both reliability and productivity.
3Reliability
If the high pressure fuel rail is purged before engine starting, then vapor accumulation is prevented, but engine starting may be delayed
Solution Approach 1:
The system performs preliminary purging action through the return line and check valve before engine starting is attempted. This removes vapor accumulation in advance, ensuring reliable engine starting without requiring delays, as the purging occurs automatically as part of the system preparation.
Solution Approach 2:
The return line provides continuous vapor removal capability that operates throughout system operation. This continuous action ensures vapor accumulation never reaches problematic levels, eliminating the need for separate purging cycles that would delay engine starting.
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 fuel return device effectively reduces vaporization-related pressure issues, ensures smooth engine operation, and prevents stalling by continuously purging vapor and maintaining stable fuel pressure and temperature.
Implementation Method 1
a fuel pump that pumps fuel from a low pressure fuel supply system into the high pressure fuel rail
Implementation Method 2
A fuel return device is coupled to the high pressure side of the fuel system... An electronically controlled valve that regulates a fuel flow from the high pressure fuel rail to the low pressure fuel supply system
Implementation Method 3
fuel may also vaporize within the high pressure side of the DI fuel system... after the engine is turned off heat from the engine may vaporize fuel that remains in the high pressure fuel rail
Data Source
AI summary
A fuel return device couples to the high pressure side of a DI fuel system. The fuel return device provides for both continuous bleeding and occasional purging of fuel from the high pressure side to prevent issues related to vapor accumulation or heat-induced pressure increase. The fuel return device may be attached to a high pressure fuel rail in place of a sensor. The sensor may be attached the fuel return device. The fuel return device may include both an orifice that throttles the fuel flow through the fuel return device and a solenoid that allows the flow rate to be increased.