Fuel System Pressure Pulsation Reduction
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Solution Overview
Problem
Existing fuel systems for internal combustion engines that combine port fuel injection (PFI) and gasoline direct injection (GDi) face issues such as high-pressure fuel pump temperature elevation and vapor creation when only PFI is used, leading to undesirable conditions and potential fueling hindrances, as well as susceptibility to pressure pulsations.
Innovation Solution
A fuel system design that includes a low-pressure fuel delivery unit, a high-pressure fuel delivery unit with distinct pressure regions, and a means to reduce fuel pressure pulsations, ensuring the high-pressure unit is lubricated and cooled even when only low-pressure fuel injectors are used, using features like orifices, check valves, or accumulators to mitigate pressure pulsations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the high-pressure fuel pump is cycled by the camshaft when only PFI is used, then the PFI system can operate independently, but the fuel temperature in the high-pressure fuel pump elevates and vapor may be created
Solution Approach 1:
The fuel delivery system is segmented into two separate circuits: a low-pressure circuit for PFI and a high-pressure circuit for GDi. The low-pressure circuit includes a low-pressure fuel pump and low-pressure fuel rail, while the high-pressure circuit includes the high-pressure fuel pump and high-pressure fuel rail. This segmentation allows independent operation of each system while preventing temperature elevation in the high-pressure pump when only PFI is used.
Solution Approach 2:
A pressure reducing valve is introduced as an intermediary component between the low-pressure fuel rail and the high-pressure fuel pump inlet. This valve enables controlled fuel flow from the low-pressure circuit to the high-pressure pump, allowing the pump to be cooled and lubricated without requiring full high-pressure operation.
2Reliability
If fuel flows through the drive section of the high-pressure fuel pump to provide lubrication and cooling, then the pump is protected, but the PFI system becomes susceptible to pressure pulsations
Solution Approach 1:
The fuel flow path is designed with local quality differentiation: fuel flows through the drive section of the high-pressure pump for lubrication and cooling, but a pressure reducing valve is placed at the inlet to the high-pressure pump to isolate pressure pulsations. This allows the pump to receive lubrication while the PFI system maintains stable pressure.
Solution Approach 2:
A pressure reducing valve is introduced as an intermediary between the low-pressure fuel rail and the high-pressure fuel pump inlet. This valve reduces pressure and filters out pressure pulsations from the PFI system, allowing stable low-pressure fuel delivery while still enabling fuel flow through the pump for lubrication and cooling.
3Stability of the object's composition
If a means for reducing fuel pressure pulsations is added between the low-pressure region and low-pressure fuel rail, then pressure pulsations are minimized, but the system complexity increases
Solution Approach 1:
A pressure reducing valve is introduced as an intermediary component between the low-pressure fuel rail and the high-pressure fuel pump inlet. This single component serves multiple functions: reducing pressure, filtering pressure pulsations, and enabling controlled fuel flow for pump lubrication, thereby minimizing system complexity while achieving pressure stability.
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 design minimizes audible noise, cylinder-to-cylinder fuel delivery variation, and adverse effects caused by pressure pulsations, while maintaining effective lubrication and cooling of the high-pressure fuel delivery unit, even when only low-pressure fuel injectors are active.
Implementation Method 1
a means for reducing fuel pressure pulsations, the means for reducing fuel pressure pulsations being located between the low-pressure region and the low-pressure fuel rail
Implementation Method 2
allows the high-pressure fuel delivery unit to be lubricated and cooled even when only the low-pressure fuel injectors are being used to supply fuel to the internal combustion engine
Data Source
AI summary
A fuel system includes a low-pressure fuel delivery unit and a high-pressure fuel delivery unit which has a low-pressure region and a high-pressure region such that the low-pressure region supplies fuel to the high-pressure region which supplies the fuel to a plurality of high-pressure fuel injectors. A low-pressure fuel rail supplies fuel to low-pressure fuel injectors. A low-pressure fuel injector line is connected at a first end directly to the high-pressure fuel delivery unit and receives fuel from the low-pressure region and is connected at a second end directly to the low-pressure fuel rail, thereby providing fluid communication from the low-pressure region to the low-pressure fuel rail. A device is located between the low-pressure region and the low-pressure fuel rail and reduces fuel pressure pulsations.