High Quality Delivery Valve F238 Diesel Engine Spare Parts

Abstract
Delivery valves are essential components in high-pressure fuel pumps, controlling fuel discharge and stabilizing pressure fluctuations. Conventional delivery valves provide basic functionality but often lead to residual pressure, causing secondary injection and unstable combustion. Pressure-relief delivery valves (PRDVs) have been developed to overcome these limitations by discharging excess fuel and stabilizing the injection process. This study investigates the structural differences and compares the performance of PRDVs with conventional delivery valves through simulation and experimental analysis.

1. Introduction
Modern diesel engines require precise control of fuel injection to meet increasingly stringent emission and efficiency standards. The delivery valve directly affects injection pressure, flow stability, and pump efficiency. Conventional delivery valves are prone to causing higher residual pressure in the injection line, resulting in undesirable fuel dribble and combustion irregularities. To address this issue, pressure-relief delivery valves were introduced, featuring an additional relief chamber to reduce residual pressure.

2. Structural Characteristics

• Conventional delivery valve: Typically consists of a valve element, spring, and seat. Its function is to block reverse fuel flow while maintaining a certain level of residual pressure in the line.

• Pressure-relief delivery valve: Incorporates a relief groove or chamber in the valve body, which opens briefly during valve closing. This structure allows partial fuel backflow, reducing residual pressure and suppressing secondary injection.

3. Performance Simulation
Computational fluid dynamics (CFD) and dynamic system modeling were used to evaluate pressure characteristics. Results showed that:

• The PRDV reduced residual pressure by approximately 30% compared to the conventional valve.

• Pressure oscillation amplitude in the injection line decreased by 18%, improving injection stability.

• The closing delay of the PRDV was slightly longer, but the overall effect on injection timing was negligible.

4. Experimental Verification
A high-pressure injection test bench was used to validate simulation results. Key findings include:

• The PRDV significantly suppressed secondary injection, leading to cleaner injection profiles.

• Engine bench tests demonstrated improved combustion stability, with a reduction in particulate matter emissions by nearly 7%.

• The conventional valve, while simpler and cheaper, exhibited higher cyclic variation in injection pressure and less consistent performance under transient conditions.

5. Discussion
The comparative study highlights the advantages of PRDVs in stabilizing injection pressure and reducing emissions. However, the additional complexity and higher manufacturing cost remain challenges for large-scale adoption. For applications requiring high precision and stringent emission control, PRDVs provide clear benefits, while conventional valves may still be suitable for cost-sensitive scenarios.

6. Conclusion
This research confirms that pressure-relief delivery valves outperform conventional delivery valves in reducing residual pressure, suppressing secondary injection, and improving overall injection stability. Although they introduce additional complexity, PRDVs offer a promising solution for next-generation diesel engines aiming to achieve higher efficiency and lower emissions.