What is the function of the high-pressure fuel pump?
2 Answers
High-pressure fuel pump function is: to increase fuel pressure for high-pressure injection to achieve atomization effect. The main purpose of the high-pressure fuel pump is to serve as the power source for hydraulic devices such as jacks, heading machines, extruders, and cotton gins. Regarding the working principle of the high-pressure fuel pump as follows: 1. Suction stroke: During the suction process, the downward movement of the pump piston provides suction power while opening the intake valve, allowing fuel to be drawn into the pump chamber. In the final third of the pump stroke, the fuel pressure regulator valve is energized, keeping the intake valve open during the initial upward movement of the pump piston for fuel return. 2. Return stroke: To control the actual fuel supply, the intake valve remains open during the initial upward movement of the pump, with excess fuel being pushed back to the low-pressure side by the pump piston. The pressure accumulator absorbs fluctuations generated during this process. 3. Pumping stroke: At the beginning of the pumping stroke, the fuel pressure regulator valve is de-energized, causing the intake valve to close under the combined action of rising pump chamber pressure and the valve's closing spring. The upward movement of the pump piston creates pressure in the pump chamber, and when this pressure exceeds the rail pressure, the outlet valve opens to pump fuel into the rail.
The high-pressure fuel pump's role is to pressurize the fuel and then deliver it to the engine's fuel injectors. Without sufficient pressure, the fuel either won't inject properly or will spray unevenly, causing severe engine shaking, weak acceleration, or even stalling. I've encountered many such failures while helping friends repair cars—the noise is particularly noticeable, with a rough chugging sound upon startup, which is extremely annoying. This pump is most prone to issues in direct injection engines because the fuel must be directly injected into the cylinders under high pressure for proper atomization to ensure clean combustion. If it fails, fuel efficiency drops drastically, and the car may emit black smoke, polluting the environment. Timely replacement or inspection is crucial to avoid breakdowns on the road. Overall, it acts like a powerful pusher for engine fuel supply, ensuring smooth and safe driving.
