Piston pump working principle introduced
Piston pumps are essential components in hydraulic systems, widely used due to their high operating voltage, ease of flow control, and efficiency. These pumps operate through three main stages: the oil intake phase, fuel supply phase, and return oil phase.
During the oil intake process, when the cam lobe rotates and lifts the plunger, the spring pushes the plunger downward, creating a vacuum in the pump chamber above the plunger. Once the plunger’s upper surface aligns with the oil inlet hole on the sleeve, diesel fuel from the fuel line enters the pump chamber through the hole. The plunger moves to the bottom dead center, completing the intake phase.
In the fuel supply stage, as the cam continues to lift the plunger, the spring compresses, and the plunger rises. Fuel is pushed into the high-pressure line, and once the plunger covers the oil inlet hole, the tight clearance between the plunger and sleeve (0.0015–0.0025 mm) creates a sealed chamber. As the plunger continues upward, pressure builds rapidly, exceeding the spring force and the residual pressure in the high-pressure tubing. This opens the delivery valve, allowing high-pressure diesel to be injected into the combustion chamber via the nozzle.
The return phase occurs when the plunger reaches a groove on the sleeve, connecting the pump chamber to the return oil passage. This causes a sudden drop in pressure, and the delivery valve closes quickly under spring force, stopping the fuel supply. When the cam lobe rotates back, the spring pushes the plunger down again, starting the next cycle.
A piston pump works by using two check valves. When the plunger moves backward, it creates a vacuum, drawing fluid into the cylinder through one valve. When the plunger moves forward, the other valve opens, allowing the fluid to be compressed and discharged. This continuous motion ensures a steady flow of fluid.
Proper maintenance is crucial for long-term performance. If corrosion is detected on the plunger, it should be replaced immediately. Regular checks of the plunger’s sealing and tappet condition are also necessary. Understanding the working principle of a piston pump helps in recognizing the importance of these maintenance steps, ensuring reliable and efficient operation over time.
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