What is the working principle of a diesel fuel injection pump?
1 Answers
The working principle of a diesel fuel injection pump is as follows: 1. Fuel suction process: The plunger is driven by the cam of the camshaft. When the raised part of the cam moves away from the plunger, the plunger moves downward under the action of the plunger spring, increasing the volume of the oil chamber and reducing the pressure. When the radial fuel inlet hole on the plunger sleeve is exposed, the fuel in the low-pressure oil chamber flows into the pump chamber through the inlet hole. 2. Fuel pumping process: When the raised part of the cam lifts the plunger, the volume inside the pump chamber decreases, and the pressure increases, causing the fuel to flow back to the low-pressure oil chamber through the radial oil hole on the plunger sleeve. When the plunger moves upward and completely blocks the radial oil hole on the plunger sleeve, the pressure in the pump chamber rapidly increases. When the pressure overcomes the preload force of the outlet valve spring, the outlet valve moves upward. When the pressure relief ring on the outlet valve leaves the valve seat, high-pressure diesel is pumped into the high-pressure fuel pipe and then injected into the cylinder through the fuel injector. 3. Fuel return process: As the plunger continues to move upward, when the inclined groove on the plunger connects with the radial oil hole on the plunger sleeve, the fuel in the pump chamber flows back to the low-pressure oil chamber through the axial oil passage on the plunger, the inclined oil passage, and the oil hole on the plunger sleeve, stopping the fuel pumping process.
