TCD2013L064V Construction Machinery Engine For Excavator

During the priming process, when the solenoid valve is de-energized and the plunger moves downward, the pressure within the injection system falls below the injection pressure of the low-pressure fuel line. Fuel from the low-pressure system enters the high-pressure injection system through the fuel inlet on the plunger sleeve.
During the bypass process, when the plunger ascends and the solenoid valve remains de-energized, the fuel in the plunger chamber is compressed. The fuel pressure, determined by the opening pressure of the return oil relief valve and significantly lower than the opening pressure of the injector, causes the fuel to flow back to the tank through the return oil passage.
During the injection process, when the plunger ascends, the ECU energizes the solenoid valve, closing the return oil passage and forming a closed volume within the plunger chamber. As the plunger ascends, fuel pressure rapidly increases. When the pressure exceeds the opening pressure of the injector, the injector opens and fuel is sprayed into the combustion chamber.
During the unloading process, when the control injection pulse signal ceases, the solenoid valve de-energizes the return oil passage, reopening the fuel return passage. Fuel overflows from this passage, rapidly decreasing the pressure in the plunger chamber and the nozzle, closing the nozzle and concluding the injection process.