Diesel Injector Fuel Injector 0445120343 compatible with Bosch injector WEICHAI WD615 WD10 – EU 4

The working process of the injector

In the working process, the injection process of the pump injector can be divided into two stages: pre-injection and main injection, and can also be divided into pre-injection, end of pre-injection, main injection, end of main injection and high-pressure oil chamber There are 5 processes of oil intake. The fuel injection time and fuel injection quantity are jointly controlled by the auxiliary plunger, the fuel injection needle valve, the fuel injection needle valve return spring, the fuel injection needle valve damper and the electromagnetic control valve.
(1) Pre-injection
When the straight section of the cam touches the rocker arm, the electronic control system supplies power to the electromagnetic control valve, so that the needle valve of the electromagnetic control valve moves to the left, cutting off the passage between the high pressure oil chamber and the low pressure oil passage, at the same time, the pump oil column Under the action of the rocker arm, the plug moves downward against the elastic force of the return spring of the pump oil plunger, so that the oil pressure in the high-pressure oil chamber rises rapidly. When the oil pressure rises to 18MPa, the upward thrust generated by the fuel on the cone surface in the middle of the injection needle valve is greater than the pre-tightening force of the return spring of the injection needle valve, and the injection needle valve will be pushed up to start pre-injection.
(2) End of pre-injection
After the pre-injection starts, the fuel injection needle continues to move upwards. When the cam turns over 1/3 of the fuel injection stroke, the lower end of the fuel injection needle damper enters the fuel injection needle damper hole, and the top of the fuel injection needle The fuel can only flow to the return spring cavity of the injection needle valve through a small gap. In this way, a so-called "hydraulic gasket" is formed on the top of the fuel injection needle valve, which prevents the fuel injection needle valve from continuing to move upwards, so that the pre-injection amount of fuel is limited. As the pump plunger continues to move downward, the oil pressure in the high-pressure oil chamber continues to rise. When the oil pressure reaches the specified value, after the auxiliary plunger moves downward under the action of high-pressure fuel, the volume of the high-pressure oil chamber suddenly increases. increases, the fuel pressure drops instantly. At this time, the upward thrust on the cone surface in the middle of the fuel injection needle decreases accordingly, and the fuel injection needle resets under the action of the return spring of the fuel injection needle (the elastic force increases due to the compression of the auxiliary plunger), and the pre-injection Oil is over.