JPH0246067U - - Google Patents

Description

[Brief explanation of drawings]

Fig. 1 is a plan sectional view of the unit injector taken along the - line in Fig. 5, Fig. 2 is a plan view of the unit injector in Fig. 1, and Fig. 3 is a side sectional view taken along the - line in Fig. 4. , Fig. 4 is a side sectional view taken along the - line in Fig. 5, Fig. 5 is a side sectional view taken along the - line in Fig. 4, and Fig. 6 is an enlarged side view of a part of Fig. 5. 7 is a side sectional view taken along the line - in FIGS. 1 and 5; FIG. 8 is a side sectional view showing another embodiment of the unit injector;
FIG. 9 is a side sectional view taken along line ``-'' in FIG. 8, and FIG. 10 is a plan sectional view taken along line ``-'' in FIG. 3...Nozzle port, 7...Needle, 11...Plunger hole, 12...Plunger, 15...Fuel pressurization chamber, 20...Fuel supply port, 30...Sliding hole, 31...Overflow valve , 35... Valve seat, 38... First annular fitting part, 39... Second annular fitting part, 40...
...Annular valve part, 41... Pressurized fuel introduction chamber, 42...
Fuel overflow chamber, 44... Overflow valve back pressure chamber, 46, 47
, 51, 52, 100, 101, 102... fuel passage, 50... annular groove, 60... rod, 66...
...Pressure control chamber, 77...Piezoelectric element, 78...
...variable volume chamber.

Claims (1)

[Scope of utility model registration request] a plunger driven by an engine; a fuel pressurization chamber filled with fuel and pressurized by the plunger; a needle that opens the valve; an overflow valve slidably inserted into the sliding hole; and the overflow valve is moved in the axial direction of the sliding hole to prevent fuel from overflowing from the fuel pressurizing chamber. An annular valve is provided on the inner wall surface of the sliding hole in the fuel injection device, which injects fuel when the overflow valve stops overflowing fuel from the fuel pressurizing chamber. an annular fitting portion is formed at one end of the overflow valve in sealing contact with the inner circumferential surface of the sliding hole, and an annular fitting portion is formed on the outer circumferential surface of the overflow valve at a distance from the annular fitting portion. An annular valve part is formed that is spaced apart and can be seated on the valve seat, and an annular pressurized fuel introduction chamber is formed around the outer peripheral surface of the overflow valve between the annular valve part and the annular fitting part. A pressurized fuel introduction chamber is connected to the fuel pressurization chamber, and a fuel overflow chamber is formed on a side opposite to the pressurized fuel introduction chamber with respect to the valve seat, and a fuel overflow chamber is formed on a side opposite to the pressurized fuel introduction chamber with respect to the annular fitting part. An overflow valve back pressure chamber defined by an annular fitting part is formed in the sliding hole of the overflow valve, and a spring is inserted into the overflow valve back pressure chamber to bias the overflow valve toward the fuel overflow chamber. , the overflow valve backpressure chamber and the fuel overflow chamber are in communication with each other via a fuel passage formed in the overflow valve and a separate fuel passage formed in a housing around the overflow valve; A fuel injection device that causes pressurized fuel in a fuel pressurizing chamber to overflow into a fuel overflow chamber via the pressurized fuel introduction chamber when the annular valve portion of the annular valve is separated from the valve seat.