ES369593A1 - Fuel injection valves for internal combustion engines - Google Patents

Abstract

An I.C. engine fuel injection valve comprises a valve needle 103, Fig. 3, guided at 34c in a housing 10a and co-operating with a valve seat 32a in the housing, the end of the valve needle remote from the seat being a greater diameter than the seat a forward fuel chamber 115 connected via ducts 114, 15 to a fuel line in which a constant pressure of 500 to 1000 atmospheres or more is maintained by a fuel pump and a spool valve 100 having a control edge 111 co-operating with a control edge 112 to allow fuel to enter a rear fuel chamber 116 from the duct 15. When a solenoid (not shown) is energized to cause a core 23 to attract the disc-like end 102 of the spool valve 100 and thereby lift the spool valve, the control edges 111, 112 block the flow of fuel from the duct 15 to the rear fuel chamber 116, and at the same time a conical end 106 of the spool valve is lifted from a seat 105 to allow fuel to flow from the rear fuel chamber via ducts 107, 108, 104 to the engine cylinder. The resultant fall in pressure above the upper end of the valve needle 103 allows the fuel pressure in the forward fuel chamber 115 to raise the valve needle from the seat 32a to permit fuel to flow via the ducts 15, 114 and the forward fuel chamber into the engine cylinder. The rapid movement of the valve needle 103 is cushioned by a stop ring 117. In another embodiment, Figs. 1 and 2 (not shown), the spool valve (26) slides within a bore (40) in the valve needle (35), the flow of fuel into the rear fuel chamber (54) being controlled by a control edge (48) on the spool valve co-operating with a control edge (46) formed within the valve needle. The stop ring (52) for cushioning the rapid upward movement of the valve needle (35) may be replaced by a stick of belleville washers (120), Fig. 4 (not shown).