PURPOSE: To stably obtain a high injection pressure over a wide operational range by controlling a pressure of fuel and pressure balance in a back pressure chamber of a needle further providing a pressure accumulator chamber holding a pressure of the predetermined or more and connecting a fuel flow line to and disconnecting it from the back pressure chamber by a solenoid valve.
CONSTITUTION: In a fuel injection device 1, when a plunger 22 is pressed down by a cam 21, high pressure fuel in a plunger chamber 20 is fed into an accumulator chamber 25. Further the fuel is allowed to flow into a valve chamber 40 and a back pressure chamber 37 from a solenoid valve 10. The fuel in the accumulator chamber is placed in a pressure chamber 32 and injected by opening a needle 35, but the accumulator chamber 25 has the predetermined volume, and the pressure chamber 32 maintains a predetermined injection rate at a high pressure by a pressure holding means (check mechanism). When the solenoid valve 10 is turned off by the timing set in an electronic control unit, fuel is allowed to flow out through a check valve 26 from the accumulator chamber, and a pressure of the valve chamber 40 and the back pressure chamber 37 is increased, closing an injection nozzle. Accordingly, a stable high pressure of injection and its rate are obtained.
| JPS6019945 | FUEL INJECTOR |
| WO/1996/009471 | UNIT INJECTOR OPTIMIZED FOR REDUCED EXHAUST EMISSIONS |
OKAJIMA MASAHIRO
OSHIMA KAZUHIKO
| JPS61167160A | 1986-07-28 |