Fuel injection system
AssigneeNippondenso Co., Ltd.
InventorsMasahiko Miyaki, Takashi Iwanaga, Hideya Fujisawa
Life of this patent
Estimating the term…
Abstract
A fuel injection system for a diesel engine has fuel pump driven by the engine for producing highly pressurized fuel, a common rail for storing the pressurized fuel therein and injection nozzles for injecting the pressurized fuel stored in the common rail into the engine. The injection nozzles are electrically controlled in accordance with engine operating conditions (N, .alpha.) by the use of injection control solenoid valves provided between the injection nozzles and the common rail. The fuel pump is electrically controlled in accordance with the engine operating conditions by the use of a spill control solenoid valve which spills the pressurized fuel to a low pressure fuel channel so that loss of engine torque required by the pump is reduced.
Claims14
A fuel injection system for a diesel engine comprising:
- condition detection means for detecting operating conditions of said diesel engine including a rotational position thereof;
- low pressure fuel supply means for supplying fuel at a low pressure at an output port thereof;
- high pressure fuel pump means, having a pump chamber communicating with said output port of said low pressure fuel supply means, and plunger means reciprocable within said pump chamber for introducing fuel from said output port of said low pressure fuel supply means into said pump chamber during a movement in a predetermined direction of said plunger means and for pressurizing the introduced fuel during a movement of said plunger means in the opposite direction so that pressurized fuel is delivered from said high pressure fuel pump means at an output port thereof;
- common rail fuel storage means, connected to said output port of said high pressure fuel pump means, for storing pressurized fuel delivered from said high pressure pump therein at a substantially continuous pressure;
- fuel injection means, connected to said common rail fuel storage means and including en electrically-controlled valve, for injecting the pressurized fuel stored in said common rail fuel storage means into said diesel engine, when activated by an injection control signal;
- spill passage means for communicating said pump chamber to said low pressure fuel supply means;
- electrically-controlled spill valve means, which is normally open and positioned in said spill passage means, for closing said spill passage means in response to a spill control signal applied thereto;
- and
- electric control means for producing said injection control signal and said spill control signal, a time period of said injection control signal being determined in accordance with the detected operating conditions of said diesel engine, and said spill control signal being started at a fixed predetermined rotational position of said diesel engine, and ending at a variable time, so that said spill valve means closes said spill passage before said high pressure pump means starts said fuel pressurizing during the movement of said plunger means in said opposite direction and opens the spill passage means in the course of the movement of said plunger means in said opposite direction thereby to maintain the fuel pressure in said fuel storage means.
A fuel injection system for electrically controlling an injection of fuel into cylinders of a combustion engine from injection nozzles mounted on the respective cylinders, said fuel injection system comprising:
- fuel storage means, connected to the injection nozzles, for storing fuel at a substantially continuous pressure therein;
- high-pressure fuel supply pump means, driven by said combustion engine and having pump chambers into which fuel to be pressurized is introduced, for pressurizing the fuel inside the pump chambers and supplying said pressurized fuel to said fuel storage means so that high-pressure fuel is kept therein;
- a plurality of low pressure fuel passages;
- a plurality of spill passages that connect the pump chambers with said low-pressure fuel passages;
- a plurality of spill solenoid valves, at least one for each said spill passage, and which, when opened, permit the fuel in the pump chambers to spill into the low-pressure fuel passages, thereby stopping further pressurization of fuel in said pump chambers;
- and
- control means for controlling the spillage of the pressurized fuel from the pump chambers by closing and opening said spill solenoid valves, one of the timings of closing and opening of the spill solenoid valves being fixed at a predetermined rotational position of said diesel engine at which said high-pressure pump is incapable of fuel pressurization, and the other timing being varied in accordance with a fuel quantity injected from said injection nozzles.
Dependencies are inferred from the claim text.