Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2001-06-28
2003-03-18
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C123S506000, C123S446000
Reexamination Certificate
active
06532943
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a system for injecting fuel into compression ignition internal combustion engines.
BACKGROUND OF THE INVENTION
Certain fuel injection systems for engines have been designed as unit injectors which incorporate hydraulically driven pressure intensifiers with a stepped plunger for injecting fuel into the engine's cylinder, wherein the fuel delivery and timing are controlled by an electronically controlled valve. In addition, the spray pattern is controlled by means of modulating the base oil pressure supplied to the unit injector and/or by means of modulating the nozzle opening pressure.
The present invention concerns hydraulically actuated electronically controlled unit injection (HEUI) systems which are well known in the art. The most relevant art includes U.S. Pat. No. 5,785,021, the contents of which are incorporated herein by reference thereto.
U.S. Pat. No. 5,785,021 discloses a fuel injection system which comprises a pressure intensifier which is associated with hydraulically controlled differential valves. These valves comprise a poppet valve opening into a working chamber of the pressure intensifier. A throttling slot is provided between the poppet valve chamber and the working chamber, with either at least a bypass channel between the poppet valve chamber and a control chamber of the valve, or a bore connecting the working chamber to the control chamber of the valve.
Furthermore, International Application No. PCT/AU98/00073 discloses a fuel injection system in which a pressure intensifier is associated with a hydraulically controlled differential valve, which in turn defines a poppet opening into a working chamber of the pressure intensifier. The pressure intensifier comprises a plunger with an external groove for connection of a locking chamber of a nozzle with a compression chamber of the plunger during an injection cut-off position of the plunger, and for connection of the locking chamber to a control channel during other positions of the plunger. The pressure in the control channel is controlled by a hydraulic control system, which, in a preferred embodiment, is common for a set of injectors of the engine. In this manner, the injection system can be used for varying the shape of an injection curve and for providing a varying fuel injection pressure.
A primary object of the present invention is to provide an improved fuel injection system. In particular, it is an object of the present invention to provide improvements which increase the range of electronic control of an injection curve shape of the unit injector, improve the stability of fuel delivery in consecutive cycles of injections and between the unit injectors of a multi-cylinder engine, simplify the unit injector's design, and improve the injection end quality.
SUMMARY OF THE INVENTION
These and other objects have now been realized by the invention of a fuel injector for use in an internal combustion engine comprising a fuel injector housing including an inlet port for the fuel, a spill port for release of the fuel, a working chamber, a piston disposed for reciprocal movement within the working chamber, a plunger attached to the piston, a nozzle for injecting the fuel into the internal combustion engine in response to the action of the plunger, a hydraulic valve movable between a closed position, an open position, and at least one intermediate position therebetween, the hydraulic valve including a first side and a second side, the first side of the hydraulic valve facing a control chamber and the second side of the hydraulic valve facing a poppet chamber, whereby the hydraulic valve moves between the control chamber and the poppet chamber, the hydraulic valve including a poppet defining the poppet chamber, the poppet including a first side and a second side, the first side of the poppet defining the poppet chamber and being in communication with the inlet port and the second side of the poppet being in communication with the working chamber, the poppet disposed with respect to the working chamber so as to provide a throttling slot between the working chamber and the poppet chamber, biasing means for urging the hydraulic valve towards the closed position in which the poppet chamber is not in communication with the inlet port, a control valve disposed between the control chamber and the spill port, and a primary bypass channel for connecting the poppet chamber to the control chamber, whereby during at least a portion of the initial movement of the hydraulic valve from the closed position to the open position the primary bypass channel is closed and when the hydraulic valve reaches the at least one intermediate position the primary bypass channel is open. In accordance with a preferred embodiment, the hydraulic valve includes a groove proximate to the first side of the hydraulic valve, whereby when the hydraulic valve is closed the groove opens the primary bypass channel, when the hydraulic valve is in the at least one intermediate position the first side of the hydraulic valve opens the primary bypass channel, and when the hydraulic valve is in a second intermediate position between the closed position and the at least one intermediate position the primary bypass channel is closed.
In accordance with one embodiment of the fuel injector of the present invention, the fuel injector includes a secondary bypass channel connecting the poppet chamber to the control chamber. In a preferred embodiment the fuel injector includes a secondary valve disposed is the secondary bypass channel for altering the flow area of the secondary bypass channel. Preferably, the fuel injector includes an engine management system for controlling the secondary valve.
In accordance with another embodiment of the fuel injector of the present invention, the fuel injector includes a tertiary bypass channel connecting the poppet chamber to the control chamber.
In accordance with another embodiment of the fuel injector of the present invention, the secondary valve cannot completely close the secondary bypass channel.
In accordance with another embodiment of the fuel injector of the present invention, the fuel injector includes a hydraulic control system for controlling the secondary valve. Preferably, the fuel injector includes an engine management system for controlling the hydraulic control system.
In accordance with another embodiment of the fuel injector of the present invention, the fuel injector includes a solenoid for actuating the secondary valve.
In accordance with the present invention, these objects have also been realized by the invention of a fuel injector for use in an internal combustion engine comprising a fuel injector housing including an inlet port for the fuel, a spill port for release of the fuel, a working chamber, a piston disposed for reciprocal movement within the working chamber, a compression chamber, a plunger attached to the piston and defining at least a portion of the compression chamber, a nozzle for injecting the fuel into the internal combustion engine in response to actuation by the plunger, a needle movable between a first position closing the nozzle and a second position opening the nozzle, a locking chamber, first biasing means disposed within the locking chamber for urging the needle into the first position, an outlet chamber connecting the nozzle to the compression chamber, a non-return valve for permitting the fuel to enter the compression chamber from the inlet port, a cut-off channel connecting the locking chamber to the compression chamber, a control channel for connecting the cut-off channel to the spill port, a secondary control valve for controlling the flow from the control channel to the spill port, a link channel connecting the control channel to either the inlet port or to a hydraulic control system of the internal combustion engine, the link channel and the secondary control valve being disposed such that when the secondary control valve is open, the pressure in the control channel is less than the pressure between the link chann
Argenbright Tony M.
Huynh Hai
Lerner David Littenberg Krumholz & Mentlik LLP
Volvo Lastvagnar AB
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