Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2001-05-21
2003-02-04
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S446000, C123S467000
Reexamination Certificate
active
06513497
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a fuel injection system for an internal combustion engine, and more particularly to such a system including a pressure booster.
2. Brief Description of the Prior Art
For better comprehension of the specification and claims, several terms will now be explained: The fuel injection system of the invention can be embodied as either stroke-controlled or pressure-controlled. As used herein, the term, “stroke-controlled fuel injection system” is understood to mean that the opening and closing of the injection opening is effected with the aid of a displaceable valve member on the basis of the hydraulic cooperation of the fuel pressures in a nozzle chamber and in a control chamber. A pressure drop inside the control chamber causes a stroke of the valve member. Alternatively, the deflection of the valve member can be done by a final control element (actuator). In a “pressure-controlled fuel injection system” according to the invention, the valve member is moved counter to the action of a closing force (spring) by the fuel pressure prevailing in the nozzle chamber of an injector, so that the injection opening is uncovered for an injection of the fuel out of the nozzle chamber into the cylinder. The pressure at which fuel emerges from the nozzle chamber into a cylinder is called the “injection pressure”, while the term “system pressure” is understood to mean the pressure at which the fuel is available or kept on hand inside the fuel injection system. “Fuel metering” means delivering fuel to the nozzle chamber by means of a metering valve. In “combined fuel” metering, a common valve is used to measure various injection pressures. In the “unit fuel injector” (PDE), the injection pump and the injector form a unit. One such unit per cylinder is built into the cylinder head and driven by the engine camshaft, either directly via a tappet or indirectly via tilting levers. The “pump-line-nozzle system” (PLD) operates by the same method. A high-pressure line in that case leads to the nozzle chamber or nozzle holder.
A unit fuel injector is known from German Patent Disclosure DE 195 175 78 A1. In this fuel injection system, the system pressure is generated via a pressure-actuatable piston, whose motion is controlled by a cam drive. A variable fuel injection of different quantities for the pre-injection, main injection and post-injection can be accomplished only to a limited extent with such a fuel injection system.
SUMMARY OF THE INVENTION
The fuel injection system of the present invention makes it possible to achieve the fuel injection with the aid of a unit fuel injector over a wide rpm range with high precision. This makes it possible to remove pollutant exchange and enables more flexible pre-injection and post-injection by means of a unit fuel injector or a pump-line-nozzle system. The teaching according to the invention combines the advantages of a pressure-boosted (pressure-amplified) injector with a non-pressure-boosted unit fuel injector. If a piezoelectric actuator is used for fuel metering, improved metering of the injected fuel quantity can be attained. This creates a good minimum quantity capability in the pre-injection and if needed in the post-injection, because such an injection is done under stroke control with a lesser injection pressure. The pre-injection and post-injection are done flexibly and replicably. Good hydraulic efficiency of the pressure boosting is achieved if the pressure booster is disposed inside the injector. The course of injection can be varied in a targeted way.
REFERENCES:
patent: 4142497 (1979-03-01), Long
patent: 4674448 (1987-06-01), Steiger
patent: 5355856 (1994-10-01), Paul et al.
patent: 5622152 (1997-04-01), Ishida
patent: 6076504 (2000-06-01), Stavnheim et al.
Kropp Martin
Magel Hans-Christoph
Mahr Bernd
Otterbach Wolfgang
Argenbright Tony M.
Greigg Ronald E.
Robert & Bosch GmbH
LandOfFree
Fuel injection system for internal combustion engines does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fuel injection system for internal combustion engines, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel injection system for internal combustion engines will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3139487