Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-11-01
2001-11-20
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S456000
Reexamination Certificate
active
06318341
ABSTRACT:
BACKGROUND INFORMATION
The present invention relates to a fuel injection system for direct injection of fuel into the combustion chamber(s) of an internal combustion engine.
The present invention is based on a fuel injection system. Unexamined Japanese Published Patent Application No. 08-312503 describes mounting holes for one fuel injector, in which each mounting hole may be provided on the cylinder head of an internal combustion engine, with one spray section of the fuel injector inserted into each hole. The fuel injector is held down by a hold-down device designed as a tightening bracket against the relatively high combustion pressure prevailing in the combustion chamber. A fuel distributor line connecting the fuel injectors to a fuel pump supplies fuel to the fuel inlet orifices provided on the fuel injectors. The fuel distributor line has one fuel outlet orifice for each fuel injector. To achieve the required seal, a sealing element in the form of an O-ring is provided for each.
However, one disadvantage of this known assembly method is that each fuel injector must be installed individually on the cylinder head, thus resulting in a very complicated assembly operation involving multiple steps. It is impossible to pretest the fuel injection system for leakage, for example. A fully automatic manufacturing process is made difficult due to the multiple operations.
Furthermore, it is also a disadvantage that the fuel distributor line and the hold-down device of the fuel injectors are mounted in the respective mounting holes in the cylinder head through separate elements. Therefore, the fuel injectors must first be preassembled in the mounting holes before the fuel distributor line can be positioned and attached to the cylinder head. Therefore, this known type of assembly has a relatively low degree of integration and the procedure is complicated.
German Published Patent Application No. 29 08 095 describes a fuel injector not provided for direct injection of fuel can be mounted on a fuel that distributor line by a retaining strap. Also described is an inlet section of the fuel injector that can be inserted into the fuel distributor line by a nipple connector. However, a hold-down force that can withstand the combustion pressure of the internal combustion engine cannot be transmitted over the retaining strap to the fuel injectors, so this type of assembly is unsuitable for fuel injectors for direct injection of fuel into the combustion chamber of an internal combustion engine.
Essentially, it is described in European Published Patent Application No. 0 491,582 that fuel injectors can be preassembled on a fuel distributor line before being inserted into the mounting holes. However, this known fuel injection system is also unsuitable for direct injection of fuel into the combustion chamber of an internal combustion engine, but instead it is suitable for indirect injection of fuel into the intake manifold of the internal combustion engine. The retaining elements are also unsuitable for transmitting an adequate hold-down force for withstanding the combustion pressure of the internal combustion engine, so this type of assembly is also unsuitable for a fuel injection system for direct injection of fuel into the combustion chamber of an internal combustion engine.
SUMMARY OF THE INVENTION
The fuel injection system according to the present invention however, has the advantage that the functions of securing the fuel distributor line and holding down the fuel injectors in the respective mounting holes of the cylinder head are integrated together into the corresponding mounting devices. After mounting the fuel distributor line by tightening the first tightening elements of the mounting devices, a hold-down force which can be predetermined by the second tightening elements can be transmitted to the fuel injectors over the hold-down devices connected to the mounting devices, so the fuel injectors are held down in the mounting holes against the combustion pressure of the internal combustion engine.
Another important advantage is that the fuel injectors can be preassembled on the fuel distributor line together with their hold-down devices, and the fuel injection system can be supplied as a complete system to the manufacturer of the internal combustion engine. The fuel injection system can be pretested for satisfactory functioning, in particular by leakage testing, at the fuel injection system manufacturing plant. Such pretesting ensures that only properly functioning fuel injection systems will be shipped to the internal combustion engine manufacturer, and thus the reliability of the fuel injection system as a whole is improved.
The preassembled fuel injection system can be installed rapidly on the internal combustion engine at the internal combustion engine manufacturing plant without requiring any (great assembly effort, e.g., by a fully automated manufacturing system. This is done by simply inserting the fuel injectors into the mounting holes provided on the cylinder head of the internal combustion engine and attaching the fuel distributor line to the cylinder head by tightening the first tightening elements of the mounting devices. Then a sufficient hold-down force is transmitted to the fuel injectors by tightening the second tightening elements of the mounting device, so that this force can withstand the combustion pressure of the internal combustion engine.
A supporting socket is preferably arranged between a mounting section of the fuel distributor line and the cylinder head, with the first tightening element preferably being designed as a threaded bolt which passes through the mounting section of the fuel distributor line and through the supporting socket and can be screwed into a respective threaded hole in the cylinder head. The hold-down device advantageously has a working section that acts on the respective fuel injector, a mounting section of the fuel distributor line assigned to the supporting socket and a guide section at least partially surrounding the first tightening element as well as a connecting section connecting the working section and the guide section. The second tightening element is advantageously designed as a threaded nut which can be screwed onto a screw head of the first tightening element and acts on the guide section of the hold-down device. This design achieves an integration of the mounting device with the hold-down device.
The hold-down device preferably has a collar that projects radially inward and can be inserted into a groove on the respective fuel injector. This not only permits a hold-down force to be exerted on the respective fuel injector in the direction of the combustion chamber but also allows a force to be exerted in the opposite direction. This is especially advantageous when dismantling the fuel injection system, because the fuel injectors can then be extracted from the mounting holes in the cylinder head with the hold-down device. In addition, when the fuel injection system is preassembled, the fuel injectors are locked on the fuel distributor line by the hold-down devices and the mounting devices and cannot become detached from the preassembled fuel injection system.
A tubular adapter is preferably arranged between each fuel outlet orifice of the fuel distributor line and the respective fuel inlet orifice of the fuel injector. This tubular adapter allows the position and angle to be adjusted within certain limits. Thus, the demands made of the dimensional accuracy of the mounting holes for the fuel injectors on the cylinder head and the dimensional accuracy of the fuel outlet orifices on the fuel distributor line may be less critical.
REFERENCES:
patent: 4205789 (1980-06-01), Raufeisen
patent: 4982983 (1991-01-01), Lenzi
patent: 5806494 (1998-09-01), Glassey
patent: 6073612 (2000-06-01), Ohkubo et al.
patent: 6148797 (2000-11-01), Gmelin
patent: 29 08 095 (1980-09-01), None
patent: 42 05 263 (1993-08-01), None
patent: 0 491 582 (1992-06-01), None
patent: 1 431 424 (1966-05-01), None
patent: 08-312503 (1996-11-01), None
Bretschneider Andreas
Fuerst Thomas
Gmelin Karl
Staiger Jochen
Kenyon & Kenyon
Moulis Thomas N.
Robert & Bosch GmbH
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