Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-05-26
2001-03-06
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S041310
Reexamination Certificate
active
06196195
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermal insulating sleeve for a fuel injection valve, which can be inserted in a mounting hole of a cylinder head of an internal combustion engine, for the direct injection of fuel into the combustion chamber of the internal combustion engine, in particular for a gasoline direct injection valve or diesel direct injection valve.
BACKGROUND INFORMATION
The provision of a thermal insulating sleeve at the nozzle body of a fuel injection valve is already known from German Patent No. 30 00 061 C2. A flange of the thermal insulating sleeve is inserted in an interior groove of the fuel injection valve and is sealed against the mounting hole of the cylinder head by a sealing ring. At the injection end, the thermal insulating sleeve has a ring-shaped collar bent toward the interior on which an elastic thermal insulating ring is supported. The thermal insulating ring is arranged between the injection end of the nozzle body of the fuel injection valve and the ring-shaped inwardly bent collar of the thermal insulating sleeve.
In a fuel injection nozzle known from British Patent No. 759 524, a pliable thermal insulating element, inserted as a disk-shaped thermal insulating ring between a face of the nozzle body and a collar of a tension nut, is formed from a thermal insulating material. To protect the inner side of the thermal insulating ring not covered by the collar or by the nozzle body from the corrosion by the combustion gases, this inner side is edged with a ring with a U-shaped cross section formed from a thin metal sheet.
A drawback of the thermal insulating sleeve according to the definition of the species is that it requires a relatively great assembly expenditure since the thermal insulating sleeve must be pre-assembled on the fuel injection valve. In addition, an additional sealing ring is necessary to seal the mounting hole of the cylinder head from combustion gases, resulting in an increase in the manufacturing and assembly effort and not least in costs. Dissipation of the heat, which develops in the nozzle body as a result of the combustion of the internal combustion engine, across the thermal insulating sleeve to the cylinder head is possible in the known configuration of the thermal insulating sleeve only to a limited extent.
SUMMARY OF THE INVENTION
In contrast, the thermal insulating sleeve according to the present invention has the advantage that assembly is made significantly easier. As a result of a folded-back section, the thermal insulating sleeve according to the present invention is configured to be radially elastic in this area. The thermal insulating sleeve therefore fits elastically in the area of the folded-back section both on the nozzle body of the fuel injection valve and on the mounting hole of the cylinder head. Through a conical section of the thermal insulating sleeve which fits tightly on a tapered section of the nozzle body, an axial transfer of force from the nozzle body of the fuel injection valve to the heat insulating sleeve is made possible. As a result of the conical configuration, self-centering is ensured. In addition, the conical configuration causes a degree of flaring of the radially elastic, folded-back section during assembly so that the axial assembly force is reduced.
The folded-back section, because of its close fit both on the nozzle body and on the mounting hole, ensures a sufficient seal for the fuel injection valve of the mounting hole of the cylinder head with respect to the combustion gases which are created in the combustion chamber of the internal combustion engine. An additional sealing ring is not necessary for the seal. As result of the elastic fit of the folded-back section both on the nozzle body of the fuel injection valve and on the mounting hole of the cylinder head, a good thermal coupling between the nozzle body of the fuel injection valve and the cylinder head is achieved through which overheating of the nozzle body is counteracted.
If a gap is formed between an inner layer and an outer layer of the folded-back section, a particularly high radial elasticity of the folded-back section results. The folded-back section can be bent in a U-shape in cross section. If the folded-back section follows directly after the conical section of the sleeve body, a particularly effective flaring of the folded-back section arises upon assembly of the fuel injection valve. If the sleeve body has a hollow cylindrical section, the internal diameter of which is larger than the external diameter of the section of the nozzle body which in the assembled state is inserted into the hollow cylindrical section, sufficient play between the nozzle body of the fuel injection valve and the mounting hole in the cylinder head will be present in this area.
A collar formed at the end opposite the injection end provides a stop for the thermal insulating sleeve at a step of the mounting hole of the cylinder head which is formed as a stepped hole, thereby fixing the final assembly position of the fuel injection valve in the thermal insulating sleeve. The sleeve body and the collar can advantageously be configured as a one-piece, deep-drawn sheet metal part, which can be manufactured particularly inexpensively. The folded-back section can likewise be inexpensively manufactured through flanging or bending.
REFERENCES:
patent: 2080189 (1937-05-01), Schwaiger
patent: 2777431 (1957-01-01), Meurer
patent: 3334617 (1967-08-01), Palkowsky
patent: 3945353 (1976-03-01), Dreisen
patent: 4201172 (1980-05-01), Jaggle
patent: 4625682 (1986-12-01), Dietrich
patent: 24 51 548 (1976-05-01), None
patent: 30 00 061 (1981-06-01), None
patent: 195 46 134 (1997-01-01), None
patent: 0294586 (1988-12-01), None
patent: 759 524 (1956-10-01), None
patent: 404086368 (1992-03-01), None
Norgauer Rainer
Pilgram Guido
Preussner Christian
Trutschel Ralf
Kenyon & Kenyon
Miller Carl S.
Robert & Bosch GmbH
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