Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-10-26
2001-02-13
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C277S313000
Reexamination Certificate
active
06186123
ABSTRACT:
FIELD OF THE INVENTION
The present invention releates to a fuel injection valve having a nozzle body that can be inserted into a receiving bore of a cylinder head of an internal combustion engine for direct injection of fuel into the combustion chamber of the internal combustion engine.
BACKGROUND INFORMATION
Such fuel injection valves are described in German Patent No. 30 00 061 and British Patent No. 759 524. German Patent No. 30 00 061 describes the use of a heat shield sleeve on the nozzle body of the fuel injection valve. A flange of the heat shield sleeve is inserted into an inside groove in the fuel injection valve and sealed by a sealing ring with respect to the receiving bore of the cylinder head. On the spray side, the heat shield sleeve has a ring-shaped collar that is bent inward, with an elastic heat shield ring supported on the collar. The heat shield ring is arranged between the spray end of the nozzle body of the fuel injection valve and the ring-shaped collar of the heat shield sleeve that is bent inward.
With the fuel injection nozzle described in British Patent No. 759 524, a flexible heat shield element inserted between an end face of the nozzle body and a collar of a clamping nut is designed as a disk-shaped heat shield ring made of a thermal insulation material. To protect the inside of the heat shield ring, which is not covered by the collar or the nozzle body, from attack by combustion gases, the inside is bordered by a U-shaped ring of thin sheet metal.
A disadvantage of these conventional fuel injection valves is that the thermal coupling between the nozzle body and the cylinder head is not entirely satisfactory because the radial pressure is limited due to the maximum allowed assembly forces. Therefore, there is the risk of overheating the nozzle body and coking during operation of the internal combustion engine.
SUMMARY OF THE INVENTION
The fuel injection valve according to the present invention claim has the advantage that a good thermal connection of the fuel injection valve to the cylinder head is possible together with easy assembly of the fuel injection valve at the same time. The fuel injection valve can be inserted easily into the receiving bore due to the metal ring, which is arranged on the nozzle body and becomes deformed when heated, producing radial pressure of the fuel injection valve in the receiving bore only when heated after the fuel injection valve has been inserted into the receiving bore of the cylinder head. The metal ring nevertheless guarantees adequate radial pressure between the inserted fuel injection valve and the cylinder head, so that good thermal coupling is guaranteed. The metal ring deforms only when it reaches the required temperature during operation of the internal combustion engine.
The outside diameter of the metal ring before heating is advantageously smaller than the diameter of the receiving bore. This measure permits easy assembly of the fuel injection valve in the receiving bore. The metal ring is typically placed on and/or attached to the nozzle body before the fuel injection valve is inserted into the receiving bore. Room temperature usually prevails here. During operation of the internal combustion engine, the fuel injection valve reaches temperatures of up to approx. 200° C. However, coking may occur at this temperature. Due to the deformation of the metal ring when heating the fuel injection valve after startup of the internal combustion engine, the metal ring becomes deformed, producing a radial pressure of the fuel injection valve in the receiving bore so there is a good thermal connection to the cylinder head. This dissipates heat from the fuel injection valve over the cylinder head, so that the operating temperature of the fuel injection valve can be lowered to less than 150° C., thus preventing coking.
In an advantageous embodiment of the present invention, the metal ring is arranged in a groove of the nozzle body. This in particular guarantees even easier insertion of the fuel injection valve into the receiving bore and a secure axial mounting of the metal ring on the fuel injection valve.
In another advantageous embodiment of the present invention, the metal ring is attached by a fastening means to an outside wall of the nozzle body. For example, the fastening means may be formed by a weld, a clamp, rivets, screws, etc.
In one embodiment, the metal ring is preferably made of a bimetal. For example, the material of the metal ring here is steel on its inside facing the nozzle body and aluminum on its outside facing away from the nozzle body.
In an alternative embodiment, the metal ring is made of a memory metal. In this case, the metal ring has a diameter smaller than the diameter of the receiving bore of the fuel injection valve at room temperature, while it has a correspondingly larger diameter in the operating temperature range of the fuel injection valve, thus guaranteeing the required radial pressure.
In another alternative embodiment, the metal ring is made of a metal having a thermal expansion coefficient different from the thermal expansion coefficient of the nozzle body. The metal ring expands when heated to the operating temperature, but if it is arranged in the groove in the nozzle body, it can yield only in the radial direction toward the receiving bore, thus creating the radial pressure. The same thing is true for the case when the metal ring is attached to the nozzle body at or near its outside edges, because the intermediate area of the metal ring between the fastenings can yield only in the radial direction toward the receiving bore when heated to the operating temperature.
In all embodiments, the metal ring may be coated at least partially with a soft metal to permit a better adaptation to the fuel injection valve and the receiving bore of the cylinder head.
REFERENCES:
patent: 3038456 (1962-06-01), Dreisin
patent: 3244377 (1966-04-01), Roosa
patent: 3777495 (1973-12-01), Kuze
patent: 4067585 (1978-01-01), Rode
patent: 4528959 (1985-07-01), Hauser, Jr.
patent: 4602795 (1986-07-01), Lillibridge
patent: 5247918 (1993-09-01), Wakeman
patent: 30 00 061 (1981-07-01), None
patent: 95 24576 (1995-09-01), None
patent: 1 219 366 (1960-05-01), None
patent: 759 524 (1956-10-01), None
patent: 09 126089 (1997-05-01), None
Maier Martin
Preussner Christian
Kenyon & Kenyon
Moulis Thomas N.
Robert & Bosch GmbH
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