Fuel injection nozzle

Details Fuel injection nozzle Fuel injection nozzle

1999-04-05

2002-04-30

Scherbel, David O. (Department: 3752)

Fluid sprinkling, spraying, and diffusing

Fluid pressure responsive discharge modifier* or flow...

Fuel injector or burner

C239S533200, C239S538000, C239S533140

Reexamination Certificate

active

06378792

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a fuel injection nozzle for use in a fuel injection valve in an internal combustion engine, etc.
DESCRIPTION OF THE RELATED ART
A known integral type fuel injection nozzle described in Japanese Laid-Open Patent Publications Nos. 9-66381 and 9-126095 is shown in partial front sectional view in FIG.
1
. The fuel injection nozzle
10
is molded from steel material and has a valve opening
13
in which a fuel injection valve
12
is slidably provided, a valve seat or seat portion
14
, and a rounded or “sack” portion
16
, which has a generally semi-spherical inner circumferential surface
16
a
. An injection opening
17
is formed in the sack portion
16
and fuel is injected into the engine through this injection opening
17
. The injection opening
17
is formed in the nozzle
10
by laser machining from the downstream side or the upstream side in the fuel injection direction.
However, if the injection opening
17
is formed from the downstream side using a laser machining process, dross accumulates in the fuel injection nozzle
10
, and the measuring accuracy of injection fuel may be diminished. Dross is metal burrs that are formed when the metal melts during the laser machining process and adheres to the nozzle
10
.
On the other hand, if the injection opening
17
is formed from the upstream side using a laser machining process, an optical fiber must be connected to a laser beam emitting apparatus and the laser machining process is indirectly performed by inserting the optical fiber into the valve opening
13
. In this case, because the laser beam emitted by the optical fiber scatters, a special beam condensing device must be utilized to condense the laser beam. Furthermore, because the valve opening
13
is generally small (approximately 6 mm) in diameter, the machining accuracy of the opening profile is limited.
An electric spark machining process also can form an injection port. However, because the time required to fabricate the injection port using an electric spark machining port is substantially longer than the time required for laser machining, manufacturing efficiency is reduced.
A known two-piece type fuel injection nozzle described in Japanese Laid-Open Patent Publication No. 6-249105 is shown by partial sectional view in FIG.
2
. This fuel injection nozzle
20
comprises a valve seat
21
made from steel material and a nozzle tip
25
molded from ceramic. A valve opening
23
, in which a fuel injection valve
22
is slidably secured, and a seat portion
24
, on which the valve
22
contacts, are formed on the valve seat
21
. The nozzle tip
25
includes a sack portion
26
having a generally semi-spherical inner circumferential surface
26
a
and an injection opening
27
. The valve seat
21
and nozzle tip
25
are joined by a brazing material
29
using a brazing process. However, because brazing these two parts is difficult, manufacturing costs are relatively high.
SUMMARY OF THE INVENTION
It is, accordingly, an object of the invention to provide improved fuel injection nozzles that can be manufactured efficiently.
In one aspect of the present teachings, improved manufacturing processes are described that facilitate the joining of the valve seat and the nozzle tip of a fuel injection nozzle.
In another aspect of the present teachings, improved methods for forming an injection opening in the nozzle tip are described.
In a further aspect of the present teachings, improved methods for manufacturing a fuel injection nozzle are described in which an optionally shaped injection opening having excellent measuring accuracy can be easily formed on the nozzle tip in a short time.
Other objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.


REFERENCES:
patent: 3838821 (1974-10-01), Berlyn
patent: 4857696 (1989-08-01), Taeusch et al.
patent: 354125148 (1979-09-01), None
patent: 404350362 (1992-12-01), None
patent: 6249105 (1994-09-01), None
patent: 9066381 (1997-03-01), None
patent: 409079114 (1997-03-01), None
patent: 9126095 (1997-05-01), None

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