Fuel injection valve

Details Fuel injection valve Fuel injection valve

1999-02-03

2001-05-01

Scherbel, David A. (Department: 3752)

Fluid sprinkling, spraying, and diffusing

Including valve means in flow line

Reciprocating

C239S585100, C239S533900, C239S533120

Reexamination Certificate

active

06224002

ABSTRACT:

BACKGROUND INFORMATION
German Patent Application No. 25 08 390 describes a fuel injection valve having an axially movable valve needle designed as a thin rigid rod or as a non-rigid wire. The downstream end of the rod is connected by friction to a closing head, which works together with a valve seat. On its opposite end, the rod runs through an armature and is connected to a tension spring upstream from the armature. The tension spring is responsible for the closing head being drawn to the valve seat via the rod when the magnet coil is not energized, so that the valve is in the closed position. If the magnet coil is energized, it attracts the armature, and the tension spring is extended. As a result, the rod moves axially so that the closing head rises from the valve seat. The tensile forces of the tension spring cause the valve to reclose when the magnet coil is not energized.
German Patent Application Nos. 34 27 526 and 35 35 438 describe electromagnetically actuated fuel injection valves having a flat armature in their magnetic circuit, German Patent Application No. 34 27 526 also describes a light and elongated valve needle.
SUMMARY OF THE INVENTION
The fuel injection valve according to the present invention has the advantage that it can be manufactured with simple and inexpensive components. The valve needle is designed as a thin wire, connected to a sealing element, and the sealing element is in turn coupled to a valve seat. It is advantageous that the valve needle and the sealing element may be designed so that the wire transfers pressure forces to the sealing element and the valve seat in the closed valve position, i.e., when the sealing element is in contact with the valve seat.
It is advantageous to design the wire used as a valve needle in one piece as an elongated downstream extension of a helical restoring spring, the elastic force of which brings the sealing element into the closed valve position through the valve needle. In order to increase the flexural strength of the thin wire, the valve needle is advantageously provided with a support element, which can be manufactured in a simple manner. A very high degree of flexural strength is achieved with minimum additional weight through an L-shaped sheet metal angle partially surrounding the elastic wire located in the bend of the sheet metal angle. The two legs of the support element prevent the sheet metal angle from slipping on the wire.
It is also advantageous for a non-positive bond to be between the wire and the sealing element. The wire, rounded on its downstream end, engages in a depression of the sealing element and thus transfers the pressure forces of the restoring spring to the sealing element. It is advantageous if the depression has a conical shape with the bottom of the depression ideally having the same diameter as the rounded wire end.
In addition, it is advantageous if an armature of the electromagnetic circuit is designed as a flat armature, which supports the restoring spring. Due to its small height, a flat armature design is particularly recommended- The design of a flat armature allows a non-magnetic, for example, austenitic, material to be used for a valve seat support, which can be deep-drawn much better than a ferritic material, resulting in lower production costs.
With the fuel injection valve according to the present invention, injection points can be preset to a considerable degree (e.g., as early as in the intake pipe) in a simple manner (extended tip injector), since the lengths of the deep-drawn valve seat support and the elastic wire can be easily and inexpensively varied. It is of great advantage that in the above-mentioned design of the valve needle the preset injection point can be achieved with a very small moving mass.
In order to guarantee that the injection valve opens when the magnet coil is energized, an elastic corrugated disk is arranged between the sealing element and a valve seat body which features the valve seat and is coupled to the sealing element; the elastic force of the corrugated disk opposes the elastic force of the restoring spring. Thus the sealing element is raised from the valve seat by the corrugated disk. The corrugated disk advantageously has bore holes, slots, or grooves to allow the fuel to flow in the direction of the valve seat. In addition, the corrugated disk is responsible for the radial guidance of the sealing element in the valve seat support.
The valve seat body may also have a conical orifice, in which an at least partially conical self-centering perforated disk can be inserted. Thus expensive centering devices are not required for the assembly of the perforated disk.
The design of the armature and the valve seat body as a flat armature and a flat seat allows relatively great guidance tolerances, which reduces manufacturing costs.
These above-mentioned overall design features, making welding operations on the sealing element and the valve seat body unnecessary, allow ceramic to be used for these two components, for example, when aggressive fuels are used.


REFERENCES:
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patent: 5881957 (1999-03-01), Mizuno et al.
patent: 5997507 (1999-12-01), Dysarz
patent: 25 08 390 (1976-09-01), None
patent: 34 27 526 (1986-02-01), None
patent: 35 35 438 (1987-04-01), None
patent: 0 354 659 (1990-02-01), None
patent: 334083 (1930-08-01), None

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