Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1999-07-21
2001-06-19
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S458000, C239S533900
Reexamination Certificate
active
06247452
ABSTRACT:
PRIOR ART
The invention is based on a fuel injection valve for internal combustion engines. In one such fuel injection valve, known from U.S. Pat. No. 4,972,997, a pistonlike valve member is guided axially displaceably in a bore of a valve body. The valve member, on its end toward the combustion chamber, has a conical valve sealing face, with which it cooperates with a conical valve seat face on the valve body, which face is formed on the inward-projecting end of the closed valve bore. A contact edge between the valve sealing face on the valve member and the valve seat face forms an encompassing sealing edge. This sealing edge, formed when the injection valve is closed, thus seals off a pressure chamber, adjoining the sealing edge upstream of the pressure chamber, when the injection valve is closed. Downstream of this sealing edge, at least one injection opening that discharges into the combustion chamber of the engine to be supplied is provided in the wall of the valve body and leads away from the valve seat face.
However, this known fuel injection valve has the disadvantage that the control times of the valve member, because of the strong hydraulic forces on the valve member, are too long for injection valves that switch at very high speed. The known fuel injection valve is therefore very large, because there are so many components axially in line with one another, which limits the utility of the known fuel injection valves in engines where the available installation space is scarce.
ADVANTAGES OF THE INVENTION
The fuel injection valve of the invention for internal combustion engines, has an advantage over the prior art that very slight control forces and thus very rapid valve stroke motions of the valve member of the injection valve are possible. These rapid adjustment motions become possible because of the small hydraulically operative surface areas of the valve member and the small control volume, since only small moving masses have to be displaced. This is advantageously attained in that the valve member has a guide bore, with which it is slidably displaceably guided on a tang of a stationary insert body. The displaceable valve member is hydraulically pressure-balanced in the intervals between injections, so that no leakage losses occur. Thus sealing from the outside for outflowing leaking oil is unnecessary, and along with the leakage heat development and any possible entry of dirt can also be reduced, because of the good separation between sealing components and guidance components. A further advantage is attained because of the very short structural design of the fuel injection valve of the invention; as a result, the required installation space in the engine to be supplied can also be reduced sharply. The restoring spring that urges the valve member of the injection valve in the closing direction merely needs to close the injection valve when the system is pressureless, and thus it can be made correspondingly small in size. During the high-pressure-filled mode, the closing movement and the holding of the valve member on the valve seat face are effected by means of the design of the hydraulic opening and closing faces that are operative at the valve member. The hydraulic engagement area of the closing faces on the valve member, when the injection valve is closed, is greater than the hydraulic engagement areas acting in the opening direction. The opening stroke motion of the valve member is advantageously limited by mechanical stroke stop faces on the tang of the stationary insert body, but hydraulic stroke stops are alternatively possible as well. The control valve that opens the control chamber into a relief chamber can be embodied as a 2/2-way magnet valve, as shown in the exemplary embodiment, but 2/3-, 3/2- or 3/3-way control valves can also be used as an alternative. The valve member is guided axially over its inner guide bore on the tang of the stationary insert body, but it is also possible to provide a further guide on the outer circumference of the valve member, inside the valve body, in addition. When this kind of improved guide is used, fuel flow openings on the valve member are provided which enable a flow of fuel from a pressure chamber to the valve seat faces; these openings can be embodied as ground face sections on the jacket face of the valve member, or as through bores. The valve member itself can advantageously be embodied in two parts, with a headpiece that has the valve sealing face being inserted, preferably press-fitted, into a sleeve. This kind of two-piece valve member can be produced in a simple way and with high precision. A further advantage of the fuel injection valve of the invention is the possibility of hydraulically floating support of the insert body, carrying the tang, in the valve body, so that the insert body, and the valve member guided on the insert body, can be reliably centered relative to the valve body.
Further advantages and advantageous features of the subject of the invention can be learned from the description, drawing and claims.
REFERENCES:
patent: 3610529 (1971-10-01), Huber
patent: 3640466 (1972-02-01), Steiger
patent: 4156560 (1979-05-01), Chklich et al.
patent: 4566416 (1986-01-01), Berchtold
patent: 5409165 (1995-04-01), Carroll, III et al.
patent: 5685483 (1997-11-01), Ganser
Boecking Friedrich
Dittus Bernd
Gimie Mahmoud M
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Yuen Henry C.
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