Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
1998-06-17
2001-01-09
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S462000
Reexamination Certificate
active
06170466
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is based on a quantity control valve for a fuel injection system, used in internal combustion engines.
From German Patent Disclosure DE 195 49 108.4, which was not published prior to the filing date of the present application, among other elements a quantity control valve is disclosed that has a longitudinal slide which is movable in a valve housing between a restoring spring chamber and the control chamber and which opens counter to the action of a restoring spring. The hollow longitudinal slide is subjected to fuel from a low-pressure pump via the restoring spring chamber. The fuel enters the control chamber through a throttle restriction located in the longitudinal slide. As soon as the fuel pressure in the control chamber exceeds a certain value, the longitudinal slide opens counter to the action of the restoring spring, and as a result the fuel passes through the longitudinal slide to reach the high-pressure pump via an uncovered outlet bore. The opening of the valve is additionally reinforced with the aid of an electromagnetic drive acting directly on the longitudinal slide.
OBJECT AND SUMMARY OF THE INVENTION
The quantity control valve according to the invention allocates the fuel, flowing in from at least one low-pressure pump, to at least one high-pressure pump. For driving the longitudinal slide, the inflowing fuel is delivered into the first control chamber via a throttle or baffle valve, past the longitudinal slide. In the second control chamber, there is either a restoring spring that urges the longitudinal slide in the direction of its closing position, or the longitudinal slide there has an effective face-end surface area upstream of which a control line containing a throttle valve ends; the surface area of this end face is smaller than the effective surface area of the face end in the first control chamber. In the closing position, the longitudinal slide blocks off the outlet bore with one of its cylindrical guide portions, while with regard to the inlet bore it has a narrowed region, which opposite the longitudinal slide bore leaves a flow cross section open that changes gradually to zero in the direction of the guide portion.
This quantity control valve requires no external electromechanical drive. The drive of the longitudinal slide is effected solely via the fuel pumped by the upstream low-pressure pump. In the valve, the flow of fuel is controlled by a targeted manipulation of cross section via a long slide stroke. Because of the long opening stroke of the longitudinal slide in conjunction with the hydraulically favorably designed contour in the constricted region, the fuel flow can be controlled sensitively with only slight flow losses.
The opening stroke of the longitudinal slide associated with a variation of the flow cross section is at least twice as long as twice the diameter of the outlet bore. In the event that the outlet bore does not have a circular cross section, the theoretical diameter resulting from the cross-sectional area—regardless of its peripheral outline—is defined as the reference dimension.
With one quantity control valve, a plurality of high-pressure pumps can be supplied independently of one another.
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment taken in conjunction with the drawings.
REFERENCES:
patent: 2995898 (1961-08-01), Thorner
patent: 4660522 (1987-04-01), Babitzka
patent: 4869219 (1989-09-01), Bremmer
patent: 5092299 (1992-03-01), Muntean
patent: 5884606 (1999-03-01), Kellner
patent: 5996557 (1999-12-01), Muraki
patent: 299337 (1989-01-01), None
patent: 2132700 (1984-07-01), None
patent: 2216632 (1989-10-01), None
patent: WO97/24526 (1997-07-01), None
Blanc Regis
Fromentoux Andre
Goettel Thomas
Klinger Horst
Kuhn Uwe
Greigg Edwin E.
Greigg Ronald E.
Miller Carl S.
Robert & Bosch GmbH
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