Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1997-07-25
1998-11-24
Miller, Carl S.
Internal-combustion engines
Charge forming device
Fuel injection system
137512, 123510, 417454, F02M 3704
Patent
active
058394141
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is directed to improvement in fuel injection system for internal combustion engines. In one such fuel injection system, known from European Patent Application EP 0 531 533 A1, a high-pressure pump pumps fuel out of a low-pressure reservoir into a high-pressure collection chamber (common rail), from which a plurality of injection lines lead away to the individual injection valves protruding into the engine combustion chamber. In the known injection system, the low-pressure reservoir is embodied by a fuel tank, from which fuel is pumped by a feed pump at a low pilot pressure via a supply line into the pump work chamber of the high-pressure pump, which is embodied as a piston pump.
In order particularly during the high-pressure pumping to prevent a return flow of fuel from the pump work chamber of the high-pressure pump into the low-pressure reservoir and to meter the high-pressure supply quantity, a pressure valve, which in the known fuel injection system is actuated by means of a magnet valve, is inserted into the supply line. In the fuel injection system of the same generic type known from British Patent GB 2 263 317, however, it is also known for this pressure valve in the supply line to be embodied as a simple check valve. Another pressure valve, preferably a check valve, is inserted in the known fuel injection systems into the high-pressure line between the pump work chamber of the high-pressure pump and the common rail. This is intended to prevent a return flow of fuel, which is at high pressure, out of the collection chamber to the high-pressure pump during the intervals between fuel supply periods.
The known injection systems have the disadvantage, however, that the individual pressure valves are inserted separately into the high-pressure line and the supply line, which entails considerable engineering and assembly effort and expense.
OBJECTS AND SUMMARY OF THE INVENTION
It is a principal object of the fuel injection system of the present invention, and an advantage over the prior art that the pressure valves of the supply line and the high-pressure line are integrated into a single, common valve combination. This common valve combination is moreover advantageously inserted into the housing of the high-pressure pump, so that a compact and very favorable structural form in terms of strength can be attained. Moreover, separately installing the pressure valves in the individual lines is now unnecessary, which considerably lowers the expense for assembly.
Another object of the invention is provided by guiding the individual valve members inside one another, so that the requisite installation space can be reduced yet again, and the valve combination can be inserted in a structurally simple way into the pump housing in the axial direction of the pump piston. Part of the valve combination forms the boundary of the pump work chamber on the side remote from the pump piston, and another part at the same time forms the connection stub, which is required anyway, for connecting the high-pressure pump to the high-pressure line. Still another object of the invention is attained by the axial in-line disposition of the individual pressure valves in the valve combination, which allows the greatest possible wall thickness in the region of the pressure chambers, while the external dimensions remain the same.
The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments taken in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWING
A single exemplary embodiment of the fuel injection system according to the invention for internal combustion engines is shown in the drawing and will be described in detail below.
The drawing figure shows a section through part of the high-pressure pump and the valve combination and a schematic representation of the connecting lines.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
The fuel injection system for internal combustion e
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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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