Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2000-02-01
2001-07-17
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C137S571000
Reexamination Certificate
active
06260542
ABSTRACT:
BACKGROUND OF INVENTION
The invention relates to a fuel supply system having operative parts that are integrally formed with respect to each other.
Many different versions of fuel supply systems are known. They all comprise a container or main tank, a (fuel) pump and usually also a splash pot (often called a calming vessel or reservoir), from which the pump sucks up. The splash pot is preferably filled, usually by means of a suction jet pump which, in turn, may be fed from the forward run of the pump or from a fuel return.
The pump is often arranged directly in the splash pot, sometimes even combined with the latter to form a fuel feed unit (DE 35 10 890 C2). The latter is introduced, complete, through a recess provided in the tank ceiling and is fastened to the recess edge by means of a closing cover. The splash pot, together with the pump, is led as near as possible to the tank bottom and supported on the latter.
In modern motor vehicles, there is less and less space left for the clear height of the tanks which, instead, have to be wider in order to maintain a sufficient volume. This gives rise to increased splashing movements of the tank content in the plane of the roadway during accelerations. In order, then, to ensure a satisfactory supply of fuel to the pump and engine under all conceivable driving conditions, a large splash pot volume must be provided. However, this can be implemented reasonably only if the splash pot is of relatively great height.
Furthermore, in light of increasingly stringent emission protection regulations, the aim is, if possible, to minimize the number of potential leakage points in the fuel supply system. Attempts are therefore also made to dispense with said recess for introducing the fuel feed unit and, instead, to introduce the latter through the filler orifice which is present in any case. As a result of this, however, there is a conflict between the requirements, on the one hand, of providing as high a splash pot as possible, but, on the other hand, also of having the possibility of exchanging the pump at any time. If the splash pot reaches near to and just below the tank ceiling, the pump can no longer be demounted separately.
DESCRIPTION OF RELATED ART
A fuel supply system is already known (DE 80 33 230 U1), in which the splash pot is virtually at the same height as the clear height of the tank. The pump is arranged outside the splash pot and the tank and fed via a separately laid suction line. The splash pot, designed as a structural unit with a filling level indicator, is introduced into the main tank through a lateral orifice having a large free cross section.
[An] older patent application 197 29 261.5 describes the production of line sections which are shaped in one piece with the half shells of an injection-molded tank which, in particular, may also be designed as a suction line fixed with respect to the tank inner wall. As is known, in contrast to the blow-molded tanks in widespread use today, injection-molded tanks are produced from two half shells which, after all the necessary fittings have been mounted on the half shell inner walls, are assembled together sealingly by means of a continuous weld seam.
OBJECTS OF THE INVENTION
An object of the invention is to design a fuel supply system of the type discussed initially, in such a way that it becomes simpler to mount it.
This object is achieved, according to the invention, by integrally forming certain portions fo the full supply system as set forth below.
BRIEF SUMMARY OF THE INVENTION
When the pump is arranged in the main tank outside the splash pot and is connected to the latter via at least one suction line that is integrally formed onto an inner wall of the tank, on the one hand the free cross section of the introduction orifice can be reduced. On the other hand, the fluidic connection between the splash pot and pump is made simply by plugging the pump onto the fixed line end, if the pump has at least one pluggable fluidic connection.
It is possible, on the one hand, to introduce the splash pot (prefabricated loose) into the tank separately from the pump. It is particularly advantageous, however, for mounting purposes, if the splash pot or its continuous side wall is fixedly connected to the tank bottom, in particular is injection-molded in one piece with the latter and fixedly connected fluidically to the suction line. The splash pot can then also be erected virtually as far as the tank ceiling, as initially required, without being subjected to any restriction by the size of an introduction orifice. At the same time, dispensing with a separate bottom for the splash pot saves material and gains volume.
Expediently, the short suction line will, on the one hand, open out in the splash pot near the bottom and, on the other hand, have an opening near the inner wall, in particular the bottom, of the main tank, so that no special manual mounting operations become necessary here and no undesirable pressure drop occurs on the suction side of the pump. If the splash pot is injection-molded on fixedly, leaks between the latter and the suction line are virtually ruled out.
In a particularly advantageous way, that section of the forward-run line which is directly connected to the pump will also be connected fixedly to the inner wall of the main tank. Fixed distances between the openings of the suction line and forward-run line are thus defined.
Preferably, the opening of the suction line projects at a predetermined fixed angle from the inner wall, so that the corresponding pump connection piece can simply be plugged on. If the forward-run opening is caused to project from the inner wall in the same direction as the opening of the suction line, a particularly efficient mounting of the pump is achieved, because, by means of only a few manual operations, the latter can be plugged on and contacted fluidically on both sides.
If, furthermore, the suction and forward-run connections of the pump open out at a corresponding distance from one another on the same side of the pump casing, said side facing the tank inner wall, the pump can be plugged onto the fixed line openings in a very simple way and is consequently immediately connected fluidically.
It is known per se to branch off a part feed quantity of the pump as a propellant jet of a suction jet pump, by means of which the splash pot is constantly refilled from the main tank. In a further addition to the idea of the invention, a line injection-molded on fixedly may likewise be provided on the tank inner wall for the third pump connection required for this purpose.
If longer line sections cannot be or are not to be injection-molded on in one piece, at least their connecting openings will be injection-molded on fixedly, so that their position remains permanently predetermined unequivocally, and said openings will be connected to one another by means of additional hoses or the like.
The pluggable fluidic connections may be sealed off by means of commercially available sealing rings. The dimensional tolerances of line openings injection-molded on are low if they are appropriately shaped. With a view to the exchangeability of the pump by unplugging it and plugging in a replacement pump, the seals will be provided on the pump side and on the connection piece side, so that, if appropriate, they can be checked and replaced in a simple way.
Mounting is simplified even further if the electric connections of the pump are also located on the same casing side as the fluidic connections and corresponding electric feed contacts are provided on the tank inner wall. This is because all the pump connections required can then be made by plugging on in one manual operation. There is, in technical terms, no problem in also injection-molding electric connections in an injection-molded tank wall so that they are in a defined position with respect to the fluidic connections.
In addition to mechanical coupling via the connections, further fixing means will, of course, also be provided, in order to hold the pump permanently, but releasably, on the tank inner
Kochsmeier Christian
Low Peter Andreas
Mannesmann VDO AG
Mayer Brown & Platt
Miller Carl S.
Speer Richard A.
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