Device for a fuel system of an internal combustion engine

Details Device for a fuel system of an internal combustion engine Device for a fuel system of an internal combustion engine

1998-08-06

2000-12-19

Wilson, Pamela

Fluid handling

Line condition change responsive valves

With separate connected fluid reactor surface

123514, F16K 3136

Patent

active

061615749

DESCRIPTION:

BRIEF SUMMARY
PRIOR ART

The invention is based on a device for a fuel system of an internal combustion engine.
One such device is known from German Patent Disclosure DE 44 02 224 A1. This device has a feed pump, which is disposed in the supply tank and can be introduced through an opening in the supply tank. The opening in the supply container can be closed by means of a closure part on which a pressure regulator is disposed. The pressure regulator has a pressure chamber which has a communication with the pressure side of the feed pump, with the internal combustion engine, and with a relief line. The closure part has a plastic, flangelike basic body that closes the opening. An indentation is formed in the basic body, and a stub embodied integrally with the basic body and forming a communication of the pressure chamber with the relief chamber protrudes into this indentation. To form the pressure chamber, the indentation of the basic body is covered with an elastically deformable diaphragm that cooperates directly with the face end of the stub, as a seat. The diaphragm is urged by a spring toward the stub, and if a predetermined pressure in the pressure chamber is exceeded, the diaphragm releases the stub for communication of the pressure chamber with the relief chamber. The diaphragm is secured to the basic body.
In the known device, the diaphragm is placed in the indentation, the spring is placed on it, and then the diaphragm together with a covering is braced against the basic body. Since in the known device the force of the spring acts on the diaphragm before the diaphragm is firmly fastened in place, it is possible to prevent with certainty that the diaphragm will shift to the side somewhat, thus allowing functional disturbances (such as pressure regulation errors, leaks, and so forth) to occur. If the device is installed in an engine compartment, then leaks can be very dangerous.
In an alternative embodiment of a device of DE 44 02 224 A1, it is provided that the housing receiving the spring has a flange on which free ends, bent outward, are formed. To secure the housing, the flange is disposed relative to a collar of a recess of the basic body, and as a result an outer edge of the diaphragm is fastened in place. The free ends of the flange engage the hook, disposed on the collar, from behind, and as a result the flange retains the housing on the basic body and fastens the diaphragm in place. However, this embodiment has the disadvantage that the hooks of the recess must absorb the fastening force of the spring that acts on the diaphragm, so that the diaphragm will close the stub toward the pressure chamber. The attendant major retention forces cannot be absorbed sufficiently by the hooks, as a result of which a drop in the regulated pressure can ensue. This is true particularly because the basic body that retains the housing comprises relatively soft, easily deformable plastic. Moreover, it is has been found that after a relatively long period in service, material fatigue can occur from swelling of the plastic, and as a result the flange of the retaining element cannot be disposed with adequate initial tension relative to the recess of the basic body and the diaphragm cannot be fixed relative to the recess.


ADVANTAGES OF THE INVENTION

The device according to the invention for a fuel system has the advantage over the prior art that simple, fast mounting, for instance of an easily produced, functionally reliable preassembled unit, on the basic body is possible.
The device also has the advantage that complicated parts to form a pressure regulator, for instance, may be embodied as components of a basic body, thus making for a simple design of the preassembled unit. Thus the stub, together with the stop through which the fuel return extends, can be injection molded together with the basic body as a single plastic part using a single injection mold. This has the advantage that in the production of the basic body, no additional effort and expense are needed to produce the stop. In addition, the design of the preassemb

REFERENCES:
patent: 4664142 (1987-05-01), Bertsch et al.
patent: 5076320 (1991-12-01), Robinson
patent: 5609138 (1997-03-01), Mutschler
patent: 5778926 (1998-07-01), Tanaka
patent: 5785080 (1998-07-01), Herbst
patent: 6016831 (2000-01-01), Bueser et al.

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