Internal-combustion engines – Charge forming device – Having fuel vapor recovery and storage system
Patent
1998-06-19
1999-11-30
Moulis, Thomas N.
Internal-combustion engines
Charge forming device
Having fuel vapor recovery and storage system
123520, F02M 3704
Patent
active
059923962
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a tank venting system for motor vehicles with an internal combustion engine supplied from a fuel tank.
In a known tank venting system of this type (German Patent Disclosure DE 195 23 935 A1), where it is called a fuel vapor trapping system, the air pump device used to generate the overpressure in the system for the sake of error diagnosis communicates by its pump outlet with the air inlet of the filter housing, via a flexible compressed air line. A shutoff valve is integrated into the pump housing of the air pump device and controls a direct flow course from the pump inlet of the pump housing, which is occupied by an air filter, and the pump outlet. The air outlet of the filter housing is connected to the intake tube of the engine via a regeneration valve. In the so-called filter or regeneration mode, with the shutoff valve open in order to regenerate the adsorption filter, embodied as an activated charcoal filter, in the filter housing, air is aspirated by means of a negative pressure generated in the engine intake tube; this air flows into the filter housing via the opened shutoff valve in the pump housing, the compressed air line, and the air inlet, and in the fg flows through the adsorption filter and in the process carries fuel vapors that have been deposited there along with it and through the regeneration valve enters in metered fashion into the intake tube. For error diagnosis, the shutoff valve and the regeneration valve are closed, and in the system comprising the tank venting system and the fuel tank the air pump device generates an increased pressure. Once the pressure buildup is concluded, there is a wait for some time until the pressure has dropped again, possibly because of a leak in the tank venting system, in which case the time elapsed until the pressure reduction is a measure of the magnitude of the leakage opening that has occurred.
ADVANTAGES OF THE INVENTION
The tank venting system according to the invention has the advantage of substantially reducing the requisite installation space in the motor vehicle; the hose connection previously usual between the pump outlet of the pump housing and the air inlet of the air filter is omitted. Installing the tank venting system in the motor vehicle is simplified substantially, because the adsorption filter and the air pump device can be premounted as a module. The attendant economy in terms of material costs and reduction in assembly time leads to a marked reduction in production costs. By providing a large-area adsorption filter in the filter housing, the function of the tank venting system is assured over a long service life. It is then possible to do without a separate air filter at the pump outlet of the pump housing, if an air filter is integrated into the filter housing. This is an aid in saving still further installation space. The spring-elastic fastening of the pump housing to the filter housing provides for an acoustical and mechanical decoupling between the two housings.
By the provisions recited, advantageous refinements of and improvements to the tank venting system disclosed are possible.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in further detail below in terms of an exemplary embodiment shown in the drawings. Shown are:
FIG. 1, a schematic sectional view of a tank venting system built into a motor vehicle with an internal combustion engine;
FIG. 2, a perspective view of a pump housing in the tank venting system of FIG. 1;
FIG. 3, a plan view of a detail of a filter housing in the tank venting system of FIG. 1;
FIG. 4, a longitudinal section taken along the line IV--IV of FIG. 3 of a detail of the filter housing with the pump housing mounted on it.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
The tank venting system for a motor vehicle with an internal combustion engine, shown schematically in FIG. 1, is disposed between a fuel tank 10 and an intake tube 11, which has a throttle valve 12 of the engine; the connection to the intake tube 11 is made downstream of the throttle
REFERENCES:
patent: 5715799 (1998-02-01), Blomquist et al.
patent: 5730107 (1998-03-01), Blumenstock
Blumenstock Andreas
Krimmer Erwin
Miehle Tilman
Schulz Wolfgang
Zimmermann Manfred
Greigg Edwin E.
Greigg Ronald E.
Moulis Thomas N.
Robert & Bosch GmbH
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