Motor vehicles – Power – With fuel supply for internal combustion engine
Patent
1990-08-03
1992-05-12
Mitchell, David M.
Motor vehicles
Power
With fuel supply for internal combustion engine
553853, 123519, 280834, B60K 15035
Patent
active
051119005
DESCRIPTION:
BRIEF SUMMARY
Regulations of law provide that fuel vapors may not be released from the fuel tank into the atmosphere. To fulfill this requirement these fuel vapors are fed through a so-called canister, which generally contains active charcoal as filter material, to the air intake system of the internal combustion engine. This filter primarily traps the fuel vapors developing while the vehicle is standing still, and is regenerated by the fact that, during operation, air is aspirated from the atmosphere through the filter. This involves relatively small amounts. Difficulty is encountered in satisfying the requirement that the fuel vapors displaced from the fuel tank when it is filled be intercepted, since their volume is relatively great and necessitates a correspondingly large canister in order effectively to prevent the emission of fuel vapors into the atmosphere. The accommodation of a large canister causes considerable problems on account of the extreme space limitations in the engine compartment.
The invention is addressed to the problem of creating a motor vehicle of the generic kind in which even a large canister can be accommodated without difficulty.
In the case of the proposal according to the invention, the normally unused space inside of the spare wheel is used to contain the canister. Since the wheel size depends on the engine size, and motor vehicles with powerful engines have larger and/or wider wheels, there is a relationship between the size of the space available for the canister and the engine size, which in turn affects the size of the fuel tank, so that it is possible to dispose in the recess accommodating the spare wheel a canister adapted to the size of the fuel tank.
By the proposal according to the invention the additional advantage is obtained that the canister is situated in the vehicle at a point which is very well protected in the case of an accident. In the conventional arrangement of the canister in the engine compartment, it can happen, especially in the event of a front-end collision, that the canister may burst and fuel may land on the hot exhaust system and ignite.
If the recess for the spare wheel is in the bottom of the trunk compartment, an annular gap open at the bottom is formed between the circumferential wall of the canister and the circumferential wall of the space accommodating the canister, and it is in communication with the interior of the canister through one or more openings in its top side, while the connecting line for the fuel vapors opens downwardly into the canister, so that, when tanking up, the displaced air laden with fuel vapors flows upward through the canister yielding the fuel to the filter material. Vice versa, when the engine is running, air is aspirated downward through the filter and the fuel stored in the filter is entrained by it.
The changeover between trapping the fuel vapors and regenerating the active charcoal filter is performed by means of a servo valve with three connections of which the first connection is connected with the fuel tank, the second with the air intake system of the internal combustion engine and the third with the canister. The valve body is held by a spring in a first position wherein the first connection is connected with the second connection and the third connection is stopped. When tanking, the valve body is brought to a second position in which the first connection is connected to the third connection and the second connection is stopped. The movement of the valve body to its second position can be brought about by a vacuum control or by an electromagnet by means of a switch when is closed when the tank cap is removed or when the pump nozzle is inserted.
An embodiment of the invention will be described herewith in conjunction with the drawings, wherein:
FIG. 1 is a diagrammatic side view of a motor vehichle, and
FIG. 2 is a section in the area of the trunk compartment for accommodating the spare wheel, showing in detail the arrangement of the canister.
The motor vehicle represented in FIG. 1 is powered by an internal combustion
REFERENCES:
patent: 4793839 (1988-12-01), Hayashida et al.
Audi AG
Mitchell David M.
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