Internal-combustion engines – Charge forming device – Having fuel vapor recovery and storage system
Patent
1991-10-08
1993-03-16
Cross, E. Rollins
Internal-combustion engines
Charge forming device
Having fuel vapor recovery and storage system
123198D, 123519, F02M 3302
Patent
active
051935120
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a tank-venting system for a motor vehicle and methods for checking the operability of such a system.
BACKGROUND OF THE INVENTION
A tank-venting system generally has a fuel tank and a tank-venting valve which is connected to the intake pipe of an internal combustion engine so that fuel vapors can be evacuated by suction with the aid of the underpressure in the intake pipe. Usually, the volume located above the fuel in the tank is not directly evacuated by suction; rather, an adsorption filter, usually an activated carbon filter, is connected between the tank and the tank-venting valve. This activated carbon filter adsorbs fuel in those periods in which no drawing out by suction via the intake pipe occurs, for example when the internal combustion engine is at standstill or when the tank-venting valve is kept closed due to the current operating state.
There is a risk of tank-venting systems developing leaks or the tank-venting valve not operating correctly. The operability of systems of this kind is therefore to be checked repeatedly during the operation of a motor vehicle.
The most important method for checking the operability of a motor vehicle tank-venting system is based on a proposal of the California Environmental Authority CARB. According to this method, when opening the tank-venting valve, a check is made as to whether a lambda controller has to carry out a correction of its control output. This is always the case when air with fuel vapor is evacuated by suction of the tank-venting system. However, it is also the case that the adsorption filter can be completely regenerated and that the fuel in the tank is completely evaporated. When the tank-venting valve is opened, no fuel is supplied in addition to that which is supplied to the injection valves of the internal combustion engine according to the control output of the lambda control. In such a case in which therefore no fuel is supplied by the tank-venting system, that is, the lambda controller does not have to carry out a correction, it is unclear whether the tank-venting system has developed a leak or whether no fuel is being supplied because of the mentioned reasons. In order to be able to decide this question, according to the known method, an evaluation of the signal from the lambda controller only occurs when a fuel temperature sensor indicates that a predetermined minimum fuel temperature is exceeded and a tank level sensor indicates that the vehicle tank has been filled. It is assumed that fuel vapor would then have to be present in the system in any event which vapor is drawn in when the tank-venting valve is opened and which then leads to a correction of the lambda controller. However, with this method incorrect decisions repeatedly occur if there is in fact evaporated fuel in the tank, refilling occurs with the same kind of fuel and the adsorption filter is largely regenerated.
Accordingly, there was still the problem of specifying a method for checking the operability of a motor vehicle tank-venting system which emits as few unjustified fault reports as possible. In addition, there was the problem of specifying a tank-venting system whose operability can be checked in a particularly reliable manner.
SUMMARY OF THE INVENTION
The tank-venting system according to the invention for a motor vehicle has the following parts: a fuel tank; an adsorption filter which is connected to the fuel tank via a filter line and which has a venting line with a controllable shut-off valve; and, a tank-venting valve which connects the adsorption filter to the intake pipe of an internal combustion engine via a valve line.
The system is different from known systems in that the venting line of the adsorption filter can be shut off in a controlled manner. This permits the methods according to the invention specified below for the checking the operability of the system. The methods have the concept in common that they utilize the possibility of shutting off the venting line of the adsorption filter.
The method a
REFERENCES:
patent: 4173207 (1979-11-01), Hiramatsu
patent: 4338106 (1982-07-01), Mizuno et al.
patent: 4430099 (1984-02-01), Yanagisawa et al.
patent: 4646702 (1987-03-01), Matsubara
patent: 4702216 (1987-10-01), Huruta et al.
patent: 4817576 (1989-04-01), Abe et al.
patent: 4862856 (1989-09-01), Yokoe et al.
patent: 4872439 (1989-10-01), Sonoda et al.
patent: 4949695 (1990-08-01), Uranishi et al.
patent: 4953514 (1990-09-01), Beicht et al.
patent: 5021071 (1991-06-01), Reddy
patent: 5085197 (1992-02-01), Mader et al.
Denz Helmut
Steinbrenner Ulrich
Wagner Wolfgang
Wild Ernst
Cross E. Rollins
Moulis Thomas
Ottesen Walter
Robert & Bosch GmbH
LandOfFree
Tank-venting system for a motor vehicle and method for checking does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tank-venting system for a motor vehicle and method for checking , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tank-venting system for a motor vehicle and method for checking will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-346011