Abstract: A common feature of known pump devices, which for diagnostic purposes build up an overpressure in a fuel vapor trapping system, is that a connection of an adsorption filter with the ambient air is closed for the duration of the diagnosis. In the event of a malfunction of the shutoff valve, for instance from seizing, a buildup of negative pressure that is dangerous to the fuel tank can occur, which can be avoided by guard valves provided on the fuel tank according to the following pump device, whose valves needed for generating the overpressure are embodied such that in an open position of a regeneration valve and in a closing position of a shutoff valve, by means of an adequate flow cross section A.sub.Schutz of the valves such a slight flow resistance is effected that an attainment of a negative pressure harmful to the fuel tank is precluded. The pump device according to the invention is intended for a fuel vapor trapping system of an internal combustion engine.

Abstract: The invention is directed to a method for checking the tightness of a tank-venting system used with an internal combustion engine having an intake pipe. The tank-venting system includes a fuel tank wherein fuel vapor forms, a storage device connected to the fuel tank, the storage device having a vent opening and a device for closing the vent opening, and a tank-venting valve interconnecting the intake pipe and the storage device whereby the fuel vapor is conducted from the tank to the intake pipe via the storage device and the tank-venting valve.

Abstract: The invention relates to a method for diagnosing the function of an adjusting device and includes the steps of: driving the adjusting device, detecting the effect of driving the adjusting device on a predetermined variable operatively coupled to the adjusting device; determining the adjusting device to be operable when the effect lies in a first range of possible values; and, determining the adjusting device to be inoperable when the effect lies in a second range of possible values. A third range is defined which separates the first and second ranges from each other. The method is interrupted or repeated when the effect lies in the third range.

Abstract: An apparatus for checking a tank venting system for leaks that serves to vent a fuel tank of a motor vehicle whose engine has a intake tube. The apparatus has an absorption filter connected to a ventilation line, which can be closed by means of a shutoff valve, and pressure producing devices for the production of an overpressure in the fuel tank. The pressure producing devices are embodied as actuatable by means of the vacuum in the intake tube in order to be able to forego the separate electromechanical drive devices for the pressure producing devices which have been necessary in the prior art.

Abstract: The invention relates to a tank-venting apparatus for a motor vehicle as well as a method for operating the apparatus. The tank-venting apparatus is for a motor vehicle having an internal combustion engine equipped with a charger having an output line. The tank-venting apparatus includes: a tank; an adsorption filter having a venting line extending therefrom; a tank supply line connecting the tank to the adsorption filter; a tank-venting valve connected to the engine; a valve line connecting the tank-venting valve to the adsorption filter; and, control valve means for connecting the output line of the charger to the venting line. In contrast to conventional tank venting apparatus on motor vehicles having an internal combustion engine equipped with a charger, no pump is required which pumps the vapor from the tank-venting apparatus into the intake pipe against the overpressure.

Abstract: A method for checking the operability of a tank-venting system for a motor vehicle having an internal combustion engine (10), the system including an adsorption filter (14) having a venting opening (17) at its venting end and having a connecting line (16) to a tank (15) as well as a tank-venting valve (13) which is connected into a connecting line (12) between the intake pipe (11) of the engine and the intake end of the adsorption filter, characterized in that:a difference pressure (Dp) is measured which is a measure for the pressure difference between the venting end and the intake end of the adsorption filter; and,a conclusion is drawn as to inadequate throughput capacity of the adsorption filter when the measured difference pressure exceeds a threshold value (Dp.sub.-- SW).With this method, as with similar methods provided in the disclosure, it is possible for the first time to check the throughput capacity of an adsorption filter in a tank-venting system.

Abstract: The invention is directed to a method for checking the operability of a tank-venting valve which is connected in a venting line of a tank-venting apparatus between the intake pipe of the internal combustion engine and an adsorption filter equipped with a venting line. The tank-venting valve can be driven into two switching states, namely, an open state and a closed state. The method includes the steps of: driving the tank-venting valve to reach one of the two selectable switching states; checking the pressure on the end of the tank-venting valve facing away from the intake pipe and checking whether this pressure exhibits a time-dependent trace as it cannot occur in the desired switching state; and, concluding that a defect in the tank-venting valve is present when the condition checked in the previous step is satisfied. With this method, the operability of a simple tank-venting valve can be reliably checked. The method requires no special mechanical, capacitive or inductive checking arrangement.

Abstract: A method for checking the operability of a tank-venting system in a vehicle having an internal combustion engine, which tank-venting system has a tank with a tank-pressure sensor, an adsorption filter connected to the tank via a tank-connecting line, and a tank-venting valve which is connected to the adsorption filter via a valve line, in which system the adsorption filter has a venting line which can be closed with the aid of a shut-off valve, has the following steps:closing the shut-off valve;opening the tank-venting valve;determining the build-up gradient (p+) of the underpressure building up in the tank;closing the tank-venting valve;determining the decay gradient (p-) of the decaying underpressure in the tank;mathematically combining the build-up and decay gradients in a manner such that the influence of the fill level has as little effect as possible on the evaluation variable (Q) formed by means of the combination; and,comparing the value of the evaluation variable with a threshold value (Q.sub.

Abstract: The invention relates to a method for venting a fuel tank for motor vehicles equipped with internal combustion engines. The tank-venting systems of these motor vehicles are equipped with a sensor for measuring tank pressure. The signal of the pressure sensor is utilized to control the tank-venting valve in such a manner that the flow resistance of the tank-venting valve is so adjusted via its opening condition in dependence upon the signal of the pressure sensor so that the scavenging rate is limited; that is, the flow volume through the tank-venting valve is limited. The scavenging rate is so limited that the tank pressure does not drop below a pregiven threshold. The tank-venting valve acts as a controllable flow throttle for preventing critical underpressures.

Abstract: The invention is directed to a method for checking the tightness of a tank-venting system when a pregiven test condition is satisfied. The method includes the steps of: (a) building up a difference pressure in the tank-venting system irrespective of whether the pregiven test condition is satisfied; (b) determining the presence of the test condition and then closing the tank-venting system; (c) determining the value of the decay gradient of the difference pressure when the pregiven test condition is satisfied thereby losing no time in starting the check of the tightness; and, (d) drawing a conclusion as to the tightness of the tank-venting system when the value of the decay gradient is less in magnitude than a threshold decay gradient. In this way, as soon as the test condition is satisfied, a determination of the value of the decay gradient of the difference pressure already built up can be started. An apparatus for carrying out the method is also disclosed.

Abstract: A breather valve for a gas tank of an internal combustion engine having an adsorption filter which is linked to the atmosphere by a breather line which is controlled by a shut-off valve. As air flows through the shut off valve, contaminations entrained in the shut off valve may deposit in the shut-off valve, so that it will no longer close tightly. For this reason, a particle filter has been arranged in front of the shut-off valve. The particle filter is of a large surface area which is integrated in the housing of the adsorption filter, thus contamination of the shut-off valve (51) and an excessive pressure drop of the air flowing through the particle filter (41) is avoided. The integrated construction facilitates a simple assembly of the adsorption filter (41) which is suitable for internal combustion engines in motor vehicles.

Abstract: A method for determining the operability of a tank-venting system on a motor vehicle subjects the signals for the volume flow through the tank-venting valve and the signals for the pressure difference between the tank interior and the ambient to a cross-covariance analysis. The above-mentioned signals are formed by a high pass in advance of forming the cross-covariance function and the maximum or the mean value of the cross-covariance function is formed with respect to the product of the two input variables. A variance measure is formed for the signal of the volume flow through the tank-venting valve and a transfer factor is computed from the variance measure and the mean value or maximum. The tank-venting system is deemed to be operational when the transfer range lies in a pregiven region. An advantage of the method is seen in the independence of the tank-pressure changes which are not caused by volume-flow changes through the tank-venting valve.

Abstract: A method for testing for the operability of a tank-venting apparatus on a motor vehicle having an internal combustion engine, the tank-venting apparatus including a tank having a tank pressure sensor, an adsorption filter and a venting line which is closable via a shutoff valve and a tank-venting valve, the adsorption filter being connected to the tank via a tank-supply line and the tank-venting valve being connected to the adsorption filter via a valve line.

Abstract: A tank venting system which avoids soiling of the negative pressure protection valve which can cause problems in functional capability. The negative pressure protection valve is preceded by the intake air filter of the engine, so that with the negative pressure protection valve opened, a pressure equalization between the atmosphere and the tank venting system takes place by means of intake air filtered by the intake air filter. The tank venting system according to the invention is used to vent a fuel tank of a mixture-compressing internal combustion engine with externally supplied ignition.

Abstract: A device for detecting the fluid level in the tank of a motor vehicle has a tank leaktightness testing device, a gas evolution testing device for testing whether the fuel in the tank vaporizes, a pumping-out/sequence control deice for subjecting the tank to a change procedure, a gradient detection device for detecting the value of a pressure change gradient parameter from at least one pressure change and one time period associated therewith, and a fluid level output device which receives the signals from the tank leaktightness testing device, the gas evolution testing device and the gradient detection device in order to output the instantaneous value of the fluid level with the aid of a known interrelation between pressure change gradient parameter and fluid level whenever the tank is sufficiently leaktight and the vaporization of the fuel is sufficiently low.

Abstract: A breather valve for the gas tank of an internal combustion engine having an adsorption filter which is linked to the atmosphere by a breather line which is controlled by a shut-off valve. The tank breather valve is constructed so that pressure build up in the fuel tank, the lines, and the adsorption filter do not lead to damage of the valves. The magnetic circuit of the shut-off valve provides that above a predetermined pressure in the adsorption filter, the generated pressure is sufficient to open the shut-off valve, thereby facilitating pressure relief without any damage. The breather is particularly suitable for internal combustion engines in motor vehicles.

Abstract: A method for alternately carrying out phases with and without tank venting during operation of an internal combustion engine equipped with a tank-venting assembly is characterized in that the ratio of the time spans with and without tank venting is selected to be dependent upon operating data of the engine or of the tank-venting assembly. Preferably, a variable is measured which is a measure for the fuel quantity to be regenerated during tank venting and the above-mentioned ratio is increased in favor of the tank-venting time span with respect to the base ratio when the value of the measured variable exceeds an upper limit (Dp.sub.-- SMW; FTEA.sub.-- SWU). This method makes possible that an adsorption filter and a tank-venting valve in the corresponding arrangement can be dimensioned for lesser throughput quantities than previously without the danger being present that fuel vapors escape to the ambient.

Abstract: An adsorption filter is linked to the atmosphere by a breather line to prevent condensates from settling in the shut-off valve, as they flow through the breather, so that this valve becomes unable to function. The breather has a vertical arrangement of the shut-off valve with a magnetic circuit arranged above the valve operative parts to ensure that any condensate which forms can flow off, without impairing the function of the shut-off valve (51, 51'). The breather is particularly suitable for internal combustion engines in motor vehicles.

Abstract: The invention relates to a method and an arrangement for diagnosing a tank-venting system of a motor vehicle wherein a pregiven underpressure is adjusted in the tank-venting system in order to determine if the system is tight. Then, a check is made to determine at which gradient this underpressure decays when the tank-venting system is completely closed. The system is evaluated as being leaky when the underpressure decays more rapidly than corresponding to a pregiven threshold. To arrive at the pregiven underpressure, much more vapor must be pumped from the system for an empty tank than for a full tank. The pulse-duty factor for opening the tank-venting valve on the system is made to vary in dependence upon the fill level of the tank in order that pumping does not take place too rapidly or too intensely for a full tank and not too long for an almost-empty tank.

Abstract: A tank-venting system has the following features: a tank 10; an adsorption filter 13 which is connected to the tank via a tank-connecting line 12 and which has a venting line 14 which can be closed off by a shut-off valve 15; and, a tank-venting valve 16 which is connected to the adsorption filter via a valve line 17; a pressure connection 21 on the valve line close to the tank-venting valve; and, a pressure sensor 11 on the tank.With the aid of this tank-venting system, the following method can be carried out: closing the tank-venting valve and the shut-off valve; supplying compressed air to the pressure connection; measuring the pressure in the tank; and, checking if the pressure satisfies a pregiven pressure condition and determining the tank-venting system as being inoperable in the event that this is not the case.