The present invention relates to a venting and/or air admission valve, which is also referred to as a shutoff valve, for an operating fluid reservoir. The present invention furthermore relates to an operating fluid reservoir having a venting and/or air admission valve and to a venting and/or air admission valve system. The operating fluid reservoir can be a fluid reservoir for aqueous urea solution required for an SCR method (Selective Catalytic Reduction) for lowering nitrogen oxide emissions from diesel vehicles. This aqueous urea solution is injected into the exhaust section from the SCR catalyst, e.g. by means of a dosing pump or an injector. In the following text, reference will be made to a fuel reservoir, although all the embodiments can also be used in a corresponding manner for fluid reservoirs for aqueous urea solution or more generally for operating fluid reservoirs.

To fill a fuel reservoir with fuel, the usual practice is to insert a fuel pump nozzle into a filler pipe opening into the fuel reservoir, thereupon allowing fuel to be introduced into the fuel reservoir. To enable the fuel reservoir to be filled unhindered, the air in the fuel reservoir or the air/gas mixture in the fuel reservoir must be able to escape from the fuel tank since, otherwise, a pressure rise within the fuel tank would hinder the filling process.

To vent air from the fuel reservoir, one or more venting valves in fluid communication with a vent line are provided in the fuel reservoir, wherein the vent line can optionally be in fluid communication with an activated carbon filter. Air/gas mixture displaced from the fuel reservoir is either filtered by the activated carbon filter, ensuring that only small quantities of fuel vapor, if any, are released to the environment, or, in the absence of an activated carbon filter, are released directly to the atmosphere.

Venting and/or air admission valves known from the prior art, which are also referred to below simply as venting valves or shutoff valves, comprise a hollow valve housing, which has at least one communication opening, by means of which a valve housing interior is in fluid communication with the environment thereof. When the venting valve is installed in a fuel reservoir, the valve housing interior is in fluid communication via the communication opening with the fuel reservoir interior, thus allowing an exchange of fuel and of a fuel vapor/air mixture between the fuel reservoir interior and the valve housing interior via the communication opening. The valve housing interior is in fluid communication with a vent line via a ventilation opening arranged in a valve seat. A valve body, which can move freely in the valve housing interior and is also referred to as a float or float element or buoyant element, closes the ventilation opening at and above a predetermined operating fluid level within the fuel reservoir, thus preventing liquid and/or gas escaping from the valve housing. Below the predetermined operating fluid level, the valve body is at a distance from the ventilation opening, with the result that the valve housing interior and the ventilation line are in fluid communication. The distance between the operating fluid level and the fuel reservoir inner wall on which the venting valve is fastened at which the valve body is subject to so much lift by the fuel that it closes the ventilation opening is referred to as the shutoff height.

If the fuel reservoir warms up, e.g. due to an adjacent exhaust system or due to a high ambient temperature, the vapor pressure of the fuel within the fuel reservoir rises. When the shutoff valve is closed by the fuel level and there is no second venting path or when the second venting path is closed by a pressure relief valve (also called a pressure retention valve) , the tank internal pressure rises, causing the fuel reservoir to expand. This, in turn, has the result that the operating fluid level in the fuel reservoir falls, as a result of which too the valve body falls in the valve housing and moves away from the valve seat and thus exposes the ventilation opening. The excess pressure built up in the fuel reservoir can thus escape via the reopened valve. This process is repeated until the supply of heat has ceased or an equilibrium has established itself between the liberation of gas due to the supply of heat and leakage through the pressure relief valve.

It is desirable to be able to achieve different shutoff heights for an operating fluid reservoir, e.g. for a fuel reservoir. This may be necessary if a motor vehicle is to be sold in different countries, in which different regulations apply to fuel reservoirs, or if the same valve is to be used for several reservoirs. For this purpose, the prior art includes what are known as "riser pipe shutoff valves", in which the lateral communication openings are extended as far down as the desired shutoff height in the installed position, making it possible to achieve closure of the venting valve or riser pipe shutoff valve in the case of a lower operating fluid level. For different shutoff heights, it is then necessary in each case to use different venting valves or riser pipe shutoff valves, each with different valve housings, in which the positions of the communication openings are matched to the desired shutoff height.

With this kind of riser pipe shutoff valve, it is possible during the filling of a fuel reservoir for the displaced fuel vapor/air mixture to be carried away via the communication opening and the vent opening to the activated carbon filter or to the atmosphere as long as the communication opening is not closed by the fuel in the fuel reservoir. With this type of venting valve, the shutoff height is the distance between the fuel reservoir inner wall and the upper edge of the communication opening. When the operating fluid level has reached the shutoff height, gas exchange between the fuel reservoir interior and the valve housing interior is no longer possible. If more fuel is introduced, it rises in the filler pipe, causing a corresponding rise in the pressure within the fuel reservoir, thereby raising the fuel column within the valve housing and hence also the valve body by virtue of the buoyancy thereof. Above a predetermined fuel level within the valve housing, the valve body closes the vent opening. If a motor vehicle with a fuel reservoir having a correspondingly designed riser pipe shutoff valve is parked with a full or approximately full fuel tank and the fuel tank then warms up, the excess pressure which arises due to evaporation of the fuel should be discharged by pressure relief valves. However, the opening pressure of such a pressure relief valve is matched to the height of the filler pipe and, as a result, the fuel reservoir often expands before the pressure relief valve opens. In such a case, the operating fluid level in the fuel reservoir falls. As a result, an upper part of the communication opening is no longer closed by the fuel, allowing the fuel vapor/air mixture in the compensating volume of the fuel tank to spread through the upper section of the communication opening into the valve housing interior. Since the operating fluid level within the valve housing interior is higher than in the fuel reservoir interior, the fuel vapor/air mixture rises to the surface of the fuel column within the valve housing interior in the form of gas bubbles. This in turn reduces the lift on the valve body since the gas bubbles in the fuel reduce the effective density thereof. As a result, the valve body no longer closes the ventilation opening.

The gas bubbles rising to the surface of the fuel entrain fuel in the form of small droplets as they pass through the surface of the fuel, and these too spread out in the direction of the ventilation opening and pass through the ventilation opening into the ventilation line and, via the latter, into the activated carbon filter. If the motor vehicle is parked in a warm environment for a prolonged period, the process of fuel loss described above continues for a long period via the ventilation line, and significant quantities of fuel can thereby be lost via the venting and/or air admission system. As a result, the ability to function of the activated carbon filter is massively impaired, and more fuel vapor is released to the environment .

It is the underlying object of the present invention to provide an improved venting and/or air admission valve for an operating fluid reservoir, e.g. for a fuel reservoir or for an SCR fluid reservoir, in which different shutoff heights can be achieved with one valve housing and which has a significantly reduced fuel loss, if any, when an operating fluid reservoir fitted with the venting and/or air admission valve according to the invention is subjected to heat in the full or approximately full state. According to the invention, this object is achieved by the features indicated in claim 1. Advantageous embodiments are indicated in the dependent claims. More precisely, the venting and/or air admission valve according to the invention comprises a hollow valve housing, which can be fastened in an interior of an operating fluid reservoir and which comprises at least one communication opening for fluid exchange between a valve housing interior and the interior of the operating fluid reservoir, and a ventilation opening for gas exchange between the valve housing interior and a ventilation line. The venting and/or air admission valve according to the invention furthermore comprises a valve body arranged in the valve housing interior. In the installed position of the venting and/or air admission valve in the operating fluid reservoir, i.e. when the venting and/or air admission valve is installed in the operating fluid reservoir, the valve body is at a distance from the ventilation opening when an operating fluid level within the interior of the operating fluid reservoir is below a predetermined shutoff level, with the result that the valve housing interior and the ventilation line are in fluid communication. On the other hand, in the installed position of the venting and/or air admission valve in the operating fluid reservoir, the valve body is subject to a lift from the operating fluid in the valve housing interior such that the valve body closes the ventilation opening when an operating fluid level within the interior of the operating fluid reservoir is above the shutoff level, with the result that the valve housing interior and the ventilation line are not in fluid communication. The venting and/or air admission valve is distinguished by the fact that it comprises an adapter, which can be fastened on an operating fluid reservoir wall, and that the valve housing can be fastened on the adapter in such a way that the adapter is arranged between the operating fluid reservoir wall and the valve housing. The venting and/or air admission valve according to the invention offers the advantage that different shutoff heights can be achieved for an operating fluid reservoir fitted with the venting and/or air admission valve using just a single valve housing. This is because using different adapters, each of which can be connected to the operating fluid reservoir wall, enables the shutoff level at which the valve body closes the ventilation opening to be adapted in an appropriate manner since the shutoff level is directly correlated with the shutoff height. The greater the shutoff height, the lower is the shutoff level.

It is furthermore possible to achieve different shutoff heights, and the position of the communication opening or communication openings can simultaneously be chosen in such a way that the operating fluid level is in the region of the communication opening, despite the shutoff level being reached by the operating fluid. When the operating fluid reservoir heats up, a gas exchange between the valve housing interior and the interior of the operating fluid reservoir will consequently continue to be possible. Since the gas does not have to rise through a liquid column in the valve housing interior for gas exchange between the interior of the operating fluid reservoir and the valve housing interior, the gas does not entrain any droplets of liquid either, and therefore no liquid can penetrate into the ventilation line. In the case of an operating fluid reservoir designed as a fuel reservoir fitted with the venting and/or air admission valve according to the invention, said reservoir would consequently exhibit significantly reduced fuel loss if the fuel tank were parked in a warm environment in the full or approximately full state and the fuel in the fuel reservoir therefore evaporated to an appreciable extent . The venting and/or air admission valve according to the invention can also be referred to as a shutoff valve since it serves to prevent gas exchange from the operating fluid reservoir to the environment from a predetermined operating fluid level, resulting in a rise in the pressure within the operating fluid reservoir, whereupon the level of an operating fluid introduced into the filler pipe rises, thereupon enabling the filling process to be ended by means of the fuel pump nozzle.

The valve body, which can also be referred to as a float or as a buoyant element, can move freely in a vertical direction in the installed position.

The adapter can be fastened on the operating fluid reservoir wall by an adhesive bond or by a weld, for example. As an alternative, it is also possible for the adapter to be connected to the operating fluid reservoir wall by means of a latching connection. It is furthermore also possible for the adapter to be connected to the operating fluid reservoir wall by means of a riveted joint. The adapter preferably comprises a first fastening device, and the valve housing preferably comprises a second fastening device. The first fastening device and the second fastening device are designed in such a way that the valve housing can be fastened to the adapter by means of the two fastening devices.

The first fastening device is preferably designed as a latching device and the second fastening device is preferably designed as a latching opening. As an alternative, it is also possible for the first fastening device to be designed as a latching opening and for the second fastening device to be designed as a latching device. This allows rapid fastening of the valve housing on the adapter since the valve housing can be connected to the adapter simply by being pushed onto the latter.

As an alternative, however, it is also possible for the valve housing to be adhesively bonded or welded to the adapter. This has the advantage that neither the valve housing nor the adapter has to have special fastening devices and that there is freedom in establishing the position of connection between the valve housing and the adapter. As a result, continuous shutoff heights can be achieved in different operating fluid reservoirs, while only a single valve housing has to be installed. Consequently, it is not necessary to adapt the air admission system for the operating fluid reservoir to different characteristics of different valve housings. Further advantages, details and features of the invention will become apparent below from the illustrative embodiments which are explained. More specifically : Figure la: shows a cross section through a schematically illustrated shutoff valve known from the prior art, which is fastened on an operating fluid reservoir wall and in which the ventilation opening is not closed by the valve body;

Figure lb: shows the shutoff valve illustrated in figure la, in which the vent opening is closed by the valve body;

Figure 2a: shows a cross section through a schematically illustrated riser pipe shutoff valve known from the prior art, which is fastened on an operating fluid reservoir wall and in which the ventilation opening is not closed by the valve body; shows the riser pipe shutoff valve illustrated in figure 2a, in which the vent opening is closed by the valve body; shows a cross-sectional illustration of a schematically illustrated venting and/or air admission valve according to the invention, in which the ventilation opening is not closed by the valve body; shows the venting and/or air admission valve illustrated in figure 3a, in which the vent opening is closed by the valve body; shows a cross-sectional illustration of a schematically illustrated venting and/or air admission valve system according to the invention having a first and a second adapter in the disassembled state; shows a cross-sectional illustration of a venting and/or air admission valve, which is obtained when the first adapter is assembled with the valve housing of the venting and/or air admission valve system illustrated in figure 4; and shows a cross-sectional illustration of a venting and/or air admission valve, which is obtained when the second adapter is assembled with the valve housing of the venting and/or air admission valve system illustrated in figure 4.

In the description which now follows, the same reference signs denote identical components or identical features, and therefore a description relating to one component, given with reference to one figure, also applies to the other figures, avoiding repetition in the description.

In the following description, reference is furthermore made to a fuel reservoir and to a fuel reservoir wall, but the present invention can be applied more generally to operating fluid reservoirs, e.g. in the form of an SCR fluid reservoir.

In each of figures la and lb, a shutoff valve known from the prior art is illustrated in cross section, wherein the shutoff valve in figure la is in an open state, in which gas exchange between the interior of the operating fluid reservoir and the environment is possible, whereas the shutoff valve in figure lb is illustrated in a closed state, in which gas exchange between the interior of the operating fluid reservoir and the environment thereof is prevented.

The shutoff valve known from the prior art comprises a valve housing 10, which is fastened on a fuel reservoir wall 1, for example. This fastening can be accomplished by welding the valve housing 10 on the fuel reservoir wall 1. In the shutoff valve illustrated, the valve housing 10 comprises three communication openings 13, which are designed for fluid exchange between a valve housing interior 15 and the fuel reservoir interior. The valve housing 10 furthermore comprises a ventilation opening 12, which is arranged in a valve seat 11 and is designed for gas exchange between the valve housing interior 15 and a ventilation line 2. Arranged in the valve housing interior 15 is a valve body 20, which can move freely in a vertical direction within the valve housing interior. When submerged in the operating fluid or in the fuel, the valve body 20 is subject to a corresponding lift and consequently varies its vertical position in the valve housing 10 in accordance with the fuel level. In figure la, the fuel level 4 is so low that the valve body 20 is at a distance from the ventilation opening 12, with the result that the valve housing interior 15 and the ventilation line 2 are in fluid communication with one another. Thus, if there is an increase in the gas pressure within the fuel tank, e.g. due to heating, an excess pressure which is established can be relieved to the ventilation line 2 via the communication openings 13, which are arranged in side walls of the valve housing 10, and via the ventilation opening 12.

In figure lb, the fuel level 4 is higher than that illustrated in figure la, and, owing to the lift, the valve body 20 therefore closes the ventilation opening 12, as a result of which the valve housing interior 15 and the ventilation line 2 are no longer in fluid communication with one another. If fuel continues to be introduced into the fuel tank, it is thus no longer possible for an excess pressure to be equalized to the ventilation line 2 via the communication openings 13 and the ventilation opening 12, and therefore further introduction of fuel leads to a rise in the fuel column in the filler pipe, thus allowing the filling process to be interrupted automatically when the fuel column within the filler pipe reaches the fuel pump nozzle.

If, on the other hand, a vehicle is parked with a fuel reservoir in the full or approximately full state and the fuel reservoir heats up, some of the fuel in the fuel reservoir evaporates, causing the internal pressure in the fuel reservoir to rise. Owing to this pressurization, the fuel reservoir expands, and the fuel level 4 therefore falls again. As the fuel level falls, the valve body 20 also moves away from the ventilation opening 12, allowing an excess pressure in the fuel reservoir to be dissipated.

The shutoff valve illustrated in figures la and lb has the disadvantage that different shutoff valves have to be used for different fuel reservoirs, in which different shutoff heights are necessary.

To solve this problem, "riser pipe shutoff valves" are known from the prior art, and these are illustrated schematically in figures 2a and 2b.

In the case of the riser pipe shutoff valve illustrated in figures 2a and 2b, the lateral communication openings 13 are moved down as far as the desired shutoff height SOH in the installed position, making it possible to achieve closure of the riser pipe shutoff valve at a lower operating fluid level or fuel level. For different shutoff heights SOH, it is then necessary to use different venting valves or riser pipe shutoff valves with different valve housings 10 in each case, where the position of the communication openings 13 in the side walls of the valve housing 10 has to be adapted to match the desired shutoff height SOH.

In the case of a riser pipe shutoff valve, it is possible during the filling of the fuel reservoir for the displaced fuel vapor/air mixture to be carried away to an activated carbon filter via the communication openings 13, which are arranged in the side walls of the valve housing, the vent opening 12 and the vent line 2 as long as the lateral communication openings 13 are not closed by the fuel in the fuel reservoir. The shutoff height SOH with this type of riser pipe shutoff valve is therefore the distance between the fuel reservoir inner wall 1 and the upper edge of the lateral communication openings 13. When the fuel level 4 reaches the shutoff height, gas exchange between the fuel reservoir interior and the valve housing interior 15 is no longer possible. This state is illustrated in figure 2a. If more fuel is introduced, it rises in the filler pipe that opens into the fuel reservoir, with the result that there is a corresponding increase in the pressure within the fuel reservoir, causing the fuel column within the valve housing 10 and hence also the valve body 20, owing to the buoyancy thereof, to be raised. From a predetermined fuel level within the valve housing 10, the valve body 20 closes the vent opening 12, as illustrated in figure 2b.

If a motor vehicle having a fuel reservoir with a correspondingly designed riser pipe valve is parked with a full or approximately full fuel tank (state in figure 2b) and the fuel tank then heats up, the excess pressure caused by evaporation of the fuel should be discharged by pressure relief valves. However, the opening pressure of the pressure relief valve is matched to the height of the filler pipe, with the result that the fuel reservoir often expands before the pressure relief valve opens. The expansion of the fuel tank causes the fuel level in the fuel reservoir to fall, with the result that an upper part of the lateral communication openings 13 is no longer closed by the fuel. The fuel vapor/air mixture in the compensating volume of the fuel reservoir can therefore spread through the upper section of the communication opening 13 into the valve housing interior 15. However, since the fuel level within the valve housing interior 15 is higher than in the fuel reservoir interior, the fuel vapor/air mixture rises to the surface of the fuel column within the valve housing interior 15 in the form of gas bubbles, which, in turn, reduces the lift on the valve body 20 in the valve housing interior 15 since the gas bubbles in the fuel reduce the effective density thereof. As a result, the valve body 10 falls and therefore no longer closes the ventilation opening 12.

The gas bubbles rising to the surface of the fuel entrain fuel in the form of small droplets as they pass through the surface of the fuel, and these too spread out in the direction of the ventilation opening 12 and pass through the ventilation opening 12 into the ventilation line 2 and, via the latter, into the activated carbon filter. If the motor vehicle is parked in a warm environment for a prolonged period, this process of fuel loss continues for a prolonged period via the ventilation line, and relatively large quantities of fuel can thereby be lost via the venting and/or air admission system.

A venting and/or air admission valve according to the invention, which can also be referred to as a shutoff valve, is illustrated in cross section in figures 3a and 3b, wherein the shutoff valve in figure 3a is illustrated in a state in which the ventilation opening 12 is not closed by the valve body 20, whereas in figure 3b the shutoff valve is illustrated in a state in which the vent opening 12 is closed by the valve body 20. The shutoff valve comprises an adapter 31, 32, which can be fastened on the operating fluid reservoir wall 1. This fastening on the operating fluid reservoir wall 1, which is a fuel reservoir wall 1 in the illustrative embodiment shown, can be accomplished by means of an adhesive joint, a welded joint or a riveted joint, for example. As an alternative, it is also possible for the adapter to be connected to the fuel reservoir wall 1 by means of correspondingly designed latching devices. From figures 3a and 3b, it can be seen that the valve housing 10 is fastened to the adapter 31, 32 in such a way that the adapter 31, 32 is arranged between the fuel reservoir wall 1 and the valve housing 10.

To fasten the valve housing 10 on the adapter 31, 32, the adapter 31, 32 has a fastening device 34 in the form of one or more latching devices 34 in the form of latching tongues 34, and the valve housing 10 comprises a second fastening device 14 in the form of a number of latching openings 14 corresponding to the number of latching devices 34. Pushing the valve housing 10 onto the adapter 31, 32 causes the latching tongues 34 to force the valve housing side walls apart until the latching tongues 34 latch into the latching openings 14. As an alternative, it is also possible for the valve housing 10 to be fastened on the adapter 31, 32 by an adhesive joint or by a welded joint. As an alternative, the adapter 31, 32 could also be screwed to the valve housing 10. It is also conceivable to design the adapter 31, 32 as a screw, thus making possible continuously variable adaptation.

The way in which the shutoff valve illustrated in figures 3a and 3b operates is otherwise identical with the shutoff valve illustrated in figures la and lb. Consequently, the shutoff valve according to the invention does not have the disadvantage that, when the fuel tank is subjected to pressure, fuel can enter the vent line 2 in liquid form, as is the case with riser pipe shutoff valves which are illustrated in figures 2a and 2b. Moreover, different adapters 31, 32 make it possible to achieve different shutoff heights SOH, and, as a result, only a single valve housing 10 is necessary to achieve different shutoff heights for different fuel reservoirs. This considerably simplifies the stocking of shutoff valves since it is not necessary to use different shutoff valves for different fuel reservoirs or, more generally, for different operating fluid reservoirs.

Figure 4 shows a venting and/or air admission system according to the invention having a first adapter 31 and a second adapter 32 in the disassembled state and in cross section. From figure 4, it can be seen that the axial extent of the first adapter 31 is greater than the axial extent of the second adapter 32.

When the valve housing 10 illustrated in figure 4 is assembled with the first adapter 31 and subsequently mounted in a fuel reservoir on a fuel reservoir wall 1, the shutoff valve illustrated in figure 5a is obtained. If, on the other hand, the valve housing illustrated in figure 4 is connected to the second adapter 32, the shutoff valve illustrated in figure 5b is obtained.

In the shutoff valve illustrated in figure 5a, the first shutoff height SOH 1, which corresponds to the first adapter 31, is greater than the second shutoff height SOH2, which corresponds to the second adapter 32. To achieve different shutoff heights SOH, all that is necessary is thus to stock different adapters 31, 32, which each have to be connected to identical valve housings 10.

Reference signs

I operating fluid reservoir wall/fuel reservoir wall

2 ventilation line

4 operating fluid level/fuel level

10 valve housing

II valve seat

12 ventilation opening

13 communication opening

14 fastening opening/latching opening (of the valve housing)

15 valve housing interior

20 valve body/buoyant element /float

31 adapter/first adapter

32 adapter/second adapter

34 fastening device/latching device/latching tongue (of the adapter)

SOH shutoff height

SOH1 first shutoff height

SOH2 second shutoff height