CN110273789B

CN110273789B - Filter device for a ventilation device of a fuel tank of a vehicle

Info

Publication number: CN110273789B
Application number: CN201910196733.XA
Authority: CN
Inventors: S·安佐格
Original assignee: Dr Ing HCF Porsche AG
Current assignee: Dr Ing HCF Porsche AG
Priority date: 2018-03-16
Filing date: 2019-03-15
Publication date: 2022-01-11
Anticipated expiration: 2039-03-15
Also published as: CN110273789A; DE102018106123A1; DE102018106123B4

Abstract

A filter device (10) for a ventilation device of a fuel tank (100) of a vehicle, having a filter housing (20) with a filter chamber (22), the filter chamber is filled with an adsorbent material (30) for at least partially adsorbing fuel vapour, the filter housing having a tank interface (24) for fluid communication with the fuel tank, an engine interface (26) for fluid communication with an internal combustion engine (200) of the vehicle, and a ventilation interface (28) for fluid communication with the environment, a buffer wall (40) is also arranged in the filter chamber between the tank interface and the engine interface (26), to avoid fuel vapor flooding from the tank interface (24) directly into the engine interface (26), the buffer wall (40) has at least one bore section (42) having a through-opening (44) with a flow resistance, which is dependent on the flow rate, against which fuel vapor flows.

Description

Filter device for a ventilation device of a fuel tank of a vehicle

Technical Field

The present invention relates to a filter device for a ventilation device of a fuel tank of a vehicle and a baffle wall for such a filter device.

Background

It is known that the fuel tank of a vehicle must be provided with a ventilation device. This is usually used to avoid negative pressure in the fuel tank when removing fuel into the internal combustion engine. Also, when filling the fuel tank with fresh fuel through the filling nozzle or when an overpressure is generated in the fuel tank due to thermal expansion at an external high temperature, the overpressure in the fuel tank must be balanced. In the case of overpressure, it must be possible to vent the gas from the fuel tank. This is usually vented to the environment through the vents of the ventilation device. However, it is ensured that excessive escape of fuel vapors through the ventilation device is avoided. In known fuel tanks, these ventilation devices are therefore equipped with filter devices which are equipped with an adsorption material in order to filter out or adsorb away fuel vapors at least partially before they escape to the environment.

A disadvantage in the known solutions is that the regeneration of the filter device has disadvantages. On the one hand, it is based on the fact that for regeneration, a negative pressure connection to the engine is usually provided, through which air is sucked in from the filter device in a suction manner. If a negative pressure is applied to such an engine connection, on the one hand ambient fresh air flows from the ventilation connection into the filter device and can in this way be used to desorb the fuel vapors stored therein and to convey them further into the engine connection. However, the application of negative pressure presents the following risks: in addition to or instead of the tank port, saturated fuel vapors are directly re-drawn into the engine port in a shorter path without bypassing the filter device. During the operation of the engine, this results in that the regeneration can only take place for a very short period of time, since otherwise the regeneration gas flowing into the internal combustion engine via the engine connection may have a negative composition which may have an adverse effect on the combustion process. However, the use of a so-called buffer wall in the region of the filter housing has the disadvantage that, although such a bypass can prevent a direct overflow from the tank connection into the engine connection, the same section within the filter device cannot be regenerated by the buffer wall. The filter device must therefore be correspondingly designed to be larger, since it cannot be completely returned to the regenerated state.

Disclosure of Invention

The object of the present invention is to eliminate the above-mentioned disadvantages at least partly. The aim of the invention is, in particular, to avoid the direct overflow of fuel vapors into the engine connection in a cost-effective and simple manner and still ensure a high regeneration capacity of the filter device.

The above object is achieved by a filter device and a baffle wall having the present invention. Further features and details of the invention emerge from the description of a preferred embodiment, the description and the drawings. The features and details described in connection with the filter device according to the invention are naturally also used in connection with the damping wall according to the invention and vice versa, so that the disclosure of the individual aspects of the invention can always be referred to one another.

According to the invention, the filter device is used for a ventilation device of a fuel tank of a vehicle. For this purpose, the filter device is equipped with a filter housing with a filter chamber, which is filled with an adsorption material for at least partially adsorbing fuel vapors. The filter housing has a tank interface for fluid communication with a fuel tank. The filter housing further has an engine interface for fluid communication with an internal combustion engine of the vehicle. Furthermore, the filter housing is equipped with a ventilation interface for fluid communication with the environment. Also in the filter chamber, a buffer wall is arranged between the tank interface and the engine interface to avoid fuel vapour overflowing directly from the tank interface into the engine interface. The buffer wall has at least one bore section with a through-hole having a flow resistance, which is dependent on the flow velocity, against the flow of fuel vapor.

The filter device according to the invention is based on known filter devices. The filter device is primarily intended to prevent fuel vapor from escaping to the environment when the fuel tank is vented. In normal operation, i.e. in ventilation operation, this results in the gas saturated with fuel vapor penetrating into the filter device in the gaseous state via the tank connection in the event of an overpressure in the fuel tank. When flowing through the filter chamber, the fuel vapor is retained in the adsorbent material at least partially by adsorption due to the filling with the adsorbent material. When escaping from the ventilation interface to the environment, the gas is now at least partially cleaned by adsorption of fuel vapors. It is preferred here that the filter chamber is completely or substantially completely filled with the adsorption material.

As soon as the loading state of the adsorption material exceeds a certain limit value, there is a risk that the adsorption performance is limited or reduced and fuel vapors may escape to a greater extent through the ventilation interface into the environment. In order to maintain the effectiveness and the operating capacity of the adsorbent material, the regeneration step is carried out at the latest. In order to provide regeneration of the sorption material, ambient air, which is free of fuel vapour, can now be sucked back into the filter chamber and thus into the sorption material through the ventilation interface. The suction is here performed by applying a negative pressure at the filter chamber via the engine connection. The engine connection can be connected to an internal combustion engine of the vehicle, so that a negative pressure can be applied to the engine connection in the form of suction. Once negative pressure is applied, it can diffuse through the adsorbent material in the filter chamber. In one aspect, ambient air is drawn through the negative pressure such that the ambient air, now free of fuel vapor, flows into the saturated or at least partially saturated adsorbent material. By means of the concentration equilibrium, the adsorbed fuel is at least partially desorbed from the adsorption material, so that, conversely, the fresh air flowing through from the environment now carries the desorbed fuel vapors, the adsorption material is regenerated in this way, and the loaded ambient air is introduced into the internal combustion engine of the vehicle via the engine connection.

At the same time, however, when negative pressure is applied, it is also applied at the tank interface of the vehicle. Accordingly, due to the same negative pressure, gas at least partially loaded with fuel vapor is drawn from the tank port. Thus, fresh air flowing through the ventilation interface and loaded air from the tank interface are provided in combination within the adsorption material.

In order to effectively avoid a direct overflow in the form of a bypass between the tank connection and the engine connection, a buffer wall is added according to the invention between the tank connection and the engine connection. The possibility of fuel vapour overflowing directly from the tank connection into the engine connection while avoiding a flow through the adsorption material is thereby reduced. Conversely, the fuel vapor-laden air flow or gas flow introduced through the tank connection completely surrounds the buffer wall and therefore travels a certain minimum distance through the adsorption material.

However, according to the invention the damping wall is not completely closed, but is provided with at least one aperture section. The bore section has at least two or more through-bores. These through holes are provided with a free-flow cross section having a defined flow resistance. The flow resistance is designed to be dependent on the flow rate by selection of the orifice diameter (as will be explained in further detail by way of example later). In particular, small or relatively small bore diameters of the individual through-bores are involved here, so that at higher flow rates the through-bores have a high flow resistance against throughflow and therefore a smaller volume throughput through these through-bores is possible. As soon as the flow rate decreases, the flow resistance decreases, so that the passable volume flow of gas through the through-holes can rise.

Due to the flow resistance situation at the through hole, which is dependent on the flow rate, a high pressure gradient between the engine connection and the tank connection at the beginning of the regeneration process will directly result in a high flow resistance at the through hole. This results in the buffer wall at the through-hole acting in such a way as to block the bypass between the tank connection and the engine connection, due to the pulsed rise in flow rate. Once the pressure gradient between the engine interface, the tank interface and the ventilation interface has been adjusted to an equilibrium state, the flow rate through the sorption material will decrease. At this point in time, the main flow with reduced flow velocity results in that the ambient air suitable for regeneration passes through the entire filter chamber and thus through the entire sorption material from the ventilation interface directly towards the engine interface and indirectly through the through-holes of the buffer wall towards the engine interface. By the bore section design according to the invention, on the one hand an undesired bypass between the tank connection and the engine connection can be avoided by the buffer wall, and at the same time regeneration of this subsection of the filter chamber can also be provided in the region of the tank connection by releasing the gas flow at a low flow rate.

It may be advantageous, in the filter device according to the invention, for the buffer wall to terminate with a wall section of the filter housing between the tank connection and the engine connection. This wall section is in particular a wall section which can also be referred to as the bottom of the filter device, so that the wall between the tank connection and the engine connection has a sealing relationship with the buffer wall. The interface is in particular gas-tight or fluid-tight, in order to prevent a direct bypass between the two interfaces. The buffer wall can be designed here separately from the filter housing and, for example, be mechanically fixed or fastened in the desired position.

It is also advantageous if, in the filter device according to the invention, the through-openings of the hole sections have the same or substantially the same hole diameter. The identity of the hole diameters is particularly relevant in relation to the same distance to the tank connection or to the engine connection. It is thereby ensured that a uniform flow resistance can be provided for the entire bore section and in particular for the entire damping wall. Under uniform flow conditions, the same flow behavior is produced at the entire buffer wall. The production of such through holes having the same or substantially the same hole diameter is also simplified.

Furthermore, it is advantageous if, in the filter device according to the invention, the through-openings of the hole sections have a loose porosity which is smaller than the sorption material (schu ü

) The diameter of the hole of (a). Loose porosity is understood to mean, in particular, the free space between the solid particles of the sorption material through which gas can pass. In the case that the sorption material does not relate to a bulk material but to a solid material with pores, the bulk porosity is understood to mean the corresponding pores of the solid materialDegree, wherein inter alia the porosity of the open pores is taken into account. This correlation makes it possible to keep the flow resistance in the sorption material smaller than the flow resistance which exists at the buffer wall and in particular in the pore section.

A further advantage is achieved when, in the filter device according to the invention, the through-openings of the hole section have a hole diameter in the range between about 0.5mm and about 5 mm. This involves a particularly simple and cost-effective size ratio of the bore diameter. Preferably, the individual through holes are provided with the same or substantially the same hole diameter, as already explained.

The same advantages arise when, in the filter device according to the invention, the tank connection and the engine connection are arranged opposite the ventilation connection. The ventilation interface is therefore preferably also arranged opposite the damper wall. This arrangement improves the flow behavior, especially for the already explained regeneration phase. The ambient air to be loaded thus flows from the opposite side of the ventilation connection in both directions and thus on both sides of the damping wall, i.e. in the direction of the tank connection on one side and in the direction of the engine connection on the other side, without the damping wall opposing this inflow of ambient air to be loaded.

It is furthermore advantageous that in the filter device according to the invention the buffer wall has a length of between 20% and 60% of the respective extension of the filter housing. The corresponding extension of the filter housing is also understood to be the length of the filter housing. Thus, the cushioning wall preferably does not extend over the entire length, but only over a range between about 20% of the minimum length of the extension portion and about 60% of the maximum length of the extension portion. Thereby providing effective protection against the described bypass and at the same time providing a fast regeneration capability for the regeneration process.

It can also be advantageous if, in the filter device according to the invention, the buffer wall extends between the first side wall section of the filter housing and the second side wall section of the filter housing. The buffer wall preferably terminates at both side wall sections. The two side wall sections are connected to the already explained wall sections, in particular between the tank connection and the engine connection, so that a substantially pot-shaped arrangement of the engine connection and the tank connection is provided on two different sides of the buffer wall. The lateral closure also prevents lateral circumferential flow and thus lateral bypass around the damper wall.

It is also advantageous that in the filter device according to the invention the buffer wall is arranged centrally or substantially centrally between the tank interface and the engine interface. This results in the same or substantially the same flow behavior on both sides of the buffer wall. In particular, the overflow from the adsorption material into the aperture section and on the other side of the aperture section into the adjacent adsorption material is homogenized or unified in such a way that the effect according to the invention in terms of flow can occur more advantageously at the aperture section.

At the same time, the subject of the invention is also a buffer wall for a filter device according to the invention. Such a buffer wall has at least one bore section with a through-hole having a flow resistance, which is dependent on the flow velocity, against a throughflow with fuel vapor. The buffer wall according to the invention thus brings about the same advantages as have already been described in detail with reference to the filter device according to the invention.

Drawings

Further advantages, features and details of the invention emerge from the description which follows, in which embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the individual embodiments and in the description may be of importance for the invention in each case individually or in any combination. The figures schematically show:

figure 1 shows a first embodiment of a filter device according to the invention,

figure 2 shows an embodiment of the filter device according to the invention in a first cross-section,

figure 3 shows the embodiment of figure 2 in cross-section in a top view,

figure 4 shows the embodiment of figures 2 and 3 during regeneration,

fig. 5 shows the embodiment of fig. 2 to 4 at the start of regeneration.

Detailed Description

In fig. 1, the arrangement of a ventilation device for a fuel tank 100 can be seen schematically. The fuel for the internal combustion engine 200 is located in the fuel tank 100, wherein the supply of the internal combustion engine 200 is provided by a line, not shown in detail, connecting fluid between the content of the fuel tank and the internal combustion engine 200. If the volume in the fuel tank 100 expands or a pressure change in the fuel tank 100 occurs as a result of filling, the overpressure can be relieved via the ventilation device, in particular via the filter device 10. The overpressure in this case extends through the tank connection 24 into the filter chamber 22 of the filter housing 20. Where the overpressure flows through the adsorbent material 30 and the contained fuel vapor is at least partially retained in the adsorbent material 30 by adsorption. The gas purified by adsorption in this way can be output into the environment of the vehicle via the ventilation connection 28.

For regeneration of the sorption material 30, fresh air is sucked in the opposite direction by the suction of ambient air via the ventilation connection 28, which fresh air can again receive the sorbed fuel vapors by desorption and can be discharged from the sorption material and the filter device 10. The application of the negative pressure takes place here via the engine connection 26 and the internal combustion engine 200 in fluid communication therewith.

In fig. 2 and 3, the internal components of the filter housing 20 of the filter device 10 are shown in cross section and in a top view. The ventilation interface 28 is arranged here on the right. Tank interface 24 and engine interface 26 are shown on the left. Wall section 21, which terminates with a buffer wall 42, is located between tank interface 24 and engine interface 26. The buffer wall 42 extends over approximately 45% of the longitudinal extension of the filter housing 20 from the left to the right. A hole section 42 with a plurality of through-holes 44 can be seen here over the entire length of the damping wall 40, the individual through-holes 44 having the same or substantially the same hole diameter here. As can be seen well in the top view of fig. 3, the damping wall 40 also extends to and ends with the two side wall sections 23. Thus, in the lower region of the wall section 21 and in the side regions of the side wall sections 23, the formation of an undesired bypass is avoided by means of a corresponding sealing by means of the buffer wall 40.

The function of the damping wall 40 and in particular the hole section 42 is further explained with reference to fig. 4 and 5. Thus, at the beginning of the regeneration process, a negative pressure is applied at the engine port 26. This negative pressure is thereby increased in a pulsed manner and expands into the sorption material 30. The pulsed change in pressure behavior within filter chamber 22 results in, first of all, a sudden rise that causes fuel vapor from tank connection 24 and air from the environment to be drawn through ventilation connection 28 at high flow rates. However, it is decisive here to consider this pulsed first phase of the flow behavior, i.e. to suck fuel vapor from tank connection 24 into filter chamber 22 at a high flow rate. At such high flow rates, the individual through holes 44 have a high flow resistance, so that the majority of the fuel vapor flowing in at high flow rates from the tank connection 24 is guided along the smallest path in fig. 5 around the entire buffer wall 40 and thus through the sorption material 30. Purified gas may overflow engine interface 26 in this manner only after a substantial portion of the fuel vapor has been sufficiently long and correspondingly adsorbed in adsorbent material 30.

Once the flow behavior normalizes and the pressure differential stabilizes at equilibrium, a lower flow rate through the adsorbent material 30 is produced. This is shown in figure 4. At lower flow rates (here illustrated by thinner arrows), now predominantly fresh ambient air flows into the filter chamber 22 through the ventilation interface 28. The pressure difference is designed to be substantially the same throughout the filter chamber 22 so that uniform fresh air can enter all parts and in particular both sides of the buffer wall 40. Since a lower flow rate is provided, the flow resistance in these through holes 44 is correspondingly likewise lower. Thus, the fuel vapor laden fresh air, which is stored in adsorbent material 30 as it passes therethrough, now also passes through buffer wall 40 and spreads through-holes 44 to engine interface 26 at a slow flow rate. Thus, the whole or substantially the whole filter chamber 22 can be regenerated by the sorption material 30 correspondingly arranged therein and then used again for the cleaning function of the ventilation device.

The foregoing description of the embodiments describes the invention by way of example only. It is naturally also possible to freely combine the individual features of the embodiments with one another (as far as technically meaningful) without departing from the scope of the invention.

Claims

1. A filter device (10) for a venting device of a fuel tank (100) of a vehicle, having:

a filter housing (20) with a filter chamber (22) filled with an adsorbing material (30) for at least partially adsorbing fuel vapour, wherein the filter housing (20) has a tank interface (24) for fluid communication with the fuel tank (100);

an engine interface (26) for fluid communication with an internal combustion engine (200) of the vehicle; and

a ventilation interface (28) for fluid communication with the environment,

wherein a buffer wall (40) is also arranged in the filter chamber (22) between the tank interface (24) and the engine interface (26) to avoid a direct overflow of fuel vapor from the tank interface (24) into the engine interface (26), and wherein the buffer wall (40) has at least one bore section (42) having a through-bore (44) with a flow resistance against a flow of fuel vapor depending on the flow velocity.

2. The filter device (10) as claimed in claim 1, characterized in that the buffer wall (40) ends with a wall section (21) of the filter housing (20) between the tank connection (24) and the engine connection (26).

3. The filter device (10) according to claim 1 or 2, characterized in that the through-holes (44) of the hole section (42) have a hole diameter which is smaller than the loose porosity of the sorption material (30).

4. The filter device (10) according to claim 1 or 2, wherein the through-holes (44) of the hole section (42) have a hole diameter in the range between 0.5mm and 5 mm.

5. The filter device (10) according to claim 1 or 2, characterized in that the tank interface (24) and the engine interface (26) are arranged opposite the ventilation interface (28).

6. The filtering device (10) according to claim 1 or 2, characterized in that the buffer wall (40) has a length of between 10% and 60% of the corresponding extension of the filter housing (20).

7. The filter device (10) according to claim 1 or 2, characterized in that the buffer wall (40) extends between a first side wall section of the filter housing (20) and a second side wall section of the filter housing (20).

8. The filter device (10) according to claim 1 or 2, characterized in that the buffer wall (40) is arranged either substantially between the tank interface (24) and the engine interface (26).

9. A buffer wall (40) for a filter device (10) according to one of claims 1 to 8, having at least one aperture section (42) with through-openings (44) having a flow resistance, which is dependent on the flow velocity, against the flow through of fuel vapor.