Liquid supply device for a motor vehicle

Abstract

The invention relates to a liquid supply device for a motor vehicle, comprising:-a supply pump for pumping a liquid from a liquid tank to a device for consuming the liquid, and-a filter assembly (7) for filtering the liquid pumped by the supply pump. The filter assembly (7) comprises a housing (8) in which a filter member (9) is housed. The receptacle (8) forms a siphon connected to the suction inlet of the feed pump and comprises an open end opening in the liquid contained in the liquid tank such that the path of the liquid in the siphon passes through a so-called high level, which when the level of the liquid in the liquid tank is below a predetermined threshold, does not pass through the siphon. And the high liquid level is higher than the liquid level of the liquid in the liquid storage tank. The filter member (9) comprises a filter region in the form of a bag of filter material, which filter region extends vertically in the receptacle (8).

Description

Technical Field

[0001] The present invention relates to a liquid supply device for a motor vehicle. The present invention also relates to a liquid tank for a motor vehicle, comprising a liquid supply device according to the present invention. Furthermore, the present invention relates to a selective catalytic reduction device for a motor vehicle, comprising a liquid tank according to the present invention. Finally, the present invention relates to a motor vehicle comprising a liquid tank according to the present invention. Background Art

[0002] Liquid supply devices for vehicles are already known in the prior art, which are used, for example, to inject additive solutions, in particular ammonia precursors, into the exhaust line of an internal combustion engine in order to carry out selective catalytic reduction (also known in English as "Selective Catalytic Reduction", acronym "SCR"). This selective catalytic reduction can reduce the nitrogen oxides (NO X ), thereby reducing the pollution caused by these vehicles to comply with nitrogen oxide emission regulations. Selective catalytic reduction requires the use of a reducing agent, such as ammonia, in precise concentration and high quality. As an additive, an ammonia precursor, such as urea, is usually used, which must be precisely metered and injected into the exhaust gas stream, where it is hydrolyzed and the nitrogen oxides (NO X ) is converted into nitrogen (N2) and water (H2O). To this end, the vehicle must be equipped with a tank with the additive solution and a device for metering and injecting the required amount of additive into the exhaust line.

[0003] In order to avoid that the additive solution injector is blocked by impurities that may be present in the additive solution, it is known to filter the additive solution before injecting it. In the prior art, a filter member is arranged at the inlet of the additive solution feed pump in the additive tank, so that the additive solution can be pumped through the filter member. With this arrangement, the additive solution is cleaned of impurities before being injected into the exhaust line, upstream of the catalyst of the selective catalytic reduction reaction. This also makes it possible to protect the feed pump from the impurities present in the sucked-in additive solution.

[0004] After a period of use, impurities clog the filter. The more and larger the impurities are, the faster the clogging occurs. This is particularly true in areas with severe pollution. When the clogging level increases, the filtering capacity of the filter element decreases and the filtering flow of liquid through the filter element becomes less than the suction flow of the supply pump. As a result, the pump sucks in all or part of the air, which leads to pressure losses in the injection of liquid through the supply pump. This makes it difficult, in particular, to accurately meter the injected additive and thus reduces the efficiency of the selective catalytic reduction. The suction of air is more pronounced when the liquid level in the tank is low, so that part of the filter element is exposed to the air. Summary of the invention

[0005] The invention has for its object in particular to reduce the risk of a loss of liquid injection pressure over time in a liquid supply device of a motor vehicle.

[0006] To this end, the subject matter of the invention relates to a liquid supply device for a motor vehicle, comprising:

[0007] a supply pump for pumping liquid from a liquid storage tank to a device for consuming the liquid, and

[0008] - a filter assembly for filtering liquid pumped by a feed pump, said filter assembly comprising a housing in which a filter member is housed, wherein said housing forms a siphon connected to a suction inlet of the feed pump and comprises an open end opening into the liquid contained in the liquid tank so that the path of the liquid in the siphon passes through a so-called high liquid level which is higher than the level of the liquid in the liquid tank when the level of the liquid in the liquid tank is below a predetermined threshold;

[0009] Characterized in that the filter member comprises a filter area in the form of a bag of filter material extending vertically in the housing forming the siphon.

[0010] Thus, when the feed pump is started, it first sucks in the air present in the housing forming the siphon. This air suction generates a negative pressure which causes the liquid level in the siphon to rise, thereby immersing the filter element in the liquid. Thus, at the end of the start-up phase of the feed pump, the filter element is no longer in contact with air, or at least, even if the liquid level in the liquid tank is below a predetermined threshold, the filter element remains sufficiently immersed to prevent the feed pump from sucking in air during its operation. Furthermore, even when the liquid level in the liquid tank is low, the majority of the filter element remains immersed in the liquid, thereby effectively limiting the clogging effect of the filter element, which results in an obstruction of the passage of the liquid through the filter element.

[0011] Thus, the fact that the feed pump does not suck in air during its operation prevents any instability or pressure loss in the injection of the liquid by the feed pump. This is particularly advantageous in cases where the liquid injected by the pump must be accurately metered, for example in the case where the liquid is an ammonia precursor intended to be injected into the exhaust line of an internal combustion engine in order to be used as an additive in a selective catalytic reduction reaction. The liquid supply device can be used with other liquids, for example with water or fuel.

[0012] It will be appreciated that the liquid supply device according to the invention enables the use of filter members of large dimensions without the risk of reduced injection liquid pressure of the supply pump, since the filter member is no longer in contact with air, or at least remains fully submerged.

[0013] Furthermore, since the air present in the receiving portion is expelled when the supply pump is started, the degree of clogging of the filter element has almost no effect on the liquid filtration flow rate, because the filter element is not in contact with the air and can therefore only filter the liquid. Therefore, the liquid supply device according to the present invention remains functional even when the filter element is severely clogged. As a result, the service life of the filter element is increased, especially in contaminated areas where it is prone to rapid clogging.

[0014] Due to its function, the housing forming the siphon comprises walls that are sealed against air and liquid present in the tank. Thus, the filter element is also protected from possible impurities present in the liquid stored in the liquid tank, thereby increasing the service life of the filter element. In particular, oily residues that may be present in the liquid remain on the surface of the liquid and are therefore blocked by the housing forming the siphon, thereby preventing them from reaching the filter element.

[0015] "Trash" is any foreign matter in the liquid, such as dust, dirt, insects, tank cuttings, oil or solid particles. This foreign matter can be floating, suspended or settled at the bottom of the liquid tank.

[0016] Within the limits of the minimum filling level, the liquid allows the filter element to be largely immersed in the liquid, regardless of the filling level of the tank, by passing through a so-called high level.

[0017] The predetermined threshold corresponds, for example, to a liquid level in the liquid tank at which at least a portion of the housing forming the siphon is no longer immersed. Preferably, the predetermined threshold corresponds to a liquid level in the housing forming the siphon at which the filter member is no longer in contact with air. It is therefore understood that the filter member is still sufficiently immersed in the liquid even when the liquid level in the tank is below a so-called high level inside the housing.

[0018] It is understood that the "bag" comprises at least one wall defining a cavity which is open at one of its ends and closed at the other of its ends to form the bottom of the bag. According to the present invention, it is understood that the wall of the bag is made of a filter material and that the liquid can be filtered through the wall towards the interior of the bag.

[0019] Since the filter area in the form of the bag extends vertically in the receptacle, when the bag is completely immersed in the liquid, for example once the pump has been started and the air has been expelled from the receptacle, the available filter surface is optimized, since all faces of the bag over its entire height and width can be used to filter the liquid that has not yet been filtered. Thus, a particularly compact filter assembly can be provided and thus a liquid supply device that is also more compact in itself.

[0020] The present invention may also include one or more of the following optional features, taken alone or in combination.

[0021] Ratio V / h at 400mm 2 Up to 800mm 2 Where V is the volume of the filter element and h is the height of the filter element, preferably, the ratio V / h is approximately equal to 600 mm 2 . This ratio can represent the filtering area of ​​the filter element. Such a filter element has good filtering performance. The provision of a housing forming a siphon advantageously allows the use of such a filter element. In fact, a filter element with these dimensions has good filtering performance, but with the liquid supply device of the prior art, due to its large volume, it is easy to fill with air, thus creating a significant risk of loss of liquid injection pressure. The liquid supply device according to the invention allows the air to be discharged outside the housing forming the siphon during perfusion, so that such a filter element can be used without creating this risk.

[0022] The liquid supply device also comprises a supply conduit extending vertically in the bag between the high point and the low point of the bag, the upper first end of the supply conduit being connected to the suction inlet of the supply pump and the lower second end opening inside the bag. This is a simple device that facilitates pumping, in particular by allowing liquid suction to be performed near the liquid level in the housing forming the siphon.

[0023] Preferably, the distance Δ between the lower second end of the supply duct and the bottom of the bag is between 10% and 90% of the bag's height p, preferably the distance Δ is approximately equal to 25% of the bag's height p. Such positioning of the lower second end of the supply duct makes it possible to optimize the suction of liquid by the supply pump through the supply duct, both during priming of the pump and during subsequent suctioning.

[0024] The bag comprises at least two lateral filter surfaces, each of which is arranged facing the wall of the accommodation portion and spaced apart from the wall of the accommodation portion. The surface available for filtering is thus optimized. In fact, it is understood that in this arrangement, the lateral filter surfaces are not in contact with the wall of the accommodation portion and can therefore be in direct contact with the liquid that has not yet been filtered. Therefore, the liquid can enter the bag not only through the bottom of the bag, but also through the lateral filter surfaces. Thereby, the filter area of ​​the filter member is increased. According to an embodiment, the number of sides can be different, for example between two and six.

[0025] The liquid supply device comprises heating means for heating the housing forming the siphon. Thus, liquid that may be frozen in the housing forming the siphon can be thawed so as to be able to use the liquid supply device. It should be noted that the heating means only need to heat a certain volume of liquid present in the housing forming the siphon. Since this volume is relatively small, it facilitates the thawing of the liquid present therein.

[0026] The feed pump is accommodated in a housing, and the filter assembly is arranged outside the housing and carried by the housing. The housing allows the different functional units of the liquid supply device to be combined together and connected to each other in a simple and effective manner. Therefore, the manufacture of the liquid supply device is simpler and allows a compact liquid supply device to be obtained.

[0027] Preferably, the liquid supply device also includes a fixing device for removably fixing the filter assembly to the housing. Therefore, it is convenient for the maintenance of the liquid supply device. In fact, it is easy to separate the filter assembly from the housing, so as to, for example, check the state of the filter member, in particular its clogging level. Therefore, it is also easy to replace the filter member when necessary. In particular, the filter member can be replaced without having to operate the rest of the liquid supply device, in particular the supply pump. This reduces the risk of wear of the rest of the power supply device, thereby increasing its service life. The detachable (removable) fixing device may include any device known to those skilled in the art, which allows the filter assembly to be connected and separated from the housing in a simple and fast manner. Preferably, these detachable fixing devices do not require the use of tools to fix the filter assembly to the housing or to separate the filter assembly from the housing. For example, the detachable fixing device is a device that is fixed by clamping or screwing, which allows the filter assembly to be directly clamped or screwed onto the housing. The term "screwing fixing" is used here to indicate that the filter assembly includes a thread complementary to the thread on the housing, so that the filter assembly can be directly screwed onto the housing. Preferably, the thread of the filter assembly and the thread of the housing form a quarter-turn screw type fixing device, so that the filter assembly can be fixed to the housing and separated from the housing by applying a quarter-turn (i.e. 90°) rotation to the filter assembly. Therefore, even in the case of small available space, the fixing and removal of the filter assembly are particularly easy.

[0028] The liquid is an aqueous solution, preferably an ammonia precursor. In case the liquid is an ammonia precursor, the liquid supply device can be advantageously used in the context of a selective catalytic reduction reaction to purify exhaust gases of an internal combustion engine. According to another embodiment, the aqueous solution is water.

[0029] The invention also relates to a liquid tank for a motor vehicle, which is equipped with a liquid supply device as described above. Thus, according to an embodiment, the tank can be, for example, a liquid tank for an aqueous solution (such as water or urea) or a fuel tank. The tank can be made of any material. In the specific case of a urea solution tank, the material of the tank is preferably a material with good chemical resistance to urea. It is typically a plastic material. Polyolefins, in particular polyethylene, more particularly high-density polyethylene (PEHD), constitute the preferred material. The tank can be made by any known processing method. A known embodiment is the injection molding method. A preferred embodiment is the extrusion blow molding method. In this method, a parison - consisting of one or more parts - is obtained by extrusion and then blow-molded in a mold. An integrally molded tank molded from a single-component parison gives good results.

[0030] The invention also relates to a selective catalytic reduction device for purifying exhaust gases of an internal combustion engine of a motor vehicle, the selective catalytic reduction device comprising a liquid tank as described above, wherein the liquid is an ammonia precursor. The ammonia precursor is, for example, urea. The catalytic reduction device is thus improved because it is equipped with a liquid supply device according to the invention, which makes it possible to reduce the risk of a loss of injection pressure of the ammonia precursor over time. This is particularly advantageous because, as mentioned above, it is important to accurately meter the ammonia precursor injected during selective catalytic reduction, and a loss of injection pressure of the ammonia precursor is detrimental to the accuracy of this metering.

[0031] Finally, the invention also relates to a motor vehicle comprising a liquid tank as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention will be better understood by reading the following description, given purely as a non-limiting example and with reference to the accompanying drawings, in which:

[0033] Figure 1 is a schematic diagram of a vehicle comprising a tank equipped with a liquid supply device according to the present invention;

[0034] Figure 2 yes Figure 1 A perspective view of a liquid supply device;

[0035] Figure 3 yes Figure 1 a cross-sectional view of a portion of a liquid supply device;

[0036] Figure 4 is formed Figure 1 a perspective view of a filter assembly of a portion of a liquid supply device;

[0037] Figure 5 yes Figure 4 A front view of a portion of a filter assembly;

[0038] Figure 6 yes Figure 5 a longitudinal cross-sectional view of a portion of the filter assembly shown; and

[0039] Figure 7 yes Figure 1 Schematic diagram of the operation of the liquid supply device. DETAILED DESCRIPTION

[0040] Figures 1 to 7 An embodiment of a liquid supply device 1 for a liquid 2 according to the invention is shown. In this case, the liquid supply device 1 for a liquid 2 is mounted on the lower wall of a liquid tank 3, which is itself mounted on a motor vehicle 4 ( Figure 1 )superior.

[0041] In this case, the liquid is a precursor of ammonia, such as urea. The liquid tank 3 and the liquid supply 1 thus form part of a selective catalytic reduction device 18 intended to purify exhaust gases of an internal combustion engine (not shown) of a motor vehicle 4 .

[0042] The material from which the liquid tank 3 is made is preferably a material having good chemical resistance to urea. It is generally a plastic material. Polyolefins, in particular polyethylene, more particularly high-density polyethylene (PEHD), constitute the preferred material. The tank can be made by any known processing method. A known embodiment is the injection molding method. A preferred embodiment is the extrusion blow molding method. In this method, a parison - consisting of one or more parts - is obtained by extrusion and then formed by blow molding in a mold. An integrally molded tank molded from a single-component parison gives good results.

[0043] The liquid supply device 1 of the liquid 2 specifically comprises a housing 5, a supply pump 6 and a filter assembly 7 ( Figure 2 , Figure 3 , Figure 4 and Figure 7 ).

[0044] The housing 5 forms a support member for the different functional units of the liquid supply device 1 for the liquid 2. In this case, the feed pump 6 is accommodated inside the housing 5, and the filter assembly 7 is arranged outside the housing 5 and carried by the housing 5 ( Figure 2 ). More specifically, the liquid supply device 1 for the liquid 2 includes a device (not shown) for detachably fixing the filter assembly to the housing 5. Preferably, these detachable fixing means do not require the use of tools to connect or separate the filter assembly 7 from the housing 5. For example, the detachable fixing means is a device for fixing by clamping or screwing, which allows the filter assembly 7 to be directly clamped or screwed to the housing 5.

[0045] The other functional units of the liquid supply device 1 for liquid 2 are conventional and are not shown for the sake of clarity. The housing 5 may be made of any material having a good chemical resistance to urea. For example, the housing 5 is made of a thermoplastic material.

[0046] The feed pump 6 is used to pump liquid from the liquid tank 3 to a device (not shown) for consuming the liquid. In this case, the liquid is a precursor of ammonia and the device for consuming the liquid is a catalyst for a selective catalytic reduction reaction. It is understood that the liquid consuming device varies according to the desired use of the liquid supply device 1 for the liquid 2 and more specifically according to the nature of the liquid 2 contained in the liquid tank 3. The feed pump 6 used is known per se and will not be described in detail here. It is understood that the feed pump 6 may in particular correspond to a feed pump 6 commonly used for injecting an ammonia precursor in the context of a selective catalytic reduction reaction in a motor vehicle 4.

[0047] The filter assembly 7 is intended to filter the liquid 2 pumped by the feed pump 6 to ensure that the liquid 2 injected into the selective catalytic reduction reaction is substantially free of impurities. The filter assembly 7 particularly comprises a filter member 9 ( Figure 4 )'s accommodation portion 8.

[0048] The housing 8 has a substantially parallelepiped shape with a closed first longitudinal end and an open (open) second longitudinal end opposite the first longitudinal end. In this case, the housing 8 is formed of two parts: a first part forms the body 10 of the housing 8, and a second part forms a closure cover 11, which closes the first longitudinal end of the housing 8 in a sealed manner to the air and the liquid 2 present in the liquid tank 3. Alternatively, the housing 8 can be manufactured so that the body 10 and the closure cover 11 are integral.

[0049] The housing 8 forms a siphon which is connected at a closed first longitudinal end of the feed pump 6 via a feed duct 13 to a suction inlet 12 of the feed pump 6. The open second longitudinal end of the housing 8 forming the siphon opens in the liquid 2 contained in the liquid tank 3 so that the path of this liquid 2 in the siphon passes through a so-called high level which is higher than the level of the liquid 2 in the liquid tank 3 when the level of the liquid 2 in the liquid tank 3 is below a predetermined threshold value (see Figure 7 ). For example, the predetermined threshold value may be located approximately at the open first longitudinal end of the siphon-forming housing 8. Preferably, the predetermined threshold value corresponds to the level of the liquid in the siphon-forming housing 8 at which the filter member 9 is immersed in the liquid 2.

[0050] The filter member 9 is made of a flexible filter screen fixed on a rigid frame. The filter screen is flexible and, for example, is wound above or below the rigid frame. Advantageously, the filter screen and the rigid frame are made of thermoplastic material and are welded to each other. Alternatively, the flexible filter screen is manufactured integrally with the rigid frame ( Figure 5 and Figure 6 ).

[0051] The filter member 9 comprises a filter area extending vertically in the housing 8 forming the siphon. In other words, the filter member 9 is arranged vertically in the housing 8, and the housing 8 is also arranged vertically when mounted on the housing 5 ( Figure 2 , 3 and 7). More specifically, the filter area of ​​the filter member 9 comprises pockets 14 of filter material formed by a filter mesh.

[0052] The bag 14 comprises at least one wall defining a cavity open at one of its ends and closed at the other of its ends to form the bottom of the bag. In this case, the opening of the bag 14 allows the passage of the supply duct 13. According to this embodiment, the bag 14 comprises two lateral filtering surfaces 19, 20, each of which is arranged facing the wall of the housing 8 and is spaced apart from it ( Figure 3 and Figure 7 ).

[0053] In the present case, the ratio V / h is between 400 mm2 and 800 mm2, where V is the volume of the filter element 9 and h is the height of the filter element 9. Preferably, the ratio V / h is approximately equal to 600 mm2. In the present embodiment, the filter bag 14 has a height p of approximately 68 mm, which is slightly less than the height h of the filter element ( Figure 5 ).

[0054] The supply conduit 13 has an overall shape of an inverted "L" and extends vertically in the bag 14 between the high point and the low point of the bag 14. The upper first end 15 of the supply conduit 13 is connected to the suction inlet 12 of the supply pump 6, and thus the interior of the siphon-forming receiving portion 8 is in fluid communication with the suction inlet 12 of the supply pump 6 ( Figure 3 and Figure 7 The lower second end 16 of the supply conduit 13 opens inside the bag 14 ( Figure 5 and Figure 6). According to different embodiments, the height position of the opening of the lower second end 16 of the supply duct 13 in the bag 14 varies. In the present case and advantageously, the distance Δ between the lower second end 16 of the supply duct 13 and the bottom of the bag 14 is about 15.5 mm, which corresponds to about 23% of the height p of the bag 14. Advantageously, the distance Δ between the lower second end 16 of the supply duct 13 and the bottom of the bag 14 is between 10% and 90% of the height of the bag, preferably, the distance Δ is approximately equal to 25% of the height of the bag.

[0055] The liquid supply device 1 further comprises heating means 17 for heating the housing 8 forming the siphon. In this case, these heating means 17 are formed by a heating layer which partially covers the housing 8 forming the siphon. According to other embodiments, any heating means which can be arranged in the liquid tank 3 for the liquid 2 in order to heat the housing 8 forming the siphon can be used. For the sake of clarity, the heating means 17 are only shown in FIG. Figure 3 Shown above.

[0056] Please refer to the following Figure 7 An example of the operation of the liquid supply device 1 for supplying the liquid 2 according to the present invention is described.

[0057] As mentioned above, the liquid supply device 1 for supplying the liquid 2 is used in the present case for a selective catalytic reduction reaction, so that the liquid 2 (in this case an ammonia precursor) is injected into the exhaust gas stream of the motor vehicle 4, in which the liquid 2 is hydrolyzed to convert nitrogen oxides (NO X ) is converted into nitrogen (N2) and water (H2O).

[0058] Figure 7 A shows the state of the liquid supply device 1 for liquid 2 before its use, i.e., before starting the supply pump 6. Here, the liquid level of the liquid 2 in the liquid storage tank 3 is relatively low, so that most of the filter assembly 7, especially most of the receiving portion 8 forming the siphon, is not immersed in the liquid 2. Air exists in the receiving portion 8 forming the siphon.

[0059] When it is necessary to inject liquid 2 into the exhaust gas flow, the supply pump 6 is activated. During the first activation step, the supply pump 6 sucks the mixture of air and liquid 2 present in the siphon-forming receptacle 8 via its suction inlet 12 and along the supply conduit 13. The suction of air generates a negative pressure which causes the level of the liquid 2 in the siphon-forming receptacle 8 to increase ( Figure 7 B).

[0060] At the end of the start-up period, all or most of the air present in the siphon-forming housing 8 is sucked in by the supply pump 6, so that the siphon-forming housing 8 is filled with liquid 2 until the filter member 9 is at least completely or almost completely immersed. Figure 7C). It should be noted that the liquid level of the liquid 2 in the receiving portion 8 forming the siphon is higher than the liquid level of the liquid 2 stored in the liquid storage tank 3 for the liquid 2. The filter member 9 is then immersed in the liquid and is not in contact with the air. At this stage, the supply pump 6 therefore no longer or almost no longer inhales air. Therefore, the risk of loss of injection pressure of the liquid 2 is reduced or even zero. In addition, regardless of the degree of clogging of the filter member 9, the immersion of the filter member 9 can be obtained after the pump is started. Therefore, even if the filter member 9 is severely clogged, the filter member 9 can continue to be used together with the liquid supply device 1 for the liquid 2 according to the present invention, because the air has been discharged from the receiving portion 8 forming the siphon, and in any case it will no longer be sucked by the supply pump 6 and thus cause the injection pressure of the liquid 2 to drop.

[0061] Example

[0062] The following describes the test results for measuring the efficiency of the liquid supply device 1 of the liquid 2 according to the present invention according to the clogging level of the filter member 9. Therefore, the clogging level of the filter member 9 tested is expressed as 0% (reference), 10%, 20%, 30%, 40% and 50% as a percentage of the height h of the filter member 9. In order to control the clogging level, the clogging level is artificially achieved by covering the filter member 9 with epoxy resin at a height corresponding to the desired clogging level percentage starting from the lower end of the filter member 9. The efficiency of the liquid supply device 1 of the liquid 2 according to the present invention is tested by measuring the amount of aqueous solution, in this case, the aqueous solution is urea. The aqueous solution can be injected using only the filter member 9 alone, as in the prior art; or the filter member 9 is accommodated in the accommodating portion 8 forming the siphon of the filter assembly 7 according to the present invention. The test results are shown in Table 1.

[0063] [Table 1]

[0064]

[0065]

[0066] The volume of urea is measured in kilograms instead of in litres for ease of measurement. Alternatively, the test can be performed by measuring the volume of urea in litres. According to the test, 5 kg of urea are injected using a liquid supply device 1 for a liquid 2 comprising either a separate filter member (representing the state of the art) or a filter assembly 7 according to the invention, wherein the filter member 9 is housed in a housing 8 forming a siphon.

[0067] Only the case of a clogging level of 0% was tested on the prior art liquid supply device in order to give a reference value. Thus, in the prior art, using a filter member which is usually not clogged because it is new, the volume of urea injected from 5 kg of urea is 4.821 kg.

[0068] In the case of a 10% blockage of the filter element 9, a reduction in the injected urea is observed for the liquid supply device of the prior art. The volume of injected urea is 4.540 kg, instead of 4.821 kg when the filter element 9 is not blocked, i.e. a loss of 0.281 kg of urea. We note that the above-mentioned reduction loss does not occur in this case, since the liquid supply device 1 for liquid 2 according to the invention injects 4.824 kg of urea. Therefore, compared with the reference example, the volume of injected urea even increases slightly (by 0.003 kg). Therefore, the filtering capacity of the filter assembly 7 according to the invention is superior to that of the prior art and is able to always maintain a filtering level that is substantially equal to the filtering level obtained when the filter element 9 is new.

[0069] In the case of a 20% blockage of the filter element 9, a reduction in the volume of urea injected is again observed for the liquid supply device of the prior art. The volume of urea injected is 4.459 kg, instead of 4.821 kg when the filter element 9 is not blocked, i.e. a loss of 0.362 kg of urea. It is again noted that for the liquid supply device 1 for supplying liquid 2 according to the invention, this reduction loss is not visible, since 4.844 kg of urea has been injected. Therefore, the volume of urea injected is also slightly increased (by 0.023 kg) compared to the reference example. Therefore, the filtering capacity of the filter assembly 7 according to the invention is superior to that of the prior art and is able to maintain a filtering level substantially equal to the filtering level obtained when the filter element 9 is new.

[0070] In the case of a 30% blockage of the filter element 9, a reduction in the volume of urea injected is again observed for the liquid supply device of the prior art. The volume of urea injected is 3.685 kg, instead of 4.821 kg when the filter element 9 is not blocked, i.e. a loss of 1.136 kg of urea. It is again noted that for the liquid supply device 1 of the liquid 2 according to the invention, this reduction loss is not visible, since 4.821 kg of urea have been injected, i.e. as much as a new filter element 9. Therefore, the filtering capacity of the filter assembly 7 according to the invention is superior to that of the prior art and is able to maintain a filtering level substantially equal to that obtained when the filter element 9 is new.

[0071] In the case of a 40% blockage of the filter member 9, a reduction in the volume of urea injected is again observed for the liquid supply device of the prior art. The volume of urea injected is 3.343 kg, instead of 4.821 kg when the filter member 9 is not blocked, i.e. 1.478 kg of urea is lost. It should be noted that for the liquid supply device 1 for liquid 2 according to the invention, this reduction is not very significant, since 4.810 kg of urea have been injected, i.e. only 0.011 kg of urea is lost. Therefore, the filtering capacity of the filter assembly 7 according to the invention is superior to that of the prior art and is able to maintain a filtering level substantially equal to that obtained when the filter member 9 is new.

[0072] In the case of 50% blockage of the filter element 9, a reduction in the volume of urea injected is again observed for the liquid supply device of the prior art. The volume of urea injected is 3.247 kg, instead of 4.821 kg when the filter element 9 is not blocked, i.e. a loss of 1.574 kg of urea. It is again noted that there is no such reduction loss for the liquid supply device 1 for liquid 2 according to the invention, since 4.841 kg of urea are injected, i.e. an increase of 0.020 kg of urea compared to the reference example. Therefore, the filtering capacity of the filter assembly 7 according to the invention is superior to that of the prior art and is able to maintain a filtering level substantially equal to that obtained when the filter element 9 is new.

[0073] This test allows conclusions to be drawn about the filtering efficiency of the filter member 9 over time, i.e. as it becomes clogged. The loss of filtering efficiency of the prior art filter member in fact corresponds to an increased risk of injection pressure loss during use of the liquid supply device 1 for liquid 2. As previously mentioned, such a loss of injection pressure is disadvantageous, in particular in cases where the amount of liquid 2 to be injected must be precisely metered, since it does not allow an acceptable level of precision to be obtained for the amount of liquid 2 injected. Thus, this test shows that the use of the liquid supply device 1 for liquid 2 according to the invention allows the filtering capacity of the filter member 9 to be maintained over time, even in the event of severe clogging, and thus reduces the risk of loss of injection pressure of the liquid 2 over time.

[0074] The invention is not limited to the embodiments presented and other embodiments will be apparent to those skilled in the art.

[0075] List of Reference Numerals

[0076] 1: Liquid supply device

[0077] 2: Liquid

[0078] 3: Storage tank

[0079] 4: Motor Vehicles

[0080] 5: Shell

[0081] 6: Supply pump

[0082] 7: Filter components

[0083] 8: Accommodation

[0084] 9: Filter component

[0085] 10: Container body

[0086] 11: Sealing cover of the receiving part

[0087] 12: Suction inlet of the supply pump

[0088] 13: Supply duct

[0089] 14: Bags for filter elements

[0090] 15: Upper first end of the supply conduit

[0091] 16: The lower second end of the supply conduit

[0092] 17: Heating device for the receiving portion forming the siphon

[0093] 18: Selective Catalytic Reduction Device

[0094] 19, 20: Lateral filter surface

[0095] h: Height of the filter element

[0096] p: Height of filter bag

[0097] Δ: distance between the lower second end of the supply conduit and the bottom of the bag

Claims

1. A liquid supply device (1) for a liquid (2) for a motor vehicle (4), comprising: a supply pump (6) for pumping the liquid (2) from the liquid storage tank (3) to a device for consuming the liquid (2), and - a filter assembly (7) for filtering the liquid (2) pumped by the supply pump (6), the filter assembly (7) comprising a receiving portion (8) receiving a filter member (9), wherein the housing (8) forms a siphon connected to the suction inlet (12) of the supply pump (6) and comprises an open end which opens into the liquid (2) contained in the liquid storage tank (3) so that the path of the liquid (2) in the siphon passes through a so-called high liquid level which is higher than the liquid level of the liquid (2) in the liquid storage tank (3) when the liquid level of the liquid (2) in the liquid storage tank (3) is below a predetermined threshold value; Characterized in that the filter member (9) comprises a filter area in the form of a bag (14) of filter material which extends vertically in the housing (8) forming a siphon.

2. The liquid supply device (1) for liquid (2) according to claim 1, wherein: Ratio V / h at 400mm 2 Up to 800mm 2 Wherein V is the volume of the filter element (9), h is the height of the filter element (9), preferably, the ratio V / h is approximately equal to 600 mm 2 .

3. The liquid supply device (1) according to claim 1 or 2, wherein: The liquid supply device (1) for the liquid (2) further comprises a supply conduit (13), which extends vertically in the bag (14) between a high point and a low point of the bag (14), an upper first end (15) of the supply conduit (13) being connected to a suction inlet (10) of the supply pump (6), and a lower second end (16) opening inside the bag (14).

4. The liquid supply device (1) according to claim 3, wherein: The distance (Δ) between the lower second end (16) of the supply conduit (13) and the bottom of the bag (14) is between 10% and 90% of the height (p) of the bag (14), preferably, the distance (Δ) is equal to about 25% of the height (p) of the bag (14).

5. A liquid supply device (1) for a liquid (2) according to any one of the preceding claims, wherein: The bag (14) comprises at least two lateral filter surfaces (19, 20), each lateral filter surface being arranged facing the wall of the housing (8) and being spaced apart from the wall of the housing (8).

6. Liquid supply device (1) for a liquid (2) according to any of the preceding claims, comprising heating means (17) for heating the receptacle (8) forming a siphon.

7. A liquid supply device (1) for a liquid (2) according to any one of the preceding claims, wherein: The feed pump (6) is accommodated in a housing (5), and the filter assembly (7) is arranged outside the housing (5) and is carried by the housing (5).

8. The liquid supply device (1) for liquid (2) according to claim 7, further comprising a fixing device for detachably fixing the filter assembly (7) to the housing (5).

9. A liquid supply device (1) for a liquid (2) according to any one of the preceding claims, wherein: The liquid (2) is an aqueous solution, preferably an ammonia precursor.

10. A liquid tank (1) for a liquid (2) for a motor vehicle (4), characterized in that It is equipped with a liquid supply (1) for a liquid (2) according to any one of the preceding claims.

11. A selective catalytic reduction device (18) for purifying exhaust gases from an internal combustion engine of a motor vehicle, characterized in that: The selective catalytic reduction device comprises a liquid tank (3) for a liquid (2) according to claim 10, wherein the liquid (2) is an ammonia precursor.

12. A motor vehicle (4), characterized in that It comprises a liquid tank (3) for a liquid (2) according to claim 10.

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